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Flexural behavior of ECC hollow beams incorporating different synthetic fibers

Ahmmad A. ABBAS, Farid H. ARNA ’OT, Sallal R. ABID, Mustafa ÖZAKÇA

《结构与土木工程前沿（英文）》 2021年第15卷第2期页码 399-411 doi: 10.1007/s11709-021-0701-4

摘要： Twelve ECC beams with three different fiber types, along with four normal concrete beams, were tested in this study to evaluate the influence of cross-sectional hollowing on their flexural performance. The fiber types used were nylon monofilament (NM), low-cost untreated polyvinyl alcohol (PVA), and polypropylene (PP). Three different square hole sizes of 60, 80, and 100 mm with cross-sectional hollowing ratios of 0.16, 0.28, and 0.44, respectively, were adopted for each group of beams in addition to a solid beam. All beams were tested under four-point loading using a displacement-controlled testing machine. The test results showed that ECC beams can mostly withstand higher cracking and ultimate loads compared to their corresponding normal concrete versions. The results also showed that both the ductility and toughness of the ECC beams are higher than those of the normal concrete beams and that the ductility values of the hollow beams with a hole size of 60 mm are higher than those of the corresponding solid beams. Moreover, hollow ECC beams with hole sizes of 60 and 80 mm exhibited a higher ductility than a solid normal concrete beam.

关键词： hollow beam hollowing ratio ECC flexural strength ductility toughness

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步行激励下大跨度钢-混凝土空心板组合梁振动舒适度研究 Article

刘界鹏, 黄鉥, 李江, Y. Frank Chen

《工程（英文）》 2022年第19卷第12期页码 93-104 doi: 10.1016/j.eng.2021.04.025

摘要：

大跨度预制钢-混凝土空心板组合梁（CBHCS）是一种新型的楼板结构，可用于各种大跨度结构。然而，人为引起的振动会对此类结构的使用产生影响。为了减轻振动，需要探究由人引起的步行力与楼板状态之间的关系。本文首先使用测力板获取了25 名测试者的150 个步行力，确定了单步行走的傅里叶级数中的动态载荷系数和相位角。其次，对7 个CBHCS试样进行了行走测试，获取了模态振型、固有频率、阻尼比和加速度等基本动态特性。CBHCS楼板系统通常表现出高频（>10 Hz）和低阻尼（阻尼比低于2%）的特性。本文还使用有限元方法进行了灵敏度研究，以研究CBHCS楼板系统的振动性能，考虑了楼板厚度、
钢梁类型、接触时间和人体重量。最后，本文推导了基频和峰值加速度的解析表达式，与实验结果吻合较好，具有实际的应用价值。

关键词：组合梁空心板步行力楼板振动模态振型

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Nanostructured hollow spheres of hydroxyapatite: preparation and potential application in drug delivery

Xiaojing ZHANG, Weixin ZHANG, Zeheng YANG, Zhao ZHANG

《化学科学与工程前沿（英文）》 2012年第6卷第3期页码 246-252 doi: 10.1007/s11705-012-1299-9

摘要： A solvothermal method has been successfully used to prepare nanostructured hydroxyapatite (HA) hollow spheres with average diameters of about 500 nm and shell thicknesses of about 100 nm in a glycerin/water mixed solvent. Transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM) images show that the shells of the HA hollow spheres are actually composed of nanosheets with thicknesses of about 10 nm. By tuning the glycerin/water volume ratio, two other kinds of HA solid spheres with average diameters of about 6 or 20 μm were assembled from nanoflakes. The properties of the different kinds of spheres as drug delivery carriers were evaluated. Ibuprofen (IBU) was chosen as the model drug to load into the HA samples. The nanostructured HA samples showed a slow and sustained release of IBU. The HA hollow spheres exhibited a higher drug loading capacity and more favorable release properties than the HA solid spheres and thus are very promising for controlled drug release applications.

关键词： hydroxyapatite hollow spheres synthesis drug release

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Seismic performance of precast hollow bridge piers with different construction details

Zhiqiang WANG,Jiping GE,Hongyi WEI

《结构与土木工程前沿（英文）》 2014年第8卷第4期页码 399-413 doi: 10.1007/s11709-014-0273-7

摘要： Currently the design scheme of precast hollow concrete bridge piers will be adopted in bridge design in China, but there is no code including specific design details of precast segmental piers in high seismic risk area. For comparative study of seismic performance of the hollow bridge piers which had different design details, six specimens of hollow section bridge pier were designed and tested. The specimens consist of the monolithic cast-in-place concrete bridge pier, precast segmental prestressed pier with cast-in-place joint and precast segmental concrete bridge pier with dry joints. Results show that all specimens have good displacement capacity. The bridge pier with bonded prestressed strands exhibits better energy dissipation capacity and higher strength. The un-bonded prestressed strand bridge pier displays less residual plastic displacement and energy dissipation capacity. The bridge pier with both bonded prestressed strands at the edge of the section and un-bonded in the center of the section not only exhibits more ductility capacity and less residual plastic displacement, but also shows better energy dissipation capacity. Compared with experimental results of prestressed bridge columns, analytical result demonstrates the developed numerical analysis model would provide the reasonable and accurate results.

关键词： hollow pier seismic performance cyclic load precast concrete bridge columns

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Impingement of hollow cone spray on hot porous medium

ZHAO Zhiguo, XIE Maozhao

《能源前沿（英文）》 2008年第2卷第3期页码 273-278 doi: 10.1007/s11708-008-0048-8

摘要： To have a good understanding of the formation of homogenous mixture in a porous medium engine, the interaction between hollow cone spray and hot porous medium was studied numerically by using an improved version of KIVA-3V code. The improved KIVA-3V code is incorporated with an impingement model, heat transfer model and linearized instability sheet atomization (LISA) model to simulate the hollow cone spray. The reasonability of the impingement model and heat transfer model was validated. With a simple model to describe the structure of the porous medium, the interaction between hollow cone spray and hot porous medium was simulated under different ambient pressures and spray cone angles. Computational results show that the fuel spray could be divided into smaller ones, which provides conditions for the quick evaporation of fuel droplets and the mixing of fuel vapor with air. Differences in ambient pressure and spray cone angle affect the distribution of droplets in the porous medium.

关键词： improved version simple impingement atomization hollow

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Preparation and characterization of EVAL hollow fiber membrane adsorbents filled with cation exchange

Fengli ZHANG, Yuzhong ZHANG, Hong LI, Guangfen LI,

《化学科学与工程前沿（英文）》 2009年第3卷第4期页码 462-467 doi: 10.1007/s11705-009-0011-1

摘要： EVAL hollow fiber membrane adsorbents filled with powder D061-type cation exchange resin were prepared through dry-wet spinning process, using hydrophilic copolymer EVAL as the fiber substrate. The microstructures of the membrane adsorbents were observed, and the pure water fluxes, BSA rejection, and static adsorption capacities of membrane adsorbents for BSA were measured. The effect of the resin-filled content on membrane performance has been discussed. The results showed that EVAL hollow fiber membrane adsorbents filled with D061-type cation exchange resins had good adsorption capacity, and the adsorption capacity increased with the quantity of the resin-filled content. The static protein adsorption capacity was 77.14 mg BSA/g membrane adsorbents when D061 resin loading content was 65% at pH 4.5.

关键词： substrate copolymer EVAL exchange EVAL hollow resin-filled content

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Preparation and characterization of alumina hollow fiber membranes

Tao WANG, Yuzhong ZHANG, Guangfen LI, Hong LI

《化学科学与工程前沿（英文）》 2009年第3卷第3期页码 265-271 doi: 10.1007/s11705-009-0010-2

摘要： With the rapid development of membrane technology in water treatment, there is a growing demand for membrane products with high performance. The inorganic hollow fiber membranes are of great interest due to their high resistance to abrasion, chemical/thermal degradation, and higher surface area/volume ratio therefore they can be utilized in the fields of water treatment. In this study, the alumina (Al O ) hollow fiber membranes were prepared by a combined phase-inversion and sintering method. The organic binder solution (dope) containing suspended Al O powders was spun to a hollow fiber precursor, which was then sintered at elevated temperatures in order to obtain the Al O hollow fiber membrane. The dope solution consisted of polyethersulfone (PES), N-methyl-2-pyrrolidone (NMP) and polyvinylpyrrolidone (PVP), which were used as polymer binder, solvent and additive, respectively. The prepared Al O hollow fiber membranes were characterized by a scanning electron microscope (SEM) and thermal gravimetric analysis (TG). The effects of the sintering temperature and Al O /PES ratios on the morphological structure, pure water flux, pore size and porosity of the membranes were also investigated extensively. The results showed that the pure water flux, maximum pore size and porosity of the prepared membranes decreased with the increase in Al O /PES ratios and sintering temperature. When the Al O /PES ratio reached 9, the pure water flux and maximum pore size were at 2547 L/m ·h and 1.4 μm, respectively. Under 1600°C of sintering temperature, the pure water flux and maximum pore size reached 2398 L/(m ·h) and 2.3 μm, respectively. The results showed that the alumina hollow fiber membranes we prepared were suitable for the microfiltration process. The morphology investigation also revealed that the prepared Al O hollow fiber membrane retained its’asymmetric structure even after the sintering process.

关键词： Al₂O₃ ceramic membranes hollow fiber

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Scaling up of cluster beam deposition technology for catalysis application

《化学科学与工程前沿（英文）》 2021年第15卷第6期页码 1360-1379 doi: 10.1007/s11705-021-2101-7

摘要： Many research works have demonstrated that the combination of atomically precise cluster deposition and theoretical calculations is able to address fundamental aspects of size-effects, cluster-support interactions, and reaction mechanisms of cluster materials. Although the wet chemistry method has been widely used to synthesize nanoparticles, the gas-phase synthesis and size-selected strategy was the only method to prepare supported metal clusters with precise numbers of atoms for a long time. However, the low throughput of the physical synthesis method has severely constrained its wider adoption for catalysis applications. In this review, we introduce the latest progress on three types of cluster source which have the most promising potential for scale-up, including sputtering gas aggregation source, pulsed microplasma cluster source, and matrix assembly cluster source. While the sputtering gas aggregation source is leading ahead with a production rate of ~20 mg·h^–1, the pulsed microplasma source has the smallest physical dimensions which makes it possible to compact multiple such devices into a small volume for multiplied production rate. The matrix assembly source has the shortest development history, but already show an impressive deposition rate of ~10 mg·h^–1. At the end of the review, the possible routes for further throughput scale-up are envisaged.

关键词： nanoparticle cluster cluster beam deposition magnetron sputtering heterogeneous catalysis

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Applications of hollow nanomaterials in environmental remediation and monitoring: A review

Yuankai ZHANG,Zhijiang HE,Hongchen WANG,Lu QI,Guohua LIU,Xiaojun ZHANG

《环境科学与工程前沿（英文）》 2015年第9卷第5期页码 770-783 doi: 10.1007/s11783-015-0811-0

摘要： Hollow nanomaterials have attracted significant attention because of their high chemical and thermal stability, high specific surface area, high porosity, low density, and good biocompatibility. These state-of-the-art nanomaterials have been shown to efficiently adsorb heavy metals, and volatile hazardous substances, photodegrade persistent organic pollutants, and other compounds, and inactivate bacteria. Such properties have enabled the use of these materials for environmental remediation, such as in water/wastewater treatment, soil remediation, air purification, and substance monitoring, etc. Hollow nanomaterials showed higher photocatalytic activity than those without hollow structure owing to their high active surface area, reduced diffusion resistance, and improved accessibility. And, the Doping method could improve the photocatalytic performance of hollow nanomaterials further under visible light. Moreover, the synthetic mechanisms and methods of these materials are important because their size and morphology help to determine their precise properties. This article reviews the environmental applications and potential risks of these materials, in addition to their syntheses. Finally, an outlook into the development of these materials is provided.

关键词： hollow nanomaterials environmental remediation nanotechnology nanostructures morphology

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Hot-dip galvanizing of cold-formed steel hollow sections: a state-of-the-art review

Min SUN, Jeffrey A. PACKER

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 49-65 doi: 10.1007/s11709-017-0448-0

摘要： A good understanding of the effects of galvanizing on the short- and long-term behaviours of steel components is essential for structural design. This review paper is motivated by a series of recent reports on cracking in galvanized cold-formed tubular steel structures and the limitations of current steel product standards and steel design specifications in this field. The steel-related and galvanizing-related factors, different pre-galvanizing countermeasures for brittle cracking and the available technical documents are summarized. An extensive bibliography is provided as a basis for future research and development in this field.

关键词： cold-formed steel hollow structural sections hot-dip galvanizing embrittlement heat-treatment residual stress cracking

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Ag/PMMA hollow waveguide for solar energy transmission

He LAN, Jianjun HAN, Hongping CHEN, Xiujian ZHAO

《化学科学与工程前沿（英文）》 2011年第5卷第3期页码 303-307 doi: 10.1007/s11705-010-0565-y

摘要： This paper describes an elaborate study on obtaining Ag/PMMA (polymethyl methacrylate) leaky hollow waveguide which has a large aperture and low loss in transmitting solar energy. Through analyses and comparison, a quartz capillary with the inner diameter of 2 mm was chosen as hollow waveguide. We used the xenon light source, which has the similar spectrum as the sunlight to test and analyze the performance of the Ag/PMMA leakage hollow waveguide. The results are consistent with the transmitted theory of the dielectric/metal leaky type well. Meanwhile, the Ag/PMMA leaky-type hollow waveguide in this work had good qualities. Therefore, it will be a satisfactory medium for solar energy transmission.

关键词： hollow waveguide transmit the solar energy Ag/PMMA multiple film parabolic collector

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Formation of CaCO hollow microspheres in carbonated distiller waste from Solvay soda ash plants

《化学科学与工程前沿（英文）》页码 1659-1671 doi: 10.1007/s11705-022-2173-z

摘要： For decades, distiller waste and CO₂ were not the first choice for production of high valued products. Here, CaCO₃ hollow microspheres, a high-value product was synthesized from such a reaction system. The synthetic methods, the formation mechanism and operational cost were discussed. When 2.5 L·min^–1·L^–1 CO₂ was flowed into distiller waste (pH = 11.4), spheres with 4–13 μm diameters and about 2 μm shell thickness were obtained. It is found that there is a transformation of CaCO₃ particles from solid-cubic nuclei to hollow spheres. Firstly, the Ca(OH)₂ in the distiller waste stimulated the nucleation of calcite with a non-template effect and further maintained the calcite form and prevented the formation of vaterite. Therefore, in absence of auxiliaries, the formation of hollow structures mainly depended on the growth and aging of CaCO₃. Studies on the crystal morphology and its changes during the growth process point to the inside–out Ostwald effect in the formation of hollow spheres. Change in chemical properties of the bulk solution caused changes in interfacial tension and interfacial energy, which promoted the morphological transformation of CaCO₃ particles from cubic calcite to spherical clusters. Finally, the flow process for absorption of CO₂ by distiller waste was designed and found profitable.

关键词： distiller waste CO₂ hollow microsphere CaCO₃ Ca(OH)₂ inside−out Ostwald effect

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Effects of baffles on separation of aqueous ethanol solution with hollow fibers

Zhihong YANG, Guoliang ZHANG, Lan LIN, Danping REN, Qin MENG, Hongzi ZHANG

《化学科学与工程前沿（英文）》 2009年第3卷第1期页码 68-72 doi: 10.1007/s11705-009-0130-8

摘要： The effects of baffles on the operation and mass-transfer characteristics in novel hollow fiber membrane contactor used in distillation were investigated. Hollow fiber membranes, coated with a 7 μm polydimethyl-siloxane, were operated as structural packing in the separation of ethanol-water solutions. The parallel flow mode was chosen for separation due to the stronger driving force of the concentration difference, in which liquid flows through the lumens of the fibers and vapor flows countercurrent-wise outside the fibers. Two baffles were installed on the shell side of the membrane contactors to enhance separation, which had a round shape with a semi-lunar hole. The results show that both baffled and unbaffled membrane contactors gave better, more productive separations than traditional packing in distillation, such as the excellent Sulzer Gauze BX structured packing. The baffled membrane contactors performed better than unbaffled ones, especially at high vapor velocities. The minimal HTU of membrane contactor with baffles could reach as low as 4.5 cm, and almost all the contactors could work well above the limit where flooding normally occurs in conventional cases. Theoretical analysis predicted that baffles helped membrane module to obtain a higher mass-transfer coefficient and a smaller mass-transfer resistance. Finally, theoretical mass-transfer coefficient and experimental value were compared as well as the contribution of each individual mass-transfer coefficients among liquid, gas and membrane.

关键词： hollow fiber membrane contactor baffle mass-transfer ethanol-water

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Hollow carbon spheres and their noble metal-free hybrids in catalysis

《化学科学与工程前沿（英文）》 2021年第15卷第6期页码 1380-1407 doi: 10.1007/s11705-021-2097-z

摘要： Hollow carbon spheres have garnered great interest owing to their high surface area, large surface-to-volume ratio and reduced transmission lengths. Herein, we overview hollow carbon sphere-based materials and their noble metal-free hybrids in catalysis. Firstly, we summarize the key fabrication techniques for various kinds of hollow carbon spheres, with a particular emphasis on controlling pore structure and surface morphology, and then heterogeneous doping as well as their metal-free/containing hybrids are presented; next, possible applications for non-noble metal/hollow carbon sphere hybrids in the area of energy-related catalysis, including oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, water splitting, rechargeable Zn-air batteries and pollutant degradation are discussed; finally, we introduce the various challenges and opportunities offered by hollow carbon spheres from the perspective of synthesis and catalysis.

关键词： hollow carbon spheres functionalization noble metal-free catalysis

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Numerical simulation of a new hollow stationary dehumidity blade in last stage of steam turbine

Youmin HOU, Danmei XIE, Wangfan LI, Xinggang YU, Yang SHI, Hanshi QIN

《能源前沿（英文）》 2011年第5卷第3期页码 288-296 doi: 10.1007/s11708-011-0160-z

摘要： As a result of adopting saturation steam and long blade, problems of water erosion of last stage blade for steam turbine become more prominent. In order to improve the operation reliability and efficiency of steam turbine, it is necessary to investigate the nonequilibrium condensing wet steam two phase flow and the dehumidity method. A wet steam model with user defined function based on FLUENT software was investigated to simulate the steam condensing flow in the cascades. The simulation consequences show that the pressure variations in simulation depict a good agreement with the experiment data. On the basis of the discrete phase model simulation results and experiment data, the efficiency of existing dehumidity blade with suction slot was calculated. A new stationary dehumidity blade was designed to elevate the dehumidity efficiency: the efficiency in the suction surface was increased by 21.5%, and that in the pressure surface was increased by 12.2%.

关键词： steam turbine hollow stationary blade dehumidity numerical simulation