SAPO-11分子筛合成条件对其结晶度与催化性能的影响

在水热条件下改变合成条件合成一系列SAPO-11分子筛,采用XRD对样品进行结晶度表征,并考察了合成条件对SAPO-11分子筛催化性能的影响.结果表明,合成条件对SAPO-11分子筛的结晶度和催化性能有很大影响.以二正丙胺(DPA)为模板剂,n(DPA)/n(Al2O3)=1.5,n(SiO2)/n(Al2O3)=0.2,晶化时间为24 h和晶化温度为170℃时,合成出的SAPO-11分子筛催化剂最有利于萘和甲醇的甲基化反应.初步探究其在萘和甲醇的甲基化反应中的失活原因.结果表明,催化剂失活的主要原因是在萘和甲醇的甲基化反应过程中生成大量的水,经高温水脱铝导致分子筛结构坍塌,从而导致分子筛失活.     

基于不同取代基的噻吩-三苯胺染料敏化剂的合成与光伏性能

本文合成了含3种不同取代基的噻吩-三苯胺染料敏化剂(H1,H2和H3),并将其应用于二氧化钛纳米晶染料敏化太阳能电池.系统地研究了3种染料的光物理、电化学和光伏性能.基于H1的染料敏化太阳能电池获得了9.10%的光电转换效率(Voc=0.72V,Jsc=18.03mAcm-2,FF=0.70).     

A Study of the Effect of Sintering Conditions of Mg0.95Ni0.05Ti3 on Its Physical and Dielectric Properties

Mg_0.95Ni_0.05TiO₃ ceramics were prepared by traditional solid-state route using sintering temperatures between 1300 and 1425 °C and holding time of 2–8 h. The sintered samples were characterized for their phase composition, micro-crystalline structure, unit–cell constant, and dielectric properties. A two-phase combination region was identified over the entire compositional range. The effect of sintering conditions was analyzed for various properties. Both permittivity (ε_r) and Q factor (Q_f) were sensitive to sintering temperatures and holding times, and the optimum performance was found at 1350 °C withholding time of 4 h. The temperature coefficient of resonant frequency (τ_f) in a range from −45.2 to −52 (ppm/°C) and unit–cell constant were not sensitive to both the sintering temperature and holding time. An optimized Q factor of 192,000 (GHz) related with a permittivity (ε_r) of 17.35 and a temperature coefficient (τ_f) of −47 (ppm/°C) was realized for the specimen sintered at 1350 °C withholding time of 4 h. For applications of 5G communication device (filter, antennas, etc.), Mg_0.95Ni_0.05TiO₃ is considered to be a suitable candidate for substrate materials.     

On the Testing of Vibration Performances of Road Vehicle Suspensions

Both a test rig and a method are presented for the indoor testing of vibration performances of road vehicle suspension systems. A suspension (corner) has been positioned on a rotating drum (2.6 m diameter) placed in the Laboratory for the Safety of Transport of the Politecnico di Milano. The suspension system is excited by means of cleats fixed to the working surface of the rotating drum. The forces and the moments acting at the suspension-chassis joints are measured in the frequency range 0–120 Hz. Five special six-axis load cells have been conceived, manufactured, calibrated and employed. Transient wheel motions have been recorded. The influence of the vehicle speed on the relevant vibration performance indexes has been assessed. An approach for the identification of the suspension damping characteristics is introduced. A full and accurate characterization of a vehicle suspension system has been performed.     

LaF_3表面修饰LiMn_2O_4的合成方法及电化学性能的研究(英文)

通过高温固相法制得尖晶石LiMn2O4,然后在通过简单易行的无水乙醇蒸干法包覆LaF3来修饰LiMn2O4。利用XRD,SEM来表征LaF3修饰的LiMn2O4的结构和形貌特征,并通过电化学测试研究LaF3修饰LiMn2O4的高温和常温下的电化学性能,另外结合电化学阻抗谱(EIS)和循环伏安(CV)考察表面修饰的锰酸锂的循环阻抗和循环可逆性。结果显示:经LaF3修饰过的LiMn2O4仍具有尖晶石结构,并且具有良好的电学性能。其中,以3wt%的修饰效果最好,常温循环100次和高温循环50次的循环保持率分别是91%和90%;而且,EIS和CV分别表明经LaF3修饰的LiMn2O4的电荷传递阻抗明显减小,其循环可逆性也明显提高。     

A method for member selection of cross-functional teams using the individual and collaborative performances

The member selection problem is an important aspect of the formation of cross-functional teams (CFTs). Selecting suitable members from a set of candidates will facilitate the successful task accomplishment. In the existing studies of member selection, the individual performance concerning a single candidate is mostly used, whereas the collaborative performance associating with a pair of candidates is overlooked. In this paper, as a solution to this problem, we propose a method for member selection of CFTs, where both the individual performance of candidates and the collaborative performance between candidates are considered. In order to select the desired members, firstly, a multi-objective 0–1 programming model is built using the individual and collaborative performances, which is an NP-hard problem. To solve the model, we develop an improved nondominated sorting genetic algorithm II (INSGA-II). Furthermore, a real example is employed to illustrate the suitability of the proposed method. Additionally, extensive computational experiments to compare INSGA-II with the nondominated sorting genetic algorithm II (NSGA-II) are conducted and much better performance of INSGA-II is observed.     

有机化学接枝-电化学沉积聚合制备CNTs/PANI纳米复合材料

通过有机化学合成法先在碳纳米管表面接枝上苯胺单体,然后在不锈钢电极表面在硫酸溶液中采用循环伏安法电化学沉积聚合制得碳纳米管/聚苯胺(CNTs/PANI)纳米复合材料.扫描电子显微镜和傅立叶变换红外光谱表征所得材料的微观结构和基团,循环伏安和恒流充放电测试用于考察所得CNTs/PANI纳米复合材料的电化学性能.所得结果与...     

Impacts of seed power on amplification performance in pulsed double-clad fiber amplifier

A pulsed master-oscillator fiber power amplifier system with near diffraction-limited output by use of China-made large-mode-area fiber and a （2 ＋ 1） × 1 multimode combiner is reported. The effect of the seed power on the amplification performance is found. For the seed power, there exists a range within which the pulsed fiber amplifier can operate safely and reliably at a certain pump power. With the seed average power of 70 mW, the amplification performances of the fiber amplifier are investigated.     

A data hiding approach for the self-security of iris recognition

Attacks to biometric data are the primary danger to the self-security of biometrics. To improve the iris feature template data security, a data hiding approach based on bit streams is proposed, in which an iris feature template is embedded into a face image. The proposed approach is applicable to present dominant techniques of iris recognition. With the low computation cost and the zero decoding-error-rate, this data hiding approach, embedding target biometrie data into other biometrie data for improving the security of target data in identity recognition, data storage and transmission, can deceive attackers more effectively. Furthermore, it does not degrade the iris recognition performances. Experimental results prove that the proposed approach can be used to protect iris feature templates and enhance the security of the iris recognition system itself.