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Energy Efficiency Analysis of Natural Convection Heat Transfer in Concentric Annulus with Interior and Exterior Grooves 带有内部和外部凹槽的同心环中自然对流传热的能效分析
Q3 Engineering Pub Date : 2023-12-07 DOI: 10.37394/232011.2023.18.25
K. B. Abdelmlek, F. B. Nejma
This study is a numerical investigation of the convective heat transfer in motionless concentric annulus composed of two horizontal cylinders, one of which is grooved. The inner cylinder is kept at hot temperature Th and the outer one is kept at cold temperature Tc. The aim of this paper is to analyze the effect of the groove on thermal and dynamic behavior in the annulus when the groove is located on the hot cylinder (inner groove), and when it is located on the cold cylinder (exterior groove). To observe the effect the inner and outer groove on the flow structure and on the heat transfer rate, the groove is positioned at ϕ0=-90̊, -45̊, 0 ̊, 45 ̊, and 90̊. Moreover, the groove size (f) and the radius ratio (e) of the annulus have been changed to investigate their effects on heat transfer rate as well as on the energy efficiency of the process. The results show that the heat transfer rate rises up with the increase of Rayleigh number. It is seen that; in the case of the inner groove; the heat transfer rate reaches a maximum at ϕ0=40̊, whatever the groove size. Furthermore, the energy efficiency of the process is maximum when the inner groove is positioned at ϕ0=90̊, and it increases well with the increase of f. On the other hand, in the case of the exterior groove, the heat transfer rate is practically close to that of non-grooved annulus for f<0.7. A decrease of 34% of the energy efficiency is noticed with the increase of the size of the groove to f=0.7. Our results would be very useful for manufacturers who are looking for increasing the energy efficiency of their process, or also who need to boost or decrease the heat transfer rate depending on the objective of their process.
本文研究了由两个水平圆柱体组成的静止同心环空的对流换热问题。内筒保持在高温Th,外筒保持在低温Tc。本文的目的是分析槽位于热筒上(内槽)和冷筒上(外槽)时,槽对环空热动态性能的影响。为了观察内外槽对流动结构和换热率的影响,将槽位设置在ϕ0=-90°、-45°、0°、45°和90°。此外,还改变了环空的凹槽尺寸(f)和半径比(e),以研究它们对传热速率和过程能量效率的影响。结果表明:传热速率随瑞利数的增加而增大;可见;在内槽的情况下;无论沟槽尺寸如何,传热率在ϕ0=40℃时达到最大值。此外,当内槽位于ϕ0=90°时,工艺的能量效率最大,并且随着f的增加而增加。另一方面,对于外槽,当f<0.7时,传热率实际上与无槽环空的传热率接近。当沟槽尺寸增大到f=0.7时,能量效率下降了34%。我们的结果对于那些正在寻求提高其工艺的能源效率,或者需要根据其工艺目标提高或降低传热速率的制造商来说非常有用。
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引用次数: 0
Derivation of Key Characteristics of Columns in Frames with Sway 带摇摆框架中柱的关键特性推导
Q3 Engineering Pub Date : 2023-11-14 DOI: 10.37394/232011.2023.18.24
Jostein Hellesland
The paper paper examines columns of elastic frames that are able to displace laterally under axial load. Columns on the same level (story) of such frames may contribute to lateral support (stability) or require lateral support (supported columns). In the former case, maximum moments will occur at column ends, but may occur between column ends in the latter case. The column response, including the formation of moments and shears, is often complicated, often calling for approximate analysis methods and information that presently may not be readily available. Main attention of the paper is paid to providing results that will be helpful in providing, in a rather simple manner, improved understanding of column mechanics, and that may be helpful also as a supplement to full second-order analyses. Towards this goal, the major objective of the paper is threefold: (i) to identify characteristic points, or behavioral“landmarks” in the axial load-moment solution space, through the study of rotationally restrained elastic columns and two-column panels with sidesway; (ii) to derive simple, novel, closed-form expressions for these, thereby providing a tool simplifying the establishment of the variation of end and maximum moments versus axial load; (iii) to identify to what extent isolated (single) column analyses may adequately represent horizontally interacting columns, and potential unwinding, in frames.
论文论文检查的弹性框架柱,能够横向位移轴向载荷下。这种框架的同一水平(楼层)上的柱可能有助于横向支撑(稳定)或需要横向支撑(支撑柱)。在前一种情况下,最大矩将出现在列端,但在后一种情况下,最大矩可能出现在列端之间。柱的响应,包括弯矩和剪力的形成,往往是复杂的,往往需要近似的分析方法和信息,目前可能不容易获得。本文的主要注意力是提供的结果,将有助于提供,在一个相当简单的方式,提高柱力学的理解,这也可能是有益的补充,以充分的二阶分析。为了实现这一目标,本文的主要目标有三个:(i)通过对旋转约束弹性柱和带侧移的双柱板的研究,确定轴向荷载-矩解空间中的特征点或行为“地标”;(ii)推导出简单的、新颖的、封闭形式的表达式,从而提供一种工具,简化建立端弯矩和最大弯矩随轴向载荷的变化;(iii)确定在多大程度上孤立(单)柱分析可以充分代表框架中水平相互作用的柱和潜在的unwind。
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引用次数: 0
Modelling of Crack Formation and Growth using FEM for Selected Structural Materials at Static Loading 选定结构材料在静载荷作用下裂纹形成和扩展的有限元模拟
Q3 Engineering Pub Date : 2023-11-01 DOI: 10.37394/232011.2023.18.23
Vladislav Kozák, Jiří Vala
The purpose of this paper is to show the results of a study focused on the occurrence of damage heterogeneous materials, especially on the issue of modelling crack formation and propagation. In the beginning the attention is paid to the direct application of the finite element method to different types of materials in order to find critical parameters determining behaviour of materials at damage process. The applications of damage mechanics and possible approaches to model the origin of a crack propagation through modifications in FEM systems are presented and some practical applications are tested. Main effort is devoted to cement fibre composites and the search for new methods for their more accurate modelling, especially close to the field stress concentrator, respectively ahead of the crack tip. Modified XFEM method has been used as a suitable tool for numerical modelling.
本文的目的是展示一项研究的结果,重点是损伤非均质材料的发生,特别是在模拟裂纹的形成和扩展问题。首先关注的是将有限元方法直接应用于不同类型的材料,以找到决定材料在损伤过程中的行为的关键参数。介绍了损伤力学在有限元系统中的应用以及通过修正来模拟裂纹扩展起源的可能方法,并对一些实际应用进行了测试。主要的工作是致力于水泥纤维复合材料和寻找新的方法,为他们更准确的建模,特别是接近应力场集中,分别在裂缝尖端之前。改进的XFEM方法已被用作一种合适的数值模拟工具。
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引用次数: 0
Application of Acoustic-solid Coupling Theory in New Energy Vehicle Noise Control 声固耦合理论在新能源汽车噪声控制中的应用
Q3 Engineering Pub Date : 2023-10-26 DOI: 10.37394/232011.2023.18.22
Fujun Mao
The development of new energy vehicles has attracted much attention due to the strong promotion and popularisation of the concept of low carbon and environmental protection, and the increasing demand for environmental protection in cars. Although these vehicles meet people’s requirements for resource and environmental protection, the noise generated during the driving process affects the comfort of the vehicle occupants and the concentration of the vehicle driver. To address this problem, the research proposes to improve the noise control technology of new energy vehicles based on acoustic-solid coupling theory and to test the practical application effect of this technology. The test results show that the maximum acceleration of vibration at the roof, floor, axle head, and spring of the new energy vehicle are 1.48 m/s2, 1.02 m/s2, 0.079 m/s2, and 0.020 m/s2 respectively, which are lower than the maximum acceleration before the use of this technology. The maximum sound pressure at the windscreen and side window glass of the new energy vehicle is 80 dB(A) and 73 dB(A) after the use of this technology. The maximum sound pressure at the driver’s ear was 62 dB(A) and 77 dB(A) when the vehicle was driven on different road surfaces, which were lower than the sound pressure values before use. In summary, the research proposes to improve the noise control technology of new energy vehicles based on the sound-solid coupling theory, which can have the effect of reducing the noise value generated by new energy vehicles and improving the comfort of users.
由于低碳环保理念的大力推广和普及,以及汽车对环保的需求不断增加,新能源汽车的发展备受关注。这些车辆虽然满足了人们对资源和环境保护的要求,但在行驶过程中产生的噪声影响了车辆乘员的舒适度和车辆驾驶员的注意力。针对这一问题,本研究提出改进基于声固耦合理论的新能源汽车噪声控制技术,并测试该技术的实际应用效果。试验结果表明,新能源汽车车顶、地板、轴头和弹簧处的最大振动加速度分别为1.48 m/s2、1.02 m/s2、0.079 m/s2和0.020 m/s2,均低于采用该技术前的最大振动加速度。采用该技术后,新能源汽车挡风玻璃和侧窗玻璃处的最大声压分别为80 dB(A)和73 dB(A)。在不同路面行驶时,驾驶员耳侧最大声压分别为62 dB(A)和77 dB(A),均低于使用前的声压值。综上所述,本研究提出基于声固耦合理论对新能源汽车噪声控制技术进行改进,可以起到降低新能源汽车产生的噪声值,提高用户舒适度的效果。
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引用次数: 0
A Mathematical method for Calculating the Retentive Force of Ring Clasps when Designing the Removable Partial Denture Metal Frame 设计可摘局部义齿金属架时计算环卡环固位力的数学方法
Q3 Engineering Pub Date : 2023-10-23 DOI: 10.37394/232011.2023.18.21
Laith Mahmoud Abdulhadi Al-Samawi
Practically, calculating the retentive force of the clasps used as a part of removable partial dentures testing of general retention. This test is done using a universal testing machine or a pull test kit. However, these techniques aren't feasible until after designing and fabricating the framework. Therefore, a calculating method or formula based on the variables affecting the retentive force of any clasp seems necessary while developing the framework and before the final casting of the partial denture. The objective of this experiment is to determine the formula that mathematically estimates the pulling force of four-ring clasps in vitro. The experiment included the fabrication and recording of pullout forces for four types of ring clasps; then, the variables were identified and related to the retentive force mathematically. An equation was generated to count the retentive force for the four clasps and assess the precision of the results. In addition, the retentive arm sizes were correlated to the pulling forces using the Pearson coefficient. In conclusion, a new mathematical method was presented to the profession using simple math. The method is a practical and simple way to enhance the selection of clasps concerning their retentive force in addition to the other design factors. Therefore, additional tools for creating the removable partial denture with a bio-protective concept were displayed, and further research should be done to analyze the force generated by other clasps to make a global system to be added to the software for designing the partial dental framework.
在实际应用中,计算了作为可摘局部义齿一部分的卡环的固位力,并进行了一般固位试验。该测试使用通用试验机或拉式测试套件完成。然而,这些技术在设计和制造框架之前是不可行的。因此,在开发框架和最终铸造部分义齿之前,基于影响任何卡环固位力的变量的计算方法或公式似乎是必要的。本实验的目的是确定四环扣在体外拉力的数学估计公式。实验包括制作和记录四种环扣的拉拔力;然后,对变量进行识别,并将其与固力进行数学关联。生成一个方程来计算四个卡环的固位力并评估结果的精度。此外,利用Pearson系数将固位臂尺寸与拉力进行了相关性分析。总之,用简单的数学方法为行业提供了一种新的数学方法。该方法是一种简便实用的方法,可以在考虑卡环固位力的同时,提高卡环的选择。因此,展示了用于制作具有生物保护概念的可摘局部义齿的额外工具,并进一步研究分析其他卡环产生的力,以便将全局系统添加到局部义齿框架设计软件中。
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引用次数: 0
Addressing the Primary and Subharmonic Resonances of the Swing Equation 求解摆动方程的主谐波和次谐波共振
Q3 Engineering Pub Date : 2023-10-13 DOI: 10.37394/232011.2023.18.19
Anastasia Sofroniou, Bhairavi Premnath
A research investigation is undertaken to gain a more comprehensive understanding of the primary and subharmonic resonances exhibited by the swing equation. The occurrence of the primary resonance is characterised by amplified oscillatory reactions, voltage instability, and the possibility for system failure. The phenomenon of subharmonic resonance arises when the frequency of disturbance is a whole-number fraction of the natural frequency. This results in the occurrence of low-frequency oscillations and the potential for detrimental effects on equipment. The objective of this study is to expand upon the current literature regarding the impacts of primary resonance and enhance comprehension of subharmonic resonance in relation to the stability of a specific power system model. The analytical and numerical tools are utilised to investigate the fundamental principles of this resonant-related problem, aiming to provide an effective control solution. This choice is driven by the model’s complex nonlinear dynamical behaviour, which offers valuable insights for further analysis. This analysis includes the Floquet Method, the Method of strained parameters, and the concept of tangent instability in order to provide an extension to existing literature relating to primary and subharmonic resonances, taking into account the dynamic and bifurcation characteristics of the swing equation. This objective will be achieved through the utilisation of both analytical and numerical methods, enabling the identification of specific indicators of chaos that can contribute to the safe operation of real-world scenarios.
为了更全面地了解摆动方程所表现出的初级和次谐波共振,进行了一项研究调查。发生主共振的特点是振荡反应放大、电压不稳定和系统故障的可能性。当扰动频率为固有频率的整数分数时,会产生次谐波谐振现象。这导致低频振荡的发生和对设备的潜在有害影响。本研究的目的是在现有文献的基础上扩展关于主共振的影响,并加强对次谐波共振与特定电力系统模型稳定性的理解。利用分析和数值工具来研究这种谐振相关问题的基本原理,旨在提供有效的控制解决方案。这种选择是由模型复杂的非线性动力学行为驱动的,这为进一步的分析提供了有价值的见解。该分析包括Floquet方法、应变参数法和切线不稳定性的概念,以提供对现有文献有关初级和次谐波共振的扩展,考虑到摆动方程的动态和分岔特性。这一目标将通过利用分析和数值方法来实现,从而能够识别特定的混沌指标,从而有助于现实世界场景的安全运行。
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引用次数: 0
Torsion of the Truncated Hollow Orthotropic Elastic Body of Rotation 截断空心正交各向异性旋转弹性体的扭转
Q3 Engineering Pub Date : 2023-10-13 DOI: 10.37394/232011.2023.18.18
István Ecsedi, Attila Baksa, Marwen Habbachi
This paper deals with the torsion of the body of rotation. The meridian section of the body is bounded by two ellipses and two straight lines which are perpendicular to the axis of rotation of the body. The material of the body is elastic and cylindrical orthotropic. To solve the torsion problem, the theory of the torsion of shafts of varying circular cross-sections is used, which was developed by Mitchell and Töppl. An analytical solution is given for the shearing stresses and circumferential displacement. A numerical example illustrates the application of the presented analytical solution. The results of this paper can be used as a benchmark solution to verify the accuracy of the results computed by finite element simulations and finite different methods.
本文讨论了旋转体的扭转问题。物体的子午线由两条椭圆和两条垂直于物体旋转轴的直线所包围。身体的材料是弹性和圆柱形正交各向异性。为了解决扭转问题,采用了米切尔和Töppl提出的变圆截面轴的扭转理论。给出了剪切应力和周向位移的解析解。数值算例说明了该解析解的应用。本文的计算结果可作为基准解,验证有限元模拟和有限不同方法计算结果的准确性。
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引用次数: 0
Methodology for 3D Scanning of Objects 物体三维扫描方法学
Q3 Engineering Pub Date : 2023-10-13 DOI: 10.37394/232011.2023.18.20
Miglena Paneva, Peter Panev, Nikolay Stoimenov, Stanislav Gyoshev
In the present work an overview and analysis of 3D scanning, as well as its application in industry, is made. А methodology for 3D scanning of an object using a portable 3D scanner EinScan HX has been compiled. A lifter with a rectangular shape is used for a scanning object. The steps that are performed to visualize a 3D model of the object will be presented in detail. Through the software programs Geomagic Essentials and Solid Edge, its dimensions can be determined and, if necessary, adjusted. The developed model can be used for a standard technology of production or by using 3D printing technology if it allows the use of this type of material.
本文对三维扫描技术及其在工业中的应用进行了综述和分析。А使用便携式3D扫描仪EinScan HX对对象进行3D扫描的方法已编制。矩形升降机用于扫描对象。将详细介绍为可视化对象的3D模型所执行的步骤。通过软件程序Geomagic Essentials和Solid Edge,可以确定其尺寸,并在必要时进行调整。开发的模型可以用于标准的生产技术或通过使用3D打印技术,如果它允许使用这种类型的材料。
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引用次数: 0
Finding the Weight Difference of a Rectangular Structure with a Parabolic Arc for Mathematical Models Made of Steel and other Composite Materials 用钢和其他复合材料制作的数学模型求带抛物线的矩形结构的重量差
Q3 Engineering Pub Date : 2023-09-28 DOI: 10.37394/232011.2023.18.17
Tymor Abed Alsttar Sediqer, Emad Toma Karash, Jamal Nayief Sultan, Majid Khaleel Najem
The most popular materials for lightweight constructions, including building and aircraft structures, industrial, military, and aerospace technology, are armored composites. Composites made of carbon fiber are typically employed in lightweight applications. The ANSYS program was used to produce four mathematical models. Steel is used in the construction of the first and second versions whereas composite materials are used in the third and fourth variants. To find all the deformations, stresses, and strains that appear on the four models, as well as to calculate the weights of those four structures and compare them, these four models were tested with the ANSYS 15.0 program to obtain equal deformation resistance for all models under the influence of different loads. The results show that the composite models had lower strains, stresses, and deformations than the steel models. Among other results, it was discovered that the weight of the third model made of composite materials decreased by (32.72%) compared to the steel-based first model, and after doing the necessary calculations and assessing the results, the fourth model made of composite materials' weight was reduced by (19.21%) when compared to the second model made of steel.
轻型结构,包括建筑和飞机结构,工业,军事和航空航天技术,最流行的材料是装甲复合材料。碳纤维制成的复合材料通常用于轻量化应用。利用ANSYS程序建立了四种数学模型。钢在第一和第二版本的结构中使用,而复合材料在第三和第四版本中使用。为了找出四种模型上出现的所有变形、应力和应变,并计算出四种结构的权重并进行比较,使用ANSYS 15.0程序对这四种模型进行了测试,以获得所有模型在不同荷载作用下的变形抗力相等。结果表明,复合材料模型具有较低的应变、应力和变形。在其他结果中,发现复合材料制成的第三个模型的重量比基于钢的第一个模型减少了(32.72%),经过必要的计算和评估结果,复合材料制成的第四个模型的重量比基于钢的第二个模型减少了(19.21%)。
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引用次数: 0
Experimental Determination of Grinding Parameters using a Ball Mill with Innovative Lifters 采用新型提升装置的球磨机磨削参数的实验确定
Q3 Engineering Pub Date : 2023-09-25 DOI: 10.37394/232011.2023.18.16
Miglena Paneva, Peter Panev, Nikolay Stoimenov
In the developed work, experiments were made with a laboratory ball mill with a liner with symmetrical displaced eight innovative lifters with a spheroidal tetrahedron type. Based on experiments done in a previous study, the number of lifters with innovative shapes, as well as their sizes, were determined. The additive material used for grinding media is PLA material and for grinding bodies PLA, SteelFill (based on PLA), and CarbonFilTM (based on PETG) are used which are printed on a 3D printer. The mill’s critical speed (CS), the angle of separation (shoulder angle), and the toe angle in the cataract mode of operation were determined experimentally. Experiments were carried out with different mill filling percentages - 20% and 30%. The required speed of the ball mill with grinding media with innovative lifters at cataract mode of operation for the three types of materials is almost the same - with an average value of 45% of CS. The best energy efficiency and grinding efficiency material at 20% filling of the mill is obtained with a SteelFill filament, and at 30% - with a PLA filament.
在开发的工作中,用实验室球磨机进行了实验,该球磨机衬板采用对称位移的八个创新的球体四面体式提升器。根据之前的一项研究的实验,确定了具有创新形状的升降机的数量以及它们的大小。用于研磨介质的添加剂材料为PLA材料,用于研磨体的PLA,使用在3D打印机上打印的SteelFill(基于PLA)和CarbonFilTM(基于PETG)。实验确定了白内障操作模式下磨机的临界转速(CS)、分离角(肩角)和磨头角。在不同的磨机填充率—20%和30%下进行了试验。对于这三种类型的材料,具有创新升降机的球磨机在白内障操作模式下的研磨介质所需的球磨机速度几乎相同-平均值为CS的45%。在填充率为20%时,使用SteelFill长丝获得了最佳的能源效率和研磨效率,而在填充率为30%时,使用PLA长丝获得了最佳的能源效率和研磨效率。
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引用次数: 0
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WSEAS Transactions on Applied and Theoretical Mechanics
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