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1.
Penmatsa Krishna Kanth Varma Nagesh Kallollu Narayanaswamy 《International Journal of Communication Systems》2023,36(8):e5460
This communication presents a compact field de-correlation lines integrated dual band with dual-polarized (LP & CP) multiple-input multiple-output (MIMO) antenna for the fifth generation (5G) sub-6-GHz wireless communication systems. Dual working bandwidths, smaller interelement gaps, and superior isolation within the MIMO components are the distinguishing characteristics that give the proposed MIMO system an aspect of novelty. The modeled MIMO antenna has compact configurations of 20 × 21 × 0.8 mm3. The unit cell consists of a microstrip feed line with optimized rectangular slots branches etched from the radiated patch. The MIMO module is generated by the antiparallel replication of a single unit cell. To enhance the isolation, two rectangular slots are incorporated on the patch between the unit elements, which act as field de-correlation lines. The MIMO identity is supported by diversity performance calculations in terms of ECC, DG, and TARC. Simulated and measured counterparts are found in the agreement. 相似文献
2.
V. S. Vendamani Syed Hamad V. Saikiran A. P. Pathak S. Venugopal Rao V. V. Ravi Kanth Kumar S. V. S. Nageswara Rao 《Journal of Materials Science》2015,50(4):1666-1672
We report a detailed study on the synthesis of ultra-small (1–10 nm) colloidal silicon nanoparticles (Si NPs) by ablating porous silicon (pSi) in acetone using femtosecond laser pulses. Porous silicon is considered as a target material for ablation because it contains a large number of light emitting silicon nanoparticles. The pSi samples were prepared by anodic etching of silicon in aqueous HF solution for different etching current densities. Transmission electron microscope measurements confirmed the successful formation of well-isolated spherical silicon nanoparticles. The average size of spherical NPs were estimated to be ~7.6, ~7, and ~6 nm when anodic etching current densities of 5, 10, and 20 mA/cm2 were used respectively for preparing pSi targets. The crystallinity of these Si NPs was confirmed by selective area electron diffraction and Raman spectroscopy measurements. The observed blue shift in the absorption and emission spectra are attributed to reduction in the average particle size with increase in etching current density. These Si NPs may be useful for fabricating low-dimensional microelectronic compatible photonic devices. 相似文献
3.
Govindarajan Muralidharan Kanth Kurumaddali Andrew K. Kercher Larry Walker Scott G. Leslie 《Journal of Electronic Materials》2013,42(2):240-248
There is a need for next-generation, high-performance power electronic packages and systems utilizing wide-band-gap devices to operate at high temperatures in automotive and electricity transmission applications. Sn-3.5Ag solder is a candidate for use in such packages with potential maximum operating temperatures of about 200°C. However, there is a need to understand the thermal cycling reliability of Sn-3.5Ag solders subject to such high-temperature operating conditions. The results of a study on the damage evolution occurring in large-area Sn-3.5Ag solder joints between silicon dies and direct bonded copper substrates with Au/Ni-P metallization subject to thermal cycling between 200°C and 5°C are presented in this paper. Interface structure evolution and damage accumulation were followed using high-resolution X-ray radiography, cross-sectional optical and scanning electron microscopies, and X-ray microanalysis in these joints for up to 3000 thermal cycles. Optical and scanning electron microscopy results showed that the stresses introduced by the thermal cycling result in cracking and delamination at the copper–intermetallic compound interface. X-ray microanalysis showed that stresses due to thermal cycling resulted in physical cracking and breakdown of the Ni-P barrier layer, facilitating Cu-Sn interdiffusion. This interdiffusion resulted in the formation of Cu-Sn intermetallic compounds underneath the Ni-P layer, subsequently leading to delamination between the Ni-rich layer and Cu-Sn intermetallic compounds. 相似文献
4.
K. Somaiah K. Ravi Kanth V. Dayakar K. Radhakrishna Rao P. Veeresham 《Materials Chemistry and Physics》2001,70(3):259-262
Thermally stimulated luminescence (TSL) of Na2ZnCl4 single crystals showed three glow peaks having their peak maxima at 343, 425 and 475 K. Optical absorption (OA) data of unirradiated samples revealed an absorption band at 272 nm while X-irradiation caused additional bands at 462 and 723 nm. Growth and room temperature annealing studies of TSL and OA supported the idea of attribution of 425 K glow peak and 462 nm absorption band to F-centres. The 272 nm OA band is due to Zn2+ centres whereas the 723 nm absorption band and 475 K glow peak have been assigned to Zn+ centres. 相似文献
5.
The photoluminescence (PL) properties of singly doped (Dy3+) and codoped (Dy3+, Eu3+) fluoroaluminoborate glasses, with an emphasis on the white light generation, are studied. The γ-irradiation led to the formation of defects in Dy3+-doped glasses and photoreduction of Eu3+ to Eu2+ in codoped (Dy3+, Eu3+) glasses. The electron paramagnetic resonance spectra confirm the presence of divalent europium ions and defects in Dy3+, Dy3+–Eu3+-doped glasses. The FTIR spectra mainly establish the compaction of glass network due to γ-irradiation. From the PL spectra, the intensity ratio of Dy3+ emission bands yellow to blue (4F9/2–6H13/2/4F9/2–6H15/2) defines the site symmetry, covalency, and feasibility of extracting white light. The existence of an energy transfer (ET) from Dy3+ to Eu3+ ions are established due to the decrease in intensity of Dy3+ peaks with an increase of Eu2O3 content. Moreover, the non-exponential nature of decay curves was well fitted with the generalization of Yokota–Tanimoto model for electric dipole-quadrupole (S = 8) interaction that is responsible for ET process from sensitizer (Dy3+) to activator (Eu3+). 相似文献
6.
This paper proposes a method to evaluate the design response of a non-classically damped coupled primary-secondary system by statistically incorporating the effects of uncertainties in modal properties of its constituent uncoupled systems. Within the framework for the coupled system seismic analysis, the uncertainties can be accounted for by modeling the uncoupled modal properties of primary and secondary systems as random variables. Gupta and Choi (2005) proposed the Square-Root-of-Mean-of-Squares (SRMS) method which employs a limited Monte Carlo simulation to evaluate the design response of the secondary system statistically. The SRMS approach was illustrated to work well with representative single degree of freedom (SDOF) primary-SDOF secondary systems. In this paper, we study the applicability of SRMS methodology to MDOF primary-MDOF secondary systems. In such systems, two or more modes are likely to have closely spaced frequencies. The individual probability density functions of the closely spaced frequencies overlap with each other. Simulation of such closely spaced frequencies as independent random can give incorrect set of frequencies in the sense that the frequencies do not remain as ordered sets. Rejection of these incorrect sets does not resolve the problem as the simulated density functions no longer maintain the originally assumed distribution. The simulation of ordered sets of natural frequencies of an MDOF structure can be achieved by using a joint density function that considers the necessary constraints. The SRMS method for MDOF primary-MDOF secondary coupled systems is modified by incorporating a closed-form formulation for the joint density function of closely spaced frequencies. The modified SRMS approach is validated for MDOF secondary systems that are both singly as well as multiply connected to the MDOF primary system. 相似文献
7.
Rama Kanth Rao M. G. Krishna S. H. Zaheer L. K. Arnold 《Journal of the American Oil Chemists' Society》1955,32(7):420-423
Summary Solubilities of cottonseed, peanut, sesame, and soybean oils in aqueous alcoholic solutions at various temperatures were determined
directly. Solubility curves for the four oils in aqueous alcoholic solutions are presented.
The critical solution temperaturesversus alcoholic concentrations data have been plotted and are in complete agreement with the previously published data of Japanese
workers in each case. It is observed that the critical solution temperature increases with the moisture content of the alcohol,
and in each case the relationship is linear. The pressure in the system also varies directly with the temperature, the maximum
being approximately 20 p.s.i.g. 相似文献
8.
9.
In this paper, coupled nonlinear equations governing the flow for magnetoconvection in a vertical channel for open and short circuits are solved. The calculations are carried out by using differential transformation method (DTM) which is a semi‐numerical–analytical solution technique. By using DTM, the nonlinear constrained governing equations are reduced to recurrence relations and related initial conditions are transformed into a set of algebraic equations. The principle of differential transformation is briefly introduced, and then applied for the aforementioned problems. The current results are then compared with those derived from the finite difference method (FDM) and perturbation method (PM) in order to verify the accuracy of the proposed method. The findings reveal that the DTM can achieve more suitable results in predicting the solution of such problems. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.21035 相似文献
10.
Richa Pandey Ross A. Kerner S. Matthew Menke James Holst Kanth V.B. Josyula Russell J. Holmes 《Organic Electronics》2013,14(3):804-808
In this work, we examine the optical properties of tin naphthalocyanine dichloride (SnNcCl2), and its performance as an electron donor material in organic photovoltaic cells (OPVs). As an active material, SnNcCl2 is attractive for its narrow energy gap which facilitates optical absorption past a wavelength of λ = 1100 nm. We demonstrate a power conversion efficiency of ηP = (1.2 ± 0.1)% under simulated AM1.5G solar illumination at 100 mW/cm2 using the electron donor–acceptor pairing of SnNcCl2 and C60 in a bilayer device architecture. While some phthalocyanines have been previously used to improve infrared absorption, this is often realized through the formation of molecular dimers. In SnNcCl2, the infrared absorption is intrinsic to the molecule, arising as a result of the extended conjugation. Consequently, it is expected that SnNcCl2 could be utilized in bulk heterojunction OPVs without sacrificing infrared absorption. 相似文献