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A Liquid Nitrogen Cooling Circulation Unit: Its Design and a Performance Study 液氮冷却循环装置：设计与性能研究

Machines Pub Date : 2024-04-18 DOI: 10.3390/machines12040271

Jianjie Yao, Xiangyou Lu, Yuanlai Xie, Qianxu Wang, Xiao Liu

{"title":"A Liquid Nitrogen Cooling Circulation Unit: Its Design and a Performance Study","authors":"Jianjie Yao, Xiangyou Lu, Yuanlai Xie, Qianxu Wang, Xiao Liu","doi":"10.3390/machines12040271","DOIUrl":"https://doi.org/10.3390/machines12040271","url":null,"abstract":"A liquid nitrogen cooling circulating unit is a necessary condition for the stable operation of a cryogenic oscillator, which can provide a stable working environment for the oscillator. In this paper, according to the user’s functional requirements and performance parameters, a closed cooling system with supercooled liquid nitrogen as the medium was designed using SOLIDWORKS 2021 software, which can provide a suitable working environment for the cryogenic oscillator. Combined with the system heat load analysis, theoretical calculation for and the design of the coil heat exchanger, one of the core pieces of equipment of the unit, were carried out. The performance of the designed nitrogen exhaust heater was studied using FLUENT 2021 software, and the velocity field and temperature field of the nitrogen exhaust heater were analyzed. The results show that the outlet temperature of the nitrogen exhaust heating device can reach up to 310 K, and the outlet flow rate of the heating device is 0.01528 kg/s. The experiments on the liquid nitrogen circulating unit using the simulated load equipment show that the refrigeration power of the unit can reach a design index of 600 W, and the temperature of the liquid nitrogen at the liquid outlet of the unit can reach 77.8 K. The experiments also show that the unit meets the design requirements.","PeriodicalId":509264,"journal":{"name":"Machines","volume":" 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140687494","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

RBF-Based Fractional-Order SMC Fault-Tolerant Controller for a Nonlinear Active Suspension 基于 RBF 的分数阶 SMC 非线性主动悬架容错控制器

Machines Pub Date : 2024-04-18 DOI: 10.3390/machines12040270

Weipeng Zhao, Liang Gu

引用次数: 0

Robust Combined Adaptive Passivity-Based Control for Induction Motors 基于被动性的感应电机鲁棒组合自适应控制

Machines Pub Date : 2024-04-18 DOI: 10.3390/machines12040272

J. Travieso-Torres, A. Ricaldi-Morales, N. Aguila-Camacho

{"title":"Robust Combined Adaptive Passivity-Based Control for Induction Motors","authors":"J. Travieso-Torres, A. Ricaldi-Morales, N. Aguila-Camacho","doi":"10.3390/machines12040272","DOIUrl":"https://doi.org/10.3390/machines12040272","url":null,"abstract":"The need for industrial and commercial machinery to maintain high torque while accurately following a variable angular speed is increasing. To meet this demand, induction motors (IMs) are commonly used with variable speed drives (VSDs) that employ a field-oriented control (FOC) scheme. Over the last thirty years, IMs have been replacing independent connection direct current motors due to their cost-effectiveness, reduced maintenance needs, and increased efficiency. However, IMs and VSDs exhibit nonlinear behavior, uncertainties, and disturbances. This paper proposes a robust combined adaptive passivity-based control (CAPBC) for this class of nonlinear systems that applies to angular rotor speed and stator current regulation inside an FOC scheme for IMs’ VSDs. It uses general Lyapunov-based design energy functions and adaptive laws with σ-modification to assure robustness after combining control and monitoring variables. Lyapunov’s second method and the Barbalat Lemma prove that the control and identification error tends to be zero over time. Moreover, comparative experimental results with a standard proportional–integral controller (PIC) and direct APBC show the proposed CAPBC’s effectiveness and robustness under normal and changing conditions.","PeriodicalId":509264,"journal":{"name":"Machines","volume":" 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140689938","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

Three-Dimensional Modeling for Mechanical Analysis of Hydropower Generators with Floating Rotor Rim 用于浮动转子轮缘水力发电机机械分析的三维建模

Machines Pub Date : 2024-04-17 DOI: 10.3390/machines12040268

D. Rondon, Simon Pääjärvi, J. Aidanpää, R. Gustavsson, Peter Jeppsson

{"title":"Three-Dimensional Modeling for Mechanical Analysis of Hydropower Generators with Floating Rotor Rim","authors":"D. Rondon, Simon Pääjärvi, J. Aidanpää, R. Gustavsson, Peter Jeppsson","doi":"10.3390/machines12040268","DOIUrl":"https://doi.org/10.3390/machines12040268","url":null,"abstract":"Hydropower generators withstand multiple forces from diverse sources during operation. To ensure their stability and safe performance, numerical tools are developed to characterize their dynamic properties. Traditionally, generators are assumed to be rigid in rotordynamic analyses. However, the measurements in power stations challenge this assumption. This article proposes a novel approach to modeling hydropower generators with floating rotor rims using a three-dimensional (3-D) Finite Element Method, aiming to study their dynamic performance and properties, including natural frequencies, the modes of vibrations, and expansion due to centrifugal and electromagnetic forces, with the goal of improving the reliability of modern designs. Both this approach and employing a two-dimensional (2-D) model using curved beams result in similar in-plane natural frequencies and the expansion of the rotor rim due to centrifugal forces. However, the 3-D model can be used to calculate the out-of-plane natural frequencies and modes, to model the dynamics of complex geometries, and to perform stress evaluation and fatigue analysis.","PeriodicalId":509264,"journal":{"name":"Machines","volume":"29 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140694256","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

A Study on the Cavitation Effect of Elastic Material with Textured Surfaces under Fluid Lubrication Conditions 流体润滑条件下带有纹理表面的弹性材料的气蚀效应研究

Machines Pub Date : 2024-04-17 DOI: 10.3390/machines12040267

Haocheng Sun, Z. Yan, Shibo Wu, Ze Liu, Yuanyuan Jiang

引用次数: 0

Study on the Evolution of Sealing Performance during the Start-Up Process of Dynamic Pressure Seals Based on Three-Dimensional Fractal Functions 基于三维分形函数的动压密封件启动过程中密封性能演变研究

Machines Pub Date : 2024-04-17 DOI: 10.3390/machines12040269

Enzhe Bi, Shuangxi Li, Jiangteng Zhang, An Liu

引用次数: 0

A Study of Sliding Friction Using an Acoustic Emission and Wavelet-Based Energy Approach 利用声发射和基于小波的能量法研究滑动摩擦力

Machines Pub Date : 2024-04-16 DOI: 10.3390/machines12040265

Sergey Sychev, A. Batako

引用次数: 0

An Intelligent Diagnostic Method for Wear Depth of Sliding Bearings Based on MGCNN 基于 MGCNN 的滑动轴承磨损深度智能诊断方法

Machines Pub Date : 2024-04-16 DOI: 10.3390/machines12040266

Jingzhou Dai, Ling Tian, Haotian Chang

{"title":"An Intelligent Diagnostic Method for Wear Depth of Sliding Bearings Based on MGCNN","authors":"Jingzhou Dai, Ling Tian, Haotian Chang","doi":"10.3390/machines12040266","DOIUrl":"https://doi.org/10.3390/machines12040266","url":null,"abstract":"Sliding bearings are vital components in modern industry, exerting a crucial influence on equipment performance, with wear being one of their primary failure modes. In addressing the issue of wear diagnosis in sliding bearings, this paper proposes an intelligent diagnostic method based on a multiscale gated convolutional neural network (MGCNN). The proposed method allows for the quantitative inference of the maximum wear depth (MWD) of sliding bearings based on online vibration signals. The constructed model adopts a dual-path parallel structure in both the time and frequency domains to process bearing vibration signals, ensuring the integrity of information transmission through residual network connections. In particular, a multiscale gated convolution (MGC) module is constructed, which utilizes convolutional network layers to extract features from sample sequences. This module incorporates multiple scale channels, including long-term, medium-term, and short-term cycles, to fully extract information from vibration signals. Furthermore, gated units are employed to adaptively assign weights to feature vectors, enabling control of information flow direction. Experimental results demonstrate that the proposed method outperforms the traditional CNN model and shallow machine learning model, offering promising support for equipment condition monitoring and predictive maintenance.","PeriodicalId":509264,"journal":{"name":"Machines","volume":"3 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140695501","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

Research on the Aerodynamic Performance and Collaborative Optimization Design of the Full-Scale Compact Inlet Chamber of a Nuclear-Powered Steam Turbine 核动力蒸汽轮机全尺寸紧凑型进气道气动性能研究与协同优化设计

Machines Pub Date : 2024-04-15 DOI: 10.3390/machines12040262

Lei Zhang, Wei Jiang, Luotao Xie, Guobing Chen

{"title":"Research on the Aerodynamic Performance and Collaborative Optimization Design of the Full-Scale Compact Inlet Chamber of a Nuclear-Powered Steam Turbine","authors":"Lei Zhang, Wei Jiang, Luotao Xie, Guobing Chen","doi":"10.3390/machines12040262","DOIUrl":"https://doi.org/10.3390/machines12040262","url":null,"abstract":"In nuclear-powered steam turbines, the aerodynamic performance of the inlet chamber tends to be contradictory to the compact design, which makes it difficult to achieve optimal efficiency and power in a nuclear-powered steam turbine. In this study, the quantitative correlation between compact design and aerodynamic performance was investigated to reveal the interaction mechanism between the aerodynamic performance of the inlet chamber of the steam turbine with its compactness. First, the effects of peripheral quantity and arrangement of inlets in the chamber inlet on its aerodynamic performance were studied. The results indicated that the proposed cross configuration exhibited optimized aerodynamic performance in multiple aspects. Then, the effects of two compactness indices (inlet/outlet area ratio and axial spacing at outlet) on the aerodynamic performance of the inlet chamber were investigated. The results indicated that the volume of the inlet chamber was proportional to the inlet/outlet area ratio, and an appropriate design of the inlet chamber can achieve compactness without significantly affecting its aerodynamic performance. In addition, the influencing mechanism of the compact optimization design on the aerodynamic performances of the inlet chamber was revealed. This study provides references for optimization designing an effective and compacted inlet chamber of steam turbines.","PeriodicalId":509264,"journal":{"name":"Machines","volume":"19 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140700956","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

Effect of Variable-Nozzle-Turbocharger-Coupled Exhaust Gas Recirculation on Natural Gas Engine Emissions and Collaborative Optimization 可变喷嘴涡轮增压器耦合废气再循环对天然气发动机排放的影响及协同优化

Machines Pub Date : 2024-04-15 DOI: 10.3390/machines12040260

Kan Zhu, Diming Lou, Yunhua Zhang, Yedi Ren, Lanlan Fan

{"title":"Effect of Variable-Nozzle-Turbocharger-Coupled Exhaust Gas Recirculation on Natural Gas Engine Emissions and Collaborative Optimization","authors":"Kan Zhu, Diming Lou, Yunhua Zhang, Yedi Ren, Lanlan Fan","doi":"10.3390/machines12040260","DOIUrl":"https://doi.org/10.3390/machines12040260","url":null,"abstract":"Equivalent combustion natural gas engines typically utilize exhaust gas recirculation (EGR) systems to tackle their high thermal burden and NOx emissions. Variable nozzle turbochargers (VNT) can increase the engine intake and EGR rate simultaneously, resulting in NOx reduction while ensuring robust power performance. Using a VNT along with engine bench testing, the impact of VNT- and EGR-coordinated control on the performance and emissions of equivalent combustion natural gas engines was investigated under different operating conditions. Subsequently, multi-objective optimization was performed using a support vector machine. The results demonstrated that the use of VNTs in equivalent combustion natural gas engines could bolster the capacity to introduce EGR under several operative conditions and extend the scope of EGR regulation, thereby decreasing the engine’s thermal burden, improving fuel efficiency, and curbing emissions. Owing to the implementation of a multi-objective optimization method based on a support vector regression model and NSGA-II genetic algorithm, VNT and EGR control parameters could be optimized to slightly improve the economy and significantly reduce NOx emissions while maintaining the original engine power performance. At 20 operating points optimized for validation, brake-specific fuel consumption (BSFC) and NOx decreased by 0.94% and 47.0%, respectively, and CH4 increased by 3.7%, on average.","PeriodicalId":509264,"journal":{"name":"Machines","volume":"279 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140704148","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