A GaN/Si nanoheterojunction is prepared through growing Ga N nanocrystallites(nc-GaN) on a silicon nanoporous pillar array(Si-NPA) by a chemical vapor deposition(CVD) technique at a relatively low temperature. T...A GaN/Si nanoheterojunction is prepared through growing Ga N nanocrystallites(nc-GaN) on a silicon nanoporous pillar array(Si-NPA) by a chemical vapor deposition(CVD) technique at a relatively low temperature. The average size of nc-Ga N is determined to be ~10 nm. The spectral measurements disclose that the photoluminescence(PL) from GaN/SiNPA is composed of an ultraviolet(UV) band and a broad band spanned from UV to red region, with the feature that the latter band is similar to that of electroluminescence(EL). The electron transition from the energy levels of conduction band and, or, shallow donors to that of deep acceptors of Ga N is indicated to be responsible for both the broad-band PL and the EL luminescence. A study of the I-V characteristic shows that at a low forward bias, the current across the heterojunction is contact-limited while at a high forward bias it is bulk-limited, which follows the thermionic emission model and space-charge-limited current(SCLC) model, respectively. The bandgap offset analysis indicates that the carrier transport is dominated by electron injection from n-GaN into the p-Si-NPA, and the EL starts to appear only when holes begin to be injected from Si-NPA into GaN with biases higher than a threshold voltage.展开更多
Ni-Zn ferrite and Bi_(2)O_(3)composites were developed by the sol-gel method.The structural,magnetic,and dielectric properties were studied for all the prepared samples.X-ray diffraction(XRD)was performed to study the...Ni-Zn ferrite and Bi_(2)O_(3)composites were developed by the sol-gel method.The structural,magnetic,and dielectric properties were studied for all the prepared samples.X-ray diffraction(XRD)was performed to study the crystal structure.The results of field emission scanning electron microscopy(FE-SEM)showed that the addition of Bi_(2)O_(3)can increase the grain size of the Ni-Zn ferrite.Magnetic properties were analyzed by a hysteresis loop test and it was found that the saturation magnetization and coercivity decreased with the increase of Bi_(2)O_(3)ratio.In addition,the dielectric properties of the Ni-Zn ferrite were also improved with the addition of Bi_(2)O_(3).展开更多
A thin-flexible multiband terahertz metamaterial absorber (MA) has been investigated. Each unit cell of the MA consists of a simple metal structure, which includes the top metal resonator ring and the bottom metalli...A thin-flexible multiband terahertz metamaterial absorber (MA) has been investigated. Each unit cell of the MA consists of a simple metal structure, which includes the top metal resonator ring and the bottom metallic ground plane, separated by a thin-flexible dielectric spacer. Finite-difference time domain simulation indicates that this MA can achieve over 99% absorption at frequencies of 1.50 THz, 3.33 THz, and 5.40 THz by properly assembling the sandwiched structure. However, because of its asymmetric structure, the MA is polarization-sensitive and can tune the absorptivity of the second absorption peak by changing the incident polarization angle. The effect of the error of the structural parameters on the absorption efficiency is also carefully analyzed in detail to guide the fabrication. Moreover, the proposed MA exhibits high refractive-index sensing sensitivity, which has potential applications in multi-wavelength sensing in the terahertz region.展开更多
An evolutionary strategy-based error parameterization method that searches for the most ideal error adjustment factors was developed to obtain better assimilation results. Numerical experiments were designed using som...An evolutionary strategy-based error parameterization method that searches for the most ideal error adjustment factors was developed to obtain better assimilation results. Numerical experiments were designed using some classical nonlinear models (i.e., the Lorenz-63 model and the Lorenz-96 model). Crossover and mutation error adjustment factors of evolutionary strategy were investigated in four aspects: the initial conditions of the Lorenz model, ensemble sizes, observation covarianee, and the observation intervals. The search for error adjustment factors is usually performed using trial-and-error methods. To solve this difficult problem, a new data assimilation system coupled with genetic algorithms was developed. The method was tested in some simplified model frameworks, and the results are encouraging. The evolutionary strategy- based error handling methods performed robustly under both perfect and imperfect model scenarios in the Lorenz-96 model. However, the application of the methodology to more complex atmospheric or land surface models remains to be tested.展开更多
The assignment of the 1^(3)F_(4) meson nonet is phenomenologically analyzed in the framework of Regge phenomenology and meson-meson mixing.The mass of the partner of in the 1^(3)F_(4) meson nonet is determined to be 2...The assignment of the 1^(3)F_(4) meson nonet is phenomenologically analyzed in the framework of Regge phenomenology and meson-meson mixing.The mass of the partner of in the 1^(3)F_(4) meson nonet is determined to be 2167±27 MeV.The quarkonia content and the decay properties of the two isoscalar states of the 1^(3)F_(4) meson nonet are presented.The predictions can be tested by the BES-Ⅲ experiment in the near future.展开更多
At present, the research of single-photon is a hot topic, it has been widely applied in quantum measurement, quantum entanglement and quantum information. In this paper, we have proposed a new single photon theory, wh...At present, the research of single-photon is a hot topic, it has been widely applied in quantum measurement, quantum entanglement and quantum information. In this paper, we have proposed a new single photon theory, which is the vector potential A rotation at the vertical motion direction of photon, it can produce the microscopic electric field and magnetic field, and they satisfy the Maxwell equations. We have calculated photon spin, momentum, energy, and found there are left-handed and right-handed photon. In addition, we study the multi-photon theory and the dynamics theory between photons interaction. On this basis, we have further given the compound structures of electron, proton, neutron, neutrino, π meson, dark matter with the photon structural theory, and calculated their mass, charge and spin.展开更多
A method is established for measuring low energy γ-rays dose by using CMOS sensors without any X-/γ-ray converters. Gamma-ray source of241 Am and152Eu are used to test the system. Based on gray value, an analysis me...A method is established for measuring low energy γ-rays dose by using CMOS sensors without any X-/γ-ray converters. Gamma-ray source of241 Am and152Eu are used to test the system. Based on gray value, an analysis method is proposed to obtain the γ-ray dose. Cumulative dose is determined by correlating the gray value to the dose readings of standard dosimeters. The relationship between gray value and the cumulative dose of γ-rays are trained by using back propagation neural network with BFGS algorithm. After comparison, it shows that BFGS algorithm trainings are suitable for different γ-ray sources under higher error condition. These indicate the feasibility of measuring low energy γ-ray dose by using common CMOS image sensors.展开更多
Up to now, the excited charmed and bottom baryon states have still not been well studied experimentally or theoretically. In this paper, we predict the mass of Ωb, the only L=0 baryon state which has not been observe...Up to now, the excited charmed and bottom baryon states have still not been well studied experimentally or theoretically. In this paper, we predict the mass of Ωb, the only L=0 baryon state which has not been observed, to be 6069.2 MeV. The spectra of charmed and bottom baryons with the orbital angular momentum L= 1 are studied in two popular constituent quark models, the Goldstone boson exchange (GBE) model and the one gluon exchange (OGE) hyperfine interaction model. Inserting the latest experimental data from the "Review of Particle Physics", we find that in the GBE model, there exist some multiplets (∑c(b), ≡c(b) and Ωc(b)) in which the total spin of the three quarks in their lowest energy states is 3/2, but in the OGE model there is no such phenomenon. This is the most important difference between the GBE and OGE models. These results can be tested in the near future. We suggest more efforts to study the excited charmed and bottom baryons both theoretically and experimentally, not only for the abundance of baryon spectra, but also for determining which hyperfine interaction model best describes nature.展开更多
La2/3Sr1/3MnO3 films with (110) preferred orientation were deposited on Si (100) substrate without any buffer layer by pulsed laser deposition technique. Effect of oxygen pressure on orientation, surface morpholog...La2/3Sr1/3MnO3 films with (110) preferred orientation were deposited on Si (100) substrate without any buffer layer by pulsed laser deposition technique. Effect of oxygen pressure on orientation, surface morphology, and electrical transport properties were investigated. The film deposited at 10 Pa presented (110) preferred orientation with the best crystalline quality, the largest grain size, and the smallest roughness. The (110) oriented film presented higher metal-insulator transition temperature, and the lower resis- tivity than that of the samples without preferred orientation.展开更多
Ultracompact dark matter minihalos (UCMHs) would be formed during the early universe if there were large density perturbations. If dark matter can decay into particles described by the standard model, such as neutri...Ultracompact dark matter minihalos (UCMHs) would be formed during the early universe if there were large density perturbations. If dark matter can decay into particles described by the standard model, such as neutrinos, these objects would become potential astrophysical sources of emission which could be detected by in- struments such as IceCube. In this paper, we investigate neutrino signals from nearby UCMHs due to gravitino dark matter decay and compare these signals with the back- ground neutrino flux which is mainly from the atmosphere to obtain constraints on the abundance of UCMHs.展开更多
Using CALIPSO (cloud-aerosol lidar and infrared pathfinder satellite observation) vertical observation data during haze periods from January 2007 to December 2008, we analyzed differences in aerosol char- acteristic...Using CALIPSO (cloud-aerosol lidar and infrared pathfinder satellite observation) vertical observation data during haze periods from January 2007 to December 2008, we analyzed differences in aerosol char- acteristics near the surface, as well as in the middle troposphere between the Beijing-Tianjin-Hebei metropolitan region (Area A) and the Yangtze River Delta region (Area B) in China. One significant dif- ference was that haze pollution in Area A was related to local and non-local aerosols, while in Area B it was related to local anthropogenic sources. In all seasons apart from autumn, aerosol pollution in Area A was more severe than in Area B, both near the surface and at higher altitudes, In Area A, non-spherical aerosols were dominant from 0 to 4 km in spring, summer, and winter; while in autumn, there were con- siderably high numbers of non-spherical aerosols below 0.5 km, and near-spherical aerosols from 0.5 to 4 km. In Area B, both near-spherical and non-spherical aerosols were common in all seasons. Moreover, aerosols with attenuated color ratios of 0-0.2 were more common in all seasons in Area A than in Area B, indicating that fine particle pollution in Area A was more serious than in Area B. Finally, relatively large aerosols linked to gravity settling appeared more frequently near the surface in Area A than in Area B.展开更多
The masses of some orbitally and radially excited heavy-light mesons are calculated in Regge phenomenol- ogy. The results are in reasonable agreement with the experimental data and those given in many other theoretica...The masses of some orbitally and radially excited heavy-light mesons are calculated in Regge phenomenol- ogy. The results are in reasonable agreement with the experimental data and those given in many other theoretical approaches. Based on the calculation, we suggest that the recently observed D(2550), D(2600) and D(2760) can be assigned as the charmed members of the 21S0, 23S1 and 13D1 multiplets, respectively. D'1(2700) may be assigned as the charm-strange member of the 23S1 state. The results may be helpful in understanding the nature of current and future experimentally observed heavy-light mesons.展开更多
The spin is an important property of a particle. Although it is unlikely, there is still a possibility that two particles with different spins share similar masses. In this paper, we propose a method to probe this kin...The spin is an important property of a particle. Although it is unlikely, there is still a possibility that two particles with different spins share similar masses. In this paper, we propose a method to probe this kind of mass degeneracy of particles with different spins. We use the cascade decay B^+ →X(3872)K^+, X(3872)→D^+D^- to illustrate our method. It can be seen that the possible mass degeneracy of X(3872) can lead to interesting behavior in the corresponding cascade decay.展开更多
The existence and properties of intrinsic localized spin-wave modes in a ferromagnetic XXZ spin chain with Dzyaloshinsky–Moriya interaction are investigated analytically in the semiclassical limit. The model Hamilton...The existence and properties of intrinsic localized spin-wave modes in a ferromagnetic XXZ spin chain with Dzyaloshinsky–Moriya interaction are investigated analytically in the semiclassical limit. The model Hamiltonian is quantized by introducing the Dyson–Maleev transformation and the coherent state representation is chosen as the basic representation of the system. By making use of the method of multiple scales combined with a quasidiscreteness approximation, the equation of motion for the coherent-state amplitude is reduced to the nonlinear Schr¨odinger equation.It is shown that a bright intrinsic localized spin-wave mode whose eigenfrequency lies below the bottom of the magnon frequency band can exist in the ferromagnetic system. We also show that the system can produce a dark intrinsic localized spin-wave mode, i.e., nonpropagating kink, whose eigenfrequency is below the upper of the magnon frequency band. In addition, we find that the introduction of the Dzyaloshinsky–Moriya interaction changes wave numbers in the Brillouin-zone corresponding to the appearance of intrinsic localized spin-wave modes.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61176044)
文摘A GaN/Si nanoheterojunction is prepared through growing Ga N nanocrystallites(nc-GaN) on a silicon nanoporous pillar array(Si-NPA) by a chemical vapor deposition(CVD) technique at a relatively low temperature. The average size of nc-Ga N is determined to be ~10 nm. The spectral measurements disclose that the photoluminescence(PL) from GaN/SiNPA is composed of an ultraviolet(UV) band and a broad band spanned from UV to red region, with the feature that the latter band is similar to that of electroluminescence(EL). The electron transition from the energy levels of conduction band and, or, shallow donors to that of deep acceptors of Ga N is indicated to be responsible for both the broad-band PL and the EL luminescence. A study of the I-V characteristic shows that at a low forward bias, the current across the heterojunction is contact-limited while at a high forward bias it is bulk-limited, which follows the thermionic emission model and space-charge-limited current(SCLC) model, respectively. The bandgap offset analysis indicates that the carrier transport is dominated by electron injection from n-GaN into the p-Si-NPA, and the EL starts to appear only when holes begin to be injected from Si-NPA into GaN with biases higher than a threshold voltage.
基金Project supported by the National Natural Science Foundation of China(Grant No.11804006)the Natural Science Foundation of Shanxi Province,China(Grant Nos.201901D111126 and 201901D111117).
文摘Ni-Zn ferrite and Bi_(2)O_(3)composites were developed by the sol-gel method.The structural,magnetic,and dielectric properties were studied for all the prepared samples.X-ray diffraction(XRD)was performed to study the crystal structure.The results of field emission scanning electron microscopy(FE-SEM)showed that the addition of Bi_(2)O_(3)can increase the grain size of the Ni-Zn ferrite.Magnetic properties were analyzed by a hysteresis loop test and it was found that the saturation magnetization and coercivity decreased with the increase of Bi_(2)O_(3)ratio.In addition,the dielectric properties of the Ni-Zn ferrite were also improved with the addition of Bi_(2)O_(3).
基金Project supported by the National Natural Science Foundation of China(Grant No.11504006)the Key Scientific Research Project of Higher Education of Henan Province,China(Grant No.15A140002)the Science and Technology Planning Project of Henan Province,China(Grant No.142300410366)
文摘A thin-flexible multiband terahertz metamaterial absorber (MA) has been investigated. Each unit cell of the MA consists of a simple metal structure, which includes the top metal resonator ring and the bottom metallic ground plane, separated by a thin-flexible dielectric spacer. Finite-difference time domain simulation indicates that this MA can achieve over 99% absorption at frequencies of 1.50 THz, 3.33 THz, and 5.40 THz by properly assembling the sandwiched structure. However, because of its asymmetric structure, the MA is polarization-sensitive and can tune the absorptivity of the second absorption peak by changing the incident polarization angle. The effect of the error of the structural parameters on the absorption efficiency is also carefully analyzed in detail to guide the fabrication. Moreover, the proposed MA exhibits high refractive-index sensing sensitivity, which has potential applications in multi-wavelength sensing in the terahertz region.
基金supported by the NSFC (National Science Foundation of China) project (Grant Nos. 41061038 and 40925004)project "Land Surface Modeling and Data Assimilation Research" (Grant No. 2009AA122104) from the National High Technology ResearchOne Hundred Person Project of the Chinese Academy of Sciences "Multi-sensor Hydrological Data Assimilation for Key Hydrological Variables in Cold and Arid Regions" (Grant No. 29Y127D01)
文摘An evolutionary strategy-based error parameterization method that searches for the most ideal error adjustment factors was developed to obtain better assimilation results. Numerical experiments were designed using some classical nonlinear models (i.e., the Lorenz-63 model and the Lorenz-96 model). Crossover and mutation error adjustment factors of evolutionary strategy were investigated in four aspects: the initial conditions of the Lorenz model, ensemble sizes, observation covarianee, and the observation intervals. The search for error adjustment factors is usually performed using trial-and-error methods. To solve this difficult problem, a new data assimilation system coupled with genetic algorithms was developed. The method was tested in some simplified model frameworks, and the results are encouraging. The evolutionary strategy- based error handling methods performed robustly under both perfect and imperfect model scenarios in the Lorenz-96 model. However, the application of the methodology to more complex atmospheric or land surface models remains to be tested.
基金Supported in part by the National Natural Science Foundation of China under Grant Nos 10975018,11147197the Key Project of Scientific and Technological Research of the Education Department of Henan Province under Grant No 12B140001。
文摘The assignment of the 1^(3)F_(4) meson nonet is phenomenologically analyzed in the framework of Regge phenomenology and meson-meson mixing.The mass of the partner of in the 1^(3)F_(4) meson nonet is determined to be 2167±27 MeV.The quarkonia content and the decay properties of the two isoscalar states of the 1^(3)F_(4) meson nonet are presented.The predictions can be tested by the BES-Ⅲ experiment in the near future.
文摘At present, the research of single-photon is a hot topic, it has been widely applied in quantum measurement, quantum entanglement and quantum information. In this paper, we have proposed a new single photon theory, which is the vector potential A rotation at the vertical motion direction of photon, it can produce the microscopic electric field and magnetic field, and they satisfy the Maxwell equations. We have calculated photon spin, momentum, energy, and found there are left-handed and right-handed photon. In addition, we study the multi-photon theory and the dynamics theory between photons interaction. On this basis, we have further given the compound structures of electron, proton, neutron, neutrino, π meson, dark matter with the photon structural theory, and calculated their mass, charge and spin.
基金Supported by National Natural Science Foundation of China(No.10905017)the Science and Technology Innovation Team Support Plan in Henan Province(No.13IRTSTHN016)
文摘A method is established for measuring low energy γ-rays dose by using CMOS sensors without any X-/γ-ray converters. Gamma-ray source of241 Am and152Eu are used to test the system. Based on gray value, an analysis method is proposed to obtain the γ-ray dose. Cumulative dose is determined by correlating the gray value to the dose readings of standard dosimeters. The relationship between gray value and the cumulative dose of γ-rays are trained by using back propagation neural network with BFGS algorithm. After comparison, it shows that BFGS algorithm trainings are suitable for different γ-ray sources under higher error condition. These indicate the feasibility of measuring low energy γ-ray dose by using common CMOS image sensors.
基金Supported by National Natural Science Foundation of China(11175020,11575023,U1204115)
文摘Up to now, the excited charmed and bottom baryon states have still not been well studied experimentally or theoretically. In this paper, we predict the mass of Ωb, the only L=0 baryon state which has not been observed, to be 6069.2 MeV. The spectra of charmed and bottom baryons with the orbital angular momentum L= 1 are studied in two popular constituent quark models, the Goldstone boson exchange (GBE) model and the one gluon exchange (OGE) hyperfine interaction model. Inserting the latest experimental data from the "Review of Particle Physics", we find that in the GBE model, there exist some multiplets (∑c(b), ≡c(b) and Ωc(b)) in which the total spin of the three quarks in their lowest energy states is 3/2, but in the OGE model there is no such phenomenon. This is the most important difference between the GBE and OGE models. These results can be tested in the near future. We suggest more efforts to study the excited charmed and bottom baryons both theoretically and experimentally, not only for the abundance of baryon spectra, but also for determining which hyperfine interaction model best describes nature.
基金supported by National Natural Science Foundation of China (51002013,11174201)Natural Science Foundation of Beijing Municipal (2122007)Science and Technology Research Projects of Education Department of Henan province (13B430895)
文摘La2/3Sr1/3MnO3 films with (110) preferred orientation were deposited on Si (100) substrate without any buffer layer by pulsed laser deposition technique. Effect of oxygen pressure on orientation, surface morphology, and electrical transport properties were investigated. The film deposited at 10 Pa presented (110) preferred orientation with the best crystalline quality, the largest grain size, and the smallest roughness. The (110) oriented film presented higher metal-insulator transition temperature, and the lower resis- tivity than that of the samples without preferred orientation.
基金Supported by the National Natural Science Foundation of China
文摘Ultracompact dark matter minihalos (UCMHs) would be formed during the early universe if there were large density perturbations. If dark matter can decay into particles described by the standard model, such as neutrinos, these objects would become potential astrophysical sources of emission which could be detected by in- struments such as IceCube. In this paper, we investigate neutrino signals from nearby UCMHs due to gravitino dark matter decay and compare these signals with the back- ground neutrino flux which is mainly from the atmosphere to obtain constraints on the abundance of UCMHs.
文摘Using CALIPSO (cloud-aerosol lidar and infrared pathfinder satellite observation) vertical observation data during haze periods from January 2007 to December 2008, we analyzed differences in aerosol char- acteristics near the surface, as well as in the middle troposphere between the Beijing-Tianjin-Hebei metropolitan region (Area A) and the Yangtze River Delta region (Area B) in China. One significant dif- ference was that haze pollution in Area A was related to local and non-local aerosols, while in Area B it was related to local anthropogenic sources. In all seasons apart from autumn, aerosol pollution in Area A was more severe than in Area B, both near the surface and at higher altitudes, In Area A, non-spherical aerosols were dominant from 0 to 4 km in spring, summer, and winter; while in autumn, there were con- siderably high numbers of non-spherical aerosols below 0.5 km, and near-spherical aerosols from 0.5 to 4 km. In Area B, both near-spherical and non-spherical aerosols were common in all seasons. Moreover, aerosols with attenuated color ratios of 0-0.2 were more common in all seasons in Area A than in Area B, indicating that fine particle pollution in Area A was more serious than in Area B. Finally, relatively large aerosols linked to gravity settling appeared more frequently near the surface in Area A than in Area B.
基金Supported by National Natural Science Foundation of China (10975018, 11147197, 11104072, U1204115)Key Project of Scientific and Technological Research of Education Department of Henan Province (12B140001)
文摘The masses of some orbitally and radially excited heavy-light mesons are calculated in Regge phenomenol- ogy. The results are in reasonable agreement with the experimental data and those given in many other theoretical approaches. Based on the calculation, we suggest that the recently observed D(2550), D(2600) and D(2760) can be assigned as the charmed members of the 21S0, 23S1 and 13D1 multiplets, respectively. D'1(2700) may be assigned as the charm-strange member of the 23S1 state. The results may be helpful in understanding the nature of current and future experimentally observed heavy-light mesons.
基金Supported by National Natural Science Foundation of China(11347124,11147003,U1204115)Doctoral Scientific Research Foundation of USC,and Innovation Team of Nuclear and Particle Physics of USC
文摘The spin is an important property of a particle. Although it is unlikely, there is still a possibility that two particles with different spins share similar masses. In this paper, we propose a method to probe this kind of mass degeneracy of particles with different spins. We use the cascade decay B^+ →X(3872)K^+, X(3872)→D^+D^- to illustrate our method. It can be seen that the possible mass degeneracy of X(3872) can lead to interesting behavior in the corresponding cascade decay.
基金Supported by the National Natural Science Foundation of China under Grant No.11264012Hunan Provincial Innovation Foundation for Postgraduate under Grant No.CX2013B264
文摘The existence and properties of intrinsic localized spin-wave modes in a ferromagnetic XXZ spin chain with Dzyaloshinsky–Moriya interaction are investigated analytically in the semiclassical limit. The model Hamiltonian is quantized by introducing the Dyson–Maleev transformation and the coherent state representation is chosen as the basic representation of the system. By making use of the method of multiple scales combined with a quasidiscreteness approximation, the equation of motion for the coherent-state amplitude is reduced to the nonlinear Schr¨odinger equation.It is shown that a bright intrinsic localized spin-wave mode whose eigenfrequency lies below the bottom of the magnon frequency band can exist in the ferromagnetic system. We also show that the system can produce a dark intrinsic localized spin-wave mode, i.e., nonpropagating kink, whose eigenfrequency is below the upper of the magnon frequency band. In addition, we find that the introduction of the Dzyaloshinsky–Moriya interaction changes wave numbers in the Brillouin-zone corresponding to the appearance of intrinsic localized spin-wave modes.
基金supported by the National Natural Science Foundation of China(11047108)the Program for Excellent Younger teachers in the universities in Henan Province of China,the Program for the Research Project of Basic and Frontier Technology of Henan Province(112300410183)the Program for Henan Postdoctoral Science Foundation,and the Foundation of Henan Educational Committee(2011B140002,14A140016,14A430029 and 14B140003)