The Experts below are selected from a list of 13776 Experts worldwide ranked by ideXlab platform
R W Mair - One of the best experts on this subject based on the ideXlab platform.
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the Narrow Pulse approximation and long length scale determination in xenon gas diffusion nmr studies of model porous media
Journal of Magnetic Resonance, 2002Co-Authors: R W Mair, Martin D Hurlimann, Samuel Patz, David G Cory, Ronald L WalsworthAbstract:Abstract We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient Pulses in a PGSE experiment (breakdown of the Narrow Pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient Pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (∼1–1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Padelength), which is found to be ∼0.13b for all bead packs, where b is the bead diameter.
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the Narrow Pulse approximation and long length scale determination in xenon gas diffusion nmr studies of model porous media
Journal of Magnetic Resonance, 2002Co-Authors: R W Mair, Martin D Hurlimann, Samuel Patz, David G Cory, Pabitra N Sen, Ronald L WalsworthAbstract:We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient Pulses in a PGSE experiment (breakdown of the Narrow Pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient Pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (approximately 1-1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Pade length), which is found to be approximately 0.13b for all bead packs, where b is the bead diameter.
Ronald L Walsworth - One of the best experts on this subject based on the ideXlab platform.
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the Narrow Pulse approximation and long length scale determination in xenon gas diffusion nmr studies of model porous media
Journal of Magnetic Resonance, 2002Co-Authors: R W Mair, Martin D Hurlimann, Samuel Patz, David G Cory, Ronald L WalsworthAbstract:Abstract We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient Pulses in a PGSE experiment (breakdown of the Narrow Pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient Pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (∼1–1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Padelength), which is found to be ∼0.13b for all bead packs, where b is the bead diameter.
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the Narrow Pulse approximation and long length scale determination in xenon gas diffusion nmr studies of model porous media
Journal of Magnetic Resonance, 2002Co-Authors: R W Mair, Martin D Hurlimann, Samuel Patz, David G Cory, Pabitra N Sen, Ronald L WalsworthAbstract:We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient Pulses in a PGSE experiment (breakdown of the Narrow Pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient Pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (approximately 1-1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Pade length), which is found to be approximately 0.13b for all bead packs, where b is the bead diameter.
S Y Tseng - One of the best experts on this subject based on the ideXlab platform.
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Wide Pulse Combined With Narrow-Pulse Generator for Food Sterilization
IEEE Transactions on Industrial Electronics, 2008Co-Authors: S Y Tseng, Yaowming ChenAbstract:This paper proposes a wide Pulse combined with a Narrow-Pulse generator for solid-food sterilization. The proposed generator is composed of a full-bridge converter in phase-shift control to generate a high dc-link voltage and a full-bridge inverter associated with an L-C network and a transformer to generate wide Pulses combined with Narrow Pulses. These combined Pulses can prevent undesired strong air arcing in free space, reduce power consumption, and save power components, while sterilizing food effectively. The converter and inverter can be operated at high frequencies and with Pulse width-modulation control; thus, its weight and size can be reduced significantly, and its efficiency can correspondingly be improved. Experimental results obtained from a prototype with plusmn10-kV wide Pulses combined with plusmn10-kV Narrow Pulses and with 10- to 50-kW peak output power, depending on Pulsewidth of the output Pulses, have demonstrated its feasibility.
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Bipolar Narrow-Pulse Generator With Energy-Recovery Feature for Liquid-Food Sterilization
IEEE Transactions on Industrial Electronics, 2008Co-Authors: S Y TsengAbstract:This paper presents a bipolar Narrow-Pulse generator with energy-recovery feature for liquid-food sterilization. The generator is formed from a bidirectional flyback converter and active-clamp circuits which are further simplified to the proposed topology with the synchronous-switch technique. In the converter, the leakage inductance of the transformer will resonate with the active-clamp capacitors to recover the trapped energy and to reduce switching loss, improving efficiency by about 13%. In addition, the capacitors can reduce voltage stress significantly. Experimental results obtained from a prototype with the output of plusmn6-20 kV, depending on loads, and the peak power of 1.2 MW has confirmed these discussions.
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A Combined Wide and Narrow Pulse Generators for Processing Microbes
2005 IEEE 36th Power Electronics Specialists Conference, 2005Co-Authors: S Y Tseng, S.-s. ChenAbstract:This paper proposes a wide Pulse combined with Narrow Pulse generator for solid food sterilization. The proposed generator is composed of a full-bridge converter in phase-shift control to generate high dc-link voltage, and a full-bridge inverter associated with an L-C network and a transformer to generate wide Pulses combined with Narrow Pulses. These combined Pulses can prevent undesired strong air arcing in free space, reduce power consumption and save power components, while can sterilize food effectively. The converter and inverter can be operated at high frequencies and with PWM control, thus its weight and size can be reduced significantly and its efficiency can be correspondingly improved. Experimental results obtained from a prototype with plusmn10 kV wide Pulses combined with plusmn10 kV Narrow Pulses and with 10 ~ 50 kW peak output power, depending on Pulse width of the output Pulses, have demonstrated its feasibility
Martin D Hurlimann - One of the best experts on this subject based on the ideXlab platform.
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the Narrow Pulse approximation and long length scale determination in xenon gas diffusion nmr studies of model porous media
Journal of Magnetic Resonance, 2002Co-Authors: R W Mair, Martin D Hurlimann, Samuel Patz, David G Cory, Ronald L WalsworthAbstract:Abstract We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient Pulses in a PGSE experiment (breakdown of the Narrow Pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient Pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (∼1–1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Padelength), which is found to be ∼0.13b for all bead packs, where b is the bead diameter.
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the Narrow Pulse approximation and long length scale determination in xenon gas diffusion nmr studies of model porous media
Journal of Magnetic Resonance, 2002Co-Authors: R W Mair, Martin D Hurlimann, Samuel Patz, David G Cory, Pabitra N Sen, Ronald L WalsworthAbstract:We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient Pulses in a PGSE experiment (breakdown of the Narrow Pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient Pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (approximately 1-1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Pade length), which is found to be approximately 0.13b for all bead packs, where b is the bead diameter.
Samuel Patz - One of the best experts on this subject based on the ideXlab platform.
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the Narrow Pulse approximation and long length scale determination in xenon gas diffusion nmr studies of model porous media
Journal of Magnetic Resonance, 2002Co-Authors: R W Mair, Martin D Hurlimann, Samuel Patz, David G Cory, Ronald L WalsworthAbstract:Abstract We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient Pulses in a PGSE experiment (breakdown of the Narrow Pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient Pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (∼1–1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Padelength), which is found to be ∼0.13b for all bead packs, where b is the bead diameter.
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the Narrow Pulse approximation and long length scale determination in xenon gas diffusion nmr studies of model porous media
Journal of Magnetic Resonance, 2002Co-Authors: R W Mair, Martin D Hurlimann, Samuel Patz, David G Cory, Pabitra N Sen, Ronald L WalsworthAbstract:We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient Pulses in a PGSE experiment (breakdown of the Narrow Pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient Pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (approximately 1-1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Pade length), which is found to be approximately 0.13b for all bead packs, where b is the bead diameter.
