Michelson干涉仪式光纤空气声传感器

介绍了一种用于直升机等低空目标探测的光纤空气声传感器.该传感器基于光纤Michelson干涉仪的原理,结合弹性盘片的应力应变理论分析和光纤粘接的工艺设计,采用相位载波解调技术进行信号解调.对比实验测试验证了这种声音探测技术可行性.传感器理论灵敏度为2.38 rad/Pa,实测灵敏度为1.5 rad/Pa,采用PGC相位解调理论最小可探测的最小声信号为6.7 μPa,即9.5 dB.传感器在20～300 Hz范围内响应基本平坦.结合声音传播规律分析并肯定其在实用中的可行性.     

新大线同沟敷设热力分析

针对新大线同沟敷设管道,采用非结构化有限容积法,分析了不同的物性条件下,常温输送原油对加热输送原油的热力影响.     

栅极电势对强光场下石墨烯场效应管中电子隧穿的影响

利用时域有限差分方法研究了强光场下石墨烯场效应管中栅极电势对电子隧穿的影响. 在强光场下由于光学stark效应,石墨烯场效应管的完美手征透射被抑制.这种抑制除了 可以利用光场来调控外,也可以通过改变栅极电势的宽度、势垒高度等来调控. 研究了非方势垒中电子的隧穿. 研究发现,当电势的倾斜较小时,电子隧穿概率变化不大.而当电势倾斜很大时,电子隧穿概率急剧改变.     

Monte Carlo simulation of glandular dose in a dedicated breast CT system

A dedicated breast CT system (DBCT) is a new method for breast cancer detection proposed in recent years. In this paper, the glandular dose in the DBCT is simulated using the Monte Carlo method. The phantom shape is half ellipsoid, and a series of phantoms with different sizes, shapes and compositions were constructed. In order to optimize the spectra, monoenergy X-ray beams of 5-80 keV were used in simulation. The dose distribution of a breast phantom was studied: a higher energy beam generated more uniform distribution, and the outer parts got more dose than the inner parts. For polyenergtic spectra, four spectra of Al filters with different thicknesses were simulated, and the polyenergtic glandular dose was calculated as a spectral weighted combination of the monoenergetic dose.     

Enhancement of upconversion luminescence of YAlO3:Er3+ by Gd3+ doping

The upconversion luminescences of YAlO3:Er3+ phosphor co-doping with different Gd3+ concentrations are investigated under the excitation of 980- and 532-nm diode lasers. A near ultraviolet upconversion emission at 410 nm is observed in YAlO3 under 532-nm excitation. Moreover, the inactive Gd3+ ions can improve the upconversion intensity efficiently in a certain range of concentration. Under 980-nm excitation, the visible upconversion emissions at 546 and 646 nm are enhanced by about 10 and 8 times at the Gd3+ concentration of 40%, respectively. The upconversion emission at 410 nm under 532-nm excitation is also enhanced by 7 times. The substitution of Gd3+ ions for Y3+ sites changes the local symmetry of Er3+, leading to the improvement of upconversion efficiency.     

The formation of different structures in the interaction between a single femtosecond laser pulse and a thin Au film

The interactions between femtosecond (fs) laser pulses and a thin Au film deposited on a silica glass substrate were systematically investigated based on experimental data. Different structures, including microholes, nanoholes, and nanobumps, are obtained when pulses with different energies are incident on the surface of a gold film. The experimental results are discussed according to specific experimental parameters. Two physical models were constructed in order to explain the experimental results. The formation of nanoholes in a silica substrate is attributed to etching by higher order harmonic generations (HHG) when the femtosecond laser pulse interacts with the generated plasma layer, while the formation of nanobumps on the surface of an Au film is attributed to the elastic and plastic characteristics of the metal film under laser pulse irradiation.     

卷绕式螺旋形薄膜介质脉冲形成线设计

采用模块化结构,设计了一种卷绕式螺旋形薄膜介质脉冲形成线,并且对绝缘材料、电极材料的选择依据进行了分析。基于模块化卷绕式脉冲形成线,研制的重复频率脉冲方波产生器采用4个开关同步触发四级形成线模块,从而实现多模块的电压串联叠加,以达到产生高压的目的。开关采用气体火花间隙开关,每级开关及充放电采用电感隔离。研制的脉冲产生器输出电压220 kV,脉冲宽度182 ns,前沿50 ns,可10 Hz重复频率稳定运行。     

利用自电离探测技术研究Sm原子Rydberg态光谱

采用孤立实激发与自电离探测技术相结合的方法对Sm原子偶宇称高激发态进行了系统研究.按照不同的自电离通道将所测数据进行了分类和比较,并进行了详细讨论.不仅报道了许多收敛于不同电离限的Rydberg态的能级位置和跃迁的相对强度等信息,而且还把处于同一能域内的Rydberg态和价态进行了辨识.另外,不但提供了一种有效识别不同类型的高激发态的鉴别技术,而且还对处于41800 cm^-1到43800 cm^-1能域内的Rydberg态和价态的光谱特性进行了详细分析和讨论. 关键词： 自电离探测 Rydberg态 Sm原子     

Study on the relations of sensitivity with energy properties for HMX and HMX-based PBXs by molecular dynamics simulation

Molecular dynamics simulation was applied to study the structure and energy properties of β-HMX (β-cyclotetramethylene tetranitramine) crystal and its composite PBXs (polymer-bonded explosives) with F₂₃₁₁ as a polymer binder under different temperatures and F₂₃₁₁ concentrations. The interface interaction energy of HMX and F₂₃₁₁, the interaction energy E_N–N between N atoms in N–NO₂ trigger bond in HMX molecules, and the cohesive energy density (CED) are presented and analyzed. A meaningful finding is that there exists correlation between E_N–N and the sensitivity of β-HMX and its composites, i.e. the less the E_N–N is, the larger the sensitivity is. Additionally, molecular interactions are inherently disclosed by using pair correlation function (PCF) to analyze the interfacial structure between (1 0 0)HMX crystal surface and F₂₃₁₁ molecular chain.     

非马尔可夫环境下经典场驱动Jaynes-Cummings模型中原子的熵压缩

运用非马尔可夫量子理论与熵压缩理论,研究了非马尔可夫环境下经典场驱动Jaynes-Cummings模型中原子的熵压缩,考察了非马尔可夫效应、经典场驱动、体系失谐量对原子熵压缩的影响.用非马尔可夫过程的记忆效应解释了原子熵压缩的动力学行为.结果表明:非马尔可夫效应和经典场驱动的共同作用有利于原子熵压缩的产生与维持.在非马尔可夫环境下,通过选择适当的系统参数,可以产生压缩度大、压缩持续时间长的原子熵压缩态.研究结果为利用光场-原子相互作用制备压缩度大、压缩持续时间长的最佳原子压缩态提供了可能途径.