First principles calculations of the electronic, dynamical, and thermodynamic properties of the rocksalt ScX (X = N, P, As, Sb)

We have investigated the electronic, dynamical, and thermodynamic properties of the rocksalt ScX (X = N, P, As, Sb) using a plane-wave pseudopotential method within the generalized gradient approximation in the frame of density functional perturbation theory. The calculated lattice constants are found to differ by less than 0.56% from the available experimental values. These materials have the indirect Γ–X band gaps and a wide and direct band gap at the X-point in band structure, which are closer to experimental results than the previous calculations. A linear-response approach is used to calculate the phonon frequencies, the phonon density of states and LO–TO splitting. The obtained phonon frequencies at the zone-center (Γ-point) for the Raman-active and infrared-active modes are analyzed. We also calculate the thermodynamic functions using the phonon density of states, and the calculated values are in nearly perfect agreement with experimental data.     

Solution-phase synthesis of rose-like CuO

Rose-like nanoarchitectures CuO have been prepared by a mild solution-phase route without the utility of templates, additives or external magnetic field. The CuO nanoparticles exhibit a perfect rose flower structure which are composed of nanosheets in size of several micrometers in length and width and 30-40 nm in thickness. The corresponding band gap was estimated to be 2.65 eV. It is expected that the novel copper compound particles may offer some potential applications in catalysis, electrochemistry, and sensors.     

Pulse broadening factor as a criterion to assess nonlinear penalty of 40-Gbit/s RZ-DQPSK signals in dynamic transparent optical networks

The real-time scheduling and routing in dynamic transparent optical networks requires fast and accurate evaluation of transmission penalty caused by nonlinear kerr effects with different dispersion maps. However, the conventional method using nonlinear phase shift can only be applied to assess the nonlinear penalty with optimized dispersion maps. In this paper, we introduce pulse broadening factor into the approach and propose a novel method to accurately evaluate nonlinear penalty and numerically investigate the feasibility of our novel method in 40-Gb/s Return-to-Zero Differential Quadrature Phase-Shift Keying (RZ-DQPSK) systems. Simulation results show that our approach can achieve good evaluation performance even with non-optimized dispersion maps.     

Synthesis and Spectroscopic Investigations of CuSO4 · 5H2O Doped Poly (m-Toluidine)

Poly (m-toluidine) has been synthesized by chemical oxidative polymerization in acidic medium. Poly (m-toluidine) so obtained has been doped with copper sulfate in different concentration and prepared samples have been characterized by UV-visible spectroscopy, FTIR spectroscopy, X-ray diffraction, and DC conductivity measurements. UV-visible study reveals that optical band gap decreases considerably with increase in dopant concentration. The FTIR spectra exhibit structural changes in the backbone of poly (m-toluidine) with doping. The XRD patterns demonstrate the amorphous nature of the samples. It is observed that DC conductivity increases with increase in temperature showing the organic semiconducting nature of doped poly (m-toluidine).     

An improved technology for eliminating nondeterministic latency in the L1 trigger system

Gamma Ray Array Detector(GRAD) is one of external target facility subsystems in the Cooling Storage Ring on the Heavy Ion Research Facility at Lanzhou(HIRFL-CSR).The trigger subsystem of GRAD is required to make a fast L1 trigger decision with a fixed latency for the data acquisition.Because the hit signals from the detector are asynchronous with the local clock of the trigger system,a nondeterministic latency(the value changes between zero and one clock period) is generated when the synchronous receivers of the conventional trigger system process the hit signals.In this paper,an improved trigger logic based on a field-programmable gate array is developed,and comprised of zero-delay broadening circuits as receivers and an improved adding circuit designed for the new receivers.Software simulation and experimental measurement have been conducted.Comparison with the conventional trigger logic,the improved trigger logic has the advantage of eliminating the nondeterministic latency and reducing the total processing latency.     

Spatially resolved positron annihilation spectroscopy on friction stir weld induced defects

A friction stir welded (FSW) Al alloy sample was investigated by Doppler broadening spectroscopy (DBS) of the positron annihilation line. The spatially resolved defect distribution showed that the material in the joint zone becomes completely annealed during the welding process at the shoulder of the FSW tool, whereas at the tip, annealing is prevailed by the deterioration of the material due to the tool movement. This might be responsible for the increased probability of cracking in the heat affected zone of friction stir welds. Examination of a material pairing of steel S235 and the Al alloy Silafont36 by coincident Doppler broadening spectroscopy (CDBS) indicates the formation of annealed steel clusters in the Al alloy component of the sample. The clear visibility of Fe in the CDB spectra is explained by the very efficient trapping at the interface between steel cluster and bulk.     

推覆体下13—1煤层综放开采水文地质特征及“三带”高度的探讨

探讨煤层开采的“三带”高度 ,确定 13- 1煤层综放开采的上限 ,正确指导 13- 1煤层安全回采     

基于三维有限元的箱梁腹板剪力分配规律分析

针对单箱多室箱梁在不同支承条件、腹板数量以及腹板厚度条件下的腹板剪力分配规律问题,提出了采用Midas/FEA对单箱多室箱梁进行数值模拟的方法,提取箱梁各道腹板的剪力值并进行对比分析,得到单箱多室箱梁各道腹板所分担剪力并非均分的结果.分析结果表明:当支承条件为双支座时,剪力增大系数最大;当腹板较少时,边腹板与中腹板剪力增大系数差别较小,边腹板的剪力增大系数随腹板数量增加而增大;腹板厚度变化对剪力分配影响不大.     

微带线平行耦合带通滤波器的软件设计

本文介绍了仿真软件ADS在平行耦合带通滤波器设计中的使用。采用ADS对原始电路进行仿真,优化等实现带通滤波器的原始设计,做出了样品,并实验验证了软件设计的合理性和正确性。     

Ground state properties and structural phase transition of beryllium chalcogenides

The ground state properties and the structural phase transformation of beryllium chalcogenides (BeS, BeSe, and BeTe) have been investigated using first principle full potential-linearized augmented plane wave method (FP-LAPW) within density functional theory. We used local density approximation with and without generalized gradient correction as well as the Engel Vosko’s GGA formalism to find band gap. From the obtained band structures, the electron (hole) valence and conduction effective masses are deduced. We have determined the full set of first-order elastic constant, which have not been established experimentally. We have also calculated the energy–volume relations for these compounds in the zinc-blende (B3) and the NiAs (B8) phases. Hence we have obtained the lattice parameters, bulk modulus, pressure derivative of bulk modulus and cohesive energy as well as structural transition pressure. The calculated ionicity parameter which expected from the charge density behavior compared well with the Phillips’ ionicity scale.