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基于DSC及剩余能量感知的最优WSN
Optimized WSN Based on DSC and Residual Energy Awareness
 [PDF]

卿粼波, 何小海
Computer Science and Application (CSA) , 2013, DOI: 10.12677/CSA.2013.32021
Abstract:
针对无线传感器网络(WSN)网络生命周期问题,将分布式信源编码(DSC)引入到WSN中,结合低复杂度剩余能量最优分簇算法,实现了最大化生命周期的最优WSN网络仿真设计分析。首先直接采用剩余能量比对分簇算法的阈值进行修订,然后簇头采用DSC对其分簇中节点数据进行压缩汇集再传输到基站。试验结果表明,剩余能量感知及DSC的引入有效均衡了网络负载,降低簇头传输功耗,提高了WSN的生命周期。
In order to prolong the life time of Wireless Sensor Network (WSN), Distributed Source Coding (DSC) and residual energy awareness have been introduced into WSN. The threshold for deciding the cluster head has been modified by additional awareness of residual energy ratio. Then the cluster head aggregates the nodes’ data in current cluster using DSC, and transmit DSC data to sink. Experimental results have shown the introduction of both residual energy awareness and DSC have effectively balanced the load of the network, reduced the energy consumption of cluster head, upon which the WSN’s lifetime increased.
Rheological and Thermal Behavior of High-Density Polyethylene (HDPE) at Different Temperatures  [PDF]
Cynthia D’Avila Carvalho Erbetta, Getúlio F. Manoel, Ana Paula Lelis Rodrigues Oliveira, Maria Elisa Scarpelli Ribeiro e Silva, Roberto Fernando Souza Freitas, Ricardo Geraldo Sousa
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.513094
Abstract: In the present work, rheological properties of HDPE samples were measured at temperatures of 150°C, 190°C and 230°C. It was shown, by oscillatory tests, at low frequencies, that, for temperatures of 150°C and 190°C, there was a predominance of the viscous behavior over the elastic one. At 230°C, there was a predominance of the elastic contribution, and there was an increase of the molar mass compared with the ones obtained from the tests at 150°C and 190°C. The results obtained from the temperature ramp oscillatory test showed that, up to around 248°C, the viscous behavior prevailed, the opposite being observed at higher temperatures. At 230°C the sample showed significantly lower values of strain when compared with the ones observed at 150°C and 190°C. Oxidative induction time (OIT), melting point and degree of crystallinity were determined by differential scanning calorimetry (DSC). The DSC results and the rheological measurements showed a completely different behavior for the HDPE samples at 230°C compared with the 150°C and the 190°C ones, suggesting that HDPE, at the temperature of 230°C, underwent thermo-oxidative degradation with the initial predominance of crosslinking.
Characterization of the β Phase Decomposition in Ti-5Al-5Mo-5V-3Cr at Slow Heating Rates  [PDF]
Quentin Contrepois, Marc Carton, Jacqueline Lecomte-Beckers
Open Journal of Metal (OJMetal) , 2011, DOI: 10.4236/ojmetal.2011.11001
Abstract: The influence of slow heating rates: 2, 5, 10 and 30?C/min (0.033, 0.083, 0.166 and 0.50℃/s) on the β phase decomposition of Ti-5Al-5Mo-5V-3Cr (Ti-5553) during continuous heating were characterized by differential scanning calorimetry (DSC) analysis, light microscopy, scanning electron microscopy, X-ray diffraction and hardness testing. Starting microstructure was the β phase obtained by heating the Ti-5553 above the Tβ temperature and a water quench. Results show that heating rate has a significant impact on the precipitation mechanisms and on the β→α transformation in this range of heating rates. The main formation of α precipitates occurs between 500 and 600℃at all heating rates tested.A heating at 2℃/min produces very fine and homogeneously distributed α plate precipitates which have nucleated on the nanometer size ωiso precipitates. The ωiso precipitates between 350 and 400℃. At higher heating rates 10, 15 or 30℃/min, the amount of precipitation of ωiso is lower so an additional formation of nanometer size precipitates occurs between 450 and 500℃ It is supposed that both precipitates act as nucleation sites for α phase precipitation. The resultant microstructure consists in a fine intragranular distribution of α precipitates and a coarser precipitation of α at the grain boundaries. It is shown that the precipitation of ωiso phase retards or prevents the precipitation of nanometer size precipitates occurring between 450 and 500℃. This cannot be generalized to all the β-metastable titanium alloys since Ti-LCB does not exhibit the same heating rate dependence on DSC curves.
Tellurium Crystallisation in GeTeSb System  [PDF]
Maamar Belhadji, Hassan Khoussa, Yahia Zanoun, Mohamed Belbachir, Noureddine Hakiki
Journal of Crystallization Process and Technology (JCPT) , 2011, DOI: 10.4236/jcpt.2011.13010
Abstract: Devitrification study of Ge15Te82Sb3 is compared to Ge14Te84.5Sb1.5 amorphous alloys using differential scanning calo-rimetry (DSC) and X-ray diffraction; we show tellurium effect in isothermal crystallization phenomena. The DSC traces of Ge15Te82Sb3 fixed at 413?C show the phase separation in the sample with increasing transition temperatures Tg followed by two crystallization temperatures Tc1 and Tc2. This sample is compared to Ge14Te84.5Sb1.5 which crystallized by two transition temperatures and two crystallization temperatures Tc1 and Tc2. By X. Rays diffraction, we show that this behaviour is due to the presence of two phases in the amorphous sample with composition vitreous change during heating sample, the most important first one corresponds to the tellurium crystallization in the hexagonal form with 1.8 eV activation energy. The second correspond essentially to the crystallization of Te+ GeTe phase with 2.1 eV activation energy.
Synthesis of Fluorite-Type Nanopowders by Citrate-Nitrate Auto-Combustion Process: A Systematic Approach  [PDF]
Mridula Biswas, Prasanta Kumar Ojha, Chadalapaka Durga Prasad, Nitin Madhusudan Gokhale, Suresh Chandra Sharma
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.32017
Abstract: Citrate-nitrate autocombustion process is a promising synthesis route in the field of nanomaterials. This route involves many controlling parameters which ultimately affect properties of the products. In the present research work, the effect of concentration of fuel to that of metal nitrates has been studied in a systematic manner. The nature of exothermic reaction was analyzed with DSC-TGA and the powder properties were characterized by XRD, TEM and BET measurement. The properties of the powders have been explained with respect to fuel content, vigorousness of the exothermic reaction, combustion temperature and duration. The most vigorous reaction was found to occur for the composition with FER of 0.50 with the production of the smallest crystallite size of 9 nm.
Synthesis and Characterization of Poly(D,L-Lactide-co-Glycolide) Copolymer  [PDF]
Cynthia D’Avila Carvalho Erbetta, Ricardo José Alves, Jarbas Magalh?es Resende, Roberto Fernando de Souza Freitas, Ricardo Geraldo de Sousa
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2012, DOI: 10.4236/jbnb.2012.32027
Abstract: The copolymer poly(D,L-lactide-co-glycolide) is one of the most interesting polymers for medical applications. This interest is justified by the fact that it is bioreabsorbable, biocompatible and non-toxic, while its degradation kinetics can be modified by the copolymerization ratio of the monomers. In this study, copolymers were synthesised at 175?C by opening the rings of the cyclic dimers of the D,L-lactide and glycolide monomers in the presence of stannous octoate initiator and lauryl alcohol co-initiator. The application of vacuum to the reaction medium, coupled with adequate stirring, is essential for obtaining good results. The following analytical techniques were used to characterise the synthesised copolymers: Differential Scanning Calorimetry (DSC), Thermogravimetry (TG), Nuclear Magnetic Resonance Spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Both the input monomers and the reaction products were analysed. Important characteristics, such as melting temperature, glass transition temperature, thermal stability, chemical composition and the ratio of the monomers in the synthesised copolymer, were obtained from these analyses. These results helped to infer the absence of residual monomers in the synthesised copolymers.
Thermal Characterization of Se80-xTe20Inx Glasses Using Iso-Conversional Methods  [PDF]
Renu Shukla, Pragya Agarwal, Ashok Kumar
Journal of Crystallization Process and Technology (JCPT) , 2012, DOI: 10.4236/jcpt.2012.22009
Abstract: Alloys of Se80-xTe20Inx glassy system are obtained by quenching technique and crystallization kinetics has been studied using Differential Scanning Calorimetric [DSC] technique. Well defined endothermic and exothermic peaks are ob- served at glass transition temperature (Tg) and crystallization temperature (Tc). From DSC scans, Tc is obtained at dif- ferent heating rates (5, 10, 15, 20, 25 K/min). It is observed that Tc increases with increasing heating rate for a particular glassy alloy. Activation energy of crystallization (Ec) has been calculated by different Non-isothermal Iso-conversional methods, i.e., Kissinger-Akahira-Sunose [KAS], Friedman, Flynn-wall-Ozawa [FWO], Friedman-Ozawa [FO] and Sta-rink methods. It is observed that Ec is dependent on extent of crystallization (α). Activation energy is also found to vary with atomic percentage of In in ternary Se80-xTe20Inx glassy system. The compositional dependence of Ec shows a re-versal in the trend at x = 15 in Se80-xTe20Inx, which is explained in terms of mechanically stabilized structure at this composition.
Preparation and Characterization of Two Polymorphs of (3aRS,4RS,7RS,7aSR)-2-(Tricyclo[3.3.1.13,7]decan-1-yl)-4,5,6,7-tetrahydro-4,7-eposyisoindoline-1,3-dione (SU2162) with PXRD and DSC  [PDF]
Wenfei Chen, Zaiyou Tan, Lin Luo, Ruisi Yan, Hui Yang, Chunmei Tong, Yuqing Huang, Tingyu Huang, Yang Yang, Ruonan Wang
Advances in Materials Physics and Chemistry (AMPC) , 2015, DOI: 10.4236/ampc.2015.51003
Abstract: Objective: To develop the characterization of the polymorphs and the best preparation method of two forms of the title compound (SU2162). After SU2162 was prepared in accordance with the patent process, the crystal form I was recrystallized by ethyl acetate and the crystal form II was obtained by the recrystal in acetone. And the two crystal forms were characterized with differential scanning calorimetry (DSC) and X-ray powder diffraction (PXRD). The melting point of crystal form I (triclinic) is at 158°C, and the melting point of crystal form II (monoclinic) is at 163°C. The PXRD studies of the two crystalline samples indicate that they have the distinct diffraction patterns. The method herein can be stably prepared for the two crystal forms of the title compound.
DC Electrical Conductivity Studies of GeO2 Doped Lead Vanadate Glass System  [PDF]
P. Tejeswararao, D. L. Sastry
New Journal of Glass and Ceramics (NJGC) , 2017, DOI: 10.4236/njgc.2017.73005
Abstract: Temperature dependent DC electrical conductivity studies of GeO2 substituted lead vanadate glass systems xGeO2(50-x)PbO:50V2O5 (x = 5, 10, 15 mole%) were carried out and the results are reported. X-ray diffraction results reveal that all samples are perfect amorphous in nature. DSC results indicate that the substituent GeO2 is replacing PbO in the glass network in such a way that the eutectic composition is maintained. DC electrical conductivity studies of the glass samples indicate that the systems are characterized by different activation energies in different temperature ranges which in turn depend on the annealing temperature. These results are interpreted in terms of temperature dependent microstructural changes in these glass systems.
Hydrothermal Processing of Phase Pure and Doped Hydroxyapatite and its Characterization  [PDF]
Muhammad Musaddique Ali Rafique
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2018, DOI: 10.4236/jeas.2018.81002
Abstract: Hydroxyapatite (HA) is a synthetic ceramic which is used in numerous biomedical applications. However, its use is restricted in load bearing applications. A novel batch hydrothermal method is indigenously developed to synthesize fine size, crystalline hydroxyapatite (HA) and titania doped hydroxyapatite (TiO2-HA) powders with distinct phase formation. Powders were characterized using XRD, FTIR and DSC-TGA. Sharp peaks in HA XRD pattern after sintering at 1000°C indicate significant crystallinity while sharp peaks in TiO2 XRD pattern at 27°, 36° and 5° after sintering indicate anatase to rutile transformation. This fact is also confirmed by FTIR and DSC-TGA Plots.
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