bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of high-order harmonic generation in crystals exposed to laser fields
Authors: Guan Zhong  , Li Wei  , Wang Guo-Li  , Zhou Xiao-Xin  ,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

Crystal structures are very different from the atomic structure in the gaseous state, so the high-order harmonic generation (HHG) from the crystal irradiated by an in intense laser is also different from that of an atom exposed to a strong laser field. By simulating the dynamics of a single active electron in periodic potentials based on the expansion method of the basis functions, we study the HHG in crystals and find, in certain wave lengths and intensity of the laser, that solid harmonic generation exhibits the characteristics of double plateaus. After analyzing the induced electric current of laser field, which is the source of HHG in the crystal, we find that the first plateau of HHG arises chiefly from the electric current between the lowest conduction band and the valence band (electron-hole recollision), and the second plateau is predominantly due to electric current between higher conduction bands and the valence band (electron-hole recollision). The cutoff energies of the two plateaus vary approximately linearly with the laser field strength. Furthermore, by considering the crystal driven by the few-cycle laser pulse, the cutoff energy of the second plateau changes monotonously with carrier-envelope phases. Based on this phenomenon, it can be a way to measure the carrier-envelope phases of the few-cycle laser pulse. Finally, we study further the HHG from crystals driven by the chirped laser and find that it has a great influence on the HHG, and the second plateau of HHG is sensitive to the chirp parameter. According to this phenomenon, we propose a novel way that is capable of greatly improving the emission efficiency of the second plateau by changing the chirp parameter of the driving laser.
Research on coherent anti-Stokes Raman scattering microscopy
Authors: Liu Shuang-Long  , Liu Wei  , Chen Dan-Ni  , Qu Jun-Le  , Niu Han-Ben  ,   Key Laboratory of Optoelectronics Devices and Systems of Ministry of Education and Guangdong Province, College of Opto-Electronic Engineering, Shenzhen University, Shenzhen 518060, China
Published: December 2020

In this paper, we analyze the process of coherent anti-Stokes Raman scattering (CARS) based on quantum theory and set up a traditional point-scanning CARS microscope. With this microscope, high-contrast images of polystyrene microspheres are obtained. By scanning polystyrene beads with 110 nm diameter, we reconstruct the point spread faction (PSF) of the system. And the full width at half maximum (FWHM) of the PSF shows a lateral resolution about 600 nm, which is larger than the theoretical value (～ 300 nm). Therefore, we propose several resolution-improvement approaches, which lay a strong foundation for the realization of nano-CARS microscopy.
Research of the influence of non-spherical ellipsoid particle parameter variation on polarization characteristic of light
Authors: Zhang Su  , Peng Jie  , Zhan Jun-Tong  , Fu Qiang  , Duan Jin  , Jiang Hui-Lin  ,   Fundamental Science on Space-Ground Laser Communication Technology Laboratory, Changchun University of Science and Technology, Changchun 130022, China;,   School of Electronics and Information Engineering, Changchun University of Science and Technology, Changchun 130022, China
Published: December 2020

There are many non-spherical particles in the sand-dust and carbonaceous environment of the natural world, but this kind of particles are in most cases approximated by the spheres in the description of the transmission process, which cannot reflect the actual state of the transmission through the particles. For this reason, on the basis of polarization characteristic of spherical particles, a further research is made on the polarization characteristic with different refractive index, effective radius, particle shape, and other parameters of ellipsoid particles. When the non-polarized light is used as the incident light, the T-matrix method is applied to the simulation of the transmission process of the non-spherical particles, and the power-law size distribution is used to describe the size distribution condition of the particles, which is the most effective method to show the whole process of light scattering through non-spherical particles. With this method, the polarization characteristic after the transmission of the ellipsoid particles and the polarization differences between the ellipsoid and spherical particles can be obtained, and at the same time the examples of the sand-dust, marine and carbonaceous aerosols are given to show the validity of the results. Simulation results show that the smaller the real part of the refractive index and the larger the image nary part of the refractive index, the less obvious the polarization character differences between the ellipsoid and spherical particles are. When the effective radius of particle increases, the DOP (degree of polarization) variation of the spherical particles is more obvious than the non-spherical particles, and the maximum values are at the positions of the scattering angles 150 and 120 respectively. When the particle shape is different, the differences between the ellipsoid at diverse vertical-to-horizontal ratio and spherical particles are not obvious if the scattering angle is less than 60, and when the vertical-to-horizontal ratio of the ellipsoid particle is reciprocal, the polarization character of the two kinds of particles becomes the same. Through the analysis above, in the process of transmission, in most circumstances the ellipsoid particles cannot be approximated by spherical particles for computation, and the parameters of the refractive index, effective radius, shape of the ellipsoid particles can all influence the polarization character.
Influence of defect states on proton conductivity of Y-doped BaZrO3
Authors: Yang Yi-Bin  , Gong Yu  , Liu Cai-Lin  , Luo Yang-Ming  , Chen Ping  ,   School of Materials Sicence and Engineering, Southwest University of Science and Technology, Mianyang 621010, China;,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Nuclear energy is a promising new energy to solve energy crisis. Separation and purification of hydrogen isotopes play an important role in the developing and utilizing of nuclear energy. BaZrO3-based oxide is an effective material for the separation and purification of hydrogen isotopes. In this paper, a series of BaZr1-xYxO3- (0 x 0.3) are synthesized by high-temperature solid state reaction method. The raw materials are calcined at 1200 ℃ for 5 h in air. Then the calcined powder is consolidated by an isostatic press and sintered at 1500 ℃ for 48 h in air, using a furnace equipped with aluminum oxide heater. Phase purity and phase structure of the obtained BaZr1-xYxO3- are analyzed by XRD. Results show that the structures of the BaZr1-xYxO3- are consistent with the BaZrO3 diffraction pattern (JCPDS 06-399). The Y ions are already incorporated into the lattice of BaZrO3, and the maximum doping concentration of Y rangs from 0.24 to 0.26. Besides, the proton conductivity of Y-doped BaZrO3 is determined under hydrogen atmosphere by the electrochemical impedance spectroscopy (EIS). Experiments show that the BaZr1-xYxO3- with 20 mol% Y has the highest conductivity of 0.0015 S/cm at 600 ℃ which is higher than that of the BaZrO3 matrix material by two orders of magnitude. As the concentration of Y increases, the strain in the crystal structure of BaZrO3 increases, which may be created by the defect of Y-doped BaZrO3. In order to reveal the mechanism of proton conduction in Y-doped BaZrO3, the influence of defect types on proton conduction is also investigated via photoluminescence (PL) and thermoluminescence (TL). For the BaZrO3 matrix, an asymmetrical broad emission peak at 350 to 650 nm occurs in PL with an excitation light of 334 nm. Analysis of Gaussian decomposition shows that the asymmetrical broad emission peak is created by two kinds of different oxygen vacancies (Vo..), which are beneficial to proton conduction. Interestingly, when BaZrO3 is doped with Y, a new emission peak P1 at 388 nm appears owing to the negatively charged YZr' of proton-trapping-type defects, which is harmful to the proton conduction in general. TL analysis shows that the number of YZr' increases and the depth of the trap reduce, as the Y concentration increases in BaZr1-xYxO3- (x=0, 0.05, 0.1, 0.2). Although the YZr' is noxious for the proton conduction, the proton conductivity of BaZr1-xYxO3- (x=0, 0.05, 0.1, 0.2) can be improved via the increase of the release ability of proton trapping as the depth of trap is reduced.
Dynamics of polarons in organic conjugated polymers with impurity ions
Authors: Liu Jun-Juan  , Wei Zeng-Jiang  , Chang Hong  , Zhang Ya-Lin  , Di Bing  ,   Hebei Normal University Affiliated College of Nationalities, Shijiazhuang 050091, China;,   Shijiazhuang Institute of Technology, Career Academy, Shijiazhuang 050020, China;,   College of Physics, Hebei Normal University, Shijiazhuang 050024, China
Published: December 2020

Based on the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model, and using the molecular dynamics method, we discuss the dynamics of electron and hole polarons under the influence of impurity potentials and the distance between impurities. Under an external electric field, the electron or hole polaron can move along the polymer chain with a steady velocity. When the polarons collide with impurities, the velocities of the polarons would be affected by the impurity potentials and the distance between the impurities. 1) Firstly, at a fixed impurity potential strength, the average velocities of the electron and hole polarons as a function of the distance (2-16 times the lattice constant) between impurities have been discussed in polymers. It is found that the average velocities of the electron and hole polarons increase with increasing distance between impurities. It is worth noting that the average velocities of the electron polarons are greater than those of the hole polarons, which results from the fact that the electron and hole polarons have different coulomb interactions with the impurity ions. That is to say, the coulomb repulsion is shown between the electron polarons and impurity ions, which is similar to the potential barriers; while the coulomb attraction appears between the hole polaron and impurity ions, which is similar to a potential well. However, as the distance between the impurity ions becomes large enough, the average speeds of the electron and hole polarons almost remain the same, and show just a few small oscillation. This is due to the different distances between impurity ions which generate the different superposition effects of barrier or potential well on the electron and hole polarons. 2) Next, with a fixed distance between the two impurity ions, we find that with the increase of impurity potential strength, the average velocities of the electron and hole polarons decrease. And the decrease of the average speed of the hole polaron is more obvious. It can be explained as follows: the coulomb attraction interactions between the hole polaron and impurity ions can obviously enhance the localization of the hole polaron. While the coulomb repulsion interactions between electron polaron and impurity ions can only make the electron polaron undergo a small shift in the polymer chain, so that the localization of it is almost unchanged. In view of the average speed of the polaron being closely related to the localization of the polaron, the change of the average speed of the hole polaron is more obvious. The results above may provide some theoretical basis for understanding the conduction properties in doped polymers.
White light emitting diode based on quantum dots and MEH-PPV
Authors: Sun Li-Zhi  , Zhao Su-Ling  , Xu Zheng  , Yin Hui-Li  , Zhang Cheng-Wen  , Long Zhi-Juan  , Hong Xiao-Xia  , Wang Peng  , Xu Xu-Rong  ,   Institute of Optoelectronics Technology, Beijing Jiaotong University, Key Laboratory of Luminescence and Optical Information (Beijing Jiaotong University), Ministry of Education, Beijing 100044, China
Published: December 2020

The white light emitting diode (LED) devices, in which blue-emitting quantum dots doped in the polymer of poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylene vinylene] (MEH-PPV) serve as the active layer, have been fabricated in a nitrogen-filled glove box; the devices have the structure of ITO/PEDOT/MEH-PPV:QDs(B)/LiF/Al. After a systematical investigation, we report the effect of different quantum dots (QDs) doping concentration (mass fraction) on the electroluminescent spectrum, current density, brightness, CIE coordinates of the devices and atomic force microscopy (AFM) characterizations of the emitting layer. With the increase of QDs doping concentration, we find that the QDs luminance intensity of the controlling devices continues to grow. When the QDs doping concentration is 40%, the normal white light emission is obtained in the devices. The CIE coordinates of the white QD-LED are (0.35, 0.32), which are close to the balanced white coordinates. Besides, we also fabricate the non-doped devices, in which the structure is ITO/PEDOT/MEH-PPV/QDs(B)/LiF/Al. After finishing the active layer's preparation, the morphology of the films are investigated by AFM. By comparing the analysis, the doped system has a lower level on the root mean squared roughness. In addition, the doped devices demonstrate a superior performance, and exhibit a low turn-on voltage and a high maximum value of luminance.
Single event upsets sensitivity of low energy proton in nanometer static random access memory
Authors: Luo Yin-Hong  , Zhang Feng-Qi  , Wang Yan-Ping  , Wang Yuan-Ming  , Guo Xiao-Qiang  , Guo Hong-Xia  ,   State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024, China
Published: December 2020

Low-energy protons are able to generate enough energy through direct ionization to cause a high single event upset cross section as the feature size of semiconductor devices shrinks. It poses a large challenge on the present proton single event modeling test technique and the space upset rate prediction method. Experimental study of proton single event effect in three different feature sizes of static random access memory (SRAM) (i.e. 65 nm, 90 nm, and 250 nm) is carried out based on domestic low-energy proton accelerators and also the foreign middle-high proton accelerators. Complete cross section curves of proton single event upset from low energy to high energy are acquired. Test results show that single event upset cross section below 1 MeV proton is up to three orders of magnitude higher than the saturation cross section of high-energy proton in nanometer SRAM. However, single event upset is not observed for protons below 3 MeV in 250 nm SRAM, and no single event multiple-cell upsets occur for protons below 1 MeV in 90 nm and 65 nm SRAM. The accurate geometrical structure model of composite sensitive volume is constructed through the combination of test data with device information, and calibrated further by single event test data of low-LET heavy ion and high-energy proton. Simulation results based on the model and Monte-Carlo calculation can reveal the root cause of low-proton single event upset cross section peak. Proton single event upsets are only caused through direct ionization of protons below 1 MeV. When low-energy protons pass through the multiple metallization and passivation layers of the device, the energy spectrum is broadened near the Bragg peak of the proton direct ionization, and the energy is deposited concentratedly into the sensitive volume through direct ionization. When the proton energy is too high or too low, the energy can not be deposited effectively into the sensitive volume through direct ionization. The energy spectrum straggling of low-energy protons due to the use of degrader has a large influence on the height and width of the single event upset cross section peak. Moreover, the contribution of low protons to the space proton single event upset rate is predicted for GEO orbit environment in the worst day environment. It shows that the direct ionization from low energy dominates the proton single event upset rate in the space in 65 nm SRAM. With the development of device technology, the critical charge of single event upset will be further reduced; and to the single event upset from low proton direct ionization more attention must be paid in the study and evaluation of single event effect.
R-branch and Q-branch high rotational spectral lines of diatomic molecules using improved difference converging method
Authors: Jiang Yong-Hong  , Sun Wei-Guo  , Zhang Yi  , Fu Jia  , Fan Qun-Chao  ,   College of Science, National University of Defense Technology, Changsha 410073, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   Research Center for Advanced Computation, School of Physics and Chemistry, Xihua University, Chengdu 610039, China;,   College of OptoElectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The accuracies of the predicted R-branch and Q-branch transitional lines of rovibrational diatomic systems for rotational states of J 100 are improved by using new analytical formulae and an improved difference converging method (DCM) in this study. The new formulae include the contributions from a higher-order energy term Hv. The improved DCM method includes a new physical converging criterion that is particularly useful in predicting unknown transitional lines. These improvements are used to study the transitional lines of the R-branch of the TiF and CO molecules and the Q-branch of the TiF molecule. The results show that the accuracies of the R-branch and Q-branch rotational lines are about one order of magnitude better than the results obtained using previous formulae; the new physical converging criterion can efficiently reduce the possible errors in the spectrum computations; the theoretical rotational lines obtained using the improved DCM method are much better than those obtained using the least-squares method.
Large-scale nanostructure metrology using Mueller matrix imaging ellipsometry
Authors: Chen Xiu-Guo  , Yuan Kui  , Du Wei-Chao  , Chen Jun  , Jiang Hao  , Zhang Chuan-Wei  , Liu Shi-Yuan  ,   State Key Laboratory for Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, China;,   Wuhan EOptics Technology Co. Ltd. , Wuhan 430075, China
Published: December 2020

In order to achieve effective process control, the fast, inexpensive, nondestructive and accurate nanoscale feature measurements are extremely useful in high-volume nanomanufacturing. The optical scatterometry has currently become one of the important approaches for in-line metrology of geometrical parameters of nanostructures in high-volume nanomanufacturing due to its high throughput, low cost, and minimal sample damage. Conventional scatterometry techniques can only obtain the mean geometrical parameter values located in the illumination spot, but cannot acquire the microscopic variation of geometrical parameters less than the illumination region. In addition, conventional scatterometry techniques can only perform monospot test. Therefore, the sample stage must be scanned spot by spot in order to obtain the distribution of geometrical parameters in a large area. Consequently, the final test efficiency will be greatly reduced. Accordingly, in this paper, we combine conventional scatterometry with imaging techniques and adopt the Mueller matrix imaging ellipsometry (MMIE) for fast, large-scale and accurate nanostructure metrology. A spectroscopic Mueller matrix imaging ellipsometer is developed in our laboratory by substituting a complementary metal oxide semiconductor camera for the spectrometer in a previously developed dual rotating-compensator Mueller matrix ellipsometer and by placing a telecentric lens as an imaging lens in the polarization state analyzer arm of the ellipsometer. The light wavelengths in the developed imaging ellipsometer are scanned in a range of 400-700 nm by using a monochromator. The spectroscopic Mueller matrix imaging ellipsometer is then used for measuring a typical Si grating template used in nanoimprint lithography. The measurement results indicate that the developed instrument has a measurement accuracy of better than 0.05 for all the Mueller matrix elements in both the whole image and the whole spectral range. The three-dimensional microscopic maps of geometrical parameters of the Si grating template over a large area with pixel-sized lateral resolution are then reconstructed from the collected spectral imaging Mueller matrices by solving an inverse diffraction problem. The MMIE-measured results that are extracted from Mueller matrix spectra collected by a single pixel of the camera are in good agreement with those measured by a scanning electron microscope and the conventional Mueller matrix ellipsometer. The MMIE that combines the great power of conventional Mueller matrix ellipsometry with the high spatial resolution of optical microscopy is thus expected to be a powerful tool for large-scale nanostructure metrology in future high-volume nanomanufacturing.
Influences of Raman gain and self-steepening on the propagation characteristic of Airy pulse
Authors: Zhu Kun-Zhan  , Jia Wei-Guo  , Zhang Kui  , Yu Yu  , Zhang Jun-Ping  ,   School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China
Published: December 2020

By using nonlinear Schrdinger equation including Raman gain and self-steepening but ignoring fiber loss situation, the propagation characteristics of Airy pulse are simulated and analyzed in the single-mode fiber. Simulations show that Airy pulse can be converted into soliton and its propagation direction is skewed due to the effects of Raman gain and self-steepening under a certain condition. In time domain, the number of small peaks of Airy pulse reduces rapidly. Airy pulse becomes a peak structure containing a main peak and sub-peaks where the energies can be ignored by changing the coefficient a reasonablely, which is approximated as the soliton structure. Therefore, Airy pulse is regarded as transforming into soliton. Meanwhile, in the case of small values b, there exists a significant difference in shape between Airy pulse and soliton. With the value of parameter b increasing slowly, the shape of Airy pulse is very close to soliton's, therefore Airy pulse can transform into soliton by changing value b reasonablely. Compared with by changing b value, Airy pulse convered into the soliton is stable by changing the a value reasonablely. Simultaneously, with the increases of values of coefficient a and amplitude b, the time-shift of Airy pulse increases. However, the time-shift of Airy pulse would decrease when Raman gain and Self-steepening become strong, no matter what the values of a and b are. Further, the acceleration properties of Airy pulse are investigated. It is found that Airy pulse autoacceleration is not a stable value at the beginning but it gradually stabilizes with the increase of transmission distance. The reason is that the energies of secondary peaks exert a tremendous influence on the main lobe of Airy pulse at the beginning, however, secondary peaks diffuse fast with the increase of transmission and then the influence can be ignored to a certain extent. So, the main peak gradually stabilizes with the increase of transmission distance.
Searching superconductivity in potassium-doped p-terphenyl
Authors: Gao Yun  , Wang Ren-Shu  , Wu Xiao-Lin  , Cheng Jia  , Deng Tian-Guo  , Yan Xun-Wang  , Huang Zhong-Bing  ,   Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062, China;,   Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, China;,   Faculty of Physics and Electronic Tengineering, Anyang Normal University, Anyang 455000, China
Published: December 2020

Searching new superconducting materials and understanding their superconducting mechanisms are the important research directions in the condensed matter physics study. The recent discovery of aromatic hydrocarbon superconductors, including potassium-doped picene, phenanthrene and dibenzopentacene, has aroused considerable research interest of physicists and materials scientists.
In this work, potassium-doped p-terphenyl is grown by sealing potassium and p-terphenyl with a mole ratio of 3 : 1 in high-vacuum glass tube and then annealed at 170 ℃ for 7 days or at 240 and 260 ℃ for 24 h. The crystal structure, molecular vibration, and magnetic property are characterized by using X-ray diffraction, Raman scattering, and superconducting quantum interference device. The combination of X-ray diffraction spectrum and Raman spectrum shows that besides potassium-doped p-terphenyl and KH, there exist C60 and graphite in annealed sample, which are found for the first time in the metal-doped aromatic hydrocarbon. Owing to the presence of potassium with high chemical activity, the C-H bond can be broken, resulting in dehydrogenated p-terphenyl with dangling bonds. Consequently, the recombination of dehydrogenated p-terphenyl will form graphite and C60. In addition, the red-shifts of partial peaks of p-terphenyl in Raman spectrum demonstrate that 4 s electron of doped potassium is transferred to C atom.
For the samples annealed at 170 and 240 ℃, Curie paramagnetic behaviors are observed in the whole temperature region. On the other hand, in one of the samples annealed at 260 ℃, there exist three anomalous sharp decreases respectively at 17.86, 10.00 and 6.42 K in the zero-field cooling magnetic measurement. Previous studies indicated that the superconducting transition temperatures of potassium-doped C60 and potassium-doped graphite are about 18 K and 3 K. Therefore, it is reasonable to attribute the anomalous sharp decrease at 17.86 K to being produced by potassium-doped C60, while the anomalous sharp decreases at 10.00 and 6.42 K, which have not been reported yet, may be produced by potassium-doped p-terphenyl. The first principles calculations show that potassium-doped p-terphenyl lies in the metallic state, which can form superconductivity due to the electron-phonon interaction. Our results are useful for understanding the crystal growth and physical properties of metal-doped aromatic hydrocarbon organic superconductors. Furthermore, our findings provide a new routine to synthesizing C60 and graphite at low temperature.
Attitude estimator for spinning aircraft using earth infrared radiation field
Authors: Yu Jing  , Bu Xiong-Zhu  , Niu Jie  , Wang Xin-Zheng  ,   School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China;,   School of Electrical and Electronic Engineering, Changzhou College of Information Technology, Changzhou 213164, China
Published: December 2020

The continuous improvement in diversification, new-type orientation and low cost of navigation control system, the accurate measurement of the spinning aircraft flight attitude parameters has becomes a more and more urgent task. In view of the above problems, a novel attitude estimator for the spinning aircraft is proposed by using earth infrared radiation field. The attitude estimation system possesses several key advantages over the current designs in low cost, no need of moving parts, and being free from reliance on GPS or other state feedback. Firstly, the mechanism of earth infrared radiation field is described in detail, and an 8-14 m atmospheric window is selected as the study object. The land surface infrared radiation is calculated by the land surface temperature and emissivity. The sky infrared radiation is calculated through layered atmosphere by combing with the sky emissivity and infrared atmospheric transmittance. According to the calculations of land surface infrared radiation and sky infrared radiation, the mathematical model of earth infrared radiation field is established by combining with propagation law of infrared radiation in the atmosphere. Then the measurement model of thermopile sensors is derived, after analyzing the motion feature of spinning aircraft during the flight. The thermopile sensors convert the observed infrared radiation into an electrical signal well suited for onboard data acquisition. To explore the inner link between the thermopile sensor output and the spinning aircraft attitude information, the characteristics of the sensor output under different attitude angles and fields of view are studied. When the thermopile sensor characteristics are included, the fully developed model can be used to generate accurate sensor output as a function of attitude angle. Finally, the installation of the thermopile sensors on the spinning aircraft is designed, and the measurement model of onboard thermopile sensor is established. In order to improve the accuracy of attitude measurement, an extended Kalman filter is developed, which enables the estimating of real-time attitude angles and roll rate by using solely three-axis thermopile sensors as feedback. The result indicates that by using this high accurate algorithm, the pitch angle estimation error is within 0.02, the roll angle estimation error is within 0.1 and the roll rate estimation error is within 1 rad/s. The detection system is simple and practical, works stably, and can meet the requirements for spinning projectile attitude measurement. The attitude estimation system will provide a new method and theory for further developing the spinning aircraft state detection.
Nonorthogonal decoy-state quantum key distribution based on coherent-state superpositions
Authors: Sun Wei  , Yin Hua-Lei  , Sun Xiang-Xiang  , Chen Teng-Yun  ,   Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China;,   Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Nonorthogonal coded agreements and decoy state method can effectively protect the photon number against splitting attack. Owing to the fact that the component of single-photon in the coherent-state superposition (CSS) is as high as 90%, CSS has recently emerged as an alternative to single-photon qubits for quantum information processing and metrology. The approximate CSS of small amplitudes is generated by the subtraction of photons from a squeezed vacuum state, and the approximate CSS of large amplitude is generated from Fock state by using a single homodyne detection. Here, we combine both of the methods and propose a new protocol by using the CSS as a light source. We derive the secure key generation rate, the lower bound of count rate and upper bound of error rate of single-photon. We simulate the curves relationship between secure key generation rate and safety transmission distance in the case of an infinite number of decoy states by using matlab. The parameters are given according to the Gobby-Yuan-Shields (GYS) experiment. We infer that the safety transmission distance achieves 147.4 km and the secure key generation rate is much higher than those of other schemes. We also simulate the relationship between key generation rate and safety transmission distance in the case of a limited number of decoy states by using matlab. The parameters are given according to the GYS experiment too. When the N is 1010, the safety transmission distance achieves 144 km; when the N is 109, the safety transmission distance achieves 139 km; when the N is 108, the safety transmission distance achieves 125.9 km. In this paper, we propose the use of CSS as the light source. Combining SARG04 agreements and decoy state, the scheme has the following advantages: first, the scheme which combines SARG04 agreements and decoy state method can effectively resist PNS; second, nonorthogonal decoy-state quantum key distribution based on coherent-state superpositions has a longer safety transmission distance and higher secure key generation rate than nonorthogonal decoy-state quantum key distribution based on weak coherent pulse and nonorthogonal decoy-state quantum key distribution based on conditionally prepared down-conversion source; third, nonorthogonal decoy-state quantum key distribution based on coherent-state superpositions is easier to prepare, which just needs one decoy state, than other schemes that require several decoy states. Obviously, our scheme can enhance the performance of quantum key distribution. Nonorthogonal decoy-state quantum key distribution based on coherent-state superpositions will have a very good application with the further development of preparation technology of CSS.
Inclined glass-sand flow and the angle of repose
Authors: Zhang Yu  , Wei Yan-Fang  , Peng Zheng  , Jiang Yi-Min  , Duan Wen-Shan  , Hou Mei-Ying  ,   College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;,   Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condense Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   College of Physical Science and Technology, Yulin Normal University, Yulin 537000, China;,   Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China;,   School of Physical and Technology, Central South University, Changsha 410083, China
Published: December 2020

Systematic experimental study on inclined orifice flow and the measurement of the angle of repose are carried out in this work. The inclined orifice flow is formed by glass beads in an inclined channel. The flow is discharged near the bottom of the channel under gravity. The flow rates are measured at various inclination angles of the channel and opening sizes of the orifice. We then record the inclination angle when the rate becomes zero. We compare this zero-rate inclination angle with the repose angle of glass-beads, and the internal friction angle is determined by the yield stress obtained from a direct shear experiment. It is interesting to find that the experimental values at these three measured critical angles are equal within the experimental errors: 1) the supplementary angle of the extrapolating inclined angle at which the flow rate becomes zero and the inclined hole of diameter approaches infinitely large value (i. e. D), s= 180-c, where c is the critical angle for the inclined hole of diameter D and cc(D); 2) the repose angle r of a cone-shaped pile, which is formed when particles fall from the top point of the heap onto a smooth bottom plate; and 3) the internal friction angle that is measured by direct shear experiment. This result intends to support that the solid-liquid transitions occurring in the inclined orifice flow and free surface of granular heap, and the Coulomb yield occurring in the bulk of the granular solid all originate from the same critical property. Owing to the fact that the internal stresses and strains of samples in the three cases all have complicated and nonuniform distributions so that they cannot be analyzed quantitatively at present, Only some qualitative discussion on this issue is given in this paper.
Numerical simulation of laminar flow past two side-by-side cylinders by discontinuous Galerkin method
Authors: Zhang Zhong-Yu  , Yao Xiong-Liang  , Zhang A-Man  ,   College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Investigations of vortex dynamics about two circular cylinders in a side-by-side arrangement help the understanding of flows around more complex structures, which are found to have many engineering applications. These applications involve offshore structures, power generation, micro-turbine engines, cooling towers, and paper machine forming fabrics, etc. Therefore, two-dimensional compressible laminar flows over two cylinders in side-by-side arrangement are numerically investigated at low Reynolds number. The high-order discontinuous Galerkin method is employed to simulate the flow, which combines the advantages associated with finite element and finite volume methods. As in classical finite element method, the spatial accuracy can be obtained by the high-order polynomial approximation within an element rather than by stencils as in finite volume method. The curved triangle is used to represent the wall boundary of cylinder to maintain the high-order accurate simulation. Then the characteristics of the wake flow are identified by capturing the vortex structure. After verifying the rationality of the method, the influences of gap spacing on vortex shedding and mechanical characteristics are analyzed. The results reveal that the flow depends to a large extent on the gap spacing between the two cylinders, which can change the vortex shedding pattern. At the gap spacing S*=1.1, wake flow pattern resembles the vortex street of a single bluff body. The flow in the gap is too weak to affect the wake pattern, leading to the complete suppression of vortices shed on the gap sides of both cylinders. At the gap spacing S*=1.4, the results reveal that the gap flow is deflected from one cylinder to another. Meanwhile, the wakes represent randomly flip-flopping between two states of the gap flow direction, which is called the flip-flopping wake pattern. The flow is no longer periodic but becomes drastically unsteady. Anti-symmetric flow pattern is predicted for gap spacing S*=2.5, indicating that two parallel vortex streets are anti-symmetric with respect to the centerline. With further increasing the gap spacing to S*=4, the symmetric flow pattern is observed. Furthermore, the flow preserves its structure very far downstream without any distortion. With the increase of the cylinder spacing, the average drag coefficients are declined significantly, and the absolute value of average lift coefficient decreases simultaneously. The Reynolds number has a little influence on the average drag coefficient. As the Reynolds number increases, the average lift coefficient decreases, while the vortex shedding frequency increases.
Stress and structure properties of X-ray W/Si multilayer under low temperature annealing
Authors: Zhang Jin-Shuai  , Huang Qiu-Shi  , Jiang Li  , Qi Run-Ze  , Yang Yang  , Wang Feng-Li  , Zhang Zhong  , Wang Zhan-Shan  ,   Key Laboratory of Advanced-Structured Micro-Materials, Ministry of Education, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
Published: December 2020

The X-ray timing and polarization telescope proposed in China is for imaging spectroscopy in an energy range of 1-30 keV. To obtain the high energy spectrum response with a large effective area, W/Si multilayer mirrors each with a mirror thickness of only 0.3 mm are used. This makes the figure accuracy of the mirror and the distortion caused by the multilayer stress an important issue during the telescope development. W/Si multilayer mirror is an important component of X-ray telescope for astronomical observation. To reduce the effect of the multilayer stress and maintain a high reflectivity at the same time, the W/Si multilayers prepared by magnetron sputtering deposition are annealed at low temperatures of 150 ℃, 175 ℃ and 200 ℃, respectively, for 3 h. The stress of the multilayer is determined based on the surface figure measurements of each sample before and after annealing. The X-ray reflectance and layer structure of the multilayer are characterized by the grazing incidence X-ray reflectometry (GIXR) and the reflectance fitting curves. The first Bragg peak reflectivity of the as-deposited sample is 67% at 8.04 keV and the multilayer stress is around -260 MPa. After annealing at 150 ℃ for 3 h, the first Bragg peak reflectivity and the layer structure are almost the same as before annealing, while the stress reduces 27%. The fitting results display almost the same interface widths of the multilayer before and after annealing. As the temperature increases to 175 ℃, the first Bragg peak reflectivity drops by about 2%. The multilayer structure begins to deteriorate and the W/Si interface widths increase from 0.346 nm/0.351 nm to 0.356 nm/0.389 nm, according to the fitting results, while the stress reduces about 50%. After annealing at 200 ℃ for 3 h, the stress reduces 60% and the stress decreases down to about -86 MPa. However, the first Bragg peak reflectivity drops by 17%, and the layer structure undergoes significant change after annealing. The W/Si interface widths increase from 0.352 nm/0.364 nm to 0.364 nm/0.405 nm. The GIXR results also show that the d-spacing between the multilayers decreases after annealing, and a higher annealing temperature causes a larger decrease. The stress reduction should be mainly caused by the enhanced atomic diffusions at the interface and inside the layer structure during the annealing. The enlarged interface and the possible compound formation contribute to the decrease of X-ray reflectance and the layer compactness. These results provide important guidance for developing low-stress X-ray multilayer mirrors.
First-principle studies of the electronic structures and optical properties of diamond crystal co-doped with B and N
Authors: Wang Ying  , Li Yong  , Li Zong-Bao  ,   Key Laboratory of New Material Manufacture and Application of the Department of Education of Guizhou Province, School of Physics and Electronic Engineering, Tongren University, Tongren 554300, China
Published: December 2020

On the basis of our previous experimental results for the diamond synthesized in FeNi-C system by B and N co-doping under high pressure and high temperature conditions, the crystals doped with B or N atom, and co-doped with B and N atom are investigated separately by using the first principle density functional theory based on the stable structure of diamond. The formation energies corresponding to the all doping diamond crystals are studied while the most stable co-doping structures with the lowest energy are obtained. Furthermore, the absorption spectra, the densities of states, and the electronic structures of the doping diamond crystals are discussed. The absorption spectra show obviously the red shift, which is consistent with the experimental result. The electronic results show that the doping of N atom is prior to the doping of B atom while the system co-doped with nearly neighboring B and N atoms creates the most stable structure with the lowest formation energy due to the synergistic effect.
Interfacial trap dependent resistance switching effect in Nd0.7Sr0.3MnO3 ceramic
Authors: Chen Shun-Sheng  , Xiong Liang-Bin  , Yang Chang-Ping  ,   Institute for Quantum Materials, School of Mathematics and Physics, Hubei Polytechnic University, Huangshi 435003, China;,   School of Physics and Electronic-Information Engineering, Hubei Engineering University, Xiaogan 432000, China;,   Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, China
Published: December 2020

Switching behavior in Nd0.7Sr0.3MnO3 ceramic is investigated widely due to its close association with the new storage Resistive random access memory. In this work, we discuss the transport characteristic of the electrode-bulk interface and boundary/phase interface, and explain the differences between the two interfaces. Firstly, the Nd0.7Sr0.3MnO3 ceramic samples are prepared by solid-phase reaction and high-energy milling methods, respectively. And the transport properties of the two interfaces are investigated respectively by the two-line and four-line measurements. The results show that the Ag electrode-bulk interfaces exhibit nonlinear and hysteretic I-V characteristics and a stable resistance switching effect, and the stability of resistance switching behavior is reduced gradually with the increase of temperature. For the boundaries/phase interfaces, however, it does not exhibit resistance switching effect, although a nonlinear and hysteretic I-V behavior can also be observed under the four-line measurement mode. Various defects in the two interfaces act as traps and regulate the interfacial transports and result in the nonlinear and hysteretic I-V behaviors in the two interfaces. Additionally, the simulation experiments reveal that a large number of boundaries/phase interfaces and larger leakage conductance resulting from the complex connections of boundaries/phase interfaces are the main responsibilities for the fact that the boundaries/(phase) interfaces do not exhibit EPIR behavior as the electrode-bulk interface.
Huber-based high-degree cubature Kalman tracking algorithm
Authors: Zhang Wen-Jie  , Wang Shi-Yuan  , Feng Ya-Li  , Feng Jiu-Chao  ,   School of Electronic and Information Engineering, Southwest University, Chongqing 400715, China;,   School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510641, China
Published: December 2020

In recent decades, nonlinear Kalman filtering based on Bayesian theory has been intensively studied to solve the problem of state estimation in nonlinear dynamical system. Under the Gaussian assumption, Bayesian filtering can provide a unified recursive solution to the estimation problem that is described as the calculation of Gaussian weighted integrals. However it is typically intractable to directly calculate these integrals. The numerical integration methods are required from a practical perspective. Therefore, nonlinear Kalman filters are generated by different numerical integrations. As a representative of nonlinear Kalman filter, cubature Kalman filter (CKF) utilizes a numerical rule based on the third-degree spherical-radial cubature rule to obtain better numerical stability, which is widely used in many fields, e.g., positioning, attitude estimation, and communication. Target tracking can be generalized as the estimations of the target position, the target velocity and other parameters. Hence, nonlinear Kalman filters can also be used to perform target tracking, effectively. Since the CKF based on the third-degree cubature rule has a limited accuracy of estimation, it is necessary to find a CKF based a cubature rule with higher accuracy in the case of target tracking system with a large uncertainty. High-degree cubature Kalman filter is therefore proposed to implement state estimation due to its higher numerical accuracy, which is preferred to solve the estimation problem existing in target tracking. To improve the filtering accuracy and robustness of high-degree cubature Kalman filter, in this paper we present a new filtering algorithm named Huber-based high-degree cubature Kalman filter (HHCKF) algorithm. After approximating nonlinear measurements by using the statistical linear regression model, the measurement update is implemented by the Huber M estimation. As a mixed estimation technique based on the minimum of l1-norm and l2-norm, the Huber estimator has high robustness and numerical accuracy under the assumption of Gaussian measurement noises. Therefore, the Huber-based high-degree cubature Kalman tracking algorithm is generated by combining the state prediction based on the fifth-degree spherical radial rule. In this paper, the influence of tuning parameter on the tracking performance is discussed by simulations. Simulations in the context of bearings only tracking and reentry vehicle tracking demonstrate that the new HHCKF can improve the tracking performance significantly.