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Optimizing thermal insulation in subtropical monsoon climate religious buildings: material selection and thickness assessment 优化亚热带季风气候宗教建筑的隔热性能:材料选择和厚度评估
Pub Date : 2024-04-02 DOI: 10.1108/wje-07-2023-0241
Jhumana Akter, Mobasshira Islam, Shuvo Dip Datta
PurposeDetermining the suitable material and accurate thickness of the thermal insulation layer used in exterior walls during the design phase of a building can be challenging. This study aims to determine suitable material and optimum thickness for the insulation layer considering both operational and embodied factors by a comprehensive assessment of the energy, economic and environmental (3E) parameters.Design/methodology/approachFirst, the energy model of an existing building was created by using Autodesk Revit software according to the as-built floor layout to evaluate the impact of five alternative insulating materials in varying thickness values. Second, using the results derived from the model, a thorough evaluation was conducted to ascertain the optimal insulation material and thickness through individual analysis of 3E factors, followed by a comprehensive analysis considering the three aforementioned factors simultaneously.FindingsThe findings indicated that polyurethane with 13 cm thickness, rockwool with 10 cm thickness and EPS with 20 cm thickness were the best states based on energy consumption, cost and environmental footprint, respectively. After completing the 3E investigation, the 15-cm-thick mineral wool insulation was presented as the ideal state.Practical implicationsThis study explores how suitable material and thickness of insulating material can be determined in advance during the design phase of a building, which is a lot more accurate and cost-effective than applying insulating materials by assumed thickness in the construction phase.Originality/valueTo the best of the authors’ knowledge, this paper is unique in investigating the advantages of using thermally insulating materials in the context of a mosque structure, taking into account its distinctive attributes that deviate from those of typical buildings. Furthermore, there has been no prior analysis of the cost and sustainability implications of these materials concerning the characteristics of subtropical monsoon climate.
目的在建筑设计阶段确定外墙保温层的合适材料和准确厚度是一项挑战。本研究旨在通过对能源、经济和环境(3E)参数的综合评估,在考虑运行和体现因素的情况下,确定保温层的合适材料和最佳厚度。首先,使用 Autodesk Revit 软件根据竣工楼面布局创建了现有建筑的能源模型,以评估不同厚度值的五种备选保温材料的影响。其次,利用模型得出的结果进行全面评估,通过对 3E 因素的单独分析,确定最佳的保温材料和厚度,然后再同时考虑上述三个因素进行综合分析。在完成 3E 调查后,15 厘米厚的矿棉隔热材料被认为是最理想的状态。本研究探讨了如何在建筑设计阶段提前确定合适的隔热材料和厚度,这比在施工阶段通过假定厚度来使用隔热材料要准确得多,也更符合成本效益。此外,此前还没有针对亚热带季风气候特点对这些材料的成本和可持续性影响进行过分析。
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引用次数: 0
Optimization and modelling of WCEDM process parameters for GZR-AA7475 HMMC using GRA and Taguchi approach 使用 GRA 和田口方法对 GZR-AA7475 HMMC 的 WCEDM 工艺参数进行优化和建模
Pub Date : 2024-02-26 DOI: 10.1108/wje-09-2023-0354
Madhavarao Singuru, Kesavarao V.V.S., Rama Bhadri Raju Chekuri
PurposeThis study aims to investigate the optimal process parameters of the wire-cut electrical discharge machining (WCEDM) for the machining of the GZR-AA7475 hybrid metal matrix composite (HMMC). HMMCs are prepared with 2 Wt.% graphite and 4 Wt.% zirconium dioxide reinforced with aluminium alloy 7475 (GZR-AA7475) composite by using the stir casting method. The objective is to enhance the mechanical properties of the material while preserving its unique features. WCEDM with a 0.18 mm molybdenum wire electrode is used for machining the composite.Design/methodology/approachTo conduct experimental studies, a Taguchi L27 orthogonal array was adopted. Input variables such as peak current (Ip), pulse-on-time (TON) and flushing pressure (PF) were used. The effect of process parameters on the output responses, such as material removal rate (MRR), surface roughness rate (SRR) and wire wear ratio (WWR), were investigated. The grey relational analysis (GRA) is used to obtain the optimal combination of the process parameters. Analysis of variance (ANOVA) was also used to identify the significant process parameters affecting the output responses.FindingsResults from the current study concluded that the optimal condition for grey relational grade is obtained at TON = 105 µs, Ip = 100 A and PF = 90 kg/cm2. Peak current is the most prominent parameter influencing the MRR, whereas SRR and WRR are highly influenced by flushing pressure.Originality/valueIdentifying the optimal process parameters in WCEDM for machining of GZR-AA7475 HMMC. ANOVA and GRA are used to obtain the optimal combination of the process parameters.
目的 本研究旨在探讨线切割放电加工(WCEDM)加工 GZR-AA7475 混合金属基复合材料(HMMC)的最佳工艺参数。采用搅拌铸造法制备了 2 重量%石墨和 4 重量%二氧化锆增强铝合金 7475(GZR-AA7475)复合材料的 HMMC。其目的是在保持材料独特特性的同时提高材料的机械性能。设计/方法/途径为了进行实验研究,采用了 Taguchi L27 正交阵列。输入变量包括峰值电流 (Ip)、脉冲持续时间 (TON) 和冲洗压力 (PF)。研究了工艺参数对材料去除率 (MRR)、表面粗糙度率 (SRR) 和线材磨损率 (WWR) 等输出响应的影响。灰色关系分析(GRA)用于获得工艺参数的最佳组合。方差分析 (ANOVA) 也用于确定影响输出响应的重要工艺参数。研究结果目前的研究得出结论,在 TON = 105 µs、Ip = 100 A 和 PF = 90 kg/cm2 时,获得了灰色关系等级的最佳条件。峰值电流是影响 MRR 的最主要参数,而 SRR 和 WRR 受冲洗压力的影响较大。利用方差分析和 GRA 得出工艺参数的最佳组合。
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引用次数: 0
Investigating the impact of TiO2 filler on abrasive wear characteristics of bamboo fiber-reinforced epoxy composites using the Taguchi method 用田口方法研究 TiO2 填料对竹纤维增强环氧树脂复合材料磨料磨损特性的影响
Pub Date : 2024-01-30 DOI: 10.1108/wje-10-2023-0432
Ravikantha Prabhu, Sharun Mendonca, Pavana Kumara Bellairu, Rudolf C Dsouza, Thirumaleshwara S. G. Bhat
PurposeThe purpose of this study is to investigate the impact of titanium oxide (TiO2) filler on the abrasive wear properties of bamboo fiber reinforced epoxy composites (BFRCs) using a Taguchi approach. The study aims to enhance the abrasive wear resistance of these composites by introducing TiO2 filler as a potential reinforcement, thus contributing to the development of sustainable and environmentally friendly materials.Design/methodology/approachThis study focuses on the fabrication of epoxy/bamboo composites infused with TiO2 particles within the Wt.% range of 0–8 Wt.% using hand layup techniques. The resulting composites were subjected to wear testing according to ASTM G99-05 standards. Statistical analysis of the wear results was carried out using the Taguchi design of experiments (DOE). Additionally, an analysis of variance (ANOVA) was used to determine the influential control factors impacting the specific wear rate (SWR) and coefficient of friction (COF).FindingsThe study illuminates how integrating TiO2 filler enhances abrasive wear in epoxy/bamboo composites. Statistical analysis of SWR highlights abrasive grit size (grit) as the most influential factor, followed by normal load, Wt.% of TiO2 and sliding distance. Analysis of the COF identifies normal load as the primary influential factor, followed by grit, Wt.% of TiO2 and sliding distance. The Taguchi predictive model closely aligns with experimental results, validating its reliability. The morphological study revealed significant differences between the unfilled and TiO2-filled composites. The inclusion of TiO2 improved wear resistance, as evidenced by reduced surface damage and wear debris.Originality/valueThis research paper aims to integrate TiO2 filler and bamboo fibers to create an innovative hybrid composite material. TiO2 micro and nanoparticles show promise as filler materials, contributing to improved tribological properties of epoxy composites. The utilization of Taguchi’s DOE and ANOVA for statistical analysis provides valuable guidance for academic researchers and practitioners in optimizing control variables, especially in the context of natural fiber reinforced composites.
本研究的目的是采用田口方法研究氧化钛(TiO2)填料对竹纤维增强环氧树脂复合材料(BFRCs)磨料磨损性能的影响。该研究旨在通过引入 TiO2 填料作为一种潜在的增强材料来提高这些复合材料的耐磨损性,从而促进可持续环保材料的发展。 设计/方法/途径 该研究的重点是采用手糊技术制造环氧树脂/竹纤维复合材料,并在 0-8 重量百分比的范围内注入 TiO2 颗粒。根据 ASTM G99-05 标准对制成的复合材料进行了磨损测试。采用田口试验设计法(DOE)对磨损结果进行了统计分析。此外,还采用了方差分析 (ANOVA) 来确定影响特定磨损率 (SWR) 和摩擦系数 (COF) 的控制因素。对 SWR 的统计分析表明,磨料粒度(磨粒)是影响最大的因素,其次是正常载荷、TiO2 重量百分比和滑动距离。对 COF 的分析表明,正常载荷是主要影响因素,其次是磨粒、TiO2 重量百分比和滑动距离。田口预测模型与实验结果非常吻合,验证了其可靠性。形态学研究表明,未填充和填充 TiO2 的复合材料之间存在显著差异。TiO2的加入提高了耐磨性,表面损伤和磨损碎片的减少证明了这一点。TiO2 微粒和纳米粒子有望作为填充材料,改善环氧树脂复合材料的摩擦学性能。利用田口 DOE 和方差分析进行统计分析为学术研究人员和从业人员优化控制变量提供了宝贵的指导,尤其是在天然纤维增强复合材料方面。
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引用次数: 0
Development of a long-term solar PV power forecasting model for power system planning 为电力系统规划开发长期太阳能光伏发电预测模型
Pub Date : 2024-01-25 DOI: 10.1108/wje-09-2023-0407
Jain Vinith P.R., Navin Sam K., V. T., Joseph Godfrey A., Venkadesan Arunachalam
PurposeThis paper aims to Solar photovoltaic (PV) power can significantly impact the power system because of its intermittent nature. Hence, an accurate solar PV power forecasting model is required for appropriate power system planning.Design/methodology/approachIn this paper, a long short-term memory (LSTM)-based double deep Q-learning (DDQL) neural network (NN) is proposed for forecasting solar PV power indirectly over the long-term horizon. The past solar irradiance, temperature and wind speed are used for forecasting the solar PV power for a place using the proposed forecasting model.FindingsThe LSTM-based DDQL NN reduces over- and underestimation and avoids gradient vanishing. Thus, the proposed model improves the forecasting accuracy of solar PV power using deep learning techniques (DLTs). In addition, the proposed model requires less training time and forecasts solar PV power with improved stability.Originality/valueThe proposed model is trained and validated for several places with different climatic patterns and seasons. The proposed model is also tested for a place with a temperate climatic pattern by constructing an experimental solar PV system. The training, validation and testing results have confirmed the practicality of the proposed solar PV power forecasting model using LSTM-based DDQL NN.
本文旨在研究太阳能光伏(PV)发电因其间歇性而对电力系统产生的重大影响。本文提出了一种基于长短期记忆(LSTM)的双深度 Q 学习(DDQL)神经网络(NN),用于间接预测长期范围内的太阳能光伏发电量。结果基于 LSTM 的 DDQL 神经网络减少了高估和低估,避免了梯度消失。因此,所提出的模型利用深度学习技术(DLT)提高了太阳能光伏发电的预测精度。此外,所提出的模型所需的训练时间更短,预测太阳能光伏发电量的稳定性更高。还通过构建一个实验性太阳能光伏系统,对温带气候模式下的一个地方进行了测试。训练、验证和测试结果证实了利用基于 LSTM 的 DDQL NN 所提出的太阳能光伏发电预测模型的实用性。
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引用次数: 0
Experimental study on the behavior of pre-loaded reinforced concrete (RC) deep beams with openings strengthened with FRP sheets 用 FRP 片材加固带开口的预加载钢筋混凝土 (RC) 深梁行为的实验研究
Pub Date : 2024-01-16 DOI: 10.1108/wje-08-2023-0307
B. Osman
PurposeRecently, the repairing of reinforced concrete (RC) structures attracted great research attentions, but the research interests were mainly concentrated on common repairing types. To this end, in this paper, a repairing of pre-loaded RC beams strengthened by aramid reinforcement polymers (AFRP) is presented. Furthermore, the purpose of this paper is to study the behavior of pre-loaded RC Deep beams under sustained load. The AFRP has many advantages such as controlling stresses distribution around the openings, controlling failure modes, and enhancing the structural capacity of pre-cracked RC beams.Design/methodology/approachFour specimens were experimentally tested: one specimen without strengthening, which is considered as control specimen, one strengthened specimen using AFRP without pre-cracking and two specimens subjected to pre-cracking load before prior to AFRP application. Furthermore, after validation of experimental data by using ANSYS software, a parametric study was conducted to investigate the effect of pre-damage level on shear capacity of RC beams. For pre-cracked beams, loading was first applied until the cracking stage, followed by specimen repairing with epoxy injection, and then the specimens were loaded again until failure point.FindingsThe result showed that pre-damage level and AFRP strengthening have great influence on the ultimate strength and failure mode. In addition, the results obtained from experimental tests were compared with those from numerical validation with ANSYS and showed good agreement.Originality/valueBased on ACI guidelines, an analytical equation for calculating the shear strength of strengthened RC beams with openings subjected to pre-damage was then proposed, and the calculated results were compared with those from the tests, with differences not exceeding 10%.
目的近年来,钢筋混凝土(RC)结构的修复引起了人们的极大关注,但研究兴趣主要集中在常见的修复类型上。为此,本文介绍了一种用芳纶加固聚合物(AFRP)加固的预加载 RC 梁的修复方法。此外,本文的目的还在于研究预加载 RC 深梁在持续荷载下的行为。AFRP 有许多优点,如控制开口周围的应力分布、控制破坏模式以及提高预开裂 RC 梁的结构承载能力。设计/方法/途径对四个试样进行了实验测试:一个试样未进行加固,被视为对照试样;一个试样在未进行预开裂的情况下使用 AFRP 进行加固;两个试样在使用 AFRP 之前承受了预开裂荷载。此外,在使用 ANSYS 软件对实验数据进行验证后,还进行了参数研究,以探讨预破坏程度对 RC 梁抗剪承载力的影响。对于预开裂梁,首先加载至开裂阶段,然后注入环氧树脂对试样进行修复,最后再次加载至破坏点。原创性/价值根据 ACI 指南,提出了一个用于计算受预破坏的带开口加固 RC 梁抗剪强度的分析方程,并将计算结果与试验结果进行了比较,两者之间的差异不超过 10%。
{"title":"Experimental study on the behavior of pre-loaded reinforced concrete (RC) deep beams with openings strengthened with FRP sheets","authors":"B. Osman","doi":"10.1108/wje-08-2023-0307","DOIUrl":"https://doi.org/10.1108/wje-08-2023-0307","url":null,"abstract":"\u0000Purpose\u0000Recently, the repairing of reinforced concrete (RC) structures attracted great research attentions, but the research interests were mainly concentrated on common repairing types. To this end, in this paper, a repairing of pre-loaded RC beams strengthened by aramid reinforcement polymers (AFRP) is presented. Furthermore, the purpose of this paper is to study the behavior of pre-loaded RC Deep beams under sustained load. The AFRP has many advantages such as controlling stresses distribution around the openings, controlling failure modes, and enhancing the structural capacity of pre-cracked RC beams.\u0000\u0000\u0000Design/methodology/approach\u0000Four specimens were experimentally tested: one specimen without strengthening, which is considered as control specimen, one strengthened specimen using AFRP without pre-cracking and two specimens subjected to pre-cracking load before prior to AFRP application. Furthermore, after validation of experimental data by using ANSYS software, a parametric study was conducted to investigate the effect of pre-damage level on shear capacity of RC beams. For pre-cracked beams, loading was first applied until the cracking stage, followed by specimen repairing with epoxy injection, and then the specimens were loaded again until failure point.\u0000\u0000\u0000Findings\u0000The result showed that pre-damage level and AFRP strengthening have great influence on the ultimate strength and failure mode. In addition, the results obtained from experimental tests were compared with those from numerical validation with ANSYS and showed good agreement.\u0000\u0000\u0000Originality/value\u0000Based on ACI guidelines, an analytical equation for calculating the shear strength of strengthened RC beams with openings subjected to pre-damage was then proposed, and the calculated results were compared with those from the tests, with differences not exceeding 10%.\u0000","PeriodicalId":509668,"journal":{"name":"World Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139528677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Behavior of elastohydrodynamic lubricating film point contact problems in the unsteady state of reciprocating motion 往复运动非稳定状态下弹性流体动力润滑膜点接触问题的行为
Pub Date : 2024-01-16 DOI: 10.1108/wje-09-2023-0321
Mohamed F. Abd Alsamieh
PurposeIn this study a numerical analysis of the elastohydrodynamic lubrication point contact problem in the unsteady state of reciprocating motion is presented. The effects of frequency, stroke length and load on film thickness and pressure variation during one operating cycle are discussed. The general tribological behavior of elastohydrodynamic lubrication during reciprocating motion is explained.Design/methodology/approachThe system of equations of Reynolds, film thickness considering surface deformation and load balance equations are solved using the Newton-Raphson technique with the Gauss-Seidel iteration method. Numerical solutions were performed with a sinusoidal contact surface velocity to simulate reciprocating elastohydrodynamics. The methodology is validated using historical experimental measurements/observations and numerical predictions from other researchers.FindingsThe numerical results showed that the change in oil film during a stroke is controlled by both wedge and squeeze effects. When the surface velocity is zero at the stroke end, the squeeze effect is most noticeable. As the frequency increases, the general trend of central and minimum film thickness increases. With the same entraining speed but different stroke lengths, the properties of the oil film differ from one another, with an increase in stroke length leading to a reduction in film thickness. Finally, the numerical results showed that the overall film thickness decreases with increasing load.Originality/valueGeneral tribological behaviors of elastohydrodynamic lubricating point contact, represented by pressure and film thickness variations over time and profiles, are analyzed under reciprocating motion during one working cycle to show the effects of frequency, stroke length and applied load.
目的 本研究对往复运动非稳态下的弹性流体动力润滑点接触问题进行了数值分析。讨论了频率、冲程长度和载荷对一个运行周期内膜厚度和压力变化的影响。使用牛顿-拉斐逊技术和高斯-赛德尔迭代法求解了雷诺方程、考虑表面变形的膜厚方程和载荷平衡方程系统。采用正弦接触面速度进行数值求解,以模拟往复式弹性流体力学。数值结果表明,冲程中油膜的变化受楔形效应和挤压效应的控制。当冲程末端的表面速度为零时,挤压效应最为明显。随着频率的增加,中心油膜厚度和最小油膜厚度的总体趋势也在增加。在相同的夹带速度但冲程长度不同的情况下,油膜的特性也各不相同,冲程长度的增加会导致油膜厚度的减小。原创性/价值分析了在一个工作周期内,往复运动下弹性流体动力润滑点接触的一般摩擦学行为,表现为压力和油膜厚度随时间和轮廓的变化,以显示频率、冲程长度和施加载荷的影响。
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引用次数: 0
Entropy generation of thermophysical properties on heat and mass transfer pulsatile flow of non-Newtonian nanofluid 非牛顿纳米流体传热和传质脉动流的热物理性质熵生成
Pub Date : 2024-01-15 DOI: 10.1108/wje-04-2023-0110
F. D. Ayegbusi, A. Idowu
PurposeThe purpose of this study is to investigate the effects of entropy generation of some embedded thermophysical properties on heat and mass transfer of pulsatile flow of non-Newtonian nanofluid flows between two porous parallel plates in the presence of Lorentz force are taken into account in this research.Design/methodology/approachThe governing partial differential equations (PDEs) were nondimensionalized using suitable nondimensional quantities to transform the PDEs into a system of coupled nonlinear PDEs. The resulting equations are solved using the spectral relaxation method due to the effectiveness and accuracy of the method. The obtained velocity and temperature profiles are used to compute the entropy generation rate and Bejan number. The influence of various flow parameters on the velocity, temperature, entropy generation rate and Bejan number are discussed graphically.FindingsThe results indicate that the energy losses can be minimized in the system by choosing appropriate values for pertinent parameters; when thermal conductivity is increasing, this leads to the depreciation of entropy generation, and while this increment in thermal conductivity appreciates the Bejan number, the Eckert number on entropy generation and Bejan number, the graph shows that each time of increase in Eckert will lead to rising of entropy generation while this increase shows a reduction in Bejan number. To shed more light, these results were further demonstrated graphically. The current research was very well supported by prior literature works.Originality/valueAll results are presented graphically, and the results in this article are anticipated to be helpful in the area of engineering.
本研究的目的是探讨在存在洛伦兹力的情况下,某些嵌入式热物理性质的熵产生对两块多孔平行板之间非牛顿纳米流体脉动流的传热和传质的影响。设计/方法/途径利用合适的非量对支配偏微分方程(PDEs)进行了非量化,从而将 PDEs 转化为耦合非线性 PDEs 系统。由于频谱松弛法的有效性和准确性,因此采用该方法求解得到的方程。得到的速度和温度曲线用于计算熵产生率和贝扬数。图解讨论了各种流动参数对速度、温度、熵产生率和贝扬数的影响。结果结果表明,通过选择适当的相关参数值,可以最大限度地减少系统中的能量损失;当热导率增加时,会导致熵产生率下降,而热导率的增加会提高贝扬数、埃克特数对熵产生率和贝扬数的影响,从图中可以看出,埃克特数每次增加都会导致熵产生率上升,而熵产生率的增加会导致贝扬数下降。为了更清楚地说明这些结果,还进一步用图表进行了展示。原创性/价值所有结果都以图表形式呈现,预计本文的结果将对工程领域有所帮助。
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引用次数: 0
Electrical analysis of normal and aged high voltage transformer oil considering different size effects of Al2O3 考虑到 Al2O3 不同粒度效应的正常和老化高压变压器油电气分析
Pub Date : 2024-01-12 DOI: 10.1108/wje-10-2023-0446
M. Khodsuz, A. H. Mashhadzadeh, Aydin Samani
PurposeElectrical characteristics of transformer oil (TO) have been studied during normal and thermal aging conditions. In this paper, breakdown voltage (BDV), partial discharge (PD), heat transfer results and the physical mechanisms considering the impact of varying the diameter of Al2O3 nanoparticles (NPs) have been investigated. Different quantities of the two sizes of Al2O3 were added to the oil using a two-step method to determine the positive effect of NPs on the electrical and thermal properties of TO. Finally, the physical mechanisms related to the obtained experimental results have been performed.Design/methodology/approachThe implementation of nanoparticles in this paper was provided by US Research Nanomaterials, Inc., USA. The provided Al2O3 NPs have an average particle size of 20–80 nm and a specific surface area of 138 and 58 m2/g, respectively, which have a purity of over 99%. Thermal aging has been done. The IEC 60156 standard has been implemented to calculate the BDV, and a 500-mL volume test cell (Apar TO 1020) has been used. PD test is performed according to Standard IEC 60343, and a JDEVS-PDMA 300 device was used for this test.FindingsBDV tests indicate that 20 nm Al2O3 is more effective at improving BDV than 80 nm Al2O3, with an improvement of 113% compared to 99% for the latter. The analysis of Weibull probability at BDV indicates that 20 nm Al2O3 performs better, with improvements of 141%, 125% and 112% at probabilities of 1, 10 and 50%, respectively. The results of the PD tests using the PDPR pattern also show that 20 nm Al2O3 is superior. For the heat transfer test, 0.05 g/L of both diameters were used to ensure fair conditions, and again, the advantage was with 20 nm Al2O3 (23% vs 18%).Originality/valueThe effect of Al2O3 NP diameter (20 and 80 nm) on various properties of virgin and aged TO has been investigated experimentally in this paper to examine the effect of proposed NP on electrical improvement of TO.
目的 研究了变压器油(TO)在正常和热老化条件下的电气特性。本文研究了击穿电压 (BDV)、局部放电 (PD)、传热结果以及考虑到不同直径 Al2O3 纳米粒子 (NPs) 影响的物理机制。采用两步法将不同数量的两种尺寸的 Al2O3 添加到油中,以确定 NPs 对 TO 的电性能和热性能的积极影响。设计/方法/途径本文中的纳米粒子由美国 US Research Nanomaterials 公司提供。所提供的 Al2O3 NPs 平均粒径为 20-80 nm,比表面积分别为 138 和 58 m2/g,纯度超过 99%。已完成热老化。采用 IEC 60156 标准计算 BDV,并使用 500 毫升容量的测试池(Apar TO 1020)。结果BDV 测试表明,20 nm Al2O3 比 80 nm Al2O3 更能有效改善 BDV,前者改善了 113%,后者改善了 99%。对 BDV 的 Weibull 概率的分析表明,20 nm Al2O3 的性能更好,在概率为 1、10 和 50%时,分别提高了 141%、125% 和 112%。使用 PDPR 模式进行的 PD 测试结果也表明,20 nm Al2O3 更胜一筹。在传热测试中,为确保条件公平,两种直径的 Al2O3 均使用了 0.05 g/L,同样,20 nm Al2O3 更具优势(23% 对 18%)。原创性/价值本文通过实验研究了 Al2O3 NP 直径(20 nm 和 80 nm)对原生 TO 和老化 TO 的各种性能的影响,以考察拟议的 NP 对 TO 电性改善的影响。
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引用次数: 0
Investigation of the effects from geopathic stress on the design thickness of flexible pavements 调查地应力对柔性路面设计厚度的影响
Pub Date : 2024-01-12 DOI: 10.1108/wje-09-2023-0383
Rohit R. Salgude, Prasad Pailwan, Sunil Pimplikar, Dipak M. Kolekar
PurposeSoil is an essential component of road construction and is used in the form of subgrade materials. It ensures the stability and durability of the road under adverse conditions; being one of the important parameters, poor judgment of the engineering properties of soil can lead to pavement failure. Geopathic stress (GS) is a subtle energy in the form of harmful electromagnetic radiation. This study aims to investigate the effect of GS on soil and concrete.Design/methodology/approachA total of 23 soil samples from stress zones and nonstress zones were tested for different engineering properties like water content, liquid limit, plastic limit, specific gravity and California bearing ratio. Two concrete panels were placed on GS zones, and their quality was monitored through nondestructive testing for a period of one year.FindingsThe result shows that the engineering properties of soil and pavement thickness are increasing in stress zones as compared with nonstress zones. For concrete panels, as time passes, the quality of the concrete gets reduced, which hints toward the detrimental effect of GS.Originality/valueThis research is a systematic, scientific, reliable study which evaluated subgrade characteristics thus determining the detrimental impact of the GS on soil and pavement thickness. On a concluding note, this study provides a detailed insight into the performance of the road segment when subjected to GS. Through this investigation, it is recommended that GS should be considered in the design of roads.
目的土壤是道路建设的重要组成部分,以路基材料的形式使用。它确保道路在不利条件下的稳定性和耐久性;作为重要的参数之一,对土壤的工程特性判断不当会导致路面失效。地应力(GS)是一种以有害电磁辐射形式存在的微妙能量。本研究旨在调查地应力对土壤和混凝土的影响。设计/方法/途径对来自应力区和非应力区的 23 个土壤样本进行了不同工程特性的测试,如含水量、液限、塑限、比重和加州承载比。结果表明,与非应力区相比,应力区土壤的工程特性和路面厚度都在增加。对于混凝土面板而言,随着时间的推移,混凝土的质量会下降,这暗示了 GS 的不利影响。原创性/价值这项研究是一项系统、科学、可靠的研究,它评估了路基特征,从而确定了 GS 对土壤和路面厚度的不利影响。总之,本研究提供了受 GS 影响的路段性能的详细见解。通过这项调查,建议在设计道路时应考虑 GS。
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引用次数: 0
Low speed impact on sandwich beam with flexible core and face sheets reinforced with FG-CNTs 夹层梁受到的低速冲击,夹层梁的柔性芯材和面材使用 FG-CNT 加固
Pub Date : 2024-01-12 DOI: 10.1108/wje-07-2023-0236
Manar Hamid Jasim, A. M. Al-araji
PurposeThe purpose of this study is to model the theory of the low-velocity impact (LVI) process on sandwich beams consisting of flexible cores and face sheets reinforced with functionally graded carbon nanotubes (CNTs).Design/methodology/approachA series of parameters derived from molecular dynamics are used to consider the size scale in the mixture rule for the combination of CNTs and resin. A procedure involving the use of the first-order shear deformation theory of the beam is used to provide the displacement field of the sandwich beam. The energy method and subsequently the generalized Lagrange method are used to derive the motion equations. Due to the use of Hertz’s nonlinear theory to calculate the contact force, the equations of motion are nonlinear. Validation of the problem is carried out by comparing natural frequencies with other papers.FindingsThe influence of a series of parameters such as CNTs distributions pattern in the face sheets, the influence of the CNTs volume fraction and the influence of the core thickness to the face sheets thickness ratio in the issue of LVI on sandwich beams with clamped-clamped boundary conditions is investigated. The result shows that the type of CNTs pattern in the face sheet and the CNTs volume fraction have a very important effect on the answer to the problem, which is caused by the change in the value of the Young’s modulus of the beam at the contact surface. Changes in the core thickness to the face sheets thickness ratio has little effect on the impact response.Originality/valueConsidering the important application of sandwich structures in vehicles, aviation and ships, in this research, sandwich beams consisting of flexible core and CNTs-reinforced face sheets are investigated under LVI.
本研究的目的是模拟由功能分级碳纳米管(CNTs)增强的柔性芯材和面片组成的夹层梁的低速冲击(LVI)过程理论。使用梁的一阶剪切变形理论提供夹层梁的位移场。能量法和随后的广义拉格朗日法用于推导运动方程。由于使用赫兹非线性理论计算接触力,因此运动方程是非线性的。研究结果研究了一系列参数,如 CNTs 在面片中的分布模式、CNTs 体积分数的影响以及芯材厚度与面片厚度比对夹层梁 LVI 问题的影响。结果表明,面片中 CNTs 图案的类型和 CNTs 体积分数对问题的答案有非常重要的影响,这是由接触面处梁的杨氏模量值变化引起的。考虑到夹层结构在车辆、航空和船舶中的重要应用,本研究对由柔性芯材和 CNT 增强面片组成的夹层梁进行了低速冲击响应研究。
{"title":"Low speed impact on sandwich beam with flexible core and face sheets reinforced with FG-CNTs","authors":"Manar Hamid Jasim, A. M. Al-araji","doi":"10.1108/wje-07-2023-0236","DOIUrl":"https://doi.org/10.1108/wje-07-2023-0236","url":null,"abstract":"\u0000Purpose\u0000The purpose of this study is to model the theory of the low-velocity impact (LVI) process on sandwich beams consisting of flexible cores and face sheets reinforced with functionally graded carbon nanotubes (CNTs).\u0000\u0000\u0000Design/methodology/approach\u0000A series of parameters derived from molecular dynamics are used to consider the size scale in the mixture rule for the combination of CNTs and resin. A procedure involving the use of the first-order shear deformation theory of the beam is used to provide the displacement field of the sandwich beam. The energy method and subsequently the generalized Lagrange method are used to derive the motion equations. Due to the use of Hertz’s nonlinear theory to calculate the contact force, the equations of motion are nonlinear. Validation of the problem is carried out by comparing natural frequencies with other papers.\u0000\u0000\u0000Findings\u0000The influence of a series of parameters such as CNTs distributions pattern in the face sheets, the influence of the CNTs volume fraction and the influence of the core thickness to the face sheets thickness ratio in the issue of LVI on sandwich beams with clamped-clamped boundary conditions is investigated. The result shows that the type of CNTs pattern in the face sheet and the CNTs volume fraction have a very important effect on the answer to the problem, which is caused by the change in the value of the Young’s modulus of the beam at the contact surface. Changes in the core thickness to the face sheets thickness ratio has little effect on the impact response.\u0000\u0000\u0000Originality/value\u0000Considering the important application of sandwich structures in vehicles, aviation and ships, in this research, sandwich beams consisting of flexible core and CNTs-reinforced face sheets are investigated under LVI.\u0000","PeriodicalId":509668,"journal":{"name":"World Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139437839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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World Journal of Engineering
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