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Lateral displacement of soft ground under vacuum pressure and surcharge load

Chin-Yee ONG, Jin-Chun CHAI

《结构与土木工程前沿（英文）》 2011年第5卷第2期页码 239-248 doi: 10.1007/s11709-011-0110-1

摘要： Surcharge load (e.g. embankment fill) will induce settlement and outward lateral displacement, while vacuum pressure will induce settlement and inward lateral displacement of a ground. Ideally, combination of surcharge load and vacuum pressure can reduce or minimize the lateral displacement. Laboratory large scale model (length: 1.50 m, width: ~0.62 m, height: 0.85 m) tests and finite element analyses (FEA) were conducted to investigate the main influencing factors on lateral displacement of a soft clayey ground under the combination of vacuum pressure and surcharge load. For the conditions investigated, the results indicate that the outward lateral displacement increases with the increase of the ratio of surcharge load to vacuum pressure ( ) and the loading rate of the surcharge load ( ). Also, it is shown that for a given and condition, lateral displacement reduces with the increase of the initial undrained shear strength ( ) of the ground. To predict the lateral displacement of a ground under the combination of surcharge load and vacuum pressure, the loading conditions in terms of and , and value of the ground have to be considered.

关键词： vacuum consolidation lateral displacement PVD finite element analysis surcharge load

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Numerical study of conduction and radiation heat losses from vacuum annulus in parabolic trough receivers

Dongqiang LEI, Yucong REN, Zhifeng WANG

《能源前沿（英文）》 2022年第16卷第6期页码 1048-1059 doi: 10.1007/s11708-020-0670-7

摘要： Parabolic trough receiver is a key component to convert solar energy into thermal energy in the parabolic trough solar system. The heat loss of the receiver has an important influence on the thermal efficiency and the operating cost of the power station. In this paper, conduction and radiation heat losses are analyzed respectively to identify the heat loss mechanism of the receiver. A 2-D heat transfer model is established by using the direct simulation Monte Carlo method for rarefied gas flow and heat transfer within the annulus of the receiver to predict the conduction heat loss caused by residual gases. The numerical results conform to the experimental results, and show the temperature of the glass envelope and heat loss for various conditions in detail. The effects of annulus pressure, gas species, temperature of heat transfer fluid, and annulus size on the conduction and radiation heat losses are systematically analyzed. Besides, the main factors that cause heat loss are analyzed, providing a theoretical basis for guiding the improvement of receiver, as well as the operation and maintenance strategy to reduce heat loss.

关键词： parabolic trough receiver vacuum annulus rarefied gas DSMC (direct simulation Monte Carlo) heat loss

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interconnected nano-channels into polyvinylidene fluoride membranes for desalination applications by vacuum

《化学科学与工程前沿（英文）》 2023年第17卷第9期页码 1162-1182 doi: 10.1007/s11705-022-2276-6

摘要： In the present research, for the first time, lycopodium as a novel nanofiller was incorporated into a polyvinylidene fluoride matrix to fabricate lycopodium/polyvinylidene fluoride flat-sheet membrane for desalination applications by vacuum membrane distillation process. The prepared lycopodium/polyvinylidene fluoride membranes and lycopodium were characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared, energy dispersive X-ray, and mapping analyses. Water contact angle and liquid entry pressure measurements were also performed. Response surface methodology was applied to optimize membrane structure and performance. The optimized lycopodium/polyvinylidene fluoride membrane exhibits superior performance compared to the neat polyvinylidene fluoride membrane in terms of flux, salt rejection, water contact angle, and hydrophobicity. In vacuum membrane distillation experiments, using a 15000 ppm NaCl solution as a feed at 70 °C, the neat polyvinylidene fluoride membrane, optimum membrane, and agglomerated membrane (with high lycopodium loading) demonstrated 3.80, 25.20, and 14.83 LMH flux and 63.30%, 99.99%, 99.96% salt rejection, respectively. This improvement in flux and salt rejection of the optimized membrane was related to the presence of lycopodium with hydrophobic nature and interconnected nano-channels in membrane structure. It was found that lycopodium, as the most hydrophobic material, effectively influences the membrane performance and structure for membrane distillation applications.

关键词： lycopodium hydrophobicity vacuum membrane distillation desalination

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Novel methods by using non-vacuum insulated tubing to extend the lifetime of the tubing

Chenglong ZHOU,Guojin ZHU,Yongxiang XU,Jifei YU,Xiaoliang ZHANG,Hongzhi SHENG

《能源前沿（英文）》 2015年第9卷第2期页码 142-147 doi: 10.1007/s11708-015-0357-7

摘要： The analysis of the failure mechanics, namely hydrogen permeation of vacuum insulated tubing (VIT), indicated that the failure of VIT could be decreased but could not be avoided. To solve this problem, some measures by using non-vacuum materials were proposed and analyzed in this paper. The results show that to fill the tubing with foam-glass beads or high pressure argon may lead to a good performance.

关键词： vacuum insulated tubing cyclic steam stimulation insulation material thermal conductivity foam-glass hydrogen permeation

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Toward better understanding vacuum ultraviolet–iodide induced photolysis via hydrogen peroxide formation

《环境科学与工程前沿（英文）》 2022年第16卷第5期 doi: 10.1007/s11783-021-1489-0

摘要：

• UV/VUV/I^– induces substantial H₂O₂ and IO₃^– formation, but UV/I^– does not.

关键词： Vacuum ultraviolet Hydrogen peroxide Iodate Hydroxyl radical Redox transition

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高频真空木材干燥的模糊神经网络控制方法研究

姜滨,孙丽萍,曹军,周正

《中国工程科学》 2014年第16卷第4期页码 17-20

摘要：

高频真空木材干燥是一种干燥速度快、能源消耗低、环境污染小的新型联合干燥技术。在木材高频真空联合干燥过程的理论分析基础上，针对神经网络方法建立的木材干燥模型，设计了木材干燥模糊控制器和模糊神经网络控制器。对模糊控制和模糊神经网络两种控制方法进行了仿真实验，结果表明模糊神经网络方法控制效果更好，如温度上升快，控制精度高，稳定性好。模糊神经网络控制方法对实现木材干燥过程的全自动控制具有重要研究意义。

关键词：高频真空木材干燥模糊神经网络

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Enhancement of distillate output of double basin solar still with vacuum tubes

Hitesh N PANCHAL, P K SHAH

《能源前沿（英文）》 2014年第8卷第1期页码 101-109 doi: 10.1007/s11708-014-0299-5

摘要： The latent heat of condensation is lost to the atmosphere; hence it is not utilized to increase distillate output of single basin solar stills. This difficulty was overcome by attaching an additional basin to the main basin. The performance of the double basin solar still was also increased by attaching vacuum tubes to the lower basin; hence the lower basin possessed a higher temperature throughout the day. The latent heat of condensation of the bottom basin was also utilized to increase distillate. But the distillate output of the top basin was even lower compared with that of the bottom basin. This paper proposed a novel approach to increase the distillate output of the double basin solar still attached with vacuum tubes by introducing different sensible energy storage materials like pebbles, black granite gravel and calcium stones to increase the basin area. Experiments were conducted in climate conditions of Mehsana (23.6000° N, 72.4000° E) Gujarat from April to September 2013 with a constant water depth of 2 cm in the top basin with and without the use of basin materials. The results showed that the distillate output of basin material with calcium stones is greater (74%) compared with that of black granite gravel and pebbles. The integration of vacuum tubes with solar still greatly increases the distillate output of the solar still by providing hot water at the lower basin.

关键词： double basin solar still calcium stones pebbles granite gravel distillate output

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Molecular size characterization of heavy oil fractions in vacuum and solution by molecular dynamic simulation

Wenpo REN, Honggang CHEN, Chaohe YANG, Honghong SHAN,

《化学科学与工程前沿（英文）》 2010年第4卷第3期页码 250-256 doi: 10.1007/s11705-009-0281-7

摘要： Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography, respectively, and samples were collected to measure properties. According to the elemental analysis, molecular weight and H-NMR data, average molecular structures of polycyclic aromatic and heavy resin were constructed with improved Brown-Ladner (B-L) method and several corrections. And then, the most stable conformations of polycyclic aromatic and heavy resin in vacuum and toluene solution were obtained by molecular dynamic simulation, and the molecular size was gotten via the radius of gyration analysis. The results showed that the radius of gyration of polycyclic aromatic and heavy resin was 0.55–0.70 nm in vacuum and 0.60–0.90 nm in toluene solution. With molecular weight increasing, the molecular size in vacuum and toluene solution also increased. Due to the swelling behavior of solvent, the alkyl side chains of heavy oil molecule in solution were more stretched. Thus, the molecular size in toluene solution was larger than that in vacuum.

关键词： dynamic simulation molecular dynamic behavior molecule Adsorption Chromatography

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低真空管道高速磁悬浮系统技术发展研究

冯仲伟,方兴,李红梅,程爱君,潘永杰

《中国工程科学》 2018年第20卷第6期页码 105-111 doi: 10.15302/J-SSCAE-2018.06.017

摘要：

轮轨式是目前轨道交通技术体系的主流，但由于空气阻力、轮轨黏着、运行噪声等问题的限制，在现有的技术水平下，难以经济地实现运营速度大幅度提高。为满足更高经济运行速度的需求，在利用磁悬浮技术减少轮轨摩擦、振动的基础上，构建低真空运行环境以减小空气阻力和噪声是未来更高速度轨道交通技术发展的重要方向。本文阐述了发展低真空管道高速磁悬浮系统的意义，研究了其技术特点、发展现状，分析了低真空管道高速磁悬浮系统的科学问题和关键技术，并提出了在国家层面立项研究、建设试验线和国家级实验室的政策建议。

关键词：轨道交通低真空管道高速磁悬浮系统技术

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Vacuum promotes metabolic shifts and increases biogenic hydrogen production in dark fermentation systems

Haifa RAJHI,Daniel PUYOL,Mirna C. MARTÍNEZ,Emiliano E. DÍAZ,José L. SANZ

《环境科学与工程前沿（英文）》 2016年第10卷第3期页码 513-521 doi: 10.1007/s11783-015-0777-y

摘要： The successful operation of any type of hydrogen-producing bioreactor depends on the performance of the microorganisms present in the system. Both substrate and partial gas pressures are crucial factors affecting dark fermentation metabolic pathways. The main objective of this study was to evaluate the impact of both factors on hydrogen production using anaerobic granular sludge as inoculum and, secondly, to study the metabolic shifts of an anaerobic community subjected to low partial gas pressures. With this goal in mind, seven different wastewater (four synthetic media, two industrial wastewater, and one domestic effluent) and the effect of applying vacuum on the systems were analyzed. The application of vacuum promoted an increase in the diversity of hydrogen-producing bacteria, such as , and promoted the dominance of acetoclastic- over hydrogenotrophic methanogens. The application of different media promoted a wide variety of metabolic pathways. Nevertheless, reduction of the hydrogen partial pressure by application of vacuum lead to further oxidation of reaction intermediates irrespective of the medium used, which resulted in higher hydrogen and methane production, and improved the COD removal. Interestingly, vacuum greatly promoted biogenic hydrogen production from a real wastewater, which opens possibilities for future application of dark fermentation systems to enhance biohydrogen yields.

关键词： dark fermentation biohydrogen wastewaters vacuum

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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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FY-3B卫星微波湿度计热真空定标方法和结果分析

王振占,张升伟,李靖,李芸,吴琼

《中国工程科学》 2013年第15卷第10期页码 33-46

摘要：

本文论述了风云三号卫星B星微波湿度计（MWHS-3B）发射前热真空定标的原理和方法，建立了各种定标误差的修正算法，获得了MWHS-3B的系统线性度、观测不同目标的灵敏度和最终定标精度等关键技术指标。这些参数已经用于MWHS-3B在轨数据的处理。

关键词：风云三号卫星微波湿度计发射前定标热真空定标

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Multifunctional antimicrobial chlorhexidine polymers by remote plasma assisted vacuum deposition

Ana Mora-Boza, Francisco J. Aparicio, María Alcaire, Carmen López-Santos, Juan P. Espinós, Daniel Torres-Lagares, Ana Borrás, Angel Barranco

《化学科学与工程前沿（英文）》 2019年第13卷第2期页码 330-339 doi: 10.1007/s11705-019-1803-6

摘要： Novel antibacterial materials for implants and medical instruments are essential to develop practical strategies to stop the spread of healthcare associated infections. This study presents the synthesis of multifunctional antibacterial nanocoatings on polydimethylsiloxane (PDMS) by remote plasma assisted deposition of sublimated chlorhexidine powders at low pressure and room temperature. The obtained materials present effective antibacterial activity against K12, either by contact killing and antibacterial adhesion or by biocide agents release depending on the synthetic parameters. In addition, these multifunctional coatings allow the endure hydrophilization of the hydrophobic PDMS surface, thereby improving their biocompatibility. Importantly, cell-viability tests conducted on these materials also prove their non-cytotoxicity, opening a way for the integration of this type of functional plasma films in biomedical devices.

关键词： plasma polymers conformal plasma deposition chlorhexidine bactericide PDMS biocompatibility

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基于模糊数据融合的脉动真空灭菌控制系统设计

陈双叶

《中国工程科学》 2008年第10卷第7期页码 69-72

摘要：

以高性能单片机为核心，结合大规模可编程逻辑器件和在系统编程技术，设计了脉动真空灭菌控制系统的硬件和软件；采用模糊信息融合方法，设计了自适应模糊控制策略；针对包裹类灭菌物品，对系统进行了仿真试验研究，研究结果表明系统具有较好的控制效果和较强的抗干扰能力。

关键词：灭菌系统模糊控制单片机

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冷冻-萃取/真空干燥法制备坚固和耐疲劳的聚酰亚胺纤维气凝胶及其增强阻燃性复合材料 Article

姚恺清, 宋崇虎, 方红, 王峰, 陈炼, 蒋少华, 查国君, 侯豪情

《工程（英文）》 2023年第21卷第2期页码 152-161 doi: 10.1016/j.eng.2021.08.024

摘要：

在现代新材料的快速发展中，用节能、省时、低成本和简便的新型方法制备具有优良机械性能和热学性能的轻质、低密度和高孔隙率气凝胶十分必要。在本工作中，我们使用短切电纺聚酰亚胺（PI）纤维作为支撑骨架，通过开发出一种无需特殊干燥方法的真空干燥（VD）与冷冻-萃取相结合的方法，制备出高性能PI 纤维气凝胶（PIFAs）。所得PIFAs 具有低密度（≤52.8 mg⋅cm⁻³）和高孔隙率（>96%）。该PIFA在至少20 000 次的循环压缩过程中展现出高度的耐疲劳性及低能量损失系数。密度为39.1 mg⋅cm⁻³的PIFA具有40.4 mW⋅m⁻¹⋅K⁻¹的热导率。通过进一步使用聚硅氮烷对PIFAs复合改性后，其具备更强的耐火性和氮气氛围中的高残留率（>70%）。这些优异的性能使PIFAs 及其复合材料成为可应用于建筑工业、航空和航天工业轻质材料、隔热和防火层以及高温反应催化剂载体的可选材料。此外，本工作中提出的冷冻-萃取/VD法因其节能、省时和节约成本而可被拓展用于制备其他材料。

关键词：聚酰亚胺气凝胶冷冻萃取真空干燥机械性能隔热性能防火性能