资源类型

期刊论文 1504

会议视频 16

年份

2024 1

2023 111

2022 123

2021 118

2020 97

2019 89

2018 72

2017 70

2016 62

2015 75

2014 69

2013 54

2012 66

2011 56

2010 70

2009 73

2008 63

2007 61

2006 31

2005 31

展开 ︾

关键词

数学模型 13

数值模拟 9

模型试验 9

模型 7

COVID-19 5

能源 5

不确定性 4

GM(1 3

可持续发展 3

计算机模拟 3

1)模型 2

DX桩 2

D区 2

Preissmann格式 2

SARS 2

TRIZ 2

Weibull分布 2

k-ε模型 2

临震信号 2

展开 ︾

检索范围：

排序： 展示方式：

PM2.5 over North China based on MODIS AOD and effect of meteorological elements during 2003‒2015

Youfang Chen, Yimin Zhou, Xinyi Zhao

《环境科学与工程前沿（英文）》 2020年 第14卷 第2期 doi: 10.1007/s11783-019-1202-8

摘要： The Taihang Mountains was the boundary between high and low pollution areas. There were one high value center for PM2.5 pollution and two low value centers. In 2004, 2009 and after 2013, PM2.5 concentration was relatively low. Over the past 40 years, PM2.5 pollution in North China has become increasingly serious and progressively exposes the densely populated areas to pollutants. However, due to limited ground data, it is challenging to estimate accurate PM2.5 exposure levels, further making it unfavorable for the prediction and prevention of PM2.5 pollutions. This paper therefore uses the mixed effect model to estimate daily PM2.5 concentrations of North China between 2003 and 2015 with ground observation data and MODIS AOD satellite data. The tempo-spatial characteristics of PM2.5 and the influence of meteorological elements on PM2.5 is discussed with EOF and canonical correlation analysis respectively. Results show that overall R2 is 0.36 and the root mean squared predicted error was 30.1 μg/m3 for the model prediction. Our time series analysis showed that, the Taihang Mountains acted as a boundary between the high and low pollution areas in North China; while the northern part of Henan Province, the southern part of Hebei Province and the western part of Shandong Province were the most polluted areas. Although, in 2004, 2009 and dates after 2013, PM2.5 concentrations were relatively low. Meteorological/topography conditions, that include high surface humidity of area in the range of 34°‒40°N and 119°‒124°E, relatively low boundary layer heights, and southerly and easterly winds from the east and north area were common factors attributed to haze in the most polluted area. Overall, the spatial distribution of increasingly concentrated PM2.5 pollution in North China are consistent with the local emission level, unfavorable meteorological conditions and topographic changes.

关键词： Aerosol optical depth     PM2.5     MODIS     Mixed effect model     Canonical correlation analysis    

HTML PDF 收藏

A rain-on-snow mixed flood forecast model and its application

Jian WU, Lan LI,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 440-444 doi: 10.1007/s11709-009-0051-0

摘要： Based on summarizing the rule of rainstorm and snowmelt mixed flood, the structure of rain-on-snow runoff-generation is discussed; and critical temperature is used to determine the form of precipitation and snowmelt factor, taking into account rainfall volume of snowmelt. A rain-on-snow flood forecast model is developed by combining LL-Ⅰdistributed hydrology model. The Kalangguer River, an internal river in Xinjiang Autonomous Region, is taken for example. It is indicated that the model has a higher precision of forecasting; its determinacy coefficient is greater than 0.80.

关键词： Xinjiang Autonomous     forecasting     hydrology     temperature     rain-on-snow runoff-generation    

HTML PDF 收藏

Reconsideration on the effect of nitrogen on mixed culture polyhydroxyalkanoate production toward high

Zhiqiang Chen, Lizhi Zhao, Ye Ji, Qinxue Wen, Long Huang

《环境科学与工程前沿（英文）》 2019年 第13卷 第4期 doi: 10.1007/s11783-019-1135-2

摘要：

Effect of nitrogen on mixed culture PHA production was reconsidered.

Enrichment history of PHA accumulating culture was discussed.

Higher PHA content and biomass growth were achieved in presence of nitrogen.

Enrichment strategy toward higher PHA accumulation was investigated.

Microbial community succession in PHA accumulation phase was investigated.

关键词： Polyhydroxyalkanoate (PHA)     Organic loading rate     Nitrogen content     Biomass growth     Enrichment history    

HTML PDF 收藏

An assemble-to-order production planning with the integration of order scheduling and mixed-model sequencing

Baoxi WANG, Zailin GUAN, Yarong CHEN, Xinyu SHAO, Ming JIN, Chaoyong ZHANG

《机械工程前沿（英文）》 2013年 第8卷 第2期   页码 137-145 doi: 10.1007/s11465-013-0251-0

摘要：

For assemble-to-order enterprises, both order scheduling and mixed-model sequencing need to be taken into consideration in the formulation of order-oriented assembly plan. First, determining production priority for the received orders, and then conducting assembly sequence to the mixed-model products in each order. Order scheduling is aimed to ensure order delivery with the optimization goal of minimal total overdue time, while product sequencing is aimed to minimize the makespan so as to meet the requirement on completion time of the order. In the end, the paper establishes a mixed integer programming model based on an industrial case, and makes programming calculation with Xpress-MP to accomplish an order-oriented assembly plan conforming to actual production.

关键词： mixed-model assembly line     assemble-to-order     order scheduling     sequencing    

HTML PDF 收藏

Effects of nitrate concentration on biological hydrogen production by mixed cultures

Bo WANG, Wei WAN, Jianlong WANG,

《环境科学与工程前沿（英文）》 2009年 第3卷 第4期   页码 380-386 doi: 10.1007/s11783-009-0142-0

摘要： The effects of nitrate on fermentative hydrogen production and soluble metabolites from mixed cultures were investigated by varying nitrate concentrations from 0 to 10g N/L at 35°C with an initial pH of 7.0. The results showed that the substrate degradation rate, hydrogen production potential, hydrogen yield, and average hydrogen production rate initially increased with increasing nitrate concentrations from 0 to 0.1g N/L, while they decreased with increasing nitrate concentrations from 0.1 to 10g N/L. The maximum hydrogen production potential of 305.0mL, maximum hydrogen yield of 313.1mL/g glucose, and maximum average hydrogen production rate of 13.3mL/h were obtained at a nitrate concentration of 0.1g N/L. The soluble metabolites produced by the mixed cultures contained only ethanol and acetic acid (HAc) without propionic acid (HPr) and butyric acid (HBu). This study used the Modified Logistic model to describe the progress of cumulative hydrogen production in batch tests. A concise model was proposed to describe the effects of nitrate concentration on average hydrogen production rate.

关键词： nitrogen source     biohydrogen     fermentative hydrogen production     quantitative kinetic model    

HTML PDF 收藏

jet ignition of methane/air mixtures with multiple orifices in a large bore constant volume chamber: effectof air-fuel equivalence ratio and pre-mixed pressure

Xiang LI, Wenzheng ZHANG, Zhong HUANG, Dehao JU, Li HUANG, Mingzhi FENG, Xingcai LU, Zhen HUANG

《能源前沿（英文）》 2019年 第13卷 第3期   页码 483-493 doi: 10.1007/s11708-019-0631-1

摘要： Liquefied natural gas (LNG), mainly composed of methane, is in progress to substitute diesel fuel in heavy-duty marine engine for practical, economic, and environmental considerations. However, natural gas is relatively difficult to be ignited in a large bore combustion chamber. A combustion enhancement technique called pre-chamber turbulent jet ignition (TJI) can permit combustion and flame propagation in a large-bore volume. To investigate the effect of air-fuel equivalence ratio and pre-mixed pressure on pre-chamber TJI of methane/air mixtures with multiple orifices in a large bore volume, experimental tests and computational simulations were implemented to study the discharge of hot turbulent jets from six orifices of the pre-chamber. Different initial pressures and air-fuel equivalence ratios were considered to analyze the characteristics of TJI. The asymmetry of the turbulent jet actuated from six different orifices were found due to the asymmetric orientation of the spark plug, resulting in the inhomogeneous distribution of combustion in the constant volume chamber, which should be considered seriously in the marine engine design. Besides, as the premixed pressure increases, it has more effect on the flame propagation and plays a more important role, as it further increases.

关键词： marine engine     natural gas     methane     turbulent jet ignition (TJI)     pre-chamber    

HTML PDF 收藏

Direct energy rebound effect for road transportation in China

《工程管理前沿（英文）》   页码 597-611 doi: 10.1007/s42524-023-0276-y

摘要： The enhancement of energy efficiency stands as the principal avenue for attaining energy conservation and emissions reduction objectives within the realm of road transportation. Nevertheless, it is imperative to acknowledge that these objectives may, in part or in entirety, be offset by the phenomenon known as the energy rebound effect (ERE). To quantify the long-term EREs and short-term EREs specific to China’s road transportation, this study employed panel cointegration and panel error correction models, accounting for asymmetric price effects. The findings reveal the following: The long-term EREs observed in road passenger transportation and road freight transportation range from 13% to 25% and 14% to 48%, respectively; in contrast, the short-term EREs in road passenger transportation and road freight transportation span from 36% to 41% and 3.9% to 32%, respectively. It is noteworthy that the EREs associated with road passenger transportation and road freight transportation represent a partial rebound effect, falling short of reaching the magnitude of a counterproductive backfire effect. This leads to the inference that the upsurge in energy consumption within the road transportation sector cannot be solely attributed to advancements in energy efficiency. Instead, various factors, including income levels, the scale of commodity trade, and industrial structure, exert more substantial facilitating influences. Furthermore, the escalation of fuel prices fails to dampen the demand for energy services, whether in the domain of road passenger transportation or road freight transportation. In light of these conclusions, recommendations are proffered for the formulation of energy efficiency policies pertinent to road transportation.

关键词： road transportation     direct energy rebound effect     asymmetric price effects     panel data model    

HTML PDF 收藏

Effect of asphalt thin beams mixed with three nominal maximum aggregate sizes in the bending beam rheometer

Chun-Hsing HO,María Francisca Martínez GONZÁLEZ,Cristina Pilar Martín LINARES

《结构与土木工程前沿（英文）》 2017年 第11卷 第1期   页码 1-7 doi: 10.1007/s11709-016-0367-5

摘要： The objective of this research is to evaluate an impact of asphalt mixture beams with varying sizes of aggregate in the Bending Beam Rheometer (BBR) for testing/predicting thermal cracking properties of asphalt pavements. The BBR test has following benefits: the equipment is cheaper, it uses smaller specimens, faster conditioning, easier availability for quality control, easier to manage, etc. However some concerns have been raised: some consider that the size of the aggregate may affect the test’s results; the other concern is that such small beams cannot represent the whole properties of the asphalt pavement. To address these criticisms, imaging techniques, statistical analysis, and viscoelastic modeling are used. Asphalt thin beams prepared with three different nominal maximum aggregate size (NMAS) (12.5mm, 9.5 mm, and 4.75 mm) were tested at three different temperatures (-18°C, -24°C, and -30°C). Based on results from statistical analyses and viscoelasticity, the ratio of asphalt binders and voids and stiffness differences among the three NMAS specimens are not significant, meaning that the impact of asphalt thin beams prepared with the three NMAS on the prediction of thermal cracking is minimal and can be neglected.

关键词： bending beam rheometer     thin beams     thermal cracking    

HTML PDF 收藏

Iteration framework for solving mixed lubrication computation problems

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 635-648 doi: 10.1007/s11465-021-0632-8

摘要： The general discrete scheme of time-varying Reynolds equation loses the information of the previous step, which makes it unreasonable. A discretization formula of the Reynolds equation, which is based on the Crank–Nicolson method, is proposed considering the physical message of the previous step. Gauss–Seidel relaxation and distribution relaxation are adopted for the linear operators of pressure during the numerical solution procedure. In addition to the convergent criteria of pressure distribution and load, an estimation framework is developed to investigate the relative error of the most important term in the Reynolds equation. Smooth surface with full contacts and mixed elastohydrodynamic lubrication is tested for validation. The asperity contact and sinusoidal wavy surface are examined by the proposed discrete scheme. Results show the precipitous decline in the boundary of the contact area. The relative error suggests that the pressure distribution is reliable and reflects the accuracy and effectiveness of the developed method.

关键词： mixed lubrication     discretization formula     relative error     Reynolds equation     asperity    

HTML PDF 收藏

Perspective of mixed matrix membranes for carbon capture

Shinji Kanehashi, Colin A. Scholes

《化学科学与工程前沿（英文）》 2020年 第14卷 第3期   页码 460-469 doi: 10.1007/s11705-019-1881-5

摘要： Polymeric membrane-based gas separation has found wide applications in industry, such as carbon capture, hydrogen recovery, natural gas sweetening, as well as oxygen enrichment. Commercial gas separation membranes are required to have high gas permeability and selectivity, while being cost-effective to process. Mixed matrix membranes (MMMs) have a composite structure that consists of polymers and fillers, therefore featuring the advantages of both materials. Much effort has been made to improve the gas separation performance of MMMs as well as general membrane properties, such as mechanical strength and thermal stability. This perspective describes potential use of MMMs for carbon capture applications, explores their limitations in fabrication and methods to overcome them, and addresses their performance under industry gas conditions.

关键词： membranes     polymeric     mixed matrix     impurities    

HTML PDF 收藏

Effect of TiO

Navid Azizi, Mojgan Isanejad, Toraj Mohammadi, Reza M. Behbahani

《化学科学与工程前沿（英文）》 2019年 第13卷 第3期   页码 517-530 doi: 10.1007/s11705-018-1781-0

摘要： Membranes have attracted much attention as economical methods for industrial chemical processes. The effects of the titanium dioxide nanoparticle load on the morphology and CO /CH separation performance of poly (ether-block-amide) (PEBAX-1657) mixed matrix membranes (MMMs) were investigated from pressures of 3–12 bar and temperatures of 30°C–60°C. The PEBAX membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, atomic force microscopy and tensile strength analysis. The incorporation of TiO nanoparticles into the polymeric MMMs improved the CO /CH gas separation performance (both the permeability and selectivity) of the membranes. The CO permeability and ideal CO /CH selectivity values of the nanocomposite membrane loaded with 8 wt-% TiO were 172.32 Barrer and 24.79, respectively whereas those of the neat membrane were 129.87 Barrer and 21.39, respectively.

关键词： mixed matrix membrane     TiO2 nanoparticles     PEBAX-1657     CO2/CH4 separation    

HTML PDF 收藏

Experimental and kinetic study on laminar flame speeds of ammonia/syngas/air at a high temperature and elevated pressure

《能源前沿（英文）》 2022年 第16卷 第2期   页码 263-276 doi: 10.1007/s11708-021-0791-7

摘要： The laminar flame speeds of ammonia mixed with syngas at a high pressure, temperature, and different syngas ratios were measured. The data obtained were fitted at different pressures, temperatures, syngas ratios, and equivalence ratios. Four kinetic models (the Glarborg model, Shrestha model, Mei model, and Han model) were compared and validated with experimental data. Pathway, sensitivity and radical pool analysis are conducted to find out the deep kinetic insight on ammonia oxidation and NO formation. The pathway analysis shows that H abstraction reactions and NHi combination reactions play important roles in ammonia oxidation. NO formation is closely related to H, OH, the O radical produced, and formation reactions. NO is mainly formed from reaction, HNO+ H= NO+ H2. Furthermore, both ammonia oxidation and NO formation are sensitive to small radical reactions and ammonia related reactions.

关键词： ammonia mixed with syngas     laminar flame speed     kinetic model     sensitivity analysis     pathway analysis    

HTML PDF 收藏

Confining pressure effect on dynamic response of high rockfill dam

Xuexing CAO, Yunlong HE, Kun XIONG,

《结构与土木工程前沿（英文）》 2010年 第4卷 第1期   页码 116-126 doi: 10.1007/s11709-010-0014-5

摘要： Studies show that the dynamic properties of rockfill are strongly dependent on the confining pressure. Therefore, confining pressure effect has become a very important factor in the seismic analysis of high rockfill dam. The relationships of dynamic shear modulus versus dynamic shear strain and damping ratio versus dynamic shear strain had been improved to a certain degree on the basic of widely used Hardin-Drnevich constitutive model in this paper. Then a new model that could consider confining pressure effect has been established. Regression analysis was carried out of the dynamic triaxial experimental data of the damming materials in the Changheba hydropower station of Sichun Province, China. The results show that, the new model can fit the test data well under various confining pressures. A corresponding computational procedure was compiled and applied in the dynamic response analysis of the Changheba Dam. Comparing the calculation results between the new constitutive model and the ordinary Hardin-Drnevich model, it can be seen that the result is conservative to some extent without considering confining pressure effect.

关键词： confining pressure effect     high rockfill dam     dynamic response     Hardin-Drnevich constitutive model    

HTML PDF 收藏

new regeneration approach to cation resins with aluminum salts: application of desalination by its mixed

Zhigang LIU, Shaomin ZHU, Yansheng LI

《环境科学与工程前沿（英文）》 2012年 第6卷 第1期   页码 45-50 doi: 10.1007/s11783-010-0262-6

摘要： A novel method for the regeneration of cation exchange resins by aluminum (Al) salts was investigated in order to improve the regeneration efficiency of resins and reduce the dosage of regenerant. The influences of Al concentration and the pH of regeneration solution on resin transformation had been studied. The desalination experiments were carried out to evaluate the characteristics of the Al form resins. Experimental results showed that the regeneration rate of resins was strictly dependent on Al concentration and the pH of the solution. Compared to the conventional regeneration method, the Al form mixed bed exhibited the same desalination capability as the H form mixed bed (MB), and the total organic carbon (TOC) removal was up to 90%, clearly higher than that of the H form. Al salt solution could be utilized repeatedly to regenerate Al form resins.

关键词： aluminum (Al) form resins     desalination     mixed bed (MB)     regeneration    

HTML PDF 收藏

一种基于高斯过程与粒子群算法的CNN超参数自动搜索混合模型优化算法 Research Article

闫涵,仲崇权,吴玉虎,张立勇,卢伟

《信息与电子工程前沿（英文）》 2023年 第24卷 第11期   页码 1557-1573 doi: 10.1631/FITEE.2200515

摘要： 卷积神经网络（CNN）在许多实际应用领域中有着快速发展。然而，CNN性能很大程度上取决于其超参数，而为CNN配置合适的超参数通常面临着以下3个挑战：（1）不同类型CNN超参数的混合变量编码问题；（2）评估候选模型的昂贵计算成本问题；（3）确保搜索过程中收敛速率和模型性能问题。针对上述问题，提出一种基于高斯过程（GP）和粒子群优化算法（PSO）的混合模型优化算法（GPPSO），用于自动搜索最优的CNN超参数配置。首先，设计一种新的编码方法高效编码CNN中不同类型的超参数。其次，提出一种混合代理辅助（HSA）模型降低评估候选模型的高计算成本。最后，设计一种新的激活函数改善模型性能并确保收敛速率。在图像分类基准数据集上进行了大量实验，验证GPPSO优于最先进的方法。以金属断口诊断为例，验证GPPSO算法在实际应用中的有效性。实验结果表明，GPPSO仅需0.04和1.70 GPU天即可在CIFAR-10和CIFAR-100数据集上实现95.26％和76.36％识别准确率。

关键词： 卷积神经网络；高斯过程；混合模型；超参数优化；混合变量；粒子群优化    

HTML PDF 收藏

标题 作者 时间 类型 操作

PM2.5 over North China based on MODIS AOD and effect of meteorological elements during 2003‒2015

Youfang Chen, Yimin Zhou, Xinyi Zhao

期刊论文

A rain-on-snow mixed flood forecast model and its application

Jian WU, Lan LI,

期刊论文

Reconsideration on the effect of nitrogen on mixed culture polyhydroxyalkanoate production toward high

Zhiqiang Chen, Lizhi Zhao, Ye Ji, Qinxue Wen, Long Huang

期刊论文

An assemble-to-order production planning with the integration of order scheduling and mixed-model sequencing

Baoxi WANG, Zailin GUAN, Yarong CHEN, Xinyu SHAO, Ming JIN, Chaoyong ZHANG

期刊论文

Effects of nitrate concentration on biological hydrogen production by mixed cultures

Bo WANG, Wei WAN, Jianlong WANG,

期刊论文

jet ignition of methane/air mixtures with multiple orifices in a large bore constant volume chamber: effectof air-fuel equivalence ratio and pre-mixed pressure

Xiang LI, Wenzheng ZHANG, Zhong HUANG, Dehao JU, Li HUANG, Mingzhi FENG, Xingcai LU, Zhen HUANG

期刊论文

Direct energy rebound effect for road transportation in China

期刊论文

Effect of asphalt thin beams mixed with three nominal maximum aggregate sizes in the bending beam rheometer

Chun-Hsing HO,María Francisca Martínez GONZÁLEZ,Cristina Pilar Martín LINARES

期刊论文

Iteration framework for solving mixed lubrication computation problems

期刊论文

Perspective of mixed matrix membranes for carbon capture

Shinji Kanehashi, Colin A. Scholes

期刊论文

Effect of TiO

Navid Azizi, Mojgan Isanejad, Toraj Mohammadi, Reza M. Behbahani

期刊论文

Experimental and kinetic study on laminar flame speeds of ammonia/syngas/air at a high temperature and elevated pressure

期刊论文

Confining pressure effect on dynamic response of high rockfill dam

Xuexing CAO, Yunlong HE, Kun XIONG,

期刊论文

new regeneration approach to cation resins with aluminum salts: application of desalination by its mixed

Zhigang LIU, Shaomin ZHU, Yansheng LI

期刊论文

一种基于高斯过程与粒子群算法的CNN超参数自动搜索混合模型优化算法

闫涵,仲崇权,吴玉虎,张立勇,卢伟

期刊论文