The response of the upper atmospheric temperature to changes in solar EUV radiation and geomagnetic activity

Solar radiation and magnetic effects on upper atmospheric neutral temperatures derived from satellite dra

Acoustic Echo and Noise Cancellation System for Hand-Free Telecommunication using Variable Step Size Algorithms

In this paper, acoustic echo cancellation with doubletalk detection system is implemented for a hand-free telecommunication system using Matlab. Here adaptive noise canceller with blind source separation (ANC-BSS) system is proposed to remove both background noise and far-end speaker echo signal in presence of double-talk. During the absence of double-talk, far-end speaker echo signal is cancelled by adaptive echo canceller. Both adaptive noise canceller and adaptive echo canceller are implemented using LMS, NLMS, VSLMS and VSNLMS algorithms. The normalized cross-correlation method is used for double-talk detection. VSNLMS has shown its superiority over all other algorithms both for double-talk and in absence of double-talk. During the absence of double-talk it shows its superiority in terms of increment in ERLE and decrement in misalignment. In presence of double-talk, it shows improvement in SNR of near-end speaker signal

Magnetic properties of a helical spin chain with alternating isotropic and anisotropic spins: magnetization plateaus and finite entropy

We study a model which could explain some of the unusual magnetic properties observed for the one-dimensional helical spin system Co(hfac)_2 NITPhOMe. One of the properties observed is that the magnetization shows plateaus near zero and near one-third of the saturation value if a magnetic field is applied along the helical axis, but not if the field is applied in the plane perpendicular to that axis. The system consists of a spin-1/2 chain in which cobalt ions (which are highly anisotropic with an easy axis e_i) and organic radicals (which are isotropic) alternate with each other. The easy axis of the cobalts e_i lie at an angle theta_i with respect to the helical axis, while the projection of e_{i+1} - e_i on the plane perpendicular to the helical axis is given by 2 pi /3. For temperatures and magnetic fields which are much smaller than the coupling between the nearest-neighbor cobalts and radicals, one can integrate out the radicals to obtain an Ising model for the cobalts; this enables one to compute the thermodynamic properties of the system using the transfer matrix approach. We consider a model in which the tilt angles theta_i are allowed to vary with i with period three; we find that for certain patterns of theta_i, the system shows the magnetization plateaus mentioned above. At the ends of the plateaus, the entropy is finite even at very low temperatures, while the magnetic susceptibility and specific heat also show some interesting features.Comment: Revtex, 7 pages including 7 figure

Perancangan Interior Healthy Day Care Di Surabaya

Healthy Day Care is a child care center which designed with priority of children's health that applied to all room elements which designed with healthy and attractive design that its application is done by making the formation, color, circulation space, lighting, which draw the attention of the child to can do their activities cheerfully but not excessive. Healthy Day Care is designed to solve the problem of any women who has some problems with her children, seeing the health of children today that are declining due to less activity and less socializing with the surrounding environment. Healthy Day Care must also be able to meet the basic needs of children to achieve the design results in accordance with the original purpose

Enhanced Critical parameters of nano-Carbon doped MgB2 Superconductor

The high field magnetization and magneto transport measurements are carried out to determine the critical superconducting parameters of MgB2-xCx system. The synthesized samples are pure phase and the lattice parameters evaluation is carried out using the Rietveld refinement. The R-T(H) measurements are done up to a field of 140 kOe. The upper critical field values, Hc2 are obtained from this data based upon the criterion of 90% of normal resistivity i.e. Hc2=H at which Rho=90%Rho; where RhoN is the normal resistivity i.e., resistivity at about 40 K in our case. The Werthamer-Helfand-Hohenberg (WHH) prediction of Hc(0) underestimates the critical field value even below than the field up to which measurement is carried out. After this the model, the Ginzburg Landau theory (GL equation) is applied to the R-T(H) data which not only calculates the Hc2(0) value but also determines the dependence of Hc2 on temperature in the low temperature high field region. The estimated Hc(0)=157.2 kOe for pure MgB2 is profoundly enhanced to 297.5 kOe for the x=0.15 sample in MgB2-xCx series. Magnetization measurements are done up to 120 kOe at different temperatures and the other parameters like irreversibility field, Hirr and critical current density Jc(H) are also calculated. The nano carbon doping results in substantial enhancement of critical parameters like Hc2, Hirr and Jc(H) in comparison to the pure MgB2 sample.Comment: 25 pages with 9 Figs: comments/suggestions([email protected]