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}
Avalanche photodiodes (APDs) produce noise during operation, which affects the device performance. However, the previous research on its noise is mainly theoretical analysis and is only reflected as optical noise. Therefore, according to the characteristics of APD material and the mechanism of noise generation, the main noise of the device is analyzed in this paper. First, the test method of noise in APDs is established, including testing of dark noise, optical noise, and multiplication noise in high frequency bands. The main noises in APDs are 1/f noise, thermal noise, shot noise, generation recombination noise, and multiplication shot noise, and shot noise is suppressed by Fermi–Dirac distribution and Coulomb action. Second, the reliability of APDs is evaluated by measuring and analyzing the noise parameters of the device through thermal aging experiments. It is concluded that the defects introduced by thermal aging can be reflected by the change in noise, which is consistent with the results in the literature. This method can comprehensively obtain the noise in APDs, which is helpful to improve the working efficiency, life, and reliability of the device.
{"title":"Analysis of noise and its characteristics in avalanche photodiode","authors":"XiaoFei Jia, Qun Wei, Yan Zhu, WenPeng Zhang","doi":"10.1063/5.0229293","DOIUrl":"https://doi.org/10.1063/5.0229293","url":null,"abstract":"Avalanche photodiodes (APDs) produce noise during operation, which affects the device performance. However, the previous research on its noise is mainly theoretical analysis and is only reflected as optical noise. Therefore, according to the characteristics of APD material and the mechanism of noise generation, the main noise of the device is analyzed in this paper. First, the test method of noise in APDs is established, including testing of dark noise, optical noise, and multiplication noise in high frequency bands. The main noises in APDs are 1/f noise, thermal noise, shot noise, generation recombination noise, and multiplication shot noise, and shot noise is suppressed by Fermi–Dirac distribution and Coulomb action. Second, the reliability of APDs is evaluated by measuring and analyzing the noise parameters of the device through thermal aging experiments. It is concluded that the defects introduced by thermal aging can be reflected by the change in noise, which is consistent with the results in the literature. This method can comprehensively obtain the noise in APDs, which is helpful to improve the working efficiency, life, and reliability of the device.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"60 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224433","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}
Deep learning techniques provide a new approach to the design and optimization of electromagnetic metamaterials. This study used a convolutional neural network and long short-term memory (CNN–LSTM) hybrid network to design and optimize a broadband metamaterial reflective linear polarization converter. The data augmentation method was also employed in few-shot learning to reduce optimization costs and improve model prediction performance. With the inverse prediction, a linear polarization converter that perfectly covers the Ku-band was obtained and fabricated with flexible printed circuit technology. Both simulation and experimental results indicate that this network can accurately predict the structural parameters. The polarization converter not only achieves remarkable broadband polarization conversion efficiency spanning the 2.2–18 GHz range but also maintains precise cross-polarization control across the entire Ku-band. The mean polarization conversion ratio in the Ku-band was calculated to be an impressive 99.69%. Finally, the mechanism of polarization conversion and the influence of each structural parameter on its performance further verify the optimality of the inverse design model. The use of CNN–LSTM deep learning methods significantly simplified the design process of electromagnetic metamaterials, reducing design costs while ensuring high design precision and excellent performance.
深度学习技术为电磁超材料的设计和优化提供了一种新方法。本研究使用卷积神经网络和长短期记忆（CNN-LSTM）混合网络来设计和优化宽带超材料反射线性极化转换器。在少次学习中还采用了数据增强方法，以降低优化成本并提高模型预测性能。通过反向预测，获得了完美覆盖 Ku 波段的线性偏振转换器，并利用柔性印刷电路技术制造了该转换器。仿真和实验结果都表明，该网络能准确预测结构参数。该偏振转换器不仅在 2.2-18 GHz 范围内实现了出色的宽带偏振转换效率，而且在整个 Ku 波段内保持了精确的交叉偏振控制。根据计算，Ku 波段的平均极化转换率达到了惊人的 99.69%。最后，极化转换机制以及各结构参数对其性能的影响进一步验证了反向设计模型的最优性。CNN-LSTM 深度学习方法的使用大大简化了电磁超材料的设计过程，降低了设计成本，同时确保了高设计精度和优异性能。
{"title":"Broadband metamaterial linear polarization converter designed by a hybrid neural network with data augmentation","authors":"Junyu Hua, Xiaodong He","doi":"10.1063/5.0224049","DOIUrl":"https://doi.org/10.1063/5.0224049","url":null,"abstract":"Deep learning techniques provide a new approach to the design and optimization of electromagnetic metamaterials. This study used a convolutional neural network and long short-term memory (CNN–LSTM) hybrid network to design and optimize a broadband metamaterial reflective linear polarization converter. The data augmentation method was also employed in few-shot learning to reduce optimization costs and improve model prediction performance. With the inverse prediction, a linear polarization converter that perfectly covers the Ku-band was obtained and fabricated with flexible printed circuit technology. Both simulation and experimental results indicate that this network can accurately predict the structural parameters. The polarization converter not only achieves remarkable broadband polarization conversion efficiency spanning the 2.2–18 GHz range but also maintains precise cross-polarization control across the entire Ku-band. The mean polarization conversion ratio in the Ku-band was calculated to be an impressive 99.69%. Finally, the mechanism of polarization conversion and the influence of each structural parameter on its performance further verify the optimality of the inverse design model. The use of CNN–LSTM deep learning methods significantly simplified the design process of electromagnetic metamaterials, reducing design costs while ensuring high design precision and excellent performance.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"9 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224432","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 essence of fluid phase transition is the jump of physical properties distinctly induced by shock waves in the hard-sphere model. Due to the strong impact of the wave, the internal freedoms of molecules are stimulated, releasing tremendous energy that commonly triggers the phase transition. Conversely, typical thermal and dynamic jumps can be described by the Rankine–Hugoniot conditions based on the Euler equation. In the theoretical simulation, the initial density and rotational freedoms of molecules are directly regarded as the primary factors to affect processes of phase transition. However, the influence of vibrational freedom in molecules has not been discussed yet. As the increasing temperature can gradually excite the affection of vibrational freedom, it is unwise to assume that the temperature element is constant in the theory. What would be a suitable model that accurately reflects the relationship between temperature and affection from vibrational freedom? The non-limited model has been courageously attempted with the temperature range from T0 to 6T0 (T0 is unperturbed temperature). We have found that the vibrational freedom can have a great effect on properties during phase transition processes.
{"title":"Non-limited vibrational effect on shock-induced phase transitions of condensed fluid in hard-sphere model","authors":"Yue Zheng, Junjun Xu, Ke Tang","doi":"10.1063/5.0231113","DOIUrl":"https://doi.org/10.1063/5.0231113","url":null,"abstract":"The essence of fluid phase transition is the jump of physical properties distinctly induced by shock waves in the hard-sphere model. Due to the strong impact of the wave, the internal freedoms of molecules are stimulated, releasing tremendous energy that commonly triggers the phase transition. Conversely, typical thermal and dynamic jumps can be described by the Rankine–Hugoniot conditions based on the Euler equation. In the theoretical simulation, the initial density and rotational freedoms of molecules are directly regarded as the primary factors to affect processes of phase transition. However, the influence of vibrational freedom in molecules has not been discussed yet. As the increasing temperature can gradually excite the affection of vibrational freedom, it is unwise to assume that the temperature element is constant in the theory. What would be a suitable model that accurately reflects the relationship between temperature and affection from vibrational freedom? The non-limited model has been courageously attempted with the temperature range from T0 to 6T0 (T0 is unperturbed temperature). We have found that the vibrational freedom can have a great effect on properties during phase transition processes.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"8 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185398","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}
Internal wave is essentially a gravity wave induced by the layered structure of water (e.g., density stable layering), with its maximum amplitude occurring within the ocean. Similar to surface waves, internal waves have significant influence on the strength and stability of a submerged body as an external factor. Meanwhile, combined shells are exposed to complicated loads under internal waves, and edge stress is dominant. In this study, the edge stresses of combined shell (typical hemisphere–cylinder combined shell and unfolded sphere–cylinder combined shell) under internal waves were analyzed. Indeed, a semi-empirical, semi-theoretical formula for the edge stress of combined shells (typical hemisphere–cylinder combined shell and unfolded sphere–cylinder combined shell) has been proposed. In this study, the semi-empirical, semi-theoretical formula was corrected by introducing internal wave loads, with the depth of the internal wave taken into consideration. In addition, the corrected formula was verified by finite element analysis, and a simplified equation for the calculation of edge stress of the combined shell under internal waves was developed, with errors in a rational range.
{"title":"Analysis of edge stress of combined shell under internal waves","authors":"Yiqiong Cui","doi":"10.1063/5.0225674","DOIUrl":"https://doi.org/10.1063/5.0225674","url":null,"abstract":"Internal wave is essentially a gravity wave induced by the layered structure of water (e.g., density stable layering), with its maximum amplitude occurring within the ocean. Similar to surface waves, internal waves have significant influence on the strength and stability of a submerged body as an external factor. Meanwhile, combined shells are exposed to complicated loads under internal waves, and edge stress is dominant. In this study, the edge stresses of combined shell (typical hemisphere–cylinder combined shell and unfolded sphere–cylinder combined shell) under internal waves were analyzed. Indeed, a semi-empirical, semi-theoretical formula for the edge stress of combined shells (typical hemisphere–cylinder combined shell and unfolded sphere–cylinder combined shell) has been proposed. In this study, the semi-empirical, semi-theoretical formula was corrected by introducing internal wave loads, with the depth of the internal wave taken into consideration. In addition, the corrected formula was verified by finite element analysis, and a simplified equation for the calculation of edge stress of the combined shell under internal waves was developed, with errors in a rational range.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"20 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185397","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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