Angular Bend Half Mode Substrate Integrated Waveguide (HMSIW) Based Band-Pass Filter with Multiple Transmission Zeroes

Wireless Personal Communications - Design methodology of 90° bend half mode substrate integrated waveguide (HMSIW) band pass filter (BPF) is presented in this paper. Edge wall reflections...     

Ultrafast Photo-Thermal Switching of Terahertz Spin Currents

Dissipationless and scattering-free spin-based terahertz electronics is the futuristic technology for energy-efficient information processing. Femtosecond light pulse provides an ideal pathway for exciting the ferromagnet (FM) out-of-equilibrium, causing ultrafast demagnetization and superdiffusive spin transport at sub-picosecond timescale, giving rise to transient terahertz radiation. Concomitantly, light pulses also deposit thermal energy at short timescales, suggesting the possibility of abrupt change in magnetic anisotropy of the FM that could cause ultrafast photo-thermal switching (PTS) of terahertz spin currents. Here, a single light pulse induced PTS of the terahertz spin current manifested through the phase reversal of the emitted terahertz photons is demonstrated. The switching of the transient spin current is due to the reversal of the magnetization state across the energy barrier of the FM layer. This demonstration opens a new paradigm for on-chip spintronic devices enabling ultralow-power hybrid electronics and photonics fueled by the interplay of charge, spin, thermal, and optical signals.     

Range‐free intersecting chord‐based geometric localization scheme for wireless sensor networks

Recent advancement in wireless sensor network has contributed greatly to the emerging of low‐cost, low‐powered sensor nodes. Even though deployment of large‐scale wireless sensor network became easier, as the power consumption rate of individual sensor nodes is restricted to prolong the battery lifetime of sensor nodes, hence the heavy computation capability is also restricted. Localization of an individual sensor node in a large‐scale geographic area is an integral part of collecting information captured by the sensor network. The Global Positioning System (GPS) is one of the most popular methods of localization of mobile terminals; however, the use of this technology in wireless sensor node greatly depletes battery life. Therefore, a novel idea is coined to use few GPS‐enabled sensor nodes, also known as anchor nodes, in the wireless sensor network in a well‐distributed manner. Distances between anchor nodes are measured, and various localization techniques utilize this information. A novel localization scheme Intersecting Chord‐Based Geometric Localization Scheme (ICBGLS) is proposed here, which loosely follows geometric constraint‐based algorithm. Simulation of the proposed scheme is carried out for various communication ranges, beacon broadcasting interval, and anchor node traversal techniques using Omnet++ framework along with INET framework. The performance of the proposed algorithm (ICBGLS), Ssu scheme, Xiao scheme, and Geometric Constraint‐Based (GCB) scheme is evaluated, and the result shows the fact that the proposed algorithm outperforms the existing localization algorithms in terms of average localization error. The proposed algorithm is executed in a real‐time indoor environment using Arduino Uno R3 and shows a significant reduction in average localization time than GCB scheme and similar to that of the SSU scheme and Xiao scheme.     

Effect of Ti Concentration on the Growth of Nb3Sn Between Solid Nb(Ti) and Liquid Sn

The change in the growth rate of the Nb₃Sn product phase because of Ti addition is studied for solid Nb(Ti)–liquid Sn interactions. The growth rate increased from no Ti to 1 at.% and 2 at.% of Ti in Nb, and the activation energy decreased from 221 kJ/mol to 146 kJ/mol. Based on the estimated values, the role of grain boundary and lattice diffusion is discussed in light of the possibility of increased grain boundary area and point defects such as antisites and vacancies.     

Synthesis of linear array using Taylor distribution and Particle Swarm Optimisation

In this article, non-uniformly excited linear arrays are optimised using Taylor distribution and classical particle swarm optimisation (CPSO) algorithm for obtaining desired equal side lobe level (SLL). Elements of the array are considered to be isotropic in nature with uniform interelement spacing. Excitation amplitudes of each element are taken as optimisation parameters. Taylor distribution defines the range of excitation amplitude in which CPSO algorithm searches for the optimum value of excitation amplitude, with the objective of obtaining desired equal SLL. The proposed method eliminates the initial randomness of defining search space for CPSO algorithm. Comparison with other methods has been made whenever possible. The results reveal that the proposed method can be used to obtain the desired SLL.     

Comparison of p–n junction formed by BF2 and B implantation in silicon microstrip detector with low and high thermal budget: impact of fluorine on electrical characteristics

The influence of crystal damage on the electrical properties and the doping profile of the implanted p⁺–n junction has been studied at different annealing temperatures using process simulator TMA-SUPREM4. This was done by carrying out two different implantations; one with implantation dose of 10¹⁵ BF₂⁺ ions/cm² at an energy of 80 keV and other with 10¹⁵ B⁺ ions/cm² at 17.93 keV. Substrate orientation 1 1 1 of phosphorus-doped n-type Si wafers of resistivity 4 kΩ cm and tilt 7° was used, and isochronally annealing was performed in N₂ ambient for 180 min in temperature range between 400°C and 1350°C. The diode properties were analysed in terms of junction depth, sheet resistance. It has been found that for low thermal budget annealing, boron diffusion depth is insensitive to the variation in annealing temperature for BF₂⁺-implanted devices, whereas, boron diffusion depth increases continuously for B⁺-implanted devices. In BF₂⁺-implanted devices, fluorine diffusion improves the breakdown voltage of the silicon microstrip detector for annealing temperature upto 900°C.For high thermal budget annealing, it has been shown that the electrical characteristics of BF₂⁺-implanted devices is similar to that obtained in B⁺-implanted devices.     

Analysis of Performance of BPSK in an Additive Combination of Impulsive and Gaussian Noise

We analyze the bit error rate (BER) performance ofa correlation receiver subject to impulsive plusGaussian noisewith coherent binary phase-shift keying (BPSK). The impulsive component of the noise is assumed to be due torandom occurrences of impulses following a Poisson arrival process.Using the moments of theimpulsive component, aseries expression for the BERis derived by a Taylor's series approach. From this expression, approximate formulae for extreme valuesof signal-to-noise ratio (SNR) and impulse arrival rate (IAR)are obtained. Numerical results show thatwhen the square root raisedcosine pulse is used, (1) the BER performance improves with increaseof the rolloff factor, but the improvement becomes more significantwith decrease of the Gaussian-to-total noise ratioor increase of the IAR,(2) as the rolloff factor increases, a decrease of the IARdegrades the BER performance for low SNRs, but improves it for high SNRs.     

Functionalized Cubic Mesoporous Silica as a Non‐Chemodosimetric Fluorescence Probe and Adsorbent for Selective Detection and Removal of Bisulfite Anions along with Toxic Metal Ions

Dual signaling and remediation systems for detection and adsorption of toxic analytes have gained more attention over sensory probes only. However, most of the sensors for bisulfites are chemodosimetric probes, which are irreversible and having drawbacks of absolute selectivity, recyclability, and solubility in a pure aqueous system. To address above drawbacks a new non‐chemodosimetric probe material with a strong hydrogen bonding pocket for bisulfites is developed. Synthesis of cubic mesoporous silica by a modified Stober process followed by functionalization with 2,2′‐(((((3‐(triethoxysilyl)propyl)azanediyl)bis(methylene))bis(2,1‐phenylene))bis(oxy))bis(N‐(4‐((E)‐phenyldiazenyl)phenyl)acetamide) (AZOL) has given a fluorogenic silica probe material SiO₂@AZOL. This material shows selectivity toward bisulfite anion (limit of detection (LOD): 64 ppb) and Hg²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ cations (LOD: 126, 95, 14, and 27 ppb, respectively) among various analytes. The adsorption studies for these toxic analytes (HSO₃ ^?, Hg²⁺, Cd²⁺, Cu²⁺, and Zn²⁺) show an extraction efficiency of around 99% and adsorption capacities of 873, 630, 633, 260, and 412 mg g^?1, respectively. Spectroscopic studies along with adsorption, striping, and regeneration studies reveal that this material is a recyclable sensory cum adsorbent material for these toxic analytes. Moreover, this material can be used as a sensitive probe material for determination of HSO₃ ^? levels in various sugar samples.     

Studies on the properties of glass fiber reinforced epoxy composites of DGEBA / epoxidized polyhydric alcohols with or without fortifier

Differential scanning calorimetry (DSC) technique was used to study the curing reaction of diglycidyl ether of bisphenol A (DGEBA) resin and different di- and trifunctional polyhydric alcohols with phthalic anhydride as curing agent and triethylamine as catalyst with or without fortifier. The thermal stability of the cured products was also studied by thermogravimetric analysis (TGA). Using these data, different glass fiber reinforced epoxy composites were fabricated and their mechanical and electrical properties and their resistance to chemicals were studied as well. Activation energies of curing reactions range within 75.1 to 88.3 kJ mol^?1. The cured products have good thermal stability; the composites have good mechanical strength, electrical insulation properties and chemical resistance. 36 to 53% improvement in flexural strength has been observed when fortifier was added to the DGEBA-diluent systems.     

Study of combined effect of natural convection and radiation heat transfer from annular finned vertical cylinder

The present numerical study reports the combined effect of natural convection and radiation heat from a vertical cylinder with annular fins. The study involves simulation for laminar as well as turbulent regimes. For the present study, Rayleigh's number is varied in the range ${10}^8-{10}^{12}$, emissivity in the range $0.2-0.8$, and the fin spacing ratio (s/d) in the range $0.1-10$. The radiation heat transfer has been found to share a considerable amount in the total heat transfer of the system for the laminar regime, but in the turbulent regime, its effect is minimal and can be neglected. When the fin spacing ratio is reduced, the total heat transfer increases for both the turbulent and laminar flow conditions. But the radiation heat increases with a reduction in fin spacing ratio for laminar and in case of turbulent flow radiation heat rate reduces with a reduction in s/d ratio. For the range of Rayleigh numbers considered in the present study, the Nusselt number increases with the increment of the fin spacing ratio. Thus, it can be concluded that there is a remarkable enhancement in the heat transfer rate in laminar cases with the fins. For turbulent cases, the fin efficiency lies between 40% and 50%.