∝型平坦展宽频谱可调全光时延线

根据全光网交换和高速时分复用技术对时延调节的需求,提出一种新的基于光纤非线性效应的∝型全光再生可调时延线。该时延线由小段高非线性光纤、色散补偿光纤、光纤光栅滤波器和光纤放大器等构成;利用自相位调制、小量群速度色散效应、以及光波分裂效应获得携带近似线性时延的平坦化展宽光谱,并在波长可调谐光纤光栅的配合下实现时延控制,同时具有对工作波长进行适当变换的功能。单皮秒脉冲演变数值分析显示其在10nm的波长范围内的调节量可达300ps以上,在40Gbps脉冲序列仿真传输实验中Q值可达23.6。仿真实验结果表明:设计的时延线在保证输出脉冲质量仍然良好(比特误差率(BER)10-12)的情况下获得了较大的时延调节量,能满足全光网和高速时分复用系统的需求。     

豆油和丙氨酸对利福霉素SV生物合成的影响

研究了在250 mL摇瓶发酵过程中添加豆油和丙氨酸对利福霉素SV生物合成的影响。72 h分别向培养基中添加3 mL/L豆油和0.8 g/L丙氨酸,发酵液中利福霉素SV的效价分别比对照提高5.3%和6.9%。通过响应面分析法优化考察了豆油和丙氨酸对利福霉素SV合成的交互作用,确定在72 h添加0.89 g/L的丙氨酸和2.57 mL/L豆油时,摇瓶发酵单位是5 179 U/mL,比对照提高12.3%。有机酸分析结果显示,发酵培养72～120h,添加组的α-酮戊二酸和柠檬酸的利用速率分别是0.86 mg/(L.h)和0.77 mg/(L.h),分别比对照提高了115.7%和23.3%;同时,琥珀酸浓度上升到1.01 g/L,添加组比对照提高了16.1%。说明添加豆油和丙氨酸后,TCA循环由柠檬酸、α-酮戊二酸到琥珀酸转化效率提高,从而促进了琥珀酰CoA和甲基丙二酰CoA的合成,有利于利福霉素SV的合成。     

锂离子电池用Na-Mn-O材料的合成及应用

Na-Mn-O材料可作为离子交换法制备层状LiMnO2的前体,同时也可以直接作为锂离子电池的正极材料,被认为是锂二次电池研究中很有前景的新型材料。本文重点介绍了Na-Mn-O材料的晶体结构、制备方法,以及以该材料为前体,通过离子交换法合成的LixMnO2正极材料的结构与电化学性能。同时讨论了Na-Mn-O材料在锂二次电池、钠离子电池以及其它一些方面的应用,分析了Na-Mn-O材料作为未来锂二次电池正极材料的发展趋势。     

The preparation and performance of calcium carbide-derived carbon/polyaniline composite electrode material for supercapacitors

Calcium carbide (CaC₂)-derived carbon (CCDC)/polyaniline (PANI) composite materials are prepared by in situ chemical oxidation polymerization of an aniline solution containing well-dispersed CCDC. The structure and morphology of CCDC/PANI composite are characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM) and N₂ sorption isotherms. It has been found that PANI was uniformly deposited on the surface and the inner pores of CCDC. The supercapacitive behaviors of the CCDC/PANI composite materials are investigated with cyclic voltammetry (CV), galvanostatic charge/discharge and cycle life measurements. The results show that the CCDC/PANI composite electrodes have higher specific capacitances than the as grown CCDC electrodes and higher stability than the conducting polymers. The capacitance of CCDC/PANI composite electrode is as high as 713.4 F g⁻¹ measured by cyclic voltammetry at 1 mV s⁻¹. Besides, the capacitance retention of coin supercapacitor remained 80.1% after 1000 cycles.     

An application of fuzzy sets to the Geological Strength Index (GSI) system used in rock engineering

Characterization of rock masses is one of the fundamental aspects of rock engineering. Particularly, as a rock mass characteristic, determination of the strength of closely jointed rock masses is difficult since the size of representative specimens including discontinuities is too large for laboratory testing. This difficulty can be overcome by using the Hoek–Brown empirical failure criterion in conjunction with the Geological Strength Index (GSI) Classification System. However, characterization of rock masses and determination of their strength may involve some uncertainties due to their complex nature. The fuzzy set theory is one of the tools to handle such uncertainties. This paper describes the application of fuzzy set theory to the GSI System by incorporating judgement and experience of practising engineers. For the purpose, the original GSI System and its modified form were defined by fuzzy sets, and Mamdani fuzzy algorithm was constructed using 22 “if–then” rules for evaluating discontinuity parameters and their ratings considered in the GSI System. In addition, slope instabilities in heavily jointed rock masses selected from two open pit mines in Turkey were back analysed and the results were evaluated to demonstrate and to check the performance of this approach.     

Three-dimensional orthotropic equivalent modelling method of large-scale circular jointed lining

Due to the large spatial scale differences between the structure details and the global tunnel, the large-scale shield tunnels were usually modeled as continuous ‘pipes’ in the 3-D numerical analyses. The details (e.g. joints) that greatly affect the integral stiffness of the continuous 3-D tunnel models have seldom been discussed in literatures. This paper presents an idea of orthotropic equivalence for the modeling of the large-scale circular shield tunnel and the optimization procedure for the identification of the nominal material constants. Considering the tunnel’s structural characteristic in its radial, circumferential and axial directions and its periodicity, the segmentally erected lining is equivalently modeled as an orthotropic continuous structure. An optimization procedure based on the idea of inverse analysis and FE method which can quickly identify the equivalent constants is also proposed. Validation example shows that a reasonable consistency between results predicted by the equivalent/segmental models and the analytical formulas is achieved.     

Investigation of the state of innovation in the Gulf Cooperation Council countries: Looking ahead

The Gulf Cooperation Council (GCC) countries are concerned with activating knowledge and innovation as a source of development that reduces their dependence on oil. This paper is concerned with investigating the state of innovation in the GCC countries for the purpose of enabling the development of future plans that promote innovation and enhance development. It starts with an introduction on the importance of innovation for development; followed by presenting the approach used in the investigation. The approach views innovation from the wide scope of the “Global Innovation Index 2014 (GII 2014)”; and in the context of the knowledge culture associated with the human behavior toward knowledge. It considers two regional powers Turkey and Iran for comparison. The application of the approach is then described; followed by looking ahead toward innovation promotion. The paper identifies problems that require attention; and it concludes recommendations that emphasize innovation as an essential human source for future development.     

A novel electrospun TPU/PVdF porous fibrous polymer electrolyte for lithium ion batteries

Novel blend-based gel polymer electrolyte (GPE) films of thermoplastic polyurethane (TPU) and poly(vinylidene fluoride) (PVdF) (denoted as TPU/PVdF) have been prepared by electrospinning. The electrospun thermoplastic polyurethane-co-poly (vinylidene fluoride) membranes were activated with a 1M solution of LiClO₄ in EC/PC and showed a high ionic conductivity about 1.6 mS cm⁻¹ at room temperature. The electrochemical stability is at 5.0 V versus Li⁺/Li, making them suitable for practical applications in lithium cells. Cycling tests of Li/GPE/LiFePO4 cells showed the suitability of the electrospun membranes made of TPU/PVdF (80/20, w/w) for applications in lithium rechargeable batteries. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

一种大直径反井钻杆接头螺纹参数的优化研究

采用有限元分析和正交试验相结合的方法对反井钻井用大直径钻杆的接头螺纹参数进行了优化研究。研究结果表明,外螺纹小端大径、锥度、牙侧角和锥部长度等参数对接头螺纹强度有显著影响,得到了各参数作用的主次顺序和不考虑交互作用条件下各参数的最优值。