An advanced framework for leakage risk assessment of hydrogen refueling stations using interval-valued spherical fuzzy sets (IV-SFS)

The extensive population growth calls for substantial studies on sustainable development in urban areas. Thus, it is vital for cities to be resilient to new situations and adequately manage the changes. Investing in renewable and green energy, including high-tech hydrogen infrastructure, is crucial for sustainable economic progress and for preserving environmental quality. However, implementing new technology needs an effective and efficient risk assessment investigation to minimize the risk to an acceptable level or ALARP (As low as reasonably practicable). The present study proposes an advanced decision-making framework to manage the risk of hydrogen refueling station leakage by adopting the Bow-tie analysis and Interval-Value Spherical Fuzzy Sets to properly deal with the subjectivity of the risk assessment process. The outcomes of the case study illustrate the causality of hydrogen refueling stations' undesired events and enhance the decision-maker's thoughts about risk management under uncertainty. According to the findings, jet fire is a more likely accident in the case of liquid hydrogen leakage. Furthermore, equipment failure has been recognized as the most likely cause of hydrogen leakage. Thus, in order to maintain the reliability of liquid hydrogen refueling stations, it is crucial that decision-makers develop a trustworthy safety management system that integrates a variety of risk mitigation measures including asset management strategies.     

Combining renewable sources towards negative carbon emission hydrogen

Multi-energy systems that combine different energy sources and carriers to improve the overall technical, economic, and environmental performance can boost the energy transition. In this paper we posit an innovative multi-energy system for green hydrogen production that achieves negative carbon emissions by combining bio-fuel membrane-integrated steam reforming and renewable electricity electrolysis. The system produces green hydrogen and carbon dioxide, both at high purity. We use thermo-chemical models to determine the system performance and optimal working parameters. Specifically, we focus on its ability to achieve negative carbon emissions.The results show that in optimal operating conditions the system can capture up to 14.1 g of CO₂ per MJ of stored hydrogen and achieves up to 70% storage efficiency. Therefore, we prove that a multi-energy system may reach the same efficiency of an average electrolyzer while implementing carbon capture. In the same optimal operating conditions the system converts 7.8 kg of biogas in 1 kg of hydrogen using 3.2 kg of oxygen coming from the production of 6.4 kg of hydrogen through the electrolyzer. With such ratios we estimate that the conversion of all the biogas produced in Europe with our system, could result in the installation of additional dedicated 800 GWp - 1280 GWp of photovoltaic power, or of 266 GWp - 532 GWp of wind power, without affecting the distribution grid and covering yearly the 45% of the worldwide hydrogen demand while removing from the atmosphere more than 2% of the European carbon dioxide emissions.     

A robust filtering algorithm based on the estimation of tracer visibility and stability for large scale particle image velocimetry

Image velocimetry for open channel is safe, efficient and environmentally friendly and large-scale particle image velocimetry (LSPIV) is one of the most adopted methods. Furthermore, robust LSPIV algorithms strongly rely on the error vector filtering strategy. However, previous works mainly conduct filtering by median filtering, main orientation filtering and maximum filtering, and these strategies are not stable enough due to the lack of taking both the visibility and stability of tracer particles into consideration. Meanwhile, statistical property like SNR (Signal-to-Noise Ratio) and peak cross-correlation are unable to estimate the tracer visibility. In order to improve the accuracy, we propose a robust and effective filtering strategy called PPSR (Peak-Peak-Sidelobe-Ratio) from the image matching perspective to ensure the visibility and stability of tracers. We conduct a serial of experiments on the public dataset Brenta and Tiber to prove the effectiveness of the proposed algorithm.     

基于双尺度柔性原型迁移网络的空间滚动轴承寿命阶段识别

针对变工况条件下样本分布差异较大、不同寿命阶段样本数量不均衡导致现有空间滚动轴承寿命阶段识别方法的寿命阶段识别精度较低问题,提出基于双尺度柔性原型迁移网络（Dual scale flexible prototype transfer network,DSFPTN）的空间滚动轴承寿命阶段识别方法。在所提出的DSFPTN中,构造双尺度柔性域感知模块并将其嵌入特征提取器来增强特征提取器对不同领域私有特征的探索能力,提高特征提取器对空间滚动轴承源域和目标域样本特征的学习能力;设计同域泛原型学习以防止跨域样本不加区分的特征学习和不正确聚类,增加两域异类样本的区分性;构建两域原型迁移机制来获得域不变原型,实现从源域原型到目标域原型的迁移;利用加载域不变原型后的双分类器对齐两域之间的分布并计算目标域待测样本与域不变原型之间相似度完成对空间滚动轴承目标域待测样本分类,该分类方式在不同寿命阶段样本数量不均衡条件下能提高对各寿命阶段样本的识别精度。地面模拟空间环境下空间滚动轴承寿命阶段识别实例验证所提出的基于DSFPTN的寿命阶段识别方法的有效性。总之,构建双尺度柔性域感知模块、同域泛原型、两域原型迁移机制和加载域不变原型的双分类器使得DSFPTN在样本分布差异较大以及不同寿命阶段样本数量不均衡条件下,仅利用空间滚动轴承源域的非均衡有标签样本就能对目标域待测样本进行较高精度的寿命阶段识别。     

入汇角为30°时交汇区水流结构试验研究

 通过水槽试验，应用声速多普勒测速仪（ADV），研究了入汇角为30°时，支流斜接主流交汇区及其附近的三维水流结构，获得了不同主支汇流比下的三维流场及其脉动特性。试验表明：在交汇区三维流场中，产生了回流分离区，其中并伴随环流结构，大大改变了单一明渠中的流速分布及脉动特性。在入汇口下游主流右侧（入汇口一侧）水流脉动强度在z/h＝0.2处易出现极大值，其形成机理还有待验证。     

Spark plasma sintering of (Ti0.9W0.1) C powders prepared by mechanical alloying

Nanocrystalline (Ti_0.9W_0.1)C powder with a diffraction crystallite size of about 10 nm was synthesized by mechanical alloying. The formation of (Ti_0.9W_0.1)C carbide was detected by XRD measurements and microscopic observation. The sintering of these powders by a spark plasma sintering (SPS) at different temperatures were also studied. The results show that the maximum hardness was obtained for more relative density materials, meanwhile, the grain size is large. The micro-hardness and the relative density of the powder milled for 10 h and sintered at 1200 °C for 5 min under 100 MPa reach, respectively, 2978 HV and 98.35%.     

Microstructure and Properties of SAE 2205 Stainless Steel After Salt Bath Nitrocarburizing at 450 °C

Nitrocarburizing of the type SAE 2205 duplex stainless steel was conducted at 450 °C, using a type of salt bath chemical surface treatment, and the microstructure and properties of the nitrided surface were systematically researched. Experimental results revealed that a modified layer transformed on the surface of samples with the thickness ranging from 3 to 28 μm changed with the treatment time. After 2205 duplex stainless steel was subjected to salt bath nitriding at 450 °C for time less than 8 h, the preexisting ferrite zone in the surface transformed into austenite by active nitrogen diffusion. The main phase of the nitrided layer was the expanded austenite. When the treatment time was extended to 16 h, the preexisting ferrite zone in the expanded austenite was decomposed and transformed partially into ε-nitride precipitate. When the treatment time extended to 40 h, the preexisting ferrite zone in the expanded austenite was transformed into ε-nitride and CrN precipitate. Further, a large amount of nitride precipitated from preexisting austenite zone. The nitrided layer depth thickness changed intensively with the increasing nitriding time. The growth of the nitride layer takes place mainly by nitrogen diffusion according to the expected parabolic rate law. The salt bath nitriding can effectively improve the surface hardness. The maximum values measured from the treated surface are observed to be approximately 1400 HV_0.1 after 8 h, which is about 3.5 times as hard as the untreated material (396 HV_0.1). Low-temperature nitriding can improve the erosion/corrosion resistance. After nitriding for 4 h, the sample has the best corrosion resistance.     

The Effect of Microstructural Evolution on Hardening Behavior of 2205 Stainless Steel in Long-Term Aging at 500 °C

The effect of microstructural evolution on hardening behavior of 2205 stainless steel in long-term aging at 500 °C was studied by optical microscope, scanning electron microscope, and transmission electron microscope. The results showed that the hardness of ferrite phase in matrix steadily increased with the aging time at the first stage of 4 months, presented a peak of hardness at about 5 months, and showed a downward trend for the aging time from 6 to 8 months, while the hardness of the austenitic phase remained constant. Analysis showed that the iron-rich α phase and the Cr-rich α′ phase generated by spinodal decomposition, Cr₂N precipitations, and Fe₂Mn (R-phase) were the main reasons for the generation of peak in hardness of ferrite phase. Further studies showed that some dislocation structure (changing with the aging time) in δ-ferrite of matrix is related to the microstructural evolution.     

Effects of Co Substitution for Ni on Microstructures and Electrochemical Properties of LaNi3.8 Hydrogen Storage Alloys

系统研究了Co替代Ni对LaNi3.8型LaNi3.8-xCox(x=0.0,0.2,0.4,0.6)贮氢合金组织结构和电化学性能的影响。研究表明,所有合金都由LaNi5、Ce5Co19和Pr5Co19相组成。随着Co含量的增加,3个相的相丰度发生变化,而且单胞体积也相应的增加,这使得合金的放氢平台压降低到镍氢电池需要的范围(0.01~0.1 MPa)。与LaNi3.8相比,含Co合金的循环性能得到改善。LaNi3.4Co0.4具有最大的放电容量,这一点与固态放氢量一致。LaNi3.6Co0.2倍率放电性能最好,具有最大的交换电流密度(Io)和最小的电荷转移电阻(Rct)。     

Bi3+掺杂蓝色荧光粉GdVO4:Tm3+的发光性能

采用共沉淀法制备了Bi3+掺杂的GdVO4:Tm3+荧光粉材料。采用X射线衍射仪(XRD)、扫描电镜(SEM)、荧光光谱仪(PL)对所得荧光粉的晶体结构,颗粒形貌以及发光特性进行了分析。结果表明:Bi3+的掺入不改变GdVO4相的晶体结构,所得的Gd0.99-xVO4:Tm0.013+,Bix3+荧光粉的相结构仍为四方锆型结构。荧光粉体的形貌呈现尺度较均匀的颗粒状,颗粒尺寸约为70 nm。Bi3+的掺入增强了Gd0.99-xVO4:Tm0.013+,Bix3+荧光粉的发光强度,当Bi3+/Tm3+为0.5时,发光强度在波长为476 nm处达到最大值,显示为明亮的篮光。