资源类型

期刊论文 270

会议视频 12

会议专题 1

年份

2024 2

2023 28

2022 26

2021 26

2020 19

2019 14

2018 24

2017 18

2016 18

2015 18

2014 9

2013 5

2012 7

2011 7

2010 8

2009 6

2008 9

2007 10

2006 4

2005 4

展开 ︾

关键词

智能制造 4

生物工程 3

2022全球十大工程成就 2

2023全球十大工程成就 2

BP神经网络 2

人工智能 2

农业科学 2

加速遗传算法 2

实物期权 2

投资决策 2

抗击疫情 2

智能电网 2

粮食安全 2

运载系统 2

3D打印 1

5% 法 1

AFHW模型 1

BMI树脂 1

CAD 装配模型 1

展开 ︾

检索范围：

排序： 展示方式：

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    

HTML PDF 收藏

自上而下和自下而上相结合提高大规模生态修复规划的实用性和效率——来自社会-生态系统的启示 Article

Zhaowei Ding, Hua Zheng, Jun Wang, Patrick O´Connor, Cong Li, Xiaodong Chen, Ruonan Li, Zhiyun Ouyang

《工程（英文）》 2023年 第31卷 第12期   页码 50-58 doi: 10.1016/j.eng.2022.08.008

摘要：

Ecological restoration policies and their implementation are influenced by ecological and socioeconomic drivers. Top-down approach-based spatial planning, emphasizing hierarchical control within government structures, and without a comprehensive consideration of social–ecological interactions may result in implementation failure and low efficiency. Although many researchers have indicated the necessity to engage social–ecological interactions between stakeholders in effective planning processes, socioeconomic drivers of ecological restoration on a large scale are difficult to quantify because of data scarcity and knowledge limitations. Here, we established a new ecological restoration planning approach linking a social–ecological system framework to large-scale ecological restoration planning. The new spatial planning approach integrates bottom-up approaches targeting stakeholder interests and provides social considerations for stakeholder behavior analysis. Based on this approach, a meta-analysis is introduced to recognize key socioeconomic and social–ecological factors influencing large-scale ecological restoration implementation, and a stochastic model is constructed to analyze the impact of socioeconomic drivers on the behavior of authorities and participants on a large scale. We used the Yangtze River Basin-based Conversion of Cropland to Forest Program (CCFP), one of the largest payments for ecosystem service programs worldwide, to quantify the socioeconomic impacts of large-scale ecological restoration programs. Current CCFP planning without socioeconomic considerations failed to achieve large-scale program goals and showed low investment efficiency, with 19.71% of the implemented area reconverting to cropland after contract expiry. In contrast, spatial matching between planned and actual restoration increased from 61.55% to 81.86% when socioeconomic drivers were included. In addition, compared to that with the current CCFP implementation, the cost effectiveness of spatial planning with social considerations improved by 46.94%. Thus, spatial optimization planning that integrates both top-down and bottom-up approaches can result in more practical and effective ecological restoration than top-down approaches alone. Our new approach incorporates socioeconomic factors into large-scale ecological restoration planning with high practicality and efficiency.

关键词： Social-ecological system     Ecological restoration     Top-down approach     Bottom-up approach    

HTML PDF 收藏

Shanghai center project excavation induced ground surface movements and deformations

Guolin XU, Jiwen ZHANG, Huang LIU, Changqin REN

《结构与土木工程前沿（英文）》 2018年 第12卷 第1期   页码 26-43 doi: 10.1007/s11709-017-0439-1

摘要： Empirical data on deep urban excavations can provide designers a significant reference basis for assessing potential deformations of the deep excavations and their impact on adjacent structures. The construction of the Shanghai Center involved excavations in excess of 33-m-deep using the top-down method at a site underlain by thick deposits of marine soft clay. A retaining system was achieved by 50-m-deep diaphragm walls with six levels of struts. During construction, a comprehensive instrumentation program lasting 14 months was conducted to monitor the behaviors of this deep circular excavation. The following main items related to ground surface movements and deformations were collected: (1) walls and circumferential soils lateral movements; (2) peripheral soil deflection in layers and ground settlements; and (3) pit basal heave. The results from the field instrumentation showed that deflections of the site were strictly controlled and had no large movements that might lead to damage to the stability of the foundation pit. The field performance of another 21cylindrical excavations in top-down method were collected to compare with this case through statistical analysis. In addition, numerical analyses were conducted to compare with the observed data. The extensively monitored data are characterized and analyzed in this paper.

关键词： deep excavation     foundation pit     soft clay     top-down method     field observation     ground surface movements     ground deformations    

HTML PDF 收藏

Comparison of membrane fouling in ultrafiltration of down-flow and up-flow biological activated carbon

Lu Ao, Wenjun Liu, Yang Qiao, Cuiping Li, Xiaomao Wang

《环境科学与工程前沿（英文）》 2018年 第12卷 第6期 doi: 10.1007/s11783-018-1046-7

摘要：

The UF membrane fouling by down- and up-flow BAC effluents were compared.

Up-flow BAC effluent fouled the membrane faster than down-flow BAC effluent.

The combined effects dominated irreversible fouling.

The extent of fouling exacerbated by inorganic particles was higher.

关键词： Ultrafiltration     Membrane fouling     Down-flow biological activated carbon     Up-flow biological activated carbon     Particles     Polysaccharide    

HTML PDF 收藏

下降敲入续租期权定价研究

吴云,何建敏

《中国工程科学》 2004年 第6卷 第12期   页码 47-50

摘要：

阐述了现代租赁的基本内涵和实物期权的基本原理，提出了下降敲入续租期权定价模型及其定价求解，最后给出了算例分析。

关键词： 租赁     续租     租赁期权     实物期权     下降敲入期权    

HTML PDF 收藏

基因组测序成本将再次降低

Robert Pollie

《工程（英文）》 2023年 第23卷 第4期   页码 3-6 doi: 10.1016/j.eng.2023.02.002

HTML PDF 收藏

基于敲出障碍期权和博弈理论的项目投资决策分析

吴云,何建敏

《中国工程科学》 2005年 第7卷 第9期   页码 44-48

摘要：

阐述了实物期权的基本原理和敲出障碍期权的内涵及其定价求解，提出了基于敲出障碍期权的实物期权定价方法和博弈理论的项目投资决策分析，分析了双寡头市场结构下的项目投资决策，给出了算例分析。

关键词： 敲出障碍期权     实物期权     博弈理论     投资决策    

HTML PDF 收藏

Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

Tiebing CHEN, Yuwen ZHANG,

《机械工程前沿（英文）》 2010年 第5卷 第2期   页码 143-148 doi: 10.1007/s11465-010-0006-0

摘要： Selective laser sintering (SLS) of a two-component metal powder layer on the top of multiple sintered layers by a moving Gaussian laser beam is modeled. The loose metal powder layer is composed of a powder mixture with significantly different melting points. The physical model that accounts the shrinkage induced by melting is described by using a temperature-transforming model. The effects of the porosity and the thickness of the atop loose powder layer with different numbers of the existing sintered metal powder layers below on the sintering process are numerically investigated. The present work will provide a better understanding to simulate much more complicated three-dimensional SLS process.

关键词： laser     sintering     melting     solidification     heat transfer    

HTML PDF 收藏

The most influential “Top 10 Events” in carbon neutrality and climate change in 2022

《能源前沿（英文）》 2023年 第17卷 第1期   页码 1-4 doi: 10.1007/s11708-023-0869-5

摘要： . {{custom_ra.content}} . . . {{article.highlightEn}} . . . {{article.abstractEn}} . . . {{article.authorSummayEn}} .
HTML PDF 收藏

Erratum to: Folded down-conversion mixer for a 60 GHz receiver architecture in 65-nm CMOS technology

Najam Muhammad AMIN,Zhi-gong WANG,Zhi-qun LI

《信息与电子工程前沿（英文）》 2015年 第16卷 第5期 doi: 10.1631/FITEE.14e0087

HTML PDF 收藏

我国综采放顶煤开采技术及其展望

赵经彻

《中国工程科学》 2001年 第3卷 第4期   页码 9-16

摘要：

介绍了20世纪80年代中期以来对我国煤炭工业有重大影响的综采放顶煤开采技术的概况；论述了我国科技人员在该项技术进步中在顶煤可放性评价、岩（煤）运动规律及支架围岩关系、提高回收率的技术和工艺、安全控制、大功率成套设备研制等方面的创造性贡献；对综采放顶煤技术的发展趋势作出了评价。

关键词： 煤炭开采     综采放顶煤     顶板管理     资源回收率     煤矿安全    

HTML PDF 收藏

tertiary-air declination angle on combustion and steam temperature characteristics in a 350-MW supercritical down-fired

Xiaoguang LI, Lingyan ZENG, Hongye LIU, Yao LI, Yifu LI, Yunlong ZHAO, Bo JIAO, Minhang SONG, Shaofeng ZHANG, Zhichao CHEN, Zhengqi LI

《能源前沿（英文）》 2021年 第15卷 第1期   页码 132-142 doi: 10.1007/s11708-020-0803-z

摘要： Industrial-scale experiments were conducted to study the effects of tertiary air declination angle (TDA) on the coal combustion and steam temperature characteristics in the first 350-MW supercritical down-fired boiler in China with the multiple-injection and multiple-staging combustion (MIMSC) technology at medium and high loads. The experimental results indicated that as the TDA increased from 0° to 15°, the overall gas temperature in the lower furnace rose and the symmetry of temperature field was enhanced. The ignition distance of the fuel-rich coal/air flow decreased. In near-burner region, the concentration of O decreased while the concentrations of CO and NO increased. The concentration of NO decreased in near-tertiary-air region. The carbon in fly ash decreased significantly from 8.40% to 6.45% at a load of 260 MW. At a TDA of 15°, the ignition distances were the shortest (2.07 m and 1.73 m) at a load of 210 MW and 260 MW, respectively. The main and reheat steam temperatures were the highest (557.2°C and 559.4°C at a load of 210 MW, 558.4°C and 560.3°C at a load of 260 MW). The carbon in fly ash was the lowest (4.83%) at a load of 210 MW. On changing the TDA from 15° to 25°, the flame kernel was found to move downward and the main and reheat steam temperatures dropped obviously. The change of TDA has little effect on NO emissions(660–681 mg/m at 6% O ). In comprehensive consideration of the pulverized coal combustion characteristics and the unit economic performance, an optimal TDA of 15° is recommended.

关键词： supercritical down-fired boiler     industrial-scale experiment     tertiary air declination angle     coal combustion     steam temperature    

HTML PDF 收藏

Development of clean energy and environmental technologies to address humanity’s top problems

Geoff G. X. Wang

《化学科学与工程前沿（英文）》 2012年 第6卷 第1期   页码 1-2 doi: 10.1007/s11705-011-1145-5

HTML PDF 收藏

GENOME EDITING: A GROUND BREAKING RESEARCH HAS BEEN RANKED TOP 10 ENGINEERING FRONTS FROM 2017 TO 2021

《农业科学与工程前沿（英文）》 2022年 第9卷 第2期   页码 309-311 doi: 10.15302/J-FASE-2022440

HTML PDF 收藏

近六年《麻省理工科技评论》“全球十大突破性技术”解析与启示

屠海令,孙棕檀,姚源,徐源

《中国工程科学》 2017年 第19卷 第5期   页码 85-91 doi: 10.15302/J-SSCAE-2017.05.015

摘要：

《麻省理工科技评论》自2001年起每年发布“全球十大突破性技术”，关注技术的商业应用潜力及其对人类生活和社会的重大影响。本文从技术影响类型、技术领域等角度入手，对《麻省理工科技评论》近六年发布的60项突破性技术进行深入理解和分析，为准确把握未来产业动态和科技趋势提供借鉴。

关键词： 科技评论     “全球十大突破性技术”     商业     产业     社会    

HTML PDF 收藏

标题 作者 时间 类型 操作

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

Xiangyu XU, Dawen YANG,

期刊论文

自上而下和自下而上相结合提高大规模生态修复规划的实用性和效率——来自社会-生态系统的启示

Zhaowei Ding, Hua Zheng, Jun Wang, Patrick O´Connor, Cong Li, Xiaodong Chen, Ruonan Li, Zhiyun Ouyang

期刊论文

Shanghai center project excavation induced ground surface movements and deformations

Guolin XU, Jiwen ZHANG, Huang LIU, Changqin REN

期刊论文

Comparison of membrane fouling in ultrafiltration of down-flow and up-flow biological activated carbon

Lu Ao, Wenjun Liu, Yang Qiao, Cuiping Li, Xiaomao Wang

期刊论文

下降敲入续租期权定价研究

吴云,何建敏

期刊论文

基因组测序成本将再次降低

Robert Pollie

期刊论文

基于敲出障碍期权和博弈理论的项目投资决策分析

吴云,何建敏

期刊论文

Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

Tiebing CHEN, Yuwen ZHANG,

期刊论文

The most influential “Top 10 Events” in carbon neutrality and climate change in 2022

期刊论文

Erratum to: Folded down-conversion mixer for a 60 GHz receiver architecture in 65-nm CMOS technology

Najam Muhammad AMIN,Zhi-gong WANG,Zhi-qun LI

期刊论文

我国综采放顶煤开采技术及其展望

赵经彻

期刊论文

tertiary-air declination angle on combustion and steam temperature characteristics in a 350-MW supercritical down-fired

Xiaoguang LI, Lingyan ZENG, Hongye LIU, Yao LI, Yifu LI, Yunlong ZHAO, Bo JIAO, Minhang SONG, Shaofeng ZHANG, Zhichao CHEN, Zhengqi LI

期刊论文

Development of clean energy and environmental technologies to address humanity’s top problems

Geoff G. X. Wang

期刊论文

GENOME EDITING: A GROUND BREAKING RESEARCH HAS BEEN RANKED TOP 10 ENGINEERING FRONTS FROM 2017 TO 2021

期刊论文

近六年《麻省理工科技评论》“全球十大突破性技术”解析与启示

屠海令,孙棕檀,姚源,徐源

期刊论文