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Influence of temperature on cam-tappet lubrication in an internal combustion engine

CHANG Qiuying, YANG Peiran, WANG Jing, CHEN Quanshi

《机械工程前沿（英文）》 2007年 第2卷 第4期   页码 489-492 doi: 10.1007/s11465-007-0085-8

摘要： The transient thermo-elastohydrodynamic (TEHL) lubrication simulation and isothermal elastohydrodynamic (EHL) simulation were performed on the exhausting cam-tappet friction pair of an internal combustion engine. Although by employing the two models the center pressure, the thickness of the lubricant film and friction coefficient obtained were similar in the changing trend during a rotating cycle, the parameters make a great difference, especially for the thickness of the lubricant film; the TEHL was four times thicker than the EHL. These results show that the temperature should not be neglected in the study of the lubrication of cam-tappet pairs.

关键词： coefficient     combustion     isothermal elastohydrodynamic     temperature     thickness    

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Influence of initial curing conditions and exposure environments on chloride migration in concrete using

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 348-353 doi: 10.1007/s11709-010-0077-3

摘要： To investigate the influence of initial curing conditions and exposure environments on chloride ions’ migration in concrete, the specimens that were cured in different conditions and placed in several marine environments were studied. The amount of chloride ions passing through the specimen’s section was monitored in the accelerated chloride migration test. The effective chloride diffusion coefficients () were calculated from the steady-state on the basis of Nernst-Planck’s equation. The results indicated that the initial curing conditions and the wet-dry interval of external environments have coupling influence on effective diffusion coefficient of chloride ion significantly. reflected the density and pore connectivity of concrete. The co-effects of the initial curing condition and following exposure environment should be taken into account in durability design for concrete structure located in marine environment.

关键词： durability     effective diffusion coefficient     steady-state     migration test    

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Nonlinear design-point performance adaptation approaches and their comparisons for gas turbine applications

Y. G. LI, P. PILIDIS,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 446-455 doi: 10.1007/s11708-009-0042-9

摘要： Accurate performance simulation and understanding of gas turbine engines is very useful for gas turbine manufacturers and users alike and such a simulation normally starts from its design point. When some of the engine component parameters for an existing engine are not available, they must be estimated in order that the performance analysis can be started. Therefore, the simulated design point performance of an engine may be slightly different from its actual performance. In this paper, two nonlinear gas turbine design-point performance adaptation approaches have been presented to best estimate the unknown component parameters and match available design point engine performance, one using a nonlinear matrix inverse adaptation method and the other using a Genetic Algorithm-based adaptation approach. The advantages and disadvantages of the two adaptation methods have been compared with each other. In the approaches, the component parameters may be compressor pressure ratios and efficiencies, turbine entry temperature, turbine efficiencies, engine mass flow rate, cooling flows, and by-pass ratio, etc. The engine performance parameters may be thrust and SFC for aero engines, shaft power, and thermal efficiency for industrial engines, gas path pressures, temperatures, etc. To select the most appropriate to-be-adapted component parameters, a sensitivity bar chart is used to analyze the sensitivity of all potential component parameters against the engine performance parameters. The two adaptation approaches have been applied to a model gas turbine engine. The application shows that the sensitivity bar chart is very useful in the selection of the to-be-adapted component parameters, and both adaptation approaches are able to produce good quality engine models at design point. The comparison of the two adaptation methods shows that the nonlinear matrix inverse method is faster and more accurate, while the genetic algorithm-based adaptation method is more robust but slower. Theoretically, both adaptation methods can be extended to other gas turbine engine performance modelling applications.

关键词： gas turbine     engine     performance adaptation     performance matching     design-point performance simulation     influence coefficient matrix     genetic algorithm    

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Balancing method without trial weights for rotor systems based on similitude scale model

Ruiduo YE, Liping WANG, Xiaojie HOU, Zhong LUO, Qingkai HAN

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 571-580 doi: 10.1007/s11465-018-0478-x

摘要：

A balancing method without trial weights based on the dynamic similitude scale model was proposed as a solution to the balancing problem of a large-scale rotor system. This method could be used to directly obtain the required coefficients for the balancing problem of the prototype system through a similarity model test without a prototype test. Thus, the weight test process of the prototype system was effectively eliminated in the proposed balancing method. First, with the rotor system as the research object, the analytical expression of the influence coefficient was derived on the basis of rotor dynamics theory. Then, through calculation and dimensional analysis methods, the similitude relationships of the rotor system and the influence coefficient were deduced on the basis of dynamic similitude theory. The correctness of the proposed similitude relationships was verified through numerical simulation and experiment. The balancing method without trial weights was proposed based on the similitude relationship of the influence coefficient. The effect of the balancing method without trial weights was compared with that of the traditional influence coefficient method through numerical simulation, and the results verified the correctness and effectiveness of the proposed balancing method. The results of this study provide theoretical supplements for the balancing method and the similitude design of the rotor system.

关键词： rotor system     dynamic similitude     balancing     without trial weights     influence coefficient    

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RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 2161-2161 doi: 10.1007/s11705-009-0143-3

摘要： RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

关键词： tee junction     Momentum exchange coefficient     RETRACTED    

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Experimental study of heat transfer coefficient with rectangular baffle fin of solar air heater

Foued CHABANE,Nesrine HATRAF,Noureddine MOUMMI

《能源前沿（英文）》 2014年 第8卷 第2期   页码 160-172 doi: 10.1007/s11708-014-0321-y

摘要： This paper presents an experimental analysis of a single pass solar air collector with, and without using baffle fin. The heat transfer coefficient between the absorber plate and air can be considerably increased by using artificial roughness on the bottom plate and under the absorber plate of a solar air heater duct. An experimental study has been conducted to investigate the effect of roughness and operating parameters on heat transfer. The investigation has covered the range of Reynolds number from 1259 to 2517 depending on types of the configuration of the solar collectors. Based on the experimental data, values of Nusselt number have been determined for different values of configurations and operating parameters. To determine the enhancement in heat transfer and increment in thermal efficiency, the values of Nusselt have been compared with those of smooth duct under similar flow conditions.

关键词： Nusselt number     flow rate     heat transfer     heat transfer coefficient     thermal efficiency     forced convection    

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A photolysis coefficient for characterizing the response of aqueous constituents to photolysis

David R. HOKANSON,Ke LI,R. Rhodes TRUSSELL

《环境科学与工程前沿（英文）》 2016年 第10卷 第3期   页码 428-437 doi: 10.1007/s11783-015-0780-3

摘要： UV photolysis and UV based advanced oxidation processes (AOPs) are gaining more and more attention for drinking water treatment. Quantum yield ( ) and molar absorption coefficient ( ) are the two critical parameters measuring the effectiveness of photolysis of a compound. The product of the two was proposed as a fundamental measure of a constituent’s amenability to transformation by photolysis. It was shown that this product, named the photolysis coefficient, , can be determined using standard bench tests and captures the properties that govern a constituent’s transformation when exposed to light. The development showed the photolysis coefficient to be equally useful for microbiological, inorganic and organic constituents. Values of calculated by the authors based on quantum yield and molar absorption coefficient data from the literature were summarized. Photolysis coefficients among microorganisms ranged from 8500 to more than 600000 and are far higher than for inorganic and organic compounds, which varied over a range of approximately 10 to 1000 and are much less sensitive to UV photolysis than the microorganisms.

关键词： UV photolysis     disinfection     advanced oxidation     N-nitrosodimethylamine     quantum yield     absorption coefficient    

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Effect of heat transfer coefficient of steam turbine rotor on thermal stress field under off-design condition

Jie GUO,Danmei XIE,Hengliang ZHANG,Wei JIANG,Yan ZHOU

《能源前沿（英文）》 2016年 第10卷 第1期   页码 57-64 doi: 10.1007/s11708-015-0385-3

摘要： The precise calculation of temperature and thermal stress field of steam turbine rotor under off-design conditions is of paramount significance for safe and economic operation, in which an accurate calculation of heat transfer (HT) coefficient plays a decisive role. HT coefficient changes dramatically along with working conditions. First, a finite element analysis of rotor model, applied with ordinary rotor materials, has been conducted to investigate the temperature and thermal stress difference along with the change of HT coefficient from 20 W/(m ·°C) to 20000 W/(m ·°C). Next, the differentiation between existing empirical formulas has been analyzed from the aspect of physical significance of non-dimension parameters. Finally, a verifying case of the cold startup of a 1000MW unit has been proceeded. The result shows that the accuracy of coefficient calculation when steam parameters are low has a greater influence on that of rotor temperature and thermal stress, which means a precise empirical HT coefficient formula, like the Sarkar formula is strongly recommended. When steam parameters are high and HT coefficient is larger than 10 W/(m ·°C), there will be barely any influence on the calculation of thermal stress. This research plays a constructive role in the calculation and analysis of thermal stress.

关键词： steam turbine     rotor     thermal stress     heat transfer coefficient     empirical formula    

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Dimensionality reduction and prediction of soil consolidation coefficient using random forest coupling

Hai-Bang LY; Huong-Lan Thi VU; Lanh Si HO; Binh Thai PHAM

《结构与土木工程前沿（英文）》 2022年 第16卷 第2期   页码 224-238 doi: 10.1007/s11709-022-0812-6

摘要： The consolidation coefficient of soil (Cv) is a crucial parameter used for the design of structures leaned on soft soi. In general, the Cv is determined experimentally in the laboratory. However, the experimental tests are time-consuming as well as expensive. Therefore, researchers tried several ways to determine Cv via other simple soil parameters. In this study, we developed a hybrid model of Random Forest coupling with a Relief algorithm (RF-RL) to predict the Cv of soil. To conduct this study, a database of soil parameters collected from a case study region in Vietnam was used for modeling. The performance of the proposed models was assessed via statistical indicators, namely Coefficient of determination (R2), Root Mean Squared Error (RMSE), and Mean Absolute Error (MAE). The proposal models were constructed with four sets of soil variables, including 6, 7, 8, and 13 inputs. The results revealed that all models performed well with a high performance (R2 > 0.980). Although the RF-RL model with 13 variables has the highest prediction accuracy ( R2 = 0.9869), the difference compared with other models was negligible (i.e., R2 = 0.9824, 0.9850, 0.9825 for the cases with 6, 7, 8 inputs, respectively). Thus, it can be concluded that the hybrid model of RF-RL can be employed to predict Cv based on the basic soil parameters.

关键词： soil consolidation coefficient     machine learning     random forest     Relief    

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Identifying spreading influence nodes for social networks

《工程管理前沿（英文）》   页码 520-549 doi: 10.1007/s42524-022-0190-8

摘要： The identification of spreading influence nodes in social networks, which studies how to detect important individuals in human society, has attracted increasing attention from physical and computer science, social science and economics communities. The identification algorithms of spreading influence nodes can be used to evaluate the spreading influence, describe the node’s position, and identify interaction centralities. This review summarizes the recent progress about the identification algorithms of spreading influence nodes from the viewpoint of social networks, emphasizing the contributions from physical perspectives and approaches, including the microstructure-based algorithms, community structure-based algorithms, macrostructure-based algorithms, and machine learning-based algorithms. We introduce diffusion models and performance evaluation metrics, and outline future challenges of the identification of spreading influence nodes.

关键词： complex network     network science     spreading influence     machine learning    

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Developing the QSPR model for predicting the storage lipid/water distribution coefficient of organic

Miao Li, Jian Li, Yuchen Lu, Cenyang Han, Xiaoxuan Wei, Guangcai Ma, Haiying Yu

《环境科学与工程前沿（英文）》 2021年 第15卷 第2期 doi: 10.1007/s11783-020-1316-z

摘要： Abstract • A predictive model for storage lipid/water distribution coefficient was developed. • The model yields outstanding fitting performance, robustness, and predictive ability. • Hydrophobic and electrostatic interactions and molecular size dominate log Klip/w. • The model can be used in a wide application domain to predict log Klip/w values. The distribution of organic compounds in stored lipids affects their migration, transformation, bioaccumulation, and toxicity in organisms. The storage lipid/water distribution coefficient (log Klip/w) of organic chemicals, which quantitatively determines such distribution, has become a key parameter to assist their ecological security and health risk. Due to the impossibility to measure Klip/w values for a huge amount of chemicals, it is necessary to develop predictive approaches. In this work, a quantitative structure-property relationship (QSPR) model for estimating log Klip/w values of small organic compounds was constructed based on 305 experimental log Klip/w values. Quantum chemical descriptors and n-octanol/water partitioning coefficient were employed to characterize the intermolecular interactions that dominate log Klip/w values. The hydrophobic and electrostatic interactions and molecular size have been found to play important roles in governing the distribution of chemicals between lipids and aqueous phases. The regression (R2 = 0.959) and validation (Q2 = 0.960) results indicate good fitting performance and robustness of the developed model. A comparison with the predictive performance of other commercial software further proves the higher accuracy and stronger predictive ability of the developed Klip/w predictive model. Thus, it can be used to predict the Klip/w values of cycloalkanes, long-chain alkanes, halides (with fluorine, chlorine, and bromine as substituents), esters (without phosphate groups), alcohols (without methoxy groups), and aromatic compounds.

关键词： Storage lipid/water distribution coefficient     log Klip/w     Organic compounds     QSPR     Quantum chemical descriptors    

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Heat transfer coefficient of wheel rim of large capacity steam turbines

SHI Jinyuan, DENG Zhicheng, YANG Yu, JUN Ganwen

《能源前沿（英文）》 2008年 第2卷 第1期   页码 20-24 doi: 10.1007/s11708-008-0015-4

摘要： A way of calculating the overall equivalent heat transfer coefficient of wheel rims of large capacity steam turbines is presented. The method and formula to calculate the mean forced convection heat-transfer coefficient of the surface of the blade and for the bottom wall of the blade passage, are introduced. The heat transmission from the blade to the rim was simplified by analogy to heat transmission in the fins. A fin heat transfer model was then used to calculate the equivalent heat transfer coefficient of the blade passage. The overall equivalent heat transfer coefficient of the wheel rim was then calculated using a cylindrical surface model. A practical calculation example was presented. The proposed method helps determine the heat transfer boundary conditions in finite element analyses of temperature and thermal stress fields of steam turbine rotors.

关键词： convection heat-transfer     capacity     heat-transfer coefficient     bottom     transmission    

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Diagnosis method based on wavelet coefficient scale relativity correlation dimension for fault

GU Junjie, TIAN Jin, PENG Xuezhi

《能源前沿（英文）》 2008年 第2卷 第2期   页码 164-168 doi: 10.1007/s11708-008-0031-4

摘要： Correlation dimension as a tool to describe machinery condition is introduced. Vibration signals of the fan under different working conditions are analyzed using a threshold filtering algorithm based on the region relativity of the wavelet coefficients for reducing noise. The result shows that the characteristics of the signal could be preserved completely. The correlation dimension is able to identify conditions of the fan with faults compared with the normal condition, thereby providing an effective technology for condition monitoring and fault diagnosis of mechanical equipment.

关键词： effective technology     monitoring     mechanical equipment     relativity     Correlation    

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Heterogeneous influence of individuals’ behavior on mask efficacy in gathering environments

《工程管理前沿（英文）》   页码 550-562 doi: 10.1007/s42524-022-0193-5

摘要： Wearing masks is an easy way to operate and popular measure for preventing epidemics. Although masks can slow down the spread of viruses, their efficacy in gathering environments involving heterogeneous person-to-person contacts remains unknown. Therefore, we aim to investigate the epidemic prevention effect of masks in different real-life gathering environments. This study uses four real interpersonal contact datasets to construct four empirical networks to represent four gathering environments. The transmission of COVID-19 is simulated using the Monte Carlo simulation method. The heterogeneity of individuals can cause mask efficacy in a specific gathering environment to be different from the baseline efficacy in general society. Furthermore, the heterogeneity of gathering environments causes the epidemic prevention effect of masks to differ. Wearing masks can greatly reduce the probability of clustered epidemics and the infection scale in primary schools, high schools, and hospitals. However, the use of masks alone in primary schools and hospitals cannot control outbreaks. In high schools with social distancing between classes and in workplaces where the interpersonal contact is relatively sparse, masks can meet the need for prevention. Given the heterogeneity of individual behavior, if individuals who are more active in terms of interpersonal contact are prioritized for mask-wearing, the epidemic prevention effect of masks can be improved. Finally, asymptomatic infection has varying effects on the prevention effect of masks in different environments. The effect can be weakened or eliminated by increasing the usage rate of masks in high schools and workplaces. However, the effect on primary schools and hospitals cannot be weakened. This study contributes to the accurate evaluation of mask efficacy in various gathering environments to provide scientific guidance for epidemic prevention.

关键词： COVID-19     masks     behavioral heterogeneity     asymptomatic infection    

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社会影响力分析——模型、方法和评价 Review

李侃, 张林, 黄河燕

《工程（英文）》 2018年 第4卷 第1期   页码 40-46 doi: 10.1016/j.eng.2018.02.004

摘要：

社会影响力分析（SIA）是一个广泛的研究领域，吸引了诸多研究者的兴趣。本文总结了SIA 相关的模型、方法和评价方面代表性的工作，并将SIA 模型归纳为两种类型：微观模型和宏观模型。微观模型考虑人与人之间的相互影响和影响的过程，而宏观模型认为每个人具有相同的传播概率和影响力。本文分析了包括影响最大化、影响最小化、影响流和个人影响力等的社会影响力分析方法；介绍了影响力评价指标，并分析了社会影响力评价模型。本文的目标是对社会影响力提供全面的分析，旨在辅助理解社会行为，为舆论影响提供理论基础，并揭示未来的研究方向和潜在的应用。

关键词： 社会影响力分析     在线社交网络     社会影响力分析模型     影响力评价    

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标题 作者 时间 类型 操作

Influence of temperature on cam-tappet lubrication in an internal combustion engine

CHANG Qiuying, YANG Peiran, WANG Jing, CHEN Quanshi

期刊论文

Influence of initial curing conditions and exposure environments on chloride migration in concrete using

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

期刊论文

Nonlinear design-point performance adaptation approaches and their comparisons for gas turbine applications

Y. G. LI, P. PILIDIS,

期刊论文

Balancing method without trial weights for rotor systems based on similitude scale model

Ruiduo YE, Liping WANG, Xiaojie HOU, Zhong LUO, Qingkai HAN

期刊论文

RETRACTED ARTICLE: Momentum exchange coefficient for two jet flows mixing in a tee junction

期刊论文

Experimental study of heat transfer coefficient with rectangular baffle fin of solar air heater

Foued CHABANE,Nesrine HATRAF,Noureddine MOUMMI

期刊论文

A photolysis coefficient for characterizing the response of aqueous constituents to photolysis

David R. HOKANSON,Ke LI,R. Rhodes TRUSSELL

期刊论文

Effect of heat transfer coefficient of steam turbine rotor on thermal stress field under off-design condition

Jie GUO,Danmei XIE,Hengliang ZHANG,Wei JIANG,Yan ZHOU

期刊论文

Dimensionality reduction and prediction of soil consolidation coefficient using random forest coupling

Hai-Bang LY; Huong-Lan Thi VU; Lanh Si HO; Binh Thai PHAM

期刊论文

Identifying spreading influence nodes for social networks

期刊论文

Developing the QSPR model for predicting the storage lipid/water distribution coefficient of organic

Miao Li, Jian Li, Yuchen Lu, Cenyang Han, Xiaoxuan Wei, Guangcai Ma, Haiying Yu

期刊论文

Heat transfer coefficient of wheel rim of large capacity steam turbines

SHI Jinyuan, DENG Zhicheng, YANG Yu, JUN Ganwen

期刊论文

Diagnosis method based on wavelet coefficient scale relativity correlation dimension for fault

GU Junjie, TIAN Jin, PENG Xuezhi

期刊论文

Heterogeneous influence of individuals’ behavior on mask efficacy in gathering environments

期刊论文

社会影响力分析——模型、方法和评价

李侃, 张林, 黄河燕

期刊论文