The present environmental and economic conditions call for the increased use of hybrid energy resources and, concurrently, recent developments in combined heat and power (CHP) systems enable their use at a domestic level. In this work, the optimal scheduling of electric and gas energy resources is achieved for a smart home (SH) which is equipped with a fuel cell-based micro-CHP system. The SH energy system has thermal and electrical loops that contain an auxiliary boiler, a battery energy storage system, and an electrical vehicle besides other typical loads. The optimal operational cost of the SH is achieved using the real coded genetic algorithm (RCGA) under various scenarios of utility tariff and availability of hybrid energy resources. The results compare different scenarios and point-out the conditions for economic operation of micro-CHP and hybrid energy systems for an SH.
SummaryThe synthesis, as well as spectroscopic and thermochemical studies of a novel class of carbazole-4-phenylpyridine co-polymers are described. The synthesis was carried out by a simple and cheaper method compared to the lengthy methods usually adopted for the preparation of carbazole–pyridine copolymers which involve costly catalysts. Thus, two series of polymers were synthesized by a modified Chichibabin reaction, i.e., by the condensation of diacetylated N-alkylcarbazoles with 3-substituted benzaldehydes in the presence of ammonium acetate in refluxing acetic acid. All the polymers were characterized by FTIR, 1H NMR, 13C NMR, UV–vis spectroscopy, fluorimetry, TGA and DSC. The weight average molecular masses (M w) of the polymers were estimated by the laser light scattering (LLS) technique.
A series of new molecular materials with varying carbazole and fluorene contents were prepared employing Suzuki coupling and their properties were compared. A variation of the core nucleus from fluorene to carbazole was a key point to study its effect on thermal, optical and electrochemical properties. The materials were characterized by FTIR, 1 H-, 13 C-NMR, APCI-MS and elemental microanalyses. The synthesized materials exhibit the slight bathochromic shifted UV/Vis spectra in dilute solution and emission maxima in the blue region along with good thermal stability. The dyes with fluorene core are electrochemically and spectrally stable with high lying HOMO levels, in contrast to the carbazole only materials, having the potential as light emitting and hole transporting materials in organic light emitting diodes. chemical stabilities, exceptional electronic and optical properties. 1-3 Moreover, the advantages of oligomers includes the tuning of their properties by varying the molecular design by selecting the suitable side chain and terminal groups for excellent processing, changing the end-capping groups, or by insertion of certain groups. Thus, by alteration of the conjugated cores charge transporting and emissive properties can be controlled. Consequently, the optoelectronic properties can be optimized by divergent molecular design along with the processing. [4][5][6] Molecular materials can serve as model systems for polymeric systems due to their well-defined structure, monodispersity as well as high purity since the purification of small molecules is much easier, as compared to the polymers. 7The excellent hole-transporting capacity, high charge carrier mobility, the formation of stable radical cations coupled with efficient thermal, morphological and photophysical properties 8 of carbazole makes possible its proficient use in organic semiconductor devices like OLED 9 , solar cells, 10 and non-linear optic (NLO) materials 11 either as a main core/or as a substituent. Zhu et al have reported the synthesis of carbazole only oligomers with improved properties for OLEDs. 12 A series of phosphine oxide hosts with different hole transporting carbazolyl units were designed for blue phosphorescent OLEDs with improved efficiency. 13-16 Recently, aryl amine modified phosphine oxide hosts have also been developed. 17 Conversely, on account of the synthetic versatility of fluorene moiety at aromatic 2,7 and C-9 positions alongwith thermal and chemical stability 18 its use in optoelectronic devices has extensively been investigated. Fluorene derivatives have been used as blue-emitting materials in (OLEDs). 19 Solubility and photoluminescent quantum yield of a number of fluorene based compounds are appropriate for use in OLEDs different electron donor and acceptor substituents in their structure in order to adjust the HOMO and LUMO energy levels. For this purpose, carbazole-fluorene based dendrimers are being synthesized with improved hole transporting properties for multilayer OLEDs applications. 22 Nobile et al reported...
We investigate characteristics of THz waves radiated from differently doped graphite samples excited by femtosecond laser pulses. Between n-type single-crystalline graphite and p-type polycrystalline graphite films, we observe the phase reversal of THz waves regardless of excitation energy variations around K-valley. In addition, variations in other parameters such as excitation fluence and azimuthal angle produce no changes in the phase of THz waves, which correlate well with the opposite dipole polarization between differently doped samples rather than unidirectional diffusive transport.
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