An electromigration failure model for interconnects under pulsedand bidirectional current stressing

An electromigration failure model which can be used to project the electromigration lifetime under pulsed DC and AC current stressing has been reported. The experimental results indicate that different metallization systems (Al-2%Si, Al4%Cu/TiW, and Cu) show similar failure behaviors, which can be explained and predicted by this model. The pulsed DC lifetime is found to be longer than DC lifetime, and the AC lifetime is found to be very much longer. This recognition can provide significant relief to circuit designs involving metals carrying pulsed DC and AC currents, and allow a more aggressive design to improve circuit density and speed     

内嵌闪存MCU的高性能多通道24位采集系统ADuC845

ADuC845是ADI公司新推出的嵌有单指令周期8052闪存MCU、带两路24位∑ -△A/D、双12位D/A以及两个灵活脉宽调制输出的高性能24位数据采集与处理系统芯片。该芯片的数据处理速度达12MIPS,且设计简单 ,噪声低 ,非常适用于精密仪器仪表。文中详细介绍了该芯片的功能特点和工作原理 ,给出了该芯片的应用方法。     

Investigation of Infrared Photonic Crystal Slab with Defect Waveguides

This paper deals with the two dimensional (2-D) infrared photonic crystal slab with an air-bridge structure featuring defect waveguides in which the optical propagation properties were obtained by measurements of transmission spectra. 3-D finite-difference time-domain (FDTD) simulations have revealed the appearance of four defect propagation modes for the band structure and transmission spectra in the air-bridge slab. These defect modes were experimentally identified in the measured transmission spectra.     

Inside Front Cover: Three‐Dimensionally Ordered Gold Nanocrystal/Silica Superlattice Thin Films Synthesized via Sol–Gel Self‐Assembly (Adv. Funct. Mater. 7/2006)

The synthesis of three‐dimensionally ordered, transparent gold‐nanocrystal (NC)/silica superlattice thin films using the self‐assembly (by spin‐coating) of water‐soluble gold nanocrystal micelles and soluble silica is reported by Fan and co‐workers on p. 891. The robust, 3D NC/silica superlattice films are of interest for the development of collective optical and electronic phenomena, and, importantly, for the integration of NC arrays into device architectures. Nanocrystals and their ordered arrays hold many important applications in fields such as catalysis, surface‐enhanced Raman spectroscopy based sensors, memory storage, and electronic and optical nanodevices. Herein, a simple and general method to synthesize ordered, three‐dimensional, transparent gold nanocrystal/silica superlattice thin films by self‐assembly of gold nanocrystal micelles with silica or organosilsesquioxane by spin‐coating is reported. The self‐assembly process is conducted under acidic sol–gel conditions (ca. pH 2), ensuring spin‐solution homogeneity and stability and facilitating the formation of ordered and transparent gold nanocrystal/silica films. The monodisperse nanocrystals are organized within inorganic host matrices as a face‐centered cubic mesostructure, and characterized by transmission electron spectroscopy and X‐ray diffraction.     

Grid‐free surface vorticity method applied to flow induced vibration of flexible cylinders

In order to study cross flow induced vibration of heat exchanger tube bundles, a new fluid–structure interaction model based on surface vorticity method is proposed. With this model, the vibration of a flexible cylinder is simulated at Re=2.67 × 10⁴, the computational results of the cylinder response, the fluid force, the vibration frequency, and the vorticity map are presented. The numerical results reproduce the amplitude‐limiting and non‐linear (lock‐in) characteristics of flow‐induced vibration. The maximum vibration amplitude as well as its corresponding lock‐in frequency is in good agreement with experimental results. The amplitude of vibration can be as high as 0.88D for the case investigated. As vibration amplitude increases, the amplitude of the lift force also increases. With enhancement of vibration amplitude, the vortex pattern in the near wake changes significantly. This fluid–structure interaction model is further applied to simulate flow‐induced vibration of two tandem cylinders and two side‐by‐side cylinders at similar Reynolds number. Promising and reasonable results and predictions are obtained. It is hopeful that with this relatively simple and computer time saving method, flow induced vibration of a large number of flexible tube bundles can be successfully simulated. Copyright © 2004 John Wiley & Sons, Ltd.     

激光对改变胰岛致免疫性的影响

新生猪胰岛样细胞团经准分子激光照射预处理后，其免疫原性明显降低，表明经激光预处理，有可能延长移植物存活时间。     

适用于LED显示屏或照明工程的异步控制卡DS2000-M1

DS2000-M1是高性能、开放式的LED控制系统,本文从软硬件两方面简述其设计原理。     

复杂形体目标激光散射特征测量系统的研制

复杂形体目标激光散射特征的测量系统中，利用反射式离轴光路满足了可见到远红外波段的测量需要，通过大孔径（250mm）物方远心接收光路实现了对实际远场的模拟测量，以光滑镀金球体作为标准器，可直接获得任意目标散射截面的绝对值。在0．6328、1．06和10．6μm三个波段针对标准器的实测结果表明，平均误差小于4．95％。     

Chiral separation of synthetic vicinal diol compounds by capillary zone electrophoresis with borate buffer and beta-cyclodextrin as buffer additive.

The investigation on capillary electrophoretic enantioseparation of six synthetic compounds containing vicinal diol groups has been undertaken to acquire the optimum conditions using native beta-cyclodextrin (beta-CD) as chiral selector and borate as a background electrolyte. The separation was carried out in an uncoated capillary (58.5 cm x 75 microm i.d., effective length 48.5 cm) and the effects of several important factors were investigated in detail. The results showed that beta-CD as a chiral selector exhibited good enantioselectivity and that the enantioseparation was greatly influenced by the structure of the diols, the borate concentration and the buffer pH. The optimum performance was obtained for the chiral vicinal diols under the conditions of 200 mM borate buffer of pH 9.8 containing 1.7% beta-CD at an applied voltage of 15 kV and a capillary temperature of 20 degrees C. Under the conditions, four diols were baseline separated with fast analysis time and the good theoretical plate numbers (above 10 x 10(4)) and favorable migration-time reproducibilities (RSDs below 3.0%) were obtained. The separation results were satisfactory.     

Some existence results on periodic and generalized periodic solutions for singular hamiltonian systems

In this paper, we use the variational method to study the existence of periodic and generalized periodic solutions of planar second order Hamiltonian systems when a singular potential is present. The results obtained are applied to the study of generalized periodic solutions of the Restricted Three-Body Problem and the Planarn-Body Problem.