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Study of Nonlinear Earthquake Flow Functions and Their Application to the Space Increased Probability of Strong Earthquake (SIP)
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作者 Wang Xiaoqing and Huang DeyuCenter for Analysis and Prediction, CSB, Beijing 100036, China 《Earthquake Research in China》 1998年第3期37-47,共11页
The definition and abnormality discriminatory criteria of earthquake flow function are introduced in this paper based on the algorithm of Space Increased Probability (SIP). Nine earthquake flow functions were defined ... The definition and abnormality discriminatory criteria of earthquake flow function are introduced in this paper based on the algorithm of Space Increased Probability (SIP). Nine earthquake flow functions were defined by the method. The retrospect test that applied the SIP algorithm with the nonlinear earthquake flow function to 7 earthquakes, which occurred from 1975 to 1989 in Eastern China, with a magnitude of 6 or greater depicted that 6 of the 7 strong earthquakes (86%) were located in the SIP areas, and the SIP covers about 32% of the total research time-space domain. These suggest that the R-value, an effective scale for earthquake forecast, is 54% and may imply that the nonlinear earthquake flow function introduced in this paper can be applied to the intermediate-term earthquake forecast research. 展开更多
关键词 NONLINEAR EARTHQUAKE flow function SPACE INCREASED PROBABILITY of strong earthquake.
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RELATIONS OF ENDOTHELIAL FUNCTION AND BLOOD FLOW IN BRACHIAL ARTERY AND CORONARY ARTERY 被引量:1
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作者 孙寅光 沈卫峰 +1 位作者 施仲伟 张大东 《Journal of Shanghai Second Medical University(Foreign Language Edition)》 2003年第1期41-45,57,共6页
Objective:To determine the relations between endothelium-dependent vasodilator function and blood flow in the brachial and coronary arteries in patients with suspected coronary artery disease.Methods:Twenty-eight pati... Objective:To determine the relations between endothelium-dependent vasodilator function and blood flow in the brachial and coronary arteries in patients with suspected coronary artery disease.Methods:Twenty-eight patients with suspected coronary artery disease underwent brachial artery endothelial function test by using high-resolution B-mode ultrasound before coronary angiography(CAG)and coronary flow reserve(CFR)test by using intracoronary Doppler technique.The correlation of coronary artery dilatation induced by an increase in blood flow after intracoronary adenosine infusion and brachial artery flow-mediated dilatation(FMD) following reactive hyperemia was evaluated.The relation between the change of brachial artery blood flow and CFR was also studied.Results:There was a positive correlation between brachial FMD and percent change of coronary diameter after adenosine infusion(12.50%±9.35% vs 11.38%±7.55%,r=0.425,P=0.02).There was also a weak negative relation between brachial flow change following reactive hy-peremia and CFR(r=-0.397,P=0.04).Conclusion:There is a correlation between the coronary endo-thelial function and the CFR by ultrasonic determination of brachial flow changes following reactive hyperemia. 展开更多
关键词 ultrasound reactive hyperemia brachial artery endothelial function coronary flow reserve
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Do Continuous Flow LVADS Improve Diastolic Dysfunction? 被引量:1
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作者 Nandini Nair Sudhir Thotakura Enrique Gongora 《Open Journal of Organ Transplant Surgery》 2014年第3期23-28,共6页
Background: Ventricular assist devices are now used as a bridge to recovery/decision/transplant or as destination therapy in end-stage heart failure. Continued improvements in technology and pump design have made impl... Background: Ventricular assist devices are now used as a bridge to recovery/decision/transplant or as destination therapy in end-stage heart failure. Continued improvements in technology and pump design have made implantation an easier process with reduced operative risks and pump-related adverse events. Considering the beneficial effects of these devices in the clinical setting, it seemed logical to address the long-term effect of the continuous flow pumps on diastolic dysfunction. Methods: This study addresses the effect of HeartMate IITM(HMII) support for 284+/-97 days on echocardiographic parameters of diastolic function. Data from fifteen patients was retrospectively studied status post left ventricular assist device (LVAD) implantation. The data at approximately 1-year post implantation was compared with that obtained prior to implantation. Statistical analyses were performed using the Microsoft Excel Program/MSExcel Stats. Echocardiographic measurements were carried out in accordance with the American Society of Echocardiography guidelines. Results: Of all the echocardiographic parameters assessed only E/Ea and calculated left atrial pressure (LAP) showed a statistically significant decrease. Two parameters that showed a trend towards significance are Ea (septal) and global functional index (p = 0.05). Conclusions: Continuous Flow LVAD support appears to improve diastolic dysfunction. This study has limitations in that we used a single type of continuous flow device (HeartMate IITM) and was conducted as a retrospective analysis. Further studies with larger populations and longer support are required to validate this finding. 展开更多
关键词 CONTINUOUS flow Device DIASTOLIC function HeartMate IITM LEFT VENTRICULAR Assist Devise
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The investigation and optimization of drag reduction in turbulent flow of Newtonian fluid passing through horizontal pipelines using functionalized magnetic nanophotocatalysts and lecithin 被引量:4
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作者 Nadia Esfandiari Reza Zareinezhad Zahra Habibi 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第1期63-75,共13页
The nanophotocatalysts were synthesized in four stages and evaluated by FTIR, FESEM and VSM analysis. The influence of nanofluids containing functionalized magnetic Ti O2 nanophotocatalyst and dipalmitoylphosphatidylc... The nanophotocatalysts were synthesized in four stages and evaluated by FTIR, FESEM and VSM analysis. The influence of nanofluids containing functionalized magnetic Ti O2 nanophotocatalyst and dipalmitoylphosphatidylcholine lecithin in drag reduction of turbulent flow in four horizontal pipelines was studied. The effective parameters on drag reduction(nanoparticle concentration, surfactant concentration, p H and Re number) were investigated and optimized in each pipeline using response surface method. The drag reduction in 1/2 " galvanized, 3/4" galvanized, 1/2 "five-layer and 1/2" cuprous pipelines was found 99.1%, 92.5%, 87.6% and 85.2%, respectively. The model adequacy was measured using ANOVA. Based on the high determination coefficient, more than 95% of variance of experimental data in all pipelines was described by quadratic model. 展开更多
关键词 Drag reduction LECITHIN functionALIZED MAGNETIC nanophotocatalyst TURBULENT flow Response surface
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A GENERAL FUNCTIONAL EQUATION GOVERNING THE MOTION OF A FLUID FLOW
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作者 张杰 方国洪 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 1995年第2期119-123,共5页
A time-correlated random field bescribing the general flow is defined. A time-correlated functionalequation governing the evolution of its characteristic functional is derived.
关键词 flow RANDOM field CHARACTERISTIC functionAL
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Flow cytometry for the assessment of animal sperm ntegrity and functionality: state of the art 被引量:1
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作者 Md. Sharoare Hossain Anders Johannisson +3 位作者 Margareta Wallgren Szabolcs Nagy Amanda Pimenta Siqueira Heriberto Rodriguez-Martinez 《Asian Journal of Andrology》 SCIE CAS CSCD 2011年第3期406-419,511,共15页
Flow cytometry is now a recognized methodology within animal spermatology, and has moved from being a research tool to become routine in the assessment of animal semen destined to breeding. The availability of 'bench... Flow cytometry is now a recognized methodology within animal spermatology, and has moved from being a research tool to become routine in the assessment of animal semen destined to breeding. The availability of 'bench-top' flow cytometers and of newer and versatile markers for cell structure and function had allowed the instrumentation to measure more sperm parameters, from viability to reactiveness when exposed to exogenous stimuli, and to increase our capabilities to sort spermatozoa for potential fertilizing capacity, or chromosomal sex. The present review summarizes the state of the art regarding flow cytometry applied to animal andrology, albeit keeping an open comparative intent. It critically evaluates the present and future capabilities of flow cytometry for the diagnostics of potential fertility and for the development of current reproductive technologies such as sperm freezing, sperm selection and sperm sorting. The flow cytometry methods will probably further revolutionize our understanding of the sperm physiology and their functionality, and will undoubtedly extend its application in isolating many uncharacterized features of spermatozoa. However, continuous follow-up of the methods is a necessity owing to technical developments and the complexity of mapping spermatozoa. 展开更多
关键词 ANIMALS FERTILITY flow cytometry semen analysis SPERMATOZOA sperm functionality sperm intactness
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Perfect Combination of Architectural Functions and Flow Lines: Study on Roof Garden of Frank Gehry's Walt Disney Concert Hall
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作者 WANG Haiou 《Journal of Landscape Research》 2016年第2期21-22,26,共3页
By exploring the space and the design techniques of roof garden in Frank Gehry's Walt Disney Concert Hall, this paper made further research on the combination of architectural functions and pedestrian fl ow lines,... By exploring the space and the design techniques of roof garden in Frank Gehry's Walt Disney Concert Hall, this paper made further research on the combination of architectural functions and pedestrian fl ow lines, and attempted to summarize the unique design techniques of Frank Gehry by analyzing his works, improve and develop design theories of roof garden, and attract more attention from the public to roof garden design. 展开更多
关键词 Walt Disney Concert Hall Roof garden Space form function flow lines
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Functional connectivity and information flow in cerebral motor regions of healthy people following finger movement training
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作者 Zeqiang Yang Dongmei Hao Ying Li Yanping Bai 《Neural Regeneration Research》 SCIE CAS CSCD 2010年第9期710-714,共5页
BACKGROUND:Neuro-rehabilitative training has been shown to promote motor function recovery in stroke patients,although the underlying mechanisms have not been fully clarified.OBJECTIVE:To investigate the effects of ... BACKGROUND:Neuro-rehabilitative training has been shown to promote motor function recovery in stroke patients,although the underlying mechanisms have not been fully clarified.OBJECTIVE:To investigate the effects of finger movement training on functional connectivity and information flow direction in cerebral motor areas of healthy people using electroencephalogram (EEG).DESIGN,TIME AND SETTING:A self-controlled,observational study was performed at the College of Life Science and Bioengineering,Beijing University of Technology between December 2008 and April 2009.PARTICIPANTS:Nineteen healthy adults,who seldom played musical instruments or keyboards,were included in the present study.METHODS:Specific finger movement training was performed,and all subjects were asked to separately press keys with their left or right hand fingers,according to instructions.The task comprised five sessions of test train test train-test.Thirty-six channel EEG signals were recorded in different test sessions prior to and after training.Data were statistically analyzed using one-way analysis of variance.MAIN OUTCOME MEASURES:The number of effective performances,correct ratio,average response time,average movement time,correlation coefficient between pairs of EEG channels,and information flow direction in motor regions were analyzed and compared between different training sessions.RESULTS:Motor function of all subjects was significantly improved in the third test comparedwith the first test (P〈 0.01).More than 80% of connections were strengthened in the motor-related areas following two training sessions,in particular the primary motor regions under the C4 electrode.Compared to the first test,a greater amount of information flowed from the Cz and Fcz electrodes (corresponding to supplementary motor area) to the C4 electrode in the third test.CONCLUSION:Finger task training increased motor ability in subjects by strengthening connections and changing information flow in the motor areas.These results provided a greater understanding of the mechanisms involved in motor rehabilitation. 展开更多
关键词 motor cortex functional connectivity information flow direction ELECTROENCEPHALOGRAM
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Developing theory of probability density function for stochastic modeling of turbulent gas-particle flows
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作者 Lixing ZHOU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第7期1019-1030,共12页
Turbulent gas-particle flows are studied by a kinetic description using a prob- ability density function (PDF). Unlike other investigators deriving the particle Reynolds stress equations using the PDF equations, the... Turbulent gas-particle flows are studied by a kinetic description using a prob- ability density function (PDF). Unlike other investigators deriving the particle Reynolds stress equations using the PDF equations, the particle PDF transport equations are di- rectly solved either using a finite-difference method for two-dimensional (2D) problems or using a Monte-Carlo (MC) method for three-dimensional (3D) problems. The proposed differential stress model together with the PDF (DSM-PDF) is used to simulate turbulent swirling gas-particle flows. The simulation results are compared with the experimental results and the second-order moment (SOM) two-phase modeling results. All of these simulation results are in agreement with the experimental results, implying that the PDF approach validates the SOM two-phase turbulence modeling. The PDF model with the SOM-MC method is used to simulate evaporating gas-droplet flows, and the simulation results are in good agreement with the experimental results. 展开更多
关键词 probability density function(PDF)modeling turbulent flow gas-particleflow
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Functionality Semantics of Predicate Data Flow Diagram
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作者 高晓雷 缪淮扣 刘玲 《Journal of Shanghai University(English Edition)》 CAS 2004年第3期309-316,共8页
SOZL (structured methodology + object-oriented methodology + Z language) is a language that attempts to integrate structured method, object-oriented method and formal method. The core of this language is predicate dat... SOZL (structured methodology + object-oriented methodology + Z language) is a language that attempts to integrate structured method, object-oriented method and formal method. The core of this language is predicate data flow diagram (PDFD). In order to eliminate the ambiguity of predicate data flow diagrams and their associated textual specifications, a formalization of the syntax and semantics of predicate data flow diagrams is necessary. In this paper we use Z notation to define an abstract syntax and the related structural constraints for the PDFD notation, and provide it with an axiomatic semantics based on the concept of data availability and functionality of predicate operation. Finally, an example is given to establish functionality consistent decomposition on hierarchical PDFD (HPDFD). 展开更多
关键词 predicate data flow diagram (PDFD) predicate operation (PO) hierarchical predicate data flow diagram (HPDFD) AVAILABILITY functionality semantics.
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Curative Effects of Warming Needle Moxibustion Combined with Manipulation Massage on Cervical Spondylotic Vertebral Arteriopathy and Its Influence on the Cerebral Blood Flow Parameters and Cervical Vertebral Function
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作者 Zhai Bingsheng 《World Journal of Integrated Traditional and Western Medicine》 2019年第3期17-23,共7页
OBJECTIVE: To explore the curative effects of warming needle moxibustion combined with manipulation massage on cervical spondylotic vertebral arteriopathy and its influence on the cerebral blood flow and cervical vert... OBJECTIVE: To explore the curative effects of warming needle moxibustion combined with manipulation massage on cervical spondylotic vertebral arteriopathy and its influence on the cerebral blood flow and cervical vertebra function. METHODS: A total of 84 patients with cervical spondylotic vertebral arteriopathy admitted to our hospital from February 2016 to June 2017 were selected, and all patients were divided into an observation group (n=42) and a control group (n=42) according to the random number table method. The patients in the control group were given conventional western treatment, and the patients in the observation group were treated with warming needle moxibustion combined with manipulation massage on the basis of the control group. After 4 weeks of treatment, the changes of main clinical symptoms (vertigo, headache, neck and shoulder pain, tinnitus), cervical function (clinical symptoms, clinical examination, daily life action) and cerebral blood flow parameters (average blood flow velocity of left vertebral artery, right vertebral artery and basilar artery) of the 2 groups were observed, and the clinical efficacy of the 2 groups were statistically analyzed. RESULTS: The scores of vertigo, headache, neck and shoulder pain and tinnitus in the 2 groups were all significantly lower than before treatment (P < 0.05), and the clinical symptom scores in the observation group were significantly lower after treatment (P < 0.05);After treatment, the scores of clinical symptoms, clinical examination and daily life action in the 2 groups were significantly higher than those before treatment (P < 0.05), and the increase of cervical vertebral function score in the observation group was better than that in the control group (P < 0.05);The mean blood flow velocity of the left vertebral artery, right vertebral artery and the basilar artery in the 2 groups after treatment were significantly higher than before treatment (P < 0.05), and the increase of the above cerebral blood flow parameters in the observation group were higher than the control group (P < 0.05). The total effective rate was 92.9% in the observation group and 76.2% in the control group after treatment, and the difference between the 2 groups was statistically significant (P < 0.05). CONCLUSION: Warming needle moxibustion combined with manipulation massage can quickly relieve the clinical symptoms of patients with cervical spondylotic vertebral arteriopathy, improve the cervical function and cerebral blood flow parameters, increase the vertebrobasilar artery blood flow, and promote the recovery of the disease. 展开更多
关键词 CERVICAL spondylotic VERTEBRAL ARTERIOPATHY WARMING needle MOXIBUSTION Manipulation MASSAGE Cerebral blood flow parameters CERVICAL spine function
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Dissipation function in turbulent plane Poiseuille and Couette flows subject to spanwise rotations
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作者 Zhenhua XIA Yipeng SHI +1 位作者 Qingdong CAI Jie GAI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2019年第2期185-192,共8页
The dissipation function in turbulent plane Poiseuille flows(PPFs) and plane Couette flows(PCFs) subject to spanwise rotations is analyzed. It is found that, in the PCFs without system rotations, the mean part is cons... The dissipation function in turbulent plane Poiseuille flows(PPFs) and plane Couette flows(PCFs) subject to spanwise rotations is analyzed. It is found that, in the PCFs without system rotations, the mean part is constant while the fluctuation part follows a logarithmic law, resulting in a similar logarithmic skin friction law as PPFs.However, if the flow system rotates in the spanwise direction, no obvious dependence on the rotation number can be evaluated. In the PPFs with rotations, the dissipation function shows an increase with the rotation number, while in the PCFs with rotations,when the rotation number increases, the dissipation function first decreases and then increases. 展开更多
关键词 dissipation function spanwise rotation plane Poiseuille flow(PPF) plane Couette flow(PCF)
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Numerical Simulation of Dam-Break Flows Using Radial Basis Functions: Application to Urban Flood Inundation
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作者 Abdoulhafar Halassi Bacar Said Charriffaini Rawhoudine 《American Journal of Computational Mathematics》 2024年第3期318-332,共15页
Dam-break flows pose significant threats to urban areas due to their potential for causing rapid and extensive flooding. Traditional numerical methods for simulating these events struggle with complex urban landscapes... Dam-break flows pose significant threats to urban areas due to their potential for causing rapid and extensive flooding. Traditional numerical methods for simulating these events struggle with complex urban landscapes. This paper presents an alternative approach using Radial Basis Functions to simulate dam-break flows and their impact on urban flood inundation. The proposed method adapts a new strategy based on Particle Swarm Optimization for variable shape parameter selection on meshfree formulation to enhance the numerical stability and convergence of the simulation. The method’s accuracy and efficiency are demonstrated through numerical experiments, including well-known partial and circular dam-break problems and an idealized city with a single building, highlighting its potential as a valuable tool for urban flood risk management. 展开更多
关键词 Dam-Break flows Numerical Simulation Shallow Water Equations Radial Basis functions Urban Flood Inundation
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Resistance Measured by Airflow Perturbation Compared with Standard Pulmonary Function Measures 被引量:1
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作者 Tania Haque Jafar Vossoughi +3 位作者 Arthur T. Johnson Wanda Bell-Farrell Thomas Fitzgerald Steven M. Scharf 《Open Journal of Respiratory Diseases》 2013年第2期63-67,共5页
Background: Routine lung function testing requires expensive equipment, or requires maximum expiratory effort. The airflow perturbation device (APD) is a light handheld device, allowing for serial measures of respirat... Background: Routine lung function testing requires expensive equipment, or requires maximum expiratory effort. The airflow perturbation device (APD) is a light handheld device, allowing for serial measures of respiratory resistance noninvasively and effortlessly. Methods: In a convenience sample of 398 patients undergoing pulmonary function testing, we compared routine spirometric indices (forced expired volume in 1 second (FEV1), peak expiratory flow (PEF)), and airways resistance (Raw-272 patients), to measures of respiratory resistance measured with the APD including inspiratory (IR), expiratory (ER) and averaged (AR) resistance. Results: Measures of lung function were significantly correlated (p 0.001). On regression analysis, between 7% - 17% of the variance (R2) for FEV1, PEF, and Raw was explained by APD measurements. Approximately 2/3 of the variance in FEV1 was explained by PEF measurements. Conclusions: APD measurements of lung function correlate with conventional measures. Future studies should be directed at exploring the use of the APD device in serial measures of lung function in patients with lung disease. 展开更多
关键词 AIRflow PERTURBATION Device PULMONARY function FORCED Expired Volume in 1 Second Peak Expiratory flow AIRWAY RESISTANCE
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Flow Chamber流动试验模型 被引量:3
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作者 刘肖珩 陈槐卿 +1 位作者 尹红梅 XIONG Wang 《生物数学学报》 CSCD 2002年第4期416-420,共5页
从Navier-Stokes方程出发,运用无量纲化及虚宗量Bessel函数法求解。导得Flow Chamber系统中流体流动的速度场、切应力场等分布规律.并且,本文公式简化为定常状态时,无论是和Cao等人的理论结果,还是和他们的实验结果比较。都是相当一致的.
关键词 流动试验模型 流室 非定常流动 流体动力学 虚宗量贝塞尔函数 血流
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铁铬液流电池中碳基电极多尺度改性研究现状与展望
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作者 崔瀚文 彭莹莹 +1 位作者 黄惠 高超 《工程科学学报》 北大核心 2026年第2期436-450,共15页
铁铬液流电池(Iron–chromium redox flow battery, ICRFB)凭借其高安全性、长循环寿命、强设计灵活性以及低维护成本等优势,成为大规模长时储能领域的研究热点.铁铬液流电池主要结构包括电解液、隔膜和电极,电极作为电池的核心组成部... 铁铬液流电池(Iron–chromium redox flow battery, ICRFB)凭借其高安全性、长循环寿命、强设计灵活性以及低维护成本等优势,成为大规模长时储能领域的研究热点.铁铬液流电池主要结构包括电解液、隔膜和电极,电极作为电池的核心组成部分和电化学反应的主要发生场所,其材料的结构与性能对整体电池效率具有决定性影响.相比于金属基和复合型电极,碳基电极具有成本低、大量的三维导电网络及优异的稳定性等特点,因而在ICRFB的电极应用中占据主导地位.然而,碳基电极的活性位点不足、比表面积有限和电解液浸润性不佳等问题限制了其电化学性能的发挥.本综述聚焦探讨碳基电极的多尺度表面改性策略:其一是在其表面引入含氧官能团(如羟基、羧基)调控表面化学环境;其二在电极表面负载催化剂,构建催化活性位点,提升电极的催化活性和活性物质的反应动力学.目前,关于改性机制(如官能团–活性位点构效关系、催化剂界面电荷转移路径)的系统分析仍鲜见报道.除此之外,本综述进一步从表面工程视角出发,深入解析不同改性策略的增效机制,并介绍相关的高通量计算构建改性策略与性能提升的定量关系模型.本文为突破碳电极“活性–稳定性–成本”权衡瓶颈提供理论依据,对推动下一代液流电池关键材料开发具有重要指导意义. 展开更多
关键词 铁铬液流电池 碳基电极 官能团 催化剂 活性位点
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基于UG和Moldflow的多功能笔注塑模设计 被引量:4
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作者 魏剑 高浩 王孝鹏 《塑料科技》 CAS 北大核心 2018年第2期93-98,共6页
借助UG进行多功能笔的注塑模设计,在得到注塑成型工艺参数及模具结构的基础上,应用Moldflow 6.1软件对模具流道进行网格划分,分析最佳浇口位置,根据调整后的各项工艺参数给出了充填、流动、翘曲部分具有代表性的模流结果,预测后期制造... 借助UG进行多功能笔的注塑模设计,在得到注塑成型工艺参数及模具结构的基础上,应用Moldflow 6.1软件对模具流道进行网格划分,分析最佳浇口位置,根据调整后的各项工艺参数给出了充填、流动、翘曲部分具有代表性的模流结果,预测后期制造中可能出现的问题。与传统模具设计方法相比,Moldflow 6.1软件的模拟分析提高了模具设计的准确性和效率,缩短了模具设计和制造周期。 展开更多
关键词 多功能笔 UG MOLDflow 注塑模设计 流动分析
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模糊交货期Flow-shop调度问题的改进微粒群算法 被引量:5
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作者 柳毅 叶春明 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2009年第1期145-148,共4页
针对企业生产中由定单变化引起的具有模糊交货期性质的连续生产调度问题,提出一种改进的微粒群算法.通过对模糊交货期Flowshop调度问题的模糊机会约束设置惩罚函数,引入自适应变异和交叉等方法来改进算法,仿真结果表明算法具有较好的全... 针对企业生产中由定单变化引起的具有模糊交货期性质的连续生产调度问题,提出一种改进的微粒群算法.通过对模糊交货期Flowshop调度问题的模糊机会约束设置惩罚函数,引入自适应变异和交叉等方法来改进算法,仿真结果表明算法具有较好的全局寻优和实用性,优于遗传算法和启发式算法. 展开更多
关键词 流水车间调度 模糊交货期 微粒群算法 惩罚函数
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Time lag characteristics of sap flow in seed-maize and their implications for modeling transpiration in an arid region of Northwest China 被引量:5
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作者 BO Xiaodong DU Taisheng +1 位作者 DING Risheng Louise COMAS 《Journal of Arid Land》 SCIE CSCD 2017年第4期515-529,共15页
Plant capacity for water storage leads to time lags between basal stem sap flow and transpiration in various woody plants. Internal water storage depends on the sizes of woody plants. However, the changes and its infl... Plant capacity for water storage leads to time lags between basal stem sap flow and transpiration in various woody plants. Internal water storage depends on the sizes of woody plants. However, the changes and its influencing factors in time lags of basal stem flow during the development of herbaceous plants including crops remain unclear. A field experiment was conducted in an arid region of Northwest China to examine the time lag characteristics of sap flow in seed-maize and to calibrate the transpiration modeling. Cross-correlation analysis was used to estimate the time lags between stem sap flow and meteorological driving factors including solar radiation(R_s) and vapor pressure deficit of the air(VPD_(air)). Results indicate that the changes in seed-maize stem sap flow consistently lagged behind the changes in R_s and preceded the changes in VPD_(air) both on hourly and daily scales, suggesting that light-mediated stomatal closures drove sap flow responses. The time lag in the maize's sap flow differed significantly during different growth stages and the difference was potentially due to developmental changes in capacitance tissue and/or xylem during ontogenesis. The time lags between stem sap flow and R_s in both female plants and male plants corresponded to plant use of stored water and were independent of total plant water use. Time lags of sap flow were always longer in male plants than in female plants. Theoretically, dry soil may decrease the speed by which sap flow adjusts ahead of shifts in VPD_(air) in comparison with wet soil and also increase the speed by which sap flow adjusts to R_s. However, sap flow lags that were associated with R_s before irrigation and after irrigation in female plants did not shift. Time series analysis method provided better results for simulating seed-maize sap flow with advantages of allowing for fewer variables to be included. This approach would be helpful in improving the accuracy of estimation for canopy transpiration and conductance using meteorological measurements. 展开更多
关键词 seed-maize sap flow capacitance transfer function model time lag stored water use
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