检索结果-南通市图书馆

Pitch link loads reduction of variable speed rotors by variable tuning frequency fluidlastic isolators

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第5期28卷 1408-1415页

作者： Han Dong National Key Laboratory of Science and Technology on Rotorcraft Aeronautics College of Aerospace EngineeringNanjing University of Aeronautics and Astronautics

To reduce the pitch link loads of variable speed rotors, variable tuning frequency fluid- lastic isolators are proposed. This isolator utilizes the variation of centrifugal force due to the change of rotor speed to change the tuning port area ratio, which can change the tuning frequency of the isolator. A rotor model including the model of fluidlastic isolator is coupled with a fuselage model to predict the steady responses of the rotor system in forward flight. The aeroelastic analyses indicate that distinct performance improvement in pitch link load control can be achieved by the utilization of variable frequency isolators compared with the constant tuning frequency isolators. The 4/rev （per revolution） pitch link load is observed to be reduced by 87.6% compared with the increase of 56.3% by the constant frequency isolator, when the rotor speed is reduced by 16.7%. The isolation ability at different rotor speeds in different flight states is investigated. To achieve overall load reduction within the whole range of rotor speed, the strategy of the variation of tuning frequency is adjusted. The results indicate that the 4/rev pitch link load within the whole rotor speed range is decreased.

关键词： Fluidlastic isolator Loads Pitch link Reduction Rotor variable frequency variable speed

Optimum control strategy for all-variable speed chiller plant

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2011年第2期18卷 573-579页

作者：蒋小强龙惟定李敏 College of Engineering Guangdong Ocean University College of Mechanical Engineering Tongji University Sino-German School of Applied Sciences Tongji University

The optimum control strategy and the saving potential of all variable chiller plant under the conditions of changing building cooling load and cooling water supply temperature were investigated. Based on a simulation model of water source chiller plant established in dynamic transient simulation program (TRNSYS),the four-variable quadratic orthogonal regression experiments were carried out by taking cooling load,cooling water supply temperature,cooling water flow rate and chilled water flow rate as variables,and the fitting formulas expressing the relationships between the total energy consumption of chiller plant with the four selected parameters was obtained. With the SAS statistical software and MATHEMATICA mathematical software,the optimal chilled water flow rate and cooling water flow rate which result in the minimum total energy consumption were determined under continuously varying cooling load and cooling water supply temperature. With regard to a chiller plant serving an office building in Shanghai,the total energy consumptions under different control strategies were computed in terms of the forecasting function of cooling load and water source temperature. The results show that applying the optimal control strategy to the chiller plant can bring a saving of 23.27% in power compared with the corresponding conventional variable speed plant,indicating that the optimal control strategy can improve the energy efficiency of chiller plant.

关键词： chiller plant control strategy variable speed cooling water flow rate chilled water flow rate

Intelligent control for large-scale variable speed variable pitch wind turbines

在线全文

学校读者我要写书评

暂无评论

控制理论与应用（英文版） 2004年第3期2卷 305-311页

作者： XinfangZHANG DapingXU YibingLIU DepartmentofAutomaticControl NorthChinaElectricPowerUniversityBeijing102206China

Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances. Automatic control is crucial for the efficiency and reliability of wind turbines. On the basis of simplified and proper model of variable speed variable pitch wind turbines, the effective wind speed is estimated using extended Kaiman filter. Intelligent control schemes proposed in the paper include two loops which operate in synchronism with each other. At below-rated wind speed, the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture. At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power. The simulation shows the effectiveness of the intelligent control.

关键词： Wind turbines Adaptive fuzzy control Least square support vector machine variable speed variable pitch

Model predictive control of indoor thermal environment conditioned by a direct expansion air conditioning system

在线全文

学校读者我要写书评

暂无评论

Building Simulation 2023年第3期16卷 357-378页

作者： Yudong Xia Ming Zhu Aipeng Jiang Jian Wang Xiaoxia Bai Shiming Deng School of Automation(School of Artificial Intelligence) Hangzhou Dianzi UniversityHangzhouChina Department of Building Environment and Energy Engineering The Hong Kong Polytechnic UniversityHong KongChina Department of Mechanical and Industrial Engineering Qatar UniversityDohaQatar

Temperature and humidity are two important factors that influence both indoor thermal comfort and air *** varying compressor and supply fan speeds of a direct expansion(DX)air conditioning(A/C)unit,the air temperature and humidity in the conditioned space can be regulated ***,most existing controllers are designed to minimize the tracking errors between the system outputs with their corresponding settings as quickly as *** energy consumption,which is directly influenced by the compressor and supply fan speeds,is not considered in the relevant controller formulations,and thus the system may not operate with the highest possible energy *** effectively control temperature and humidity while minimizing the system energy consumption,a model predictive control(MPC)strategy was developed for a DX A/C system,and the development results are presented in this paper.A physically-based dynamic model for the DX A/C system with both sensible and latent heat transfers being considered was established and validated by *** facilitate the design of MPC,the physical model was further *** MPC scheme was then developed by formulating the objective function which sought to minimize the tracking errors of temperature and moisture content while saving energy *** on the results of command following and disturbance rejection tests,the proposed MPC scheme was capable of controlling temperature and humidity with adequate control accuracy and *** comparison to linear-quadratic-Gaussian(LQG)controller,better control accuracy and lower energy consumption could be realized when using the proposed MPC strategy to simultaneously control temperature and humidity.

关键词： direct expansion air conditioning humidity control model predictive control variable speed operational efficiency

Thermal management for thermoset automated fiber placement based on infrared heater structure arrangement

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第1期35卷 173-183页

作者： Han WANG Weiwei WANG Haijin WANG Huiyue DONG Yinglin KE A State Key Laboratory of Fluid Power and Mechatronic System School of Mechanical EngineeringZhejiang UniversityHangzhou 310027China Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province School of Mechanical EngineeringZhejiang UniversityHangzhou 310027China

Layup temperature is a vital factor that affects the production quality of automated fiber placement for thermoset *** high quality production,this paper proposes a new prediction model of layup temperature by considering the structure of infrared heater of automatic fiber placement *** model was first verified by comparing with the temperature results of layup *** a prediction on the effects of heater structure arrangement on layup temperature was conducted in the *** research shows that the length of infrared tube and the radian of reflective-film have significant influences,rather than other *** to this investigation,a heater structure-based heating strategy was presented in the paper to efficiently achieve constant temperature control in variable speed layup process.

关键词： Automated fiber placement Heating strategy optimization Infrared heater structure Thermal management variable speed

Study of corrective abrasive finishing for plane surfaces using magnetic abrasive finishing processes

在线全文

学校读者我要写书评

暂无评论

Nanotechnology and Precision Engineering 2021年第3期4卷 1-11页

作者： Yulong Zhang Yanhua Zou Graduate School of Engineering Utsunomiya University7-1-2YotoUtsunomiyaTochigi 321-8585Japan

On the basis of ordinary plane magnetic abrasive finishing,a finishing method is proposed that can improve the flatness of a plane *** this method,the feed speed is varied during finishing according to the profile curve of the initial surface and the material removal efficiency,to control the effective finishing time in different areas and thereby improve the surface flatness.A small magnetic pole with an end face diameter of 1 mm is designed,and a ferromagnetic plate is placed under the workpiece to improve the uniformity of the magnetic field distribution near the magnetic *** experiment on an A5052 aluminum alloy plate workpiece shows that after 60 min of finishing using the proposed method,the extreme difference of the workpiece surface can be reduced from 14.317μm to 2.18μm,and the standard deviation can be reduced from 3.322μm to 0.417μ*** the same time,according to the measurement results,a similar flatness can be achieved at different positions on the finishing ***,the proposed variable-speed finishing method leads to obvious improvements in flatness.

关键词： variable speed Magnetic abrasive finishing Corrective abrasive finishing Finishing efficiency Surface flatness Aluminum alloy(A5052)

OPTIMAL DESIGN OF DUAL STATOR-WINDING INDUCTION GENERATOR WITH PWM CONVERTER

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2006年第3期23卷 185-193页

作者：刘陵顺胡育文黄文新南京航空航天大学航空电源航空科技重点实验室

To minimize the reactive power of the converter of the control winding in the novel dual stator-winding induction generator based on the PWM converter, design features of the induction generator with a rectified load are proposed. The optimization method of excited capacitors to minimize the reactive power of the control winding at a variable speed is given. The calculation capacity of the machine with a diode bridge rectifier load is proposed. To achieve global searching, the integrated method with the improved real-coded genetic algorithm and the twodimensional finite element method （FEM） is introduced. Design results of the sample show that reactive power can be reduced by the method, and the converter capacity can be decreased to 1/3 of output rated power at the speed ratio of 1 ： 3, thus reducing the volume and the mass of the inverter.

关键词： dual stator-winding induction generator variable speed PWM converter genetic algorithm FEM optimal design

Advanced Control of a PMSG Wind Turbine

在线全文

学校读者我要写书评

暂无评论

International Journal of Modern Nonlinear Theory and Application 2016年第1期5卷 1-10页

作者： Hafsi Slah Dhaoui Mehdi Sbita Lassaad National Engineering School of Gabes Photovoltaic Wind and Geothermal Systems Research Gabes Tunisia

In this work, an intelligent artificial control of a variable speed wind turbine (PMSG) is proposed. First, a mathematical model of turbine written at variable speed is established to investigate simulations results. In order to optimize energy production from wind, a pitch angle and DC bus control law is synthesized using PI controllers. Then, an intelligent artificial control such as fuzzy logic and artificial neural network control is applied. Its simulated performances are then compared to those of a classical PI controller. Results obtained in MATLAB/Simulink environment show that the fuzzy and the neuro control is more robust and has superior dynamic performance and hence is found to be a suitable replacement of the conventional PI controller for the high performance drive applications.

关键词： Wind Turbine variable speed Pitch Angle Pi Controller Fuzzy Logic Controller Neural Networks Controller

A New Formula of Redshift vs. Space Expansion and Dark Energy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Physics 2021年第3期12卷 229-253页

作者： Olivier Serret ESIM Engineer Cugnaux France

The speed away of stars and galaxies is traditionally calculated from the relativistic formula according to the measurement of the redshift. It is demonstrated here another formula for this speed away of stars and galaxies, from this same redshift z. After having exposed critiques on the demonstration and the relativistic use which require the assumption of an expanding universe by itself, it is proposed within the framework of neo-Newtonian mechanics the formula where V is the speed from the source. This formula has the double characteristic of being equivalent to relativistic predictions for low redshifts, but of deviating from them by up to 17% for high redshifts. It is consistent with the observation of the anisotropy of the Universe and the Cosmic Microwave Background. It helps to explain Pioneer anomalies. It is compatible with the constancy in the majority of cases of interference phenomena. Finally, it provides a new analysis grid for the observation of supernovae, galaxies and distant pulsars, thus opening up new fields of research on the increase in distances attributed to dark energy and also in other areas of the cosmology.

关键词： Redshift Blueshift Dark Energy Radial Velocity Expansion of the Universe Anisotropy Hubble Law Pioneer Spacecraft Photon Wavelength Frequency variable speed Celerity of Light