Distributed Temperature Sensing using a SPIRAL Configuration UltrasonicWaveguide

Distributed temperature sensing has important applications in the long term monitoring of critical enclosures such as containment vessels, flue gas stacks, furnaces, underground storage tanks and buildings for fire risk. This paper presents novel techniques for such measurements, using wire in a spiral configuration and having special embodiments such a notch for obtaining wave reflections from desired locations. Transduction is performed using commercially available Piezo-electric crystal that is bonded to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes were employed. Time of fight (TOF) differences between predefined reflectors located on the waveguides are used to infer temperature profile in a chamber with temperature gradients. Both L(0,1) and T(0,1) wave modes were generated and the pros and cons of these two modes are highlighted.The ultrasonic measurements were compared with commercially available thermocouples

Connecting sensors to LTE

The number of sensors that will be connected to the internet is expected to grow exponentially in the near future. As sensors are starting to get used for more and more applications, a large number of them will be placed in locations where wireless networks, such as Long Term Evolution (LTE), are the only available method of connectivity. Examples of such locations include remote areas (e.g. for Smartgrid and agricultural applications), and inhospitable environments (e.g. for industrial applications). Unfortunately, these wireless networks have not been designed for low power constrained devices, like battery operated sensors, and the procedures for attaching and staying connected to such networks would consume significant amounts of energy. Due to this increased power consumption the battery life on these devices would be too low to be useful. In addition to this due to the always-connected nature of the devices, the wireless network will quickly run out of resources when large numbers of sensors get connected. The resources include radio spectrum (that is extremely limited and prohibitively expensive) and signaling capacity on the network nodes. This thesis describes a new connection paradigm for connecting sensors to LTE networks along with the necessary wireless signaling changes that will allow for a battery life of the sensor to be at least 10 fold than that using the current mechanisms. This will enable the sensors to be placed in more applications where battery replacement cycles are very long and the battery replacement costs are very expensive. The new signaling mechanism will also conserve scarce resources in the wireless network so that the wireless network can scale to handle 10 fold more connections than today’s wireless networks

Controllability of nonlinear fractional Langevin delay systems

In this paper, we discuss the controllability of fractional Langevin delay dynamical systems represented by the fractional delay differential equations of order 0 < α,β ≤ 1. Necessary and sufficient conditions for the controllability of linear fractional Langevin delay dynamical system are obtained by using the Grammian matrix. Sufficient conditions for the controllability of the nonlinear delay dynamical systems are established by using the Schauders fixed-point theorem. The problem of controllability of linear and nonlinear fractional Langevin delay dynamical systems with multiple delays and distributed delays in control are studied by using the same technique. Examples are provided to illustrate the theory

FluTO: Graded Multiscale Fluid Topology Optimization using Neural Networks

Fluid-flow devices with low dissipation, but high contact area, are of importance in many applications. A well-known strategy to design such devices is multi-scale topology optimization (MTO), where optimal microstructures are designed within each cell of a discretized domain. Unfortunately, MTO is computationally very expensive since one must perform homogenization of the evolving microstructures, during each step of the homogenization process. As an alternate, we propose here a graded multiscale topology optimization (GMTO) for designing fluid-flow devices. In the proposed method, several pre-selected but size-parameterized and orientable microstructures are used to fill the domain optimally. GMTO significantly reduces the computation while retaining many of the benefits of MTO. In particular, GMTO is implemented here using a neural-network (NN) since: (1) homogenization can be performed off-line, and used by the NN during optimization, (2) it enables continuous switching between microstructures during optimization, (3) the number of design variables and computational effort is independent of number of microstructure used, and, (4) it supports automatic differentiation, thereby eliminating manual sensitivity analysis. Several numerical results are presented to illustrate the proposed framework

Effect of Energetic Materials on Thermal Decomposition of Phase-Stabilised Ammonium Nitrate - An Eco-Friendly Oxidiser

Phase-stabilised ammonium nitrate (PSAN) was prepared by incorporating copper (II) diamine nitrate in the ammonium nitrate (AN) crystal lattice, thereby avoiding the abrupt volume change within the useful temperature range. The effect of RDX on the thermal decomposition of PSAN has been investigated. Decomposition temperatures of PSAN and RDX are almost in the same temperature range. The synergetic effect of the interaction between PSAN and RDX resulted in a net exothermic reaction of PSAN. The kinetic and thermodynamic parameters of the exothermic decomposition have been computed. Two well-known equations based on variable programme heating rate method, viz., Kissinger and Ozawa equations were employed for the kinetic evaluation. The approximate activation energy obtained from Ozawa method was refined by an iteration procedure using the two-term approximation for Arrhenius temperature integral, p(x) and the refinement was found to be unwarranted for the reaction. There is a close agreement between the values of kinetic parameters of the exothermic reaction of PSAN and RDX obtained from the Kissinger and Ozawa methods.