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A super-element approach for structural identification in time domain

LI Jie, ZHAO Xin

《机械工程前沿(英文)》 2006年 第1卷 第2期   页码 215-221 doi: 10.1007/s11465-006-0004-4

摘要: For most time-domain identification methods, a complete measurement for unique identification results is required for structural responses. However, the number of transducers is commonly far less than the number of structural degrees of freedom (DOFs) in practical applications, and thus make the time-domain identification methods rarely feasible for practical systems. A super-element approach is proposed in this study to identify the structural parameters of a large-scale structure in the time domain. The most interesting feature of the proposed super-element approach is its divide-and-conquer ability, which can be applied to identify large-scale structures using a relatively small number of transducers. The super-element model used for time domain identification is first discussed in this study. Then a parameterization procedure based on the sensitivities of response forces is introduced to establish the identification equations of super-elements. Some principles are suggested on effective decomposing of the whole structure into super-elements for identification purposes. Numerical simulations are conducted at the end of this study. The numerical results show that all structural parameters can be identified using a relatively small number of transducers, and the computational time can also be greatly shortened.

关键词: numerical     effective decomposing     parameterization procedure     divide-and-conquer ability     time-domain identification    

Topology optimization based on reduction methods with applications to multiscale design and additive manufacturing

Emmanuel TROMME, Atsushi KAWAMOTO, James K. GUEST

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 151-165 doi: 10.1007/s11465-019-0564-8

摘要: Advanced manufacturing processes such as additive manufacturing offer now the capability to control material placement at unprecedented length scales and thereby dramatically open up the design space. This includes the considerations of new component topologies as well as the architecture of material within a topology offering new paths to creating lighter and more efficient structures. Topology optimization is an ideal tool for navigating this multiscale design problem and leveraging the capabilities of advanced manufacturing technologies. However, the resulting design problem is computationally challenging as very fine discretizations are needed to capture all micro-structural details. In this paper, a method based on reduction techniques is proposed to perform efficiently topology optimization at multiple scales. This method solves the design problem without length scale separation, i.e., without iterating between the two scales. Ergo, connectivity between space-varying micro-structures is naturally ensured. Several design problems for various types of micro-structural periodicity are performed to illustrate the method, including applications to infill patterns in additive manufacturing.

关键词: multiscale topology optimization     micro-structure     additive manufacturing     reduction techniques     substructuring     static condensation     super-element    

Structure improvement and strength finite element analysis of VHP welded rotor of 700°C USC steam turbine

Jinyuan SHI,Zhicheng DENG,Yong WANG,Yu YANG

《能源前沿(英文)》 2016年 第10卷 第1期   页码 88-104 doi: 10.1007/s11708-015-0387-1

摘要: The optimized structure strength design and finite element analysis method for very high pressure (VHP) rotors of the 700°C ultra-super-critical (USC) steam turbine are presented. The main parameters of steam and the steam thermal parameters of blade stages of VHP welded rotors as well as the start and shutdown curves of the steam turbine are determined. The structure design feature, the mechanical models and the typical position of stress analysis of the VHP welded rotors are introduced. The steady and transient finite element analysis are implemented for steady condition, start and shutdown process, including steady rated condition, 110% rated speed, 120% rated speed, cold start, warm start, hot start, very hot start, sliding-pressure shutdown, normal shutdown and emergency shutdown, to obtain the temperature and stress distribution as well as the stress ratio of the welded rotor. The strength design criteria and strength analysis results of the welded rotor are given. The results show that the strength design of improved structure of the VHP welded rotor of the 700°C USC steam turbine is safe at the steady condition and during the transient start or shutdown process.

关键词: 700°C ultra-super-critical unit     steam turbine     very high pressure rotor     structure strength design     strength design criteria     finite element analysis    

Aerodynamic stability evolution tendency of suspension bridges with spans from 1000 to 5000 m

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0980-z

摘要: Aerodynamic instability owing to aerostatic and flutter-related failures is a significant concern in the wind-resistant design of long-span suspension bridges. Based on the dynamic characteristics of suspension bridges with spans ranging from 888 to 1991 m, we proposed fitted equations for increasing spans and base frequencies. Finite element models of suspension bridges with increasing span from 1000 to 5000 m were constructed. The structural parameters were optimized to follow the fitted tendencies. To analyze the aerodynamic instability, streamlined single-box section (SBS), lattice truss section (LTS), narrow slotted section (NSS), and wide slotted section (WSS) were considered. We performed three-dimensional (3-D) full-mode flutter analysis and nonlinear aerostatic instability analysis. The flutter critical wind speed continuously decreases with span growth, showing an unlimited approaching phenomenon. Regarding aerostatic instability, the instability wind speed decreases with span to approximately 3000 m, and increases when the span is in the range of 3000 to 5000 m. Minimum aerostatic instability wind speed with SBS or LTS girder would be lower than observed maximal gust wind speed, indicating the probability of aerostatic instability. This study proposes that suspension bridge with span approximately 3000 m should be focused on both aerostatic instability and flutter, and more aerodynamic configuration optimistic optimizations for flutter are essential for super long-span suspension bridges with spans longer than 3000 m.

关键词: suspension bridge     super long-span     finite element model     aerodynamic instability     aerodynamic configuration    

Breeding strategies for increasing yield potential in super hybrid rice

Shihua CHENG,Xiaodeng ZHAN,Liyong CAO

《农业科学与工程前沿(英文)》 2015年 第2卷 第4期   页码 277-282 doi: 10.15302/J-FASE-2015081

摘要: Super hybrid rice breeding is a new breeding method combining semi-dwarf breeding and heterosis breeding using germplasm and gene-environment interactions. This paper reviews the breeding strategies of super hybrid rice breeding in China, focusing on the utilization of heterosis of indica and japonica subspecies, construction of ideal plant architecture and pyramiding of disease resistant genes in restorer lines. To develop super hybrid rice, considerable effort should be made to explore genes related with high yield, good quality, resistance to pests and diseases, tolerance to stresses. Molecular breeding methods in combination with crossing techniques should be adopted in super hybrid rice breeding.

关键词: super hybrid rice     breeding strategies     yield potential    

Tool wear mechanisms in the machining of Nickel based super-alloys: A review

Waseem AKHTAR,Jianfei SUN,Pengfei SUN,Wuyi CHEN,Zawar SALEEM

《机械工程前沿(英文)》 2014年 第9卷 第2期   页码 106-119 doi: 10.1007/s11465-014-0301-2

摘要:

Nickel based super-alloys are widely employed in aircraft engines and gas turbines due to their high temperature strength, corrosion resistance and, excellent thermal fatigue properties. Conversely, these alloys are very difficult to machine and cause rapid wear of the cutting tool, frequent tool changes are thus required resulting in low economy of the machining process. This study provides a detailed review of the tool wear mechanism in the machining of nickel based super-alloys. Typical tool wear mechanisms found by different researchers are analyzed in order to find out the most prevalent wear mechanism affecting the tool life. The review of existing works has revealed interesting findings about the tool wear mechanisms in the machining of these alloys. Adhesion wear is found to be the main phenomenon leading to the cutting tool wear in this study.

关键词: tool wear     nickel based super-alloy     wear mechanism    

Sulige Gas Field super project

Wenrui HU, Jingwei BAO, Pengcheng JI

《工程管理前沿(英文)》 2017年 第4卷 第3期   页码 379-384 doi: 10.15302/J-FEM-2017107

Cross-stacked super-aligned carbon nanotube/activated carbon composite electrodes for efficient water

Min Li, Shuai Liang, Yang Wu, Meiyue Yang, Xia Huang

《环境科学与工程前沿(英文)》 2020年 第14卷 第6期 doi: 10.1007/s11783-020-1286-1

摘要: Abstract • A high-performance electrode was prepared with super-aligned carbon nanotubes. • SACNT/AC electrode achieved a ~100% increase in desalination capacity and rate. • SACNT/AC electrode achieved a ~26% increase in charge efficiency. • CUF process with SACNT/AC achieved an up to 2.43-fold fouling reduction. • SACNT/AC imparts overall improved water purification efficiency. The practical application of the capacitive deionization (CDI) enhanced ultrafiltration (CUF) technology is hampered due to low performance of electrodes. The current study demonstrated a novel super-aligned carbon nanotube (SACNT)/activated carbon (AC) composite electrode, which was prepared through coating AC on a cross-stacked SACNT film. The desalination capability and water purification performance of the prepared electrode were systematically investigated at different applied voltages (0.8–1.2 V) with a CDI system and a CUF system, respectively. In the CDI tests, as compared with the control AC electrode, the SACNT/AC electrode achieved an approximately 100% increase in both maximum salt adsorption capacity and average salt adsorption rate under all the applied voltage conditions, demonstrating a superior desalination capability. Meanwhile, a conspicuous increase by an average of ~26% in charge efficiency was also achieved at all the voltages. In the CUF tests, as compared with the control run at 0 V, the treatment runs at 0.8, 1.0, and 1.2 V achieved a 2.40-fold, 2.08-fold, and 2.43-fold reduction in membrane fouling (calculated according to the final transmembrane pressure (TMP) data at the end of every purification stage), respectively. The average TMP increasing rates at 0.8, 1.0, and 1.2 V were also roughly two times smaller than that at 0 V, indicating a dramatical reduction of membrane fouling. The SACNT/AC electrode also maintained its superior desalination capability in the CUF process, resulting in an overall improved water purification efficiency.

关键词: Carbon nanotube     Super aligned     Conductive membrane     Capacitive deionization     Ultrafiltration     Desalination    

Effective and selective separation of perrhenate from acidic wastewater by super-stable, superhydrophobic

《环境科学与工程前沿(英文)》 2022年 第16卷 第2期 doi: 10.1007/s11783-021-1456-9

摘要:

• A ZnO-biochar hybrid composite was prepared by solvothermal-pyrolysis synthesis.

关键词: Selectivity     Adsorption     Re(VII)     ZnO     Biochar    

Nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment

《环境科学与工程前沿(英文)》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1630-3

摘要:

● A novel nonpolar super-aligned carbon nanotube (SACNT) membrane was prepared.

关键词: Membrane fouling     Wastewater     Membrane separation     Antifouling     Aligned carbon nanotube    

Significant enhancement in catalytic ozonationefficacy: From granular to super-fine powdered activated

Tianyi Chen, Wancong Gu, Gen Li, Qiuying Wang, Peng Liang, Xiaoyuan Zhang, Xia Huang

《环境科学与工程前沿(英文)》 2018年 第12卷 第1期 doi: 10.1007/s11783-018-1022-2

摘要: In this study, super-fine powdered activated carbon (SPAC) hasbeen proposed and investigated as a novel catalyst for the catalyticozonation of oxalate for the first time. SPAC was prepared from commercialgranular activated carbon (GAC) by ball milling. SPAC exhibited highexternal surface area with a far greater member of meso- and macropores(563% increase in volume). The catalytic performances of activatedcarbons (ACs) of 8 sizes were compared and the rate constant for pseudofirst-order total organic carbon removal increased from 0.012 min to 0.568 min (47-fold increase) withthe decrease in size of AC from 20 to 40 mesh (863 mm) to SPAC (~1.0 mm). Furthermore, the diffusion resistance of SPAC decreased17-fold compared with GAC. The ratio of oxalate degradation by surfacereaction increased by 57%. The rate of transformationof ozone to radicals by SPAC was 330 times that of GAC. The resultssuggest that a series of changes stimulated by ball milling, includinga larger ratio of external surface area, less diffusion resistance,significant surface reaction and potential oxidized surface all contributedto enhancing catalytic ozonation performance. This study demonstratedthat SPAC is a simple and effective catalyst for enhancing catalyticozonation efficacy.

关键词: Super-fine activated carbon     Catalytic ozonation     External surface area     Surface reaction     Hydroxyl radical    

Structural design and mechanical responses of closely spaced super-span double tunnels in strongly weathered

Jiaxin HE; Shaohui HE; Xiabing LIU; Jinlei ZHENG

《结构与土木工程前沿(英文)》 2022年 第16卷 第6期   页码 685-703 doi: 10.1007/s11709-022-0824-2

摘要: This paper presents a study of closely spaced double tunnels in Taizhou, China. One is Xiabei Mountain No. 2 four-line super-span high-speed railway tunnel (HRT), and the other is Xiabei Mountain double-line large-span subway tunnel (ST). The excavation spans of HRT and ST are 26.3 and 14 m, respectively. The two tunnels are located at different levels, and their separating distance is 17.2 m. Due to the short construction period, the HRT excavation was completed earlier than ST. The structural design of the HRT, taking account of the disturbance by the ST construction, was analyzed by a numerical simulation. It was found that the “yielding principle” design was more feasible than the “resistance principle” design when considering the safety and durability of the HRT secondary lining. The mechanical responses of the HRT during ST construction were comprehensively monitored and analyzed, including the vault settlement, horizontal convergence, surrounding rock pressure, and the internal stress in shotcrete and steel arch. Results show that the longitudinal influence range of the ST construction on the HRT was approximately 0.6–1.1 times the ST outer diameter; the disturbance was mainly generated in the ST upper bench excavation; and the final axial force of the HRT shotcrete was approximately 9–16 times that of the steel arch, which indicated that the shotcrete was the main bearing structure. The safety status of the HRT was assessed based on the monitoring data, and the minimum safety factors of the HRT shotcrete and steel arch were 1.61 and 1.89, respectively. Parametric studies were performed to show how the lining stress of HRT was affected by the relative angle, pillar width, ST excavation method and excavation footage. Finally, the design and construction optimization were proposed according to the monitoring data and parameter analysis results. This study might provide practical reference for similar projects.

关键词: double tunnels     super-span     structural design     mechanical response     numerical simulation     field monitoring    

超大型沉井降排水下沉施工

夏国星,杜洪池

《中国工程科学》 2010年 第12卷 第4期   页码 25-28

摘要:

泰州大桥北锚碇沉井基础长67.9 m、宽52 m、高57 m,在沉井下沉的初期,采用降排水下沉。降排水下沉施工成本相比不排水下沉低,且下沉效率高,易控制,可形成良好的下沉导向,并确保沉井的下沉速度和精度,适宜在粉细砂、软塑性亚黏土等地质条件下采用。文章以泰州大桥北锚碇沉井基础为例,介绍了超大型沉井降排水施工的降排水下沉施工工艺。

关键词: 超大型沉井     降排水施工    

Ultra-precision ductile grinding of BK7 using super abrasive diamond wheel

ZHAO Qingliang, Brinksmeier Ekkard, Riemer Oltmann, Rickens Kai

《机械工程前沿(英文)》 2007年 第2卷 第3期   页码 350-355 doi: 10.1007/s11465-007-0061-3

摘要: In this paper, a novel conditioning technique using copper bonded diamond grinding wheels of 91 yD grain size and electrolytic in-process dressing (ELID) is first developed to precisely and effectively condition a nickel-electroplated monolayer coarse-grained diamond grinding wheel of 151 μm grain size. Under optimised conditioning parameters, the super abrasive diamond wheel was well conditioned in terms of a minimized run-out error and flattened diamond grain surfaces of constant peripheral envelope. The conditioning force was monitored by a force transducer, while the modified wheel surface status was in-situ monitored by a coaxial optical distance measurement system. Finally, the grinding experiment on BK7 was conducted using the well-conditioned wheel with the corresponding surface morphology and subsurface damage measured by atomic force microscope (AFM) and scanning electric microscope (SEM), respectively. The experimental result shows that the newly developed conditioning technique is applicable and feasible to ductile grinding optical glass featuring nano scale surface roughness, indicating the potential of super abrasive diamond wheels in ductile machining brittle materials.

关键词: ELID     peripheral     electrolytic in-process     nickel-electroplated monolayer     measurement    

Seismic analysis of a super high-rise steel structure with horizontal strengthened storeys

Yuanqing WANG, Hui ZHOU, Yongjiu SHI, Yi HUANG, Gang SHI, Siqing WEN

《结构与土木工程前沿(英文)》 2011年 第5卷 第3期   页码 394-404 doi: 10.1007/s11709-011-0116-8

摘要: Horizontal strengthened storeys are widely used in super high-rise steel structures to improve the lateral structural rigidity. This use has great effects on the seismic properties of the entire structure. The seismic properties of the Wuhan International Securities Building (a 68-storey super high-rise steel structure with three horizontal strengthened storeys) were evaluated in this study. Two approaches, i.e., mode-superposition response spectrum analysis and time-history analysis, were employed to calculate the seismic response of the structure. The response spectrum analysis indicated that transition parts near the three strengthened storeys were weak zones of the structure because of the abrupt change in rigidity. In the response spectrum analysis approach, the Square Root of Sum of Square (SRSS) method was recommended when the vertical seismic effects could be ignored. However, the complete quadratic combination (CQC) method was superior to SRSS method when the vertical seismic effects should be considered. With the aid of time-history analysis, the seismic responses of the structure were obtained. The whiplash effect that spectrum analysis cannot reveal was observed through time-history analysis. This study provides references for the seismic design of super high-rise steel structures with horizontal strengthened storeys.

关键词: seismic analysis     steel structure     super high-rise     horizontal strengthened storey     response spectrum analysis     time-history analysis    

标题 作者 时间 类型 操作

A super-element approach for structural identification in time domain

LI Jie, ZHAO Xin

期刊论文

Topology optimization based on reduction methods with applications to multiscale design and additive manufacturing

Emmanuel TROMME, Atsushi KAWAMOTO, James K. GUEST

期刊论文

Structure improvement and strength finite element analysis of VHP welded rotor of 700°C USC steam turbine

Jinyuan SHI,Zhicheng DENG,Yong WANG,Yu YANG

期刊论文

Aerodynamic stability evolution tendency of suspension bridges with spans from 1000 to 5000 m

期刊论文

Breeding strategies for increasing yield potential in super hybrid rice

Shihua CHENG,Xiaodeng ZHAN,Liyong CAO

期刊论文

Tool wear mechanisms in the machining of Nickel based super-alloys: A review

Waseem AKHTAR,Jianfei SUN,Pengfei SUN,Wuyi CHEN,Zawar SALEEM

期刊论文

Sulige Gas Field super project

Wenrui HU, Jingwei BAO, Pengcheng JI

期刊论文

Cross-stacked super-aligned carbon nanotube/activated carbon composite electrodes for efficient water

Min Li, Shuai Liang, Yang Wu, Meiyue Yang, Xia Huang

期刊论文

Effective and selective separation of perrhenate from acidic wastewater by super-stable, superhydrophobic

期刊论文

Nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment

期刊论文

Significant enhancement in catalytic ozonationefficacy: From granular to super-fine powdered activated

Tianyi Chen, Wancong Gu, Gen Li, Qiuying Wang, Peng Liang, Xiaoyuan Zhang, Xia Huang

期刊论文

Structural design and mechanical responses of closely spaced super-span double tunnels in strongly weathered

Jiaxin HE; Shaohui HE; Xiabing LIU; Jinlei ZHENG

期刊论文

超大型沉井降排水下沉施工

夏国星,杜洪池

期刊论文

Ultra-precision ductile grinding of BK7 using super abrasive diamond wheel

ZHAO Qingliang, Brinksmeier Ekkard, Riemer Oltmann, Rickens Kai

期刊论文

Seismic analysis of a super high-rise steel structure with horizontal strengthened storeys

Yuanqing WANG, Hui ZHOU, Yongjiu SHI, Yi HUANG, Gang SHI, Siqing WEN

期刊论文