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优化 18

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Layout optimization of steel reinforcement in concrete structure using a truss-continuum model

《结构与土木工程前沿(英文)》 2023年 第17卷 第5期   页码 669-685 doi: 10.1007/s11709-023-0963-0

摘要: Owing to advancement in advanced manufacturing technology, the reinforcement design of concrete structures has become an important topic in structural engineering. Based on bi-directional evolutionary structural optimization (BESO), a new approach is developed in this study to optimize the reinforcement layout in steel-reinforced concrete (SRC) structures. This approach combines a minimum compliance objective function with a hybrid truss-continuum model. Furthermore, a modified bi-directional evolutionary structural optimization (M-BESO) method is proposed to control the level of tensile stress in concrete. To fully utilize the tensile strength of steel and the compressive strength of concrete, the optimization sensitivity of steel in a concrete–steel composite is integrated with the average normal stress of a neighboring concrete. To demonstrate the effectiveness of the proposed procedures, reinforcement layout optimizations of a simply supported beam, a corbel, and a wall with a window are conducted. Clear steel trajectories of SRC structures can be obtained using both methods. The area of ​​critical tensile stress in concrete yielded by the M-BESO is more than 40% lower than that yielded by the uniform design and BESO. Hence, the M-BESO facilitates a fully digital workflow that can be extremely effective for improving the design of steel reinforcements in concrete structures.

关键词: bi-directional evolutionary structural optimization     steel-reinforced concrete     concrete stress     reinforcement method     hybrid model    

Acoustic characteristics of bi-directional turbines for thermoacoustic generators

Dongdong LIU, Yanyan CHEN, Wei DAI, Ercang LUO

《能源前沿(英文)》 2022年 第16卷 第6期   页码 1027-1036 doi: 10.1007/s11708-020-0702-3

摘要: Bi-directional turbines combined with rotary motors may be a feasible option for developing high power thermoacoustic generators with low cost. A general expression for the acoustic characteristics of the bi-directional turbine was proposed based on theoretical derivation, which was validated by computational fluid dynamics modeling of an impulse turbine with fixed guide vanes. The structure of the turbine was optimized primarily using steady flow with an efficiency of near 70% (the shaft power divided by the total energy consumed by the turbine). The turbine in the oscillating flow was treated in a lumped-parameter model to extract the acoustic impedance characteristics from the simulation results. The key acoustic impedance characteristic of the turbine was the resistance and inertance due to complex flow condition in the turbine, whereas the capacitance was treated as an adiabatic case because of the large-scale flow channel relative to the heat penetration depth. Correlations for the impedance were obtained from both theoretical predictions and numerical fittings. The good fit of the correlations shows that these characteristics are valid for describing the bi-directional turbine, providing the basis for optimization of the coupling between the thermoacoustic engine and the turbine using quasi-one-dimensional theory in the frequency domain.

关键词: thermoacoustic power generator     acoustic characteristics     bi-directional impulse turbine     energy conversion    

A Bayesian modeling approach to bi-directional pedestrian flows in carnival events

S. Q. XIE, S. C. WONG, William H. K. LAM

《工程管理前沿(英文)》 2017年 第4卷 第4期   页码 483-489 doi: 10.15302/J-FEM-2017023

摘要: Bi-directional pedestrian flows are common at crosswalks, footpaths, and shopping areas. However, the properties of pedestrian movement may vary in urban areas according to the type of walking facility. In recent years, crowd movements at carnival events have attracted the attention of researchers. In contrast to pedestrian behavior in other walking facilities, pedestrians whose attention is attracted by carnival displays or activities may slow down and even stop walking. The Lunar New Year Market is a traditional carnival event in Hong Kong held annually one week before the Lunar New Year. During the said event, crowd movements can be easily identified, particularly in Victoria Park, where the largest Lunar New Year Market in Hong Kong is hosted. In this study, we conducted a video-based observational survey to collect pedestrian flow and speed data at the Victoria Park Lunar New Year Market on the eve of the Lunar New Year. Using the collected data, an extant mathematical model was calibrated to capture the relationships between the relevant macroscopic quantities, thereby providing insight into pedestrian behavior at the carnival event. Bayesian inference was employed to calibrate the model by using prior data obtained from a previous controlled experiment. Results obtained enhance our understanding of crowd behavior under different conditions at carnival events, thus facilitating the improvement of the safety and efficiency of similar events in the future.

关键词: pedestrian flow model     bi-directional interactions     empirical studies     Bayesian inference    

Technological development and engineering applications of novel steel-concrete composite structures

Jianguo NIE, Jiaji WANG, Shuangke GOU, Yaoyu ZHU, Jiansheng FAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 1-14 doi: 10.1007/s11709-019-0514-x

摘要:

In view of China’s development trend of green building and building industrialization, based on the emerging requirements of the structural engineering community, the development and proposition of novel resource-saving high-performance steel-concrete composite structural systems with adequate safety and durability has become a kernel development trend in structural engineering. This paper provides a state of the art review of China’s cutting-edge research and technologies in steel-concrete composite structures in recent years, including the building engineering, the bridge engineering and the special engineering. This paper summarizes the technical principles and applications of the long-span bi-directional composite structures, the long-span composite transfer structures, the comprehensive crack control technique based on uplift-restricted and slip-permitted (URSP) connectors, the steel plate concrete composite (SPCC) strengthen technique, and the innovative composite joints. By improving and revising traditional structure types, the comprehensive superiority of steel-concrete composite structures is well elicited. The research results also indicate that the high-performance steel-concrete composite structures have a promising popularizing prospect in the future.

关键词: high-performance composite structure     bi-directional composite     composite transfer     uplift-restricted and slip-permitted connectors     steel plate concrete composite strengthen    

Observation of a higher JAK2 V617F homozygous mutated clone in polycythemia vera compared to essential thrombocythemia

LIU Hongxing, TONG Chunrong, CAI Peng, GU Jiangying, LIN Yuehui, TENG Wen, WANG He, ZHANG Ying, ZHU Ping

《医学前沿(英文)》 2008年 第2卷 第3期   页码 309-313 doi: 10.1007/s11684-008-0059-1

摘要: Single-tube bi-directional allele specific amplification (SB-ASA) and real-time quantitative polymerase chain reaction (RQ-PCR) assays were developed and performed for JAK2V617F detection on 40 polycythemia vera (PV) samples, 31 essential thrombocythemia (ET) samples, 40 acute leukemia samples, and 40 healthy control samples. Differences between detect limitations of the two assays and their influence on the mutation detection rate were analyzed. The results showed that in some samples, the JAK2V617F burden was as low as nearly 1%, and thus more JAK2V617F-positive samples were detected by RQ-PCR than by SB-ASA assay due to the former higher detect limitation. Mutation allele ratios in PV and ET samples and their relevance to biological characteristics were also analyzed. The results showed that the mutation allele ratio was 0.436 ± 0.261 in PV, higher than the 0.216 ± 0.207 in ET; percentage of certainly homozygous mutation carriers in PV was 40.54%, higher than the 10% in ET. However, statistical analysis showed no relevance between mutation allele burden and sex or age. Our result shows that the pathogenesis of PV and ET may be related to the mutation allele burden of JAK2V617F.

关键词: specific amplification     essential thrombocythemia     Single-tube bi-directional     JAK2V617F-positive     JAK2V617F detection    

基于Spark面向分布式EEMDN-SABiGRU模型的乘客热点预测

夏大文,耿建,黄瑞曦,申冰琪,胡杨,李艳涛,李华青

《信息与电子工程前沿(英文)》 2023年 第24卷 第9期   页码 1316-1331 doi: 10.1631/FITEE.2200621

摘要: 针对出租车与乘客之间的供需不平衡问题,本文提出一种基于Spark的分布式归一化集合经验模态分解和面向空间注意力机制的双向门控循环单元(EEMDN-SABiGRU)模型,实现乘客热点的精准预测,旨在于降低盲目巡航开支、提高载客效率和实现收益最大化。首先,提出一种归一化的集合经验模态分解方法(EEMDN),处理网格中乘客热点数据,解决非平稳序列问题和数值差异过大造成的预测精度下降问题,避免EMD本征模态函数(IMF)存在的模态混叠现象。其次,构建一种基于乘客上下车热点的权重和乘客的空间规律性的空间注意力机制,捕捉每个网格中的乘客热点特征。再次,融合一种双向门控循环单元(GRU)算法,解决GRU仅能获取前向信息而忽略后向信息问题,提高特征提取的准确性。最后,在Spark并行计算框架下,采用真实的出租车GPS轨迹数据,基于EEMDN-SABiGRU模型实现了乘客热点的准确预测。实验结果表明,在00网格4个数据集上,与LSTM、EMDL-STM、EEMD-LSTM、GRU、EMD-GRU、EEMD-GRU、EMDN-GRU、CNN和BP相比,EEMDN-SABiGRU的平均绝对百分比误差、平均绝对误差、均方根误差和最大误差值分别降低了43.18%、44.91%、55.04%和39.33%。

关键词: 乘客热点预测     集合经验模态分解(EEMD)     空间注意力机制     双向门控循环单元(BiGRU)     GPS轨迹     Spark    

Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Mariana MORETTI, Emílio C. N. SILVA

《机械工程前沿(英文)》 2019年 第14卷 第2期   页码 190-200 doi: 10.1007/s11465-019-0537-y

摘要: In recent years, the new technologies and discoveries on manufacturing materials have encouraged researchers to investigate the appearance of material properties that are not naturally available. Materials featuring a specific stiffness, or structures that combine non-structural and structural functions are applied in the aerospace, electronics and medical industry fields. Particularly, structures designed for dynamic actuation with reduced vibration response are the focus of this work. The bi-material and multifunctional concepts are considered for the design of a controlled piezoelectric actuator with vibration suppression by means of the topology optimization method (TOM). The bi-material piezoelectric actuator (BPEA) has its metallic host layer designed by the TOM, which defines the structural function, and the electric function is given by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control (AVFC). The AVFC, provided by the piezoelectric layers, affects the structural damping of the system through the velocity state variables readings in time domain. The dynamic equation analyzed throughout the optimization procedure is fully elaborated and implemented. The dynamic response for the rectangular four-noded FE analysis is obtained by the Newmark’s time-integration method, which is applied to the physical and the adjoint systems, given that the adjoint formulation is needed for the sensitivity analysis. A gradient-based optimization method is applied to minimize the displacement energy output measured at a predefined degree-of-freedom of the BPEA when a transient mechanical load is applied. Results are obtained for different control gain values to evaluate their influence on the final topology.

关键词: topology optimization method     bi-material piezoactuator     active velocity feedback control     time-domain transient analysis     host structure design     vibration suppression    

多目标优化与决策问题的演化算法

谢涛,陈火旺

《中国工程科学》 2002年 第4卷 第2期   页码 59-68

摘要:

近年来,多目标优化与决策问题求解已成为演化计算的一个重要研究方向。为使演化算法的种群解 能尽快收敛并均匀分布于多目标问题的非劣最优域,多目标演化算法的研究热点集中在基于Pareto最优概念的 种群个体的比较与排序、适应值賦值与小生境技术等方面。介绍了多目标优化与决策技术的发展历史与分类方 法,分析了基于Pareto最优概念与不基于Pareto最优概念两大类的多目标演化算法,并详细比较与分析了几种 典型多目标演化算法。其次,论述了与多目标演化算法研究紧密相关的一些问题,如多目标问题解的性质,测 试函数集设计,算法性能评估技术,算法收敛性,并行实现以及实际多目标优化问题的处理等。

关键词: 演化计算     多目标优化与决策     Pareto最优    

粒子群优化算法综述

杨维,李歧强

《中国工程科学》 2004年 第6卷 第5期   页码 87-94

摘要:

粒子群优化(PSO)算法是一种新兴的优化技术,其思想来源于人工生命和演化计算理论。PSO通过粒子追随自己找到的最好解和整个群的最好解来完成优化。该算法简单易实现,可调参数少,已得到广泛研究和应用。详细介绍了PSO的基本原理、各种改进技术及其应用等,并对其未来的研究提出了一些建议。

关键词: 群体智能     演化算法     粒子群优化    

Evolutionary engineering of

Jixian GONG, Nan DUAN, Xueming ZHAO

《化学科学与工程前沿(英文)》 2012年 第6卷 第2期   页码 174-178 doi: 10.1007/s11705-012-1276-3

摘要: Evolutionary engineering is a novel whole-genome wide engineering strategy inspired by natural evolution for strain improvement. Astaxanthin has been widely used in cosmetics, pharmaceutical and health care food due to its capability of quenching active oxygen. Strain improvement of , one of the main sources for natural astaxanthin, is of commercial interest for astaxanthin production. In this study a selection procedure was developed for adaptive evolution of strains under endogenetic selective pressure induced by additive in environmental niches. Six agents, which can induce active oxygen in cells, were added to the culture medium respectively to produce selective pressure in process of evolution. The initial strain, 2-1557, was mutagenized to acquire the initial strain population, which was then cultivated for 550 h at selective pressure and the culture was transferred every 48h. Finally, six evolved strains were selected after 150 generations of evolution. The evolved strains produced up to 48.2% more astaxanthin than the initial strain. Our procedure may provide a promising alternative for improvement of high-production strain.

关键词: evolutionary engineering     astaxanthin     strain improvement    

Investigation of the structural form optimization methods of high-rise buildings

ZHANG Shihai, WANG Li, OU Jinping, WANG Guangyuan

《结构与土木工程前沿(英文)》 2007年 第1卷 第2期   页码 182-187 doi: 10.1007/s11709-007-0020-4

摘要: In this paper, the structural form optimization methods of high-rise buildings based on the expert system (ES), case-based reasoning (CBR), and knowledge discovery in database (KDD) are evaluated systematically. The characteristics and shortcomings of each method are pointed out. It is predicted that the incorporation of these three techniques into an intelligent form optimization method will be an important development direction in the future. Finally, the unified intelligent form selection model combined with concepts of ES, CBR, KDD and artificially intelligent beautification is proposed. In consideration of the needs of human beings, machinery and computation, the model has been used for structural design combined with relevant knowledge, means, maneuver and strategy. The model plays an important role and has practical value in the process of artificially intelligent form optimization. It effectively reduces the blindness and failure of computer-aided structural design.

关键词: case-based reasoning     computation     KDD     important development     high-rise    

Multidisciplinary co-design optimization of structural and control parameters for bucket wheel reclaimer

Yongliang YUAN, Liye LV, Shuo WANG, Xueguan SONG

《机械工程前沿(英文)》 2020年 第15卷 第3期   页码 406-416 doi: 10.1007/s11465-019-0578-2

摘要: Bucket wheel reclaimer (BWR) is an extremely complex engineering machine that involves multiple disciplines, such as structure, dynamics, and electromechanics. The conventional design strategy, namely, sequential strategy, is structural design followed by control optimization. However, the global optimal solution is difficult to achieve because of the discoordination of structural and control parameters. The co-design strategy is explored to address the aforementioned problem by combining the structural and control system design based on simultaneous dynamic optimization approach. The radial basis function model is applied for the planning of the rotation speed considering the relationships of subsystems to minimize the energy consumption per volume. Co-design strategy is implemented to resolve the optimization problem, and numerical results are compared with those of sequential strategy. The dynamic response of the BWR is also analyzed with different optimization strategies to evaluate the advantages of the strategies. Results indicate that co-design strategy not only can reduce the energy consumption of the BWR but also can achieve a smaller vibration amplitude than the sequential strategy.

关键词: bucket wheel reclaimer     co-design     energy-minimum optimization     sequential strategy    

Estimation of optimum design of structural systems via machine learning

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1441-1452 doi: 10.1007/s11709-021-0774-0

摘要: Three different structural engineering designs were investigated to determine optimum design variables, and then to estimate design parameters and the main objective function of designs directly, speedily, and effectively. Two different optimization operations were carried out: One used the harmony search (HS) algorithm, combining different ranges of both HS parameters and iteration with population numbers. The other used an estimation application that was done via artificial neural networks (ANN) to find out the estimated values of parameters. To explore the estimation success of ANN models, different test cases were proposed for the three structural designs. Outcomes of the study suggest that ANN estimation for structures is an effective, successful, and speedy tool to forecast and determine the real optimum results for any design model.

关键词: optimization     metaheuristic algorithms     harmony search     structural designs     machine learning     artificial neural networks    

Independent continuous and mapping method of structural topology optimization based on the global stress

Yunkang SUI, Jili FENG, Hongling YE, Xirong PENG,

《机械工程前沿(英文)》 2010年 第5卷 第2期   页码 130-142 doi: 10.1007/s11465-010-0011-3

摘要: There are three difficulties in topology optimization of continuum structures. 1) The topology under multiple load case is more difficult to be optimized than under single load case, because the former becomes a multiple objective based on compliance objective functions. 2) With local constraints, such as an elemental stress limit, the topology is more difficult to be solved than with global constraints, such as the displacement or frequency limits, because the sensitivity analysis of the former has very expensive computation. 3) With the phenomenon of load illness, which is similar with stiffness illness in the structural analysis, it is not easy to get the reasonable final topological structure, because it is difficult to consider different influences between the loads with small forces and big forces, and some topology paths of transferring small forces may disappear during the iteration process. To overcome difficulties above, four measures are adopted. 1) Topology optimization model is established by independent continuous mapping (ICM) method. 2) Based on the von Mises strength theory, all elements’ stress constraints are transformed into a structural energy constraint. 3) The phenomenon of load illness is divided to classify into three cases. 4) A strategy based on strain energy is proposed to adopt ICM method with stress globalization, and the problems of the above mentioned three cases of load illness are solved in terms of different complementary approaches. Several numerical examples show that the topology path of transferring forces can be obtained more easily by substituting global strain energy constraints for local stresses constraints, and the problem of load illness can be solved well by the weighting method that takes the structural energy as a weighting coefficient.

关键词: independent continuous mapping (ICM) method     global stresses constraints     topology optimization     continuum structure     load illness    

Multi-objective genetic algorithms based structural optimization and experimental investigation of the

Pengxing YI,Lijian DONG,Tielin SHI

《机械工程前沿(英文)》 2014年 第9卷 第4期   页码 354-367 doi: 10.1007/s11465-014-0319-5

摘要:

To improve the dynamic performance and reduce the weight of the planet carrier in wind turbine gearbox, a multi-objective optimization method, which is driven by the maximum deformation, the maximum stress and the minimum mass of the studied part, is proposed by combining the response surface method and genetic algorithms in this paper. Firstly, the design points’ distribution for the design variables of the planet carrier is established with the central composite design (CCD) method. Then, based on the computing results of finite element analysis (FEA), the response surface analysis is conducted to find out the proper sets of design variable values. And a multi-objective genetic algorithm (MOGA) is applied to determine the direction of optimization. As well, this method is applied to design and optimize the planet carrier in a 1.5 MW wind turbine gearbox, the results of which are validated by an experimental modal test. Compared with the original design, the mass and the stress of the optimized planet carrier are respectively reduced by 9.3% and 40%. Consequently, the cost of planet carrier is greatly reduced and its stability is also improved.

关键词: planet carrier     multi-objective optimization     genetic algorithms     wind turbine gearbox     modal experiment    

标题 作者 时间 类型 操作

Layout optimization of steel reinforcement in concrete structure using a truss-continuum model

期刊论文

Acoustic characteristics of bi-directional turbines for thermoacoustic generators

Dongdong LIU, Yanyan CHEN, Wei DAI, Ercang LUO

期刊论文

A Bayesian modeling approach to bi-directional pedestrian flows in carnival events

S. Q. XIE, S. C. WONG, William H. K. LAM

期刊论文

Technological development and engineering applications of novel steel-concrete composite structures

Jianguo NIE, Jiaji WANG, Shuangke GOU, Yaoyu ZHU, Jiansheng FAN

期刊论文

Observation of a higher JAK2 V617F homozygous mutated clone in polycythemia vera compared to essential thrombocythemia

LIU Hongxing, TONG Chunrong, CAI Peng, GU Jiangying, LIN Yuehui, TENG Wen, WANG He, ZHANG Ying, ZHU Ping

期刊论文

基于Spark面向分布式EEMDN-SABiGRU模型的乘客热点预测

夏大文,耿建,黄瑞曦,申冰琪,胡杨,李艳涛,李华青

期刊论文

Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Mariana MORETTI, Emílio C. N. SILVA

期刊论文

多目标优化与决策问题的演化算法

谢涛,陈火旺

期刊论文

粒子群优化算法综述

杨维,李歧强

期刊论文

Evolutionary engineering of

Jixian GONG, Nan DUAN, Xueming ZHAO

期刊论文

Investigation of the structural form optimization methods of high-rise buildings

ZHANG Shihai, WANG Li, OU Jinping, WANG Guangyuan

期刊论文

Multidisciplinary co-design optimization of structural and control parameters for bucket wheel reclaimer

Yongliang YUAN, Liye LV, Shuo WANG, Xueguan SONG

期刊论文

Estimation of optimum design of structural systems via machine learning

期刊论文

Independent continuous and mapping method of structural topology optimization based on the global stress

Yunkang SUI, Jili FENG, Hongling YE, Xirong PENG,

期刊论文

Multi-objective genetic algorithms based structural optimization and experimental investigation of the

Pengxing YI,Lijian DONG,Tielin SHI

期刊论文