In this paper, a numerical computation method for the Gierer–Meinhardt model in two-dimensional space diffusion with homogeneous Neumann boundary conditions, considering the interaction between activator and inhibitor substances, is proposed. First, a high-order compact finite difference scheme is constructed for the Gierer–Meinhardt model using the finite difference method. A fourth-order compact difference scheme is applied to the second-order spatial derivative terms, while the time derivative terms are discretized using Taylor series expansion and residual correction functions. Consequently, the difference scheme achieves fourth-order accuracy in space and second-order accuracy in time for the Gierer–Meinhardt model. In addition, the stability of the difference scheme is demonstrated using Fourier analysis. Finally, numerical simulations are conducted on the Gierer–Meinhardt model near its equilibrium point to explore the impact of the inhibitor degradation rate, denoted as E, on the pattern formation. The model exhibits distinct pattern structures with varying E, thereby revealing the relationship between tissue variability and pattern formation in biological systems.
本文提出了一种考虑到激活剂和抑制剂物质之间相互作用的二维空间扩散中具有均质 Neumann 边界条件的 Gierer-Meinhardt 模型的数值计算方法。首先，利用有限差分法为 Gierer-Meinhardt 模型构建了一个高阶紧凑有限差分方案。对二阶空间导数项采用四阶紧凑差分方案，对时间导数项采用泰勒级数展开和残差修正函数进行离散化。因此，差分方案实现了 Gierer-Meinhardt 模型的空间四阶精度和时间二阶精度。此外，还利用傅立叶分析证明了差分方案的稳定性。最后，对接近平衡点的 Gierer-Meinhardt 模型进行了数值模拟，以探讨抑制剂降解率（用 E 表示）对图案形成的影响。随着 E 的变化，模型呈现出不同的图案结构，从而揭示了生物系统中组织变化与图案形成之间的关系。
{"title":"Analyzing the dynamic behavior of the Gierer–Meinhardt model using finite difference method","authors":"Jianping Lv, Hefang Jing","doi":"10.1063/5.0223717","DOIUrl":"https://doi.org/10.1063/5.0223717","url":null,"abstract":"In this paper, a numerical computation method for the Gierer–Meinhardt model in two-dimensional space diffusion with homogeneous Neumann boundary conditions, considering the interaction between activator and inhibitor substances, is proposed. First, a high-order compact finite difference scheme is constructed for the Gierer–Meinhardt model using the finite difference method. A fourth-order compact difference scheme is applied to the second-order spatial derivative terms, while the time derivative terms are discretized using Taylor series expansion and residual correction functions. Consequently, the difference scheme achieves fourth-order accuracy in space and second-order accuracy in time for the Gierer–Meinhardt model. In addition, the stability of the difference scheme is demonstrated using Fourier analysis. Finally, numerical simulations are conducted on the Gierer–Meinhardt model near its equilibrium point to explore the impact of the inhibitor degradation rate, denoted as E, on the pattern formation. The model exhibits distinct pattern structures with varying E, thereby revealing the relationship between tissue variability and pattern formation in biological systems.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"72 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943490","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}
Kai Wang, Jiwei Zhao, Zhangyou Yang, Peixuan Zhu, Huan Lu, Bin Zheng
The emergence of 5G represents a pivotal step in merging mobile communication networks with the Industrial Internet of Things. Despite the numerous advantages of 5G, the presence of unknown obstacles can adversely affect user signals. Although mitigating signal pressures can be achieved by increasing base station density, it often involves bulky equipment and high costs. To address this, we propose a deep learning-based method for controlling tunable transmissive metasurfaces and validate their scattering control capabilities in the presence of obstacles. By constructing a network model to analyze the mapping relationship between metasurface arrays and far-field scattering, rapid control of scattering characteristics is achieved. AI-driven high-performance tunable metasurfaces exhibit vast potential applications in intelligent communication, offering a universal solution for intelligent control in complex signal environments.
{"title":"Programmable transmission metasurface scattering control under obstacles based on deep learning","authors":"Kai Wang, Jiwei Zhao, Zhangyou Yang, Peixuan Zhu, Huan Lu, Bin Zheng","doi":"10.1063/5.0217386","DOIUrl":"https://doi.org/10.1063/5.0217386","url":null,"abstract":"The emergence of 5G represents a pivotal step in merging mobile communication networks with the Industrial Internet of Things. Despite the numerous advantages of 5G, the presence of unknown obstacles can adversely affect user signals. Although mitigating signal pressures can be achieved by increasing base station density, it often involves bulky equipment and high costs. To address this, we propose a deep learning-based method for controlling tunable transmissive metasurfaces and validate their scattering control capabilities in the presence of obstacles. By constructing a network model to analyze the mapping relationship between metasurface arrays and far-field scattering, rapid control of scattering characteristics is achieved. AI-driven high-performance tunable metasurfaces exhibit vast potential applications in intelligent communication, offering a universal solution for intelligent control in complex signal environments.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"23 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943487","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}
Dongjian Su, Qingwei An, Shao Xue, Hao Wang, Ruyi Tao
The impulse thruster exhibits the advantages of the simplistic structure and rapid response speed. It is often used for the attitude adjustment and orbit control of the aircraft and space vehicle. In order to study the internal ballistic variation law and the flow characteristics of the gunpowder gas, the interior working process of the L-type impulse thruster was investigated by the numerical simulation and experimental verification. First, an internal ballistic test was designed and conducted, and the change process of the thrust and pressure over time was measured, and the feasibility and rationality of the impulse thruster design were verified. Second, a three-dimensional internal ballistic model of the L-type impulse thruster including the ignition process was established. With the help of the dynamic mesh technology and secondary development capability of the user-defined function in the software Fluent, the coupling process of the propellant combustion and internal flow field change of the gunpowder gas was realized. The calculated results were in good agreement with the test data. Finally, the distribution of the pressure and velocity in the flow field was analyzed in detail, and the variation law of the thrust characteristics with the nozzle length and the expansion ratio was studied, which could provide the essential data for further optimization design research. The outcomes from this paper can offer technical means for advancing studies on the internal ballistic changing law of the L-type impulse thruster.
脉冲推进器具有结构简单、响应速度快等优点。它常用于飞机和空间飞行器的姿态调整和轨道控制。为了研究内弹道变化规律和火药气体的流动特性，通过数值模拟和实验验证，对 L 型脉冲推进器的内部工作过程进行了研究。首先，设计并进行了内弹道试验，测量了推力和压力随时间的变化过程，验证了脉冲推进器设计的可行性和合理性。其次，建立了包括点火过程在内的 L 型脉冲推进器三维内弹道模型。借助 Fluent 软件中的动态网格技术和用户自定义函数的二次开发能力，实现了推进剂燃烧与火药气体内部流场变化的耦合过程。计算结果与试验数据吻合良好。最后，详细分析了流场中压力和速度的分布，研究了推力特性随喷管长度和膨胀比的变化规律，为进一步优化设计研究提供了重要数据。本文的研究成果可为推进 L 型脉冲推进器内弹道变化规律的研究提供技术手段。
{"title":"Experiment and numerical investigation on internal ballistic characteristics of L-type impulse thruster","authors":"Dongjian Su, Qingwei An, Shao Xue, Hao Wang, Ruyi Tao","doi":"10.1063/5.0219940","DOIUrl":"https://doi.org/10.1063/5.0219940","url":null,"abstract":"The impulse thruster exhibits the advantages of the simplistic structure and rapid response speed. It is often used for the attitude adjustment and orbit control of the aircraft and space vehicle. In order to study the internal ballistic variation law and the flow characteristics of the gunpowder gas, the interior working process of the L-type impulse thruster was investigated by the numerical simulation and experimental verification. First, an internal ballistic test was designed and conducted, and the change process of the thrust and pressure over time was measured, and the feasibility and rationality of the impulse thruster design were verified. Second, a three-dimensional internal ballistic model of the L-type impulse thruster including the ignition process was established. With the help of the dynamic mesh technology and secondary development capability of the user-defined function in the software Fluent, the coupling process of the propellant combustion and internal flow field change of the gunpowder gas was realized. The calculated results were in good agreement with the test data. Finally, the distribution of the pressure and velocity in the flow field was analyzed in detail, and the variation law of the thrust characteristics with the nozzle length and the expansion ratio was studied, which could provide the essential data for further optimization design research. The outcomes from this paper can offer technical means for advancing studies on the internal ballistic changing law of the L-type impulse thruster.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"60 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943492","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}
In order to enhance the support capability of photovoltaic inverters for new energy microgrid systems, grid-forming control technology has attracted widespread attention, with Virtual Synchronous Generator (VSG) emerging as a research frontier. This paper integrates hybrid energy storage systems with photovoltaic generation to provide stable voltage support and power compensation for the system. In addition, leveraging the variability of the virtual parameters J and D in traditional VSGs, an adaptive grid-forming photovoltaic inverter control strategy based on fuzzy algorithm is proposed. Furthermore, to reduce the frequency deviation caused by load transients during islanding operation, an adaptive droop coefficient based on frequency power limits is introduced. Finally, simulations are conducted under grid-connected and islanded conditions to compare three control methods: fixed parameter control, traditional adaptive control, and the proposed adaptive with fuzzy control. The results demonstrate that integrating adaptive droop coefficients with fuzzy control can effectively improve the frequency stability and dynamic response capability of microgrids.
为增强光伏逆变器对新能源微电网系统的支持能力，并网控制技术受到广泛关注，其中虚拟同步发电机（VSG）成为研究前沿。本文将混合储能系统与光伏发电相结合，为系统提供稳定的电压支持和功率补偿。此外，利用传统 VSG 中虚拟参数 J 和 D 的可变性，提出了一种基于模糊算法的自适应并网光伏逆变器控制策略。此外，为了减少孤岛运行期间负载瞬变引起的频率偏差，还引入了基于频率功率限制的自适应下垂系数。最后，在并网和孤岛条件下进行了仿真，比较了三种控制方法：固定参数控制、传统自适应控制和所提出的自适应模糊控制。结果表明，将自适应下垂系数与模糊控制相结合可有效提高微电网的频率稳定性和动态响应能力。
{"title":"Adaptive grid-forming photovoltaic inverter control strategy based on fuzzy algorithm","authors":"Chenzhao Wang, Kan Cao, Pan Hu","doi":"10.1063/5.0223194","DOIUrl":"https://doi.org/10.1063/5.0223194","url":null,"abstract":"In order to enhance the support capability of photovoltaic inverters for new energy microgrid systems, grid-forming control technology has attracted widespread attention, with Virtual Synchronous Generator (VSG) emerging as a research frontier. This paper integrates hybrid energy storage systems with photovoltaic generation to provide stable voltage support and power compensation for the system. In addition, leveraging the variability of the virtual parameters J and D in traditional VSGs, an adaptive grid-forming photovoltaic inverter control strategy based on fuzzy algorithm is proposed. Furthermore, to reduce the frequency deviation caused by load transients during islanding operation, an adaptive droop coefficient based on frequency power limits is introduced. Finally, simulations are conducted under grid-connected and islanded conditions to compare three control methods: fixed parameter control, traditional adaptive control, and the proposed adaptive with fuzzy control. The results demonstrate that integrating adaptive droop coefficients with fuzzy control can effectively improve the frequency stability and dynamic response capability of microgrids.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"24 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943489","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}
Manish Kumar Singh, Kadiyam Anusha, A. D. D. Dwivedi
Transistors find application within various integrated circuits (ICs) alongside a multitude of electronic devices. These ICs have become integral components in contemporary systems. When organic semiconducting materials constitute the active layer, transistors are termed “organic transistors.” The enhancement of diverse device characteristics is achievable through the modeling and simulation of these organic transistors. This study focuses on the simulation of different configurations of pentacene-based organic transistors. To augment device performance, an active layer comprising pentacene is coupled with 5 and 15 nm graphene. Notably, the top gate configuration yields an increase in ON/OFF ratio from 102 to 107, accompanied by an enhancement in sub-threshold swing from 276 to 59 mV/decade. Similarly, the bottom gate configuration exhibits an ON/OFF ratio improvement from 105 to 109, alongside a sub-threshold swing enhancement from 108 to 59 mV/decade. Leveraging graphene as the active layer material results in substantial benefits. These encompass a heightened on-current of 210 mA, a reduced sub-threshold swing of 58 mV/decade, and a significantly enhanced ON/OFF ratio of 1017.
{"title":"Enhancing device characteristics of pentacene-based organic transistors through graphene integration: A simulation study and performance analysis","authors":"Manish Kumar Singh, Kadiyam Anusha, A. D. D. Dwivedi","doi":"10.1063/5.0218617","DOIUrl":"https://doi.org/10.1063/5.0218617","url":null,"abstract":"Transistors find application within various integrated circuits (ICs) alongside a multitude of electronic devices. These ICs have become integral components in contemporary systems. When organic semiconducting materials constitute the active layer, transistors are termed “organic transistors.” The enhancement of diverse device characteristics is achievable through the modeling and simulation of these organic transistors. This study focuses on the simulation of different configurations of pentacene-based organic transistors. To augment device performance, an active layer comprising pentacene is coupled with 5 and 15 nm graphene. Notably, the top gate configuration yields an increase in ON/OFF ratio from 102 to 107, accompanied by an enhancement in sub-threshold swing from 276 to 59 mV/decade. Similarly, the bottom gate configuration exhibits an ON/OFF ratio improvement from 105 to 109, alongside a sub-threshold swing enhancement from 108 to 59 mV/decade. Leveraging graphene as the active layer material results in substantial benefits. These encompass a heightened on-current of 210 mA, a reduced sub-threshold swing of 58 mV/decade, and a significantly enhanced ON/OFF ratio of 1017.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"8 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943491","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}
Dipjyoti Balo Majumder, Rishi Verma, J. M. V. V. S. Aravind, J. N. Rao, Manraj Meena, Lakshman Rao Rongali, Bijayalaxmi Sethi, Archana Sharma
In this paper, the effect of driving current profile on efficient utilization and conversion of stored electrical energy into kinetic energy of the projectile has been investigated for electromagnetic railgun systems. It has been experimentally evidenced and also corroborated by simulation results that the acceleration efficiency of railgun launcher is much higher for the case when the driving current feed has an over-damped unidirectional profile vs the case when an under-damped sinusoidal current of same amplitude is fed. To analyze this effect, a mathematical model has been developed incorporating dynamic resistance scaling and velocity dependent frictional effects. For the typical case of projectile weighing ∼8 g and input driving current amplitude of ∼220 kA, the estimated average force from the mathematical model simulation acting on the armature projectile increases from 1.4 to 3.83 kN, consequently resulting in an increase in velocity from 489 to 931 m/s and overall efficiency from 0.55% to 2% for the sinusoidal and unidirectional current profiles, respectively. Experimentally, a maximum velocity of ∼1024 m/s was obtained when a unidirectional over-damped current of similar amplitude was fed using a pulse shaping inductor in conjunction with a crowbar switch. The obtained experimental results of trials with different masses of armatures complement the results of the conceived mathematical model used in simulations. The marginal underestimation of the simulated velocity is due to the inevitable lacking in precise estimation of the frictional force and mass loss that dynamically occur in the projectile during acceleration.
本文研究了电磁轨道炮系统的驱动电流剖面对有效利用存储电能并将其转化为弹丸动能的影响。实验和模拟结果都证明，当馈入的驱动电流为过阻尼单向电流时，轨道炮发射器的加速效率要比馈入相同振幅的欠阻尼正弦电流时高得多。为了分析这种效应，我们建立了一个数学模型，其中包含动态阻力缩放和速度相关摩擦效应。在弹丸重量为 ∼8 g 和输入驱动电流振幅为 ∼220 kA 的典型情况下，数学模型模拟估算的作用在电枢弹丸上的平均力从 1.4 kN 增加到 3.83 kN，从而导致速度从 489 m/s 增加到 931 m/s，正弦和单向电流曲线的总效率分别从 0.55% 增加到 2%。实验结果表明，当使用脉冲整形电感和撬棒开关馈入类似振幅的单向过阻尼电流时，最大速度可达 ∼1024 m/s。不同质量电枢的试验结果与模拟所用数学模型的结果相辅相成。模拟速度被略微低估的原因是对加速过程中弹丸动态产生的摩擦力和质量损失缺乏精确的估计。
{"title":"Effect of driving current profile on acceleration efficiency of electromagnetic railgun","authors":"Dipjyoti Balo Majumder, Rishi Verma, J. M. V. V. S. Aravind, J. N. Rao, Manraj Meena, Lakshman Rao Rongali, Bijayalaxmi Sethi, Archana Sharma","doi":"10.1063/5.0214320","DOIUrl":"https://doi.org/10.1063/5.0214320","url":null,"abstract":"In this paper, the effect of driving current profile on efficient utilization and conversion of stored electrical energy into kinetic energy of the projectile has been investigated for electromagnetic railgun systems. It has been experimentally evidenced and also corroborated by simulation results that the acceleration efficiency of railgun launcher is much higher for the case when the driving current feed has an over-damped unidirectional profile vs the case when an under-damped sinusoidal current of same amplitude is fed. To analyze this effect, a mathematical model has been developed incorporating dynamic resistance scaling and velocity dependent frictional effects. For the typical case of projectile weighing ∼8 g and input driving current amplitude of ∼220 kA, the estimated average force from the mathematical model simulation acting on the armature projectile increases from 1.4 to 3.83 kN, consequently resulting in an increase in velocity from 489 to 931 m/s and overall efficiency from 0.55% to 2% for the sinusoidal and unidirectional current profiles, respectively. Experimentally, a maximum velocity of ∼1024 m/s was obtained when a unidirectional over-damped current of similar amplitude was fed using a pulse shaping inductor in conjunction with a crowbar switch. The obtained experimental results of trials with different masses of armatures complement the results of the conceived mathematical model used in simulations. The marginal underestimation of the simulated velocity is due to the inevitable lacking in precise estimation of the frictional force and mass loss that dynamically occur in the projectile during acceleration.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"23 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943495","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}
Kuo Wang, Zhanqiang Zhang, Keqilao Meng, Pengbing Lei, Rui Wang, Wenlu Yang, Zhihua Lin
Owing to the volatility and intermittency of renewable energy generation units in microgrids, effective energy scheduling methods are essential for efficient renewable energy utilization and stable microgrid operation. In recent years, microgrid energy optimization scheduling based on deep reinforcement learning (DRL) has made significant progress. With the development of the microgrid, the drawbacks of the traditional DRL agent, such as long training time and poor convergence effect, are gradually revealed. This paper proposes a generative adversarial imitation learning method with Wasserstein distance for optimal energy scheduling in the microgrid. This method combines a proximal policy optimization algorithm to optimize energy scheduling and reduce microgrid operating costs. First, the agent adaptively learns the action exploration process by imitating expert trajectories. Second, based on the generative adversarial theory, a discriminator network is added, and the Wasserstein distance is introduced into the discriminator network to distinguish between the generative and expert strategies. This feedback assists in updating the neural network parameters. Finally, the effectiveness of the proposed method is verified through an arithmetic example analysis.
{"title":"Optimal energy scheduling for microgrid based on GAIL with Wasserstein distance","authors":"Kuo Wang, Zhanqiang Zhang, Keqilao Meng, Pengbing Lei, Rui Wang, Wenlu Yang, Zhihua Lin","doi":"10.1063/5.0207444","DOIUrl":"https://doi.org/10.1063/5.0207444","url":null,"abstract":"Owing to the volatility and intermittency of renewable energy generation units in microgrids, effective energy scheduling methods are essential for efficient renewable energy utilization and stable microgrid operation. In recent years, microgrid energy optimization scheduling based on deep reinforcement learning (DRL) has made significant progress. With the development of the microgrid, the drawbacks of the traditional DRL agent, such as long training time and poor convergence effect, are gradually revealed. This paper proposes a generative adversarial imitation learning method with Wasserstein distance for optimal energy scheduling in the microgrid. This method combines a proximal policy optimization algorithm to optimize energy scheduling and reduce microgrid operating costs. First, the agent adaptively learns the action exploration process by imitating expert trajectories. Second, based on the generative adversarial theory, a discriminator network is added, and the Wasserstein distance is introduced into the discriminator network to distinguish between the generative and expert strategies. This feedback assists in updating the neural network parameters. Finally, the effectiveness of the proposed method is verified through an arithmetic example analysis.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"18 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943493","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}
Leonid A. Bulavin, Yevgenii G. Rudnikov, Alexander V. Chalyi
Using modern databases, the behavior of the isothermal compressibility coefficient −(∂V/∂P)T = VβT of water in the liquid state near its specific temperature of θ = 42.2 ± 0.2 °C was analyzed. The applicability of the principle of corresponding states in a wide range of thermodynamic parameters of water has been confirmed, excluding the area of water anomalies. The following anomalies of the physical–chemical properties of water were observed: (a) the temperature of θ = 42.2 ± 0.2 °C was found at which the entropy contribution to the isothermal compressibility coefficient of water changed its sign and became positive below this temperature; (b) the temperature of θ = 28.8 ± 0.2 °C was found at which the energy contribution to the isothermal compressibility coefficient of water changed its sign and became negative below this temperature; and (c) the temperature of θ = 17.6 ± 0.2 °C was found at which the energy and entropy contributions to the isothermal compressibility coefficient of water were equal. The entropy contribution to the isothermal compressibility coefficient, according to the two-structure model of water, can be associated with the existence of an “expanded” low-density water structure of hydrogen bonds, the role of which increases with decreasing temperature. We associate the energy contribution to the isothermal compressibility coefficient with the “collapsed” high-density water structure of hydrogen bonds, the role of which in the field of thermodynamic anomalies of water decreases as the temperature decreases.
{"title":"Contributions to the isothermal compressibility coefficient of water near the temperature of 42 °C","authors":"Leonid A. Bulavin, Yevgenii G. Rudnikov, Alexander V. Chalyi","doi":"10.1063/5.0205612","DOIUrl":"https://doi.org/10.1063/5.0205612","url":null,"abstract":"Using modern databases, the behavior of the isothermal compressibility coefficient −(∂V/∂P)T = VβT of water in the liquid state near its specific temperature of θ = 42.2 ± 0.2 °C was analyzed. The applicability of the principle of corresponding states in a wide range of thermodynamic parameters of water has been confirmed, excluding the area of water anomalies. The following anomalies of the physical–chemical properties of water were observed: (a) the temperature of θ = 42.2 ± 0.2 °C was found at which the entropy contribution to the isothermal compressibility coefficient of water changed its sign and became positive below this temperature; (b) the temperature of θ = 28.8 ± 0.2 °C was found at which the energy contribution to the isothermal compressibility coefficient of water changed its sign and became negative below this temperature; and (c) the temperature of θ = 17.6 ± 0.2 °C was found at which the energy and entropy contributions to the isothermal compressibility coefficient of water were equal. The entropy contribution to the isothermal compressibility coefficient, according to the two-structure model of water, can be associated with the existence of an “expanded” low-density water structure of hydrogen bonds, the role of which increases with decreasing temperature. We associate the energy contribution to the isothermal compressibility coefficient with the “collapsed” high-density water structure of hydrogen bonds, the role of which in the field of thermodynamic anomalies of water decreases as the temperature decreases.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"36 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943494","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}
In isotope concentration technology, ion extraction current and ion extraction efficiency are the key factors to measure the efficiency of the isotope concentration. In order to increase the ion extraction current, researchers usually hope to produce a plasma source with large initial peak density and width; however, in reality, it is limited by the laser power, and the total number of ions in a plasma produced by laser ionization is almost certain. In this case, how to improve the ion extraction efficiency by choosing the appropriate initial density distribution of plasma has become a difficult problem. In this paper, the effects of the initial density distribution of plasma on the ion extraction characteristics are studied by using the electron equilibrium fluid model. The numerical results suggest that the ion extraction efficiency is independent of the initial density distribution of plasma while the total number of ions in the plasma, the distance between the electrodes, and the electric field intensity are kept constant. When the total number of ions and the electric field intensity are kept constant, the distance between the electrodes is shortened by one time, and the time of ion extraction is also shortened by nearly one time; thus, the plasma source with high initial peak density and small width can be chosen, and the aim of ion extraction can be achieved by shortening the distance between the electrodes. This research results provide an important reference for guiding the experimental parameters such as laser power distribution and the design of ion extraction device.
{"title":"Simulation study on the influence of initial density distribution of laser ionized plasma on the ion extraction characteristics","authors":"Xing Chen, Xiao-Yong Lu, Lu Cai","doi":"10.1063/5.0206433","DOIUrl":"https://doi.org/10.1063/5.0206433","url":null,"abstract":"In isotope concentration technology, ion extraction current and ion extraction efficiency are the key factors to measure the efficiency of the isotope concentration. In order to increase the ion extraction current, researchers usually hope to produce a plasma source with large initial peak density and width; however, in reality, it is limited by the laser power, and the total number of ions in a plasma produced by laser ionization is almost certain. In this case, how to improve the ion extraction efficiency by choosing the appropriate initial density distribution of plasma has become a difficult problem. In this paper, the effects of the initial density distribution of plasma on the ion extraction characteristics are studied by using the electron equilibrium fluid model. The numerical results suggest that the ion extraction efficiency is independent of the initial density distribution of plasma while the total number of ions in the plasma, the distance between the electrodes, and the electric field intensity are kept constant. When the total number of ions and the electric field intensity are kept constant, the distance between the electrodes is shortened by one time, and the time of ion extraction is also shortened by nearly one time; thus, the plasma source with high initial peak density and small width can be chosen, and the aim of ion extraction can be achieved by shortening the distance between the electrodes. This research results provide an important reference for guiding the experimental parameters such as laser power distribution and the design of ion extraction device.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"43 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943284","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}
Global path planning is one of the key technologies in unmanned underwater vehicle (UUV) intelligent control. At present, research on UUV global path planning technology tends to choose long-distance and large-scale 3D space as the research environment, which leads to a sharp increase in the amount of data and search range for 3D spatial path planning. Therefore, an efficient and relatively small data volume 3D spatial path planning method is an urgent problem that needs to be solved for UUV engineering applications. To solve this problem, a new bilevel path planning algorithm for UUV is proposed. In the upper level of the algorithm, a Max Min Ant System-Elite Genetic (MMAS-EGA) algorithm is put forward, which is a hybrid ant colony optimization/genetic algorithm, in order to improve the convergence speed of the algorithm. In the lower level of the bilevel algorithm, a function optimization algorithm and the MMAS algorithm are used to minimize the number of variables to be optimized. To verify the effectiveness of the algorithm, we conducted simulation experiments in a three dimensional environment. The simulation results in the three-dimensional environment show that, compared with the existing bilevel algorithm, the time to search the global optimal solution is reduced by 9%, and the number of iterations is reduced by 4.4%. Furthermore, the new algorithm we proposed is more efficient and suitable for global path planning for different tasks.
{"title":"A new bilevel algorithm for UUV global path planning","authors":"Xin Pan, Guoli Feng, Lin Huang, Haiyan Zeng","doi":"10.1063/5.0207107","DOIUrl":"https://doi.org/10.1063/5.0207107","url":null,"abstract":"Global path planning is one of the key technologies in unmanned underwater vehicle (UUV) intelligent control. At present, research on UUV global path planning technology tends to choose long-distance and large-scale 3D space as the research environment, which leads to a sharp increase in the amount of data and search range for 3D spatial path planning. Therefore, an efficient and relatively small data volume 3D spatial path planning method is an urgent problem that needs to be solved for UUV engineering applications. To solve this problem, a new bilevel path planning algorithm for UUV is proposed. In the upper level of the algorithm, a Max Min Ant System-Elite Genetic (MMAS-EGA) algorithm is put forward, which is a hybrid ant colony optimization/genetic algorithm, in order to improve the convergence speed of the algorithm. In the lower level of the bilevel algorithm, a function optimization algorithm and the MMAS algorithm are used to minimize the number of variables to be optimized. To verify the effectiveness of the algorithm, we conducted simulation experiments in a three dimensional environment. The simulation results in the three-dimensional environment show that, compared with the existing bilevel algorithm, the time to search the global optimal solution is reduced by 9%, and the number of iterations is reduced by 4.4%. Furthermore, the new algorithm we proposed is more efficient and suitable for global path planning for different tasks.","PeriodicalId":7619,"journal":{"name":"AIP Advances","volume":"60 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943288","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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