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Determination of bond model for 7-wire strands in pretensioned concrete beam 预应力混凝土梁中7股绞线粘结模型的确定
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-12-31 DOI: 10.14311/ap.2021.61.0740
Vadzim Parkhats, R. Krzywoń, Jacek Hulimka, J. Kubica
A correct choice of a bond model for prestressing tendons is crucial for the right modelling of a structural behaviour of a pretensioned concrete structure. The aim of this paper is the determination of an optimal bond model for 7-wire strands in a prestressed concrete beam produced in a precast concrete plant of Consolis Poland. ATENA 3D is used to develop finite element models of the beam that differ only in a bond stress-slip relationship of tendons. The bond stress-slip relationships for modelling are taken from the results of bond tests carried out by different researchers in previous years. Moreover, for comparison purposes, a simplified 2D model of the beam is created in Autodesk Robot. The strain distribution at the time of the strand release is found for each of the finite element models. The determined strain distributions are compared with the strain distribution in the beam established by an experimental test using a measuring system based on a digital image correlation. On the basis of the comparison results, the most appropriate bond models for 7-wire strands used in the beam are identified.
正确选择预应力筋的粘结模型对于正确建模预张拉混凝土结构的结构性能至关重要。本文的目的是确定波兰康索利斯预制混凝土厂生产的预应力混凝土梁中7股钢丝绳的最佳粘结模型。ATENA 3D用于开发梁的有限元模型,这些模型的不同之处仅在于钢筋束的粘结-应力-滑移关系。用于建模的粘结应力-滑移关系取自不同研究人员在前几年进行的粘结测试的结果。此外,为了进行比较,将在Autodesk Robot中创建梁的简化二维模型。对于每一个有限元模型,都可以找到绞线释放时的应变分布。将确定的应变分布与通过使用基于数字图像相关性的测量系统的实验测试建立的梁中的应变分布进行比较。在比较结果的基础上,确定了梁中使用的7股线的最合适的结合模型。
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引用次数: 0
Delamination of polyimide in hydrofluoric acid 聚酰亚胺在氢氟酸中的分层
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-12-31 DOI: 10.14311/ap.2021.61.0684
A. K. Al-mashaal, R. Cheung
Wet etching is a critical fabrication step for the mass production of micro and nanoelectronic devices. However, when an extremely corrosive acid such as hydrofluoric (HF) acid are used during etching, an undesirable damage might occur if the device includes a material that is not compatible with the acid. Polyimide thin films can serve as sacrificial/structural layers to fabricate freestanding or flexible devices. The importance of polyimide in microelectronics is due to its relatively low stress and compatibility with standard micromachining processes. In this work, a fast delamination process of a 4-μm-thin film of polyimide from a silicon substrate has been demonstrated. The films’ detachment has been performed using a wet-based etchant of HF acid. Specifically, the effect of HF concentration on the delamination time required to detach the polyimide film from the substrate has been investigated. This study is intended to provide the information on the compatibility of using polyimide films with HF, which can help in the design and fabrication of polyimide-based devices.
湿法蚀刻是大规模生产微型和纳米电子器件的关键制造步骤。然而,当在蚀刻过程中使用腐蚀性极强的酸,例如氢氟酸(HF)时,如果器件包括与酸不兼容的材料,则可能发生不期望的损坏。聚酰亚胺薄膜可用作牺牲/结构层以制造独立式或柔性器件。聚酰亚胺在微电子技术中的重要性是由于其相对较低的应力和与标准微加工工艺的兼容性。在这项工作中,演示了4μm聚酰亚胺薄膜从硅衬底上的快速分层过程。薄膜的剥离是使用HF酸的湿基蚀刻剂进行的。具体地,已经研究了HF浓度对将聚酰亚胺膜从衬底分离所需的分层时间的影响。本研究旨在提供有关使用聚酰亚胺薄膜与HF的兼容性的信息,这有助于聚酰亚胺基器件的设计和制造。
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引用次数: 0
Cavitation wear of Eurofer 97, Cr18Ni10Ti and 42HNM alloys Eurofer 97、Cr18Ni10Ti和42HNM合金的空化磨损
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-12-31 DOI: 10.14311/ap.2021.61.0762
H. Rostova, V. Voyevodin, R. Vasilenko, I. Kolodiy, V. Kovalenko, V. Marinin, V. Zuyok, A. Kuprin
The microstructure, hardness and cavitation wear of Eurofer 97, Cr18Ni10Ti and 42HNM have been investigated. It was revealed that the cavitation resistance of the 42HNM alloy is by an order of magnitude higher than that of the Cr18Ni10Ti steel and 16 times higher than that of the Eurofer 97 steel. Alloy 42HNM has the highest microhardness (249 kg/mm2) of all the investigated materials, which explains its high cavitation resistance. The microhardness values of the Cr18Ni10Ti steel and the Eurofer 97 were 196.2 kg/mm2 and 207.2 kg/mm2, respectively. The rate of cavitation wear of the austenitic steel Cr18Ni10Ti is 2.6 times lower than that of the martensitic Eurofer 97.
研究了Eurofer97、Cr18Ni10Ti和42HNM的组织、硬度和空蚀性能。结果表明,42HNM合金的抗空化性能比Cr18Ni10Ti钢高一个数量级,是Eurofer97钢的16倍。在所有研究材料中,42HNM合金具有最高的显微硬度(249kg/mm2),这解释了其高抗空化性。Cr18Ni10Ti钢和Eurofer97钢的显微硬度值分别为196.2kg/mm2和207.2kg/mm2。奥氏体钢Cr18Ni10Ti的空化磨损率是马氏体Eurofer97的2.6倍。
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引用次数: 1
Water-air ejector with conical-cylindrical mixing chamber 带锥形圆柱形混合室的水-空气喷射器
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-12-31 DOI: 10.14311/ap.2021.61.0768
A. Sliusenko, V. Ponomarenko, Inna Forostiuk
In the paper, the hydrodynamics of the liquid-gas mixture in the mixing chamber of the ejectors at different spatial positions was analyzed and the comparative study of such ejectors was carried out. It was found that a more ordered mode of movement of the mixture in the mixing chamber is created as a result of the coincidence of the velocity vector of liquid drops and the direction of gravity in the vertical position of the ejectors. This leads to increasing the volume entrainment ratio almost twice. The analysis of the liquid-gas mixture flow in the mixing chamber, evaluation calculations and research allowed to develop and to patent a jet apparatus with a conical-cylindrical (combined) mixing chamber. It was also found that for such ejectors, the volume entrainment ratio is 15–55% higher than for a jet apparatus with a cylindrical mixing chamber due to the reduction of the resistance of the passive flow into the mixing chamber and prevention of the formation of reverse-circulating flows. A study has been conducted on liquid-gas ejectors in the range of the main geometric parameter m (ratio of the mixing chamber area to the nozzle area) 9.4–126.5, which allowed to establish its rational values at which the maximum volume entrainment ratio is achieved (m = 25–40).
本文分析了不同空间位置喷射器混合室内液气混合物的流体力学特性,并对不同喷射器进行了对比研究。研究发现,由于液滴的速度矢量与喷射器垂直位置的重力方向一致,混合室中的混合物产生了更有序的运动模式。这导致体积夹带率几乎增加了两倍。通过对混合室内液气混合物流动的分析、评估计算和研究,开发了一种具有锥形圆柱形(组合)混合室的喷射装置并获得了专利。还发现,对于这种喷射器,由于降低了进入混合室的被动流的阻力并防止了反向循环流的形成,因此体积夹带率比具有圆柱形混合室的喷射装置高15-55%。在主要几何参数m(混合室面积与喷嘴面积之比)9.4-126.5的范围内,对液气喷射器进行了研究,从而确定了实现最大体积夹带率的合理值(m=25-40)。
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引用次数: 0
Design of Potential Rainwater Harvesting Structures for Environmental Adoption Measures in India 印度采用环保措施的潜在雨水收集结构设计
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-12-01 DOI: 10.1007/s41050-021-00035-9
Pallavi Uppala, S. Dey
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引用次数: 2
On reducing CO2 concentration in buildings by using plants 利用植物降低建筑物中二氧化碳浓度的研究
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-10-31 DOI: 10.14311/ap.2021.61.0617
O. Franek, Č. Jarský
The article deals with the implementation of plants in the indoor environment of buildings to reduce the concentration of CO2. Based on a specified model representing the internal environment of an office space, it was studied whether the requirement for the total amount of ventilated air could be reduced by using plants, thereby achieving savings of operating costs in the building ventilation sector. The present research describes the effect of plant implementation according to different levels of CO2 concentration of the supply air, specifically with values of 410 ppm corresponding to the year 2020, 550 ppm to the year 2050 and 670 ppm to the year 2100, as well as according to different levels of CO2 concentration in the indoor environment, namely 1000 ppm and 1500 ppm, the illumination of plants in the indoor environment is constant in the model, PPFD equals to 200 μmolm−2 s−1. Based on the computational model, it was found that the implemented plants can positively influence the requirement for the total amount of ventilated air, the most significant effect is in the case of a low indoor environment quality, with the CO2 concentration of 1500 ppm, and a high supply air quality 410 p˙pm. The simulation also showed that compared to 2020, by the year 2100, it will be necessary to increase the ventilation of the indoor environment by 25.1% to ensure the same quality of the indoorenvironment.
本文论述了在建筑物的室内环境中种植植物以降低二氧化碳浓度。根据代表办公空间内部环境的特定模型,研究了是否可以通过使用植物来减少对通风总量的要求,从而节省建筑通风部门的运营成本。本研究描述了根据供应空气的不同CO2浓度水平,特别是对应于2020年的410ppm、对应于2050年的550ppm和对应于2100年的670ppm的值,以及根据室内环境中的不同CO2含量水平,即1000ppm和1500ppm,实施工厂的效果,模型中植物在室内环境中的光照是恒定的,PPFD等于200μmolm−2s−1。基于计算模型,研究发现,所实施的工厂可以对通风总量的要求产生积极影响,最显著的影响是在室内环境质量较低的情况下,CO2浓度为1500ppm,供应空气质量较高的情况下为410p*pm。模拟还显示,与2020年相比,到2100年,有必要将室内环境的通风量增加25.1%,以确保室内环境的质量不变。
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引用次数: 1
Subjective approach to optimal cross-sectional design of biodegradable magnesium alloy stent undergoing heterogeneous corrosion 异质腐蚀下可生物降解镁合金支架截面优化设计的主观方法
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-10-31 DOI: 10.14311/ap.2021.61.0661
N. Zarei, S. Anvar, S. Goenezen
Existing biodegradable Magnesium Alloy Stents (MAS) have several drawbacks, such as high restenosis, hasty degradation, and bulky cross-section, that limit their widespread application in a current clinical practice. To find the optimum stent with the smallest possible cross-section and adequate scaffolding ability, a 3D finite element model of 25 MAS stents of different cross-sectional dimensions were analysed while localized corrosion was underway. For the stent geometric design, a generic sine-wave ring of biodegradable magnesium alloy (AZ31) was selected. Previous studies have shown that the long-term performance of MAS was characterized by two key features: Stent Recoil Percent (SRP) and Stent Radial Stiffness (SRS). In this research, the variation with time of these two features during the corrosion phase was monitored for the 25 stents. To find the optimum profile design of the stent subjectively (without using optimization codes and with much less computational costs), radial recoil was limited to 27 % (corresponding to about 10 % probability of in-stent diameter stenosis after an almost complete degradation) and the stent with the highest radial stiffness was selected.The comparison of the recoil performance of 25 stents during the heterogeneous corrosion phase showed that four stents would satisfy the recoil criterion and among these four, the one having a width of 0.161 mm and a thickness of 0.110 mm, showed a 24 % – 49 % higher radial stiffness at the end of the corrosion phase. Accordingly, this stent, which also showed a 23.28 % mass loss, was selected as the optimum choice and it has a thinner cross-sectional profile than commercially available MAS, which leads to a greater deliverability and lower rates of restenosis.
现有的可生物降解镁合金支架(MAS)存在高再狭窄、降解快、横截面大等缺点,限制了其在当前临床实践中的广泛应用。为了找到尽可能小的横截面和足够的支架能力的最佳支架,在局部腐蚀的情况下,对25个不同横截面尺寸的MAS支架进行了三维有限元分析。支架几何设计采用可生物降解镁合金(AZ31)的通用正弦波环。先前的研究表明,MAS的长期性能由两个关键特征表征:支架后坐力百分比(SRP)和支架径向刚度(SRS)。在本研究中,监测了25个支架在腐蚀阶段这两个特征随时间的变化。为了在主观上(不使用优化代码,计算成本更少)找到支架的最佳轮廓设计,将径向后坐力限制在27%(相当于几乎完全降解后支架内直径狭窄的概率约为10%),并选择径向刚度最高的支架。对25个支架在非均匀腐蚀阶段的后坐力性能进行了比较,结果表明,有4个支架满足非均匀腐蚀阶段的后坐力要求,其中宽度为0.161 mm、厚度为0.110 mm的支架在腐蚀阶段结束时的径向刚度提高了24% ~ 49%。因此,该支架也显示23.28%的质量损失,被选为最佳选择,它比市售的MAS具有更薄的横截面,从而导致更高的输送率和更低的再狭窄率。
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引用次数: 0
Application of additional insulation to ETICS on surfaces with biocorrosion ETICS在生物腐蚀表面的附加绝缘应用
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-10-31 DOI: 10.14311/ap.2021.61.0590
N. Antošová, P. Šťastný, M. Petro, Štefan Krištofič
The paper presents partial outputs from an experiment that demonstrated the impact of applying an additional insulation on an existing contact insulation system with a green-algae surface. The aim was mainly to detect the development of microorganisms in the gap between the original and the new insulation. The existing ETICS on the polystyrene-based contact thermal insulation system and EPS-based additional thermal insulation were used in the experiment. A theoretical modelling of temperature conditions showed that this type of doubling the insulation presented the highest risk of condensation of water in the gap between the insulation layers and that these conditions presented suitable humidity conditions for the growth of microorganisms. The reason for the experiment is to demonstrate the need to eliminate microorganisms before applying an additional thermal insulation to surfaces with biocorrosion. This is especially the case where EPS is used. The temperature and humidity parameters obtained during the experiment can be used to model the moisture regime in the gap of other types of insulations (e.g. MW, PUR, PIR.)
本文介绍了一个实验的部分输出,该实验展示了在现有的带有绿藻表面的接触绝缘系统上应用额外绝缘的影响。目的主要是检测在原保温层和新保温层之间的空隙中微生物的发展情况。实验采用现有的基于聚苯乙烯的接触式保温系统的ETICS和基于eps的附加保温系统。对温度条件的理论建模表明,这种加倍的保温层在保温层之间的缝隙中凝结水的风险最高,而且这些条件为微生物的生长提供了合适的湿度条件。该实验的原因是为了证明在对有生物腐蚀的表面施加额外的隔热材料之前需要消除微生物。在使用EPS时尤其如此。实验过程中获得的温度和湿度参数可用于模拟其他类型绝缘(例如MW, PUR, PIR)间隙中的水分状况。
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引用次数: 2
Design development and study of an elastic sectional screw operating tool 一种弹性分段螺杆操作工具的设计开发与研究
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-10-31 DOI: 10.14311/ap.2021.61.0624
R. Hevko, S. Zalutskyi, I. Tkachenko, O. Lyashuk, O. Trokhaniak
The results of an elastic sectional screw operating tool development and its production technique are presented in the article under consideration. The operating tool has been made to fix the elastic sections, providing the transportation of bulk materials of agricultural production, in order to ensure their minimal damage and the process minimal power capacity. The article presents constructed regression dependencies and response surfaces for the effects of the design, kinematic and technological parameters of a sectional screw operating tool on power consumption and the damage rate of grain material in the process of its transportation. As the result of the conducted experimental research, authors came to a conclusion that the arrangement of an elastic auger without a gap between its peripheral part and the inner surface of the guiding tube significantly reduces vibrations in the process of conveying bulk material.
本文介绍了一种弹性分段螺杆操作工具的研制结果及其生产技术。该操作工具用于固定弹性部分,提供农业生产的散装材料运输,以确保其损坏最小,并确保过程的功率最小。本文给出了分段螺杆操作工具的设计、运动学和工艺参数对颗粒材料在运输过程中的功耗和损伤率的影响的回归依赖关系和响应面。通过实验研究,作者得出结论,在输送散装材料的过程中,弹性螺旋输送器的外围部分和导管内表面之间没有间隙的布置显著降低了振动。
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引用次数: 3
Process optimization and performance evaluation of a downdraft gasifier for energy generation from wood biomass 木材生物质发电下吸式气化炉工艺优化及性能评价
IF 0.8 Q3 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2021-10-31 DOI: 10.14311/ap.2021.61.0601
I. Daniyan, Felix Ale, I. Uchegbu, K. Bello, Momoh Osazele
In recent time, due to the increasing demand for energy and the need to address environment-related issues, a great deal of focus has been given to alternative sources of energy, which are green, sustainable and safe. This work considers the process optimization and performance evaluation of a downdraft gasifier, suitable for energy generation using wood biomass. The assessment of the performance of the downdraft gasifier was based on the amount of output energy generated as well as the emission characteristics of the output. The Response Surface Methodology (RSM) was employed for the determination of the optimum range of the process parameters that will yield the optimum conversion of the biomass to energy. The optimum process parameters that produced the highest rate of conversion of biomass to energy (2.55 Nm3/kg) during the physical experiments were: temperature (1000 °C), particle size (6.0 mm) and residence time (35 min). The produced gas indicated an appreciable generation of methane gas (10.04 % vol.), but with a significant amount of CO (19.20 % vol.) and CO2 (22.68 % vol.). From the numerical results obtained, the gas yield was observed to increase from 1.86908 Nm3/kg to 2.40324 Nm3/kg as the temperature increased from 800 °C to 1200 °C. The obtained results indicate the feasibility for the production of combustible gases from the developed system using wood chips. It is envisaged that the findings of this work will assist in the development of an alternative and renewable energy source in an effort to meet the growing energy requirements.
近年来,由于能源需求的增加和解决环境问题的需要,绿色、可持续和安全的替代能源成为人们关注的焦点。这项工作考虑了工艺优化和性能评估的下吸式气化炉,适用于能源生产利用木材生物质。对下吸式气化炉性能的评估是基于产生的输出能量以及输出的排放特性。采用响应面法(RSM)确定了将生物质转化为能源的最佳工艺参数的最佳范围。在物理实验中,产生最高生物质转化率(2.55 Nm3/kg)的最佳工艺参数为:温度(1000°C),粒径(6.0 mm)和停留时间(35 min)。产气中甲烷(体积10.04%)含量较高,CO(体积19.20%)和CO2(体积22.68%)含量较高。从数值结果来看,当温度从800℃升高到1200℃时,产气量从1.86908 Nm3/kg增加到2.40324 Nm3/kg。实验结果表明,该系统利用木屑生产可燃气体是可行的。预计这项工作的结果将有助于开发一种替代能源和可再生能源,以努力满足日益增长的能源需求。
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引用次数: 1
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Acta Polytechnica
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