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Robust optimization of the billet for isothermal local loading transitional region of a Ti-alloy rib-webcomponent based on dual-response surface method

Ke WEI, Xiaoguang FAN, Mei ZHAN, Miao MENG

《机械工程前沿(英文)》 2018年 第13卷 第3期   页码 376-384 doi: 10.1007/s11465-018-0500-3

摘要:

Billet optimization can greatly improve the forming quality of the transitional region in the isothermal local loading forming (ILLF) of large-scale Ti-alloy rib-web components. However, the final quality of the transitional region may be deteriorated by uncontrollable factors, such as the manufacturing tolerance of the preforming billet, fluctuation of the stroke length, and friction factor. Thus, a dual-response surface method (RSM)-based robust optimization of the billet was proposed to address the uncontrollable factors in transitional region of the ILLF. Given that the die underfilling and folding defect are two key factors that influence the forming quality of the transitional region, minimizing the mean and standard deviation of the die underfilling rate and avoiding folding defect were defined as the objective function and constraint condition in robust optimization. Then, the cross array design was constructed, a dual-RSM model was established for the mean and standard deviation of the die underfilling rate by considering the size parameters of the billet and uncontrollable factors. Subsequently, an optimum solution was derived to achieve the robust optimization of the billet. A case study on robust optimization was conducted. Good results were attained for improving the die filling and avoiding folding defect, suggesting that the robust optimization of the billet in the transitional region of the ILLF was efficient and reliable.

关键词: isothermal local loading forming     rib-web component     transitional region     robust optimization     dual response surface method    

Comparison of shallow tunneling method with pile and rib method for construction of subway station in

Sina AMIRI; Ali Naghi DEHGHAN

《结构与土木工程前沿(英文)》 2022年 第16卷 第6期   页码 704-717 doi: 10.1007/s11709-021-0746-4

摘要: In the present study, a comparison between the new shallow tunneling method (STM) and the traditional pile and rib method (PRM) was conducted to excavate and construct subway stations in the geological conditions of Tehran. First, by selecting Station Z6 located in the Tehran Subway Line 6 as a case study, the construction process was analyzed by PRM. The maximum ground settlement of 29.84 mm obtained from this method was related to the station axis, and it was within the allowable settlement limit of 30 mm. The acceptable agreement between the results of numerical modeling and instrumentation data indicated the confirmation and accuracy of the excavation and construction process of Station Z6 by PRM. In the next stage, based on the numerical model validated by instrumentation data, the value of the ground surface settlement was investigated during the station excavation and construction by STM. The results obtained from STM showed a significant reduction in the ground surface settlement compared to PRM. The maximum settlement obtained from STM was 6.09 mm as related to the front of the excavation face. Also, the sensitivity analysis results denoted that in addition to controlling the surface settlement by STM, it is possible to optimize some critical geometric parameters of the support system during the station excavation and construction.

关键词: shallow tunneling method     pile and rib method     ground surface settlement     subway station construction     numerical modeling    

Parametric equations for notch stress concentration factors of rib–deck welds under bending loading

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 595-608 doi: 10.1007/s11709-021-0720-1

摘要: The effective notch stress approach for evaluating the fatigue strength of rib–deck welds requires notch stress concentration factors obtained from complex finite element analysis. To improve the efficiency of the approach, the notch stress concentration factors for three typical fatigue-cracking modes (i.e., root–toe, root–deck, and toe–deck cracking modes) were thoroughly investigated in this study. First, we developed a model for investigating the effective notch stress in rib–deck welds. Then, we performed a parametric analysis to investigate the effects of multiple geometric parameters of a rib–deck weld on the notch stress concentration factors. On this basis, the multiple linear stepwise regression analysis was performed to obtain the optimal regression functions for predicting the notch stress concentration factors. Finally, we employed the proposed formulas in a case study. The notch stress concentration factors estimated from the developed formulas show agree well with the finite element analysis results. The results of the case study demonstrate the feasibility and reliability of the proposed formulas. It also shows that the fatigue design curve of FAT225 seems to be conservative for evaluating the fatigue strength of rib–deck welds.

关键词: notch stress concentration factor     rib–deck weld     parametric analysis     regression analysis     parametric equation    

Finite element analysis and structural design of pretensioned inverted T-beams with web openings

Hock Tian CHENG, Bashar S. MOHAMMED, Kamal Nasharuddin MUSTAPHA

《结构与土木工程前沿(英文)》 2009年 第3卷 第2期   页码 148-157 doi: 10.1007/s11709-009-0030-5

摘要: This paper presents the results of a research project aimed at providing standard circular web openings to the popular precast pretensioned inverted T-beam. Opening size and placement and required materials strengths were investigated. In this paper the nonlinear analysis and design of simply supported pretensioned inverted T-beam with circular web openings are presented. Two design parameters are varied: opening location and number of openings. The results from nonlinear finite element analysis were substantiated by test results from five pretensioned inverted T-beams with web opening and one solid beam. Good agreement is shown between the theoretical and the experimental results. The test results obtained from this investigation show that the performance of the specimens with web openings is almost identical to that of the specimen without web openings. A simple design method for pretensioned inverted T-beam with circular web openings is proposed.

关键词: prestressed concrete     inverted-T beam     web opening    

Torsional behavior of triangular web profile (TRIWP) steel section by experimental study

Fatimah DE’NAN,Hazwani HASAN,Mohd Hanim OSMAN,Sariffudin SAAD

《结构与土木工程前沿(英文)》 2016年 第10卷 第4期   页码 409-419 doi: 10.1007/s11709-016-0358-6

摘要: A triangular web profile (TriWP) is a modified section where the flanges are connected to a web plate of triangular profile. This study examined the torsional behavior of TriWP steel sections and compared to that of the flat web (FW) steel sections. Three types of specimen sizes were used: 180 mm × 75 mm × 5 mm × 2 mm, 200 mm × 100 mm × 8 mm × 6 mm, and 200 mm × 100 mm × 6 mm × 5 mm. All the specimens were loaded vertically until the maximum load was achieved and then the load was released. For both types of specimens, it was observed that the torsional rotation for bigger size [200 mm × 100 mm × 8 mm × 6 mm] were smaller than that of smaller size [180 mm × 75 mm × 5 mm × 2 mm] of the specimens. At the maximum torsional loading, the experimental result was compared to the theoretical calculation. The comparison showed that the percentage difference ranged from 1.10% to 16.80%. From the graph of torsional load versus rotational angle, the torsional rotation for all TriWP steel sections were smaller than that of the FW steel section under the same torsional loading i.e., 0.2 kNm and 1 kNm. The range between FW and TriWP were 3.74 to 71.83 at 0.2 kNm while 14.5 to 75.1 at 1.0 kNm. The findings were shown that the TriWP steel sections had better resistance against torsion in comparison to FW steel section.

关键词: corrugated web     i-beam     non uniform steel section     torsion resistance     torsion angle     triangular web profile steel section    

Predicting the capacity of perfobond rib shear connector using an ANN model and GSA method

Guorui SUN; Jun SHI; Yuang DENG

《结构与土木工程前沿(英文)》 2022年 第16卷 第10期   页码 1233-1248 doi: 10.1007/s11709-022-0878-1

摘要: Due to recent advances in the field of artificial neural networks (ANN) and the global sensitivity analysis (GSA) method, the application of these techniques in structural analysis has become feasible. A connector is an important part of a composite beam, and its shear strength can have a significant impact on structural design. In this paper, the shear performance of perfobond rib shear connectors (PRSCs) is predicted based on the back propagation (BP) ANN model, the Genetic Algorithm (GA) method and GSA method. A database was created using push-out test test and related references, where the input variables were based on different empirical formulas and the output variables were the corresponding shear strengths. The results predicted by the ANN models and empirical equations were compared, and the factors affecting shear strength were examined by the GSA method. The results show that the use of ANN model optimization by GA method has fewer errors compared to the empirical equations. Furthermore, penetrating reinforcement has the greatest sensitivity to shear performance, while the bonding force between steel plate and concrete has the least sensitivity to shear strength.

关键词: perfobond rib shear connector     shear strength     ANN model     global sensitivity analysis    

Experimental study on shear behavior of reinforced concrete beams with web horizontal reinforcement

Dong XU,Yu ZHAO,Chao LIU

《结构与土木工程前沿(英文)》 2014年 第8卷 第4期   页码 325-336 doi: 10.1007/s11709-014-0080-1

摘要: In determining the shear capacity of reinforced concrete beams, current codes do not provide any calculation method to evaluate the influence of web horizontal reinforcement, although they exist as structural reinforcements (or skin reinforcement). The present paper comprises results of 11 reinforced concrete beams in an effort to investigate the influence of web horizontal reinforcement on the shear behavior of reinforced concrete beams. The primary design variables are the shear-span-depth ratio, different reinforcement ratio of stirrups and web horizontal reinforcement. Influence of web horizontal reinforcement on crack patterns and failure mode was studied. It was found that web horizontal reinforcement can increase the shear capacity of the beams and restrain growth of inclined cracks effectively. Test results are very valuable, as very few references of shear tests can be found focusing on the effect of web horizontal reinforcement on the shear capacity of the beams.

关键词: reinforced concrete beam     shear strength     web horizontal reinforcement     experiments    

基于Web服务的分布式仿真系统的双重访问控制

陈学勤,吴慧中,朱耀琴

《中国工程科学》 2009年 第11卷 第8期   页码 72-78

摘要:

随着分布式仿真系统与Web服务技术的结合日益紧密,以及功能与资源分离的愈加明显,导致大量仿真资源暴露于网络中,传统、单一的访问控制模型已无法应对

关键词: Web服务安全     双重访问控制     分布式仿真系统    

An exploratory study for predicting component reliability with new load conditions

Zhengwei HU, Xiaoping DU

《机械工程前沿(英文)》 2019年 第14卷 第1期   页码 76-84 doi: 10.1007/s11465-018-0522-x

摘要: Reliability is important to design innovation. A new product should be not only innovative, but also reliable. For many existing components used in the new product, their reliability will change because the applied Loads are different from the ones for which the components are originally designed and manufactured. Then the new reliability must be re-evaluated. The system designers of the new product, however, may not have enough information to perform this task. With a beam problem as a case study, this study explores a feasible way to re-evaluate the component reliability with new Loads given the following information: The original reliability of the component with respect to the component Loads and the distributions of the new component Loads. Physics-based methods are employed to build the equivalent component limit-state function that can predict the component failure under the new Loads. Since the information is limited, the re-evaluated component reliability is given by its maximum and minimum values. The case study shows that good accuracy can be obtained even though the new reliability is provided with the aforementioned interval.

关键词: reliability     component     failure mode     prediction     random variable    

共享信息的第二类网络

李幼平

《中国工程科学》 2002年 第4卷 第8期   页码 8-11

摘要:

基于Internet的万维网是当代共享信息的原创网络(primary web) ,它是一种隐含冲突的系统,难以摆脱带宽瓶颈的困扰,不支持用户数量的自由增长。提出的第二类信息共享网络(secondary web),通过广播镜像把许多网站的完整内容收存于家庭,然后按内容的语义直接提取满足个性需求的读物。

关键词: 万维网     第二类共享网络     内容的语义     带宽瓶颈    

Ribbed strip rolling by three-dimensional finite element method combining extremely thin array of elements

Zhengyi JIANG,

《机械工程前沿(英文)》 2010年 第5卷 第1期   页码 52-60 doi: 10.1007/s11465-009-0087-9

摘要: In this paper, a three-dimensional finite element modelling of the ribbed strip rolling is carried out, coupling the use of an extremely thin array of elements that is equivalent to the calculation of the additional shear deformation work rate occurred by the velocity discontinuity in the roll bite. The formulation of the finite element modelling by adding a rib inclined contact surface boundary condition is derived, and the performance of the proposed method is conducted. The simulated rib height, forward slip, and the pulling down of rib height have been compared with the measured values and are in good agreement. The equivalent strain rate of the rib was obtained in the simulation. The effect of the rib inclined angle on pulling down of rib height has also been discussed, which is helpful in optimizing the design of the rib inclined angle.

关键词: rib inclined contact boundary condition     ribbed strip     extremely thin elements     pulling down of rib height     finite element modelling    

A sampling method based on URL clustering for fast web accessibility evaluation

Meng-ni ZHANG,Can WANG,Jia-jun BU,Zhi YU,Yu ZHOU,Chun CHEN

《信息与电子工程前沿(英文)》 2015年 第16卷 第6期   页码 449-456 doi: 10.1631/FITEE.1400377

摘要: When evaluating the accessibility of a large website, we rely on sampling methods to reduce the cost of evaluation. This may lead to a biased evaluation when the distribution of checkpoint violations in a website is skewed and the selected samples do not provide a good representation of the entire website. To improve sampling quality, stratified sampling methods first cluster web pages in a site and then draw samples from each cluster. In existing stratified sampling methods, however, all the pages in a website need to be analyzed for clustering, causing huge I/O and computation costs. To address this issue, we propose a novel page sampling method based on URL clustering for web accessibility evaluation, namely URLSamp. Using only the URL information for stratified page sampling, URLSamp can efficiently scale to large websites. Meanwhile, by exploiting similarities in URL patterns, URLSamp cluster pages by their generating scripts and can thus effectively detect accessibility problems from web page templates. We use a data set of 45 web sites to validate our method. Experimental results show that our URLSamp method is both effective and efficient for web accessibility evaluation.

关键词: Page sampling     URL clustering     Web accessibility evaluation    

An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercritical

TANG Renhu, YIN Fei, WANG Haijun, CHEN Tingkuan

《能源前沿(英文)》 2007年 第1卷 第3期   页码 300-304 doi: 10.1007/s11708-007-0043-5

摘要: Within the pressure range of 9–28 MPa, mass velocity range of 600–1 200 kg/(m · s), and heat flux range of 200–500 kW/m, experiments were performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with an inclined angle of 19.5 degrees, a maximum outer diameter of 38.1 mm, and a thickness of 7.5 mm. Based on the experiments, it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical pressure. However, the heat transfer enhancement decreased near the critical pressure. At supercritical pressure, the temperature difference between the wall and the fluid increased near the pseudo-critical temperature, but the increase of wall temperature was less than that of departure from nucleate boiling at sub-critical pressure. When pressure is closer to the critical pressure, the temperature difference between the wall and the fluid increased greatly near the pseudo-critical temperature. Heat transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat flux. Because the rotational flow of the internal groove reduced the effect of natural convection, the internal wall temperature of internally ribbed tube uniformly distributed along the circumference. The maximum internal wall temperature difference of the tube along the circumference was only 10 degrees when the fluid enthalpy exceeded 2 000 J/g. Considering the effect of acute variety of the fluid property on heat transfer, the correlation of heat transfer coefficient on the top of the internally ribbed tube was provided.

关键词: m ·     diameter     critical pressure     sub-critical pressure     maximum    

Improved resilience measure for component recovery priority in power grids

《工程管理前沿(英文)》 2021年 第8卷 第4期   页码 545-556 doi: 10.1007/s42524-021-0161-5

摘要: Given the complexity of power grids, the failure of any component may cause large-scale economic losses. Consequently, the quick recovery of power grids after disasters has become a new research direction. Considering the severity of power grid disasters, an improved power grid resilience measure and its corresponding importance measures are proposed. The recovery priority of failed components after a disaster is determined according to the influence of the failed components on the power grid resilience. Finally, based on the data from the 2019 Power Yearbook of each city in Shandong Province, China, the power grid resilience after a disaster is analyzed for two situations, namely, partial components failure and failure of all components. Result shows that the recovery priorities of components with different importance measures vary. The resilience evaluations under different repair conditions prove the feasibility of the proposed method.

关键词: resilience measure     power grid     importance measure     component recovery    

Ultimate load analysis of pretensioned inverted T-beams with circular web openings

Hock Tian CHENG , Bashar S. MOHAMMED , Kamal Nasharuddin MUSTAPHA ,

《结构与土木工程前沿(英文)》 2009年 第3卷 第3期   页码 262-271 doi: 10.1007/s11709-009-0031-4

摘要: The provision of transverse openings in floor beams to facilitate the passage of utility pipes and service ducts not only results in a more systematic layout of pipes and ducts, it also translates into substantial economic savings in the construction of a multi-storey building. In this paper, ultimate load analysis of statically loaded simply supported pretensioned inverted T-beams with circular web openings is presented. Major findings relevant to ultimate load analysis of pretensioned beams with circular web openings are summarized. An attempt has been made to answer the frequently asked questions related to ultimate load analysis on multiple circular web openings. It has been shown that the analysis method for pretensioned beams with multiple large circular web openings can be further simplified without sacrificing rationality.

关键词: pretensioned inverted T-beam     web opening    

标题 作者 时间 类型 操作

Robust optimization of the billet for isothermal local loading transitional region of a Ti-alloy rib-webcomponent based on dual-response surface method

Ke WEI, Xiaoguang FAN, Mei ZHAN, Miao MENG

期刊论文

Comparison of shallow tunneling method with pile and rib method for construction of subway station in

Sina AMIRI; Ali Naghi DEHGHAN

期刊论文

Parametric equations for notch stress concentration factors of rib–deck welds under bending loading

期刊论文

Finite element analysis and structural design of pretensioned inverted T-beams with web openings

Hock Tian CHENG, Bashar S. MOHAMMED, Kamal Nasharuddin MUSTAPHA

期刊论文

Torsional behavior of triangular web profile (TRIWP) steel section by experimental study

Fatimah DE’NAN,Hazwani HASAN,Mohd Hanim OSMAN,Sariffudin SAAD

期刊论文

Predicting the capacity of perfobond rib shear connector using an ANN model and GSA method

Guorui SUN; Jun SHI; Yuang DENG

期刊论文

Experimental study on shear behavior of reinforced concrete beams with web horizontal reinforcement

Dong XU,Yu ZHAO,Chao LIU

期刊论文

基于Web服务的分布式仿真系统的双重访问控制

陈学勤,吴慧中,朱耀琴

期刊论文

An exploratory study for predicting component reliability with new load conditions

Zhengwei HU, Xiaoping DU

期刊论文

共享信息的第二类网络

李幼平

期刊论文

Ribbed strip rolling by three-dimensional finite element method combining extremely thin array of elements

Zhengyi JIANG,

期刊论文

A sampling method based on URL clustering for fast web accessibility evaluation

Meng-ni ZHANG,Can WANG,Jia-jun BU,Zhi YU,Yu ZHOU,Chun CHEN

期刊论文

An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercritical

TANG Renhu, YIN Fei, WANG Haijun, CHEN Tingkuan

期刊论文

Improved resilience measure for component recovery priority in power grids

期刊论文

Ultimate load analysis of pretensioned inverted T-beams with circular web openings

Hock Tian CHENG , Bashar S. MOHAMMED , Kamal Nasharuddin MUSTAPHA ,

期刊论文