Preparation of iron and nitrogen co-doped carbon material Fe/N-CCM-T for oxygen reduction reaction

In this paper, iron and nitrogen co-doped carbon material with nanotube structure (Fe/N-C_CM-T) was synthesized by pyrolyzing a mixture of Fe salt, chitosan and melamine and displayed high electrocatalytic performance for oxygen reduction reaction (ORR). The structure of the Fe/N-C_CM-T was characterized and their ORR performance in alkaline media was investigated by linear sweep voltammetry, cyclic voltammetry and chronoamperometry. Fe/N-C_CM-T displayed better ORR performance than other carbon materials like Fe/N-C_C-800. The Fe/N-C_CM-800 with a large surface area (302.5 m²/g) especially exhibited the best ORR electrocatalytic performance among the prepared carbon materials, which was also proved by its similar Tafel slope (76 mV decade^?1) to Pt/C catalyst (74 mV decade^?1). Fe/N-C_CM-800 showed similar ORR activity as commercial Pt/C catalyst, but superior tolerance to methanol and stability. Such high ORR performance of the Fe/N-C_CM-T can be attributed to its nanotube structure, high specific surface area (SSA), high graphitic-N and pyridinic-N contents.     

计及损耗的双馈感应风力发电机高电压穿越控制策略

利用换向原理分析其电磁暂态特性，在此基础上，对DFIG输出无功功率与其铜损耗的解析关系进行了理论分析，推导出了使铜损耗最低的DFIG输出无功功率最优参考值。同时，转子的瞬时功率补偿分量减小了DC总线电压的波动，从而减少了转换器的功率损耗。由此，提出了考虑DFIG铜损和转换器损耗的DFIG高电压穿越控制策略。仿真结果表明，该控制策略可以在保证DFIG高电压穿越能力的同时降低DFIG铜损耗与换流器损耗，并具有较好的暂态特性。     

Enthalpies of formation of selected Pd2YZ Heusler compounds

Standard enthalpies of formation of selected ternary Pd-based Heusler type compositions Pd₂YZ (Y = Cu, Hf, Mn, Ti, Zr; Z = Al, Ga, In, Ge, Sn) were measured using high temperature direct synthesis calorimetry. The measured enthalpies of formation (in kJ/mole of atoms) of the Heusler compounds are, Pd₂HfAl (−81.6 ± 2.4); Pd₂HfGa (−79.9 ± 2.9); Pd₂HfIn (−76.4 ± 1.4); Pd₂HfSn (−77.6 ± 1.6); Pd₂MnSn (−54.6 ± 3.1); Pd₂TiGa (−65.6 ± 3.6); Pd₂TiIn (−69.9 ± 2.1); Pd₂TiSn (−78.6 ± 2.4); Pd₂ZrAl (−85.3 ± 3.0); Pd₂ZrGa (−76.2 ± 1.9); Pd₂ZrIn (−85.1 ± 3.9); Pd₂ZrSn (−92.2 ± 3.1); for the B2 compounds, Pd₂MnAl (−87.1 ± 3.0); Pd₂MnGa (−54.5 ± 1.7); Pd₂MnIn (−41.0 ± 2.5); Pd₂TiAl (−81.4 ± 1.9); for the tetragonal compound Pd₂CuAl (−55.2 ± 3.0) and for the orthorhombic compound Pd₂CuSn (−43.1 ± 2.3). Values were compared with those from published first principles calculation and the Open Quantum Materials Database (OQMD). Lattice parameters of these compounds were determined by X-ray diffraction analysis (XRD). Microstructures were identified using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Selected alloys were annealed at various temperatures to investigate phase transformations and phase relationships.     

Efficient utilization of waste heat from molten carbonate fuel cell in parabolic trough power plant for electricity and hydrogen coproduction

Direct steam generating parabolic trough power plant is an important technology to match future electric energy demand. One of the problems related to its emergence is energy storage. Solar-to-hydrogen is a promising technology for solar energy storage. Electrolysis is among the most processes of hydrogen production recently investigated. High temperature steam electrolysis is a clean process to efficiently produce hydrogen. In this paper, steam electrolysis process using solar energy is used to produce hydrogen. A heat recovery steam generator generates high temperature steam thanks to the molten carbonate fuel cell's waste heat. The analytical study investigates the energy efficiency of solar power plant, molten carbonate fuel cell and electrolyser. The impact of waste heat utilization on electricity and hydrogen generation is analysed. The results of calculations done with MATLAB software show that fuel cell produces 7.73 MWth of thermal energy at design conditions. 73.37 tonnes of hydrogen and 14.26 GWh of electricity are yearly produced. The annual energy efficiency of electrolyser is 70% while the annual mean electric efficiency of solar power plant is 18.30%.The proposed configuration based on the yearly electricity production and hydrogen generation has presented a good performance.     

小波变换在数字埋入云纹技术中的应用

埋入云纹技术可以用于三维力学问题的全场测量,对接触问题和物体内部力学场的测量具有很大的优势。将小波变换引入到数字埋入云纹技术中,可以方便快捷地消除条纹图中的噪声,模拟出清晰光滑的条纹图。介绍了应用小波变换生成云纹条纹的原理,并且进行了实验测试,结果表明该方法是可行的。     

多壁碳纳米管催化剂合成环氧化端羟基聚丁二烯

采用超声法将甲基三辛基氯化铵(A336)接枝在羟基多壁碳纳米管(MWCNT)表面,制备了A336/MWCNT催化剂。用傅里叶红外光谱(FTIR)和热重分析仪(TGA)表征了其结构。研究了其催化端羟基聚丁二烯(HTPB)合成环氧化端羟基聚丁二烯(EHTPB)的反应性能。结果表明,A336成功通过氨基与羰基的配位作用接枝在MWCNT表面,A336/MWCNT催化活性好、稳定性高、区域选择性强。催化反应4h时,HTPB环化度达25%,催化剂循环利用三次,HTPB环化度无明显下降,HTPB中反式1,4—CC的反应选择性较A336催化剂提高14.4%。     

基于不同电机极对数对开关磁阻电机性能的影响研究

针对电机本体结构的改变可能会引起的电机性能的变化,采取实验研究法对两种额定参数相同的四相8/6极和四相16/12极相同功率不同结构的开关磁阻电机(SRM)进行实验研究。对两种不同极数结构SRM的绕组自感、互感、转矩大小及脉动影响和绕组电流等方面进行了电磁仿真分析。结果表明:8/6极开关磁阻电机与16/12极相比,前者具有各相绕组自感值大、互感值大、转矩大等优点,后者具有转矩脉动小的优点。此项研究对SRM电机本体设计和SRM的选型具有重要的指导意义。     

络合法去除油田硫酸钡的研究与应用

以二乙烯三胺五乙酸（DTPA）为螯合剂主剂,配以氢氧化钾中和至pH值为13,并添加一定量的无机盐,对重晶石粉末进行溶出研究。结果表明,在DTPA质量分数一定的情况下,由于溶液黏度影响,钾盐的助溶效果为钠盐的2倍;随着无机盐质量分数的增加,碳酸钾、氟化钾和氯化钾对重晶石的助溶效果相应增加,碳酸钾添加量为10%时,溶出率达到最高的47.79%;反应4 h时,由于重晶石结块导致反应面积增大,碳酸钾的助溶效果比氟化钾高10.56%;反应12 h时,反应趋于完全,由于盐效应影响反应终点,氟化钾的助溶效果比碳酸钾高12.39%;对DTPABa3-离子进行了计算机模拟,得到了其稳定构象,并分析了钡离子络合常数低的原因;最终将该螯合剂应用于某堵塞油井,并对返排液中的无机盐组分、硫酸盐沉淀组分进行了XRD分析,并在沉淀中检测出钡元素,证明油井解堵成功,应用良好。      

微乳助排剂的研制及性能评价

采用两性表面活性剂、双子表面活性剂和非离子表面活性剂作为主剂、添加助剂及油相,复配得到了具有低表面张力和低界面张力的微乳液,并对其粒径、热稳定性、改善水润湿性能力、与压裂液配伍性及返排提高率进行评价,得到了具有优异助排效果的微乳液体系。结果表明:该体系粒径分布约80nm,其表面张力平衡值约26.0mN/m,与煤油间界面张力最低可降至0.1mN/m,可改善云母表面润湿性,与其接触角最高改善约70°,返排提高率最高达到了29.72%;微乳液具有一定的耐温性,且与压裂液、添加剂和破胶液配伍性良好。     

A chiral mononuclear DyIII complex with field-induced single molecule magnet behavior

A chiral mononuclear Dy^III complex, formulated [Dy(PNO)₆(H₂O)₂]Cl₃ (1) (PNO = pyridine-N-oxide), has been prepared by using an achiral ligand through spontaneous resolution. Structure analyses show that complex 1 consists of a Dy^III mononuclear unit and such units interact with each other by hydrogen bonds to form helical chains along a axis. The crystals of 1 are optically active and opposite Cotton effects can be observed in the circular dichroism (CD) spectra. Magnetic studies reveal that complex 1 exhibits field-induced single molecule magnet behavior with an energy barrier of 49 K.