FFTPL: An Analytic Placement Algorithm Using Fast Fourier Transform for Density Equalization

We propose a flat nonlinear placement algorithm FFTPL using fast Fourier transform for density equalization. The placement instance is modeled as an electrostatic system with the analogy of density cost to the potential energy. A well-defined Poisson's equation is proposed for gradient and cost computation. Our placer outperforms state-of-the-art placers with better solution quality and efficiency

Direct Large-Area Growth of Graphene on Silicon for Potential Ultra-Low-Friction Applications and Silicon-Based Technologies

Deposition of layers of graphene on silicon has the potential for a wide range of optoelectronic and mechanical applications. However, direct growth of graphene on silicon has been difficult due to the inert, oxidized silicon surfaces. Transferring graphene from metallic growth substrates to silicon is not a good solution either, because most transfer methods involve multiple steps that often lead to polymer residues or degradation of sample quality. Here we report a single-step method for large-area direct growth of continuous horizontal graphene sheets and vertical graphene nano-walls on silicon substrates by plasma-enhanced chemical vapor deposition (PECVD) without active heating. Comprehensive studies utilizing Raman spectroscopy, x-ray/ultraviolet photoelectron spectroscopy (XPS/UPS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and optical transmission are carried out to characterize the quality and properties of these samples. Data gathered by the residual gas analyzer (RGA) during the growth process further provide information about the synthesis mechanism. Additionally, ultra-low friction (with a frictional coefficient ~0.015) on multilayer graphene-covered silicon surface is achieved, which is approaching the superlubricity limit (for frictional coefficients <0.01). Our growth method therefore opens up a new pathway towards scalable and direct integration of graphene into silicon technology for potential applications ranging from structural superlubricity to nanoelectronics, optoelectronics, and even the next-generation lithium-ion batteries

Changes in Outcome and Complication Rates of Very-low-birth-weight Infants in One Tertiary Center in Southern Taiwan Between 2003 and 2010

BackgroundNeonatal intensive care has changed dramatically over the past few decades and the survival of infants has generally improved in many countries. The purpose of this study was to explore the recent evolution of mortality and morbidities among very-low-birth-weight (VLBW) infants in southern Taiwan.MethodsWe retrospectively reviewed the medical records of VLBW (birth weight <1500 g) infants who were admitted to a neonatal intensive care unit at a tertiary medical center in southern Taiwan from 2003 to 2010. The study period was divided into two cohorts: the first cohort of 2003–2006 and the second cohort of 2007–2010. Demographic profiles and complications were recorded, including the following information: sex, birth body weight (BBW), gestational age (GA), Apgar score, patent ductus arteriosus (PDA), necrotizing enterocolitis, retinopathy, chronic lung disease (CLD), inguinal hernia, and sepsis. The length of stay (LOS) in hospital was compared between the two cohorts.ResultsA total of 420 (212 male) VLBW infants were enrolled with 52 (12.4%) deaths. Compared to surviving infants, deceased infants had significantly lower GA, Apgar scores, and BBW. The mortality of VLBW infants remained static between the two birth cohorts, but the incidence of major morbidities generally decreased. The LOS for overall surviving infants and the proportion of LOS > 60 days were both reduced in the period of 2007–2010. With further stratification by BBW, the major reduction of long LOS was only found in the group of BBW ≥ 1000 g. The multivariate logistic regression model found PDA, CLD, and BBW < 1000 g were major complications to be associated with long LOS among surviving infants.ConclusionPeriodic evaluation of the mortality and morbidity of preterm infants can help to understand the changes and trends of our neonatal care. Further study using the national dataset to provide more representative information is warranted

The design of quasi-sliding mode control for a permanent magnet synchronous motor with unmatched uncertainties

AbstractIn this study, the concept of a quasi-sliding mode control (QSMC) is introduced for the robust control of a permanent magnet synchronous motor (PMSM) system subjected to unmatched uncertainties, and even with input nonlinearity. On the basis of the new concept of QSMC, continuous control is obtained, to avoid the chattering phenomenon. As expected, the system state can be stabilized and driven into a predictable neighborhood of zero. Also, this approach only uses a single controller to achieve chaos control, which reduces the cost and complexity of implementation. The results of numerical simulations demonstrate the validity of the proposed QSMC design method

Microstructure and superelastic properties of FeNiCoAlTi single crystals with the <100> orientation under tension

The microstructure and superelastic response of an Fe41 Ni28 Co17 Al11.5 Ti2.5 (at.%) single crystal along the [removed] orientation was investigated under tension at room temperature after aging at 600◦ C for 24 h. From the superelastic results, the samples aged at 600◦ C for 24 h exhibited 4.5% recoverable strain at room temperature. The digital image correlation (DIC) method was used to observe the strain distribution during the 6.5% applied strain loading. The DIC results showed that the strain was uniformly distributed during the loading and unloading cycles. Only one martensite variant was observed from the DIC results. This was related to the aging heat treatment times. The martensite morphology became a single variant with a longer aging time. The thermo-magnetization results indicated that the phase transformation and temperature hysteresis was around 36◦ C. Increasing the magnetic field from 0.05 to 7 Tesla, the transformation temperatures increased. The maximum magnetization was 160 emu/g under the magnetic field of 7 Tesla. From the transmission electron microscopy results, the L12 precipitates were around 10 nm in size, and they were high in Ni content and low in Fe content