高功率脉冲TEA CO2激光除漆的研究

选用高功率脉冲TEA CO2激光器,对不同颜色不同种类的油漆进行了清洗实验,运用数码照片分析程序计算出清洁率,找出了完全清洗阈值和损伤阈值.实验结果较为清晰地给出了激光输出能量和重复频率对清洗效果的影响.对红色醇酸漆来说,完全清洗阈值为10.37J/cm2,而损伤阈值为11.43 J/cm2;红色金属喷漆的完全清洗阈值为9.66 J/cm2,其损伤阈值达10.37 J/cm2;黄色金属喷漆的完全清洗阈值为10.71 J/cm2,损伤阈值则为11.07 J/cm2.输出能量和重复频率未达指定参数时,激光清洗清洁率则低于100%.     

CO2激光和等离子体清洗提高石英基片损伤阈值

 采用连续CO₂激光和真空等离子体相结合的方法对石英基片进行清洗。通过光学显微图、水接触角、透过率和损伤阈值测量分别表征了CO₂激光和等离子体对真空硅脂蒸发物污染过的石英基片的清洗效果。研究表明：对于真空硅脂蒸发物污染后的石英基片，可以先采用低能量的CO₂激光进行大面积清洗，再用真空等离子体进行精细清洗。光学显微图像表明：清洗后的基片表面的油珠被清除干净；水滴接触角由63°下降到4°；在400 nm附近，基片透过率由92.3%上升到93.3%；损伤阈值由3.77 J/cm²上升到5.09 J/cm²。     

Effect of structural parameters of Gaussian repaired pit on light intensity distribution inside KH_2PO_4 crystal

KH2PO4 （KDP） crystal with excellent optical properties is a very important element of inertial confinement fusion （ICF） device. However, KDP crystal surface micro-defects severely reduce the crystal laser damage threshold, affecting the crystal service life. In this paper, Gaussian repaired pit is used to replace the crystal surface micro-defects, in order to improve the laser damage resistance of the KDP crystal with surface micro-defects. At first, the physical model of Gaussian repaired pit is built by Fourier model method, and the accuracy of the method is analyzed. It is found that the calculation error can be reduced by increasing the product of the width-period ratio and the truncation constant of the repaired pit. The calculation results about the physical model of Gaussian repaired pit show that the light intensity distribution within the crystal is symmetrical, and there are evidently enhanced light intensity regions in the crystal. Meanwhile, the maximum relative intensity inside the KDP crystal decreases gradually with the increase of the width of the Gaussian repaired pit. Secondly, the Gaussian repaired pits with different widths and the same depth of 20 μm are processed by micro-milling. Their surfaces are very smooth and present the ductile cutting state under the microscope. Finally, the laser damage threshold of the Gaussian repaired pits on the surface of the KDP crystal sample is measured by a 3 ω, 6-ns laser. The results showthat the maximum threshold of the Gaussian repaired pits is 3.12 J/cm2, which is 60% higher than the threshold of initial damage point, and the laser damage threshold increases with the increase of the width of the Gaussian repaired pit.     

清洗对偏振分光膜损伤阈值的影响

采用微分干涉显微镜、扫描电镜和聚焦离子束观察了偏振分光膜损伤的形貌,从损伤机理出发,研究了清洗对偏振分光膜损伤阈值的影响。结果表明:清洗能有效去除表面杂质,清洗质量越好,基板上的杂质尺寸越小,杂质密度也越小,相应的偏振分光膜S光的损伤阈值越高;清洗能有效去除基板表面的纳米吸收中心,吸收性杂质分布密度越小,吸收峰越低,P光的损伤阈值越高。     

Effect of high temperature band gap of GaN annealing on strain and nanoparticles

<正>Black-coloured GaN nanoparticles with an average grain size of 50 nm have been obtained by annealing GaN nanoparticles under flowing nitrogen at 1200℃for 30 min.XRD measurement result indicates an increase in the lattice parameter of the GaN nanoparticles annealed at 1200℃,and HRTEM image shows that the increase cannot be ascribed to other ions in the interstitial positions.If the as-synthesised GaN nanoparticles at 950℃are regarded as standard,the thermal expansion changes nonlinearly with temperature and is anisotropic;the expansion below 1000℃is smaller than that above 1000℃.This study provides an experimental demonstration for selecting the proper annealing temperature of GaN.In addition,a large blueshift in optical bandgap of the annealed GaN nanoparticles at 1200℃is observed,which can be ascribed to the dominant transitions from the C（Γ₇） with the peak energy at 3.532 eV.     

Relaxation Property and Stability Analysis of the Quasispecies Models

The relaxation property of both Eigen model and Crow-Kimura model with a single peak fitness landscape is studied from phase transition point of view. We first analyze the eigenvalue spectra of the replication mutation matrices. For sufficiently long sequences, the almost crossing point between the largest and seeond-largest eigenvalues locates the error threshold at which critical slowing down behavior appears. We calculate the critical exponent in the limit of infinite sequence lengths and compare it with the result from numerical curve fittings at sufficiently long sequences. We find that for both models the relaxation time diverges with exponent 1 at the error （mutation） threshold point. Results obtained from both methods agree quite well. From the unlimited correlation length feature, the first order phase transition is further confirmed. Finally with linear stability theory, we show that the two model systems are stable for all ranges of mutation rate. The Igigen model is asymptotically stable in terms of mutant classes, and the Crow-Kimura model is completely stable.     

Modeling process of the neutral beam re-ionization loss

The basic process of re-ionization loss was studied.In the drift duct there are three processes leading to re-ionization loss：the collision of neutral beam particles with the molecules of background gas,similar collisions with released molecules from the inner wall of the drift duct and the ferret-collisions among particles with different energy of the neutral beam.Mathematical models have been developed and taking EAST-NBI parameters as an example,the re-ionization loss was obtained within these models.The result indicated that in the early stage of the neutral beam injector operation the released gas was quite abundant.The amount of re-ionization loss owing to the released gas can be as high as 60%.In the case of a long-time operation of the neutral beam injector,the total re-ionization loss decreases from 13.7% to 5.7%.Then the reionization loss originating mainly from the collisions between particles of the neutral beam and the background molecules is dominant,covering about 92% of the total re-ionization loss.The drift duct pressure was the decisive factor for neutral beam re-ionization loss.     

Influences of anionic and cationic dopants on the morphology and optical properties of PbS nanostructures

Selenium and zinc are used as anionic and cationic dopant elements to dope PbS nanostructures. The undoped and doped PbS nanostructures are grown using a thermal evaporation method. Scanning electron microscopy （SEM） results show similar morphologies for the undoped and doped PbS nanostructures. X-ray diffraction （XRD） patterns of three sets of the nanostructures indicate that these nanostructures each have a PbS structure with a cubic phase. Evidence of dopant incorporation is demonstrated by X-ray photoelectron spectroscopy （XPS）. Raman spectra of the synthesized samples con- firm the XRD results and indicate five Raman active modes, which relate to the PbS cubic phase for all the nanostructures. Room temperature photoluminescence （PL） and UV-Vis spectrometers are used to study optical properties of the undoped and doped PbS nanostructures. Optical characterization shows that emission and absorption peaks are in the infrared （IR） region of the electromagnetic spectrum for all PbS nanostructures. In addition, the optical studies of the doped PbS nanos- tructures reveal that the band gap of the Se-doped PbS is smaller, and the band gap of the Zn-doped PbS is bigger than the band gap of the undoped PbS nanostructures.     

Threshold Multiparty Controlled Teleportation of Arbitrary m-Qubit Quantum Information

We present a （t, .n） threshold multiparty controlled quantum teleportation protocol of an arbitrary m-qubit quantum state between two remote parties. The unknown m-qubit quantum state can be recovered by the receiver under control of a subset of the n controllers if the number of the subset is larger than or equal to a threshold, say, t, but not for any t - 1 or fewer controllers. Our scheme seems to be more practical and more flexible than other existing protocols. The quantum resource required is just m Einstein-Podolsky-Rosen （EPR） pairs plus some single photons. The techniques required are only Bell state measurement, single-qubit unitary operation and yon Neumann measurement. So our scheme is also feasible with present-day technique.     

Improved Ligand-Field Theoretical Calculations of R-Line Thermal Broadenings of NIgO：Cr^3＋ and MgO：V^2＋

With the values of parameters obtained from improved ligand-field theory, by taking into account all the irreducible representations and their components in EPI as well as all the levels and the admixtures of basic wavefunctions within d^3 electronic configuration, the R-line thermal broadenings （TB） of both MgO：Cr^3＋ and MgO：V^2＋ have microscopic-theoretically been calculated, The results are in very good agreement with the experimental data. It is found that the R-line TB of MgO：Cr^3＋ or MgO：V^2＋ comes from the first-order term of EPI. The elastic Raman scattering of acoustic phonons plays a dominant role in R-line TB of MgO：Cr^3＋ or MgO：V^2＋.     

Energy Spectrum,g Factors,Strain-Induced Level-Splittings and R-Line Thermal Shift of MgO：V^2＋＋

Traditional ligand-field theory has to be improved by taking into account both pure electronic contribution and electron-phonon interaction one （including lattice-vibrational relaxation energy）. By means of improved ligand-field theory, the R line, t^322T1 and t^322T2 lines, t^22（^3T1）e^4T2, t^22（^3T1）e^4T1 and t2e^2（^4A2）4T1 bands, g factors of t^32 ^4A2 and t32E, four strain-induced level-splittings and R-line thermal shift of MgO：V^2＋ have been calculated. The results are in very good agreement with the experimental data. It is found that for MgO：V^2＋, the contributions due to electronphonon interaction （EPI） come from the first-order term; the contributions from the second-order and higher terms are insignificant. In thermal shift of R line of MgO：V^2＋, the temperature-dependent contribution due to EPI is dominant. The results obtained in this work may be used in theoretical calculations of other effects of EPI.     

Cooling of Akmal-Pandharipande-Ravenhall neutron stars with a rotochemical heating source

Employing phenomenological density-dependent critical temperatures of strong singlet-state proton pairing and of moderate triplet-state neutron pairing, we investigate the effects of rotochemical heating on the thermal evolution of superfluid neutron stars whose cores consist of npe matter with the Akmal-Pandharipande-Ravenhall equation of state. Since the star is not quite in the weak interaction equilibrium state during spin-down, the departure from the chemical equilibrium leads to the rotochemical heating in a rotating NS which will increase the stellar＇s temperature. Our calculations show that the rotochemical heating delays the cooling of superfluid neutron stars considerably and makes the previous classification of NS cooling ambiguous. What＇s more, our model is currently consistent with all the observational data, and in particular some middle-aged and cold NSs （PRS J0205＋6449 in 3C 58, PRS J1357-6429, RX J007.0＋7303 in CTA 1, Vela） can be better explained when taking into account rotochemical heating.     

Characteristic parameters from a human of electromagnetic signals heart system

The electromagnetic field of a human heart system is a bioelectromagnetic field. Electrocardiography （ECG） and magnetocardiography （MCG） are both carriers of electromagnetic information about the cardiac system, and they are nonstationary signals. In this study, ECG and MCG data from healthy subjects are acquired; the MCG data are captured using a high-Tc radio frequency superconducting quantum interference device （HTc rf SQUIDs） and the QRS complexes in these data are analysed by the evolutionary spectrum analysis method. The results show that the quality factor Q and the central frequency fz of the QRS complex evolutionary spectrum are the characteristic parameters （CHPs） of ECG and MCG in the time-frequency domain. The confidence intervals of the mean values of the CHPs are estimated by the Student t distribution method in mathematical statistics. We believe that there are threshold ranges of the mean values of Q and fz for healthy subjects. We have postulated the following criterion： if the mean values of CHPs are in the proper ranges, the cardiac system is in a normal condition and it possesses the capability of homeostasis. In contrast, if the mean values of the CHPs do not lie in the proper ranges, the homeostasis of the cardiac system is lacking and some cardiac disease may follow. The results and procedure of MCG CHPs in the study afford a technological route for the application of HTc rf SQUIDs in cardiology.     

Fabrication of VO_2 thin film by rapid thermal annealing in oxygen atmosphere and its metal–insulator phase transition properties

Vanadium dioxide thin films have been fabricated through sputtering vanadium thin films and rapid thermal annealing in oxygen. The microstructure and the metal–insulator transition properties of the vanadium dioxide thin films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and a spectrometer. It is found that the preferred orientation of the vanadium dioxide changes from(1ˉ11) to(011) with increasing thickness of the vanadium thin film after rapid thermal annealing. The vanadium dioxide thin films exhibit an obvious metal–insulator transition with increasing temperature, and the phase transition temperature decreases as the film thickness increases. The transition shows hysteretic behaviors, and the hysteresis width decreases as the film thickness increases due to the higher concentration carriers resulted from the uncompleted lattice. The fabrication of vanadium dioxide thin films with higher concentration carriers will facilitate the nature study of the metal–insulator transition.     

Phase transformation in Mg Sb_3Te thin films

Mg-doped Sb3Te films are proposed to improve the performance of phase-change memory （PCM）. We prepare Mg- doped Sb3Te films and investigate their crystallization behaviors, structural, optical and electrical properties. We find that Mg-doping can increase the crystallization temperature, enhance the activation energy, and improve the 10-year data retention of Sb3Te. Especially Mg25.19（Sb3Te）74.81 shows higher Tc （~ 190℃） and larger Ea （~ 3.49 eV）, which results in a better data retention maintaining for 10 yr at ~ 112 ℃. Moreover Ra/Rc value is also improved. These excellent properties make Mg-Sb-Te material a promising candidate for the phase-change memory （PCM）.     

Performance characteristics a nonlinear diode and optimal analysis of refrigerator

This paper establishes a model of a nonlinear diode refrigerator consisting of two diodes switched in the opposite directions and located in two heat reservoirs with different temperatures. Based on the theory of thermal fluctuations, the expressions of the heat flux absorbed from the heat reservoirs are derived. After the heat leak between the two reservoirs is considered, the cooling rate and the coefficient of performance are obtained analytically. The influence of the heat leak and the temperature ratio on the performance characteristics of the refrigerator is analysed in detail.     

Thermal analysis and expected performance of the low energy instrument on board the HXMT satellite

The Low Energy X-ray Instrument （LE） of the Hard X-ray Modulation Telescope （HXMT） uses the Swept Charge Device （SCD） to detect the X-rays in 1-15 keV. The performance of SCD is vulnerable to temperature. We analyzed the thermal condition of LE at different satellite working attitudes with the Finite Element Method （FEM）. It is shown that the angle between the sunlight and the normal line of the barrier should be less them 26°, to keep the SCD detectors working in the required temperature range, i.e. -40 ℃ to -80 ℃. We find that the performance of LE is very stable in this temperature range, with a typical energy resolution of 160 eV at 5.9 keV.     

Thermal modeling optimization and experimental validation for a single, concentrator solar cell system with a heat sink

A single concentrator solar cell model with a heat sink is established to simulate the thermal performance of the system by varying the number, height, and thickness of fins, the base thickness and thermal resistance of the thermal conductive adhesive. Influence disciplines of those parameters on temperatures of the solar cell and heat sink are obtained. With optimized number, height and thickness of fins, and the thickness values of base of 8, 1.4 cm, 1.5 mm, and 2 mm, the lowest temperatures of the solar cell and heat sink are 41.7℃ and 36.3℃ respectively. A concentrator solar cell prototype with a heat sink fabricated based on the simulation optimized structure is built. Outdoor temperatures of the prototype are tested. Temperatures of the solar cell and heat sink are stabilized with time continuing at about 37℃-38℃ and 35℃-36℃ respectively, slightly lower than the simulation results because of effects of the wind and cloud. Thus the simulation model enables to predict the thermal performance of the system, and the simulation results can be a reference for designing heat sinks in the field of single concentrator solar cells.     

Thermal analysis for the high duty cycle PIMS accelerator

To develop the high power proton linear accelerator for the Accelerator Driven System（ADS） program,the preliminary design of the Pi mode accelerating structure（PIMS） has been carried out.It is estimated that PIMS would heat up to 80 for low duty cycle（0.1%） without water-cooling,which is not acceptable thus water-cooling is demanded.The structure stability for the high duty cycle or even for CW operation is crucially important for the ADS application.Therefore,thermal analysis with water-cooling for a high duty accelerator in our ADS research is performed to control the frequency shift caused by a temperature rise.     

Different Epidemic Models on Complex Networks

Models for diseases spreading are not just limited to SIS or SIR. For instance, for the spreading of AIDS/HIV, the susceptible individuals can be classified into different cases according to their immunity, and similarly, the infected individuals can be sorted into different classes according to their infectivity. Moreover, some diseases may develop through several stages. Many authors have shown that the individuals＇ relation can be viewed as a complex network. So in this paper, in order to better explain the dynamical behavior of epidemics, we consider different epidemic models on complex networks, and obtain the epidemic threshold for each ease. Finally, we present numerical simulations for each case to verify our results.