A Novel Tunable Dual-frequency Laser with Large Frequency Difference

This paper proposed a novel tunable dual frequency laser with large frequency difference,which used LD to pump the Nd∶YAG microchip in the end surface and put the liquid pressure on the radial direction of the crystal by a pressure-transporting thin film. As a result of the stress birefringence, there was a mode splitting phenomenon of the microchip laser longitudinal mode. Both theoretical analysis and experiments indicated that there is a directly proportional relation between the frequency difference and the pressure, so the tunable frequency difference could be obtained when the pressure was changed. A large frequency difference of about 3.4 GHz with linear tunable relation was achieved in the experiment,so it can be a practical light source for the absolute distance interferometry.     

辉光放电等离子体处理阳离子染料结晶紫废水

用辉光放电等离子体技术对结晶紫进行了降解脱色处理,考察了多种因素对结晶紫降解效果的影响。实验发现,提高电解质浓度和增加电压均可提高结晶紫的脱色效果,考虑到电极损耗,辉光放电最佳条件为:电解质浓度为2 g/L Na2SO4,电压为600 V。当改变溶液的初始pH值时,结晶紫的脱色率随溶液的初始pH值升高而增加,加入一定量H2O2能明显地提高结晶紫的脱色效率;若加入0.4 mmol/L Fe2 ,5 min时结晶紫的脱色率由原来的13.64%增加到91.36%。结果表明,辉光放电产生的.OH对结晶紫的降解起重要作用。最佳条件下,40 min内的脱色率达到93%,降解率为74%。     

超磁致伸缩换能器的磁滞非线性动力学仿真

在超磁致伸缩材料输出端位移假设的基础上,建立了以输出顶杆为研究对 象、考虑材料内部磁滞非线性及预压弹簧特性的超磁致伸缩换能器非线性动力学模 型; 并将Simulink仿真系统应用到超磁致伸缩换能器系统动力学仿真中. 仿真结果表 明: 换能器模型系统为稳定周期运动系统,并具有滞回非线性特性;弹簧非线性项中的平方 项是影响换能器模型系统的主要因素. 经验证,数值计算结果与文献给出的试验测试结果吻 合较好.     

The research of used in aircraft optical windows sensor systems

The optical windows used in aircrafts protect their imaging sensors from environmental effects. Considering the imaging performance, flat surfaces are traditionally used in the design of optical windows. For aircrafts operating at high speeds, the optical windows should be relatively aerodynamic, but a flat optical window may introduce unacceptably high drag to the airframes. The linear scanning infrared sensors used in aircrafts with, respectively, a flat window, a spherical window and a toric window in front of the aircraft sensors are designed and compared. Simulation results show that the optical design using a toric surface has the integrated advantages of field of regard, aerodynamic drag, narcissus effect, and imaging performance, so the optical window with a toric surface is demonstrated to be suited for this application.     

刚塑性矩形板在冲击载荷作用下的一个新的界限

通过加权残数法，给出了考虑有限变形时刚塑性板在冲击载荷下的能量守恒方程。广义屈服条件由Mij和Nij表示，通过将非光滑屈服函数用其内切和外接光滑函数代替，从而得到板位移的上、下界限解。采用此方法对一矩形板受横向冲击载荷进行了分析，计算结果与有关文献符合较好。     

复合材料层合板在动集中力作用下的结构声强特性

本文研究了复合材料正交异性层合板在动集中力作用下的结构声强特性。应用MSC/-NASTRAN商业软件计算了复合材料正交异性层合板在动集中力作用下各单元的内力和速度,再应用MATLAB软件得出复合材料层合板的结构声强。算例表明,复合材料正交异性层合板的结构声强流线图与各向同性板存在明显不同的特性。复合材料正交异性层合板的结构声强流线图受边界条件、层合板叠层顺序和层数的影响。从结构声强向量图和流线图可获得关于能量传递路径、源位置和能量汇合点的许多信息。进一步,结构振动产生的噪声可根据上述信息加以控制。     

In-situ high pressure X-ray diffraction studies of orthoferrite SmFeO_3

The high-pressure behaviors of SmFeO3 are investigated by angle-dispersive synchrotron X-ray powder diffraction under a pressure of up to 40.3 GPa at room temperature. The crystal structure of SmFeO3 remains stable at up to the highest pressure. The different pressure coefficients of the normalized axial compressibility are obtained to be βa = 0.60 × 10-3 GPa-1,βb = 0.79 × 10-3 GPa-1, βc = 1.28 × 10-3 GPa- 1, and the bulk modulus （B0） is determined to be 293（3） GPa by fitting the pressure-volume data using the Birch-Murnaghan equation of state. Furthermore, the larger compressibility of the FeO6 octahedra suggests the evolution of the orthorhombic structure towards higher symmetry configuration at high pressures.     

星载激光多普勒测风雷达鉴频系统仿真(I):基于Fizeau干涉仪的Mie通道大气风速反演研究

研究了星载激光多普勒测风雷达系统结构,构建了基于Fizeau干涉仪的鉴频仿真系统,仿真研究了Mie通道风速反演算法,并利用无线电探空数据集仿真结果统计分析了Mie通道大气水平视线(HLOS)风速反演误差.仿真和统计结果表明,基于Fizeau干涉仪的Mie通道可反演低对流层大气风速;低对流层HLOS风速误差和标准差分别小于1 m·s-1和2 m·s-1;气溶胶和云的分布影响星载激光多普勒雷达测风误差,可使风速最大偏差增大一倍.     

Structural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressure

The structural stability and electrical properties of A1B2-type MnB2 were studied based on high pressure angle- dispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell （DAC） and first-principles calcu- lations under high pressure. The x-ray diffraction results show that the structure of A1B2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9~3.7 GPa with a fixed pressure derivative of 4, which indicates that A1B2-type MnB2 is a hard and incompressible material. The electrical resistance un- dergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.