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排序方式: 共有695条查询结果,搜索用时 15 毫秒
11.
Nabil Yassine Steve Barker Khaled Hayatleh Bhaskar Choubey Rajasekhar Nagulapalli 《Analog Integrated Circuits and Signal Processing》2018,95(3):409-414
This paper proposes a system to detect and measure blink rate to determine fatigue levels. The method involved analysing specific frames to determine that a blink occurred, and then monitoring the time between successive blinks. The program was simulated in python using a Raspberry Pi Zero and a standard USB camera. For the blink rate detection block, a gate level schematic was implemented in Cadence software using 65 nm CMOS technology. The design was based around an asynchronous 6-bit based edge counter which was designed using D-flip-flops. The simulation calculated the average blink rate and compared this to the most recent blink rate. The outcome would determine if an alarm signal should be sent to the alarm. The system consumed 130 μA from a 1.2 V power supply. 相似文献
12.
This paper presents a new method for copy-move forgery detection of duplicated objects. A bounding rectangle is drawn around the detected object to form a sub-image. Morphological operator is used to remove the unnecessary small objects. Highly accurate polar complex exponential transform moments are used as features for the detected objects. Euclidian distance and correlation coefficient between the feature vectors are calculated and used for searching the similar objects. A set of 20 forged images with duplicated objects is carefully selected from previously published works. Additional 80 non-forged images are edited by the authors and forged by duplicating different kinds of objects. Numerical simulation is performed where the results show that the proposed method successfully detect different kinds of duplicated objects. The proposed method is much faster than the previously existing methods. Also, it exhibits high robustness to various attacks such as additive white Gaussian noise, JPEG compression, rotation, and scaling. 相似文献
13.
Fahad A. Alharthi G. Nagaraju S P Vinay Udayabhanu Nabil Al-Zaqri Ali Alsalme 《国际能源研究杂志》2020,44(11):8362-8371
The photocatalytic hydrogen generation is a novel, eco-friendly and favourable method for production of green and clean energy using light energy. In this direction, we report low-temperature ionothermal method for the preparation of TiO2 nanoparticles (NPs) using methoxy ethyl methyl imidazolium tris (pentafluoroethyl) trifluoro phosphate (MOEMINtf2) as an ionic liquid (IL) at 120°C for 1 day. The synthesized nanomaterials were examined using different spectrochemical methods like UV-DRS, XRD, FT-IR, TEM, BET and TGA-DTA techniques. The mixed phase TiO2 is obtained with 81.7% of anatase and 18.3% of rutile phase by the XRD studies, and average crystallite size is found to be ∼7 nm. The stretching of Ti-O bond (∼555 cm−1) and few other bands related to ionic liquid were confirmed by FTIR spectrum. The band gap energy was observed to be ∼3.38 eV by UV-DRS analysis. TEM images reveal spherical shape with an average particles size of about 10 nm. Photocatalytic H2 generation was carried out using TiO2 NPs and observed the generation of 553 μmol h−1 g−1 via water splitting reaction. Furthermore, the prepared TiO2 NPs employed for the photocatalytic degradation of methylene blue dye (84.54%), and photoluminescence studies confirms the obtained material can be used in optoelectronic applications with green emission. 相似文献
14.
Telecommunication Systems - In the era of Internet-of-things (IoT), the future 5G networks are supposed to provide ubiquitous connectivity, high speed, as well as low latency and energy efficiency... 相似文献
15.
Nabil Dawahre Gang Shen Soner Balci William Baughman David S. Wilbert Nick Harris Lee Butler Rich Martens Seongsin Margaret Kim Patrick Kung 《Journal of Electronic Materials》2012,41(5):801-808
Wide-bandgap zinc oxide (ZnO) semiconductors and nanowires have become important materials for electronic and photonic device
applications. In this work, we report the growth of well-aligned single-crystal ZnO nanowire arrays on sapphire substrates
by chemical vapor deposition and the development of atom probe tomography, an emerging nanoscale characterization method capable
of providing deeper insight into the three-dimensional distribution of atoms and impurities within its structure. Using a
metal-catalyst-free approach, the influence of the growth parameters on the orientation and density of the nanowires were
studied. The resulting ZnO nanowires were determined to be single crystalline, with diameter on the order of 50 nm to 150 nm
and length that could be controlled between 0.5 μm to 20 μm. Their density was on the order of high 108 cm−2 to low 109 cm−2. In addition to routine characterizations using scanning and transmission electron microscopy, x-ray diffraction, photoluminescence,
and Raman spectroscopy, we developed the atom probe tomography technique for ZnO nanowires, comparing the voltage pulse and
laser pulse modes. In-depth analysis of the data was carried out to determine the accurate chemical composition of the nanowires
and reveal the incorporation of nitrogen impurities. The current–voltage characteristics of individual nanowires were measured
to determine their electrical properties. 相似文献
16.
A theoretical investigation has been conducted for the prediction of the critical height at the onset of gas entrainment during single discharge from a stratified, two‐phase region, through a branch installed on an inclined flat wall. The predicted critical height at the onset of gas entrainment was proven to be a function of Froude number (Fr) and density ratio of the interface fluids. Three different experimental data sets at wall inclination angles of zero, 45 and 90 degrees (i.e. side, inclined and bottom branches) were used for comparisons. A good concurrence was illustrated between the experimental and theoretical values. 相似文献
17.
Zine Eddine Cherif Christophe Poilne Thierry Falher Alexandre Vivet Nabil Ouail Bessem Ben Doudou Jun Chen 《Polymer Composites》2013,34(10):1761-1773
The aim of the present work is to study the effect of conventional textile treatments of woven flax on the mechanical properties and the water sorption of flax/epoxy composites. The flax fabrics are standard 2/2 twills. Various treatments are carried out on fabric such as mercerization, bleaching, and leaching for long fibers or on yarn such as leaching for short fibers. A model, based on a modified rule of mixture applied to composite reinforced with woven fabric, is developed to include the effect of fiber and porosity volume fractions on composite stiffness and strength. Most treatments improve tensile stiffness and strength of flax/epoxy composite and reduce composite water sorption. We prove by X‐ray fluorescence analysis, thermogravimetric analysis, and tensile tests of dry fabric that it is due to an improvement in the interfacial bonding between fibers and matrix. The best performances are achieved with bleaching and mercerization treatment. The weakest performances are obtained with the composites made with leached yarns. POLYM. COMPOS., 34:1761–1773, 2013. © 2013 Society of Plastics Engineers 相似文献
18.
The design of a novel micro‐screw pump for viscous fluid is described. The device consists of a rotating screw in the centre of the channel, connected with a shaft and micro motor. The objective of this research is to investigate the effect of using various screw geometries on the pump performance. Theoretical analysis by finite volume simulations is carried out to study the influence of pitch, diameter of the screw and the thread (flight depth) to evaluate the optimal dimensions for the pump and to obtain the maximum flow rate. When the screw rotates, a net force is transferred to the fluid due to the differential pressure on the depth of the thread and pressure gradient along the screw axis, thus causing the fluid to displace. The three‐dimensional simulations indicate a gradual increase of the average velocity with increasing the screw diameter. The maximum average velocity can be obtained when the ratio between the pitch and screw diameter (pi/d) is 0.6. Effective pumping is achieved by increasing the thread and pitch at maximum screw diameter. The numerical simulation has been validated experimentally. 相似文献
19.
Preparation,characterization, and dynamic adsorption–desorption studies on polypyrrole encapsulated TiO2 nanoparticles 下载免费PDF全文
Binary doped polypyrrole (PPy) encapsulated Titania (TiO2) nanoparticles were prepared by oxidative polymerization using FeCl3 as oxidant in presence of camphorsulfonic acid (CSA) as surfactant. Both FeCl3 (oxidant) and camphorsulfonic acid (surfactant) also act as dopant and hence thus prepared polypyrrole/Titania (TiO2@PPy) is termed as binary doped nanocomposite i.e. FeCl3 dopes polypyrrole by oxidation mechanism while camphorsulfonic acid dopes polypyrrole by protonic doping mechanism. The TiO2@PPy coreshell nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetry, differential scanning calorimetry (DSC), field emission‐scanning electron microscopy (FE‐SEM), and inductance‐capacitance‐resistance (LCR) measurements. The results indicated that the structural and electrical properties of the TiO2@PPy coreshell nanocomposites were significantly influenced by the extent of TiO2 nanoparticles loading of polypyrrole. The direct current (DC) electrical conductivity of the as‐prepared TiO2@PPy coreshell nanocomposites was higher than that of PPy. As‐prepared TiO2@PPy coreshell nanocomposites were also studied for their dielectric losses for alternating current (AC) which is useful characteristic for their application in the fabrication of charge storing devices. TiO2@PPy coreshell nanocomposites showed synergistic effect of combining components in improving their alcohol sensing properties. This improvement may be attributed to the adsorption on and desorption from alcohols TiO2@PPy interface of the nanocomposites and alcohol vapors causing decrease in depletion region. The TiO2@PPy coreshell nanocomposites were observed to show better reproducibility of electrical conductivity and fast self‐recovery during the alcohol vapor sensing process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43411. 相似文献
20.
Commercial fillers, including carbon black (N550), halloysite nanotubes (HNTs), and precipitated silica, were replaced by recycled poly(ethylene terephthalate) powder (R‐PET) in natural rubber (NR) composites. Five different compositions of NR/N550/R‐PET, NR/HNTs/R‐PET, and NR/silica/R‐PET compounds, i.e., 100/20/0, 100/15/5, 100/10/10, 100/5/15, and 100/0/20 parts per hundred rubber (phr), were prepared on a two‐roll mill. The curing behavior, tensile properties, and morphological characteristics of the natural rubber composites were investigated. The results indicated that the replacement of carbon black, HNTs, and silica by R‐PET decreased the tensile strength and tensile modulus, such that NR/silica/R‐PET composites showed the lowest effect, followed by NR/HNTs/R‐PET and NR/N550/R‐PET composites. The negative effect on these properties can be explained by the decrease of crosslink density. The curing results revealed that with the replacement of carbon black by R‐PET, the scorch time and cure time decreased, but that the NR/HNTs/R‐PET and NR/silica/R‐PET composites exhibited the opposite trend. Scanning electron microscopy investigation of tensile fracture surfaces confirmed that the co‐incorporation of N550/R‐PET improved the dispersion of R‐PET and enhanced the interaction between the fillers and NR matrix more than R‐PET and silica/R‐PET hybrid fillers. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers 相似文献