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Importance of emulsions in crystallization—applications for fat crystallization

Sandra PETERSEN, K. CHALEEPA, Joachim ULRICH

《化学科学与工程前沿（英文）》 2013年第7卷第1期页码 43-48 doi: 10.1007/s11705-013-1309-6

摘要： Emulsions and crystallization are two independent research topics which normally do not overlap although a combination of the two could be applicable to many areas. Here, the importance of emulsions in the field of fat crystallization is described. Three applications with industrial relevance were chosen for investigation: fat fractionation, the solidification of phase change materials and solid lipid nanoparticles. For fat fractionation and phase change materials, emulsification can be applied as a tool to improve the fat crystallization process, and thus the product quality of the crystallized fat. Furthermore, the use of emulsification creates new application fields such as solid lipid nanoparticles in the area of fat crystallization.

关键词： emulsion fat crystallization phase change material emulsion fractionation emulsion solidification

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乳化炸药结构与稳定性关系的研究

汪旭光,申英锋

《中国工程科学》 2000年第2卷第2期页码 24-29

摘要：

文章从结构角度出发，系统分析了乳化炸药乳胶体稳定性的各个因素，并得出了零渗透压体系在结构上最为稳定的结论。实验测定表明，几种较稳定的乳胶配方均接近为零渗透压体系。

关键词：乳化炸药结构稳定性

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Premature melt solidification during mold filling and its influence on the as-cast structure

M. WU, M. AHMADEIN, A. LUDWIG

《机械工程前沿（英文）》 2018年第13卷第1期页码 53-65 doi: 10.1007/s11465-017-0437-y

摘要：

Premature melt solidification is the solidification of a melt during mold filling. In this study, a numerical model is used to analyze the influence of the pouring process on the premature solidification. The numerical model considers three phases, namely, air, melt, and equiaxed crystals. The crystals are assumed to have originated from the heterogeneous nucleation in the undercooled melt resulting from the first contact of the melt with the cold mold during pouring. The transport of the crystals by the melt flow, in accordance with the so-called “big bang” theory, is considered. The crystals are assumed globular in morphology and capable of growing according to the local constitutional undercooling. These crystals can also be remelted by mixing with the superheated melt. As the modeling results, the evolutionary trends of the number density of the crystals and the volume fraction of the solid crystals in the melt during pouring are presented. The calculated number density of the crystals and the volume fraction of the solid crystals in the melt at the end of pouring are used as the initial conditions for the subsequent solidification simulation of the evolution of the as-cast structure. A five-phase volume-average model for mixed columnar-equiaxed solidification is used for the solidification simulation. An improved agreement between the simulation and experimental results is achieved by considering the effect of premature melt solidification during mold filling. Finally, the influences of pouring parameters, namely, pouring temperature, initial mold temperature, and pouring rate, on the premature melt solidification are discussed.

关键词： premature solidification mold filling as-cast structure modeling

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Analysis of molten metal spreading and solidification behaviors utilizing moving particle full-implicit

《能源前沿（英文）》 2021年第15卷第4期页码 959-973 doi: 10.1007/s11708-021-0753-0

摘要： To retrieve the fuel debris in Fukushima Daiichi Nuclear Power Plants (1F), it is essential to infer the fuel debris distribution. In particular, the molten metal spreading behavior is one of the vital phenomena in nuclear severe accidents because it determines the initial condition for further accident scenarios such as molten core concrete interaction (MCCI). In this study, the fundamental molten metal spreading experiments were performed with different outlet diameters and sample amounts to investigate the effect of the outlet for spreading-solidification behavior. In the numerical analysis, the moving particle full-implicit method (MPFI), which is one of the particle methods, was applied to simulate the spreading experiments. In the MPFI framework, the melting-solidification model including heat transfer, radiation heat loss, phase change, and solid fraction-dependent viscosity was developed and implemented. In addition, the difference in the spreading and solidification behavior due to the outlet diameters was reproduced in the calculation. The simulation results reveal the detailed solidification procedure during the molten metal spreading. It is found that the viscosity change and the solid fraction change during the spreading are key factors for the free surface condition and solidified materials. Overall, it is suggested that the MPFI method has the potential to simulate the actual nuclear melt-down phenomena in the future.

关键词： molten metal spreading solidification particle method severe accident fuel debris decommissioning

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Novel technologies for the lost foam casting process

Wenming JIANG, Zitian FAN

《机械工程前沿（英文）》 2018年第13卷第1期页码 37-47 doi: 10.1007/s11465-018-0473-2

摘要：

Lost foam casting (LFC) is a green precision casting process categorized as a near net forming technology. Yet, despite its popularity, it still suffers from some technological problems, such as poor filling ability of the castings, coarse and non-dense microstructure, low mechanical properties for the Al and Mg LFC processes, and defective carburization for the low carbon steel LFC process. These drawbacks restrict the development and widespread application of the LFC process. To solve these problems, the present study developed several novel LFC technologies, namely, LFC technologies under vacuum and low pressure, vibration solidification, and pressure solidification conditions; expendable shell casting techno- logy; and preparation technology of bimetallic castings based on the LFC process. The results showed that the LFC under vacuum and low pressure evidently improved the filling ability and solved the oxidization problem of the alloys, which is suitable for producing complex and thin-wall castings. The vibration and pressure solidifications increased the compactness of the castings and refined the microstructure, significantly improving the mechanical properties of the castings. The expendable shell casting technology could solve the pore, carburization, and inclusion defects of the traditional LFC method, obtaining castings with acceptable surface quality. Moreover, the Al/Mg and Al/Al bimetallic castings with acceptable metallurgical bonding were successfully fabricated using the LFC process. These proposed novel LFC technologies can solve the current technological issues and promote the technological progress of the LFC process.

关键词： LFC under vacuum and low pressure vibration solidification pressure solidification expendable shell casting bimetallic castings

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Cement-based solidification/stabilization of contaminated soils by nitrobenzene

Jianguo LIU, Xiaoqin NIE, Xianwei ZENG, Zhaoji SU

《环境科学与工程前沿（英文）》 2012年第6卷第3期页码 437-443 doi: 10.1007/s11783-012-0406-y

摘要： The cement-based solidification/stabilization (S/S) of nitrobenzene (NB) contaminated soils, with cement and lime as binders, sodium silicate solution and powder activated carbon (PAC) as additives, was optimized through an orthogonal experiment, and S/S efficiency was estimated by both leaching test and volatilization measurement. The leaching test results showed that the factors affecting S/S efficiency were NB concentration, cement-to-lime ratio and binder-to-soils ratio, in sequence. With increasing curing time, the leaching concentration of NB between different levels of the same factor in the orthogonal experiment decreased, and less than 9% NB leached out from the 28 d cured samples. The volatilization measurement results indicated that 0.5‰ of NB was volatilized during the mixing and curing processes for the samples without PAC in the 28 d cycle, whereas adding 2 wt% and 5 wt% PAC, with respect to the weight of contaminated soils, could reduce NB volatilization to half of its original values either during the mixing or curing process. The optimizing formula, that is, contaminated soils (dry weight):cement:lime= 100:25:25, with 5 wt% additional sodium silicate and 2 wt% additional PAC, was applied to the engineering application of NB contaminated soils. Both the leaching test results of the product and the ambient air quality monitoring results met related regulations during the treating process.

关键词： solidification/stabilization nitrobenzene contaminated soils powder activated carbon

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Improvement of solidification model and analysis of 3D channel blockage with MPS method

《能源前沿（英文）》 2021年第15卷第4期页码 946-958 doi: 10.1007/s11708-021-0754-z

摘要： In a severe accident of a nuclear power reactor, coolant channel blockage by solidified molten core debris may significantly influence the core degradations that follow. The moving particle semi-implicit (MPS) method is one of the Lagrangian-based particle methods for analyzing incompressible flows. In the study described in this paper, a novel solidification model for analyzing melt flowing channel blockage with the MPS method has been developed, which is suitable to attain a sufficient numerical accuracy with a reasonable calculation cost. The prompt velocity diffusion by viscosity is prioritized over the prompt velocity correction by the pressure term (for assuring incompressibility) within each time step over the “mushy zone” (between the solidus and liquidus temperature) for accurate modeling of solidification before fixing the coordinates of the completely solidified particles. To sustain the numerical accuracy and stability, the corrective matrix and particle shifting techniques have been applied to correct the discretization errors from irregular particle arrangements and to recover the regular particle arrangements, respectively. To validate the newly developed algorithm, 2-D benchmark analyses are conducted for steady-state freezing of the water in a laminar flow between two parallel plates. Furthermore, 3-D channel blockage analyses of a boiling water reactor (BWR) fuel support piece have been performed. The results show that a partial channel blockage develops from the vicinity of the speed limiter, which does not fully develop into a complete channel blockage, but still diverts the incoming melt flow that follows to the orifice region.

关键词： boiling water reactor (BWR) severe accident channel blockage moving particle semi-implicit (MPS) method solidification

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凝固科学技术与材料

傅恒志,魏炳波,郭景杰

《中国工程科学》 2003年第5卷第8期页码 1-15

摘要：

从凝固科学与实践发展的角度介绍了当前凝固材料体系的基本框架和凝固科学主要发展阶段的基本理论。作为材料科学与工程的基本组成，凝固科学技术正在现代科学理论的基础上针对传统材料的改性提高和新材料的发展需求，以控形、控构、控性为目标开展优质铸件的定向、晶体生长、快凝、深过冷及各种新型和超常领域凝固过程的研究，并介绍了其中某些方面和展望了可能的发展趋势。

关键词：材料科学凝固技术凝固过程

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Performance and emission characteristics of a diesel engine operating on different water in diesel emulsion

Seyed Saeed HOSEINI, Mohammad Amin SOBATI

《能源前沿（英文）》 2019年第13卷第4期页码 636-657 doi: 10.1007/s11708-019-0646-7

摘要： The nitrogen oxide (NO ) release of diesel engines can be reduced using water in diesel emulsion fuel without any engine modification. In the present paper, different formulations of water in diesel emulsion fuels were prepared by ultrasonic irradiation. The water droplet size in the emulsion, polydisperisty index, and the stability of prepared fuel was examined, experimentally. Afterwards, the performance characteristics and exhaust emission of a single cylinder air-cooled diesel engine were investigated using different water in diesel emulsion fuels. The effect of water content (in the range of 5%–10% by volume), surfactant content (in the range of 0.5%–2% by volume), and hydrophilic-lipophilic balance (HLB) (in the range of 5–8) was examined using Box-Behnken design (BBD) as a subset of response surface methodology (RSM). Considering multi-objective optimization, the best formulation for the emulsion fuel was found to be 5% water, 2% surfactant, and HLB of 6.8. A comparison was made between the best emulsion fuel and the neat diesel fuel for engine performance and emission characteristics. A considerable decrease in the nitrogen oxide emission (–18.24%) was observed for the best emulsion fuel compared to neat diesel fuel.

关键词： water in diesel emulsion fuel hydrophilic-lipophilic balance (HLB) response surface methodology (RSM) emulsion stability engine performance exhaust emission

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Directional solidification of metal-gas eutectic and fabrication of regular porous metals

LIU Yuan, LI Yanxiang, WAN Jiang

《机械工程前沿（英文）》 2007年第2卷第2期页码 180-183 doi: 10.1007/s11465-007-0030-x

摘要： Directional solidification of metal-gas eutectic (Gasar) is a novel process for making regular porous metals. This process is based on a solid-gas eutectic reaction involving a gaseous medium and a metal or ceramic phase. The process easily controls the porosity, the pore size, the pore orientation, and the pore morphology when the melting and solidifying conditions are varied in a wide range. The latest progress and our research work are reviewed in this paper.

关键词： orientation solid-gas eutectic research solidifying porosity

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材料的成形加工与凝固技术

介万奇

《中国工程科学》 2002年第4卷第6期页码 1-4

摘要：

从对材料成形加工技术进步的分析入手，论述了凝固技术在材料先进成形加工技术中的应用及其重要性。结合对几种凝固新技术的实例的分析指出，不论是传统材料加工过程“控形—控性（控制组织）—控制成本—控制污染”一体化新技术，还是作为新材料研制手段，凝固技术的重要性均是非常突出的。进而分析了近年来受到广泛重视的凝固过程研究的新课题及其由此可能带来的技术进步。

关键词：材料成形加工凝固技术

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金属凝固显微组织的计算机模拟

朱鸣芳,于金,洪俊杓

《中国工程科学》 2004年第6卷第5期页码 8-16

摘要：

应用计算机数值模拟技术研究金属凝固显微组织的形成规律是材料科学发展的重要前沿领域之一。文章对该领域的最新研究进展作了简要评述；重点介绍了作者发展的一个改进的MCA(modified cellular automaton)模型的特点以及应用该模型在合金凝固组织数值模拟方面的一些主要工作。

关键词：凝固显微组织计算机模拟 cellular automaton模型

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An integrated method for the rapid dewatering and solidification/stabilization of dredged contaminated

Hefu Pu, Aamir Khan Mastoi, Xunlong Chen, Dingbao Song, Jinwei Qiu, Peng Yang

《环境科学与工程前沿（英文）》 2021年第15卷第4期 doi: 10.1007/s11783-020-1359-1

摘要： Abstract • An integrated method, called PHDVPSS, was proposed for treating DCS. • The PHDVPSS method showed superior performance compared to conventional method. • Using the method, water content (%) of DCS decreased from 300 to<150 in 3 days. • The 56-day UCS from this method is 12‒17 times higher than conventional method. • Relative to PC, GGBS-MgO binder yielded greater reduction in the leachability. To more efficiently treat the dredged contaminated sediment (DCS) with a high water content, this study proposes an integrated method (called PHDVPSS) that uses the solidifying/stabilizing (S/S) agents and prefabricated horizontal drain (PHD) assisted by vacuum pressure (VP). Using this method, dewatering and solidification/stabilization can be carried out simultaneously such that the treatment time can be significantly shortened and the treatment efficacy can be significantly improved. A series of model tests was conducted to investigate the effectiveness of the proposed method. Experimental results indicated that the proposed PHDVPSS method showed superior performance compared to the conventional S/S method that uses Portland cement (PC) directly without prior dewatering. The 56-day unconfined compressive strength of DCS treated by the proposed method with GGBS-MgO as the binder is 12‒17 times higher than that by the conventional S/S method. DCS treated by the PHDVPSS method exhibited continuous decrease in leaching concentration of Zn with increasing curing age. The reduction of Zn leachability is more obvious when using GGBS-MgO as the binder than when using PC, because GGBS-MgO increased the residual fraction and decreased the acid soluble fraction of Zn. The microstructure analysis reveals the formation of hydrotalcite in GGBS-MgO binder, which resulted in higher mechanical strength and higher Zn stabilization efficiency.

关键词： Dredged contaminated sediment Dewatering Solidification/stabilization Vacuum preloading Prefabricated horizontal drain Heavy metal

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Optimising the oil phases of aluminium hydrogel-stabilised emulsions for stable, safe and efficient vaccine adjuvant

《化学科学与工程前沿（英文）》 2022年第16卷第6期页码 973-984 doi: 10.1007/s11705-021-2123-1

摘要： To increase antibody secretion and dose sparing, squalene-in-water aluminium hydrogel (alum)-stabilised emulsions (ASEs) have been developed, which offer increased surface areas and cellular interactions for higher antigen loading and enhanced immune responses. Nevertheless, the squalene (oil) in previous attempts suffered from limited oxidation resistance, thus, safety and stability were compromised. From a clinical translational perspective, it is imperative to screen the optimal oils for enhanced emulsion adjuvants. Here, because of the varying oleic to linoleic acid ratio, soybean oil, peanut oil, and olive oil were utilised as oil phases in the preparation of aluminium hydrogel-stabilised squalene-in-water emulsions, which were then screened for their stability and immunogenicity. Additionally, the underlying mechanisms of oil phases and emulsion stability were unravelled, which showed that a higher oleic to linoleic acid ratio increased anti-oxidative capabilities but reduced the long-term storage stability owing to the relatively low zeta potential of the prepared droplets. As a result, compared with squalene-in-water ASEs, soybean-in-water ASEs exhibited comparable immune responses and enhanced stability. By optimising the oil phase of the emulsion adjuvants, this work may offer an alternative strategy for safe, stable, and effective emulsion adjuvants.

关键词： pickering emulsion vaccine adjuvant alum-stabilised emulsion oleic to linoleic acid ratio stability

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铸件凝固过程的宏观及微观模拟仿真研究进展

柳百成

《中国工程科学》 2000年第2卷第9期页码 29-37

摘要：

面向市场经济，迎接全球化竞争的挑战，为国民经济的发展作贡献，就要十分重视制造业特别是铸造行业的发展。但是，我国铸造行业与国外相比有很大差距，它制约着国民经济的发展。世界各国在铸造成形加工技术的发展趋势方面，认识是一致的，即：一是大型工程中特大型铸件的关键铸造技术；二是向精确成形技术方向发展；三是用计算机模拟仿真逐步代替传统的经验性研究方法。铸造过程计算机模拟仿真是改造传统铸造产业的必由之路，是当今世界各国专家学者关注的热点。铸造充型凝固过程的数值模拟可以帮助工程技术.人员优化工艺设计，缩短试制周期、降低生产成本、确保铸件质量，已成为铸造领域最热门的研究课题之一。目前，凝固过程的流场、温度场数值模拟及缩孔缩松预测已应用于实际生产，应力分析、微观组织模拟等方面的基础研究及实用化进程都取得了很大进展。

关键词：铸造凝固过程模拟仿真净形铸造