几种基于特殊媒介的无线传输技术

随着科技的发展和应用需求的推动,基于特殊媒介的无线传输技术不断涌现。对国外几种典型的基于特殊媒介的无线传输技术的基本机理、主要特点及国外发展情况进行了介绍,其中海面蒸发波导通信可显著降低微波超枫五巨传播损耗;基于电离层加热的沿场散射通信能够显著改善HF／VHF／UHF超视距通信性能;水声通信是一种极有前途的对潜通信手段;中微子通信具有钻地入海的直线通信能力。各项技术利用其独特的信道特性提供了优于常规通信的传输性能,对未来通信发展具有重要意义。     

基于LabVIEW 8.0测定纯液体蒸发焓的虚拟仪器

将常规的数字温度仪与压力计通过串行口和计算机连接,构建基于LabVIEW 8.0测定纯液体蒸发焓的虚拟仪器,实现实验数据的动态采集、实时显示、自动绘制p～T曲线并显示曲线方程、自动数据处理和写成结果报告等。应用结果表明:基于LabVIEW构建的测定纯液体蒸发焓的虚拟仪器,免除人工操作的繁琐和人为误差,测定乙醇和苯蒸发焓的相对误差分别为0.86%、-2.97%,提高了测量结果的准确度,且具有界面友好,操作简便和功能易扩展等诸多优点。     

DCS控制系统在蒸发工段的应用

分析了碱回收蒸发工段的工艺流程和控制要求,从硬件配置和软件设计等方面对碱回收蒸发工段进行了详细的叙述,同时采取软测量的方法测量黑液浓度,提出黑液浓度-压力串级控制方法;根据工艺要求设计出一种新型的DCS控制方法,它是由西门子公司的SIMATIC 400系列PLC连接ET200系列的分布式I/O系统及标准伺服控制系统组成的DP控制网络,通过相应的智能仪表及阀门对现场信号进行采集和控制;由此对碱回收蒸发工段实施集散控制的优化控制法案;工程实践表明,该系统在江苏甲乙粘胶公司生产线上投用,各种控制性指标能够很好地满足公司的要求。     

PLC控制系统在碱回收蒸发工段的应用

针对碱回收蒸发工段的工艺特点和控制要求,设计了S7-300PLC控制系统。对黑液浓度采取软测量方法,提出了黑液浓度-压力串级控制策略;对温度控制对象采用了具有自整定功能的温度控制功能块FB58,并从硬件配置和软件设计等方面对系统进行详细论述。     

基于稀疏采样传播数据和决策树算法的蒸发波导反演

蒸发波导的超视距传播特性是影响海上无线电系统性能的重要因素,准确预测蒸发波导是进行系统 评估的基础。文中提出一种基于稀疏采样传播数据和决策树轻量梯度提升机(Light Gradient Boosting Machine, LightGBM)算法的蒸发波导反演方法。首先,采用抛物方程方法仿真得到稀疏采样传播数据并构建训练集和测试 集;其次,使用决策树LightGBM 算法搭建反演模型,通过不断调参改进模型的精度以达到较高的反演准确度;最后, 调用训练好的LightGBM 模型进行蒸发波导反演,并对反演结果的概率分布进行了分析。结果表明,基于稀疏采样 传播数据的蒸发波导反演方法能够有效且快速地实现蒸发波导反演,为海上蒸发波导预测提供了一种新途径。     

Solar-Driven Interfacial Evaporation Accelerated Electrocatalytic Water Splitting on 2D Perovskite Oxide/MXene Heterostructure

The rational design of economic and high-performance electrocatalytic water-splitting systems is of great significance for energy and environmental sustainability. Developing a sustainable energy conversion-assisted electrocatalytic process provides a promising novel approach to effectively boost its performance. Herein, a self-sustained water-splitting system originated from the heterostructure of perovskite oxide with 2D Ti₃C₂T_x MXene on Ni foam (La_1-xSr_xCoO₃/Ti₃C₂T_x MXene/Ni) that shows high activity for solar-powered water evaporation and simultaneous electrocatalytic water splitting is presented. The all-in-one interfacial electrocatalyst exhibits highly improved oxygen evolution reaction (OER) performance with a low overpotential of 279 mV at 10 mA cm⁻² and a small Tafel slope of 74.3 mV dec⁻¹, superior to previously reported perovskite oxide-based electrocatalysts. Density functional theory calculations reveal that the integration of La_0.9Sr_0.1CoO₃ with Ti₃C₂T_x MXene can lower the energy barrier for the electron transfer and decrease the OER overpotential, while COMSOL simulations unveil that interfacial solar evaporation could induce OH⁻ enrichment near the catalyst surfaces and enhance the convection flow above the catalysts to remove the generated gas, remarkably accelerating the kinetics of electrocatalytic water splitting.     

2D MoN1.2-rGO Stacked Heterostructures Enabled Water State Modification for Highly Efficient Interfacial Solar Evaporation

Improving interfacial solar evaporation performance is crucial for the practical application of this technology in solar-driven seawater desalination. Lowering evaporation enthalpy is one of the most promising and effective strategies to significantly improve solar evaporation rate. In this study, a new pathway to lower vaporization enthalpy by introducing heterogeneous interactions between hydrophilic hybrid materials and water molecules is developed. 2D MoN_1.2 nanosheets are synthesized and integrated with rGO nanosheets to form stacked MoN_1.2-rGO heterostructures with massive junction interfaces for interfacial solar evaporation. Molecular dynamics simulation confirms that atomic thick 2D MoN_1.2 and rGO in the MoN_1.2-rGO heterostructures simultaneously interact with water molecules, while the interactions are remarkably different. These heterogeneous interactions cause an imbalanced water state, which easily breaks the hydrogen bonds between water molecules, leading to dramatically lowered vaporization enthalpy and improved solar evaporation rate (2.6 kg m⁻² h⁻¹). This study provides a promising strategy for designing 2D-2D heterostructures to regulate evaporation enthalpy to improve solar evaporate rate for clean water production.     

脱硫废水旋转喷雾蒸发与旁路烟道蒸发特性研究

针对旋转喷雾和旁路烟道两类高温旁路烟气蒸发技术工艺,开展脱硫废水蒸发特性对比实验,结合可视化荧光示踪法及单液滴蒸发试验研究了废水雾滴在高温烟气中的蒸发过程,分析了烟气温度及烟气停留时间对蒸发性能的影响,并比较了两类废水蒸发工艺的差异。结果表明：脱硫废水液滴接触热烟气后将迅速失去表面自由水分,表面成壳固化为半干颗粒;旋转喷雾蒸发塔内主蒸发区域温度迅速降低,提高烟气温度有助于提升蒸发效率,降低出口灰分含水率;通过适当增大干燥塔尺寸,延长高温烟气在干燥塔内停留时间,可提升热量利用率,实现低气液比条件下的蒸发干燥;两类旁路蒸发工艺相比,旋转喷雾蒸发因雾化效果较好、气液混合均匀,蒸发性能略优于旁路烟道工艺。     

High throughput research and evaporation rate modeling for solvent screening for ethylcellulose barrier membranes in pharmaceutical applications

Context: Ethylcellulose is commonly dissolved in a solvent or formed into an aqueous dispersion and sprayed onto various dosage forms to form a barrier membrane to provide controlled release in pharmaceutical formulations. Due to the variety of solvents utilized in the pharmaceutical industry and the importance solvent can play on film formation and film strength it is critical to understand how solvent can influence these parameters.

Objective: To systematically study a variety of solvent blends and how these solvent blends influence ethylcellulose film formation, physical and mechanical film properties and solution properties such as clarity and viscosity.

Materials and methods: Using high throughput capabilities and evaporation rate modeling, thirty-one different solvent blends composed of ethanol, isopropanol, acetone, methanol, and/or water were formulated, analyzed for viscosity and clarity, and narrowed down to four solvent blends. Brookfield viscosity, film casting, mechanical film testing and water permeation were also completed.

Results and discussion: High throughput analysis identified isopropanol/water, ethanol, ethanol/water and methanol/acetone/water as solvent blends with unique clarity and viscosity values. Evaporation rate modeling further rank ordered these candidates from excellent to poor interaction with ethylcellulose. Isopropanol/water was identified as the most suitable solvent blend for ethylcellulose due to azeotrope formation during evaporation, which resulted in a solvent-rich phase allowing the ethylcellulose polymer chains to remain maximally extended during film formation. Consequently, the highest clarity and most ductile films were formed.

Conclusion: Employing high throughput capabilities paired with evaporation rate modeling allowed strong predictions between solvent interaction with ethylcellulose and mechanical film properties.     

一种新型低温容器综合性能检测仪设计及应用

针对低温容器性能检测实际需求,介绍了一种新型低温容器综合性能检测仪的设计计算方法及工艺流程,并从抽真空系统、测量分析系统、环境监测系统、控制系统及工艺流程方面重点阐述其设计方法,最后介绍了基于此设计完成的产品及实际应用情况。