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Monetary Policy and Borrowers'Loan Defaults:Research Based on Data from Ren re ndai

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China & World Economy 2020年第1期28卷 94-121页

作者： wenda Song Haiyang zhang School of Banking and Finance University of International Business and Economics School of Banking and Finance University of International Business and Economicsand Institute of Digital FinancePeking University

This paper uses Renrendai data to study the relationship between monetaryj policy and the default behavior of borrowers,and analyzes the transmission channels.The research shows that tight monetary policy will lead to a significant increase in a borrower s probability to default,and this effect will continue for several months.There may be two transmission channels:(i)monetary policy changes a debtor s liquidity through credit and balance sheet channels,which directly affects their current repayment behavior;and(ii)monetary policy may affect a borrower s investment,production and profitability,thus changing their long-term solvency.The paper also finds that the repayment behavior of productive borrowers is more susceptible to monetary policy than consumptive borrowers,and that the default behavior of borrowers in coastal provinces is more susceptible to monetary policy than of borrowers in inland provinces.These findings provide new evidence for understanding how monetary policy affects individual behavior and its transmission mechanisms.

关键词： default liquidity monetary policy online lending

Improved Baseline Correction Method Based on Polynomial Fitting for Raman Spectroscopy

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Photonic Sensors 2018年第4期8卷 332-340页

作者： Haibing HU Jing BAI Guo XIA WenDa Zhang Yan MA Key Laboratory of Special Display Technology of the Ministry of Education National Engineering Laboratory of SpecialDisplay Technology National Key Laboratory of Advanced Display Technology Academy of Photoelectric TechnologyHefei University of Technology Hefei 230009 China

Raman spectrum, as a kind of scattering spectrum, has been widely used in many fields because it can characterize the special properties of materials. However, Raman signal is so weak that the noise distorts the real signals seriously. Polynomial fitting has been proved to be the most convenient and simplest method for baseline correction. It is hard to choose the order of polynomial because it may be so high that Runge phenomenon appears or so low that inaccuracy fitting happens. This paper proposes an improved approach for baseline correction, namely the piecewise polynomial fitting （PPF）. The spectral data are segmented, and then the proper orders are fitted, respectively. The iterative optimization method is used to eliminate discontinuities between piecewise points. The experimental results demonstrate that this approach improves the fitting accuracy.

关键词： Raman spectrum piecewise polynomial fitting baseline correction elimination of discontinuities

Fixed-length roof cutting with vertical hydraulic fracture based on the stress shadow effect:A case study

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International Journal of Mining Science and Technology 2022年第2期32卷 295-308页

作者： Feiteng zhang Xiangyu Wang Jianbiao Bai wenda Wu Bowen Wu Guanghui Wang School of Mines China University of Mining&TechnologyXuzhou 221116China State Key Laboratory of Coal Resources and Safe Mining China University of Mining&TechnologyXuzhou 221116China

Pre-driven longwall retracement roadway(PLRR)is commonly used in large mine shaft.The support crushing disasters occur frequently during the retracement,and roof management is necessary.Taking the 31107 panel as research background,the roof breaking structure of PLRR is analyzed.It is concluded that the roof cutting with vertical hydraulic fracture(HF)at a specified position,that is,fixed-length roof cutting,can reduce support load and keep immediate roof intact.The extended finite element method(XFEM)is applied to simulate hydraulic fracturing.The results show that both the axial and transverse hydraulic fracturing cannot effectively create vertical HFs.Therefore,a novel construction method of vertical HF based on the stress shadow effect(SSE)is proposed.The stress reversal region and HF orientation caused by the prefabricated hydraulic fracture(PF)are verified in simulation.The sub-vertical HFs are obtained between two PFs,the vertical extension range of which is much larger than that of directional hydraulic fracturing.The new construction method was used to determine the field plan for fixed-length roof cutting.The roof formed a stable suspended structure and deformation of the main PLRR was improved after hydraulic fracturing.

关键词： Roof cutting Hydraulic fracture Stress shadow effect Retracement roadway Extended finite element method

Control of upper limb rehabilitation robot based on active disturbance rejection control

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IET Cyber-Systems and Robotics 2021年第4期3卷 347-362页

作者： Junchen Li Wenzhao zhang Yu Zheng Aimin An wenda Pan College of Electrical and Information Engineering Lanzhou University of TechnologyLanzhouChina Wenzhou Zhilong Intelligent Technology Co. LtdWenzhouChina Key Laboratory of Gansu Advanced Control for Industrial Processes LanzhouChina National Demonstration Center for Experimental Electrical and Control Engineering Education Lanzhou University of TechnologyLanzhouChina

The upper limb rehabilitation robot technology integrates rehabilitation medicine,human anatomy,mechanics,computer science,robotics,and many other disciplines.Its main function is to drive the affected limb to carry out rehabilitation training to restore the condition of patients with upper limb dyskinesia,which plays a great role in improving the quality of life.In this study,to resolve the problems of slow convergence speed and poor tracking accuracy due to the interference of patient spasms with the trajectory-tracking control of the upper limb rehabilitation robot,a novel algorithm based on active disturbance rejection control(ADRC)is adopted,and the convergence of its main structure is proved by the time-domain analysis method.First,this ADRC algorithm can obtain better trajectory-tracking performance due to its non-linear extended observer and non-linear feedback mechanism,even if the model suffers a strong disturbance or receives inaccurate information.Second,the non-linear tracking differentiator can guarantee to gain quick convergence speed.To validate this algorithm,a model of three degrees of freedom upper limb rehabilitation robot is established using MATLAB R2019b and three situations including strong spasm and weak spasm are carried out to prove the effectiveness and reliability of the control algorithm designed.

关键词： 3‐DOF rehabilitation robot active disturbance rejection control extended state observer

Memristive switching in two-dimensional BiSe crystals

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Nano Research 2023年第2期16卷 3188-3194页

作者： wenda Ma Junfeng Lu Shuaipeng Ge Li zhang Fengchang Huang Naiwei Gao Peiguang Yan Caofeng Pan College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro-nano Energy and SensorBeijing Institute of Nanoenergy and NanosystemsChinese Academy of SciencesBeijing 101400China College of Physics Nanjing University of Aeronautics and AstronauticsNanjing 211106China State Key Laboratory of Bioelectronics Southeast UniversityNanjing 210096China

In spite of the explosive rise of research on memristive switching,more improvements in tunability,versatility,and hetero-integration are required through the discovery and application of novel materials.Herein,we report resistance switching in nano-thick two-dimensional(2D)crystals of bismuth selenium(BiSe).The BiSe devices exhibit nonvolatile bipolar resistance switching,volatile switching,and electrical bistable behavior in different conditions.The different memristive behavior of BiSe devices may be related to the concentration of Bi ions in this Bi-rich structure,which directly affects the capability of filaments forming.Furthermore,the external mechanical strain is applied in modulation of multi-layer BiSe devices.The memristive BiSe devices show a large on/off ratio of~10^(4)and retention time of~104 s.The discovery of memristive switching behavior in multi-layer BiSe is attributed to the forming of Bi filaments.The resistance switching behavior in multi-layer BiSe demonstrates the potential application in the flexible memories and functional integrated devices.

关键词： bismuth selenium heterostructure resistance switching memristors flexible memories strain engineering

Long-term correction of hemorrhagic diathesis in hemophilia A mice by an AAV-delivered hybrid FⅧcomposed of the human heavy chain and the rat light chain

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Frontiers of Medicine 2022年第4期16卷 584-595页

作者： Jianhua Mao Yun Wang Wei zhang Yan Shen Guowei zhang wenda Xi Qiang Wang Zheng Ruan Jin Wang Xiaodong Xi Shanghai Institute of Hematology State Key Laboratory of Medical GenomicsCollaborative Innovation Center of HematologyRuijin Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghai 200025China Shanghai Institute of Hematology State Key Laboratory for Medical Genomics and Department of HematologyCollaborative Innovation Center of Systems BiomedicinePôle SinoFrançais des Sciences du Vivant et GenomiqueRuijin Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghai 200025China Research Center for Experimental Medicine Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghai 200025China The School of Medicine Hangzhou Normal UniversityHangzhou 310036China Shanghai Institute of Hypertension Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghai 200025China

Conventional therapies for hemophilia A(HA)are prophylactic or on-demand intravenous FⅧinfusions.However,they are expensive and inconvenient to perform.Thus,better strategies for HA treatment must be developed.In this study,a recombinant FⅧcDNA encoding a human/rat hybrid FⅧwith an enhanced procoagulant potential for adeno-associated virus(AAV)-delivered gene therapy was developed.Plasmids containing human FⅧheavy chain(hHC),human light chain(hLC),and rat light chain(rLC)were transfected into cells and hydrodynamically injected into HA mice.Purified AAV viruses were intravenously injected into HA mice at two doses.Results showed that the hHC+rLC protein had a higher activity than the hHC+hLC protein at comparable expression levels.The specific activity of hHC+rLC was about 4-to 8-fold higher than that of their counterparts.Hydrodynamic injection experiments obtained consistent results.Notably,the HA mice undergoing the AAV-delivered hHC+rLC treatment exhibited a visibly higher activity than those treated with hHC+hLC,and the therapeutic effects lasted for up to 40 weeks.In conclusion,the application of the hybrid FⅧ(hHC+rLC)via an AAV-delivered gene therapy substantially improved the hemorrhagic diathesis of the HA mice.These data might be of help to the development of optimized FⅧexpression cassette for HA gene therapy.

关键词： hemophilia A adeno-associated virus(AAV) human/rat hybrid factorⅧ gene therapy dual chain strategy

Mechanism of K/Ni Etching for Biochar-HO Gasification

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Journal of Harbin Institute of Technology(New series) 2023年

作者： Zhenyu Cheng Dongdong Feng Qi Shang Yijun Zhao WenDa Zhang Shaozeng Sun School of Energy Science and Engineering Harbin Institute of Technology

Biomass-H2O gasification is a complex thermochemical reaction， including three processes of volatile removal: homogeneous/heterogeneous reforming， biochar gasification and etching. The rate-determining step is biochar-H2O gasification and etching so the DFT is carried out to see the catalytic role of different metal elements(K/Ni) in the zigzag biochar model. The calculation results show that the gasification of biochar-H2O needs to go through four processes: dissociative adsorption of water， hydrogen transfer (hydrogen desorption， hydrogen atom transfer)， carbon dissolution and CO desorption. The energy barrier indicated that the most significant step in reducing the activation energy of K is reflected in the hydrogen transfer step， which is reduced from 374.14 kJ/mol to 152.41 kJ/mol; the catalytic effect of Ni is mainly reflected in the carbon dissolution step， which is reduced from 122.34 kJ/mol to 84.8 kJ/mol. The existence of K causes the edge to have a stronger attraction to H and does not destroy the π bonds of biochar molecules. The destruction of π bonds is mainly due to the role of H free radicals， while the destruction of π bonds will lead to easier C-C bond rupture. Ni shows a strong attraction to O in OH， which forms strong Ni-O chemical bonds. Ni can also destroy the aromatic structure directly， making the gasification easier to happen. This study explored the catalytic mechanism of K/Ni on the biochar-H2O gasification at the molecular level and looked forward to the potential synergy of K/Ni， laying a foundation for experimental research and catalyst design.

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The Role of Ti in the Preparation of SiC/7075 Aluminum Matrix Composite

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Journal of Wuhan University of Technology(Materials Science) 2020年第2期35卷 293-298页

作者： zhang wenda CHEN Chengcheng XU Hong CHE Luchang GUO Cuiping DU Zhenmin Department of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering North University of ChinaTaiyuan 030051China Southwest Technique and Engineering Institute Chongqing 400039China

SiC/7075 aluminum matrix composites were prepared by a liquid stirring method.The role of Ti facilitating the preparation of SiC/7075 aluminum matrix were studied by means of direct-reading spectrometer,scanning electron microscope,energy dispersive spectrometer,X-ray diffraction and the sessile drop method.The results show that the SiC content in the SiC/7075 composite increases with an increase of Ti addition.The addition of Ti can significantly improve the wettability of SiC/Al system,there is a critical value of above 0.5%of Ti content in improving the wettability of the Al/SiC system at 1173K.The temperature of the"non wetting-wetting"transition for the(Al-2Ti)/SiC system is about 1123K,the contact angle decreases to 88°at 200 seconds and reaches a stable contact angle of 28°at 2100 seconds.

关键词： aluminum matrix composites Al3Ti particles SiC particles wettability

Electroextraction of neodymium from LiCl-KCl melt using binary liquid Ga-Al cathode

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Journal of Rare Earths 2023年第8期41卷 1250-1257,I0005页

作者： Li Ding Xuepeng Wang Yongde Yan Valeri Smolenski wenda Xu Alena Novoselova Yun Xue Fuqiu Ma Xingmei zhang Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China Yantai Research Institute of Harbin Engineering University Yantai 264006China Institute of High-Temperature Electrochemistry UB RAS Ekaterinburg 620990Russia Department of Rare Metals and Nanomaterials Institute of Physics and TechnologyUral Federal UniversityEkaterinburg 620990Russia Yantai Standard Metrology Inspection&Test Center National Steam Flowrate Measurement StationYantai 264000China

The electrochemical behaviour of Nd(Ⅲ)ion was investigated on inert W,active Ga and Ga-AI cathodes.It is established that the reduction of Nd(Ⅲ)ion on the inert electrode is a consecutive two-step process while that on the active electrodes is a one-step process.The apparent standard potential of the Nd(Ⅲ)/Nd redox couple at different temperatures was determined by open-circuit chronopotentiometry and semi-differential method,and the relationship between temperature and apparent standard potential was further discussed.The thermodynamic properties of Nd in Ga and Ga-Al electrodes such as activity coefficient and activity were evaluated via intermittent coulomb titration and temperature dependence test,and the effect of temperature on activity coefficient was verified.Finally,Nd was successfully extracted in form of alloy from molten salt by galvanostatic electrolysis,in which the current efficiency of91.7%for the electroextraction indicates that the binary liquid Ga-Al electrode has favorable performance.

关键词： Rareearths Electroextraction Spent nuclear fuel Pyrochemical processing Lanthanides Binary liquid cathode