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Simulation of bubble column reactors using CFD coupled with a population balance model

Tiefeng WANG

《化学科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 162-172 doi: 10.1007/s11705-009-0267-5

摘要： Bubble columns are widely used in chemical and biochemical processes due to their excellent mass and heat transfer characteristics and simple construction. However, their fundamental hydrodynamic behaviors, which are essential for reactor scale-up and design, are still not fully understood. To develop design tools for engineering purposes, much research has been carried out in the area of computational fluid dynamics (CFD) modeling and simulation of gas-liquid flows. Due to the importance of the bubble behavior, the bubble size distribution must be considered in the CFD models. The population balance model (PBM) is an effective approach to predict the bubble size distribution, and great efforts have been made in recent years to couple the PBM into CFD simulations. This article gives a selective review of the modeling and simulation of bubble column reactors using CFD coupled with PBM. Bubble breakup and coalescence models due to different mechanisms are discussed. It is shown that the CFD-PBM coupled model with proper bubble breakup and coalescence models and interphase force formulations has the ability of predicting the complex hydrodynamics in different flow regimes and, thus, provides a unified description of both the homogeneous and heterogeneous regimes. Further study is needed to improve the models of bubble coalescence and breakup, turbulence modification in high gas holdup, and interphase forces of bubble swarms.

关键词： bubble column     computational fluid dynamics     bubble breakup and coalescence     population balance model     bubble size distribution    

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Nonlinear sealing force of a seawater balance valve used in an 11000-meter manned submersible

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0726-y

摘要： Balance valve is a core component of the 11000-meter manned submersible “struggle,” and its sealing performance is crucial and challenging when the maximum pressure difference is 118 MPa. The increasing sealing force improves the sealing performance and increases the system’s energy consumption at the same time. A hybrid analytical–numerical–experimental (ANE) model is proposed to obtain the minimum sealing force, ensuring no leakage at the valve port and reducing energy consumption as much as possible. The effects of roundness error, environmental pressure, and materials on the minimum sealing force are considered in the ANE model. The basic form of minimum sealing force equations is established, and the remaining unknown coefficients of the equations are obtained by the finite element method (FEM). The accuracy of the equation is evaluated by comparing the independent FEM data to the equation data. Results of the comparison show good agreement, and the difference between the independent FEM data and equation data is within 3% when the environmental pressure is 0–118 MPa. Finally, the minimum sealing force equation is applied in a balance valve to be experimented using a deep-sea simulation device. The balance valve designed through the minimum sealing force equation is leak-free in the experiment. Thus, the minimum sealing force equation is suitable for the ultrahigh pressure balance valve and has guiding significance for evaluating the sealing performance of ultrahigh pressure balance valves.

关键词： seawater balance valve     sealing performance     hybrid ANE model     FEM     minimum sealing force equation    

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Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0676-4

摘要： The control system presently used in shield posture rectification is based on driver experience, which is marginally reliable. The study of the related theory is flawed. Therefore, a decision-making approach for the deviation correction trajectory and posture rectification load for an earth pressure balance (EPB) shield is proposed. A calculation model of posture rectification load of an EPB shield is developed by considering the interactions among the cutter head, shield shell, and ground. The additional position change during the shield attitude correction is highlighted. The posture rectification loads and shield behaviors results can be solved by the proposed method. The influences of the stratum distribution (i.e., bedrock height in the upper-soft and lower-hard strata) on shield behaviors and posture rectification loads are analyzed. Results indicated that the increase of pitch angle in the upper-soft and lower-hard strata causes a sharp rise in vertical displacement. The bedrock height increases the magnitudes of the required posture rectification moments when hr/D > 0.5. For a tunnel with hr/D ≤ 0.5, the variation of hr/D has little effect on the posture rectification moments. Finally, the posture rectifying curves based on the theoretical model are compared with the target ones based on the double circular arc interpolation method. The required results can be obtained regardless of the soil–rock compound stratum distribution. The maximum rectification moment in the rock layer is almost 12.6 times that in the soil layer. Overall, this study provides a valuable reference for moment determination and the trajectory prediction of posture rectification in compound strata.

关键词： additional position change     deviation correction trajectory     earth pressure balance shield     mechanical model     posture rectification    

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Optimization model for rotor blades of horizontal axis wind turbines

LIU Xiong, CHEN Yan, YE Zhiquan

《机械工程前沿（英文）》 2007年 第2卷 第4期   页码 483-488 doi: 10.1007/s11465-007-0084-9

摘要： This paper presents an optimization model for rotor blades of horizontal axis wind turbines. The model refers to the wind speed distribution function on the specific wind site, with an objective to satisfy the maximum annual energy output. To speed up the search process and guarantee a global optimal result, the extended compact genetic algorithm (ECGA) is used to carry out the search process. Compared with the simple genetic algorithm, ECGA runs much faster and can get more accurate results with a much smaller population size and fewer function evaluations. Using the developed optimization program, blades of a 1.3 MW stall-regulated wind turbine are designed. Compared with the existing blades, the designed blades have obviously better aerodynamic performance.

关键词： population     extended     algorithm     developed optimization     accurate    

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Gut microbial balance and liver transplantation: alteration, management, and prediction

null

《医学前沿（英文）》 2018年 第12卷 第2期   页码 123-129 doi: 10.1007/s11684-017-0563-2

摘要：

Liver transplantation is a conventional treatment for terminal stage liver diseases. However, several complications still hinder the survival rate. Intestinal barrier destruction is widely observed among patients receiving liver transplant and suffering from ischemia–reperfusion or rejection injuries because of the relationship between the intestine and the liver, both in anatomy and function. Importantly, the resulting alteration of gut microbiota aggravates graft dysfunctions during the process. This article reviews the research progress for gut microbial alterations and liver transplantation. Especially, this work also evaluates research on the management of gut microbial alteration and the prediction of possible injuries utilizing microbial alteration during liver transplantation. In addition, we propose possible directions for research on gut microbial alteration during liver transplantation and offer a hypothesis on the utilization of microbial alteration in liver transplantation. The aim is not only to predict perioperative injuries but also to function as a method of treatment or even inhibit the rejection of liver transplantation.

关键词： gut microbial balance     liver transplantation     ischemia–reperfusion     acute rejection    

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Quantitative analysis of yield and soil water balance for summer maize on the piedmont of the North China

Jingjing WANG,Feng HUANG,Baoguo LI

《农业科学与工程前沿（英文）》 2015年 第2卷 第4期   页码 295-310 doi: 10.15302/J-FASE-2015074

摘要： The North China Plain (NCP) is a major grain production area in China, but the current winter wheat-summer maize system has resulted in a large water deficit. This water-shortage necessitates the improvement of crop water productivity in the NCP. A crop water model, AquaCrop, was adopted to investigate yield and water productivity (WP) for rain-fed summer maize on the piedmont of the NCP. The data sets to calibrate and validate the model were obtained from a 3-year (2011–2013) field experiment conducted on the Yanshan piedmont of the NCP. The range of root mean square error (RMSE) between the simulated and measured biomass was 0.67–1.25 t·hm , and that of relative error (RE) was 9.4%–15.4%, the coefficient of determination ( ) ranged from 0.992 to 0.994. The RMSE between the simulated and measured soil water storage at depth of 0–100 cm ranged from 4.09 to 4.39 mm; and RE and in the range of 1.07%–1.20% and 0.880–0.997, respectively. The WP as measured by crop yield per unit evapotranspiration was 2.50–2.66 kg·m . The simulated impact of long-term climate (i.e., 1980–2010) and groundwater depth on crop yield and WP revealed that the higher yield and WP could be obtained in dry years in areas with capillary recharge from groundwater, and much lower values elsewhere. The simulation also suggested that supplementary irrigation in areas without capillary groundwater would not result in groundwater over-tapping since the precipitation can meet the water required by both maize and ecosystem, thus a beneficial outcome for both food and ecosystem security can be assured.

关键词： AquaCrop     summer maize     soil water balance     water productivity    

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Analysis of catchment evapotranspiration at different scales using bottom-up and top-down approaches

Xiangyu XU, Dawen YANG,

《结构与土木工程前沿（英文）》 2010年 第4卷 第1期   页码 65-77 doi: 10.1007/s11709-010-0002-9

摘要： Physically-based hydrological models are used to predict catchment water balance through detailed simulation of hydrological processes at small temporal and spatial scales. However, annual catchment water balance can also be easily and simply predicted using lumped conceptual model. Comparison between physically-based hydrological models and lumped conceptual models can help us understand the dominant factors on catchment water balance at different scales. In this paper, a distributed physically-based hydrological model (i.e., bottom-up approach) and a simple water-energy balance model (i.e., top-down approach) are used to predict actual evapotranspiration in nine sub-catchments, and the whole basin of the Luan River in northern China. Both simulations give very close values of annual evapotranspiration and show the same complementary relationship between actual and potential evapotranspiration at annual time scale. From the analysis at different time scales through comparison of the top-down and the bottom-up methods, it is shown that the annual catchment evapotranspiration is controlled mainly by annual precipitation and potential evapotranspiration, and the variability of soil water and vegetation becomes more important at a smaller time scale in the study areas. It is also known that the relationship between potential and actual evapotranspiration shows a highly nonlinear relationship at the annual and catchment scale but can be simplified to a linear relationship at hourly temporal and hillslope scales, which is commonly used in the physically-based hydrological models.

关键词： catchment evapotranspiration     distributed hydrological model     water-energy balance model     top-down and bottom-up approaches    

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Mass and heat balance calculations and economic evaluation of an innovative biomass pyrolysis project

Quanyuan WEI, Yongshui QU, Tianwei TAN

《化学科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 355-361 doi: 10.1007/s11705-010-0567-9

摘要： Biomass can be converted into flammable gas, charcoal, wood vinegar, wood tar oil and noncombustible materials with thermo-chemical pyrolysis reactions. Many factors influence these processes, such as the properties of the raw materials, and temperature control and these will affect the products that are produced. Based on the data from a straw pyrolysis demonstration project, the mass and heat balance of the biomass pyrolysis process were analyzed. The statistical product and service solutions (SPSS) statistical method was used to analyze the data which were monitored on-site. A cost-benefit analysis was then used to study the viability of commercializing the project. The analysis included net present value, internal rate of return and investment payback period. These results showed that the straw pyrolysis project has little risk, and will produce remarkable economic benefits.

关键词： mass balance     heat balance     biomass pyrolysis     economic benefit    

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具有冗余结构的分布式数据库服务器及其负载平衡模型

田俊峰,刘玉玲,杜瑞忠

《中国工程科学》 2004年 第6卷 第6期   页码 35-42

摘要：

服务器冗余技术在解决传统分布式环境的可用性和性能瓶颈问题的同时给系统的管理带来了新的挑战。介绍了一种分布式数据库服务器的构成原理及工作模型，重点讨论了它的冗余关系、基于移动代理的负载平衡模型及其性能分析等。

关键词： 分布式数据库     冗余     负载平衡     移动代理     性能分析    

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Effects of hydraulic retention time on nitrification activities and population dynamics of a conventional

Hongyan LI, Yu ZHANG, Min YANG, Yoichi KAMAGATA

《环境科学与工程前沿（英文）》 2013年 第7卷 第1期   页码 43-48 doi: 10.1007/s11783-012-0397-8

摘要： The effects of hydraulic retention time (HRT) on the nitrification activities and population dynamics of a conventional activated sludge system fed with synthetic inorganic wastewater were investigated over a period of 260 days. When the HRT was gradually decreased from 30 to 5 h, the specific ammonium-oxidizing rates (SAOR) varied between 0.32 and 0.45 kg (kg mixed liquor suspended solids (MLSS)·d) , and the specific nitrate-forming rates (SNFR) increased from 0.11 to 0.50 kg (kg MLSS·d) , showing that the decrease in HRT led to a significant increase in the nitrite oxidation activity. According to fluorescence in situ hybridization (FISH) analysis results, the proportion of ammonia-oxidizing bacteria (AOBs) among the total bacteria decreased from 33% to 15% with the decrease in HRT, whereas the fraction of nitrite-oxidizing bacteria (NOBs), particularly the fast-growing sp., increased significantly (from 4% to 15% for NOBs and from 1.5% to 10.6% for sp.) with the decrease in HRT, which was in accordance with the changes in SNFR. A short HRT favored the relative growth of NOBs, particularly the fast-growing sp., in the conventional activated sludge system.

关键词： ammonia-oxidizing bacteria     hydraulic retention time     nitrification activity     nitrite-oxidizing bacteria     population dynamics    

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Flow and mass balance analysis of eco-bio infiltration system

Marla C. MANIQUIZ, Lee-Hyung KIM, Soyoung LEE, Jiyeon CHOI

《环境科学与工程前沿（英文）》 2012年 第6卷 第5期   页码 612-619 doi: 10.1007/s11783-012-0448-1

摘要： A structured stormwater infiltration system was developed and constructed at a university campus and monitoring of storm events was performed during a one-year operation period. The flow and pollutant mass balances were analyzed and the overall efficiency of the system was assessed. While significant positive correlations were observed among rainfall, runoff and discharge volume ( = 0.93-0.99; <0.05), there was no significant correlations existed between rainfall, runoff, discharge volume and pollutant load. The system was more effective in reducing the runoff volume by more than 50% for small storm events but the difference between the runoff and discharge volume was significant even with rainfall greater than 10 mm. Results showed that the pollutant reduction rates were higher compared to the runoff volume reduction. Average pollutant reduction rates were in the range of 72% to 90% with coefficient of variation between 0.10 and 0.46. Comparable with runoff reduction, the system was more effective in reducing the pollutant load for small storm events, in the range of 80% to 100% for rainfall between 0 and 10 mm; while 65% to 80% for rainfall between 10 and 20 mm. Among the pollutant parameters, particulate matters was highly reduced by the system achieving only a maximum of 25% discharge load even after the entire runoff was completely discharged. The findings have proven the capability of the system as a tool in stormwater management achieving both flow reduction and water quality improvement.

关键词： best management practice     flow balance     low impact development     mass balance     nonpoint source     stormwater runoff    

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Socialized care services for the aged population: System construction and support measures

《工程管理前沿（英文）》 2023年 第10卷 第2期   页码 339-353 doi: 10.1007/s42524-022-0208-2

摘要： Given the aging society, an increase in social demand, information- and communication technology-driven culture, and government policy support emerges to enable the development of the socialized care services system for the aged (SCSSA). The development of the SCSSA would be a significant step toward addressing China’s aging population. However, the construction of the SCSSA challenges the theories and methods of traditional elderly care service system construction. Specifically, the implementation path for such elderly care service policies is unclear, the necessary technological support is insufficient, and the mechanism for integrating intelligent information technology remains underexplored. Thus, this paper focuses on the needs of the elderly, grounded in the context of the changing elderly care service policies in China, and proposes a research paradigm that integrates system construction and support measure embedding. We then construct the original SCSSA, which includes “material + spirit + medical treatment + healthcare” and propose a method of optimization and iteration. Finally, we build the research framework of systematic support measures from the perspectives of policy reconstruction, institutional embeddedness, and technical support. Our work provides theoretical support and practical guidance for the construction and dynamic optimization of the SCSSA, thus making a significant contribution that will help China effectively cope with its aging society.

关键词： socialized     care service for the elderly     system construction     support measure    

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Obesity and overweight prevalence and its association with undiagnosed hypertension in Shanghai population, China: a cross-sectional population-based survey

null

《医学前沿（英文）》 2012年 第6卷 第3期   页码 322-328 doi: 10.1007/s11684-012-0204-8

摘要：

The aim of this study was to determine the prevalence of overweight and obese subjects in the Shanghai population of China and its association with undiagnosed hypertension, by taking age, gender and place of residence (urban or suburban) into account. A cross-sectional population-based survey was conducted in 2007. The sample included 13 359 participants aged 15–69 years. Weight, height, and blood pressure were recorded, and information about gender, age and place of residence was obtained. Overweight and obesity prevalence were calculated by the body mass index (BMI) definition recommended by Working Group on Obesity in China (normal weight, 18.5–23.9 kg/m2; overweight, 24–27.9 kg/m2; obesity,≥28 kg/m2). Undiagnosed hypertension was defined by China criteria in accord with that of WHO-ISH (subjects with systolic pressure≥140 mmHg, and/or diastolic pressure≥90 mmHg). Multiple logistic regression analyses were used to assess the association of overweight or obesity with undiagnosed hypertension by adjusting for age, gender and place of residence. The overall overweight, obesity, and undiagnosed hypertension prevalence were 27.6% (95% CI: 26.8–28.4), 6.6% (95% CI: 6.2–7.0), and 15.5% (95% CI: 14.9–16.1), respectively. Compared to normal weight subjects, the odds ratios (OR) for subjects who were overweight and had hypertension was 2.33 (95% CI: 2.10–2.59); that for obesity and hypertension was 4.27 (95% CI: 3.66–4.99). These data suggest that overweight and obesity prevalence and their association with undiagnosed hypertension are high in our study population.

关键词： overweight     obesity     undiagnosed hypertension     prevalence     association    

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Prognostic analysis of chronic myeloid leukemia in Chinese population in an imatinib era

null

《医学前沿（英文）》 2012年 第6卷 第2期   页码 204-211 doi: 10.1007/s11684-012-0202-x

摘要：

We evaluated the outcomes of chronic myeloid leukemia (CML) patients in three clinical phases, namely, chronic (CP), accelerated (AP), and blast (BP) phases, receiving imatinib treatment. The single-institution treatment experiences of Chinese patients with CML were presented. A total of 275 CML patients (CP, 210; AP, 24; and BP, 41) who received imatinib between February 2001 and April 2008 were enrolled in this study. We evaluated the responses (hematologic, cytogenetic, and molecular), overall survival (OS), treatment event-free survival (EFS), and prognostic factors of outcome. At the cut-off point, the complete cytogenetic response (CCyR) and complete molecular response rates of patients in the CP were 84.7% and 61.9%, respectively, which were significantly higher than those of patients in the AP (50% and 29.1%, respectively, both P<0.001) and BP (24.3% and 9.7%, respectively, both P<0.001). The estimated five-year OS and five-year EFS rates were 93.2% and 86.4% for CP patients, as well as 64.5% and 50.9% for AP patients, which were significantly higher than those for BP patients (P<0.001). In CP patients, univariate analysis revealed that early treatment with imatinib, achieving CCyR within 12 months, additional cytogenetic abnormalities, and kinase domain mutations were associated with the treatment outcome. More patients are needed to carry out multivariate analysis.

关键词： imatinib     chronic myeloid leukemia     complete cytogenetic response    

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Projections of heat-related excess mortality in China due to climate change, population and aging

《环境科学与工程前沿（英文）》 2023年 第17卷 第11期 doi: 10.1007/s11783-023-1732-y

摘要：

● Four scenarios were used to project heat-related excess mortality in China.

关键词： Heat-related excess mortality     LMDI     Aging     YLL     VSLY    

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标题 作者 时间 类型 操作

Simulation of bubble column reactors using CFD coupled with a population balance model

Tiefeng WANG

期刊论文

Nonlinear sealing force of a seawater balance valve used in an 11000-meter manned submersible

期刊论文

Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

期刊论文

Optimization model for rotor blades of horizontal axis wind turbines

LIU Xiong, CHEN Yan, YE Zhiquan

期刊论文

Gut microbial balance and liver transplantation: alteration, management, and prediction

null

期刊论文

Quantitative analysis of yield and soil water balance for summer maize on the piedmont of the North China

Jingjing WANG,Feng HUANG,Baoguo LI

期刊论文

Analysis of catchment evapotranspiration at different scales using bottom-up and top-down approaches

Xiangyu XU, Dawen YANG,

期刊论文

Mass and heat balance calculations and economic evaluation of an innovative biomass pyrolysis project

Quanyuan WEI, Yongshui QU, Tianwei TAN

期刊论文

具有冗余结构的分布式数据库服务器及其负载平衡模型

田俊峰,刘玉玲,杜瑞忠

期刊论文

Effects of hydraulic retention time on nitrification activities and population dynamics of a conventional

Hongyan LI, Yu ZHANG, Min YANG, Yoichi KAMAGATA

期刊论文

Flow and mass balance analysis of eco-bio infiltration system

Marla C. MANIQUIZ, Lee-Hyung KIM, Soyoung LEE, Jiyeon CHOI

期刊论文

Socialized care services for the aged population: System construction and support measures

期刊论文

Obesity and overweight prevalence and its association with undiagnosed hypertension in Shanghai population, China: a cross-sectional population-based survey

null

期刊论文

Prognostic analysis of chronic myeloid leukemia in Chinese population in an imatinib era

null

期刊论文

Projections of heat-related excess mortality in China due to climate change, population and aging

期刊论文