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Sequential Feature Screening for Generalized Linear Models with Sparse Ultra-High Dimensional Data

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Journal of Systems Science & Complexity 2020年第2期33卷 510-526页

作者： zhang Junying WANG Hang zhang Riquan zhang jiajia Department of Mathematics Taiyuan University of TechnologyTaiyuan 030024China Department of Statistics East China Normal UniversityShanghai 200241China Department of Epidemiology and Biostatistics University of South CarolinaColumbia 20295USA

This paper considers the iterative sequential lasso(ISLasso)variable selection for generalized linear model with ultrahigh dimensional feature *** ISLasso selects features by estimated parameter sequentially iteratively for the second order approximation of likelihood function where the features selected depend on regulatory *** procedure stops when extended BIC(EBIC)reaches a *** study demonstrates that the new method is a desirable approach over other methods.

关键词： Extended BIC generalized linear model sequential lasso sequential iteration variable screening variable selection

Modeling Morning Commute with Different Kinds of Activities Based on Bottleneck Model

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Journal of Systems Science and Systems Engineering 2023年第4期32卷 444-461页

作者： Qing Dai jiajia zhang Zhengkui Lin School of Management Science and Engineering Dongbei University of Finance and EconomicsDalian116025China School of Maritime Economics and Management Dalian Maritime UniversityDalian116026China

Morning commute problem has always been concerned by researchers in transportation research *** the bottleneck existing in the road network between home and school,this paper studies the household travel with different kinds of activities,i.e.,home-school-home trip and home-school-workplace *** just send their children to school and then go home,which is named school *** need to send their children to school firstly and then go to work,which is named household ***,according to the proportions of two types of travelers and school-work start time difference,the possible equilibrium cases are solved and the conditions for the occurrence of each case are *** from the traditional bottleneck model with a unique equilibrium traffic pattern,the mixed travel case has six possible equilibrium traffic ***,the cost of traveler is analyzed for all possible equilibrium traffic *** shows that equilibrium trip costs of two types of travelers are more sensitive to the number of travelers in that class than the number in another class in all possible equilibrium ***,the influence of school-work start time difference on the total travel cost is *** shows that the total system travel cost can be reduced by appropriately adjusting the difference of school-work start time.

关键词： Morning commute bottleneck model household travel school travel

Nonlinear simultaneous inversion of pore structure and physical parameters based on elastic impedance

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Science China Earth Sciences 2021年第6期64卷 977-991页

作者： Hongbing LI jiajia zhang Haojie PAN Qiang GAO Research Institute of Petroleum Exploration and Development PetroChina Company LimitedBeijing100083China School of Geosciences China University of Petroleum(East China)Qingdao266580China College of Geophysics and Petroleum Resources Yangtze UniversityWuhan430100China

Carbonate reservoirs have complex pore structures,which not only significantly affect the elastic properties and seismic responses of the reservoirs but also affect the accuracy of the prediction of the physical *** existing rockphysics inversion methods are mainly designed for clastic rocks,and the inversion objects are generally porosity and water *** data used are primarily based on the elastic parameters,and the inversion methods are mainly linear *** date,there has been a lack of a simultaneous pore structure and physical parameter inversion method for carbonate *** solve these problems,a new Bayesian nonlinear simultaneous inversion method based on elastic impedance is *** method integrates the differential effective medium model of multiple-porosity rocks,Gassmann equation,Amplitude Versus Offset(AVO)theory,Bayesian theory,and a nonlinear inversion algorithm to achieve the simultaneous quantitative prediction of the pore structure and physical parameters of complex porous *** forward modeling indicates that the contribution of the pore structure,i.e.,the pore aspect ratio,to the AVO response and elastic impedance is second only to that of porosity and is far greater than that of water *** application to real data shows that the new inversion method for determining the pore structure and physical parameters directly from pre-stack data can accurately predict a reservoir's porosity and water saturation and can evaluate the pore structure of the effective reservoir.

关键词： Carbonate rocks Pore structure Physical parameters Elastic impedance Nonlinear Rock-physics inversion

Bifurcation analysis and optimal control of COVID-19 with exogenous reinfection and media coverages

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International Journal of Biomathematics 2023年第3期16卷 83-118页

作者： jiajia zhang Yuanhua Qiao Yan zhang Faculty of Science Beijing University of Technology Beijing 100124P.R.China

In this paper,a SEIR epidemic model related to media coverage and exogenous reinfections is established to explore the transmission dynamics of *** basic reproduction number is calculated using the next generation matrix ***,the existence of equilibrium points is investigated,and different kinds of equilibrium points indicate that the disease may disappear,or exist that result in different quantity of susceptible individuals,pre-symptomatic infected individuals and symptomatic infected *** stability of the equilibria is discussed by a geometric approach,and it is found that controlling reproduction number to be lower than 1 is not suficient for eradication of ***,transcritical bifurcation is explored,and it is found that improving the ratio of exogenous reinfection may lead to backward bifurcation under poor medical conditions,which indicates that two endemic equilibrium points ***,to investigate the infuence of parameters on the basic reproduction,sensitivity analysis is done to choose relatively sensitive parameters,and the parameters for treatment and media coverage are *** optimal control model is established to balance the treatment and media *** exploring the existence and the uniqueness of the optimal control solution,the optimal control strategies are ***,we run numerical simulations to verify the theoretical analysis on actual data of China,and the data from the four different states of India is used for forecasting the situation of infected individuals in a short *** is found by the simulation that the co-function of treatment and media coverage results in the reduced number of infectious individuals.

关键词： COVID-19 backward bifurcation globally stable optimal control

Onfocus detection: identifying individual-camera eye contact from unconstrained images

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Science China(Information Sciences) 2022年第6期65卷 5-16页

作者： Dingwen zhang Bo WANG Gerong WANG Qiang zhang jiajia zhang Jungong HAN Zheng YOU School of Mechano-Electronic Engineering Xidian University State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua University Beijing Jingzhen Medical Technology Ltd. Computer Science Department Aberystwyth University

Onfocus detection aims at identifying whether the focus of the individual captured by a camera is on the camera or not. Based on the behavioral research, the focus of an individual during face-to-camera communication leads to a special type of eye contact, i.e., the individual-camera eye contact, which is a powerful signal in social communication and plays a crucial role in recognizing irregular individual status(e.g., lying or suffering mental disease) and special purposes(e.g., seeking help or attracting fans). Thus,developing effective onfocus detection algorithms is of significance for assisting the criminal investigation,disease discovery, and social behavior analysis. However, the review of the literature shows that very few efforts have been made toward the development of onfocus detector owing to the lack of large-scale public available datasets as well as the challenging nature of this task. To this end, this paper engages in the onfocus detection research by addressing the above two issues. Firstly, we build a large-scale onfocus detection dataset, named as the onfocus detection in the wild(OFDIW). It consists of 20623 images in unconstrained capture conditions(thus called “in the wild”) and contains individuals with diverse emotions, ages, facial characteristics, and rich interactions with surrounding objects and background scenes. On top of that, we propose a novel end-to-end deep model, i.e., the eye-context interaction inferring network(ECIIN), for onfocus detection, which explores eye-context interaction via dynamic capsule routing. Finally, comprehensive experiments are conducted on the proposed OFDIW dataset to benchmark the existing learning models and demonstrate the effectiveness of the proposed ECIIN.

关键词： Computer Vision onfocus detection Deep Learning deep neural network capsule routing computer vision deep learning Deep neural network

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Coverage Probability Analysis for Full-Duplex Relay Aided Device-to-Device Communications Networks

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China Communications 2016年第11期13卷 60-67页

作者： Bin Zhong jiajia zhang Qian Zeng Xiaoming Dai School of Information and Electrical Engineering Hunan University of Science and Technology Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services University of Science and Technology Beijing Business School Xiangtan University

The coverage probability of both the cellular users and the Device-to-Device(D2D) users are analyzed. We assume that the cellular users are able to communication with the Base Station(BS) either by relying on the assistance of Full-Duplex(FD) mode relays or via direct user-to-BS links with high-enough Signal-to-Interference-plus-Noise-Ratio(SINR). Note that the FD-mode devices are capable of simultaneously operating in two modes,i.e. the D2D mode and the cooperative relay mode,with the sum power consumption at these devices kept constant. The closedform expressions for coverage probability of both tier users are derived. After that,numerical analyses are provided,showing that the coverage probability of the both the cellular and the D2D users can be substantially influenced by a variety of parameters,including the power allocation factor of the relays,the density of users,and the self-interference imposed on the FD mode relays,etc. Furthermore,in the D2D enabled networks,it is shown that the FD relay aided transmission is beneficial to enhancing the coverage probability of the cellular users if the target SINR is lower than 5 d B.

关键词： cooperative communication coverage probability Full-duplex device-to-device

Energy transfer process of Nd^(3+)/Ho3+co-doped fluoride halide glasses with anion substituted multi-wavelength tunable mid-infrared luminescence

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Journal of Rare Earths 2021年第11期39卷 1344-1352,I0002页

作者： Hao Yin Xiaosong zhang Lan Li jiajia zhang Zhaowei zhang Xin Liu Xiaokai Gong Rukun Ding Key Laboratory of Display Materials and Photoelectric Devices Ministry of EducationTianjin Key Laboratory for Photoelectric Materials and DevicesNational Demonstration Center for Experimental Function Materials EducationInstitute of Material PhysicsSchool of Materials Science and EngineeringTianjin University of TechnologyTianjin 300384China

Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was *** order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state density of the *** the same time,Nd^(3+)was introduced to transfer the energy to Ho^(3+)pumped with a 793 nm laser(Nd^(3+):4 F5/2,4 F3/2→Ho^(3+):5 I6).The effect of different halogen ion on the luminescent properties of the fluoride halide glass was *** results show that the luminescent intensity of infrared increases with the introduction of different halogen *** comparison,it is found that the sample with I-has the strongest luminescence of 1064 nm,2.0μm and 2.9μ*** is consistent with the calculated J-O intensity *** addition,the 2.0 and 2.9μm emission of Ho^(3+)pumped with a 450 nm laser will not disappear.A mid-infrared sample with multi-wavelength excitation and multi-wavelength emission can be ***^(3+)/Ho^(3+)co-doped fluoride halide glasses with 1064 nm,2.0μm and 2.9μm luminescence were prepared by melt quenching *** luminescent mechanism and the energy transfer process between the two ions of Nd^(3+)/Ho^(3+)co-doped fluoride halide glass were *** J-O parameters,luminescence lifetime and absorption emission cross-sectional area of Ho^(3+)and Nd^(3+)were calculated,*** is found that the value ofΩ2 in the glass matrix increases with the introduction of different halogen ions,whileΩ4 andΩ6 do not change obviously in different glass *** is because the environment of the crystal field around the rare earth ions *** crystal phase and phonon energy of the sample were analyzed by X-ray diffraction pattern and a Fourier transform infrared spectrometer,*** on the above spectra and data(phonon energy is 634.71 cm-1),it can be predicted that Nd^(3+)/Ho^(3+)co-doped fluoride halide glass is a potential mid-infrared luminescent material.

关键词： Halogen ion substitution Rare earth ion Multi-wavelength tunable Energy transfer mechanism Mid-infrared emission

Nd^(3+)/Yb^(3+) co-doped mid-infrared luminescence fluorobromide glass with energy transfer and zero-thermal-quenching IR emission

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Journal of Rare Earths 2021年第9期39卷 1049-1055页

作者： jiajia zhang Xiaosong zhang Hao Yin Lan Li Zhaowei zhang Xin Liu Xiaokai Gong Rukun Ding School of Materials Science and Engineering Institute of Material PhysicsKey Laboratory of Display Materials and Photoelectric DevicesMinistry of EducationTianjin Key Laboratory for Photoelectric Materials and Devicesand National Demonstration Center for Experimental Function Materials EducationTianjin University of TechnologyTianjin 300384China

Nd^(3+)/Yb^(3+)co-doped fluorobromide glass samples were prepared by melt *** mid-infrared(MIR)luminescence of the Nd^(3+)/Yb^(3+)co-doped fluorobromide glass was investigated by Br-doping reduces the phonon state density of the *** 3.9μm MIR luminescence of the samples excited at 793 and 980 nm pump excitation was investigated in *** is an effective mutual energy transfer process between Nd^(3+)and Yb^(3+).It is proved under 793 nm excitation that the luminescence of Nd^(3+)at 3.9μm is reduced by effective energy transfer from,Nd^(3+):2 H11/2→Yb^(3+):2 F5/2,At the same time,it is proved that the effective energy transfer from Yb^(3+):2 F5/2→Nd^(3+):2 H11/2 under the excitation of 980 nm enhances the luminescence of Nd^(3+)at 3.9μ*** addition,it is found that the samples still have good infrared(IR)luminescent properties when the temperature *** emission cross-sectional area and the absorption cross-sectional area areσem(3.87×10^(-20)cm^(2))andσabs(4.25×10^(-20)cm^(2)).The fluorescence decay characteristics of the sample at 3.9μm at the 2 H11/2 level were investigated and the fluorescence lifetime was *** gain performance of the sample was calculated and analyzed,which can reach 4.25×10^(-20)cm^(2).Those results prove that Nd^(3+)/Yb^(3+)co-doped fluorobromide glass is the potential mid-infrared laser gain material.

关键词： Mid-infrared luminescence Fluorobromide glass Nd3+/Yb3+co-doped Energy transfer Rare earths

Giant negative electrocaloric effect measured by indirect method in X-ray irradiated P(VDF-TrFE)films

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Journal of Materiomics 2024年第3期10卷 624-631页

作者： Bo Li Bin Yang Hong zhang jiajia zhang Qianjin Wang Weishu Liu Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhenGuangdong 518055China Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices Southern University of Science and TechnologyShenzhenChina College of Physics and Electronic Information Yunnan Normal UniversityYunnan Kunming 650500China The Science and Technology on Reliability Physics and Application of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research InstituteGuangzhou 510610China

Flexible solid-state cooling devices with high efficiency are attracted to ferroelectric polymers with excellent negative electrocaloric(EC)*** is challenging to obtain a large negative EC effect in ferroelectric polymers due to the lack of tunable techniques.A giant negative EC response was obtained in the poly(vinylidene fluoride-trifluoroethylene)copolymers(P(VDF-TrFE),70/30,in mole ratio)irra-diated with high-energy *** irradiated P(VDF-TrFE)films showed an adiabatic temperature change of-13.5 K at 40 MV/m under a dose of 5 Mrad(1 Mrad=10^(4) J/kg)obtained by the indirect *** significant negative EC effect is attributed to the enhancement of crystalline due to the entry of polymer molecules into the amorphous to crystalline structure and the reduction of heat ca-pacity due to the increase of *** addition,X-ray irradiation improves the dielectric coefficient from 15 to *** research indicates that irradiation can modify the negative EC properties of ferro-electric polymers for solid-state cooling.

关键词： Negative electrocaloric effects X-rays radiation P(VDF-TrFE)films