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Progressive collapse of 2D reinforced concrete structures under sudden column removal

El Houcine MOURID, Said MAMOURI, Adnan IBRAHIMBEGOVIC

《结构与土木工程前沿(英文)》 2020年 第14卷 第6期   页码 1387-1402 doi: 10.1007/s11709-020-0645-0

摘要: Once a column in building is removed due to gas explosion, vehicle impact, terrorist attack, earthquake or any natural disaster, the loading supported by removed column transfers to neighboring structural elements. If these elements are unable to resist the supplementary loading, they continue to fail, which leads to progressive collapse of building. In this paper, an efficient strategy to model and simulate the progressive collapse of multi-story reinforced concrete structure under sudden column removal is presented. The strategy is subdivided into several connected steps including failure mechanism creation, MBS dynamic analysis and dynamic contact simulation, the latter is solved by using conserving/decaying scheme to handle the stiff nonlinear dynamic equations. The effect of gravity loads, structure-ground contact, and structure-structure contact are accounted for as well. The main novelty in this study consists in the introduction of failure function, and the proper manner to control the mechanism creation of a frame until its total failure. Moreover, this contribution pertains to a very thorough investigation of progressive collapse of the structure under sudden column removal. The proposed methodology is applied to a six-story frame, and many different progressive collapse scenarios are investigated. The results illustrate the efficiency of the proposed strategy.

关键词: failure mechanism     MBS dynamic analysis     gravity loads     structure-ground contact     structure-structure contact     energy conserving/decaying scheme    

Experimental study of wind loads on gable roofs of low-rise buildings with overhangs

Peng HUANG, Ling TAO, Ming GU, Yong QUAN

《结构与土木工程前沿(英文)》 2018年 第12卷 第3期   页码 300-317 doi: 10.1007/s11709-018-0449-7

摘要:

Gable roofs with overhangs (eaves) are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative (block) pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future’s modification of wind load codes.

关键词: low-rise building     gable roof     wind loads     wind tunnel test     block pressure coefficient     load code    

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    

Integration of renewable energies, flexible loads and storages into the German power grid: Actual situation

Harald SCHWARZ, Xiaoshu CAI

《能源前沿(英文)》 2017年 第11卷 第2期   页码 107-118 doi: 10.1007/s11708-017-0470-x

摘要: Starting from the late 1990’s, the German government decided to change the national electric power supply system dramatically. The main stimulating instrument was the German Law on Renewable Energies (Erneuerbare Energien Gesetz (EEG)), which guaranteed a fixed feed-in tariff to everyone who was willing to invest into renewable generation. Based on the year of commissioning, defined revenues per kWh were fixed for the next 20 years. Due to a very attractive over-funding, more than 1.5 million renewable generation units were connected to the German grid up to the end of 2015. According to the EEG, renewable generation units can feed to the grid wherever they are located and whenever they are able to produce. The old physical principle was and is still neglected, which clearly stated that generation always has to follow the demand—simply due to the limited availability of storages in the power system. Only in cases, when temporarily renewable overproduction exceeds the tolerable loading of lines or transformers respectively endangers the system stability in total, are German grid operators allowed to announce curtailments by emergency measures. Even in such cases, the “not produced energy” from renewable sources has to be funded. Although the installed capacity from renewables is much higher than the peak load in Germany, it contributes only about 32% to German average annual energy. Unfortunately, the regional distribution of renewable generation and load is very different, e.g. in the northeast of Germany, this Renewable Energy (RE)-ratio meanwhile exceeds 100% due to the high RE-penetration and low load. High transits of renewable overproduction from the north to the south will be necessary at nearly every day per year. Therefore, a tremendous change is needed within the German power grid. This paper will give a first overview followed by several others, describing possible solutions on how to overcome this critical situation.

关键词: grid integration     renewable energies     system stability     storages     flexible loads     new market design    

Possible role of power-to-heat and power-to-gas as flexible loads in German medium voltage networks

Mark KUPRAT, Martin BENDIG, Klaus PFEIFFER

《能源前沿(英文)》 2017年 第11卷 第2期   页码 135-145 doi: 10.1007/s11708-017-0472-8

摘要: Germany’s energy transition triggered a rapid and unilateral growth of renewable energy sources (RES) in the electricity sector. With increasing shares of intermittent RES, overcapacities during periods of strong wind and photovoltaic electricity generation occur. In the face of insufficient transmission capacities, due to an inhibited network extension, the electricity generation has to be curtailed. This curtailment of RES leads to economic losses and could be avoided through flexible loads. As an option to cope with those problems, the technologies of power-to-gas (PtG) and power-to-heat (PtH) are presented in this paper. First, the alkaline electrolyzer (AEL), polymer electrolyte membrane electrolyzer (PEMEL), and solid oxide electrolyzer cell (SOEC) are investigated regarding their operational parameters. Second, the electric boiler, electrode heating boiler, and heat pumps are considered. Ultimately, the network-supporting abilities and the potential to provide ancillary services, such as control power, load sequence operation, cold start and part load capability, are compared among one another.

关键词: power-to-gas     power-to-heat     flexible loads     ancillary services     coherent energy systems    

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    

Possible role of power-to-vehicle and vehicle-to-grid as storages and flexible loads in the German 110

Erik BLASIUS

《能源前沿(英文)》 2017年 第11卷 第2期   页码 146-154 doi: 10.1007/s11708-017-0475-5

摘要: The sectoral coupling of road traffic (in form of E-Mobility) and electrical energy supply (known as power-to-vehicle (P2V), vehicle-to-grid (V2G) is discussed as one of the possible development concepts for the flexible system integration of renewable energy sources (RES) and the support of the objectives of the German energy transition (aka. Energiewende). It is obvious that E-mobility, which shall produce as few emissions as possible, should be based on the exclusive use of renewable energies. At the same time, the E-mobility can help to reduce the negative effects of the grid integration of RES to the distribution grids. However, this assumes that the electric vehicles are smart integrated to the grids where they charge, meaning that they must be able to communicate and be controllable. Because per se unplanned and uncontrollable charging processes are harmful for the grid operation, especially if they occur frequently and unexpected in similar time periods, the effects can hardly be controlled and can lead to serious technical problems in practical grid operation. This paper provides an insight into the current development of E-mobility in Germany. The insight will be matched with the German development of the RES. By the combination of both sectors, the possible role of the E-mobility for the distribution grid will be depicted, which can have positive and negative aspects.

关键词: P2V     V2G     grid integration     electric vehicles     distribution grid    

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    

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    

Unified solution of limit loads of thick wall cylinder subject to external pressure considering strain

CHEN Changfu, XIAO Shujun, YANG Yu

《结构与土木工程前沿(英文)》 2007年 第1卷 第3期   页码 329-333 doi: 10.1007/s11709-007-0043-x

摘要: Based on the unified strength theory [1], a unified strength criterion for strain softening materials, such as concrete or rock, was derived, and the elastic and plastic limit loads of a thick-walled cylinder made of these materials subject to external pressure were also given. In addition, the influence of some factors on the limit loads of such cylinders as the ratio of the external radius to internal radius,/, the coefficient , which reflects the effect of medium principal stress and the normal stress of the relevant surface on the material destroy degree, the ratio of tensile strength to compressed strength of the material, , and the damage variable

Applications of thermostatically controlled loads for demand response with the proliferation of variable

Meng SONG, Wei SUN

《能源前沿(英文)》 2022年 第16卷 第1期   页码 64-73 doi: 10.1007/s11708-021-0732-5

摘要: More flexibility is desirable with the proliferation of variable renewable resources for balancing supply and demand in power systems. Thermostatically controlled loads (TCLs) attract tremendous attentions because of their specific thermal inertia capability in demand response (DR) programs. To effectively manage numerous and distributed TCLs, intermediate coordinators, e.g., aggregators, as a bridge between end users and dispatch operators are required to model and control TCLs for serving the grid. Specifically, intermediate coordinators get the access to fundamental models and response modes of TCLs, make control strategies, and distribute control signals to TCLs according the requirements of dispatch operators. On the other hand, intermediate coordinators also provide dispatch models that characterize the external characteristics of TCLs to dispatch operators for scheduling different resources. In this paper, the bottom-up key technologies of TCLs in DR programs based on the current research have been reviewed and compared, including fundamental models, response modes, control strategies, dispatch models and dispatch strategies of TCLs, as well as challenges and opportunities in future work.

关键词: thermostatically controlled load     demand response     renewable energy     power system operation    

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    

Stormwater runoff pollution loads from an urban catchment with rainy climate in China

Liqing LI, Baoqing SHAN, Chenqing YIN

《环境科学与工程前沿(英文)》 2012年 第6卷 第5期   页码 672-677 doi: 10.1007/s11783-012-0447-2

摘要: An older urban district in Wuhan, China, is transitioning from discharging sewage and stormwater directly into lakes, to directing the sewage to wastewater treatment plants (WWTPs). Dealing with polluted stormwater discharge is a great challenge. Stormwater runoff from an urban catchment with a combined sewer system was sampled and analyzed over a three-year period. Results indicate that wet weather flows account for 66%, 31%, 17%, and 13% of the total load of suspended solids (SS), chemical oxygen demand (COD), total nitrogen, and total phosphorus, respectively. The first flush of COD and SS was significant in all runoff events. More than 50% of the SS and COD loads were transported by the first 30% of runoff volume. Storage and treatment of the first 10 mm from each combined sewer overflow event could reduce more than 70% of the annual COD overflow load. An integrated solution is recommended, consisting of a tank connected to the WWTP and a detention pond, to store and treat the combined sewer overflow (CSO). These results may be helpful in mitigating CSO pollution for many other urban areas in China and other developing countries.

关键词: combined sewer overflow     pollution load     first flush     detention basins    

Numerical analysis of bearing behaviors of single batter piles under horizontal loads in various directions

《结构与土木工程前沿(英文)》 2023年 第17卷 第2期   页码 224-237 doi: 10.1007/s11709-022-0914-1

摘要: The horizontal bearing behavior of a single batter pile (SBP) is vital to its application in practical engineering; however, the horizontal responses of SBPs change with the directions of horizontal loads, and this phenomenon is rarely investigated. Therefore, the directional differences in the horizontal bearing behaviors of SBPs are investigated in this study. Four model tests are conducted to preliminarily examine the effects of the skew angle of horizontal loads on the horizontal bearing capacities and distributions of the bending moments of the SBPs. Subsequently, the differences in the responses of the SBPs under horizontal loads in various directions at full scale are analyzed comprehensively via finite-element (FE) analysis. The effects of the skew angle on SBP-soil interaction are discussed. Moreover, an empirical design method is proposed based on the FE analysis results to predict the bearing ratios of SBPs in medium-dense and dense sand while considering the effects of the skew angle, batter angle, and pile diameter. The method is confirmed to be effective, as confirmed by the close agreement between the predicting results with the model test (reported in this study) and centrifuge model test results (reported in the literature).

关键词: single batter pile     skew horizontal load     model test     finite-element analysis     empirical design method    

Enhanced methane production during long-term UASB operation at high organic loads as enabled by the immobilized

《环境科学与工程前沿(英文)》 2022年 第16卷 第6期 doi: 10.1007/s11783-021-1505-4

摘要:

• Fungi enable the constant UASB operation even at OLR of 25.0 kg/(m3×d).

关键词: Anaerobic digestion     Fungi     Methane production     High OLR     Microbial community    

标题 作者 时间 类型 操作

Progressive collapse of 2D reinforced concrete structures under sudden column removal

El Houcine MOURID, Said MAMOURI, Adnan IBRAHIMBEGOVIC

期刊论文

Experimental study of wind loads on gable roofs of low-rise buildings with overhangs

Peng HUANG, Ling TAO, Ming GU, Yong QUAN

期刊论文

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

期刊论文

Integration of renewable energies, flexible loads and storages into the German power grid: Actual situation

Harald SCHWARZ, Xiaoshu CAI

期刊论文

Possible role of power-to-heat and power-to-gas as flexible loads in German medium voltage networks

Mark KUPRAT, Martin BENDIG, Klaus PFEIFFER

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

Possible role of power-to-vehicle and vehicle-to-grid as storages and flexible loads in the German 110

Erik BLASIUS

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

Unified solution of limit loads of thick wall cylinder subject to external pressure considering strain

CHEN Changfu, XIAO Shujun, YANG Yu

期刊论文

Applications of thermostatically controlled loads for demand response with the proliferation of variable

Meng SONG, Wei 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

Stormwater runoff pollution loads from an urban catchment with rainy climate in China

Liqing LI, Baoqing SHAN, Chenqing YIN

期刊论文

Numerical analysis of bearing behaviors of single batter piles under horizontal loads in various directions

期刊论文

Enhanced methane production during long-term UASB operation at high organic loads as enabled by the immobilized

期刊论文