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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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Effect of extrusion temperature on the physical properties of high-silicon aluminum alloy

YANG Fuliang, GAN Weiping, CHEN Zhaoke

《机械工程前沿（英文）》 2007年 第2卷 第1期   页码 120-124 doi: 10.1007/s11465-007-0021-y

摘要： Light-weight high-silicon aluminum alloys are used for electronic packaging in the aviation and space-flight industry. Al-30Si and Al-40Si are fabricated with air-atomization and vacuum-canning hot-extrusion process. The density, thermal conductivity, hermeticity and thermal expansion coefficients of the material are measured, and the relationship between extrusion temperature and properties is obtained. Experimental results show that the density of high-silicon aluminum alloys prepared with this method is as high as 99.64% of the theory density, and increases with elevating extrusion temperature. At the same time, thermal conductivity varies between 104-140 W/(m " K); with the extrusion temperature, thermal expansion coefficient also increases but within 13?10 (at 100?C) and hermeticity of the material is high to 10 order of magnitude.

关键词： coefficient     hermeticity     temperature     relationship     air-atomization    

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The combined effects of biomass and temperature on maximum specific ammonia oxidation rate in domestic

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1411-9

摘要：

• Actual SAORs was determined using MLVSS and temperature.

关键词： Specific ammonia oxidation rate     Sequencing batch reactor     Biomass     Temperature coefficient     Model simulation    

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Simulation on thermodynamic state of ammonia carbonation at low temperature and low pressure

Jingcai ZHAO, Xingfu SONG, Ze SUN, Jianguo YU

《化学科学与工程前沿（英文）》 2013年 第7卷 第4期   页码 447-455 doi: 10.1007/s11705-013-1370-1

摘要： This study on thermodynamic property of NH -CO -H O system provided the basic data for ammonia carbonation. Simulations on vapor-liquid equilibrium (VLE) of ammonia carbonation with different physical properties were discussed in NH -H O and NH -CO -H O systems, respectively. The results indicated that at low temperature (303.15 K–363.15 K) and pressure (0.1–0.4 MPa), the PR (Peng-Robinson) equation was suitable for the description of the thermodynamic state in NH -H O system. NRTL (Non-Random-Two-Liquid) series models were selected for NH -CO -H O mixed electrolyte solution system. VLE data regression results showed that NRTL series models were suitable for describing thermodynamic properties of NH -CO -H O system, because average relative error fitting with each model was about 1%. As an asymmetric electrolytes model in NRTL model, E–NRTLRK (Electrolyte NRTL Redlich Kwong) could most accurately fit VLE data of NH -CO -H O system, with fitting error less than 1%. In the extent temperature range of 273.15 K–363.15 K, the prediction of product component using E-NRTLRK model for ammonia carbonation agreed well with the data reported in literature.

关键词： vapor-liquid equilibrium     activity coefficient     carbon dioxide     ammonia     NRTL    

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Sensitivity analysis and numerical experiments on transient test of compact heat exchanger surfaces

REN Hesheng, LAI Lingjun, CUI Yongzheng

《能源前沿（英文）》 2008年 第2卷 第4期   页码 374-380 doi: 10.1007/s11708-008-0079-1

摘要： A single-blow transient testing technique considering the effect of longitudinal heat conduction is suggested for determining the average convection heat transfer coefficient of compact heat exchanger surface. By matching the measured outlet fluid temperature variation with similar theoretical curves, the dimensionless longitudinal conduction parameter , the time constant of the inlet fluid temperature , and the number of heat transfer units can be determined simultaneously using the Levenberg-Marquardt nonlinear parameter estimation method. Both sensitivity analysis and numerical experiments with simulated measurements containing random errors show that the method in the present investigation provides satisfactory accuracy of the estimated parameter , which characterizes the heat transfer performance of compact heat exchanger surfaces.

关键词： coefficient     dimensionless longitudinal     longitudinal     temperature     conduction    

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Dynamic fate modeling of γ-hexachlorocyclohexane in the lower reaches of the Liao River

LIU Zhenyu, YANG Fenglin, QUAN Xie, ZHANG Xiaohong

《环境科学与工程前沿（英文）》 2007年 第1卷 第2期   页码 166-171 doi: 10.1007/s11783-007-0029-x

摘要： A QWASI model dependent on temperature is parameterized to describe the long-term fate of persistent organic pollutants (POPs) in the Liao River. The model parameters, namely fugacity capacity, degradation rate, and transfer coefficient, are profoundly affected by temperature. This model is used to simulate the fate of γ-hexachlorocyclohexane (γ-HCH) in the lower reaches of the Liao River from 1998 to 2008. Modeling results show that γ-HCH fugacity capacities in air, water, and sediment increase as temperature decreases, and the transfer and transformation rate coefficients increase as temperature increases. The variations of transfer and transformation parameter values depend on fugacity capacities, and transfer and transformation coefficients simultaneously. The performance of the model is evaluated by comparing the predicted and observed concentrations in the water and sediment of the Liao River. The predicted values agree well with the observed value in the order of magnitude, in most cases within the factor of 3. It is believed that the model is appropriate for simulating the long term fate of POPs in the Liao River.

关键词： coefficient     POPs     temperature     sediment increase     dependent    

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Efficient MgO-doped CaO sorbent pellets for high temperature CO

Zhihong Xu, Tao Jiang, Hao Zhang, Yujun Zhao, Xinbin Ma, Shengping Wang

《化学科学与工程前沿（英文）》 2021年 第15卷 第3期   页码 698-708 doi: 10.1007/s11705-020-1981-2

摘要： Novel MgO-doped CaO sorbent pellets were prepared by gel-casting and wet impregnation. The effect of Na and MgO on the structure and CO adsorption performance of CaO sorbent pellets was elucidated. MgO-doped CaO sorbent pellets with the diameter range of 0.5 1.5 mm exhibited an excellent capacity for CO adsorption and adsorption rate due to the homogeneous dispersion of MgO in the sorbent pellets and its effects on the physical structure of sorbents. The results show that MgO can effectively inhibit the sintering of CaO and retain the adsorption capacity of sorbents during multiple adsorption-desorption cycles. The presence of mesopores and macropores resulted in appreciable change of volume from CaO (16.7 cm ∙mol ) to CaCO (36.9 cm ∙mol ) over repeated operation cycles. Ca2Mg1 sorbent pellets exhibited favorable CO capture capacity (9.49 mmol∙g ), average adsorption rate (0.32 mmol∙g ∙min ) and conversion rate of CaO (74.83%) after 30 cycles.

关键词： MgO doping     CaO sorbent pellets     gel-casting technique     CO2 capture    

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New technique of precision necking for long tubes with variable wall thickness

Yongqiang GUO, Chunguo XU, Jingtao HAN, Zhengyu WANG

《机械工程前沿（英文）》 2020年 第15卷 第4期   页码 622-630 doi: 10.1007/s11465-019-0565-7

摘要： This study analyzed the deformation law of rear axles with variable wall thickness under bidirectional horizontal extrusion and found that necking was accompanied by upsetting deformation through theoretical calculation, numerical simulation, and experimental research. The sequence and occurrence of necking and upsetting deformations were obtained. A theory of deformation was proposed by controlling the distribution of temperature field. Effective processes to control the wall thickness of rear axle at different positions were also proposed. The ultimate limit deformation with a necking coefficient of 0.68 could be achieved using the temperature gradient coefficient. A new technology of two-step heating and two-step extrusion for a 13 t rear axle was developed, qualified test samples were obtained, and suggestions for further industrial application were put forward.

关键词： extrusion     rear axle     necking coefficient     temperature gradient    

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Preparation and properties of nano SiO2 core-shell structured additives and their nanocomposite with polypropylene

KE Yangchuan, SUN Mingzhuo, SONG Yanxin, YANG GuangFu

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 76-80 doi: 10.1007/s11705-007-0016-6

摘要： To improve the performance of traditional nucleation additives and their compatibility with other additives, as well as to solve complex problems in practical applications, SiO precursors were reactively grafted in situ with the symmetrical hydroxyl groups of the nucleation agents. With this approach, the dissymmetrical part of the nucleation agents plays an important role. As a result, the prepared composite additive the nanoparticle precursor (NPP0) produces excellent results. The NPP0-PP composite has a transparency of over 93%, haze lower than 15%, and a heat distortion temperature (HDT) of 142?C, which is more than the 110?C of the pure PP matrix. In addition, it maintains over 90% of the mechanical properties with a deformation coefficient less than 1%. This indicates a strong nanoeffect.

关键词： deformation coefficient     distortion temperature     excellent     NPP0-PP     traditional nucleation    

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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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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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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

Effect of extrusion temperature on the physical properties of high-silicon aluminum alloy

YANG Fuliang, GAN Weiping, CHEN Zhaoke

期刊论文

The combined effects of biomass and temperature on maximum specific ammonia oxidation rate in domestic

期刊论文

Simulation on thermodynamic state of ammonia carbonation at low temperature and low pressure

Jingcai ZHAO, Xingfu SONG, Ze SUN, Jianguo YU

期刊论文

Sensitivity analysis and numerical experiments on transient test of compact heat exchanger surfaces

REN Hesheng, LAI Lingjun, CUI Yongzheng

期刊论文

Dynamic fate modeling of γ-hexachlorocyclohexane in the lower reaches of the Liao River

LIU Zhenyu, YANG Fenglin, QUAN Xie, ZHANG Xiaohong

期刊论文

Efficient MgO-doped CaO sorbent pellets for high temperature CO

Zhihong Xu, Tao Jiang, Hao Zhang, Yujun Zhao, Xinbin Ma, Shengping Wang

期刊论文

New technique of precision necking for long tubes with variable wall thickness

Yongqiang GUO, Chunguo XU, Jingtao HAN, Zhengyu WANG

期刊论文

Preparation and properties of nano SiO2 core-shell structured additives and their nanocomposite with polypropylene

KE Yangchuan, SUN Mingzhuo, SONG Yanxin, YANG GuangFu

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

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