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Journal articles on the topic 'High efficiency variable speed'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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MORIKAWA, Koji, Makoto KANEKO, Hiroshi OIWA, and Yasuo MORIYOSHI. "High Compression Ratio High Efficiency Gasoline Engine with Variable Speed Piston-crank Mechanism." Transactions of the Japan Society of Mechanical Engineers Series B 73, no. 735 (2007): 2176–82. http://dx.doi.org/10.1299/kikaib.73.2176.

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De Capua, C., and C. Landi. "Measurement station performance optimization for testing of high efficiency variable speed drives." IEEE Transactions on Instrumentation and Measurement 48, no. 6 (1999): 1149–54. http://dx.doi.org/10.1109/19.816129.

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Shen, Hai Kuo, Meng Nie, Shao Dan Zhi, and Jin Bo. "Study on High Dynamic Variable Speed Hydraulic Control System." Applied Mechanics and Materials 271-272 (December 2012): 625–31. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.625.

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A new type of high dynamic variable speed hydraulic control system is developed in this paper. In this system, a fixed displacement hydraulic pump is driven by an electrical motor which is controlled by a frequency inverter, so the discharge of the pump can be modified by changing the speed of the motor. A proportional directional valve is used to acquire higher low-speed control precision and faster dynamic response while the system is decelerating. In order to improve the dynamic response while the system is accelerating, an energy regulation device is employed in the system. The digital simulation results show that this system has higher efficiency than valve control system. Further more it has faster dynamic response and higher low-speed control precision than normal variable speed hydraulic control system.

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Kshirsagar, Parag, and R. Krishnan. "High-Efficiency Current Excitation Strategy for Variable-Speed Nonsinusoidal Back-EMF PMSM Machines." IEEE Transactions on Industry Applications 48, no. 6 (2012): 1875–89. http://dx.doi.org/10.1109/tia.2012.2225814.

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Hasan, Md Ehtesham, K. Dasgupta, and Sanjoy Ghoshal. "Comparison of the efficiency of the high speed low torque hydrostatic drives using bent axis motor: An experimental study." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 231, no. 4 (2015): 650–66. http://dx.doi.org/10.1177/0954408915622413.

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This article is aimed at analysing the steady-state performance of four hydrostatic drives and compares their overall efficiency. The speed of the hydrostatic drives is controlled by speed controlled vane pump, variable displacement flow compensated pump, variable displacement pressure compensated pump and proportional direction controlled valve. Bondgraph simulation technique is used to model the hydrostatic drive. The relationships of the loss coefficients with the state variables obtained from the model are identified through experimental investigation. Using them, at different torque levels, the performances of the hydrostatic drives are studied on their slips, torque losses and the overall efficiencies and they are validated experimentally. It is found that hydrostatic drive using speed controlled vane pump exhibits the maximum efficiency, whereas the poorest efficiency is shown by the valve controlled system out of the four drives considered in the analysis.

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Xu, L. Y., Zhi Li Zhou, M. Z. Zhang, and Y. Niu. "Multi-Range Hydro-Mechanical Continuously Variable Transmission of Tractor." Materials Science Forum 628-629 (August 2009): 167–72. http://dx.doi.org/10.4028/www.scientific.net/msf.628-629.167.

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In this paper, to improve the transmission ratio discontinuity problem during the gear shift process in the multi-gear fixed step ratio transmission of the tractors, a hydro-mechanical continuously variable transmission (HMCVT) for tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of the variable displacement pump (PV) and the fixed displacement motor (MF) and a multi-gear fixed step ratio transmission. Its stepless-speed-regulating characteristic, smooth range shifting condition and transmission efficiency are analyzed. The analytical results show that the tractors assembled with HMCVT can gain wide speed range and high transmission efficiency. There are eight high efficiency pure mechanical gears in the whole speed range, which is benefit to improve power and economic capabilities of vehicles.

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D'Août, K., and P. Aerts. "Kinematics and efficiency of steady swimming in adult axolotls (Ambystoma mexicanum)." Journal of Experimental Biology 200, no. 13 (1997): 1863–71. http://dx.doi.org/10.1242/jeb.200.13.1863.

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The kinematics of steady swimming at a wide range of velocities was analysed using high-speed video recordings (500 frames s-1) of eight individuals of Ambystoma mexicanum swimming through a tunnel containing stationary water. Animals in the observed size range (0.135&shy;0.238 m total body length) prefer to swim at similar absolute speeds, irrespective of their body size. The swimming mechanism is of the anguilliform type. The measured kinematic variables &shy; the speed, length, frequency and amplitude (along the entire body) of the propulsive wave &shy; are more similar to those of anguilliform swimming fish than to those of tadpoles, in spite of common morphological features with the latter, such as limbs, external gills and a tapering tail. The swimming speed for a given animal size correlates linearly with the tailbeat frequency (r2=0.71), whereas the wavelength and tail-tip amplitude do not correlate with this variable. The shape of the amplitude profile along the body, however, is very variable between the different swimming bouts, even at similar speeds. It is suggested that, for a given frequency, the amplitude profile along the body is adjusted in a variable way to yield the resulting swimming speed rather than maintaining a fixed-amplitude profile. The swimming efficiency was estimated by calculating two kinematic variables (the stride length and the propeller efficiency) and by applying two hydrodynamic theories, the elongated-body theory and an extension of this theory accounting for the slope at the tail tip. The latter theory was found to be the most appropriate for the axolotl's swimming mode and yields a hydromechanical efficiency of 0.75&plusmn;0.04 (mean &plusmn; s.d.), indicating that Ambystoma mexicanum swims less efficiently than do anuran tadpoles and most fishes. This can be understood given its natural habitat in vegetation at the bottom of lakes, which would favour manoeuvrability and fast escape.

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Zagar, Philipp, Helmut Kogler, Rudolf Scheidl, and Bernd Winkler. "Hydraulic Switching Control Supplementing Speed Variable Hydraulic Drives." Actuators 9, no. 4 (2020): 129. http://dx.doi.org/10.3390/act9040129.

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Primary control of linear motion by variable speed electric motors driving a hydraulic cylinder via a constant displacement pump is an established and successful concept with a frequent use in industry. One problem arises when low or zero motion speed has to be realized under high pump pressure conditions. Such load scenarios occur frequently in certain pressing processes, e.g., for sintering or veneering. Most pumps have a lower speed limit, below which critical tribological conditions occur which impair lifespan and efficiency. In addition, pump speed control and pump fluctuation suffer from the mixed lubrication conditions in such an operation range. For a circumvention of such low speed pump operation, a digital valve control concept is presented and studied in this paper. Valve control is used in load holding phases with low speed. Pressure is provided by an accumulator which is charged by the pump in short charging cycles at reasonable pump speeds. It is shown that the mean control error during load holding phase lies within the desired band and the fluctuations of the control force are lower than those of the pump control. In addition, the unfavorable pump operation conditions can be avoided via digital control.

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Lin, Dakai, Duan Huang, Peng Huang, Jinye Peng, and Guihua Zeng. "High performance reconciliation for continuous-variable quantum key distribution with LDPC code." International Journal of Quantum Information 13, no. 02 (2015): 1550010. http://dx.doi.org/10.1142/s0219749915500100.

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Reconciliation is a significant procedure in a continuous-variable quantum key distribution (CV-QKD) system. It is employed to extract secure secret key from the resulted string through quantum channel between two users. However, the efficiency and the speed of previous reconciliation algorithms are low. These problems limit the secure communication distance and the secure key rate of CV-QKD systems. In this paper, we proposed a high-speed reconciliation algorithm through employing a well-structured decoding scheme based on low density parity-check (LDPC) code. The complexity of the proposed algorithm is reduced obviously. By using a graphics processing unit (GPU) device, our method may reach a reconciliation speed of 25 Mb/s for a CV-QKD system, which is currently the highest level and paves the way to high-speed CV-QKD.

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Bai, Yuxing, Fanyu Kong, Fei Zhao, Jiaqiong Wang, Bin Xia, and Qianlan Hu. "Experiments and Numerical Simulation of Performances and Internal Flow for High-Speed Rescue Pump with Variable Speeds." Mathematical Problems in Engineering 2018 (July 2, 2018): 1–18. http://dx.doi.org/10.1155/2018/9168694.

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The model pump is a high-speed, high-power pump designed to achieve rapid mine flooding rescue. This study conducted experiments to investigate pump performance curves, including head, efficiency, and power for the following six different rotation speeds: 3000, 3600, 4200, 4800, 5400, and 6000 rpm. Then, the numerical simulation method based on computational fluid dynamics commercial code Ansys was used to present the internal flow of the pump for the six different rotation speeds through steady and unsteady analyses. Results show that the numerical results agree well with experimental data. The designs of outlet and inlet angles of the impeller match each other well at high rotation speeds. The pressure pulsation coefficient Cp in the impeller and the diffuser channel remain constant at the same monitor point under different rotation speed conditions. The varying trend of the pressure-augmented coefficient ΔP indicates that, with the increase in rotation speed, the effect on pressure rise induced by the back part of the impeller channel is more evident than that by the front part. Also, the main frequency components of ΔP are concentrated on the region with low frequency. Moreover, the rotation speed has no significant effect on ΔP in the diffuser region. This study provides effective guidance and valuable reference for the design of high-speed, high-power pumps.

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Nguyen, Minh Tri, Tri Dung Dang, and Kyoung Kwan Ahn. "Application of Electro-Hydraulic Actuator System to Control Continuously Variable Transmission in Wind Energy Converter." Energies 12, no. 13 (2019): 2499. http://dx.doi.org/10.3390/en12132499.

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The wind energy conversion system (WEC) has been increasingly proposed to capture wind energy producing electrical power in high efficiency. One of the most important factors that has significant influence on the overall efficiency is the performance of generators in a fixed-speed wind turbine. The efficiency of the generator strongly depends on the operating speed. Therefore, the generator should be controlled to operate at the rated speed to increase the overall efficiency. In this paper, a continuously variable transmission (CVT) was employed to maintain the speed of the generator by controlling the transmission ratio. By employing a position control system based on an electro-hydraulic actuator (EHA), the speed ratio could be tuned continuously to keep the generator at rated speed. Here, an adaptive fuzzy sliding mode control (AFSC) was developed to control the proposed EHA CVT. Mathematical analysis was also carried out to investigate the global stability of the system. Finally, experiments were conducted to evaluate the performance of the proposed WECs.

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Deng, Xu, Barrie Mecrow, Haimeng Wu, Richard Martin, and Yaohui Gai. "Cost-Effective and High-Efficiency Variable-Speed Switched Reluctance Drives With Ring-Connected Winding Configuration." IEEE Transactions on Energy Conversion 34, no. 1 (2019): 120–29. http://dx.doi.org/10.1109/tec.2018.2851065.

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Yang, Shujun, Yong Bao, Xianzhi Tang, Xiaojuan Jiao, Deqing Yang, and Qing Wang. "Integrated Control of Hydromechanical Variable Transmissions." Mathematical Problems in Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/290659.

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A hydromechanical variable transmission (HMT) has advantages of continuous variation and high efficiency. So it is one of the ideal transmissions of heavy vehicles. The continuous speed varying process involves speed governing in range and range shift. Integrated control strategy of the HMT is proposed in this paper. The algorithm of the asymmetric saturated incremental proportional integral derivative (PID) speed control strategy in range and range shift conditions are derived. And this paper presents the range shift logic and range shift control strategies. A controller model is built in Matlab Simulink and cosimulated with the model of vehicle equipped with a two-range HMT. The HMT prototype hardware-in-the-loop simulation (HILS) platform of the integrated control strategy is built. The HILS results show that the range shift process is smooth and speed fluctuation does not happen. In the throttle stable stage, the engine speed is adjusted to the near optimal speed, and its change rules are in accordance with simulation results. The integrated control strategy is reasonable.

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Lou, Xi Yin. "Application of Tracked Combine Harvester Step-Less Speed Regulated System." Advanced Materials Research 904 (March 2014): 365–67. http://dx.doi.org/10.4028/www.scientific.net/amr.904.365.

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In this paper, Step-less speed regulation system using double reversible variable pump and double quantitative motor, since the middle of no other control valve, the hydraulic pump and hydraulic motor with high efficiency. To meet the tracked combine and walking machines because of their own characteristics has the advantages of compact structure, light weight, high efficiency, high reliability, and other requirements of the system..

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Apelfröjd, Senad, and Sandra Eriksson. "System Efficiency of a Tap Transformer Based Grid Connection Topology Applied on a Direct Driven Generator for Wind Power." Scientific World Journal 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/784295.

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Results from experiments on a tap transformer based grid connection system for a variable speed vertical axis wind turbine are presented. The tap transformer based system topology consists of a passive diode rectifier, DC-link, IGBT inverter, LCL-filter, and tap transformer. Full range variable speed operation is enabled by using the different step-up ratios of a tap transformer. Simulations using MATLAB/Simulink have been performed in order to study the behavior of the system. A full experimental set up of the system has been used in the laboratory study, where a clone of the on-site generator was driven by an induction motor and the system was connected to a resistive load to better evaluate the performance. Furthermore, the system is run and evaluated for realistic wind speeds and variable speed operation. For a more complete picture of the system performance, a case study using real site Weibull parameters is done, comparing different tap selection options. The results show high system efficiency at nominal power and an increase in overall power output for full tap operation in comparison with the base case, a standard transformer. In addition, the loss distribution at different wind speeds is shown, which highlights the dominant losses at low and high wind speeds. Finally, means for further increasing the overall system efficiency are proposed.

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Wang, Junyan, Changgao Xia, Xin Fan, and Junyu Cai. "Research on Transmission Characteristics of Hydromechanical Continuously Variable Transmission of Tractor." Mathematical Problems in Engineering 2020 (August 12, 2020): 1–14. http://dx.doi.org/10.1155/2020/6978329.

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This paper proposes a new transmission scheme of hydromechanical continuously variable transmission (HMCVT) for tractors. The HMCVT has 4 working ranges in each of the front and rear directions. The speed characteristic and the torque characteristic of HMCVT are theoretically derived. On the basis of HMCVT power flow direction, the Крейнeс formula is used to calculate the transmission efficiency. Then, the image analysis method is used to study the influence of parameters on the transmission efficiency of HMCVT, and the main influencing factors are found. The results of theoretical derivation demonstrate that, by coordinating control of the HST displacement ratio and the engagement conditions of shifting clutches, the stepless speed regulation of HMCVT at the tractor speed of 0–50 km/h can be realized. The proposed HMCVT has the ability to continuously transmit and change torque over all working ranges. The overall transmission efficiency of HMCVT is at a high level. To verify the theoretical derivation, Amesim simulation software is used for the modeling and simulation of HMCVT. The simulation results are consistent with the theoretical analysis results. Therefore, the HMCVT proposed in this paper has the advantages of compact structure and high transmission efficiency, and it is suitable for matching tractors.

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Yuan, Y., D. Thomson, and R. Chen. "Variable rotor speed strategy for coaxial compound helicopters with lift–offset rotors." Aeronautical Journal 124, no. 1271 (2019): 96–120. http://dx.doi.org/10.1017/aer.2019.113.

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ABSTRACTThe coaxial compound helicopter with lift-offset rotors has been proposed as a concept for future high-performance rotorcraft. This helicopter usually utilizes a variable-speed rotor system to improve the high-speed performance and the cruise efficiency. A flight dynamics model of this helicopter associated with rotor speed governor/engine model is used in this article to investigate the effect of the rotor speed change and to study the variable rotor speed strategy. Firstly, the power-required results at various rotor rotational speeds are calculated. This comparison indicates that choice of rotor speed can reduce the power consumption, and the rotor speed has to be reduced in high-speed flight due to the compressibility effects at the blade tip region. Furthermore, the rotor speed strategy in trim is obtained by optimizing the power required. It is demonstrated that the variable rotor speed successfully improves the performance across the flight range, but especially in the mid-speed range, where the rotor speed strategy can reduce the overall power consumption by around 15%. To investigate the impact of the rotor speed strategy on the flight dynamics properties, the trim characteristics, the bandwidth and phase delay, and eigenvalues are investigated. It is shown that the reduction of the rotor speed alters the flight dynamics characteristics as it affects the stability, damping, and control power provided by the coaxial rotor. However, the handling qualities requirements are still satisfied with different rotor speed strategies. Finally, a rotor speed strategy associated with the collective pitch is designed for maneuvering flight considering the normal load factor. Inverse simulation is used to investigate this strategy on maneuverability in the Push-up & Pull-over Mission-Task-Element (MTE). It is shown that the helicopter can achieve Level 1 ratings with this rotor speed strategy. In addition, the rotor speed strategy could further reduce the power consumption and pilot workload during the maneuver.

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Sehra, A., J. Bettner, and A. Cohn. "Design of a High-Performance Axial Compressor for Utility Gas Turbine." Journal of Turbomachinery 114, no. 2 (1992): 277–86. http://dx.doi.org/10.1115/1.2929141.

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An aerodynamic design study to configure a high-efficiency industrial-size gas turbine compressor is presented. This study was conducted using an advanced aircraft engine compressor design system. Starting with an initial configuration based on conventional design practice, compressor design parameters were progressively optimized. To improve the efficiency potential of this design further, several advanced design concepts (such as stator ends bends and velocity controlled airfoils) were introduced. The projected poly tropic efficiency of the final advanced concept compressor design having 19 axial stages was estimated at 92.8 percent, which is 2 to 3 percent higher than the current high-efficiency aircraft turbine engine compressors. The influence of variable geometry on the flow and efficiency (at design speed) was also investigated. Operation at 77 percent design flow with inlet guide vanes and front five variable stators is predicted to increase the compressor efficiency by 6 points as compared to conventional designs having only the inlet guide vane as variable geometry.

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Kim, Young Hyun, Seong Soo Lee, and Jung Ho Lee. "A study of flux control for high-efficiency speed control of variable flux permanent magnet motor." AIP Advances 8, no. 5 (2018): 056632. http://dx.doi.org/10.1063/1.5006443.

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Okada, Takeshi, Takashi Kosaka, Hiroaki Matsumori, and Nobuyuki Matsui. "Comparative Study on Hybrid Excitation Flux Switching Motors without and with Variably Magnetizable Permanent Magnets for Electrified Vehicle Propulsion." World Electric Vehicle Journal 12, no. 2 (2021): 58. http://dx.doi.org/10.3390/wevj12020058.

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A demand for high efficiency traction motors has been accelerated by the promotion of electrified vehicles, such as battery and fuel cell electric vehicles. As a part of development of the high efficiency traction motor, this paper reports a comparative study on two kinds of hybrid excitation flux switching motors (HEFSM) as a variable flux machine. One is the conventional HEFSM, which consists of a stator with constantly magnetized-permanent magnets, field excitation coils (FECs) and three-phase armature windings, and a rotor with salient poles like a switched reluctance motor. The other is a HEFSM employing variably magnetizable-permanent magnets (VM-PMs) that replace a part in the FEC slot area in the conventional one. Based on the variable magnetization nature of VM-PMs, the latter HEFSM promises that the replacement of magnetomotive force (mmf) of FECs with that of the VM-PMs makes the motor efficiency better at both low- and high-speed under the low-torque condition, that is, at both urban driving or highway cruising. To verify that, finite element analysis- (FEA)-based design simulations, as well as experimental performance evaluations for the two kinds of HEFSM, were conducted under reasonable dimensional and electrical constraints. As a result, it is shown that the latter HEFSM can achieve higher motor efficiency at the low-torque and high-speed region while keeping the motor efficiency at the low-torque and low-speed region.

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Boretti, Albert. "Super Turbocharging the Direct Injection Diesel engine." Nonlinear Engineering 7, no. 1 (2018): 17–27. http://dx.doi.org/10.1515/nleng-2017-0067.

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Abstract The steady operation of a turbocharged diesel direct injection (TDI) engine featuring a variable speed ratio mechanism linking the turbocharger shaft to the crankshaft is modelled in the present study. Key parameters of the variable speed ratio mechanism are range of speed ratios, efficiency and inertia, in addition to the ability to control relative speed and flow of power. The device receives energy from, or delivers energy to, the crankshaft or the turbocharger. In addition to the pistons of the internal combustion engine (ICE), also the turbocharger thus contributes to the total mechanical power output of the engine. The energy supply from the crankshaft is mostly needed during sharp accelerations to avoid turbo-lag, and to boost torque at low speeds. At low speeds, the maximum torque is drastically improved, radically expanding the load range. Additionally, moving closer to the points of operation of a balanced turbocharger, it is also possible to improve both the efficiency η, defined as the ratio of the piston crankshaft power to the fuel flow power, and the total efficiency η*, defined as the ratio of piston crankshaft power augmented of the power from the turbocharger shaft to the fuel flow power, even if of a minimal extent. The energy supply to the crankshaft is possible mostly at high speeds and high loads, where otherwise the turbine could have been waste gated, and during decelerations. The use of the energy at the turbine otherwise waste gated translates in improvements of the total fuel conversion efficiency η* more than the efficiency η. Much smaller improvements are obtained for the maximum torque, yet again moving closer to the points of operation of a balanced turbocharger. Adopting a much larger turbocharger (target displacement x speed 30% larger than a conventional turbocharger), better torque outputs and fuel conversion efficiencies η* and η are possible at every speed vs. the engine with a smaller, balanced turbocharger. This result motivates further studies of the mechanism that may considerably benefit traditional powertrains based on diesel engines.

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Qiu, Xu Yun, Liang Xiu Zhang, Hui Jun Wang, and Yong Hui Liu. "Research on Power Matching of Automatic Variable Transmission." Applied Mechanics and Materials 427-429 (September 2013): 1246–49. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.1246.

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Automatic Variable Transmission (AVT) is composed of a metal belt CVT unit and a step speed changing transmission component. According to the needs of automotive conditions, AVT can realize continuously variable transmission and gear transmission, which not only play the advantage of gear transmission efficiency, but also overcome the deficiency of CVT when it is in high-speed. In the paper, the transmission matching rule is introduced, and engine model is established using engine test data. Based on SimulationX software, a vehicle that equips AVT is used for modeling and simulation. Finally the power matching is researched.

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Ye, Chao, Ting You Wang, and Ye Yuan. "Design of Small Variable Frequency Speed Regulation System Based on ARM." Applied Mechanics and Materials 635-637 (September 2014): 1155–58. http://dx.doi.org/10.4028/www.scientific.net/amm.635-637.1155.

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This paper presents a small ARM-based frequency control system, the voltage 220V/50Hz mains, rectified, filtered into DC, then reverse into adjustable frequency alternating current supplied to the motor used. Through software algorithms SPWM control signal generated by the microcontroller, the control signal sent through the intelligent power module, the realization of the DC inverter process. The design is simple, functional and meet the current frequency control system, modular, digital trends, has a waveform, small size, high efficiency, frequency wide range of features. Has good practical value and low cost.

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Ma, Lei, Masayuki Sanada, Shigeo Morimoto, and Yoji Takeda. "Extended Operating Range and High Efficiency Adjustable Speed Control of IPMSM with Variable PM Armature Flux Linkage." IEEJ Transactions on Industry Applications 120, no. 8-9 (2000): 1031–36. http://dx.doi.org/10.1541/ieejias.120.1031.

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Ha, Keunsoo, Cheewoo Lee, Jaehyuck Kim, R. Krishnan, and Seok-Gyu Oh. "Design and Development of Low-Cost and High-Efficiency Variable-Speed Drive System With Switched Reluctance Motor." IEEE Transactions on Industry Applications 43, no. 3 (2007): 703–13. http://dx.doi.org/10.1109/tia.2007.895744.

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Zhao, Xin, Xiangdong Ni, Qi Wang, Mingxi Bao, Sheng Li, and Shuangman Han. "Research on adaptive control strategy of hydraulic mechanical continuously variable transmission of a cotton picker." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 17 (2020): 3335–45. http://dx.doi.org/10.1177/0954406220916536.

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Hydraulic mechanical continuously variable transmission has the advantages of good hydraulic stepless speed regulation performance and high efficiency of mechanical transmission, which can achieve the optimal matching of transmission system load and power source. In this article, an adaptive control strategy based on radial basis function neural network and proportional–integral–derivative control was proposed. The speed compound control method was used to solve the problems that the output speed of the hydraulic mechanical continuously variable transmission system was poor at the variable speed input and was difficult to control. The throttle opening and the engine speed were used as controller inputs. The pump–motor's displacement ratio and the output speed were used as controller outputs. Finally, the output speed of the cotton picker was stably controlled. Simulation and experimental results show that the transmission can quickly respond to the target speed and had little fluctuation based on different initial input speeds. The control strategy had good control precision and robustness. Compared with the traditional proportional–integral–derivative algorithm, the average steady-state error of the system output speed was controlled between ±0.0125%. The proposed algorithm based on radial basis function neural network proportional–integral–derivative adaptive control strategy had obvious control effect, and the stability of the speed output of the system was improved under the nonlinear input complex conditions. It provided research for the speed ratio adjustment and control of the hydraulic mechanical continuously variable transmission of the cotton picker.

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Qiu, Lemiao, Huifang Zhou, Zili Wang, Wenqian Lou, Shuyou Zhang, and Lichun Zhang. "A Stepped-Segmentation Method for the High-Speed Theoretical Elevator Car Air Pressure Curve Adjustment." Energies 13, no. 10 (2020): 2585. http://dx.doi.org/10.3390/en13102585.

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As the demand for high-speed elevators grows, the requirements of elevator performance have also increased. Most of these are single variables that do not consider the comprehensive impact of multiple variables on performance, especially comfort. To overcome this problem, a stepped segmentation method for a theoretical high-speed elevator car air pressure curve (THEC-APC) adjustment is proposed that could actively help to select a suitable theoretical elevator car air pressure adjustment curve. By utilizing the proposed Particle Swarm Optimization (PSO) algorithm, the theoretical elevator car air pressure curve is optimized for multiple performances (including passenger comfort, energy consumption, and aerodynamic characteristics). In addition, the THEC-APC is smoothed by the Bezier curve for the variable destination floor. To verify the proposed method, the KLK2 (Canny Elevator Co., Ltd., 2015, Suzhou) high-speed elevator design process is applied. The numerical experiment results show that the proposed method can improve the accuracy and search efficiency of the optimal solution. Meanwhile, the proposed method helps to promote further air pressure compensation design for high-speed elevators.

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Khramshina, Ekaterina A., Alexander S. Karandaev, and Rifkhat R. Khramshin. "Improving Energy Efficiency of the Variable Frequency Drive of the Forced-Draught Fan with the Two-Speed Asynchronous Motor." Applied Mechanics and Materials 792 (September 2015): 128–33. http://dx.doi.org/10.4028/www.scientific.net/amm.792.128.

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Based on the example of forced-draught fans of the GOFHWB-100 series hot water boilers (gas and oil fired hot water boilers) power supply reserves of the electric drive with two-speed asynchronous motor have been determined. The structural chart of the developed control system of the electric drive with winding changeover depending on the boiler performance is provided. The paper considers power consumption of electric drive in the variable frequency speed control mode at the motor operation on the high and low speed windings. It presents methods for calculation of energy performance based on computing the equivalent efficiency of the fluid-handling application. The analysis of the efficiency change has proved that the variable frequency control enables electric power savings at the low speed winding by 5 to 6%. The results obtained are recommended to be widely applied at the change-over of the electric drives with two-speed asynchronous motors to the variable frequency control of performance.

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Jin, Xing, Chang Hong Jiang, and Xiang Guang Li. "A Study on Variable Frequency Control of Precooling Pump Motors." Applied Mechanics and Materials 325-326 (June 2013): 1233–36. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.1233.

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Based on the energy-saving principle of variable frequency and energy adjustment, problems on application of the optimization table method of voltage vector in AC frequency control of motor speed adjusting are mainly emphasized by analysis on precooling system of air separation in this paper. With the help of Matlab/Simulink simulation software, the simulation model of the control system of the AC induction motor is built, and a method of frequency and speed adjusting control of the motor based on dsPIC is put forward. Furthermore, this technology is applied in the precooling pump system of air separation, and a full digital SPWM variable frequency and speed adjusting system with low energy consumption, high efficiency and good dynamic is constructed.

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Chen, Weixing, Feng Gao, Xiangdun Meng, Anye Ren, and Songlin Zhou. "An offshore hydraulic wind turbine generator with variable-diameter rotor: Design, modeling and experiment." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 231, no. 2 (2016): 521–32. http://dx.doi.org/10.1177/1475090216661449.

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Offshore wind power is more abundant and stronger than the onshore, and more and more research enthusiasms have been raised in recent years. However, there are still many issues in the utilization of the offshore wind power such as the cost of installations and maintenance and the ability to resist extreme weather conditions. In this article, an offshore hydraulic wind turbine generator with variable-diameter rotor is presented. The diameter of the rotor can be regulated according to the wind speeds to achieve the maximum power coefficient. The hydraulic energy working as the transmission medium can improve the output power quality. The high-speed gearbox is removed, and the generator is installed on the platform, which facilitates the installations and maintenance. Here, the power conversion principle of the wind turbine generator was introduced first. Then, the dynamics and performance of the wind turbine generator was obtained. The relationship between the diameter of the rotor and the wind speed was established according to the dynamics and the optimum tip-speed ratio. Relying on the specific parameters, the dynamic response was calculated in Simulink. The results show that the instantaneous output of the wind turbine generator is relatively stable. Based on the power recovery method, the test platform was built, and the efficiency of the energy conversion device was tested. The experimental results demonstrate that the efficiency of the energy conversion device can be 88%. Finally, the total efficiency of the offshore hydraulic wind turbine generator was predicted to be 33.7%.

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Dhand, Aditya, and Keith Pullen. "Analysis of continuously variable transmission for flywheel energy storage systems in vehicular application." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 2 (2014): 273–90. http://dx.doi.org/10.1177/0954406214533096.

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Energy storage devices are an essential part of hybrid and electric vehicles. The most commonly used ones are batteries, ultra capacitors and high speed flywheels. Among these, the flywheel is the only device that keeps the energy stored in the same form as the moving vehicle, i.e. mechanical energy. In order to connect the flywheel with the vehicle drive line, a suitable means is needed which would allow the flywheel to vary its speed continuously, in other words a continuously variable transmission (CVT) is needed. To improve the efficiency and speed ratio range of the variators, a power spilt CVT (PSCVT) can be employed. This paper discusses the kinematics of PSCVT used to connect the flywheel to the driveline. A methodology describing the characteristic equations of speed ratio, power flow and efficiency of the PSCVT for various types including power recirculating and multi regime in both directions of power flow has been presented. An example of a PSCVT for a flywheel energy storage system (FESS) is computed using the derived equations and the results compared.

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Song, En Zhe, Chang Xi Ji, Mei Liang Yin, Jun Sun, and Cheng Shun Yin. "Simulation Study on Travel-Driven System of HST Loader with Matlab/Simulink." Applied Mechanics and Materials 313-314 (March 2013): 1100–1104. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.1100.

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This paper establishes the mathematical model of the volume speed-modulating system and simulates dynamically with Matlab/Simulink. Provide a theoretical basis for algorithm of close loop control [ of the three variables which are diesel engines, variable pump and variable motor. Use PID control algorithm, through simulation and analysis, find out the parameter optimization adjustment rule [2,, seek matching operation between three variables. Provide a theoretical basis for the study on dynamic system of full-hydraulic loaders and have very important practical significance in realizing high efficiency energy saving and reducing energy consumption.

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Liu, Yong Hui, Hui Jun Wang, Xu Yun Qiu, and Ying Ling Du. "The Study on the System Dynamics Characteristics of Automatic Variable Transmission." Applied Mechanics and Materials 568-570 (June 2014): 1041–44. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.1041.

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In this paper, a new automatic variable transmission (AVT) is studied. This AVT is made up of two parts, which include the metal belt continuously variable transmission (CVT) and gear transmission. And the CVT mode is used in the low speed and the gear transmission is used in the high speed. The software ofsimulationXis used to build a simulation model for the AVT vehicle, and the system dynamics characteristics of AVT are studied via this model. Compared to the CVT vehicle in terms of the maximum speed, the accelerate time and fuel consumption, the AVT vehicle develops the advantage of CVT in the low load and improves the weakness of low power in the high load. The results of this paper show that the AVT vehicle has good dynamics performance at the whole work area, which can advance the transmission efficiency and improve the fuel economy of the vehicle.

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Chudzik, Stanisław. "Model of a Wind Turbine with Variable Blade Angle." Pomiary Automatyka Robotyka 25, no. 1 (2021): 41–48. http://dx.doi.org/10.14313/par_239/41.

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The article presents the results of research into the operation of a model of a wind micropower plant with a variable blade angle. The research was carried out on a miniature model of a measuring stand built for the purpose of carrying out work on pre-developed projects of wind micro power plants. The stand allows to carry out measurements related to the selection of the optimal propeller geometry, as well as the development and testing of algorithms for optimal control of the micropower plant. The physical basics of wind turbine operation and the methods of its optimal control are presented. The results of the performed measurements for the selected propeller blade geometry with the possibility of changing its setting angle are presented. A DC generator with a load with a non-linear characteristic in the form of a Li-Po battery cell was used. The results of operation of a simple MPPT control algorithm are presented. The lack of optimal control systems for the operation of micropower plants is dictated by the general belief that the costs of its production are high in relation to the possible improvement of the efficiency of micropower plants. Moreover, the practical methods of controlling larger wind turbines are not optimal for small and very small turbines. The conducted research focused on determining the possibility of using turbines with variable blade angles depending on its rotational speed. In larger wind farms, changing the blade angle is mainly used to limit the power of the turbine at high wind speeds. In micro wind power plants such solutions are not used for economic reasons. However, the use of a simple mechanism for changing the angle of the blades depending on the rotational speed of the propeller can increase the efficiency of the turbine in a wider range of wind speeds. The small dimensions of the research model allow for quick and cheap development of preliminary prototypes of turbine blades thanks to the possibility of using 3D printing technology.

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Chen, Du, Feng Kang, Qing Yuan Zhu, and Shu Mao Wang. "Study on Combine Harvester Speed Control Based on Optimum Threshing Power Consumption Model." Applied Mechanics and Materials 130-134 (October 2011): 1911–14. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.1911.

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Combine harvester have to be operated in a wide range of field condition which may induce varying feeding rate. Forward speed is a main variable to control the feeding rate of combine harvester for high efficiency. In this study a control strategy based on optimum threshing power consumption model was developed and integrated into a speed control system for combine harvester automation. A conventional self-propelled combine harvester (Xinjiang-II) was equipped with multiple sensors to collect online information, including forward speed, threshing drum torque and speed. Forward speed was then adjusted by an electric-hydraulic unit based on designed PID controller to achieve an optimum range of threshing power consumption. Field test was conducted to evaluate the performance of the controller under variable feeding rate condition. From obtained results, the controller can improve the efficiency of tested machine during field operation.

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Soo Kim, Chul, and Chung Oh Lee. "Robust Speed Control of a Variable-Displacement Hydraulic Motor Considering Saturation Nonlinearity." Journal of Dynamic Systems, Measurement, and Control 122, no. 1 (1997): 196–201. http://dx.doi.org/10.1115/1.482442.

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This paper presents the speed control of a variable-displacement hydraulic motor on a constant pressure network, which is noted for its high system efficiency, fast dynamic response, and energy recovery capability. The speed control and response characteristics of the conventional cascade PI controller are considerably affected by load torque disturbances, variations in system parameters, and input magnitude. To obtain robust speed control under such conditions, the load torque is estimated by an observer and compensated for by a feedforward loop, and a windup compensator is used to prevent windup phenomena due to saturation of the regulating piston and integral controller. It is shown by experiment that improved speed control can be obtained with the proposed controller in spite of load torque disturbances, variations in system parameters, and input magnitude. [S0022-0434(00)00401-9]

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Ram, Ganapathy, and Santha K R. "Review of Sliding Mode Observers for Sensorless Control of Permanent Magnet Synchronous Motor Drives." International Journal of Power Electronics and Drive Systems (IJPEDS) 9, no. 1 (2018): 46. http://dx.doi.org/10.11591/ijpeds.v9.i1.pp46-54.

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Permanent magnet synchronous motors (PMSMs) are increasingly used in high performance variable speed drives of many industrial applications. PMSM has many features, like high efficiency, compactness, high torque to inertia ratio, rapid dynamic response, simple modeling and control, and maintenance free operation. Presence of position sensors presents several disadvantages, such as reduced reliability, susceptibility to noise, additional cost and weight and increased complexity of the drive system. For these reasons, the development of alternative indirect methods for speed and position control becomes an important research topic. Advantages of sensorless control are reduced hardware complexity, low cost, reduced size, cable elimination, increased noise immunity, increased reliability and decreased maintenance. The key problem in sensorless vector control of ac drives is the accurate dynamic estimation of the stator flux vector over a wide speed range using only terminal variables (currents and voltages). The difficulty comprises state estimation at very low speeds where the fundamental excitation is low and the observer performance tends to be poor. Moreover, the noises of system and measurements are considered other main problems. This paper presents a comprehensive study of the different sliding mode observer methods of speed and position estimations for sensorless control of PMSM drives.

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Ding, Haigang, Henan Song, Jiyun Zhao, and Chaowen Lin. "Valve-Pump Parallel Variable Mode Control for Complex Speed Regulation Processes." Complexity 2018 (September 3, 2018): 1–9. http://dx.doi.org/10.1155/2018/8016345.

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To improve comprehensive performances of hydraulic systems with complex speed regulation processes, this paper proposes a new control scheme, valve-pump parallel variable mode control, which can change control modes according to control requirements and adjust the proportion of valve control and pump control in the speed regulation process. In this paper, we design a valve-pump parallel variable mode control system, explain its working principle, establish its mathematical model, analyse the influences of valve control on the system parameters, and at last, build an experimental system to carry out an experimental research. The experimental results show that during the speed regulation process, control modes could vary with control requirements, the switch between different control modes is smooth and meets expectations, and the proposed control approach can achieve excellent comprehensive performances for complex speed regulation, such as low-speed stability, fast response to load disturbance, and high efficiency. The valve-pump parallel variable mode control makes hydraulic control systems more flexible and suitable and enrich the current control schemes of hydraulic speed regulation systems.

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Obukhova, Elena N., Vyacheslav I. Grishchenko, and Grigoriy A. Dolgov. "Formalization of dynamic model of pneumatic drive with variable structure." MATEC Web of Conferences 226 (2018): 02022. http://dx.doi.org/10.1051/matecconf/201822602022.

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The work is devoted to solving the actual technical problem of increasing the speed and accuracy of pneumatic servo drives. Pneumatic drives have a large number of advantages (high speed of the output link, environmental friendliness, low cost, etc.). But having a high compressibility of compressed air limits the possibility of realizing optimal trajectories of motion of control objects. The complexity in the organization of controlling the follow-up pneumatic drive is also introduced by a mathematical apparatus that takes into account the thermodynamic processes during the filling and emptying of the working cavities of a pneumatic cylinder. In connection with this, the goal of this work was the development of a mathematical model of a servomotor with a variable structure that takes into account the various structures of pneumatic valves with proportional control. The proposed mathematical model will make it possible to use the synergetic approach in controlling the pneumatic drive. This makes it possible to take into account not less important drive parameters such as energy efficiency, etc., with increasing speed and accuracy of the drive.

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Bleizgys, V., and A. Baskys. "The Influence of Supply Voltage Amplitude Variation Law on AC Induction Motor Efficiency in Variable-Speed Drive." Solid State Phenomena 164 (June 2010): 1–4. http://dx.doi.org/10.4028/www.scientific.net/ssp.164.1.

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This paper presents investigation results of the influence of the supply voltage amplitude variation law on the efficiency of AC induction motor in variable-speed drive based on the frequency converter. It is demonstrated that the commonly employed linear and square voltage amplitude variation laws do not provide the highest efficiency of the AC induction motor. The corrected AC voltage amplitude variation dependences for different motor load torque, at which high efficiency of the motor supplied by the frequency converter is maintained, are proposed and discussed. Reported experimental study was performed on a special test bench.

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Han, Wei, Ting Shang, Min Su, Chengyong Gong, Rennian Li, and Bin Meng. "Direct Sailing Variable Acceleration Dynamics Characteristics of Water-Jet Propulsion with a Screw Mixed-Flow Pump." Applied Sciences 9, no. 19 (2019): 4194. http://dx.doi.org/10.3390/app9194194.

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Strong nonlinearity and the relevance of time-varying dynamic parameters in the maneuverable process of water-jet propulsion were major problems encountered in the prediction of variable acceleration dynamics characteristics. The relationships between the thrust and rotation speed of a screw mixed-flow pump, drag and submerged speed of water-jet propulsion were obtained from flume experiments and numerical calculations, based on which a dynamic model of pump-jet propulsion was established in this paper. As an initial condition, the numerical solution of the submerged speed with respect to time was inputted to computational fluid dynamics (CFD) for unsteady calculation based on a user-defined function (UDF). Thus, the relationships between the acceleration, drag, net thrust, propulsion torque and efficiency with respect to time were revealed. The results indicate that the relationship between the thrust and rotational speed of a water-jet propeller is a quadratic function, which agrees well with the experimental values. The variation of submerged speed with respect to time satisfies a hyperbolic tangent function distribution. The acceleration increases sharply at the beginning and then decreases gradually to zero, especially at high rotation speeds of the water-jet pump. The variations in drag and propulsion efficiency with respect to time coincide with the step response of a second-order system with critical damping. The method and results of this study can give a better understanding of the changes in dynamic parameters such as velocity, acceleration, thrust, and drag during the acceleration of a pump-jet submersible and helped to estimate the effects of pump performance on water-jet propulsion kinetic parameters.

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Kilicaslan, Ibrahim, and Engin Ozdemir. "Energy Economy With a Variable Speed Drive in an Oxygen Trim Controlled Boiler House." Journal of Energy Resources Technology 127, no. 1 (2005): 59–65. http://dx.doi.org/10.1115/1.1849227.

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This paper investigates the potentional for energy saving in a boiler house that can be achieved through installing a variable speed drive (VSD) for the fan motor by including an oxygen trim control cycle. This investigation is carried out through surveys; energy saving calculations are based on experimental data. In particular, some unique energy saving measures and energy efficiency improvements in the boiler associated with the VSD system are analytically and experimentally studied. In this study, the relation between excess air ratio and boiler efficiency was investigated in a water tube boiler that has the capacity of producing 55 tons of steam per unit time at 245°C and 20 bar pressure. The boiler combustion air is supplied from a fan driven by a 30 kW 1450 rpm induction motor. Since the fan motor running at nominal speed has supplied the same airflow rate, excess air amount and exhaust gas temperature were very high at low loads. The boiler efficiency was low due to thermal energy losses and also consequently led to electrical energy losses. After implementation of the VSD, stack temperature was reduced from 200°C to 142°C, so the boiler efficiency was increased about 2.5% and 8000 kWh of electrical energy were saved in a month. The energy losses associated with excess air rate and its cost to manufacturers are evaluated and quantified. An overview and analysis of such conservation measures, along with the potential energy and cost savings, the implementation cost, and simple payback period are also given.

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Mutlu, Mustafa, and Muhsin Kiliç. "Effects of piston speed, compression ratio and cylinder geometry on system performance of a liquid piston." Thermal Science 20, no. 6 (2016): 1953–61. http://dx.doi.org/10.2298/tsci140926146m.

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Energy storage systems are being more important to compensate irregularities of renewable energy sources and yields more profitable to invest. Compressed air energy storage (CAES) systems provide sufficient of system usability, then large scale plants are found around the world. The compression process is the most critical part of these systems and different designs must be developed to improve efficiency such as liquid piston. In this study, a liquid piston is analyzed with CFD tools to look into the effect of piston speed, compression ratio and cylinder geometry on compression efficiency and required work. It is found that, increasing piston speeds do not affect the piston work but efficiency decreases. Piston work remains constant at higher than 0.05 m/s piston speeds but the efficiency decreases from 90.9 % to 74.6 %. Using variable piston speeds has not a significant improvement on the system performance. It is seen that, the effect of compression ratio is increasing with high piston speeds. The required power, when the compression ratio is 80, is 2.39 times greater than the power when the compression ratio is 5 at 0.01 m/s piston speed and 2.87 times greater at 0.15 m/s. Cylinder geometry is also very important because, efficiency, power and work alter by L/D, D and cylinder volume respectively.

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Doder, Dragan, and Radoslava Doder. "The effect of anthropological characteristics on the efficiency of execution of forward kick." Zbornik Matice srpske za prirodne nauke, no. 111 (2006): 45–54. http://dx.doi.org/10.2298/zmspn0611045d.

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A sample of eighty-two karatists at the ages from ten to fourteen has been analyzed for a system of 25 variables (12 morphological, 12 basic motoric variables and 1 specific motoric variable) with the aim of establishing the effect of prediction system of morphological variables and a system of basic motoric variables on the criterion variable, i.e., the direct forward kick - mae geri. The obtained results showed that the system of morphological variables had a statistically significant effect on the execution of direct forward kick. Among the individual variables in the regression analysis body weight had the largest effect. The stepwise method showed that body height and weight had highest prediction values. Young karatists of high body height, with long extremities and increased weight, had better results in the execution of direct forward kick. The investigation of basic motoric variables used in the regression and stepwise analyses indicated that the endurance in half-squat with weight and standing jump had statistically significant effects on the efficiency of direct forward kick. Thus it was concluded that the speed of forward kick depends on the explosive and static strength of legs.

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Abe, Takashi, Ryohei Ohba, and Tsuyoshi Higuchi. "Fundamental characteristics and first prototype of a novel claw pole type half-wave rectified variable field flux motor." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 35, no. 2 (2016): 407–23. http://dx.doi.org/10.1108/compel-02-2015-0102.

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Purpose – Recently, considerable attention has been attracted to the development of the new concept motor for EV or HEV. Wider torque and speed controllable operating range and high efficiency under driving area are needed for traction motor. The purpose of this paper is to realize the new concept variable field flux motor with claw pole rotor and brushless robust structure for high-speed range. Design/methodology/approach – In the previous paper, the authors proposed a half-wave rectified brushless variable field flux method with a diode inserted into the field winding. This paper presents a designing for a novel claw pole rotor type motor using the variable field flux method (CP-HVFM). The claw pole type rotor has simple and robust structure for high-speed operation. This paper describes a first prototype design result for CP-HVFM using 3D-FEM. And the authors report the torque and efficiency characteristic results using 3D-FEM. Findings – The authors have studied the designing for CP-HVFM using 3D-FEM. The designed prototype CP-HVFM reached a rated power of 2 kW or more at a rated speed 1,800 rpm under design restrictions of experimental equipment and initial specifications. In addition, the authors found the ratio of the tip and root embrace of the claw pole shape for maximum average torque and minimum torque ripple. Finally, the authors revealed an influence of the armature current on the torque and the efficiency characteristic results for the designed prototype CP-HVFM using 3D-FEM. Originality/value – The half-wave rectified brushless variable field flux method proved to be effective for the claw pole rotor type motor. And also the authors found the best claw pole shape for torque characteristic. This results are applied to another concept motor for EV or HEV.

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Toumi, Mohamed, Abderrahim Maizate, Mohammed Ouzzif, and Med Said Salah. "Dynamic Clustering Algorithm for Tracking Targets with High and Variable Celerity (ATHVC)." Journal of Computer Networks and Communications 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/7631548.

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Target tracking with the wireless sensors networks is to detect and locate a target on its entire path through a region of interest. This application arouses interest in the world of research for its many fields of use. Wireless sensor networks, thanks to their versatility, can be used in many hostile and inaccessible to humans environments. However, with a limited energy, they cannot remain permanently active, which can significantly reduce their lifetime. The formation of a cluster network seems an effective mechanism to increase network lifetime. We propose to build optimal dynamic clusters on the target trajectory. For increasing energy efficiency, our algorithm integrates for the first time, to our knowledge, strategies to avoid overlapping clusters and a model to wake up the sensors, adapting to the context of targets with large and variable speed.

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Afonso, F., J. Vale, É. Oliveira, F. Lau, and A. Suleman. "Non-linear aeroelastic response of high aspect-ratio wings in the frequency domain." Aeronautical Journal 121, no. 1240 (2017): 858–76. http://dx.doi.org/10.1017/aer.2017.29.

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ABSTRACTA current trend in the aeronautic industry is to increase the wing aspect ratio to enhance aerodynamic efficiency by reducing the induced drag and thus reduce fuel consumption. Despite the associated benefits of a large aspect ratio, such as higher lift-to-drag ratios and range, commercial aircraft usually have a relatively low aspect ratio. This is partially explained by the fact that the wing becomes more flexible with increasing aspect ratio and thus more prone to large deflections, which can cause aeroelastic instability problems such as flutter. In this work, an aeroelastic study is conducted on a rectangular wing model of 20 m span and variable chord for a low subsonic speed condition to evaluate the differences between linear and non-linear static aeroelastic responses. Comparisons between linear and non-linear displacements, natural frequencies and flutter boundary are performed. An in-house non-linear aeroelastic framework was employed for this purpose. In this work, the influence of the aspect ratio and geometric non-linearity (highly deformed states) is assessed in terms of aeroelastic performance parameters: flutter speed and divergence speed. A nearly linear correlation of flutter speed difference (relative to linear analysis results) with vertical-tip displacement difference is observed. The flutter and divergence speeds vary substantially as the wing aspect ratio increases, and the divergence speeds always remain above the flutter speed. Furthermore, the flutter mechanism was observed to change as the wing chord is decreased.

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Lisiecka, Katarzyna, and Agnieszka Wójtowicz. "The Production Efficiency and Specific Energy Consumption During Processing of Corn Extrudates with Fresh Vegetables Addition." Agricultural Engineering 23, no. 2 (2019): 15–23. http://dx.doi.org/10.1515/agriceng-2019-0012.

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AbstractThe aim of the work was to determine the influence of screw speed and variable amounts of fresh vegetable additives on selected aspects of extrusion-cooking of corn-vegetable blends. Corn grit as a basic component was supplemented with a fresh pulp of beetroot, carrot, leek and onion in amounts of 2.5-10% in the recipe. The extrusion-cooking was carried out using a single-screw extruder in the temperature range 120-145°C and extrudates were formed into directly expanded snacks. Two indicators were measured: the production efficiency (Q) and the specific mechanical energy (SME) consumption. As a result of the findings it was noted that the rotational speed of the extruder’s screw showed a greater impact on both production efficiency and SME as compared to the variable amounts of applied additives. A tendency to increased efficiency and specific mechanical energy consumption was observed along with the increase of screw speed during processing. The highest production efficiency was observed if fresh leek and onion were used as additives and the highest extrusion speed screw was applied. The largest specific energy consumption was noted during the extrusion-cooking of blends containing fresh carrot and onion addition at high screw speed.

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Qu, Jin Yu, Dong Wang, Yi Rui Zhang, and Gui Xin Qu. "Modeling and Simulation of Electric-Hydraulic Clutch on Light Vehicle." Advanced Materials Research 383-390 (November 2011): 2377–82. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.2377.

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With high efficiency, simple structure and low cost, Automatic Mechanical Transmission (AMT) is suitable for the development and application of light vehicles. The control of clutch is emphasized on in the shifting process. It is necessary to study the control of engagement speed. In this paper, the electric-hydraulic clutch applied on light vehicles is modeled and the engagement process of clutch during vehicle starting simulated. After analyzing the operation quality of clutch with different engagement speeds, the speed variable control strategy is proposed. According to the strategy, engagement speed changes with the development of different operating stages. At last, the simulation is carried out to verify the feasibility and superiority of this kind of strategy.

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Biskup, Tomasz. "Recovery braking of variable-structure electronic commutator for BLDC motor." Archives of Electrical Engineering 61, no. 4 (2012): 579–96. http://dx.doi.org/10.2478/v10171-012-0043-x.

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Abstract Permanent magnet motors are more and more frequently used in various applications. In this group motors with a trapezoidal EMF deserve a special attention. They are characterized by a simple construction, high efficiency and high torque overload. A certain drawback of BLDC motors are difficulties with an operation at a speed above the nominal value. The article presents the results of investigations into the variablestructure electronic commutator designed for the drive of a small electric vehicle equipped with BLDC motors. Such a solution allows extending the standard range of the drive’s speed. The considerations contained in the article focus on the possibilities and effects of regeneration mode in the proposed topology of converter. A theoretical analysis has been presented as well as computer simulations carried out by means of Matlab- Simulink, which were then verified at a laboratory. The tests were finished with trials conducted using a small electric vehicle Elipsa.

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