电力物联网D2D通信中模式预选的多播重传技术

针对电力物联网D2 D通信中的模式预选问题,提出多播重传机制.首先,通过分析D2 D传输的集中式和分布式2种重传方案的优势和不足,提出一种新的基于重传模式预选的D2 D多播重传方案.新方案通过簇头汇总D2 D多播ACK状态和簇内链路质量,避免了集中式方案中上行汇报信令开销太大的问题;同时,通过让簇头来决定重传方案后再上报基站的方式,避免了分布式重传方案中预留资源带来的资源浪费问题.簇头充分考虑D2 D链路差异,根据D2 D链路质量自适应地选择最优传输节点,可充分利用D2 D链路的多信道分集增益.理论分析和计算机仿真验证方案在信令开销和传输效率方面的有效性.     

氮气氛下直拉硅中氮含量的红外光谱测定

提出了利用直拉硅中与氮有关的特征红外吸收峰９６３、９９６、１０８１－１及１０２７ｃｍ－１确定直拉硅中氮含量的计算公式，并进行了多种样品实测。该法克服了只用９６３ｃｍ－１峰测定直拉硅中氮使结果偏低的弊病，方法相对偏差为５％～２０％     

Experimental investigation of liquid water in flow field of proton exchange membrane fuel cell by combining X-ray with EIS technologies

The flow field is a pivotal part to manage the transport of water and gas in proton exchange membrane fuel cell. However, the reported water measurement methods (e.g., X-ray and electrochemical impedance spectroscopy (EIS)) cannot give a comprehensive understanding water distribution in the flow field, resulting in challenges in optimizing the channel design and enhancing fuel cell performance. Therefore, we propose a water measurement method combining the X-ray radiography with EIS to investigate the effect of different operating conditions on the growth law and distribution of liquid water in parallel and serpentine flow fields. The attenuation coefficient of liquid water to X-ray is calibrated with constant tube-current and tube-voltage of X-ray generator. Besides, the parallel flow field with hydrophobic treatment is studied. The results show that the water accumulation of the parallel flow field is far more than the serpentine flow field, and the water content of the middle region is higher than that of other regions in the parallel flow field. Furthermore, operating conditions (cathode inlet gas flow rate, inlet gas humidity, and back pressure) have little effect on the liquid water content of the middle region in the parallel flow field. The polarization curve, EIS result, and X-ray radiography show that the performance and water drainage capacity of the hydrophobic parallel flow field are better than the normal one.

     

Robust Superhydrophobic Fabric for Durability,Self-Cleaning,and Oil/Water Separation via Thiol–Acrylate Polymerization

In recent years, highly efficient oil/water separation materials have brought much attention. It requests superhydrophobic surfaces with a rapid and facile separation process, excellent durability, and large-scale fabrication. Herein, a facile vapor-liquid sol-gel, and free radical polymerization reaction method to prepare the durable and robust superhydrophobic cotton fabric is proposed. Moreover, the fabric can be used for highly efficient and various oil/water separation. It is prepared via a simple two-step process, including a vapor-liquid sol-gel process to deposit with thiols particles, and then followed a free radical polymerization reaction to graft 2,2,3,4,4,4-hexafluorobutyl methacrylate. Scanning electron microscopy and Fourier transform infrared spectrometry prove that the rough structures are generated from the hydrolysis condensation reaction between tetraethyl orthosilicate and 3-mercaptopropyltriethoxysilane. As a result, the synthetic chemical composition provided by the natural fabric and silica nanoparticles synergistically construct a superhydrophobic surface with water contact angles and shedding angle of 158° and 9°, respectively. Additionally, the treated fabric exhibits excellent chemical resistance and self-cleaning ability. Remarkably, the fabric still retains superhydrophobic and excellent mechanical robustness after 30 cycles of various oil/water separation. In summary, the resultant fabrics with excellent chemical resistance, remarkable mechanical robustness, and versatile separation abilities have potential applications in various oil/water separations.     

High Efficiency Electrochemiluminescence for Copper(II) and Cadmium(II) Pyrazolate Polymers

Journal of Inorganic and Organometallic Polymers and Materials - Two new coordination polymers, namely, [Cu2(L)2(4,4′-bpy)]n (1) and [Cd(HL)Cl(1,10′-phen)]n (2)...     

蒽醌法合成过氧化氢催化剂的研究进展

过氧化氢（H₂O₂, 俗称双氧水）, 由于其强氧化性常用作漂白剂、消毒剂, 同时也作化工原料。目前工业上生产过氧化氢的主要方法为蒽醌法, 全球近99%的产品均通过蒽醌法制得。研究具有高活性、高选择性及经济性的催化剂是合成过氧化氢所面对的最具挑战性的课题, 同时也是工业催化领域的研究热点之一。主要针对蒽醌法制过氧化氢催化剂, 综述了各种活性组分、载体及助剂在蒽醌加氢催化剂中的研究进展, 并简单探讨了各种活性组分的优缺点, 概括了各种载体、助剂的作用, 以期对过氧化氢催化剂的合成制备提供一些有益的启示。     

氟硅酸钾滴定法测定粗制氟化钠中二氧化硅

采用硝酸-氢氟酸混合酸为消解溶剂,通过微波消解技术对粗制氟化钠进行快速消解,并用氟硅酸钾滴定法测定其二氧化硅含量。选择饱和氯化钾溶液替代固体氯化钾作为沉淀剂,考察了消解酸体系、饱和氯化钾溶液用量、沉淀温度、沉淀放置时间、共存元素干扰及指示剂选择等条件对测定结果的影响并进行优化。确定了最优测试条件：以8 mL硝酸+2 mL氢氟酸为消解溶剂,以8 mL饱和氯化钾溶液为沉淀剂,控制沉淀温度为20~25 ℃、沉淀放置时间为15 min,选择50 g/L氯化钾-50%乙醇溶液洗涤沉淀,采用溴麝香草酚蓝-酚红指示剂。该方法应用于回收粗制氟化钠中二氧化硅含量的测定可大幅度缩短分解试样的时间,有效降低检测成本,回收率为99.15%~100.63%,相对标准偏差（RSD,n=8）小于1%,与传统高温碱熔法测定结果相符,方法的准确度和精密度较好。     

CHARAC TERIZATION OF TiAl POWDER PRODUCED BY MECHANICAL ALLOYING

The microstructure,alloying reaction and sintering behavior of the powder produced by Mechanical Al-loying(MA)for 8 h from 64 wt.-% Ti powder and 36 wt.-% Al powder were studied by scanning electronmicroscopy,optical microscopy,X-ray diffractometry,differential scanning calorimetry(DSC)and dilatometry.The mechanically alloyed powder partictes are Ti-Al composite particles.Thus,titanium aluminides can formeasily in the powder through diffusion during heat treatment.It is shown that the sintering behavior of this pow-der,different from the behaviors of TiAl alloy powder and mixed powder of 64 wt.-% Ti powder and 36 wt.-%Al powder,changes from expansion at temperatures below 1000℃ to shrinkage at temperatures above 1000℃.Homogeneously alloyed TiAl material with a density over 96% of the theoretical density can be produced fromthe mechanically alloyed powder by compaction-sintering.