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Nonlinear uncertainty impact of geometric variations on aerodynamic performance of low-pressure turbine blades with ultra-high loading under extreme operational conditions

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Chinese Journal of Aeronautics 2024年第5期37卷 281-300页

作者： Xiaojing WANG Zhengping ZOU Chao FU Pengcheng DU School of Energy and Power Engineering Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China

Uncertainty impact of random geometric variations on the aerodynamic performance of low-pressure turbine blades is considerable,which is further amplified by the current ultra-high-lift design trend for weight ***,this uncertainty impact on ultra-highly loaded blades under extreme operational conditions near the margins with potential large-scale open separation is focused on in this *** is demonstrated that this impact is significant,unfavourable,and nonlinear,which is clearly severer under extreme *** addition to the overall attenuation and notable scattering of specific performance,the operational margins with open separation are also notably scattered with great risk of significant *** scattering and nonlinearity are dominated by the variations in leading-edge *** thinning of leading edge triggers local transition,enhancing downstream friction and reducing resistance to open separation,which is further exacerbated by operational ***,the opposite thickening yields less benefit,implying *** unfavourable impact highlights the need for robust aerodynamic design,where both a safer operational condition and a more robust blade are indispensable,i.e.,a compromise among performance,weight,and *** the necessary limitation of loading levels,a mid-loaded design is recommended to reduce adverse pressure gradients in both the leading edge and rear region of the suction side,which helps to decrease the susceptibility of the transition and open separation to random *** improvements can also be achieved by appropriately thickening the leading edge.

关键词： Ultra-highly loaded turbine blade Geometric variations Uncertainty analysis Operational margins Robust aerodynamic design nonlinearity

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nonlinearity in Stock Exchange Markets: The Case of Bist 100 Indices

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Chinese Business Review 2021年第1期20卷 15-21页

作者： Jamilu Said Babangida Department of Economics Ahmadu Bello UniversityNigeria Department of International Finance Istanbul Commerce UniversityTurkey Department of Economics Ibn Haldun UniversityTurkey

In this paper,using data for the Bist 100 index,we investigate the presence of nonlinearities by employing several nonlinearity *** Brock,Dechert,and Scheinkman(BDS)and runs tests were first applied to the series to show an initial indication of *** findings for the BDS and runs test of randomness were followed by other sets of direct nonlinearity tests developed by White(1989),Terasvirta(1993),Keenan(1985),and Tsay(1986).Also,the Threshold Autoregression(TAR)test is employed as a final test to confirm the existence of nonlinearity in the Turkish stock exchange *** the results of the nonlinearity test,it is concluded that the Bist 100 index is characterised by the presence of nonlinearities and *** finding is in contrast with the efficient market hypothesis(EMH)implying that the Turkish stock exchange market is inefficient.

关键词： stock market nonlinearity efficient market hypothesis Bist 100 index

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High Responsivity and Ultra-Low Detection Limits in Nonlinear a-Si:H p-i-n Photodiodes Enabled by Photogating

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Photonic Sensors 2023年第4期13卷 27-38页

作者： Andreas BABLICH Maurice MÜLLER Rainer BORNEMANN Andreas NACHTIGAL Peter HARING BOLÍVAR Institute of Graphene-Based Nanotechnology University of SiegenHölderlinstr.357076 SiegenGermany Institute of High Frequency and Quantum Electronics University of SiegenHölderlinstr.357076 SiegenGermany

Photodetectors operating at the wavelength in the visible spectrum are key components in high-performance optoelectronic *** this work,massive nonlinearities in amorphous silicon p-i-n photodiodes enabled by the photogating are presented,resulting in responsivities up to 744 mA/W at blue *** detectors exhibit significant responsivity gains at optical modulation frequencies exceeding MHz and a more than 60-fold enhanced spectral response compared to the non-gated *** detection limits down to 10.4 nW/mm^(2) and mean signal-to-noise ratio enhancements of 8.5dB are demonstrated by illuminating the sensor with an additional 6.6μW/mm^(2) red ***-optical simulations verify photocarrier modulation due to defect-induced field screening to be the origin of such high responsivity *** experimental results validate the theory and enable the development of commercially viable and complementary metal oxide semiconductor(CMOS)compatible high responsivity photodetectors operating in the visible range for low-light level imaging and detection.

关键词： Photogating amorphous silicon a-Si:H nonlinearity photodetector responsivity gain

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Quantitative simulation and prediction of extreme geological events

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Science China Earth Sciences 2022年第6期65卷 1012-1029页

作者： Qiuming CHENG School of Earth Science and Engineering Sun Yat-Sen UniversityZhuhai 915000China State Key Lab of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China

The systematic study of extreme geological events(such as plate collision and subduction, extreme cold and extreme hot events, biological extinction and revival, earthquakes, volcanoes, mineralization, and oil accumulation) that occurred during the evolution of the earth is essential not only for understanding the “abrupt changes in the evolution of the earth”, but also for an in-depth understanding of the co-evolution of material-life-environment of the livable earth. However, due to the temporal and spatial anomalies and complexity of extreme geological events, classical mathematical models cannot be effectively applied to quantitively describe such events. After comparative studies of many types of geological events, the author found that such extreme geological events often depict “singular” characteristics(abnormal accumulation or depletion of matter or massive release or absorption of energy in a small space or time interval). On this basis, the author proposes a unified definition of extreme geological events, a new concept of “fractal density” and a “local singularity analysis” method for quantitative description and modeling of extreme geological events. Applications of these methods to several types of extreme geological events have demonstrated that the singularity theory and methods developed in the current research can be used as general approaches for the characterization, simulation, and prediction of geological events.

关键词： Mathematical geosciences nonlinearity Geocomplexity Multifractals Chaos Phase transition Multiplicative cascade processes

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Generation of mid-infrared supercontinuum by designing circular photonic crystal fiber

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Chinese Physics B 2022年第5期31卷 370-378页

作者： Ying Huang Hua Yang Yucheng Mao College of Computer Science and Electronic Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

A circular photonic crystal fiber(C-PCF)based on As2 Se3 is designed,which has three zero dispersion wavelengths and flat *** this fiber,a wide mid-infrared supercontinuum(MIR-SC)can be generated by launching a femtosecond pulse in the first anomalous dispersion *** simulation results show that the MIR-SC is formed by soliton self-frequency shift and direct soliton spectrum tunneling on the long wavelength side and self-phase modulation,soliton fission on the short wavelength ***,optical shocking and four-wave mixing(FWM)are not conducive to the long-wavelength extension of MIR-SC,while the number and intensity of fundamental solitons have a greater effect on the short-wavelength extension of *** generation of optical shocking waves,FWM waves and fundamental solitons can be obviously affected by changing the fiber length and input pulse parameters,so that the spectrum range and flatness can be adjusted with great ***,under the conditions of 4000 W pulse peak power,30 fs pulse width,47 mm fiber length,and 0 initial chirp,a wide MIR-SC with a coverage range of 2.535μm-16.6μm is *** numerical results are encouraging because they demonstrate that the spread of MIR-SC towards the red and blue ends can be manipulated by choosing the appropriate incident pulse and designing optimized fiber parameters,which contributes to applications in such diverse areas as spectroscopy,metrology and tomography.

关键词： circular photonic crystal fiber chalcogenide glass direct soliton spectrum tunneling nonlinearity

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Generalized degradation reliability model considering phase transition

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Journal of Systems Engineering and Electronics 2022年第3期33卷 748-758页

作者： ZHANG Ao WANG Zhihua WU Qiong LIU Chengrui School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Institute of Spacecraft System Engineering China Academy of Space TechnologyBeijing 100094China Beijing Institute of Control Engineering Beijing 100094China

Aiming to evaluate the reliability of phase-transition degrading systems,a generalized stochastic degradation model with phase transition is constructed,and the corresponding analytical reliability function is formulated under the concept of the first hitting *** phase-varying stochastic property and the phase-varying nonlinearity are considered simultaneously in the proposed *** capture the phase-varying stochastic pro-perty,a Wiener process is adopted to model the non-monotonous degradation phase,while a Gamma process is utilized to model the monotonous *** addition,the phase-varying non-linearity is captured by different transformed time scale *** facilitate the practical application of the proposed model,identification of phase model type and estimation of model parameters are discussed,and the initial guesses for parameters optimization are also *** on the constructed model,two simulation studies are carried out to verify the analytical reliability function and analyze the influence of model ***,a practical case study is conducted for illustration.

关键词： degradation phase transition reliability stochastic process nonlinearity

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Self-focusing of partially coherent beams based on complex screen and split-step Fourier transform methods

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中国光学快报:英文版 2023年第7期21卷 53-58页

作者：杨方伦张国文张笑琪张艳丽王瑞峰朱健强 School of Physical Sciences University of Science and Technology of ChinaHefei 230026China Key Laboratory of High Power Laser and Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China National Laboratory on High Power Laser and Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

The self-focusing phenomenon of partially coherent beams(PCBs)was simulated using the complex screen method combined with the split-step Fourier method to solve the nonlinear Schrödinger *** the propagation of Gaussian Schell-model beams in a nonlinear medium as an example,the suppression effects of intensity,propagation distance,and spatial coherence on small-scale self-focusing were *** of overall and small-scale self-focusing using this method were compared with the existing literature to demonstrate the validity of the *** method can numerically analyze the degree of self-focusing in PCBs and advance the study of their nonlinearity.

关键词： partially coherent beams self-focusing nonlinearity complex screen method Gaussian Schell-model

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Modeling and analysis of the friction in a non-linear sliding-mode triboelectric energy harvester

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Acta Mechanica Sinica 2022年第4期38卷 189-206,I0004页

作者： Dongguo Tan Jiaxi Zhou Kai Wang Changqi Cai Daolin Xu College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China Chongqing Institute of Hunan University Chongqing 401133China

Friction plays a pivotal role in the sliding-mode triboelectric energy harvester(TEH),which not only enables the charge transfer between two dielectrics,but also influences the energy harvesting performance by affecting the dynamic response of the *** to evaluate the effects of the friction on TEHs is important for optimizing TEHs in engineering *** order to analyze the effects of the friction on the dynamic response and evaluate the energy harvesting performance ofTEHs,the paper models the friction of a devised non-linear TEH based on the Coulomb friction model and the Macro-slip friction *** TEH equips a pair of magnets,rendering a switching between the bistability and the monostability by tuning the distance between two *** dynamic model of the non-linear TEH is established by the extended Hamilton *** effects of friction in slidingmode TEH are dissected in *** influences of parameters on both the mechanical and electrical responses are also systemically studied to explore an optimal energy harvesting performance in the low-frequency *** work provides a guideline for designing and accurately analyzing a sliding-mode TEH.

关键词： Triboelectric energy harvester Magnetic bistability Macro-slip friction model Coulomb friction model nonlinearity

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High-power and high-efficiency 4.3 μm ZGP-OPO

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Chinese Optics Letters 2022年第1期20卷 74-78页

作者： Feifei Wang Jiatong Li Xiaohui Sun Bingzheng Yan Hongkun Nie Xun Li Kejian Yang Baitao Zhang Jingliang He State Key Laboratory of Crystal Materials Institute of Novel SemiconductorsShandong UniversityJinan 250100China Key Laboratory of Laser&Infrared System Ministry of EducationShandong UniversityQingdao 266237China Collaborative Innovation Center of Light Manipulations and Applications Shandong Normal UniversityJinan 250358China State Key Laboratory of Transient Optics and Photonics Xi’an Institute of Optics and Precision Mechanics of CASXi’an 710119China

In this paper,a high-power and high-efficiency 4.3μm mid-infrared(MIR)optical parametric oscillator(OPO)based on ZnGeP_(2)(ZGP)crystal is *** acousto-optically Q-switched Ho Y_(3)Al_(5)O_(12) laser operating at 2.1μm with a maximum average output power of 35 W and pulse width of 38 ns at a repetition rate of 15 kHz is established and employed as the pump source.A doubly resonant OPO is designed and realized with the total MIR output power of 13.27 W,including the signal and idler output power of 2.65 W at 4.07μm and 10.62 W at 4.3μ*** corresponding total optical-to-optical and slope efficiencies are 37.9%and 67.1%,*** shortest pulse width,beam quality factor,and output power instability are measured to be 36 ns,M_(x)^(2)=1.8,M_(y)^(2)=2.0,and RMS<1.9%at 8 h,*** results pave a way for designing high-power and high-efficiency 4–5μm MIR laser sources.

关键词： mid-infrared laser optical parametric oscillator nonlinearity

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Nanosecond and femtosecond lasers based on black arsenic-phosphorus alloys saturable absorber

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Chinese Optics Letters 2022年第2期20卷 106-110页

作者： Shengjun Huang Yiran Wang Jingliang He Xiancui Su Jie Liu Shandong Provincial Engineering and Technical Center of Light Manipulations&Shandong Provincial Key Laboratory of Optics and Photonic Device School of Physics and ElectronicsShandong Normal UniversityJinan 250358China Shandong Key Laboratory of Optical Communication Science and Technology School of Physics Science and Information TechnologyLiaocheng UniversityLiaocheng 252059China State Key Laboratory of Crystal Materials Institute of Novel SemiconductorsShandong UniversityJinan 250100China

In this paper, the high-repetition-rate passively Q-switched(PQS) and the femtosecond continuous-wave mode-locked(CWML) lasers are successfully obtained with 2 D black arsenic-phosphorus(b-As P) nanosheets as saturable absorber(SA) at 1 μm for the first time, to the best of our knowledge. The saturable absorption properties and ultrafast carrier dynamics of the 2 D b-As P SA are explored by Z-scan and pump-probe techniques. Moreover, according to the measurement of desired nonlinear optical characteristics of the relaxation time of 27 ps and the modulation depth of 7.14%, the PQS and CWML lasers are demonstrated with the highest repetition rate of 2.26 MHz in the PQS laser and the pulse width of 470 fs in the CWML laser. The results show 2 D b-As P SA has enormous potential for pulse modulation in solid-state bulk lasers.

关键词： ultrafast lasers mode-locked lasers passively Q-switched lasers nonlinearity

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