600 MW机组凝结水泵的变频改造

国电大同发电有限公司为了实现机组的节能降耗,提高企业的经济效益,对8号机组凝结水泵进行了变频改造。为此介绍热工方面改造的方案、改造后的运行情况及存在的问题。     

风力机参数的可辨识分析

风力机是风电机组吸收和转化风能的关键设备,准确的模型和参数是机组优化运行和控制的基础。文中基于风力机常用的高精度数学模型,运用计及实际运行工况的风力机的可测量量,进行参数的可辨识性理论分析,结果表明风力机的参数可辨识。     

不同煤级区煤层气可动性和初始排水速度控制策略

对中国20个区块/煤矿煤层气地质参数进行了系统整理,开展了煤层气吸附时间和渗透率随煤级变化规律分析,并结合不同煤级区煤层气井的产气曲线,揭示了峰值产量出现前后不同煤级区产气动态差异的原因,以期为不同煤级区初始排水速度控制提供依据。研究结果表明：①吸附时间随煤级升高呈"U"型变化规律,中、低煤级区煤岩吸附时间一般低于15 d,高煤级区吸附时间变化大,吸附时间在0.1~85.54 d变化;②区块/煤矿间煤储层渗透率随煤级升高没有明显的规律性变化,同一区块内部,渗透率变化级差达2~3个数量级;③峰值产量出现时间与初始排水速度和煤岩吸附时间有较好的对应关系,而与渗透率的关系不明显;④在不同煤级区,针对不同井层煤储层吸附时间与渗透率的配置关系,应采用针对性初始排水速度控制策略：中、低煤级区煤岩吸附时间短,对低渗透井层应严格控制初始排水速度;高煤级区吸附时间变化区间大,对吸附时间长、渗透率高的井层,可适当加快初始排水速度。     

四川盆地中部中二叠统热液白云岩储渗空间类型及成因

近年来,四川盆地川西北地区有多口井在中二叠统栖霞组、茅口组钻获高产气流,展现出该层系巨大的天然气勘探潜力,但有关该盆地中二叠统白云岩储层的成因机理则众说纷纭,一直未达成共识。为此,基于川中地区栖霞组、茅口组岩心及薄片等岩相学特征,以及碳、氧、锶同位素和包裹体均一化温度等地球化学特征,开展了中二叠统热液白云岩储渗空间类型及储渗相特征研究,分析了白云岩储层的成因及其控制因素。结果认为:(1)茅口组、栖霞组石灰岩地层经历了构造控制热液活动,发育萤石、鞍状白云石、天青石的热液矿物组合和膨胀角砾结构;(2)较之于宿主石灰岩,细—中晶云岩和鞍状白云石均呈现出δ18O负偏移、87Sr/86Sr正偏移;(3)中二叠统形成由热液溶孔、热液白云岩晶间孔、热液溶洞、热液扩溶缝等4种储渗空间构成的热液白云岩储渗体。结论认为:(1)热液白云岩储集相发育和分布受深大断裂的控制,呈"透镜状"分布在具"下凹"地震反射特征的区域;(2)中二叠统热液白云岩储集相与下伏烃源岩和上覆封堵层的有机组合可构成有利的天然气勘探目标。     

环形网络的业务误连接及防止

本文详细介绍了环形中复用段共享保护方式下业务连接的产生原因,解决办法,并给出了一个实用的压制时隙计算算法。     

A Quaternary van der Waals Ferromagnetic Semiconductor AgVP2Se6

The recent realization of 2D magnetism in van der Waals (vdWs) magnets holds promise for future information technology. However, the vdWs semiconducting ferromagnets, which remain rare, are especially important in developing 2D magnetic devices with new functionalities due to the possibility of simultaneous control of the carrier charge and spin. Metal thiophosphate (MTP), a multifunctional vdWs material system that combines the sought‐after properties of complex oxides, is a promising vdWs magnet system. Here, single crystals of a novel vdWs ferromagnetic semiconductor MTP AgVP₂Se₆ with a room‐temperature resistivity of 1 Ω m are successfully synthesized. Due to the nature of vdWs bonding along the c‐axis, the magnetic properties of the few‐layer AgVP₂Se₆ with different thicknesses are characterized on the exfoliated samples. The AgVP₂Se₆ flakes exhibit significant thickness‐dependent magnetic properties, and a rectangular hysteresis loop with a large coercive field of 750 Oe at 2 K and an undiminished Curie temperature of 19 K are observed in the 6.7 nm AgVP₂Se₆ flake. The discovered vdWs ferromagnet AgVP₂Se₆ with semiconducting behavior will provide alternative platforms for exploring 2D magnetism and potential applications in spintronic devices.     

Achieving Rich and Active Alkaline Hydrogen Evolution Heterostructures via Interface Engineering on 2D 1T‐MoS2 Quantum Sheets

Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS₂ nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active ${\text{edge}}_{{\text{1T‐MoS}}_{\text{2}}}$/ ${\text{edge}}_{\text{Ni}{(\text{OH})}_{\text{2}}}$ heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich ${\text{edge}}_{{\text{1T‐MoS}}_{\text{2}}}$/ ${\text{edge}}_{\text{Ni}{(\text{OH})}_{\text{2}}}$ sites, the fabricated 1T–MoS₂ QS/Ni(OH)₂ hybrid (quantum sized 1T–MoS₂ sheets decorated with Ni(OH)₂ via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm^?2, respectively, and has a low Tafel slope of 30 mV dec^?1 in 1 m KOH. So far, this is the best performance for MoS₂‐based electrocatalysts and the 1T–MoS₂ QS/Ni(OH)₂ hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm^?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions.     

Thermal Shrinkage Behavior of Metal–Organic Frameworks

Thermal treatment of metal–organic frameworks (MOFs) as a post‐treatment approach has grown in popularity and resulted in various MOF‐derived materials. However, the widely used extreme thermolytic conditions (usually above 500 °C) lead to degradation in the well‐defined MOFs intrinsic properties. This work demonstrates that MIL‐101 calcined at medium‐temperature range (200–280 °C) partially breaks the coordination bonds that can introduce more accessible active sites, exhibiting a 10‐fold increase in oxidation activity while retaining its intrinsic structure and porosity. Another fascinating feature of MIL‐101 calcined in this temperature range is their temperature‐dependent shrinkage behavior, which is also found in many other types of MOFs. Based on different shrinkage ratios of various MOFs, yolk–shell MOFs@MOFs structures can be constructed through nonsacrificial template method. Overall, the structural and morphological evolution process of MOFs treated in the medium‐temperature range can open new horizons to develop efficient MOFs catalysts and design complex structures.     

p型微晶硅薄膜的沉积及其在微晶硅薄膜太阳电池中的应用

采用等离子体化学气相沉积（PECVD）方法制备了硼掺杂微晶硅薄膜和微晶硅薄膜太阳电池.研究了乙硼烷含量、p型膜厚度及沉积温度对硼掺杂薄膜生长特性和高沉积速率的电池性能的影响.通过对p型微晶硅薄膜沉积参数的优化,在本征层沉积速率为0.78nm/s的高沉积速率下,制备了效率为5.5%的单结微晶硅薄膜太阳电池.另外,对p型微晶硅薄膜的载流子疏输运机理进行了讨论.     

基于分段PID实现永磁同步电机快速启停控制技术的研究

扫描镜常用于获取空间光电信息,应用中对其快速启停和指向精度有较高的要求。针对永磁同步电机驱动扫描镜的运动方式,建立了电机Simulink仿真模型,并采用了三闭环矢量控制策略,提出了采用分段式比例积分微分(Proportion Integration Differentiation, PID)算法进行位置环控制的方法。结果表明,相较于传统的PID,分段式PID提高了系统的响应速度,同时控制精度和稳定性也有一定提升。