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Active control for performance enhancement of electrically controlled rotor

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Chinese Journal of Aeronautics 2015年第5期28卷 1494-1502页

作者： lu yang Wang Chao National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and Astronautics

Electrically controlled rotor （ECR） system has the potential to enhance the rotor perfor- mance by applying higher harmonic flap inputs. In order to explore the feasibility and effectiveness for ECR performance enhancement using closed-loop control method, firstly, an ECR rotor performance analysis model based on helicopter flight dynamic model is established, which can reflect the performance characteristics of ECR helicopter at high advance ratio. Based on the simulation platform, an active control method named adaptive T-matrix algorithm is adopted to explore the feasibility and effectiveness for ECR performance enhancement. The simulation results verify the effectiveness of this closed-loop control method. For the sample ECR helicopter, about 3% rotor power reduction is obtained with the optimum 2/rev flap inputs at the advance ratio of 0.34. And through analyzing the distributions of attack of angle and drag in rotor disk, the underlying physical essence of ECR power reduction is cleared. Furthermore, the influence of the key control parameters, including convergence factor and weighting matrix, on the effectiveness of closed-loop control for ECR performance enhancement is explored. Some useful results are summarized, which can be used to direct the future active control law design of ECR performance enhancement.

关键词： Electrically controlled rotor(ECR) Helicopter Higher harmonic control Performance enhancement Swashplateless

High-efficiency prediction method for helicopter global/ground noise based on near-field acoustic holography

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Chinese Journal of Aeronautics 2024年第7期37卷 271-284页

作者： Mengxue SHAO yang lu Xice XU Jiaxin lu National Key Laboratory of Helicopter Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Noise reduction program design is an effective approach that relies on efficient noise prediction for reducing ground noise during *** existing noise prediction methods have the limitations of being computationally expensive or only applicable to *** this paper,a High-Efficiency Prediction Method(HEPM)for helicopter global/ground noise based on near-field acoustic holography is *** HEPM can predict the global noise based on acoustic modal analysis and has the advantages of high prediction accuracy and low time *** process is given as follows:firstly,the rotor noise on the holographic surface in the specified flight is obtained by simulations or ***,the global noise model,which maps time-domain noise to acoustic modes,is established based on near-field acoustic holography and Fourier acoustic analysis ***,combined with acoustic modal amplitude,the model established enables efficiently predicting the global/ground noise in the corresponding flight *** verify the accuracy of the prediction method,a simulation study is conducted in hovering and forward flight states using a model helicopter with a 2-meter rotor and Rotor Body Interaction(ROBIN)*** comparison of HEPM with numerical results shows that the average prediction errors of the global and ground noise are less than 0.3 dB and 0.2 dB,*** a region containing 100000 observers,the computation time of the HEPM is only one-fifth of that of the acoustic hemisphere method,demonstrating the rapidity of the proposed method.

关键词： Helicopter Rotor noise prediction Noise abatement procedure design Acoustic modal analysis Near-field acoustic holography

Noise attenuation of frequency-modulated multi-rotor using sound field reproduction

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Chinese Journal of Aeronautics 2023年第11期36卷 185-203页

作者： Xice XU yang lu Mengxue SHAO Jiaxin lu National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention ***-rotor aircrafts are typically controlled by changing the rotation speeds of the *** reduce the noise of multiple frequency-modulated rotors,a global noise attenuation method is proposed in this ***,the fast prediction method is used to estimate the global noise of the multirotor with different configurations ***,the sound field reproduction method is used to obtain the control signal of the loudspeaker array to achieve global noise ***,the influence of array arrangement on noise reduction is analyzed in the acoustic modal domain,which reveals that different optimization models are needed to minimize the noise power or/and the noise pressure in some directions when the scale of the array is ***,to improve the real-time performance of the system,the online calculation of the optimal control signal is transformed into the offline design of the optimal filter,which satisfies the target frequency-domain ***,the experimental results of the noise of a model quadrotor in the anechoic chamber were consistent with the predicted *** simulation results of noise attenuation for the quadrotor show that the method proposed reduced the global noise power by about 13 ***,the noise region radiated from the quadrotor to the ground with the boundary of 40 dB was reduced to 8.4%of that before control.

关键词： Acoustic modal analysis Frequency-modulated multirotor Noise attenuation Optimal filter design Sound reproduction

A multi-scale second-order autoregressive recursive filter approach for the sea ice concentration analysis

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Acta Oceanologica Sinica 2024年第3期43卷 115-126页

作者： lu yang Xuefeng Zhang School of Marine Science and Technology Tianjin UniversityTianjin 300072China

To effectively extract multi-scale information from observation data and improve computational efficiency,a multi-scale second-order autoregressive recursive filter(MSRF)method is *** second-order autoregressive filter used in this study has been attempted to replace the traditional first-order recursive filter used in spatial multi-scale recursive filter(SMRF)*** experimental results indicate that the MSRF scheme successfully extracts various scale information resolved by ***,compared with the SMRF scheme,the MSRF scheme improves computational accuracy and efficiency to some *** MSRF scheme can not only propagate to a longer distance without the attenuation of innovation,but also reduce the mean absolute deviation between the reconstructed sea ice concentration results and observations reduced by about 3.2%compared to the SMRF *** the other hand,compared with traditional first-order recursive filters using in the SMRF scheme that multiple filters are executed,the MSRF scheme only needs to perform two filter processes in one iteration,greatly improving filtering *** the two-dimensional experiment of sea ice concentration,the calculation time of the MSRF scheme is only 1/7 of that of SMRF *** means that the MSRF scheme can achieve better performance with less computational cost,which is of great significance for further application in real-time ocean or sea ice data assimilation systems in the future.

关键词： second-order auto-regressive filter multi-scale recursive filter sea ice concentration three-dimensional variational data assimilation

Synthesis of layered cathode materials Li[Co_x Ni_y Mn_(1-x-y)]O_2 from layered double hydroxide precursors

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Particuology 2010年第3期8卷 202-206页

作者： Yanluo lu yang Zhao State Key Laboratory of Chemical Resource Engineering Beifing University of Chemical Technology Beijing 100029 China

Cathode materials Li[CoxNiyMn1-x-y]O2 for lithium secondary batteries have been prepared by a new route using layered double hydroxides （LDHs） as a precursor. The resulting layered phase with the α- NaFe02 structure crystallizes in the rhombohedral system, with space group R-3m having an interlayer spacing close to 0.47 nm. X-ray photoelectron spectroscopy （XPS） was used to measure the oxidation states of Co, Ni and Mn. The effects of varying the Co[Ni[Mn ratio on both the structure and electrochemical properties of Li[CoxNiyMn1-x-y]O2 have been investigated by X-ray diffraction and electrochemical tests. The products demonstrated a rather stable cycling behavior, with a reversible capacity of 118 mAh/g for the layered material with Co/Ni/Mn = 1/1/1.

关键词： Layered Li[CoxNiyMn1-x-y]O2 Layered double hydroxides Precursor method Cathode materials

Artificial intelligence:a survey on evolution,models,applications and future trends

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Journal of Management Analytics 2019年第1期6卷 1-29页

作者： yang lu Department of Information System and Decision Sciences University of KentuckyLexingtonKYUSA Alliance Manchester Business University of ManchesterManchesterUK

Artificial intelligence(AI)is one of the core drivers of industrial development and a critical factor in promoting the integration of emerging technologies,such as graphic processing unit,Internet of Things,cloud computing,and the blockchain,in the new generation of big data and Industry *** this paper,we construct an extensive survey over the period 1961-2018 of AI and deep *** research provides a valuable reference for researchers and practitioners through the multi-angle systematic analysis of AI,from underlying mechanisms to practical applications,from fundamental algorithms to industrial achievements,from current status to future *** there exist many issues toward AI,it is undoubtful that AI has become an innovative and revolutionary assistant in a wide range of applications and fields.

关键词： artificial intelligence deep learning Internet of Things Industry 4.0 graphic processing unit big data

NHPP-based software reliability model considering testing effort and multivariate fault detection rate

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Journal of Systems Engineering and Electronics 2016年第1期27卷 260-270页

作者： Jie Zhang yang lu Shu yang Chong Xu School of Computer and Information Hefei University of Technology Hefei 230009 China School of Mathematics and Computer Science Anhui Normal University Wuhu 241003 China

In recent decades,many software reliability growth models（SRGMs） have been proposed for the engineers and testers in measuring the software reliability *** of them is established based on the non-homogeneous Poisson process（NHPP）,and it is proved that the prediction accuracy of such models could be improved by adding the describing of characterization of testing ***,some research work indicates that the fault detection rate（FDR） is another key factor affects final software *** early NHPPbased models deal with the FDR as constant or piecewise function,which does not fit the different testing stages ***,this paper first incorporates a multivariate function of FDR,which is bathtub-shaped,into the NHPP-based SRGMs considering testing effort in order to further improve performance.A new model framework is proposed,and a stepwise method is used to apply the framework with real data sets to find the optimal *** studies show that the obtained new model can provide better performance of fitting and prediction compared with other traditional SRGMs.

关键词： software reliability software reliability growth mo del(SRGM) testing effort fault detection rate(FDR).

Strategies to improve micelle stability for drug delivery

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Nano Research 2018年第10期11卷 4985-4998页

作者： yang lu Ershuai Zhang Jianhai yang Zhiqiang Cao Department of Chemical Engineering and Materials Science Wayne State University Detroit 48202 MI USA

Micelles have been studied as drug delivery carriers for decades. Their use can potentially result in high drug accumulation at the target site through the enhanced permeability and retention effect. Nevertheless, the lack of stability of micelles in the physiological environment limits their efficacy as a drug carrier. In particular, micelles tend to disassociate and prematurely release the encapsulated drugs, lowering delivery efficacy and creating toxicity concerns. Many efforts to enhance the stability of micelles have focused mainly on decreasing the critical micelle forming concentration and improving blood circulation. Herein, we review different strategies including crosslinking and non-crosslinking approaches designed to stabilize micelles and offer perspectives on future research directions.

关键词： micelle stability crosslinking critical micelle concentration (CMC) drug delivery

Band Gap of Strained Graphene Nanoribbons

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Nano Research 2010年第3期3卷 189-199页

作者： yang lu Jing Guo Department of Electrical and Computer Engineering University of FloridaGainesvilleFL 32611USA

The band structures of strained graphene nanoribbons(GNRs)are examined using a tight-binding Hamiltonian that is directly related to the type and magnitude of *** to a two-dimensional graphene whose band gap remains close to zero even if a large strain is applied,the band gap of a graphene nanoribbon(GNR)is sensitive to both uniaxial and shear *** effect of strain on the electronic structure of a GNR depends strongly on its edge shape and structural *** an armchair GNR,a weak uniaxial strain changes the band gap in a linear fashion,whereas a large strain results in periodic oscillation of the band *** the other hand,shear strain always tends to reduce the band *** a zigzag GNR,the effect of strain is to change the spin polarization at the edges of GNR,and thereby modulate the band gap.A simple analytical model,which agrees with the numerical results,is proposed to interpret the response of the band gap to strain in armchair GNRs.

关键词： Graphene nanoribbons(GNRs) band gap strain