分宜100 MW循环流化床锅炉旋风分离器分离效率的计算

为了得到分宜发电有限责任公司100MW循环流化床（CFB）锅炉旋风分离器的分离效率，对CFB锅炉分离器分离效率的工程计算方法进行了研究。在热态试验条件下通过直接测量物料浓度进行分离器分离效率的计算是很困难的，同时该方法还需要辅以分离器进出口物料粒径分布的测量，在数据处理和数据精度上都存在问题。为此从工程应用的角度出发，通过炉膛压力计算分离器人口烟气携带的物料浓度，采用物料平衡计算飞灰浓度，从而提出了一种工程上简单准确并且实时的计算测量方法。利用该方法，得到了分宜100MW CFB锅炉旋风分离器的分离效率在99．17％左右，同时得到循环倍率为24．7。     

上海锅炉厂有限公司新型容克式换热器设计技术

简要介绍了上海锅炉厂有限公司容克式预热器和烟气再热器的新设计方法 ,提供了目前空气预热器设计领域的最新发展情况     

Nucleate Pool Boiling of Pure Liquids and Binary Mixtures ：Part I—Analytical Model for Boiling Heat Transfer of Pure Liquids on Smooth Tubes

A mechanism is proposed for nucleate pool boiling heat transfer along with a general model for both pure liquids and binary mixtures. A combined physical model of bubble growth is also proposed along with a corresponding bubble growth model for pure liquids on smooth tubes. Using the general model and the bubble growth model for pure liquids, an analytical model for nucleate pool boiling heat transfer of pure liquids on smooth tubes is developed.     

Electrochemical deposition of iron nanoneedles on titanium oxide nanotubes

Iron as a catalyst has wide applications for hydrogen generation from ammonia, photodecomposition of organics, and carbon nanotube growth. Tuning the size and shape of iron is meaningful for improving the catalysis efficiency. It is the objective of this work to prepare nanostructured iron with high surface area via electrochemical deposition. Iron nanoneedles were successfully electrodeposited on Ti supported TiO₂ nanotube arrays in a chlorine-based electrolyte containing 0.15 M FeCl₂·4H₂O and 2.0 M HCl. Transmission electron microscopic analysis reveals that the average length of the nanoneedles is about 200 nm and the thickness is about 10 nm. It has been found that a high overpotential at the cathode made of Ti/TiO₂ nanotube arrays is necessary for the formation of the nanoneedles. Cyclic voltammetry test indicates that the electrodeposition of iron nanoneedles is a concentration-limited process.     

Grating lobe elimination in steerable parametric loudspeaker

In the past two decades, the majority of research on the parametric loudspeaker has concentrated on the nonlinear modeling of acoustic propagation and pre-processing techniques to reduce nonlinear distortion in sound reproduction. There are, however, very few studies on directivity control of the parametric loudspeaker. In this paper, we propose an equivalent circular Gaussian source array that approximates the directivity characteristics of the linear ultrasonic transducer array. By using this approximation, the directivity of the sound beam from the parametric loudspeaker can be predicted by the product directivity principle. New theoretical results, which are verified through measurements, are presented to show the effectiveness of the delay-and-sum beamsteering structure for the parametric loudspeaker. Unlike the conventional loudspeaker array, where the spacing between array elements must be less than half the wavelength to avoid spatial aliasing, the parametric loudspeaker can take advantage of grating lobe elimination to extend the spacing of ultrasonic transducer array to more than 1.5 wavelengths in a typical application.     

Synthesis and electrochemical properties of Nb-doped Li3V2(PO4)3/C cathode materials for lithium-ion batteries

Li₃V_2−xNb_x(PO₄)₃/C cathode materials were synthesized by a sol-gel method. X-ray diffraction patterns demonstrated that the appropriate addition of Nb did not destroy the lattice structure of Li₃V₂(PO₄)₃, and enlarged the unit cell volume, which could provide more space for lithium intercalation/de-intercalation. Transmission electron microscopy and energy dispersive X-ray spectroscopy analysis illustrated that Nb could not only be doped into the crystal lattice, but also form an amorphous (Nb, C, V, P and O) layer around the particles. As the cathode materials of Li-ion batteries, Li₃V_2−xNb_x(PO₄)₃/C (x ≤ 0.15) exhibited higher discharge capacity and better cycle stability than the pure one. At a discharge rate of 0.5C, the initial discharge capacity of Li₃V_1.85Nb_0.15(PO₄)₃/C was 162.4 mAh/g. The low charge-transfer resistances and large lithium ion diffusion coefficients confirmed that Li₃V_2−xNb_x(PO₄)₃/C samples possessed better electronic conductivity and lithium ion mobility. These improved electrochemical performances can be attributed to the appropriate amount of Nb doping in Li₃V₂(PO₄)₃ system by enhancing structural stability and electrical conductivity.     

高精度二维DCT的结构优化算法研究及FPGA实现

提出了一种基于5级流水线的高精度向量乘法器的二维DCT VLSI结构.采用一维DCT行处理,转置RAM存储器,一维DCT列处理的流水线结构代替复用一维DCT算法以提高速度,并且在一维DCT算法模块中,对于系数乘法,采用并行乘法的结构,可以进一步提高运算速度.在高精度方面,采用移位的方案,精度精确到小数点后5位,满足高精...     

Schottky diode fabricated on a single crystalline diamond rod

The fabrication process of Al/diamond Schottky diodes on single crystalline diamond rods (SCDRs) was demonstrated. SCDRs of submicron diameters were obtained by etching a polished polycrystalline diamond film in oxygen plasma. The as-scratched SCDR was confirmed to be single crystalline diamond by electron diffraction measurements showing the same fuzzy spot pattern at different parts of an SCDR. Each SCDR was extracted from a grain in the polycrystalline film where the grain size served as a limit of the length of an SCDR. Al/Ti and Al metals were deposited to form ohmic and Schottky contacts, respectively. A hydrogen plasma treatment is an essential step prior to the formation of an Al/diamond Schottky contact in order to improve the device performance. The submicron scale Al/diamond Schottky diode exhibits a very high current density of 1.4 × 10(4) A cm(-2) at a forward bias (V(F)) voltage of - 3 V.     

不同柔性链丙烯酸松香环氧树脂性能比较

以丙烯酸松香二缩水甘油酯(ARE)、丙烯酸松香乙二醇二缩水甘油醚(AR-EDGE)和丙烯酸松香丁二醇二缩水甘油醚(AR-BDGE)为研究对象,通过测定固化反应的凝胶时间、固化产物的耐热性、力学性能及耐溶剂性,研究了不同柔性链对松香基环氧树脂性能的影响。结果表明,松香基的稠环结构有着优异的耐热性,然而也会带来较大的脆性,需引入合适长度的柔性链。三种体系中,AR-EDGE综合性能最好,虽耐热性不及ARE,但其力学性能强于另两种体系;柔性链稍短的ARE因脆性大力学性能不好;柔性链稍长的AR-BDGE耐热性及耐丙酮性不佳,力学性能一般。