Micro squeeze flow rheometer for high frequency analysis of nano-litre volumes of viscoelastic fluid

In this paper, the design, fabrication and experimental analysis of a piezoelectrically actuated micro squeeze flow rheometer is presented. Being only 30 × 30 × 0.5 mm in size, the micro rheometer is sensitive to very small volumes of the order of 1-10 nL of liquid and light enough to operate at frequencies in the kHz regime, an order of magnitude higher than normally attainable with conventional cone and plate rheometry. Initial experiments show that the response of the rheometer is dependent on the viscoelasticity of the fluid being tested. The prototype was used to measure the moduli of poly(dimethylsiloxane) (PDMS) of viscosity 10 Pa s, a non-volatile viscoelastic fluid, over the frequency range of 10-1000 Hz. Results show good agreement between with the moduli measured using conventional rheometry up to 100 Hz and with values extrapolated up to 1 kHz.     

SIMULTANEOUS MULTIPLE TARGET RECOGNITION USING POLARIZATION AGILE WAVES

A novel matching method for simultaneous multi-target recognition is proposed by jointly considering target’s prior scattering knowledge and the polarization parameters of radar echoes. The matching coefficients are calculated for the judgment. MATLAB simulations show that several targets can be accurately recognized simultaneously, and a high recognition probability can be achieved in Monte Carlo simulations. The total execution time can be remarkably reduced in the Field Programmable Gate Array (FPGA) implementation of the matching procedure.     

基于宽带均匀同心球阵列的低复杂度二维波达方向估计算法

该文提出一种基于宽带均匀同心球阵列(UCSA)的2维波达方向(2D-DOA)低复杂度估计算法.该方法将宽带UCSA输出信号转换为相位模式,并对其进行频率补偿,实现近似频率不变(FI)特性,从而降低宽带信号处理的计算复杂度.为了进一步降低2D-DOA估计的计算复杂度,该文提出基于FI-UCSA的降维多重信号分类(MUSI...     

Application of Wet Chemical Etching in Fabrication Process of GaAs/AlGaAs Quantum Dot Arrays

Two types of GaAs/AlGaAs quantum dot arrays with different dot size are fabricated by dry etching and dry-wet etching. PL spectra of the quantum dot arrays at low temperature show the blue shifts due to the quantization confinement effects, and the blue-shift increases with the decrease of the dot size. It is also found that wet chemical etching can reduce the surface damage caused by high-energy ion etching and improve the optical characteristics of the quantum dot arrays.     

铁镍合金纳米线阵列的制备与穆斯堡尔谱研究

用交流电化学沉积方法在阳极氧化铝模板中成功地制备了直径约16nm,长度4μm的Fe_1-xNi_x(0关键词： 纳米线阵列 穆斯堡尔谱 铁镍合金     

高性能128×128元PtSi肖特基势垒红外焦平面列阵

设计并研制成功128×128元 PtSi 肖特基势垒红外 CCD(PtSi-SBIRCCD)焦平面列阵。介绍了该器件的工作原理。阐述了器件结构和设计思想,并就器件的性能参数进行了研究。     

An approach for low sidelobe beamforming in uniform concentric circular arrays

In this paper, a new tapered beamforming function for sidelobe reduction in the uniform concentric circular arrays (UCCA) is proposed. This technique is based on tapering the current amplitudes of the rings in the array, where all elements in an individual ring are weighted in amplitude by the same value and the weight values of different rings are determined by a function that has a normalized-gaussian probability density function variation. This novel tapering window is optimized in its parameters to have the lowest possible sidelobe level that may reach 43 dB below the main lobe and these optimum weights are found to be function of the number of elements of the innermost ring and the number of rings in the array. The proposed tapering window can be modified to compensate the gain reduction due to tapering when compared with the uniform feeding case.     

Characterization of solid state array cameras for the mid-IR

We present a characterization of some processes affecting the performance of solid state array cameras designed for ground based astronomical imaging in the 8–13m atmospheric window. Our discussion includes a novel model for electron-hole generationrecombination noise based on the probable pathlength of an electron in a photoconductor. We use the Berkeley mid-IR Array Camera as an example. For this camera, the results show that the total optical system composed of the camera, a 3m telescope, and the atmosphere has an efficiency of about 3%, a 1 noise equivalent flux density of 25 mJy min^–1/2arcsec^–2 measured over a /=10% band width, and a noise equivalent expressed as the ambient temperature thermal black body noise of 23%.     

Electrochemical Redundant Microsensor Arrays for Glucose Monitoring with Patterned Polymer Films

Redundant microsensor arrays for glucose sensing were fabricated using photopolymerization of poly(ethylene glycol) diacrylate (PEG‐DA) with 2‐hydroxy‐2‐methyl phenyl‐propanone as photoinitiator to encapsulate the enzyme glucose oxidase. Silicon micro fabrication technologies were used to fabricate microelectrode sensor arrays on flexible polyimide sheets. These microarray sensors were individually addressable as observed using square‐wave voltammetry. Redox polymer, poly[4‐vinylpyridine Os(bipyridine)₂Cl]‐co‐ethylamine, was first immobilized on the electrode surface and then glucose oxidase was entrapped in PEG‐DA hydrogels. The redox polymer was found to exchange electrons with glucose oxidase in biocompatible PEG‐DA hydrogels. The entrapped glucose oxidase was found to respond linearly to glucose in solution (0–20 mM) as determined using square‐wave voltammetry.