Simulation of the western North Pacific summer monsoon by regional ocean–atmosphere coupled model:impacts of oceanic components

A successful simulation of the western North Pacific summer monsoon needs a regional ocean–atmosphere coupled model(ROAM). How the performance of ROAM relies on the oceanic component model remains unknown. In this study, the authors investigated the effects of different oceanic components on the simulation of western North Pacific(WNP) summer monsoon in a ROAM. Three cases of simulations were performed, viz. the summer of 1998(El Nin o decaying phase), 2004(El Nin o developing phase), and 1993(the non-ENSO phase). Results show that the coupled simulations for different ENSO phases exhibit improvements in the simulation of location of Meiyu rainband and spatial distribution of monsoon low-level flow over WNP, whereas the systemic cold biases of sea surface air temperature are further increased. The coupled simulations with different oceanic components show similar performance, which is not ENSO phase dependent. For the case of the summer of 1998, a slightly stronger western Pacific subtropical high and colder sea surface air temperature are found in the simulation with colder sea surface temperature(SST) biases. The colder SST biases are partly contributed by the ocean dynamics processes because the sea surface net flux favors a warmer SST. This study suggests that the dependence of performance of ROAM over WNP on oceanic models is much weaker than that on atmospheric models.     

Effect of high pressure sintering and annealing on microstructure and thermoelectric properties of nanocrystalline Bi2Te2.7Se0.3 doped with Gd

Bi2Te2.7Se0.3of high performance doped with Gd bulk materials was prepared by a high pressure(6.0 GPa) sintering(HPS) method at 593 K,633 K, 673 K and 693 K. The sample was then annealed for 36 h in a vacuum at 633 K. The phase composition, crystal structure and morphology of the sample were analyzed by X-ray diffraction and scanning electron microscopy. The electric conductivity, Seebeck coefficient, and thermal conductivity aspects of the sample were measured from 298 K to 473 K. The results show that high pressure sintering and the doping with Gd has a great effect on the crystal structure and the thermoelectric properties of the samples. The samples are consisted of nanoparticles before and after annealing, and these nanostructures have good stability at high temperature. HPS together with annealing can improve the TE properties of the sample by decreasing the thermal conductivity of the sample with nanostructures. The maximum ZT value of 0.74 was obtained at 423 K for the sample, which was sintered at 673 K and then annealed at 633 K for 36 h. Compared with the zone melting sample, it was increased by 85% at423 K. Hence the temperature of the maximum of figure of merit was increased. The results can be applied to the field of thermoelectric power generation materials.     

Improving the mid-infrared energy absorption efficiency by using a dual-band metamaterial absorber

In this paper, a dual-band mid-infrared metamaterial absorber was proposed to improve the energy absorption efficiency. Up to 99% absorption was obtained at 9.03 and 11.83 μm in the simulation, and each absorption band can be tuned by the dielectric spacing layer, i.e., the dielectric constant and its thickness. The dual-band absorption mechanism was analyzed, and the quite well absorption performance at large incident angles was also presented. The results of this study can be applied in the field of thermal absorbing and solar energy harvesting.     

青藏高原的散射辐射特征

利用大量连续观测数据阐明了青藏高原散射辐射的时间变化特征,揭示了晴空指数(Rs/Ro)与散射辐射的关系,以及不同晴空指数条件下散射辐射随太阳高度角的变化.散射辐射日最高值出现在午后,年最高值出现在4月份.日晴空指数小于0.3时,太阳辐射基本以散射辐射形式到达地面,日晴空指数大于0.3时,散射辐射占总辐射的比例随晴空指数的增加而呈线性递减.日晴空指数达到0.45左右时,散射辐射占大气外界太阳辐射日总量的比例最高.散射辐射随太阳高度的蛇呈指数递增,但晴空指数在0.3～0.7范围内时,散射辐射随太阳高度角的变化最为明显.     

2-甲基吡啶的合成工艺

探讨了以乙炔和乙腈为原料制备高纯度2-甲基吡啶的合成工艺,通过实验确定了适宜的反应条件．结果表明,乙炔压力为1．1MPa、乙炔耗用量为7．332g、反应温度为180℃、有机钴类催化剂用量为200mg、反应时间为12h时,2-甲基吡啶收率可达50．88％．反应生成的混合溶液经过滤、间歇精馏制得含量大于98％的2-甲基吡啶产品．该工艺操作简单,收率较高,具有潜在的工业应用价值．     

高分辨率影像道路提取的整体矩形匹配方法

提出了一种整体矩形匹配方法,对高分辨率遥感影像中的城市直线道路进行提取.方法基于影像特征、道路知识和数学形态学的击中击不中思想,通过改变影像分割阈值、矩形宽度和矩形方向,从矩形的内部和外部进行整体匹配,使得矩形满足最佳匹配原则,从而提取出道路.利用提出的方法对高分辨率卫星影像进行了实验.结果表明:该方法能较好地消除树木、汽车等对道路提取的影响,有效地提取出直线道路的边缘.     

高精度低功耗快速启动带隙基准电路设计

提出一种能够明显减小电流失配误差的新颖带隙基准核心结构,结合低功耗设计方法和一种全新的启动方式,实现了整个带隙基准电路超低功耗和快速启动的功能.基于JAZZ BCD 0.5μm工艺库模型,采用Spectre仿真器进行了仿真验证,结果显示,在电源电压VCC工作范围2.5~6.0 V内,带隙电压的变化为0.06mV;在VCC=3.6 V,温度范围为-25~100℃时,带隙电压精度为17.5μV/℃;典型工作状态下(VCC=3.6V,t=25℃),整个电路静态电流仅为3.71μA,启动时间为23μs.     

深化认识 强化建设 优化成果——精品课程建设的思考

精品课程建设是一项长期的教学基础业务建设工程,其理论和实践都需要不断探索,我们结合<档案管理学>课程建设实践中的体会,从"精品课程与精品课程建设的涵义"、"优化配置,夯实基础"、"强化建设,注重实绩"三方面提出一些粗浅之见,以为深化讨论略尽绵薄.     

非负矩阵的n次幂等性

以非负矩阵的不可约正规形式为工具,给出了非负矩阵n次幂等的充要条件.