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Journal articles on the topic 'Reference speed'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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1

Kantor, Sarah. "Reference speed dating: Creating a spark at the reference desk." College & Research Libraries News 81, no. 2 (February 4, 2020): 80. http://dx.doi.org/10.5860/crln.81.2.80.

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Reference services, whether face-to-face or virtual, have been and remain a core library service. The importance of reference services is reflected in the library and information science (LIS) curriculum, but it is often overlooked in continuing education opportunities for librarians. In both master’s degree programs and the few continuing education offerings for reference services, instructors generally focus on the reference interview. For many working librarians, this can feel rote and ineffectual. After all, they already learned this in school. Experienced librarians may also feel that the reference interview is old hat, while newer librarians would benefit more from real-world practice than a repeat of their reference class.

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Adiputra, Dimas, Mohd Azizi Abdul Rahman, Ubaidillah, Saiful Amri Mazlan, Nurhazimah Nazmi, Muhammad Kashfi Shabdin, Jun Kobayashi, and Mohd Hatta Mohammed Ariff. "Control Reference Parameter for Stance Assistance Using a Passive Controlled Ankle Foot Orthosis—A Preliminary Study." Applied Sciences 9, no. 20 (October 18, 2019): 4416. http://dx.doi.org/10.3390/app9204416.

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This paper aims to present a preliminary study of control reference parameters for stance assistance among different subjects and walking speeds using a passive-controlled ankle foot orthosis. Four young male able-bodied subjects with varying body mass indexes (23.842 ± 4.827) walked in three walking speeds of 1, 3, and 5 km/h. Two control references, average ankle torque (aMa), and ankle angular velocity (aω), which can be implemented using a magnetorheological brake, were measured. Regression analysis was conducted to identify suitable control references in the three different phases of the stance. The results showed that aω has greater correlation (p) with body mass index and walking speed compared to aMa in the whole stance phase (p1(aω) = 0.666 > p1(aMa) = 0.560, p2(aω) = 0.837 > p2(aMa) = 0.277, and p3(aω) = 0.839 > p3(aMa) = 0.369). The estimation standard error (Se) of the aMa was found to be generally higher than of aω (Se1(aMa) = 2.251 > Se1(aω) = 0.786, Se2(aMa) = 1.236 > Se2(aω) = 0.231, Se3(aMa) = 0.696 < Se3(aω) = 0.755). Future studies should perform aω estimation based on body mass index and walking speed, as suggested by the higher correlation and lower standard error as compared to aMa. The number of subjects and walking speed scenarios should also be increased to reduce the standard error of control reference parameters estimation.

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Wicaksono, Nanda Avianto, Abdul Halim, Aries Subiantoro, and Feri Yusivar. "Critical Condition of Sensorless Induction Generator Using Flux Weakening in Wind Turbine Application." International Journal of Power Electronics and Drive Systems (IJPEDS) 7, no. 1 (March 1, 2016): 202. http://dx.doi.org/10.11591/ijpeds.v7.i1.pp202-216.

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This paper was intended to examine thoroughly a critical condition of the sensorless induction generator using flux weakening in wind turbine application. The critical condition would happen when the rotor speed reached the critical rotor speed reference. The critical rotor speed reference was the highest of the rotor speed reference that still caused the stable response. It was obtained by increasing the rotor speed reference until the system response became unstable. In the low speed range of wind showed that there was no unstable condition whatever a rotor speed reference was set. On the other hand, there was a critical rotor speed reference in the medium and high speed range of wind. The unstable condition was caused by the induction generator that received a power higher than its capacity, so its rotor speed couldn't be maintained at reference value. The first solution was suggested that the stable condition would be made by setting the rotor speed reference at the minimum critical reference. The second solution was suggested that the controlling rotor speed in triangle area between the critical condition and the operation that used the minimum critical reference for the rotor speed reference. In the triangle area, the rotor speed was controlled by setting the tip speed ratio.

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4

Amichai, Eran, and Yossi Yovel. "Echolocating bats rely on an innate speed-of-sound reference." Proceedings of the National Academy of Sciences 118, no. 19 (May 3, 2021): e2024352118. http://dx.doi.org/10.1073/pnas.2024352118.

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Animals must encode fundamental physical relationships in their brains. A heron plunging its head underwater to skewer a fish must correct for light refraction, an archerfish shooting down an insect must “consider” gravity, and an echolocating bat that is attacking prey must account for the speed of sound in order to assess its distance. Do animals learn these relations or are they encoded innately and can they adjust them as adults are all open questions. We addressed this question by shifting the speed of sound and assessing the sensory behavior of a bat species that naturally experiences different speeds of sound. We found that both newborn pups and adults are unable to adjust to this shift, suggesting that the speed of sound is innately encoded in the bat brain. Moreover, our results suggest that bats encode the world in terms of time and do not translate time into distance. Our results shed light on the evolution of innate and flexible sensory perception.

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Wang, Hsiu Ping, Yu Feng Chang, and Fwu Hsing Liu. "Modified MRAS Speed Controller for Direct Torque Controlled Sensorless Induction Motor Drives." Applied Mechanics and Materials 423-426 (September 2013): 2059–62. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.2059.

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This paper presents a Modified model reference adaptive system (MMRAS) speed controller for speed estimation of induction motor using model-reference adaptive scheme (MRAS) approach in a direct torque control system. A good speed controller of induction motor can enhance the speed estimation of sensorless drives. The MMRAS controller can reduce effect of parameter variations and nonlinearities in the induction motor, and approaches to desired performance of referenced model. So, the presented controller can enhance the performance of speed estimation. The availability of the proposed structure scheme is verified by through under computation simulations with MATLAB software. Simulation results are presented in order to prove the availability of the proposed structure scheme.

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Sharaf, Soliman M., and Mohamed I. Mahmoud. "Reference Speed Tracking Control for DC Motor Drives." EPE Journal 3, no. 3 (September 1993): 179–83. http://dx.doi.org/10.1080/09398368.1993.11463324.

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7

Zhiping, Yang, Yue Qiuqin, and Ye yong. "Induction Motor Speed Control Based on Model Reference." Procedia Engineering 29 (2012): 2376–81. http://dx.doi.org/10.1016/j.proeng.2012.01.318.

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8

H. Mark, Harry. "Speed of Light, the Vanished Points of Reference." Optics 3, no. 2 (2014): 12. http://dx.doi.org/10.11648/j.optics.20140302.11.

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9

Prachar, Ales. "Local low speed preconditioning in rotating reference frame." Applied Mathematical Sciences 9 (2015): 209–18. http://dx.doi.org/10.12988/ams.2015.411885.

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10

Hwang, Paul A. "Drag Coefficient, Dynamic Roughness and Reference Wind Speed." Journal of Oceanography 61, no. 3 (June 2005): 399–413. http://dx.doi.org/10.1007/s10872-005-0050-2.

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11

Eremenko, V. S., V. P. Babak, and A. O. Zaporozhets. "METHOD OF REFERENCE SIGNALS CREATING IN NON-DESTRUCTIVE TESTING BASED ON LOW-SPEED IMPACT." Tekhnichna Elektrodynamika 2021, no. 4 (June 17, 2021): 70–82. http://dx.doi.org/10.15407/techned2021.04.070.

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The article describes the approach to the formation of a simulation model of information signals, which are typical for objects with different types of defects. The dispersive analysis of the signal spectrum components in the bases of the discrete Hartley transform and the discrete cosine transform is carried out. The analysis of the form of the reconstructed information signal is carried out depending on the number of coefficients of the spectral alignment in Hartley bases and cosine functions. The basis of orthogonal functions of a discrete argument is obtained, which can be used for the spectral transformation of information signals of a flaw detector. A method of simulation of information signals has been developed and experimentally investigated, which allows taking into account the deterministic and random components of the characteristics of real information signals. References 24, figures 13, tables 3.

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12

Peng, Hao, and Ze Lun Li. "A Method of Measuring Rotational Speed for a High-Speed Rotator Based on DSP." Applied Mechanics and Materials 233 (November 2012): 270–73. http://dx.doi.org/10.4028/www.scientific.net/amm.233.270.

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Requirements for the device of measuring rotational speed is high-accuracy, stabilization, credibility, and shorter measuring time during the dynamic-balancing process. This paper studies a way of measuring rotator reference signal based on DSP(digital signal processing). The way of picking-up rotator reference signal, measuring rotator speed are introduced. This new way of measuring rotational speed in high-speed rotor dynamic-balancing measuring system based on DSP is accurate, simple and convenient.

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13

Davies, Kenneth William. "Measuring the One-Way Speed of Light." Applied Physics Research 10, no. 6 (November 30, 2018): 45. http://dx.doi.org/10.5539/apr.v10n6p45.

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This paper describes a method for determining the one-way speed of light. My thesis is that the one-way speed of light is NOT constant in a moving frame of reference, and that the one-way speed of light in any moving frame of reference is anisotropic, in that its one-way measured speed varies depending on the direction of travel of light relative to the direction of travel and velocity of the moving frame of reference. Using the disclosed method for measuring the one-way speed of light, a method is proposed for how to use this knowledge to synchronize clocks, and how to calculate the absolute velocity and direction of movement of a moving frame of reference through absolute spacetime using the measured one-way speed of light as the only point of reference.

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14

Fan, Bo, Zhi-Xin Yang, Xian-Bo Wang, Lu Song, and Shu-Zhong Song. "Model reference adaptive vector control for induction motor without speed sensor." Advances in Mechanical Engineering 9, no. 1 (January 2017): 168781401668308. http://dx.doi.org/10.1177/1687814016683086.

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The wide applications of vector control improve the high-accuracy performance of alternating current (AC) adjustable speed system. In order to obverse the full-order flux and calculate the real-time speed, this article introduces the motor T equivalent circuit to build a full-order flux observer model, where the current and flux variables of stator and rotor are adopted. Model reference adaptive control is introduced to build the AC motor flux observer. The current output is used as feedback to build the feedback matrix. The calculation method of motor speed, which is part of the inputs of flux observation, is applied to realize the adaptive control. The concept of characteristic function is introduced to calculate the flux, of which the foundation is the variables of composite form of voltage and current models. The characteristic function is deduced as a relative-state variable function. The feedback matrix is improved and designed to ensure the motor flux observer is a smooth switch between current and voltage model in low and high speeds, respectively. Experimental results show that the feedback and characteristic model are feasible, and the vector control with speed sensorless based on the full-order flux observer has better performance and anti-disturbance.

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15

Bae, Jong-Nam, Grace Firsta Lukman, Jin-Woo Ahn, and Dong-Hee Lee. "Variable speed reference control of a high-speed BLDC motor for a blender machine." IET Electric Power Applications 14, no. 11 (November 1, 2020): 2154–62. http://dx.doi.org/10.1049/iet-epa.2020.0078.

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Lutonin, Aleksandr, Andrey Shklyarskiy, and Yaroslav Shklyarskiy. "Operation modes and control algorithms of anisotropic permanent magnet synchronous motor (IPMSM)." E3S Web of Conferences 140 (2019): 10006. http://dx.doi.org/10.1051/e3sconf/201914010006.

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This paper represents control strategy of anisotropic permanent magnet synchronous motor (IPMSM) in the field-weakening region. Field weakening controller allows to increase maximum achievable speed with output torque reduction. Proposed control system consists of four general modes: MTPA (maximum torque per ampere), MC (maximum current), FW (field weakening), and MTPV (maximum torque per voltage) which must be chosen accordingly to motor speed, current and torque references. Operation point is found as an intersection of torque hyperbola and voltage ellipse curves in d-q motor’s current reference frame involving motor parameters’ limits. However, due to nonlinear dependence between torque and voltage equations, it is quite complicated to obtain both right control mode selection and reference output calculation. In order to solve this problem, a unified control algorithm adopted for wide speed and torque reference with online constraints calculation is proposed. Matlab/Simulink control model of PMSM motor and control system were designed in order to show developed strategy performance. Simulation results shows increasing of speed limit by more than 2.5 times related to nominal speed with high controller’s response. However, speed limit increasing leads to a decrease in motor’s output torque. Due to this fact, presented control strategy is not suitable for applications where nominal torque level is essential for all speed operation points.

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17

He, YC, JCK Cheung, QS Li, and JY Fu. "Accurate determination of reference wind speed and reference static pressure in wind tunnel tests." Advances in Structural Engineering 23, no. 3 (September 15, 2019): 578–83. http://dx.doi.org/10.1177/1369433219875302.

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The reference wind speed and reference static pressure are two key parameters for determining the testing results of wind tunnel experiments. Traditionally, the values of these parameters can be determined using direct measurement methods. However, such methods may suffer from less accuracy and inconvenience of operations. This article documents an indirect measurement method which, compared to the traditional methods, has the merits of higher accuracy and greater operational convenience. Examples are presented to demonstrate the main procedures of the method and typical findings by using the method in a boundary layer wind tunnel.

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18

Fukushima, Toshio. "Reference Frame/Coordinate System in General Relativity." Highlights of Astronomy 7 (1986): 113–16. http://dx.doi.org/10.1017/s1539299600006328.

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The order of magnitude of relativistic effects is expressed as the power of v/c where v is a typical speed of objects and c is the speed of light in vacuum. In the neighbourhood of the Earth, v ≅ 30 km/s. Then the magnitudes of the relativistic effects are ordered as follows:

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19

Bernardes, Luis G. "Reference-dependent preferences and the speed of economic liberalization." Journal of Socio-Economics 32, no. 5 (November 2003): 521–48. http://dx.doi.org/10.1016/j.socec.2003.08.008.

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20

Zhou, Jinliang, Wangyang Zhao, Lingfeng Zhou, Juzhong Liu, and Fenghao Zhao. "INS/CNS Integrated Calibration based on Speed Reference Information." IOP Conference Series: Materials Science and Engineering 768 (March 31, 2020): 052069. http://dx.doi.org/10.1088/1757-899x/768/5/052069.

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21

Németh-Csóka, M. "Open-loop speed calculation in stator-fixed reference frame." European Transactions on Electrical Power 6, no. 2 (September 7, 2007): 125–30. http://dx.doi.org/10.1002/etep.4450060208.

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22

Bohannon, Richard W., A. Williams Andrews, and Michael W. Thomas. "Walking Speed: Reference Values and Correlates for Older Adults." Journal of Orthopaedic & Sports Physical Therapy 24, no. 2 (August 1996): 86–90. http://dx.doi.org/10.2519/jospt.1996.24.2.86.

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23

De Cock, Nicolas, Mathieu Massinon, David Nuyttens, Donald Dekeyser, and Frédéric Lebeau. "Measurements of reference ISO nozzles by high-speed imaging." Crop Protection 89 (November 2016): 105–15. http://dx.doi.org/10.1016/j.cropro.2016.07.016.

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24

Wibowo, Bagus, Edi Sofyan, and Gembong Baskoro. "PROTOTYPE DESIGN OF SPEED DETECTION MOBILE APPLICATION FOR GOLFER’S SWING MOVEMENT USING COMPUTER VISION COMPARED TO PORTABLE RADAR AND ACCELEROMETER SYSTEMS." Proceedings of The Conference on Management and Engineering in Industry 1, no. 1 (September 16, 2019): 49–52. http://dx.doi.org/10.33555/cmei.v1i1.7.

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Prototype Design of Golf Swing Speed Detection Mobile Application (GSSDMA)/Swing Vision (SV) has been researched and developed on this thesis with computer vision technique. Frames detection method has been implemented to performed calculation of the swing speed by manually identification of the frames from start of down swing to impact of the ball with Matlab Video Viewer as initial reference calculation, when head of golf club start to move to downswing as frame-zero/fr0 and frame-n/frn as end of the frame after the head of golf club impact to the ball and then the total frames can be determined by frn minus fr0 (frn - fr0) which will be used for speed calculation reference formula using Python programming.Both measurements have been recorded using RADAR and accelerometer systems to get references of swing speed data measurement from some golfers in golf driving ranges. Accelerometer data measurements have been selected to use as reference of speed calculation with Python programming for software application development since deviation standard is lower than the RADAR systems.There is a limitation on the hand phone camera speed which only have thirty frames per second (30 fps) and the maximum swing speed can be tested with this camera is 101,2 mph at the moment which has three frames (frn-fr0). Found a swing speed formula y = - 0,53x3 + 9,53x2 – 61,27x + 213,35 from experimental data’s of Driver, 6 Iron, 8 Iron and Pitching and maximum swing speed can be predicted is 124,69 mph which has two frames.

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Jia, Yan Fei, Xiao Dong Yang, Li Yue Xu, and Li Quan Zhao. "An Improved Independent Component Analysis with Reference." Applied Mechanics and Materials 667 (October 2014): 64–67. http://dx.doi.org/10.4028/www.scientific.net/amm.667.64.

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Independent component analysis with reference is a general framework to incorporate a priori information of interesting source signal into the cost function as constrained terms to form an augmented Lagrange function, and utilizes Newton method to optimize the cost function. It can extract any interesting source signal without extracting all source signals comparing with the traditional Independent component analysis method. In this paper, to accelerate the convergence speed of the Independent component analysis with reference, two improved algorithms are presented. The new algorithms, firstly whiten the observed signals to avoid matrix inverse operation to reduce algorithm complexity, secondly use improved Newton method with fast convergence speed to optimize cost function,in the end deduce the improved Independent component analysis with reference algorithms. Simulation result demonstrates the new algorithms have faster convergence speed with smaller error compared with the original method.

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Feyo, Abu, Amruth Thelkar, C. Bharatiraja, and Yusuff Adedayo. "Reference design and comparative analysis of model reference adaptive control for steam turbine speed control." FME Transactions 48, no. 2 (2020): 329–41. http://dx.doi.org/10.5937/fme2002329f.

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27

Zhu, Zexuan, Linsen Li, Yongpeng Zhang, Yanli Yang, and Xiao Yang. "CompMap: a reference-based compression program to speed up read mapping to related reference sequences." Bioinformatics 31, no. 3 (October 4, 2014): 426–28. http://dx.doi.org/10.1093/bioinformatics/btu656.

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Nasir Salim Hassen and Nor Azwadi Che Sidik. "Nozzle Type and Driving Speed Effects on Spray Density of Aerial Application According to the Wind Tunnel Measurements." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 84, no. 1 (July 1, 2021): 101–10. http://dx.doi.org/10.37934/arfmts.84.1.101110.

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Spray density (Number of droplets/cm2) is an important component of agricultural spraying processes. In the field, assessment of the spray density under effect of a number of variables such as nozzle type and driving speed without take in account the effect of cross wind speed is insufficient. In this study, to simulate field spray operation, tests were carried out in wind tunnel using automatic spraying mechanism to investigate and to clarify effect of three types of flat fan nozzle tip spray at three driving speeds under effect three cross wind speeds on spray density. Water sensitive papers (WSPs) were used to collect spray density data. Spray density was calculated through image processing program software. Performance of spray nozzles was validated relative to experimental data of a TP11003 reference nozzle. Results indicated that XR11003 nozzle behavior was to some extent similar to that TP11003 nozzle under effect slow wind speed. It is also noticed that the spray density value decreased with increasing driving speed and wind speed, the spray density value with driving speed of 2.2 m/s and wind speed of 1 m/s was the best, reaching 64.3 droplet /cm2. While the spray density value with driving speed of 5.5 m/s and wind speed of 3 m/s was the least, reaching 3.8 droplet /cm2. The current study presents that the use of DG11003 nozzle gives the best control spray density data under effect very windy conditions to the reference nozzle.

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Yang, Qi, Yu Feng Zhang, Shi Bao Qian, and Bing Li. "Speed Sensorless Vector Control of Cascaded Inverter for Asynchronous Motor." Applied Mechanics and Materials 241-244 (December 2012): 1797–801. http://dx.doi.org/10.4028/www.scientific.net/amm.241-244.1797.

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According to speed sensorless vector control of Asynchronous motor for Cascaded high voltage inverter, a model reference adaptive system (MRAS) implemented in two phase rotating reference frame was studied to identify the rotor speed of an asynchronous motor. To eliminate the inherent limitations of MRAS in two phase stationary reference frame, the reference model and adjustable model used in this MRAS scheme are composed of an improved rotor flux voltage model and rotor flux current model in two phase rotating reference frame respectively. Simulation and experimental results show that the vector control system can estimate the flux and speed with good accuracy, and run with good static and dynamic performance in start, speed regulation and steady operation.

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Abd Samat, Ahmad Asri, Dahaman Ishak, Shahid Iqbal, and Aimi Idzwan Tajudin. "Comparison between Takagi Sugeno FIS and PI Controller: An Adaptation Scheme of MRAS for Speed Sensorless Control of PMSM." Applied Mechanics and Materials 785 (August 2015): 193–97. http://dx.doi.org/10.4028/www.scientific.net/amm.785.193.

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— This paper proposes modification of an adaptation scheme which aims to replace the conventional PI controller for MRAS by using Fuzzy Logic Control (FLC). This FLC based on Takagi-Sugeno Fuzzy Logic Inference System (FIS). To achieve this goal, field oriented control (FOC) method has been utilized to control the speed of PMSM with the implementation of MRAS to observe the rotor position and speed of the motor. PMSM becomes the reference model for MRAS while the current model in the rotor reference frame is set as the adjustable model. The Takagi Sugeno Fuzzy FIS is executed in the MRAS adaptive scheme in order to tune the errors between the reference and adjustable model. The effectiveness of the Takagi Sugeno FIS to tune the errors in MRAS scheme is compared with the conventional PI controller. The proposed method clearly indicates improved motor performance over a wide range of operating speeds since is capable of tracking the motor speed effectively.

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31

Urbański, Konrad. "Sensorless control of SRM at medium speed range." Archives of Electrical Engineering 60, no. 2 (June 1, 2011): 179–85. http://dx.doi.org/10.2478/v10171-011-0017-4.

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Sensorless control of SRM at medium speed rangeThe paper deals with the problem of position and speed estimation methods in SRM (Switched Reluctance Motor) drive equipped with hysteresis band current controller with MRAS (Model Reference Adaptive System) type observer. An adaptive flux model uses equation set of one-dimensional equations instead of one two-dimensional equation. The reference model is the formal one. Instead of measured current the observer utilizes reference current. Such drive system works well at speed range up to 600 rad/s. The observer's gains must change depend on the speed range. The robustness on motor parameter poor estimation is presented.

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Da Silva, Marco Jose, Eduardo N. Dos Santos, and Tiago P. Vendruscolo. "High-speed multichannel impedance measuring system." ACTA IMEKO 1, no. 1 (June 7, 2012): 36. http://dx.doi.org/10.21014/acta_imeko.v1i1.18.

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In this paper, a novel high-speed multichannel impedance measuring system in presented. The measurements are based on simultaneous excitation with two distinct frequencies to interrogate the multiple sensing point of a given sensor. Received signals are analogue-to-digital converted (with a DAQ card) and the amplitudes of each frequency are determined using FFT implemented in LabVIEW. The capacitive and conductive parts of impedance are calculated based on amplitude measurements. The developed system can operate 8 transmitter and 8 receiver electrodes at a frame repetition frequency of up to 781 Hz, i.e. single channels are sampled at 6,248 Hz. The system has been evaluated by measuring reference components. Deviations from references values are below 10% which considering the fast repetition frequency of measurements is satisfactory. The developed system was applied to visualize the fluid distribution over the surface of planar multipoint sensor. Two different liquids (oil and water) and air were evaluated and their spatial distribution over the sensor’s surface was correctly visualized.

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She, Zhi Ting, Jun Bo Yuan, Yong Zheng, and Yong Jin Peng. "Rotor Speed and Stator Resistance Identification of Direct Torque Control for Induction Motor Based on Mutual MRAS." Advanced Materials Research 383-390 (November 2011): 2458–63. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.2458.

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Based on the dynamic mathematical model of induction motor, the mutual model reference adaptive system method (MRAS) for rotor speed identification is proposed to implement a speed sensorless direct torque control of induction motor. The model reference adaptive theory is flexibly used in the rotor speed and the stator resistance online identification. The reference model and adjustable model used in the mutual MRAS scheme are interchangeable. Therefore, The induction motor speed sensorless direct torque control system can obtain high-precision speed identification. Computer simulations and experimental results show that the method can solve the problems of speed control accuracy and system stability under the influence of motor parameter variation. The low speed performance of DTC is also improved.

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Ewertsen, Caroline, Jonathan Carlsen, Mohammed Perveez, and Henrik Schytz. "Reference Values for Shear Wave Elastography of Neck and Shoulder Muscles in Healthy Individuals." Ultrasound International Open 04, no. 01 (January 2018): E23—E29. http://dx.doi.org/10.1055/s-0044-102013.

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Abstract Purpose to establish reference values for ultrasound shear-wave elastography for pericranial muscles in healthy individuals (m. trapezius, m. splenius capitis, m. semispinalis capitis, m. sternocleidomastoideus and m. masseter). Also to evaluate day-to-day variations in the shear-wave speeds and evaluate the effect of the pennation of the muscle fibers, ie scanning parallel or perpendicularly to the fibers. Materials and Methods 10 healthy individuals (5 males and 5 females) had their pericranial muscles examined with shear-wave elastography in two orthogonal planes on two different days for their dominant and non-dominant side. Mean shear wave speeds from 5 ROI’s in each muscle, for each scan plane for the dominant and non-dominant side for the two days were calculated. The effect of the different parameters – muscle pennation, gender, dominant vs non-dominant side and day was evaluated. Results The effect of scan plane in relation to muscle pennation was statistically significant (p<0.0001). The mean shear-wave speed when scanning parallel to the muscle fibers was significantly higher than the mean shear-wave speed when scanning perpendicularly to the fibers. The day-to-day variation was statistically significant (p=0.0258), but not clinically relevant. Shear-wave speeds differed significantly between muscles. Mean shear wave speeds (m/s) for the muscles in the parallel plane were: for masseter 2.45 (SD:+/−0.25), semispinal 3.36 (SD:+/−0.75), splenius 3.04 (SD:+/−0.65), sternocleidomastoid 2.75 (SD:+/−0.23), trapezius 3.20 (SD:+/−0.27) and trapezius lateral 3.87 (SD:+/−3.87). Conclusion The shear wave speed variation depended on the direction of scanning. Shear wave elastography may be a method to evaluate muscle stiffness in patients suffering from chronic neck pain.

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She, Zhi Ting, Yong Zheng, and Yong Jin Peng. "Rotor Speed Adaptive Identification of Direct Torque Control for Induction Motor." Advanced Materials Research 139-141 (October 2010): 1785–88. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.1785.

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Based on the dynamic mathematical model of induction motor, the mutual model reference adaptive system method (MRAS) for rotor speed identification is proposed to implement a speed sensorless direct torque control. The model reference adaptive theory is flexibly used in the rotor speed and the stator resistance online identification. The reference model and adjustable model used in the mutual MRAS scheme are interchangeable. Therefore, the control system can obtain high-precision speed identification. Simulation results show the method can solve the problems of speed control accuracy and system stability under the influence of motor parameter variation. The low speed performance of DTC is also improved.

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Wang, Ji Yan, Rong Chun Guo, and Xu Fei Si. "The Dynamic Analysis of SFD-Sliding Bearing Flexible Rotor System Based on Optimization Design." Applied Mechanics and Materials 159 (March 2012): 355–60. http://dx.doi.org/10.4028/www.scientific.net/amm.159.355.

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The paper establishes the mechanical model of SFD-sliding bearing flexible rotor system, adopting Runge-Kutta method to solve nonlinear differential equation, thus acquiring the unbalanced response curve and then gaining the first two critical speeds of the system. Meanwhile, the paper analyzes the sensitivity of the system on the first two critical speeds towards structural parameters, offering design variables to optimization analysis. Based on sensitivity analysis, genetic algorithm is employed to give an optimization analysis on critical speed, which aims to remove critical speed from working speed as much as possible. The critical speed ameliorates after the optimization which supplies theoretical basis as well as theoretical analysis towards the dynamic stability of high-speed rotor system and provides reference for the design of such rotor system.

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Orlowska-Kowalska, T., and M. Dybkowski. "Performance analysis of the sensorless adaptive sliding-mode neuro-fuzzy control of the induction motor drive with MRAS-type speed estimator." Bulletin of the Polish Academy of Sciences: Technical Sciences 60, no. 1 (March 1, 2012): 61–70. http://dx.doi.org/10.2478/v10175-012-0010-0.

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Performance analysis of the sensorless adaptive sliding-mode neuro-fuzzy control of the induction motor drive with MRAS-type speed estimator This paper discusses a model reference adaptive sliding-mode control of the sensorless vector controlled induction motor drive in a wide speed range. The adaptive speed controller uses on-line trained fuzzy neural network, which enables very fast tracking of the changing speed reference signal. This adaptive sliding-mode neuro-fuzzy controller (ASNFC) is used as a speed controller in the direct rotor-field oriented control (DRFOC) of the induction motor (IM) drive structure. Connective weights of the controller are trained on-line according to the error between the actual speed of the drive and the reference model output signal. The rotor flux and speed of the vector controlled induction motor are estimated using the model reference adaptive system (MRAS) - type estimator. Presented simulation results are verified by experimental tests performed on the laboratory-rig with DSP controller.

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Salem, Z. M., M. M. Khater, S. A. Kalilah, and S. A. Mahmoud. "FOUR-QUADRANT SPEED ESTIMATION BASED ON MODEL REFERENCE ADAPTIVE SYSTEM." ERJ. Engineering Research Journal 28, no. 2 (April 1, 2005): 169–77. http://dx.doi.org/10.21608/erjm.2005.69937.

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Bilgili, M., and B. Sahin. "Wind Speed Prediction of Target Station from Reference Stations Data." Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 35, no. 5 (March 2013): 455–66. http://dx.doi.org/10.1080/15567036.2010.512906.

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Gu, R. X., and M. I. Elmasry. "High-speed dynamic reference voltage (DRV) CMOS/ECL interface circuits." IEEE Journal of Solid-State Circuits 29, no. 10 (1994): 1282–87. http://dx.doi.org/10.1109/4.315215.

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Kherde, Rajesh Vijaykumar, and Sumana Sahoo. "Modeling Reference Evapotranspiration with Wind Speed and Relative Humidity Data." International Journal of Engineering and Technology 8, no. 6 (December 31, 2016): 2815–23. http://dx.doi.org/10.21817/ijet/2016/v8i6/160806241.

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Chen, T. C., and T. T. Sheu. "Model Reference Neural Network Controller for Induction Motor Speed Control." IEEE Power Engineering Review 22, no. 4 (April 2002): 73. http://dx.doi.org/10.1109/mper.2002.4312121.

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Jingzhuo, Shi, and Wenwen Huang. "Model Reference Adaptive Iterative Learning Speed Control for Ultrasonic Motor." IEEE Access 8 (2020): 181815–24. http://dx.doi.org/10.1109/access.2020.3029106.

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Huypens, Valere. "Constant speed lines–curves—NURBS reference pulse IPOs (part I)." International Journal of Advanced Manufacturing Technology 111, no. 5-6 (October 9, 2020): 1247–75. http://dx.doi.org/10.1007/s00170-020-05339-1.

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Tien-Chi Chen and Tsong-Terng Sheu. "Model reference neural network controller for induction motor speed control." IEEE Transactions on Energy Conversion 17, no. 2 (June 2002): 157–63. http://dx.doi.org/10.1109/tec.2002.1009462.

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Koopman, B., E. H. F. van Asseldonk, and H. van der Kooij. "Speed-dependent reference joint trajectory generation for robotic gait support." Journal of Biomechanics 47, no. 6 (April 2014): 1447–58. http://dx.doi.org/10.1016/j.jbiomech.2014.01.037.

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Tereshchenko, V. E. "Technique for relation global reference system and local realization of global reference system by continuously operated reference stations." Geodesy and Cartography 962, no. 8 (September 20, 2020): 24–37. http://dx.doi.org/10.22389/0016-7126-2020-962-8-24-37.

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The article suggests a technique for relation global kinematic reference system and local static realization of global reference system by regional continuously operated reference stations (CORS) network. On the example of regional CORS network located in the Novosibirsk Region (CORS NSO) the relation parameters of the global reference system WGS-84 and its local static realization by CORS NSO network at the epoch of fixing stations coordinates in catalog are calculated. With the realization of this technique, the main parameters to be determined are the speed of displacement one system center relativly to another and the speeds of rotation the coordinate axes of one system relatively to another, since the time evolution of most stations in the Russian Federation is not currently provided. The article shows the scale factor for relation determination of coordinate systems is not always necessary to consider. The technique described in the article also allows detecting the errors in determining the coordinates of CORS network in global coordinate system and compensate for them. A systematic error of determining and fixing the CORS NSO coordinates in global coordinate system was detected. It is noted that the main part of the error falls on the altitude component and reaches 12 cm. The proposed technique creates conditions for practical use of the advanced method Precise Point Positioning (PPP) in some regions of the Russian Federation. Also the technique will ensure consistent PPP method results with the results of the most commonly used in the Russian Federation other post-processing methods of high-precision positioning.

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Pignard, Olivier. "Black holes in the theory of the dynamic medium of reference." Physics Essays 33, no. 4 (December 29, 2020): 395–99. http://dx.doi.org/10.4006/0836-1398-33.4.395.

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The aim of this article is to apply the theory of the dynamic medium of reference [O. Pignard, Phys. Essays 32, 422 (2019)] to black holes and to find all the results of general relativity concerning black holes without rotation and without load. Among the most important results to which this article leads, we can mention: (1) The speed of the flux of the medium is greater than the speed of light inside the horizon of a black hole or even much greater than the speed of light at a distance from the center of the black hole much less than the radius of Schwarzschild. (2) In the hybrid coordinate system (drSchwarzschild, dtfree fall), the speed of light is established simply in relation to its propagation medium. (3) A photon emitted at an infinite distance from the black hole with speed c 0 arrives near the horizon of the black hole with a real speed zero. And yet the local measurement of the speed of the photon carried out with a material clock and a material ruler remains c 0. (4) Study of the possible orbits of a material particle around a black hole and the possibility of orbits of a photon around a black hole.

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Tarchała and Wolkiewicz. "Performance of the Stator Winding Fault Diagnosis in Sensorless Induction Motor Drive." Energies 12, no. 8 (April 21, 2019): 1507. http://dx.doi.org/10.3390/en12081507.

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This paper deals with the diagnosis of stator winding inter-turn faults for an induction motor drive operating without a speed sensor in a speed-sensorless mode. The rotor direct field oriented control structure (DFOC) was applied, its reference current and voltage component values were analyzed, and their selected harmonics were applied as effective fault indicators. To ensure robust speed estimation, a sliding mode model reference adaptive system (SM-MRAS) estimator was selected. The influence of load torque, reference speed, proportional-integral (PI) controller parameters, and short-circuit current on fault diagnosis and speed estimation performance was verified. Experimental test results obtained for a 3 kW induction motor drive are included.

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Gao, Yuan, Changlong Guan, Jian Sun, and Lian Xie. "Tropical Cyclone Wind Speed Retrieval from Dual-Polarization Sentinel-1 EW Mode Products." Journal of Atmospheric and Oceanic Technology 37, no. 9 (September 1, 2020): 1713–24. http://dx.doi.org/10.1175/jtech-d-19-0148.1.

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AbstractRecent studies indicate that the cross-polarization synthetic aperture radar (SAR) images have the ability of retrieving high wind speed on ocean surface without wind direction input. This study presents a new approach for tropical cyclone (TC) wind speed retrieval utilizing thermal-noise-removed Sentinel-1 dual-polarization (VV + VH) Extra-Wide Swath (EW) Mode products. Based on 20 images of 9 TCs observed in the 2016 and 2018 and SAR-collocated European Centre for Medium-Range Weather Forecasts (ECMWF) fifth-generation reanalysis (ERA5) data and the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division’s (HRD) Real-time Hurricane Wind Analysis System (H*Wind) data, a subswath-based geophysical model function (GMF) Sentinel-1 EW Mode Wind Speed Retrieval Model after Noise Removal (S1EW.NR) is developed and validated statistically. TC wind speed is retrieved by using the proposed GMF and the C-band model 5.N (CMOD5.N). The results show that the wind speeds retrieved by the S1EW.NR model are in good agreement with wind references up to 31 m s−1. The correlation coefficient, bias, and standard deviation between the retrieval results and reference wind speeds are 0.74, −0.11, and 3.54 m s−1, respectively. Comparison of the wind speeds retrieved from both channels suggests that the cross-polarized signal is more suitable for high–wind speed retrieval, indicating the promising capability of cross-polarization SAR for TC monitoring.

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