Synthesis of Boron Nitride Microtubes and Formation of Boron Nitride Nanosheets

Boron nitride microtubes are synthesized in a dual zone quartz tube furnace at 1200°C with ammonia as a reaction atmosphere. Field emission scanning electron microscopy (FE-SEM) results show a unique cone-like morphology of the tubes with larger internal space and thin walls structure. The diameters of the tubes were found to be in the range of 1 to ～2 µm with the walls thickness estimated to be from 10 to 100 nm. XPS survey shows N 1 s and B 1 s peaks at 398.7 and 191 eV, respectively, that represent h-BN in the sample. Raman spectroscopy indicates a high-intensity peak at 1372.53 (cm^?1) that corresponds to the E_2g mode of h-BN. Along with the novel tubular morphology of boron nitride microtubes, the present work also explains a mechanism for the formation of boron nitride nanosheets (from boron nitride microtubes) found in the FE-SEM results of the current sample.     

Multiple responses analysis and modeling of Fenton process for treatment of high strength landfill leachate

Landfill leachate is one of the most recalcitrant wastes for biotreatment and can be considered a potential source of contamination to surface and groundwater ecosystems. In the present study, Fenton oxidation was employed for degradation of stabilized landfill leachate. Response surface methodology was applied to analyze, model and optimize the process parameters, i.e. pH and reaction time as well as the initial concentrations of hydrogen peroxide and ferrous ion. Analysis of variance showed that good coefficients of determination were obtained (R2 > 0.99), thus ensuring satisfactory agreement of the second-order regression model with the experimental data. The results indicated that, pH and its quadratic effects were the main factors influencing Fenton oxidation. Furthermore, antagonistic effects between pH and other variables were observed. The optimum H2O2 concentration, Fe(II) concentration, pH and reaction time were 0.033 mol/L, 0.011 mol/L, 3 and 145 min, respectively, with 58.3% COD, 79.0% color and 82.1% iron removals.     

Automatic computer-aided caries detection from dental x-ray images using intelligent level set

Multimedia Tools and Applications - Dental diseases have high risk of affection across the globe and mostly in adult population. The analysis of dental X-ray images has some difficulties in...     

Phase Distribution and Magnetic Properties of Mechanically Alloyed Hard/Soft Ferrite Nanocomposites

Improvement in the magnetic properties of hard/ soft ferrite nanocomposites was studied by varying the composition of the soft phase in SrFe₁₂O₁₉/Ni_0.5Zn_0.5Fe₂O₄ nanocomposites. The SrFe₁₂O₁₉/Ni_0.5Zn_0.5Fe₂O₄ nanocomposites were prepared using the mechanical alloying method. The samples were prepared by varying the amount of the soft phase from 10 to 50 wt% while the amount of the hard phase remained 100 wt% in the ferrite nanocomposites. X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), and a transmission electron microscope (TEM) were used to characterize the samples. From the result, it was found that the nanocomposite magnet with 10 wt% of soft phase content had the highest remanence ratio, M _r / M _s , which was 0.61, while the values of the coercivity, H _c , and magnetization, M _s , measured were 4482.4 G and 9.71 emu/g, respectively, and the average particle size of the ferrite nanocomposites was < 50 nm for all the samples. It was also shown that H _c decreased as the weight percent of the soft ferrite increased, which resulted from the dipolar interaction that occurred in the ferrite nanocomposites, showing the effect of phase distribution on the magnetic properties.     

Filter-Bank Modulation Based Signal Design and Transmission Techniques for Intensity Modulated MIMO Visible Light Communication Systems

Wireless Personal Communications - Current research in wireless communication undoubtedly points towards the tremendous advantages of using visible light as a spectrum for significantly boosting...     

Self-reinforcing mechanisms for cellularisation: a longitudinal case study

Firms that adopt cellular manufacturing (CM) often need to restructure their products, personnel, equipment, factory management and organisation culture. Despite voluminous literature on CM, only a few case studies related to cellularisation exist. Therefore, to enhance understanding in this area, this paper presents a longitudinal case study on cellularisation in an electronic assembly plant. Six years of data were collected from the observations and discussions of an industrialist and an academician. Events instrumental to the persistence of CM were highlighted, with reference to path dependence analysis. Cellularisation is not entirely evolutionary or teleological but is an interplay of the two; it is significantly influenced by the positive feedback of self-reinforcing mechanisms after departing from critical junctures. The observed self-reinforcing mechanisms were expounded and divided into six categories.     

Direct Growth and Photoluminescence of SiO<Subscript>x</Subscript> Nanowires and Aligned Nanocakes by Simple Carbothermal Evaporation

The growth of SiO_x nanowires and nanocakes on an Au-coated n-type-Silicon (100) substrate was achieved via carbothermal evaporation. The effects of the Au layer thickness and the rapid heating rate on the morphology of obtained SiO_x nanowires were investigated. A broad emission band from 290 to 600 nm was observed in the photoluminescence (PL) spectrum of these nanowires. There are four PL peaks: one blue emission peak 485 nm (2.56 eV) two green bands centered at 502 nm (2.47 eV) and 524 nm (2.37 eV) for nanocakes and one ultraviolet emission peak at 350 nm (3.54 eV) and a hemisphere curve over the bluish green area taken for SiO_x nanowires. These emissions may be related to the various oxygen defects and twofold coordinated silicon lone pair centers.     

Ontology as a Service (OaaS): a case for sub-ontology merging on the cloud

Cloud computing is a revolution in the information technology industry. It allows computing services provided as utilities. The traditional cloud services include Software as a Service, Platform as a Service, Hardware/Infrastructure as a Service, and Database as a Service. In this paper, we introduce the notion of Ontology as a Service (OaaS), whereby the ontology tailoring process is a service in the cloud. This is particularly relevant as we are moving toward Cloud 2.0—multi-cloud providers to provide an interoperable service to customers. To illustrate OaaS, in this paper we propose sub-ontology extraction and merging, whereby multiple sub-ontologies are extracted from various source ontologies, and then these extracted sub-ontologies are merged to form a complete ontology to be used by the user. We use the Minimum extraction method to facilitate this. A walkthrough case study using the UMLS meta-thesaurus ontology is elaborated, and its performance in the cloud is also discussed.     

Optimized unequal error protection of embedded video bitstream using adaptive-hierarchical QAM

In this paper, a reliable video communication system using adaptive Hierarchical QAM (HQAM) is designed to provide optimized unequal error protection (UEP) to embedded video bitstreams. Based on the relative importance of bits, video bitstream is partitioned into two priorities, namely High Priority (HP) and Low Priority (LP) substreams. Then, the optimal value of modulation (or hierarchical) parameter (α) of HQAM, which controls the relative error protection of these substreams, is selected from a pre-designed look-up table. The proposed system adapts itself by adapting the optimal α according to the varying channel condition, without changing the modulation level. This is in contrast to conventional WiMAX and LTE systems, in which dynamic switching among multiple modulations is used to adapt the varying channel conditions. This paper proposes HQAM with adaptive α as an alternative to the multiple modulation schemes. Moreover, for fixed average transmission power, receiver demodulates symbols without the knowledge of α. In order to further improve the video quality and to reduce the effects of erroneously received LP bits, the proposed system uses another level of adaptation, in which received LP bits are adaptively considered or discarded, before decoding the video, depending on the channel conditions (or optimized α). Simulation results show that proposed system can achieve significant improvement in the video quality compared to QAM based EEP scheme and non-adaptive HQAM.