级联二阶非线性铌酸锂全光开关的研制

以基于准位相匹配和频与差频级联二阶非线性[X^(2)：X^(2)]基础上的全光开关的理论分析作指导,进行了周期极化铌酸锂晶体(PPLN)和退火质子交换光波导(APE)的实验制备,利用所研制的PPLN-APE器件,以自行研制的工作波长为1．54μm的被动调Q掺钴铝酸镁激光器作为控制光源,以工作波长为1．5μm的连续二极管激光器为信号光源进行了级联二阶非线性全光开关实验。当控制光峰值功率为3kw,信号光功率为1mW时,实现13％的开关效率,分析了进一步提高全光开关性能的途径。     

采用选择激发研究光系统Ⅱ反应中心β-Car的物理特性

光系统Ⅱ反应中心包含有2个去镁叶绿素分子(Pheo),2个β胡萝卜素分子(β-Car)和6个叶绿素a分子(Chla).对反应中心的时间分辨荧光光谱表明,两个β-Car具有不同的吸收光谱,吸收峰分别为489 nm(Car489)和507 nm(Car507),Car489靠近吸收峰为667 nm和675 nm的叶绿素a(Chl a),它的主要功能是保护反应中心免受单态氧的破坏,而不能将激发能传递给光化学反应活性的色素分子P680;Car507靠近吸收峰为669 nm的Chl a分子;能够将激发能传递给P680,进行电荷分离.采用全局优化拟合的方法对荧光光谱进行处理,Car489在61 ps时间内将能量传递给Chl a672, 随后传给Chl a677,处于激发态的Chl a677在3 ns衰减到基态;Car507在274 ps时间内将能量传递给P680,P680＋Pheo-的电荷重组发生在3.8 ns和16 ns.     

捕光复合物LHCⅡ的荧光动力学特性

采用时间分辨荧光光谱技术,在273 K下用波长为507 nm的光激发对菠菜光系统Ⅱ捕光天线LHCⅡ的光谱特性和时间特性作了研究.将获得的荧光光谱进行高斯解析,得到6个光谱组分,反映了光谱特性：Chl a６６２６６０／６６１、Chl a/b６７２６７０／６７１、Chl a６８３.5６８０／６８１和Chl a６９９.9６９５.0,而中心波长为738.6nm、761.0 nm的光谱组分则可能对应着主发射峰的振动副带.通过对荧光衰减曲线进行三指数时间拟合,得到激发能在LHCⅡ中传递的时间常数：8.8 ps、500 ps、1.6 ns,并分析得出了时间常数与光谱组分的对应关系.     

二(1-正丁基茚基)四羰基二钌的合成与晶体结构

由C9H6-n-BuH与Ru3(CO)12在二甲苯中加热回流, 合成了一个新的双核配合物(η5-C9H6-n-Bu)2Ru2(CO)4. 通过元素分析、红外光谱、核磁共振氢谱对其结构进行了表征. 用X射线单晶衍射法测定了(η5-C9H6-n-Bu)2Ru2(CO)4的结构, 结果表明: 晶体属于三斜晶系, Pī空间群, a＝0.8880(5) nm, b＝1.2337(8) nm, c＝1.3235(8) nm, α＝83.054(12)°, β＝76.683(10)°, γ＝77.036(12)°, V＝1.3713(15) nm3, Dc＝1.588 g•cm－3, m＝1.134 mm－1, F(000)＝658, Z＝2, R1＝0.0993, wR2＝0.2459.     

微量稀土对奥氏体耐热钢高温力学性能的影响

研究了微量稀土对Cr21Ni11N奥氏体耐热不锈钢高温热塑性及高温持久性能的影响.结果表明:在750～1250℃范围内,稀土显著提高耐热钢的热塑性,消除800℃的塑性低凹区,扩宽安全热加工温度范围近75℃.稀土显著延长耐热钢的高温持久寿命约3～5倍,并提高持久断裂塑性.钢中添加稀土后,其蠕变断裂机制由楔形裂纹为主的机制逐渐转变为空洞裂纹为主的机制,高温持久断口附近的楔形裂纹明显减少,且断口呈典型的韧窝状塑性断口特征.     

双面碎片的英文文件复原方法研究

对英文材料的双面规则碎片文件复原问题进行了研究.由于碎片边界是规则的几何形状,无法采用几何形状匹配算法进行复原,为此提出了基于碎片边缘像素特征的匹配复原算法,建立了双面二维灰度匹配数学模型.通过加入行约束条件,减少横向匹配中的纵向误差,并通过消除列匹配中的误差,优化了匹配算法.该模型可以实现块状双面英文碎片的完整复原.     

基于质量控制的供应链计划问题研究

为了研究基于质量控制的供应链计划问题,采用了优化建模的方法,分析了易腐物品生命周期函数的选用及拟合原则,建立起了质量衰减成本与时间之间的关系,考虑了涉及交通及天气情况的运输风险,最终建立了优化模型,以实现供应链运行总成本最小。最后,提出了动态规划的求解方法,并通过仿真实验证明了算法的有效性。     

The influence of thermally assisted tunneling on the performance of charge trapping memory

We evaluate the influence of the thermally assisted tunneling (TAT) mechanism on charge trapping memory (CTM) cell performance by numerical simulation, and comprehensively analyse the effects of the temperature, trap depth, distribution of trapped charge, gate voltage and parameters of TAT on erasing/programming speed and retention performance. TAT is an indispensable mechanism in CTM that can increase the detrapping probability of trapped charge. Our results reveal that the TAT effect causes the sensitivity of cell performance to temperature and it could affect the operational speed, especially for the erasing operation. The results show that the retention performance degrades compared with when the TAT mechanism is ignored.     

Adaptive optimization on ultrasonic transmission tomography-based temperature image for biomedical treatment

Hyperthermia has proven to be beneficial to treating superficial malignancies, particularly chest wall recurrences of breast cancer. During hyperthermia, monitoring the time–temperature profiles in the target and surrounding areas is of great significance for the effect of therapy. An ultrasound-based temperature imaging method has advantages over other approaches. When the temperature around the tumor is calculated by using the propagation speed of ultrasound, there always exist overshoot artifacts along the boundary between different tissues. In this paper, we present a new method combined with empirical mode decomposition(EDM), similarity constraint, and continuity constraint to optimize the temperature images. Simulation and phantom experiment results compared with those from our previously proposed method prove that the EMD-based method can build a better temperature field image, which can adaptively yield better temperature images with less computation for assistant medical treatment control.     

Study of the temperature rise induced by a focusing transducer with a wide aperture angle on biological tissue containing ribs

We used the spheroidal beam equation to calculate the sound field created by focusing a transducer with a wide aperture angle to obtain the heat deposition, and then we used the Pennes bioheat equation to calculate the temperature field in biological tissue with ribs and to ascertain the effects of rib parameters on the temperature field. The results show that the location and the gap width between the ribs have a great influence on the axial and radial temperature rise of multilayer biological tissue. With a decreasing gap width, the location of the maximum temperature rise moves forward; as the ribs are closer to the transducer surface, the sound energy that passes through the gap between the ribs at the focus decreases,the maximum temperature rise decreases, and the location of the maximum temperature rise moves forward with the ribs.