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Optimization of urban bus operation frequency under common route condition with rail transit

Bin YU, Sijia REN, Enze WU, Yifan ZHOU, Yunpeng WANG

《工程管理前沿（英文）》 2017年 第4卷 第4期   页码 451-462 doi: 10.15302/J-FEM-2017036

摘要： The overlap of bus and rail transit routes is common in China. This overlap provides passengers multiple choices for one trip. However, the availability of multiple options would cause uncertainty in the travel distribution of passengers. Given that buses and rail transits are becoming increasingly common, this paper aims to present the overlapped operation condition of bus and rail transit using a bi-level model from the perspective of bus operators. Frequency optimization model is established in the upper-level model. A heuristic algorithm called shuffled complex evolution (SCE-UA) method is used to solve the established frequency optimization model, and three other heuristic methods are compared with SCE-UA. A lower-level Logit model based on Agent simulation is set for traffic mode split. Data on the transit system in Dalian city are chosen as an example to test the feasibility of the model and the algorithm. Results show that as the overlapped optimization of bus route and rail transit routes changed primary bus frequency, the use of SCE-UA to solve such problems has evident advantages and feasibility; furthermore, changed bus frequency would improve bus operations.

关键词： common route     bus operation frequency     bi-level model     Agent simulation     SCE-UA algorithm    

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Leveraging individual-level data to advance air pollution health risk management

Jianxun YANG, Wenjing WU, Miaomiao LIU, Jun BI

《工程管理前沿（英文）》 2022年 第9卷 第2期   页码 337-342 doi: 10.1007/s42524-022-0189-1

摘要：

Environmental health risk management is a systematic engineering task, engaging multiple disciplines from the academic and government sectors. Reducing environmental health risks has become one of the key targets in the United Nations Sustainable Development Goals (SDGs). This target has been translated into public policies at many jurisdictional levels (Yue et al., 2020). To design region-specific and targeted policy initiatives, understanding how environmental health risks are spatially distributed and temporally resolved is fundamental.

Along with the advances in high-resolution pollution mapping and projection, environmental risk assessment and management have been performed at a highly granular scale (Caplin et al., 2019). For instance, taking advantage of the fine air pollution dataset, recent research efforts have evaluated the health burdens of historical air pollution exposure or cost-benefits of pollution control policies at finer-scale administrative units and grids (Liu et al., 2017; Ou et al., 2020). These assessments reveal expensive health costs of air pollution exposure and highlight that the health outcomes of air pollution are unevenly distributed across regions and more evident among vulnerable populations (Colmer et al., 2020).

Even though detailed geospatial mappings of air pollution capture local patterns, they do not necessarily represent individual-level unique exposure experiences and health outcomes. Personal exposure to air pollution can be influenced by a range of behavioral factors such as mobility patterns and self-protective actions (Tainio et al., 2021). Individual cofactors such as risk perceptions of air pollutants, baseline health conditions, and socio–economic status also influence the pollution-related health impacts (Piel et al., 2020). Dramatic variations in health risks, therefore, occur even within small spatial units such as blocks and neighborhoods. Thus, individual-level exposure and health assessment are critical in advancing the engineering management of air pollution at granular spatiotemporal scales and informing targeted local policies for reducing pollution-related health risks.

To perform air pollution health risk assessment and management at the individual level, first, gathering datasets relevant to personal exposure experiences and health outcomes is important. For example, portable sensor technology is widely applied, in which participants carry the sensors to measure their real-time locations and micro-environmental exposure (Su et al., 2017). These monitors can illustrate individual time–activity patterns and assess personal-specific pollution exposure during outdoor activities such as daily commuting and exercises (Dons et al., 2017). These activities finally form direct flows of datasets on human behaviors and are made available to researchers for more nuanced characterizations of environmental risk.

In this comment, we summarize different types of individual-level data and outline pathways through which the data may advance air pollution health risks assessment. We then review representative studies revolving around these aspects and showcase how abundant information at the individual level improves environmental health risk management. We finally detail the challenges and uncertainties in this rapidly growing field and highlight the priorities in future research. The aim is to motivate local policy actions and foster collective research efforts to promote public health.

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Rapid evaluation technology for CNC machine tool slide level based on built-in sensors

Yuqing ZHOU, Xuesong MEI, Gedong JIANG, Nuogang SUN,

《机械工程前沿（英文）》 2010年 第5卷 第1期   页码 79-86 doi: 10.1007/s11465-009-0070-5

摘要： Slide level impacts the CNC machine tool performance. The deterioration of slide level will result in the torsional vibration of a feed-axis control system and lower the CNC machine tool control precision. It is necessary to investigate the rapid evaluation technology for the slide level of a CNC machine tool. In this paper, a new type of rapid evaluation method for machine tool slide level is proposed, which uses the linear scale, motor encoder, and AC servo motor current/output torque. To acquire level information, the built-in sensors test principle is profoundly investigated, and the mathematical model between the slide level and the measured data is established. In addition, two different level identification methods are comparatively analyzed. The analysis results of experiments show that it is simple, rapid, feasible, and reliable to use built-in sensors information for evaluating slide level.

关键词： slide level     built-in sensors     Stribeck effect     model identification    

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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    

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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    

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M-LFM: a multi-level fusion modeling method for shape−performance integrated digital twin of complex

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0708-0

摘要： As a virtual representation of a specific physical asset, the digital twin has great potential for realizing the life cycle maintenance management of a dynamic system. Nevertheless, the dynamic stress concentration is generated since the state of the dynamic system changes over time. This generation of dynamic stress concentration has hindered the exploitation of the digital twin to reflect the dynamic behaviors of systems in practical engineering applications. In this context, this paper is interested in achieving real-time performance prediction of dynamic systems by developing a new digital twin framework that includes simulation data, measuring data, multi-level fusion modeling (M-LFM), visualization techniques, and fatigue analysis. To leverage its capacity, the M-LFM method combines the advantages of different surrogate models and integrates simulation and measured data, which can improve the prediction accuracy of dynamic stress concentration. A telescopic boom crane is used as an example to verify the proposed framework for stress prediction and fatigue analysis of the complex dynamic system. The results show that the M-LFM method has better performance in the computational efficiency and calculation accuracy of the stress prediction compared with the polynomial response surface method and the kriging method. In other words, the proposed framework can leverage the advantages of digital twins in a dynamic system: damage monitoring, safety assessment, and other aspects and then promote the development of digital twins in industrial fields.

关键词： shape−performance integrated digital twin (SPI-DT)     multi-level fusion modeling (M-LFM)     surrogate model     telescopic boom crane     data fusion    

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Isogeometric analysis based on geometric reconstruction models

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 782-797 doi: 10.1007/s11465-021-0648-0

摘要： In isogeometric analysis (IGA), the boundary representation of computer-aided design (CAD) and the tensor-product non-uniform rational B-spline structure make the analysis of three-dimensional (3D) problems with irregular geometries difficult. In this paper, an IGA method for complex models is presented by reconstructing analysis-suitable models. The CAD model is represented by boundary polygons or point cloud and is embedded into a regular background grid, and a model reconstruction method is proposed to obtain the level set function of the approximate model, which can be directly used in IGA. Three 3D examples are used to test the proposed method, and the results demonstrate that the proposed method can deal with complex engineering parts reconstructed by boundary polygons or point clouds.

关键词： isogeometric analysis     reconstruction model     level set function     trimmed element     point cloud    

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Development of a constitutive model for rockfills and similar granular materials based on the disturbed

Mehdi VEISKARAMI, Ali GHORBANI, Mohammadreza ALAVIPOUR

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 365-378 doi: 10.1007/s11709-012-0178-2

摘要： Behavior of rockfills was investigated experimentally and theoretically. A series of standard triaxial compression tests were carried out on a quarried rockfill material at different stress levels. It was found that both the stress level and the shear stress ratio, like most of granular materials, controls the behavior of rockfill materials. At lower shear stress ratios the behavior is much more similar to a nonlinear elastic solid. When the shear stress goes further, the stress-strain curve shows an elasto-plastic behavior which suggests using the disturbed state concept to develop a constitutive model to predict the stress-strain behavior. The presented constitutive model complies reasonably with the experimental data.

关键词： constitutive model     granular material     rockfill     plasticity     disturbed state concept     stress level    

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一种适用于自动驾驶汽车的多层地图模型和车道级轨迹规划 Article

江昆, 杨殿阁, 柳超然, 张涛, 肖中阳

《工程（英文）》 2019年 第5卷 第2期   页码 305-318 doi: 10.1016/j.eng.2018.11.032

摘要：

越来越多的司机依赖于汽车或手机上的电子地图导航系统来选择最佳的驾驶路线，以节省时间和提高安全性，在不久的将来，电子地图和导航系统有望在未来交通运输系统中发挥更大的作用。为了将现有的导航系统扩展到更多的应用领域，如自动驾驶，需要考虑在传统道路地图模型的基础上，建立车道级地图模型和车道级轨迹规划。本研究针对传统电子地图内容不够丰富的局限性，提出了一种全新的七层自动驾驶地图结构模型，并将它命名为清华地图模型。考虑车辆换道、转向和直行等不同行车特点，建立了车道级路段行车代价模型，建立一种分层路径轨迹搜索方法，能够在道路和车道网络中实现快速的轨迹规划，能够很好地支持自动驾驶的车道级轨迹规划。通过在虚拟道路网络和实际道路网络上的测试，充分验证了该地图模型和算法的灵活性和有效性。

关键词： 车道级地图     路径规划     清华地图模型     行车代价模型    

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Cleaning the energy sources for water heating among Nanjing households: barriers and opportunities for solar and natural gas

Lingyun ZHU,Beibei LIU,Jun BI

《环境科学与工程前沿（英文）》 2014年 第8卷 第5期   页码 757-766 doi: 10.1007/s11783-013-0603-3

摘要： Energy for water heating accounts for an increasing part in residential energy demand in China. An extensive survey was conducted to analyze the determinants of household energy choices for water heaters among residents in Nanjing, China. Two sets of variables were examined as potential influences: building features and household socio-economic characteristics. Results suggest that building features such as gas availability and building structures, and household characteristics such as household head’s education degree and energy-conserving sense are crucial determinants in choosing natural gas as water heater energy. Installation permission for solar water heater, building stories, and residential location serve as determining factors in choosing solar water heaters. Based on these, barriers and opportunities are discussed for transitions toward cleaner water heating energies, and suggestions are given for local governments to promote cleaner energy replacement in China.

关键词： residential energy demand     water heating     multinomial logit model    

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基于位平面可预测性的无损图像压缩研究

厉鲁卫,周朔燕,蔡益宇

《中国工程科学》 2005年 第7卷 第10期   页码 33-37

摘要：

提出了一种基于嵌入式位平面的静止连续色调图像的无损图像压缩方法：通过将1幅图像分割成两类位平面（基础层和增强层）使得该图像具有了位平面的可测量性，并且通过利用平面与平面以及每个平面中各像素之间的相关性减少冗余，从而获得优秀的压缩性能；与其他压缩算法的比较表明，基于嵌入式位平面的无损图像压缩算法由于具有位平面可测量性而体现了巨大的优越性。

关键词： 信息处理技术     无损图像压缩     上下图模型     嵌入式位平面    

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平朔东露天煤矿工业场地地下水位变化影响因素分析

林杜军,宫守才,张银洲

《中国工程科学》 2012年 第14卷 第2期   页码 49-53

摘要：

在地下水三维流数值模型研究的基础上，采用参数灵敏度分析的方法，对东露天煤矿工业场地地下水位变化影响因素进行定量分析。结果表明，场地内强风化砂泥岩的渗透性能、填土区大气降水补给能力、盲沟排水能力对工业场地因填土引起的地下水位变化有显著影响。针对这些主要影响因素，进行工业场地各地层渗透系数研究，为完善地面排水系统，控制盲沟质量等提供有力依据，控制工业场地的地下水位上升。

关键词： 数值模型     地下水位变化     影响因素     灵敏度分析    

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三峡工程对葛洲坝枢纽下游近坝段水位与航道影响研究

陆永军,陈稚聪,赵连白,邵学军,杨美卿,李云中

《中国工程科学》 2002年 第4卷 第10期   页码 67-72

摘要：

根据实测地形和水文泥沙资料，分析了葛洲坝枢纽运用后宜昌河段的河床冲淤变化、推移质和床沙的粗化以及枯水位的变化。由数学模型计算和物理模型试验成果，预测了三峡工程施工期及初期运用阶段葛洲坝枢纽近坝段水位下降及对通航的影响。

关键词： 葛洲坝枢纽     三峡工程     冲刷     水位下降     船闸与航道     数学模型     物理模型    

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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    

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Bi-modes alternation stepping ultrasonic motors

JIN Jiamei, ZHAO Chunsheng

《机械工程前沿（英文）》 2008年 第3卷 第1期   页码 101-105 doi: 10.1007/s11465-008-0018-1

摘要： Based on the principle of alternative operation of two bending vibration modes in an annular stator, this paper presents a standing-wave stepping ultrasonic motor characterized by no accumulative errors driven by an open-loop control circuitry. The driving forces are generated from the motions of projections on the stator in two modes. The positioning of the motor is achieved by the cooperation between the stator projections and rotor teeth, and the number of the rotors determines the stepping angle of the motor. Two-phase sinusoidal signals corresponding to the two modal frequencies drive the motor bi-direction stepping rotation via a switch unit. The prototype runs steadily without miss-step on trial. The single-step angle displacement of the motor is 2.5°.

关键词： miss-step     bi-direction     Two-phase sinusoidal     positioning     accumulative    

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标题 作者 时间 类型 操作

Optimization of urban bus operation frequency under common route condition with rail transit

Bin YU, Sijia REN, Enze WU, Yifan ZHOU, Yunpeng WANG

期刊论文

Leveraging individual-level data to advance air pollution health risk management

Jianxun YANG, Wenjing WU, Miaomiao LIU, Jun BI

期刊论文

Rapid evaluation technology for CNC machine tool slide level based on built-in sensors

Yuqing ZHOU, Xuesong MEI, Gedong JIANG, Nuogang SUN,

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

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

期刊论文

M-LFM: a multi-level fusion modeling method for shape−performance integrated digital twin of complex

期刊论文

Isogeometric analysis based on geometric reconstruction models

期刊论文

Development of a constitutive model for rockfills and similar granular materials based on the disturbed

Mehdi VEISKARAMI, Ali GHORBANI, Mohammadreza ALAVIPOUR

期刊论文

一种适用于自动驾驶汽车的多层地图模型和车道级轨迹规划

江昆, 杨殿阁, 柳超然, 张涛, 肖中阳

期刊论文

Cleaning the energy sources for water heating among Nanjing households: barriers and opportunities for solar and natural gas

Lingyun ZHU,Beibei LIU,Jun BI

期刊论文

基于位平面可预测性的无损图像压缩研究

厉鲁卫,周朔燕,蔡益宇

期刊论文

平朔东露天煤矿工业场地地下水位变化影响因素分析

林杜军,宫守才,张银洲

期刊论文

三峡工程对葛洲坝枢纽下游近坝段水位与航道影响研究

陆永军,陈稚聪,赵连白,邵学军,杨美卿,李云中

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

Bi-modes alternation stepping ultrasonic motors

JIN Jiamei, ZHAO Chunsheng

期刊论文