Pub Date : 2023-12-02DOI: 10.1142/s0217984924501367
Xin Guo, Ping Yang, Jiayin Zhang, Junqiang Ren, Xuefeng Lu
In this paper, the effects of rare earth elements on the bonding strength and stability of TiC/fcc-Fe interface are explored by using the first-principles method based on density functional theory. The results show that the Ti terminal is more stable than the C terminal in the process of forming the interface. The alloying elements tend to segregate at position 2 on the side of fcc-Fe. The segregation of Mo, Nb, Cr and Ce alloying elements increases the interatomic electron cloud enrichment and consumption between the interfaces and enhances the Fe–Ti interactions. The d orbitals of Mo, Nb, Cr and Ce and f orbitals of Ce have strong hybridization with Fe-d orbitals and Ti-d orbitals electrons near the Fermi energy level, indicating an increase in bonding strength and stability of the interfaces. When Fe atoms are replaced by W, Ni and Al atoms, the covalent bond strength between interfacial atoms is reduced, thus weakening the interfacial bonding strength. This provides solid theoretical foundation with regard to further application in austenitic heat-resistant steel fields.
{"title":"Segregation behavior of alloying elements at the fcc-Fe/TiC interface by first principles exploration","authors":"Xin Guo, Ping Yang, Jiayin Zhang, Junqiang Ren, Xuefeng Lu","doi":"10.1142/s0217984924501367","DOIUrl":"https://doi.org/10.1142/s0217984924501367","url":null,"abstract":"In this paper, the effects of rare earth elements on the bonding strength and stability of TiC/fcc-Fe interface are explored by using the first-principles method based on density functional theory. The results show that the Ti terminal is more stable than the C terminal in the process of forming the interface. The alloying elements tend to segregate at position 2 on the side of fcc-Fe. The segregation of Mo, Nb, Cr and Ce alloying elements increases the interatomic electron cloud enrichment and consumption between the interfaces and enhances the Fe–Ti interactions. The d orbitals of Mo, Nb, Cr and Ce and f orbitals of Ce have strong hybridization with Fe-d orbitals and Ti-d orbitals electrons near the Fermi energy level, indicating an increase in bonding strength and stability of the interfaces. When Fe atoms are replaced by W, Ni and Al atoms, the covalent bond strength between interfacial atoms is reduced, thus weakening the interfacial bonding strength. This provides solid theoretical foundation with regard to further application in austenitic heat-resistant steel fields.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"77 7","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138606023","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}
Pub Date : 2023-12-02DOI: 10.1142/s0217984924501306
Aamir Ali, Hajra Safdar Khan, Ifra Noor, A. Pasha, K. Irshad, Mohammad K. Al Mesfer, Mohd Danish
The study of nanofluids and hybrid nanofluids is gaining conceivable importance due to their characteristics of being so useful in various daily life applications. This study deals with the motion of an electro conductive, incompressible magneto-hydrodynamic (MHD) hybrid nanofluid across a stretched surface of variable thickness. The objective of this study is motivated by a number of manufacturing and machine-building applications. However, no attempt has been made to establish MHD flow of hybrid nanofluid along a stretching sheet (a sheet with variable thickness) while keeping an eye on the impact of Hall current. In real-life situations, variable-thickness sheets are crucial in the creation of flexible containers and, additionally, in the layout and production of aerospace wings and auto body components. This study extends our fundamental knowledge of fluid dynamics and heat transmission in intricate systems. Recognizing how magnetic effects, nanofluid traits and heat conduction interplay can help researchers make valuable developments and breakthroughs in the areas of fluid mechanics and heat transfer. Hall effects are vital for applications including conductive fluids or plasma as they provide a more precise understanding of the movement of charged nanoparticles in the presence of a magnetic field. For hybrid nanofluid, we mixed the nanoparticles of titanium dioxide and copper (TiO2–Cu) into the water. Due to the low noxiousness and chemical strength of titanium dioxide-based nanoparticles, they have great uses in research. We also consider the effects of Cattaneo–Christov heat flux to analyze the heat transfer of nanoparticles and Hall current effects, which make the flow three-dimensional. For both fundamental research and real-world applications, it is of the utmost importance to take into account the Hall effects and Cattaneo–Christov heat flux in the MHD flow analysis of hybrid nanofluid over stretched surface. It makes it possible to describe the phenomenon more precisely and can enhance the effectiveness and efficiency of numerous technical procedures. By using appropriate transformations, the equations that govern the flow are transformed into a system of non-dimensional ordinary differential equations. The non-dimensional system of equations has been solved numerically by using the ND Solve command in Mathematica Software, which is based on a multistep predictor-corrector method. For velocity and temperature profiles, the interplay of numerous developing parameters on flow is depicted graphically. The Hall parameter enhances the axial velocity but reduces the transverse velocity, while the magnetic field has the opposite effects. The temperature increases with the volume fraction of nanoparticles but decreases with the thermal relaxation parameter.
{"title":"Hall effects and Cattaneo–Christov heat flux on MHD flow of hybrid nanofluid over a varying thickness stretching surface","authors":"Aamir Ali, Hajra Safdar Khan, Ifra Noor, A. Pasha, K. Irshad, Mohammad K. Al Mesfer, Mohd Danish","doi":"10.1142/s0217984924501306","DOIUrl":"https://doi.org/10.1142/s0217984924501306","url":null,"abstract":"The study of nanofluids and hybrid nanofluids is gaining conceivable importance due to their characteristics of being so useful in various daily life applications. This study deals with the motion of an electro conductive, incompressible magneto-hydrodynamic (MHD) hybrid nanofluid across a stretched surface of variable thickness. The objective of this study is motivated by a number of manufacturing and machine-building applications. However, no attempt has been made to establish MHD flow of hybrid nanofluid along a stretching sheet (a sheet with variable thickness) while keeping an eye on the impact of Hall current. In real-life situations, variable-thickness sheets are crucial in the creation of flexible containers and, additionally, in the layout and production of aerospace wings and auto body components. This study extends our fundamental knowledge of fluid dynamics and heat transmission in intricate systems. Recognizing how magnetic effects, nanofluid traits and heat conduction interplay can help researchers make valuable developments and breakthroughs in the areas of fluid mechanics and heat transfer. Hall effects are vital for applications including conductive fluids or plasma as they provide a more precise understanding of the movement of charged nanoparticles in the presence of a magnetic field. For hybrid nanofluid, we mixed the nanoparticles of titanium dioxide and copper (TiO2–Cu) into the water. Due to the low noxiousness and chemical strength of titanium dioxide-based nanoparticles, they have great uses in research. We also consider the effects of Cattaneo–Christov heat flux to analyze the heat transfer of nanoparticles and Hall current effects, which make the flow three-dimensional. For both fundamental research and real-world applications, it is of the utmost importance to take into account the Hall effects and Cattaneo–Christov heat flux in the MHD flow analysis of hybrid nanofluid over stretched surface. It makes it possible to describe the phenomenon more precisely and can enhance the effectiveness and efficiency of numerous technical procedures. By using appropriate transformations, the equations that govern the flow are transformed into a system of non-dimensional ordinary differential equations. The non-dimensional system of equations has been solved numerically by using the ND Solve command in Mathematica Software, which is based on a multistep predictor-corrector method. For velocity and temperature profiles, the interplay of numerous developing parameters on flow is depicted graphically. The Hall parameter enhances the axial velocity but reduces the transverse velocity, while the magnetic field has the opposite effects. The temperature increases with the volume fraction of nanoparticles but decreases with the thermal relaxation parameter.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"12 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138607007","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}
Pub Date : 2023-12-02DOI: 10.1142/s0217984923420150
Cheng Ma, Shuang Leng, Shanshan Cao
Angular velocity is a very important measurement parameter for autonomous driving and industrial applications. The design of MEMS quartz gyro measurement and control circuit has always been the key to restricting the measurement angular velocity performance of gyro system. This paper introduces the application-specific integrated circuit (ASIC) design and implementation of a MEMS quartz gyro measurement and control circuit for angular velocity measurement. The designed nonlinear multiplier can use a square wave to drive the gyro’s sensitive structure at the beginning of gyro start-up, thereby reducing the gyro power-up time. The drive circuit replaces the PLL with an automatic gain control unit composed of peak detection and proportional integration (PI) controller, which makes the MEMS gyro system have good robustness. First, SIMULINK is used to model and simulate the MEMS gyroscope system-level model, which illustrates the feasibility of the drive circuit design scheme. Then, the operating principle of the drive loop is analyzed, and the design of the key circuit modules of the measurement and control circuit is introduced. Finally, the performance of the gyroscope drive and detection circuit is experimentally tested, the amplitude and frequency uncertainty of the gyroscope drive circuit are evaluated, and the bias instability and nonlinearity of the gyroscope are tested, the experiment results show that the gyroscope has good performance.
{"title":"Design and development of MEMS quartz gyroscope measurement and control circuit with automatic gain control principle","authors":"Cheng Ma, Shuang Leng, Shanshan Cao","doi":"10.1142/s0217984923420150","DOIUrl":"https://doi.org/10.1142/s0217984923420150","url":null,"abstract":"Angular velocity is a very important measurement parameter for autonomous driving and industrial applications. The design of MEMS quartz gyro measurement and control circuit has always been the key to restricting the measurement angular velocity performance of gyro system. This paper introduces the application-specific integrated circuit (ASIC) design and implementation of a MEMS quartz gyro measurement and control circuit for angular velocity measurement. The designed nonlinear multiplier can use a square wave to drive the gyro’s sensitive structure at the beginning of gyro start-up, thereby reducing the gyro power-up time. The drive circuit replaces the PLL with an automatic gain control unit composed of peak detection and proportional integration (PI) controller, which makes the MEMS gyro system have good robustness. First, SIMULINK is used to model and simulate the MEMS gyroscope system-level model, which illustrates the feasibility of the drive circuit design scheme. Then, the operating principle of the drive loop is analyzed, and the design of the key circuit modules of the measurement and control circuit is introduced. Finally, the performance of the gyroscope drive and detection circuit is experimentally tested, the amplitude and frequency uncertainty of the gyroscope drive circuit are evaluated, and the bias instability and nonlinearity of the gyroscope are tested, the experiment results show that the gyroscope has good performance.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"78 17","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138606354","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}
Pub Date : 2023-11-30DOI: 10.1142/s0217984924501057
Raj Kumar, Hemant Kumar, U. Ramani, Sanket Kumar, Bipin K. Singh, P. P. Singh, P. C. Pandey
We propose a cross-shaped resonator design of a metamaterial (MTM) absorber that shows a 98% average absorbance in the range of 400–1100[Formula: see text]nm. This design consists of three layers: a tungsten-based cross-shaped on the top, silicon dioxide (SiO2) in the middle layer, and a tungsten layer at the bottom. The finite integration technique (FIT) method is used to simulate the metamaterial absorber’s performance. We have observed the absorber’s performance on the different thicknesses of a dielectric layer. We have presented the absorption spectrum for transverse electric (TE) and transverse magnetic (TM) modes for different polarization angles (0°–90°) and incident angles (0°–60°). Additionally, we have investigated the short-circuit current density for different dielectric layer thicknesses and different incidence angles. This is theoretically analogous to parametric studies. The universal AM 1.5 solar spectrum properties have been used to investigate the feasibility of the proposed MTM absorber as a solar cell. The proposed MTM has many potential uses, including for solar cells.
{"title":"Wide-angle and polarization-insensitive perfect metamaterial absorber","authors":"Raj Kumar, Hemant Kumar, U. Ramani, Sanket Kumar, Bipin K. Singh, P. P. Singh, P. C. Pandey","doi":"10.1142/s0217984924501057","DOIUrl":"https://doi.org/10.1142/s0217984924501057","url":null,"abstract":"We propose a cross-shaped resonator design of a metamaterial (MTM) absorber that shows a 98% average absorbance in the range of 400–1100[Formula: see text]nm. This design consists of three layers: a tungsten-based cross-shaped on the top, silicon dioxide (SiO2) in the middle layer, and a tungsten layer at the bottom. The finite integration technique (FIT) method is used to simulate the metamaterial absorber’s performance. We have observed the absorber’s performance on the different thicknesses of a dielectric layer. We have presented the absorption spectrum for transverse electric (TE) and transverse magnetic (TM) modes for different polarization angles (0°–90°) and incident angles (0°–60°). Additionally, we have investigated the short-circuit current density for different dielectric layer thicknesses and different incidence angles. This is theoretically analogous to parametric studies. The universal AM 1.5 solar spectrum properties have been used to investigate the feasibility of the proposed MTM absorber as a solar cell. The proposed MTM has many potential uses, including for solar cells.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":" 35","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139197470","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}
Pub Date : 2023-11-30DOI: 10.1142/s0217984924501380
R. E. Fdil, Z. Fadil, E. Salmani, R. Haldhar, H. Ez-zahraouy
In this study, we performed extensive Monte Carlo simulations to comprehensively analyze the magnetic properties of a single-layer MXene-like lattice. Our investigation involved the exploration of transition temperatures and the behavior of hysteresis cycles, all influenced by a series of key physical parameters. Additionally, we carefully mapped the magnetization as a function of temperature and crystal field, introducing variations in the exchange coupling to unveil their impact on the transition temperature. Furthermore, we investigated the behavior of hysteresis loops, complexly dissecting their responses to changes in exchange coupling, temperature, and crystal field. Significantly, our results highlight the central role of the crystal field in the formation of magnetization plateaus, thus providing promising avenues for applications in nanotechnology and advanced memory storage systems.
{"title":"Magnetic behavior of a ferrimagnetic MXene-like lattice: Monte Carlo study","authors":"R. E. Fdil, Z. Fadil, E. Salmani, R. Haldhar, H. Ez-zahraouy","doi":"10.1142/s0217984924501380","DOIUrl":"https://doi.org/10.1142/s0217984924501380","url":null,"abstract":"In this study, we performed extensive Monte Carlo simulations to comprehensively analyze the magnetic properties of a single-layer MXene-like lattice. Our investigation involved the exploration of transition temperatures and the behavior of hysteresis cycles, all influenced by a series of key physical parameters. Additionally, we carefully mapped the magnetization as a function of temperature and crystal field, introducing variations in the exchange coupling to unveil their impact on the transition temperature. Furthermore, we investigated the behavior of hysteresis loops, complexly dissecting their responses to changes in exchange coupling, temperature, and crystal field. Significantly, our results highlight the central role of the crystal field in the formation of magnetization plateaus, thus providing promising avenues for applications in nanotechnology and advanced memory storage systems.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"126 21","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139197111","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}
Pub Date : 2023-11-30DOI: 10.1142/s021798492450132x
H. Durur, Reyhan Arslantürk, Aleyna Aydın
This study deals with the Lonngren wave equation, which is used to model the transmission of electrical signals in a type of semiconductor material called a tunnel diode. The aim of this study is to produce dark soliton, singular soliton, trigonometric, complex rational solutions to the Lonngren wave equation by using the sub-equation method. Graphs representing the Lonngren wave are drawn by giving different values to the variables in the solutions obtained. Graphs are presented using a special package program. In the light of the data obtained as a result of the study, it is thought that this new method used in the research of the solution of the Lonngren wave equation will contribute to the literature.
{"title":"Mathematical analysis of electric signal transmission in semi-conductor materials","authors":"H. Durur, Reyhan Arslantürk, Aleyna Aydın","doi":"10.1142/s021798492450132x","DOIUrl":"https://doi.org/10.1142/s021798492450132x","url":null,"abstract":"This study deals with the Lonngren wave equation, which is used to model the transmission of electrical signals in a type of semiconductor material called a tunnel diode. The aim of this study is to produce dark soliton, singular soliton, trigonometric, complex rational solutions to the Lonngren wave equation by using the sub-equation method. Graphs representing the Lonngren wave are drawn by giving different values to the variables in the solutions obtained. Graphs are presented using a special package program. In the light of the data obtained as a result of the study, it is thought that this new method used in the research of the solution of the Lonngren wave equation will contribute to the literature.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"396 ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139203207","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}
Pub Date : 2023-11-30DOI: 10.1142/s0217984924501100
Yan Qiang, Minzu Zhang, Tianci Duan, Liejiang Wei, Wenqi Zhong
The flow structures of jet impingement dominate heat and mass transfer process, even the whole thermal performance. In this study, we have inspected the flow structures and mechanism of nanofluid jet impingement onto a dimpled target surface with different design parameters. Investigations are performed for the relative depth of dimple ([Formula: see text]), the jet-to-plate spacing ([Formula: see text]), nanoparticle volume concentration ([Formula: see text]), and Reynolds number (Re) ranging to explore the mechanism of flow structure variations. Results indicate that these parameters have a significant effect on the flow structure of nanofluid jet impingement near the dimpled target surface. The flow begins to separate after passing the edge of the dimple along with the curvature of a dimple. [Formula: see text] will affect the form and location of flow separation and reattachment, and [Formula: see text] will affect the intensity of separation flow. The length of the flow separation bubble varies in different [Formula: see text] cases. When [Formula: see text] increases, the impinging energy and the velocity near the dimple edge decreases. The different Re has little effect on the length of the flow separation bubble and the tendency of the pressure coefficient (Cp). These results can provide further mechanism inspiration for the design of the flow structure of nanofluid jet impingement.
射流撞击的流动结构主导着传热和传质过程，甚至整个热性能。本研究考察了不同设计参数下纳米流体射流撞击凹陷靶表面的流动结构和机理。我们对凹痕相对深度（[计算公式：见正文]）、射流与板间距（[计算公式：见正文]）、纳米粒子体积浓度（[计算公式：见正文]）和雷诺数（Re）范围进行了研究，以探索流动结构变化的机理。结果表明，这些参数对纳米流体射流撞击凹陷靶表面附近的流动结构有显著影响。流体在通过凹痕边缘后开始分离，凹痕的曲率也会影响流体的分离。[计算公式：见正文]将影响流动分离和重新附着的形式和位置，[计算公式：见正文]将影响分离流动的强度。在不同的[计算公式：见正文]情况下，分流气泡的长度也不同。当[计算公式：见正文]增大时，酒窝边缘附近的撞击能量和速度减小。不同的 Re 对分流泡的长度和压力系数（Cp）的变化趋势影响不大。这些结果可为纳米流体射流撞击的流动结构设计提供进一步的机理启示。
{"title":"Flow structure analysis of nanofluid impingement on modified target surface under different design parameters","authors":"Yan Qiang, Minzu Zhang, Tianci Duan, Liejiang Wei, Wenqi Zhong","doi":"10.1142/s0217984924501100","DOIUrl":"https://doi.org/10.1142/s0217984924501100","url":null,"abstract":"The flow structures of jet impingement dominate heat and mass transfer process, even the whole thermal performance. In this study, we have inspected the flow structures and mechanism of nanofluid jet impingement onto a dimpled target surface with different design parameters. Investigations are performed for the relative depth of dimple ([Formula: see text]), the jet-to-plate spacing ([Formula: see text]), nanoparticle volume concentration ([Formula: see text]), and Reynolds number (Re) ranging to explore the mechanism of flow structure variations. Results indicate that these parameters have a significant effect on the flow structure of nanofluid jet impingement near the dimpled target surface. The flow begins to separate after passing the edge of the dimple along with the curvature of a dimple. [Formula: see text] will affect the form and location of flow separation and reattachment, and [Formula: see text] will affect the intensity of separation flow. The length of the flow separation bubble varies in different [Formula: see text] cases. When [Formula: see text] increases, the impinging energy and the velocity near the dimple edge decreases. The different Re has little effect on the length of the flow separation bubble and the tendency of the pressure coefficient (Cp). These results can provide further mechanism inspiration for the design of the flow structure of nanofluid jet impingement.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"123 9","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139196722","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}
Pub Date : 2023-11-30DOI: 10.1142/s0217984924501239
Dongming Chen, W. Yuan, Xiangdong Han
In this paper, the motion of inertial particles in three-dimensional (3D) unsteady cylindrical wake flow is investigated by a two-way coupled Eulerian–Lagrangian approach. At different flow Reynolds numbers (Re), the corresponding striking dynamic property and dispersion mechanism of four particle classes have been studied, with inertia parameterized by means of Stokes number (Sk). It is found that inertial particles with lower Stokes number are expelled from vortex cores, and coherent voids encompass the local Kármán vortex cells. As Stokes number increases, a low velocity particle channel could be formed, which almost coincides with the results in the literature. Moreover, with the increase of Reynolds number, numerous irregular coherent voids are observed in the cylinder wake, and the high-speed particles follow the fluid flow closely when they are contained in the vortices. Although the centrifugal force of Kármán vortex cells significantly affects the dynamics of inertial particles, the fluid flow modulation is believed to be responsible for the distinctive particle dispersion patterns in the vortex streets. For particles with medium inertia, the two-way coupled modulation weakens the centrifugal effect of vortex structures on the particles. This trend declines with the increase of Reynolds number, and vanishes with light particles, while both two-way coupled modulation and the centrifugal effect of vortex structures are almost equally effective with heavy particles. The investigations contribute to a better understanding of the particle-laden flows in practical applications, which will benefit the optimized design of certain machinery and equipment for the industry.
{"title":"Dynamics and dispersion of inertial particles in circular cylinder wake flows: A two-way coupled Eulerian–Lagrangian approach","authors":"Dongming Chen, W. Yuan, Xiangdong Han","doi":"10.1142/s0217984924501239","DOIUrl":"https://doi.org/10.1142/s0217984924501239","url":null,"abstract":"In this paper, the motion of inertial particles in three-dimensional (3D) unsteady cylindrical wake flow is investigated by a two-way coupled Eulerian–Lagrangian approach. At different flow Reynolds numbers (Re), the corresponding striking dynamic property and dispersion mechanism of four particle classes have been studied, with inertia parameterized by means of Stokes number (Sk). It is found that inertial particles with lower Stokes number are expelled from vortex cores, and coherent voids encompass the local Kármán vortex cells. As Stokes number increases, a low velocity particle channel could be formed, which almost coincides with the results in the literature. Moreover, with the increase of Reynolds number, numerous irregular coherent voids are observed in the cylinder wake, and the high-speed particles follow the fluid flow closely when they are contained in the vortices. Although the centrifugal force of Kármán vortex cells significantly affects the dynamics of inertial particles, the fluid flow modulation is believed to be responsible for the distinctive particle dispersion patterns in the vortex streets. For particles with medium inertia, the two-way coupled modulation weakens the centrifugal effect of vortex structures on the particles. This trend declines with the increase of Reynolds number, and vanishes with light particles, while both two-way coupled modulation and the centrifugal effect of vortex structures are almost equally effective with heavy particles. The investigations contribute to a better understanding of the particle-laden flows in practical applications, which will benefit the optimized design of certain machinery and equipment for the industry.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"20 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139198990","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}
Pub Date : 2023-11-30DOI: 10.1142/s0217984924501069
Fengjuan Si, Wuyang Liu, Wei-Ping Hu
The electronic properties of the bulk CsPbI2Br and the passivation of CsPbI2Br (110) surface states are calculated by using first-principles calculations. It is found that the band gap of CsPbI2Br is 1.42[Formula: see text]eV by using the generalized gradient approximation of the Perdew–Burke–Ernzerhof function. The band gap is about 1.96[Formula: see text]eV by using the more complex Heyd–Scuseria–Ernzerhof mixed functional, which is closer to the experimental value of 1.92[Formula: see text]eV. The valence band top of CsPbI2Br bulk is mainly contributed by I-5p orbital and Br-4p orbital, and the conduction band bottom is mainly contributed by Pb-6p orbital. Through the calculation of CsPbI2Br (110) surface states passivated by Cl, F and H atoms, it is found that H atom has the best passivation effect. Its adsorption energy value fluctuates less, it is less sensitive to the adsorption position, and the adsorption is stable. Followed by F atom, its passivation effect is worse than that of H atom, but better than that of Cl atom. Although the passivation position has a certain influence on it, it has little effect. The Cl atom is most affected by the passivation position. The different positions of passivated atoms have a significant impact on adsorption energy. The adsorption stability is poor, and the passivation effect is also poor. Through analyzing the charge density difference and Bader charges, it is found that the H atom gets more electrons from the I atom, which is beneficial to passivate surface states. The electron-acquiring ability of the F atom is inferior to that of the H atom and is superior to that of the Cl atom. The electron-acquiring ability and passivation ability of Cl atom are the weakest among the three elements.
利用第一性原理计算了块体 CsPbI2Br 的电子特性以及 CsPbI2Br (110) 表面态的钝化。通过使用 Perdew-Burke-Ernzerhof 函数的广义梯度近似，发现 CsPbI2Br 的带隙为 1.42[公式：见正文]eV。使用更复杂的海德-斯库塞里亚-恩泽霍夫混合函数，带隙约为 1.96[式：见正文]eV，更接近实验值 1.92[式：见正文]eV。CsPbI2Br 体的价带顶部主要由 I-5p 轨道和 Br-4p 轨道贡献，导带底部主要由 Pb-6p 轨道贡献。通过计算被 Cl、F 和 H 原子钝化的 CsPbI2Br (110) 表面态，发现 H 原子的钝化效果最好。其吸附能值波动较小，对吸附位置不敏感，吸附稳定。其次是 F 原子，其钝化效果比 H 原子差，但比 Cl 原子好。虽然钝化位置对其有一定影响，但影响不大。Cl 原子受钝化位置的影响最大。钝化原子的不同位置对吸附能有很大影响。吸附稳定性差，钝化效果也差。通过分析电荷密度差和巴德电荷发现，H 原子从 I 原子获得的电子较多，有利于表面态的钝化。F 原子的获电子能力不如 H 原子，而优于 Cl 原子。在三种元素中，Cl 原子的电子获取能力和钝化能力最弱。
{"title":"First-principles study on the electronic properties of atom passivating CsPbI2Br surface","authors":"Fengjuan Si, Wuyang Liu, Wei-Ping Hu","doi":"10.1142/s0217984924501069","DOIUrl":"https://doi.org/10.1142/s0217984924501069","url":null,"abstract":"The electronic properties of the bulk CsPbI2Br and the passivation of CsPbI2Br (110) surface states are calculated by using first-principles calculations. It is found that the band gap of CsPbI2Br is 1.42[Formula: see text]eV by using the generalized gradient approximation of the Perdew–Burke–Ernzerhof function. The band gap is about 1.96[Formula: see text]eV by using the more complex Heyd–Scuseria–Ernzerhof mixed functional, which is closer to the experimental value of 1.92[Formula: see text]eV. The valence band top of CsPbI2Br bulk is mainly contributed by I-5p orbital and Br-4p orbital, and the conduction band bottom is mainly contributed by Pb-6p orbital. Through the calculation of CsPbI2Br (110) surface states passivated by Cl, F and H atoms, it is found that H atom has the best passivation effect. Its adsorption energy value fluctuates less, it is less sensitive to the adsorption position, and the adsorption is stable. Followed by F atom, its passivation effect is worse than that of H atom, but better than that of Cl atom. Although the passivation position has a certain influence on it, it has little effect. The Cl atom is most affected by the passivation position. The different positions of passivated atoms have a significant impact on adsorption energy. The adsorption stability is poor, and the passivation effect is also poor. Through analyzing the charge density difference and Bader charges, it is found that the H atom gets more electrons from the I atom, which is beneficial to passivate surface states. The electron-acquiring ability of the F atom is inferior to that of the H atom and is superior to that of the Cl atom. The electron-acquiring ability and passivation ability of Cl atom are the weakest among the three elements.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"148 ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139203297","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}
Pub Date : 2023-11-30DOI: 10.1142/s0217984923420113
P. Nithiananthi, G. Vignesh
The semiconductor-to-metal transition (SMT) due to excitons exciton mott transition (EMT) in GaAs/Al[Formula: see text]Ga[Formula: see text]As asymmetric double quantum well (ADQW) has been studied theoretically by tuning direct (DX) and indirect (IDX) exciton densities using variation technique combined with the Monte Carlo approximation. The interaction of the optically pumped exciton densities is accounted for through the Thomas–Fermi (TF) dielectric screening and compared with Hartree–Fock (HF) screening. The screening effects of IDX at the barrier regime have been accounted for through size-dependent screening. The important characteristics of EMT, such as (i). binding energy and (ii), diamagnetic susceptibility have been studied in both coupled ([Formula: see text]Å) and isolated ([Formula: see text]Å) regimes of ADQW. The effect of asymmetry on the EMT of DX (IDX) is significant only for [Formula: see text] in the case of the coupled regime of ADQW, which may be due to the dynamic tunneling mechanism. The impact of the screening among the exciton densities to bring out the avalanche breakdown of excitons at the critical concentration has been studied for different kinds of excitons.
{"title":"The influence of screening function on exciton mott transition in an asymmetric double quantum well","authors":"P. Nithiananthi, G. Vignesh","doi":"10.1142/s0217984923420113","DOIUrl":"https://doi.org/10.1142/s0217984923420113","url":null,"abstract":"The semiconductor-to-metal transition (SMT) due to excitons exciton mott transition (EMT) in GaAs/Al[Formula: see text]Ga[Formula: see text]As asymmetric double quantum well (ADQW) has been studied theoretically by tuning direct (DX) and indirect (IDX) exciton densities using variation technique combined with the Monte Carlo approximation. The interaction of the optically pumped exciton densities is accounted for through the Thomas–Fermi (TF) dielectric screening and compared with Hartree–Fock (HF) screening. The screening effects of IDX at the barrier regime have been accounted for through size-dependent screening. The important characteristics of EMT, such as (i). binding energy and (ii), diamagnetic susceptibility have been studied in both coupled ([Formula: see text]Å) and isolated ([Formula: see text]Å) regimes of ADQW. The effect of asymmetry on the EMT of DX (IDX) is significant only for [Formula: see text] in the case of the coupled regime of ADQW, which may be due to the dynamic tunneling mechanism. The impact of the screening among the exciton densities to bring out the avalanche breakdown of excitons at the critical concentration has been studied for different kinds of excitons.","PeriodicalId":18570,"journal":{"name":"Modern Physics Letters B","volume":"129 7","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139205453","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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