Acta Polytechnica最新文献_第4页

Linearisation of a second-order nonlinear ordinary differential equation 二阶非线性常微分方程的线性化

IF 0.8

Acta Polytechnica Pub Date : 2023-03-02 DOI: 10.14311/ap.2023.63.0019

A. Maharaj, P. Leach, M. Govender, David P. Day

引用次数: 0

Induction motor mechanical defect diagnosis using DWT under different loading levels 不同载荷水平下感应电机机械缺陷的小波变换诊断

IF 0.8

Acta Polytechnica Pub Date : 2023-03-02 DOI: 10.14311/ap.2023.63.0001

A. Bouzida, R. Abdelli, Aimad Boudouda

引用次数: 0

Self-interference cancellation in underwater acoustic communications systems using orthogonal pilots in IBFD 基于IBFD正交导频的水声通信系统自干扰消除

IF 0.8

Acta Polytechnica Pub Date : 2023-03-02 DOI: 10.14311/ap.2023.63.0023

Hala A. Naman, A. E. Abdelkareem

{"title":"Self-interference cancellation in underwater acoustic communications systems using orthogonal pilots in IBFD","authors":"Hala A. Naman, A. E. Abdelkareem","doi":"10.14311/ap.2023.63.0023","DOIUrl":"https://doi.org/10.14311/ap.2023.63.0023","url":null,"abstract":"This paper proposes a Self-interference (SI) cancellation system model of Underwater acoustic (UWA) communication for in-band full-duplex (IBFD) technology. The SI channel is separated from the Far channel by exploiting a concurrently orthogonal pilot channel estimation technique using two orthogonal frequency-division multiplexing (OFDM) blocks to establish orthogonality between them based on a unitary matrix. Compared to the half-duplex channel estimator, the mean squared error (MSE) and the bit error rate (BER) provided strong evidence for the efficiency of the proposed SI cancellation. Since full-duplex systems are more efficient than half-duplex ones, the proposed approach might be seen as a viable option for them. The proposed method proved effective when used with a fixed full-duplex (FD) position and FD shifting of up to 4°. Different channel lengths and distances are adopted to evaluate the proposed method. Initial findings indicate that MSE for the SI channel minimum mean-square error (MMSE) estimator at 20 dB is 0.118 · 10−3, for fixed FD. In addition, this paper presents a geometry channel model for the Far channel in the IBFD underwater communication system that describes the propagation delay of the multipath reflection. The simulation results for the multipath propagation delay spread are similar to the traditional results, with the delay spread of the suggested model reaching (79 ms), which is close to the Bellhop simulator result (78 ms).","PeriodicalId":45804,"journal":{"name":"Acta Polytechnica","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41950434","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

Heat transfer characteristics of double pipe heat exchanger having externally enhanced inner pipe 内管外增强双管换热器的传热特性

IF 0.8

Acta Polytechnica Pub Date : 2023-03-02 DOI: 10.14311/ap.2023.63.0065

Balasubramanian Vijayaragavan, S. P. Asok, Chandrasekar Ramalekshmi Shakthi Ganesh

引用次数: 0

Femtosecond laser processing of advanced technical materials 飞秒激光加工先进技术材料

IF 0.8

Acta Polytechnica Pub Date : 2023-03-02 DOI: 10.14311/ap.2023.63.0036

T. Primus, M. Novák, P. Zeman, F. Holešovský

引用次数: 0

Comparative study of state space averaging and PWM with extra element theorem techniques for complex cascaded DC-DC Buck converter 复杂级联DC-DC降压变换器状态空间平均与带额外元素定理的PWM技术的比较研究

IF 0.8

Acta Polytechnica Pub Date : 2023-03-02 DOI: 10.14311/ap.2023.63.0050

Sangeeta H. Shete, P. Joshi

引用次数: 0

Theoretical analysis of the influence of the chevron inclination angle on the thermal performance of a gasket plate heat exchanger 人字形倾角对垫板式换热器热性能影响的理论分析

IF 0.8

Acta Polytechnica Pub Date : 2022-12-31 DOI: 10.14311/ap.2022.62.0627

E. Nogueira

{"title":"Theoretical analysis of the influence of the chevron inclination angle on the thermal performance of a gasket plate heat exchanger","authors":"E. Nogueira","doi":"10.14311/ap.2022.62.0627","DOIUrl":"https://doi.org/10.14311/ap.2022.62.0627","url":null,"abstract":"Different models are applied for an experimental and theoretical determination of the thermal and hydraulic performance of gasket plate heat exchanger. One of the relevant aspects of recent works is the influence of the chevron inclination angle between the heat exchanger plates. This work aims to analyse the impact of the chevron inclination angle by applying an effective concept in a sunflower vegetable oil cooler. Comparisons are made with theoretical and experimental results from the literature for works that consider angles of inclination equal to 30◦, 45◦, and 60◦. An analysis model that does not consider the inclination angle as an explicit parameter is included for comparison purposes. In addition to the angle of inclination, two other parameters, the mass flow rate of the cold fluid (water) and the number of plates, are considered crucial for determining and analysing the results. Nusselt number, global heat transfer coefficient, effectiveness, heat transfer rate, and outlet temperatures for hot and cold fluids are presented in a graphical format. The results point to the need to improve models applied to gasket plate heat exchangers concerning the influence of the inclination angle since there are significant differences between those obtained and analysed in this work.","PeriodicalId":45804,"journal":{"name":"Acta Polytechnica","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48667803","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

Stone Topography – Useful Tool in Monuments Restoration Process 石头地形——古迹修复过程中的有用工具

IF 0.8

Acta Polytechnica Pub Date : 2022-12-31 DOI: 10.14311/ap.2022.62.0589

Michal Cihla, K. Kovářová, Richard Malát, J. Valach

{"title":"Stone Topography – Useful Tool in Monuments Restoration Process","authors":"Michal Cihla, K. Kovářová, Richard Malát, J. Valach","doi":"10.14311/ap.2022.62.0589","DOIUrl":"https://doi.org/10.14311/ap.2022.62.0589","url":null,"abstract":"The surface of building stone on historic buildings often bears the original traces of craftsmanship processing. These are an integral part of the visual appearance of the monument and thus its value, which needs to be protected. For studying and identifying traces and subsequent reconstruction of stonemason's tools, we use the methods of traceology and mechanoscopy. Using modern imaging techniques, we can identify the stonemason's tool used, reconstruct the shape of its blade, and determine how it was used. The obtained results can be used in the process of monument care, especially in the process of preparation and implementation of restoration interventions on the objects, but they are also useful for completing the historical context of the monument. Our research is focused on the systematic study of the surface topography of the stone monuments in Prague. The obtained results were systematically divided according to individual historical period. As a model example of the use of the above-mentioned methods and approaches, we present the topography of stone elements and the development of stonemason's craft in Gothic Prague. The development of the stonemason's craft within one city in a given period can be documented on selected examples arranged chronologically in succession.","PeriodicalId":45804,"journal":{"name":"Acta Polytechnica","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46172735","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

Design and simulation of a bearing housing aerospace component from titanium alloy (Ti6Al4V) for additive manufacturing 用于增材制造的钛合金(Ti6Al4V)航空部件轴承座的设计与仿真

IF 0.8

Acta Polytechnica Pub Date : 2022-12-31 DOI: 10.14311/ap.2022.62.0639

Moses Oyesola, K. Mpofu, I. Daniyan, N. Mathe

{"title":"Design and simulation of a bearing housing aerospace component from titanium alloy (Ti6Al4V) for additive manufacturing","authors":"Moses Oyesola, K. Mpofu, I. Daniyan, N. Mathe","doi":"10.14311/ap.2022.62.0639","DOIUrl":"https://doi.org/10.14311/ap.2022.62.0639","url":null,"abstract":"In evaluating emerging technology, such as additive manufacturing, it is important to analyse the impact of the manufacturing process on efficiency in an objective and quantifiable manner. This study deals with the design and simulation of a bearing housing made from titanium alloy (Ti6Al4V) using the selective laser melting (SLM) technique. The Finite Element Analysis (FEA) method was used for assessing the suitability of Ti6Al4V for aerospace application. The choice of Ti6Al4V is due to the comparative advantage of its strength-to-weight ratio. The implicit and explicit modules of the Abaqus software were employed for the non-linear and linear analyses of the component part. The results obtained revealed that the titanium alloy (Ti6Al4V) sufficiently meets the design, functional and service requirements of the bearing housing component produced for aerospace application. The designed bearing is suitable for a high speed and temperature application beyond 1900 K, while the maximum stress induced in the component during loading was 521 kPa. It is evident that the developed stresses do not result in a distortion or deformation of the material with yield strength in the region of 820 MPa. This work provides design data for the development of a bearing housing for AM under the technique of SLM using Ti6Al4V by reflecting the knowledge of the material behaviour under the operating conditions.","PeriodicalId":45804,"journal":{"name":"Acta Polytechnica","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44396990","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

Parametric study of the energy potential of a building’s envelope with integrated energy-active elements 具有集成能量有源元件的建筑围护结构能量势能的参数研究

IF 0.8

Acta Polytechnica Pub Date : 2022-12-31 DOI: 10.14311/ap.2022.62.0595

D. Kalús, Daniela Koudelková, Veronika Mučková, Martin Sokol, Mária Kurčová, P. Šťastný

{"title":"Parametric study of the energy potential of a building’s envelope with integrated energy-active elements","authors":"D. Kalús, Daniela Koudelková, Veronika Mučková, Martin Sokol, Mária Kurčová, P. Šťastný","doi":"10.14311/ap.2022.62.0595","DOIUrl":"https://doi.org/10.14311/ap.2022.62.0595","url":null,"abstract":"Building structures with integrated energy-active elements (BSIEAE) present a progressive alternative for building construction with multifunctional energy functions. The aim was to determine the energy potential of a building envelope with integrated energy-active elements in the function of direct-heating, semi-accumulation and accumulation of large-area radiant heating. The research methodology consists in an analysis of building structures with energy-active elements, creation of mathematical-physical models based on the simplified definition of heat and mass transfer in radiant large-area heating, and a parametric study of the energy potential of individual variants of technical solutions. The results indicate that the increase in heat loss due to the location of the tubes in the structure closer to the exterior is negligible for Variant II, semi-accumulation heating, and Variant III, accumulation heating, as compared to Variant I, direct heating, it is below 1 % of the total delivered heat flux. The direct heat flux to the heated room is 89.17 %, 73.36 %, and 58.46 % of the total heat flux for Variant I, Variant II and Variant III, respectively. For Variant II and Variant III, the heat storage accounts for 14.84 %, and 29.86 % of the total heat flux, respectively. Variants II and III appear to be promising in terms of heat/cool accumulation with an assumption of lower energy demand (at least 10 %) than for low inertia walls. We plan to extend these simplified parametric studies with dynamic computer simulations to optimise the design and composition of the panels with integrated energy-active elements.","PeriodicalId":45804,"journal":{"name":"Acta Polytechnica","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47015626","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