Study of curved and planar frequency-selective surfaces withnonplanar illumination

A locally planar technique (LPT) is investigated for determining the forward scattered field from a generally shaped inductive frequency-selective surface (FSS) with nonplanar illumination. The results of an experimental study are presented to assess the LPT accuracy. The effects of a nonplanar incident field are determined by comparing the LPT numerical results with a series of experiments with the feed source placed at varying distances from the planar FSS. The limitations of the LPT model due to surface curvature are investigated in an experimental study of the scattered fields from a set of hyperbolic cylinders of different curvatures. From these comparisons, guidelines for applying the locally planar technique are developed     

Covariant-projection quadrilateral elements for the analysis ofwaveguides with sharp edges

Covariant-projection elements are shown to be a good way of finding the dispersion characteristics of arbitrarily shaped waveguides. They have been demonstrated to produce no spurious modes, and because only tangential continuity is imposed between elements, either the electric field or the magnetic field may be calculated in the presence of dielectric and magnetic materials. Waveguides with sharp metal edges may be analyzed more efficiently than with other methods. Results are presented for a rectangular waveguide half loaded with dielectric, a double-ridged waveguide, a shielded microstrip line, and coupled microstrip lines on a cylindrical substrate. The matrices generated are sparse. and the number of zero eigenvalues produced is predictable. It therefore seems likely that the algebraic problem can be solved by sparse techniques, which would make the method applicable to even more complicated geometries at a modest computational cost     

Capacitance DNA bio-chips improved by new probe immobilization strategies

Label-free DNA detection plays a crucial role in developing point-of-care biochips. Capacitance detection is a promising technology for label-free detection. However, data published in literature often show evident time drift, large standard deviation, scattered data points, and poor reproducibility. To address these problems, mercapto-hexanol or similar alkanethiols are usually considered as blocking agents. The aim of the present paper is to investigate new blocking agents to further improve DNA probe surfaces. Data from AFM, SPR, florescence microscopy, and capacitance measurements are used to investigate new lipoate and ethylene-glycol molecules. The new surfaces offer further improvements in terms of diminished detection errors. Film structures are investigated at the nano-scale to justify the detection improvements in terms of probe surface quality. This study demonstrates the superiority of lipoate and ethylene-glycol molecules as blocking candidates when immobilizing molecular probes onto spot surfaces in label-free DNA biochip.     

汽车电子系统要求低静态电流

如今的汽车电子系统越来越复杂。同时，汽车环境对任何电子产品来说都是很大的挑战，因为汽车电子系统要求运行电压很宽，并且有很大的瞬态电压和温度变化。另外，性能要求也越来越高，需要多个供应电压以满足系统的不同要求。典型的     

Investigation of the fluid/structure interaction phenomenon in IC packaging

In the present study, experiment and simulation studies were conducted on the fluid/structure interaction (FSI) analysis of integrated circuit (IC) packaging. The visualisation of FSI phenomenon in the actual package is difficult due to limitations of package size, available equipment, and the high cost of the experimental setup. However, the experimental data are necessary to validate the simulation results in the FSI analysis of IC packaging. Scaled-up package size was fabricated to emulate the encapsulation of IC packaging and to study the effects of FSI phenomenon in the moulded package. The interaction between the fluid and the structure was observed. The deformation of the imitated chip was studied experimentally. The air-trap mechanism that occurred during the experiment is also presented in this paper. Simulation technique was utilised to validate the experimental result and to describe the physics of FSI. The predicted flow front was validated well by the experiment. Hence, the virtual modelling technique was proven to be excellent in handling this problem. The study also extends FSI modelling in actual-size packaging.     

嵌入式POL DC/DC转换器设计

大多数嵌入式系统都是通过48V背板供电的。这个电压通常要降为更低的12V或5V中间电压,以向系统内的电路板供电。然而,在这些电路板上,大多数电路都要求供电电压范围在0.8V～3.3V,电流范围为几十mA至几十A。因此,需要负载点(POL)DC/DC转换器对12V或5V降压,以获得所需的电压和电流值。     

Hydration-Induced Void-Containing Hydrogels for Encapsulation and Sustained Release of Small Hydrophilic Molecules

Efficient encapsulation and sustained release of small hydrophilic molecules from traditional hydrogel systems are challenging due to the large mesh size of 3D networks and high water content. Furthermore, the encapsulated molecules are prone to early release from the hydrogel prior to use, resulting in a short shelf life of the formulation. Here, a hydration-induced void-containing hydrogel (HVH) based on hyperbranched polyglycerol-poly(propylene oxide)-hyperbranched polyglycerol (HPG-PPG-HPG) as a robust and efficient delivery system is presented for small hydrophilic molecules. Specifically, after the HPG-PPG-HPG is incubated overnight at 4 °C in the drug solution, it is hydrated into a hydrogel containing micron-sized voids, which can encapsulate hydrophilic drugs and achieve 100% drug encapsulation efficiency. In addition, the voids are surrounded by a densely packed polymer matrix, which restricts drug transport to achieve sustained drug release. The hydrogel/drug formulation can be stored for several months without changing the drug encapsulation and release properties. HVH hydrogels are injectable due to shear thinning properties. In rats, a single injection of the HPG-PPG-HPG hydrogel containing 8 µg of tetrodotoxin (TTX) produces sciatic nerve block lasting up to 10 h without any TTX-related systemic toxicity nor local toxicity to nerves and muscles.     

期待理想DC

看了11月杂志上的特别策划《数码相机IQ大调查》,平时见的祖机不少,对里面提到的几种技术发表点看法。1．智能场景,有用。好点的卡片相机都提供了越来越多的场景模式,往好了说是方便用户选择,其实是给用户添了麻烦,反正我平时拍照很少会去选择。如果相机能够帮我做出正确的选择当然是最好的,但它也要足够聪明才行。     

MPEG-4 Video and Image Coding on Digital Signal Processors

The emerging MPEG-4 standard encompasses a wide variety of applications, many of which are suitable for implementation on a Digital Signal Processor (DSP). In particular, consumer products with embedded multimedia capability, such as set-top boxes and wireless communicators, are suitable for DSP-based implementation. With a programmable approach, various algorithmic tradeoffs can be made, based on processing capability. For best performance, careful attention must be paid to memory allocation, data transfer, and ordering of instructions to best match the DSP architecture. We discuss implementing simple profile MPEG-4 video on the low-power TMS320C54x, core profile on the TMS320C6x, and scalable texture profile, which could be implemented on either processor family.     

Optimization of electromagnetic phased-arrays for hyperthermia via magnetic resonance temperature estimation

A technique for the optimization of electromagnetic annular phased arrays (APAs) for therapeutic hyperthermia has been developed and implemented. The controllable inputs are the amplitudes and phases of the driving signals of each element of the array. Magnetic resonance imaging (MRI) is used to estimate noninvasively the temperature distribution based on the temperature dependence of the proton resonance frequency (PRF). A parametric model of the dynamics that couple the control inputs to the resultant temperature elevations is developed based on physical considerations. The unknown parameters of this model are estimated during a pretreatment identification phase and can be continuously updated as new measurement data become available. Based on the parametric model, a controller automatically chooses optimal phases and amplitudes of the driving signals of the APA. An advantage of this approach to optimizing the APA is that no a priori information is required, eliminating the need for patient-specific computational modeling and optimization. Additionally, this approach represents a first step toward employing temperature feedback to make the optimization of the APA robust with respect to modeling errors and physiological changes. The ability of the controller to choose therapeutically beneficial driving amplitudes and phases is demonstrated via simulation. Experimental results are presented which demonstrate the ability of the controller to choose optimal phases for the APA using only information from magnetic resonance thermometry (MRT).