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排序方式: 共有68条查询结果,搜索用时 46 毫秒
1.
We report here on an ecologically friendly carbothermal reduction method to realize SrS:Ce phosphor. The method effectively reduces the preparation temperature by 100 °C. The effect of sulfur and charge compensator were studied separately and in combination, on the luminescent properties of SrS:Ce phosphor prepared from SrSO4:Ce(SO4)2·4H2O using this method without inert gas or hazardous gas (H2S) environment. To analyze the role of charge compensator on the luminescent emission property of SrS:Ce, various fluxes, viz., NH4Cl, NaCl were used. The synthesized products were characterized by XRD, photoluminescence emission and excitation spectroscopy (PLE). SrS:Ce showed a bright blue-green emission at 480 and 540 nm corresponding to energy bands originating from 2T2g (5d) to 2F7/2, 2F5/2 (4f) of Ce3+ transitions. The characterization results showed the formation of SrS calcined at 900 °C for 5 h with an increase in blue-green luminescence intensity after the addition of sulfur and charge compensator, separately. When the sulfur and NH4Cl were jointly added, the intensity of blue emission was enhanced, whereas, that of green emission was suppressed. The excitation spectrum showed a fundamental absorption of SrS host crystal lattice at 283 nm and Ce3+ absorption at 430 nm respectively. The CIE (Commission International de’Eclairge) chromaticity coordinates of the phosphor are also reported. 相似文献
2.
Thiyagarajan Subramanian Ankit Sonthalia 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2019,41(16):1972-1982
The present study aims to reduce carbon dioxide (CO2) emission from a CI engine using calcite/activated carbon-based post-combustion CO2 capture system fueled with Calophyllum inophyllum biodiesel (B100). The tests were conducted in a two-cylinder CI engine used in tractors at different load conditions. The performance and emission parameters of diesel and B100 with and without calcite and activated carbon-based CO2 capture system were studied. The results show that compared to diesel, CO2 emission increased by 19% for B100 due to high fuel-bound oxygen and carbon. Higher NO emission with a slightly reduced smoke opacity is observed with B100 combustion. CO2 emission is reduced with the CO2 capture system for both diesel and B100. CO2 emission is reduced by 11.5% and 7.3% for diesel with calcite and activated carbon, respectively, and reduced by 15.8% and 10.5% for B100 with calcite and activated carbon. Due to the adsorption capacity of both calcite and activated carbon, NO and smoke opacity are reduced considerably. The results display that calcite is better in reducing CO2 compared to activated carbon-based CO2 capture system. It is perceived that the combination of biofuel and calcite-based CO2 capture system can both reduce engine-out emissions and cause a net negative CO2 emission as it is renewable aiding in mitigation of global warming effects. 相似文献
3.
Aruna Devi Balasubramanian Pallikonda Rajasekaran Murugan Arun Prasath Thiyagarajan 《International journal of imaging systems and technology》2019,29(4):399-418
Computer-aided diagnosis (CAD) is a computerized way of detecting tumors in MR images. Magnetic resonance imaging (MRI) has been generally used in the diagnosis and detection of pancreatic tumors. In a medical imaging system, soft tissue contrast and noninvasiveness are clear preferences of MRI. Inaccurate detection of tumor and long time consumption are the disadvantages of MRI. Computerized classifiers can greatly renew the diagnosis activity, in terms of both accuracy and time necessity by normal and abnormal images, automatically. This article presents an intelligent, automatic, accurate, and robust method to classify human pancreas MRI images as normal or abnormal in terms of pancreatic tumor. It represents the response of artificial neural network (ANN) and support vector machine (SVM) techniques for pancreatic tumor classification. For this, we extract features from MR images of pancreas using the GLCM method and select the best features using JAFER algorithm. These features are analyzed by five classification techniques: ANN BP, ANN RBF, SVM Linear, SVM Poly, and SVM RBF. We compare the results with benchmark data set of MR brain images. The analytical outcome presents that the two best features used to classify the MR images using ANN BP technique have 98% classification accuracy. 相似文献
4.
Kannan Radhakrishnan Sruthi Kalyanasundharam Nandini Ravichandran Subramanian Thiyagarajan 《分离科学与技术》2018,53(1):13-21
Automobile emissions are composed of NOx and unburned hydrocarbon that contribute significantly to major environmental and health issues. In this study, encapsulated Moringa oleifera beads (EMBs) were synthesized using Moringa oleifera pod powder that was cross-linked with calcium alginate and used as a biosorbent for reducing the emission gas concentrations from the single-cylinder diesel engine. The breakthrough curve was attained from single and double stage of fixed bed column by the influence of temperature ranging from (80°C–120°C) ± 5°C with a feed flow rate varying from 8 to 10 kg hr–1 and bed height varying from 15 to 30 cm. Based on the experimental results, the maximum biosorption capacity (qo) was found to be 14.45 and 123.51 mg g–1 for HC and NOx, respectively, and was obtained at 80°C–90°C with double stage of BH–30cm under flow rate of 8 kg hr–1. Further, breakthrough curves were investigated, and the experimental data were fitted using well-established models like Thomas, Yoon–Nelson, and Wang models. In addition, mass transfer models like Weber–Morris and Boyd were investigated to identify the rate-limiting step of the overall biosorption process. 相似文献
5.
The microstructure of trans‐4‐methacryloyloxyazobenzene–methyl methacrylate copolymers prepared by solution polymerization process using AIBN as initiator is analyzed by one‐and two‐dimensional spectroscopy. Sequence distribution was calculated from the 13C(1H)‐NMR spectra of the copolymers. Comonomer reactivity ratios were determined using the Kelen–Tudos and the nonlinear error‐in‐variables methods are rA = 1.14 ± 0.08 and rM = 0.51 ± 0.03; rA = 1.13 ± 0.1 and rM = 0.50 ± 0.04, respectively. The sequence distribution of A‐ and M‐centered triads determined from 13C(1H)‐NMR spectra of copolymer is in good agreement with triad concentration calculated from a statistical model. The 2‐D heteronuclear single‐quantum correlation and correlated spectroscopy (TOCSY) was used to analyze the complex 1H‐NMR spectrum. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3016–3025, 1999 相似文献
6.
B. Thiyagarajan V. Senthilkumar S. Suresh 《Transactions of the Indian Institute of Metals》2017,70(10):2555-2561
The nickel based as-atomized thermal spray feedstock powder (NiCrFeSiB) was ball milled to produce the nanostructured powder. The feedstock powder was mechanically milled using two station planetary ball-mill. The milled and unmilled feedstock powders were coated using High-velocity oxygen fuel system to produce nanostructured and conventional coatings respectively on the carbon steel substrate (SA210 Grade C). The metallurgical characterization of feedstock powders and coatings were performed using scanning electron microscope, High resolution- transmission electron microscope coupled with energy dispersive spectroscopy and X-ray diffraction techniques. The developed coatings were mechanically characterized by microhardness test and bond strength measurement techniques. The porosity of the coating was measured by analyzing the optical microscope image using the image-J software. In this study, nanostructured coatings exhibited higher hardness, less porous and better bond strength compared to conventional coating. 相似文献
7.
8.
Small‐angle neutron scattering (SANS) data for n‐octane solutions of TBP loaded with progressively larger amounts of HNO3, HClO4, H2SO4, and H3PO4 up to and beyond the LOC (limiting organic concentration of acid) condition, were interpreted using the Baxter model for hard spheres with surface adhesion. The coherent picture of the behavior of the TBP solutions derived from the SANS investigation discussed in this paper confirmed our recently developed model for third phase formation. This model analyses the features of the scattering data in the low Q region as arising from van der Waals interactions between the polar cores of reverse micelles. Our SANS data indicated that the TBP micelles swell when acid and water are extracted into their polar core. The swollen micelles have critical diameters ranging from 15 to 22 Å, and polar core diameters between 10 and 15 Å, depending on the specific system. At the respective LOC conditions, the TBP weight‐average aggregation numbers are ~4 for HClO4, ~6 for H2SO4, ~7 for HCl, and ~10 for H3PO4. The comparison between the behavior of HNO3, a non‐third phase forming acid, and the other acids provided an explanation of the effect of the water molecules present in the polar core of the micelles on third phase formation. The thickness of the lipophilic shell of the micelles indicated that the butyl groups of TBP lie at an angle of ~25 degrees relative to a plane tangent to the micellar core. The critical energy of intermicellar attraction, U(r), was about ?2 kBT for all the acids investigated. This value is the same as that reported in our previous publications on the extraction of metal nitrates by TBP, confirming that the same mechanism and energetics are operative in the formation of a third phase, independent of whether the chemical species extracted are metal nitrate salts or inorganic acids. 相似文献
9.
ABSTRACT The aggregation of several metal complexes formed during solvent extraction with P,P'-di(2-ethylhexyl) ethanediphosphonic acid, H2DEH[EDP], and by P,P'-di(2-ethylhexyl) butanediphosphorac acid, H2DEH[BuDP], in deuterated toluene, has been investigated by small angle neutron scattering (SANS). With H2DEH[EDP], the extraction of Ca(II), La(IH) and U(VT) does not disrupt the cyclic hexameric structure of the ligand in solution. Fe(III) and Th(IV) complexes of H2DEH[EDP], on the other hand, exhibit a very modest tendency to aggregate but only at very high metal loading in the organic phase. With H2DEH[BuDP], the extraction of Ca(H), La(III), U(VI) and Th(IV) is not accompanied by significant aggregation of the metal complexes The Fe(HI)-H2DEH[BuDP] complexes, however, form long cylindrical aggregates similar to those previously observed with P,P'di(2-ethylhexyl) methanediphosphonic acid, H2DEH[MDP]. The aggregation behavior of the various metal-extractant species is discussed in light of the information obtained from earlier solvent extraction, vapor pressure osmometry, and infrared spectroscopy studies. 相似文献
10.
Ganesh Babu Thiyagarajan Renjith Devasia 《Journal of the American Ceramic Society》2019,102(1):476-489
This study reports a simple and low-cost synthetic route for preparing SiBCN ceramic powder via pyrolysis of boron-modified cyclotrisilazane (BCTS). BCTS resins were synthesized by reacting boric acid with 1, 3, 5-trimethyl-1′, 3′, 5′-trivinylcyclotrisilazane (CTS) in the molar ratio of 1:1, 1:3, and 1:5. The boron modification in CTS resin resulted in optimum properties for preceramic polymers such as solubility in common solvents, processable viscosity (<20 cps) and high ceramic yield (>80 wt. %). The polymer to ceramic conversion was carried out at 1450 and 1650°C under a nitrogen atmosphere. The study demonstrated that the changes in CTS concentration and pyrolysis temperature significantly affected the evolution of ceramic phases, morphology, and elemental composition which were thoroughly investigated through XRD, SEM, and HRTEM techniques. The results revealed the formation of β-SiC, β-Si3N4, and oxide ceramic phases with BCTS in the molar ratio of 1:1 and 1:3; whereas, β-SiC, β-Si3N4, and turbostratic BN(C) ceramic phases were obtained with BCTS in the molar ratio of 1:5. 相似文献