Error propagation of the track model and track fitting strategy for the Iron CALorimeter detector in India-based neutrino observatory

A Kalman filter package has been developed for reconstructing muon (μ^±)$\left({\mu }^{\pm }\right)$ tracks (coming from the neutrino interactions) in ICAL detector. Here, we describe the algorithm of muon track fitting, with emphasis on the error propagation of the elements of Kalman state vector along the muon trajectory through dense materials and inhomogeneous magnetic field. The higher order correction terms are included for reconstructing muon tracks at large zenith angle θ$\theta$ (measured from the perpendicular to the detector planes). The performances of this algorithm and its limitations are discussed.     

Numerical Study of Compressible Mixing Layers Using High-Order WENO Schemes

This paper reports high resolution simulations using fifth-order weighted essentially non-oscillatory (WENO) schemes with a third-order TVD Runge-Kutta method to examine the features of turbulent mixing layers. The implementation of high-order WENO schemes for multi-species non-reacting Navier-Stokes (NS) solver has been validated through selective test problems. A comparative study of performance behavior of different WENO schemes has been made on a 2D spatially-evolving mixing layer interacting with oblique shock. The Bandwidth-optimized WENO scheme with total variation relative limiters is found to be less dissipative than the classical WENO scheme, but prone to exhibit some dispersion errors in relatively coarse meshes. Based on its accuracy and minimum dissipation error, the choice of this scheme has been made for the DNS studies of temporally-evolving mixing layers. The results are found in excellent agreement with the previous experimental and DNS data. The effect of density ratio is further investigated, reflecting earlier findings of the mixing growth-rate reduction.     

Volume holographic imaging in transmission geometry

We address the performance of transmission geometry volume holograms as depth-selective imaging elements. We consider two simple implementations using holograms recorded with spherical and plane beams. We derive the point-spread function (PSF) of these systems using volume diffraction theory and use the PSF to estimate depth resolution. Furthermore, we show that appropriately designed objective optics can significantly improve the depth resolution or the working distance of plane-wave reference holographic imaging systems. These results are confirmed experimentally and demonstrated for objects with millimeter axial features, imaged from the 5- to 50-cm range.     

Experimental and numerical study of heat transfer in horizontal concentric annulus containing phase change material

In the present research work, solid–liquid phase change heat transfer was studied experimentally as well as numerically for paraffin wax encapsulated in the annulus of two coaxial circular cylinders with variable heat flux. Two‐dimensional mathematical model (Navier–Stokes equation) in terms of primitive variables has been formulated to study the melting characteristics of the phase change material (PCM). The finite volume method (FVM) and semi‐implicit, that is, SIMPLE scheme are applied to discretise the governing equations and track the solid–liquid moving front. From the comparison of experimental data and numerical simulation, it is evident that the convective heat transfer is dominant in melting phase. From the computational results it is also observed that both eccentricity and the variation in the angle of inclination of the eccentricity plays an important role for the net circulation of the molten phase as well as the thermal flux at the inner surface of the annulus.     

Computational Studies on Mechanical and Thermal Properties of Carbon Nanotube Based Nanostructures

The excellent set of properties of carbon nanotube and carbon nanotube-based nanostructures has been established by various studies. However the claimed property values and trends have not been unanimously agreed upon. Using state of the art molecular dynamics and ab initio methods, we have extensively studied the mechanical, thermal and structural properties of carbon nanotubes and carbon nanotube based nanostructures. Additionally this study aims to address the approaches used in various studies to assess the validity and influence of various definitions used for determining the physical properties as reported in earlier experiments and theoretical calculations. We have come up with equations, which quantitatively address the wide differences in trend and values of nanotube axial modulus available across the literature. Applying a novel bond rearrangement scheme, we have found similar values in twist modulus of zigzag and armchair nanotubes. This opposes the claim of difference that was shown to be valid only at finite limit in our study. We have shown that the contribution of van der Waals energy in a multi-wall nanotube is powerful enough to make it hexagonal in shape but negligible in affecting the axial modulus. These insights will also help in designing micromechanics model of materials made from carbon nanotube or nanotube like structures. In particular, we have calculated the mechanical properties (young modulus, bending modulus and twist modulus) of isolated and bundled nanotubes, single and multi-wall nanotubes and single and multi-wall carbon nanotube based tori. We also report studies on thermal variation of moduli and thermal expansion of nanotubes. The result obtained by first principles calculation based interatomic potential agrees well with the experimental results.     

Wide Voltage Input Receiver with Hysteresis Characteristic to Reduce Input Signal Noise Effect

In this paper, an input receiver with a hysteresis characteristic that can work at voltage levels between 0.9 V and 5 V is proposed. The input receiver can be used as a wide voltage range Schmitt trigger also. At the same time, reliable circuit operation is ensured. According to the research findings, this is the first time a wide voltage range Schmitt trigger is being reported. The proposed circuit is compared with previously reported input receivers, and it is shown that the circuit has better noise immunity. The proposed input receiver ends the need for a separate Schmitt trigger and input buffer. The frequency of operation is also higher than that of the previously reported receiver. The circuit is simulated using HSPICE at 0.35‐μm standard thin oxide technology. Monte Carlo analysis is conducted at different process conditions, showing that the proposed circuit works well for different process conditions at different voltage levels of operation. A noise impulse of (V_CC/2) magnitude is added to the input voltage to show that the receiver receives the correct logic level even in the presence of noise. Here, V_CC is the fixed voltage supply of 3.3 V.     

Coarse grain modeling of polyimide copolymers

Addressing the wide span of timescales, where various important phenomena takes place in a polymer system, is inconceivable through a typical molecular dynamics simulation. Coarsening of simpler polymer systems has demonstrated significant potential in computationally characterizing and simulating systems at larger timescales. Addressing the need to extend existing coarsening methodologies on multifunctional materials to help design future generation materials is both promising and challenging. In this paper we present development of an atomistically informed coarse grain bead model of piezoelectric polyimide copolymers for large-scale simulations of thermal, mechanical and especially electrical properties. The coarsening approach generated a gain of two and a half orders of magnitude in terms of computational time and an order of magnitude gain in system size (equivalent to ∼ 360,000 atomistic model) while retaining the physical characteristics specific to the piezoelectric polymer. Reasonable agreement was observed between simulation results of the coarse grained and the atomistic model. Specifically mechanical moduli, density, dielectric constant, yield behavior, work hardening, response under dynamic loading and glass transition behavior were analyzed and compared.