Abstract

Synaptic integration is a prominent aspect of neuronal information processing. The detailed mechanisms that modulate synaptic inputs determine the computational properties of any given neuron. We study a simple model for the summation of excitatory inputs from synapses and illustrate its use by characterizing some functional properties of postsynaptic neurons. In this regard, we study the response of postsynaptic neurons as defined by the model to two well known noise driven processes: stochastic and coherence resonance. The model requires a small number of parameters and is especially useful to isolate the role of integration mechanisms that rely on summation of inputs with little dendritic processing.

Abstract

Surface codes are quantum error correcting codes normally defined on 2D arrays of qubits. In this paper, we introduce a surface code design based on the fact that the severity of bit flip and phase flip errors in the physical quantum systems is asymmetric. For our proposed surface code design for asymmetric error channels, we present pseudo-threshold and threshold values in the presence of various degrees of asymmetry of Pauli Xˆ, Yˆ , and Zˆ errors in a depolarization channel. We show that, compared to symmetric surface codes, our asymmetric surface codes can provide almost double the pseudo-threshold rates while requiring less than half the number of physical qubits in the presence of increasing asymmetry in the error channel. We also demonstrate that as the asymmetry of the surface code increases, the advantage in the pseudo-threshold rates begins to saturate for any degree of asymmetry in the channel. Keywords: Surface Codes, Quantum Error Correction, Quantum Computing

Abstract

In this paper, we develop a Kinetic Monte Carlo (KMC) based model to simulate the atomistic growth behavior of metallic nanoparticle in the solution of its ions and understand the growth pattern. KMC is used as it can model the growth of nanoparticle to the timescale comparable with that actual experiments. Energy minimas where metal atom can adsorb or surface diffuse have been found using Shrake–Rupley algorithm and conjugate gradient energy minimization algorithm. The rate of adsorption, desorption, and surface diffusion was artificially accelerated, and decelerated to observe different shapes. We demonstrate the model by a case study on growth of gold nanoparticles and find that shapes like the truncated octahedron, cuboctahedron, truncated cube, cube, rhombic dodecahedron, and sphere are seen to form by the model during the growth of NP. This KMC model provides a simplistic understanding of the mechanism and progression of shapes that may be seen during the growth of nanoparticle; these in turn may provide clues to synthesize NP of specific shapes.

Abstract

In recent times, quadrotors have become immensely applicable in scenarios such as relief operations, infrastructure maintenance, search-and-rescue missions etc. A key control design challenge arises in these applications when the quadrotor has to manoeuvre through constrained spaces such as narrow windows, pipelines in the presence of external disturbances and parametric uncertainties: such conditions necessitate the controller to guarantee predefined tracking accuracy so as to not violate the constraints and simultaneously tackle uncertainties. However, state-of-the-art controllers dealing with constrained system motion are not applicable either for an underactuated system like quadrotor or for an uncertain system dynamics. This work proposes a robust controller that enables the quadrotor to follow a trajectory with predefined tracking accuracy in constrained space as well as to tackle uncertainties stemming from imprecise system modelling and external disturbances. The closed-loop system stability is analysed via the Barrier Lyapunov approach and the effectiveness of the proposed controller is validated via simulation with state of the art.

Abstract

Recently leptoquarks (LQs) are receiving a lot of attention in the literature. Since they connect the quark and the lepton sectors of the Standard Model (SM), their phenomenology is interesting in general. However, the recent attention is mainly due to their ability to explain the long-standing anomalies observed in B-meson decays and the muon anomalous magnetic moment measurements (see, e.g., [1–34] for a few recent studies). Generally, the models explaining the anomalies contain LQs that couple with the third-generation quarks and leptons. This gives additional motivation to search for such LQs (commonly known as the third-generation LQs in the literature) at the Large Hadron Collider (LHC). Various strategies have already been applied in the searches for third-generation LQs at the LHC [

Abstract

The use of cell phones inside an aircraft is prohibited because cell phones pose a safety risk to aircraft systems and operations. Personal Electronic Device (PED) policies exist to avoid radio interference caused by the operation of cell phones in flight. The PED policies require passengers and crew members to stow away or use Airplane Mode when traveling by air. This paper focuses on studying the existing PED policies for the usage of cell phones inside an aircraft. We also study reports presenting technical data on why such a policy is required. We have also included individual experiences reported by passengers while travelling on how people react and behave when asked to turn on Airplane Mode or switch off their electronic devices. After establishing the problem, we discuss solutions that might switch off cell phones in flight or enable Airplane Mode automatically without any human intervention. We deliberate on three potential solutions (a) Mobile phone jammer, (b) Cellular Pico-cell onboard, (c) an Automatic Airplane Mode system. We propose creating an Automatic Airplane Mode System. We discuss various aspects of the proposed system, technical development choices and social features considerations. We discuss system development details and architecture along with the proposed uses of the system proposed. In the end, we conclude our work and list out some future scope activities.

Abstract

—Congestion in a network can cause several undesirable conditions such as packet loss, retransmission of packets, etc. There have been many variations of TCP for appropriate congestion control. These variations manage the sending rate of the users based upon the feedback they get from the network. In like manner, there are congestion control methods that take leverage of the Software Defined Networking and manage congestion from the controller. In this work we aim to manage congestion by coupling the activity of both the users and network controller in an SDN. We provide a utility based framework for a joint proactive and reactive mechanism for congestion control. We propose a system optimization function and show that our user and network congestion control methods optimize the system utility. Further, we simulate our model and show that our model significantly improves the system utility.

Abstract

The design, simulation, analysis, and measurement results of a spark gap switched dipole antenna with a pulse repetition frequency (PRF) of 100 Hz when excited with a double exponential pulse are reported. The spark gap is filled with hydrogen owing to its superior recovery rate. The theoretical analysis of such an antenna is also presented and the results obtained closely match the measured values. When a voltage of 144 kV p-p is input to the antenna, a peak radiated field of 20.4 kV/m was observed at 10 m. The corresponding figure of merit (FoM) of the proposed antenna computes to 1.42 which is higher than those in the literature. Index Terms— Figure of merit (FoM), high-power electromagnetic (HPEM), hydrogen spark gap switch dipole (H-SGSD), ultra-wideband (UWB).

Abstract

A comprehensive review paper concerning the geometry, topology, implementation methodology, feeding mechanisms and application domain of wideband and ultrawideband (UWB) antennas for high power applications is presented. Single element antennas, reflector based antennas and array type antennas developed across the globe are taken into account. The antennas considered here are grouped based on their similarity in structure and their performance is compared based on their mode of implementation. This information provides a guidance to the selection of different geometries for various applications especially in the applications pertaining to intentional electromagnetic interference(IEMI). Few antenna models were simulated in CST for the transient response to show their typical transient responses. An exhaustive comparative table is presented with the worldwide designs and some indigenous developments.

Abstract

Surface Temperature (ST) is important in terms of surface energy and terrestrial water balances affecting urban ecosystems. In this study, to process the nonlinear changes of climatological variables by leveraging the distinct advantages of Long Short-Term Memory (LSTM) and Bidirectional Long Short-Term Memory (BiLSTM), we propose an LSTM-BiLSTM hybrid deep learning model which extracts multi-dimension features of inputs, i.e., backward (future to past) or forward (past to future) to predict ST. This study assessed the climatological variables, i.e., wind speed, wind direction, relative humidity, dew point temperature, and atmospheric pressure impact on ST using five major coastal cities of India: Chennai, Mangalore, Visakhapatnam, Cuddalore, and Cochin. The Recurrent Neural Networks (RNN) and hybrid LSTM-BiLSTM models have effectively predicted ST and outperformed the standalone Artificial Neural Networks (ANN), LSTM, and BiLSTM models. The RNN and LSTM-BiLSTM models have performed better in predicting ST for Mangalore (Nash-Sutcliffe efficiency (NSE)¼0.91), followed by Cochin (NSE¼0.89), Chennai (NSE¼0.88), Cuddalore (NSE¼0.88), and Vishakhapatnam (NSE¼0.81). The hybrid data-driven modeling framework indicated that coupling the LSTM and BiLSTM models were proven effective in predicting the ST of coastal cities