Joint estimation of synchronization impairments in MIMO-OFDM system

A joint Maximum Likelihood (ML) estimation algorithm for the synchronization impairments such as Carrier Frequency Offset (CFO), Sampling Frequency Offset (SFO) and Symbol Timing Error (STE) in single user MIMO-OFDM system is investigated in this work. A received signal model that takes into account the nonlinear effects of CFO, SFO, STE and Channel Impulse Response (CIR) is formulated. Based on the signal model, a joint ML estimation algorithm is proposed. Cramer-Rao Lower Bound (CRLB) for the continuous parameters CFO and SFO is derived for the cases of with and without channel response effects and is used to compare the effect of coupling between different estimated parameters. The performance of the estimation method is studied through numerical simulations.

Thermodynamics of NdRhO3 and phase relations in the system Nd-Rh-O

Phase equilibrium experiments indicate that NdRhO3 is the only ternary oxide in the system Nd-Rh-O at 1273 K; it has orthorhombically-distorted perovskite structure. By employing a solid-state electrochemical cell incorporating calcia-stabilized zirconia as the electrolyte, thermodynamic properties of NdRhO3 are determined. The standard Gibbs energy of formation of NdRhO3 from its component binary oxides in the temperature ranges from 900 to 1300 K can be expressed as: 1/2Rh(2)O(3) (ortho)+1/2Nd(2)O(3)(hex)=NdRhO3(ortho), Delta(f(o,x))G(0)/J mol(-1)( +/- 197) = - 66256+5.64 (T/K). The decomposition temperature of NdRhO3 computed from extrapolated thermodynamic data is 1803 (+/- 4) K in pure oxygen and 1692 (+/- 4) K in air at standard pressure. Oxygen partial pressure-composition diagram and three-dimensional chemical potential diagram at 1273 K are developed from thermodynamic data obtained in this study and auxiliary information from the literature. Equilibrium temperature-composition phase diagrams at constant oxygen partial pressures are also constructed. (C) 2013 Elsevier Ltd. All rights reserved.

Growth of AgInS2 thin films by ultrasonic spray pyrolysis technique

Silver Indium Di-sulfide (AgInS2) thin films are deposited using ultrasonic spray pyrolysis technique and the effect of substrate temperature (T-s) on film growth is studied by varying the temperature from 250 to 400 degrees C. From the structural analysis, orthorhombic AgInS2 phase is identified with preferential orientation along (002) plane. Further analysis with Raman revealed the coexistence of Cu-Au ordered and chalcopyrite structures in the films. Stoichiometric films are obtained at T-s of 300 degrees C. Above 300 degrees C, the film conductivity changed from p to n-type and the grain size decreased. The band gap of AgInS2 films varied from 1.55 to 1.89 eV and absorption coefficient is found to be >10(4) cm(-1). The films have sheet resistance in the range of 0.05 to 1300 Omega/square Both p and n type films are prepared through this technique without any external doping. (C) 2013 Elsevier B.V. All rights reserved.

Synthesis of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes composite for supercapacitance application

We are reporting the fabrication, characterizations and supercapacitance performance of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes (BI-GO/MWCNTs) composite. The synthesis of BI-GO materials involves cyclization reaction of carboxylic groups on GO among the hydroxyl and amino groups on o-phenylenediamine. The BI-GO/MWCNTs composite has been fabricated via in situ reduction of BI-GO using hydrazine in presence of MWCNTs. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize its surface and elemental composition. The uniform dispersion of MWCNTs with BI-GO helps to improve the charge transfer reaction during electrochemical process. The specific capacitance of BI-GO/MWCNTs composite is 275 and 460 F/g at 200 and 5 mV/s scan rate in 1 mol/L aqueous solution of H2SO4. This BI-GO/MWCNTs composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate, which represents its good electrochemical stability. (C) 2014 Elsevier B.V. All rights reserved.

Dynamic compression behavior of reactive spark plasma sintered ultrafine grained (Hf, Zr)B-2-SiC composites

This paper reports the dynamic compression behavior of ultrafine grained (Hf, Zr)B-2-SiC composites, sintered using reactive spark plasma sintering at 1600 degrees C for 10 min. Dynamic strength of similar to 2.3 GPa has been measured using Split Hopkinson Pressure Bar (SHPB) tests in a reproducible manner at strain rates of 800-1300 s(-1). A comparison with competing boride based armor ceramics, in reference to the spectrum of properties evaluated, establishes the potential of (Hf, Zr)B-2-SiC composites for armor applications. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Nanomaterial-based ionic polymermetal composite insect scale flapping wing actuators

Small size actuators (8 mm x 1 mm), IPMNC (RuO2/Nafion) and IPMNC (LbL/CNC) are studied for flapping at the frequency of insects and compared to Platinum IPMC-Pt. Flapping wing actuators based on IPMNC (RuO2/Nafion) are modeled with the size of three dragonfly species. To achieve maximum actuation performance with Sympetrum Frequens scale actuator with optimized Young's modulus, the effect of variation of thickness of electrode and Nafion region of Sympetrum Frequens scale actuator is studied. A trade-off in the electrode thickness and Young's modulus for dragonfly size IPMNC-RuO2/Nafion actuator is essential to achieve the desirable flapping performance.