Graphene-encapsulated mesoporous SnO2 composites as high performance anodes for lithium-ion batteries

Mesoporous metal oxides such as SnO₂ exhibit a superior electrochemical performance as anode materials for lithium-ion batteries due to their large surface areas and uniform pores. However, they suffer from the capacity fading in varying degrees during cycles because their partial pores may collapse during the charge–discharge process. Herein, graphene-encapsulated mesoporous SnO₂ composites have been simply synthesized using a modified stepwise heterocoagulation method. These graphene-based SnO₂ composites exhibit not only higher capacities and better rate capabilities but also improved cycle performances, suggesting that the electrochemical performance of mesoporous SnO₂ can be further enhanced by graphene encapsulation.     

利用灰色理论精细评价油气储层的方法

利用测井资料,依据测井地质评价方法和准则,提出利用灰色理论精细评价油气储层的方法,在各类微机和微机工作站上建立起用灰色理论精细评价油气储层的解释系统.通过华北、胜利、塔里木、二连及长庆油田100余口不同类型井(包括直井、斜井和水平井)中的应用,取得了明显的实用效果,文中给出了该方法和软件的主要处理过程和实际应用的例子.     

腹板加劲冷弯薄壁拼合H形钢压弯构件畸变性能试验研究

为研究偏心荷载作用下拼合构件的畸变屈曲性能,并评估现行中美规范计算方法适用性,对22个腹板V形加劲及开孔的冷弯薄壁拼合H形钢柱进行受压性能试验,得到了不同柱长、不同开孔位置及个数、不同偏心距以及绕强轴和弱轴弯曲方向的拼合构件的破坏模式和承载力。试验结果表明：所有腹板V形加劲及开孔的冷弯薄壁拼合H形钢柱均发生了畸变屈曲或以畸变为主的相关屈曲,畸变半波的分布受孔洞和加劲的影响;绕强轴和绕弱轴偏心方向及偏心距大小对承载力有显著影响。基于现行中美规范计算方法对腹板V形加劲及开孔的冷弯薄壁拼合H形钢柱承载力进行研究,结果表明：计算绕强轴压弯承载力时,按GB 50018—2002《冷弯薄壁型钢结构技术规范》、JGJ/T 421—2018《冷弯薄壁型钢多层住宅技术标准》以及美国NAS100-16的承载力公式计算结果均偏于安全;计算绕弱轴压弯承载力时,试验结果与按GB 50018—2002和美国NAS100-16的承载力公式计算结果的比值平均值为1.16、1.15,偏于安全且较为合理,与按JGJ/T 421—2018的计算结果的比值平均值为1.66,较为保守,建议拼合构件的双肢可靠连接时,按拼合整体截...     

基于忆阻神经网络的光伏面板清扫机器人PID控制器研究

机器人清扫是光伏面板高效、便捷的清扫方式。文章研究了光伏面板清扫机器人的PID控制器的优化策略。文章基于忆阻器独特的纳米级电路特性,设计了一种新型的突触电路;然后,基于新型的突触电路,构建对应的神经元和神经网络电路,并将忆阻神经网络和光伏面板清扫机器人中的PID控制器相结合,提出一种新型PID控制方法,该方法在一定程度上解决了传统PID控制器体积大、功耗高和相关参数不可调的问题;最后,基于仿真结果验证了文章提出方案的可行性和有效性。     

基于DEA和投入产出模型的我国省际水-能源-经济耦合关系研究

产业体系中能源和水资源的消费是紧密联系的,两者存在相辅相成的关系。在生态文明建设和产业转型升级的背景下,我国需要提高能源和水资源的使用效率,实现水资源与能源协同利用,才能更好地实现经济的可持续发展。本文采用DEA分析法对2012～2017年我国各省(区、市)的水资源和能源投入利用效率评价,对各省(区、市)的综合效率和规模效率进行分析,对各省(区、市)规模报酬进行判断,研究水资源、能源投入对经济的影响。接着采用投入产出法研究水资源和能源产业之间的相关联系,分析两者之间的供求关系和依赖程度。结果显示,我国省际经济与水资源和能源之间存在协同发展关系,水资源和能源投入将会刺激经济发展;整体上来看,水资源部门发展依赖能源部门的发展,个别地区能源部门对水资源部门依赖程度较高。     

通过倒序推理法确定火车煤管理流程时间

煤炭从发运、进站到接卸、上煤等一系列煤场管理流程间接影响着煤电企业的运营成本,流程中各环节衔接不顺畅、协调不及时则导致煤场混乱及影响机组安全运行。通过倒序推理法确定火车煤清晰的流程时间段,让火车在合理的时间内对位、翻卸堆料、上煤,以降低火车煤翻卸冲突与上煤冲突并预留设备的自检维护时间。外卸率由不稳定时的最高5.59%降至低于0.1%,设备故障率由每月平均70次~80次降低至平均50次~60次,增加了各部门管理协调的可操作性,可有效降低火电厂的经济运行成本并使煤场管理更加有序。     

A review on single bubble gas–liquid mass transfer

It is common to empirically correlate volumetric mass transfer coefficient k_La for predicting gas–liquid mass transfer in industrial applications, and the investigation of single bubble mass transfer is crucial for a detailed understanding of mass transfer mechanism. In this work, experiments, models and simulations based on the experimental results were highlighted to elucidate the mass transfer between single bubbles and ambient liquid. The experimental setups, measurement methods, the mass transfer of single bubbles in the Newtonian and the non-Newtonian liquid, models derived from the concept of eddy diffusion, the extension of Whitman's, Higbie's and Danckwerts' models, or dimensionless numbers, and simulation methods on turbulence, gas–liquid partition methods and mass transfer source term determination are introduced and commented on. Although people have a great knowledge on mass transfer between single bubbles and ambient liquid in single conditions, it is still insufficient when facing complex liquid conditions or some phenomena such as turbulence, contamination or non-Newtonian behavior. Additional studies on single bubbles are required for experiments and models in various liquid conditions in future.     

Advancements in Prelithiation Technology: Transforming Batteries from Li-Shortage to Li-Rich Systems

The sufficient and reversible active lithium is the cornerstone for the operation of high-energy lithium-ion batteries. However, active lithium is inevitably depleted due to the formation of a solid electrolyte and the presence of irreversible side reactions. The shortage of lithium in optimally designed batteries not only leads to a depreciation of energy density but also deteriorates the electrode structure resulting in degradation of cycle life. Inspiringly, prelithiation technology that additionally compensates for lithium has been proposed and is playing an increasingly significant role in enhancing battery energy density and prolonging cycle life. Herein, guided by the factors that initiate lithium loss, the action mechanism and the effectiveness of prelithiation are scrutinized. Moreover, the emerging advanced prelithiation technologies based on anode/cathode materials, the key barriers, and the applicability at scale are systematically summarized and compared. Integrating the challenges and development trends aspires to provide a comprehensive prelithiated hybrid lithium replenishment and storage technology as a reference in the scale-up of prelithiation technologies.     

西秦岭土壤和岩石光谱在风化作用中的演化

岩石与土壤的物质成分,以及反映物质成分的光谱特征,无疑存在着重要的依存关系。对西秦岭地区土壤及其母岩在0.4～2.5μm的实验室反射光谱进行分析,探讨了母岩在风化成壤过程中光谱特征的演化;不同成壤阶段,不同土壤层光谱的变异,以及有机质及铁氧化矿物成分增减对光谱的影响。了解这种光谱的演化过程,对于遥感岩性识别和遥感地质找矿应用,都具有重要的意义。