Efficient Red Downshifting in Layered Structure: A Broad Spectral Converter for Enhancing Photo-response of Solar Cell

Spectral convertors are promising materials for solar cells as they engineered the band gap necessary for suppressing the losses. Existing spectral convertors have small stokes shift which exerts re-absorption losses due to the overlap of spectrum and limits light catching ability. Here we present large stoke shift chromium doped rhombohedral Al₂O₃: Cr³⁺ as a spectral convertor from UV–VIS to red region as single doped with maximum coverage of solar spectrum in UV region. The large stoke shifts in red region around 694 nm originate from ²E_g to ⁴A_2g and broad absorption originates from \(^{{\text{4}}}{{\text{A}}_{{\text{2g}}}}{ \to ^{\text{4}}}{{\text{T}}_{{\text{1g}}}},{{\text{ }}^{\text{4}}}{{\text{A}}_{{\text{2g}}}}{ \to ^{\text{4}}}{{\text{T}}_{{\text{2g}}}}\). This broad absorption (300–600 nm) and large stokes shift emission at 694 nm suggest that the Cr³⁺ dopant rhombohedral Al₂O₃ is well suited as spectral convertors for enhancing the efficiency of the solar cell through better matching of spectral response with spectral distribution of light striking on the solar cell.     

The effect of orientation of various phenols on the degradation kinetics of blends of resole and epoxy

Resoles were prepared separately with different phenols, with formaldehyde having phenol‐to‐formaldehyde mole ratio of 1:2 in basic medium at 70°C. These resoles were physically blended with different weight percentages of diglycidyl ether of bisphenol‐A (DGEBA)–epoxy resin. The blends were cured with 40, 50, and 60 wt % polyamide (based on total amount of the blended resin). Decomposition kinetics of blend sample was studied by dynamic thermogravimetric (TG) analysis. It was found that the degradation of most of the blend samples followed two‐step second‐order degradation kinetics with 50 wt % polyamide and varied reaction orders with 40 and 60 wt % polyamide and type of phenols used in the resole. The energy of activation (E) was found to be maximum with the blend system containing p‐cresolic resole and epoxy. The value of preexponential factor (Z) decreased when phenolic resole was changed to p‐cresolic resole in the blend. Also, the plotted values of E and Z were found to be in close resemblance with those obtained from calculated values. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4171–4176, 2006     

Review:Botnet detection techniques: review,future trends,and issue

In recent years, the Internet has enabled access to widespread remote services in the distributed computing environment; however, integrity of data transmission in the distributed computing platform is hindered by a number of security issues. For instance, the botnet phenomenon is a prominent threat to Internet security, including the threat of malicious codes. The botnet phenomenon supports a wide range of criminal activities, including distributed denial of service(DDoS) attacks, click fraud, phishing, malware distribution, spam emails, and building machines for illegitimate exchange of information/materials. Therefore, it is imperative to design and develop a robust mechanism for improving the botnet detection, analysis, and removal process. Currently, botnet detection techniques have been reviewed in different ways; however, such studies are limited in scope and lack discussions on the latest botnet detection techniques. This paper presents a comprehensive review of the latest state-of-the-art techniques for botnet detection and figures out the trends of previous and current research. It provides a thematic taxonomy for the classification of botnet detection techniques and highlights the implications and critical aspects by qualitatively analyzing such techniques. Related to our comprehensive review, we highlight future directions for improving the schemes that broadly span the entire botnet detection research field and identify the persistent and prominent research challenges that remain open.     

Performance Analysis of Combined Space Time Block Coding with Generalized Selection Combining in Underlay Cognitive Radio

Wireless Personal Communications - In this paper, we demonstrate the performance analysis of an underlay MIMO cognitive radios employing space time block coding at secondary’s user...     

Preparation and Characterization of Ni0.5Zn0.5Fe2O4 + Polyurethane Nanocomposites Using Melt Mixing Method

Silicon - In this study, nanocomposites of Ni0.5Zn0.5Fe2O4/polyurethane were prepared by melt mixing method and determined the influence of amount of Ni0.5Zn0.5Fe2O4 (0, 0.5, 1, 2, and 3 wt%)...     

Investigation of age-differentiated spatial semantic elaboration strategies for communicating route instructions

This paper investigates the effect of spatial semantic elaboration strategies on young and older participants’ performance and preferences in a route drawing task where participants read route instructions and then drew the route on a map. In particular, an elaborated form of spatial perspective that communicated the route instruction in both egocentric and allocentric perspectives was compared against just the egocentric or allocentric perspective instructions individually. Additionally, route instruction granularity was varied to compare elaborated hierarchical instructions that communicated goal and landmark information with flat instructions. The results of the experiment showed that older participants performed best with least confusion in the allocentric perspective with flat granularity, but that they benefited from semantic elaboration when less optimal spatial strategies were used, unlike young participants who performed best with the mixed (i.e. elaborated) perspective and flat granularity. The experiment showed that older participants actually suffered from what might be information overload when excess semantic elaboration was provided, as was likely the case with the use of the mixed perspective, which confused them considerably. In addition, hierarchical granularity was only beneficial in confusing spatial perspectives, while it detracted from older participants’ performance in their optimal perspective, showing that there is a fine balance to be struck between beneficial semantic elaboration and information overload.