Synthesis and cross-coupling reactions of tetraalkylammonium organotrifluoroborate salts

Treatment of organoboronic acids with hydrofluoric acid generates an in situ tetracoordinate hydronium organotrifluoroborate species which undergoes counterion exchange with tetra-n-butylammonium hydroxide. The resultant tetraalkylammonium salts are as air and moisture stable as their potassium organotrifluoroborate counterparts with the added advantage of being readily soluble in organic media. They were found to undergo Pd-catalyzed Suzuki–Miyaura cross-couplings with a variety of aryl- and alkenylhalides under mild conditions. Their Pd-catalyzed cross-coupling with acid halides is also possible for the generation of ketones.     

Electronic inhomogeneities,electron-lattice and pairing interactions in high-T c superconductors

The presence of electronic inhomogeneities strongly reduces the screening of the electron-ion interaction in high-temperature superconductors. This implies the existence of an non-totally screened long-range contribution to the electron-lattice coupling and opens an additional channel for the formation of copper pairs. We calculate the superconducting order parameter taking into account a) the longrange and the short-range parts of the electron-lattice interaction and b) the Coulomb repulsion between charge-carriers. We show that whereas the long-range electron-lattice coupling determines the anisotropy of the order parameter, the Coulomb repulsion and the short-range interactions determine its symmetry. Thus, different high-T _c superconductors may have s- or d-wave symmetry, depending on the relative strength of the interactions involved in the pairing.     

芯片尺寸是否越大越好?

把更多的功能和更多的门电路集成在一块芯片上的能力——无论你将这块芯片称为SoC(单片系统)、ASIC(专用集成电路)还是称为一块大型集成电路——正在迅速提高。在亚微米设计和亚微米制造工艺的推动下,以及在更好的EDA工具和程序库的支持下,人们可以把数百万个子电路集成在一块硅片上。这种情况也许会有人认为,一种定制的、一块集成电路的体系结构——或许还能得到几个新奇而又     

业务使能软交换技术在市场的推动下前进

最初的软交换技术在电信领域的商业化应用为VoIP长途电话业务,即C4替代。接着,C5替代和应用使能软交换系统受到关注。前者由于承载和业务开放性方面的限制、业务集成困难和端到端QoS的困难而停滞不前;相比之下,后者却受到了许多中小企业的欢迎。在应用使能软交换的基础上,UT斯达康公司倡导业务使能交换技术,其核心为电信业务网络技术,适用于基于IP的下一代宽带固定多媒体网络和第三代移动多媒体网络。     

3G移动电话的系统级LSI

引言 无线移动电话仅具备语音功能的时代已经离我们远去了.目前的3G手机更多的是作为多媒体系统,提供彩显、游戏、音频、视频、相机、蓝牙、GPS、WLAN、高速广域数据服务以及其他高级特性.由于功能非常之多,因此处理新型3G电话比处理仅有语音功能的2G电话要复杂5倍至10倍,在应用处理方面则要求更高.     

Investigation of operational parameters for an industrial CFB combustor of coal, biomass and sludge

The combustion of coal and/or biomass （sludge, wood waste, RDF, etc.） in a circulating fluidized bed has been a commercial topper for over 20 years, and references to principles and applications are numerous and widespread although few data are presented concerning the operation of large scale CFB-units. The authors studied the CFB-combustion at UPM-Kymmene （Ayr）, a major paper mill relying for its steam production upon the combustion of coal （80-85 %）, wood bark （5-10%） and wastewater treatment sludge （5-10%）. The maximum capacity of the CFB is 58 MWth. A complete diagnostic of the operation was made, and additional tests were performed to assess the operating mode. The plant schematics, relevant dimensions and process data are given. To assess the operation of the UPM-CFB, it is important to review essential design parameters and principles of CFB combustors, which will be discussed in detail to include required data, heat balance and flowrates, operating versus transport velocity, kinetics and conversion （including the possible effect of the Bouduard reaction if carbon is present）. Since the residence time in the riser and the cyclone efficiency determine the burnout of circulating fuel-particles, the UPM-CFB was subjected to a stimulus response technique using nickel oxide as tracer. Results illustrate the efficiency of the cyclone separation and the number of recycle loops for particles of a given size. Results will also be used to assess the cyclone operation and efficiency and to comment upon expected and measured carbon conversion.     

基于数据融合的居民区建筑物重建方法研究

针对美国新奥尔良地区稀疏的LiDAR （Light Detecting and Ranging）点云数据,提出了一种基于LiDAR数据和卫星图像进行融合的居民区建筑物重建方法.该方法利用LiDAR数据点集的边界来定位卫星图像上的感兴趣区域,利用从感兴趣区域中提取的关键提示线来实现屋顶的分割,从而得到属于每个建筑物的屋顶点.然后,基于三角面片的法向量方向信息对其进行聚类,根据法向量之间的关系进行屋顶类型识别,从而实现居民区建筑物的重建.实验表明,该方法在进行居民区建筑物重建时,能达到较高的重建率,且重建所需时间合理,能够满足虚拟现实系统的需要.