MgCl2·6H2O热分解过程的阿姆斯特丹密度泛函理论研究

利用阿姆斯特丹密度泛函理论对MgCl₂·6H₂O的热分解反应进行理论计算,结合对其热分解过程的实验研究数据,从理论层面探讨其热分解的机理,为掌握氯化镁水合物分解条件、控制反应路径,获取目标产物提供理论依据。通过ADF理论计算并结合实验研究得出,MgCl₂·6H₂O脱除HCl需要较高能量,为5246.59 kJ/mol,是MgCl₂·6H₂O脱除H₂O分子需要能量的6.45倍,是MgCl₂·5H₂O脱除H₂O所需能量的10.69倍。可见在同等温度条件下,MgCl₂·6H₂O首先发生的是脱除H₂O分子反应,在MgCl₂·6H₂O脱除2分子H₂O之前不会发生MgCl₂·6H₂O脱除HCl的反应。     

SF6气体的过热分解特性随温度的发展趋势研究

为了深入探究故障温度与SF6过热分解之间的关系,克服对运行中设备进行故障发展程度监测的困难,通过设计局部发热元件进行过热故障模拟,在该平台上开展200 ℃ ~ 360 ℃模拟实验。结果表明：SF6在200 ℃时就开始出现分解,故障温度较低时,SF6分解产物主要存在形式为SO2;中温段开始新生成SOF2;SO2F2、COS、H2S在高温下才产生,该三种产物的检出可表征设备已发生严重过热故障。此外,还定义了C（SO2F2 + SOF2）/C（SO2）特征比值量,其与故障发展趋势紧密相关,该值越大,揭示了SF6气体绝缘劣化越严重,电气设备故障发展程度就越严重。     

一种估算CO2和SO2在多元胺水溶液体系中溶解度的数学模型

通过离子反应式和亨利定律建立数学模型,在对模型进行适当简化的基础上再借助编程手段可以得到CO₂-SO₂在H₂O-MDEA-活化胺复杂多元溶液体系中溶解度的数值解。研究表明,在MDEA质量分率30%的水溶液中SO₂比CO₂优先溶解,溶液只有在基本上完全吸收SO₂之后才会吸收CO₂;而且其溶解度比较大,常温常压下1 mol的MDEA可吸收超过1.4mol的SO₂气体。在气体分压为（1～100）kPa范围内,SO₂的溶解度受压力参数的影响较大:而在此压力范围之外,温度参数则成为主要影响因素。在MDEA水溶液中添加MEA或DEA活化剂,随着活化剂质量分率的增加,SO₂的溶解度有较大程度的下降;若同时添加MEA-DEA2种活化剂,SO₂的溶解度会随着MEA质量分率的增加而减小,但减少的幅度并不大。     

145 kV SF6/N2混合气体GIS的研制

为响应国家绿色低碳环保的号召,开展SF₆/N₂混合气体GIS的研制。介绍了SF₆/N₂混合气体的混合比、充气压力的选择及设计压力的计算方法。最后,145 kV SF₆/N₂混合气体GIS(断路器除外)通过了全部试验。     

基于DCNN的SF6气体在线监测系统设计

针对传统SF₆气体泄漏检测方法存在图像采集和泄漏识别精度低的问题，提出设计一种基于DCNN网络的SF₆气体在线监测系统。首先，采用OV78和MSP430单片机进行泄漏气体图像采集；然后通过WIFI无线通信将采集数据输入至深度学习模块中进行GMM泄漏区域提取和多特征提取；最后采用DCNN神经网络进行SF₆气体泄漏准确识别和分类。实验结果表明，相较于传统的Lenet-5、ZF-net和Alexnet经典网络，提出的DCNN方法无论在网络性能，还是在识别的准确率方面，均具备良好的表现，其识别准确率最高可达82%,识别性能均优于另外三种网络模型。实际应用表明，该方法具有良好的检测效果。由此说明本文构建的系统可用于电力中的SF₆气体在线监测，保障电力的安全。     

1000MW燃煤机组排放SO2浓度扩散模拟研究

1000MW燃煤机组火电厂排放污染气体中二氧化硫(SO₂)浓度是我国火电厂排放污染的重点控制目标,为了研究SO₂浓度扩散对周围环境及人们身体健康造成的影响,对SO₂浓度扩散进行了模拟研究。首先,根据电厂的实际排放数据建立了高斯羽流扩散模型,利用该模型模拟在大气稳定度相同的情况下模拟不同的风速对SO₂浓度扩散分布规律的影响,并且分析SO₂浓度扩散的距离及范围。结果表明,SO₂浓度扩散与风速及大气稳定度有着密切的关系,风速越大,越有利于SO₂浓度扩散及气体的稀释,并证明了利用高斯烟羽模型模拟有害气体扩散具有较好的实际参考意义。     

基于5G通信技术的变电站SF6气瓶智能管理系统设计

为确保变电站六氟化硫(SF₆)气瓶智能管理的时效性和可靠性,设计基于5G通信技术的变电站SF₆气瓶智能管理系统。通过SF₆气体采集器等装置,感知并采集变电站SF₆气瓶的状态数据。将该数据通过由5G通信技术构建的5G传输模块,传送至管理模块,并采用5G切片技术划分网络,以实现按需通信。管理模块接收经由5G传输模块传送的数据后,基于非分光红外差分检测方法,在线智能检测SF₆气瓶的泄漏浓度,并校核SF₆气体在线监测结果,以实现SF₆气瓶的智能管理。测试结果表明：网络传输平均速率在8～10 Gbit/s之间,极大程度接近传输速率峰值,通信的实时性良好;能够实时监测SF₆气瓶运行状态,在线监测精度较高,平均偏移程度低于0.035。该系统可全面呈现气体的泄漏情况,以及发生泄漏的时间和泄漏气体的浓度情况。     

基于VO2的超表面双气体传感器设计

针对传统矿用气体传感器易受温度和环境湿度等因素的影响而导致稳定性不高的问题,基于局域表面等离子共振原理和二氧化钒(VO₂)的相变特性,设计了一种基于VO₂的超表面双气体传感器。该传感器结构由上下三层组成,表面由多层金属-介电-金属(MDM)结构组成。根据VO₂的相变特点,通过改变施加的偏置电压,以电阻加热的形式加热金属板,精细控制VO₂的温度,通过改变VO₂的电导率来模拟VO₂的不同状态。当VO₂呈高温金属态时,上三层形成MDM结构,VO₂表现出金属性质,并在1 721.3 nm激发局域表面等离子体共振(LSPR),实现甲烷检测,传感器的吸收率为94.3%,甲烷灵敏度为4.21 nm/%。当VO₂呈低温绝缘态时,下三层形成MDM结构,在2 694.6 nm激发LSPR,实现氢气检测,传感器的吸收率为95.9%,氢气灵敏度为2.10 nm/%。当环境折射率发生变化时,VO₂     

基于OMI/OMPS中国季风区大气边界层SO2时空格局分析

为研究季风对大气边界层 SO₂变化的影响,利用2005~2014年OMI SO₂、2015~2017年OMPS NMSO₂遥感数据,选取中国季风区为研究对象,分析大气边界层SO₂时空分布特征,并选取4座典型城市,通过相关性分析和HYSPLIT后向轨迹模拟。结果表明：中国季风区PBL SO₂空间上呈现异质性,冬、夏季风变迁对于季风区大气边界层 SO₂柱浓度变化影响明显;温度和气压是影响大气边界层 SO₂柱浓度的主要气象因子,其次是地域性气象条件;冬季气流对日SO₂柱浓度升高影响较大,四川盆地及来自印度半岛、孟加拉湾的西南气流对重庆市SO₂柱浓度升高效果显著,银川市SO₂受蒙古高原偏北气流及天山北部西北气流影响,天津市和杭州市受华北平原及蒙古高原地区气流的作用。     

不同预氧化程度焦煤CO2冷却后自燃特性研究

针对利用惰性气体降低煤氧化性来解决煤自燃、复燃的问题,现有研究大多是对煤低温氧化过程及煤复燃过程进行相关实验,对惰性气体降温后煤二次氧化的自燃特性涉及较少。针对上述问题,以焦煤为例,通过低温氧化实验,探究不同温度氧化的焦煤经过CO₂冷却二次氧化的自燃特性。采用GC-4000A程序升温装置对焦煤进行预氧化(预氧化温度分别设为70,110,150℃),并对分别通入CO₂气体和干空气冷却至30℃后焦煤二次氧化过程中的耗氧速率、CO产生率、CO₂浓度和表观活化能进行分析。实验结果表明：预氧化温度相同时,与干空气冷却相比,通入CO₂冷却后的焦煤相关参数的变化规律基本一致,二次氧化初期,因预氧化焦煤吸附大量CO₂,阻碍了煤与O₂接触,耗氧速率和CO产生率减小,表观活化能增大,焦煤的氧化性减弱;随着CO₂解析,CO₂冷却也影响预氧化焦煤的后期反应,使得预氧化焦煤整个反应过程自燃危险性降低。预氧化温度不同时,70℃和110℃预氧...     

Titania NOx sensors for exhaust monitoring

Oxide semiconductors have been examined to develop NO_x sensors for exhaust monitoring. Titania doped with trivalent elements, such as Al³⁺, Sc³⁺, Ga³⁺ or In³⁺, has a good sensitivity and selectivity to NO between 450 and 550 °C, and shows rapid response. A sensor probe for monitoring exhaust NO_x has been fabricated. Many kinds of interference gases, such as C₃H₆, CO and SO₂, have been found to have only a slight influence on the sensor response to NO. The influence of O₂ and H₂O is also negligible, except for the cases of 0% H₂O and fuel-rich conditions. In accordance with these results, the sensor probe operates satisfactority in the exhaust gas of various combustion conditions without interference from the various kinds of gas species in the exhaust gases.     

Etch rates for micromachining processing

The etch rates for 317 combinations of 16 materials (single-crystal silicon, doped, and undoped polysilicon, several types of silicon dioxide, stoichiometric and silicon-rich silicon nitride, aluminum, tungsten, titanium, Ti/W alloy, and two brands of positive photoresist) used in the fabrication of microelectromechanical systems and integrated circuits in 28 wet, plasma, and plasmaless-gas-phase etches (several HF solutions, H₃PO₄, HNO₃ +H₂O+NH₄F, KOH, Type A aluminum etchant, H ₂O+H₂O₂+HF, H₂O₂, piranha, acetone, HF vapor, XeF₂, and various combinations of SF₆, CF₄, CHF₃, Cl₂, O₂ , N₂, and He in plasmas) were measured and are tabulated. Etch preparation, use, and chemical reactions (from the technical literature) are given. Sample preparation and MEMS applications are described for the materials     

CuO/SnO2 thin film heterostructures as chemical sensors to H2S

CuO/SnO₂ heterostructures as well as SnO₂(CuO) polycrystalline films have been studied for H₂S sensing. Gas sensing properties of these materials have been compared in conditions: 25–300 ppm H₂S in N₂ at 100–250°C. A shorter response time of the heterostructures as compared to that of the SnO₂(CuO) films has been found. It is suggested that the improvement of dynamic sensor properties of SnO₂/CuO heterostructures is caused by the localization of electrical barrier between CuO and SnO₂ layers.     

Electrochemical measurement of SO3-SO2 in process gas streams

The two major industrial sources of sulphur dioxide emissions are electrical generation and non-ferrous smelting. While flue-gas scrubbing and acid-plant technology are well established, continuous methods for the determination of SO₂ in these process streams are based on expensive conventional UV or IR spectroscopic instrumentation in which the gases must be conditioned prior to analysis. Additionally, there appears to be no reliable continuous low-maintenance method of analysis for SO₃ in gases. Solid-state sensors for the continuous real-time measurement of concentrations of SO₃ and SO₂ in process gas streams offer the possibility of monitoring the efficiency of flue-gas scrubbing, determining the concentrations of SO₃ in corrosion-susceptible ducting or in acid-plant conversion towers and guarding against excessive releases of SO₃ from acid-plant tail gas. The measurement of SO₂ and SO₃ in gases by solid-state electrochemistry is reviewed. The electrochemical cells are described, and wherever possible, the temperature and concentration ranges of the various solid-state devices reported in the literature are given. We conclude with a summary of the further requirements for a successful inexpensive commercial solid-state sensor for SO₃ and SO₂ measurement in process gas streams.     

Development of an optical hydrogen sulphide sensor

A hydrogen sulphide (H₂S)-sensitive optode film has been fabricated by immobilising tetraoctylammonium fluorescein mercury(II) acetate (TOFMA) and tri-n-butyl phosphate in a poly(vinyl chloride) (PVC) matrix. The optode film, coated on an overhead transparency film, was employed as a sensing device for fluorimetric detection of H₂S. The fluorescence intensity monitored at 553 nm (excitation at 503 nm) increased with increasing H₂S concentrations. The optode film showed a good, linear and reversible response to H₂S from 0 to 15 ppm (v/v). It was optically stable and the reproducible response of the film on exposure to 10 ppm (v/v) H₂S was extremely good. There was no sign of degradation after 8 h of continuous use. The response to H₂S levelled off at about 27.5 ppm The response and recovery times of the optical H₂S sensor were fast and less than 2 and 5 s, respectively. An optically-based sensor for H₂S determination was successfully developed. It was anticipated that the system could be used to monitor H₂S with a concentration range of 0–25 ppm (v/v) with satisfactory results. A proposed mechanism for the detection of H₂S by the optode films is described.     

Robust Fault Detection and Isolation Based on Finite-frequency H?/H∞ Unknown Input Observers and Zonotopic Threshold Analysis

This work proposes a robust fault detection and isolation scheme for discrete-time systems subject to actuator faults, in which a bank of H_?/H_∞ fault detection unknown input observers (UIOs) and a zonotopic threshold analysis strategy are considered. In observer design, finite-frequency H_? index based on the generalized Kalman-Yakubovich-Popov lemma and H_∞ technique are utilized to evaluate worst-case fault sensitivity and disturbance attenuation performance, respectively. The proposed H_?/H_∞ fault detection observers are designed to be insensitive to the corresponding actuator fault only, but sensitive to others. Then, to overcome the weakness of predefining threshold for FDI decision-making, this work proposes a zonotopic threshold analysis method to evaluate the generated residuals. The FDI decision-making relies on the evaluation with a dynamical zonotopic threshold. Finally, numerical simulations are provided to show the feasibility of the proposed scheme.      

Performance evaluation of an SnO2-based sensor array for the quantitative measurement of mixtures of H2S and NO2

In this paper formed by SnO₂-based sensors, for the quantitative measurement of H₂S and NO₂ mixtures, have been studied. The performance of the arrays, obtained by merging together a set of SnO₂ sensors of different kinds, has been evaluated in terms of a set of figures of merit. The analysis allows us to select the arrays with the best performance among all the possible configurations obtainable using the available set of sensors.     

Plasma planarization for sensor applications

Filling trenches in silicon using phosphosilicate glass (PSG) provides many possibilities for novel device structures for sensors and actuators. This paper describes a plasma planarization technique that provides fully planarized PSG filled silicon trenches for sensor applications. The technique consists of planarizing the substrate using two photoresist layers and plasma etching-back. The lower resist layer is the AZ5214 image reversal resist, which is patterned and then thermally cured. The upper resist layer is a global HPR204 coating. The plasma etching-back is carried out using CHF₃/C₂F ₆ gas mixture with an O₂ addition. It is shown that by using the image reversal photoresist approach, fully planarized surface coating can be obtained without resorting to an additional mask. By adding 25 sccm (14%) O₂ into the 137 sccm CHF₃+18 sccm C₂F₆ gas mixture, the etch rates for the photoresist and PSG can be matched. Process optimization for the two layer resist coating and plasma etching is discussed     

Spatial Distribution of Atmospheric Boundary Layer SO2 in Monsoon Region of China based on OMI/OMPS

The monsoon has obvious influences on biological migration, cultural formation, regional architectural structure, and changes in meteorological elements, but lacks study on the impact of the PBL SO₂. In this paper, we make a study on the temporal and spatial distribution characteristics of the PBL SO₂ in Chinese monsoon region by OMI SO₂ from 2005 to 2014 and OMPS NMSO₂ from 2015 to 2017 in order to identify the influence of monsoon on PBL SO₂ in different regions. Four typical cities were selected to do correlation analysis, and HYSPLIT model was run for backward Trajectory simulation by the corresponding date of daily SO₂ columns are greater than the monthly average in January 2012. The results show that china’s PBL SO₂ is spatial heterogeneity; the change of winter and summer monsoon has obvious influence on the PBL SO₂, temperature and pressure are the main factors affecting the concentration of the PBL SO₂. Regional meteorological conditions have large differences in the dry and wet deposition, photochemical reaction and wind diffusion of SO₂; the winter airflow has a greater impact on the increase of the SO₂, internal discharge in the Sichuan Basin, and southwesterly airflow which comes from the Indian Peninsula and the Bay of Bengal has a significant effect on the increase of SO₂ in Chongqing. Yinchuan is affected by the airflow that comes from the Mongolian Plateau or the Tianshan Mountains; Tianjin and Hangzhou are influenced by airflow come from the North China Plain or the Mongolian Plateau.