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Simulation of performance of intermediate fluid vaporizer under wide operation conditions

Bojie WANG, Wen WANG, Chao QI, Yiwu KUANG, Jiawei XU

《能源前沿（英文）》 2020年第14卷第3期页码 452-462 doi: 10.1007/s11708-020-0681-4

摘要： The intermediate fluid vaporizer (IFV) is a typical vaporizer of liquefied natural gas (LNG), which in general consists of three shell-and-tube heat exchangers (an evaporator, a condenser, and a thermolator). LNG is heated by seawater and the intermediate fluid in these heat exchangers. A one-dimensional heat transfer model for IFV is established in this paper in order to investigate the influences of structure and operation parameters on the heat transfer performance. In the rated condition, it is suggested to reduce tube diameters appropriately to get a large total heat transfer coefficient and increase the tube number to ensure the sufficient heat transfer area. According to simulation results, although the IFV capacity is much larger than the simplified-IFV (SIFV) capacity, the mode of SIFV could be recommended in some low-load cases as well. In some cases at high loads exceeding the capacity of a single IFV, it is better to add an AAV or an SCV operating to the IFV than just to increase the mass flow rate of seawater in the IFV in LNG receiving terminals.

关键词： liquefied natural gas intermediate fluid vapo-rizer heat transfer performance numerical simulation extreme condition

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忆容振荡器初值切换调控的超级多稳定性及其机理分析 Research Articles

陈蓓,徐权,陈墨,武花干,包伯成

《信息与电子工程前沿（英文）》 2021年第22卷第11期页码 1517-1531 doi: 10.1631/FITEE.2000622

摘要：超级多稳定性以其丰富多样的动力学状态和工程应用中的极大灵活性受到科学家们关注。利用4个线性电路元件和一个具有余弦逆忆容值的非线性荷控型忆容元件，构造了一个四维忆容振荡器。四维忆容振荡器具有一个线平衡集，其稳定性随忆容的初始条件周期性演化。由于周期性演化的稳定性，四维忆容振荡器展现了初值切换调控的超级多稳定性。通过分岔图、李雅普诺夫指数和相轨图，揭示了周期倍增/减半分岔、混沌危机和初值切换共存吸引子的复杂动力学行为。在此基础上，通过积分变换得到一个重构系统，揭示了忆容振荡器中初值切换调控超级多稳定性的形成机理。最后设计了重构系统的实现电路，并进行了PSIM电路仿真，验证了数值分析的有效性。

关键词：超级多稳定性；初值切换调控；忆容振荡器；机理分析

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strength prediction and optimization design of sustainable concrete based on squirrel search algorithm-extreme

《结构与土木工程前沿（英文）》页码 1310-1325 doi: 10.1007/s11709-023-0997-3

摘要： Concrete is the most commonly used construction material. However, its production leads to high carbon dioxide (CO₂) emissions and energy consumption. Therefore, developing waste-substitutable concrete components is necessary. Improving the sustainability and greenness of concrete is the focus of this research. In this regard, 899 data points were collected from existing studies where cement, slag, fly ash, superplasticizer, coarse aggregate, and fine aggregate were considered potential influential factors. The complex relationship between influential factors and concrete compressive strength makes the prediction and estimation of compressive strength difficult. Instead of the traditional compressive strength test, this study combines five novel metaheuristic algorithms with extreme gradient boosting (XGB) to predict the compressive strength of green concrete based on fly ash and blast furnace slag. The intelligent prediction models were assessed using the root mean square error (RMSE), coefficient of determination (R²), mean absolute error (MAE), and variance accounted for (VAF). The results indicated that the squirrel search algorithm-extreme gradient boosting (SSA-XGB) yielded the best overall prediction performance with R² values of 0.9930 and 0.9576, VAF values of 99.30 and 95.79, MAE values of 0.52 and 2.50, RMSE of 1.34 and 3.31 for the training and testing sets, respectively. The remaining five prediction methods yield promising results. Therefore, the developed hybrid XGB model can be introduced as an accurate and fast technique for the performance prediction of green concrete. Finally, the developed SSA-XGB considered the effects of all the input factors on the compressive strength. The ability of the model to predict the performance of concrete with unknown proportions can play a significant role in accelerating the development and application of sustainable concrete and furthering a sustainable economy.

关键词： sustainable concrete fly ash slay extreme gradient boosting technique squirrel search algorithm parametric analysis

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气候变暖背景下的极端天气气候事件与防灾减灾

翟盘茂,刘静

《中国工程科学》 2012年第14卷第9期页码 55-63

摘要：

首先概括极端天气气候事件以及“气候极值”的相关定义，并把极端事件分为单要素的极端事件、与天气现象有关的极端事件、多要素极端事件和极端气候事件。在此基础上，总结上述几类极端事件在气候变暖背景下的变化趋势及影响。指出气候变暖背景下我国长江中下游区域强降水事件更趋频繁，我国东部地区高温热浪天气更为明显；东北华北地区干旱趋势增加，尤其在20世纪末期和21世纪初期最为明显；近10年来西南地区干旱频繁发生。为减轻日益增加的重大气象灾害的损失，我国有必要加强高影响极端事件的监测、预警能力建设，同时还必须根据极端天气气候事件变化规律加强工程性防御措施，以防范和应对强降水引发的洪涝灾害和城市渍涝，以及与降水持续不足有关的重大干旱和高温热浪等气象灾害。

关键词：极端气候指数高影响气象灾害工程

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Concrete corrosion in wastewater systems: Prediction and sensitivity analysis using advanced extreme

Mohammad ZOUNEMAT-KERMANI, Meysam ALIZAMIR, Zaher Mundher YASEEN, Reinhard HINKELMANN

《结构与土木工程前沿（英文）》 2021年第15卷第2期页码 444-460 doi: 10.1007/s11709-021-0697-9

摘要： The implementation of novel machine learning models can contribute remarkably to simulating the degradation of concrete due to environmental factors. This study considers the sulfuric acid corrosive factor in wastewater systems to simulate concrete mass loss using five machine learning models. The models include three different types of extreme learning machines, including the standard, online sequential, and kernel extreme learning machines, in addition to the artificial neural network, classification and regression tree model, and statistical multiple linear regression model. The reported values of concrete mass loss for six different types of concrete are the target values of the machine learning models. The input variability was assessed based on two scenarios prior to the application of the predictive models. For the first assessment, the machine learning models were developed using all the available cement and concrete mixture input variables; the second assessment was conducted based on the gamma test approach, which is a sensitivity analysis technique. Subsequently, the sensitivity analysis of the most effective parameters for concrete corrosion was tested using three different approaches. The adopted methodology attained optimistic and reliable modeling results. The online sequential extreme learning machine model demonstrated superior performance over the other investigated models in predicting the concrete mass loss of different types of concrete.

关键词： sewer systems environmental engineering data-driven methods sensitivity analysis

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A review of condition-based maintenance: Its prognostic and operational aspects

Yanrong LI, Shizhe PENG, Yanting LI, Wei JIANG

《工程管理前沿（英文）》 2020年第7卷第3期页码 323-334 doi: 10.1007/s42524-020-0121-5

摘要： Condition-based maintenance (CBM) detects early signs of failure and dictates when maintenance should be performed based on the actual condition of a system. In this paper, we first review some of the recent research on CBM under various physical structures and signal data. Then, we summarize several kinds of prognostic models that use monitoring information to estimate the reliability of complex systems or products. Monitoring information also facilitates operational decisions in production planning, spare parts management, reliability improvement, and prognostics and health management. Finally, we suggest some research opportunities for the reliability and operations management communities to fill the research gap between these two fields.

关键词： condition-based maintenance prognostics operational decision-making reliability

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Trend prediction technology of condition maintenance for large water injection units

Xiaoli XU, Sanpeng DENG

《机械工程前沿（英文）》 2010年第5卷第2期页码 171-175 doi: 10.1007/s11465-009-0091-0

摘要： Trend prediction technology is the key technology to achieve condition-based maintenance of mechanical equipment. Large-sized water injection units are key equipment in oilfields. The traditional preventive maintenance is not economical and cannot completely avoid vicious accidents. To ensure the normal operation of units and save maintenance costs, trend prediction technology is studied to achieve condition-based maintenance for water injection units. The main methods of the technology are given, the trend prediction method based on neural network is put forward, and the expert system based on the knowledge is developed. The industrial site verification shows that the proposed trend prediction technology can reflect the operating condition trend change of the water injection units and provide technical means to achieve condition-based predictive maintenance.

关键词： water injection units condition-based maintenance trend prediction

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compressive strength of concrete containing micro-silica, nano-silica, and polypropylene fibers using extreme

Fatemeh ZAHIRI, Hamid ESKANDARI-NADDAF

《结构与土木工程前沿（英文）》 2019年第13卷第4期页码 821-830 doi: 10.1007/s11709-019-0518-6

摘要： Many studies have evaluated the effects of additives such as nano-silica (NS), micro-silica (MS) and polymer fibers on optimizing the mechanical properties of concrete, such as compressive strength. Nowadays, with progress in cement industry provides, it has become possible to produce cement type I with strength classes of 32.5, 42.5, and 52.5 MPa. On the one hand, the microstructure of cement has changed, and modified by NS, MS, and polymers; therefore it is very important to determine the optimal percentage of each additives for those CSCs. In this study, 12 mix designs containing different percentages of MS, NS, and polymer fibers in three cement strength classes(CSCs) (32.5, 42.5, and 52.5 MPa) were designed and constructed based on the mixture method. Results indicated the sensitivity of each CSCs can be different on the NS or MS in compressive strength of concrete. Consequently, strength classes have a significant effect on the amount of MS and NS in mix design of concrete. While, polymer fibers don’t have significant effect in compressive strength considering CSCs.

关键词： mixture method compressive strength nano-silica micro-silica polypropylene fibers

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Real-time tool condition monitoring method based on temperature measurement and artificial neural network

《机械工程前沿（英文）》 doi: 10.1007/s11465-021-0661-3

摘要： Tool failures in machining processes often cause severe damages of workpieces and lead to large quantities of loss, making tool condition monitoring an important, urgent issue. However, problems such as practicability still remain in actual machining. Here, a real-time tool condition monitoring method integrated in an in situ fiber optic temperature measuring apparatus is proposed. A thermal simulation is conducted to investigate how the fluctuating cutting heats affect the measuring temperatures, and an intermittent cutting experiment is carried out, verifying that the apparatus can capture the rapid but slight temperature undulations. Fourier transform is carried out. The spectrum features are then selected and input into the artificial neural network for classification, and a caution is given if the tool is worn. A learning rate adaption algorithm is introduced, greatly reducing the dependence on initial parameters, making training convenient and flexible. The accuracy stays 90% and higher in variable argument processes. Furthermore, an application program with a graphical user interface is constructed to present real-time results, confirming the practicality.

关键词： tool condition monitoring cutting temperature neural network learning rate adaption

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Liquid metal enabled combinatorial heat transfer science: toward unconventional extreme cooling

Xiao-Hu YANG, Jing LIU

《能源前沿（英文）》 2018年第12卷第2期页码 259-275 doi: 10.1007/s11708-017-0521-3

摘要： As a class of newly emerging material, liquid metal exhibits many outstanding performances in a wide variety of thermal management areas, such as thermal interface material, heat spreader, convective cooling and phase change material (PCM) for thermal buffering etc. To help mold next generation unconventional cooling technologies and further advance the liquid metal cooling to an ever higher level in tackling more extreme, complex and critical thermal issues and energy utilizations, a novel conceptual scientific category was dedicated here which could be termed as combinatorial liquid metal heat transfer science. Through comprehensive interpretations on a group of representative liquid metal thermal management strategies, the most basic ways were outlined for developing liquid metal enabled combined cooling systems. The main scientific and technical features of the proposed hybrid cooling systems were illustrated. Particularly, five abstractive segments toward constructing the combinatorial liquid metal heat transfer systems were clarified. The most common methods on innovating liquid metal combined cooling systems based on this classification principle were discussed, and their potential utilization forms were proposed. For illustration purpose, several typical examples such as low melting point metal PCM combined cooling systems and liquid metal convection combined cooling systems, etc. were specifically introduced. Finally, future prospects to search for and make full use of the liquid metal combined high performance cooling system were discussed. It is expected that in practical application in the future, more unconventional combination forms on the liquid metal cooling can be obtained from the current fundamental principles.

关键词： combinatorial heat transfer liquid metal high flux cooling thermal management

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中国极端降水和高温历史变化及未来趋势

舒章康,李文鑫,张建云,金君良,薛晴,王银堂,胡庆芳,王国庆

《中国工程科学》 2022年第24卷第5期页码 116-125 doi: 10.15302/J-SSCAE-2022.05.014

摘要：

在全球变暖背景下，我国极端事件频发，了解和掌握极端事件的时空变化，合理预估极端事件的未来趋势，可为制定区域气候变化适应策略提供理论依据。本文利用CN05.1 全国网格气象数据和第六次国际耦合模式比较计划（CMIP6）的11 种全球气候模式，分析了我国1975—2014 年历史极端降水和高温事件的演变特征，研判了2015—2054 年极端事件的变化情况，提出了应对极端事件的政策建议。结果表明：① 1975—2014 年，全国强降水量呈现由西北向东南依次增加‒ 减少‒增加的空间格局，胡焕庸线以东地区极端降水风险和危险性较大；在选取的两种对比情景下，2015—2054 年，我国极端降水将普遍增多趋强，其中华北和东北地区极端降水事件增幅较大，西北地区强降水量将进一步增加。② 我国1975—2014 年暖夜日数和暖昼日数均呈显著增加趋势，暖夜日数增幅高于暖昼日数增幅；在选取的两种对比情景下，2015—2054 年，我国极端高温事件将显著增加，西北、西南和华南等地区的高温热浪风险增幅最大。为减缓气候变化影响和应对未来极端事件风险，应进一步提升洪涝灾害和高温热浪风险应对和应急管理能力，强化国际合作并因地制宜制定相关适应气候变化战略，以防范和应对全球变暖引起的极端灾害。

关键词：气候变化；极端事件；CMIP6；极端灾害应对

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Benzene removal by nano magnetic particles under continuous condition from aqueous solutions

Amin Mohammad Mehdi,Bina Bijan,Majd Amir Masoud Samani,Pourzamani Hamidreza

《环境科学与工程前沿（英文）》 2014年第8卷第3期页码 345-356 doi: 10.1007/s11783-013-0574-4

摘要： Benzene removal from aqueous solutions was evaluated using Fe O nano magnetic particles (NM) in continuous condition. A 4 factorial design including initial benzene concentration, NM dose, contact time and pH was investigated in 16 experiments (Taguchi OA design). The results indicated that all factors were significant and the optimum condition was: pH 8, NM dose of 2000 mg·L , benzene concentrations of 100 mg·L and contact time of 14 min. The maximum benzene uptake and distribution ratio in the optimum situation were 49.4 mg·g and 38.4 L·g , respectively. The nano particles were shown to capture 98.7% of the benzene in optimum batch condition and 94.5% in continuous condition. The isotherm data proved that the Brunauer-Emmett-Teller model fit more closely and produced an isotherm constant (b) less than one, indicating favorable adsorption. Regeneration studies verified that the benzene adsorbed by the NM could be easily desorbed by temperature, and thereby, NM can be employed repeatedly in water and wastewater management.

关键词： benzene experimental design Fe₃O₄ continues condition thermal recycling

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超大规模并行计算：瓶颈与对策 None

Ze-yao MO

《信息与电子工程前沿（英文）》 2018年第19卷第10期页码 1251-1260 doi: 10.1631/FITEE.1800421

摘要：超大规模数值模拟极大依赖并行计算能力。从计算规模、计算效率和编程生产率3个维度，系统分析了超大规模并行计算能力的主要瓶颈，提出亟待研究的若干关键技术问题和技术对策。本文对推动数值模拟软件计算能力与超级计算机峰值性能的同步提升具有参考价值。

关键词：超大规模；数值模拟；并行计算；超级计算机

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Modeling of semi-rigid beam-to-column steel joints under extreme loading

C FANG, B A IZZUDDIN, A Y ELGHAZOULI, D A NETHERCOT

《结构与土木工程前沿（英文）》 2013年第7卷第3期页码 245-263 doi: 10.1007/s11709-013-0215-9

摘要： Joints play an important role in providing ductility for steel-composite structures subject to extreme loading conditions, such as blast, fire and impact. Due to sound energy dissipation capability and fabrication efficiency, semi-rigid joints have increasingly received attention during the last decade. This paper presents a component approach for modeling semi-rigid beam-to-column joints based on Eurocode3, where the post-elastic response, including component strain hardening and ultimate rotational capacity, is also considered. Failure criteria are defined based on the ultimate deformation capacity of components and bolt-rows. The model enables a direct integration of joint response into global frame models with the consideration of axial deformability, such that the interaction between bending moment and axial force within the joints can be realistically captured. In addition, elevated temperature can be considered in the joint model via the degradation of the component response. Through comparisons with available test data, the joint model is shown to have good accuracy, and the failure criteria are found to be reliable yet conservative. The strain hardening response of components is shown to have significant influence on the ultimate bending capacity of the joints, while neglecting it usually leads to a conservative prediction.

关键词： semi-rigid joint component method ductility elevated temperature

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In-situ condition monitoring of reinforced concrete structures

Sanjeev Kumar VERMA,Sudhir Singh BHADAURIA,Saleem AKHTAR

《结构与土木工程前沿（英文）》 2016年第10卷第4期页码 420-437 doi: 10.1007/s11709-016-0336-z

摘要： Performance of concrete structures is significantly influenced and governed by its durability and resistance to environmental or exposure conditions, apart from its physical strength. It can be monitored, evaluated and predicted through modeling of physical deterioration mechanisms, performance characteristics and parameters and condition monitoring of in situ concrete structures. One such study has been conducted using Non-destructive testing equipment in the city of Bhopal and around located in India. Some selected parameters influencing durability of reinforced concrete (RC) structures such as concrete cover, carbonation depth, chloride concentration, half cell potential and compressive strength have been measured, for establishing correlation among various parameters and age of structures. Effects of concrete cover and compressive strength over the variation of chloride content with time are also investigated.

关键词： concrete carbonation chloride corrosion monitoring models