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Early changes in white blood cell,C-reactive protein and procalcitonin levels in children with severe multiple trauma

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World Journal of Emergency Medicine 2022年第6期13卷 448-452页

作者： Cai-fang xu Ming-chao Huo Jin-hui Huang Chun-feng Liu Wei xu The Pediatrics Department Shengjing Hospital of China Medical UniversityShenyang 110004China Department of Critical Care Medicine Shanghai Children’s HospitalShanghai Jiao Tong University School of MedicineShanghai 200062China

BACKGROUND:To analyze early changes in white blood cells(WBCs),C-reactive protein(CRP)and procalcitonin(PCT)in children with multiple trauma,before secondary inflammation ***:This single-center retrospective study collected data from patients with blunt traumatic injury admitted to the pediatric intensive care unit(PICU).According to the prognostic outcome of 28 d after admission to the PICU,patients were divided into survival group(n=141)and non-survival group(n=36).Characteristics between the two groups were *** operation characteristic(ROC)curve analysis was conducted to evaluate the capacity of different biomarkers as predictors of ***:The percentages of children with elevated WBC,CRP,and PCT levels were 81.36%,31.07%,and 95.48%,*** in the non-survival group presented a statistically significantly higher injury severity score(ISS)than those in the survival group:37.17±16.11 vs.22.23±11.24(t=6.47,P<0.01).WBCs were also higher in non-survival group than in the survival group([18.70±8.42]×109/L vs.[15.89±6.98]×109/L,t=2.065,P=0.040).There was no significant difference between the survival and non-survival groups in PCT or *** areas under the ROC curves of PCT,WBC and ISS for predicting 28-day mortality were 0.548(P=0.376),0.607(P=0.047)and 0.799(P<0.01),***:Secondary to multiple trauma,PCT levels increased in more patients,even if their WBC and CRP levels remained ***,early rising WBC and ISS were superior to PCT at predicting the mortality of multiple trauma patients in the PICU.

关键词： Pediatric Procalcitonin Injury severity score Multiple trauma

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CFD simulation of internal-loop airlift reactor using EMMS drag model

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Particuology 2015年第2期13卷 124-132页

作者： Tingting xu xuedong Jiang Ning Yang Jiahua Zhu State Key Laboratory of Multi-Phase Complex Systems Institute of Process EngineeringChinese Academy of Sciences University of Chinese Academy of Sciences Department of Chemical Engineering Xi'an Jiaotong University School of Chemical Engineering Sichuan University

The simulation of internal-loop airlift reactors is challenging because complex meso-scale structures exist in different sections of the reactor, separated by the draft tube. This paper reports on the computational fluid dynamics （CFD） simulation of internal-loop airlift reactors using a new drag model derived from the dual-bubble-size （DBS） model, an extended energy-minimization multi-scale （EMMS） approach for gas-liquid flows. Compared with the traditional Schiller-Naumann （S-N） correlation, the new model improves the simulation of gas holdup in the riser and downcomer significantly. In particular, gas holdup and circulation of two-phase flow can be modeled successfully using the new model, whereas traditional drag models such as the S-N correlation show an absence of gas in the downcomer. The simulation demonstrates the advantage and potential of this new model for internal-loop airlift reactors.

关键词： Computational fluid dynamics Internal-loop Airlift Multi-scale Multiphase flow Hydrodynamics

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Chatter stability prediction in four-axis milling of aero-engine casings with bull-nose end mill

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Chinese Journal of Aeronautics 2015年第6期28卷 1766-1773页

作者： Zhou xu Zhang Dinghua Luo Ming Wu Baohai Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of EducationNorthwestern Polytechnical University

An analytical model for chatter aero-engine casings is presented in this paper stability prediction in bull-nose end milling of And the mechanics and dynamics variations due to the complex cutter and workpiece geometry are considered by analyzing the effects of the lead angle on the milling process. Firstly, the tool-workpiece engagement region is obtained by using a previously developed method and divided into several disk elements along the tool-axis direction. Secondly, a 3D dynamic model for stability limit calculation is developed and simplified into a 1D model in normal direction considering only the dominant mode of the workpiece. Then the cutting force coefficients, the start and exit angles corresponding to each disk element are determined. And the total stability lobe diagram is calculated using an iterative algorithm. Finally, several experimental tests are carried out to validate the feasibility and effectiveness of the proposed ~rediction approach.

关键词： Aero-engine casings Bull-nose end mill Chatter Four-axis milling Stability lobe diagram

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Application of Active Flow Control Technique for Gust Load Alleviation

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Chinese Journal of Aeronautics 2011年第4期24卷 410-416页

作者： xu Xiaoping ZHU Xiaoping ZHOU Zhou FAN Ruijun National Key Laboratory of Science and Technology on UAV Northwestern Polytechnical University Xi 'an 710072 China Research Institute of Unmanned Aerial Vehicle Northwestern Polytechnical University Xi 'an 710072 China

A new gust load alleviation technique is presented in this paper based on active flow control. Numerical studies are conducted to investigate the beneficial effects on the aerodynamic characteristics of the quasi ＂Global Hawk＂ airfoil using arrays of jets during the gust process. Based on unsteady Navier-Stokes equations, the grid-velocity method is introduced to simulate the gust influence, and dynamic response in vertical gust flow perturbation is investigated for the airfoil as well. An unsteady surface transpiration boundary condition is enforced over a user specified portion of the airfoil’s surface to emulate the time dependent velocity boundary conditions. Firstly, after applying this method to simulate typical NACA0006 airfoil gust response to a step change in the angle of attack, it shows that the indicial responses of the airfoil make good agreement with the exact theoretical values and the calculated values in references. Furthermore, gust response characteristic for the quasi ＂Global Hawk＂ airfoil is analyzed. Five kinds of flow control techniques are introduced as steady blowing, steady suction, unsteady blowing, unsteady suction and synthetic jets. The physical analysis of the influence on the effects of gust load alleviation is proposed to provide some guidelines for practice. Numerical results have indicated that active flow control technique,as a new technology of gust load alleviation, can affect and suppress the fluid disturbances caused by gust so as to achieve the purpose of gust load alleviation.

关键词： active flow control gust response gust alleviation numerical simulation aerodynamics unsteady flow airfoil

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Biomimetic Material Simulating Solar Spectrum Reflection Characteristics of Yellow Leaf

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Journal of Bionic Engineering 2018年第4期15卷 741-750页

作者： Kai xu Yang Lin xuezhong Wei Hong Ye Department of Thermal Science and Energy Engineering University of Science and Technology of China Hefei 230027 China Beijing Institute of Space Launch Technology Beijing 100076 China

To counter the threat of hyperspectral detection, it is necessary to develop biomimetic materials to simulate the solar spectral re- flection characteristics of plant leaf accurately. Two kinds ofmembranaceous yellow biomimetic materials were prepared by dispersing the particles of chrome titanium yellow and iron oxide yellow as fillers in polyvinyl alcohol films respectively. Reflectance and transmittance of the biomimetic materials were measured, and absorption and scattering coefficients of the biomimetic materials were inverted with a four-flux model. Results indicate that the biomimetic material adopting chrome titanium yellow particles can simulate the solar spectrum reflection characteristics of yellow leaf because of the similar absorption and scattering characteristics. The biomimetic material adopting iron oxide yellow particles cannot simulate the spectrum reflection characteristics of yellow leaf near the wavelength of 900 nm due to the characteristic absorption of the iron oxide. When the volume fraction of the chrome titanium yellow particles is lower than 2.12%, the absorption and scattering coefficients both increase approximately linearly with the volume fraction, indicating that the particles can scatter radiation independently. Therefore, the reflectance of the biomimetic material can be regulated through linearly changing of the volume fraction of the chrome titanium yellow particles.

关键词： biomimetic material yellow leaf solar spectrum reflection four-flux model absorption coefficient scattering coefficient

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Finite-time stabilization of switched dynamical networks with quantized couplings via quantized controller

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Science China(Technological Sciences) 2018年第2期61卷 299-308页

作者： YANG XinSong CAO JinDe xu Chen FENG JianWen School of Mathematical Sciences Chongqing Normal UniversityChongqing 401331China School of Mathematics and Research Center for Complex Systems and Network SciencesSoutheast UniversityNanjing 210096China College of Mathematics and Statistics Shenzhen UniversityShenzhen 518060China

This paper concerns the stabilization of switched dynamical networks with logarithmic quantization couplings in a settling *** switching sequence is constrained by hybrid dwell time. Controller is designed by using limited information. Due to the quantization and switching, traditional finite-time analysis methods cannot be utilized directly. By designing multiple Lyapunov functions and constructing comparison systems, a general criterion formulated by matrix inequalities is first given. Then specific conditions in terms of linear matrix inequalities are established by partitioning the dwell time and using convex combination technique. An optimal algorithm is proposed for the estimation of settling time. Numerical simulations are given to verify the effectiveness of the theoretical results.

关键词： dwell time finite time quantized couplings quantized controller switching

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Design System of the Two-step Gear Reducer on Case-based Reasoning

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Chinese Journal of Mechanical Engineering 2009年第5期22卷 671-679页

作者： JI Aimin HUANG Quansheng xu Huanmin CHEN Zhengming College of Mechanical and Electrical Engineering Hohai University Changzhou 213022 China State Key Lab ofCAD＆CG Zhejiang University Hangzhou 310058 China College of Computer and Information Engineering Hohai University Changzhou 213022 China

The design of the two-step gear reducer is a tedious and time-consuming process. For the purpose of improving the efficiency and intelligence of design process, case-based reasoning（CBR） technology was applied to the design of the two-step gear reducer. Firstly, the current design method for the two-step gear reducer was analyzed and the principle of CBR was described. Secondly, according to the characteristics of the reducer, three key technologies of CBR were studied and the corresponding methods were provided, which are as follows：（a） an object-oriented knowledge representation method, （b） a retrieval method combining the nearest neighbor with the induction indexing, and （c） a case adaptation algorithm combining the revision based on rule with artificial revision. Also, for the purpose of improving the credibility of case retrieval, a new method for determining the weights of characteristics and a similarity formula were presented, which is a combinatorial weighting method with the analytic hierarchy process（AHP） and roughness set theory. Lastly, according to the above analytic results, a design system of the two-step gear reducer on CBR was developed by VC＋＋, UG and Access 2003. A new method for the design of the two-step gear reducer is provided in this study. If the foregoing developed system is applied to design the two-step gear reducer, design efficiency is improved, which enables the designer to release from the tedious design process of the gear reducer so as to put more efforts on innovative design. The study result fully reflects the feasibility and validity of CBR technology in the process of the design of the mechanical parts.

关键词： two-step gear reducer case-based reasoning(CBR) weights of characteristics similarity

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Flow boiling heat transfer in copper foam fin microchannels with different fin widths using R134a

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Science China(Technological Sciences) 2023年第11期66卷 3245-3258页

作者： GAO WuHuan FU Kai xu XiangHua LIANG XinGang School of Aerospace Engineering Key Laboratory for Thermal Science and Power Engineering of Ministry of EducationTsinghua UniversityBeijing 100084China Beijing Institute of Astronautical Systems Engineering Beijing 100076China

Heat sinks of copper foam fin microchannels are developed to deal with cooling *** heat sinks consist of fins made of copper foam and *** channels are 0.5 mm in width and 1 mm in height,and the fins are 0.5 and 2.0 mm in *** boiling experiments are conducted using R134a at subcooled and saturated inlet *** heat flux is between 22 and 172 W/cm^(2),and the mass flux ranges from 264 to 1213 kg/(m^(2)s).The influence of the quality,the heat flux,and the mass flow rate on the heat transfer coefficient is *** is found that wider fin raises the heat transfer coefficient.A correlation is developed based on heat transfer mechanisms,and it predicts the experimental result with a 12%mean absolute *** with a solid fin microchannels heat sink,the heat transfer coefficient of the copper foam fin microchannels is higher(up to 60%)when the heat flux is lower than 100 W/cm^(2).The copper foam fin microchannels may enhance the heat transfer coefficient and reduce the pressure drop at the same time.

关键词： microchannel copper foam flow boiling heat transfer correlation

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Simulation-based security of function-hiding inner product encryption

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Science China(Information Sciences) 2018年第4期61卷 215-225页

作者： Qingsong ZHAO Qingkai ZENG Ximeng LIU Huanliang xu State Key Laboratory for Novel Software Technology Nanjing University Department of Computer Science and Technology Nanjing University College of Information Science and Technology Nanjing Agricultural University School of Information Systems Singapore Management University

Functional encryption(FE)[1,2]is a modern type of encryption scheme that extends several previous notions and allows tremendous flexibility in controlling and computing on encrypted *** enables an authority to derive ... 详细信息

关键词： PP IPE MSK Simulation-based security of function-hiding inner product encryption

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Enhanced dechlorination of 2,4-dichlorophenol by recoverable Ni/Fe–Fe_3O_4 nanocomposites

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Journal of Environmental Sciences 2016年第10期28卷 92-101页

作者： Cancan xu Rui Liu Lvjun Chen Jialu Tang Zhejiang Provincial Key Laboratory of Water Science and Technology Department of Environment Yangtze Delta Region Institute of Tsinghua University School of Environment Tsinghua University

Ni/Fe-Fe3O4 nanocomposites were synthesized for dechlorination of 2,4-dichlorophenol （2,4-DCP）. The effects of the Ni content in Ni/Fe-Fe3O4 nanocomposites, solution pH, and common dissolved ions on the dechlorination efficiency were investigated, in addition to the reusability of the nanocomposites. The results showed that increasing content of Ni in Ni/Fe-FesO4 nanocomposites, from 1 to 5 wt.%, greatly increased the dechlorination efficiency; the Ni/Fe-Fe3O4 nanocomposites had much higher dechlorination efficiency than bare Ni/Fe nanoparticles. Ni content of S wt.% and initial pH below 6.0 was found to be the optimal conditions for the catalytic dechlorination of 2,4-DCP. Both 2,4-DCP and the intermediate product 2-chlorophenol （2-CP） were completely removed, and the concentra- tion of the final product phenol was close to the theoretical phenol production from complete dechlorination of 20 mg/L of 2,4-DCP, after 3 hr reaction at initial pH value of 6.0, 3 g/L Ni/Fe-Fe3O4, S wt.% Ni content in the composite, and temperature of 22℃ 2,4-DCP dechlorination was enhanced by C1- and inhibited by NO3- and SO42-. The nanocomposites were easily separated from the solution by an applied magnetic field. When the catalyst was reused, the removal efficiency of 2,4-DCP was almost 100% for the first seven uses, and gradually decreased to 75% in cycles 8-10. Therefore, the Ni/Fe-Fe3O4 nanocomposites can be considered as a potentially effective tool for remediation of Pollution bv 2.4-DCP.

关键词： Ni/Fe-Fe3O4 nanocomposites2 4-DichlorophenolCatalytic dechlorinationRecoverableCommon dissolved ions

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