Dictionary based Image Compression via Sparse Representation

Nowadays image compression has become a necessity due to a large volume of images. For efficient use of storage space and data transmission, it becomes essential to compress the image. In this paper, we propose a dictionary based image compression framework via sparse representation, with the construction of a trained over-complete dictionary. The over-complete dictionary is trained using the intra-prediction residuals obtained from different images and is applied for sparse representation. In this method, the current image block is first predicted from its spatially neighboring blocks, and then the prediction residuals are encoded via sparse representation. Sparse approximation algorithm and the trained over-complete dictionary are applied for sparse representation of prediction residuals. The detail coefficients obtained from sparse representation are used for encoding. Experimental result shows that the proposed method yields both improved coding efficiency and image quality as compared to some state-of-the-art image compression methods

Computational and Experimental Studies on Gas-Solid Fluidized Bed Reactor for Treatment of Industrial Gaseous Effluent Containing Fluorides

Fluidization with respect to abatement of fluorides is carried out experimentally using fluidized bed reactor (FBR). Treatment of gaseous effluent from Aluminium industry containing fluorides is considered as a case study. For knowing the optimum operating conditions of FBR, some hydrodynamic studies are carried out in a Perspex column. After which same conditions in addition to the temperature effects are maintained in a stainless steel reactor of same dimensions. Different bed materials are used at different temperatures to check the maximum reduction of fluorides from industrial effluent gas. The phase composition and structural transition of bed materials at different temperatures are investigated. Characterization of bed materials before and after the experiments are carried out from which abatement of fluorides from industrial effluents is confirmed. For proper design of fluidized bed reactor CFD simulation is carried out by using the commercial CFD solver ANSYS/FLUENT 13.0 in the present work. All phases are described using an Eulerian approach to model the exchange of mass, energy and momentum. The appropriate model predictions are achieved, using Gidaspow drag model with restitution coefficient of 0.9, convergence criterions as 0.001, no slip boundary condition of specularity coefficient and first order discretization scheme. Hydrodynamic studies for the fluidized bed reactor are carried out computationally using fine i.e. Geldart-A particles. Effects of superficial velocity, static bed height, particle size and density of bed materials on bed pressure drop, bed expansion / fluctuation and fluidization index are studied. Results of experimental and computational studies are compared with each other. The comparison shows that CFD modeling is capable of predicting the hydrodynamic behaviors of gas–solid fluidized bed for fine particles with reasonable accuracy. CFD modeling is also carried out for thermal analysis. Velocity profile, bed expansion, solid movement, temperature profile are also focused in the present simulation work. Results of CFD simulation indicate that CFD modelling can be used to study the performance of fluidized bed reactor for high temperature reactions satisfactorily

HYDRODYNAMIC BEHAVIOUR OF SPOUTED BED USING COARSE / FINE PARTICLES

The characteristics of coarse / fine particles have been studied using a cylindrical spouted bed. The effects of different system parameters (viz. static bed height, particle size, particle density and superficial velocity of the medium) have been analysed to study the bed dynamics such as bed expansion / fluctuation ratio, bed pressure drop and fluidization index of coarse / fine particles. Mathematical expressions have been developed on the basis of dimensionless analysis. Finally calculated values of these bed dynamics have been compared against the experimentally observed values. The comparison results show very good agreement between the experimental and calculated values thereby indicating the application of these correlations over a wide range of parameters

Nanostructured Semiconductors for Thermoelectric Energy Conversion: Synthesis and Transport Properties.

Half-Heusler (HH) alloys are among the most popular material systems for high temperature thermoelectric energy conversion. Approaches to increase the thermoelectric figure of merit (ZT) of HH range from (1) chemical substitution of atoms with different masses within the same atomic position in the crystal structure to optimize carrier concentration and enhance phonon scattering via mass fluctuation and (2) embedding secondary phonon scattering centers in the matrix (nanostructuring) to further reduce thermal conductivity. This work focuses on three material systems. The first part describes the synthesis and properties of oxide nanostructures (NiO, Co3O4) which were subsequently used as inclusion phases in HH matrix to reduce the thermal conductivity. The effects of the synthesis conditions on the thermoelectric properties of compacted pellets of NiO and Co3O4 are discussed. The second part of the work discusses the development of synthetic strategies for the fabrication of p-type and n-type bulk nanostructured thermoelectric materials made of a half-Heusler matrix based on (Ti,Hf)CoSb, containing nanostructures with full-Heusler (FH) compositions. The role of the nanostructures in the regulation of phonon and charge carrier transports within the HH matrix is discussed by combining transport data and electron microscopy images. It was found that the FH nanoinclusions form staggered heterojunctions with a valence band (VB) offset energy at the HH/FH phase boundaries which discriminates existing holes with respect to their energy by trapping low energy holes and promoting the transport of high energy holes through the VB of the FH nanostructures. This results in large increase in the mobility and effective mass of high energy holes contributing to electronic conduction. The simultaneous reduction in the density and the increase in the effective mass of holes caused large enhancements of the thermopower. In the third part, the application of this concept of nanostructuring on the copper selenide material system is described. Various synthetic approaches such as liquid assisted solid-state reaction and mechanical alloying are utilized for the fabrication of copper selenide compositions. We found that the mechanical alloying clearly decreases the thermal conductivity of the composition as well increases the Seebeck due to decrease in carrier concentrations.PhDMaterials Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102348/1/pranati_1.pd

Hydrodynamic Studies of Coarse, Fine and Nano Particles in a Cylindrical Fluidized / Spouted Bed: CFD Simulation

The fluidization characteristics or hydrodynamic behaviours of coarse (regular / irregular), fine and nano particles have been studied in a fluidized and/or spouted bed for gas-solid system. A stirrer and external force (equivalent centrifugal force) have been used with fine and nano particles respectively for smooth fluidization. The speed of rotation of stirrer with fine particles and frequency of application of external force (magnitude of force) with nano particles were also varied for analyzing the fluidization characteristics. Experiments were carried out in a cylindrical column by varying different system parameters (viz. static bed height, particle size, particle density and superficial velocity of the medium, speed of rotation of stirrer and spout diameter). Fluidization characteristics, such as bed expansion ratio, bed fluctuation ratio, bed pressure drop, minimum fluidizing/spouting velocity and fluidization index of coarse (regular / irregular), fine and nano particleshave been tried to be analyzed by developing correlations on the basis of dimensional less analysis. Finally calculated values of different fluidization characteristics have been compared against the experimentally observed values. The comparison results show a good agreement among the experimental and calculated values thereby indicating the application of these developed correlations over a wide range of parameters.CFD simulation has also been carried out for the hydrodynamic behaviours. Finally calculated values of these fluidization characteristics obtained through CFD simulation have been compared against the experimentally observed values. The results show a good agreement thereby implying the design of fluidizer for gas-solid systems can be optimum design for many chemical industries. The technique of external force application can also be suitably used in industries for handling nano particles with increased efficiencies

Crystal Structure of FePb 4 Sb 6 Se 14 and its Structural Relationship with FePb 3 Sb 4 Se 10

Single crystals of FePb 4 Sb 6 Se 14 , were obtained from solid‐state combination of high purity elemental powders at 873K for three days. Single crystal X‐ray structure determination revealed that the compound crystallizes in the monoclinic space group P 2 1 / c (no. 14) and adopts the structure of Jamesonite (FePb 4 Sb 6 S 14 ). The structure contains two crystallographically independent lead atoms with monocapped and bicapped trigonal prismatic coordinations, three antimony atoms located in a distorted octahedral environment and one iron atom occupying a flattened octahedral coordination. Neighboring monocapped and bicapped trigonal prims around lead atoms share faces and edges to build a corrugated layer parallel to the ac plane. Octahedrally coordinated antimony atoms share edges to form one‐dimensional (1D) {SbSe} ∞ ribbons connecting adjacent corrugated layers. The distortion of the octahedral coordination around antimony atoms within the {SbSe} ∞ ribbons with the longest bond pointing towards the center of the ribbon, suggests the stereochemical activity of antimony lone‐pairs with their electron clouds pointing towards the center of the {SbSe} ∞ ribbon. The three dimensional framework resulting from the connectivity between the corrugated layers and the {SbSe} ∞ ribbons, contains isolated cylindrical voids parallel to [100] which are filled by a 1D Fe n Se 4n+2 straight chain of edge‐sharing FeSe 6 octahedra. The crystal structure of FePb 4 Sb 6 Se 14 is closely related to that of FePb 3 Sb 4 Se 10 as they are formed by similar building units with different sizes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95198/1/2549_ftp.pd

Identifying Risk Factors for Lower Reproductive Tract Infections among Women Using Reusable Absorbents in Odisha, India.

A large proportion of women in Odisha, India, use reusable absorbents to manage their menstruation. Yet, the risk factors for lower reproductive tract infections (RTIs) related to menstrual hygiene management (MHM) have not been studied among reusable absorbent users. Women of reproductive age attending one of two hospitals from two different cities in Odisha during two separate study intervals were recruited for the study. Laboratory diagnosis of bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC) were conducted. A questionnaire was used to collect information on MHM practices, water, sanitation, and socio-demographic factors. Among the 509 women who used reusable absorbents, 71.7% were diagnosed with at least one infection. After adjusting for confounders, women with BV were more likely to identify as being a housewife (aOR: 1.8 (1.1-2.9)). Frequent absorbent changing was protective against BV (aOR: 0.5 (0.3-0.8)), whereas frequent body washing increased the odds of BV (aOR: 1.5 (1.0-2.2)). Women with VVC were more likely to be older (aOR: 1.6 (1.0-2.5)), live below the poverty line (aOR: 1.5 (1.1-2.2)), have a non-private household latrine (aOR: 2.2 (1.3-4.0)), dry their absorbents inside the house (aOR: 3.7 (2.5-4.5)), and store absorbents in the latrine area (aOR: 2.0 (1.3-2.9)). Washing absorbents outside the house was protective against VVC (aOR: 0.7 (0.4-1.0)). This study highlights the importance of improving MHM practices among reusable absorbent users to prevent lower RTIs among women reusing menstrual materials in Odisha

Association between unhygienic menstrual management practices and prevalence of lower reproductive tract infections: a hospital-based cross-sectional study in Odisha, India.

BACKGROUND: The extent to which reproductive tract infections (RTIs) are associated with poor menstrual hygiene management (MHM) practices has not been extensively studied. We aimed to determine whether poor menstrual hygiene practices were associated with three common infections of the lower reproductive tract; Bacterial vaginosis (BV), Candida, and Trichomonas vaginalis (TV). METHODS: Non-pregnant women of reproductive age (18-45 years) and attending one of two hospitals in Odisha, India, between April 2015 and February 2016 were recruited for the study. A standardized questionnaire was used to collect information on: MHM practices, clinical symptoms for the three infections, and socio-economic and demographic information. Specimens from posterior vaginal fornix were collected using swabs for diagnosis of BV, Candida and TV infection. RESULTS: A total of 558 women were recruited for the study of whom 62.4% were diagnosed with at least one of the three tested infections and 52% presented with one or more RTI symptoms. BV was the most prevalent infection (41%), followed by Candida infection (34%) and TV infection (5.6%). After adjustment for potentially confounding factors, women diagnosed with Candida infection were more likely to use reusable absorbent material (aPRR = 1.54, 95%CI 1.2-2.0) and practice lower frequency of personal washing (aPRR = 1.34, 95%CI 1.07-1.7). Women with BV were more likely to practice personal washing less frequently (aPRR = 1.25, 95%CI 1.0-1.5), change absorbent material outside a toilet facility (aPRR = 1.21, 95%CI 1.0-1.48) whilst a higher frequency of absorbent material changing was protective (aPRR = 0.56, 95%CI 0.4-0.75). No studied factors were found to be associated with TV infection. In addition, among women reusing absorbent material, Candida but not BV or TV - infection was more frequent who dried their pads inside their houses and who stored the cloth hidden in the toilet compartment. CONCLUSION: The results of our study add to growing number of studies which demonstrate a strong and consistent association between poor menstrual hygiene practices and higher prevalence of lower RTIs

CFD simulation for hydrodynamic behaviour of fine particles in a fluidized bed

253-261The fluidization characteristics of fine particles i.e. Geldart–C and A particles are studied in a cylindrical fluidized column. The effects of different system parameters (viz. static bed height, particle density, size of particle, speed of promoter and superficial velocity of the fluidizing medium) on bed dynamics are analyzed. CFD simulation is carried out for the hydrodynamic behaviour of fine powders. The values of these bed dynamics obtained through CFD simulation are compared against the respective experimental values. The comparison results show very good agreement between the experimental and simulated results thereby indicating the possibility of smooth or proper fluidization for fine particles. Thus these findings will be helpful in designing a good fluidized bed reactor for fine particle system can optimize the processes very well