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Jason P Jue - One of the best experts on this subject based on the ideXlab platform.
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energy efficient translucent optical transport networks with mixed Regenerator placement
Journal of Lightwave Technology, 2012Co-Authors: Zuqing Zhu, Xiaoliang Chen, Liang Zhang, Farid Farahmand, Jason P JueAbstract:Translucent networks utilize sparse placements of optical-electronic-optical (O/E/O) 3R (reamplification, reshaping, and retiming) Regenerators to improve the cost effectiveness and energy efficiency of wavelength-routed optical transport networks. In this paper, we show that the energy cost of a translucent network can be further reduced by leveraging the energy efficiency of all-optical 2R (reamplification and reshaping) Regenerators. We propose a translucent network infrastructure that uses all-optical 2R Regenerators to partially replace O/E/O 3R Regenerators and implements mixed Regenerator placements (MRP). We first consider the problem of MRP along a single given path, and propose three path-based impairment-aware MRP algorithms, based on periodic placement, genetic algorithm (GA), and ant colony optimization (ACO). We then address the offline network planning problem and develop a heuristic algorithm. By incorporating with one of the proposed MRP algorithms, the heuristic can achieve joint optimization of MRP and routing and wavelength assignment for high energy efficiency. We design simulations to compare the performance of different offline network planning scenarios and to see which one can provide the best balance between quality of transmission and energy cost. Simulation results show that the algorithm achieves 58.91-73.62% saving on regeneration energy, compared to the traditional scheme without all-optical 2R Regenerators. The results also indicate that the joint optimization using the MRP-GA obtains the best network planning in terms of energy efficiency. Finally, we address the problem of online provisioning, and propose several algorithms to serve dynamic lightpath requests in translucent networks with MRP, and implement them in simulations to compare their performance in terms of blocking probability. Simulation results indicate that the online provisioning algorithm that utilizes the combination of the MRP-GA and a multiple MRP scheme achieves the lowest blocking probability.
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cost efficient traffic grooming and Regenerator placement in impairment aware optical wdm networks
Optical Switching and Networking, 2012Co-Authors: Ankitkumar N Patel, Chengyi Gao, Xi Wang, Qiong Zhang, Paparao Palacharla, Jason P Jue, Takao NaitoAbstract:Abstract In this paper, we address the problem of traffic grooming and Regenerator placement in a WDM optical network in which lightpaths are hop-constrained by physical impairments. The efficient placement of Regenerators and electronic grooming equipment at ROADM nodes for a given network topology is required such that all traffic demands can be supported with minimum cost. We present a detailed ROADM node architecture together with an associated cost model. We model the problem by Integer Linear Programming (ILPs) and propose an auxiliary-graph-based heuristic for jointly placing Regenerators and electronic grooming equipment in the network. To evaluate the performance of the proposed heuristic, we also derive a lower bound on the network cost. The numerical results show that combining the grooming problem with the placement of Regenerators reduces the network cost significantly compared to the cases in which traffic grooming and Regenerator placement are handled separately. The performance of the proposed polynomial-time heuristic is very close to the lower bound and approaches the bound as the network load increases.
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Regenerator placement and waveband routing in optical networks with impairment constraints
International Conference on Communications, 2011Co-Authors: Saket Varma, Jason P JueAbstract:Waveband networks allow multiple lightpaths to be aggregated and routed as wavebands, resulting in fewer switch ports. In an impairment-aware waveband network, a lightpath needs to be electronically regenerated before its signal to noise ratio reaches an unacceptable level. However, when a lightpath in a waveband needs to be regenerated the entire waveband needs to be demultiplexed into wavelengths resulting in additional wavelength ports at a node. Regenerator placement in a waveband network should be done so as to facilitate banding of lightpaths and to reduce the total cost of switch ports in the network. We formulate the Regenerator placement problem in an impairment constrained waveband network as an integer linear program (ILP). We compare the performance of the heuristics with an ILP for a small size network. Results demonstrate that the proposed band-aware reachability graph heuristic yields solution that are very close to the ILP. We study the performance of the heuristics on larger networks and study their effectiveness in reducing the combined cost of optical switch ports and electronic Regenerators.
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efficient impairment constrained 3r Regenerator placement for light trees in optical networks
IEEE\ OSA Journal of Optical Communications and Networking, 2011Co-Authors: Yi Zhu, Xiaofeng Gao, Jason P JueAbstract:Light-trees can efficiently guarantee point-to-multipoint connection in optical networks for many widely used multicast applications, such as Internet protocol television (IPTV). The establishment of a light-tree requires the placement of 3R Regenerators along the tree due to the wavelength continuity constraint and physical impairments. Thus, the problem is to establish a light-tree and to assign wavelengths such that the number of Regenerators is minimized. We call this problem the efficient 3R Regenerator placement (ERP) problem. If we fix the routing of the multicast tree, then how to place a minimum number of Regenerators and assign wavelengths to links becomes a subproblem of ERP, which is named the wavelength assignment and Regenerator placement (WARP) problem. We find that ERP is NP-hard, and then provide an approximation algorithm named SPT-ReWa, which has a subroutine named ReWa which can solve WARP optimally. We prove that ReWa can find an optimal solution for WARP, and we analyze the approximation ratio of SPT-ReWa for ERP. Finally, we illustrate several simulation scenarios to show the efficiency of SPT-ReWa.
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Survivable impairment-aware traffic grooming and Regenerator placement with shared connection-level protection
2011 13th International Conference on Transparent Optical Networks, 2011Co-Authors: Chengyi Gao, Hakki C Cankaya, Ankitkumar N Patel, Xi Wang, Qiong Zhang, Paparao Palacharla, Jason P Jue, Motoyoshi SekiyaAbstract:In this paper, we address the problem of survivable traffic grooming and Regenerator placement in optical WDM networks with impairment constraints. The working connections are protected end to end by provisioning bandwidth along a sequence of lightpaths by using a shared connection-level protection scheme. An auxiliary-graph-based approach is proposed to address the placement of Regenerators and grooming equipment for both working and shared backup connections in the network with the goal of minimizing the total equipment cost. Simulation results show that the proposed algorithm outperforms the dedicated connection-level protection algorithm as the load increases.
Jader R Barbosa - One of the best experts on this subject based on the ideXlab platform.
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Influence of inlet flow maldistribution and carryover losses on the performance of thermal Regenerators
Applied Thermal Engineering, 2018Co-Authors: P V Trevizoli, Guilherme F Peixer, Matheus S. Capovilla, Alan T.d. Nakashima, Jaime Lozano, Jader R BarbosaAbstract:Abstract Void (dead) volumes represent a penalty to the thermal performance of Active Magnetic Regenerators (AMR). While much effort has been put in designing AMRs with small void volumes, in most designs, penalties associated with inlet flow maldistribution and pressure loss may increase with the reduction of the void volumes. In this work, an experimental evaluation of the combined effect of void volume and inlet flow maldistribution is carried out. The analysis is performed based on the Regenerator thermal effectiveness determined experimentally in a passive Regenerator test apparatus. The results show that the negative impact of inlet flow maldistribution on the Regenerator effectiveness is more significant than that of the void volume.
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thermal hydraulic behavior and influence of carryover losses in oscillating flow Regenerators
International Journal of Thermal Sciences, 2017Co-Authors: P V Trevizoli, Jader R BarbosaAbstract:Abstract Thermal Regenerators that use a liquid as the heat transfer fluid are encountered in active-caloric (e.g., magnetocaloric, electrocaloric, elastocaloric) coolers/heat pumps and other applications. In this study, we present a mathematical model, its numerical implementation and comparisons with an extensive experimental database on the thermal performance of packed bed Regenerators composed of stainless steel spheres [1]. The Regenerator model consists of the one-dimensional Brinkman-Forchheimer equation to describe the fluid flow in the porous matrix and coupled energy equations to determine the temperatures in the fluid and solid phases. A mathematical model for the so-called carryover (leakage) losses provoked by the dead (void) volumes on each side of the Regenerator was implemented to improve the thermal effectiveness prediction. A good agreement between the mathematical model and the experimental data was observed, enabling an accurate quantification of thermal-hydraulic losses. The mathematical model and its results can be extended to and incorporated into performance analyses of active magnetic Regenerators.
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performance assessment of different porous matrix geometries for active magnetic Regenerators
Applied Energy, 2017Co-Authors: P V Trevizoli, Guilherme F Peixer, Alan T.d. Nakashima, Jader R BarbosaAbstract:Abstract The development of efficient active magnetic Regenerators (AMR) is highly dependent on the regenerative matrix thermal performance. Matrix geometries should have a high thermal effectiveness and small thermal and viscous losses. In this study, we present a systematic experimental evaluation of three different Regenerator geometries: parallel-plate, pin array and packed bed of spheres. All matrices were fabricated with approximately the same porosity (between 0.36 and 0.37). The cross sectional area and length of the Regenerator beds are identical, resulting in the same interstitial area. Hence, any difference in performance between the matrices is due to interstitial heat transfer between the solid and the fluid and losses related to thermal, viscous and magnetic effects. As a means to quantify these losses individually, experiments were first conducted using stainless steel matrices without the application of a magnetic field (passive Regenerator mode). Later, gadolinium matrices made with the same characteristics as the stainless steel ones were evaluated in an AMR test apparatus for which experimental results of cooling capacity, temperature span between the thermal reservoirs, coefficient of performance and second-law efficiency were generated as a function of utilization for different operating frequencies. Parallel plates had the poorest performance, while the packed bed of spheres presented the highest cooling capacity. On the other hand, the packed bed also had the highest viscous losses. For this reason, the pin array exhibited the highest COP and second-law efficiency.
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thermal hydraulic evaluation of oscillating flow Regenerators using water experimental analysis of packed beds of spheres
International Journal of Heat and Mass Transfer, 2016Co-Authors: P V Trevizoli, Guilherme F Peixer, Jader R BarbosaAbstract:Thermal Regenerators that use liquid heat transfer fluids are being researched for their application in active caloric cooling/heat pumping systems. The performance of active caloric devices is significantly influenced by the Regenerator thermal effectiveness and by viscous losses. The present paper is the first part of a study on the thermal–hydraulic evaluation of packed bed Regenerators that use water as a thermal fluid. Here, a detailed experimental analysis of the thermal–hydraulic performance of regenerative matrices composed of packed beds of stainless steel spheres is carried out. A laboratory apparatus was developed to quantify the viscous losses and thermal effectiveness in oscillating-flow Regenerators that use water as the heat transfer fluid. Operating parameters such as frequency and mass flow rate were varied to cover broad ranges of utilization and number of transfer units (NTU). The diameter of the spherical particles and the dimensions of the Regenerator housing were also changed in order to evaluate their influence on the behavior of the time-dependent and time-average performance parameters.
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entropy generation minimization analysis of oscillating flow Regenerators
International Journal of Heat and Mass Transfer, 2015Co-Authors: P V Trevizoli, Jader R BarbosaAbstract:Abstract The thermodynamic efficiencies of regenerative cooling cycles are directly linked to the heat transfer effectiveness and thermal losses in the Regenerator. This paper proposes a performance analysis for Regenerators based on the Entropy Generation Minimization (EGM) theory. The mathematical model consists of the one-dimensional Brinkman–Forchheimer equation to describe the fluid flow in the porous matrix and coupled energy equations to determine the temperatures in the fluid and solid phases. The cycle-average entropy generation contributions due to axial heat conduction, fluid friction and interstitial heat transfer are calculated. The influences of parameters such as the mass flow rate, operating frequency, Regenerator cross sectional area, housing aspect ratio, utilization factor and particle diameter are evaluated according to the variable geometry (VG) and fixed face (cross-section) area (FA) performance evaluation criteria (PEC). Optimal Regenerator configurations are found for each PEC for flow rates between 40 and 300 kg/h (0.01 and 0.083 kg/s) and frequencies between 1 and 4 Hz with constraints of Regenerator effectiveness equal to 95% and temperature span of 40 K.
P V Trevizoli - One of the best experts on this subject based on the ideXlab platform.
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experimental characterization of multilayer active magnetic Regenerators using first order materials multiple points of equilibrium
Journal of Applied Physics, 2018Co-Authors: P Govindappa, P V Trevizoli, I Niknia, T V Christiaanse, R Teyber, A RoweAbstract:Multiplepoints of equilibrium (MPE) have recently been observed in single layer active magnetic Regenerators (AMRs) using first order magnetic materials (FOMs). Here, we describe experiments using three multilayer MnFeP1-xAsx FOM Regenerator beds characterized under a range of applied loads and rejection temperatures. Thermal performance and the impacts of MPE are evaluated via heating and cooling experiments where the rejection (hot side) temperature is varied in a range from 283 K to 300 K. With fixed operating conditions, we find multiple points of equilibrium for steady-state spans as a function of warm rejection temperature. The results indicate a significant impact of MPE on the heating and cooling temperature span for a multilayer MnFeP1-xAsx FOM Regenerator. Unlike single material FOM tests where MPEs tend to disappear as load is increased (or span reduced), with the layered AMRs, MPEs can be significant even with small temperature span conditions.Multiplepoints of equilibrium (MPE) have recently been observed in single layer active magnetic Regenerators (AMRs) using first order magnetic materials (FOMs). Here, we describe experiments using three multilayer MnFeP1-xAsx FOM Regenerator beds characterized under a range of applied loads and rejection temperatures. Thermal performance and the impacts of MPE are evaluated via heating and cooling experiments where the rejection (hot side) temperature is varied in a range from 283 K to 300 K. With fixed operating conditions, we find multiple points of equilibrium for steady-state spans as a function of warm rejection temperature. The results indicate a significant impact of MPE on the heating and cooling temperature span for a multilayer MnFeP1-xAsx FOM Regenerator. Unlike single material FOM tests where MPEs tend to disappear as load is increased (or span reduced), with the layered AMRs, MPEs can be significant even with small temperature span conditions.
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Influence of inlet flow maldistribution and carryover losses on the performance of thermal Regenerators
Applied Thermal Engineering, 2018Co-Authors: P V Trevizoli, Guilherme F Peixer, Matheus S. Capovilla, Alan T.d. Nakashima, Jaime Lozano, Jader R BarbosaAbstract:Abstract Void (dead) volumes represent a penalty to the thermal performance of Active Magnetic Regenerators (AMR). While much effort has been put in designing AMRs with small void volumes, in most designs, penalties associated with inlet flow maldistribution and pressure loss may increase with the reduction of the void volumes. In this work, an experimental evaluation of the combined effect of void volume and inlet flow maldistribution is carried out. The analysis is performed based on the Regenerator thermal effectiveness determined experimentally in a passive Regenerator test apparatus. The results show that the negative impact of inlet flow maldistribution on the Regenerator effectiveness is more significant than that of the void volume.
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thermal hydraulic behavior and influence of carryover losses in oscillating flow Regenerators
International Journal of Thermal Sciences, 2017Co-Authors: P V Trevizoli, Jader R BarbosaAbstract:Abstract Thermal Regenerators that use a liquid as the heat transfer fluid are encountered in active-caloric (e.g., magnetocaloric, electrocaloric, elastocaloric) coolers/heat pumps and other applications. In this study, we present a mathematical model, its numerical implementation and comparisons with an extensive experimental database on the thermal performance of packed bed Regenerators composed of stainless steel spheres [1]. The Regenerator model consists of the one-dimensional Brinkman-Forchheimer equation to describe the fluid flow in the porous matrix and coupled energy equations to determine the temperatures in the fluid and solid phases. A mathematical model for the so-called carryover (leakage) losses provoked by the dead (void) volumes on each side of the Regenerator was implemented to improve the thermal effectiveness prediction. A good agreement between the mathematical model and the experimental data was observed, enabling an accurate quantification of thermal-hydraulic losses. The mathematical model and its results can be extended to and incorporated into performance analyses of active magnetic Regenerators.
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performance assessment of different porous matrix geometries for active magnetic Regenerators
Applied Energy, 2017Co-Authors: P V Trevizoli, Guilherme F Peixer, Alan T.d. Nakashima, Jader R BarbosaAbstract:Abstract The development of efficient active magnetic Regenerators (AMR) is highly dependent on the regenerative matrix thermal performance. Matrix geometries should have a high thermal effectiveness and small thermal and viscous losses. In this study, we present a systematic experimental evaluation of three different Regenerator geometries: parallel-plate, pin array and packed bed of spheres. All matrices were fabricated with approximately the same porosity (between 0.36 and 0.37). The cross sectional area and length of the Regenerator beds are identical, resulting in the same interstitial area. Hence, any difference in performance between the matrices is due to interstitial heat transfer between the solid and the fluid and losses related to thermal, viscous and magnetic effects. As a means to quantify these losses individually, experiments were first conducted using stainless steel matrices without the application of a magnetic field (passive Regenerator mode). Later, gadolinium matrices made with the same characteristics as the stainless steel ones were evaluated in an AMR test apparatus for which experimental results of cooling capacity, temperature span between the thermal reservoirs, coefficient of performance and second-law efficiency were generated as a function of utilization for different operating frequencies. Parallel plates had the poorest performance, while the packed bed of spheres presented the highest cooling capacity. On the other hand, the packed bed also had the highest viscous losses. For this reason, the pin array exhibited the highest COP and second-law efficiency.
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thermal hydraulic evaluation of oscillating flow Regenerators using water experimental analysis of packed beds of spheres
International Journal of Heat and Mass Transfer, 2016Co-Authors: P V Trevizoli, Guilherme F Peixer, Jader R BarbosaAbstract:Thermal Regenerators that use liquid heat transfer fluids are being researched for their application in active caloric cooling/heat pumping systems. The performance of active caloric devices is significantly influenced by the Regenerator thermal effectiveness and by viscous losses. The present paper is the first part of a study on the thermal–hydraulic evaluation of packed bed Regenerators that use water as a thermal fluid. Here, a detailed experimental analysis of the thermal–hydraulic performance of regenerative matrices composed of packed beds of stainless steel spheres is carried out. A laboratory apparatus was developed to quantify the viscous losses and thermal effectiveness in oscillating-flow Regenerators that use water as the heat transfer fluid. Operating parameters such as frequency and mass flow rate were varied to cover broad ranges of utilization and number of transfer units (NTU). The diameter of the spherical particles and the dimensions of the Regenerator housing were also changed in order to evaluate their influence on the behavior of the time-dependent and time-average performance parameters.
Benjamin J Eggleton - One of the best experts on this subject based on the ideXlab platform.
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bit error ratio improvement with 2r optical Regenerators
IEEE Photonics Technology Letters, 2005Co-Authors: Martin Rochette, J N Kutz, Justin L Blows, David J Moss, Benjamin J EggletonAbstract:We show that an all-optical optical Regenerator can improve the bit-error ratio (BER) of a signal passing through it only if the Regenerator has different power transfer functions for the logical ones and logical zeros. A Regenerator that operates with a single transfer function-which constitute most of optical Regenerators reported in the literature-cannot improve the BER, but can only reduce the BER degradation when, for example, placed before optical amplifiers. Of all the optical Regenerators reported to date, only the one proposed by Mamyshev, based on filtering a self-phase modulated signal, has different transfer functions for the logical ones and the logical zeros. This makes the Mamyshev scheme a superior candidate for ultrahigh-speed all-optical regeneration.
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bit error ratio improvement with 2r optical Regenerators
IEEE Photonics Technology Letters, 2005Co-Authors: Martin Rochette, J N Kutz, Justin L Blows, David J Moss, Joe T Mok, Benjamin J EggletonAbstract:We show that an all-optical optical Regenerator can improve the bit-error ratio (BER) of a signal passing through it only if the Regenerator has different power transfer functions for the logical ones and logical zeros. A Regenerator that operates with a single transfer function-which constitute most of optical Regenerators reported in the literature-cannot improve the BER, but can only reduce the BER degradation when, for example, placed before optical amplifiers. Of all the optical Regenerators reported to date, only the one proposed by Mamyshev, based on filtering a self-phase modulated signal, has different transfer functions for the logical ones and the logical zeros. This makes the Mamyshev scheme a superior candidate for ultrahigh-speed all-optical regeneration.
Artur J Jaworski - One of the best experts on this subject based on the ideXlab platform.
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selection and experimental evaluation of low cost porous materials for Regenerator applications in thermoacoustic engines
Materials & Design, 2011Co-Authors: Abdulrahman S Abduljalil, Artur J JaworskiAbstract:Abstract This paper aims at evaluating three selected low-cost porous materials from the point of view of their suitability as Regenerator materials in the design of thermoacoustic travelling-wave engines. The materials tested include: a cellular ceramic substrate with regular square channels; steel “scourers”; and stainless steel “wool”. Comparisons are made against a widely used Regenerator material: stainless steel woven wire mesh screen. For meaningful comparisons, the materials are selected to have similar hydraulic radii. One set of Regenerators was designed around the hydraulic radius of 200 μm. This included the ceramic substrate, steel “scourers”, stainless steel “wool” and stacked wire screens (as a reference). This set was complemented by steel “scourers” and stacked wire screens (as a reference) with hydraulic radii of 120 μm. Therefore six Regenerators were produced to carry out the testing. Initial tests were made in a steady air flow to estimate their relative pressure drop due to viscous dissipation. Subsequently, they were installed in a looped-tube travelling-wave thermoacoustic engine to test their relative performance. Testing included the onset temperature difference, the maximum pressure amplitude generated and the acoustic power output as a function of mean pressure between 0 and 10 bar above atmospheric. It appears that the performance of Regenerators made out of “scourers” and steel “wool” is much worse than their mesh-screen counterparts of the same hydraulic radius. However cellular ceramics may offer an alternative to traditional Regenerator materials to reduce the overall system costs. Detailed discussions are provided.
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impact of acoustic impedance and flow resistance on the power output capacity of the Regenerators in travelling wave thermoacoustic engines
Energy Conversion and Management, 2010Co-Authors: Artur J JaworskiAbstract:Abstract This paper considers the role of acoustic impedance, flow resistance, configuration and geometrical dimensions of Regenerators on the power produced in travelling-wave thermoacoustic engines. The effects are modelled assuming a pure travelling-wave and ideal gas, which allows defining a pair of dimensionless factors based on the “net” acoustic power production. Based on the analysis provided, the acoustic power flow in the Regenerators is investigated numerically. It is shown that impedance essentially reflects the proportion between the acoustic power produced from heat energy through the thermoacoustic processes and the acoustic power dissipated by viscous and thermal-relaxation effects in the Regenerators. Viscous resistance of the Regenerator mainly determines the magnitude of the volumetric velocity and then affects the magnitude of acoustic impedance. High impedance and high volumetric velocity are both required in the Regenerators for high power engines. The results also show that the optimum transverse dimension of the gas passage exists, but depends on the local acoustic impedance. In principle, it is possible to obtain an optimum combination between these two parameters.
