A cathode support structure for use in a magnetron oscillator experiment

A low temperature co-fired ceramic (LTCC) material system has been used to develop a protype field emission cathode structure for use in an experimental magnetron oscillator. The structure is designed for used with 30 gated field emission array (GFEA) die electrically connected through silver metal traces and electrical vias. To approximate a cylinder, the cathode structure (48 mm long and 13.7 mm in diameter) is comprised of 10 faceted plates which cover the GFEA dies. Slits in the facet plates allow electron injection. The GFEA die (3 mm × 8 mm) are placed in axial columns of 3 and spaced azimuthally around a cylindrical support structure in a staggered configuration resulting in 10 azimuthal locations. LTCC manufacturing techniques were developed in order to fabricate the newly designed cathode with seven layers wrapped to form the cylinder with electrical traces and vias. Two different cathode wrapping techniques and two different via filling techniques were studied and compared. Two different facet plate manufacturing techniques were studied. Finally, four different support stand configurations for firing the cylindrical structure were also compared with a square post stand having the best circularity and linearity measurements of the fired structure.     

三稳态压电能量采集器的动态特性与实验

为了探究三稳态压电振动能量采集器的动力学特性,以磁-机-压电耦合型三稳态压电振动能量采集器(tristable piezoelectric vibration energy harvester,简称TPVEH)为研究对象,利用磁荷法、力平衡和基尔霍夫定律分别建立了采集器末端磁铁与外部磁铁之间的非线性磁力模型和系统集总参数动力学模型。仿真分析了磁铁间距、激励加速度幅值和频率等参数对采集器动力学特性和采集电压的影响。研制了三稳态压电振动能量采集器原理样机,搭建了实验测试平台,实验验证了仿真结果的正确性。研究结果表明,随着激励加速度幅值增大,能量采集器依次经历单稳态、双稳态和三稳态3种运动状态,且三稳态运动时的工作频带和输出性能(位移、速度和采集电压)比双稳态和单稳态时要高。     

Halogenation effect promoted low bandgap polymers based on asymmetric isoindigo unit with low energy loss

To optimize the energy levels of the structural framework of isoindigo polymers, a series of asymmetric isoindigo based low bandgap polymers with chlorine, fluorine and thiazole substituents was constructed and their optical, electrochemical and photovoltaic properties were comparatively evaluated for the impact of different substitutions. In comparison with the polymer based on 2,2'‐bithiophene and isoindigo unit (PTi) with non‐substituted bithiophene as the donor moiety, the highest occupied molecular orbital energy level for the newly synthesized polymers is significantly decreased, and in turn an improvement of the open‐circuit voltage (V_OC) is noted in the corresponding photovoltaic devices. More importantly, combined with a low bandgap of 1.32 eV, the energy losses (E_loss) could be reduced to 0.61 eV for polymer based on chlorinated 2,2'‐bithiophene and isoindigo unit (PCl). In addition, the halogen moieties are observed to be superior in device fabrication and give better values than the thiazole substituent. Both fluorinated and chlorinated polymer donors exhibited improved performance compared with the original polymer PTi. Consequently, this work not only presents the influence of different electron withdrawing substituents on the physicochemical and photovoltaic performance, but also backs the concept of how to reduce the energy loss via the heteroatom effect. © 2020 Society of Chemical Industry     

一种数字式高温燃油控制阀的特性研究

该文提出了一种数字式高温燃油控制阀,可以实现对高温燃油的连续精确控制。首先,针对高温的恶劣工况,进行了方案设计,包括前置级伺服阀的选用、主阀阀口的设计、整阀的冷却设计,介绍了其结构组成及工作原理;之后分别对高温阀的热特性和控制特性进行了仿真分析,结果表明该方案的高温阀能够满足设计要求。     

300MW等级锅炉变工况低负荷稳燃能力数值模拟与预测

采用数值模拟软测量技术,在保证锅炉燃烧稳定和炉内温度较高水平的条件下,预测300 MW等级锅炉在实际运行中可降低到25%负荷稳定燃烧,并经过现场低负荷稳燃实验对结果进行验证。针对一次风速调整、磨煤机投运方式调整和配风方式及运行氧量调整三种方式对低负荷稳燃能力的影响进行分析,结果表明:在降负荷过程中调平一次风速偏差并适当降低一次风速,投运相邻层燃烧器,关小周界风,适当降低二次风量的同时适当降低运行氧量有利于提高低负荷稳燃特性。     

浅析煤矿综采放顶煤安全开采问题

以煤矿放顶煤安全开采问题为对象开展分析探究。结合具体工程实际,在分析综放工艺技术特征的基础上,对综采放顶煤安全开采需注意的问题与防范措施开展深入分析,希望能够为其他矿井综放开采的有效开展提供借鉴和帮助。     

高固气比技术在2 500 t/d水泥熟料线的改造案例介绍*

采用高固气比悬浮预热分解技术对宝江2 500 t/d生产线烧成系统进行技改后,预热系统出口温度从351℃降低至279℃,粉尘浓度(标况下,以下同)从151.6 g/m3减少至43.9 g/m3,系统分离效率大幅提高;入窑生料分解率从90.5%提高至98%,生产线熟料烧成煤耗从119.4kg/t降低至100.80kg/t,熟料产量从2744t/d提高至3840t/d,各指标均属领先水平。     

Combustion behaviors and explosibility of suspended metal hydride TiH2 dust

In the production and storage processes of metal hydride material of TiH₂, there are at least three kinds of explosion hazards, for example, TiH₂ dust explosion, H₂ explosion and hybrid H₂/TiH₂ dust explosion. In this study, combustion behaviors of TiH₂ dust cloud under isobaric and isochoric conditions were studied using a visual dust combustion facility and a standard 20-L spherical explosion vessel bomb, respectively, and Ti dust and hybrid H₂/Ti dust were used as the reference materials. Experimental results showed that at equal dust concentrations, the flame propagation speed S_f, burning velocity S_L, maximum pressure rise P_ex and maximum rate of pressure rise (dP/dt)_ex of TiH₂ dust were all higher than those of Ti dust, while much smaller than those of hybrid H₂/Ti dust except the maximum pressure rise P_ex. The hydrogen state and content were the primary factors for the combustion differences of dust explosions. The values of explosion index K_st showed that the explosion risks of these samples increased as follows: Ti ˂ TiH₂ ˂ hybrid H₂/Ti dust.     

基于数据驱动理念的电力日负荷曲线预测方法研究

针对短期日负荷预测的精度问题,本文提出一种基于数据驱动理念的电力负荷预测方法。在建立预测模型前对所给数据采取一定的预处理:首先提取所收集的海量数据的负荷特征,对负荷特征进行分析,然后进行负荷数据与影响负荷值的因素之间的相关性分析,以此确定对负荷影响较密切的因素,随后建立分类器得到各主要影响因素与各负荷类别之间的关系为后续预测模型奠定基础。对预处理后得到的不同类型的负荷数据采用最小二乘支持向量机方法建立不同的负荷预测模型。以南方某发达城市2008年的负荷数据作为算例验证数据,将本文所提负荷预测方法所得结果与未经数据预处理的负荷预测方法所得结果进行比较,结果表明本文提出的方法得到的预测结果精度较传统方法提高约6%。     

40万t/年转炉钢渣蒸汽陈化处理生产线

介绍了针对国内某炼钢厂专门设计的40万t/年转炉钢渣蒸汽陈化处理生产线主要参数及工艺流程,对该生产线中的钢渣倾翻车、钢渣冷却搅碎车、转运车、蒸汽陈化釜等主要设备特点进行了阐述,同时对该生产线应用的冷却水量研究、搅碎辊轨迹优化等关键技术作了进一步的探讨。