198,837 research outputs found
CNN-based deep learning technique for improved H7 TLI with grid-connected photovoltaic systems
Get PDFIn this article, a three-phase transformerless inverter (TLI) for a solar photovoltaic (PV) system connected to a high-power grid are proposed, which has advantages of better performance and lower cost. The primary concern about the TLI is fluctuations in the common-mode voltage, which impacts switching frequency leakage current and grid interface system. An improved H7 common-mode voltage (CMV) clamped TLI with discontinuous pulse width modulation (DPWM) is designed using a conventional neural network (CNN)-based deep learning approach. In this, a completely minimized leakage current is obtained to avoid CMV transients. The proposed PV-connected improved H7-TLI provides low-loss DC-side decoupling, which further reduces leakage current and isolation of the PV system during off-grid. In addition, the effects of several factors on CNN deep learning performance are explored, including training data size, image resolution, and network configuration. The proposed technique has the potential to be used in a test instrument for intelligent signal analysis or used in an artificial intelligence system. Switching loss is analyzed using proposed and existing H7 inverters under different load conditions. To verify the theoretical explanation, existing H7 inverters is analyzed by MATLAB/Simulink, and the outcomes are tested experimentally. The total harmonic distortion (THD) analysis of proposed and existing topology is analyzed and compared. The THD values of the existing and proposed topology are 3.74% and 3.23%, respectively
Characterization of 〈0 1 0〉 directed KAP single crystals grown by Sankaranarayanan–Ramasamy (SR) method
No full textSingle crystals of potassium acid phthalate (KAP), a semi-organic compound, have been grown at an average growth rate of 4 mm/day from aqueous solution by using the uniaxial crystal growth method of Sankaranarayanan–Ramasamy (SR). Transparent, cylindrical KAP crystal of size 70 mm length and 15 mm diameter was grown. The grown crystals were characterized by etching and UV–vis NIR analysis. HRXRD analysis indicates that the crystalline perfection of SR method-grown KAP is good. The KAP crystals grown by SR method have 9% higher transmittance than conventional method-grown crystal. The microhardness test was carried out on the (0 1 0) face and a load-dependent hardness was observed. TG–DTA evaluated the thermal properties of the grown crystal. KAP was found to be thermally stable up to 290 °C. The dielectric constant and dielectric loss of the crystal were studied as function of frequency and temperature
The growth of benzophenone crystals by Sankaranarayanan-Ramasamy (SR) method and slow evaporation solution technique (SEST): A comparative investigation
No full textLongest unidirectional benzophenone (BP) crystal having dimension of 1060 mm length and 55 mm diameter was grown by Sankaranarayanan-Ramasamy method. The growth rate was measured by monitoring the elevation of the crystal-solution interface at different temperatures. The high resolution X-ray diffraction and etching measurements indicate that the unidirectional grown benzophenone crystal has good crystalline perfection and less density of defects. The optical damage threshold of SEST and SR grown BP crystals has been investigated and found that the SR grown benzophenone crystal has higher laser damage threshold value than the conventional method grown crystal. Microhardness measurement shows that crystals grown by SR method have a higher mechanical stability than the crystals grown by SEST method. Dielectric permittivity and birefringence are high in SR grown crystal compared to SEST grown BP crystal. The UV-vis-NIR results show that SR method grown crystal exhibits 7% higher transmittance as against crystals grown by conventional method
Carbon Nanotubes as an Alternative to Copper Wires in Electrical Machines: A Review
Get PDFThe surge in electric vehicles (EVs) and their electrical appliances requires highly efficient, lightweight electrical machines with better performance. However, conventional wire used for electrical machine windings have certain limits to the current requirements. Copper is a commonly used material in electrical windings, and due to its ohmic resistance, it causes 75% of total losses in electrical machines (copper losses). The high mass of the copper results in a bulky system size, and the winding temperature of copper is always maintained at less than 150 °C to preserve the thermal insulation of the electric machine of the windings. On the other hand, carbon nanotubes and carbon nanotube materials have superior electrical conductivity properties and mechanical properties. Carbon nanotubes ensure 100 MS/m of electrical conductivity, which is higher than the copper electrical conductivity of 59.6 MS/m. In the literature, various carbon nanotubes have been studied based on electrical conductivity, temperature co-efficient with resistivity, material thickness and strength, insulation, and efficiency of the materials. Here, we review the electrical and mechanical properties of carbon nanotubes, and carbon nanotube composite materials are reviewed with copper windings for electrical wires
Ferrocene-derivatized ordered mesoporous carbon as high performance counter electrodes for dye-sensitized solar cells
No full textFerrocene-derivatized large pore size mesocellular carbon foam (Fe-MCF-C) has been synthesized using divinylbenzene as a carbon source and mesocellular silica foam as a hard template. Cyclic voltammetric studies demonstrate a relatively faster electron transfer rate of Fe-MCF-C in K(3)Fe(CN)(6)/1 M KNO(3) solution, as compared with pristine mesocellular carbon foam (MCF-C). Such an enhanced electrochemical property is beneficial for improving the cathodic reduction of tri-iodide in dye-sensitized solar cells (DSSCs). Under 1 sun illumination (100 mW cm(-2), AM 1.5G), Fe-MCF-C counter electrode based DSSC shows an energy conversion efficiency of 7.89%, which is 12% higher than that of solar cell based on pristine MCF-C counter electrode. (C) 2010 Elsevier Ltd. All rights reserved.
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Selection of Infective Arbuscular Mycorrhizal Fungal Isolates for Field Inoculation
Get PDFArbuscular mycorrhizal (AM) fungi play a key role in host plant growth and health, nutrient and water uptake, plant community diversity and dynamics. AM fungi differ in their symbiotic performance, which is the result of the interaction of two fungal characters, infectivity and efficiency. Infectivity is the ability of a fungal isolate to establish rapidly an extensive mycorrhizal symbiosis and is correlated with pre-symbiotic steps of fungal life cycle, such as spore germination and hyphal growth. Here, different AM fungal isolates were tested, with the aim of selecting infective endophytes for field inoculation. Greenhouse and microcosm experiments were performed in order to assess the ability of 12 AM fungal isolates to produce spores, colonize host roots and to perform initial steps of symbiosis establishment, such as spore germination and hyphal growth. AM fungal spore production and root colonization were significantly different among AM fungal isolates. Spore and sporocarp densities ranged from 0.8 to 7.4 and from 0.6 to 2.0 per gram of soil, respectively, whereas root colonization ranged from 2.9 to 72.2%. Percentage of spore or sporocarp germination ranged from 5.8 to 53.3% and hyphal length from 4.7 to 79.8 mm. The ordination analysis (Redundancy Analysis, RDA) showed that environmental factors explained about 60% of the whole variance and their effect on fungal infectivity variables was significant (P = 0.002). The biplot clearly showed that variables which might be used to detect infective AM fungal isolates were hyphal length and root colonization. Such analysis may allow the detection of the best parameters to select efficient AM fungal isolates to be used in agriculture
Soft-template synthesized ordered mesoporous carbon counter electrodes for dye-sensitized solar cells
No full textOrdered mesoporous carbon (OMC) with a high surface area (similar to 1575 m(2)/g) and bimodal pores (2.5 and 6.1 nm) was synthesized using a soft-template method employing triblock copolymer F127 as the structure directing agent and then applied as a low-temperature processable counter electrode for dye-sensitized solar cell (DSSC). The OMC counter electrode-based DSSC shows an energy conversion efficiency of 7.46%, whereas that of a Vulcan counter electrode is 4.30%. Electrochemical impedance spectroscopy analysis reveals decreased charge transfer resistance at the OMC counter electrode-electrolyte interface, thus improved fill factor and energy conversion efficiency. (C) 2010 Elsevier Ltd. All rights reserved.
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Re: A Prospective, Blinded Comparison of Magnetic Resonance (MR) Imaging-Ultrasound Fusion and Visual Estimation in the Performance of MR-targeted Prostate Biopsy: The PROFUS Trial
No full textsecondary to nerve-sparing radical retropubic prostatectomy. Rev Urol 2005;7(Suppl 2):S33–8. [4] Zelefsky MJ, Shasha D, Branco RD, et al. Prophylactic sildenafil citrate improves selected aspects of sexual function in men treated by radiotherapy for prostate cancer. J Urol. In press. http://dx.doi. org/10.1016/j.juro.2014.02.097. [5] SandaMG, Dunn RL, Michalski J, et al. Quality of life and satisfaction with outcome among prostate-cancer survivors. N Engl J Med 2008; 358:1250–61. Gavin M. Langille, Jason R. Kovac, Ranjith Ramasamy, James M. Dupree, Larry I. Lipshultz* Department of Urology, Baylor College of Medicine, Houston, TX, US
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
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