多光子纳米加工中激光扫描条件对金属微纳结构的影响

研究了飞秒激光多光子还原制备银微纳结构技术中激光扫描条件对金属微纳结构与形貌的影响。结果表明:增加激光扫描点间距d可获得较小线宽,延长曝光时间t使线条变宽,增加扫描次数N可使金属微纳结构表面银纳米粒子熔融凝固成较大尺寸颗粒及块状物。     

双馈式风力发电机减振系统的优化

发电机是风力发电机组的关键部件之一,必须保证其在正常工作状态下运转平稳且不发生共振。国内某双馈式风力发电机在运行过程中出现振动超标问题,理论计算及振动测试结果表明减振器与发电机不匹配。通过安装不同刚度性能的橡胶减振器,并进行相关的振动测试,找到适合该电机的减振器,为发电机选配合适的减振器提供参考。     

Dye-sensitized solar cells based on ZnO nanotetrapods

In this paper, we reviewed recent systematic studies of using ZnO nanotetrapods for photoanodes of dye-sensitized solar cells (DSSCs) in our group. First, the efficiency of power conversion was obtained by more than 3.27% by changes of conditions of dye loading and film thickness of ZnO nanotetrapod. Short-circuit photocurrent densities (Jsc) increased with the film thickness, Jsc would not be saturation even the film thickness was greater than 35 μm. The photoanode architecture had been charactered by good crystallinity, network forming ability, and limited electron-hopping interjunctions. Next, DSSCs with high efficiency was devised by infiltrating SnO2 nanoparticles into the ZnO nanotetrapods photoanodes. Due to material advantages of both constituents described as above, the composite photoanodes exhibited extremely large roughness factors (RFs), good charge collection, and tunable light scattering properties. By varying the composition of the composite photoanodes, we had achieved an efficiency of 6.31% by striking a balance between high efficiency of charge collection for SnO2 nanoparticles rich films and high light scattering ability for ZnO nanotetrapods rich films. An ultrathin layer of ZnO was found to form spontaneously on the SnO2 nanoparticles, which primarily was responsible for enhancing open-circuit photovoltage (Voc). We also identified that recombination in SnO2/ZnO composite films was mainly determined by ZnO shell condition on SnO2, whereas electron transport was greatly influenced by the morphologies and sizes of ZnO crystalline additives. Finally, we applied the composite photoanodes of SnO2 nanoparticles/ZnO nanotetrapods to flexible DSSCs by low temperature technique of "acetic acid gelation-mechanical press-ammonia activation." The efficiency has been achieved by 4.91% on ITO-coated polyethylenenaphtalate substrate. The formation of a thin ZnO shell on SnO2 nanoparticles, after ammonia activation, was also found to be critical to boosting Voc and to improving inter-particles contacts. Mechanical press, apart from enhancing film durability, also significantly improved charge collection. ZnO nanotetrapods had been demonstrated to be a better additive than ZnO particles for the improvement of charge collection in SnO2/ZnO composite photoanodes regardless of whether they were calcined.     

花状纳米结构ZnS:Cu的制备与光学性质研究

采用水热法合成了具有花状纳米结构的ZnS:Cu粉末.利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)和荧光光谱仪研究了在不同正硅酸四乙酯(TEOS)含量的条件下制备的样品的物相、形貌与光致发光(PL)性质.测试结果表明:制备的ZnS:Cu样品都具有立方相闪锌矿结构;由于TEOS分子...     

Highly Intensified Surface Enhanced Raman Scattering by Using Monolayer Graphene as the Nanospacer of Metal Film–Metal Nanoparticle Coupling System

It is widely accepted that surface enhanced Raman scattering (SERS) enhancement results from a combination of electromagnetic mechanisms (EM) and chemical mechanisms (CM). Recently, the nanoparticle‐film gap (NFG) system was studied due to its strong local enhancement field. However, there are still some technical limitations in establishing effective and simple ways for reliable and precise control of sub‐nanospacer. In addition, works on designing the nanospacer in NFG system for efficient interaction with target molecules for further improving SERS signals are rather limited. Here, a novel NFG system is proposed by introducing ultrathin monolayer graphene as well‐defined sub‐nanospacer between Ag NPs and Ag film (named G(graphene)‐NFG system). The new G–NFG system offers tremendous near‐field enhancement with one of the highest enhancement ratio of 1700 reported to date. These results show that the single‐layer graphene as a sub‐nanospacer renders the proposed G–NFG system with particularly strong EM enhancement (due to multiple couplings including the NP–NP couplings and NP‐film couplings) and additional CM enhancement in detecting some π‐conjugated molecules to function as a powerful tool in analytical science and the related fields.     

Chemical Processing of Nanostructured Cemented Carbide

Chemical processing is becoming a vital component in the economic development of advanced engineering materials. Our research group on chemical processing has been focussed on the development of process to produce nanophase cemented carbide. It is a much more direct route for making WC/Co than traditional processing methods, and offers the potential for lower cost production of novel materials with homogeneous nanophase microstructures and improved properties. This paper addresses the scientific and technical issues relating to the chemical processing of nanophase WC/Co composite powder and their sintering.     

Hydrothermal Synthesis of Nanostructural LaxBi2-xSeyTe3-y Powders

Nanostructural monophase LaxBi2-xSeyTe3-y alloy was synthesized with a hydrothermal route using BiCl3, LaCl3, selenium and tellurium powders as the precursors, NaOH and disodium ethylenediaminetetraacetiate （EDTA） as the additives. The hydrothermally synthesized powders have a petal-like morphology self-structured by the parallel side-by-side arrangement of the nano-scales. It is found that an alkaline additive is necessary for the synthesis of a monophase Bi2Te3 based alloy.     

Magneto-Optical Study of Diluted Magnetic Semiconductor Nanostructures Prepared by Pulsed Laser Deposition

The CdTe/Cd_1–x Mn _x Te quantum well structures have been grown by pulsed laser deposition. X-ray diffraction analysis demonstrates high structural quality of the deposited layers and nanostructures. In the magnetoabsorption spectra the large Zeeman splitting of exciton peak which is corresponded to the heavy-hole exciton transition in the CdTe quantum well layers is revealed. The Faraday rotation spectra of the superlattices is interpreted in framework of the exciton transition for the Cd_1–x Mn _x Te layers at a higher photon energy. Influence of different factors on behavior of the Zeeman splitting and the Faraday rotation in the studied nanostructures is discussed.     

A horizontal axis sail windmill for use in irrigation

This paper describes some basic considerations in the design and development of a horizontal axis windmill intended primarily for irrigation in small farms from shallow open wells. This windmill has six triangular sails sweeping a circle of 10 m diameter and is an adaptation from Greek sail windmills. For the construction of this windmill all efforts were made to use materials and parts readily available in the hardware market except for the gear boxes. The cost of material and the parts is Rs. 7,000/- excluding the cost of machining and fabrication. Preliminary performance tests have indicated a pumping rate of 6000–11000 litres/hr over a head of 6.85 m in wind speeds of 10–16 km/hr.     

无库式潮汐能发电设备发展及其轴承应用

介绍了潮汐能发电设备的结构形式和发展状况,主要讨论目前已经具备样机的海底风车式和贯流式潮汐能发电机组,研究了这2种形式的潮汐能发电设备中各部位的轴承应用条件,并讨论了适用于该工况的轴承结构形式。