Microstructure coarsening during static annealing of 60Sn40Pb solder joints: III intermetallic compound growth kientics

The growth of the total (Cu₃Sn+Cu₆Sn) intermetallic compound layer in Cu-60Sn40Pb solder joints during static annealing at 50°C to 150°C was described by the equation hi=h_o+A_o exp(−Q_a/RT)t^p with h_o=0–0.3 μm, p=0.38–0.70, A_o=1.9×10⁻⁴–3.4×10⁻⁴ m/s^p, and Q_a=25.5–30.9 kJ/mole. These constants are within the range of those obtained by others and give values of D_o and Q which are in reasonable accord with those for the diffusion coefficients in Cu₃Sn and Cu₆Sn₅ determined in diffusion couples. The deviation of the values of the time exponent p from the ideal of 0.5 for diffusion growth may be due to inaccuracies or errors pertaining to the measured thickness (especially h_o) and the complex nature of the diffusion process.     

Integration of InGaP/GaAs/Ge triple‐junction solar cells on deeply patterned silicon substrates

We report preliminary results on InGaP/InGaAs/Ge photovoltaic cells for concentrated terrestrial applications, monolithically integrated on engineered Si(001) substrates. Cells deposited on planar Ge/Si(001) epilayers, grown by plasma‐enhanced chemical vapor deposition, provide good efficiency and spectral response, despite the small thickness of the Ge epilayers and a threading dislocation density as large as 10⁷/cm². The presence of microcracks generated by the thermal misfit is compensated by a dense collection grid that avoids insulated areas. In order to avoid the excessive shadowing introduced by the use of a dense grid, the crack density needs to be lowered. Here, we show that deep patterning of the Si substrate in blocks can be an option, provided that a continuous Ge layer is formed at the top, and it is suitably planarized before the metalorganic chemical vapor deposition. The crack density is effectively decreased, despite that the efficiency is also lowered with respect to unpatterned devices. The reasons of this efficiency reduction are discussed, and a strategy for improvement is proposed and explored. Full morphological analysis of the coalesced Ge blocks is reported, and the final devices are tested under concentrated AM1.5D spectrum. Copyright © 2016 John Wiley & Sons, Ltd.     

Qualitative and quantitative evaluation of heart sound reduction from lung sound recordings

Recursive least squares (RLS) adaptive noise cancellation (ANC) and wavelet transform (WT) ANC have been applied and compared for heart sound (HS) reduction from lung sounds (LS) recordings. Novel processes for quantitative and qualitative evaluation of any method for HS reduction from LS have also been proposed.     

Parameterization of the MISO IFC rate region: the case of partial channel state information

We study the achievable rate region of the multipleinput single-output (MISO) interference channel (IFC), under the assumption that all receivers treat the interference as additive Gaussian noise. We assume the case of two users, and that the channel state information (CSI) is only partially known at the transmitters. Our main result is a characterization of Paretooptimal transmit strategies, for channel matrices that satisfy a certain technical condition. Numerical examples are provided to illustrate the theoretical results.     

On the search for low correlated binary sequences

The construction of binary sequences with low aperiodic correlation is one of the most famous, but also one of the most challenging, problems in signal design theory. In recent decades, many approaches from different mathematical disciplines have been used to tackle the problem. This paper summarizes the known results and adds some new results on the peak correlation of extended Legendre sequences and on binary arrays.     

Endurance behavior of conductive yarns

Various companies are industrializing ‘photonic’ textiles for medical and architectural applications. Here we report reliability testing of photonic textiles based on woven textiles with integrated copper-based conductive yarns used to drive attached LEDs. These textiles were subjected to cyclic mechanical stress tests and the cycle life was analyzed in terms of fatigue. Results show that failure is due to wire fractures at the transition from the rigid component to the compliant textile. The results are in good agreement with Cu-fatigue data from literature. This shows that it is possible to estimate the lifetime of electronic textiles under use conditions by the mechanical fatigue of the conducting yarn material properties.     

平台2015:Intel处理器及平台在下一个十年的演化

毫无疑问,近年来计算技术取得了长足的进步。但是,在未来的十年,主流计算技术中新的工作量、使用模式的出现及变化对未来的计算平台提出的要求,与过去十年所取得的进展也差不多,这些巨大的要求包括:更高的性能、更低的功率密度、更好的功能可扩展性。倘若出现这些使用计算机的震撼性的变化,我们怎样定义和构架未来的计算平台,就将不得不做出引人注目的改变。要整体地理解和满足的,不仅仅有计算的需要,而且还有接口以及系统基础设施的需要。Intel对这三个基础平台要素的演化的长期设想,以及驱动演化的架构的创新和核心能力,即是我们称之为平台2015(Platform2015)的内容。除了考察相关的趋势、使用、平台处理含意之外,本文将集中在平台2015的计算单元,描述Intel微处理器架构在未来十年的演化。     

Incoupling waveguide hologram with reduced polarization sensitivity

An incoupling waveguide hologram (IWGH) with significantly reduced polarization sensitivity was designed and fabricated in InP for 1550 nm wavelength. The IWGH couples the light from an optical fiber, irrespectively of the state of polarization, into the InP waveguide and simultaneously focuses it to a desired position in the waveguide. Conventional IWGHs are strongly polarization sensitive with a measured 19 dB difference in the incoupling efficiency between the TE and TM mode. In contrast, although some design parameters turned out to be slightly in error, the fabricated IWGHs designed for reduced polarization sensitivity exhibited a 3.1 dB difference in the incoupling efficiency between the TE and TM modes