23 research outputs found
BER degradation of MC-CDMA at high SNR with MMSE equalization and residual frequency offset
Multicarrier Code Division Multiple Access (MC-CDMA) is an attractive technique for high speed wireless data transmission in view of its advantages over orthogonal frequency division multiplexing. In this paper, we analyze the performance of fully loaded downlink MC-CDMA systems with minimum mean square error (MMSE) equalizer in the presence of residual frequency offset (RFO) in multipath Rayleigh fading channels. We first show that as the SNR is increased beyond a value, referred as threshold SNR, the performance degrades. We then analyze the cause for this behavior and propose a remedy to prevent the degradation by regularizing the coefficient(s) of the equalizer, and use the regularized equalizer for SNRs beyond the threshold value. We suggest two methods for estimating this SNR, one gives close to the true value but requires the knowledge of RFO and the channel state information (CSI), while the other gives an approximate value but requires only CSI. We show that the regularization based on the approximate value also prevents the degradation, but the performance at higher SNRs is slightly poorer compared to that with the better estimate. Numerical and simulation results are provided to support the analysis
Dissipative-particle dynamics simulations of flow over a stationary sphere in compliant channels
Dissipative-particle dynamics (DPD), a particle-based fluid-simulation approach, is employed to simulate isothermal pressure-driven flow across a sphere in compliant cylindrical channels. The sphere is represented by frozen DPD particles, while the surrounding fluid is modeled using simple fluid particles. The channel walls are made up of interconnected finite extensible nonlinear elastic bead-spring chains. The wall particles at the inlet and outlet ends of the channel are frozen so as to hinge the channel. The model is assessed for accuracy by computing the drag coefficient CD in shear flow past a uniform sphere in unbounded flow, and comparing the results with those from correlations in literature. The effect of the aspect ratio 位 of the channel, i.e., the ratio of the sphere diameter d to the channel diameter D, on the drag force FD on the sphere is investigated, and it is found that FD decreases as 位 decreases toward the values predicted by the correlations as 位 approaches zero. The effect of the elasticity of the wall is also studied. It is observed that as the wall becomes more elastic, there is a decrease in FD on the sphere.Harinath Reddy and John Abraha
Magnetism generation & control by using solid state relay for application of absorbing change of conductivity in acids
The Electro Magnetic induction is an electrical instrument which produces the magnetism. By varying the current we control the electro-magnetism in mutual inductance. Here we use SSR as mediator for input and output process. By changing the input voltage we can control the output current. By varying the current we can adjust the magnetism. By hall sensor we can observe the changing in magnetism.
 
The Importance of E-Learning in Present Day Education
ABSTRACT- The potentials of e-learning are likely to be explored for many years to come in view of some of its obvious logistical benefits for learners and apparent financial incentives for institutions. One would hope that such exploration of teaching practice would have a parallel research program to investigate the nature and effects of dialogue and communities of enquiry in e-learning in higher education. The common sense approach to this issue is to compare outcomes of e-learning with those of classroom learning, but this approach has proven to be too simplistic to satisfy those attempting to understand the characteristics and potential of e-learning
Seroreactivity of purified <i>Brugia malayi </i>microfilarial soluble and excretory-secretory antigens in different clinical presentations of bancroftian filariasis
791-796Brugia malayi microfilarial
excretory-secretory (mf ES) and phosphate buffer saline soluble (mf S) antigens
were fractionated by fast protein liquid chromatography (FPLC) on superdex 200
HR 10/30 gel filtration column. The active antigen fractions were identified
and explored in comparison with whole mf ES and mf S antigens to detect
filarial IgG antibodies in different groups viz microfilaraemics, acute,
chronic and occult filarial cases of Wuchereria bancrofti infection and
endemic and non-endemic normals. One of the fractions of mf ES antigen (ESF-6)
and two fractions of mf S antigen (SF-2 & 3) were identified to be useful
to detect filarial antibodies. A pooled preparation of these antigen fractions
gave a sensitivity of 86.6% (for microfilaraemic cases) and a specificity of
95% to detect filarial IgG antibodies by indirect ELISA. The pooled FPLC
purified mf antigens also showed 55-88% of cases of different grades of
clinical filariasis and 65% of tropical pulmonary eosinophilia cases as
positive for filarial antibodies. The pooled FPLC purified B. malayi mf
antigens with higher specificity are preferable to whole mf ES and mf S
antigens to detect active filarial infection in microfilaraemia and as well in
different clinical entities of bancroftian filariasis