Green cell association for multimedia transmission in cognitive heterogeneous networks

With the introduction of low‐powered pico/femto‐base stations and relay nodes into the macro‐cell, recent heterogeneous networks provide an attractive approach for future wireless communication. Although it may achieve better coverage and higher capacity, several problems remain unsolved before practical deployment. For example, how to select the proper cell from neighbor low‐powered cells and then occupy the radio resource without interference on macro‐users is both important and challenging, especially for rigorous multimedia applications. The traditional cell access algorithms and quality‐control parameters such as delay or throughput no longer suit well in this complex environment. An effective approach should be pursued. In this paper, we investigate this interesting cell association problem and propose a complete green resolution on the basis of thorough discussions about the multimedia transmission under these concerns. Cognitive radio is introduced to share spectrum between macro‐cell and low‐powered cells while securing the transmission of authorized macro‐users. We also bring forth the concept of ‘interference balance’ to better manage the overall interference and energy consumption in the network. Restless bandit model is formulated on the basis of channel state, data rate, interference control, and the carefully chosen intra‐refreshing rate for multimedia traffic. Then the cell association scheme is designed to be efficient and practical because of the simple index property of our model output. Simulation results have proven the performance of our proposed resolution compared with existing algorithms on interference constraint, multimedia distortion, and overall network energy consumption balance. Copyright © 2013 John Wiley & Sons, Ltd.     

Recent Advances in Porphyrin-Based Systems for Electrochemical Oxygen Evolution Reaction

Oxygen evolution reaction (OER) plays a pivotal role in the development of renewable energy methods, such as water-splitting devices and the use of Zn–air batteries. First-row transition metal complexes are promising catalyst candidates due to their excellent electrocatalytic performance, rich abundance, and cheap price. Metalloporphyrins are a class of representative high-efficiency complex catalysts owing to their structural and functional characteristics. However, OER based on porphyrin systems previously have been paid little attention in comparison to the well-described oxygen reduction reaction (ORR), hydrogen evolution reaction, and CO₂ reduction reaction. Recently, porphyrin-based systems, including both small molecules and porous polymers for electrochemical OER, are emerging. Accordingly, this review summarizes the recent advances of porphyrin-based systems for electrochemical OER. Firstly, the electrochemical OER for water oxidation is discussed, which shows various methodologies to achieve catalysis from homogeneous to heterogeneous processes. Subsequently, the porphyrin-based catalytic systems for bifunctional oxygen electrocatalysis including both OER and ORR are demonstrated. Finally, the future development of porphyrin-based catalytic systems for electrochemical OER is briefly prospected.     

储层流动单元研究新技术在油田开发中的应用

流动单元研究提供了精细解剖砂体,表征砂体内部非均质性的新方法。本文在传统流动单元划分的基础上应用流动带指标新方法(F z)进行储层流动单元的定量划分,为合理进行油田开发动态分析提供依据,同时开辟了一个可预测可操作的有效流动单元研究方法。     

横江水库土坝渗水原因分析及处理措施

横江水库长期处于限制蓄水、 "带病"运行状态.只有对渗水原因进行分析、解决土坝的变形和渗透等问题,才能最终达到除险加固之目的.     

天荒坪电站上水库进出水口截水墙帷幕补强灌浆试验

天荒坪电站上水库采用全库盆沥青混凝土防渗,仅进出水口位置未设置.为防止库水下渗到沥青混凝土库盆的下卧层,设置了截水墙和防渗帷幕,该帷幕长期处于动水压力下,性能削弱较严重,需要补强.为了保证帷幕补强的耐久性,进行了试验,对灌浆的参数和材料进行比选,并用于最终补强施工.     

多功能油层保护剂JQD的研制与应用

针对新疆小拐油田裂缝-孔隙型储层特点,开发研制了一种新型的兼具防漏堵漏及油层保护功能的JQD处理剂。该处理剂具有较好的油溶率、酸溶率,与现有钻井完井液体系配伍性良好,加工粒径可调,对1—4mm的裂缝堵漏效果良好。动态损害实验表明,JQD体系的岩心渗透率恢复值不小于80％。现场试验三口表明,JQD与钻井液配伍性良好,防漏堵漏效果显著,性能调整及维护方便,起下钻及电测顺利。三口井投产后,两口井产量分别为30和28t/d,一口井产气量为1.1×10~4m~3/d,说明储层得到了有效的保护,实现了“堵得住、解得开”的目标。     

油水两相非达西试井分析新进展及其展望

简述了低渗透油藏、油水两相低渗透油藏非达西试井分析研究的新进展。提出对低渗透油藏应建立公认的非达西渗流数学模型,准则数、数值试井模型及分析方法,指出低渗透油藏是否存在非达西渗流,除加强渗流特征的影响因素、渗流形成机理的研究之外,还要从实验上能够模拟代表真实的现场条件的体现度。     

柴达木盆地油泉子储油构造分析

通过对野外露头、地震反射剖面和钻井资料的综合分析,查明柴达木盆地油泉子储油构造为共轭膝褶带夹持的不对称半箱状背斜,具有北北东倾的平直转折端,北翼为一宽超过800m的大型膝褶带,高角度倾向南南西,带内岩层产状直立。带内岩层的旋转指示南侧沿膝褶带向北逆向剪切。南翼发育四条规模较小的膝褶带,向南逆冲剪切,导致该翼呈阶梯状产出,总体南南西倾,倾角约20°。沿南北两翼膝褶带边界仅见小型高角逆断层,膝褶带内裂隙发育,主要为顺层张裂隙,其次为与层理近垂直的张裂隙(主要出现在坚硬的钙质粉砂岩中),偶尔见有小型低角逆冲断层。这些断裂普遍被纤维状石膏充填,并见少量油迹,表明这些断裂为高流体压力下的产物。鉴于膝褶带及相关背斜高点为裂隙发育带,具有油气运移和聚集的双重功能,在缺乏足够理想的岩性储集层的情况下,为寻找裂隙型油气藏提供了新途径。     

塔里木盆地志留系热液碎屑岩储层:证据、矿物组合及油气地质意义

根据岩心观察、扫描电镜、能谱分析、显微薄片观察及流体包裹体测温显示的岩石宏观与微观特征、矿物组合、自生矿物形成温度等,认为塔里木盆地存在热液碎屑岩储层.热液碎屑岩岩石学证据主要体现在塔中地区中1井志留系柯坪塔格组碎屑岩中发育的基性侵入岩夹层、热液角砾岩、热炙烤现象及热液溶蚀孔洞等;在塔里木盆地中部的塔中地区和顺托果勒地区柯坪塔格组可识别出3种热液矿物组合.综合前人研究成果,认为热液的侵入主要发生于二叠纪,造成储集岩孔隙流体离子环境紊乱,溶解作用的发生促进了次生孔隙发育,并沉淀了热液矿物,总体上改善了碎屑岩储层,是塔里木盆地柯坪塔格组碎屑岩储层不可忽视的影响因素.热液侵入对已形成的古油藏产生破坏作用,并在志留系沥青砂岩生成过程中产生重要作用.     

高黏度牛顿流体中砂粒运动实验研究

为了解决疏松砂岩稠油油藏开采过程中的砂粒运移问题,基于固液两相流理论及实验流体力学理论,利用研制的高黏度流体颗粒自由沉降实验装置,分别开展了高黏度牛顿流体中球形颗粒的自由沉降实验、砂粒的自由沉降实验和不同含砂体积分数下混合黏度变化规律实验,根据实验结果,建立了不同粒径范围的阻力系数模型以及混合黏度模型。研究表明,高黏油混合黏度存在相应的临界值,在实验条件下,含砂体积分数为0.1%时,混合黏度达到最低,不利于携砂。结合上述模型和实验结果,建立了高黏度牛顿流体中的砂粒运动模型,揭示了高黏介质中颗粒的特定运移规律,为今后稠油携砂流动规律理论研究奠定了基础。