Dual effect synergistically triggered Ce:(Y,Tb)3(Al,Mn)5O12 transparent ceramics enabling a high color-rendering index and excellent thermal stability for white LEDs

Ce:Y₃Al₅O₁₂ transparent ceramics (TCs) with appropriate emission light proportion and high thermal stability are significant to construct white light emitting diode devices with excellent chromaticity parameters. In this work, strategies of controlling crystal-field splitting around Ce³⁺ ion and doping orange-red emitting ion, were adopted to fabricate Ce:(Y,Tb)₃(Al,Mn)₅O₁₂ TCs via vacuum sintering technique. Notably, 85.4 % of the room-temperature luminescence intensity of the TC was retained at 150 °C, and the color rendering index was as high as 79.8. Furthermore, a 12 nm red shift and a 16.2 % increase of full width at half maximum were achieved owing to the synergistic effects of Tb³⁺ and Mn²⁺ ions. By combining TCs with a 460 nm blue chip, a warm white light with a low correlated color temperature of 4155 K was acquired. Meanwhile, the action mechanism of Tb³⁺ ion and the energy transfer between Ce³⁺ and Mn²⁺ ions were verified in prepared TCs.     

Effects of anion and cation doping on the thermoelectric properties of n-type PbS

The PbCl_xS_1-x and Pb_1-xBi_xS (x? =?0–0.05) bulks were fabricated with a facile method of hydrothermal synthesis and microwave sintering, and the effect of anionic and cationic donors on the thermoelectric performance of PbS was investigated. Although Cl^? and Bi³⁺ both effectively improved the thermoelectric properties of n-type PbS, more excellent thermoelectric performance was obtained from Cl^? doped samples because of higher electrical property and lower thermal conductivity at higher temperature (T? >?600?K). The thermoelectric figure of merit (ZT) reaches 1.04 for PbCl_0.015S_0.985 at 800?K and increases with temperature increasing without sign of saturation, which is probably the highest value ever reported for single-phase polycrystalline n-type PbS. The results also indicate that the hydrothermal synthesis and microwave sintering can realize anion doping as well as cation doping for n-type PbS at low cost, and PbS should be a robust alternative for PbTe thermoelectric materials.     

多类型源储协调互动的配电网分布鲁棒优化调度

分布式光伏、风电等可再生能源出力具有较强的随机性和不确定性,其大量并网给配电网的运行带来了极大的挑战。本文提出了一种多类型源储协调互动的配电网分布鲁棒优化调度方法,基于分布鲁棒优化理论,对配电网中传统离散设备、可再生能源以及储能决策进行协调优化,提高配电网运行的经济性和安全性,实现了配电网运行决策保守性与鲁棒性的有效平衡。首先,考虑多类型源储资源的协调互动,建立配电网优化调度模型,并将其转化为混合整数二阶锥规划的形式;其次,利用可再生能源出力场景集进行不确定性刻画,建立分布鲁棒优化模型,并通过列和约束生成算法进行求解;最后,在PG&E69节点系统上进行算例分析,验证了所提方法的可行性与准确性。     

基于转轮换型的水轮机增容改造及数值模拟

从青海铁吾电站HL160-WJ-84水轮机运行中的实际问题出发,在明确了水轮机改造的方向和目标后,对新旧型谱系列模型转轮的性能进行了对比分析。基于对比结果,初选出了D06A转轮用于技术改造试验。对改造前后的水轮机全流道进行三维湍流数值计算,给出了水轮机改造前后的水动力学特性差异。同时,对改造前后的水轮机蜗壳、转轮叶片的流态分布状况进行了分析比较,对改造后的水轮机整体水力性能进行预估。分析认为,对于小型卧式HL160机组而言,更换转轮后还需对上冠泄水孔实施改造,以防止对流场造成扰动,降低机组的效率。     

峡谷和垭口地形风场特征的CFD数值模拟

为获得峡谷和垭口地形的风场特征和典型位置的风加速效应,采用计算流体动力学(CFD)方法进行模拟计算,将计算得到的单山结果与风洞试验及规范进行对比以验证CFD计算的有效性,对峡谷和垭口地形进行数值模拟计算,分析峡谷和垭口在不同山脚间距时的加速效应,针对内侧山脚和山顶处的加速比给出设计建议.研究表明:山顶处加速比最大;山体横风切面的加速效应比顺风切面显著;CFD模拟与风洞试验结果吻合较好;山顶处,垭口地形风加速效应比峡谷和单山都大;内侧山脚加速比随着两山靠近而增大;内侧山脚处,峡谷地形的加速比小于规范下限,垭口地形在山间距小于一半山体底部直径、离山表面高度低于0.4倍山体高度时的加速比大于规范上限;山顶处的加速比在各种工况下均比较接近;不建议将山顶和垭口位置作为构筑物的选址地点.     

红河油田空气泡沫驱实验

鄂尔多斯盆地南部红河油田长8油藏为典型的致密双重介质储层,注水采油时出现沿裂缝水窜现象,导致开发效果变差.为有效补充地层能量、提高采收率,开展红河油田长8储层空气泡沫驱实验.通过空气原油氧化实验,确定红河油田原油与空气在地层条件下可以发生低温氧化反应,反应速率为(0.025~0.110)×10-5 mol(O2)/(h·g)(oil);通过泡沫体系优选实验,优选阻力因子高、封堵能力强、可有效封堵储层裂缝的泡沫体系;通过长岩心空气泡沫驱油实验,认为空气泡沫驱的采收率比水驱的提高15%以上,气体突破时产出气体中O2的体积分数为1.34%~3.81%,满足空气驱的安全范围.结果表明:空气泡沫驱综合泡沫驱与空气驱的稳定、耐温、耐油和较强封堵能力等优点,在红河油田具有较好适用性,为红河油田提高采收率提供技术储备.     

电力市场环境下虚拟电厂经济效益敏感因素分析

随着我国对新型电力系统建设要求的不断明确,虚拟电厂（virtual power plants,VPP）的建设得到了业界的广泛关注。然而,在虚拟电厂规模化推进建设和运营过程中,市场化环境下的经济效益影响因素尚未得到充分研究。针对此问题,对虚拟电厂的建设投资成本、运营成本和收益情况进行梳理,构建了虚拟电厂经济效益模型;进一步,在市场化收益的视角下选取敏感因素,提出虚拟电厂参与不同市场交易品种的经济效益分析方法;最后,给出算例验证,讨论了虚拟电厂经济效益在不同敏感因素条件下的变化趋势。研究结果可为新型电力系统市场环境下的虚拟电厂合理有效回收成本、参与市场交易提供客观的评价方法支持。     

Concurrency control in mobile distributed real-time database systems

This paper presents DMVOCC-2PLV (Distributed Multiversion Optimistic Concurrency Control with Two-Phase Local Validation) protocol for processing mobile distributed real-time transactions in mobile broadcast environments. In DMVOCC-2PLV protocol, transaction validation is performed at two levels: local validation and global validation. Local validation of transactions is performed in two phases: local pre-validation and local final validation. At the MHs (Mobile Hosts), all mobile transactions perform local pre-validation of transactions by using a backward validation mechanism. The local pre-validation process is carried out against committed transactions at the server in the last broadcast cycle. Such an early data conflict detection feature can save processing and communication resources. Transactions that survive in local pre-validation must be submitted to the server for local final validation. In global validation distributed update transactions have to check to ensure distributed serializability in all participants. The protocol can eliminate conflicts between mobile read-only and mobile update transactions, and resolve data conflicts flexibly using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly reduced. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. The results of simulation experiment show that the new protocol proposed offers better performance in terms of miss rate, restart rate, commit rate and throughput.     

计算机在兽药中的应用

兽药企业间的竞争加剧,提高生产效率、降低生产成本,进而提升企业的核心竞争力,是兽药企业在竞争中取得有利地位的重要途径之一。计算机在兽药中的应用有效提高了兽药企业生产效率、降低了生产成本。文章介绍了计算机在兽药中各个方面的应用,可为兽药企业提供参考。     

面向对象技术的机器翻译系统的设计与实现

在分析以往机器翻译系统的基础上,针对以信息提取为目的的机器翻译系统在行业内的应用提出了一个基于面向对象技术（OOT）的机器翻译系统的模型,并在文中给出了该模型的面向对象描述,利用该模型可以快速建立灵活的机器翻译系统。