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Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

《化学科学与工程前沿（英文）》 2011年第5卷第2期页码 194-202 doi: 10.1007/s11705-010-1019-2

摘要： In this study, the effect of ethanol addition into pure water and its concentration on bubble diameter, gas hold-up and flow regimes were investigated in an airlift reactor. Air and water with ethanol (concentration ranging from 0%–1%, v/v) were as dispersed and continuous phases, respectively. Superficial gas velocity was considered as an effective parameter. Bubble size distribution was measured by photography and picture analysis at various concentrations of ethanol and various velocities of gas. Alcohol concentration enhancement caused bubble diameter to decrease. Furthermore, the bubbles diameter in pure water was nearly 4 times higher than that of ethanol with concentration of 1% (v/v) and also was 3.4 times higher than that of ethanol with concentration of 0.25% (v/v) at the highest aeration gas velocity inlet. For ethanol solutions in lower superficial gas velocity, a homogenous flow regime was observed. This trend continued to inlet gas velocity of about 0.4 cm/s. The transition flow regime occurred after this datum although in pure water, a homogenous flow regime was observed up to a superficial gas velocity of 0.7 cm/s. The gas hold-up in dilute ethanol solutions were more than (around 2 times) that of pure water and increased with increasing concentration of ethanol in those solutions.

关键词： airlift rector bubble diameter gas hold-up flow regime ethanol

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Impacts of different diameter combinations on the temperature of a crude oil pipeline when colocating

Bo YU, Yue SHI, Xin LIU, Jinjun ZHANG, Jinjia WEI,

《能源前沿（英文）》 2010年第4卷第2期页码 192-197 doi: 10.1007/s11708-009-0074-1

摘要： In order to show the effects of different diameter combinations on crude oil temperature when a crude oil pipeline and a products pipeline are laid in one trench, four typical diameter combinations are selected to conduct numerical simulation. After a series of calculations, the minimum mean temperature difference and the maximum temperature difference of the crude oil along the pipelines are obtained. In real pipeline constructions, the effects of other diameter combinations on crude oil temperature can be predicted by the method of linear interpolation to calculate results of the four diameter combinations obtained in this study.

关键词： technology of laying two pipelines in one trench diameter combinations crude oil temperature pipeline interval

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Effects of slip length and hydraulic diameter on hydraulic entrance length of microchannels with superhydrophobic

Wenchi GONG, Jun SHEN, Wei DAI, Zeng DENG, Xueqiang DONG, Maoqiong GONG

《能源前沿（英文）》 2020年第14卷第1期页码 127-138 doi: 10.1007/s11708-020-0661-8

摘要： This paper investigated effects of slip length and hydraulic diameter on the hydraulic entrance length of laminar flow in superhydrophobic microchannels. Numerical investigations were performed for square microchannels with Re ranging between 0.1 and 1000. It is found that superhydrophobic microchannels have a longer hydraulic entrance length than that of conventional ones by nearly 26.62% at a low Re. The dimensionless hydraulic entrance length slightly increases with the increasing slip length at approximately Re<10, and does not vary with the hydraulic diameter. A new correlation to predict the entrance length in square microchannels with different slip lengths was developed, which has a satisfying predictive performance with a mean absolute relative deviation of 5.69%. The results not only ascertain the flow characteristics of superhydrophobic microchannels, but also suggest that super hydrophobic microchannels have more significant advantages for heat transfer enhancement at a low Re.

关键词： laminar flow hydraulic entrance length super hydrophobic surface slip length hydraulic diameter

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大直径管片拼装及缺陷处理

程学武,许维青,杨志永

《中国工程科学》 2010年第12卷第12期页码 89-93

摘要：

总结了北京地下直径线工程大直径盾构管片拼装技术，初步分析了大直径盾构钢筋混凝土管片施工过程中的表观破损原因，并对破损管片修补技术进行探讨，提出对拱腰以上、拱腰以下部位管片的不同修补方法，保证了大直径盾构管片的强度及外观质量。

关键词：大直径盾构管片拼装修补

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Stability analysis of large diameter thin-walled tube beam-columns

PAN Hanming, GUO Yanlin, LIANG Shuo, PEI Shengxing, LIANG Weisheng, WANG Lewen

《结构与土木工程前沿（英文）》 2008年第2卷第2期页码 123-132 doi: 10.1007/s11709-008-0017-7

摘要： Based on a blind spot in the current design standard of steel structures, the large diameter thin-walled tube beam-columns are analyzed using nonlinear finite element method in this paper. The influence of several factors on stability capacity of the large diameter thin-walled tube beam-columns is taken into account. Thus, according to the correlative design standard of steel structures, and on the basis of the numerical analytical results by the finite element methods, the calculation formulas of the stability bearing capacity are presented for beam-column members of the large diameter thin-walled tubes. Three tests of thin-walled steel tube beam-columns were reported. Test results for deformations and ultimate strength are found to be in a good agreement with the corresponding values predicted by the calculation formulas, and the proposed methods can be used in design practice.

关键词： ultimate strength nonlinear numerical analytical diameter thin-walled practice

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Influence of sprinkler irrigation droplet diameter, application intensity and specific power on flower

Yisheng ZHANG, Delan ZHU

《农业科学与工程前沿（英文）》 2017年第4卷第2期页码 165-171 doi: 10.15302/J-FASE-2017145

摘要： To determine the main parameters of droplet strike damage and avoid flower injury due to the unsuitable practices during sprinkler irrigation, an indoor experiment of irrigation droplet impact on cyclamen was conducted. The influences of different parameters such as droplet diameter, application intensity, specific power on flower strike damage was analyzed using Image Pro-Plus software to compute strike damage area and define damage level by sense-analysis. The results showed that a damage area of <1% represents a safe irrigation level, 1%–3% slight damage level, 3%–6% moderate damage level, and>6% heavy damage level. Equations of application intensity, specific power with sprinkler irrigation time and flower injury ratio were regressed against parameters which cause impact damages. The results indicated that specific power has a significant correlation with injury, and flower damage area increased as the increasing of the value of specific power for the same irrigation time. Application intensity was also correlated with injury when the droplet diameter was larger than 1 mm. When the duration of sprinkler irrigation was 1, 5 and 10 min, the threshold of impinging damage of application intensity was 25.30, 5.01 and 1.64 mm·h and the specific power was 0.467×10 , 9.340×10 and 3.110×10 W·m . These results provide a reference for determining the suitable values of sprinkler properties in operation design.

关键词： application intensity damage floriculture flowers specific power sprinkler irrigation

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A new performance evaluation method and its application in fin-tube surface design of small diameter

Jufang FAN, Weikun DING, Zhigeng WU, Yaling HE, Wenquan TAO, Yongxin ZHENG, Yifeng GAO, Ji SONG

《能源前沿（英文）》 2011年第5卷第1期页码 59-68 doi: 10.1007/s11708-010-0132-8

摘要： In this paper, a simple yet efficient performance comparison method is proposed based on the assumptions of constant properties and identical frontal area. For this method, no correlations are required, and a small number of discrete data are sufficient. To illustrate the feasibility of the proposed approach, a new slotted fin with 4 mm tubes is designed to replace the original louvered fin with tubes of 7 mm. The orthogonal design method is adopted in the fin design to reduce the number of computational cases significantly, and yet a nearly optimum combination of major geometric factors can still be obtained. The reasonable parametric combination of 3 global parameters is obtained by analyzing the numerical results of 16 plain plate fins. Based on this result, 3 new slotted fins with different fin pitches are studied. The slotted fin with a fin pitch of 1.4 mm is recommended after considering the heat transfer, comprehensive performance, and cost of material and operation. The result shows that compared with the original louvered fin, the recommended fin not only increases the heat transfer rate by 2.2%, 22.5%, and 13.7% under an identical flow rate, identical pressure drop, and identical pumping power constraint, respectively, but also saves approximately 36% of the copper tube materials.

关键词： performance evaluation orthogonal design small-diameter tube

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北京铁路地下直径线泥水盾构刀盘、刀具适应性分析

何峰,李小岗,孙善辉

《中国工程科学》 2010年第12卷第12期页码 35-40

摘要：

结合北京站至北京西站地下直径线工程实例，通过不同盾构刀盘刀具配置在砂卵石下的应用对比，重点对工程刀盘刀具改造前后对地层的适应性进行了详细的对比分析，提出了砂卵石条件下刀盘刀具配置应注意的关键问题，对类似工程有借鉴作用。

关键词：直径线泥水盾构刀盘刀具适应性

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Cutting Force Model for a Small-diameter Helical Milling Cutter

LI Xiwen, YANG Shuzi, YANG Mingjin, XIE Shouyong

《机械工程前沿（英文）》 2007年第2卷第3期页码 272-277 doi: 10.1007/s11465-007-0047-1

摘要： In the milling process, the major flank wear land area (two-dimensional measurement for the wear) of a small-diameter milling cutter, as wear standard, can reflect actual changes of the wear land of the cutter. By analyzing the wearing characteristics of the cutter, a cutting force model based on the major flank wear land area is established. Characteristic parameters such as pressure parameter and friction parameter are calculated by substituting tested data into their corresponding equations. The cutting force model for the helical milling cutter is validated by experiments. The computational and experimental results show that the cutting force model is almost consistent with the actual cutting conditions. Thus, the cutting force model established in the research can provide a theoretical foundation for monitoring the condition of a milling process that uses a small-diameter helical milling cutter.

关键词： computational corresponding helical milling theoretical foundation Characteristic

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Fatigue crack growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combined

《结构与土木工程前沿（英文）》 2021年第15卷第4期页码 905-913 doi: 10.1007/s11709-021-0683-2

摘要： In a nuclear powerplant, the rotary equipment, such as a pump directly fitted with hanger in the piping system, experiences torsional and bending loads. Higher crack growth rate occurs because of this torsional load in addition to the bending load. Hence, it is necessary to study the fatigue behavior of piping components under the influence of combined torsional and bending load. In this study, experimental fatigue life evaluation was conducted on a notched stainless steel SA312 Type 304LN straight pipe having an outer diameter of 170 mm. The experimental crack depth was measured using alternating current potential drop technique. The fatigue life of the stainless steel straight pipe was predicted using experiments, Delale and Erdogan method, and area-averaged root mean square–stress intensity factor approach at the deepest and surface points of the notch. Afterward, the fatigue crack growth and crack pattern were discussed. As a result, fatigue crack growth predicted using analytical methods are in good agreement with experimental results.

关键词： fatigue life Delale and Erdogan method RMS–SIF approach stainless steel torsion and bending load fatigue crack growth

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小口径血管的生物打印进展 Review

曹霞, Sushila Maharjan, Ramla Ashfaq, Jane Shin, Yu Shrike Zhang

《工程（英文）》 2021年第7卷第6期页码 832-844 doi: 10.1016/j.eng.2020.03.019

摘要：

生物工程血管在再生医学和药物筛选等应用中的需求越来越大，但生物工程血管移植物的真正可用性仍然有限。三维（3D）生物打印技术为移植和再生提供了一种潜在的血管或血管化组织结构的制备方法。本文总结了不同血管的基本生物学特性，以及用于制备血管和血管化组织结构的3D生物打印方法和生物墨水设计，重点探讨了小口径血管。

关键词：生物打印小口径血管生物墨水血管生物工程

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大直径盾构刀盘改造竖井施工技术

王振飞,何峰,贺善宁

《中国工程科学》 2010年第12卷第12期页码 103-107

摘要：

以北京地下直径线盾构的刀盘改造竖井施工为例，针对复杂边界条件下大直径盾构刀盘改造异性结构竖井的设计及施工进行探讨，就如何保证竖井结构安全，同时又能合理协调盾构施工进行了实践探索，并给出了可靠的解决措施，取得了成功，为类似工程提供参考借鉴。

关键词：大直径盾构改造竖井复杂条件

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北京铁路地下直径线盾构始发技术

吕传田,翟志国,苏清贵

《中国工程科学》 2010年第12卷第12期页码 59-64

摘要：

通过对北京地下直径线工程采用的直径Ø12.04 m泥水平衡盾构机始发竖井及盾构始发施工的介绍，总结了在城市繁华地段、富水砂砾石地质条件下，大直径泥水盾构始发施工的一些关键技术。

关键词：城市富水砂卵石大直径泥水盾构始发

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大直径盾构负环管片拆除及隧道换装技术

翟志国,黄学军,杨志永

《中国工程科学》 2010年第12卷第12期页码 83-88

摘要：

通过对北京铁路地下直径线2标工程的研究，确定在刀盘改造期间进行负环管片拆除的一系列工作，重点如部分反力架的拆除方法、负环管片的详细拆除方法以及拆除反力架后临时支撑的架设方法，同时就泥水盾构隧道的换装技术进行了叙述，最终在7 d之内成功拆除了7环负环管片，节约了工期，保证了后继施工的材料运输速度。

关键词：大直径盾构负环管片拆除隧道换装

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various grade of Ordinary Portland Cement (OPC) and Portland Pozzolane Cement (PPC) mixes and different diameter

A D POFALE, S P WANJARI

《结构与土木工程前沿（英文）》 2013年第7卷第1期页码 39-45 doi: 10.1007/s11709-013-0193-y

摘要： Since last two decades, the Portland Pozzolane Cement (PPC) is extensively used in structural concrete. But, till to date, a few literature is available on bond strength of concrete using PPC mixes. There are many literatures available on bond strength of concrete mixes using Ordinary Portland Cement (OPC). Hence, a comparative study was conducted on bond strength between OPC and PPC mixes. In the present investigation, total 24 samples consisting of M20, M35 and M50 grades of concrete and 16 and 25 mm diameter of TMT bar were tested for 7 and 28 days. The pullout bond test was conducted on each specimen as per IS: 2770-1967/1997 [1] and the results were observed at 0.25 mm slip at loaded end called as critical bond stress and at maximum bond load called as maximum bond stress. It was observed that the critical bond strength of PPC mixes is 10% higher than OPC mixes. Whereas, marginal improvement was noticed in maximum bond strength of PPC mixes. Hence, based on these findings, it could be concluded that development length for PPC mixes could be reduced by 10% as compared with same grade of OPC mixes.

关键词： bond strength Portland Pozzolane Cement (PPC) concrete Ordinary Portland Cement (OPC) concrete bond between concrete and steel pullout test development length