混酸插层制备膨胀石墨研究

对采用H2SO4-HNO3-KMnO4-H2O2混酸氧化插层体系制备膨胀石墨进行了研究,采用扫描电镜（SEM）、X射线衍射（XRD）、红外光谱（IR）和热重一差热法（TG-DTA）分析产物,并提出了氧化插层过程和机理。分析表明：插入剂的插入破坏了原有鳞片石墨层的紧密结构,使碳层间距增大,高温膨胀后,膨胀石墨呈蠕虫状或手风琴状蓬松结构,一个石墨蠕虫由许多微胞连接在一起组成,微胞之间呈现较大的狭缝裂开。氧化插层破坏了鳞片石墨原有的晶体结构,但是未破坏石墨的C—C键,20=29．5。处的特征峰是由石墨插层物结晶区引起的。可膨胀石墨片层。间存在SO4^2-、NO2阴离子插层物。可膨胀石墨在500℃之前的热失重和267℃附近较小的放热峰,均是由石墨插层物的气化、分解所致。     

Na2SiO3电解液体系中CaCl2/MgCl2加入量对Ti6Al4V合金微弧氧化膜层特性的影响

本文以Na2SiO3为基础电解液体系,加入一定量的CaCl2及MgCl2,对Ti6Al4V合金表面进行微弧氧化,研究CaCl2及MgCl2的加入对Ti6Al4V合金表面微弧氧化膜形成过程及其特性的影响规律。试验结果表明:CaCl2及MgCl2加入量从0.05g/L增加到0.35 g/L的过程中,正向起弧电压分别从350V增加至358V、330V增加至369V。SEM形貌分析显示,随着电解液中CaCl2的加入量增加,氧化膜层表面的孔洞减少,膜层表面出现直径约为5μm的颗粒状陶瓷,膜层变得疏松;MgCl2的加入量增加,氧化膜表面孔洞减少。EDS分析结果显示加入CaCl2、MgCl2的电解液中获得的膜层组成元素分别是Ti、Na、Al、Si、P、O,与基础电解液体系相比较,Ca元素有所增加,Mg元素变化不明显。XRD分析结果表明,CaCl2加入到电解液中出现了更多的金红石相TiO2的衍射峰;MgCl2加入电解液中之后,锐钛矿相TiO2有所增加。     

An extended DEM–CFD model for char combustion in a bubbling fluidized bed combustor of inert sand

This paper proposes a transient three-phase numerical model for the simulation of multiphase flow, heat and mass transfer and combustion in a bubbling fluidized bed of inert sand. The gas phase is treated as a continuum and solved using the computational fluid dynamics (CFD) approach; the solid particles are treated as two discrete phases with different reactivity characteristics and solved on the individual particle scale using an extended discrete element model (DEM). A new char combustion submodel considering sand inhibitory effects is also developed to describe char particle combustion behavior in the fluidized bed. Two conditions, i.e. a single larger graphite particle and a batch of smaller graphite particles, are used to test the prediction capability of the model. The model is validated by comparing the predicted results with the previous measured results and conclusions in the literature in terms of bed hydrodynamics, individual particle temperature, char residence time and concentrations of the products. The effects of bed temperature, oxygen concentration and superficial velocity on char combustion behavior are also examined through model simulation. The results indicate that the proposed model provides a proximal approach to elucidate multiphase flow and combustion mechanisms in fluidized bed combustors.     

二连盆地乌兰花凹陷花岗岩潜山储层特征及发育模式

乌兰花凹陷为二连盆地潜山油气重点勘探区域,凹陷内花岗岩潜山岩性复杂,储层非均质性强,整体勘探程度较低.综合镜下鉴定、岩性分析、测井解释等多种技术手段研究乌兰花凹陷花岗岩潜山储层特征及其发育模式.乌兰花凹陷花岗岩潜山主要储集空间类型为溶蚀孔、溶蚀扩大缝和构造裂缝,发育风化型和构造型2种储层,具有风化型-构造型储层复合发育的潜山储层发育模式,潜山优质储层分布在断裂带与风化壳复合的区域.该认识对深化乌兰花凹陷潜山勘探具有重要意义,同时也为其他勘探程度较低的花岗岩潜山储层区块提供借鉴.     

Effect of Bolts Assembly on the Deformation and Pressure Distribution of Flow‐Channel Plates in Micro‐PEMFC

The main aim of this study is to simulate the response of a micro‐PEMFC numerically by utilizing a 3‐D FEM model while the micro‐PEMFC was assembled by three pairs of bolt along the upper and lower portions, respectively, of the end plates. The effects of different bolts locking sequences on the deformation and pressure distributions at flow‐channel plates in a micro‐PEMFC were investigated. The simulated results showed that if one locked the middle bolt either on the upper or lower portion first, then the obtained warpage, uniformities of deformation and von Mises equivalent stress were superior than those results if one locked either one of the four corner bolts first. Also, among the three pairs of bolts used for assembling the cell, the first locking bolt of the first pair of locking bolt and the first locking bolt of the rest of two pairs of locking bolt were to minimize the warpage and stress should locate on the different portions of the end plates.     

JPEG forensics scheme for signature embedding and packet‐level detection

As the volume of multimedia digital information transmitted over the Internet continues to rise, the problem of preventing the unauthorized tampering and dissemination of digital content has emerged as a major concern. Thus, the present study proposes a forensic scheme for tracking the dissemination of copyright‐protected JPEG images over the Internet. The proposed scheme incorporates two basic mechanisms, namely signature embedding and signature detecting. To preserve the quality of the protected JPEG images, the signature is embedded at the application layer. By contrast, the signature detection process is performed at the packet level in order to improve the scalability of the proposed mechanism. For any flows regarded as suspicious, the signatures embedded in the JPEG packet trains are compared with the known digital signatures for forensic purposes. The experimental results show that the embedded signature has no effect on the visual quality of the JPEG image. Moreover, it is shown that the computational complexity of the proposed detection scheme is significantly lower than that of existing application‐level schemes. Thus, the scheme provides an ideal solution for the forensic analysis of JPEG streams over large‐scale network environments such as the Internet. Copyright © 2013 John Wiley & Sons, Ltd.     

Distinguishing the Importance of Fullerene Phase Separation from Polymer Ordering in the Performance of Low Band Gap Polymer:Bis‐Fullerene Heterojunctions

One way to improve power conversion efficiency (PCE) of polymer based bulk‐heterojunction (BHJ) photovoltaic cells is to increase the open circuit voltage (V _oc). Replacing PCBM with bis‐adduct fullerenes significantly improves V _oc and the PCE in devices based on the conjugated polymer poly(3‐hexyl thiophene) (P3HT). However, for the most promising low band‐gap polymer (LBP) system, replacing PCBM with ICBA results in poor short‐circuit current (J _sc) and PCE although V _oc is significantly improved. The optimization of the morphology of as‐cast LBP/bis‐fullerene BHJ photovoltaics is attempted by adding a co‐solvent to the polymer/fullerene solution prior to film deposition. Varying the solubility of polymer and fullerene in the co‐solvent, bulk heterojunctions are fabricated with no change of polymer ordering, but with changes in fullerene phase separation. The morphologies of the as‐cast samples are characterized by small angle neutron scattering and neutron reflectometry. A homogenous dispersion of ICBA in LBP is found in the samples where the co‐solvent is selective to the polymer, giving poor device performance. Aggregates of ICBA are formed in samples where the co‐solvent is selective to ICBA. The resultant morphology improves PCE by up to 246%. A quantitative analysis of the neutron data shows that the interfacial area between ICBA aggregates and its surrounding matrix is improved, facilitating charge transport and improving the PCE.     

空天一体作战初级阶段的典型作战运用

介绍了空天一体作战初级阶段的典型作战样式,即空间信息支援下的空地进攻作战,逐层剖析了它的作战过程,并突出强调了空间信息资源的作用及信息流程,为研究空间信息资源及评价其作战效能奠定了一定的基础.     

城市雨水利用调蓄方式及调蓄容积实用算法的探讨

在城市雨水利用中,雨水调蓄容积的计算依其目的、方式、有无渗透、溢流做法等条件的差异而不尽相同.主要从城市雨水利用的角度出发对雨水调蓄的不同方式及其调蓄容积计算原理进行了评述,并对其实用算法进行探讨和分析,主要包括降雨量估算法、降雨强度曲线计算法、统计降雨频率累计法.对有削减洪峰要求的调蓄储存池建议核算其削峰容积.结合实际,对雨水调蓄的泥区容积、超高和溢流方法也进行了讨论.