Development of a Continuous Segmented Flow Tubular Reactor and the “Scale‐out” Concept – In Search of Perfect Powders

The synthesis of powders with controlled shape and narrow particle size distributions is still a major challenge for many industries. A continuous Segmented Flow Tubular Reactor (SFTR) has been developed to overcome homogeneity and scale‐up problems encountered when using batch reactors. Supersaturation is created by mixing the co‐reactants in a micromixer inducing precipitation; the suspension is then segmented into identical micro‐volumes by a non‐miscible fluid and sent through a tube. These micro‐volumes are more homogeneous when compared to large batch reactors leading to narrower size distributions, better particle morphology, polymorph selectivity and stoichiometry. All these features have been demonstrated on single tube SFTR for different chemical systems. To increase productivity for commercial application the SFTR is being “scaled‐out” by multiplying the number of tubes running in parallel instead of scaling‐up by increasing their size. The versatility of the multi‐tube unit will allow changes in type of precipitate with a minimum of new investment as new chemistry can be researched, developed and optimised in a single tube SFTR and then transferred to the multi‐tube unit for powder production.     

Improvement of AlGaInP light emitting diode by sulfide passivation

The brightness of AlGaInP light emitting diodes (LEDs) has been raised by a factor of 1.12 at 20 mA by sulfide passivation. Meanwhile, the sulfide also can decrease leakage current of AlGaInP LEDs at -2 V to nearly one thousandth of that in the as-fabricated device. The possible causes for the brightness increase of AlGaInP LEDs after sulfide treatment including surface roughness, reduction of Fresnel loss, and effective injection of carriers were demonstrated.     

Panchromatic Chromophore Mixtures in an AlPO4‐5 Molecular Sieve: Spatial Separation Effects and Energy Transfer Cascades

Dye‐loaded AlPO₄‐5 single crystals were prepared by microwave‐assisted hydrothermal synthesis from a batch, containing a mixture of three chromophores (Coumarin 40, Rhodamine BE50, and Oxazine 1) differing in their absorption range, molecular dimensions, and solubilities. Confocal fluorescence images reveal a spatial separation effect of the dye molecules, where the slimmer, more‐soluble dye molecule (Coumarin 40) is uniformly distributed in the body of the single crystal, and the bulky and/or less‐soluble ones (Rhodamine BE50, Oxazine 1) are situated in distinct domains. Visible spectra show good panchromatic absorption of visible light. Fluorescence lifetime measurements indicate the presence of an energy transfer cascade of the entirely fixed dye molecules from Coumarin 40 to Oxazine 1. The transfer mechanism is predominantly radiative.     

Ripple: a wireless token-passing protocol for multi-hop wireless mesh networks

This work presents a wireless token-passing protocol, named Ripple, for wireless mesh networks (WMNs). In contrast to existing random-access approaches, Ripple uses a decentralized controlled-access approach to protect nodes from unintentional packet collisions and maximize the spatial reuse. The performance of Ripple under an error-free wireless channel was investigated and the accuracy of the analysis was verified by simulation. Simulation results also indicated that Ripple achieved throughput, stability, and QoS enhancement than that of 802.11 DCF under a highly loaded situation.     

高水头弧形闸门止水型式研究

介绍了高水头弧形闸门止水型式,在此基础上,论述了突扩门槽的水力学问题。结合一些国内工程实例,探讨了高水头闸门常用的3种止水型式(偏心铰压紧式、液压伸缩式、滑动转铰式)的结构特点和适用范围。     

一种制氢预转化催化剂还原的新方法

对上海高桥分公司2×10~4m~3/h(标准状态)制氢装置原设计的预转化催化剂还原流程进行了改进。先跳开预转化反应器,利用转化炉制取氢气,再用自产的高纯氢气代替重整氢,对预转化催化剂进行单独升温还原,避免了催化剂在还原初期因发生甲烷化反应而超温失活的问题,使催化剂具有更好的活性和稳定性。     

异步DS-CDMA系统中基于矩阵点除算法的DOA估计

针对异步DS-CDMA系统中的多用户环境,本文提出了一种低复杂度的DOA估计算法——矩阵点除算法。该算法通过对感兴趣信息的逐次分离,实现了DOA的逐路径估计。算法具有两方面显著优势:(1)克服了传统的DOA估计算法在路径总数大于天线阵元数时不能工作这一缺陷:(2)避免了计算复杂的特征值分解运算,大大降低了算法复杂度。仿真实验验证了算法的有效性。     

火工品压药机装配误差的研究

针对军用雷管生产线中压药机结构,分别用极值法和概率法对压药机冲子和雷管的配合精度,进行了装配尺寸链的描述和计算,并对所得的结果进行了比较。