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Structural behavior of tree-like steel columns subjected to combined axial and lateral loads 树状钢柱在轴向和横向组合荷载作用下的结构性能
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0030
Rabab C. Dekhn, K. Shadhan
Abstract Few studies have been conducted on the structural behavior of steel columns with branches that are called tree-like columns. These kinds of columns have been used in many structures around the world. The purpose of this study is to investigate the failure load, vertical and lateral displacement, and failure mode of tree-like columns subjected to a combination of axial and lateral loading. The ratio of lateral load to axial load has been selected as the design variable. A finite element model with one branching level and two branches within the level was first developed using ABAQUS/CAE 2017 software. The model was verified with experimental results. The axial failure load and axial and lateral displacement were determined and compared for different loading ratios. The failure mode was also studied for different loading conditions. The results showed that the axial failure load decreased significantly by 54, 42, and 28% when lateral/axial loading ratio increased by 20, 40, and 60%, respectively. There was no significant decrease when lateral/axial loading ratio was more than 60%, while axial and lateral displacements increased significantly by 24% for each 20% increase in the loading ratio. Local buckling was observed as a failure mode when only gravity load is applied, while combined load resulted in lateral buckling.
摘要对带分支的树状钢柱的结构性能研究较少。这种类型的柱子已经在世界各地的许多结构中使用。本研究的目的是研究树状柱在轴向和侧向荷载联合作用下的破坏荷载、竖向和侧向位移以及破坏模式。横向荷载与轴向荷载的比值被选为设计变量。首先利用ABAQUS/CAE 2017软件建立了具有一个分支层和两个分支层的有限元模型。用实验结果验证了模型的正确性。测定并比较了不同加载比下的轴向破坏载荷、轴向和侧向位移。并对不同加载条件下的破坏模式进行了研究。结果表明:当横向/轴向加载比分别提高20%、40%和60%时,轴向破坏载荷分别显著降低54%、42%和28%;当横向/轴向加载比大于60%时,轴向和横向加载比每增加20%,轴向和横向位移显著增加24%。当仅施加重力荷载时,局部屈曲是一种破坏模式,而联合荷载则导致侧向屈曲。
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引用次数: 1
Calcium carbonate nanoparticles of quail’s egg shells: Synthesis and characterizations 鹌鹑蛋壳的碳酸钙纳米颗粒:合成和表征
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0001
N. Ahmed, Faten Kamil, Adnan Ali Hasso, A. N. Abduljawaad, Thekra Fadel Saleh, S. Mahmood
Abstract Avian eggshell is a natural biomaterial that has been used as an alternative natural source of CaCO3 and is accessible in big amounts from egg manufacturing. This study was planned to estimate CaCO3 in quail’s eggshell because it has a probable use in the progress of a novel choice of many applications. Physical properties: mineralogical documentation of the natural eggshell nanoparticles were approved using XRD and FTIR to explore the chemical bond or molecular structure of the materials. Micrographs were obtained using FESEM/EDX and TEM to identify the morphology and size of nanoparticles. The results showed that quail eggshell was soft, with white to light sand color, and a smooth texture which allows good deposition of different color spots, from black to brown spots. The resulted of eggshells signifies almost 8.4% w/w of the overall weight (12.2) gram of quail egg and 91.60% w/w of the micropowder to the full weight of (0.94) gram of quail eggshell. The results presented that calcium is the main element in an eggshell; frequently occurs in a formula of CaCO3 and the crystal construction was almost pure calcite. FTIR spectra for quail eggshell demonstrated the existence of the out of plane bending, the asymmetric stretching, and the plane bending styles of the carbonate groups, specific of normal dolomite, situated at 873 cm–1, 1405 cm–1, and 710 cm–1, respectively. The FESEM and TEM for nanoparticles were shown calcite CaCO3 nanoparticles with an ordinary size of ≤ 100 nm for FESEM and with a variety size of ≤ 50 nm for TEM. Unfortunately, eggshell is an egg product manufacturing deposit. These incomes will let fast developments in proportional studies of the organic elements of avian eggshell and their purposeful consequences by usages of eggshell in nourishment and medicine which can be applied for many resolutions that diminish their consequence on environmental contamination.
禽蛋壳是一种天然生物材料,已被用作CaCO3的替代天然来源,并且可以从鸡蛋制造中大量获取。本研究计划估计鹌鹑蛋壳中的CaCO3,因为它可能在许多应用的新选择的进展中使用。物理性质:利用XRD和FTIR对天然蛋壳纳米颗粒进行了矿物学记录,以探索材料的化学键或分子结构。利用FESEM/EDX和TEM对纳米颗粒的形貌和尺寸进行了表征。结果表明,鹌鹑蛋壳质地柔软,呈白色至浅砂色,质地光滑,适合沉积从黑色到棕色等不同颜色的斑点。结果表明,微粉对鹌鹑蛋壳总重(12.2)g的w/w约占8.4%,对鹌鹑蛋壳总重(0.94)g的w/w约占91.60%。结果表明:钙是蛋壳中的主要元素;经常出现在CaCO3分子式中,晶体结构几乎为纯方解石。鹌鹑壳的FTIR光谱显示,普通白云岩的碳酸盐基团分别位于873 cm-1、1405 cm-1和710 cm-1处,存在平面外弯曲、不对称拉伸和平面弯曲。纳米颗粒的FESEM和TEM显示,方解石CaCO3纳米颗粒,FESEM显示为普通尺寸≤100 nm, TEM显示为各种尺寸≤50 nm。不幸的是,蛋壳是蛋制品的制造沉积物。这些收入将促进对禽蛋壳有机成分的比例研究的快速发展,并通过蛋壳在营养和医药中的使用产生有目的的后果,这些研究可用于许多解决方案,以减少它们对环境污染的影响。
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引用次数: 7
Utilization of serial tendering to reduce the value project 利用连续招标降低项目价值
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0034
Arshed Abbas Mohammed, K. R. Erzaij
Abstract Serial tendering is better than other types of tendering when it comes to cost reduction, where civil infrastructure projects need a significant increase in the amount of tough planning, financial expenditures, engineering work, and resources of a different character than other types of construction projects. The effects of a lack of funding cause decrease in the completion speed of the project on time. The need to reduce the cost of bidding on recurrent civil infrastructure projects is critical. To achieve the desired goals of this research, this article will provide an overview of the type of bids used in the construction of schools implemented in the current financial perspective in Iraq, the extent of benefit, and the amount of possible reduction if continuous and serial tendering are used.
摘要在降低成本方面,串行招标比其他类型的招标要好,因为民用基础设施项目需要大幅增加艰难的规划、财务支出、工程工作量和与其他类型的建设项目不同的资源。缺乏资金的影响导致项目按时完成的速度下降。降低经常性民用基础设施项目投标成本的必要性至关重要。为了实现本研究的预期目标,本文将概述在伊拉克当前财政角度下实施的学校建设中使用的投标类型、收益程度以及如果使用连续和连续投标可能减少的金额。
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引用次数: 1
Response of composite steel-concrete cellular beams of different concrete deck types under harmonic loads 不同混凝土板型钢-混凝土组合孔形梁在谐波荷载作用下的响应
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0014
Zahraa Hussien Dakhela, S. D. Mohammed
Abstract This study aims to investigate the adequacy of composite cellular beams with lightweight reinforced concrete deck slab as a structural unit for harmonic loaded buildings. The experimental program involved three fixed-ends supported beams throughout 2140 mm. Three concrete types were included: Normal Weight Concrete (NWC), Lightweight Aggregate Concrete (LWAC), and Lightweight Fiber Reinforced Aggregate Concrete (LWACF). The considered frequencies were (5, 10, 15, 20, 25, and 30) Hz. It was indicated that the harmonic load caused a significant influence on LWAC response (64% greater than NWC) and lattice cracks were observed, especially at 30 Hz. As for LWACF slab, no cracks appeared, and the harmonic load had a minor effect on the vibration amplitude. Adding fiber to LWAC improved its behavior and made the amplitude no more than 11.11%, corresponding to NWC. So, the response variance for the LWACF was approximately negligible compared with NWC. It is worth mentioning that the study produced a lightweight structure that resists harmonic vibrations with a small strength reduction by using LWACF as a deck-slab for cellular specimens and provides a structural element with a smaller density of about 27%, which presents an advantage for the cellular beam that is adopted for low-loaded structures.
摘要本研究旨在研究以轻质钢筋混凝土桥面板为结构单元的组合单元梁在谐波荷载建筑中的适用性。实验项目涉及三根2140mm长的固定端支撑梁。包括三种混凝土类型:正常重量混凝土(NWC)、轻骨料混凝土(LWAC)和轻纤维增强骨料混凝土(LWACF)。所考虑的频率为(5、10、15、20、25和30)Hz。研究表明,谐波负载对LWAC响应产生了显著影响(比NWC大64%),并观察到晶格裂纹,尤其是在30Hz时。对于LWACF板坯,没有出现裂纹,谐波载荷对振幅的影响较小。在LWAC中加入光纤改善了其性能,使其振幅不超过11.11%,相当于NWC。因此,与NWC相比,LWACF的响应方差几乎可以忽略不计。值得一提的是,该研究通过使用LWACF作为蜂窝试件的桥面板,产生了一种轻型结构,该结构能够抵抗谐波振动,强度降低较小,并提供了密度较小的结构元件,约为27%,这为低荷载结构所采用的蜂窝梁带来了优势。
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引用次数: 2
A spherical fuzzy AHP model for contractor assessment during project life cycle 项目全生命周期承包商评价的球面模糊层次分析法
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0042
Hayder Ghazi Abdulkareem, K. R. Erzaij
Abstract Measurement of construction performance is essential to a clear image of the present situation. This monitoring by the management team is necessary to identify locations where performance is exceptionally excellent or poor and to identify the primary reasons so that the lessons gained may be exported to the firm and its progress strengthened. This research attempts to construct an integrated mathematical model utilizing one of the recent methodologies for dealing with the fuzzy representation of experts’ knowledge and judgment considering hesitancy called spherical fuzzy analytic hierarchy process (SFAHP) method to assess the contractor’s performance per the project performance parameters (cost, schedule, quality, leadership, and change management). At the same time, most project control systems are currently applied through software like Primavera P6 or MS Project. These look at a project’s cost and schedule status by following the earned value analysis for finding the performance. Based on decision makers’ preferences, the analytic hierarchy process (AHP) may be used to arrive at the optimum conclusion. AHP approaches are discussed, including AHP, grey-AHP, fuzzy-AHP, and SFAHP weights comparison. Calculation results showed that the spherical fuzzy approach differs significantly from the other approaches where it considers the decision maker’s hesitation when making linguistic multicriteria decisions and then, as a result, recommends applying periodically for performance measurement. This model can be viewed as a valuable way to help the decision-making stakeholders in the construction sector do the best job about critical issues at a suitable time.
摘要建筑性能的测量对于清晰地了解现状至关重要。管理团队的这种监测是必要的,以确定绩效异常优秀或较差的地点,并确定主要原因,从而将所获得的经验教训输出到公司,并加强其进展。本研究试图利用一种最新的方法来处理专家知识和判断的模糊表示,并考虑到犹豫,构建一个综合数学模型,称为球面模糊层次分析法(SFAHP),根据项目绩效参数评估承包商的绩效(成本、进度、质量、领导力和变更管理)。同时,目前大多数项目控制系统都是通过Primavera P6或MS project等软件应用的。它们通过遵循挣值分析来查找性能,从而查看项目的成本和进度状态。基于决策者的偏好,可以使用层次分析法(AHP)来得出最优结论。讨论了AHP方法,包括AHP、灰色AHP、模糊AHP和SFAHP权重比较。计算结果表明,球形模糊方法与其他方法有很大不同,在其他方法中,球形模糊算法考虑了决策者在做出语言多准则决策时的犹豫,因此建议定期应用于绩效衡量。该模型可以被视为一种有价值的方式,帮助建筑行业的决策利益相关者在适当的时候就关键问题做得最好。
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引用次数: 2
Investigation on microstructural features and tensile shear fracture properties of resistance spot welded advanced high strength dual phase steel sheets in lap joint configuration for automotive frame applications 汽车车架搭接结构高级高强度双相钢电阻点焊微结构特征及拉伸剪切断裂性能研究
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0006
C. Rajarajan, P. Sivaraj, Tushar Sonar, S. Raja, N. Mathiazhagan
Abstract The main objective of this research paper is to study the microstructural features and mechanical properties of resistance spot welded advanced high-strength steel of dual phase grade in lap joint configuration which is mainly employed in sheet form for fabrication of the automotive structure. Resistance spot welding (RSW) being a solid-state welding (SSW) process is used to overcome the problems in fusion welding of AHSS-DP steel such as heat affected zone (HAZ) softening, solidification cracking and distortion which significantly deteriorates the mechanical properties of AHSS-DP800 steel joints. The straight lap (SL-TSFL) and cross lap tensile shear fracture load (CL-TSFL) of spot joints were evaluated. Optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques were used to characterize the weld nugget. The X-ray diffraction (XRD) results are also presented for phase identification in the weld nugget. The fracture surface of failed TSFL specimens was analyzed using SEM. The lap joints made using RSW disclosed superior SL-TSFL, CL-TSFL, and WNZH of 21.7 kN, 17.65 kN, and 589 HV0.5 The superior joint strength and hardness of the weld nugget zone are correlated to the evolution of lath martensite in the nugget zone.
摘要本论文的主要目的是研究主要用于汽车结构件薄板制造的双相级高级高强度钢搭接电阻点焊的显微组织特征和力学性能。电阻点焊(RSW)是一种固态焊接(SSW)工艺,用于克服AHSS-DP800钢在熔焊中存在的热影响区(HAZ)软化、凝固开裂和变形等问题,这些问题严重影响了AHSS-DP800钢接头的力学性能。对点节点的直搭接(SL-TSFL)和交叉搭接拉伸剪切断裂载荷(CL-TSFL)进行了评价。采用光学显微镜(OM)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)技术对焊缝熔核进行了表征。给出了焊缝熔核的x射线衍射(XRD)结果。利用扫描电镜对失效TSFL试样的断口形貌进行了分析。RSW搭接接头的SL-TSFL、CL-TSFL和WNZH分别为21.7 kN、17.65 kN和589 HV0.5,接头强度和硬度的提高与焊核区板条马氏体的演化有关。
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引用次数: 5
Ultimate bearing capacity of eccentrically loaded square footing over geogrid-reinforced cohesive soil 土工格栅加筋粘性土偏心加载方基础极限承载力研究
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0035
Hussam Aldeen J. Hassan, R. R. Shakir
Abstract Construction of shallow foundations on weak cohesive soils have limited load-bearing capacity and excessive vertical displacement. This may cause structural damage and reduce the structure’s durability. Traditionally, weak cohesive soils are excavated and replaced with another stronger material layer, or the foundation is enlarged. These procedures are costly and time-consuming. However, these soils are also difficult to stabilize due to their low permeability and slow consolidation. Therefore, it has become necessary to use geosynthetic material. In this study, a square footing model with an eccentric load was tested in geogrid-reinforced clay. The adopted load eccentricity ratios were 0.05 to 0.1, 0.16, and 0.25. Twenty-one tests were executed to estimate the reinforcement influence and eccentricity on the ultimate bearing capacity (UBC). The geogrid improved the BC by 2.27 and 2.12 times compared to unreinforced soil for centrical and eccentrical loads, respectively. The best first layer ratio and the best number of reinforcements were found to be 0.35 and 4. A new equation for BCR with knowing the number of reinforcing layers was proposed and compared with other studies’ outcomes. It was concluded that the foundation tilts in a linear relationship with eccentricity, with a smaller rate inside the core than outside.
摘要在弱粘性土上进行浅基础施工,存在承载能力有限、竖向位移过大的问题。这可能会造成结构损坏,降低结构的耐久性。传统的做法是挖掘弱粘性土并用另一层较强的材料层代替,或者扩大地基。这些程序既昂贵又费时。然而,由于其渗透性低,固结缓慢,这些土壤也难以稳定。因此,使用土工合成材料已成为必要。在土工格栅加筋粘土中进行了偏心荷载作用下的方基础模型试验。采用的载荷偏心比分别为0.05 ~ 0.1、0.16和0.25。进行了21次试验,以估计配筋和偏心对极限承载力的影响。在中心荷载和偏心荷载作用下,土工格栅比未加筋土的BC分别提高了2.27倍和2.12倍。最佳第一层比为0.35,最佳加筋数为4。提出了一个新的已知加筋层数的BCR方程,并与其他研究结果进行了比较。结果表明,地基倾斜与离心率呈线性关系,且核心内部的倾斜比核心外部的倾斜要小。
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引用次数: 0
Comparison of time extension provisions between the Joint Contracts Tribunal and Iraqi Standard Bidding Document 联合合同法庭和伊拉克标准招标文件延期规定的比较
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0063
Wurood R. Zain-alabdeen, Sawsan M. Rasheed
Abstract Many contractors face challenges in completing the project on time due to delays arising for various reasons, including reasons beyond the contractor’s control, such as force majeure, exceptionally bad weather conditions, changes, etc. As a result, contractors submit a time extension claim to make up for lost time and set a later completion date to complete the project. Each contract has its terms for the extension of time (EOT). Therefore, the objective of this article is to study the provisions for extending the time when the reasons are beyond the control of the contractor according to Iraqi Standard Bidding Documents for Procurement of Works (SBDW) and the Joint Contracts Tribunal (SBC/Q 2016). The article also aims to show the extent of the difference between the two contracts in applying these provisions. The study found that when submitting a claim in the Iraqi SBDW, the contractor shall consider the notifications relating to it as per the specified period. Therefore, they will not be considered if claims are submitted after that period. In SBC/Q 2016, submitting a claim notice is not required to gain additional time. Therefore, the failure to provide notice does not forfeit the right to claim additional time. This study enhances the contractor’s knowledge of the terms related to the EOT under the two contracts, reducing the disputes resulting from a misunderstanding of these provisions.
摘要由于各种原因造成的延误,包括不可抗力、异常恶劣的天气条件、变化等承包商无法控制的原因,许多承包商在按时完成项目方面面临挑战。因此,承包商提出延期索赔,以弥补损失的时间,并设定更晚的完工日期来完成项目。每份合同都有其延期条款。因此,本条的目的是研究根据伊拉克工程采购标准招标文件(SBDW)和联合合同法庭(SBC/Q 2016),当原因超出承包商控制范围时延长时间的规定。该条还旨在说明两份合同在适用这些条款方面的差异程度。研究发现,在伊拉克SBDW提交索赔时,承包商应按照规定的期限考虑与之相关的通知。因此,如果在此期间之后提出索赔,则不考虑这些索赔。在SBC/Q 2016中,提交索赔通知无需获得额外时间。因此,未提供通知并不丧失要求额外时间的权利。这项研究提高了承包商对两份合同下EOT相关条款的了解,减少了因误解这些条款而产生的争议。
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引用次数: 1
Flexural behavior of concrete beams with horizontal and vertical openings reinforced by glass-fiber-reinforced polymer (GFRP) bars 玻璃纤维增强聚合物(GFRP)钢筋加固水平和垂直开口混凝土梁的弯曲性能
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0045
Hasani Ali, A. Said
Abstract This study conducted an analytical investigation on the behavior of concrete beams with openings reinforced by glass-fiber-reinforced polymer (GFRP) bars. In this study, five proposed beams reinforced by GFRP bars as flexural and shear reinforcement with openings were numerically examined. The variables were the opening orientation (vertical and horizontal) and the number of openings. These openings were located within the flexural zone of the proposed beams. The result shows that the vertical openings had a significant effect over the horizontal openings on reducing the ultimate load and increasing the mid-span deflection compared with the control beam. Moreover, the results showed that when replacing two adjacent openings by one equivalent opening, the capacity of the beam is decreased.
摘要本研究对玻璃纤维增强聚合物(GFRP)钢筋加固开孔混凝土梁的性能进行了分析研究。在本研究中,对五个拟采用GFRP钢筋作为开口抗弯和抗剪钢筋的梁进行了数值分析。变量是开口方向(垂直和水平)和开口数量。这些开口位于拟建梁的弯曲区内。结果表明,与控制梁相比,竖向开孔在降低极限荷载和增加跨中挠度方面比水平开孔有显著的效果。此外,结果表明,当用一个等效开孔替换两个相邻开孔时,梁的承载力会降低。
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引用次数: 4
Influences of pre-bending load and corrosion degree of reinforcement on the loading capacity of concrete beams 预弯荷载和钢筋锈蚀程度对混凝土梁承载力的影响
IF 1.8 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2022-01-01 DOI: 10.1515/jmbm-2022-0061
The Truyen Tran, Thúy Minh Trần, X. Nguyen, Duc Hieu Nguyen, BaThao Vu, V. Vo
Abstract In this article, experimental studies on the flexural behavior of concrete beams with corroded reinforcement were conducted. The beams were subjected to simultaneous different load levels and immersed in NaCl solution for 30 days with accelerated corrosion. A four-point bending test was subsequently carried out to determine the loading capacity of these beams. Experimental data show that the loading capacity of the beam decreases as the level of preload increases. The mass loss of steel bars in the beams increases as the level of preload increases. The loading capacity and steel mass loss of the beams subjected to 0.8 of failure load of the non-corroded beam decrease by 32.7 and 30.3%, respectively. The numerical investigation was also done to evaluate the loading capacity with various corrosion degrees of steel bars.
摘要本文对锈蚀钢筋混凝土梁的受弯性能进行了试验研究。梁同时承受不同的荷载水平,并在NaCl溶液中浸泡30天,加速腐蚀。随后进行了四点弯曲试验,以确定这些梁的承载能力。实验数据表明,梁的承载能力随着预载水平的增加而降低。梁中钢筋的质量损失随着预载水平的增加而增加。在未腐蚀梁的0.8破坏荷载作用下,梁的承载力和钢质量损失分别降低了32.7%和30.3%。数值研究还评估了钢筋在不同腐蚀程度下的承载能力。
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引用次数: 0
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Journal of the Mechanical Behavior of Materials
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