Acta Mechanica et Automatica最新文献_第5页

Aerodynamic Investigation on the Artefact “Bird of Saqqara” 人工制品“塞加拉鸟”的空气动力学研究

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-07-11 DOI: 10.2478/ama-2023-0046

Michel Zierow, Leon Lesemann

{"title":"Aerodynamic Investigation on the Artefact “Bird of Saqqara”","authors":"Michel Zierow, Leon Lesemann","doi":"10.2478/ama-2023-0046","DOIUrl":"https://doi.org/10.2478/ama-2023-0046","url":null,"abstract":"Abstract Lost, technical knowledge of ancient cultures is being rediscovered in modern times during archaeological excavations. A presumed example of the innovative power of ancient cultures is the artefact “Bird of Saqqara”. In the context of this paper, the aerodynamic characteristics of the artefact are to be determined by a computational fluid simulation, in order to be able to make a statement about the actual flight suitability and to examine the theses of the pre-astronautics critically. Based on a 3D scan, a CAD model of the artefact is created and then a numerical flow simulation is performed. By varying the angle of attack, the dimensionless coefficients can be represented in corresponding polars. The results show that the artefact has a low maximum glide ratio and thus the glide properties are not sufficient for use as a handglider. The centre of gravity of the artefact is located at the trailing edge of the wing and behind the neutral point. The resulting longitudinal stability does not meet modern specifications. Asymmetric lift distribution in the spanwise direction results in uncontrolled roll. Consequently, the artefact cannot fly a straight path. Within the scope of this work, the connection between the “Bird of Saqqara” and an alleged knowledge of aerodynamics in ancient Egypt could not be confirmed.","PeriodicalId":44942,"journal":{"name":"Acta Mechanica et Automatica","volume":"17 1","pages":"405 - 409"},"PeriodicalIF":0.7,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46573752","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

Solutions of the Nonlinear Evolution Problems and their Applications 非线性演化问题的解及其应用

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-07-11 DOI: 10.2478/ama-2023-0040

Muhammad Amir, J. A. Haider, Jamshaid Ul Rahman, Asifa Ashraf

{"title":"Solutions of the Nonlinear Evolution Problems and their Applications","authors":"Muhammad Amir, J. A. Haider, Jamshaid Ul Rahman, Asifa Ashraf","doi":"10.2478/ama-2023-0040","DOIUrl":"https://doi.org/10.2478/ama-2023-0040","url":null,"abstract":"Abstract In this article, a well-known technique, the variational iterative method with the Laplace transform, is used to solve nonlinear evolution problems of a simple pendulum and mass spring oscillator, which represents the duffing equation. In the variational iteration method (VIM), finding the Lagrange multiplier is an important step, and the variational theory is often used for this purpose. This paper shows how the Laplace transform can be used to find the multiplier in a simpler way. This method gives an easy approach for scientists and engineers who deal with a wide range of nonlinear problems. Duffing equation is solved by different analytic methods, but we tackle this for the first time to solve the duffing equation and the nonlinear oscillator by using the Laplace-based VIM. In the majority of cases, Laplace variational iteration method (LVIM) just needs one iteration to attain high accuracy of the answer for linearization anddiscretization, or intensive computational work is needed. The convergence criteria of this method are efficient as compared with the VIM. Comparing the analytical VIM by Laplace transform with MATLAB’s built-in command Simulink that confirms the method’s suitability for solving nonlinear evolution problems will be helpful. In future, we will be able to find the solution of highly nonlinear oscillators.","PeriodicalId":44942,"journal":{"name":"Acta Mechanica et Automatica","volume":"17 1","pages":"357 - 363"},"PeriodicalIF":0.7,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44312250","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

Mineralogical Analysis of Iron Ore Using Ultrasonic Wave Propagation Parameters 利用超声波传播参数分析铁矿矿物学

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-07-11 DOI: 10.2478/ama-2023-0041

N. Morkun, G. Fischerauer, V. Tron, Alona Gaponenko

引用次数: 0

Properties of Rubber-Like Materials and their Blends in Wide Range of Temperatures – Experimental and Numerical Study 类橡胶材料及其共混物在大温度范围内的性能——实验与数值研究

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-06-25 DOI: 10.2478/ama-2023-0037

M. Konarzewski, M. Stankiewicz, Marcin Sarzyński, M. Wieczorek, M. Czerwińska, P. Prasuła, R. Panowicz

引用次数: 0

Deterministic Seismic Damage Analysis for Concrete Gravity Dams: A Case Study of Oued Fodda Dam 混凝土重力坝的确定性地震损伤分析——以Oued Fodda大坝为例

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-06-25 DOI: 10.2478/ama-2023-0039

D. Ouzandja, A. Berrabah

{"title":"Deterministic Seismic Damage Analysis for Concrete Gravity Dams: A Case Study of Oued Fodda Dam","authors":"D. Ouzandja, A. Berrabah","doi":"10.2478/ama-2023-0039","DOIUrl":"https://doi.org/10.2478/ama-2023-0039","url":null,"abstract":"Abstract One of the major dangers for seismic damage of concrete dams is the propagation of cracks in dam concrete. The present study undertakes a numerical investigation of the seismic damage for Oued Fodda concrete gravity dam, located in the northwest of Algeria, considering the impacts of properties of joints along the dam-foundation rock interface and cross-stream earthquake excitation. Three-dimensional transient analyses for coupled dam-foundation rock system are carried out using Ansys software. The hydrodynamic effect of reservoir fluid is modelled using the added mass approach. The smeared crack approach is utilised to present the seismic damage of dam concrete using the Willam and Warnke failure criterion. The dam-foundation rock interface joints are presented with two ways, adhesive joints and frictional joints. The Drucker–Prager model is considered for dam concrete in nonlinear analyses. Consideration of the study results indicates that the frictional joints model can reduce the seismic response and damage hazard of the dam body to a better extent compared with the adhesive joints model. Furthermore, the application of cross-stream earthquake excitation reveals the significant effect on cracking response of the dam in the two models of joints.","PeriodicalId":44942,"journal":{"name":"Acta Mechanica et Automatica","volume":"17 1","pages":"347 - 356"},"PeriodicalIF":0.7,"publicationDate":"2023-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49627503","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

Investigations Into the Stability of Thin-Walled Composite Structures with Top-Hat Cross-Sections 顶帽截面薄壁复合材料结构稳定性研究

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-06-25 DOI: 10.2478/ama-2023-0036

Błażej Czajka

引用次数: 0

Use of 3D Optical Techniques in the Analysis of the Effect of Adding Rubber Recyclate to the Matrix on Selected Strength Parameters of Epoxy–Glass Composites 3D光学技术在分析基体中添加橡胶再生胶对环氧-玻璃复合材料强度参数选择的影响中的应用

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-06-25 DOI: 10.2478/ama-2023-0038

A. Charchalis, M. Kneć, D. Żuk, N. Abramczyk

{"title":"Use of 3D Optical Techniques in the Analysis of the Effect of Adding Rubber Recyclate to the Matrix on Selected Strength Parameters of Epoxy–Glass Composites","authors":"A. Charchalis, M. Kneć, D. Żuk, N. Abramczyk","doi":"10.2478/ama-2023-0038","DOIUrl":"https://doi.org/10.2478/ama-2023-0038","url":null,"abstract":"Abstract The article presents a method of modifying the strength properties of epoxy–glass composite by changing the percentage composition of the matrix by the addition of rubber recyclate. Taking into account environmental protection and economic conditions in the process of recycling and utilisation of waste, it is advisable to look for applications of non-degradable waste materials. Based on epoxy resin, a glass mat with a random direction of fibres and rubber recyclate, a test material with different percentage compositions was produced. Samples from the manufactured materials were subjected to a static tensile test on a ZwickRoell testing machine using the ARAMIS SRX measuring system. In addition, CT (computerized tomography) scans of the inside of the samples were made using a ZEISS METROTOM 6 Scout tomograph, and observations of the internal structures were made using a scanning electron microscope. The use of optical and microscopic techniques enabled the precise determination of strength parameters of the examined composites and the analysis of the behaviour of samples under load. The analysis of deformations over time in the examined samples showed a beneficial effect of the addition of rubber recyclate on the elastic properties of the examined composites.","PeriodicalId":44942,"journal":{"name":"Acta Mechanica et Automatica","volume":"17 1","pages":"333 - 346"},"PeriodicalIF":0.7,"publicationDate":"2023-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42496845","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: 1

Education in Flow Chemistry. 流动化学教育。

IF 1.2

Acta Mechanica et Automatica Pub Date : 2023-05-31 DOI: 10.2533/chimia.2023.294

Christophe Allemann, Roger Marti

引用次数: 0

Numerical Investigation of Production-Related Characteristics Regarding their Influence on the Fatigue Strength of Additively Manufactured Components 增材制造部件疲劳强度影响生产相关特性的数值研究

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-05-10 DOI: 10.2478/ama-2023-0033

M. Zeißig, F. Jablonski

引用次数: 0

Ability of Black-Box Optimisation to Efficiently Perform Simulation Studies in Power Engineering 黑盒优化有效进行电力工程仿真研究的能力

IF 0.7

Acta Mechanica et Automatica Pub Date : 2023-05-10 DOI: 10.2478/ama-2023-0034

Lukas Peters, Rüdiger Kutzner, M. Schäfer, L. Hofmann

{"title":"Ability of Black-Box Optimisation to Efficiently Perform Simulation Studies in Power Engineering","authors":"Lukas Peters, Rüdiger Kutzner, M. Schäfer, L. Hofmann","doi":"10.2478/ama-2023-0034","DOIUrl":"https://doi.org/10.2478/ama-2023-0034","url":null,"abstract":"Abstract In this study, the potential of the so-called black-box optimisation (BBO) to increase the efficiency of simulation studies in power engineering is evaluated. Three algorithms (“Multilevel Coordinate Search” (MCS) and “Stable Noisy Optimization by Branch and Fit” (SNOBFIT) by Huyer and Neumaier and “blackbox: A Procedure for Parallel Optimization of Expensive Black-box Functions” (blackbox) by Knysh and Korkolis) are implemented in MATLAB and compared for solving two use cases: the analysis of the maximum rotational speed of a gas turbine after a load rejection and the identification of transfer function parameters by measurements. The first use case has a high computational cost, whereas the second use case is computationally cheap. For each run of the algorithms, the accuracy of the found solution and the number of simulations or function evaluations needed to determine the optimum and the overall runtime are used to identify the potential of the algorithms in comparison to currently used methods. All methods provide solutions for potential optima that are at least 99.8% accurate compared to the reference methods. The number of evaluations of the objective functions differs significantly but cannot be directly compared as only the SNOBFIT algorithm does stop when the found solution does not improve further, whereas the other algorithms use a predefined number of function evaluations. Therefore, SNOBFIT has the shortest runtime for both examples. For computationally expensive simulations, it is shown that parallelisation of the function evaluations (SNOBFIT and blackbox) and quantisation of the input variables (SNOBFIT) are essential for the algorithmic performance. For the gas turbine overspeed analysis, only SNOBFIT can compete with the reference procedure concerning the runtime. Further studies will have to investigate whether the quantisation of input variables can be applied to other algorithms and whether the BBO algorithms can outperform the reference methods for problems with a higher dimensionality.","PeriodicalId":44942,"journal":{"name":"Acta Mechanica et Automatica","volume":"17 1","pages":"292 - 302"},"PeriodicalIF":0.7,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42076964","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