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Achieving desired nodal lines in freely vibrating structures via material-field series-expansion topology optimization

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Frontiers of Mechanical Engineering 2023年第3期18卷 187-201页

作者： Yi YAN Xiaopeng ZHANG jiaqi he Dazhi WANG Yangjun LUO State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China School of Mechanical Engineering Dalian University of TechnologyDalian 116024China School of Science Harbin Institute of TechnologyShenzhen 518055China

Accurately controlling the nodal lines of vibrating structures with topology optimization is a highly challenging task.The major difficulties in this type of problem include a large number of design variables,the highly nonlinear and multi-peak characteristics of iteration,and the changeable orders of eigenmodes.In this study,an effective material-field series-expansion(MFSE)-based topology optimization design strategy for precisely controlling nodal lines is proposed.here,two typical optimization targets are established:(1)minimizing the difference between structural nodal lines and their desired positions,and(2)keeping the position of nodal lines within the specified range while optimizing certain dynamic performance.To solve this complex optimization problem,the structural topology of structures is first represented by a few design variables on the basis of the MFSE model.Then,the problems are effectively solved using a sequence Kriging-based optimization algorithm without requiring design sensitivity analysis.The proposed design strategy inherently circumvents various numerical difficulties and can effectively obtain the desired vibration modes and nodal lines.Numerical examples are provided to validate the proposed topology optimization models and the corresponding solution strategy.

关键词： nodal line topology optimization structural dynamics design material-field series-expansion

Enhanced carrier mobility in MoSe_(2) by pressure modulation

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Nano Research 2023年第11期16卷 12738-12744页

作者： Zhiying Bai he Zhang jiaqi he Dawei he Jiarong Wang Guili Li Jinxuan Bai Kun Zhao Xiaohui Yu Yongsheng Wang Xiaoxian Zhang Key Laboratory of Luminescence and Optical Information Ministry of EducationInstitute of Optoelectronic TechnologyBeijing Jiaotong UniversityBeijing 100044China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China College of Mathematics and Physics Beijing University of Chemical TechnologyBeijing 100029China Songshan Lake Materials Laboratory Dongguan 523808China

Two-dimensional(2D)materials hold great potential for the development of next-generation integrated circuits(ICs)at the atomic limit.However,it is still very challenging to build high performance devices.One of the main factors that limit the incorporation of 2D materials into IC technology is their relatively low carrier mobility.Thus,the engineering strategies that focus on optimizing performance continue to emerge.herein,using a spatiotemporal resolved pump-probe setup,the carrier transport performance and relaxation process of few-layer and bulk MoSe_(2) under pressure were investigated nondestructively and simultaneously.Our results show that pressure can tune the transport performance effectively.In particular,under pressure regulation,the carrier mobility of the bulk MoSe_(2) increases by~4 times;meanwhile,the carrier lifetimes of the samples become shorter.Although the processes almost return to their initial state after the pressure release,it is still surprising to see that the carrier mobilities of fewlayer and bulk MoSe2 are still~1.5 and 2 times enhanced,and carrier lifetimes are still shorter than the initial state.Combined with the Raman spectra under pressure,we consider that it is caused by the enhanced layer coupling and lattice compression.The combination of enhanced mobility and shortened lifetime in MoSe_(2) under pressure holds great potential for optoelectronic applications under the deep ocean and deep earth.

关键词： transition metal dichalcogenides(TMDs) pressure carrier relaxation transport performance spatiotemporally resolved pump-probe spectroscopy

A colorimetric assay for cholesterol based on the encapsulation of multienzyme in leaf-shape crossed ZIF-L

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Chinese Chemical Letters 2023年第2期34卷 382-387页

作者： jiaqi he Tingling Zhuo Yintong Teng Guoqin Chen Peng Zhao Caiwen Ou Department of Cardiology Guangzhou Panyu Central HospitalGuangzhou University of Chinese MedicineGuangzhou 510006China Department of Cardiology and Laboratory of heart Center Zhujiang HospitalSouthern Medical UniversityGuangzhou 510280China NMPA Key Laboratory for Research and Evaluation of Drug Metabolism Guangdong Provincial Key Laboratory of New Drug ScreeningSchool of Pharmaceutical SciencesSouthern Medical UniversityGuangzhou 510515China Affiliated Dongguan Hospital Southern Medical UniversityDongguan 523059China Guangdong Provincial Key Laboratory of Shock and Microcirculation Southern Medical UniversityGuangzhou 510515China

The serum cholesterol level is an important indicator of healthy and there is a great necessity for frequent cholesterol monitoring to some cardiovascular-related diseases, which puts forward higher requirements for point-of-care testing(POCT) of cholesterol. In this work, a cascade catalytic system of cholesterol is developed by encapsulation of cholesterol oxidase(Ch Ox) and Pd Cu Au nanoparticles into zeolitic imidazolate framework-L(Ch Ox/PCA@ZIF-L). Results indicate that ZIF-L carrier can significantly increase the catalytic activity of single or multiple enzymes, due to its high loading capacity and efficient molecular transport. Under the optimal conditions, the absorbance of reaction system performs linear relationships with the concentration of cholesterol in two intervals from 0.0005 mmol/L to 1.0000 mmol/L, with a limit of detection of 0.2176 μmol/L. The proposed colorimetric strategy based on Ch Ox/PCA@ZIF-L performs a good agreement with the results provided by chemiluminescence method for the serum cholesterol detection. Interestingly, a simple paper-based sensing system is constructed through a pre-reaction-transfer operation, which gets rid of the complex pre-processing requirements of traditional operations on filter paper. The presented strategy allows for the sensitive, convenient, costless assay of serum cholesterol,and paves a new way to design the POCT device for daily monitoring of healthy.

关键词： Cholesterol Zeolitic imidazolate framework-L Artificial enzyme Colorimetric Point-of-care testing

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Pigeon-inspired optimization and extreme learning machine via wavelet packet analysis for predicting bulk commodity futures prices

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Science China(Information Sciences) 2019年第7期62卷 45-63页

作者： Feng JIANG jiaqi he Zhigang ZENG School of Statistics and Mathematics Zhongnan University of Economics and Law School of Automation Huazhong University of Science and Technology

In this paper, a hybrid approach consisting of pigeon-inspired optimization(PIO) and extreme learning machine(ELM) based on wavelet packet analysis(WPA) is presented for predicting bulk commodity futures prices. Firstly, WPA is applied to decompose the original futures prices into a set of lower-frequency subseries. Secondly, the PIO algorithm is used to optimize the parameters of ELM and then the optimized ELM is utilized to forecast the subseries. Finally, we adopt the hybrid method to calculate the final forecasting outcomes of futures prices. In order to further test the predictive ability of the hybrid forecasting model on bulk commodity futures prices, we use the prices of West Texas Intermediate crude oil futures and Chicago Board of Trade soybean futures to make one-step, two-step and four-step ahead predictions. In comparison with complete ensemble empirical mode decomposition with adaptive noise, empirical mode decomposition and singular spectrum analysis, WPA is the most suitable for decomposing bulk commodity futures prices.The experimental outcomes show that the hybrid WPA-PIO-ELM model has better performance on horizontal precision, directional precision and robustness.

关键词： wavelet packet analysis extreme learning machine pigeon-inspired optimization bulk commodity futures price prediction directional precision

Enhanced exciton diffusion from interlayer charge-transfer transitions in PtSe2/MoSe_(2) van der Waals heterojunction

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Nano Research 2023年第11期16卷 12809-12816页

作者： Jiarong Wang Dawei he Zhiying Bai Guili Li Jinxuan Bai Keqin Liu Fangying Ren Xiaojing Liu jiaqi he Weiya Zhou Jianlin Sun Yongsheng Wang Xiaoxian Zhang Yuchao Yang Key Laboratory of Luminescence and Optical Information Ministry of EducationInstitute of Optoelectronic TechnologyBeijing Jiaotong UniversityBeijing 100044China Beijing Advanced Innovation Center for Integrated Circuits School of Integrated CircuitsPeking UniversityBeijing 100871China School of Electronic and Computer Engineering Peking UniversityShenzhen 518055China Center for Brain Inspired Chips Institute for Artificial IntelligenceFrontiers Science Center for Nano-optoelectronicsPeking UniversityBeijing 100871China Center for Brain Inspired Intelligence Chinese Institute for Brain Research(CIBR)Beijing 102206China College of Mathematics and Physics Beijing University of Chemical TechnologyBeijing 100029China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

Artificial van der Waals(vdWs)heterostructures offer unprecedented opportunities to explore and reveal novel synergistic electronic and optical phenomena,which are beneficial for the development of novel optoelectronic devices at atomic limits.However,due to the damage caused by the device fabrication process,their inherent properties such as carrier mobility are obscured,which hinders the improvement of device performance and the incorporation of vdWs materials into next-generation integrated circuits.herein,combining pump-probe spectroscopic and scanning probe microscopic techniques,the intrinsic optoelectronic properties of PtSe_(2)/MoSe_(2)heterojunction were nondestructively and systematically investigated.The heterojunction exhibits a broad-spectrum optical response and maintains ultrafast carrier dynamics(interfacial charge transfer~0.8 ps and carrier lifetime~38.2 ps)simultaneously.The in-plane exciton diffusion coefficient of the heterojunction was extracted(19.4±7.6 cm^(2)∙s^(−1)),and its exciton mobility as high as 756.8 cm^(2)∙V−1∙s^(−1)was deduced,exceeding the value of its components.This enhancement was attributed to the formation of an n-type Schottky junction between PtSe_(2)and MoSe_(2),and its built-in electric field assisted the ultrafast transfer of photogenerated carriers from MoSe_(2)to PtSe_(2),enhancing the in-plane exciton diffusion of the heterojunction.Our results demonstrate that PtSe_(2)/MoSe_(2)is suitable for the development of broadspectrum and sensitive optoelectronic devices.Meanwhile,the results contribute to a fundamental understanding of the performance of various optoelectronic devices based on such PtSe_(2)two-dimensional(2D)heterostructures.

关键词： van der Waals heterostructures ultrafast carrier dynamics exciton diffusion pump-probe spectroscopy scanning probe microscopy

A Bayesian Updating Method for Non-Probabilistic Reliability Assessment of Structures with Performance Test Data

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Computer Modeling in Engineering & Sciences 2020年第11期125卷 777-800页

作者： jiaqi he Yangjun Luo Province Key Laboratory of Advanced Technology for Aerospace Vehicles School of Aeronautics and AstronauticsDalian University of TechnologyDalian116024China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian116024China

For structures that only the predicted bounds of uncertainties are available,this study proposes a Bayesianmethod to logically evaluate the nonprobabilistic reliability of structures based on multi-ellipsoid convex model and performance test data.According to the given interval ranges of uncertainties,we determine the initial characteristic parameters of a multi-ellipsoid convex set.Moreover,to update the plausibility of characteristic parameters,a Bayesian network for the information fusion of prior uncertainty knowledge and subsequent performance test data is constructed.Then,an updated multi-ellipsoid set with the maximum likelihood of the performance test data can be achieved.The credible non-probabilistic reliability index is calculated based on the Kriging-based surrogate model of the performance function.Several numerical examples are presented to validate the proposed Bayesian updating method.

关键词： Convex model Bayesian method non-probabilistic reliability information fusion

Synthesis of N-doped carbon quantumn dots as lubricant additive to enhance the tribological behavioor f MoS_(2)nanofluid

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Friction 2023年第3期11卷 441-459页

作者： jiaqi he Jianlin SUN Junho CHOI Chenglong WANG Daoxin SU School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Department of Mechanical Engineering The University of TokyoTokyo 113-8656Japan

In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal method.The synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a graphene oxide(GO)-like structure with various oxygen(O)-and nitrogen(N)-containing functional groups.Then N-CQDs were added to MoS_(2)nanofluid,and the tribological properties for steel/steel friction pairs were evaluated using a pin-on-disk tribometer.Non-equilibrium molecular dynamics(NEMD)simulations for the friction system with MoS_(2)or MoS_(2)+N-CQD nanoparticles were also conducted.The results showed that friction processes with MoS_(2)+N-CQD nanofluids were under the mixed lubrication regime.And MoS_(2)nanofluid containing 0.4 wt%N-CQDs could achieve 30.4%and 31.0%reduction in the friction coefficient and wear rate,respectively,compared to those without N-CQDs.By analyzing the worn surface topography and chemical compositions,the excellent lubrication performance resulted from the formation of tribochemistry-induced tribofilm.The average thickness of tribofilm was about 13.9 nm,and it was composed of amorphous substances,ultrafine crystalline nanoparticles,and self-lubricating FeSO_(4)/Fe2(SO_(4))_(3).NEMD simulation results indicated the interaction between S atoms in MoS_(2)as well as these O-and N-containing functional groups in N-CQDs with steel surfaces enhanced the stability and strength of tribofilm.Thereby the metal surface was further protected from friction and wear.

关键词： carbon-based quantum dots(CQDs) lubricant nanofluid molecular dynamics(MD) tribofilm

Mongolia Contributed More than 42%of the Dust Concentrations in Northern China in March and April 2023

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Advances in Atmospheric Sciences 2023年第9期40卷 1549-1557页

作者： Siyu CheN Dan ZHAO Jianping HUANG jiaqi he Yu CheN Junyan CheN Hongru BI Gaotong LOU Shikang DU Yue ZHANG Fan YANG Key Laboratory for Semi-Arid Climate Change of the Ministry of Education Lanzhou UniversityLanzhou 730000China Institute of Desert Meteorology China Meteorological AdministrationUrumqi 830002China

Dust storms are one of the most frequent meteorological disasters in China,endangering agricultural production,transportation,air quality,and the safety of people’s lives and property.Against the backdrop of climate change,Mongolia’s contribution to China’s dust cannot be ignored in recent years.In this study,we used the Weather Research and Forecasting model coupled with Chemistry(WRF-Chem),along with dynamic dust sources and the HYSPLIT model,to analyze the contributions of different dust sources to dust concentrations in northern China in March and April 2023.The results show that the frequency of dust storms in 2023 was the highest observed in the past decade.Mongolia and the Taklimakan Desert were identified as two main dust sources contributing to northern China.Specifically,Mongolia contributed more than 42%of dust,while the Taklimakan Desert accounted for 26%.A cold high-pressure center,a cold front,and a Mongolian cyclone resulted in the transport of dust aerosols from Mongolia and the Taklimakan Desert to northern China,where they affected most parts of the region.Moreover,two machine learning methods[the XGBoost algorithm and the Synthetic Minority Oversampling Technique(SMOTE)]were used to forecast the dust storms in March 2023,based on ground observations and WRF-Chem simulations over East Asia.XGBoost-SMOTE performed well in predicting hourly PM10 concentrations in China in March 2023,with a mean absolute error of 33.8μg m−3 and RMSE of 54.2μg m−3.

关键词： dust aerosol Mongolian dust transboundary contribution WRF-Chem HYSPLIT model

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Near-infrared light-controllable bufalin delivery from a black phosphorus-hybrid supramolecular hydrogel for synergistic photothermal-chemo tumor therapy

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Nano Research 2021年第11期14卷 3988-3998页

作者： jiaqi he Guoqin Chen Peng Zhao Caiwen Ou Cardiology Department of Panyu Central Hospital Guangzhou University of Chinese MedicineGuangzhou510006China Guangdong Provincial Key Laboratory of New Drug Screening School of Pharmaceutical SciencesSouthern Medical UniversityGuangzhou510515China Guangdong Provincial Key Laboratory of Shock and Microcirculation Zhujiang Hospital of Southern Medical UniversitySouthern Medical UniversityGuangzhou510280China

Bufalin is efficacious in treating various tumors, however, the clinical application of which is restricted by the myocardial toxicity. Developing a smart synergetic delivery system is widely considered as a promising therapeutic strategy. To address this issue, a black phosphorus hybrid polypeptides hydrogel was designed to highly load bufalin, and achieved near-infrared (NIR)-controllable drug release with synergistic photothermal-chemo therapeutic effect. Black phosphorus nanosheets (BPNSs) and bufalin were co-loaded in temperature-sensitive supramolecular hydrogel to receive smart hybridization (BP-bufalin@SH). With NIR irradiation (1 W·cm−2), BP-bufalin@SH exhibited a rapid and large temperature increase and released bufalin via light-controllable manner, with which the side effects of bufalin were greatly decreased. Combined with photothermal-chemo therapeutic effect, BP-bufalin@SH could collapse the mitochondrial transmembrane potential resulting in the irreversible apoptosis of tumor cells, and realize a highly efficient in vivo tumor elimination with good biosafety and biocompatibility. This work provides a new hydrogel platform for controlling bufalin release, and thus further promotes the practical application on antitumor therapy.

关键词： photothermal-chemo synergic therapy bufalin black phosphorus nanosheets supramolecular hydrogel