A nano-plasmonic HMIM waveguide based concurrent dual-band BPF using circular ring resonator

This article analyzes the transmission line characteristics of plasmonic hybrid metal insulator metal (HMIM) waveguide, circular ring resonator (CRR) based dual-band band-pass filters with two transmission poles in both pass-bands in the optical regime using coupled line feed. The transmission line characteristics of an HMIM waveguide, such as characteristic impedance (ZPV), effective refractive index (neff) and propagation length (Lspp), have been obtained by using full wave simulation. Using basic HMIM slot waveguide, a CRR with periodic loading of double- and triple-ring CRR is numerically analyzed. Two input ports have been used for excitation, which are located at the separation of 180° positions along the CRR, and are coupled with the ring by parallel coupled lines, producing the dual pass-bands with the synchronous excitation of two transmission poles. The proposed double-ring dual-band band-pass filter (DR-DB-BPF) offers 35 dB extinction ratio (ER), 299.69 nm free spectral range (FSR) and narrow band full width half maximum (FWHM) of 78.057—112.43 nm. The triple-ring DB-BPF (TR-DB-BPF) has 22.5 dB ER, FSR of 292.18 nm and FWHM of 42.751—59.58 nm. The proposed filters are very useful in the development of dual-band filters for electronic photonic integrated circuits (EPICs), as the optical signals are filtered at two wavelengths simultaneously.     

Design of compact two-port dual-band dual-polarized MIMO antenna for CBRS and WLAN sub-6-GHz applications

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.     

KERNEL: Enabler to build smart surrogates for online optimization and knowledge discovery

KERNEL – A novel parameter-free surrogate building algorithm using Adaptive Neuro Fuzzy Inference System (ANFIS) is presented to provide an intelligent and robust technology to optimally estimate the configuration of ANFIS along with Sobol-based fast sample size determination (SSD) methodology. The proposed algorithm is capable of fine-tuning the existing knowledge base about the physics of the process in terms of human experience. It also enables knowledge discovery through a multi-objective optimization problem (MOOP) solved by non-dominated sorting genetic algorithm, NSGA-II, thus presenting machine-invented physics of the process. Experimentally validated polymerization reaction network model is considered and ANFIS surrogates are built using KERNEL. Surrogate-based optimization was found to be nine times faster than conventional optimization using the time expensive model, thus enabling its online implementation. Comparison of ANFIS with Kriging is also included.     

Synthesis of ultra-small silicon nanoparticles by femtosecond laser ablation of porous silicon

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.     

An X-ray Radiography Study of the Effect of Thermal Cycling on Damage Evolution in Large-Area Sn-3.5Ag Solder Joints

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.     

Colour centres and thermally stimulated luminescence of Na2ZnCl4

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.     

Consideration of uncertainties in seismic analysis of non-classically damped coupled systems

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.     

Photoluminescence properties and energy transfer in γ-irradiated Dy3+, Eu3+-codoped fluoroaluminoborate glasses

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 (⁴F_9/2–⁶H_13/2/⁴F_9/2–⁶H_15/2) 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⁺).     

Alcoholic extraction of vegetable oils. I. Solubilities of cottonseed,peanut, sesame,and soybean oils in aqueous ethanol

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.