The Experts below are selected from a list of 70887 Experts worldwide ranked by ideXlab platform
Shun Zhang - One of the best experts on this subject based on the ideXlab platform.
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segment training based Individual Channel estimation in one way relay network with power allocation
IEEE Transactions on Wireless Communications, 2013Co-Authors: Shun Zhang, Xiandeng HeAbstract:In this paper, we design a segment training based Individual Channel estimation (STICE) scheme in the classical three-node it amplify-and-forward (AF) one-way relay network (OWRN). The linear minimum mean-square-error (LMMSE) Channel estimator is used to obtain a good initialization, and an iterative maximum a posteriori (MAP) Channel estimator is developed to improve the estimation accuracy. We then investigate the underlying power allocation at the relay node both to minimize the mean-square-error (MSE) of the Individual Channel estimation and to maximize the average effective signal-to-noise ratio (AESNR) of the data detection. The closed-form Bayesian Cramer-Rao Bound (CRB) is also derived to evaluate the proposed algorithm. Finally, numerical results are provided to corroborate the proposed studies.
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optimal training design for Individual Channel estimation in two way relay networks
IEEE Transactions on Signal Processing, 2012Co-Authors: Shun Zhang, Feifei Gao, Changxing PeiAbstract:This correspondence considers the optimal training design in a classical three-node amplify-and-forward two-way relay network (TWRN) that targets at estimating the Individual Channel between each source node and the relay node. The transmission environment is assumed to be frequency selective and the orthogonal-frequency-division multiplexing (OFDM) modulation is adopted. We derive the Bayesian Cramer-Rao bound (CRB) for the Individual Channel estimation, from which the optimal training is obtained. Extensive numerical results are provided to corroborate the proposed studies.
Satish G Kandlikar - One of the best experts on this subject based on the ideXlab platform.
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water management studies in pem fuel cells part iv effects of Channel surface wettability geometry and orientation on the two phase flow in parallel gas Channels
International Journal of Hydrogen Energy, 2011Co-Authors: Zijie Lu, Cody Rath, Guangsheng Zhang, Satish G KandlikarAbstract:Abstract In this study, the effects of Channel surface wettability, cross-sectional geometry and orientation on the two-phase flow in parallel gas Channels of proton exchange membrane fuel cells (PEMFCs) are investigated. Ex situ experiments were conducted in flow Channels with three different surface wettability (hydrophilically coated, uncoated, and hydrophobically coated), three cross-sectional geometries (rectangular, sinusoidal and trapezoidal), and two orientations (vertical and horizontal). Flow pattern map, Individual Channel flow variation due to maldistribution, pressure drop and flow visualization images were used to analyze the two-phase flow characteristics. It is found that hydrophilically coated gas Channels are advantageous over uncoated or slightly hydrophobic Channels regarding uniform water and gas flow distribution and favoring film flow, the most desirable two-phase flow pattern in PEMFC gas Channels. Sinusoidal Channels favor film flow and have lower pressure drop than rectangular and trapezoidal Channels, while the rectangular and trapezoidal Channels behave similarly to each other. Vertical Channel orientation is advantageous over horizontal orientation because the latter is more prone to slug flow, nonuniform liquid water distribution and instable operation.
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uneven gas diffusion layer intrusion in gas Channel arrays of proton exchange membrane fuel cell and its effects on flow distribution
Journal of Power Sources, 2009Co-Authors: Satish G Kandlikar, Zijie Lu, Dwight Cooke, Michael M DainoAbstract:Intrusion of the gas diffusion layer (GDL) into gas Channels due to fuel cell compression has a major impact on the gas flow distribution, fuel cell performance and durability. In this work, the effect of compression resulting in GDL intrusion in Individual parallel PEMFC Channels is investigated. The intrusion is determined using two methods: an optical measurement in both the in-plane and through-plane directions of GDL, as well as an analytical fluid flow model based on Individual Channel flow rate measurements. The intrusion measurements and estimates obtained from these methods agree well with each other. An uneven distribution of GDL intrusion into Individual parallel Channels is observed. A non-uniform compression force distribution derived from the clamping bolts causes a higher intrusion in the end Channels. The heterogeneous GDL structure and physical properties may also contribute to the uneven GDL intrusion. As a result of uneven intrusion distribution, severe flow maldistribution and increased pressure drop have been observed. The intrusion data can be further used to determine the mechanical properties of GDL materials. Using the finite element analysis software program ANSYS, the Young's modulus of the GDL from these measurements is estimated to be 30.9 MPa.
Changxing Pei - One of the best experts on this subject based on the ideXlab platform.
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optimal training design for Individual Channel estimation in two way relay networks
IEEE Transactions on Signal Processing, 2012Co-Authors: Shun Zhang, Feifei Gao, Changxing PeiAbstract:This correspondence considers the optimal training design in a classical three-node amplify-and-forward two-way relay network (TWRN) that targets at estimating the Individual Channel between each source node and the relay node. The transmission environment is assumed to be frequency selective and the orthogonal-frequency-division multiplexing (OFDM) modulation is adopted. We derive the Bayesian Cramer-Rao bound (CRB) for the Individual Channel estimation, from which the optimal training is obtained. Extensive numerical results are provided to corroborate the proposed studies.
Zijie Lu - One of the best experts on this subject based on the ideXlab platform.
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water management studies in pem fuel cells part iv effects of Channel surface wettability geometry and orientation on the two phase flow in parallel gas Channels
International Journal of Hydrogen Energy, 2011Co-Authors: Zijie Lu, Cody Rath, Guangsheng Zhang, Satish G KandlikarAbstract:Abstract In this study, the effects of Channel surface wettability, cross-sectional geometry and orientation on the two-phase flow in parallel gas Channels of proton exchange membrane fuel cells (PEMFCs) are investigated. Ex situ experiments were conducted in flow Channels with three different surface wettability (hydrophilically coated, uncoated, and hydrophobically coated), three cross-sectional geometries (rectangular, sinusoidal and trapezoidal), and two orientations (vertical and horizontal). Flow pattern map, Individual Channel flow variation due to maldistribution, pressure drop and flow visualization images were used to analyze the two-phase flow characteristics. It is found that hydrophilically coated gas Channels are advantageous over uncoated or slightly hydrophobic Channels regarding uniform water and gas flow distribution and favoring film flow, the most desirable two-phase flow pattern in PEMFC gas Channels. Sinusoidal Channels favor film flow and have lower pressure drop than rectangular and trapezoidal Channels, while the rectangular and trapezoidal Channels behave similarly to each other. Vertical Channel orientation is advantageous over horizontal orientation because the latter is more prone to slug flow, nonuniform liquid water distribution and instable operation.
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uneven gas diffusion layer intrusion in gas Channel arrays of proton exchange membrane fuel cell and its effects on flow distribution
Journal of Power Sources, 2009Co-Authors: Satish G Kandlikar, Zijie Lu, Dwight Cooke, Michael M DainoAbstract:Intrusion of the gas diffusion layer (GDL) into gas Channels due to fuel cell compression has a major impact on the gas flow distribution, fuel cell performance and durability. In this work, the effect of compression resulting in GDL intrusion in Individual parallel PEMFC Channels is investigated. The intrusion is determined using two methods: an optical measurement in both the in-plane and through-plane directions of GDL, as well as an analytical fluid flow model based on Individual Channel flow rate measurements. The intrusion measurements and estimates obtained from these methods agree well with each other. An uneven distribution of GDL intrusion into Individual parallel Channels is observed. A non-uniform compression force distribution derived from the clamping bolts causes a higher intrusion in the end Channels. The heterogeneous GDL structure and physical properties may also contribute to the uneven GDL intrusion. As a result of uneven intrusion distribution, severe flow maldistribution and increased pressure drop have been observed. The intrusion data can be further used to determine the mechanical properties of GDL materials. Using the finite element analysis software program ANSYS, the Young's modulus of the GDL from these measurements is estimated to be 30.9 MPa.
Ravi Jain - One of the best experts on this subject based on the ideXlab platform.
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single longitudinal mode tunable wdm Channel selectable fiber laser
Optics Express, 2002Co-Authors: N J C Libatique, L Wang, Ravi JainAbstract:We report operation of a single-longitudinal-mode WDM-Channel-selectable fiber laser. The use of a tunable fiber Bragg grating and a linewidth narrowing saturable absorption filter in conjunction with an intracavity etalon enabled single-frequency emission and discretely tunable WDM Channel operation without the need for external wavelength locking modules. Side mode suppression ratios (SMSRs) > 50 dB have been demonstrated with ~ 3 dBm Individual Channel output powers for 8 Channel (Δf = 50 GHz) operation of this WDM source.