S. R. S. Prabaharan

Radio Frequency Energy Harvesting and Management for Wireless Sensor Networks

Radio Frequency (RF) Energy Harvesting holds a promising future for generating a small amount of electrical power to drive partial circuits in wirelessly communicating electronics devices. Reducing power consumption has become a major challenge in wireless sensor networks. As a vital factor affecting system cost and lifetime, energy consumption in wireless sensor networks is an emerging and active research area. This chapter presents a practical approach for RF Energy harvesting and management of the harvested and available energy for wireless sensor networks using the Improved Energy Efficient Ant Based Routing Algorithm (IEEABR) as our proposed algorithm. The chapter looks at measurement of the RF power density, calculation of the received power, storage of the harvested power, and management of the power in wireless sensor networks. The routing uses IEEABR technique for energy management. Practical and real-time implementations of the RF Energy using Powercast harvesters and simulations using the energy model of our Libelium Waspmote to verify the approach were performed. The chapter concludes with performance analysis of the harvested energy, comparison of IEEABR and other traditional energy management techniques, while also looking at open research areas of energy harvesting and management for wireless sensor networks.

Electrode properties of Mn 2 O 3 nanospheres synthesized by combined sonochemical/solvothermal method for use in electrochemical capacitors

We report here an efficient single step combined sonochemical and solvothermal synthesis process to obtain bulk quantities of nanospherical particles of cubic Mn2O3 and characterized its pseudocapacitive characteristics in relevance to electrochemical capacitors for the first time. It has been found that quantitative determination of specific capacitance yielded a value of capacitance of ∼100 Fg-1 within 0-0.4 V (versus SCE) potential range in a 6 M KOH alkaline electrolyte. The as-prepared nanopowders after being subjected to heat treatment at 400°C were characterized by using XRD which shows a typical cubic single-phase structure (space group Ia-3), the broad crystalline peaks indicating the presence of explicit nanostructure. Electron microscopic studies (FE-SEM and TEM) revealed that the synthesized powders exhibit nanospherical morphology with uniform sphere-like grains of ∼10-15nm range. Two heat-treated samples were studied in the context of crystallinity versus electrochemical capacitance using rate-dependent cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in a three-electrode system. The excellent well-refined redox behavior corroborates with EIS measurements. The presence of near symmetric redox couple observed in CV has been attributed to pronounced one-electron-transfer process owing to the presence of facileMn redox centere facilitating the reversible one-electron transfer that accounts for its pseudocapacitance.

New Lithiated NASICON-Type Li2Ni2 ( MoO4 ) 3 for Rechargeable Lithium Batteries Synthesis, Structural, and Electrochemical Properties

We report on the first synthesis of a new NASICON framework Li 2 Ni 2 (MoO 4 ) 3 and on the investigation of its electrochemical behavior upon Li extraction coupled with structural analysis. Li 2 Ni 2 (MoO 4 ) 3 was synthesizedby a novel soft-combustion approach involving glycine as a combustion agent and the product was found to crystallize in an orthorhombic structure (space group Pmcn) with lattice parameters a = 10.424(4) A, b = 17.525(1) A, and c = 5.074(3) A. Reversible extraction and insertion of lithium from and into the framework structure delivered a reversible capacity of ∼115 mAh/g (4.9-1.5 V window) after the first charge/discharge cycle.

Ant Based Routing Protocol for Visual Sensors

In routing protocols, sensor nodes tend to route events (images) captured to a particular destination (sink) using the most efficient path. The power and bandwidth required to transmit video data from hundreds of cameras to a central location for processing at a high success rate would be enormous. In this work, captured packets were routed from different sensors placed at different locations to the sink using the best path. Since the captured images (packets) need to be routed to the destination (sink) at regular interval and within a predefined period of time, while consuming low energy without performance degradation, Ant based routing which utilizes the behavior of real ants searching for food through pheromone deposition, while dealing with problems that need to find paths to goals, through the simulating behavior of ant colony is adopted. In this end, we present an Improved Energy-Efficient Ant- Based Routing (IEEABR) Algorithm in Visual Sensor Networks. Compared to the state-of-the-art Ant-Based routing protocols; Basic Ant-Based Routing (BABR) Algorithm, Sensor-driven and Cost-aware ant routing (SC), Flooded Forward ant routing (FF), Flooded Piggybacked ant routing (FP), and Energy- Efficient Ant-Based Routing (EEABR), the proposed IEEABR approach have advantages of reduced energy usage, delivering events packets at high success rate with low latency, increases the network lifetime, and actively performing its set target without performance degradation. The performance evaluations for the algorithms on a real application are conducted in a well known WSNs MATLAB-based simulator (RMASE) using both static and dynamic scenario.

Synthesis of a Polyanion Cathode Material, Li2Co2 ( MoO4 ) 3 , and Its Electrochemical Properties for Lithium Batteries

High voltage redox properties of a polyanion material, Li2Co2(MoO4)(3), as positive electrode was demonstrated against lithium for the first time. The orthorhombic structure showed reversible extraction and insertion cycles of lithium at a potential of ca. 4.9 V vs. Li+/Li as well as 1.5 V. The former potential was attributed to Co2+/Co3+ and the latter to Mo6+/Mo5+. The reason for the change in charge/discharge curves after the first charge is clearly demonstrated by the structural changes (monoclinic, P2/m) caused by electrochemical extraction and insertion of lithium as deduced from the ex situ X-ray diffraction analysis on the cycled electrode pellet

Soft-combustion (wet-chemical) synthesis of a new 4-V class cathode-active material, LiVMoO6, for Li-ion batteries

Abstract A new, 4-V class, lithiated transition metal oxide cathode, LiVMoO6, has been synthesized by a novel soft-combustion (wet chemical) low temperature (LT) method that presents advantages compared to the classical ceramic method, namely, in terms of phase purity, surface texture and size, preparation time, costs and electrochemical performances of the resulting products. The structural properties of the newly synthesized product have been examined by means of X-ray diffraction studies (XRD). The thermal reactions which occur during the soft-combustion of the precursor mixture have been examined by DTA/TG techniques. It has been found that the layered LiVMoO6 can only be obtained upon calcining the precursor at 540°C, beyond which the compound will thermally be reduced to LiVMoO5 which exhibits inferior structural characteristics for the intercalation/deintercalation reactions. The product (LiVMoO6) thus prepared exhibits submicrometre spherical grains (

Optimization of synthesis condition and the electrochemical properties of LiVMO6−δ (M=Mo or W) as candidate positive electrode material for lithium batteries

Abstract A new family of high voltage (4 V) class positive electrode materials namely LiVMO 6− δ [M=Mo or W] has been identified for use in lithium-containing rechargeable cells. The lithiated twin transition metal oxides have been synthesized following a simple aqueous solution reaction (ASR) process called soft-combustion method. The submicronic particles of the electrode powder, thus prepared, demonstrate the high voltage behavior in lithium-containing cells. Electrochemical studies such as galvanostatic intermittent charge–discharge (GITT) experiments and cyclic voltammetry (CV) have proved that these materials could certainly be regarded as 4-V type materials with specific capacities as high as ∼165 mA h/g (LiVMoO 6− δ ) and ∼95 mA h/g ((LiVWO 6− δ ) between 4.6 and 2.8 V. Both these materials are found to have similar electrochemical character with respect to their operating voltages. Among these brannerites, LiVMoO 6− δ exhibits a higher practical capacity than its tungstate counterpart.

Synthesis and redox behavior of a new polyanion compound, Li2Co2(MoO4)3, as 4 V class positive electrode material for lithium batteries

A new material, Li2Co2(MoO4)3, belonging to NASICON type polyanion family was synthesized by means of a low temperature soft-combustion method using glycine as a soft combustion fuel. The annealed product, Li2Co2(MoO4)3, was found to exhibit a single phase structure as confirmed by XRD and crystallized in an orthorhombic structure (space group Pnma) with lattice parametersa=5.086(1) Å,b=10.484(2) Å and c=17.606(2) Å. The electronic state of each element present in the new material was confirmed by X-ray photoelectron spectroscopic (XPS) analysis. The stoichiometry of the synthesized product was determined by the metal analysis using inductively coupled plasma (ICP-AES) technique. The microstructural analysis by means of SEM revealed cylindrical fiber-like grains. Electrochemistry of the new material was demonstrated by extraction/insertion process of Li+ in lithium batteries. Galvanostatic charge/discharge profiles revealed a reversible discharge capacity of ∼ 55 mAh/g over the potential window of 4.9 - 1.5 V.

NASICON Open Framework Structured Transition Metal Oxides for Lithium Batteries

Since the dawn of civilization, world has become increasingly addicted to electricity due to its utmost necessity for human life. The demand for electrically operated devices led to a variety of different energy storage systems which are chosen depending on the field of application. Among the available stationary power sources, rechargeable lithium-ion batteries substantially impact the areas of energy storage, energy efficiency and advanced vehicles. These batteries are the most advanced and true portable power sources combined with advantages of small size, reduced weight, longer operating time and easy operation. Such batteries can be recharged anytime (no memory effect) regardless of the charge current/voltage and they are reliable and safe. These unique features render their application in a variety of consumer electronic gadgets such as mobile phones, digital cameras, personal digital assistants (PDAs), portable CD players and palmtop computers. The high-end applications of this smart power source are projected for Hybrid Electric Vehicles (HEVs) as potential source of propulsion. The evolution of rechargeable lithium batteries since their inception by Sony Corporation (Reimers & Dahn, 1992) has led to the development of new electrode materials (Kobayashi et al., 2000; Gaubicher, et al., 2000; Zhang et al., 2009; Zhu et al., 2008) for their effective operation in the real ICT environment. Among the new materials search for Li-ion batteries, polyanion compounds are growing into incredible dimensions owing to their intriguing properties (Manthiram & Goodenough, 1989; Huang et al., 2001; Yang et al., 2002; Chung et al., 2002). In this chapter, we present a systematic study of a group of new polyanion materials, namely, lithium-rich [Li2M2(MoO4)3] and lithium-free [LixM2(MoO4)3] (M= Ni, Co) phases of transition metal oxides having NASICON open framework structure. A simple and efficient approach to prepare the materials and a combination of characterization techniques to reveal the physical and electrochemical properties of these materials are covered at length. A separate section is devoted to a nano-composite approach wherein conductivity enhancement of all the four materials is enlightened. We begin this chapter with a brief 5

Data Compression Algorithms for Visual Information

Audio-visual information is one of the richest but also most bandwidth-consuming modes of communication. To meet the requirements of new applications, powerful data compression schemes are needed to reduce the global bit rate drastically. In this paper, we proposed a simple lossless visual image compression scheme that will be used to compress visual images. In this scheme, the two dimensional visual image data is converted to a one dimensional data using our proposed pixel scanning method. The difference between consecutive pixel values in the resulting one dimensional image data is taken and the residues are encoded losslessly using an entropy encoder. The working principles of this our approach is presented together with the image compression algorithm used. We developed a software algorithm and implemented it to compress some standard test images using Huffman style coding techniques in a MATLAB platform.