Effects of thin film processing on pentacene/C60 bilayer solar cell performance

Solar cells based on pentacene/C₆₀ bilayer heterojunctions have been fabricated with a structure of ITO/poly(styrenesulfonate) (PEDOT:PSS)/pentacene (40 nm)/fullerene (C₆₀)(40 nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) (10 nm)/Al. The effect of pentacene crystalline domain size on performance was investigated by controlling the pentacene deposition rate. The devices show improved light-to-electricity conversion efficiencies from 0.49% to 1.12% under an AM 1.5 solar simulator (100 mW/cm²), when the pentacene evaporation rate is in a range of 5 Å/s–0.5 Å/s. Atomic force microscopy (AFM) measurements show that the pentacene films deposited by a slow evaporation rate have larger crystalline domains and a fewer amorphous domains, compared to films obtained by faster evaporation rates. Upon thermal annealing at 200 °C for 1 min, there is merging of pentacene crystalline domains. These changes in film morphology impact the charge separation at the donor/acceptor interface and the hole and electron mobilities, and hence, directly affect the device performance.     

Investigation of the behavior of a mode-I crack in functionally graded materials by non-local theory

In this paper, the behavior of a mode-I crack in functionally graded materials is investigated by means of the non-local theory. The traditional concepts of the non-local theory are firstly extended to solve the mode-I crack fracture problem in functionally graded materials, in which the shear modulus varies exponentially with coordinate parallel to the crack. Through the Fourier transform, the problem can be solved with the help of two pairs of dual integral equations, in which the unknown variables are jumps of displacements across crack surfaces, not the dislocation density functions or the analysis functions. To solve the dual integral equations, the jumps of displacements across crack surfaces are directly expanded in a series of Jacobi polynomials. Unlike the classical elasticity solutions, it is found that no stress singularity is present near crack tips. The non-local elastic solutions yield a finite stress at crack tips, thus allowing us to use the maximum stress as a fracture criterion. Numerical examples are provided to show the effects of the crack length, the parameter describing functionally graded materials, the lattice parameter of materials and the material constants upon the stress fields near crack tips.     

Microwave-assisted synthesis of barium tungstate nanosheets and nanobelts by using polymer PVP micelle as templates

Single-crystal BaWO₄ nanosheets and nanobelts have been successfully synthesized by using polymer PVP micelle as templates in a reflux system under microwave irradiation. Our result shows that the concentration of PVP aqueous solutions played an important role in the formation of BaWO₄ crystal with different morphologies. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and electron diffraction (ED).     

Combining color and spatial information for object recognition across illumination changes

One of the most widely used approaches in the context of object recognition across illumination changes consists in comparing the images by means of the intersection between invariant histograms. However, this approach does not provide satisfying results with limited image databases. We propose to cope with the problem of illumination changes by analyzing simultaneously the color components of the pixels and their spatial arrangement in the image. For this purpose, we introduce the chromatic co-occurrence matrices to characterize the relationship between the color component levels of neighboring pixels. In order to compare two images acquired under different illuminations, these matrices are transformed into adapted co-occurrence matrices that are determined so that their intersection is higher when the two images contain the same object lit with different illuminations than when they contain different objects.     

黑河水源调配中的Conflict解析法

跨际河流水源在多主体间调配的Conflict问题的协调与消除始终是关系资源合理利用、保护生态平衡的重要课题,以META—game理论为基础的Conflict数理解析方法,研究分析黑河流域水源调配中利益冲突的主体以及水源调配所涉及Conflict问题,利用META-game理论的Conflict数理解析方法,建立典型模型,然后通过模型,借助Conflict数理分析手段,对问题进行安定分析,寻求问题的答案——均衡解。最终提出Conflict问题消除的、能被矛盾各方接受的推荐方案,供决策部门选择。     

择优蚀坑表征立方晶系冷轧电工硅钢取向性

为确定电工硅钢的晶粒取向性,应用蚀坑技术研究了冷轧无取向硅钢、取向硅钢因择优腐蚀所形成的蚀坑与晶粒取向的关系,分析了{100}面系蚀坑形貌的演变过程,从晶体学角度建立了蚀坑形貌与晶面指数的对应关系.结果发现:无取向硅钢形成不同形貌的蚀坑,其晶面指数为(001)、(011)和(111),或是由它们演变形成的其他晶面指数;取向硅钢形成的蚀坑为同一类型,晶面指数为(011)或由其演变形成的其他晶面指数;晶界也会形成蚀坑,其形貌与相邻晶粒间的取向差有关,取向差大,形成{100}、{110}和{111}面系的蚀坑,取向差小,形成{110}面系的蚀坑.取向硅钢的蚀坑分布具有连续性,晶界的存在并不改变蚀坑的基本特征;取向硅钢蚀坑的底棱相互平行,相差不超过5°,底棱延伸方向与硅钢的轧制方向即[001]方向一致,偏离角度不超过5°.     

水产养殖产品精制加工与质量安全发展战略研究

本文基于对我国养殖水产品精制加工和质量安全现状、存在问题的客观分析,提出了"构建以加工引导养殖、保障消费的现代水产业发展新模式,促进养殖、加工与物流业同步发展""完善科研经费投入体制,构建以加工引导养殖、以加工保障消费的渔业科技创新体系""强化源头创新,研发关键配套技术,解决水产加工产业发展的瓶颈问题"及"加强顶层设计,增强政策、法律法规与科研项目引导,切实保障养殖水产品质量安全"等促进水产品加工业健康发展的建议,并提出了发展我国水产品加工产业的关键技术,为推动我国水产业转型升级、实现现代化提供理论支撑。     

水产养殖动物营养与饲料工程发展战略研究

本文综述了我国水产养殖动物营养学研究和饲料工程方面近期的研究,分析了产业发展的问题,探讨了下一步的政策措施。可以发现,过去10多年里,水产动物营养与饲料的发展在营养素需求、动物的摄食与投喂、仔稚鱼饲料、亲本营养、添加剂等方面取得了重要的进展,但仍然存在饵料系数高、环境排放大、饲料成本高、效益不稳定等问题。下一步的研究应该以"安全高效,节约环保"为目标,引入生态学和现代组学理念,开展水产动物营养代谢的分子机理、动物的营养需要与精准饲料配方技术、饲料质量控制与加工工艺、精准投喂技术、品质调控技术等方面的研究,同时在政策上应该扩大学科交流、实行长期稳定支持等。     

“一带一路”战略背景下的北极航线开发利用

为了研究北极冰融加速环境下我国开展北极航线商业通航的价值意义,本文通过对传统航线与北极航线的成本效益比较分析,运用制度分析法考察了北极航线利用所面临的严峻挑战。提出北极航线开发利用应当纳入"一带一路"战略规划之中,北极航线可以成为延伸丝绸之路经济带的海上通道、21世纪海上丝绸之路的拓展航线、对外经贸网络不可或缺的组成部分,"一带一路"战略不应忽视开发利用北极航线的战略价值。     

超声波振动仪器在采用沉降法进行粘性泥沙粒径分析中的应用

本文提出在粘性泥沙粒径颗粒分析中使用超声波振动仪器进行细颗粒泥沙分散的方法,使用基于沉降法原理的TZC-4粒度分析仪,采用三种不同的颗粒粒径测量工艺分别对乐清湾港区、阳澄湖、奉贤边滩、上海闵行河道四种不同的泥样进行了颗粒粒径分析,并与现有规范规定的测量工艺所得结果进行了对比。实验分析表明,该方法能够有效地测量泥沙的基本粒径,泥沙颗粒越细,该方法的优越性越为突出。