In this study,we present a comprehensive analysis of a modified Frolov black hole(BH)model that incorporates two types of topological defects,a global monopole(GM)and a cloud of strings(CS).This composite BH solution ...In this study,we present a comprehensive analysis of a modified Frolov black hole(BH)model that incorporates two types of topological defects,a global monopole(GM)and a cloud of strings(CS).This composite BH solution is examined from multiple theoretical perspectives to explore the impact of these modifications on the BH's geometric,thermodynamic and dynamical properties.We begin by studying the geometrical optics of the spacetime,focusing on the motion of null geodesics.Key features,such as the effective potential,photon sphere,the force acting on photons and the stability of circular photon orbits,are analyzed in detail.Our results show that the presence of GM and CS significantly affects the spacetime geometry and photon dynamics.In addition,the thermodynamic behavior of the modified BH is also investigated.We derive essential quantities such as the Hawking temperature and entropy,demonstrating how the inclusion of GM and CS leads to deviations from the standard thermodynamic relations observed in classical BH solutions.These deviations may offer valuable insights into quantum gravity and the role of topological defects in BH physics.Furthermore,we examine the BH shadow as an observational signature of the underlying geometry.Our analysis shows that the Frolov parameter tends to reduce the apparent size of the shadow,while the presence of topological defects,particularly GM and CS,enlarges it.In addition,we investigate the perturbative dynamics of the BH by studying both scalar(spin-0),fermionic(spin-1/2)and electromagnetic(spin-1)fields through the massless Klein-Gordon and Maxwell equations,respectively.Using the Wentzel-Kramers-Brillouin approximation,we compute the quasinormal modes(QNMs)for scalar and electromagnetic field perturbations.The results confirm the stability of the BH under small perturbations and show that the QNM frequencies and damping rates are strongly influenced by the Frolov parameter,electric charge,GM and CS.展开更多
We uncover the virtual monopoles underlying the nontrivial phases of the one-dimensional nonlinear excitations of rogue waves by extending the Dirac magnetic monopole theory to a complex plane. We find that the densit...We uncover the virtual monopoles underlying the nontrivial phases of the one-dimensional nonlinear excitations of rogue waves by extending the Dirac magnetic monopole theory to a complex plane. We find that the density zeros of the nonlinear waves on the extended complex plane constitute the virtual monopole fields with a quantized flux of elementary π. We then explain the exotic properties of rogue waves by means of a virtual monopole collision mechanism and find that the maximum amplitude amplification ratio and multiple phase steps of the high-order rogue waves are closely related to the number of their contained monopoles. These results open a new avenue for studying topological properties of nonlinear waves and provide an alternative way to understand their dynamics.展开更多
A thin compact broadband coplanarfed rectangular-ring monopole antenna parasiticallyloaded by three nested concentric rectangle rings and aπ-shaped stub is proposed suitable for modern communication needs.It has an o...A thin compact broadband coplanarfed rectangular-ring monopole antenna parasiticallyloaded by three nested concentric rectangle rings and aπ-shaped stub is proposed suitable for modern communication needs.It has an overall area of only 25 mm×6 mm(0.29λ_(0)×0.07λ_(0)at 3.5 GHz),which can be the base radiating element of the MIMO array,being easily integrated into any wireless device.Its measured(simulated)fractional bandwidth is 24.6%(31.6%)ranging from 3.25(3.09)to 4.16(4.25)GHz,being applicable to the 5G N48,N77,and N78 bands.Practical guidelines are also provided to make the proposed design operate on some other additional 5G bands(e.g.,N41 or N46)without compromising its overall size.As far as the radiation properties are concerned,the antenna with such small dimensions radiates nearly bidirectionally and omnidirectionally in the E-and H-plane,respectively,and has an average measured(simulated)peak realized gain of-0.1(1.8)dBi over the band of interest.The proposed antenna is wideband,physically small and relatively easy to manufacture,making it straightforward to integrate with the RF electronics in IoT sensors.展开更多
By regarding the Newton constant GNand cosmological constantΛas variables,in this paper we study the thermodynamics and phase transition of the Reissner-Nordstr o m anti-de Sitter(RN-Ad S)black hole with a global mon...By regarding the Newton constant GNand cosmological constantΛas variables,in this paper we study the thermodynamics and phase transition of the Reissner-Nordstr o m anti-de Sitter(RN-Ad S)black hole with a global monopole within the framework of Ad S/CFT correspondence.We find interesting critical phenomena and phase behavior in the(grand)canonical ensembles of fixed(Q,V,C),(Φ,V,C)and(Q,V,μ).When the other parameters are fixed,the free energy decreases with the global monopole increases.In the(Q,V,C)ensemble,the range of the unstable region decreases with the increase of the global monopole.In the(Φ,V,C)ensemble,whenΦ<Φc,the free energy appears as two branches,where the upper and lower branches correspond to low and high entropy,respectively.When(Q,V,μ)is fixed,a new zero-order phase transition occurs in the high-entropy phase and the low-entropy phase at certainμ-dependent temperatures.Whenμincreases to a certain value,this zero-order phase transition disappears.This certain value is negatively related to the magnitude of the global monopole.Finally,we find that p-V criticality does not appear with the change of global monopole.Therefore,it is important to note that the CFT states of charged black holes with global monopoles do not correspond to van der Waals fluids.Finally,we find that charged black holes with global monopoles can better reflect thermodynamic phase transitions and critical phenomena under the Ad S/CFT correspondence.By adjusting the change of the global monopole,the thermodynamic phase transition will also change.展开更多
The continuum quasiparticle random phase approximation(CQRPA),which includes the Skyrme interaction for both groundand excited-state calculations,is extended in a more consistent manner in the present work.The emergen...The continuum quasiparticle random phase approximation(CQRPA),which includes the Skyrme interaction for both groundand excited-state calculations,is extended in a more consistent manner in the present work.The emergence,evolution,and origin of pygmy monopole strengths along the even-even Ni isotopes were investigated carefully within consistent Skyrme HF+BCS and CQRPA models.The SLy5 Skyrme interaction and density-dependent zero-range pairing interactions were adopted in the calculations.No pygmy monopole strength was observed in^(70-78)Ni.However,pronounced pygmy monopole strengths are clearly observed in^(80-84)Ni,which are attributed mainly to the neutron excitations from weakly bound orbitals into the continuum.The neutron states involved in the pygmy monopole strength include 1 g_(9∕2),2 d_(5∕2),3 s_(1∕2)and 2 d_(3∕2).We suggest that more efforts from experimental investigations of pygmy monopole resonance should be made to confirm or disprove the predictions from models in the future.展开更多
In this work,we investigate the thermodynamic variables of a harmonic oscillator in a conical geometry metric.Moreover,we introduce an external field in the form of a Wu-Yang magnetic monopole(WYMM)and an inverse squa...In this work,we investigate the thermodynamic variables of a harmonic oscillator in a conical geometry metric.Moreover,we introduce an external field in the form of a Wu-Yang magnetic monopole(WYMM)and an inverse square potential into the system and analyze the results.Using an analytical approach,we obtain the energy level and study the thermodynamics at finite temperature.Our findings demonstrate that thermodynamic variables,except for the specific heat and entropy,are influenced by the topological parameters,the strength of the WYMM,and the inverse square potential.展开更多
We present the first numerical solution that corresponds to a pair of Cho–Maison monopoles and antimonopoles(MAPs) in the SU(2) × U(1) Weinberg–Salam(WS) theory.The monopoles are finitely separated,while each p...We present the first numerical solution that corresponds to a pair of Cho–Maison monopoles and antimonopoles(MAPs) in the SU(2) × U(1) Weinberg–Salam(WS) theory.The monopoles are finitely separated,while each pole carries a magnetic charge ±4π/e.The positive pole is situated in the upper hemisphere,whereas the negative pole is in the lower hemisphere.The Cho–Maison MAP is investigated for a range of Weinberg angles,0.4675≤ tan θ_(W)≤10,and Higgs self-coupling,0 ≤ β ≤ 1.7704.The magnetic dipole moment(μm) and pole separation(d_(z)) of the numerical solutions are calculated and analyzed.The total energy of the system,however,is infinite due to point singularities at the locations of monopoles.展开更多
Due to rapid growth in wireless communication technology,higher bandwidth requirement for advance telecommunication systems,capable of operating on two or higher bands with higher channel capacities and minimum distor...Due to rapid growth in wireless communication technology,higher bandwidth requirement for advance telecommunication systems,capable of operating on two or higher bands with higher channel capacities and minimum distortion losses is desired.In this paper,a compact Ultra-Wideband(UWB)V-shaped monopole antenna is presented.UWB response is achieved by modifying the ground plane with Chichen Itzia inspired rectangular staircase shape.The proposed V-shaped is designed by incorporating a rectangle,and an inverted isosceles triangle using FR4 substrate.The size of the antenna is 25 mm×26 mm×1.6 mm.The proposed V-shaped monopole antenna produces bandwidth response of 3 GHz Industrial,Scientific,and Medical(ISM),Worldwide Interoperability for Microwave Access(WiMAX),(IEEE 802.11/HIPERLAN band,5G sub 6 GHz)which with an additional square cut amplified the bandwidth response up to 8 GHz ranging from 3.1 GHz to 10.6 GHz attaining UWB defined by Federal Communications Commission(FCC)with a maximum gain of 3.83 dB.The antenna is designed in Ansys HFSS.Results for key performance parameters of the antenna are presented.The measured results are in good agreement with the simulated results.Due to flat gain,uniform group delay,omni directional radiation pattern characteristics and well-matched impedance,the proposed antenna is suitable for WiMAX,ISM and heterogeneous wireless systems.展开更多
A kind of compact ultra wideband （UWB） monopole antenna with dual-band notched function is presented.The proposed antenna,using ＂C＂ and ＂L＂ apertures embedded in the annular ring patch and ground patch,gets two ...A kind of compact ultra wideband （UWB） monopole antenna with dual-band notched function is presented.The proposed antenna,using ＂C＂ and ＂L＂ apertures embedded in the annular ring patch and ground patch,gets two bandnotched characteristics in WiMAX3.5 GHz and WLAN 5.5 GHz.The size of antenna is 24 mm × 36 mm × 1.6 mm.The simulation results show that waveband range of the antenna is 2.7-10.6 GHz for S11 ＜-10 dB and the band-notched wavebands are 3.2-3.8 GHz and 5.1-6 GHz.So it has miniaturization,ultra-band and band-notched characteristics.Meanwhile,the radition pattern,directivety and gain are perfect,which meets the practical need.展开更多
In this paper,a low cost,highly efficient and low profile monopole antenna for ultra-wideband(UWB)applications is presented.A new inverted triangular-shape structure possessing meander lines is designed to achieve a w...In this paper,a low cost,highly efficient and low profile monopole antenna for ultra-wideband(UWB)applications is presented.A new inverted triangular-shape structure possessing meander lines is designed to achieve a wideband response and high efficiency.To design the proposed structure,three steps are utilized to achieve an UWB response.The bandwidth of the proposed antenna is improved with changing meander lines parameters,miniaturization of the ground width and optimization of the feeding line.The measured and simulated frequency band ranges from 3.2 to 12 GHz,while the radiation patterns are measured at 4,5.3,6 and 8 GHz frequency bands.The overall volume of the proposed antenna is 26×25×1.6 mm^(3);whereas the FR4 material is used as a substrate with a relative permittivity and loss tangent of 4.3 and 0.025,correspondingly.The peak gain of 4 dB is achieved with a radiation efficiency of 80 to 98%for the entire wideband.Design modelling of proposed antenna is performed in ANSYS HFSS 13 software.A decent consistency between the simulated and measured results is accomplished which shows that the proposed antenna is a potential candidate for the UWB applications.展开更多
This paper derives the Hawking flux from the Schwarzschild black hole with a global monopole by using Robinson and Wilczek＇s method. Adopting a dimensional reduction technique, it can describe the effective quantum f...This paper derives the Hawking flux from the Schwarzschild black hole with a global monopole by using Robinson and Wilczek＇s method. Adopting a dimensional reduction technique, it can describe the effective quantum field in the （3 ＋ 1）-dimensional global monopole background by an infinite collection of the （1 ＋ 1）-dimensional massless fields if neglecting the ingoing modes near the horizon, where the gravitational anomaly can be cancelled by the （1 ＋ 1）- dimensional black body radiation at the Hawking temperature.展开更多
Based on the symmetry of the structure, a two-dimensional finite difference time domain （FDTD） method is used to analyze the sleeve monopole antenna on the infinite perfect conductor ground fed by a coaxial line. Th...Based on the symmetry of the structure, a two-dimensional finite difference time domain （FDTD） method is used to analyze the sleeve monopole antenna on the infinite perfect conductor ground fed by a coaxial line. The fields in time domain are then turned into frequency domain through the discrete Fourier Transform to compute the surface current distribution and the input impedance of the sleeve monopole antenna. The gain or pattern of the monopole antenna is also computed, employing the combination of the image theory and the near-to-far transformation in frequency domain. All the computed results agree very well with the results of other methods and measured ones, verifying the application of the FDTD method to analyze the sleeve monopole antennas. The voltage standing wave ratio （VSWR） of the sleeve monopole antennas with different heights and radii of the sleeve are checked to study the influence of the sleeve, which indicates that the height and the radius of the sleeve are both important to the impedance bandwidth of the sleeve monopole antennas.展开更多
Applying Parikh＇s quantum tunneling model, we study the quantum tunneling radiation of Reissne- Nordstrom de Sitter black hole with a global monopole. The result shows that the tunneling rates at the event horizon an...Applying Parikh＇s quantum tunneling model, we study the quantum tunneling radiation of Reissne- Nordstrom de Sitter black hole with a global monopole. The result shows that the tunneling rates at the event horizon and the cosmic horizon are related to Bekenstein-Hawking entropy if we take the energy conservation into consideration, and the true radiate spectrum is not precisely thermal.展开更多
We present the extended hydrogen atom and monopole-hydrogen atom theory through generalizing the usual hydrogen atom model and with a monopole model respectively, in which Y (sl(2) ) algebras are realized. We derive t...We present the extended hydrogen atom and monopole-hydrogen atom theory through generalizing the usual hydrogen atom model and with a monopole model respectively, in which Y (sl(2) ) algebras are realized. We derive the Hamiltonians of the two models based on the Y(sl(2) ) and the generalized Pauli equation. The energy spectra of the systems are also given in terms of Yangian algebra and quantum mechanics.展开更多
The paper analyzes the motion of electron in plasma antenna and the distribution of electromagnetic field power around the plasma antenna, and proposes a self-consistent model according to the structure of cylindrical...The paper analyzes the motion of electron in plasma antenna and the distribution of electromagnetic field power around the plasma antenna, and proposes a self-consistent model according to the structure of cylindrical monopole plasma antenna excited by surface wave;calculation of the model is based on Maxwell-Boltzmann equation and gas molecular dynamics theory. The calculation results show that this method can reflect the relationships between the external excitation power, gas pressure, discharge current and the characteristic of plasma. It is an accurate method to predicate and calculate the parameters of plasma antenna.展开更多
In this work, we re-assess a class of black hole solutions in a global monopole spacetime in the framework of an f(R)-gravity model. Our main line of investigation consists in considering a region close enough to the ...In this work, we re-assess a class of black hole solutions in a global monopole spacetime in the framework of an f(R)-gravity model. Our main line of investigation consists in considering a region close enough to the black hole, but such that the weak field approximation is still valid. The stability of the black hole is studied in terms of its thermodynamical properties, with the radial coordinate written as a power-law function with the status of the main factor underneath the stability of the model. We obtain the explicit expressions for the thermodynamical quantities of the black hole as functions of the event horizon, by considering both the Hawking and the local temperatures. The phase transitions that may occur in this system, including the Hawking-Page phase transition, are inspected with particular attention. We work out and contemplate a solution of special interest in which one of the parameters is related to the cosmological constant. Our main result sets out to establish a comparison between both the Hawking and the local formalisms for the black hole in the framework of the f(R)-gravity in the particular space-time adopted here.展开更多
In this paper a novel,compact,microstrip-fed,quad-band monopole antenna is presented for the application of Global System for Mobile communication(GSM 900),Worldwide Interoperability for Microwave Access(WiMAX)and Wir...In this paper a novel,compact,microstrip-fed,quad-band monopole antenna is presented for the application of Global System for Mobile communication(GSM 900),Worldwide Interoperability for Microwave Access(WiMAX)and Wireless Local Area Network(WLAN).The proposed antenna comprises of a sickle-shaped structure with four circular arc strips,and a modified rectangular ground plane.The four strips of the antenna are independently responsible for the four different resonant frequencies of the operating bands and can be tuned separately to control the radiation performance.The proposed quad-band antenna is designed to resonate at 940 MHz for GSM 900,2.5 and 3.5 GHz for WiMAX and 5.85 GHz for WLAN applications.At the four intended operating bands,the antenna exhibits impedance bandwidth of 60 MHz(905–965MHz),80 MHz(2.45–2.53 GHz),110 MHz(3.48–3.59 GHz)and 2.39 GHz(4.82–7.21 GHz),respectively.At the resonance frequency of the four bands,the gain of the proposed antenna is obtained as 4.2,2.5,1.7 and 1.9 dBi,respectively.A prototype of the designed antenna is fabricated and a good agreement between simulated and measured results is observed.Furthermore,the proposed antenna shows good radiation characteristics and gains at all the four operating bands.展开更多
Understanding the properties of nuclei near the double magic nucleus^(40)Ca is crucial for both nuclear theory and experiments.In this study,Ca isotopes were investigated using an extended pairing-plus-quadrupole mode...Understanding the properties of nuclei near the double magic nucleus^(40)Ca is crucial for both nuclear theory and experiments.In this study,Ca isotopes were investigated using an extended pairing-plus-quadrupole model with monopole corrections.The negative-parity states of^(44)Ca were coupled with the intruder orbital g_(9/2)at 4 MeV.The values of E_(4+)/E_(2+)agree well with experimental trend from^(42)Ca to^(50)Ca,considering monopole effects between νf_(7/2)and νp_(3/2)(νf_(5/2)).This monopole effect,determined from data of^(48)Ca and^(50)Ca,supports the proposed new nuclear magic number N=34 by predicting a high-energy 2^(+)state in^(54)Ca.展开更多
In this paper, by making use of Duan＇s topological current theory, the branch process of regular magnetic monopoles is discussed in detail. Regular magnetic monopoles are found generating or annihilating at the limit...In this paper, by making use of Duan＇s topological current theory, the branch process of regular magnetic monopoles is discussed in detail. Regular magnetic monopoles are found generating or annihilating at the limit point and encountering, splitting, or merging at the bifurcation point and the degenerate point systematically of the vector order parameter field φ（x）. Furthermore, it is also shown that when regular magnetic monopoles split or merge at the degenerate point of field function φ, the total topological charges of the regular magnetic monopoles are stilI unchanged.展开更多
基金financial support from EMU, TÜBİTAK, ANKOS and SCOAP3
文摘In this study,we present a comprehensive analysis of a modified Frolov black hole(BH)model that incorporates two types of topological defects,a global monopole(GM)and a cloud of strings(CS).This composite BH solution is examined from multiple theoretical perspectives to explore the impact of these modifications on the BH's geometric,thermodynamic and dynamical properties.We begin by studying the geometrical optics of the spacetime,focusing on the motion of null geodesics.Key features,such as the effective potential,photon sphere,the force acting on photons and the stability of circular photon orbits,are analyzed in detail.Our results show that the presence of GM and CS significantly affects the spacetime geometry and photon dynamics.In addition,the thermodynamic behavior of the modified BH is also investigated.We derive essential quantities such as the Hawking temperature and entropy,demonstrating how the inclusion of GM and CS leads to deviations from the standard thermodynamic relations observed in classical BH solutions.These deviations may offer valuable insights into quantum gravity and the role of topological defects in BH physics.Furthermore,we examine the BH shadow as an observational signature of the underlying geometry.Our analysis shows that the Frolov parameter tends to reduce the apparent size of the shadow,while the presence of topological defects,particularly GM and CS,enlarges it.In addition,we investigate the perturbative dynamics of the BH by studying both scalar(spin-0),fermionic(spin-1/2)and electromagnetic(spin-1)fields through the massless Klein-Gordon and Maxwell equations,respectively.Using the Wentzel-Kramers-Brillouin approximation,we compute the quasinormal modes(QNMs)for scalar and electromagnetic field perturbations.The results confirm the stability of the BH under small perturbations and show that the QNM frequencies and damping rates are strongly influenced by the Frolov parameter,electric charge,GM and CS.
基金supported by the National Natural Science Foundation of China (Grant Nos.12375005,12022513,and12235007)the National Safety Academic Fund(Grant No.U2330401)。
文摘We uncover the virtual monopoles underlying the nontrivial phases of the one-dimensional nonlinear excitations of rogue waves by extending the Dirac magnetic monopole theory to a complex plane. We find that the density zeros of the nonlinear waves on the extended complex plane constitute the virtual monopole fields with a quantized flux of elementary π. We then explain the exotic properties of rogue waves by means of a virtual monopole collision mechanism and find that the maximum amplitude amplification ratio and multiple phase steps of the high-order rogue waves are closely related to the number of their contained monopoles. These results open a new avenue for studying topological properties of nonlinear waves and provide an alternative way to understand their dynamics.
文摘A thin compact broadband coplanarfed rectangular-ring monopole antenna parasiticallyloaded by three nested concentric rectangle rings and aπ-shaped stub is proposed suitable for modern communication needs.It has an overall area of only 25 mm×6 mm(0.29λ_(0)×0.07λ_(0)at 3.5 GHz),which can be the base radiating element of the MIMO array,being easily integrated into any wireless device.Its measured(simulated)fractional bandwidth is 24.6%(31.6%)ranging from 3.25(3.09)to 4.16(4.25)GHz,being applicable to the 5G N48,N77,and N78 bands.Practical guidelines are also provided to make the proposed design operate on some other additional 5G bands(e.g.,N41 or N46)without compromising its overall size.As far as the radiation properties are concerned,the antenna with such small dimensions radiates nearly bidirectionally and omnidirectionally in the E-and H-plane,respectively,and has an average measured(simulated)peak realized gain of-0.1(1.8)dBi over the band of interest.The proposed antenna is wideband,physically small and relatively easy to manufacture,making it straightforward to integrate with the RF electronics in IoT sensors.
基金supported by the Natural Science Foundation of Sichuan Province(Grant No.2022NSFSC1833)the Sichuan Science and Technology Program(Grant No.2023ZYD0023)the Science Technology Department of Sichuan Province(Grant No.R21ZYZF0001)。
文摘By regarding the Newton constant GNand cosmological constantΛas variables,in this paper we study the thermodynamics and phase transition of the Reissner-Nordstr o m anti-de Sitter(RN-Ad S)black hole with a global monopole within the framework of Ad S/CFT correspondence.We find interesting critical phenomena and phase behavior in the(grand)canonical ensembles of fixed(Q,V,C),(Φ,V,C)and(Q,V,μ).When the other parameters are fixed,the free energy decreases with the global monopole increases.In the(Q,V,C)ensemble,the range of the unstable region decreases with the increase of the global monopole.In the(Φ,V,C)ensemble,whenΦ<Φc,the free energy appears as two branches,where the upper and lower branches correspond to low and high entropy,respectively.When(Q,V,μ)is fixed,a new zero-order phase transition occurs in the high-entropy phase and the low-entropy phase at certainμ-dependent temperatures.Whenμincreases to a certain value,this zero-order phase transition disappears.This certain value is negatively related to the magnitude of the global monopole.Finally,we find that p-V criticality does not appear with the change of global monopole.Therefore,it is important to note that the CFT states of charged black holes with global monopoles do not correspond to van der Waals fluids.Finally,we find that charged black holes with global monopoles can better reflect thermodynamic phase transitions and critical phenomena under the Ad S/CFT correspondence.By adjusting the change of the global monopole,the thermodynamic phase transition will also change.
基金partly supported by the National Natural Science Foundation of China(Nos.12275025,11975096,12135004,and 11961141004)the Fundamental Research Funds for the Central Universities(No.2020NTST06)。
文摘The continuum quasiparticle random phase approximation(CQRPA),which includes the Skyrme interaction for both groundand excited-state calculations,is extended in a more consistent manner in the present work.The emergence,evolution,and origin of pygmy monopole strengths along the even-even Ni isotopes were investigated carefully within consistent Skyrme HF+BCS and CQRPA models.The SLy5 Skyrme interaction and density-dependent zero-range pairing interactions were adopted in the calculations.No pygmy monopole strength was observed in^(70-78)Ni.However,pronounced pygmy monopole strengths are clearly observed in^(80-84)Ni,which are attributed mainly to the neutron excitations from weakly bound orbitals into the continuum.The neutron states involved in the pygmy monopole strength include 1 g_(9∕2),2 d_(5∕2),3 s_(1∕2)and 2 d_(3∕2).We suggest that more efforts from experimental investigations of pygmy monopole resonance should be made to confirm or disprove the predictions from models in the future.
文摘In this work,we investigate the thermodynamic variables of a harmonic oscillator in a conical geometry metric.Moreover,we introduce an external field in the form of a Wu-Yang magnetic monopole(WYMM)and an inverse square potential into the system and analyze the results.Using an analytical approach,we obtain the energy level and study the thermodynamics at finite temperature.Our findings demonstrate that thermodynamic variables,except for the specific heat and entropy,are influenced by the topological parameters,the strength of the WYMM,and the inverse square potential.
文摘We present the first numerical solution that corresponds to a pair of Cho–Maison monopoles and antimonopoles(MAPs) in the SU(2) × U(1) Weinberg–Salam(WS) theory.The monopoles are finitely separated,while each pole carries a magnetic charge ±4π/e.The positive pole is situated in the upper hemisphere,whereas the negative pole is in the lower hemisphere.The Cho–Maison MAP is investigated for a range of Weinberg angles,0.4675≤ tan θ_(W)≤10,and Higgs self-coupling,0 ≤ β ≤ 1.7704.The magnetic dipole moment(μm) and pole separation(d_(z)) of the numerical solutions are calculated and analyzed.The total energy of the system,however,is infinite due to point singularities at the locations of monopoles.
基金This work was supported by the Research Program through the National Research Foundation of Korea,NRF-2019R1A2C1005920,S.K.
文摘Due to rapid growth in wireless communication technology,higher bandwidth requirement for advance telecommunication systems,capable of operating on two or higher bands with higher channel capacities and minimum distortion losses is desired.In this paper,a compact Ultra-Wideband(UWB)V-shaped monopole antenna is presented.UWB response is achieved by modifying the ground plane with Chichen Itzia inspired rectangular staircase shape.The proposed V-shaped is designed by incorporating a rectangle,and an inverted isosceles triangle using FR4 substrate.The size of the antenna is 25 mm×26 mm×1.6 mm.The proposed V-shaped monopole antenna produces bandwidth response of 3 GHz Industrial,Scientific,and Medical(ISM),Worldwide Interoperability for Microwave Access(WiMAX),(IEEE 802.11/HIPERLAN band,5G sub 6 GHz)which with an additional square cut amplified the bandwidth response up to 8 GHz ranging from 3.1 GHz to 10.6 GHz attaining UWB defined by Federal Communications Commission(FCC)with a maximum gain of 3.83 dB.The antenna is designed in Ansys HFSS.Results for key performance parameters of the antenna are presented.The measured results are in good agreement with the simulated results.Due to flat gain,uniform group delay,omni directional radiation pattern characteristics and well-matched impedance,the proposed antenna is suitable for WiMAX,ISM and heterogeneous wireless systems.
文摘A kind of compact ultra wideband （UWB） monopole antenna with dual-band notched function is presented.The proposed antenna,using ＂C＂ and ＂L＂ apertures embedded in the annular ring patch and ground patch,gets two bandnotched characteristics in WiMAX3.5 GHz and WLAN 5.5 GHz.The size of antenna is 24 mm × 36 mm × 1.6 mm.The simulation results show that waveband range of the antenna is 2.7-10.6 GHz for S11 ＜-10 dB and the band-notched wavebands are 3.2-3.8 GHz and 5.1-6 GHz.So it has miniaturization,ultra-band and band-notched characteristics.Meanwhile,the radition pattern,directivety and gain are perfect,which meets the practical need.
基金the Research Program through the National Research Foundation of Korea,NRF-2019R1A2C1005920,S.K.
文摘In this paper,a low cost,highly efficient and low profile monopole antenna for ultra-wideband(UWB)applications is presented.A new inverted triangular-shape structure possessing meander lines is designed to achieve a wideband response and high efficiency.To design the proposed structure,three steps are utilized to achieve an UWB response.The bandwidth of the proposed antenna is improved with changing meander lines parameters,miniaturization of the ground width and optimization of the feeding line.The measured and simulated frequency band ranges from 3.2 to 12 GHz,while the radiation patterns are measured at 4,5.3,6 and 8 GHz frequency bands.The overall volume of the proposed antenna is 26×25×1.6 mm^(3);whereas the FR4 material is used as a substrate with a relative permittivity and loss tangent of 4.3 and 0.025,correspondingly.The peak gain of 4 dB is achieved with a radiation efficiency of 80 to 98%for the entire wideband.Design modelling of proposed antenna is performed in ANSYS HFSS 13 software.A decent consistency between the simulated and measured results is accomplished which shows that the proposed antenna is a potential candidate for the UWB applications.
基金Project supported by the National Natural Science Foundation of China(Grant No10675051)
文摘This paper derives the Hawking flux from the Schwarzschild black hole with a global monopole by using Robinson and Wilczek＇s method. Adopting a dimensional reduction technique, it can describe the effective quantum field in the （3 ＋ 1）-dimensional global monopole background by an infinite collection of the （1 ＋ 1）-dimensional massless fields if neglecting the ingoing modes near the horizon, where the gravitational anomaly can be cancelled by the （1 ＋ 1）- dimensional black body radiation at the Hawking temperature.
基金Supported by the National High Technology and Development Program of China(2001AA631050)
文摘Based on the symmetry of the structure, a two-dimensional finite difference time domain （FDTD） method is used to analyze the sleeve monopole antenna on the infinite perfect conductor ground fed by a coaxial line. The fields in time domain are then turned into frequency domain through the discrete Fourier Transform to compute the surface current distribution and the input impedance of the sleeve monopole antenna. The gain or pattern of the monopole antenna is also computed, employing the combination of the image theory and the near-to-far transformation in frequency domain. All the computed results agree very well with the results of other methods and measured ones, verifying the application of the FDTD method to analyze the sleeve monopole antennas. The voltage standing wave ratio （VSWR） of the sleeve monopole antennas with different heights and radii of the sleeve are checked to study the influence of the sleeve, which indicates that the height and the radius of the sleeve are both important to the impedance bandwidth of the sleeve monopole antennas.
基金The project supported by National Natural Science Foundation of China under Grant No. 10347008
文摘Applying Parikh＇s quantum tunneling model, we study the quantum tunneling radiation of Reissne- Nordstrom de Sitter black hole with a global monopole. The result shows that the tunneling rates at the event horizon and the cosmic horizon are related to Bekenstein-Hawking entropy if we take the energy conservation into consideration, and the true radiate spectrum is not precisely thermal.
文摘We present the extended hydrogen atom and monopole-hydrogen atom theory through generalizing the usual hydrogen atom model and with a monopole model respectively, in which Y (sl(2) ) algebras are realized. We derive the Hamiltonians of the two models based on the Y(sl(2) ) and the generalized Pauli equation. The energy spectra of the systems are also given in terms of Yangian algebra and quantum mechanics.
文摘The paper analyzes the motion of electron in plasma antenna and the distribution of electromagnetic field power around the plasma antenna, and proposes a self-consistent model according to the structure of cylindrical monopole plasma antenna excited by surface wave;calculation of the model is based on Maxwell-Boltzmann equation and gas molecular dynamics theory. The calculation results show that this method can reflect the relationships between the external excitation power, gas pressure, discharge current and the characteristic of plasma. It is an accurate method to predicate and calculate the parameters of plasma antenna.
基金CNPq-Brasil for his MSc Fellowship at the Instituto de Fsica of Universidade Federal Fluminense
文摘In this work, we re-assess a class of black hole solutions in a global monopole spacetime in the framework of an f(R)-gravity model. Our main line of investigation consists in considering a region close enough to the black hole, but such that the weak field approximation is still valid. The stability of the black hole is studied in terms of its thermodynamical properties, with the radial coordinate written as a power-law function with the status of the main factor underneath the stability of the model. We obtain the explicit expressions for the thermodynamical quantities of the black hole as functions of the event horizon, by considering both the Hawking and the local temperatures. The phase transitions that may occur in this system, including the Hawking-Page phase transition, are inspected with particular attention. We work out and contemplate a solution of special interest in which one of the parameters is related to the cosmological constant. Our main result sets out to establish a comparison between both the Hawking and the local formalisms for the black hole in the framework of the f(R)-gravity in the particular space-time adopted here.
基金The authors gracefully acknowledge the support provided by Visvesvaraya PhD scheme,Ministry of Electronics and Information Technology(MeiTy),Govt.of India,Grant No.PhD-MLA/4(29)/2015–16/01.
文摘In this paper a novel,compact,microstrip-fed,quad-band monopole antenna is presented for the application of Global System for Mobile communication(GSM 900),Worldwide Interoperability for Microwave Access(WiMAX)and Wireless Local Area Network(WLAN).The proposed antenna comprises of a sickle-shaped structure with four circular arc strips,and a modified rectangular ground plane.The four strips of the antenna are independently responsible for the four different resonant frequencies of the operating bands and can be tuned separately to control the radiation performance.The proposed quad-band antenna is designed to resonate at 940 MHz for GSM 900,2.5 and 3.5 GHz for WiMAX and 5.85 GHz for WLAN applications.At the four intended operating bands,the antenna exhibits impedance bandwidth of 60 MHz(905–965MHz),80 MHz(2.45–2.53 GHz),110 MHz(3.48–3.59 GHz)and 2.39 GHz(4.82–7.21 GHz),respectively.At the resonance frequency of the four bands,the gain of the proposed antenna is obtained as 4.2,2.5,1.7 and 1.9 dBi,respectively.A prototype of the designed antenna is fabricated and a good agreement between simulated and measured results is observed.Furthermore,the proposed antenna shows good radiation characteristics and gains at all the four operating bands.
基金supported by the National Natural Science Foundation of China(Nos.12175199,U2267205,12475124)the ZSTU intramural grant(22062267-Y)。
文摘Understanding the properties of nuclei near the double magic nucleus^(40)Ca is crucial for both nuclear theory and experiments.In this study,Ca isotopes were investigated using an extended pairing-plus-quadrupole model with monopole corrections.The negative-parity states of^(44)Ca were coupled with the intruder orbital g_(9/2)at 4 MeV.The values of E_(4+)/E_(2+)agree well with experimental trend from^(42)Ca to^(50)Ca,considering monopole effects between νf_(7/2)and νp_(3/2)(νf_(5/2)).This monopole effect,determined from data of^(48)Ca and^(50)Ca,supports the proposed new nuclear magic number N=34 by predicting a high-energy 2^(+)state in^(54)Ca.
基金supported by National Natural Science Foundation of Chinathe Cuiying Programm of Lanzhou University
文摘In this paper, by making use of Duan＇s topological current theory, the branch process of regular magnetic monopoles is discussed in detail. Regular magnetic monopoles are found generating or annihilating at the limit point and encountering, splitting, or merging at the bifurcation point and the degenerate point systematically of the vector order parameter field φ（x）. Furthermore, it is also shown that when regular magnetic monopoles split or merge at the degenerate point of field function φ, the total topological charges of the regular magnetic monopoles are stilI unchanged.
