Structural health monitoring of railway tracks using IoT-based multi-robot system

Neural Computing and Applications - A multi-robot-based fault detection system for railway tracks is proposed to eliminate manual human visual inspection. A hardware prototype is designed to...     

Design of high-speed data transfer turbo code for body channel communication transceivers

In this work, a digital differential transmitter based on low-power wireless compensation transceiver for body channel communication (BCC) is proposed. Further, the proposed transceiver is composed of Touch Status Detection Unit (TSDU), Wireless Status Compensation Unit (WSCU), and a reconfigurable preamplifier. Initially, the human body channel environment for wireless communication is investigated based on properties from 1 to 100 MHz. Further, the turbo code-based encoding scheme is used to encode the data before transferring the data on the transmitter side. Also, the proposed error-correcting parallel turbo decoder using a modified step-by-step algorithm is presented. The turbo code-based decoding scheme is used to recover the error-free transmitted data at the receiver side. Results demonstrate that the proposed BCC transceiver is designed using 90 nm CMOS technology and it is observed that the proposed BCC transceiver has utilized an area of 600mm². Also, the maximum data rate achieved by a proposed BCC transceiver was 100 Mbps, and the overall transceiver power consumption is 0.42 mW, and energy for communication is 0.02 nj/b.     

On the Design of Link-State Routing Protocol for Connection-Oriented Networks

Link-state routing protocols are being increasingly used in modern communications networks. A salient feature of this class of routing protocols is that network connectivity and state information of all links are available to nodes for making routing decision. Two main components of a link-state routing protocol are an update mechanism and a routing algorithm. These components must be properly designed for efficient routing. Various alternatives are possible for each of these components leading to different scenarios for routing protocol. In this paper, we quantitatively examine the impact of these alternatives on network performance using call-by-call simulations. Our design objective is to reduce call blocking ratio without significantly increasing routing overhead. We also present a new signaling scheme that can be used in conjunction with link-state protocols. We show that, if properly designed, this scheme can enhance the network performance.     

Novel Ultrahigh-Energy Materials

This paper reviews the recent work carried out in the field of modern high-energy materials (HEMs) with the emphasis on homoleptic polynitrogen compounds. A large volume of quantum-chemical investigations have predicted the possibility of existence of polynitrogen compounds not only as short-lived transient species but also in the form of isolable discrete molecules. Despite the theoretical speculations, only a few polynitrogen ions are known today in addition to well-entrenched N _1– ³ discovered almost 100 year ago. Extraordinary potential of these green molecules to deliver high amounts of energy in comparison with todays and tomorrows most powerful HEMs, namely, hexanitrohexaazaisowurtzitane (CL-20) and octanitrocubane (ONC), has fuelled the imagination of propellant and explosive engineers and technologists. Research activities are in progress in many quantum-chemical schools to explore the possibility of other promising polynitrogen compounds. After the recent discovery of key synthons/building blocks Mg(N₅)₂, N ₁₊ ⁵ SbF _1– ⁶ , N ₁₊ ⁵ SbF₁₁, N ₁₊ ⁵ , N ₁₊ ⁵ SnF₆, and N ₁₊ ⁵ Sn(CF₃)₄, the wealth of polynitrogen compounds is just waiting to be harvested by the HEMs community. There are ambitious plans all over the globe to realize N₆₀, which only prove a eco-friendly dense powerhouse of energy.__________Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 3, pp. 29–45, May–June, 2005.     

Thermal, mechanical and vibration characteristics of epoxy-clay nanocomposites

Diglycidyl ether of bisphenol-A (DGEBA) epoxy resin system filled individually with organoclay (OC) and unmodified clay (UC) were synthesized by mechanical shear mixing with the addition of diamino-diphenylmethane (DDM) hardener. The unmodified clay used was Na⁺-Montmorillonite (MMT) and the organoclay was alkyl ammonium treated MMT clay. The reinforcement effect of OC and UC in the epoxy polymer on thermal, mechanical and vibration properties were studied. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) were used to study the structure and morphology of nanocomposites. Curing study shows that the addition of OC in epoxy resin aids the polymerization by catalytic effect, and UC addition does not show any effect in the curing behavior of epoxy polymer. Thermogravimetry analysis (TGA) shows enhanced thermal stability for epoxy with OC fillers than that of epoxy with UC fillers. The epoxy with OC fillers shows considerable improvement on tensile and impact properties over pure epoxy polymer and epoxy with UC fillers. The improvement in tensile and impact properties of nanocomposites is supported with the fracture surface studies. Epoxy with OC fillers shows enhanced vibration characteristics than that of the pure epoxy polymer and epoxy with UC fillers.     

Corrosion of carbon steel feeders during dilute chemical decontamination of primary heat transport system of PHWRs

Carbon steel feeders in the primary heat transport system of pressurized heavy water reactors (PHWRs) show significant wall thinning due to flow accelerated corrosion (FAC). This is of great concern, as the wear rate in certain locations exceeds the corrosion allowance by design. This necessitates periodic measurement of wall thickness and in some cases even mid course enmasse replacement of feeders. While analyzing the data on wall thicknesses and in arriving at the wall thinning rate during operation of the reactor, sufficient care has to be taken to account for the wall thinning occurring during full system chemical decontamination campaign which is carried out occasionally to reduce dose rates during reactor shut down. Chemical decontamination of primary heat transport system is carried out using a mixture of organic acids at a total concentration of about 0.1 g/L and at 85 °C. The results of experiments carried out under simulated conditions for estimating the wall thinning occurring in carbon steel feeder elbow during dilute chemical decontamination are described in this work. The corrosion rates are quantified.     

Effect of SiC on Mechanical and Microstructural Characteristics of Al Based Functionally Graded Material

Silicon - In this study, an attempt was made to enhance the mechanical and microstructural properties of aluminium (Al) based FGM with the influence of silicon carbide (SiC) elements. The five...     

Machining of NiTi-shape memory alloys-A review

The emerging trends in the development of advanced smart materials with better unique properties under different environments for a particular application fascinate the researchers and industrialists. Nickel-Titanium based shape memory alloys are exotic materials due to their unique properties such as SME, SE, high damping characteristics, high corrosion and wear resistance and biocompatibility. This article presents an overview of machining processes that can be used to machine the NiTi and its surface induced characteristics such as microhardness, surface roughness, topography, induced layer, residual stress, fatigue and phase transformation. The surface integrity characteristics are discussed for machining of NiTi-SMAs under the category of traditional, non-traditional and micro-machining with the effect of input parameters such as cutting speed, feed, depth of cut, type of lubricant and type of coating material on cutting tool. The conventional machining of NiTi alloys are quite complicated due to high toughness, severe strain hardening, fatigue hardening and distinctive property of NiTi-SMAs such as pseudoelastic and shape memory effect. From this study, non-traditional process is significantly used to machine the NiTi-SMAs due to its better results on surface integrity characteristics. Consequently, future trends are also identified for machining the NiTi-SMAs and to improve the surface integrity characteristics.     

Scheduling Network and Computing Resources for Sliding Demands in Optical Grids

In this paper, we consider the problem of scheduling lightpaths and computing resources for sliding grid demands in WDM networks. Each sliding grid demand is represented by a tuple (v,R,c,p,q,l) , where v is the client node, R is the resource-group which includes a group of predefined resource nodes, c is the required amount of computing resources, [p,q] is the time window and l is the demand duration. With each demand, the scheduling algorithm is required to decide the start time t (p les t les q - l), reserve an amount of c computing resources at a resource node v ^' isin R and provision a primary lightpath as well as a backup lightpath from v ^' to v . The reserved computing resources and lightpaths are used during [t,t + l]. Unlike the sequential approach wherein the start time, the network resources (lightpaths) and the computing resources are considered one after another, in our work we use the joint scheduling approach wherein the resources and the start time are examined jointly. We consider sliding demands with static and dynamic arrival patterns. We develop an integer linear programming (ILP) formulation to obtain optimal results. For the reason of scalability, we propose heuristic algorithms based on joint resource scheduling and study their effectiveness through simulation experiments.