Bi2SiO5 Doping Concentration Effects on the Electrical Properties of SrBi2Ta2O9 Films

In this paper, we investigated the microstructure and electrical properties of Bi₂SiO₅ (BSO) doped SrBi₂Ta₂O₉ (SBT) films deposited by chemical solution deposition. X-ray diffraction observation indicated that the crystalline structures of all the BSO-doped SBT films are nearly the same as those of a pure SBT film. Through BSO doping, the 2Pr and 2Ec values of SBT films were changed from 15.3 μC/cm² and 138 kV/cm of pure SBT to 1.45 μC/cm² and 74 kV/cm of 10 wt.% BSO-doped SBT. The dielectric constant at 1 MHz for SBT varied from 199 of pure SBT to 96 of 10 wt.% BSO-doped SBT. The doped SBT films exhibited higher leakage current than that of non-doped SBT films. Nevertheless, all the doped SBT films still had small dielectric loss and low leakage current. Our present work will provide useful insights into the BSO doping effects to the SBT films, and it will be helpful for the material design in the future nonvolatile ferroelectric memories.     

Preparation,Infrared Emissivity,and Dielectric and Microwave Absorption Properties of Fe-Doped ZnO Powder

Fe-doped ZnO powders have been synthesized by the coprecipitation method using zinc nitrate [Zn(NO₃)₂·6H₂O] as starting material, urea [CO(NH₂)₂] as precipitator, and ferric nitrate [Fe(NO₃)₃·9H₂O] as doping source. The microstructure of the prepared powders has been characterized by x-ray diffraction and scanning electron microscopy. Results show that, when the molar ratio of Fe to (Zn + Fe) was less than 0.09, the prepared powder was ZnO(Fe) solid solution, and the ZnFe₂O₄ impurity phase appeared when the Fe doping content was further increased. The electric permittivity in the frequency range of 8.2 GHz to 12.4 GHz and the average infrared emissivity in the wavelength range of 8 μm to 14 μm have been determined for the prepared powders. The average infrared emissivity decreased with increasing Fe doping content. The real (ε′) and imaginary part (ε″) of the permittivity of the prepared powders showed opposite trends. When the molar ratio of Fe to (Zn + Fe) was 0.03, the prepared Fe-doped ZnO powder demonstrated the best microwave absorption in the frequency range of 8.2 GHz to 12.4 GHz.     

斯拉夫哈萨克文与现行哈萨克文编码字符转换规则的探究

哈萨克语在发展变化的过程中,在世界范围内形成了基于同一语言的两种文字形式的特殊情况,分别是国外的以斯拉夫文字母为基础的哈萨克斯拉夫文字,称之为斯拉夫哈萨克文,以及我国的以阿拉伯文字母为基础的哈萨克阿拉伯文字,称之为现行哈萨克文。由于两种哈萨克文发音相同,而且均是一音一字的文字形式,所以斯拉夫哈萨克文与现行哈萨克文是可以通过规则互相转换的,但至今并没有相关的国家或地方标准对转换规则进行明确描述。因此,本文通过对斯拉夫哈萨克文和现行哈萨克文的研究,提出两种文字的字符编码转换规则。     

铁氧体在电磁兼容设计中的应用

概述了铁氧体的特性,并重点论述了铁氧体抑制元件的应用场合,以及在电磁兼容设计中如何正确地选择及使用铁氧体抑制元件。     

Mobile Cloud Computing: A Survey,State of Art and Future Directions

In the recent years, cloud computing frameworks such as Amazon Web Services, Google AppEngine and Windows Azure have become increasingly popular among IT organizations and developers. Simultaneously, we have seen a phenomenal increase in the usage and deployment of smartphone platforms and applications worldwide. This paper discusses the current state of the art in the merger of these two popular technologies, that we refer to as Mobile Cloud Computing (MCC). We illustrate the applicability of MCC in various domains including mobile learning, commerce, health/wellness and social medias. We further identify research gaps covering critical aspects of how MCC can be realized and effectively utilized at scale. These include improved resource allocation in the MCC environment through efficient task distribution and offloading, security and privacy.     

硫酸盐法蒸煮脱木素历程的近红外光谱表征法

利用近红外光谱法对木材硫酸盐法蒸煮过程脱木素历程进行了研究。结果表明,利用红外光谱能较好地表征木材的三段脱木素历程。这为下一步近红外光谱在线测量仪的开发奠定了理论基础。     

溶剂法浸出棉籽油和脱除棉酚的工艺研究

综述了采用单一溶剂或混合溶剂浸出棉仁生坯（或饼）,提取棉籽油并脱除棉籽粕中棉酚的工艺研究进展情况。     

Optimal nonnegative definite approximations of estimated movingaverage covariance sequences

The problem of finding the closest nonnegative definite moving average covariance sequence to a given estimate which may not be nonnegative definite is considered. An algorithm is developed which is based on a set of constrained minimization problems, each parameterized by the zero frequencies of the spectral density function corresponding to the optimal solution. The algorithm entails first solving a simple minimization problem with linear constraints whose closed-form solution is given by a projection onto a subspace. These solutions lie either outside the set of nonnegative definite sequences, or on its boundary; if the solution lies on the boundary, it is the optimal solution. The problem is considered directly in the space of covariance sequence elements. As a result, the nonlinear maximization step is performed on sets of low dimension. By considering the minimization problem in this space, it is possible to characterize some of the geometrical properties of the optimal solution in terms of the locations of its zero frequencies     

建筑装修中的电气问题

装修工程的电气安装应该重新进行负荷计算电气设计，正确选用导线、开关和静设方式，采用线槽敷设时的容线面积可限定在２０－４０％以下。     

无人立尺测量技术在三峡大江截流中的应用

在三峡工程大江截流进程中，随着深水围堰戗堤进占，裹头水位观测的平面位置是一个平行于围堰轴线的动态轨迹。采用无人立尺测量技术代替常规主法接测水中消除堤塌和施工车辆振动等因素对水位精度的影响，并且目标位置可根据需要随时变动。