2017, 6(1):1-7. DOI: 10.12146/j.issn.2095-3135.201701001
Abstract:The modification such as introducing charge is an effective means to make the graphene applicable in the field of electronic devices. In this paper, the first-principle calculation was performed to investigate the electronic and phononic band structures as well as the electron-phonon interaction in a monolayer graphene doped by small number of electrons or holes. It was found that, the charged graphene exhibits metallic character due to the shift of Fermi level. The introducing charge did not affect the variation of bending in graphene since the z-axis acoustic mode was unchanged. The abnormal softened phonon mode was observed for electron-doped graphene. The electron-phonon coupling was constantly enhanced with the increasing of charge concentration. It was concluded that, the carrier mobility in graphene can be improved since the doping adjusts the longitudinal optical phonon frequency and results in a stronger electron-phonon interaction.
2017, 6(1):8-15. DOI: 10.12146/j.issn.2095-3135.201701002
Abstract:A vision-based fingertip interactive projector-camera system was presented in this paper. The proposed method can detect touch operations by judging the fusion level of fingertip and its shadow. To improve the robustness of the proposed method, in image detection stage, finger and its shadow are extracted and segmented from the image separately. And then, a linear detection model was introduced to judge the fusing level of fingertip and its shadow in the image. While a touching event was detected, the touching location can be calculated from the extracted fingertip image coordinate. With the proposed method, users can realize finger-based operation on the projector screen without any accessory tools.
2017, 6(1):16-23. DOI: 10.12146/j.issn.2095-3135.201701003
Abstract:A flexible paper fiber-reduced graphene oxide-polyaniline hybrid electrode was investigated in this article. Using low-cost paper fiber as flexible substrate, the electrode was prepared through ultrasonic dispersion and vacuum filtration. It combined the advantages of graphene oxide electric double layer with polyaniline conductive polymer pseudo-capacitance. The obtained electrode was characterized and tested by various instrumentations such as scanning electron microscope, cyclic voltammetry and galvanostatic chargedischarge. In the bending test experiments, the obtained electrode was not separated into individual layers after hundreds of bending cycles. The flexible paper fiber-reduced graphene oxide-polyaniline hybrid electrode also exhibits excellent capacitance (458 F/g at a discharge current density of 1 A/g and 250 F/g at a discharge current density of 10 A/g) and remarkable cycling stability with capacitance degradation about 20% after 1 000 charge-discharge cycles at a current density of 3 A/g. The proposed flexible electrode has great potentials in the development of flexible energy-storage devices for wearable electronic products.
2017, 6(1):24-38. DOI: 10.12146/j.issn.2095-3135.201701004
Abstract:Diamond coated hard metal is an outstanding cutting material for manufacturing. By adding SiC to the diamond coating material, not only the surface toughness but also the film adhesive strength can be improved. Diamond/β-SiC/cobalt silicide composite films were deposited on Co-cemented tungsten carbide (WC-Co) substrates by direct current plasma assisted hot filament chemical vapor deposition using a gas mixture of hydrogen, methane and tetramethylsilane. Scanning electron microscopy, electron probe microanalysis, X-ray diffraction and Raman scattering analyses were carried out to characterize the surface morphology, composition and structure of the deposited films. The results revealed that the composite films consist of diamond, β-SiC and cobalt silicides (Co2Si, CoSi). The structure and composition of the composite films can be controlled by adjusting bias current and tetramethylsilane concentration in the gas phase. With the increase of bias current, the grain size and content of diamond also increase, while the content of β-SiC decrease. Since bias current enhances the secondary nucleation and growth of diamond. Although the dissociation of hydrogen, methane and tetramethylsilane are all enhanced by electron bombardment during the biasing process, the concentration of produced C sources is much higher than that of Si sources with the increase of bias current. Then the growth of diamond becomes more competitive than that of β-SiC. The bias current cannot be too high to deposit the three substances of diamond, β-SiC and cobalt silicides. By adjusting bias and gas composition, the distribution of diamond and β-SiC in the composite films was manipulated. These results demonstrated the significance to understand and control the growth of composite materials and super hard thin films. Such composite films can be utilized to improve the cutting performance of diamond coated cutting tools.
2017, 6(1):39-52. DOI: 10.12146/j.issn.2095-3135.201701005
Abstract:It is of great value to rapidly and accurately detect garbage from urban images in the application of intelligent city management. Garbage images are highly diverse in color texture and geometry; moreover, garbage recognition can be a subject matter, which poses great challenges to automatic detection of garbage. In this paper, a garbage detection method based on faster region-based convolutional neural networks was proposed. It can detect garbage from urban images with high accuracy by integrating techniques such as data fusion, data augmentation, and transfer learning. We have built an image database containing various types of garbage based on photographs taken from urban scenes in the Shenzhen city, showing a detection accuracy of 89.07%.
2017, 6(1):53-60. DOI: 10.12146/j.issn.2095-3135.201701006
Abstract:The porous metal material is an ideal functional material with low density, high specific stiffness, and good energy absorption effect. It has been widely studied and used for various applications. In this paper, a new method to fabricate porous metal based on cubic cells was studied. In order to study the mechanical properties of this energy absorbing material, some samples are prepared for the actual quasi-static and dynamic impact tests. By analyzing the experimental results, feasibility of the method can be verified. This work may extend the range of porous metal materials, and provide foundations for further optimization of porous metals.
2017, 6(1):61-68. DOI: 10.12146/j.issn.2095-3135.201701007
Abstract:With the increasing consumption of traditional fossil energy, progress on the renewable energy attracts more and more attentions. Solar cells that convert the solar energy into electric energy, has been one of most important technology in the renewable energy domain. In this paper, an instrument which can continuously measure the electricity generation of several solar panels is developed and tested. Under different weather conditions, performance of several mainstream solar cells that available in the market was compared. The generated electricity by different solar panels was normalized to the area and nominal power. Based on the experimental results, performance and characteristic of different solar cells at different outdoor conditions are provided and analyzed.
2017, 6(1):69-81. DOI: 10.12146/j.issn.2095-3135.201701008
Abstract:Realistic fluid animation with computer graphics technology has great practical importance in various fields such as film and television special effects and advertising, 3D game development, and virtual reality. This paper reviews the techniques and trend of fluid animation in recent years, summarizing the research results into three categories: experience-based method, physical method and data-driven method, with a comprehensive comparison of their pros and cons. In particular, this paper documents the mainstream physical methods and the latest data-driven methods.
2017, 6(1):82-86. DOI: 10.12146/j.issn.2095-3135.201701009
Abstract:Plate heat exchanger (PHE) freshwater generators are wildly applied at ocean vessels for freshwater supply. In this paper, based on the thermodynamics principle of PHE, a distillation desalination device was designed and manufactured. Water production rate of the investigated PHE device was tested to obtain an optimized setting. The experimental results showed that, the heat source water temperature at inlet and flow rate are the two major factors that affect the freshwater generator performance. Basically, freshwater production rate is linearly with the increase of heat source water inlet temperature increases (60-74℃) and flow (2 000-3 900 kg/h). Feed water flow has an optimal value of about 150 kg/h, and the water production rate increases with the feed water flow below the optimal value. Feed water flow did not increase the rate of water production significantly while the feed water flow over the optimal value, and even led to the decrease of the water production rate. The obtained data can provide empirical reference for the design and optimization of PHE devices.