资源类型

期刊论文 119

会议视频 2

会议信息 1

年份

2023 11

2022 12

2021 8

2020 13

2019 13

2018 5

2017 6

2016 4

2015 2

2014 6

2013 4

2012 3

2011 6

2010 6

2009 1

2008 6

2007 7

2005 1

2004 1

2003 2

展开 ︾

关键词

3D打印 2

大地水准面 2

ADV 1

CAR设计 1

Caco-2细胞 1

Cas12a 1

GOCE 1

GRACE 1

Kdn 1

PIV 1

SAC 1

SINS/GNSS数据融合 1

TBM 1

Walsh循环谱 1

circRNA 1

一般方法论 1

万有引力定律 1

三峡 1

三维有限元分析 1

展开 ︾

检索范围：

排序： 展示方式：

How did Archimedes discover the law of buoyancy by experiment?

Hidetaka KUROKI

《机械工程前沿（英文）》 2016年 第11卷 第1期   页码 26-32 doi: 10.1007/s11465-016-0368-z

摘要：

After Archimedes and Vitruvius era, for more than 2000 years, it has been believed that the displaced water measurement of golden crown is impossible, and at his Eureka moment, Archimedes discovered the law of buoyancy (Proposition 7 of his principles) and proved the theft of a goldsmith by weighing the golden crown in water.

A previous study showed that a small amount of displaced water was able to be measured with enough accuracy by the introduced method. Archimedes measured the weight of displaced water. He did not find the law of buoyancy but rather specific gravity of things at the moment.

After which, Archimedes continued to measure the specific gravity of various solids and fluids. Through these measurements, he reached the discovery of the law of buoyancy directly by experiment. In this paper, the process to the discovery of Archimedes’ principle (Proposition 5) is presented.

关键词： Archimedes’ principle     buoyancy     specific gravity     Eureka     Vitruvius     displaced water     balance     floating body    

HTML PDF 收藏

High-gravity intensified iron-carbon micro-electrolysis for degradation of dinitrotoluene

《化学科学与工程前沿（英文）》 2023年 第17卷 第10期   页码 1595-1605 doi: 10.1007/s11705-022-2204-9

摘要： The application of iron–carbon (Fe–C) micro-electrolysis to wastewater treatment is limited by the passivation potential of the Fe–C packing. In order to address this problem, high-gravity intensified Fe–C micro-electrolysis was proposed in this study for degradation of dinitrotoluene wastewater in a rotating packed bed (RPB) using commercial Fe–C particles as the packing. The effects of reaction time, high-gravity factor, liquid flow rate and initial solution pH were investigated. The degradation intermediates were determined by gas chromatography-mass spectrometry, and the possible degradation pathways of nitro compounds by Fe–C micro-electrolysis in RPB were also proposed. It is found that under optimal conditions, the removal rate of nitro compounds reaches 68.4% at 100 min. The removal rate is maintained at approximately 68% after 4 cycles in RPB, but it is decreased substantially from 57.9% to 36.8% in a stirred tank reactor. This is because RPB can increase the specific surface area and the renewal of the liquid–solid interface, and as a result the degradation efficiency of Fe–C micro-electrolysis is improved and the active sites on the Fe–C surface can be regenerated for continuous use. In conclusion, high-gravity intensified Fe–C micro-electrolysis can weaken the passivation of Fe–C particles and extend their service life.

关键词： high-gravity technology     rotating packed bed     Fe–C micro-electrolysis     dinitrotoluene wastewater     active sites    

HTML PDF 收藏

卫星重力梯度数据用于精化地球重力场的研究

宁津生,罗志才,陈永奇

《中国工程科学》 2002年 第4卷 第7期   页码 23-28

摘要：

确定厘米级大地水准面和发展超高阶地球重力场模型是现代物理大地测量的主要科学目标之一。卫星重力梯度测量的实现将为这一目标做出重大贡献。文章着重评述这一领域的研究进展，并讨论利用卫星重力梯度数据精化地球重力场的若干理论和方法问题。

关键词： 卫星重力梯度测量     卫星重力梯度边值问题     地球重力场模型     大地水准面    

HTML PDF 收藏

Stability analysis on Tingzikou gravity dam along deep-seated weak planes during earthquake

Weiping HE, Yunlong HE

《结构与土木工程前沿（英文）》 2012年 第6卷 第1期   页码 69-75 doi: 10.1007/s11709-012-0146-x

摘要： The stability of a gravity dam against sliding along deep-seated weak planes is a universal and important problem encountered in the construction of dams. There is no recommended method for stability analysis of the dam on deep-seated weak planes under earthquake condition in Chinese design codes. Taking Tingzikou dam as an example, the research in this paper is focused on searching a proper way to evaluate the seismic safety of the dam against sliding along deep-seated weak planes and the probable failure modes of dam on deep-seated weak planes during earthquake. It is concluded that there are two probable failure modes of the dam along the main weak geological planes in the foundation. In the first mode, the concrete tooth under the dam will be cut and then the dam together with part foundation will slide along the muddy layer; in the second mode, the dam together with part foundation will slide along the path consist of the weak rock layer under the tooth and the muddy layer downstream the tooth. While there is no geological structure planes to form the second slip surface, the intersection of the main and the second slip surface is 40 to 80 m downstream from dam toe, and the angle between the second slip surface and the horizontal plane probably be 25 to 45 degrees.

关键词： gravity dam     deep-seated weak planes     stability against sliding     earthquake    

HTML PDF 收藏

A comprehensive simulation approach for pollutant bio-transformation in the gravity sewer

Nan Zhao, Huu Hao Ngo, Yuyou Li, Xiaochang Wang, Lei Yang, Pengkang Jin, Guangxi Sun

《环境科学与工程前沿（英文）》 2019年 第13卷 第4期 doi: 10.1007/s11783-019-1144-1

摘要：

A comprehensive pollutant transformation model for sewer systems is established.

The model comprises fermentation, sulfate reduction and ammonification processes.

Biochemical reactions related to distinct carbon sources are depicted in the model.

Pollutant transformation is attributed to different biochemical reaction processes.

关键词： Gravity sewer     Modeling     Pollutant transformation     Biochemical reaction process    

HTML PDF 收藏

Evaluation of seismic reliability of gravity dam-reservoir-inhomogeneous foundation coupled system

Hamid Taghavi GANJI, Mohammad ALEMBAGHERI, Mohammad Houshmand KHANEGHAHI

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 701-715 doi: 10.1007/s11709-018-0507-1

摘要： The seismic performance of gravity dam-reservoir-foundation coupled system is investigated utilizing probabilistic approach. In this research, the uncertainties associated with modeling parameters are incorporated in nonlinear response history simulations to realistically quantify their effects on the seismic performance of the system. The methodology is applied to Pine Flat gravity dam and the foundation is considered to be inhomogeneous assuming a constant spatial geometry but with various rock material properties. The sources of uncertainty are taken into account in the reliability analysis using Latin Hypercube Sampling procedure. The effects of the deconvolution process, number of samples, and foundation inhomogeneity are investigated.

关键词： gravity dams     dam-reservoir-foundation interaction     seismic reliability     inhomogeneous foundation     earthquake deconvolution    

HTML PDF 收藏

mechanism of nitrobenzene degradation by hydroxyl radicals-based ozonation process enhanced by high gravity

Weizhou Jiao, Shengjuan Shao, Peizhen Yang, Kechang Gao, Youzhi Liu

《化学科学与工程前沿（英文）》 2021年 第15卷 第5期   页码 1197-1205 doi: 10.1007/s11705-020-1998-6

摘要： This study investigated the indirect oxidation of nitrobenzene (NB) by hydroxyl radicals (·OH) in a rotating packed bed (RPB) using competitive kinetics method with -nitrochlorobenzene as a reference compound. The rate constants of NB with ·OH are calculated to be between (1.465±0.113) × 10 L/(mol·s) and (2.497±0.192) × 10 L/(mol·s). The experimental data are fitted by the modified Arrhenius equation, where the activation energy is 4877.74 J/mol, the order of NB concentration, rotation speed, and initial pH is 0.2425, 0.1400 and 0.0167, respectively. The ozonation process of NB could be enhanced by RPB, which is especially effective for highly concentrated NB-containing wastewater under alkaline conditions. The high gravity technology can accelerate ozone mass transfer and self-decomposition of ozone to produce more ·OH, resulting in an increase in the indirect oxidation rate of NB by ·OH and consequently effective degradation of NB in wastewater.

关键词： high gravity technology     hydroxyl radicals     nitrobenzene     reaction kinetics    

HTML PDF 收藏

Hazard potential of zones of weakness in gravity dams under impact loading conditions

Herbert LINSBAUER

《结构与土木工程前沿（英文）》 2011年 第5卷 第1期   页码 90-97 doi: 10.1007/s11709-010-0008-3

摘要： Dam constructions worldwide are designed and constructed in view of the strictest safety aspects for all static and dynamic load cases. As experience shows, however, formation of cracks in the “homogeneos concrete” as well as unsatisfactory compound behavior of lift joints are not to be excluded. These zones of weakness especially on the upstream side of the dam— exposed to high water pressure (static and dynamic)— represent an increased risk of safety. The main investigation, apart from the computation of the dynamic effects on the dam as a global structure, focuses on the stability analysis of a pressure-water filled crack configuration subjected to “dynamic loading” in the form of seismic action on the dam-reservoir-system and alternatively by “impact spot-loading” within sectors of the reservoir. A fracture mechanics based analysis shows an excessive potential of damage for the afflicted structure.

关键词： dam-reservoir     earthquake     impact     cracking     fracture mechanics    

HTML PDF 收藏

Earthquake analysis of arch and gravity dams including the effects of foundation inhomogeneity

LIN Gao, DU Jianguo, HU Zhiqiang

《结构与土木工程前沿（英文）》 2007年 第1卷 第1期   页码 41-50 doi: 10.1007/s11709-007-0004-4

摘要： Dam-foundation interaction plays an important role in the design of earthquake-resistant concrete arch and gravity dams. Geological conditions of the dam canyon are usually very complicated; however, in the literature, the damfoundation interaction analysis is often carried out based on the premise of a homogeneous unbounded foundation. In this paper, the effect of foundation inhomogeneity on the seismic response of arch and gravity dams was studied by means of scaled boundary finite element method (SBFEM). In order to satisfy the similarity requirement of SBFEM and simplify the computational effort, a subdomain approach and a conical representation of an unbounded foundation were proposed. The way of partitioning the domain and the selection of open angle and bottom radius of the cone model on the accuracy of the result were examined. Numerical examples show that the proposed approach is rational and efficient. Cases of foundation inhomogeneity with stiffness varying in accordance with an exponential function along the radial direction, and cases of foundation inhomogeneity with stiffness discontinuity and with weak interlayer strata on the earthquake response of concrete arch dams as well as gravity dams were analyzed. It was found that a homogeneous idealization of the unbounded foundation may sometimes greatly underestimate the maximum earthquake stress response of the dam. Therefore, taking into account the effect of foundation inhomogeneity for the earthquake safety assessment of concrete arch and gravity dams has great significance.

关键词： selection     interlayer     damfoundation interaction     Geological     computational    

HTML PDF 收藏

New method for efficient control of hydrogen sulfide and methane in gravity sewers: Combination of NaOH

《环境科学与工程前沿（英文）》 2022年 第16卷 第6期 doi: 10.1007/s11783-021-1509-0

摘要：

• The combination of NaOH and nitrite was used to control harmful gas in sewers.

关键词： Sewer corrosion     Sulfide control     Combination treatment     NaOH     Nitrite    

HTML PDF 收藏

Seismic analysis of semi-gravity RC cantilever retaining wall with TDA backfill

Il-Sang AHN, Lijuan CHENG

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 455-469 doi: 10.1007/s11709-017-0392-z

摘要： The seismic behavior of Tire Derived Aggregate (TDA) used as backfill material of 6.10 m high retaining walls was investigated based on nonlinear time-history Finite Element Analysis (FEA). The retaining walls were semi-gravity reinforced concrete cantilever type. In the backfill, a 2.74 m thick conventional soil layer was placed over a 3.06 m thick TDA layer. For comparison purpose, a conventional all soil-backfill model was also developed, and the analysis results from the two models under the Northridge and Takatori earthquakes were compared. The FEA results showed that both models did not experience major damage in the backfill under the Northridge earthquake. However, under the Takatori earthquake, the TDA-backfill model developed substantially large displacement in the retaining walls and in the backfill compared with the soil-backfill model. Regions of large plastic strain were mainly formed in the TDA layer, and the soil over the TDA layer did not experience such large plastic strain, suggesting less damage than the soil-backfill model. In addition, the acceleration on the backfill surface of the TDA-backfill model decreased substantially compared with the soil-backfill model. If an acceleration sensitive structure is placed on the surface of the backfill, the TDA backfill may induce less damage to it.

关键词： TDA (Tire Derived Aggregate)     scrap tires     retaining wall     seismic analysis     Finite Element Analysis    

HTML PDF 收藏

High-gravity-assisted emulsification for continuous preparation of waterborne polyurethane nanodispersion

Weihong Zhang, Dan Wang, Jie-Xin Wang, Yuan Pu, Jian-Feng Chen

《化学科学与工程前沿（英文）》 2020年 第14卷 第6期   页码 1087-1099 doi: 10.1007/s11705-019-1895-z

HTML PDF 收藏

Influence of sprinkler irrigation droplet diameter, application intensity and specific power on flower

Yisheng ZHANG, Delan ZHU

《农业科学与工程前沿（英文）》 2017年 第4卷 第2期   页码 165-171 doi: 10.15302/J-FASE-2017145

摘要： To determine the main parameters of droplet strike damage and avoid flower injury due to the unsuitable practices during sprinkler irrigation, an indoor experiment of irrigation droplet impact on cyclamen was conducted. The influences of different parameters such as droplet diameter, application intensity, specific power on flower strike damage was analyzed using Image Pro-Plus software to compute strike damage area and define damage level by sense-analysis. The results showed that a damage area of <1% represents a safe irrigation level, 1%–3% slight damage level, 3%–6% moderate damage level, and>6% heavy damage level. Equations of application intensity, specific power with sprinkler irrigation time and flower injury ratio were regressed against parameters which cause impact damages. The results indicated that specific power has a significant correlation with injury, and flower damage area increased as the increasing of the value of specific power for the same irrigation time. Application intensity was also correlated with injury when the droplet diameter was larger than 1 mm. When the duration of sprinkler irrigation was 1, 5 and 10 min, the threshold of impinging damage of application intensity was 25.30, 5.01 and 1.64 mm·h and the specific power was 0.467×10 , 9.340×10 and 3.110×10 W·m . These results provide a reference for determining the suitable values of sprinkler properties in operation design.

关键词： application intensity     damage     floriculture     flowers     specific power     sprinkler irrigation    

HTML PDF 收藏

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    

HTML PDF 收藏

Several issues to be considered for long-term better behavior of concrete gravity dams

Jinsheng JIA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第1期   页码 40-46 doi: 10.1007/s11709-010-0006-5

摘要： Along with economic, social quick development and urbanization, dams and reservoirs are of strategic importance for flood control, water supply, electricity production, irrigation, etc., both for developed countries and for developing countries. Climate change is a new challenging issue to be considered which will speed up the development of hydropower in developing countries. More and more attention will be paid on the long-term better behavior of dams to guarantee the safety of the people involved and the better development of the world. There are about 50000 old dams in the world and a lot of them have been completed and operated for more than 50 years. However, how do we evaluate the dams’ safety? How do we make the decision to do rehabilitation work or to rebuild a new dam based on evaluation results? The life span and the real safety status of old dams becomes a challenging task for the dam society, especially for China because it has more than 6000 dams to be evaluated and rehabilitated within the next few years. Based on the investigation of the Fengman gravity dam, which is 91.7 m high, operated since 1943 and suffered uplift pressure, freeze and thaw problems, etc., discussions on the life span evaluation of old concrete gravity dams have been made. The reasonable coefficient of dam safety has been discussed. The social decision for the final choice after comprehensive studies has been introduced.

关键词： dam safety     economic life span     structural life span     environmental life span     rehabilitation     social decision    

HTML PDF 收藏

标题 作者 时间 类型 操作

How did Archimedes discover the law of buoyancy by experiment?

Hidetaka KUROKI

期刊论文

High-gravity intensified iron-carbon micro-electrolysis for degradation of dinitrotoluene

期刊论文

卫星重力梯度数据用于精化地球重力场的研究

宁津生,罗志才,陈永奇

期刊论文

Stability analysis on Tingzikou gravity dam along deep-seated weak planes during earthquake

Weiping HE, Yunlong HE

期刊论文

A comprehensive simulation approach for pollutant bio-transformation in the gravity sewer

Nan Zhao, Huu Hao Ngo, Yuyou Li, Xiaochang Wang, Lei Yang, Pengkang Jin, Guangxi Sun

期刊论文

Evaluation of seismic reliability of gravity dam-reservoir-inhomogeneous foundation coupled system

Hamid Taghavi GANJI, Mohammad ALEMBAGHERI, Mohammad Houshmand KHANEGHAHI

期刊论文

mechanism of nitrobenzene degradation by hydroxyl radicals-based ozonation process enhanced by high gravity

Weizhou Jiao, Shengjuan Shao, Peizhen Yang, Kechang Gao, Youzhi Liu

期刊论文

Hazard potential of zones of weakness in gravity dams under impact loading conditions

Herbert LINSBAUER

期刊论文

Earthquake analysis of arch and gravity dams including the effects of foundation inhomogeneity

LIN Gao, DU Jianguo, HU Zhiqiang

期刊论文

New method for efficient control of hydrogen sulfide and methane in gravity sewers: Combination of NaOH

期刊论文

Seismic analysis of semi-gravity RC cantilever retaining wall with TDA backfill

Il-Sang AHN, Lijuan CHENG

期刊论文

High-gravity-assisted emulsification for continuous preparation of waterborne polyurethane nanodispersion

Weihong Zhang, Dan Wang, Jie-Xin Wang, Yuan Pu, Jian-Feng Chen

期刊论文

Influence of sprinkler irrigation droplet diameter, application intensity and specific power on flower

Yisheng ZHANG, Delan ZHU

期刊论文

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

期刊论文

Several issues to be considered for long-term better behavior of concrete gravity dams

Jinsheng JIA,

期刊论文