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Investigation on multiple-melting behavior of nano-CaCO3/polypropylene composites

LIN Zhidan, ZENG Chunlian, MAI Kancheng

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 81-86 doi: 10.1007/s11705-007-0017-5

摘要： The multiple melting-peak behavior of polypropylene (PP) in nano-CaCO/PP composites and modified nano-CaCO/PP composites were investigated under the condition of isothermal crystallization and nonisothermal crystallization. The result indicated that the addition of nano-CaCO markedly increased the crystallization temperatures of PP and induced the formation of the β-crystal of PP. The crystallization temperatures of nano-CaCO/PP composites modified by reactive monomers were further increased, but the melting-peak intensity of the β-crystal of PP was not greatly influenced. While in the presence of dicumyl peroxide, nano-CaCO/PP composites modified by reactive monomers led to the significant increase in the melting-peak intensity of the β-crystal of PP. The double melting-peak of PP was observed, which was attributed to the formation of two kinds of different crystallization forms of α-crystal or β-crystal during the crystallization of PP. With the increase of crystallization temperatures, the double melting-peak moved toward the high-temperature side. The intensity of high-temperature melting peak was higher than that of low-temperature melting peak in nano-CaCO/PP composites. While in modified nano-CaCO/PP composites crystallized at higher temperature, the intensity of high-temperature melting peak was lower than that of low-temperature melting peak. The isothermal crystallization time had little effect on the melting temperatures.

关键词： polypropylene     nano-CaCO/PP     presence     melting-peak behavior     low-temperature    

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Study on the crystal morphology and melting behavior of isothermally crystallized composites of short

Mingtao RUN, Hongzan SONG, Yanping HAO

《化学科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 255-264 doi: 10.1007/s11705-009-0008-9

摘要： The spherulites of the short carbon fiber(SCF)/poly (trimethylene terephthalate) (PTT) composites formed in limited space at designed temperatures, and their melting behaviors were studied by the polarized optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. The results suggest that SCF content, isothermal crystallization temperatures, and the film thicknesses influence the crystal morphology of the composites. The dimension of the spherulites is decreased with increasing SCF content, but whether banded or nonbanded spherulites will form in the composites is not dependent on SCF content. However, the crystal morphology of the composites depends strongly on the temperature. When the isothermal crystallization temperatures increase from 180°C to 230°C, the crystal morphology of SCF/PTT composites continuously changes in the following order: nonbanded → banded → nonbanded spherulites. Discontinuous circle lines form in the film when the film thickness increases from 30 to 60 μm. Basing on the SEM observation, it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the spherulites. These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room temperature at a slow cooling rate; while they will disappear gradually at different temperatures in the heating process. The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated. The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the spherulites.

关键词： poly(trimethylene terephthalate)     short carbon fiber     banded spherulites     crack    

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Room temperature liquid metal: its melting point, dominating mechanism and applications

Junheng FU, Chenglin ZHANG, Tianying LIU, Jing LIU

《能源前沿（英文）》 2020年 第14卷 第1期   页码 81-104 doi: 10.1007/s11708-019-0653-8

摘要： The room temperature liquid metal (LM) is recently emerging as a new class of versatile materials with fascinating characteristics mostly originated from its simultaneous metallic and liquid natures. The melting point is a typical parameter to describe the peculiarity of LM, and a pivotal factor to consider concerning its practical applications such as phase change materials (PCMs) and advanced thermal management. Therefore, the theoretical exploration into the melting point of LM is an essential issue, which can be of special value for the design of new LM materials with desired properties. So far, some available strategies such as molecular dynamics (MD) simulation and classical thermodynamic theory have been applied to perform correlative analysis. This paper is primarily dedicated to performing a comprehensive overview regarding typical theoretical strategies on analyzing the melting points. It, then, presents evaluations on several factors like components, pressure, size and supercooling that may be critical for melting processes of liquid metal. After that, it discusses applications associated with the characteristic of low melting points of LM. It is expected that a great many fundamental and practical works are to be conducted in the coming future.

关键词： melting point     liquid metal     crystal     thermodynamics     molecular dynamics    

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Phase change effect of low melting point metal for an automatic cooling of USB flash memory

Haoshan GE, Jing LIU

《能源前沿（英文）》 2012年 第6卷 第3期   页码 207-209 doi: 10.1007/s11708-012-0204-z

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Factors influencing peak bone mass gain

Xiaowei Zhu, Houfeng Zheng

《医学前沿（英文）》 2021年 第15卷 第1期   页码 53-69 doi: 10.1007/s11684-020-0748-y

摘要： Bone mass is a key determinant of osteoporosis and fragility fractures. Epidemiologic studies have shown that a 10% increase in peak bone mass (PBM) at the population level reduces the risk of fracture later in life by 50%. Low PBM is possibly due to the bone loss caused by various conditions or processes that occur during adolescence and young adulthood. Race, gender, and family history (genetics) are responsible for the majority of PBM, but other factors, such as physical activity, calcium and vitamin D intake, weight, smoking and alcohol consumption, socioeconomic status, age at menarche, and other secondary causes (diseases and medications), play important roles in PBM gain during childhood and adolescence. Hence, the optimization of lifestyle factors that affect PBM and bone strength is an important strategy to maximize PBM among adolescents and young people, and thus to reduce the low bone mass or osteoporosis risk in later life. This review aims to summarize the available evidence for the common but important factors that influence bone mass gain during growth and development and discuss the advances of developing high PBM.

关键词： peak bone mass     children     adolescents     genetic     risk factors    

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Zero increase in peak discharge for sustainable development

Xing Fang, Junqi Li, Yongwei Gong, Xiaoning Li

《环境科学与工程前沿（英文）》 2017年 第11卷 第4期 doi: 10.1007/s11783-017-0935-5

摘要： For urban land development, some or all natural land uses (primarily pervious) are converted into impervious areas which lead to increases of runoff volume and peak discharge. Most of the developed countries require a zero increase in peak discharge for any land development, and the policy has been implemented for several decades. The policy of zero increase in peak discharge can be considered as historical and early stage for the low impact development (LID) and sustainable development, which is to maintain natural hydrological conditions by storing a part or all of additional runoff due to the development on site. The paper will discuss the policy, the policy implementation for individual projects and their impact on regional hydrology. The design rainfalls for sizing LID facilities that are determined in 206 weather stations in USA are smaller than design rainfalls for sizing detention basins. The zero-increase policy links to financial responsibility and sustainability for construction of urban stormwater infrastructures and for reducing urban flooding. The policy was compared with current practices of urban development in China to shine the light for solving urban stormwater problems. The connections and differences among LID practices, the zero-increase policy, and the flood control infrastructure were discussed. We promote and advocate the zero-increase policy on peak discharge for comprehensive stormwater management in China in addition to LID.

关键词： Stormwater management     Detention basin     Zero increase     Peak discharge     Sustainable development     Design rainfall    

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A steam dried municipal solid waste gasification and melting process

Gang XIAO, Baosheng JIN, Mingjiang NI, Kefa CEN, Yong CHI, Zhongxin TAN

《环境科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 193-204 doi: 10.1007/s11783-010-0268-0

摘要： Considering high-moisture municipal solid waste (MSW) of China, a steam dried MSW gasification and melting process was proposed, the feasibility was tested, and the mass and energy balance was analyzed. Preliminary experiments were conducted using a fixed-bed drying apparatus, a 200 kg per day fluidized-bed gasifier, and a swirl melting furnace. Moisture percentage was reduced from 50% to 20% roughly when MSW was dried by slightly superheated steam of 150°C–350°C within 40 min. When the temperature was less than 250°C, no incondensable gas was produced during the drying process. The gasifier ran at 550°C–700°Cwith an air equivalence ratio (ER) of 0.2–0.4. The temperature of the swirl melting furnace reached about 1240°C when the gasification ER was 0.3 and the total ER was 1.1. At these conditions, the fly ash concentration in the flue gas was 1.7 g·(Nm ) , which meant over 95% fly ash was trapped in the furnace and discharged as slag. 85% of Ni and Cr were bound in the slag, as well as 60% of Cu. The mass and energy balance analysis indicates that the boiler heat efficiency of an industrial MSW incineration plant reaches 86.97% when MSW is dried by steam of 200°C. The boiler heat efficiency is sensitive to three important parameters, including the temperature of preheated MSW, the moisture percentage of dried MSW and the fly ash percentage in the total ash.

关键词： municipal solid waste (MSW)     steam drying     gasification and melting    

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用于介观模拟电子束选区熔化的数据挖掘技术 Article

钱亚, 闫文韬, 林峰

《工程（英文）》 2019年 第5卷 第4期   页码 746-754 doi: 10.1016/j.eng.2019.06.006

摘要：

 在电子束选区熔化技术（EBSM）工艺中，制造部件的性质受到每一道熔道沉积质量的影响。然而，熔道的形成受到各种物理现象和工艺参数的支配，这些参数之间的相关性十分复杂，难以通过实验得出。近来，介观建模技术已成为模拟电子束（EB）熔化过程以及揭示特定熔道形貌的形成机制的手段。尽管如此，人们对工艺参数与熔道特征之间的相关性尚未有定量的理解。本文从介观模拟的结果出发，研究了熔道的形态特征，同时引入了熔道宽度和高度等关键性描述指标，以便从数值上评估沉积质量。本文还定量研究了各种工艺参数的影响，从而导出了工艺条件和熔道特征之间的相关性。最后，本文提出了一种由介观建模和数据挖掘技术组成的仿真驱动优化框架，并讨论了框架的潜力和局限性。

关键词： 电子束选区熔化     介观模型     数据挖掘    

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Investigating peak stresses in fitting and repair patches of buried polyethylene gas pipes

Reza KHADEMI ZAHEDI, Pouyan ALIMOURI, Hooman KHADEMI ZAHEDI, Mohammad SHISHESAZ

《结构与土木工程前沿（英文）》 2020年 第14卷 第1期   页码 147-168 doi: 10.1007/s11709-019-0587-6

摘要： Nowadays, polyethylene composes a large number of natural gas distribution pipelines installed under the ground. The focus of the present contribution is two fold. One of the objectives is to investigate the applicability of polyethylene fittings in joining polyethylene gas pipes which are electrofused onto the pipe ends and buried under the ground, by estimating stress distribution using finite element method. The second objective is to study the effectiveness of polyethylene repair patches which are used to mend the defected pipelines by performing a finite element analysis to calculate peak stress values. Buried polyethylene pipelines in the natural gas industry, can be imposed by sever loadings including the soil-structure interaction, traffic load, soil’s column weight, internal pressure, and thermal loads resulting from daily and/or seasonal temperature changes. Additionally, due to the application of pipe joints, and repair patches local stresses superimposed on the aforementioned loading effects. The pipe is assumed to be made of PE80 resin and its jointing socket, and the repair patch is PE100 material. The computational analysis of stresses and the computer simulations are performed using ANSYS commercial software. According to the results, the peak stress values take place in the middle of the fitting and at its internal surface. The maximum stress values in fitting and pipe are below the allowable stresses which shows the proper use of introduced fitting is applicable even in hot climate areas of Ahvaz, Iran. Although the buried pipe is imposed to the maximum values of stresses, the PE100 socket is more sensitive to a temperature drop. Furthermore, all four studied patch arrangements show significant reinforcing effects on the defected section of the buried PE gas pipe to transfer applied loads. Meanwhile, the defected buried medium density polyethylene gas pipe and its saddle fused patch can resist the imposed mechanical and thermal loads of 22°C temperature increase. Moreover, increasing the saddle fusion patch length to 12 inches reduces the maximum stress values in the pipe, significantly.

关键词： Ansys software     polyethylene     buried pipelines     polyethylene joints     polyethylene patches     peak von Mises stress     soil-pipe interaction     temperature variation    

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Differences in microstructure and properties between selective laser melting and traditional manufacturing

Bo SONG,Xiao ZHAO,Shuai LI,Changjun HAN,Qingsong WEI,Shifeng WEN,Jie LIU,Yusheng SHI

《机械工程前沿（英文）》 2015年 第10卷 第2期   页码 111-125 doi: 10.1007/s11465-015-0341-2

摘要：

Selective laser melting (SLM), as one of the additive manufacturing technologies, is widely investigated to fabricate metal parts. In SLM, parts are manufactured directly from powders in a layer-by-layer fashion; SLM also provides several advantages, such as production of complex parts with high three-dimensional accuracy, compared with other additive manufacturing technologies. Therefore, SLM can be applied in aeronautics, astronautics, medicine, and die and mould industry. However, this technique differs from traditional methods, such as casting and forging; for instance, the former greatly differs in terms of microstructure and properties of products. This paper summarizes relevant studies on metal material fabrication through SLM. Based on a work completed in Huazhong Univ. Sci Tech., Rapid Manuf. Center (HUST-RMC) and compared with characteristics described in other reported studies, microstructure, properties, dimensional accuracy, and application of SLM are presented.

关键词： selective laser melting     microstructure     performance     application    

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Control of peak pressures of an HCCI engine under varying swirl and operating parameters

T. KARTHIKEYA SHARMA,G. AMBA PRASAD RAO,K. MADHU MURTHY

《能源前沿（英文）》 2016年 第10卷 第3期   页码 337-346 doi: 10.1007/s11708-016-0401-2

摘要： The major advantages of homogeneous charge compression ignition (HCCI) are high efficiency in combination with low NO -emissions. However, one of the major challenges with HCCI is the control of higher peak pressures which may damage the engine, limiting the HCCI engine life period. In this paper, an attempt is made to analyze computationally the effect of induction swirl in controlling the peak pressures of an HCCI engine under various operating parameters. A single cylinder 1.6 L reentrant piston bowl diesel engine is chosen. For computational analysis, the ECFM-3Z model of STAR –CD is considered because it is suitable for analyzing the combustion processes in SI and CI engines. As an HCCI engine is a hybrid version of SI and CI engines, the ECFM-3Z model with necessary modifications is used to analyze the peak pressures inside the combustion chamber. The ECFM-3Z model for HCCI mode of combustion is validated with the existing literature to make sure that the results obtained are accurate. Numerical experiments are performed to study the effect of varying properties like speed of the engine, piston bowl geometry, exhaust gas recirculation (EGR) and equivalence ratio under different swirl ratios in controlling the peak pressures inside the combustion chamber. The results show that the swirl ratio has a considerable impact on controlling the peak pressures of HCCI engine. A reduction in peak pressures are observed with a swirl ratio of 4 because of reduced in cylinder temperatures. The combined effect of four operating parameters, i.e., the speed of the engine, piston bowl geometry, EGR, and equivalence ratio with swirl ratios suggest that lower intake temperatures, reentrant piston bowl, higher engine speeds and higher swirl ratios are favorable in controlling the peak pressures.

关键词： HCCI engine     ECFM-3Z     Swirl ratio     peak pressures     engine speed     piston bowl geometry    

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Build orientation determination of multi-feature mechanical parts in selective laser melting via multi-objective

《机械工程前沿（英文）》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0737-8

摘要： Selective laser melting (SLM) is a unique additive manufacturing (AM) category that can be used to manufacture mechanical parts. It has been widely used in aerospace and automotive using metal or alloy powder. The build orientation is crucial in AM because it affects the as-built part, including its part accuracy, surface roughness, support structure, and build time and cost. A mechanical part is usually composed of multiple surface features. The surface features carry the production and design knowledge, which can be utilized in SLM fabrication. This study proposes a method to determine the build orientation of multi-feature mechanical parts (MFMPs) in SLM. First, the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives. Second, the estimation models of involved optimization objectives are established, and a set of alternative build orientations (ABOs) is further obtained by many-objective optimization. Lastly, a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs. The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process. Two case studies are reported to validate the proposed method with numerical results, and the effectiveness comparison is presented. Physical manufacturing is conducted to prove the performance of the proposed method. The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82, 10.84, and 10.62 μm, respectively. The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.

关键词： selective laser melting (SLM)     build orientation determination     multi-feature mechanical part (MFMP)     fuzzy analytical hierarchy process     multi-objective decision making (MODM)    

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峰谷电价体制下东北输油管网日输油优化研究

崔慧,吴长春,吴江林,孙青峰

《中国工程科学》 2004年 第6卷 第8期   页码 69-73

摘要：

东北原油长输管网是中国规模最大的地区性原油运输系统，就该管网基于峰谷电价体制下的运行现状，建立了线性规划数学模型，提出了日输油计划优化问题，并以铁秦线为例进行分析；初步揭示了峰谷电价体制下日输油计划方式的一些基本规律， 表明在该体制下东北管网具有一定的节能降耗潜力。但该方式在一定程度上受到管道本身运行特性的约束，与热油管道相比它更适合于等温管道。

关键词： 东北管网     峰谷电价     日输油     优化    

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Peak CO

Sheng ZHOU, Maosheng DUAN, Zhiyi YUAN, Xunmin OU

《能源前沿（英文）》 2020年 第14卷 第4期   页码 740-758 doi: 10.1007/s11708-018-0558-y

摘要： This paper studies the pathways of peaking CO emissions of Dezhou city in China, by employing a bottom-up sector analysis model and considering future economic growth, the adjustment of the industrial structure, and the trend of energy intensity. Two scenarios (a business-as-usual (BAU) scenario and a CO mitigation scenario (CMS)) are set up. The results show that in the BAU scenario, the final energy consumption will peak at 25.93 million tons of coal equivalent (Mtce) (16% growth versus 2014) in 2030. In the CMS scenario, the final energy will peak in 2020 at 23.47 Mtce (9% lower versus peak in the BAU scenario). The total primary energy consumption will increase by 12% (BAU scenario) and decrease by 3% (CMS scenario) in 2030, respectively, compared to that in 2014. In the BAU scenario, CO emission will peak in 2025 at 70 million tons of carbon dioxide (MtCO ), and subsequently decrease gradually in 2030. In the CMS scenario, the peak has occurred in 2014, and 60 MtCO will be emitted in 2030. Active policies including restructuring the economy, improving energy efficiency, capping coal consumption, and using more low-carbon /carbon free fuel are recommended in Dezhou city peaked CO emission as early as possible.

关键词： carbon dioxide emission     energy consumption     peak CO2 emission     low-carbon transition     Dezhou city     China    

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A comprehensive simulator for assessing the reliability of a photovoltaic panel peak power tracking system

Nabil KAHOUL,Mourad HOUABES,Ammar NEÇAIBIA

《能源前沿（英文）》 2015年 第9卷 第2期   页码 170-179 doi: 10.1007/s11708-015-0353-y

摘要： When designing a maximum power point tracking (MPPT) algorithm, it is often difficult to correctly predict, before field testing, the behavior of this MPPT under varying solar irradiation on photovoltaic (PV) panels. A solution to this problem is to design a maximum power point trackers simulator of a PV system used to test MPPT algorithms. This simulator must have the same role as the MPPT card of the PV panel and thus will fully emulate the response of a real MPPT card of the PV panel. Therefore, it is a good substitute to help to test the peak power trackers of the PV system in the laboratory. This paper describes a simple peak power trackers simulator of the PV system which has a short response time thus, can be used to test MPPT algorithms under very rapid variation condition. The obtained results and the theoretical operation confirm the reliability and the superior performance of the proposed model.

关键词： photovoltaic module     DC-DC converter     design     maximum power point tracking (MPPT) card     microprocessor    

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标题 作者 时间 类型 操作

Investigation on multiple-melting behavior of nano-CaCO3/polypropylene composites

LIN Zhidan, ZENG Chunlian, MAI Kancheng

期刊论文

Study on the crystal morphology and melting behavior of isothermally crystallized composites of short

Mingtao RUN, Hongzan SONG, Yanping HAO

期刊论文

Room temperature liquid metal: its melting point, dominating mechanism and applications

Junheng FU, Chenglin ZHANG, Tianying LIU, Jing LIU

期刊论文

Phase change effect of low melting point metal for an automatic cooling of USB flash memory

Haoshan GE, Jing LIU

期刊论文

Factors influencing peak bone mass gain

Xiaowei Zhu, Houfeng Zheng

期刊论文

Zero increase in peak discharge for sustainable development

Xing Fang, Junqi Li, Yongwei Gong, Xiaoning Li

期刊论文

A steam dried municipal solid waste gasification and melting process

Gang XIAO, Baosheng JIN, Mingjiang NI, Kefa CEN, Yong CHI, Zhongxin TAN

期刊论文

用于介观模拟电子束选区熔化的数据挖掘技术

钱亚, 闫文韬, 林峰

期刊论文

Investigating peak stresses in fitting and repair patches of buried polyethylene gas pipes

Reza KHADEMI ZAHEDI, Pouyan ALIMOURI, Hooman KHADEMI ZAHEDI, Mohammad SHISHESAZ

期刊论文

Differences in microstructure and properties between selective laser melting and traditional manufacturing

Bo SONG,Xiao ZHAO,Shuai LI,Changjun HAN,Qingsong WEI,Shifeng WEN,Jie LIU,Yusheng SHI

期刊论文

Control of peak pressures of an HCCI engine under varying swirl and operating parameters

T. KARTHIKEYA SHARMA,G. AMBA PRASAD RAO,K. MADHU MURTHY

期刊论文

Build orientation determination of multi-feature mechanical parts in selective laser melting via multi-objective

期刊论文

峰谷电价体制下东北输油管网日输油优化研究

崔慧,吴长春,吴江林,孙青峰

期刊论文

Peak CO

Sheng ZHOU, Maosheng DUAN, Zhiyi YUAN, Xunmin OU

期刊论文

A comprehensive simulator for assessing the reliability of a photovoltaic panel peak power tracking system

Nabil KAHOUL,Mourad HOUABES,Ammar NEÇAIBIA

期刊论文