Characterization of electrically-assisted micro-rolling for surface texturing using embedded sensor

Electrically-assisted micro-rolling (EAμR) takes advantage of localized heating by loading current through the deformation zone to enhance the texturing capability of Ti-6Al-4V and AA3003-H14. The challenge to achieve a desired deformation pattern is the lack of reliable models to capture the often non-uniform mechanical and thermal behaviors. In this paper, pressure distributions are measured by a custom-designed, tool-embedded sensor. Furthermore, the effects of current on texturing are first characterized using a coupled mechanical and thermal model. Comparison between modeling and experimental results confirmed the effectiveness of EAμR on texturing and the importance of multi-physics modeling.     

计及反馈信号多时滞特性的广域阻尼控制

广域测量系统是由多种通信媒质组成的复杂网络系统。由于不同通信媒质和装置的通信延迟时间各异且具有随机性，闭环电力系统在数学上是一个典型的非线性、多时滞且变时滞的动力系统。文中首先将非线性多时滞的系统模型线性化为线性多时滞的模型，然后分析了线性多时滞系统的稳定时滞域的拓扑性质，最后根据其拓扑性质设计了对时滞的异步变化不敏感的广域阻尼控制器。时域仿真结果表明:对于2区4机系统，当区内通信和区间通信分别具有不同时滞及其随机性的情况下，所设计的控制器仍能有效阻尼区间联络线上的低频振荡。     

Anomalous enhancement of fluorescence of carbon dots through lanthanum doping and potential application in intracellular imaging of ferric ion

An anomalous enhancement of fluorescence of carbon dots (CDs) was observed via lanthanum (La) doping. La-doped CDs (La-CDs) were prepared through microwave pyrolysis within 4 min. With La³⁺ doping, the emission band shifted from blue to green although La³⁺ is non-fluorescent. The quantum yield and fluorescence lifetime improved by about 20% and 35%, respectively. All experiment results indicate that La³⁺ doping is an effective way to tune fluorescence and improve the performance of CDs. Another unique attribute of La-CDs is high sensitivity to Fe³⁺. The La-CD-based fluorescence probe was established and used for sensitive and selective detection of Fe³⁺ with a limit of detection of 91 nmol/L. The proposed fluorescence probe also was successfully employed to visualize intracellular Fe³⁺ in live HeLa cells through cell imaging. It was also shown that yttrium exhibited the same fluorescence enhancement effect as La. The results may provide a new route for preparing CDs with special properties.

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消防服热防护性能检测用热传感器的研究

叙述了消防服热防护性能检测对热传感器的具体要求,对四种应用在该领域的热传感器进行了比较和分析,概述其性能和特点。     

Theoretical representation of shear and pressure influence on the phase separation behavior of PVME/PS mixture

In the framework of lattice fluid model, the Gibbs energy and equation of state are derived by introducing the energy (E_s) stored during flow for polymer blends under shear. From the calculation of the spinodal of poly(vinyl methyl ether) (PVME) and polystyrene (PS) mixtures, we have found the influence of E_s on equation of state in pure component is inappreciable, but it is appreciable in the mixture. However, the effect of E_s on phase separation behavior is extremely striking. In the calculation of spinodal for the PVME/PS system, a thin, long and banana miscibility gap generated by shear is seen beside the miscibility gap with lower critical solution temperature. Meanwhile, a binodal coalescence of upper and lower miscibility gaps is occurred. The three points of the three-phase equilibrium are forecasted. The shear rate dependence of cloud point temperature at a certain composition is discussed. The calculated results are acceptable compared with the experiment values obtained by Higgins et al. However, the maximum positive shift and the minimum negative shift of cloud point temperature guessed by Higgins are not obtained. Furthermore, the combining effects of pressure and shear on spinodal shift are predicted.     

应用光纤光栅和虚拟仪器的切削力测量技术

在分析光纤光栅应变传感器原理的基础上,针对切削力测量的需要,设计出了光纤光栅传感器各项参数,简化了测试仪器结构,避免了温度对测量精度的影响。在虚拟仪器平台上开发了测试数据处理和自动化管理的程序,介绍了LabVIEW环境中建立切削力经验公式的简单方法。     

单片机在自动供水控制系统中的应用

MCS-51系列单片机具有丰富的I/O口,定时器以及中断系统等硬件资源和功能较强的指令系统,特别适用于控制领域中的应用。本文介绍的自动供水设备采用了以单片机为核心的控制系统,具有自动化程度高、结构简单、成本低等特点。     

一个柴油机驱动的复合制冷循环

介绍了一个用柴油机驱动的复合制冷循环，即用柴油机主机带动压缩式循环，同时利用柴油机排气和缸套水的热量作源驱动吸收式循环。热力学分析和数值计算表明，此复合循环由于实现了不同品位热源的合理利用，减少了不可逆损失，其能效比普通式循环或直燃式吸收循环可分别提高19％和58％。     

Multiple scattering simulations for the Japanese space lidarproject ELISE

Spaceborne lidar observations have a great potential to improve our knowledge of the atmosphere. However, contrary to ground-based or airborne lidar measurements in observations from space multiple scattering (MS) has to be accounted for under all atmospheric conditions. A simple way to achieve this is to introduce the approximative MS factor F in the single scattering lidar equation. We determined F for measurements of aerosols, ice and water clouds as they were planned with the Japanese space lidar ELISE. We found that F is almost constant in cirrus clouds and in water clouds which are penetrable by lidar. In aerosol layers F depends on penetration depth, extinction coefficient and aerosol type. In comparison to LITE the MS factor is smaller (for aerosols and water clouds) or almost equal (cirrus)     

基于密钥图像的加密技术

基于密钥图像的加密技术主要采用自然图像的傅立叶变换的相位作为密钥,并和另一幅图像的相位谱(phasespectrum)进行相加,实现图像加密。研究发现,用该密钥同时对两幅以上图像进行加密时,则用独立变量分析法可有效分离出密钥或原图像。本文提出一种相位调制(modulate0)方法,可有效保护密钥,确保加密图像的安全性。