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51.
On the basis of the rational analysis about the fluidic property of the system, an ultralow gas flow chemical vapor deposition (CVD) strategy was designed to prepare large-scale horizontally aligned ultralong single-walled carbon nanotube (SWNT) arrays. SWNT arrays could be well obtained under extremely low feeding flow of 1.5 sccm in a 1 in. quartz tube reactor. It was confirmed that the tubes grew floatingly and could cross microtrenches or climb over micro-obstacles in ultraslow gas flow. SWNTs arrays also could be formed no matter the substrate was placed vertically or upside down. The growth mechanism was discussed. Both the buoyancy effect induced by gas temperature/density difference and gas flow stability played dominant roles. More attractively, simultaneous batch-scale preparation of SWNT arrays was realized by the ultralow gas flow strategy. This new strategy turns to be more abstemious, efficient, promising, and flexible compared with the high gas flow rate fast-heating CVD processes. 相似文献
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Yihui Sun Xiaoqin Yan Xin Zheng Yong Li Yichong Liu Yanwei Shen Yi Ding Yue Zhang 《Nano Research》2017,10(1):77-86
The carrier screening effect occurs commonly in dielectric materials. It reduces the electric potential gradient, thus negatively affecting the functionality of resistive random access memory (RRAM) devices. An Au/ZnO film/Al-doped ZnO device fabricated in this work exhibited no resistive switching (RS), which was attributed to the carrier screening effect. Therefore, annealing was used for alleviating the screening effect, significantly enhancing the RS property. In addition, different on/off ratios were obtained for various bias values, and the screening effect was accounted for by investigating electron transport mechanisms. Furthermore, different annealing temperatures were employed to modulate the free carrier concentration in ZnO films to alleviate the screening effect. The maximal on/off ratio reached 105 at an annealing temperature of 600 °C, yielding the lowest number of free carriers and the weakest screening effect in ZnO films. This work investigates the screening effect in RS devices. The screening effect not only modulates the characteristics of memory devices but also provides insight into the mechanism of RS in these devices. 相似文献
54.
Chen-Chau Chu Aggarwal J.K. 《IEEE transactions on pattern analysis and machine intelligence》1993,15(12):1241-1252
We present an algorithm that integrates multiple region segmentation maps and edge maps. It operates independently of image sources and specific region-segmentation or edge-detection techniques. User-specified weights and the arbitrary mixing of region/edge maps are allowed. The integration algorithm enables multiple edge detection/region segmentation modules to work in parallel as front ends. The solution procedure consists of three steps. A maximum likelihood estimator provides initial solutions to the positions of edge pixels from various inputs. An iterative procedure using only local information (without edge tracing) then minimizes the contour curvature. Finally, regions are merged to guarantee that each region is large and compact. The channel-resolution width controls the spatial scope of the initial estimation and contour smoothing to facilitate multiscale processing. Experimental results are demonstrated using data from different types of sensors and processing techniques. The results show an improvement over individual inputs and a strong resemblance to human-generated segmentation 相似文献
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Yadong Liu Qingjiang Ren Zisheng Su Bei Chu Wenlian Li Shuanghong Wu Fangming Jin Bo Zhao Xingwu Yan Junbo Wang Di Fan Feng Zhang 《Organic Electronics》2012,13(10):2156-2159
We demonstrate the working mechanism of organic photovoltaic (OPV) cell with copper phthalocyanine (CuPc) as exciton blocking layer (EBL). The new EBL material CuPc, commonly has been used as electron donor in the organic solar cells due to its electron-donating and hole-transporting properties. But here we proves that the α-polymorph CuPc layer can transfer electrons to Al cathode through the half-filled b1g level, this mechanism is different from that of general EBL material with larger band gap and electron-transporting property, which is based on damage states induced by the heat of evaporating Al. 相似文献
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Mao-Yuan Pai Hui-Chuan Chu Su-Chen Wang Yuh-Min Chen 《Expert systems with applications》2013,40(6):1993-2006
Since eWOM provides a rich source of objective information about products or services, it has become one of the major ways in which consumers collect information about items they are interested in buying. However, the problem of eWOM overload makes it difficult to effectively collect this information, and may have adverse effects on their actual purchase behavior. eWOM content is characterized by unstructured text formats, oversimplified expressions, and newly coined phrases (textspeak), and these all contribute to the challenges that arise when analyzing eWOM. This study thus proposes an eWOM analysis method for analyzing eWOM, which may lead to a more effective method for analyzing eWOM content, extracting both positive and negative appraisals, and help consumers in their decision making. At the same time, the method proposed in this study can also be utilized as a tool to assist companies in better understanding product or service appraisals, thus translating these opinions into business intelligence and as the basis for product/service improvements. 相似文献
60.
在应试教育的背景下,许多中学片面追求高考升学率,家长也对子女抱有很高的期望,这给高三学生带来了沉重的心理压力.此外,严峻的就业形势、不良的人际关系及非理性的自我期许,使这种压力处于过度状态.要想解决这种困境,教师和家长应帮助学生理性认识高考与就业的关系,理性评价学生,为他们创建良好的学习氛围,鼓励同学之间加大交流. 相似文献