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Fast scaling approach based on cavitation conditions to estimate the speed limitation for axial piston

Qun CHAO, Jianfeng TAO, Junbo LEI, Xiaoliang WEI, Chengliang LIU, Yuanhang WANG, Linghui MENG

《机械工程前沿(英文)》 2021年 第16卷 第1期   页码 176-185 doi: 10.1007/s11465-020-0616-0

摘要: The power density of axial piston pumps can benefit greatly from increased rotational speeds. However, the maximum rotational speed of axial piston machines is limited by the cavitation phenomenon for a given volumetric displacement. This paper presents a scaling law derived from an analytical cavitation model to estimate the speed limitations for the same series of axial piston pumps. The cavitation model is experimentally verified using a high-speed axial piston pump, and the scaling law is validated with open specification data in product brochures. Results show that the speed limitation is approximately proportional to the square root of the inlet pressure and inversely proportional to the cube root of volumetric displacement. Furthermore, a characteristic constant is defined based on the presented scaling law. This constant can represent the comprehensive capacity of axial piston pumps free from cavitation.

关键词: axial piston pump     cavitation     speed limitation     scaling law    

Capacity limitation of nuclear units in grid based on analysis of frequency regulation

Yiping DAI, Pan JIANG, Lin GAO, Weimin KAN, Xiaoqing XIAO, Ge JIN

《能源前沿(英文)》 2012年 第6卷 第2期   页码 148-154 doi: 10.1007/s11708-012-0174-1

摘要: The increasing capacity of nuclear units in power grid poses threat to system stability and security. Load disturbance may cause overspeed of the units and trigger the overspeed protection controller (OPC). Repeating actions of valves have a strong impact on the security of the equipment and may result in a collapse of the power system. Based on the analysis of frequency regulation, mathematic models for nuclear units in the grid are established in this paper to simulate the dynamic process when load disturbance occurs. The critical action of the OPC is proposed as the constraint of safe operation for the units. The relationship between different styles of frequency regulation and the allowable capacity of the nuclear units in the grid is discussed. This research can help to estimate the capacity limitation of nuclear units in the grid.

关键词: nuclear units capacity     overspeed     primary frequency control (PFC)     second frequency control (SFC)    

Aerodynamic challenges in span length of suspension bridges

XIANG Haifan, GE Yaojun

《结构与土木工程前沿(英文)》 2007年 第1卷 第2期   页码 153-162 doi: 10.1007/s11709-007-0016-0

摘要: The potential requirement of extreme bridge spans is firstly discussed according to horizontal clearances for navigation and economical construction of deep-water foundation. To ensure the technological feasibility of suspension bridges with longer spans, the static estimation of feasible span length is then made based on current material strength and weight of cables and deck. After the performances of the countermeasures for raising the aerodynamic stability are reviewed, a trial design of a 5 000 m suspension bridge, which is estimated as a reasonable limitation of span length, is finally conducted to respond to the tomorrow s challenge in span length of suspension bridges with the particular aspects, including dynamic stiffness, aerodynamic flutter and aerostatic stability.

关键词: requirement     reasonable limitation     challenge     particular     economical construction    

Genome-wide association studies: inherent limitations and future challenges

null

《医学前沿(英文)》 2012年 第6卷 第4期   页码 444-450 doi: 10.1007/s11684-012-0225-3

摘要:

Genome-wide association studies (GWAS) have achieved great success in identifying genetic variants related to complex human diseases such as cancer and have provided valuable insights into their genetic architecture. Recently, GWAS is quite the fashion in China. However, there are issues related to its nature. Enormous work needs to be done in the post-GWAS era. Deep sequencing followed by functional studies will be needed to elucidate the underpinning biological mechanisms and further translate GWAS findings into medical practice. Along with pharmacogenomics, the success of GWAS in identifying genetic risk factors and genetic differences in drug response has been gradually enabling personalized medicine. In this article, we used hepatocellular carcinoma (HCC) as an example to demonstrate some of the inherent limitations and summarized future challenges of GWAS.

关键词: genome-wide association studies (GWAS)     genetic variant     cancer     limitation     challenge    

Value and governance of high-speed railway

Xiaoyan LIN, Zehua ZHANG, Meng WANG

《工程管理前沿(英文)》 2017年 第4卷 第4期   页码 463-482 doi: 10.15302/J-FEM-2017054

摘要: This paper considers multiple perspectives to explore the concept of high-speed railway (HSR), rationally abstract its value formation mechanism, and quantitatively measure its actual performance. This paper analyzes the governance potential of major countries in the high-speed railway value chain and studies the feasible ways and development strategies to enhance the high-speed railway governance in China. Findings of this paper are as follows. First, the government, as the early manager of high-speed railway governance, has given way to Siemens and other integrated enterprises. Second, the high-speed railway standard output has become the core competitiveness that embodies high-speed railway. Third, the global high-speed railway market presents a hierarchical high-speed railway governance model and changes to a modular approach to governance.

关键词: high-speed railway value     communication value     high-speed railway value governance     governance path upgrade    

Robust energy-efficient train speed profile optimization in a scenario-based position–time–speed network

《工程管理前沿(英文)》 2021年 第8卷 第4期   页码 595-614 doi: 10.1007/s42524-021-0173-1

摘要: Train speed profile optimization is an efficient approach to reducing energy consumption in urban rail transit systems. Different from most existing studies that assume deterministic parameters as model inputs, this paper proposes a robust energy-efficient train speed profile optimization approach by considering the uncertainty of train modeling parameters. Specifically, we first construct a scenario-based position–time–speed (PTS) network by considering resistance parameters as discrete scenario-based random variables. Then, a percentile reliability model is proposed to generate a robust train speed profile, by which the scenario-based energy consumption is less than the model objective value at α confidence level. To solve the model efficiently, we present several algorithms to eliminate the infeasible nodes and arcs in the PTS network and propose a model reformulation strategy to transform the original model into an equivalent linear programming model. Lastly, on the basis of our field test data collected in Beijing metro Yizhuang line, a series of experiments are conducted to verify the effectiveness of the model and analyze the influences of parameter uncertainties on the generated train speed profile.

关键词: robust train speed profile     percentile reliability model     scenario-based position–time–speed network     mixed-integer programming    

Construction management and technical innovation of the Beijing–Shanghai High Speed Railway

《工程管理前沿(英文)》 doi: 10.1007/s42524-024-0309-1

摘要: Construction management and technical innovation of the Beijing–Shanghai High Speed Railway

关键词: Beijing–Shanghai High Speed Railway     project construction     project management     technological innovation    

Data-driven rolling eco-speed optimization for autonomous vehicles

《工程管理前沿(英文)》 doi: 10.1007/s42524-023-0284-y

摘要: In urban settings, fluctuating traffic conditions and closely spaced signalized intersections lead to frequent emergency acceleration, deceleration, and idling in vehicles. These maneuvers contribute to elevated energy use and emissions. Advances in vehicle-to-vehicle and vehicle-to-infrastructure communication technologies allow autonomous vehicles (AVs) to perceive signals over long distances and coordinate with other vehicles, thereby mitigating environmentally harmful maneuvers. This paper introduces a data-driven algorithm for rolling eco-speed optimization in AVs aimed at enhancing vehicle operation. The algorithm integrates a deep belief network with a back propagation neural network to formulate a traffic state perception mechanism for predicting feasible speed ranges. Fuel consumption data from the Argonne National Laboratory in the United States serves as the basis for establishing the quantitative correlation between the fuel consumption rate and speed. A spatiotemporal network is subsequently developed to achieve eco-speed optimization for AVs within the projected speed limits. The proposed algorithm results in a 12.2% reduction in energy consumption relative to standard driving practices, without a significant extension in travel time.

关键词: data-driven learning     speed optimization     autonomous vehicles     energy saving    

中国铁路高速道岔技术研究

何华武

《中国工程科学》 2009年 第11卷 第5期   页码 23-30

摘要:

高速道岔是高速铁路轨道结构的关键,其结构与状态对列车运行安全和运行品质具有重大影响。文章介绍了高速道岔设计参数和平面线形,扣件、岔枕、道岔转换系统等部件主要结构特征,高速道岔设计理论,相关技术条件及取得的创新成果,对于中国高速铁路道岔的进一步研制、试验验证及推广使用具有重要的指导意义。

关键词: 高速铁路     高速道岔     技术研究    

WEIS wheel speed real-time measuring method for VOSM

Mengyao PAN, Guixiong LIU, Xiaobin HONG, Tusheng LIN,

《机械工程前沿(英文)》 2010年 第5卷 第3期   页码 322-327 doi: 10.1007/s11465-010-0022-0

摘要: Wheel speed is one of the key parameters of vehicle operating attitude. To solve the problems in traditional wheel speed measuring methods, such as low measurement precision and the lack of real-time monitoring of the vehicle’s operating attitude, a wheel embedded intelligent sensors (WEIS) wheel speed measuring method for vehicle operating safety states monitoring (VOSM) is innovatively proposed. Radial acceleration signal is obtained through a WEIS module embedded in the hub. Using wavelet packet to implement wavelet de-noising for the non-stationary acceleration signals, and adopting short-time Fourier transform (STFT) algorithm to extract the signal characteristics, the wheel speed measurement can be achieved. The experimental result shows that under experimental conditions the speed measurement error is −2.05%, and the speed measuring response time is 0.45 s.

关键词: wheel embedded     intelligent sensing     wheel speed     monitoring    

Interactive effects of high-speed rail on nodal zones in a city: exploratory study on China

Guo LIU, Kunhui YE

《工程管理前沿(英文)》 2019年 第6卷 第3期   页码 327-335 doi: 10.1007/s42524-019-0051-2

摘要: The arrival of the high-speed rail (HSR) era has accelerated the pace of urban development, but its broad socioeconomic impact remains subject to intense debates. This research aims to propose a model for measuring the impact of HSR operation on HSR stations and the surrounding areas, which this research call the HSR-based nodal zone (HNZ). The proposed model is composed of two variables (i.e., transportation situation and vitality) and three subsystems (i.e., economic, societal, and environmental). Data were collected in China through questionnaire survey. Results indicate that the effects of HSR operation on HNZ are multidimensional, transportation vitality has an intermediary role in the effects, and the effects on the physical environment are negative. This study presents an early examination of the impact of HSR operation on the HSR stations and relevant areas and contributes new evidence to academic debates on the contribution of HSR to urban development. Accordingly, urban development policies should be built on the mechanism of HSR in driving the growth of HNZ.

关键词: high-speed rail     nodal zone     interactive effects     sustainable urbanization     China    

Detection of critical road roughness sections by trend analysis and investigation of driver speed interaction

Meltem SAPLIOGLU; Ayse UNAL; Melek BOCEK

《结构与土木工程前沿(英文)》 2022年 第16卷 第4期   页码 515-532 doi: 10.1007/s11709-022-0814-4

摘要: Pavement roughness (IRI—International Roughness Index values) influence the stability of traffic movements both on intercity roads and urban roads. This study is to determine the exact locations of critical pavement roughness values that affect traffic motion stability and comfort in city centre highway arteries. Roughness data with 10 m intervals were collected on a 3140 m divided road containing three consecutive signalized intersections in the city centre arterial. These data were analysed using the distance-dependent Mann-Kendall trend analysis method and checkerboard model. The sections where roughness is important were determined at a 95% confidence interval. The results will show where future pavement improvements should be prioritized for municipalities and road maintenance engineers and will form a basis for the urban road management system.

关键词: trend analysis     checkerboard model     IRI     driver speed    

Case modifying of high-speed cutting database based on CSP and similarity theory

Kejun XIANG, Zhanqiang LIU, Xing AI

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 83-87 doi: 10.1007/s11465-009-0014-0

摘要: By analyzing the reasoning of a high-speed cutting database system, a case modifying method is put forward. According to the variables’ difference of the solution part in a case, a constraint satisfaction problem (CSP) and similarity calculation are used to modify a case. The constraint relationship of discrete variables is described by establishing a rule knowledge base. The algorithm of CSP is used to solve the discrete variable constraint problem. On the basis of the high-speed cutting theory, a similarity calculation formula is deduced to calculate the consecutive variables. The CSP and similarity calculation are applied to case modifying, which is possible to automatically modify cases in the high-speed cutting database system.

关键词: high-speed cutting database     case modifying     CSP     similarity calculation    

Robust train speed trajectory optimization: A stochastic constrained shortest path approach

Li WANG, Lixing YANG, Ziyou GAO, Yeran HUANG

《工程管理前沿(英文)》 2017年 第4卷 第4期   页码 408-417 doi: 10.15302/J-FEM-2017042

摘要: Train speed trajectory optimization is a significant issue in railway traffic systems, and it plays a key role in determining energy consumption and travel time of trains. Due to the complexity of real-world operational environments, a variety of factors can lead to the uncertainty in energy-consumption. To appropriately characterize the uncertainties and generate a robust speed trajectory, this study specifically proposes distance-speed networks over the inter-station and treats the uncertainty with respect to energy consumption as discrete sample-based random variables with correlation. The problem of interest is formulated as a stochastic constrained shortest path problem with travel time threshold constraints in which the expected total energy consumption is treated as the evaluation index. To generate an approximate optimal solution, a Lagrangian relaxation algorithm combined with dynamic programming algorithm is proposed to solve the optimal solutions. Numerical examples are implemented and analyzed to demonstrate the performance of proposed approaches.

关键词: train speed trajectory optimization     railway operation     stochastic programming    

Exploration on Engineering Management Practice of China’s High Speed Railways

Yong-fu Sun

《工程管理前沿(英文)》 2014年 第1卷 第3期   页码 232-240 doi: 10.15302/J-FEM-2014043

摘要: This paper explores the principal motivations and successful experiences of the rapid development of China’s high speed railway. In the perspective of the engineering management practice, the developers have studied and made prospective mid- and long-term railway network planning, including the four east-west and four north-south corridors as the backbone, the interregional urban passenger traffic corridors and the intercity railways, with a planning scale above 16,000 km. Under the overall coordination of the government, a high speed railway technology system has been formed with the China’s characteristics, by the way of sticking to independent innovation, of combining original innovation, collaborative innovation and integrative innovation, and of attaching importance to experimental verification. The target control system and support-guarantee system were established for the high speed railway project, enacting standardized management, strengthening integration test and commissioning, conducting strict acceptance, and achieving construction management experiences on the high speed railway. Finally, this paper proposes such issues worthy of attention and further study, as the improvement of the engineering decision-making management, the enhancement of investment and financing system reform, and the promotion of professionalization and the specialization of engineering project management.

关键词: high speed railway     engineering management     practice     innovation    

标题 作者 时间 类型 操作

Fast scaling approach based on cavitation conditions to estimate the speed limitation for axial piston

Qun CHAO, Jianfeng TAO, Junbo LEI, Xiaoliang WEI, Chengliang LIU, Yuanhang WANG, Linghui MENG

期刊论文

Capacity limitation of nuclear units in grid based on analysis of frequency regulation

Yiping DAI, Pan JIANG, Lin GAO, Weimin KAN, Xiaoqing XIAO, Ge JIN

期刊论文

Aerodynamic challenges in span length of suspension bridges

XIANG Haifan, GE Yaojun

期刊论文

Genome-wide association studies: inherent limitations and future challenges

null

期刊论文

Value and governance of high-speed railway

Xiaoyan LIN, Zehua ZHANG, Meng WANG

期刊论文

Robust energy-efficient train speed profile optimization in a scenario-based position–time–speed network

期刊论文

Construction management and technical innovation of the Beijing–Shanghai High Speed Railway

期刊论文

Data-driven rolling eco-speed optimization for autonomous vehicles

期刊论文

中国铁路高速道岔技术研究

何华武

期刊论文

WEIS wheel speed real-time measuring method for VOSM

Mengyao PAN, Guixiong LIU, Xiaobin HONG, Tusheng LIN,

期刊论文

Interactive effects of high-speed rail on nodal zones in a city: exploratory study on China

Guo LIU, Kunhui YE

期刊论文

Detection of critical road roughness sections by trend analysis and investigation of driver speed interaction

Meltem SAPLIOGLU; Ayse UNAL; Melek BOCEK

期刊论文

Case modifying of high-speed cutting database based on CSP and similarity theory

Kejun XIANG, Zhanqiang LIU, Xing AI

期刊论文

Robust train speed trajectory optimization: A stochastic constrained shortest path approach

Li WANG, Lixing YANG, Ziyou GAO, Yeran HUANG

期刊论文

Exploration on Engineering Management Practice of China’s High Speed Railways

Yong-fu Sun

期刊论文