FaSa: A fast and stable quadratic placement algorithm

Placement is a critical step in VLSI design because it dominates overall speed and quality of design flow.In this paper,a new fast and stable placement algorithm called FaSa is proposed.It uses quadratic programming model and Lagrange multiplier method to solve placement problems.And an incremental LU factorization method is used to solve equations for speeding up.The experimental results show that FaSa is very stable,much faster than previous algorithms and its total wire length is comparable with other algorithms.     

Enhanced chain dynamics in loop-sorting-systems by means of layout optimization and a kinematic model of the polygon action

Poor dynamics owing to polygon action is a known concern in mechanical applications of closed articulated chains. In this paper a kinematic model of the polygon action in large chains of loop-sorting-systems is proposed. Through optimization techniques the chain dynamics is improved by minimizing the polygon action using a parametric model of the track layout as design variables. Three formulations of the kinematic polygon action are tested on an average sized planer tracks layout to find a superior model. Verification of the proposed optimization method is performed using a state-of-the-art multi-body simulation model of the chain dynamics.     

Achieving large transport bandgaps in bilayer graphene

Since opening sizable bandgaps in bilayer graphene (BLG) was proven possible, BLG has attracted considerable attention as a promising high-mobility candidate material for many electronic and optoelectronic applications. However, the bandgaps observed in the transport experiments reported in the literature are far smaller than both the theoretical predictions and the bandgaps extracted from optical measurements. In this study, we investigate the factors preventing the formation of large bandgaps and demonstrate that a ~200-meV transport bandgap can be opened in BLG by scaling the gate dielectric and employing a ribbon channel to suppress the percolative transport. This is the largest transport bandgap that has been achieved in BLG to date.

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Magnetron sputtering of TiOxNy films

This article reports on the characterization and preparation of N-doped titanium dioxide (TiO₂) films by reactive magnetron sputtering from Ti(99.5) targets in a mixture of Ar/O₂/N₂ atmosphere on unheated glass substrates. A dual magnetron system supplied by a dc bipolar pulsed power source was used to sputter the TiO_xN_y films. The amount of N in the TiO_xN_y film ranges from 5 to 40 at%. Its structure was measured using X-ray diffraction (XRD), the optical band gap was calculated from Tauc plots and the decrease of the water contact angle α_ir after the film activation by UV irradiation was investigated as a function of at% of N in the TiO_xN_y film. The yellow-coloured TiO_xN_y films with high (≈8 at%) amount of N exhibited a strong decrease of the band gap E_g down to 2.7 eV. A significant decrease of the water contact angle α_ir after UV irradiation has been observed for 2 μm thick transparent nanocrystalline (anatase+rutile) N-doped TiO₂ films containing less than 6 at% of N.     

Supported Pt-particles on multi-walled carbon nanotubes with controlled surface chemistry

Multi-walled carbon nanotubes (MWCNTs) were functionalized by HNO₃ hydrothermal oxidation at 200 °C. The degree of surface functionalization was described by an exponential function in terms of HNO₃ concentration. Very small Pt particles, with mean particle size of 1.7 ± 0.3 nm, could be supported on the surface of pristine MWCNTs and also on MWCNTs treated with HNO₃ concentrations up to 0.20 mol L^− 1, while a broader range of particle sizes, and larger Pt particles (3.4 ± 1.3 nm) were obtained on the MWCNTs treated with a higher HNO₃ concentration (0.30 mol L^− 1). Therefore, the amounts of surface groups and Pt particle sizes can be selected by tuning the HNO₃ concentration used in the hydrothermal treatment.     

Time-domain BEM for transient interfacial crack problems in anisotropic piezoelectric bi-materials

A time-domain boundary element method (BEM) together with the sub-domain technique is applied to study transient response of interfacial cracks in piecewise homogeneous, anisotropic and linear piezoelectric bi-materials under electrical and mechanical impacts. The present time-domain BEM uses a quadrature formula for the temporal discretization to approximate the convolution integrals and a collocation method for the spatial discretization. Quadratic quarter-point elements are implemented at the tips of the interface cracks. To determine the real or complex dynamic stress intensity factors and the dynamic electrical displacement intensity factor of the interfacial cracks, an explicit extrapolating formula in a typical state of the crack plane perpendicular to the poling direction is presented in this paper. Numerical examples are presented; and the effects of the load combination and material combination on dynamic intensity factors and dynamic energy release rate are discussed.     

Synthesis,structural and optical properties of CdS nanoparticles with enhanced photocatalytic activities by photodegradation of organic dye molecules

CdS nanoparticles (NPs) were synthesized using co-precipitation method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to confirm the structures and morphologies of CdS NPs. X-ray diffraction data confirmed the crystal structure of the CdS NPs. Raman spectrum exhibited the Raman modes of LO and 2LO of CdS at 290 and 595 cm^?1 respectively. The evaluated band gap was 3.15 eV, this value was shifted compared with the bulk value and this could be a significance of a size quantization effect in the sample. The CdS nanoparticles showed higher photocatalytic activity for the discoloration of methyl orange (MO) under UV light irradiation for 90 min. The highest photocatalytic activity was obtained with the sample containing 0.3 wt % CdS nanoparticles, in which more than 98 % of the MO was discolored within 90 min.     

Information hiding in product development: the design churn effect

Execution of a complex product development project is facilitated through its decomposition into an interrelated set of localized development tasks. When a local task is completed, its output is integrated through an iterative cycle of system-wide integration activities. Integration is often accompanied by inadvertent information hiding due to the asynchronous information exchanges. We show that information hiding leads to persistent recurrence of problems (termed the design churn effect) such that progress oscillates between being on schedule and falling behind. The oscillatory nature of the PD process confounds progress measurement and makes it difficult to judge whether the project is on schedule or slipping. We develop a dynamic model of work transformation to derive conditions under which churn is observed as an unintended consequence of information hiding due to local and system task decomposition. We illustrate these conditions with a case example from an automotive development project and discuss strategies to mitigate design churn.

高能气体压裂技术在油田的应用

阐述高能气体压裂的作用机理和特点,并通过在油田的应用总结出现场施工工艺、应用效果和适用范围,为该技术的推广应用提供借鉴.