The Experts below are selected from a list of 36597 Experts worldwide ranked by ideXlab platform
Johann F Gorgens - One of the best experts on this subject based on the ideXlab platform.
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techno economics of integrating bioethanol production from spent sulfite liquor for reduction of greenhouse gas emissions from sulfite pulping mills
Biotechnology for Biofuels, 2014Co-Authors: Abdul M Petersen, Kate Haigh, Johann F GorgensAbstract:Flow sheet options for integrating ethanol production from spent sulfite liquor (SSL) into the acid-based sulfite pulping process at the Sappi Saiccor mill (Umkomaas, South Africa) were investigated, including options for generation of thermal and electrical Energy from onsite bio-wastes, such as bark. Processes were simulated with Aspen Plus® for mass- and Energy-balances, followed by an estimation of the economic viability and environmental impacts. Various concentration levels of the total dissolved solids in magnesium oxide-based SSL, which currently fuels a recovery boiler, prior to fermentation was considered, together with return of the fermentation residues (distillation bottoms) to the recovery boiler after ethanol separation. The generation of renewable thermal and electrical Energy from onsite bio-wastes were also included in the Energy balance of the combined pulping-ethanol process, in order to partially replace coal consumption. The bio-Energy supplementations included the combustion of bark for heat and electricity generation and the bio-digestion of the calcium oxide SSL to produce methane as Additional Energy Source. Ethanol production from SSL at the highest substrate concentration was the most economically feasible when coal was used for process Energy. However this solution did not provide any savings in greenhouse gas (GHG) emissions for the concentration-fermentation-distillation process. Maximizing the use of renewable Energy Sources to partially replace coal consumption yielded a satisfactory economic performance, with a minimum ethanol selling price of 0.83 US$/l , and a drastic reduction in the overall greenhouse gas emissions for the entire facility. High substrate concentrations and conventional distillation should be used when considering integrating ethanol production at sulfite pulping mills. Bio-wastes generated onsite should be utilized at their maximum potential for Energy generation in order to maximize the GHG emissions reduction.
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techno economics of integrating bioethanol production from spent sulfite liquor for reduction of greenhouse gas emissions from sulfite pulping mills
Biotechnology for Biofuels, 2014Co-Authors: Abdul M Petersen, Kate Haigh, Johann F GorgensAbstract:Background Flow sheet options for integrating ethanol production from spent sulfite liquor (SSL) into the acid-based sulfite pulping process at the Sappi Saiccor mill (Umkomaas, South Africa) were investigated, including options for generation of thermal and electrical Energy from onsite bio-wastes, such as bark. Processes were simulated with Aspen Plus® for mass- and Energy-balances, followed by an estimation of the economic viability and environmental impacts. Various concentration levels of the total dissolved solids in magnesium oxide-based SSL, which currently fuels a recovery boiler, prior to fermentation was considered, together with return of the fermentation residues (distillation bottoms) to the recovery boiler after ethanol separation. The generation of renewable thermal and electrical Energy from onsite bio-wastes were also included in the Energy balance of the combined pulping-ethanol process, in order to partially replace coal consumption. The bio-Energy supplementations included the combustion of bark for heat and electricity generation and the bio-digestion of the calcium oxide SSL to produce methane as Additional Energy Source.
Gregory S Sawicki - One of the best experts on this subject based on the ideXlab platform.
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reducing the Energy cost of human walking using an unpowered exoskeleton
Nature, 2015Co-Authors: Steven H Collins, Bruce M Wiggin, Gregory S SawickiAbstract:With efficiencies derived from evolution, growth and learning, humans are very well-tuned for locomotion1. Metabolic Energy used during walking can be partly replaced by power input from an exoskeleton2, but is it possible to reduce metabolic rate without providing an Additional Energy Source? This would require an improvement in the efficiency of the human–machine system as a whole, and would be remarkable given the apparent optimality of human gait. Here we show that the metabolic rate of human walking can be reduced by an unpowered ankle exoskeleton. We built a lightweight elastic device that acts in parallel with the user's calf muscles, off-loading muscle force and thereby reducing the metabolic Energy consumed in contractions. The device uses a mechanical clutch to hold a spring as it is stretched and relaxed by ankle movements when the foot is on the ground, helping to fulfil one function of the calf muscles and Achilles tendon. Unlike muscles, however, the clutch sustains force passively. The exoskeleton consumes no chemical or electrical Energy and delivers no net positive mechanical work, yet reduces the metabolic cost of walking by 7.2 ± 2.6% for healthy human users under natural conditions, comparable to savings with powered devices. Improving upon walking economy in this way is analogous to altering the structure of the body such that it is more Energy-effective at walking. While strong natural pressures have already shaped human locomotion, improvements in efficiency are still possible. Much remains to be learned about this seemingly simple behaviour. The attachment of a simple, unpowered, mechanical exoskeleton to the foot and ankle results in a net saving of 7% of the metabolic Energy expended in human walking. Walking is the most commonplace of activities, yet we know remarkably little about it and no robot has yet reproduced the grace and poise of a human walk. Steven Collins et al. now show that the attachment of a simple mechanical exoskeleton to the foot and ankle results in a 7% reduction of the metabolic Energy expended in walking. This work shows that net Energy input is not a fundamental requirement for reducing the metabolic cost of human walking, and that reducing calf muscle forces — while also fulfilling normal ankle functions and minimizing penalties associated with added mass or restricted motions — can be beneficial.
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Reducing the Energy cost of human walking using an unpowered exoskeleton
Nature, 2015Co-Authors: M. Bruce Wiggin, Gregory S SawickiAbstract:With efficiencies derived from evolution, growth and learning, humans are very well-tuned for locomotion. Metabolic Energy used during walking can be partly replaced by power input from an exoskeleton, but is it possible to reduce metabolic rate without providing an Additional Energy Source? This would require an improvement in the efficiency of the human-machine system as a whole, and would be remarkable given the apparent optimality of human gait. Here we show that the metabolic rate of human walking can be reduced by an unpowered ankle exoskeleton. We built a lightweight elastic device that acts in parallel with the user's calf muscles, off-loading muscle force and thereby reducing the metabolic Energy consumed in contractions. The device uses a mechanical clutch to hold a spring as it is stretched and relaxed by ankle movements when the foot is on the ground, helping to fulfil one function of the calf muscles and Achilles tendon. Unlike muscles, however, the clutch sustains force passively. The exoskeleton consumes no chemical or electrical Energy and delivers no net positive mechanical work, yet reduces the metabolic cost of walking by 7.2 [plusmn] 2.6% for healthy human users under natural conditions, comparable to savings with powered devices. Improving upon walking economy in this way is analogous to altering the structure of the body such that it is more Energy-effective at walking. While strong natural pressures have already shaped human locomotion, improvements in efficiency are still possible. Much remains to be learned about this seemingly simple behaviour.
Abdul M Petersen - One of the best experts on this subject based on the ideXlab platform.
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techno economics of integrating bioethanol production from spent sulfite liquor for reduction of greenhouse gas emissions from sulfite pulping mills
Biotechnology for Biofuels, 2014Co-Authors: Abdul M Petersen, Kate Haigh, Johann F GorgensAbstract:Flow sheet options for integrating ethanol production from spent sulfite liquor (SSL) into the acid-based sulfite pulping process at the Sappi Saiccor mill (Umkomaas, South Africa) were investigated, including options for generation of thermal and electrical Energy from onsite bio-wastes, such as bark. Processes were simulated with Aspen Plus® for mass- and Energy-balances, followed by an estimation of the economic viability and environmental impacts. Various concentration levels of the total dissolved solids in magnesium oxide-based SSL, which currently fuels a recovery boiler, prior to fermentation was considered, together with return of the fermentation residues (distillation bottoms) to the recovery boiler after ethanol separation. The generation of renewable thermal and electrical Energy from onsite bio-wastes were also included in the Energy balance of the combined pulping-ethanol process, in order to partially replace coal consumption. The bio-Energy supplementations included the combustion of bark for heat and electricity generation and the bio-digestion of the calcium oxide SSL to produce methane as Additional Energy Source. Ethanol production from SSL at the highest substrate concentration was the most economically feasible when coal was used for process Energy. However this solution did not provide any savings in greenhouse gas (GHG) emissions for the concentration-fermentation-distillation process. Maximizing the use of renewable Energy Sources to partially replace coal consumption yielded a satisfactory economic performance, with a minimum ethanol selling price of 0.83 US$/l , and a drastic reduction in the overall greenhouse gas emissions for the entire facility. High substrate concentrations and conventional distillation should be used when considering integrating ethanol production at sulfite pulping mills. Bio-wastes generated onsite should be utilized at their maximum potential for Energy generation in order to maximize the GHG emissions reduction.
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techno economics of integrating bioethanol production from spent sulfite liquor for reduction of greenhouse gas emissions from sulfite pulping mills
Biotechnology for Biofuels, 2014Co-Authors: Abdul M Petersen, Kate Haigh, Johann F GorgensAbstract:Background Flow sheet options for integrating ethanol production from spent sulfite liquor (SSL) into the acid-based sulfite pulping process at the Sappi Saiccor mill (Umkomaas, South Africa) were investigated, including options for generation of thermal and electrical Energy from onsite bio-wastes, such as bark. Processes were simulated with Aspen Plus® for mass- and Energy-balances, followed by an estimation of the economic viability and environmental impacts. Various concentration levels of the total dissolved solids in magnesium oxide-based SSL, which currently fuels a recovery boiler, prior to fermentation was considered, together with return of the fermentation residues (distillation bottoms) to the recovery boiler after ethanol separation. The generation of renewable thermal and electrical Energy from onsite bio-wastes were also included in the Energy balance of the combined pulping-ethanol process, in order to partially replace coal consumption. The bio-Energy supplementations included the combustion of bark for heat and electricity generation and the bio-digestion of the calcium oxide SSL to produce methane as Additional Energy Source.
Eric C Bellm - One of the best experts on this subject based on the ideXlab platform.
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evidence for late stage eruptive mass loss in the progenitor to sn2018gep a broad lined ic supernova pre explosion emission and a rapidly rising luminous transient
The Astrophysical Journal, 2019Co-Authors: Daniel A Goldstein, S Schulze, David Khatami, D A Perley, M Ergon, A Galyam, A Corsi, Igor Andreoni, C Barbarino, Eric C BellmAbstract:Author(s): Ho, AYQ; Goldstein, DA; Schulze, S; Khatami, DK; Perley, DA; Ergon, M; Gal-Yam, A; Corsi, A; Andreoni, I; Barbarino, C; Bellm, EC; Blagorodnova, N; Bright, JS; Burns, E; Cenko, SB; Cunningham, V; De, K; Dekany, R; Dugas, A; Fender, RP; Fransson, C; Fremling, C; Goldstein, A; Graham, MJ; Hale, D; Horesh, A; Hung, T; Kasliwal, MM; M. Kuin, NP; Kulkarni, SR; Kupfer, T; Lunnan, R; Masci, FJ; Ngeow, CC; Nugent, PE; Ofek, EO; Patterson, MT; Petitpas, G; Rusholme, B; Sai, H; Sfaradi, I; Shupe, DL; Sollerman, J; Soumagnac, MT; Tachibana, Y; Taddia, F; Walters, R; Wang, X; Yao, Y; Zhang, X | Abstract: © 2019. The American Astronomical Society. All rights reserved. We present detailed observations of ZTF18abukavn (SN2018gep), discovered in high-cadence data from the Zwicky Transient Facility as a rapidly rising (1.4 ± 0.1 mag hr-1) and luminous (Mg,peak = -20 mag) transient. It is spectroscopically classified as a broad-lined stripped-envelope supernova (Ic-BL SN). The high peak luminosity (Lbol ≳ 3 × 1044 erg s-1), the short rise time (trise = 3 days in g band), and the blue colors at peak (g-r ∼ -0.4) all resemble the high-redshift Ic-BL iPTF16asu, as well as several other unclassified fast transients. The early discovery of SN2018gep (within an hour of shock breakout) enabled an intensive spectroscopic campaign, including the highest-temperature (Teff ≳ 40,000 K) spectra of a stripped-envelope SN. A retrospective search revealed luminous (Mg ∼ Mr ≈ mag) emission in the days to weeks before explosion, the first definitive detection of precursor emission for a Ic-BL. We find a limit on the isotropic gamma-ray Energy release E γ,iso l 4.9 × 10 48 erg, a limit on X-ray emission LX l 1040 erg s-1, and a limit on radio emission ν Lν ≲ 1037 erg s-1. Taken together, we find that the early (l 10 days) data are best explained by shock breakout in a massive shell of dense circumstellar material (0.02 M⊙) at large radii (3 × 1014 cm) that was ejected in eruptive pre-explosion mass-loss episodes. The late-time (g 10 days) light curve requires an Additional Energy Source, which could be the radioactive decay of Ni-56.
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evidence for late stage eruptive mass loss in the progenitor to sn2018gep a broad lined ic supernova pre explosion emission and a rapidly rising luminous transient
arXiv: High Energy Astrophysical Phenomena, 2019Co-Authors: Daniel A Goldstein, S Schulze, David Khatami, D A Perley, M Ergon, A Galyam, A Corsi, Igor Andreoni, C Barbarino, Eric C BellmAbstract:We present detailed observations of ZTF18abukavn (SN2018gep), discovered in high-cadence data from the Zwicky Transient Facility as a rapidly rising ($1.4\pm0.1$ mag/hr) and luminous ($M_{g,\mathrm{peak}}=-20$ mag) transient. It is spectroscopically classified as a broad-lined stripped-envelope supernova (Ic-BL SN). The high peak luminosity ($L_{\mathrm{bol}} \gtrsim 3 \times 10^{44}$ erg $\mathrm{sec}^{-1}$), the short rise time ($t_{\mathrm{rise}}= 3$ days in $g$-band), and the blue colors at peak ($g-r\sim-0.4$) all resemble the high-redshift Ic-BL iPTF16asu, as well as several other unclassified fast transients. The early discovery of SN2018gep (within an hour of shock breakout) enabled an intensive spectroscopic campaign, including the highest-temperature ($T_{\mathrm{eff}}\gtrsim40,000$ K) spectra of a stripped-envelope SN. A retrospective search revealed luminous ($M_g \sim M_r \approx -14\,$mag) emission in the days to weeks before explosion, the first definitive detection of precursor emission for a Ic-BL. We find a limit on the isotropic gamma-ray Energy release $E_\mathrm{\gamma,iso} 10$ days) light curve requires an Additional Energy Source, which could be the radioactive decay of Ni-56.
Kate Haigh - One of the best experts on this subject based on the ideXlab platform.
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techno economics of integrating bioethanol production from spent sulfite liquor for reduction of greenhouse gas emissions from sulfite pulping mills
Biotechnology for Biofuels, 2014Co-Authors: Abdul M Petersen, Kate Haigh, Johann F GorgensAbstract:Flow sheet options for integrating ethanol production from spent sulfite liquor (SSL) into the acid-based sulfite pulping process at the Sappi Saiccor mill (Umkomaas, South Africa) were investigated, including options for generation of thermal and electrical Energy from onsite bio-wastes, such as bark. Processes were simulated with Aspen Plus® for mass- and Energy-balances, followed by an estimation of the economic viability and environmental impacts. Various concentration levels of the total dissolved solids in magnesium oxide-based SSL, which currently fuels a recovery boiler, prior to fermentation was considered, together with return of the fermentation residues (distillation bottoms) to the recovery boiler after ethanol separation. The generation of renewable thermal and electrical Energy from onsite bio-wastes were also included in the Energy balance of the combined pulping-ethanol process, in order to partially replace coal consumption. The bio-Energy supplementations included the combustion of bark for heat and electricity generation and the bio-digestion of the calcium oxide SSL to produce methane as Additional Energy Source. Ethanol production from SSL at the highest substrate concentration was the most economically feasible when coal was used for process Energy. However this solution did not provide any savings in greenhouse gas (GHG) emissions for the concentration-fermentation-distillation process. Maximizing the use of renewable Energy Sources to partially replace coal consumption yielded a satisfactory economic performance, with a minimum ethanol selling price of 0.83 US$/l , and a drastic reduction in the overall greenhouse gas emissions for the entire facility. High substrate concentrations and conventional distillation should be used when considering integrating ethanol production at sulfite pulping mills. Bio-wastes generated onsite should be utilized at their maximum potential for Energy generation in order to maximize the GHG emissions reduction.
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techno economics of integrating bioethanol production from spent sulfite liquor for reduction of greenhouse gas emissions from sulfite pulping mills
Biotechnology for Biofuels, 2014Co-Authors: Abdul M Petersen, Kate Haigh, Johann F GorgensAbstract:Background Flow sheet options for integrating ethanol production from spent sulfite liquor (SSL) into the acid-based sulfite pulping process at the Sappi Saiccor mill (Umkomaas, South Africa) were investigated, including options for generation of thermal and electrical Energy from onsite bio-wastes, such as bark. Processes were simulated with Aspen Plus® for mass- and Energy-balances, followed by an estimation of the economic viability and environmental impacts. Various concentration levels of the total dissolved solids in magnesium oxide-based SSL, which currently fuels a recovery boiler, prior to fermentation was considered, together with return of the fermentation residues (distillation bottoms) to the recovery boiler after ethanol separation. The generation of renewable thermal and electrical Energy from onsite bio-wastes were also included in the Energy balance of the combined pulping-ethanol process, in order to partially replace coal consumption. The bio-Energy supplementations included the combustion of bark for heat and electricity generation and the bio-digestion of the calcium oxide SSL to produce methane as Additional Energy Source.