The objective of this study is to propose an optimal plant design for blue hydrogen production aboard a liquefiednatural gas(LNG)carrier.This investigation focuses on integrating two distinct processes—steam methaner...The objective of this study is to propose an optimal plant design for blue hydrogen production aboard a liquefiednatural gas(LNG)carrier.This investigation focuses on integrating two distinct processes—steam methanereforming(SMR)and ship-based carbon capture(SBCC).The first refers to the common practice used to obtainhydrogen from methane(often derived from natural gas),where steam reacts with methane to produce hydrogenand carbon dioxide(CO_(2)).The second refers to capturing the CO_(2) generated during the SMR process on boardships.By capturing and storing the carbon emissions,the process significantly reduces its environmental impact,making the hydrogen production“blue,”as opposed to“grey”(which involves CO_(2) emissions without capture).For the SMR process,the analysis reveals that increasing the reformer temperature enhances both the processperformance and CO_(2) emissions.Conversely,a higher steam-to-carbon(s/c)ratio reduces hydrogen yield,therebydecreasing thermal efficiency.The study also shows that preheating the air and boil-off gas(BOG)before theyenter the combustion chamber boosts overall efficiency and curtails CO_(2) emissions.In the SBCC process,puremonoethanolamine(MEA)is employed to capture the CO_(2) generated by the exhaust gases from the SMR process.The results indicate that with a 90%CO_(2) capture rate,the associated heat consumption amounts to 4.6 MJ perkilogram of CO_(2) captured.This combined approach offers a viable pathway to produce blue hydrogen on LNGcarriers while significantly reducing the carbon footprint.展开更多
In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a to...In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a total of 19,126 solar flares were observed regardless the class: 3548 flares in solar cycle 23 (SC23) and 15,668 flares in solar cycle 24 (SC24). Our findings show that the cycle 23 has observed the highest occurrences of M-class and X-class flares, whereas cycle 24 has pointed out a predominance of B-class and C-class flares throughout its different phases. The results indicate that the cycle 23 was magnetically more intense than cycle 24, leading to more powerful solar flares and more frequent geomagnetic storms, capable of generating significant electromagnetic emissions that can affect satellites and GPS signals. The decrease in intense solar flares during cycle 24 compared to cycle 23 reflects an evolution in solar activity patterns over time.展开更多
The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0....The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0.05 g/cm3) of the composite produced is lower than that of wood used in this field. The material has low porosity (9.8%) and is less absorbent (12.61%) than wood. The result of the thermal conductivity test by the hot plane method shows that this composite can contribute to the internal thermal insulation (an example of thermal conductivity is 0.32W/m.K) of floating boats. The mechanical tests of compression (young modulus is 22.86 GPa), resilience (1.238 J/Cm2) and hardness (233.04 BH30-2.5/187.5-15s) show that this composite is much harder and more absorbent than many wood and bio-composite materials used in the construction of pleasure boats. The abrasion test (0.005349) shows that this composite could well resist friction with the beach.展开更多
In this study, we examined variability of sun-related energies, auroral electrojet current, ring current, and magnetopause current during solar cycles 23 and 24. The study revealed a dependence of sun-related energies...In this study, we examined variability of sun-related energies, auroral electrojet current, ring current, and magnetopause current during solar cycles 23 and 24. The study revealed a dependence of sun-related energies to the Sun and Earth currents systems with solar activity from 1996 to 2019. A decrease in the correlation between sun-related energies and sunspot number was observed over solar cycles 23 and 24 (0.88 for the solar cycle 23 and 0.66 for the solar cycle 24), with a drop in the speed of magnetic disturbances in the solar wind. These results could be attributed to the decrease in Sun’s magnetic field toroidal component magnitude induced by a weak in sunspots number and solar flares during the solar cycle 24. A weak in the Earth currents systems (auroral electrojet current, ring current, and magnetopause current) is also observed. During the decrease in the Earth currents, several peaks are observed, indicating a nonlinear dependence in the Earth currents variation (ring current, auroral electrojet current, and magnetopause current) from solar cycle 23 to solar cycle 24. This could be attributed to the Corotating Interaction Regions (CIRs) observed during the declining phase of solar cycle 23 and the deep minimum preceding solar cycle 24.展开更多
Bio-based thermoplastic film from flax fiber and fatty acid(FA)was obtained using trifluoroacetic anhydride(TFAA)as an impelling agent.Different quantities of TFAA/FA,size of flax fiber,and fatty acids were applied to...Bio-based thermoplastic film from flax fiber and fatty acid(FA)was obtained using trifluoroacetic anhydride(TFAA)as an impelling agent.Different quantities of TFAA/FA,size of flax fiber,and fatty acids were applied to investigate chemical structure in relation to the mechanical properties.Decreasing the quantity of TFAA/FA by almost half from 1:4 to 1:2.5(flax to TFAA/FA)only reduces by 22%the weight percent gain(WPG)and ester content and reducing flax fiber size slightly increases the WPG and ester content.All the treatments showed sig-nificant chemical structure modification,observed by FTIR and solid CP/MAS^(13)C NMR,confirming the presence of carbonyl ester groups and alkyl chains,in relatively similar intensities.The crystallinity index(CrI)of esterified flax was evaluated by comparing the signal of solid CP/MAS^(13)C NMR in crystalline and amorphous regions and CrI was higher in esterified flax using a lower quantity of reagent and longer fatty acid.Esterified flax in a high quantity of reagent showed ductile or flexible behavior.Decreasing the reagent to 1:2.5 significantly increases the tensile strength and Young’s modulus,and decreases the elongation at break,presenting more brittle and stiff material.Using flax fiber in the original size results in slightly higher tensile strength and Young’s modulus and slightly lower elongation than milled flax.The tensile strength and Young’s modulus of stearic acid esterified flax obtained in this research were higher than myristic acid and comparable to the polyethylene plastics-LDPE and HDPE.展开更多
Carbon dioxide(CO_(2))is often monitored as a convenient yardstick for indoor air safety,yet its ability to stand in for pathogen-laden aerosols has never been settled.To probe the question,we reproduced an open-plan ...Carbon dioxide(CO_(2))is often monitored as a convenient yardstick for indoor air safety,yet its ability to stand in for pathogen-laden aerosols has never been settled.To probe the question,we reproduced an open-plan office at full scale(7.2m×5.2m×2.8m)and introduced a breathing plume that carried 4% CO_(2),together with a polydisperse aerosol spanning 0.5–10μm(1320 particles s^(−1)).Inlet air was supplied at 0.7,1.4,and 2.1 m s^(−1),and the resulting fields were simulated with a Realisable k–εRANS model coupled to Lagrangian particle tracking.Nine strategically placed probes provided validation;the calibrated solution deviated fromthe experiment by 58 ppm for CO_(2)(8.1%RMSE)and 0.008 m s^(−1)for velocity(15.7%RMSE).Despite this agreement,gas and particles behaved in sharply different ways.Room-averaged CO_(2)varied by<15%,whereas the aerosol mass rose to almost three-fold the background within slowmoving corner vortices.Sub-micron particles stayed aloft along streamlines,while those≥5μmpeeled away and settled on nearby surfaces.The divergence shows that neither the CO_(2)level nor themeanageof air,taken in isolation,delineates all high-exposure zones.We therefore recommend that ventilation design be informed by a composite diagnosis that couples gas data,size-resolved particle measurements,and rapid CFD appraisal.展开更多
1 Foreword The crises produced by the COVID-19 pandemic and the ongoing Russia-Ukraine conflict have starkly highlighted the critical need for scientific innovation and global cooperation.The pandemic underscored the ...1 Foreword The crises produced by the COVID-19 pandemic and the ongoing Russia-Ukraine conflict have starkly highlighted the critical need for scientific innovation and global cooperation.The pandemic underscored the urgency of swift,science-driven responses to worldwide health emergencies,while the war has intensified energy shortages and material scarcities,amplifying the demand for sustainable and resilient solutions.展开更多
The effect of thixoforming process on morphologies of silicon particles that affect fracture mode of A356 alloy was investigated.Microstructure and fracture surfaces of thixoformed samples were investigated by image a...The effect of thixoforming process on morphologies of silicon particles that affect fracture mode of A356 alloy was investigated.Microstructure and fracture surfaces of thixoformed samples were investigated by image analyzing technique and scanning electron microscopy.A new combination parameter, called silicon density ratio (SDR) index, was introduced.SDR index approximates the collective effects of morphological characteristics of silicon particles on microstructure transparency of alloy in crossing the dislocation.It is suggested that samples with lower SDR index have superior mechanical properties, especially elongation, and consequently intergranular fracture mode.On the contrary, samples with higher SDR index have inferior mechanical properties and fracture path tends to propagate along the cell boundaries leading to transgranular fracture.展开更多
The transmission of seismic waves in a particular region may influence the hydraulic properties of a rock mass, including permeability, which is one of the most important. To determine the effect of a seismic wave on ...The transmission of seismic waves in a particular region may influence the hydraulic properties of a rock mass, including permeability, which is one of the most important. To determine the effect of a seismic wave on the hydraulic behavior of a fractured rock mass, systematic numerical modeling was conducted. A number of discrete fracture network（DFN） models with a size of 20 m × 20 m were used as geometrical bases, and a discrete element method（DEM） was employed as a numerical simulation tool. Three different boundary conditions without（Type Ⅰ） and with static（Type Ⅱ） and dynamic（Type Ⅲ） loading were performed on the models, and then their permeability was calculated. The results showed that permeability in Type Ⅲ models was respectively 62.7% and 44.2% higher than in Type I and Type Ⅱ models. This study indicates that seismic waves can affect deep earth, and, according to the results, seismic waves increase the permeability and change the flow rate patterns in a fractured rock mass.展开更多
Uncertainty in input fracture geometric parameters during analysis of the stability of jointed rock slopes is inevitable and therefore the stochastic discrete fracture network(DFN)-distinct element method(DEM) is an e...Uncertainty in input fracture geometric parameters during analysis of the stability of jointed rock slopes is inevitable and therefore the stochastic discrete fracture network(DFN)-distinct element method(DEM) is an efficient modeling tool. In this research, potentially unstable conditions are detected in the right abutment of the Karun 4 dam and downstream of the dam body as a case study. Two extreme states with small and relatively large block sizes are selected and a series of numerical DEM models are generated using a number of validated DFN models. Stability of the rock slope is assessed in both static and dynamic loading states. Based on the design basis earthquake(DBE) and maximum credible earthquake(MCE) expected in the dam site, histories of seismic waves are applied to analyze the stability of the slope in dynamic earthquake conditions. The results indicate that a MCE is likely to trigger sliding of rock blocks on the rock slope major joint. Furthermore, the dynamic analysis also shows a local block failure by the DBE, which can consequently lead to slope instability over the long term. According to the seismic behavior of the two models, larger blocks are prone to greater instability and are less safe against earthquakes.展开更多
Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-...Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-80 specifications：35mL/L 85% H3PO4＋20g/L CrO3 at 38℃.Influence of oxalic acid concentration,bath temperature and anodic current density on dissolution rate and coating ratio was examined,when the sulphuric acid concentration was maintained at 160g/L.It was found that chemically resistant and compact oxide layers were produced under low operational temperature （5℃） and high current densities （3A/dm^2）.A beneficial effect was observed concerning the addition of oxalic acid （18g/L）.The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy （SEM）,atomic force microscopy （AFM） and glow-discharge optical emission spectroscopy （GDOES）.展开更多
文摘The objective of this study is to propose an optimal plant design for blue hydrogen production aboard a liquefiednatural gas(LNG)carrier.This investigation focuses on integrating two distinct processes—steam methanereforming(SMR)and ship-based carbon capture(SBCC).The first refers to the common practice used to obtainhydrogen from methane(often derived from natural gas),where steam reacts with methane to produce hydrogenand carbon dioxide(CO_(2)).The second refers to capturing the CO_(2) generated during the SMR process on boardships.By capturing and storing the carbon emissions,the process significantly reduces its environmental impact,making the hydrogen production“blue,”as opposed to“grey”(which involves CO_(2) emissions without capture).For the SMR process,the analysis reveals that increasing the reformer temperature enhances both the processperformance and CO_(2) emissions.Conversely,a higher steam-to-carbon(s/c)ratio reduces hydrogen yield,therebydecreasing thermal efficiency.The study also shows that preheating the air and boil-off gas(BOG)before theyenter the combustion chamber boosts overall efficiency and curtails CO_(2) emissions.In the SBCC process,puremonoethanolamine(MEA)is employed to capture the CO_(2) generated by the exhaust gases from the SMR process.The results indicate that with a 90%CO_(2) capture rate,the associated heat consumption amounts to 4.6 MJ perkilogram of CO_(2) captured.This combined approach offers a viable pathway to produce blue hydrogen on LNGcarriers while significantly reducing the carbon footprint.
文摘In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a total of 19,126 solar flares were observed regardless the class: 3548 flares in solar cycle 23 (SC23) and 15,668 flares in solar cycle 24 (SC24). Our findings show that the cycle 23 has observed the highest occurrences of M-class and X-class flares, whereas cycle 24 has pointed out a predominance of B-class and C-class flares throughout its different phases. The results indicate that the cycle 23 was magnetically more intense than cycle 24, leading to more powerful solar flares and more frequent geomagnetic storms, capable of generating significant electromagnetic emissions that can affect satellites and GPS signals. The decrease in intense solar flares during cycle 24 compared to cycle 23 reflects an evolution in solar activity patterns over time.
文摘The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0.05 g/cm3) of the composite produced is lower than that of wood used in this field. The material has low porosity (9.8%) and is less absorbent (12.61%) than wood. The result of the thermal conductivity test by the hot plane method shows that this composite can contribute to the internal thermal insulation (an example of thermal conductivity is 0.32W/m.K) of floating boats. The mechanical tests of compression (young modulus is 22.86 GPa), resilience (1.238 J/Cm2) and hardness (233.04 BH30-2.5/187.5-15s) show that this composite is much harder and more absorbent than many wood and bio-composite materials used in the construction of pleasure boats. The abrasion test (0.005349) shows that this composite could well resist friction with the beach.
文摘In this study, we examined variability of sun-related energies, auroral electrojet current, ring current, and magnetopause current during solar cycles 23 and 24. The study revealed a dependence of sun-related energies to the Sun and Earth currents systems with solar activity from 1996 to 2019. A decrease in the correlation between sun-related energies and sunspot number was observed over solar cycles 23 and 24 (0.88 for the solar cycle 23 and 0.66 for the solar cycle 24), with a drop in the speed of magnetic disturbances in the solar wind. These results could be attributed to the decrease in Sun’s magnetic field toroidal component magnitude induced by a weak in sunspots number and solar flares during the solar cycle 24. A weak in the Earth currents systems (auroral electrojet current, ring current, and magnetopause current) is also observed. During the decrease in the Earth currents, several peaks are observed, indicating a nonlinear dependence in the Earth currents variation (ring current, auroral electrojet current, and magnetopause current) from solar cycle 23 to solar cycle 24. This could be attributed to the Corotating Interaction Regions (CIRs) observed during the declining phase of solar cycle 23 and the deep minimum preceding solar cycle 24.
基金UR 4370 LERMAB is supported by a grant overseen by the French National Research Agency(ANR)as part of the“Investissements d’Avenir”program(ANR-11-LABX-0002-01,Lab of Excellence ARBRE)in the frame of the project“Woodstic”ICEEL for the financial in the frame of the project“BoisPlast”(CARN 001301).
文摘Bio-based thermoplastic film from flax fiber and fatty acid(FA)was obtained using trifluoroacetic anhydride(TFAA)as an impelling agent.Different quantities of TFAA/FA,size of flax fiber,and fatty acids were applied to investigate chemical structure in relation to the mechanical properties.Decreasing the quantity of TFAA/FA by almost half from 1:4 to 1:2.5(flax to TFAA/FA)only reduces by 22%the weight percent gain(WPG)and ester content and reducing flax fiber size slightly increases the WPG and ester content.All the treatments showed sig-nificant chemical structure modification,observed by FTIR and solid CP/MAS^(13)C NMR,confirming the presence of carbonyl ester groups and alkyl chains,in relatively similar intensities.The crystallinity index(CrI)of esterified flax was evaluated by comparing the signal of solid CP/MAS^(13)C NMR in crystalline and amorphous regions and CrI was higher in esterified flax using a lower quantity of reagent and longer fatty acid.Esterified flax in a high quantity of reagent showed ductile or flexible behavior.Decreasing the reagent to 1:2.5 significantly increases the tensile strength and Young’s modulus,and decreases the elongation at break,presenting more brittle and stiff material.Using flax fiber in the original size results in slightly higher tensile strength and Young’s modulus and slightly lower elongation than milled flax.The tensile strength and Young’s modulus of stearic acid esterified flax obtained in this research were higher than myristic acid and comparable to the polyethylene plastics-LDPE and HDPE.
文摘Carbon dioxide(CO_(2))is often monitored as a convenient yardstick for indoor air safety,yet its ability to stand in for pathogen-laden aerosols has never been settled.To probe the question,we reproduced an open-plan office at full scale(7.2m×5.2m×2.8m)and introduced a breathing plume that carried 4% CO_(2),together with a polydisperse aerosol spanning 0.5–10μm(1320 particles s^(−1)).Inlet air was supplied at 0.7,1.4,and 2.1 m s^(−1),and the resulting fields were simulated with a Realisable k–εRANS model coupled to Lagrangian particle tracking.Nine strategically placed probes provided validation;the calibrated solution deviated fromthe experiment by 58 ppm for CO_(2)(8.1%RMSE)and 0.008 m s^(−1)for velocity(15.7%RMSE).Despite this agreement,gas and particles behaved in sharply different ways.Room-averaged CO_(2)varied by<15%,whereas the aerosol mass rose to almost three-fold the background within slowmoving corner vortices.Sub-micron particles stayed aloft along streamlines,while those≥5μmpeeled away and settled on nearby surfaces.The divergence shows that neither the CO_(2)level nor themeanageof air,taken in isolation,delineates all high-exposure zones.We therefore recommend that ventilation design be informed by a composite diagnosis that couples gas data,size-resolved particle measurements,and rapid CFD appraisal.
文摘1 Foreword The crises produced by the COVID-19 pandemic and the ongoing Russia-Ukraine conflict have starkly highlighted the critical need for scientific innovation and global cooperation.The pandemic underscored the urgency of swift,science-driven responses to worldwide health emergencies,while the war has intensified energy shortages and material scarcities,amplifying the demand for sustainable and resilient solutions.
文摘The effect of thixoforming process on morphologies of silicon particles that affect fracture mode of A356 alloy was investigated.Microstructure and fracture surfaces of thixoformed samples were investigated by image analyzing technique and scanning electron microscopy.A new combination parameter, called silicon density ratio (SDR) index, was introduced.SDR index approximates the collective effects of morphological characteristics of silicon particles on microstructure transparency of alloy in crossing the dislocation.It is suggested that samples with lower SDR index have superior mechanical properties, especially elongation, and consequently intergranular fracture mode.On the contrary, samples with higher SDR index have inferior mechanical properties and fracture path tends to propagate along the cell boundaries leading to transgranular fracture.
文摘The transmission of seismic waves in a particular region may influence the hydraulic properties of a rock mass, including permeability, which is one of the most important. To determine the effect of a seismic wave on the hydraulic behavior of a fractured rock mass, systematic numerical modeling was conducted. A number of discrete fracture network（DFN） models with a size of 20 m × 20 m were used as geometrical bases, and a discrete element method（DEM） was employed as a numerical simulation tool. Three different boundary conditions without（Type Ⅰ） and with static（Type Ⅱ） and dynamic（Type Ⅲ） loading were performed on the models, and then their permeability was calculated. The results showed that permeability in Type Ⅲ models was respectively 62.7% and 44.2% higher than in Type I and Type Ⅱ models. This study indicates that seismic waves can affect deep earth, and, according to the results, seismic waves increase the permeability and change the flow rate patterns in a fractured rock mass.
文摘Uncertainty in input fracture geometric parameters during analysis of the stability of jointed rock slopes is inevitable and therefore the stochastic discrete fracture network(DFN)-distinct element method(DEM) is an efficient modeling tool. In this research, potentially unstable conditions are detected in the right abutment of the Karun 4 dam and downstream of the dam body as a case study. Two extreme states with small and relatively large block sizes are selected and a series of numerical DEM models are generated using a number of validated DFN models. Stability of the rock slope is assessed in both static and dynamic loading states. Based on the design basis earthquake(DBE) and maximum credible earthquake(MCE) expected in the dam site, histories of seismic waves are applied to analyze the stability of the slope in dynamic earthquake conditions. The results indicate that a MCE is likely to trigger sliding of rock blocks on the rock slope major joint. Furthermore, the dynamic analysis also shows a local block failure by the DBE, which can consequently lead to slope instability over the long term. According to the seismic behavior of the two models, larger blocks are prone to greater instability and are less safe against earthquakes.
文摘Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-80 specifications：35mL/L 85% H3PO4＋20g/L CrO3 at 38℃.Influence of oxalic acid concentration,bath temperature and anodic current density on dissolution rate and coating ratio was examined,when the sulphuric acid concentration was maintained at 160g/L.It was found that chemically resistant and compact oxide layers were produced under low operational temperature （5℃） and high current densities （3A/dm^2）.A beneficial effect was observed concerning the addition of oxalic acid （18g/L）.The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy （SEM）,atomic force microscopy （AFM） and glow-discharge optical emission spectroscopy （GDOES）.
