1,235 research outputs found
Bandwidth Allocation and Routing Information for Wireless Mobile Ad-hoc Networks
An admission control Algorithm must organize among flows and should afford assurance of how the medium is shared between nodes. In a wired network, nodes can keep an eye on the medium to see how much bandwidth is being used by the network. On the other hand, in an Ad-Hoc network, during communication nodes possibly will use the bandwidth of neighbouring nodes. Consequently, the bandwidth consumption of flows and the accessible resources to a node are not local concepts, other than it being linked to the neighbouring nodes in carrier-sensing range. Current solutions do not address how to perform admission control in such an environment so that the admitted flows in the network do not exceed network capacity. Here I present an application to demonstrate how the bandwidth is shared between nodes and the effectiveness of admission control framework to support QoS in Ad-Hoc networks
Evaluation of Antioxidant Property and Toxicological Assessment of Polyalthia Longifolia var. Pendula Leaf
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On the study of balanced incomplete block designs with repeated blocks and other incomplete block designs
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Evaluation of antioxidant propery and toxicological assessment of polyalthia longifolia var. pendula leaf
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Modeling of non-uniform hydrodynamics and catalytic reaction in a solids-laden riser
The riser reactors are widely used in a variety of industrial applications such as polymerization, coal combustion and petroleum refinery because of the strong mixing of gas and solids that yields high heat and mass transfer rates, and reaction rates. In a Fluid Catalytic Cracking (FCC) process, the performance of riser reactor is strongly dependent on the interaction between the fluid and catalysts, since the reaction takes place on the active surface of the catalysts. This is why, the local coupling between hydrodynamics and reaction kinetics is critical to the development of riser reaction models. The local gas-solids flow structure in riser reactors is highly heterogeneous both in axial and radial direction with back-mixing of catalyst. The radial non-uniform gas-solid flow structure is presented as core-annulus regime, with up-flow of dilute suspension of fresh catalyst and hydrocarbon vapor in the core regime, which is surrounded by dense down-flow of deactivated catalyst in the wall regime. As a result, the reaction characteristics in core and wall regions are strikingly different. The performance of the riser reactor is also strongly dependent on the vaporization and reaction characteristics in the feed injection regime of the riser reactors. From the modeling point of view, to predict the reaction characteristics in riser reactors, there is a need to develop hydrodynamics model, which can predicts both axial and radial nonuniform distribution of hydrocarbon vapor and catalyst and back-mixing of catalyst. There is also need for reasonable description of mechanistic coupling between nonuniform flow hydrodynamics and the cracking kinetics.
This dissertation is aimed to develop the mechanistic model for nonuniform hydrodynamics and catalytic reactions in a FCC riser reactor. A mechanistic model for multiphase flow interactions, vaporization of droplets and reactions in the feed injection regime is developed for to decide proper input boundary conditions for FCC riser reaction models. The dissertation is divided into the three major parts: 1) development of governing mechanisms and modeling of the axial and radial nonuniform distribution of the gas-solids transport properties in riser reactors 2) development of mechanistic model that gives a quantitative understanding of the interplay of three phase flow hydrodynamics, heat/mass transfer, and cracking reactions in the feed injection regime of a riser reactor 3) modeling of nonuniform hydrodynamics coupled reaction kinetics in the core and wall regime of the riser reactors.
For the modeling of the axial nonuniform distribution of gas-solids transport properties, a new controlling mechanism in terms of impact of pressure gradient along the riser on the particles transport is introduced. A correlation for inter-particle collision force is proposed which can be used for any operation conditions of riser, riser geometry and particle types. For simultaneous modeling of axial and radial nonuniform distribution of the gas-solids phase transport properties, a continuous modeling approach is used. In this dissertation, governing mechanisms for radial nonuniform distribution of gas-solids phase is proposed based on which a mechanistic model for radial nonuniform distribution of the gas and solid phase transport properties is proposed. With the proposed model for radial nonuniform phase distribution, the continuous model can successfully predicts both axial and radial nonuniform distribution of phase transport properties.
As the performance of the riser reactor is strongly influence by the vaporization and reactions in the feed injection regime, in this dissertation, a detailed mechanistic model for the multiphase flow hydrodynamics, vaporization and reaction characteristics in feed injection regime is established. To simulate the conditions of industrial riser reactor, the four nozzle spray jets were used, while overlapping of the spray jets is also considered.
Finally, in this dissertation, a modeling concept for the reactions in the core and wall regime of the riser reactor is explored. The proposed modeling concept takes into the account very important missed out physics such as, non-thermal equilibrium between the hydrocarbon vapor and the feed, back mixing and recirculation of the deactivated catalyst, activity of catalyst in core and wall regime, and coupling between the flow hydrodynamics and reaction kinetics
Synthesis of silver nanoparticles using fresh bark of Pongamia pinnata and characterization of its antibacterial activity against gram positive and gram negative pathogens
The recent advancements in techniques for synthesis of zerovalent nanoparticles using green method show a clean, simple, less toxic and environmentally benign process. In this communication, silver nanoparticles were synthesized and characterized using the fresh bark extract of Pongamia pinnata. The bark extract was exposed to silver ions and the resultant biosynthesized silver nanoparticles characterized by UV-vis spectrophotometry shows the surface plasmon resonance band at 420 nm. X-ray diffraction spectrum shows crystalline structure while scanning electron microscope and transmission electron microscope analyses revealed the polydisperse distribution and particle size of 5-55 nm. The elemental analysis shows strong signal at 3 keV that corresponds to silver ions and confirms the presence of metallic silver. The antibacterial activity of silver nanoparticles was determined by agar well diffusion method against gram positive and gram negative bacteria. Maximum and minimum zones of inhibition were noted against Klebsiella planticola (15 mm) and Staphylococcus aureus (13 mm), respectively. This study reveals that silver nanoparticles possess good antibacterial activity at 100 μg/ml concentration
Xeroderma Pigmentosum A Deficiency Results in Increased Generation of Microvesicle Particles in Response to Ultraviolet B Radiation
Xeroderma Pigmentosum is a genetic disorder in which ability to repair DNA damage such as from UV radiation is decreased. Nucleotide excision repair is known for repairing DNA damage caused by UV radiation and XPA plays a major role in recognizing and eliminating abnormal section of DNA. Therefore, XPA deficiency decreases repair efficiency of DNA. Of note, XPA deficiency is linked with photosensitivity. Microvesicle particles are membrane-bound particles which are released into the extracellular environment in response to multiple stimuli including the lipid Platelet activating factor (PAF). Previous studies have shown that XPA deficiency can induce increase production of reactive oxygen species and generates large amounts of PAF agonists produced non-enzymatically. Hence, the present studies are designed to study if XPA deficiency induces higher UVB-MVP release via PAF-R signaling pathway. Studies involving a XPA- deficient keratinocyte cell-line were able to show that UVB irradiation can cause increase MVP release. Similarly, XPA knockout (KO) mice generated increased MVP with UVB irradiation both in skin as well as plasma in comparison to wild-type mice. Increased production of cytokines (TNF-alpha and IL-6) were also seen in XPA KO mice. However, absence of XPA did not affect MVP release when treated with PAF-R agonist or phorbol ester TPA. Topical application of the acid sphingomyelinase (aSMase) inhibitor imipramine was able to inhibit UVB induced MVP release and pro-inflammatory cytokines. Likewise, genetically knocking down aSMase affected MVP release by UVB irradiation in comparison to wild-type and XPA KO mice. As MVP been involved in UVB signaling, inhibiting MVP release by pharmacological means might be a novel therapeutic approach in photosensitive conditions
Development and validation of a two-phase computational model for an alternative fire suppression agent
[ES] Halon1301 se ha utilizado como agente de extinción de incendios en sistemas activos de extinción de incendios en motores de aviones, APU (Unidad de potencia auxiliar) y protección contra incendios de carga durante más de 50 años. En 1987, una investigación realizada por el Protocolo de Montreal muestra que Halon está dañando el medio ambiente debido a sus propiedades que agotan el ozono. Por lo tanto, el uso de gases de halón ha sido prohibido en la industria por el protocolo de Montreal (1994) y Kyoto (1998). Por lo tanto, es el reemplazo de gases de halón lo que es más ecológico. Entre estas alternativas, Novec-1230 es una alternativa sostenible que funciona de manera rápida, limpia y eficiente. El sistema de extinción de incendios requiere que se diluya una concentración específica del agente de extinción de incendios (4-6% para Novec-1230 y 5% para Halon) en el aire para extinguir el fuego. El problema de cambiar la fase de la niebla rápidamente despresurizada de un sistema de extinción de incendios es un tema de gran interés debido al efecto del modelado de estos fenómenos en una simulación exitosa para diseñar estas modificaciones. Debido a la gran diferencia de presiones entre el recipiente y el ambiente, se espera que la descarga a través de la boquilla sea crítica. En este informe, se utilizan dos agentes de supresión de incendios alternativos diferentes y dos boquillas: agua y Novec1230.
El objetivo principal de este proyecto es desarrollar un nuevo modelo de subcuadrícula para un U-RANS CFD Euleriano-Euleriano de dos fases que pueda usarse para reducir el costo computacional y aumentar la precisión de los enfoques tradicionales basados en Eulerian-Lagrangian. Estos dos enfoques se realizan con el software comercial CFD (ANSYS Fluent). Como validación, los rendimientos de pulverización como la forma de pulverización, el ángulo del cono de pulverización se comparan con los resultados experimentales.[EN] Halon1301 has been used as a fire suppression agent in active fire extinction systems in aircraft engines, APU (Auxiliary Power Unit) and cargo fire protection for more than 50 years. In 1987, a research carried out by the Montreal Protocol shows that Halon is damaging the environment because of its ozone-depleting properties. Therefore, the use of Halon gases has been banned in the industry by the Montreal (1994) and Kyoto (1998) protocol. So, it is indeed to find replacement of halon gases which is more eco friendly. Among these alternatives, Novec-1230 is a sustainable alternative that works quickly, cleanly and efficiently. The fire suppression system requires a specific concentration of the fire suppression agent (4-6 % for Novec-1230 and 5% for Halon) to be diluted in the air to extinguish the fire. The problem of changing the phase of the rapidly depressurized mist of a fire suppression system is a topic of high interest due to the effect of the modelling of these phenomena in a successful simulation to design these modifications. Due to the high difference of pressures between the container and the ambient, the discharge through the nozzle is expected to be critical. In this report, two different alternative fire suppression agents and two nozzles are used - Water and Novec1230.
The main goal of this project is to develop a new sub-grid model for a two-phase Eulerian-Eulerian CFD U-RANS that can be used to reduce the computational cost and increase the accuracy of traditional approaches based on Eulerian-Lagrangian. These two approaches are performed with CFD commercial software (ANSYS Fluent). As validation, spray performances such as spray shape, spray cone angle are compared with experimental results.Shaparia, NR. (2020). Development and validation of a two-phase computational model for an alternative fire suppression agent. Universitat Politècnia de València. http://hdl.handle.net/10251/157474TFG
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