bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of biochemical markers in the monitoring of COVID-19 patients
Authors: Letelier Pablo , Encina Nicole , Morales Pablo , Riffo Alejandra , Silva Halett , Riquelme Ismael , Guzmán Neftalí
Published: December 2020

COVID-19 is an infectious disease caused by the SARSCoV-2 virus, which has given rise to a global sanitary emergency. The clinical characteristics of COVID-19 are varied and can range from an asymptomatic infection to a mild to severe pneumonia. Recent studies have shown that different laboratory parameters become altered in these patients, and as such are useful as biomarkers to assess the progression of the disease and categorize patients that may present a severe and/or fatal clinical condition. This review analyzes biochemical and immunological markers that become altered in COVID-19 patients and their impact on different organs at a hepatic, cardiac, renal and pancreatic level, as well as markers of inflammation, analyzing their implications in the evolution of the disease.
Stepwise Algorithmic Approach to Endoscopic Removal of Biliary Partially Covered and Uncovered Self-Expanding Metal Stents (with Videos)
Authors: Jain Deepanshu , Stein Assaf , Hasan Muhammad K.
Published: December 2020

Self-expanding metal stents play a crucial role in the management of patients with biliary obstruction. Endoscopic extraction of uncovered metal stents (UCMSs) and partially covered metal stents (PCMSs) could be challenging because of tissue ingrowth. No standardized technique can guarantee universal success. We present our technique and experience of endoscopic extraction of biliary stents in two patients with a UCMS and three patients with a PCMS. Three of the five patients had a previous failed attempt of stent extraction at an outside hospital. Overall, our composite success rate was 80% (4/5). The individual success rate was 100% (3/3) for PCMSs and 50% (1/2) for UCMSs. The stent-in-stent technique, in which a fully covered metal stent is placed through an existing UCMS/PCMS, was used in 60% (3/5) of the cases, with a success rate of 66.7% (2/3). We share our algorithmic approach to each case, with detailed emphasis on the technical aspects of the procedure.
Relapsed/Refractory Diffuse Large B-Cell Lymphoma and Mantle Cell Lymphoma: Is It Time to Consider CAR-T for All?
Authors: Zelenetz Andrew D.
Published: December 2020

CAR T cells have demonstrated activity in relapsed/refractory non-Hodgkin lymphoma, including diffuse large B-cell lymphoma (DLBCL), indolent non-Hodgkin lymphoma, and mantle cell lymphoma. For patients with chemorefractory disease, CAR T cells can provide a durable complete response in a portion of patients, which represents a major advance in the field. For patients with chemosensitive disease, however, additional data are needed to determine whether CAR T cells are preferable to conventional approaches. Studies in DLBCL have shown that patients experiencing a PET-positive partial response after second-line chemotherapy have long-term outcomes after high-dose therapy and autologous stem cell rescue that are similar to CAR T-cell therapy, with decreased toxicity and cost. Alternative third-line options such as tafasitamab/lenalidomide and bispecific antibodies may also have a role for patients with chemorefractory disease.
The work integration social enterprises in Greece
Authors: Douvitsa Ifigeneia -
Published: December 2020

The present paper focuses on the available legal forms with work integration as their explicit purpose in the Greek legislature and outlines their main traits on the basis of the EMES (European Research Network) nine criteria of social enterprises. Their thus far implementation is also discussed, including the challenges and shortcomings that WISEs have faced in the Greek context.The main findings of the study indicate a dominance of the cooperative form for the WISEs under the Greek context. More specifically, the legislator imposes a percentage of members coming from the target group, perceiving in that way mutuality and solidarity as rather intertwined, since the WISEs’ explicit aim of work integration of the disadvantaged people is mainly achieved by joining the cooperative. Despite the supportive measures for the WISEs, the implementation of the thus far public policies has not been effective in further promoting such a model of enterprise.
Classification and quantification of qubit and qutrit multipartite pure state entanglement
Authors: Lu Guo-Ying  , Pan Feng  ,   (1)辽宁师范大学物理系，大连 116029; (2)辽宁师范大学物理系，大连 116029;辽宁大学物理系，沈阳 110036
Published: December 2020

Classification and quantification of bipartite qubit, tripartite qubit, and bipartite qutrit entanglement are studied in detail based on the entanglement measure of multipartite pure states. The results show that different ways of pure state entanglement can be characterized by extremal values of the corresponding entanglement measure under the stochastic local operation and classical communication(SLOCC). Detailed analysis shows that there are three different kinds of entanglement under the SLOCC in both tripartite qubit and bipartite qutrit pure state systems. Comparison of the measure with the recently proposed entropy-product measure is made and briefly discussed.
Research on network fixed point theory based on the correlation of nodes
Authors: Liu Hui  , Zhang Jun  ,   北京航空航天大学电子信息工程学院，北京 100083
Published: December 2020

Power laws are ubiquitous in the complex communication networks of today. Network nodes are correlated. According to the correlation, network fixed point theory is proposed and analyzed. Banach fixed point theory was used to explain the operation of networks. In this way, the validity of network fixed point theory is proved. The iterative node sequences of Markov-like chains are generated by algorithms of routing. Communication network can be considered as a space formed by the node sequences. Based on the correlation of nodes, the more nodes in the sequence, the more accurately reflected the searching object node. The property makes location finding and data mining more accurate in communication. The object node mapped from the source node by some routing rule corresponds to Banach fixed point. The fixed point in network space is the object node. The physical character of network fixed point theory will be highly evident, when the network can provide ubiquitous connection for users. The reason is that when the network scale becomes greater, the colony action of nodes is more obvious, and network fixed point theory can show its physical character better. It has great significant theoretical and practical meaning for the organic and dynamic characters and congestion analysis of complex traffic communication network.
A novel all-optical surface atomic (molecular) funnel
Authors: Ji Xian-Ming  , Lu Jun-Fa  , Mu Ren-Wang  , Yin Jian-Ping  ,   (1)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海 200062; (2)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海 200062;东华理工学院物理系，抚州 344000; (3)南通大学理学院，南通 226007;华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海 200062
Published: December 2020

We propose a novel scheme to build an all-optical surface atomic (or molecular) funnel using an optical system consisting of three cylindrical lenses, which can be used to produce a funnel-shaped intensity distribution near the focal plane of the last lens when the optical system is illuminated by a red-detuned Gaussian laser beam. We calculate the corresponding intensity distribution, the optical dipole potential and its dipole force for 23Na atoms. Our study shows that the proposed atom (or molecular) funnel can be used for the efficient loading of cold atoms in the surface optical guid, beam splitter and interferometer and surface microtrap, and so on. So our funnel has important applications in the integrated atom optics and its atom chip.
Theoretical calculation of the differential cross section for He-NO collision system
Authors: Wang Rong-Kai  , Linghu Rong-Feng  , Yang Xiang-Dong  ,   (1)贵州师范大学理学院,贵阳 550001; (2)贵州师范大学理学院,贵阳 550001;四川大学原子与分子物理研究所,成都 610065; (3)四川大学原子与分子物理研究所,成都 610065
Published: December 2020

An anisotropic intermolecular potential of the He-NO complex has been obtained by utilizing the Huxley analytic function to fit the intermolecular energy data, which have been calculated at the theoretical level of the RCCSD(T)/aug-cc-pVTZ+bf. Then the total differential cross section, elastic differential cross section and inelastic differential cross section for collision between He atom and NO molecule have been calculated using close-coupling approximation. Finally, the law governing the change of the differential scattering cross section has been given. This study shows that the fitted anisotropic intermolecular potential not only possesses the advantage of a simpler function form but also offers a better description of the characteristic of interaction in He-NO system. At the same time, the difficult problem of determining the intermolecular potential parameters can be solved on the basis of the results of ab initio calculation for the collision systems. Therefore, the result obtained may be helpful for probing collision mechanism between atoms and molecules.
The S, T, U parameters study of electron scattering by sodium atom
Authors: You Yong  , Liu Yi-Bao  , Deng Ling-Na  , Li Qun  ,   (1)东华理工学院核资源与环境教育部重点实验室，南昌 330013;东华理工学院物理系，抚州 344000; (2)东华理工学院核资源与环境教育部重点实验室，南昌 330013;东华理工学院物理系，抚州 344000;清华大学物理系，北京 100084
Published: December 2020

The S, T, U parameters of sodium from S→P state excited by electron, which can describe the changes of spin moment before and after collision, are calculated using the distorded wave Born approach with the scattering amplitudes and phases. We analyze the S,T,U parameters under the incident electron energy from 2.2 to 60 eV. The Sp parameter better coincides with reported experiment at 10 eV incident electron energy. All results show that the distribution changes are more obvious at lower incident energy than at higher energy.
Investigation of the processes in the collisions of partially stripped carbon ions with helium atom at low to intermediate energies
Authors: Gao Zhi-Min  , Chen Xi-Meng  , Liu Zhao-Yuan  , Ding Bao-Wei  , Lu Yan-Xia  , Fu Hong-Bin  , Liu Yu-Wen  , Du Juan  , Cui Ying  , Shao Jian-Xiong  , Zhang Hong-Qiang  , Sun Guang-Zhi  ,   兰州大学核科学与技术学院，兰州 730000
Published: December 2020

he cross-section ratios for the double-to-single ionization of He associated with no projectile charge change (Rq,q), single-electron capture (Rq,q-1) and single-electron loss (Rq,q+1) were measured using coincidence technique. The coincidences resulted from the signals of recoil ions and scattered projectiles. For a given incoming projectile charge state the double-to-single ionization ratios vary strongly with the outgoing reaction channel. It is found that Rq,qRq,q+1Rq,q-1. For direct ionization, Rq,q is nearly independent of the incident projectile charge state. However, for ionization associated with single-electron capture and single-electron loss by the projectile, Rq,q-1 and Rq,q+1 depend strongly on the incident charge state of the projectile. These ionization ratios are interpreted in terms of theories of the atomic polarization effect and the screening and antiscreening effect of the electrons around the core.
Monte Carlo simulation of backscattering by a melting layer of precipitation
Authors: Sun Xian-Ming  , Han Yi-Ping  , Shi Xiao-Wei  ,   西安电子科技大学理学院,西安 710071
Published: December 2020

The melting snow particles on top of clouds form the melting layer of precipitation. The melting process starts with the snow particles falling, so the microphysical characteristics of the melting layer vary continuously in vertical direction. In this paper, a Monte Carlo simulation model for the melting layer is developed, and the melting snow particles are modeled by more practical three-layered spherical particles. The size distribution of the melting snow particles is derived from the raindrops size distribution. Vertical profiles of radar reflectivity and specific attenuation factor are computed at 5, 10, 35 and 94 GHz using the Mie theory at rain rates below 12.5 mm/h. It is shown that the radar bright band can be absent in the melting layer at frequencies above 20 GHz. This agrees with radar observations at 35 and 94 GHz. Base on the radiative transfer theory, the Monte Carlo method is used to compute the reflectivity of the melting layer whose microphysical characteristics are continuous in vertical direction. We compared the reflectivity of the melting layers with two different size-distributions (Gamma size distribution and Marshall-Palmer size distribution). These provided theoretical and numerical basis for radar remote sensing of the melting layer with high frequencies electromagnetic waves.
Soliton pulses in an erbium-doped fiber ring laser and its use in supercontinuum generation
Authors: Zhang Shu-Min  , Fan Hong  , Lü Fu-Yun  , Zuo Xiao-Xue  ,   (1)河北建筑工程学院数理系，张家口 075024; (2)河北师范大学物理科学与信息工程学院，石家庄 050016; (3)南开大学物理科学学院，天津 300071
Published: December 2020

We present a source of soliton pulses in an erbium-doped fiber ring laser. The passive mode-locking is achieved by using the nonlinear polarization rotation technique. The system generates 352 fs pulses with repetition rate of 12.5 MHz and the 3dB spectrum width of about 7.8 nm at the central wavelength of 1563.3 nm. A low-cost erbium-doped fiber amplifier is employed to boost the peak power of the pulses. Single-mode supercontinuum is obtained by passing the amplified pulses through a photonic crystal fiber with the length of 101 nm. Further more, we show the evolution process of the supercontinuum with different optical pump power. It is shown that, with the low-intensity femtosecond pulses, the spectrum broadening is caused by the fission of the higher-order solitons. With the increase of the pump power, the threshold of stimulated Raman scattering (SRS) is achieved, and the energy transfer through SRS spreads toward the long wavelength and the short wavelength sides. On further increasing the pump power, the coupling between SRS and parametric four-wave mixing will result in the appearance of waves with new wavelengths, and the spectrum will become broader and more smooth.
Spectroscopic properties of Er3+/Yb3+ co-doped transparent yttrium lanthanum oxide ceramic
Authors: Ding Jun  , Yang Qiu-Hong  , Tang Zai-Feng  , Xu Jun  , Su Liang-Bi  ,   (1)上海大学电子信息材料系，上海 200072; (2)中国科学院上海光学精密机械研究所，上海 201800
Published: December 2020

Yb3+/Er3+ co-doped yttrium lanthanum oxide transparent ceramics were fabricated and their spectroscopic properties were investigated. The specimens have large absorption and emission cross section. Because of the additive La2O3, the fluorescence lifetime of the specimens were close to that of the glasses. When the Yb3+ and Er3+ contents were 5at% and 0.5at%, the lifetime reached 9.65 ms. The properties of the specimens such as long lifetime, high emission cross section and narrow line width are favorable for the microminiaturization, integration and high power output of lasers.
Investigation of supercontinuum generation in normal dispersion-flattened fiber by picosecond seed pulses
Authors: Xia Ge  , Huang De-Xiu  , Yuan Xiu-Hua  ,   华中科技大学光电子工程系，武汉 430074
Published: December 2020

The evolution of picosecond seed pulses in the normal dispersion-flattened fiber to generate supercontinuum (SC) is investigated. The appearance of wave breaking during the process and the effect of the revealed four-wave mixing on the char acteristics of SC are also analyzed. The research indicates that the broadening of the pulse spectrum in the initial stage is dominated by the self-phase modulation. Afterwards, self-phase modulation is impaired while four-wave mixing is enhanced due to energy in the inner spectrum region being transferred continuously to the outside wings by dispersion, and the pulse spectrum further broadens remarkably. The characteristic of SC noise manifests the dynamic responses of typical SC spectral structures to the seed pulse amplitude noise that are closely related to the evolution.
Experimental and theoretical investigation on novel all-optical format conversion based on a folded ultrafast nonlinear interferometer
Authors: Li Da  , Zhang Xin-Liang  , Huang De-Xiu  ,   华中科技大学光电子与信息学院，武汉 430074;华中科技大学光电子科学与工程学院，武汉 430074
Published: December 2020

Pattern conversion is the key technology for all-optical clock recovery from non-return-to-zero (NRZ)signal. A novel scheme for all-optical NRZ to pseudo-return-to-zero (PRZ)conversion using a folded ultrafast nonlinear interferometer (UNI) has been put forward and demonstrated for the first time. Based on the segmented semiconductor optical amplifier model and the transmittance of the UNI, theoretical model for this scheme is established and the output characteristics are calculated theoretically. Stable format conversion from NRZ data to PRZ data has been achieved at 10, 20 and 40 Gbit/s. The influences of the input signal characteristics on the performance of the format conversion are investigated. Experimental results are in agreement with the numerical simulation results.
Perpendicular all-optical control of interactional optical spatical soliton pair
Authors: Li Yang-Gang  , She Wei-Long  , Wang Hong-Cheng  ,   中山大学光电材料与技术国家重点实验室，广州 510275
Published: December 2020

In photoisomerization polymer, the perpendicular optical control of the optical spatial soliton interaction is simulated by numerical method. Under control, the properties of two interacting solitons are damaged, the signal beam can give birth to phenomena such as the two beams to join together, or to detach and so on. We also give a physical explanation of the phenomena, that they are determined by the difference in the initiatial phases of the beams, the incident position of control-beam and so on. The effect of perpendicular optical control of interaction solitons can be applied to optical interlinkage, optical waveguide and so on.
Measurement of optical nonlinearities in nonlocal nonlinear media by a single Z-scan method
Authors: Gao Xi-Cun  , Hu Wei  , Zhang Tao  , Guo Qi  , Wang Xin-Ai  , Long Xue-Wen  ,   华南师范大学光子信息技术实验室，广州 510006;华南师范大学传输光学实验室，广州 510006
Published: December 2020

Using Gaussian decomposion method, we analyze the characteristics of Z-scan curves for nonlocal nonlinear materials in this paper.We provide the normalized transmittance expression for determinating the nonlinear refractive index of nonlocal nonlinear medium based on Gaussian nonlinear response, analyze the influence of the degree of nonlocality on the Z-scan curves, show the methods of measuring the nonlinear refractive index of nonlocal nonlinear medium and the degree of nonlocality, discuss the adjustment brought about by the degree of nonlocality and suggest some feasible measurements. In addition, the numerical results on the base of sech response are obtained and compared with the results on the assumption that the nonlinear response of the nonlocal media is Gaussian.
Dispersion analysis of photonic crystal fiber using improved full-vectorial effective index method
Authors: Zhao Xing-Tao  , Hou Lan-Tian  , Liu Zhao-Lun  , Wang Wei  , Wei Hong-Yan  , Ma Jing-Rui  ,   燕山大学信息科学与工程学院，红外光纤与传感研究所，秦皇岛 066004
Published: December 2020

The relation of normalized core radius (p/Λ) with hole-to-pitch ratio (d/Λ) and normalized frequency (Λ/λ) is obtained using full-vectorial effective index method. The illogical fixed valve of p/Λ is modified, and an improved full-vectorial effective index method is proposed. The modal properties computed using this method, such as the effective index and total dispersion, closely agree with those of the multi-pole method as well the experimental values, and the error of effective index was reduced by two to three orders. The dispersion of photonic crystal fiber is analyzed in detail, and the relations of dispersion with wavelength, hole pitch and d/Λ is obtained.
The characteristics of wave propagation in laminated grid structure
Authors: Wen Ji-Hong  , Yu Dian-Long  , Wang Gang  , Zhao Hong-Gang  , Liu Yao-Zong  ,   国防科学技术大学机电工程研究所,长沙 410073
Published: December 2020

The characteristics of wave propagation in laminated grid structure are analyzed using the lumped-mass method to yield the phase constant surface. The directions and regions of wave propagation in this grid structure for certain frequencies during pass bands are predicted with the iso-frequency contour lines of the phase constant surface, which are also validated with the calculated harmonic responses of a finite two-dimensional grid structure with 15×15 unit cells.
Studies of maximum static friction force in granular pile with probing rod
Authors: Kong Wei-Shu  , Hu Lin  , Du Xue-Neng  , Zhang Xing-Gang  , Wang Wei-Ming  , Wu Yu  ,   贵州大学理学院，贵州省光电子技术与应用重点实验室，贵阳 550025
Published: December 2020

Experiments are designed to explore the maximum static friction F on a dragged probing rod in a granular pile contained in a cylindrical vessel. The results show that F decreases with the radius R of the cylindrical vessel increasing when R is smaller than 0.040 m, and F scarcely changes with R for R >0.045 m. Curve fitting shows that F is as a function of h (the height of the granular pile), namely F=A［h+B(e-h/B-1)］, here the parameter A relates to the shape of probing rod and the flow rate of injecting granules into the cylindrical vessel, and parameter B depends on the flow rate of injecting granules into the cylindrical vessel.
Molecular theory of apparent viscosity of liquid in microchannels
Authors: You Xue-Yi  , Zheng Xiang-Jun  , Zheng Jing-Ru  ,   天津大学环境科学与工程学院，天津 300072
Published: December 2020

By considering the effect of intermolecular force, the apparent viscosity of non-polar-molecular liquid flowing in microchannels with isotropic solid wall is studied. The molecular theory of apparent viscosity in microchannel taking into account the effects of channel walls is proposed. Numerical results show that the effect of the wall on liquid apparent viscosity can be very strong. The intensity of effect is determined by the intermolecular force between the liquid and the wall. Meanwhile, the effect of the wall decreases rapidly with the increase of distance from the wall. For liquid argon, the extent of influence is within 10 layers of molecules, which is about 4 nm from the wall.
Structure, magnetism and 119Sn M?ssbauer spectral study on intermetallic compound PrMn6Sn6
Authors: Huang Yan-Jun  , Li Shu-Zhen  , Han Zhi-Da  , Lü Li-Ya  , Xia Yuan-Fu  ,   (1)南京大学固体微结构物理国家重点实验室，南京 210093;南京大学江苏省纳米技术重点实验室，南京 210093; (2)南京大学物理系，南京 210093; (3)南京大学物理系，南京 210093;南京大学固体微结构物理国家重点实验室，南京 210093
Published: December 2020

The intermetallic compound PrMn6Sn6 was prepared by arc-melting and showed a HoFe6Sn6-type (group space: Immm) structure. The compound is ferromagnetic, where the Mn- and Pr-sublattices are ferromagnetically coupled,and has a Curie temperature of 325 K. The 119Sn Mssbauer spectra between 15 and 360 K were measured, and were analyzed by a simplified model according to the eight Sn crystallographic sites with different nearest-neighbors environment, and the corresponding transferred hyperfine fields and the average value dependence on temperature were obtained. The magnetic structure of the two sublattice is discussed.
Direct observation of phase separation in binary monotectic solution
Authors: Zhai Wei  , Wang Nan  , Wei Bing-Bo  ,   西北工业大学应用物理系，西安 710072
Published: December 2020

A horizontal annular temperature field has been designed on the basis of similarity principle to investigate the formation mechanism of core-shell microstructures of monotectic alloys during free fall. The phase separation process of transparent succino-dinitrile-52.6mol%H2O monotectic solution was observed directly. The H2O phase separated from the parent liquid at first, then moved to the center of the sample, and at last occupied the core part. The moving velocities of H2O droplets were measured according to the photographic pictures, which are in good agreement with the theoretical prediction of Marangoni migration velocities. The experiment reproduced the liquid phase separation process of monotectic alloy under microgravity condition.
Depletion interactions in charged colloidal system
Authors: Li Chun-Shu  , Xiao Chang-Ming  ,   (1)湖南师范大学物理系, 长沙 410081; (2)湖南师范大学物理系, 长沙 410081;湖南科技学院物理系, 永州 425100
Published: December 2020

The weakly charged colloidal system consisting of one or two charged large-spheres immersed in charged small-spheres confined between two charged plates are studied through Monte Carlo simulation. The electrostatic energy of the system is analytically calculated using the hyper-sphere method, and the depletion interactions between the charged large-sphere and the charged plate, and that between two charged large-spheres, are obtained using the acceptance ratio method. Compared with the corresponding uncharged hard sphere systems, it is found that, in the charged systems, the depletion forces between the charged spheres and the two charged plates are strengthened by the electrostatic interactions.
Research on characteristics of neuron potassium channel under low level laser irradiation
Authors: Qiao Xiao-Yan  , Li Gang  , Lin Ling  , He Bing-Jun  ,   (1)南开大学生命科学学院,天津 300071; (2)天津大学精密仪器与光电子工程学院,天津 300072; (3)天津大学精密仪器与光电子工程学院,天津 300072;山西大学物理电子工程学院,太原 030006
Published: December 2020

Acutely isolated rat hippocampal CA3 pyramidal neurons were irradiated with a semiconductor laser of wavelength 670 nm and power 5 mW. The properties of transient outward potassium (K+) channel were investigated using the whole-cell patch clamp technique. The experiment revealed that low level laser reduced the amplitudes of IA in a voltage-dependent and reversible manner. The steady-state activation and inactivation processes of IA were significantly affected by laser irradiation. And the steady-state activation curve shifted towards positive potential direction, altering the slope factor of curve and increasing the half-activation voltage. However, the steady-state inactivation curve shifted towards negative potential direction, reducing the half-inactivation voltage without changing the slope factor. The results show that low level laser irradiation could change the characteristics of transient outward K+ channel. Accordingly, the firing of action potential and the physiological function of neurons were adjusted as a result of low level laser irradiation, which might contribute to the recovery and regeneration of injured neurons.
The study of symmetries and conserved quantities for one class of linearly coupled multidimensional freedom systems
Authors: Lou Zhi_Mei  ,   绍兴文理学院物理系，绍兴 312000
Published: December 2020

In this paper, we eliminate the coupled terms in Lagrangian firstly by changing the coordinate scales and rotating the coordinate axes, and obtain the conserved quantities in new coordinates directly. According inverse transform of the coordinates, we can obtain the conserved quantities in original coordinates, the Noether symmetry and Lie symmetry of the infinitesimal transformations of conserve quantities are studied in this paper，and an example is given to illustrate the application of the result.
The effect of Noise-First and anticipation headway on traffic flow
Authors: Chen Shi_Dong  , Zhu Liu_Hua  , Kong Ling_Jiang  , Liu Mu_Ren  ,   (1)广西师范大学物理与电子工程学院,桂林 541004; (2)玉林师范学院物理与信息科学系,玉林 537000
Published: December 2020

In this context, we introduce anticipation headway to modify the Noise-First NaSch model under condition of periodic boundary. The traffic situation with different parameters can be numerical simulated. It was indicated that the Noise-First model with added anticipation headway is more realistic in reflecting traffic flow. Not only start-stop wave and synchronized flow but also the metastable state can be obtained by numerical simulation. The modified model can reproduce nonlinear phenomena which tallies with the real traffic.
Study of a novel matrix converter based on double-loop control strategy
Authors: Zhang Xiao_Ping  , Zhu Jian_Lin  , Wen Ze_Jun  , Yue Zhou  , Liu Sha_Sha  ,   (1)湖南科技大学机械设备健康维护湖南省重点实验室，湘潭 411201; (2)湖南科技大学机械设备健康维护湖南省重点实验室，湘潭 411201；湖南科技大学信息与电气工程学院，湘潭 411201; (3)湘潭大学信息工程学院，湘潭 411105
Published: December 2020

As the conventional matrix converter has the drawback of low voltage transfer ratio, a novel matrix converter referred to as a boost AC-DC-AC matrix converter is proposed. The basic configuration of the new topology and its fundamental principles are firstly introduced, the analytic expression concerning functional relation of voltage transfer ratio to duty cycle is analyzed, and the design method of double-loop control strategy adopted is expounded particularly. Finally the validity and feasibility of the new topology are tested by simulation, and the results indicate that the modulation of voltage transfer ratio and output frequency can be realized optionally through this new converter and an ideal sine output wave with little distortion can be gotten, so that the inherent drawback of conventional matrix converter having low voltage transfer ratio is solved successfully. This work may give some hints on further technological research and engineering application.
Optical-readout micro-cantilever array IR imaging system and performance analysis
Authors: Xiong Zhi_Ming  , Zhang Qing_Chuan  , Chen Da_Peng  , Wu Xiao_Ping  , Guo Zhe_Ying  , Dong Feng_Liang  , Miao Zheng_Yu  , Li Chao_Bo  ,   (1)中国科学技术大学，中国科学院材料力学行为和设计重点实验室，合肥 230027; (2)中国科学院微电子研究所，北京 100029
Published: December 2020

The uncooled IR imaging technology has wide applications. Using the optical readout uncooled IR imaging system built in our laboratory, thermal images of human body are obtained successfully by placing a bi-material micro-cantilever array (FPA) without silicon substrate in air. By comparing the IR imaging results obtained by placing FPA under different vacuum pressures, the pressure dependence of the thermal conductance and system noise is modeled, and the influence to the system performance is analyzed. The model of thermal conductance of gas is analyzed and verified experimentally on condition that the mean-free path of the gas molecules is larger than the gas gap between the bi-material cantilever and the wall of vacuum chamber. Experimental analysis indicates that for FPA working in air, the random vibration noise of the cantilever impacted by the gas molecules' thermal motion is the main source of the system noise. When the pressure decreases to lower than 10-2 Pa, the influence of gas conductance can be neglected, the total thermal conductance decreases to the limit of radiative conductance, and the random vibration noise of the cantilever is reduced to a minimum. The experimental results and theoretical analysis agree well.
Global geometry optimization of water clusters (H2O)n≤14)using a single-parent genetic algorithm
Authors: Zhang Su_Ling  , Chen Hong_Shan  , Song Yan  , Yin Yue_Hong  ,   西北师范大学物理与电子工程学院，兰州 730070
Published: December 2020

A single-parent genetic algorithm (SPGA) is developed from the traditional genetic algorithm to optimize cluster structures. Two mutation operators are used to find the global minimum on the potential surface. The algorithm for optimizing the structure of molecule clusters is proposed. Combined with the TIP3P potential energy, the structures of water clusters (H2O)n(n≤14) is studied using SPGA. The stable structures obtained are in complete agreement with the reported results obtained theoretically and experimentally. The calculation results show that SPGA is an efficient and reliable method to find the global minimum structure of molecular clusters.
Wavelength chirping of laser-diodes and optimization of diode-pumped solid-state lasers
Authors: Yu Hai_Wu  , Xu Mei_Jian  , Duan Wen_Tao  , Sui Zhan  ,   中国工程物理研究院激光聚变研究中心，绵阳 621900
Published: December 2020

A spectrum-, temporal- and spatial-resolved physical model of LD pumping dynamics is set up, which includes the wavelength chirping and transient behavior of the power output of LD arrays. Based on this model, we investigate in detail the spectrum selective absorption characteristics from LD output by laser materials with different absorption bandwidths. Also the pumping excitation performances for typical three kinds of laser crystals, Yb:YAG, Yb:S-FAP, and Nd:YAG, are investigated specifically for the pulsed-energy-storage operation mode. Finally, we have optimized the initial central wavelength of LD arrays for the above three crystals and compared their sensitivity to the wavelength chirping of LD arrays.
Experimental and theoretical study of a quasi-bitron as a new high-power microwave device
Authors: Li Zheng-Hong  , Chang An-Bi  , Ju Bing-Quan  , Zhang Youg-Hui  , Xiang Fei  , Zhao Dian-Lin  , Gan Yan-Qing  , Liu Zhong  , Su Chang  , Huang Hua  ,   中国工程物理研究院应用电子学研究所，绵阳 621900
Published: December 2020

A new type of high power microwave device is developed as a quasi-bitron. The device is simple and composes of two parts, the modulation cavity and the extraction cavity, with a coupling between the cavities. The structure has two working modes, one of them is the working mode, and competition between modes can be easily avoided even when the RF field in the device is very strong compared with the BWO (backward wave oscillator). Besides the theoretical analysis, the model has been realized on 2.5 PIC (particle in cell) simulation code. A 9.42GHz bitron oscillator is designed and its theoretical efficiency is 29.4%. The simulation shows the device achieves the efficiency 28% when the beam is 800 kV and 10 kA, and outputs RF power of 2.25GW. The experiment was also carried out on Sinus-700 accelerator. The measured microwave power is 2.44GW at the frequency 9.4GHz.
Investigation of a lossless metamaterial covered conductor cylinder illuminated　by electric-line-source
Authors: Wang Hai-Long  , Wu Qun  , Meng Fan-Yi  , Li Le-Wei  ,   (1)哈尔滨工业大学电子与信息技术研究院，哈尔滨 150001; (2)哈尔滨工业大学电子与信息技术研究院，哈尔滨 150001；新加坡国立大学电气与计算机工程系，新加坡
Published: December 2020

The electromagnetic characteristics of the model for an electric line source radiating parallel to a lossless metamaterial covered infinitely long conductor circular cylinder is investigated. First, the electromagnetic model is presented and exact solution is derived. Second, the exact solution is employed in numerical calculations. The figures of the near field under different geometric and electromagnetic parameters are obtained; the characteristics of the far field properties are also studied through the directivity and normalized radiation resistance. Because of the negative refraction of the metamaterial, the distinct “focus”, which could not be seen in the conventional material, could be obtained in the material layer from the near field pattern. The presented electromagnetic model is compared with the former approach and its validity is proven.
Effect of the strength of randomness on lasing threshold in one-dimensional partially random media
Authors: Wang Hong  , Ouyang Zheng_Biao  , Han Yan-Ling  , Meng Qing-Sheng  , Luo Xian-Da  , Liu Jin-Song  ,   (1)华中科技大学激光技术国家重点实验室，武汉 430074; (2)深圳大学太赫兹技术研究中心，深圳大学工程技术学院,深圳 518060; (3)深圳大学太赫兹技术研究中心，深圳大学工程技术学院,深圳 518060;成都电子科技大学物理电子学院，成都 610054; (4)中国地质大学(武汉)数理系，武汉 430074;华中科技大学图像所，武汉 430074
Published: December 2020

Based on the model of the Maxwell's equations coupled with the rate equations of electronic population, the lasing threshold of optical modes in partially random media is analyzed using the finite difference time domain method. The characteristics of random laser can be described by some factors, such as the strength of randomness, size of medium,etc.,which determine the lasing threshold in random medium. The simulated results show that one or more lasing modes appear when the pumping rate Pr increases beyond the threshold, and the number of modes will increase with random strength and size of medium. In addition, the simulated results demonstrate that the lasing threshold value will attain the minimum value under certain random strength and size of medium, which is at variance with the theoretical result in one-dimensional completely random medium. Such properties of the medium show potential advantage in future application for optical integration.
Coherence vortices in partially coherent beams consisting of a superposition of Laguerre-Gaussian modes
Authors: Liu Pu-Sheng  , Lü Bai-Da  ,   四川大学激光物理与化学研究所，成都 610064
Published: December 2020

The coherence vortices in a new class of partially coherent beams with separable phase recently proposed by Bogatyryova et al. are studied in detail. The new beams are generated by taking an incoherent superposition of Laguerre-Gaussian (LG) modes with equal azimuthal index. It is shown that the mode indices and weight factors of superposed LG modes, as well as the reference choice, affect the position where the circular edge dislocation takes place, and result in the vortex disappearance or the appearance of more than one coherence vortices. Furthermore, there also exist coherence vortices in partially coherent beams with non-separable phase consisting of an incoherent superposition of LG modes.
Ciphertext-only attack on double random phase encoding optical encryption system
Authors: Peng Xiang  , Tang Hong-Qiao  , Tian Jin-Dong  ,   深圳大学光电子学研究所，光电子器件与系统教育部重点实验室，深圳 518060
Published: December 2020

Security analysis of optical encryption system based on double random phase encoding indicates that the system can be classified as a linear symmetric block-cipher cryptosystem, which may lead to a great vulnerability. Under the ciphertext-only attack (COA), an opponent can attack such a cryptosystem only on the basis of estimated support of wave function in the object plane with iterative phase retrieval methods, and subsequently deduce the phase keys in the Fourier plane easily. The ciphertext-only attack (COA) requires much less resources than other types of attacks. Estimated support of wave function in the object plane could have some translations relative to the true support, so retrieved wave function could also have translations in both the amplitude and the phase, leading to a translation of retrieved plaintext relative to original plaintext. However, attackers can take this translation as a priori knowledge to traverse estimated support in the object plane until finding the best estimated keys, which bring about the best decryption quality.
Theoretical investigation on THz wavelength conversion based on four-wave mixing in QWS-DFB-LD
Authors: Jia Xin-Hong  , Zhong Dong-Zhou  , Wang Fei  , Chen Hai-Tao  ,   (1)四川师范大学物理学院，成都 610068; (2)五邑大学信息学院，江门 529020; (3)中国人民解放军武装警察部队学院基础部，廊坊 065000; (4)重庆工学院数理学院，重庆 400050
Published: December 2020

By using the coupled mode equations, the characteristics of THz wavelength converter based on four-wave mixing (FWM) in λ/4 phase-shifted distributed feedback laser diode (QWS-DFB -LD) are analyzed. The numerical simulation indicates that, larger biasing current and smaller detuning expand the dynamic range of conversion efficiency and extinction ratio, but worsen the frequency chirp. Due to the lasing effect, the peak modulation frequency of extinction ratio and chirp occur at the relaxation oscillation frequency. Good conversion characteristics can be obtained by selecting system parameters reasonably. This configuration would have potentials in optics communications because of its wide-band, high-speed and without pump input.
Optical characteristics of Yb:Y2O3 transparent ceramic
Authors: Qi Yun-Feng  , Lou Qi-Hong  , Zhu Hong-Tao  , Zhou Jun  , Dong Jing-Xing  , Wei Yun-Rong  , He Bing  ,   中国科学院上海光学精密机械研究所，上海 201800
Published: December 2020

A new solid-state laser material——Yb：Y2O3 transparent ceramic based on nano crystalline technology and the vacuum sintering (NTVS) method is reported. The manufacture technology, the physical and chemical properties, the energy level split structure and the spectra characteristics of Yb：Y2O3 ceramic media are discussed and compared with those of Yb:YAG single crystal. Further more, with the compact active mirror laser (CAMIL) design, the laser parameters of Yb:Y2O3 ceramic are demonstrated at room temperature. An optimum output power of 10.5W has been obtained under the max imum pumping power of 35 W. Its corresponding slope efficiency was 37.5%. The laser wavelength red-shift was observed with the increasing of the pump power and the reflectivities while the decrease of the radium of output coupler (ROC). In fact, Yb：Y2O3 ceramic is an ideal laser material, it has excellent physical and chemical properties and spectra characteristics comparable with those of the Yb:YAG single crystal. Further more, its thermal conductivity and emission bandwidths are nearly twice those of Yb:YAG, which shows that it is a promising candidate in high power and femto-second pulsed laser applications.
Two-photon asymmetric color-locking second-order stochastic correlation of attosecond polarization beats
Authors: Gan Chen-Li  , Zhang Yan-Peng  , Yu Xiao-Jun  , Nie Zhi-Qiang  , Li Ling  , Song Jian-Ping  , Ge Hao  , Jiang Tong  , Zhang Xiang-Chen  , Lu Ke-Qing  ,   (1)Department of Physics,University of Arkansas,Fayetteville,Arkansas 72701,USA; (2)西安交通大学电子物理与器件教育部重点实验室，西安 710049; (3)中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安 710068
Published: December 2020

Based on the phase-conjugation polarization interference between two two-photon processes, we theoretically investigated the attosecond scale asymmetry sum-frequency polarization beat in four-level system (FASPB). The field correlation has weak influence on the FASPB signal when the laser has narrow bandwidth. Conversely, when the laser has broadband linewidth, the FASPB signal shows resonance-nonresonance cross correlation. The two-photon signal exhibits hybrid radiation-matter detuning terahertz damping oscillation, i. e., when the laser frequency is off resonance from the two-photon transition, the signal exhibits damping oscillation and the profile of the two-photon self-correlation signal also exhibits zero time-delay asymmetry of the maxima. We have also investigated the asymmetry of attosecond polarization beat caused by the shift of the two-photon self-correlation zero time-delay phenomenon, in which the maxima of the two two-photon signals are shifted from zero time-delay point to opposite directions. As an attosecond ultrafast modulation process，FASPB can be intrinsically extended to any level-summation systems of two dipolar forbidden excited states.
Study on the rapid numerical difference recurrence algorithm for the simulation of optical pulse propagation and its applications
Authors: Zhang Guan-Mao  , Zhang Xiao-Ping  ,   兰州大学信息科学与工程学院现代通信技术研究所，兰州 730000
Published: December 2020

Maclaurin expansion near zero domain is applied to analysis the difference form of the normalized nonlinear Schrdinger equation in frequency domain, and a rapid numerical difference recurrence formula is deduced in time domain, which considers the nonlinear Kerr effect as well as the effect of chromatic dispersion in optical medium simultaneously. Through some examples, a comparison is made between the results using the algorithm of this paper and the known analytical results, including the results of SSFM method. The calculated results show that this method has not only fairly fast calculation speed, but also very high calculation precision, and is more suitable to the actual situation of light pulse propagation affected by the dispersion and nonlinearity at the same time through optical medium. All the above results show that it is a well founded, fast and effective numerical calculation method to study light pulse propagation in optical medium.
Widely tunable optical parametric oscillators base on periodically poled MgO doped LiNbO3
Authors: Wu Bo  , Cai Shuang-Shuang  , Shen Jian-Wei  , Shen Yong-Hang  ,   浙江大学现代光学仪器国家重点实验室 310027
Published: December 2020

This paper reports the fabrication of the periodically poled 6mol% MgO doped LiNbO3 (PPMgLN) and the demonstration of the PPMgLN-based optical parametric oscillators (OPOs). The PPMgLN wafer was fabricated by high voltage pulse trigged domain reversal technique with periods ranging from 27.8—31.6μm by a step of 0.2μm. The OPO has a wide spectral tuning range from 1.42—1.73μm (for the signal) and 2.76—4.27μm (for the idler) while the wavelength of the pump is 1.064μm. In the experiment, the output power of 4.8W (the sum of the signal and the idler) was achieved when the input pumping power was 10.6W and the slope efficiency was computed to be 47%.
Optical characterization of ultraviolet laser photosensitive Er3+-doped bismuth-silicate glasses
Authors: Qian Qi  , Wang Yan  , Zhang Qin-Yuan  , Yang Zhong-Min  , Yang Gang-Feng  , Jiang Zhong-Hong  ,   特种功能材料及其制备新技术教育部重点实验室，华南理工大学光通信材料研究所，广州 510640
Published: December 2020

This paper reports on the spectroscopic properties of ultraviolet laser photosensitive Er3+-doped bismuth-silicate glasses. Two series of the glasses Na2O-Bi2O3-SiO2-Er2O3 and Na2O-B2O3-Bi2O3-SiO2-Er2O3 have been prepared by conventional melting and quenching technique. The absorption spectra, emission spectra and lifetime of Er3+ ion have been measured. The optical parameters have been analysed by Judd-Ofelt theory. It is found that the full width at half maximums (FWHMs) increase with increase of the value of Bi2O3/SiO2 and B2O3 content. Meanwhile, the lifetimes of 4I13/2 level of Er3+-doped glasses decrease with increasing Bi2O3 and B2O3 content. When the content of B2O3 is 40%, the measured stimulatied emission cross section, lifetime and FWHM of 4I13/2→4I15/2 transition of Er3+-doped Na2O-B2O3-Bi2O3-SiO2 glass are 8.49×10－21cm2, 0.52ms and 78nm respectively.
Measurement of carrier-envelope phase of few cycles Ti:sapphire laser by difference frequency technique
Authors: Han Hai_Nian  , Zhao Yan_Ying  , Zhang Wei  , Zhu Jiang_Feng  , Wang Peng  , Wei Zhi_Yi  , Li Shi_Qun  ,   (1)清华大学物理系原子分子与光物理研究所，北京 100084; (2)中国科学院物理研究所北京凝聚态物理国家实验室，光物理实验室,北京 100080; (3)中国科学院物理研究所北京凝聚态物理国家实验室，光物理实验室,北京 100080；清华大学物理系原子分子与光物理研究所，北京 100084
Published: December 2020

The self-reference technique is widely used to measure the carrier-envelope phase offset (CEO) of femtosecond laser pulses in the normal femtosecond laser frequency comb system. However, the instability of the frequency comb system is increased because the photonic crystal fiber is introduced into the system to broaden the spectrum of femtosecond laser pulses outside the cavity. In this paper, we presented another method to measure specifically the CEO for the broad spectrum Ti:sapphire oscillator with the pulse duration of 7fs, namely the difference frequency technique, with which we have obtained the beat frequency signal with a S/N ratio greater than 31dB. This provided a good precondition for the next generation of the femtosecond laser frequency comb system without the photonic crystal fiber.
Algorithm and experimental investigation of patch nearfield acoustic holography based on wave superposition approach
Authors: Xu Liang  , Bi Chuan-Xing  , Chen Jian  , Chen Xin-Zhao  ,   合肥工业大学噪声振动工程研究所，合肥 230009
Published: December 2020

A new patch nearfield acoustic holography (PNAH) based on wave superposition approach is proposed in this paper. In the method, the sound field is extrapolated by superposing wave fields produced by a number of fictitious sources placed inside the radiator, and then the FFT is used for reconstructing the normal velocity or the field on and near the radiator. This method has higher computational accuracy and efficiency than other PNAH techniques, and is very easy for applications. In order to prove its validity, the method was used in the experiment to reconstruct the normal velocity of a clamped point-driven steel plate, and satisfactory results were obtained.
The growth mechanism of monocrystal aluminum nitride nanowires at low temperature
Authors: Lü Hui-Min  , Chen Guang-De  , Yan Guo-Jun  , Ye Hong-Gang  ,   (1)西安交通大学应用物理系，西安 710049; (2)西安交通大学应用物理系，西安 710049;西安理工大学应用物理系，西安 710048
Published: December 2020

In a stainless steel autoclave of 25ml capacity, pure hexagonal aluminum nitride (h-AlN) nanowire has been successfully synthesized by direct reaction of AlCl3 with NaN3 in non-solvent system at low temperature. The obtained grayish-white powder is characterized by high-resolution transmission election microscopy, which shows that the grayish-white products consist of long straight-wires with diameter from 40nm to 60nm and the longest ones were up to several micrometers. The electron diffraction and XRD analysis indicat that the AlN manowire has hexagonal/cubicl monocrystal structure. A possible growth mechanism for h-AlN nanowire is disscussed.