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| 1 | An adaptive turbo-shaft engine modeling method based on PS and MRR-LSSVR algorithms显示文摘In order to establish an adaptive turbo-shaft engine model with high accuracy, a new modeling method based on parameter selection (PS) algorithm and multi-input multi-output recursive reduced least square support vector regression (MRR-LSSVR) machine is proposed. Firstly, the PS algorithm is designed to choose the most reasonable inputs of the adaptive module. During this process, a wrapper criterion based on least square support vector regression (LSSVR) machine is adopted, which can not only reduce computational complexity but also enhance generalization performance. Secondly, with the input variables determined by the PS algorithm, a mapping model of engine parameter estimation is trained off-line using MRR-LSSVR, which has a satisfying accuracy within 5&. Finally, based on a numerical simulation platform of an integrated helicopter/ turbo-shaft engine system, an adaptive turbo-shaft engine model is developed and tested in a certain flight envelope. Under the condition of single or multiple engine components being degraded, many simulation experiments are carried out, and the simulation results show the effectiveness and validity of the proposed adaptive modeling method. | Wang Jiankang Zhang Haibo Yan Changkai Duan Shujing Huang Xianghua | 2013 | Chinese Journal of Aeronautics2013，26，1： | 5 |
| 2 | A New Hybrid Control Scheme for an Integrated Helicopter and Engine System显示文摘A new hybrid control scheme is presented with a robust multiple model fusion control(RMMFC) law for a UH-60 helicopter and an active disturbance rejection control(ADRC) controller for its engines.This scheme is a control design method with every subsystem designed separately but fully considering the couplings between them.With three subspaces with respect to forward flight velocity,a RMMFC is proposed to devise a four-loop reference signal tracing control for the helicopter,which escapes the closed-loop system from unstable state due to the extreme complexity of this integrated nonlinear system.The engines are controlled by the proposed ADRC decoupling controller,which fully takes advantage of a good compensation ability for unmodeled dynamics and extra disturbances,so as to compensate torque disturbance in power turbine speed loop.By simulating a forward acceleration flight task,the RMMFC for the helicopter is validated.It is apparent that the integrated helicopter and engine system(IHES) has much better dynamic performance under the new control scheme.Especially in the switching process,the large transient is significantly weakened,and smooth transition among candidate controllers is achieved.Over the entire simulation task,the droop of power turbine speed with the proposed ADRC controller is significantly slighter than with the conventional PID controller,and the response time of the former is much faster than the latter.By simulating a rapid climb and descent flight task,the results also show the feasibility for the application of the proposed multiple model fusion control.Although there is aggressive power demand in this maneuver,the droop of power turbine speed with an ADRC controller is smaller than using a PID controller.The control performance for helicopter and engine is enhanced by adopting this hybrid control scheme,and simulation results in other envelope state give proofs of robustness for this new scheme. | ZHANG Haibo WANG Jiankang CHEN Guoqiang YAN Changkai | 2012 | Chinese Journal of Aeronautics2012，25，4： | 2 |
| 3 | Quantitative analysis of glutamate compounds in the swine brain following central analgesics nasal spray using proton magnetic resonance spectroscopy and linear combination model显示文摘<正>BACKGROUND:In localized brain proton magnetic resonance spectroscopy(~1H-MRS),metabolite levels are often expressed as ratios,rather than absolute concentrations.Frequently,the denominator is creatine,which is assumed to be stable in normal,as well as many pathological, states.However,in vivo creatine levels do not remain constant.Therefore,absolute metabolite measurements,which provide the precise concentrations of certain chemical compounds,are superior to metabolite ratios for determining pathological and evolutional changes. OBJECTIVE:To investigate the feasibility of quantification analysis of brain metabolite changes caused by central analgesics nasal spray using the ~1H-MRS and linear combination model(LCModel) methods. DESIGN,TIME AND SETTING:This neuroimaging,observational,animal study was performed at the Laboratory of the Department of Medical Imaging,Second Affiliated Hospital,Medical College, Shantou University,China from July to December 2007. MATERIALS:Butorphanol tartrate nasal spray,as a mixed agonist-antagonist opioid analgesic,was purchased from Shanghai Hengrui Pharmacy,China.A General Electric Signa 1.5T System (General Electric Medical Systems,Milwaukee,Wl,USA) and LCModel software(Stephen Provencher,Oakville,Ontario,Canada) were used in this study. METHODS:MRS images were acquired in ten healthy swine aged 2 weeks using single-voxel point-resolved spectroscopic sequence.A region of interest(2 cm×2 cm×2 cm) was placed in the image centers of maximum brain parenchyma.Repeated MRS scanning was performed 15-20 minutes after intranasal administration of 1 mg of butorphanol tartrate.Three settings of repetition time/echo time were selected before and after nasal spray administration 3000 ms/30 ms, 1500 ms/30 ms,and 3000 ms/50 ms.Metabolite concentrations were estimated by LCModel software. MAIN OUTCOME MEASURES:~1H-MRS spectra was obtained using various repetition time/echo time settings.Concentrations of glutamate compounds(glutamate+glutamine),N-acetyl aspartate, and choline were detected in swine brain prior to and following nasal spray treatment. RESULTS:The glutamate compounds curve was consistent with original spectra,when a repetition time/echo time of 3 000 ms/30 ms was adopted.Concentrations of glutamate compounds,N-acetyl aspartate,and choline decreased following administration.The most significant reduction was observed in glutamate compound concentrations from(9.28±0.54) mmol/kg to(7.28±0.54) mmol/kg (P<0.05). CONCLUSION:~1H-MRS and LCModel software were effectively utilized to quantitatively analyze and measure brain metabolites.Glutamate compounds might be an important neurotransmitter in central analgesia. | Jianlin Wu Ting Liu Yan Lin Zhiwei Shen Yanwei Miao Renhua Wu Changkai Sun | 2009 | Neural Regeneration Research2009，4，7： | 0 |
| 4 | Spontaneous firing properties of rat medial vestibular nucleus neurons in brain slices by infrared visual patch clamp technique显示文摘Domestic application of infrared patch clamp techniques on brain slices is limited.The key of the tech-nique is to prepare high-quality brain slices.The present paper describes the preparation procedure of brainstem slices and the spontaneous firing properties of rat medial vestibular nucleus(MVN)neurons.By infrared differ-ential interference contrast technique,neurons of rat MVN were visualized directly at the depth of 50–100 mm underneath the surface of slices.Firing activities of MVN neurons were recorded by the whole-cell patch clamp technique in artificial cerebrospinal fluid(ACSF)and low Ca^(2+)-high Mg^(2+) fluid.The firing mode was more irregular and depressive in low Ca^(2+)-high Mg2+fluid than in ACSF.According to the averaged waveform of action potentials,cells were classified as the neurons with mono-phasic after-hyperpolarization potential(AHP),and the neurons with biphasic AHP.The resting membrane potential(RMP),input resistance(Rin)and membrane capacitance(Cm)of neurons were recorded and com-pared between groups.With infrared videomicroscopy,patch clamp recordings could be made under direct obser-vation in freshly prepared brainstem slices.The discharge activities of MVN neurons were spontaneous and the fir-ing mode was modulated by extracellular calcium concen-tration.The basic membrane properties of two types of neurons were not significantly different,while the differ-ences in waveform might play a role in the segregation between tonic and kinetic cells. | Jiao XIA Weijia KONG Yun ZHU Yan ZHOU Yu ZHANG Changkai GUO | 2008 | Frontiers of Medicine2008，2，3： | 0 |
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