Continuous-wave fiber cavity ring-down measurements using frequency-shifted interferometry

We present a spatial-domain fiber cavity ring-down (CRD) technique that does not require optical pulses for time-resolved detection. Instead of measuring the intensity decay rate of an optical pulse in the time domain as in conventional CRD experiments, we measure the decay rate of a CW signal in a ring-down cavity (RDC) using frequency-shifted interferometry in the spatial domain, as a function of distance traveled by the light. As a proof-of-concept demonstration, we measured fiber bend loss in a loop RDC using this technique, and a cavity loss change as low as 0.0135 dB induced by every fiber turn on a mandrel was unambiguously discerned.     

Effect of the thickness of InGaN interlayer on a-plane GaN epilayer

In this paper,we use the a-plane InGaN interlayer to improve the property of a-plane GaN.Based on the a-InGaN interlayer,a template exhibits that a regular,porous structure,which acts as a compliant effect,can be obtained to release the strain caused by the lattice and thermal mismatch between a-GaN and r-sapphire.We find that the thickness of InGaN has a great influence on the growth of a-GaN.The surface morphology and crystalline quality both are first improved and then deteriorated with increasing the thickness of the InGaN interlayer.When the InGaN thickness exceeds a critical point,the a-GaN epilayer peels off in the process of cooling down to room temperature.This is an attractive way of lifting off a-GaN films from the sapphire substrate.     

Generalized optical logic elements - GOLEs

A Generalized Optical Logic Element or GOLE is device that performs any of the 16 Boolean logic operations on signals in an optical beam with very fast switching among functions. The advantages of a generalized or universal gate in manufacturing are obvious. Extremely flexible functioning becomes possible if the GOLE functionality is switched in response to earlier computations. Likewise Field Programmable Gate Arrays or FPGAs can be used to fix the GOLE functions, making one of the most powerful and flexible processor units ever designed - called a Field GOLE. Such systems can be made in bulk optics to utilize Spatial Light Modulator or SLM capabilities, but integrated optics on silicon will be the choice for most applications. GOLEs can be generalized in several ways to become Fredkin gates and generalized Fredkin gates. They can also be cascaded similarly to electronic gates.     

三线摆实验中摆角偏大产生的误差及修正方法

研究了三线摆实验中摆角偏大(5°θ20°)时对测量转动惯量产生的误差和修正办法。实验发现随着摆角的增大,测得的圆盘转动惯量也会相应偏大,从而导致测量误差增大。文章通过进一步的理论分析解释了这一现象,并对测量结果进行了系统误差修正。     

基于单片机的电缆导通测试方法 

文章介绍了一种基于单片机的电缆导通测试方法。该方法以小型化、智能化为目标,采用了嵌入式设计,不仅使测试系统的体积大幅度降低,而且使操作界面更加简洁方便;系统采用C8051F120单片机做为核心控制器,以及技术成熟的万用表作为测量模块;通过设计接口电路,实现了单片机与液晶显示模块、微型打印机模块和键盘模块的互通;通过使用移位寄存器和继电器阵列,系统也实现了多个通道间的切换;系统用单片机驱动外部测量模块,完成了某型伺服系统电缆束的导通、不导通的测试;该测试方法改变了一直以来电缆导通测试需要依赖人工手动测试的现状,同时提高了测试的效率和准确性。     

A false color image fusion method based on multi-resolution color transfer in normalization YCBCR space

In this paper, a false color image fusion method for merging visible and infrared images is proposed. Firstly, the source images and reference image are decomposed respectively by Laplacian pyramid transform. Then the grayscale fused image and the difference images between the normalized source images are assigned to construct YC_BC_R components. In the color transfer step, all the three channels of the color space in each decomposition level are processed with the statistic color mapping according to the color characteristics of the corresponding sub-images of the reference image. Color transfer is designed based on the multi-resolution scheme in order to significantly improve the detailed information of the final image, and to reduce excessive saturation phenomenon to have a comparatively natural color appearance compared with the classical global-coloring algorithm. Moreover, the differencing operation between the normalized source images not only provides inter-sensor contrast to make popping the potential targets but also weakens the influence of the ambient illumination variety to a certain degree. Finally, the fused results and several metrics for evaluation of fused images subjectively and objectively illustrate that the proposed color image fusion algorithm can yield a more complete mental representation of the perceived scene, resulting in better situational awareness.     

Entropy production of Brownian macromolecules with inertia

We investigate the nonequilibrium steady-state thermodynamics of single Brownian macromolecules with inertia under feedback control in an isothermal ambient fluid. With the control being represented by a velocity-dependent external force, we find such an open system can have a negative entropy production rate, and we develop a mesoscopic theory consistent with the second law. We propose an equilibrium condition and define a class of external force, which includes the transverse Lorentz force, leading to equilibrium.     

对应原理的普遍意义——科学与人文漫话之十四

论述了对应原理提出的历史背景,讨论了对应原理的基本内容、普遍意义及其推广到社会领域的表述.     

Co50Fe25-xMnxSi25系列合金的结构、磁性和半金属性研究

利用实验和能带计算相结合的方法,对介于两种预期的半金属Heusler合金Co₂FeSi和Co₂MnSi间的四元合金Co₅₀Fe_25-xMn_xSi₂₅的晶体结构、磁性、能带结构和半金属性进行了研究.采用考虑库仑相互作用的的广义梯度近似方法计算了系列合金的能带结构,通过与实验结果进行对比,揭示了成分变化过程中合金分子磁矩及原子磁矩的变化规律.研究发现, 关键词： 磁性 半金属 Heusler合金