EFFECT OF INTERPHASE MASS TRANSFER ON UNSTEADY CONVECTTVE DIFFUSION: PART II HAGEN POISEUILLE FLOW OF A POWER LAW FLUID IN A TUBE

The influence of interphase mass transfer on dispersion of solute in a tube flow of a power-law fluid is examined at all times after the injection of the solute. Three important dispersion mechanisms are shown to arise in the study in place of two in classical studies. This is true in channel flows also (see Siddheshwar et al. [1]). The present analytical result on dispersion of solute with wall catalysed reaction at long times is compared with the analytical solution when reaction is absent. The Taylor [2] and Aris [2] of dispersion are obtained as limiting cases from the study. The graphical results of the study serve as a jury on any numerical treatment of the present problem that might be undertaken considering non-asymptotic all-time analysis.     

Solving general multi-class closed queuing networks using parametric decomposition

This paper presents a new approach to evaluate the performance of general multi-class closed queuing networks. The approach uses parametric characterization of the traffic processes to derive two-moment approximations for performance measures at individual nodes. Based on these approximations, linkage equations are derived to establish the relationships between the various nodes in the network. These relationships result in a system of non-linear equations that is solved using an iterative procedure. Numerical studies comparing the performance of the approach with detailed simulations suggest that the approach yields fairly accurate estimates of performance measures without significant computational complexity.     

Synthesis,and measurement of structural and magnetic properties,of La<Subscript>1−x</Subscript>Cd<Subscript>x</Subscript>CoO<Subscript>3</Subscript> perovskite ceramic oxides

Perovskite-type Cd-doped LaCoO₃ materials were synthesized by a simple solution-based combustion process. The synthesized materials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance (DR) in the UV-VIS, and magnetic property measurements. The parent LaCoO₃ compound showed spin-glass transition at low temperatures, and with progressive Cd doping, showed transition to paramagnetic ordering. The changes in magnetic properties of the materials are correlated to the changes in structural features resulting from the Rietveld structural refinement of the materials.     

Enhancing form factor and light collection of multiplex imaging systems by using a cubic phase mask

The bulky form factor of traditional optical sensors limits their utility for certain applications. Flat multiplex imaging-sensor architectures face the light-gathering challenges inherent with small collection apertures. We examine a wavefront-coding approach wherein a cubic phase mask is used to increase the aperture sizes of multiplex imaging systems while maintaining the distance from the lens to the detector array. The proposed approach exploits the ability of cubic-phase-mask systems to operate over a large range of misfocus values. An exact expression for the optical transfer function of cubic-phase-mask systems is presented, and its misfocus-dependent spatial-filtering properties are described. Criteria for form-factor enhancement are assessed and trade-offs encountered in the design process are evaluated.     

Applications of the phase transfer function of digital incoherent imaging systems

The phase of the optical transfer function is advocated as an important tool in the characterization of modern incoherent imaging systems. It is shown that knowledge of the phase transfer function (PTF) can benefit a diverse array of applications involving both traditional and computational imaging systems. Areas of potential benefits are discussed, and three applications are presented, demonstrating the utility of the phase of the complex frequency response in practical scenarios. In traditional imaging systems, the PTF is shown via simulation results to be strongly coupled with odd-order aberrations and hence useful in misalignment detection and correction. In computational imaging systems, experimental results confirm that the PTF can be successfully applied to subpixel shift estimation and wavefront coding characterization tasks.     

A tutorial survey of topics in wireless networking: Part I

In this two part paper, we provide a survey of recent and emerging topics in wireless networking. We view the area of wireless networking as dealing with problems of resource allocation so that the various connections that utilise the network achieve their desired performance objectives. In the first part of the paper, we first survey the area by providing a taxonomy of wireless networks as they have been deployed. Then, we provide a quick tutorial on the main issues in the wireless ‘physical’ layer, which is concerned with transporting bits over the radio frequency spectrum. Then, we proceed to discuss some resource allocation formulations in CDMA(code division multiple access) cellular networks and OFDMA(orthogonal frequency division multiple access) networks. In the second part of the paper, we first analyse random access wireless networks and pay special attention to 802·11 (Wi-Fi) networks.We then survey some topics in ad hoc multihop wireless networks, where we discuss arbitrary networks, as well as some theory of dense random networks. Finally, we provide an overview of the technical issues in the emerging area of wireless sensor networks.     

2D graphene supported nickel oxide nano-composite for fiber optic ethanol gas sensing,removal of azo dye,and biological activity

Journal of Materials Science: Materials in Electronics - Green synthesis of multifunctional metal oxide nanoparticles and its composites are widely evaluated for their efficacy in environmental and...     

Gap‐Mode Surface‐Plasmon‐Enhanced Photoluminescence and Photoresponse of MoS2

2D materials hold great potential for designing novel electronic and optoelectronic devices. However, 2D material can only absorb limited incident light. As a representative 2D semiconductor, monolayer MoS₂ can only absorb up to 10% of the incident light in the visible, which is not sufficient to achieve a high optical‐to‐electrical conversion efficiency. To overcome this shortcoming, a “gap‐mode” plasmon‐enhanced monolayer MoS₂ fluorescent emitter and photodetector is designed by squeezing the light‐field into Ag shell‐isolated nanoparticles–Au film gap, where the confined electromagnetic field can interact with monolayer MoS₂. With this gap‐mode plasmon‐enhanced configuration, a 110‐fold enhancement of photoluminescence intensity is achieved, exceeding values reached by other plasmon‐enhanced MoS₂ fluorescent emitters. In addition, a gap‐mode plasmon‐enhanced monolayer MoS₂ photodetector with an 880% enhancement in photocurrent and a responsivity of 287.5 A W^?1 is demonstrated, exceeding previously reported plasmon‐enhanced monolayer MoS₂ photodetectors.     

Spatiotemporal modelling of methane flux from the rice fields of India using remote sensing and GIS

Rice fields have been accredited as an important source of anthropogenic methane, with estimates of annual emission ranging from 47 to 60 Tg per year, representing 8.5–10.9% of total emission from all sources. In this study, attempts have been made to derive the spatial and temporal pattern of methane emitted from the rice lands of India using an integrated methodology involving satellite remote sensing and geographic information system (GIS) techniques. Multidate SPOT VGT 10‐day Normalized Difference Vegetation Index (NDVI) composite data for a complete year were used to map the rice area, delineate single‐ and double‐cropped rice areas, crop calendar and growth stages. Rainfall, digital elevation and irrigation data were integrated to stratify the rice area into distinct categories related to methane emission. Preliminary analysis of the methane emission pattern was carried out using published values. The results show that around 91% of total methane emission results from wet‐season rice, contributing 4.66 Tg per year. The temporal pattern shows that August and September are the months of peak emission during the wet season, and March and April during the dry season.     

Graph partitioning active contours (GPAC) for image segmentation

In this paper, we introduce new types of variational segmentation cost functions and associated active contour methods that are based on pairwise similarities or dissimilarities of the pixels. As a solution to a minimization problem, we introduce a new curve evolution framework, the graph partitioning active contours (GPAC). Using global features, our curve evolution is able to produce results close to the ideal minimization of such cost functions. New and efficient implementation techniques are also introduced in this paper. Our experiments show that GPAC solution is effective on natural images and computationally efficient. Experiments on gray-scale, color, and texture images show promising segmentation results.