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Improvement of impact resistance of plain-woven composite by embedding superelastic shape memory alloy wires

Xiaojun GU, Xiuzhong SU, Jun WANG, Yingjie XU, Jihong ZHU, Weihong ZHANG

《机械工程前沿（英文）》 2020年 第15卷 第4期   页码 547-557 doi: 10.1007/s11465-020-0595-1

摘要： Carbon fiber reinforced polymer (CFRP) composites have excellent mechanical properties, specifically, high specific stiffness and strength. However, most CFRP composites exhibit poor impact resistance. To overcome this limitation, this study presents a new plain-woven CFRP composite embedded with superelastic shape memory alloy (SMA) wires. Composite specimens are fabricated using the vacuum-assisted resin injection method. Drop-weight impact tests are conducted on composite specimens with and without SMA wires to evaluate the improvement of impact resistance. The material models of the CFRP composite and superelastic SMA wire are introduced and implemented into a finite element (FE) software by the explicit user-defined material subroutine. FE simulations of the drop-weight impact tests are performed to reveal the superelastic deformation and debonding failure of the SMA inserts. Improvement of the energy absorption capacity and toughness of the SMA-CFRP composite is confirmed by the comparison results.

关键词： carbon fiber reinforced polymer composite     shape memory alloy wire     impact resistance     drop-weight test     finite element simulation    

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Design of a shaking table test box for a subway station structure in soft soil

YANG Linde, ZHENG Yonglai, ZHANG Dongliang, JI Qianqian, YANG Chao

《结构与土木工程前沿（英文）》 2007年 第1卷 第2期   页码 194-197 doi: 10.1007/s11709-007-0022-2

摘要： A reasonable choice of structure of a model box is significant for a shaking table test to be successful in geotechnical engineering. A model box has been designed for the shaking table test of a subway station structure in the soft soil of Shanghai in the paper. The reasonable geometric similarity scale of the subway station structure has been determined by a 3-D dynamic analysis under the action of lateral equivalent static loading. The shape, size and structure of the model box are chosen by considering all the involved factors comprehensively. The shape of the box is similar to that of a typical station structure, and the ratio between the plane dimension of the model ground and that of the model structure is big enough to reduce the influence of boundary condition effectively. The structure is strong enough to avoid being demolished by shaking during a test. The contact conditions between the model soil and box are clear to help the data gained from the test well fit that from numerical analysis. The total weight of the model soil and box is less than the bearing capacity of the shaking table apparatus and there is no resonance between the model soil and box. The results show that the model box can be used to simulate the dynamic response of a subway station structure very well, so it provides a firm foundation for the success of the shaking table test of a subway station structure.

关键词： geotechnical engineering     numerical analysis     weight     dynamic analysis     Shanghai    

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CFD evaluation of pressure drop across a 3-D filter housing for industrial gas turbine plants

Fidelis I. ABAM,Samuel O. EFFIOM,Olayinka S. OHUNAKIN

《能源前沿（英文）》 2016年 第10卷 第2期   页码 192-202 doi: 10.1007/s11708-016-0406-x

摘要： This paper investigated the flow distribution and total pressure drop across a designed 3-D filter housing integrated with a 3-stage filtration system using computational fluid dynamics (CFD). The filter housing model was proposed for a heavy-duty industrial gas turbine plant operating at an average ambient temperature of 20°C.The pressure drops across the classes of filters were 652.8 Pa, 2692.2 Pa, 887.8 Pa, 776.2 Pa and 2304.2 Pa for I-GB, GB-GA, GA-FA, FA-HA, and HA-O, respectively. The results obtained indicated an acceptable total pressure drop of 7.2% for the entire filter housing before filter clean-up. Although the CFD simulation result shows that small outlet flow velocity and transonic flows exist at the outlet of the filter housing, the designed filter housing was proved compatible with the studied GT, for inlet flow conditions between 600≤ ≤610 kg/s and 60≤ ≤70 m/s for the air flow rate and velocity, respectively. Furthermore, the designed filter housing could be adopted for the studied GT and locations of Usan and Maiduguri in Nigeria, and other locations with similar environmental conditions.

关键词： computational fluid dynamics (CFD)     pressure drop     flow distribution     filter housing     gas turbine    

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A biofilter model for simultaneous simulation of toluene removal and bed pressure drop under varied inlet

Jinying XI,Insun KANG,Hongying HU,Xian ZHANG

《环境科学与工程前沿（英文）》 2015年 第9卷 第3期   页码 554-562 doi: 10.1007/s11783-014-0671-z

摘要： In this study, a biofiltration model including the effect of biomass accumulation and inert biomass growth is developed to simultaneously predict the Volatile Organic Compounds (VOCs) removal and filter bed pressure drop under varied inlet loadings. A laboratory-scale experimental biofilter for gaseous toluene removal was set up and operated for 100 days with inlet toluene concentration ranging from 250 to 2500 mg?m . According to sensitivity analysis based on the model, the VOCs removal efficiency of the biofilter is more sensitive to Henry’s constant, the specific surface area of the filter bed and the thickness of water layer, while the filter bed pressure drop is more sensitive to biomass yield coefficient and original void fraction. The calculated toluene removal efficiency and bed pressure drop satisfactorily fit the experimental data under varied inlet toluene loadings, which indicates the model in this study can be used to predict VOCs removal and bed pressure drop simultaneously. Based on the model, the effect of mass-transfer parameters on VOCs removal and the stable-run time of a biofilter are analyzed. The results demonstrate that the model can function as a good tool to evaluate the effect of biomass accumulation and optimize the design and operation of biofilters.

关键词： Volatile Organic Compounds (VOCs)     biofilters     modelling     biomass accumulation     pressure drop    

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Ultrasound-assisted emulsification solidified floating organic drop microextraction for the determination

Qingyun CHANG, Jingwen ZHANG, Xin DU, Jingjun MA, Jingci LI,

《环境科学与工程前沿（英文）》 2010年 第4卷 第2期   页码 187-195 doi: 10.1007/s11783-010-0030-7

摘要： A simple and efficient liquid-phase microextraction (LPME) technique was developed using ultrasound-assisted emulsification solidified floating organic drop microextraction (USAE-SFODME) combined with flame atomic absorption spectrometry, for the extraction and determination of trace copper in water samples. 1-(2-Pyridylazo)-2-naphthol (PAN) was used as chelating agent. Microextraction efficiency factors (including extraction solvent type, extraction volume, time, temperature, and pH), the amount of the chelating agent, and salt effect were investigated and optimized. Under the optimum extraction conditions, figures of merit of the proposed method were evaluated. The calibration graph was linear in the range of 20–600 g·L with a detection limit of 0.76 g·L. The relative standard deviation (R.S.D) for ten replicate measurements of 20 and 400 g·L of copper was 3.83% and 2.65%, respectively. Finally, the proposed method was applied to tap water, river water, and sea water, and accuracy was assessed through the analysis of certified reference water or recovery experiments.

关键词： ultrasound-assisted emulsification     solidified floating organic drop microextraction     flame atomic absorption spectrometry     preconcentration     copper    

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Solving topology optimization problems by the Guide-Weight method

Xinjun LIU, Zhidong LI, Liping WANG, Jinsong WANG

《机械工程前沿（英文）》 2011年 第6卷 第1期   页码 136-150 doi: 10.1007/s11465-010-0126-6

摘要：

Finding a good solution method for topology optimization problems is always paid attention to by the research field because they are subject to the large number of the design variables and to the complexity that occurs because the objective and constraint functions are usually implicit with respect to design variables. Guide-Weight method, proposed first by Chen in 1980s, was effectively and successfully used in antenna structures’ optimization. This paper makes some improvement to it so that it possesses the characteristics of both the optimality criteria methods and the mathematical programming methods. When the Guide-Weight method is applied into topology optimization, it works very well with unified and simple form, wide availability and fast convergence. The algorithm of the Guide-Weight method and the improvement on it are described; two formulations of topology optimization solved by the Guide-Weight method combining with SIMP method are presented; subsequently, three numerical examples are provided, and comparison of the Guide-Weight method with other methods is made.

关键词： Guide-Weight method     topology optimization     SIMP method    

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Hybrid intelligent water drop bundled wavelet neural network to solve the islanding detection by inverter-based

Mehrdad TARAFDAR HAGH,Homayoun EBRAHIMIAN,Noradin GHADIMI

《能源前沿（英文）》 2015年 第9卷 第1期   页码 75-90 doi: 10.1007/s11708-014-0337-3

摘要： In this paper, a passive neuro-wavelet based islanding detection technique for grid-connected inverter-based distributed generation was developed. The weight parameters of the neural network were optimized by intelligent water drop (IWD) to improve the capability of the proposed technique in the proposed problem. The proposed method utilizes and combines wavelet analysis and artificial neural network (ANN) to detect islanding. Connecting distributed generator to the distribution network has many benefits such as increasing the capacity of the grid and enhancing the power quality. However, it gives rise to many problems. This is mainly due to the fact that distribution networks are designed without any generation units at that level. Hence, integrating distributed generators into the existing distribution network is not problem-free. Unintentional islanding is one of the encountered problems. Discrete wavelet transform (DWT) is capable of decomposing the signals into different frequency bands. It can be utilized in extracting discriminative features from the acquired voltage signals. In passive schemes with a large non-detection zone (NDZ), concern has been raised on active method due to its degrading power quality effect. The main emphasis of the proposed scheme is to reduce the NDZ to as close as possible and to keep the output power quality unchanged. The simulation results from Matlab/Simulink shows that the proposed method has a small non-detection zone, and is capable of detecting islanding accurately within the minimum standard time.

关键词： islanding detection     neuro-wavelet     intelligent water drop (IWD)     non-detection zone (NDZ)     distributed generation (DG)    

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The investigation of pressure drop in moving-beds

CHEN Yunhua, ZHU Xuedong, WU Yongqiang, ZHU Zibin

《化学科学与工程前沿（英文）》 2007年 第1卷 第2期   页码 184-189 doi: 10.1007/s11705-007-0034-4

摘要： The pressure drop of a cross-flow moving-bed was investigated in a two-dimensional rectangular apparatus. The effects of the particle velocity, the superficial gas velocity, the formation and development of cavity/raceway and voidage of particles on the pressure drop were investigated experimentally under the operational conditions of 0.09 1.35 m/s of the superficial gas velocity and 0.95 9.68 cm/min of the particle velocity. The experimental results show that the particle velocity has little influence on the pressure drop, while the phenomena of cavity and pinning occur when the cross-flow velocity is high enough. The development of a cavity or a raceway can result in three types of variations of pressure drop with time: stabilization, slight fluctuation and severe fluctuation. A cavity appears in a process cycle of formation-growing up-collapsing-fluidization at a high gas velocity. On the basis of experimental results, a model for calculating the pressure drop after a cavity occurs and a dimensionless relationship of cavity size is developed, which gives a good qualitative account of the experimental data.

关键词： development     cross-flow velocity     superficial     qualitative account     stabilization    

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Instantaneous deflection of light-weight concrete slabs

Behnam VAKHSHOURI, Shami NEJADI

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 412-423 doi: 10.1007/s11709-017-0416-8

摘要： Construction loading before the age of 28 d can have the most significant effects on the slabs, especially for multi-story structures. The changing properties of the young concrete complicate the prediction of serviceability design requirements also. An experimental investigation is performed on four simply supported Light-Weight Concrete (LWC) one-way slabs subjected to immediate loading at 14 d. Effects of aggregate type, loading levels and cracking moment together with the influences of ultimate moment capacity and service moment on the instantaneous deflection of slabs are studied. Comparison of the obtained results with predictions of existing models in the literature shows considerable differences between the recorded and estimated instantaneous deflection of LWC slabs. Based on sensitivity analysis of the effective parameters, a new equation is proposed and verified to predict the instantaneous deflection of LWC slabs subjected to loading at the age of 14 d.

关键词： instantaneous deflection     light-weight concrete     expanded polystyrene     effective moment of inertia     cracking moment     moment capacity     service moment    

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产品跌落冲击耐撞性能稳健设计研究进展

杨书仪,刘德顺,赵继云,文泽军

《中国工程科学》 2010年 第12卷 第1期   页码 61-66

摘要：

跌落冲击是物体在短时间内受到强大冲击力而运动状态发生急剧变化的现象，是导致产品特别是小型机电产品外表破损、功能失效的主要原因。近年来，国内外研究学者针对如何提高产品抗跌落冲击的本质耐撞性能进行了大量研究。笔者从研究对象、研究方法等角度，系统总结了产品跌落冲击耐撞性和产品耐撞性能稳健设计的研究现状，归纳了有待进一步研究的问题。

关键词： 跌落冲击     耐撞性     稳健设计    

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Characterization of soil low-molecular-weight organic acids in the Karst rocky desertification region

Xiaoliang LI, Xiaomin CHEN, Xia LIU, Lianchuan ZHOU, Xinqiang YANG

《环境科学与工程前沿（英文）》 2012年 第6卷 第2期   页码 195-203 doi: 10.1007/s11783-012-0391-1

摘要： Soil low-molecular-weight (LMW) organic acids play important roles in the soil-forming process and the cycling of nutrients in Karst regions. In this study, we quantified the contents of LMW organic acids (including lactate, acetate, formate, malate, and oxalate) in soil solution over the Karst region of Guizhou Province, China using ion chromatography. The concentration of total LMW organic acids in topsoil solution ranged from 0.358 to 1.823 μmol·g , with an average of 0.912 μmol·g . The mean concentrations of lactate, acetate, formate, malate, and oxalate were 0.212±0.089, 0.302±0.228, 0.301±0.214, 0.014±0.018 and 0.086±0.118 μmol·g , respectively. There were also significant difference in the contents of these acids among four phases of rocky desertification, and their concentrations decreased with the aggravation of rocky desertification. The concentrations of the LMW organic acids were significantly positive correlated each other. Significant positive correlations were also observed among individual LMW organic acids in soil solution, and between them and soil available P, available K, exchangeable Ca, respectively. Furthermore, the concentrations of LMW organic acids were significantly positively correlated with inorganic anions (chlorides, nitrates, and sulfates) in Karst topsoil solution. Therefore, the concentrations of soil LMW organic acids might be one of driving force in the Karst rock desertification process in Guizhou Province.

关键词： Karst rocky desertification     low-molecular-weight (LMW) organic acids     distribution characteristics     soil    

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Prediction of falling weight deflectometer parameters using hybrid model of genetic algorithm and adaptive

《结构与土木工程前沿（英文）》   页码 812-826 doi: 10.1007/s11709-023-0940-7

摘要： A falling weight deflectometer is a testing device used in civil engineering to measure and evaluate the physical properties of pavements, such as the modulus of the subgrade reaction (Y1) and the elastic modulus of the slab (Y2), which are crucial for assessing the structural strength of pavements. In this study, we developed a novel hybrid artificial intelligence model, i.e., a genetic algorithm (GA)-optimized adaptive neuro-fuzzy inference system (ANFIS-GA), to predict Y1 and Y2 based on easily determined 13 parameters of rigid pavements. The performance of the novel ANFIS-GA model was compared to that of other benchmark models, namely logistic regression (LR) and radial basis function regression (RBFR) algorithms. These models were validated using standard statistical measures, namely, the coefficient of correlation (R), mean absolute error (MAE), and root mean square error (RMSE). The results indicated that the ANFIS-GA model was the best at predicting Y1 (R = 0.945) and Y2 (R = 0.887) compared to the LR and RBFR models. Therefore, the ANFIS-GA model can be used to accurately predict Y1 and Y2 based on easily measured parameters for the appropriate and rapid assessment of the quality and strength of pavements.

关键词： falling weight deflectometer     modulus of subgrade reaction     elastic modulus     metaheuristic algorithms    

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Pressure drop analysis on the positive half-cell of a cerium redox flow battery using computational fluid

Fernando F. Rivera, Berenice Miranda-Alcántara, Germán Orozco, Carlos Ponce de León, Luis F. Arenas

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 399-409 doi: 10.1007/s11705-020-1934-9

摘要： Description of electrolyte fluid dynamics in the electrode compartments by mathematical models can be a powerful tool in the development of redox flow batteries (RFBs) and other electrochemical reactors. In order to determine their predictive capability, turbulent Reynolds-averaged Navier-Stokes (RANS) and free flow plus porous media (Brinkman) models were applied to compute local fluid velocities taking place in a rectangular channel electrochemical flow cell used as the positive half-cell of a cerium-based RFB for laboratory studies. Two different platinized titanium electrodes were considered, a plate plus a turbulence promoter and an expanded metal mesh. Calculated pressure drop was validated against experimental data obtained with typical cerium electrolytes. It was found that the pressure drop values were better described by the RANS approach, whereas the validity of Brinkman equations was strongly dependent on porosity and permeability values of the porous media.

关键词： CFD simulation     porous media     porous electrode     pressure drop     redox flow battery    

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Evaluation of ICUs and weight of quality control indicators: an exploratory study based on Chinese ICU

《医学前沿（英文）》 2023年 第17卷 第4期   页码 675-684 doi: 10.1007/s11684-022-0970-x

摘要： This study aimed to explore key quality control factors that affected the prognosis of intensive care unit (ICU) patients in Chinese mainland over six years (2015−2020). The data for this study were from 31 provincial and municipal hospitals (3425 hospital ICUs) and included 2 110 685 ICU patients, for a total of 27 607 376 ICU hospitalization days. We found that 15 initially established quality control indicators were good predictors of patient prognosis, including percentage of ICU patients out of all inpatients (%), percentage of ICU bed occupancy of total inpatient bed occupancy (%), percentage of all ICU inpatients with an APACHE II score ≥15 (%), three-hour (surviving sepsis campaign) SSC bundle compliance (%), six-hour SSC bundle compliance (%), rate of microbe detection before antibiotics (%), percentage of drug deep venous thrombosis (DVT) prophylaxis (%), percentage of unplanned endotracheal extubations (%), percentage of patients reintubated within 48 hours (%), unplanned transfers to the ICU (%), 48-h ICU readmission rate (%), ventilator associated pneumonia (VAP) (per 1000 ventilator days), catheter related blood stream infection (CRBSI) (per 1000 catheter days), catheter-associated urinary tract infections (CAUTI) (per 1000 catheter days), in-hospital mortality (%). When exploratory factor analysis was applied, the 15 indicators were divided into 6 core elements that varied in weight regarding quality evaluation: nosocomial infection management (21.35%), compliance with the Surviving Sepsis Campaign guidelines (17.97%), ICU resources (17.46%), airway management (15.53%), prevention of deep-vein thrombosis (14.07%), and severity of patient condition (13.61%). Based on the different weights of the core elements associated with the 15 indicators, we developed an integrated quality scoring system defined as F score=21.35%×nosocomial infection management + 17.97%×compliance with SSC guidelines + 17.46%×ICU resources + 15.53%×airway management + 14.07%×DVT prevention + 13.61%×severity of patient condition. This evidence-based quality scoring system will help in assessing the key elements of quality management and establish a foundation for further optimization of the quality control indicator system.

关键词： critical care medicine     quality control     evaluation     exploratory factor analysis (EFA) model    

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Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content on

《化学科学与工程前沿（英文）》 2023年 第17卷 第10期   页码 1484-1502 doi: 10.1007/s11705-023-2331-y

摘要： Various hydrophilic poly(ethylene-co-vinyl alcohol) (EVOH) were used herein to precisely control the structure and hydrodynamic properties of polysulfone (PSF) membranes. Particularly, to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol (VOH: 73%, 68%, 56%), the non-solvent-induced phase separation (NIPS) technique was used. Polyethylene glycol was used as a compatibilizer and as a porogen in N,N-dimethylacetamide. Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism. The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism. Accordingly, the addition of EVOH led to an increase in the rheology of the dopes. The resulting membranes exhibited a microporous structure, while the finger-like structures became more evident with increasing VOH content. The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics. Interestingly, the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m–2·h–1·bar–1, which was higher than that of pure PSF membranes (171 L·m–2·h–1·bar–1). In addition, PSF/EVOH32 rejected bovine serum albumin at a high rate (> 90%) and achieved a significant restoration of permeability. Finally, from the thermodynamic and hydrodynamic results, valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.

关键词： polysulfone     blend modification     ultrafiltration membrane     formation hydrodynamics     poly(ethylene-co-vinyl alcohol) copolymer    

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标题 作者 时间 类型 操作

Improvement of impact resistance of plain-woven composite by embedding superelastic shape memory alloy wires

Xiaojun GU, Xiuzhong SU, Jun WANG, Yingjie XU, Jihong ZHU, Weihong ZHANG

期刊论文

Design of a shaking table test box for a subway station structure in soft soil

YANG Linde, ZHENG Yonglai, ZHANG Dongliang, JI Qianqian, YANG Chao

期刊论文

CFD evaluation of pressure drop across a 3-D filter housing for industrial gas turbine plants

Fidelis I. ABAM,Samuel O. EFFIOM,Olayinka S. OHUNAKIN

期刊论文

A biofilter model for simultaneous simulation of toluene removal and bed pressure drop under varied inlet

Jinying XI,Insun KANG,Hongying HU,Xian ZHANG

期刊论文

Ultrasound-assisted emulsification solidified floating organic drop microextraction for the determination

Qingyun CHANG, Jingwen ZHANG, Xin DU, Jingjun MA, Jingci LI,

期刊论文

Solving topology optimization problems by the Guide-Weight method

Xinjun LIU, Zhidong LI, Liping WANG, Jinsong WANG

期刊论文

Hybrid intelligent water drop bundled wavelet neural network to solve the islanding detection by inverter-based

Mehrdad TARAFDAR HAGH,Homayoun EBRAHIMIAN,Noradin GHADIMI

期刊论文

The investigation of pressure drop in moving-beds

CHEN Yunhua, ZHU Xuedong, WU Yongqiang, ZHU Zibin

期刊论文

Instantaneous deflection of light-weight concrete slabs

Behnam VAKHSHOURI, Shami NEJADI

期刊论文

产品跌落冲击耐撞性能稳健设计研究进展

杨书仪,刘德顺,赵继云,文泽军

期刊论文

Characterization of soil low-molecular-weight organic acids in the Karst rocky desertification region

Xiaoliang LI, Xiaomin CHEN, Xia LIU, Lianchuan ZHOU, Xinqiang YANG

期刊论文

Prediction of falling weight deflectometer parameters using hybrid model of genetic algorithm and adaptive

期刊论文

Pressure drop analysis on the positive half-cell of a cerium redox flow battery using computational fluid

Fernando F. Rivera, Berenice Miranda-Alcántara, Germán Orozco, Carlos Ponce de León, Luis F. Arenas

期刊论文

Evaluation of ICUs and weight of quality control indicators: an exploratory study based on Chinese ICU

期刊论文

Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content on

期刊论文