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A direct position determination method with combined TDOA and FDOA based on particle filter

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Chinese Journal of Aeronautics 2018年第1期31卷 161-168页

作者： Zhiyu LU Bin ba Jianhui WANG Wenchao LI Daming WANG China National Digital Switching System Engineering & Technological R&D Cente Zhengzhou 450000 China Jiuquan Satellite Launch Center Jiuquan 735000 China

The localization of a stationary transmitter using moving receivers is considered. The original Direct Position Determination （DPD） methods, with combined Time Difference of Arrival （TDOA） and Frequency Difference of Arrival （FDOA）, do not perform well under low Signal-to-Noise Ratio （SNR）, and worse still, the computation cost is difficult to accept when the computational capabilities are limited. To get better positioning performance, we present a new DPD algorithm that proves to be more computationally efficient and more precise for weak signals than the conventional approach. The algorithm partitions the signal received with the same receiver into multiple non-overlapping short-time signal segments, and then uses the TDOA, the FDOA and the coherency among the short-time signals to locate the target. The fast maximum likelihood estimation, one iterative method based on particle filter, is designed to solve the problem of high computation load. A secondary but important result is a derivation of closed-form expressions of the Cramer-Rao Lower Bound （CRLB）. The simulation results show that the algorithm proposed in this paper outperforms the traditional DPD algorithms with more accurate results and higher computational efficiency, and especially at low SNR, it is more close to the CRLB.

关键词： Direct position determination Cramer-Rao lower bound Frequency difference of arrival Time difference of arrival Particle filter

Preventive and control system for the life cycle of a pandemic

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Journal of Safety Science and Resilience 2022年第4期3卷 321-329页

作者： Chenyang Wang Rui ba Ranpeng Wang Hui Zhang Department of Engineering Physics Tsinghua UniversityBeijing 100084China

Herein,a matching method for varied epidemic phase characteristics and appropriate strategies is presented,aiming at the complexities of the novel coronavirus disease 2019 pandemic and the hysteresis of *** classical diffusion dynamic models of the epidemic spread are ***,the bass diffusion model is selected to study more characteristics of an epidemic,such as the diversities in regional internal and external infection ***,the classical division method vis-à-vis a pandemic life cycle is improved.A specific approach is proposed to portray more detailed characteristics of the pandemic by dividing it into more ***,a four-level epidemic prevention and control measure system is *** applicable phases and strategic effectiveness of each measure are integrated into the different phases of the pandemic life ***,the matching method is applied to analyze two cases of the spread of the outbreak in cities and significant *** findings provide a certain reference for the effectiveness of the matching method in the post-peak epidemic period.

关键词： Pandemic Life cycle Prevention and control system

Optimization of antioxidant activity by response surface methodology in hydrolysates of jellyfish(Rhopilema esculentum) umbrella collagen

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维普期刊数据库

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第8期10卷 572-579页

作者： Yong-liang ZHUANG Xue ZHAO ba-fang LI College of Food Science and Engineering Ocean University of China Qingdao 266003 China

To optimize the hydrolysis conditions to prepare hydrolysates of jellyfish umbrella collagen with the highest hydroxyl radical scavenging activity, collagen extracted from jellyfish umbrella was hydrolyzed with trypsin, and response surface methodology （RSM） was applied. The optimum conditions obtained from experiments were pH 7.75, temperature （T） 48.77 ℃, and enzyme-to-substrate ratio （[E]/[S]） 3.50%. The analysis of variance in RSM showed that pH and [E]/[S] were important factors that significantly affected the process （P〈0.05 and P〈0.01, respectively）. The hydrolysates of jellyfish umbrella collagen were fractionated by high performance liquid chromatography （HPLC）, and three fractions （HF-1〉3000 Da, 1000 Da〈HF-2〈3000 Da, and HF-3〈1000 Da） were collected. The HF-2 fraction had the highest hydroxyl radical scavenging activity with the highest yield compared with the other two fractions. Furthermore, HF-2 also showed the strongest Cu^2＋-chelating ability and the best tyrosinase-inhibitory activity.

关键词： Jellyfish umbrella collagen Hydrolysis Antioxidant activity Response surface methodology (RSM)

Velocity field of wave-induced local fluid flow in double-porosity media

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Science China(Physics,Mechanics & Astronomy) 2014年第6期57卷 1020-1030页

作者： ba Jing ZHANG Lin SUN WeiTao HAO ZhaoBing Geophysical Department Research Institute of Petroleum Exploration and Development School of Geosciences China University of Petroleum (Eastern China) Zhou Pei-Yuan Center for Applied Mathematics Tsinghua University Key Laboratory of Integrative Researches on Geophysics for Petroleum Institute of Geology and GeophysicsChinese Academy of Sciences

Under the excitation of elastic waves,local fluid flow in a complex porous medium is a major cause for wave dispersion and *** the local fluid flow process is simulated with wave propagation equations in the double-porosity medium,two porous skeletons are usually assumed,namely,host and *** them,the volume ratio of inclusion skeletons is *** previous studies have ignored the consideration of local fluid flow velocity field in inclusions,and therefore they can not completely describe the physical process of local flow oscillation and should not be applied to the situation where the fluid kinetic energy in inclusions cannot be *** this paper,we analyze the local fluid flow velocity fields inside and outside the inclusion,rewrite the kinetic energy function and dissipation function based on the double-porosity medium model containing spherical inclusions,and derive the reformulated Biot-Rayleigh(BR)equations of elastic wave propagation based on Hamilton’s *** present simulation examples with different rock and fluid *** between BR equations and reformulated BR equations show that there are significant differences in wave response ***,we compare the reformulated BR equations with the previous theories and experimental data,and the results show that the theoretical results of this paper are correct and effective.

关键词： double-porosity medium elastic wave propagation local fluid flow velocity dispersion Biot-Rayleigh equations petro-physical experiment

Nonlinear Mathematical Modeling and Sensitivity Analysis of Hydraulic Drive Unit

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 999-1011页

作者： KONG Xiangdong YU Bin QUAN Lingxiao ba Kaixian WU Liujie National Engineering Research Center for Local Joint of Advanced Manufacturing Technology and Equipment Yanshan University Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University School of Mechanical Engineering Yanshan University

The previous sensitivity analysis researches are not accurate enough and also have the limited reference value, because those mathematical models are relatively simple and the change of the load and the initial displacement changes of the piston are ignored, even experiment verification is not conducted. Therefore, in view of deficiencies above, a nonlinear mathematical model is established in this paper, including dynamic characteristics of servo valve, nonlinear characteristics of pressure-flow, initial displacement of servo cylinder piston and friction nonlinearity. The transfer function block diagram is built for the hydraulic drive unit closed loop position control, as well as the state equations. Through deriving the time-varying coefficient items matrix and time-varying free items matrix of sensitivity equations respectively, the expression of sensitivity equations based on the nonlinear mathematical model are obtained. According to structure parameters of hydraulic drive unit, working parameters, fluid transmission characteristics and measured friction-velocity curves, the simulation analysis of hydraulic drive unit is completed on the MATLAB/Simulink simulation platform with the displacement step 2 mm, 5 mm and 10 mm, respectively. The simulation results indicate that the developed nonlinear mathematical model is sufficient by comparing the characteristic curves of experimental step response and simulation step response under different constant load. Then, the sensitivity function time-history curves of seventeen parameters are obtained, basing on each state vector time-history curve of step response characteristic. The maximum value of displacement variation percentage and the sum of displacement variation absolute values in the sampling time are both taken as sensitivity indexes. The sensitivity indexes values above are calculated and shown visually in histograms under different working conditions, and change rules are analyzed. Then the sensitivity index

关键词： nonlinear mathematical model hydraulic drive unit valve-controlled symmetrical cylinder sensitivity analysis sensitivity index

International Szent-Gyorgyi Prize for Progress in Cancer Research:basic and translational research recognition Mary-Claire King received the 2016 Prize for her pioneering research that demonstrated the first evidence of genetic predisposition to breast cancer

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Chinese Journal of Cancer 2017年第11期36卷 533-536页

作者： Hali Hartmann Jie Zhao Sujuan ba National Foundation for Cancer Research

The Szent-Gy?rgyi Prize for Progress in Cancer Research is a prestigious scientific award sponsored by the National Foundation for Cancer Research(NFCR)-a leading cancer research charitable organization in the United States that supports innovative cancer research globally with the ultimate goal to cure cancer. The coveted Szent-Gy?rgyi Prize annually honors a scientist whose seminal discovery or body of work has resulted in, or led toward, notable contributions to cancer prevention, diagnosis, or treatment; and the discovery has had a high direct impact of saving people's lives. In addition, the prize promotes public awareness of the importance of basic cancer research and encourages the sustained investment needed to accelerate the translation of these research discoveries into new cancer treatments. In 2016, NFCR's Szent-Gy?rgyi Prize Selection Committee was unanimous in its decision to recognize an icon in human disease genetics, Dr. Mary-Claire King, for her pioneering research that demonstrated the first evidence of genetic predisposition to breast cancer. Her proof of existence of BRCA1 gene and its location has made genetic screening for breast and ovarian cancers possible, saving lives of many people who are at high risk with inherited BRCA1 mutations.

关键词： The National Foundation for Cancer Research The Szent-Gyorgyi Prize Mary-Claire King BRCA1 and genetic testing

Cracking Tendency of Restrained Concrete at Early Ages

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Journal of Wuhan University of Technology(Materials Science) 2008年第2期23卷 263-267页

作者： ba Hengjing SU Anshuang GAO Xiaojian TAO Qi School of Civil Engineering Harbin Institute of Technology Harbin 150006 China

A modified testing system characterized by full automation, steady operation and high accuracy of strain and stress measurements was developed to determine the cracking tendency of high strength concrete （HSC） in restrained condition at early ages. The shrinkage stress and the tensile creep behavior of HSC at early ages were investigated. The influence of W/C ratio and curing conditions on the early-age shrinkage stress and tensile creep was evaluated. It was found that the lower W/C ratio and drying curing condition resulted in higher shrinkage stress, stress induced tensile creep and greater cracking tendency.

关键词： cracking tendency shrinkage stress tensile creep concrete early ages

RO-heparin Inhibits L-Selectin-mediated Neutrophils Adhesion to Vascular Endothelium Under Flow Conditions

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Chemical Research in Chinese Universities 2006年第3期22卷 302-307页

作者： CHEN Zhi-hong XU Li ba Xue-qing ZENG Xian-lu Institute of Genetics and Cytology Northeast Normal University Changchun 130024 P. R. China School of Life Science Mudanjiang Medical University Mudanjiang 157011 P. R. China Biology Section College of Changchun Traditional Chinese Medicine Changchun 130017 P. R. China

Selectins are carbohydrate-binding cell adhesion molecules that play a major role in the initiation of inflammatory responses. Accumulaed evidence has suggested that heparin＇s anti-inflammatory effects are mainly mediated by blocking L-or P-selectin-initiated cell adhesion. Recently, we have reported that periodate-oxidized, borohydridereduced heparin （RO-heparln） can inhibit P-selectin-mediated acute inflammation. Here we further examined the effect of RO-heparin on the adhesion of L-selectin-mediated leukocytes to vascular endothelium under flow conditions in vivo and in vitro. The results show that RO-heparin with a low anticoagulant activity can effectively reduce leucocyte roiling on thioglycoUate-induced rat mesenterlc venules and L-selectin-metadiated neutrophil roiling on TNF-α-induced human umbilical vein endothelial cells（HUVECs） under flow conditions. Our findings suggest that the effect of RO-heparin on inflammatory responses is mainly a result of its inhibiting the interaction between P- or L-selectin and its ligands. The findings also suggest that RO-heparin may be useful in preventing inflammation diseases.

关键词： RO-heparin Neutrophils adhesion L-selectin Human umbilical vein endothelial cells (HUVECs)

A simulation-based software to support the real-time operational parameters selection of tunnel boring machines

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Underground Space 2024年第1期14卷 176-196页

作者： Yaman Zendaki ba Trung Cao Abdullah Alsahly Steffen Freitag Gunther Meschke Institute for Structural Mechanics Ruhr University BochumBochum 44801Germany Institute for Structural Analysis Karlsruhe Institute of TechnologyKarlsruhe 76131Germany

With the fact that the main operational parameters of the construction process in mechanized tunneling are currently selected based on monitoring data and engineering experience without exploiting the advantages of computer methods,the focus of this work is to develop a simulation-based real-time assistant system to support the selection of operational *** choice of an appropriate set of these parameters(i.e.,the face support pressure,the grouting pressure,and the advance speed)during the operation of tunnel boring machines(TBM)is determined by evaluating different tunneling-induced soil-structure interactions such as the surface settlement,the associated risks on existing structures and the tunnel lining *** evaluate soil-structure behavior,an advanced process-oriented numerical simulation model based on the finite cell method is *** enable the real-time prediction capability of the simulation model for a practical application during the advancement of TBMs,surrogate models based on the Proper Orthogonal Decomposition and Radial basis Functions(POD-RBF)are *** proposed approach is demonstrated through several synthetic numerical examples inspired by the data of real tunnel *** developed methods are integrated into a user-friendly application called SMART to serve as a support platform for tunnel engineers at construction *** to each user adjustment of the input parameters,i.e.,each TBM driving scenario,approximately two million outputs of soil-structure interactions are quickly predicted and visualized in seconds,which can provide the site engineers with a rough estimation of the impacts of the chosen scenario on structural responses of the tunnel and above ground structures.

关键词： Numerical simulation Surrogate model Real-time prediction Proper orthogonal decomposition Radial basis functions TBM operation Smart construction