On the performance analysis of SIR-based SSC diversity over correlated α-μ fading channels

In this paper, an approach to the performance analysis of dual-branch switch-and-stay combining (SSC) diversity receiver, operating over correlated α-μ fading channels in the presence of co-channel interference (CCI), is presented. Very useful novel infinite series expressions are obtained for the probability density function (PDF) and cumulative distribution function (CDF) of the SSC output signal-to-interference ratio (SIR). Capitalizing on these, performance analysis is performed based on standard criterion measures, such as the outage probability (OP) and average bit error probability (ABEP). Obtained results are graphically presented to show the effects of various parameters such as the fading severity, propagation environment non-linearity and level of correlation on the overall system’s performance.     

Convergence and comparison theorems for single and double decompositions of rectangular matrices

Different convergence and comparison theorems for proper regular splittings and proper weak regular splittings are discussed. The notion of double splitting is also extended to rectangular matrices. Finally, convergence and comparison theorems using this notion are presented.     

The Effect of Selective Additives on the Rheological Behavior of Power Plant Ash Slurry

The rheological behavior of power plant ash samples collected from JSPL (M/s Jindal Steel & Power Limited, Raigarh), India, was carried out using a HAAKE rotational rheometer (Model: RheoStress 1, Thermo Fisher Scientific). The ash slurry indicated non-Newtonian behavior in the solids concentration range of 50–60% by mass. The rheological data were best fitted by Bingham plastic model in the studied ranges of concentrations and shear rates. Two selective additives, namely sodium silicate and Ghadi detergent, were applied in small quantities (0–0.6% of total solids) and their effects on rheological parameters were evaluated. It was indicated that the small dosage of sodium silicate substantially influenced the Bingham parameters of the ash slurry than the Ghadi detergent. The percentage reduction in Yield stress at a slurry concentration of 60% by weight were found to be 59.3% and 46.23% for sodium silicate and Ghadi detergent, respectively, at a maximum dosage of 0.6% additives. More importantly, the plastic viscosity reduced by 37.6% and 16.3%, respectively, with the same dosage of sodium silicate and Ghadi detergent at same slurry concentration.     

Studies of dielectric and varistor behavior of lead manganese tungstate ceramics

Polycrystalline samples of Pb(Mn_1/2W_1/2)O₃ were prepared by the high-temperature solid-state reaction technique. Preliminary crystal structure and microstructure of the compound at room temperature were studied using the X-ray diffraction (XRD) technique and scanning electron microscopy (SEM), respectively. The dielectric permittivity () and loss tangent (tan) of the compound were obtained both as a function of frequency (0.5×10³–10⁴Hz), at room temperature, and temperature (30 °C–320 °C), at 10 kHz. Both the a.c. and d.c. conductivities have been studied over a wide range of temperature. The forbidden energy gap (E_g) and activation energy (E_a) of the compound were calculated from the plot of d.c. resistivity and a.c. conductivity versus inverse absolute temperature, respectively. The current density–field strength (J–E) characteristics of the compound studied at different temperatures reveals that the compound has excellent varistor behavior. The change in magnitude of the current with time was also studied at different voltage.     

Strain of concrete at peak compressive stress for a wide range of compressive strengths

The increasing interest in the strain behaviour of concrete is not restricted to everyday mean compressive strengths but now extends to very high values. In this paper it is shown that the various proposals for assessing the value ε₀ of the strain at the peak of the compressive strength of concrete appear sufficiently precise, at maximum, for a limited range of strengths, This had led us to estimate ε₀ for a wide range of strengths, and the new formula in this paper seems to perform much better when applied to the experimental data obtained in the very wide range of strengths possible today.

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Resume L'intérêt toujours croissant pour le comportement en déformation du béton ne se limite pas aux résistances moyennes en compression normales, mais il s'étend aussi aux valeurs de pointe atteignables aujourd'hui. Dans cet article, on montre que les différentes formules proposées pour l'évaluation de la valeur ε₀ de la déformation au pic de la résistance en compression du béton sont tout juste assez précises pour un éventail limité de résistances. Ceci nous a conduits à évaluer ε₀ pour un large éventail et la proposition nouvelle exposée ici offre une bien meilleure concordance avec les données expérimentales obtenues dans l'éventail de résistances le plus étendu à ce jour.

     

New TiNiSi-type RMgAg and RMgPd with R=Ca, Yb, and MgZn2-type Ca(Mg,Ag)2 compounds

The phases CaMgAg, YbMgAg, CaMgPd, and YbMgPd were synthesized by melting the constituent metals in sealed tantalum crucibles and by annealing at 1023 K. All the samples were homogeneous, and the crystallographic analysis, which was performed by powder and singlecrystal techniques, shows that the four compounds are isotypic and belong to the orthorhombic TiNiSi type. Magnetic measurements showed that YbMgAg and YbMgPd behave like Pauli paramagnets, according to the divalency of Yb in both phases. Within the Ca-Mg-Ag system, the existence range of the MgZn₂-type phases in the Mg-rich CaMg_2−x Ag _x pseudobinary system goes from CaMg₂ to CaMg_1.6Ag_0.4. Another stability region of the MgZn₂ structure occurs around the Ag-rich composition (Ca_0.94Mg_0.06)(Ag_1.60Mg_0.40), where magnesium replaces both the Ca and Ag atoms.     

Solid-state laser pumping with a planar compound parabolic concentrator

A novel solid-state laser-pumping scheme is proposed that combines a reflective lamp chamber and a compound parabolic concentrator (CPC) as a light guide. The CPC is made of a transparent material of high refractive index, and light is guided by the total internal reflection, with drastically reduced reflection losses. Material is chosen so that the absorption losses are minimized in the pumping wavelength range. The lamp chamber is designed with the principles of nonimaging optics, which ensures that the radiation is efficiently transferred from the lamp to the input aperture of the CPC. The pumping efficiency was first estimated theoretically, which gave us enough justification for the more accurate calculations with ray tracing. Single as well as multiple pumping cavities are discussed. New pumping geometry results in significantly increased pumping efficiency compared with conventional geometries. Also the lamp and the laser rod are separated, leading to reduced thermal load. We found that the proposed pumping method is also applicable to diode-pumped lasers.     

Authorship patterns in life sciences,preclinical basic and clinical research papers

The present paper examines the multiple authorship in research papers in biomedical sciences from the more basic aspects to clinically oriented research. Seventeen journals were chosen for analysis — nine from the general and life sciences categories and eight from medical sciences group with clinical orientation. All these were high impact journals as per the Science Citation Index and come in the top ten journals in their respective desciplines. The average authors/paper was significantly higher (P<0.001) in medical journals –4.299 (range 3.21–5.35) as compared to general biomedical journals –3.298 (range 3.21–5.35). Data from highly cited papers (1961–78) also indicate that papers in clinical sciences have higher average authors (2.71) as compared to preclinical basic research (2.25: P<0.26) and more basic research areas like biochemistry and molecular biology (2.208; P<0.02). The team size in research in clinical subjects is therefore appreciably larger as compared to basic biomedical sciences. Also the general and biomedical sciences articles were relatively longer (average 7.75 pages; range 2.69–10.07) as compared to medical papers with a clinical orientation (avarage 4.24 pages; range 1.80–12.92; P<0.001).     

Optimal Error Estimates of Two Mixed Finite Element Methods for Parabolic Integro-Differential Equations with Nonsmooth Initial Data

In the first part of this article, a new mixed method is proposed and analyzed for parabolic integro-differential equations (PIDE) with nonsmooth initial data. Compared to the standard mixed method for PIDE, the present method does not bank on a reformulation using a resolvent operator. Based on energy arguments combined with a repeated use of an integral operator and without using parabolic type duality technique, optimal $L^2$ L 2 -error estimates are derived for semidiscrete approximations, when the initial condition is in $L^2$ L 2 . Due to the presence of the integral term, it is, further, observed that a negative norm estimate plays a crucial role in our error analysis. Moreover, the proposed analysis follows the spirit of the proof techniques used in deriving optimal error estimates for finite element approximations to PIDE with smooth data and therefore, it unifies both the theories, i.e., one for smooth data and other for nonsmooth data. Finally, we extend the proposed analysis to the standard mixed method for PIDE with rough initial data and provide an optimal error estimate in $L^2,$ L 2 , which improves upon the results available in the literature.