α-芳族酮酸钛盐和锂试剂还原反应机理初探

对钛调整体系中的一种新的还原反应的机理进行推证,证明体系的还原反应中存在一种类似Meerwein-Ponderf-Verley还原反应的分子内氢迁移反应,同时证明体系中的锂试剂以2种不同的方式促进了该还原反应的进行。     

疏松砂岩油藏封隔颗粒防砂控水技术矿场实践

南海东部的F油田为疏松砂岩稠油油田,针对投产后出现的储层出砂堵塞筛管,油井产量递减快、见水后含水上升快等难题,在充分调研常规防砂控水技术优缺点的基础上,提出了一种由亲油疏水材料构成的封隔颗粒防砂控水技术。利用实验、油藏工程、数值模拟等方法评价了封隔颗粒的防砂控水效果。结果表明：封隔颗粒防砂控水技术具有无需找水、全井段控水、防砂、绿色环保等多种优势,配合自适应流量控水阀(autonomous inflow control device, AICD),防砂控水效果进一步提升;F油田部分单井矿场采用封隔颗粒防砂控水后,有明显的无水采油期,在相同采出程度的情况条件下,含水上升率明显更低,防砂控水增油效果显著。该技术为类似疏松砂岩油田的防砂控水开发提供了借鉴,推广前景良好。     

添加ZrO_2对镁钙砂抗水化性能的影响

以w(CaO)为55%的镁钙砂细粉为原料、ZrO_2为添加剂,在1550℃温度下烧结5h制备镁钙试样,研究了添加ZrO_2对镁钙试样物相组成、显微结构、烧结性能和抗水化性能的影响。结果表明,添加ZrO_2能促进镁钙材料的烧结,且随着ZrO_2加入量的增加,试样的体积密度逐渐增大,显气孔率减小,抗水化性能逐渐增强,这是由于ZrO_2的加入增大了Ca~(2+)的空位浓度,有利于Ca~(2+)的扩散,促进了镁钙试样的烧结致密化和试样中CaO晶粒的长大。此外,ZrO_2还可与游离态CaO反应生成不易水化的CaZrO_3,该反应发生在晶界等容易水化的部位,改变了镁钙试样的显微结构,又进一步提高了材料抗水化性能;当ZrO_2添加量超过5%后,试样的各项性能变化趋于平缓。综合考虑,该镁钙试样中ZrO_2的适宜添加量为5%。     

Missile robust gain scheduling autopilot design using full block multipliers

Reduction of conservatism is one of the key and difficult problems in missile robust gain scheduling autopilot design based on multipliers. This article presents a scheme of adopting linear parameter-varying (LPV) control approach with full block multipliers to design a missile robust gain scheduling autopilot in order to eliminate conservatism. A model matching design structure with a high demand on matching precision is constructed based on the missile linear fractional transformation (LFT) model. By applying full block S-procedure and elimination lemma, a convex feasibility problem with an infinite number of constraints is formulated to satisfy robust quadratic performance specifications. Then a grid method is adopted to transform the infinite-dimensional convex feasibility problem into a solvable finite-dimensional convex feasibility problem, based on which a gain scheduling controller with linear fractional dependence on the flight Mach number and altitude is derived. Static and dynamic simulation results show the effectiveness and feasibility of the proposed scheme.     

一类域上的混合模空间的有界算子

本讨论一类Ｒｅｉｎｈａｒｄｔ域上的混合模空间的投影算了，证明这类算子的有界性。     

浅析古希腊哲学家的灵魂学说

灵魂问题在古希腊哲学中占有非常重要的位置."灵魂"一词含义广泛.且有一个较为复杂的演化过程.弄清"灵魂"一词的含义和演变过程,对于我们正确认识古希腊哲学家的思想,了解"精神"范畴的形成及其和物质的对立,反对宗教迷信,有重要的理论意义和现实意义.     

Vectorial holography-mediated growth of plasmonic metasurfaces

Nowadays,the electromagnetic properties of artificial photonic materials can be well-tuned via designs over their composition and geometries.However,engineering...     

Single-cell atlas of domestic pig cerebral cortex and hypothalamus

The brain of the domestic pig(Sus scrofa domesticus)has drawn considerable attention due to its high similarities to that of humans.However,the cellular composi...     

Moving beyond Volatility Index (VIX): HARnessing the term structure of implied volatility

This paper considers how information from the implied volatility (IV) term structure can be harnessed to improve stock return volatility forecasting within the state-of-the-art HAR model. Factors are extracted from the IV term structure and included as exogenous variables in the HAR framework. We found that including slope and curvature factors leads to significant forecast improvements over the HAR benchmark at a range of forecast horizons, compared with the standard HAR model and HAR model with VIX as IV information set.