Nanotechnology and Nanomaterials for New and Sustainable Energy Engineering

Role of nanotechnology and nanomaterials for utilization, storage and generation of hydrogen energy, generation of environment friendly thermoelectric power, generation of geothermal energy and photovoltaic or solar energy has been explored. Graphene nanosheet has emerged as a promising material for Platinum catalyst support of fuel cell to enhance electrochemically active surface area and power generation. Graphene and graphene based nanocomposites namely graphene-Polyaniline (PANI) are explored as promising alternatives for hydrogen storage. Inorganic-organic nanocomposite electrolyte membranes comprising of nanosize inorganic building block offers higher proton conductivity, ion exchange capacity and enhanced power generation when applied in a fuel cell. Nanostructured thermoelectric material enhances the power factor and figure of merit. Inorganic (bismuth telluride) –organic (conducting polymer) nanocomposites are explored as a new class of thermoelectric material. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3528

Nanostructures of Polyaniline with Organic and Inorganic Dopants for Sensing of Ammonia

Nanostructured samples of polyaniline (PANI) doped with different dopants (organic and inorganic) have been synthesized employing polymerization and electrodeposition. The influence of nature of dopants( organic and inorganic) and process variation on the room temperature electrical conductivity and on ammonia vapour sensing performance (response percentage and response time) has been investigated. The synthesized samples have been structurally characterized by transmission electron microscopy (TEM) and fourier transform infrared (FTIR) spectra. Regardless of type of dopants, polymerization produces nanospheres of PANI and electrodeposition leads to formation of nanorod-like structures. Among all the synthesized samples, the organic doped electrodeposited sample exhibits highest conductivity. The conductivity of the prepared samples ware measured as a function of time after exposure to ammonia indicating that the polymerized samples (both for organic and inorganic dopants) exhibit fastest response (least response time), while the electrodeposited samples show sluggish response. Thus response percentages of different samples are found to depend on the nanostructures which vary with the nature of dopants and process of preparation. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3519

Thermoelectric Characterization of Nanostructures of Bismuth Prepared by Solvothermal Approach

Nanostructured thermoelectric materials being an emerging area of research bismuth (Bi) nanostructures have been developed by solvothermal approach with a change of solvent. Structural characterization revealed that nanorods and nanospheres like structures were generated in the process when the solvent used were only ethylene glycol (EG) and ethylene glycol with absolute ethanol (AE) in the ratio of 1:1 respectively. Electrical properties viz. conductivity (σ) and thermoelectric power(S) have been measured in the temperature range 300K to 400K. From the observed value of σ and S power factor P has been calculated. The property improved for nanosphere like structures. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3525

Synthesis, Characterization and Performance Study of Phosphosilicate Gel-Sulfonated Poly (Ether Ether Ketone) Nanocomposite Membrane for Fuel Cell Application

Phosphosilicate gel – SPEEK (Sulfonated Poly Ether Ether Ketone) hybrid nanocomposite membranes are proposed for performance enhancement of polymer electrolyte fuel cell. The nanocomposite membranes are synthesized and characterized at 50 and 60 weight percent of inorganic loading. Phosphosilicate gel particles of varying size (sub micro to nanometer) are synthesized using sol gel approach followed by grinding using planetary ball mill for different time. Transmission Electron Microscopy (TEM) reveals less than 10 nm particle size for 20 hr grinding. Nano composite membrane having inorganic particles of size less than 10 nm exhibits higher values of proton conductivity, ion exchange capacity and water uptake compared to composite membrane comprising of larger (400 nm and above) inorganic particles. The membrane is assembled with the electrode in the unit cell and the polarization characteristics are measured at different operating temperatures. Performance study reveals that between 70 to 80 C the membrane offers best performance in terms of peak power generation and of allowable load current. For the same conditions 40-50 % nano-enhancement of peak power generation is achieved by reducing the average gel particle size from sub micro to less than 10 nm. At medium temperature (between 70 to 80 C) the nanocomposite membrane offers more than 100 enhancement of peak power generation compared to that generated by SPEEK membrane. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2491

Privacy Preserving Multi-Server k-means Computation over Horizontally Partitioned Data

The k-means clustering is one of the most popular clustering algorithms in data mining. Recently a lot of research has been concentrated on the algorithm when the dataset is divided into multiple parties or when the dataset is too large to be handled by the data owner. In the latter case, usually some servers are hired to perform the task of clustering. The dataset is divided by the data owner among the servers who together perform the k-means and return the cluster labels to the owner. The major challenge in this method is to prevent the servers from gaining substantial information about the actual data of the owner. Several algorithms have been designed in the past that provide cryptographic solutions to perform privacy preserving k-means. We provide a new method to perform k-means over a large set using multiple servers. Our technique avoids heavy cryptographic computations and instead we use a simple randomization technique to preserve the privacy of the data. The k-means computed has exactly the same efficiency and accuracy as the k-means computed over the original dataset without any randomization. We argue that our algorithm is secure against honest but curious and passive adversary.Comment: 19 pages, 4 tables. International Conference on Information Systems Security. Springer, Cham, 201

Dewetting of thin films on heterogeneous substrates: Pinning vs. coarsening

We study a model for a thin liquid film dewetting from a periodic heterogeneous substrate (template). The amplitude and periodicity of a striped template heterogeneity necessary to obtain a stable periodic stripe pattern, i.e. pinning, are computed. This requires a stabilization of the longitudinal and transversal modes driving the typical coarsening dynamics during dewetting of a thin film on a homogeneous substrate. If the heterogeneity has a larger spatial period than the critical dewetting mode, weak heterogeneities are sufficient for pinning. A large region of coexistence between coarsening dynamics and pinning is found.Comment: 4 pages, 4 figure

Constrained blackbox optimization: The SEARCH perspective

Search and optimization in the context of blackbox objective function evaluation subject to blackbox constraints satisfaction is the thesis of this work. The SEARCH (Search Envisioned As Relation and Class Hierarchizing) framework introduced by Kargupta (1995) offered an alternate perspective of blackbox optimization in terms of relations, classes, and partial ordering. The primary motivation comes from the observation that sampling in blackbox optimization is essentially an inductive process and in the absence of any relation among the members of the search space, induction is no better than enumeration. SEARCH also offers conditions for polynomial complexity search and bounds on sample complexity using its ordinal, probabilistic, and approximate framework. In this work the authors extend the SEARCH framework to tackle constrained blackbox optimization problems. The methodology aims at characterizing the search domain into feasible and infeasible relations among which the feasible relations can be explored further to optimize an objective function. Both -- objective function and constraints -- can be in the form of blackboxes. The authors derive results for bounds on sample complexity. They demonstrate their methodology on several benchmark problems

Credit card fraud detection: An application of the gene expression messy genetic algorithm

This paper describes an application of the recently introduced gene expression messy genetic algorithm (GEMGA) (Kargupta, 1996) for detecting fraudulent transactions of credit cards. It also explains the fundamental concepts underlying the GEMGA in the light of the SEARCH (Search Envisioned As Relation and Class Hierarchizing) (Kargupta, 1995) framework

Templeting of Thin Films Induced by Dewetting on Patterned Surfaces

The instability, dynamics and morphological transitions of patterns in thin liquid films on periodic striped surfaces (consisting of alternating less and more wettable stripes) are investigated based on 3-D nonlinear simulations that account for the inter-site hydrodynamic and surface-energetic interactions. The film breakup is suppressed on some potentially destabilizing nonwettable sites when their spacing is below a characteristic lengthscale of the instability, the upper bound for which is close to the spinodal lengthscale. The thin film pattern replicates the substrate surface energy pattern closely only when, (a) the periodicity of substrate pattern matches closely with the characteristic lengthscale, and (b) the stripe-width is within a range bounded by a lower critical length, below which no heterogeneous rupture occurs, and an upper transition length above which complex morphological features bearing little resemblance to the substrate pattern are formed.Comment: 5 pages TeX (REVTeX 4), other comments: submitted to Phys. Rev.Let

Ideal-gas like market models with savings: quenched and annealed cases

We analyze the ideal gas like models of markets and review the different cases where a `savings' factor changes the nature and shape of the distribution of wealth. These models can produce similar distribution of wealth as observed across varied economies. We present a more realistic model where the saving factor can vary over time (annealed savings) and yet produces Pareto distribution of wealth in certain cases. We discuss the relevance of such models in the context of wealth distribution, and address some recent issues in the context of these models.Comment: 2-col RevTeX4, 4 pages, 1 eps figure; Proc. APFA5 Conference, Torino, 200