The Experts below are selected from a list of 22188 Experts worldwide ranked by ideXlab platform

Minho Kang - One of the best experts on this subject based on the ideXlab platform.

  • Fair Bandwidth Allocation Using Effective Multicast Traffic Share in TDM-PONs
    Journal of Lightwave Technology, 2008
    Co-Authors: Namuk Kim, Hynu-su Lim, Minho Kang
    Abstract:

    In this paper, the effects of optical traffic-sharing on the performance of multicast video delivery in terms of the efficiency of bandwidth allocation and the fairness of link-sharing are discussed for the Downstream Direction of a time-division-multiplexed passive optical network (TDM-PON). We analyze the practical issues associated with multicast packet switching and transmission control in a TDM-PON and also propose a fair bandwidth allocation mechanism, called share-based proportional bandwidth allocation (S-PBA), to effectively support multicast services. In order to provide an optical network unit with a fair amount of link bandwidth and high throughput independent of traffic type, S-PBA arbitrates the amount of unicast timeslot by using effective multicast traffic share, which is determined based on multicast traffic load distribution and traffic-sharing density. Analytic and simulation results clearly validate the effectiveness of the proposed mechanism. This work is applicable to multicast video delivery or multicast traffic transmission in general, such as voice traffic, or a combination of both in the case of video conferencing, for example.

A H H Tan - One of the best experts on this subject based on the ideXlab platform.

  • super pon a fiber to the home cable network for catv and pots isdn vod as economical as a coaxial cable network
    Journal of Lightwave Technology, 1997
    Co-Authors: A H H Tan
    Abstract:

    A complete super PON fiber to the home cable network as economical as the classic coaxial cable network, designed for application in the local loop is presented. The concept uses high power lasers, remote pumped erbium doped fiber amplifiers (EDFAs) to reduce cost by high splitting ratio, economical receivers for the Downstream Direction and economical CD player lasers for the upstream Direction. Several novel technical solutions for this application (a new method to avoid stimulated Brillouin scattering (SBS), remote pumping of the EDFA and a compensating technique to adapt the CD laser to the normal fiber) are presented.

Dierk Raabe - One of the best experts on this subject based on the ideXlab platform.

  • lattice boltzmann modeling of dendritic growth in a forced melt convection
    Acta Materialia, 2009
    Co-Authors: Dongke Sun, Mingfang Zhu, Shiyan Pan, Dierk Raabe
    Abstract:

    Abstract A two-dimensional (2D) lattice Boltzmann-based model is developed to simulate solutal dendritic growth of binary alloys in the presence of forced flow. The model adopts the lattice Boltzmann method (LBM) that describes transport phenomena by the evolution of distribution functions of moving pseudoparticles to numerically solve fluid flow and solute transport governed by both convection and diffusion. Based on the LBM-calculated solutal field, the dynamics of dendritic growth is determined according to a previously proposed local solutal equilibrium approach. After detailed model analysis and validation, the model is applied to simulate single and equiaxed multidendritic growth of Al–Cu alloys with forced convection. The results demonstrate the quantitative, numerically stable and computationally efficient capabilities of the proposed model. It is found that the solute distribution and dendritic growth are strongly influenced by convection, producing asymmetrical dendrites that grow faster in the upstream Direction, but mostly slower in the Downstream Direction.

Wei Tang - One of the best experts on this subject based on the ideXlab platform.

  • a global model on temperature profile of buoyant ceiling gas flow in a channel with combining mass and heat loss due to ceiling extraction and longitudinal forced air flow
    International Journal of Heat and Mass Transfer, 2014
    Co-Authors: Longhua Hu, Longfei Chen, Wei Tang
    Abstract:

    Abstract This paper investigates temperature profiles of buoyancy-driven gas flow (both upstream and Downstream) beneath a channel ceiling with combining heat and mass loss due to ceiling extraction (right above the buoyancy source) and longitudinal forced air flow. Experiments are conducted in a large scale model channel with dimensions of 72 m (length) × 1.5 m (width) × 1.3 m (height). The gas temperature profiles beneath the channel ceiling are measured by K-type thermocouples. Computational Fluid Dynamics (CFD) Large Eddy Simulations (LES) are carried out correspondingly by Fire Dynamics Simulator (FDS). It is found that: (a) with ceiling extraction only, the gas temperature profiles along the ceiling are symmetrically similar for upstream and Downstream; and both decay faster longitudinally with increase in ceiling mass extraction velocity; however (b) with both ceiling extraction and longitudinal forced air flow, the gas temperature decays faster upstream than that Downstream. A global model is theoretically proposed to describe the gas temperature profiles in both upstream and Downstream Direction with combination of mass and heat loss due to ceiling extraction and longitudinal forced air flow. Its predictions are in good agreement with measured values and CFD simulation results.

Mcclain Michael - One of the best experts on this subject based on the ideXlab platform.

  • Morphodynamic trends of the Ribb River, Ethiopia, prior to dam construction
    2018
    Co-Authors: Mulatu C.a., Crosato A., Moges, Michael M., Langendoen, Eddy J., Mcclain Michael
    Abstract:

    The meandering Ribb River flows in northwest Ethiopia to Lake Tana, the source of the Blue Nile River. The river has already undergone changes due to several human interventions, such as embanking, sand mining, water extraction and lake level regulation for hydropower. At present, a dam and a weir are under construction to store and divert water for irrigation. This will strongly alter both water and sediment discharges to the Downstream river reaches, causing adjustments to the morphology. Assessing the current morphodynamic trends is the first necessary step to study the future effects and find ways to mitigate them. This paper presents an analysis of the current and past river based on newly collected data, aerial photographs, SPOT and Google Earth images. The riverbed changes are derived from historical staff gauge height analysis. The effects of sediment mining and water extraction are assessed using the theory of morphodynamic equilibrium. The findings of the analysis show a reduction of sediment transport capacity in the Downstream Direction, which has resulted in intense sediment deposition, resulting in blockage of the Lower River reach and subsequent channel avulsion. The effects of Lake Tana level regulation on the observed processes appear to be minor.

  • Morphodynamic trends of the Ribb River, Ethiopia, prior to dam construction
    'MDPI AG', 2018
    Co-Authors: Mulatu C.a., Crosato A., Moges, Michael M., Langendoen, Eddy J., Mcclain Michael
    Abstract:

    The meandering Ribb River flows in northwest Ethiopia to Lake Tana, the source of the Blue Nile River. The river has already undergone changes due to several human interventions, such as embanking, sand mining, water extraction and lake level regulation for hydropower. At present, a dam and a weir are under construction to store and divert water for irrigation. This will strongly alter both water and sediment discharges to the Downstream river reaches, causing adjustments to the morphology. Assessing the current morphodynamic trends is the first necessary step to study the future effects and find ways to mitigate them. This paper presents an analysis of the current and past river based on newly collected data, aerial photographs, SPOT and Google Earth images. The riverbed changes are derived from historical staff gauge height analysis. The effects of sediment mining and water extraction are assessed using the theory of morphodynamic equilibrium. The findings of the analysis show a reduction of sediment transport capacity in the Downstream Direction, which has resulted in intense sediment deposition, resulting in blockage of the Lower River reach and subsequent channel avulsion. The effects of Lake Tana level regulation on the observed processes appear to be minor.Water ResourcesEnvironmental Fluid Mechanic