Ze Guo, Weimeng Han, Zixu Guo, Hang Liu, Chuanjun Ma
High voltage circuit breakers are important equipment in power systems, and the valve motion of the chambers plays a role in the arc extinguishing performance of high-voltage circuit breakers. Therefore, in this paper, a 145 kV auto-expansion SF6 circuit breaker is taken as the research object, and a two-dimensional axisymmetric magnetohydrodynamic arc model considering valve motion process is established. The influence of different short circuit breaking conditions on the valve motion was studied. The results show that the backflow phenomenon of ablated steam is the main reason for the closure of the non-return valve, which plays an important role in opening the pressure relief valve. The closing time of the non-return valve is about 0.4 ms faster at a short circuit current of 40 kA than at a short circuit current of 36 kA.
高压断路器是电力系统中的重要设备，断路器室的阀门运动对高压断路器的灭弧性能有一定影响。因此，本文以 145 kV 自动膨胀 SF6 断路器为研究对象，建立了考虑阀运动过程的二维轴对称磁流体动力学电弧模型。研究了不同短路分断条件对阀运动的影响。结果表明，烧蚀蒸汽的倒流现象是止回阀关闭的主要原因，对开启泄压阀起着重要作用。短路电流为 40 kA 时，止回阀的关闭时间比短路电流为 36 kA 时快约 0.4 ms。
{"title":"Simulation of auto-expansion high voltage SF6 circuit breaker breaking process considering valve motion","authors":"Ze Guo, Weimeng Han, Zixu Guo, Hang Liu, Chuanjun Ma","doi":"10.1063/5.0222063","DOIUrl":"https://doi.org/10.1063/5.0222063","url":null,"abstract":"High voltage circuit breakers are important equipment in power systems, and the valve motion of the chambers plays a role in the arc extinguishing performance of high-voltage circuit breakers. Therefore, in this paper, a 145 kV auto-expansion SF6 circuit breaker is taken as the research object, and a two-dimensional axisymmetric magnetohydrodynamic arc model considering valve motion process is established. The influence of different short circuit breaking conditions on the valve motion was studied. The results show that the backflow phenomenon of ablated steam is the main reason for the closure of the non-return valve, which plays an important role in opening the pressure relief valve. The closing time of the non-return valve is about 0.4 ms faster at a short circuit current of 40 kA than at a short circuit current of 36 kA.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"9 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The advancement of rechargeable batteries for electronic devices requires continuous development of innovative materials for anodes, cathodes, and electrolytes. Li5GaO4 stands out as a promising electrode material for lithium-ion batteries, demonstrating swift Li-ion conductivity. Employing sophisticated computational simulation techniques based on classical potentials, we investigate the defect, diffusion, and dopant characteristics of Li5GaO4. Our simulations reveal that the Li Frenkel defect process possesses a minimum energy of 1.00 eV, while the Li–Ga anti-site isolated defect exhibits a higher energy. The Li–Ga anti-site cluster defect is favored over the Li–Ga anti-site isolated defect due to an exothermic binding of isolated defects forming a cluster (−2.28 eV). The projected long-range Li diffusion pathway aligns along the c-axis, featuring an activation energy of 0.42 eV. Notably, Na and Al emerge as the most promising isovalent dopants for the Li and Ge sites, respectively, with solution energies of −0.92 and 3.62 eV. Furthermore, the introduction of Si doping at the Ga site facilitates the formation of Li vacancies. This study offers crucial insights into the design of advanced materials, improving the capacity and performance of lithium-ion batteries, particularly addressing challenges associated with liquid electrolytes by utilizing solid electrolytes.
电子设备充电电池的发展需要不断开发创新的阳极、阴极和电解质材料。Li5GaO4 是一种很有前途的锂离子电池电极材料，具有快速的锂离子传导性。我们采用基于经典电位的复杂计算模拟技术，研究了 Li5GaO4 的缺陷、扩散和掺杂特性。模拟结果表明，锂 Frenkel 缺陷过程的最小能量为 1.00 eV，而锂镓反位孤立缺陷的能量更高。与镓锂反位孤立缺陷相比，镓锂反位簇缺陷更受青睐，这是因为孤立缺陷形成簇的放热结合（-2.28 eV）。预测的锂长程扩散路径沿 c 轴排列，活化能为 0.42 eV。值得注意的是，Na 和 Al 分别以-0.92 和 3.62 eV 的溶解能成为锂和 Ge 基底最有希望的异价掺杂剂。此外，在 Ga 位点引入硅掺杂剂有利于锂空位的形成。这项研究为设计先进材料、提高锂离子电池的容量和性能，特别是通过利用固体电解质解决与液态电解质相关的挑战提供了重要见解。
{"title":"Atomistic simulation study of Li5GaO4 for lithium-ion batteries","authors":"Sathiyamoorthy Mathushan, Poobalasingam Abiman, Poobalasuntharam Iyngaran, Navaratnarajah Kuganathan","doi":"10.1063/5.0213136","DOIUrl":"https://doi.org/10.1063/5.0213136","url":null,"abstract":"The advancement of rechargeable batteries for electronic devices requires continuous development of innovative materials for anodes, cathodes, and electrolytes. Li5GaO4 stands out as a promising electrode material for lithium-ion batteries, demonstrating swift Li-ion conductivity. Employing sophisticated computational simulation techniques based on classical potentials, we investigate the defect, diffusion, and dopant characteristics of Li5GaO4. Our simulations reveal that the Li Frenkel defect process possesses a minimum energy of 1.00 eV, while the Li–Ga anti-site isolated defect exhibits a higher energy. The Li–Ga anti-site cluster defect is favored over the Li–Ga anti-site isolated defect due to an exothermic binding of isolated defects forming a cluster (−2.28 eV). The projected long-range Li diffusion pathway aligns along the c-axis, featuring an activation energy of 0.42 eV. Notably, Na and Al emerge as the most promising isovalent dopants for the Li and Ge sites, respectively, with solution energies of −0.92 and 3.62 eV. Furthermore, the introduction of Si doping at the Ga site facilitates the formation of Li vacancies. This study offers crucial insights into the design of advanced materials, improving the capacity and performance of lithium-ion batteries, particularly addressing challenges associated with liquid electrolytes by utilizing solid electrolytes.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"22 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Giles Harrison, Ahmad A. Alkamali, Veronica Escobar-Ruiz, Keri A. Nicoll, Maarten H. P. Ambaum
Releasing charge into natural droplet systems such as fog and clouds offers a route to influence their properties. To facilitate charge release across a wide range of altitudes and meteorological circumstances—such as developing clouds—a charge emitter has been developed for integration with the conventional cloud-seeding flares carried by crewed cloud-seeding aircraft. This allows charge emitters to be used alongside, or instead of, conventional particle releasing flares. The charge emitter flare system is self-contained and self-powered, and includes internal monitoring and recording of its operating parameters. Using this “flare emitter” approach, successful charge emission has been demonstrated in level flight, at 3 km altitude, likely to have exceeded natural ion concentrations by several orders of magnitude. This quantitative verification of successful charge emission can underpin further physically based experiments on the effectiveness of charge release in cloud seeding.
{"title":"Providing charge emission for cloud seeding aircraft","authors":"R. Giles Harrison, Ahmad A. Alkamali, Veronica Escobar-Ruiz, Keri A. Nicoll, Maarten H. P. Ambaum","doi":"10.1063/5.0227533","DOIUrl":"https://doi.org/10.1063/5.0227533","url":null,"abstract":"Releasing charge into natural droplet systems such as fog and clouds offers a route to influence their properties. To facilitate charge release across a wide range of altitudes and meteorological circumstances—such as developing clouds—a charge emitter has been developed for integration with the conventional cloud-seeding flares carried by crewed cloud-seeding aircraft. This allows charge emitters to be used alongside, or instead of, conventional particle releasing flares. The charge emitter flare system is self-contained and self-powered, and includes internal monitoring and recording of its operating parameters. Using this “flare emitter” approach, successful charge emission has been demonstrated in level flight, at 3 km altitude, likely to have exceeded natural ion concentrations by several orders of magnitude. This quantitative verification of successful charge emission can underpin further physically based experiments on the effectiveness of charge release in cloud seeding.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"5 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The significant disparities in physical and chemical properties between aluminum alloy and high-strength steel pose substantial challenges for conventional friction joining techniques. To address this issue, this study proposes a novel approach utilizing inertial friction welding with an interlayer to join these dissimilar materials. A CrCoNi medium entropy alloy sheet was selected as the interlayer due to its intermediate melting point, thermal conductivity, strength, and surface hardness between 6061-T6 aluminum alloy and 42CrMo steel, as well as its high element mixing entropy. These properties were deemed crucial for balancing interface heat generation and regulation the formation of intermetallic compounds. The experimental procedure involved embedding the CrCoNi sheet into the end face of the 6061-T6 aluminum alloy, followed by the application of IFW to join the aluminum alloy with 42CrMo high-strength steel. This investigation focuses on examining the effects of three distinct friction speeds (3800, 4000, and 4200 rpm) on the microstructural characteristics and mechanical properties of the regulating joints with the CrCoNi interlayer. Results demonstrate that the CrCoNi enhances the temperature at the steel-side interface through friction with 42CrMo steel and 6061-T6 aluminum, combined with adjustments in the friction sequence and duration, promoting plastic deformation. The axial transfer of heat creates a temperature gradient at the joint, enabling low-temperature welding on the aluminum side and forming a mechanical interlocking structure at the interface. The diffusion of Cr, Co, and Ni elements regulates the type and thickness of interfacial intermetallic compounds, ultimately enhancing the joint's strength. The thickness of the intermetallic compounds AlNi3, FeAl3, AlCo, and Fe2Al5 formed at the interface is less than 2 µm. A phase transformation occurred at the 42CrMo high-strength steel interface, leading to the formation of numerous needle-like martensites, which increased the Vickers hardness in the welding seam to 763.9 HV. The joint's tensile strength initially increased and then decreased with increasing friction speed, reaching a maximum of 168.7 MPa at 4000 rpm, which is more than 60% of the aluminum alloy base material's tensile strength.
{"title":"Enhanced inertia friction welding of aluminum alloy and high-strength steel using CrCoNi interlayer: Microstructural and mechanical characterization","authors":"Qiming Jiang, Wei Wu, Hongrui Yang, Kunhang Li, Guangchuan Zhang, Hong Huang","doi":"10.1063/5.0221957","DOIUrl":"https://doi.org/10.1063/5.0221957","url":null,"abstract":"The significant disparities in physical and chemical properties between aluminum alloy and high-strength steel pose substantial challenges for conventional friction joining techniques. To address this issue, this study proposes a novel approach utilizing inertial friction welding with an interlayer to join these dissimilar materials. A CrCoNi medium entropy alloy sheet was selected as the interlayer due to its intermediate melting point, thermal conductivity, strength, and surface hardness between 6061-T6 aluminum alloy and 42CrMo steel, as well as its high element mixing entropy. These properties were deemed crucial for balancing interface heat generation and regulation the formation of intermetallic compounds. The experimental procedure involved embedding the CrCoNi sheet into the end face of the 6061-T6 aluminum alloy, followed by the application of IFW to join the aluminum alloy with 42CrMo high-strength steel. This investigation focuses on examining the effects of three distinct friction speeds (3800, 4000, and 4200 rpm) on the microstructural characteristics and mechanical properties of the regulating joints with the CrCoNi interlayer. Results demonstrate that the CrCoNi enhances the temperature at the steel-side interface through friction with 42CrMo steel and 6061-T6 aluminum, combined with adjustments in the friction sequence and duration, promoting plastic deformation. The axial transfer of heat creates a temperature gradient at the joint, enabling low-temperature welding on the aluminum side and forming a mechanical interlocking structure at the interface. The diffusion of Cr, Co, and Ni elements regulates the type and thickness of interfacial intermetallic compounds, ultimately enhancing the joint's strength. The thickness of the intermetallic compounds AlNi3, FeAl3, AlCo, and Fe2Al5 formed at the interface is less than 2 µm. A phase transformation occurred at the 42CrMo high-strength steel interface, leading to the formation of numerous needle-like martensites, which increased the Vickers hardness in the welding seam to 763.9 HV. The joint's tensile strength initially increased and then decreased with increasing friction speed, reaching a maximum of 168.7 MPa at 4000 rpm, which is more than 60% of the aluminum alloy base material's tensile strength.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"56 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. M. Gopal, V. Kavimani, S. Sudhagar, Debabrata Barik, Prabhu Paramasivam, Harinadh Vemanaboina
The aim of this experimental work is to find the ideal wire electric discharge machining (WEDM) parameter combination for processing a novel FeCoCrNiMn High Entropy Alloy (HEA)-reinforced magnesium composite. This composite is developed with varying weights of FeCoCrNiMn at 5%, 10%, and 15% through powder metallurgy. Experiments are performed to examine the effects of HEA and wire-EDM variables on surface roughness (Ra) and kerf width (KW) using Taguchi’s L27 orthogonal array. The hybrid ENTROPY-COCOSO (Combined Compromise Solution) methodology is used for multiple objective optimizations after the Taguchi method for optimization. The most significant constraints on Ra and KW are found to be pulse ON time and current. Wider kerfs and rougher surfaces are the result of longer pulse ON times and higher current. The ideal input parameters recommended by ENTROPY-COCOSO for minimal Ra and KW are 2 A of current, 20 µs of pulse ON time, 25 µs of pulse OFF time, and 4 mm/min of wire feed rate. To predict outcomes, both linear regression models and artificial neural networks (ANNs) are used, and the results are compared with experimental data. The results are validated by the fact that ANN predictions closely match experimental data with minimal deviation.
这项实验工作的目的是找到理想的线切割加工（WEDM）参数组合，以加工新型铁钴铬镍锰高熵合金（HEA）增强镁复合材料。这种复合材料是通过粉末冶金法研制的，其中铁钴铬镍锰的重量分别为 5%、10% 和 15%。实验采用田口 L27 正交阵列来检验 HEA 和线切割变量对表面粗糙度 (Ra) 和切口宽度 (KW) 的影响。在采用田口方法进行优化后，使用混合 ENTROPY-COCOSO（组合折衷方案）方法进行多目标优化。发现对 Ra 和 KW 最重要的限制因素是脉冲接通时间和电流。更长的脉冲开启时间和更大的电流会导致更宽的切口和更粗糙的表面。ENTROPY-COCOSO 推荐的最小 Ra 和 KW 的理想输入参数为：2 A 电流、20 µs 脉冲接通时间、25 µs 脉冲关断时间和 4 mm/min 的送丝速度。为了预测结果，使用了线性回归模型和人工神经网络（ANN），并将结果与实验数据进行了比较。人工神经网络的预测结果与实验数据非常吻合，偏差极小，从而验证了预测结果。
{"title":"Enhancing WEDM performance on Mg/FeCoCrNiMn HEA composites through ANN and entropy integrated COCOSO optimization","authors":"P. M. Gopal, V. Kavimani, S. Sudhagar, Debabrata Barik, Prabhu Paramasivam, Harinadh Vemanaboina","doi":"10.1063/5.0226558","DOIUrl":"https://doi.org/10.1063/5.0226558","url":null,"abstract":"The aim of this experimental work is to find the ideal wire electric discharge machining (WEDM) parameter combination for processing a novel FeCoCrNiMn High Entropy Alloy (HEA)-reinforced magnesium composite. This composite is developed with varying weights of FeCoCrNiMn at 5%, 10%, and 15% through powder metallurgy. Experiments are performed to examine the effects of HEA and wire-EDM variables on surface roughness (Ra) and kerf width (KW) using Taguchi’s L27 orthogonal array. The hybrid ENTROPY-COCOSO (Combined Compromise Solution) methodology is used for multiple objective optimizations after the Taguchi method for optimization. The most significant constraints on Ra and KW are found to be pulse ON time and current. Wider kerfs and rougher surfaces are the result of longer pulse ON times and higher current. The ideal input parameters recommended by ENTROPY-COCOSO for minimal Ra and KW are 2 A of current, 20 µs of pulse ON time, 25 µs of pulse OFF time, and 4 mm/min of wire feed rate. To predict outcomes, both linear regression models and artificial neural networks (ANNs) are used, and the results are compared with experimental data. The results are validated by the fact that ANN predictions closely match experimental data with minimal deviation.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"184 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zinc-ion batteries (ZIBs) have become a highly desirable energy storage technology due to their significant advantages, such as low cost and high safety; however, the limitation of cathode materials has become a major factor restricting the development of ZIBs. Here, molybdenum diselenide (MoSe2) nanoflakes were investigated for the first time as a novel cathode for ZIBs. The unique two-dimensional (2D) layered structure of MoSe2 provides convenient channels and multiple active sites for zinc (Zn) ion diffusion. MoSe2 showed a specific capacity of 30.1 mA h/g at 0.1 A/g as well as almost no capacity decay at 1.0 A/g after 1500 cycles. Further, the Zn–MoSe2 coin cell successfully excited a light-emitting diode, showing good application prospects. Moreover, there was almost no aging of the battery after cycling, thus indicating satisfactory application potential. This work broadens the application of 2D materials in ZIBs.
{"title":"MoSe2 nanoflakes for zinc ion storage","authors":"Renzhi Jiang, Yuncheng Cai","doi":"10.1063/5.0226948","DOIUrl":"https://doi.org/10.1063/5.0226948","url":null,"abstract":"Zinc-ion batteries (ZIBs) have become a highly desirable energy storage technology due to their significant advantages, such as low cost and high safety; however, the limitation of cathode materials has become a major factor restricting the development of ZIBs. Here, molybdenum diselenide (MoSe2) nanoflakes were investigated for the first time as a novel cathode for ZIBs. The unique two-dimensional (2D) layered structure of MoSe2 provides convenient channels and multiple active sites for zinc (Zn) ion diffusion. MoSe2 showed a specific capacity of 30.1 mA h/g at 0.1 A/g as well as almost no capacity decay at 1.0 A/g after 1500 cycles. Further, the Zn–MoSe2 coin cell successfully excited a light-emitting diode, showing good application prospects. Moreover, there was almost no aging of the battery after cycling, thus indicating satisfactory application potential. This work broadens the application of 2D materials in ZIBs.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"35 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a detailed experimental study of discharge current oscillations in a planar cathode plasma with poly-dispersed alumina dust particles. The dominant frequency of oscillation depends on the discharge voltage, operating pressure, and amount of dust particles placed on the cathode. The power-law variation in the dominant frequency with different external operating parameters is presented. Experimental observations suggest that the dominant mechanism behind the generation of these oscillations is the cathode spot injection of sub-micron-sized dust particles. The cathode spots also aid in the generation of fine dust particles. The threshold limit on dust particle density dispersed on the cathode suggests that below the threshold limit, the fine particles depleting the electrons play an important role and lead to the generation of self-excited oscillations. Operating above the threshold limit, a stable dust cloud was observed together with the suppression of self-excited oscillations.
{"title":"Experimental study of discharge current oscillations with dust particles","authors":"Nidhi Patel, G. Prasad","doi":"10.1063/5.0222899","DOIUrl":"https://doi.org/10.1063/5.0222899","url":null,"abstract":"We present a detailed experimental study of discharge current oscillations in a planar cathode plasma with poly-dispersed alumina dust particles. The dominant frequency of oscillation depends on the discharge voltage, operating pressure, and amount of dust particles placed on the cathode. The power-law variation in the dominant frequency with different external operating parameters is presented. Experimental observations suggest that the dominant mechanism behind the generation of these oscillations is the cathode spot injection of sub-micron-sized dust particles. The cathode spots also aid in the generation of fine dust particles. The threshold limit on dust particle density dispersed on the cathode suggests that below the threshold limit, the fine particles depleting the electrons play an important role and lead to the generation of self-excited oscillations. Operating above the threshold limit, a stable dust cloud was observed together with the suppression of self-excited oscillations.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aerodynamic noise resulting from the flow around cylinders is a significant engineering challenge in aviation and wind engineering. The phenomenon of alternating vortex shedding in the flow leads to vibration and noise generation. However, accurately describing both the flow field and the sound field is challenging due to the significant difference in magnitude between them. To tackle this issue, this work introduces the application of the spectral element method (SEM) and flow-acoustic monolithic simulation for solving the two-dimensional compressible Navier–Stokes equations at low Reynolds numbers. This study is to investigate the reduction of flow-induced noise through the implementation of slotting technology on a circular cylinder. This study focuses on examining two different slit width ratios, s/d = 0.15 and 0.25, with a slit angle of attack of 0°. A comparative analysis is conducted between a complete circular cylinder and a slotted circular cylinder. The findings indicate that the slotted cylinder exhibits reduced intensity of vortex shedding and an extended region of downstream vortex generation compared to the complete cylinder. Notably, when s/d = 0.25, the slotted cylinder demonstrates minimal noise generation. Even at s/d = 0.15, a significant reduction in flow-induced noise is observed. These results highlight the potential of utilizing slotting technology on cylinders to effectively mitigate aerodynamic noise. The application of SEM and flow-acoustic monolithic simulation shows their relevance in analyzing and designing noise mitigation techniques in aerodynamics. This work can develop innovative solutions to reduce noise and improve the performance of various applications in aviation and wind engineering.
{"title":"Fluid-acoustic monolithic simulation based on spectral element method to solve flows past a slotted circular cylinder at low Reynolds numbers","authors":"Ya Zhuo, Guoliang Qin, Ximeng Ye","doi":"10.1063/5.0215719","DOIUrl":"https://doi.org/10.1063/5.0215719","url":null,"abstract":"Aerodynamic noise resulting from the flow around cylinders is a significant engineering challenge in aviation and wind engineering. The phenomenon of alternating vortex shedding in the flow leads to vibration and noise generation. However, accurately describing both the flow field and the sound field is challenging due to the significant difference in magnitude between them. To tackle this issue, this work introduces the application of the spectral element method (SEM) and flow-acoustic monolithic simulation for solving the two-dimensional compressible Navier–Stokes equations at low Reynolds numbers. This study is to investigate the reduction of flow-induced noise through the implementation of slotting technology on a circular cylinder. This study focuses on examining two different slit width ratios, s/d = 0.15 and 0.25, with a slit angle of attack of 0°. A comparative analysis is conducted between a complete circular cylinder and a slotted circular cylinder. The findings indicate that the slotted cylinder exhibits reduced intensity of vortex shedding and an extended region of downstream vortex generation compared to the complete cylinder. Notably, when s/d = 0.25, the slotted cylinder demonstrates minimal noise generation. Even at s/d = 0.15, a significant reduction in flow-induced noise is observed. These results highlight the potential of utilizing slotting technology on cylinders to effectively mitigate aerodynamic noise. The application of SEM and flow-acoustic monolithic simulation shows their relevance in analyzing and designing noise mitigation techniques in aerodynamics. This work can develop innovative solutions to reduce noise and improve the performance of various applications in aviation and wind engineering.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"30 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiajin Rao, Boya Peng, Lei Zhang, Dajian Li, Wei Zhang, Peng Liu, Fangyuan Han, Liangyuan Chen, Yi Su, Le Wang, Shaoming Pan, Rui Li, Wei Huang, Min Yu
Amino-cured epoxy resins are widely used in the electrical and electronic industry for their excellent properties. To investigate the mechanism of the effect of O2 and H2O on the pyrolysis behavior of epoxy resin, in this paper, the cross-linked structure of bisphenol A type epoxy resin cured by adducts of diethylenetriamine and butyl glycidyl ether is modeled based on the ReaxFF force field, and the thermal decomposition processes at different temperatures and gas atmospheres were simulated and the pathways of the small molecule products were clarified. The results show that epoxy resin will produce small molecule gas products, such as H2, CO, H2O, OH, CH2O, and free radicals, in the process of pyrolysis; the presence of amino groups also generates nitrogen-containing radicals, such as CN, CH2N, and C2H4N; as the reaction temperature increases, the rate of pyrolysis reaction will be accelerated. The same temperature in oxygen and water atmospheres can accelerate the breakage of epoxy resin main chain by promoting the breakage of carbon and oxygen bonds and, at the same time, promote the generation of small molecule gases, such as H2 and CO.
氨基固化环氧树脂以其优异的性能被广泛应用于电子电气行业。为了研究 O2 和 H2O 对环氧树脂热分解行为的影响机理，本文基于 ReaxFF 力场，模拟了二乙烯三胺和丁基缩水甘油醚加合物固化双酚 A 型环氧树脂的交联结构，并模拟了不同温度和气体环境下的热分解过程，明确了小分子产物的生成途径。结果表明，环氧树脂在热解过程中会产生 H2、CO、H2O、OH、CH2O 和自由基等小分子气体产物；氨基的存在还会产生 CN、CH2N 和 C2H4N 等含氮自由基；随着反应温度的升高，热解反应的速率会加快。在氧气和水气氛中，相同的温度会促进碳键和氧键的断裂，从而加速环氧树脂主链的 断裂，同时促进 H2 和 CO 等小分子气体的生成。
{"title":"Study on the cracking process of epoxy resin under oxygen and water atmosphere based on ReaxFF force field","authors":"Xiajin Rao, Boya Peng, Lei Zhang, Dajian Li, Wei Zhang, Peng Liu, Fangyuan Han, Liangyuan Chen, Yi Su, Le Wang, Shaoming Pan, Rui Li, Wei Huang, Min Yu","doi":"10.1063/5.0226686","DOIUrl":"https://doi.org/10.1063/5.0226686","url":null,"abstract":"Amino-cured epoxy resins are widely used in the electrical and electronic industry for their excellent properties. To investigate the mechanism of the effect of O2 and H2O on the pyrolysis behavior of epoxy resin, in this paper, the cross-linked structure of bisphenol A type epoxy resin cured by adducts of diethylenetriamine and butyl glycidyl ether is modeled based on the ReaxFF force field, and the thermal decomposition processes at different temperatures and gas atmospheres were simulated and the pathways of the small molecule products were clarified. The results show that epoxy resin will produce small molecule gas products, such as H2, CO, H2O, OH, CH2O, and free radicals, in the process of pyrolysis; the presence of amino groups also generates nitrogen-containing radicals, such as CN, CH2N, and C2H4N; as the reaction temperature increases, the rate of pyrolysis reaction will be accelerated. The same temperature in oxygen and water atmospheres can accelerate the breakage of epoxy resin main chain by promoting the breakage of carbon and oxygen bonds and, at the same time, promote the generation of small molecule gases, such as H2 and CO.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"11 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article mainly introduces the impedance based single-phase grounding fault location method for distribution networks, including its theoretical basis, algorithm steps, and simulation verification. First, starting from the impedance analysis of the transmission line model, the method of accurately measuring the location of the fault point through phase domain analysis is explained. Next, the process of impedance analysis for single-phase grounding faults was described in detail, that is, how to solve the impedance of the grounding fault points by calculating the voltage and current signals. Then, the specific process of the impedance based grounding fault location algorithm was introduced, including the calculation of equivalent load impedance, the calculation of starting voltage and current, the calculation of grounding current, and the solution of fault point location. Finally, simulation verification was conducted using an IEEE 34 node distribution system example in a MATLAB/Simulink environment, and the results showed that the algorithm has high positioning accuracy, with a maximum error of within 3%.
{"title":"Research on single-phase grounding fault location technology in distribution networks based on impedance method","authors":"Sha Wang, Shengkai Wei","doi":"10.1063/5.0225951","DOIUrl":"https://doi.org/10.1063/5.0225951","url":null,"abstract":"This article mainly introduces the impedance based single-phase grounding fault location method for distribution networks, including its theoretical basis, algorithm steps, and simulation verification. First, starting from the impedance analysis of the transmission line model, the method of accurately measuring the location of the fault point through phase domain analysis is explained. Next, the process of impedance analysis for single-phase grounding faults was described in detail, that is, how to solve the impedance of the grounding fault points by calculating the voltage and current signals. Then, the specific process of the impedance based grounding fault location algorithm was introduced, including the calculation of equivalent load impedance, the calculation of starting voltage and current, the calculation of grounding current, and the solution of fault point location. Finally, simulation verification was conducted using an IEEE 34 node distribution system example in a MATLAB/Simulink environment, and the results showed that the algorithm has high positioning accuracy, with a maximum error of within 3%.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"31 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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