The article considers one of the possible approaches to the solution of an urgent issue of metal consumption reduction, increase of operating life and maximum operating temperature as well as reduction of irrecoverabl...The article considers one of the possible approaches to the solution of an urgent issue of metal consumption reduction, increase of operating life and maximum operating temperature as well as reduction of irrecoverable losses of platinum products and alloys when operating under high temperature conditions, particularly for glassblowing and single crystal growing crucibles. A two-layered composite material based on platinum-group metals and corundum plasma ceramics is thoroughly investigated. A successful experience of crucibles exploitation, designed for production of high temperature optical glasses from the composite and results of the research on composite material specimens are described.展开更多
The co-variation of surface wind speed and sea surface temperature (SST) over the Gulf Stream frontal region is investigated using high-resolution satellite measurements and atmospheric reanalysis data. Results show t...The co-variation of surface wind speed and sea surface temperature (SST) over the Gulf Stream frontal region is investigated using high-resolution satellite measurements and atmospheric reanalysis data. Results show that the pattern of positive SST-surface wind speed correlations is anchored by strong SST gradient and marine atmospheric boundary layer (MABL) height front, with active warm and cold-ocean eddies around. The MABL has an obvious transitional structure along the strong SST front, with greater (lesser) heights over the north (south) side. The significant positive SST-surface wind-speed perturbation correlations are mostly found over both strong warm and cold eddies. The surface wind speed increases (decreases) about 0.32 (0.41) m/s and the MABL elevates (drops) approximate 55 (54) m per 1℃ of SST perturbation induced by warm (cold) eddies. The response of the surface wind speed to SST perturbations over the mesoscale eddies is mainly attributed to the momentum vertical mixing in the MABL, which is confirmed by the linear relationships between the downwind (crosswind) SST gradient and wind divergence (curl).展开更多
Applications, theoretical analysis and numerical methods are introduced for the simulation of mechanical models and principles of the porous flow in high temperature, high salt, complicated geology and large-scale res...Applications, theoretical analysis and numerical methods are introduced for the simulation of mechanical models and principles of the porous flow in high temperature, high salt, complicated geology and large-scale reservoirs in this paper. Considering petroleum geology, geochemistry, computational permeation fluid mechanics and computer technology, we state the models of permeation fluid mechanics and put forward a sequence of implicit upwind difference iteration schemes based on refined fractional steps of the upstream, which can compute the pressures, the saturation and the concentrations of different chemistry components. A type of software applicable in major industries has been completed and carried out in numerical analysis and simulations of oil extraction in Shengli Oil-field, which brings huge economic benefits and social benefits. This software gives many characters: spatial steps are taken as ten meters, the number of nodes is up to hundreds of thousands and simulation time period can be tens of years and the high-order accuracy can be promised in numerical data. Precise analysis is present for simplified models of this type and that provides a tool to solve the international famous problem.展开更多
The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shun...The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5oC up to 50oC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed.展开更多
The aim of this work was to investigate the effect of lithium chloride (LiCl) on the fibre length distribution, melting temperature and the rheological characteristics of high yield pulp fibre reinforced polyamide bio...The aim of this work was to investigate the effect of lithium chloride (LiCl) on the fibre length distribution, melting temperature and the rheological characteristics of high yield pulp fibre reinforced polyamide biocomposite. The inorganic salt lithium chloride (LiCl) was used to decrease the melting and processing temperature of bio-based polyamide 11. The extrusion method and Brabender mixer approaches were used to carry out the compounding process. The densities and fibre content were found to be increased after processing using both compounding methods. The HYP fibre length distribution analysis realized using the FQA equipment showed an important fibre-length reduction after processing by both techniques. The rheological properties of HYP-reinforced net and modified bio-based polyamide 11 “PA11” (HYP/PA11) composite were investigated using a capillary rheometer. The rheological tests were performed in function of the shear rate for different temperature conditions. The low-temperature process compounding had higher shear viscosity;this was because during the process the temperature was low and the mixing and melting were induced by the high shear rate created during compounding process. Experimental test results using the extrusion process showed a steep decrease in shear viscosity with increasing shear rate, and this melt-flow characteristic corresponds to shear-thinning behavior in HYP/PA11, and this steep decrease in the melt viscosity can be associated to the hydrolyse reaction of nylon for high pulp fibre moisture content at high temperature. In addition to the low processing temperature, the melt viscosity of the biocomposite using the Brabender mixer approach increases with increasing shear rate, and this stability in the increase even at high shear rate for high pulp moisture content is associated to the presence of inorganic salt lithium chloride which creates the hydrogen bonds with pulp during the compounding process.展开更多
In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. Th...In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. The four Al I-neutral lines at 308.21, 309.27, 394.40 and 369.15 nm as well as Al II-ionic lines at 281.61, 385.64 and 466.30 nm are used for the determination of the electron temperature Te using Saha-Boltzmann plot method. The neutral aluminum lines were found to suffer from optical thickness which manifested itself on the form of scattered points around the Saha-Boltzmann line. The isolated optically thin hydrogen Hα-line at 656.27 nm appeared in the spectra under the same experimental conditions was used to correct the Al I-lines which contained some optical thickness. The measurements were repeated at different delay times ranging from 1 to 5 μs. The comparison between the deduced electron temperatures from aluminum neutral lines before correction against the effect self-absorption to that after correction revealed a precise value in temperature. The results sure that, in case of the presence of self-absorption effect the temperature varies from (1.4067 - 1.2548 eV) as the delay time is varied from 0 to 5 μs. Whereas, in the case of repairing against the effect, it varies from (1.2826 - 0.8961 eV) for the same delay time variation.展开更多
Our research objective was to expand the very limited knowledgebase pertaining to the ecology of fringing coral reefs in the Gulf of Suez, Egypt. Specifically, determine dominant coral species and investigate why this...Our research objective was to expand the very limited knowledgebase pertaining to the ecology of fringing coral reefs in the Gulf of Suez, Egypt. Specifically, determine dominant coral species and investigate why this reef is capable of surviving at such a high-latitude and extreme harsh environment. Data collection included annual reef surveys, randomized quadrat sampling, five permanent video transects and in situ seawater temperature. Of the known Gulf of Suez 35 taxa, only six (Acropora humilis, A. microclados, A. hemprichii, Litophyton arboretum, Stylophora pistillata, Porites columna, and P. plantulata), compose 94% of the reef's coral cover. Coral dominance across species shifted drastically during the study period. However, the six coral dominance remained unchanged, while some decreased others increased. These six coral taxa regularly experience daily changes in seawater temperature and seasonal variations that exceed These extreme temperatures variation and the fact that only six coral taxa dominance remained unchanged, suggest that these corals may have developed a mechanism to cope with extreme seawater temperatures as evidenced by their continued growth and survival over the study period. We speculate that species dominance shift occurred largely as a result of a local oil spill rather than exposure to extreme temperatures. Further scrutiny of these species and the mechanisms by which they are able to thrive is recommended, as they hold the potential to benefit other coral communities as a resilient transplant species and model for understanding coral survivability in extreme environmental conditions.展开更多
To effectively solve the problem of lost circulation and well kick frequently occurring during the drilling of abnormally high temperature and pressure fractured-vuggy reservoirs in the Tazhong block, a rigid particle...To effectively solve the problem of lost circulation and well kick frequently occurring during the drilling of abnormally high temperature and pressure fractured-vuggy reservoirs in the Tazhong block, a rigid particle material, GZD, with high temperature tolerance, high rigidity(> 8 MPa) and low abrasiveness has been selected based on geological characteristics of the theft zones in the reservoirs. Through static pressure sealing experiments, its dosage when used alone and when used in combination with lignin fiber, elastic material SQD-98 and calcium carbonate were optimized, and the formula of a new type(SXM-I) of compound lost circulation material with high temperature tolerance and high strength was formed. Its performance was evaluated by compatibility test, static sealing experiment and sand bed plugging experiment. The test results show that it has good compatibility with drilling fluid used commonly and is able to plug fractures and vugs, the sealed fractures are able to withstand the static pressure of more than 9 MPa and the cumulative leakage is 13.4 mL. The mud filtrate invasion depth is only 2.5 cm in 30 min when the sand bed is made of particles with sizes between 10 mesh and 20 mesh. Overall, with good sealing property and high temperature and high pressure tolerance, the lost circulation material provides strong technical support for the safety drilling in the block.展开更多
The description of experimentally observed phenomenon of abnormally high electrical conductivity—'superconductivity' (SC) at the room and higher temperatures is represented. The effect was observed in metalli...The description of experimentally observed phenomenon of abnormally high electrical conductivity—'superconductivity' (SC) at the room and higher temperatures is represented. The effect was observed in metallic monospirals of small radius curvature with high density and regular distribution of dislocations. Transition into state of SC has been observed experimentally in the range from –50 up to 3000°C at the density of transmitting current up to 2·109 A/cm2. The experimental data confirming the watched phenomenon are represented. The explanations of this phenomenon are being proposed in the framework of the dislocation model.展开更多
The assumption of M. Milankovich about the constancy of the Earth's albedo during the interglacial period was replaced with the alternative one. The model was developed where anomalies of the average annual temper...The assumption of M. Milankovich about the constancy of the Earth's albedo during the interglacial period was replaced with the alternative one. The model was developed where anomalies of the average annual temperature of the surface atmosphere were related with interannual changes in the planetary albedo and the thermal inertia of the hydrosphere. The surface temperature changes due to albedo actual and model changes were calculated. Possible external causes of albedo changes were considered.展开更多
In this paper, the model output machine learning (MOML) method is proposed for simulating weather consultation, which can improve the forecast results of numerical weather prediction (NWP). During weather consultation...In this paper, the model output machine learning (MOML) method is proposed for simulating weather consultation, which can improve the forecast results of numerical weather prediction (NWP). During weather consultation, the forecasters obtain the final results by combining the observations with the NWP results and giving opinions based on their experience. It is obvious that using a suitable post-processing algorithm for simulating weather consultation is an interesting and important topic. MOML is a post-processing method based on machine learning, which matches NWP forecasts against observations through a regression function. By adopting different feature engineering of datasets and training periods, the observational and model data can be processed into the corresponding training set and test set. The MOML regression function uses an existing machine learning algorithm with the processed dataset to revise the output of NWP models combined with the observations, so as to improve the results of weather forecasts. To test the new approach for grid temperature forecasts, the 2-m surface air temperature in the Beijing area from the ECMWF model is used. MOML with different feature engineering is compared against the ECMWF model and modified model output statistics (MOS) method. MOML shows a better numerical performance than the ECMWF model and MOS, especially for winter. The results of MOML with a linear algorithm, running training period, and dataset using spatial interpolation ideas, are better than others when the forecast time is within a few days. The results of MOML with the Random Forest algorithm, year-round training period, and dataset containing surrounding gridpoint information, are better when the forecast time is longer.展开更多
Polymer Electrolyte Fuel Cell(PEFC)is desired to be operated at temperature around 90℃ for stationary applications during the period from 2020 to 2025 in Japan.It can be expected thinner polymer electrolyte membrane(...Polymer Electrolyte Fuel Cell(PEFC)is desired to be operated at temperature around 90℃ for stationary applications during the period from 2020 to 2025 in Japan.It can be expected thinner polymer electrolyte membrane(PEM)and gas diffusion layer(GDL)would promote the power generation performance of PEFC at this temperature.The aim of this study is to understand the impact of thickness of PEM and GDL on the temperature profile of interface between PEM and catalyst layer at the cathode(i.e.,the reaction surface)in a single PEFC with an initial operation temperature(Tini).An 1D multi-plate heat transfer model based on temperature data of separator measured using thermograph in power generation process was developed to evaluate temperature of the reaction surface(Treact).This study investigated the effect of Tini,flow rate and relative humidity of supply gas on Treact distribution.The study finds that when using thin GDL,the even distribution of Treact – Tini is obtained irrespective of thickness of PEM,Tini and relative humidity conditions.Treact – Tini using Nafion 115 is higher than the other thin PEMs irrespective of Tini and relative humidity conditions.It can be concluded that the even temperature distribution could be achieved by using thin PEM and GDL.展开更多
The effects of tidal currents(i.e., barotropic and internal tides) are important in the biogeochemistry of a coastal shelf sea. The high-frequency of currents and near-bottom temperatures collected in three consecutiv...The effects of tidal currents(i.e., barotropic and internal tides) are important in the biogeochemistry of a coastal shelf sea. The high-frequency of currents and near-bottom temperatures collected in three consecutive southwest monsoon seasons(May, June, July and August of 2013 until 2015) is presented to reveal the role of the tidal currents to the temperature variability in the coastal shelf sea of the east coast of Peninsular Malaysia(ECPM),south of the South China Sea(SCS). The results of a spectral density and harmonic analysis demonstrate that the near-bottom temperature variability and the tidal currents are influenced by diurnal(O_1 and K_1) and semidiurnal(M_2) tidal currents. The spectral density of residual currents(detided data) at 5, 10 and 16 m depth also shows significant peaks at the diurnal tidal frequency(K_1) and small peaks at the semidiurnal tidal frequency(M_2)indicating the existence of internal tides. The result of the horizontal kinetic energy(HKE) shows a strong intermittent energy of internal tides in the ECPM with the strongest energy is found at 16 m depth during a sporadic cooling event in June and July. A high horizontal cross-shore heat flux(16 m) also indicates strong intrusions of cooler water into the ECPM in June and July. During the short duration of cold pulse water observed in June and July, a cross-wavelet analysis also reveals the strong relationship between the near-bottom temperatures and the internal tidal currents at the diurnal tidal frequency. The intrusion of this cooler water is probably related to the monsoon-induced upwelling in June. It is loosely interpreted that the interaction between the strong barotropic tides and the steep slope in the central basin of the SCS under the stratified condition in southwest monsoon has generated these internal tides. The dissipation of internal tides from the slope area probably has driven the cold-upwelled water into the ECPM coastal shelf sea when the upwelling intensity is the highest in June and July.展开更多
This paper presents,using Lyapunov-Krasovskii functional technique combined with reciprocal convex lemma is considered for a networked control temperature control system with additive time-varying-delays.In the stabil...This paper presents,using Lyapunov-Krasovskii functional technique combined with reciprocal convex lemma is considered for a networked control temperature control system with additive time-varying-delays.In the stability analysis,a new LK functional is assumed,and take the time-derivative of the(LK)functional,using reciprocal convex combination technique was employed to obtain less conservative stability criteria.Finally,the proposed stability analysis culminates into a stability criterion in the LMI(linear matrix inequalities)framework.The results obtained are in accordance with the theoretically obtained in the temperature control system and they are closer to the standard benchmark temperature-control system.展开更多
Understanding the temperature dependent deformation behavior of Mg alloys is crucial for their expanding use in the aerospace sector.This study investigates the deformation mechanisms of hot-rolled AZ61 Mg alloy under...Understanding the temperature dependent deformation behavior of Mg alloys is crucial for their expanding use in the aerospace sector.This study investigates the deformation mechanisms of hot-rolled AZ61 Mg alloy under uniaxial tension along rolling direction(RD)and transverse direction(TD)at-50,25,50,and 150℃.Results reveal a transition from high strength with limited elongation at-50℃ to significant softening and maximum ductility at 150℃.TD samples consistently showed 2%-6%higher strength than RD;however,this yield anisotropy diminished at 150℃ due to the shift from twinning to thermally activated slip and recovery.Fractography indicated a change from semi-brittle to fully ductile fracture with increasing temperature.Electron backscattered diffraction(EBSD)analysis confirmed twinning-driven grain refinement at low temperatures,while deformation at high temperatures involved grain elongation along shear zones,enabling greater strain accommodation before material failure.展开更多
In this study, an etched-SiO-film grating fabrication technique based on solute-solvent separation soft lithography is developed. By using this new technique, high temperature grating with frequency of 600 lines/mm is...In this study, an etched-SiO-film grating fabrication technique based on solute-solvent separation soft lithography is developed. By using this new technique, high temperature grating with frequency of 600 lines/mm is successfully fabricated on the surface of thermal barrier coatings(TBCs). During the fabrication process, the microstructure and chemical compositions of ceramic coating before and after polishing is analyzed with a digital microscope and the energy dispersive X-ray spectroscope(EDS) in scanning electron microscope(SEM). And then the grating on TBCs is heated at the temperature ranging from 300℃ to 1000℃ for examining the high temperature resistance. In the practical application, the displacement and strain field around the crack on the ceramic surface are investigated with geometry phase analysis(GPA). The successful results verify that the etched-SiO-film grating has a good oxidation resistance and can be applied to high temperature deformation measurement of TBCs.展开更多
Hydrostatic cyclic expansion extrusion(HCEE) process at elevated temperatures is proposed as a method for processing less deformable materials such as magnesium and for producing long ultrafine-grained rods. In the HC...Hydrostatic cyclic expansion extrusion(HCEE) process at elevated temperatures is proposed as a method for processing less deformable materials such as magnesium and for producing long ultrafine-grained rods. In the HCEE process at elevated temperatures, high-pressure molten linear low-density polyethylene(LLDPE) was used as a fluid to eliminate frictional forces. To study the capability of the process,AM60 magnesium rods were processed and the properties were investigated. The mechanical properties were found to improve significantly after the HCEE process. The yield and ultimate strengths increased from initial values of 138 and 221 MPa to 212 and 317 MPa, respectively.Moreover, the elongation was enhanced due to the refined grains and the existence of high hydrostatic pressure. Furthermore, the microhardness was increased from HV 55.0 to HV 72.5. The microstructural analysis revealed that ultrafine-grained structure could be produced by the HCEE process. Moreover, the size of the particles decreased, and these particles thoroughly scattered between the grains. Finite element analysis showed that the HCEE was independent of the length of the sample, which makes the process suitable for industrial applications.展开更多
By adopting characteristic index data for the Western Pacific Subtropical High(WPSH) from the National Climate Center of China, U.S. National Centers for Environmental Prediction-National Center for Atmospheric Resear...By adopting characteristic index data for the Western Pacific Subtropical High(WPSH) from the National Climate Center of China, U.S. National Centers for Environmental Prediction-National Center for Atmospheric Research(NCEP/NCAR) reanalysis data, and the National Oceanic and Atmospheric Administration(NOAA) sea surface temperature(SST) data, we studied the WPSH variability considering the background of climate warming by using a Gaussian filter, moving averages, correlation analysis, and synthetic analysis. Our results show that with climate warming over the past 60 years, significant changes in the WPSH include its enlarged area, strengthened intensity,westward extended ridge point and southward expanded southern boundary, as well as enhanced interannual fluctuations in all these indices. The western ridge point of the WPSH consistently varies with temperature changes in the Northern Hemisphere, but the location of the ridgeline varies independently. The intensity and area of the WPSH were both significantly increased in the late 1980 s. Specifically, the western ridge point started to significantly extend westward in the early 1990 s, and the associated interannual variability had a significant increase in the late 1990 s; in addition, the ridgeline was swaying along the north-south-north direction, and the corresponding variability was also greatly enhanced in the late 1990 s. With climate warming, the SST increase becomes more weakly correlated with the WPSH intensity enhancement but more strongly correlated with the westward extension of the ridge point in the equatorial central and eastern Pacific Ocean in winter, corresponding to an expanding WPSH in space. In the northern Pacific in winter, the SST decrease has a weaker correlation with the southerly location of the ridgeline but also a stronger correlation with the westward extension of the ridge point. In the tropical western Pacific in winter, the correlations of the SST decrease with the WPSH intensity enhancement, and the westward extension of the ridge point is strengthened. These observations can be explained by strengthened Hadley circulations, the dominant effects of the southward shift, and additional effects of the weakened ascending branch of the Walker circulation during warm climatological periods,which consequently lead to strengthened intensities, increased areas, and southward expansions of the WPSH in summer.展开更多
文摘The article considers one of the possible approaches to the solution of an urgent issue of metal consumption reduction, increase of operating life and maximum operating temperature as well as reduction of irrecoverable losses of platinum products and alloys when operating under high temperature conditions, particularly for glassblowing and single crystal growing crucibles. A two-layered composite material based on platinum-group metals and corundum plasma ceramics is thoroughly investigated. A successful experience of crucibles exploitation, designed for production of high temperature optical glasses from the composite and results of the research on composite material specimens are described.
基金Supported by the China’s National Key Research and Development Projects(No.2016YFA0601803)the National Natural Science Foundation of China(Nos.41490641,41521091,U1606402)the Qingdao National Laboratory for Marine Science and Technology(No.2017ASKJ01)
文摘The co-variation of surface wind speed and sea surface temperature (SST) over the Gulf Stream frontal region is investigated using high-resolution satellite measurements and atmospheric reanalysis data. Results show that the pattern of positive SST-surface wind speed correlations is anchored by strong SST gradient and marine atmospheric boundary layer (MABL) height front, with active warm and cold-ocean eddies around. The MABL has an obvious transitional structure along the strong SST front, with greater (lesser) heights over the north (south) side. The significant positive SST-surface wind-speed perturbation correlations are mostly found over both strong warm and cold eddies. The surface wind speed increases (decreases) about 0.32 (0.41) m/s and the MABL elevates (drops) approximate 55 (54) m per 1℃ of SST perturbation induced by warm (cold) eddies. The response of the surface wind speed to SST perturbations over the mesoscale eddies is mainly attributed to the momentum vertical mixing in the MABL, which is confirmed by the linear relationships between the downwind (crosswind) SST gradient and wind divergence (curl).
文摘Applications, theoretical analysis and numerical methods are introduced for the simulation of mechanical models and principles of the porous flow in high temperature, high salt, complicated geology and large-scale reservoirs in this paper. Considering petroleum geology, geochemistry, computational permeation fluid mechanics and computer technology, we state the models of permeation fluid mechanics and put forward a sequence of implicit upwind difference iteration schemes based on refined fractional steps of the upstream, which can compute the pressures, the saturation and the concentrations of different chemistry components. A type of software applicable in major industries has been completed and carried out in numerical analysis and simulations of oil extraction in Shengli Oil-field, which brings huge economic benefits and social benefits. This software gives many characters: spatial steps are taken as ten meters, the number of nodes is up to hundreds of thousands and simulation time period can be tens of years and the high-order accuracy can be promised in numerical data. Precise analysis is present for simplified models of this type and that provides a tool to solve the international famous problem.
文摘The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5oC up to 50oC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed.
文摘The aim of this work was to investigate the effect of lithium chloride (LiCl) on the fibre length distribution, melting temperature and the rheological characteristics of high yield pulp fibre reinforced polyamide biocomposite. The inorganic salt lithium chloride (LiCl) was used to decrease the melting and processing temperature of bio-based polyamide 11. The extrusion method and Brabender mixer approaches were used to carry out the compounding process. The densities and fibre content were found to be increased after processing using both compounding methods. The HYP fibre length distribution analysis realized using the FQA equipment showed an important fibre-length reduction after processing by both techniques. The rheological properties of HYP-reinforced net and modified bio-based polyamide 11 “PA11” (HYP/PA11) composite were investigated using a capillary rheometer. The rheological tests were performed in function of the shear rate for different temperature conditions. The low-temperature process compounding had higher shear viscosity;this was because during the process the temperature was low and the mixing and melting were induced by the high shear rate created during compounding process. Experimental test results using the extrusion process showed a steep decrease in shear viscosity with increasing shear rate, and this melt-flow characteristic corresponds to shear-thinning behavior in HYP/PA11, and this steep decrease in the melt viscosity can be associated to the hydrolyse reaction of nylon for high pulp fibre moisture content at high temperature. In addition to the low processing temperature, the melt viscosity of the biocomposite using the Brabender mixer approach increases with increasing shear rate, and this stability in the increase even at high shear rate for high pulp moisture content is associated to the presence of inorganic salt lithium chloride which creates the hydrogen bonds with pulp during the compounding process.
文摘In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. The four Al I-neutral lines at 308.21, 309.27, 394.40 and 369.15 nm as well as Al II-ionic lines at 281.61, 385.64 and 466.30 nm are used for the determination of the electron temperature Te using Saha-Boltzmann plot method. The neutral aluminum lines were found to suffer from optical thickness which manifested itself on the form of scattered points around the Saha-Boltzmann line. The isolated optically thin hydrogen Hα-line at 656.27 nm appeared in the spectra under the same experimental conditions was used to correct the Al I-lines which contained some optical thickness. The measurements were repeated at different delay times ranging from 1 to 5 μs. The comparison between the deduced electron temperatures from aluminum neutral lines before correction against the effect self-absorption to that after correction revealed a precise value in temperature. The results sure that, in case of the presence of self-absorption effect the temperature varies from (1.4067 - 1.2548 eV) as the delay time is varied from 0 to 5 μs. Whereas, in the case of repairing against the effect, it varies from (1.2826 - 0.8961 eV) for the same delay time variation.
文摘Our research objective was to expand the very limited knowledgebase pertaining to the ecology of fringing coral reefs in the Gulf of Suez, Egypt. Specifically, determine dominant coral species and investigate why this reef is capable of surviving at such a high-latitude and extreme harsh environment. Data collection included annual reef surveys, randomized quadrat sampling, five permanent video transects and in situ seawater temperature. Of the known Gulf of Suez 35 taxa, only six (Acropora humilis, A. microclados, A. hemprichii, Litophyton arboretum, Stylophora pistillata, Porites columna, and P. plantulata), compose 94% of the reef's coral cover. Coral dominance across species shifted drastically during the study period. However, the six coral dominance remained unchanged, while some decreased others increased. These six coral taxa regularly experience daily changes in seawater temperature and seasonal variations that exceed These extreme temperatures variation and the fact that only six coral taxa dominance remained unchanged, suggest that these corals may have developed a mechanism to cope with extreme seawater temperatures as evidenced by their continued growth and survival over the study period. We speculate that species dominance shift occurred largely as a result of a local oil spill rather than exposure to extreme temperatures. Further scrutiny of these species and the mechanisms by which they are able to thrive is recommended, as they hold the potential to benefit other coral communities as a resilient transplant species and model for understanding coral survivability in extreme environmental conditions.
基金Supported by the China National Science and Technology Major Project(2011ZX05042-002-001)
文摘To effectively solve the problem of lost circulation and well kick frequently occurring during the drilling of abnormally high temperature and pressure fractured-vuggy reservoirs in the Tazhong block, a rigid particle material, GZD, with high temperature tolerance, high rigidity(> 8 MPa) and low abrasiveness has been selected based on geological characteristics of the theft zones in the reservoirs. Through static pressure sealing experiments, its dosage when used alone and when used in combination with lignin fiber, elastic material SQD-98 and calcium carbonate were optimized, and the formula of a new type(SXM-I) of compound lost circulation material with high temperature tolerance and high strength was formed. Its performance was evaluated by compatibility test, static sealing experiment and sand bed plugging experiment. The test results show that it has good compatibility with drilling fluid used commonly and is able to plug fractures and vugs, the sealed fractures are able to withstand the static pressure of more than 9 MPa and the cumulative leakage is 13.4 mL. The mud filtrate invasion depth is only 2.5 cm in 30 min when the sand bed is made of particles with sizes between 10 mesh and 20 mesh. Overall, with good sealing property and high temperature and high pressure tolerance, the lost circulation material provides strong technical support for the safety drilling in the block.
文摘The description of experimentally observed phenomenon of abnormally high electrical conductivity—'superconductivity' (SC) at the room and higher temperatures is represented. The effect was observed in metallic monospirals of small radius curvature with high density and regular distribution of dislocations. Transition into state of SC has been observed experimentally in the range from –50 up to 3000°C at the density of transmitting current up to 2·109 A/cm2. The experimental data confirming the watched phenomenon are represented. The explanations of this phenomenon are being proposed in the framework of the dislocation model.
文摘The assumption of M. Milankovich about the constancy of the Earth's albedo during the interglacial period was replaced with the alternative one. The model was developed where anomalies of the average annual temperature of the surface atmosphere were related with interannual changes in the planetary albedo and the thermal inertia of the hydrosphere. The surface temperature changes due to albedo actual and model changes were calculated. Possible external causes of albedo changes were considered.
基金supported by the National Key Research and Development Program of China (Grant Nos. 2018YFF0300104 and 2017YFC0209804)the National Natural Science Foundation of China (Grant No. 11421101)Beijing Academy of Artifical Intelligence (BAAI)
文摘In this paper, the model output machine learning (MOML) method is proposed for simulating weather consultation, which can improve the forecast results of numerical weather prediction (NWP). During weather consultation, the forecasters obtain the final results by combining the observations with the NWP results and giving opinions based on their experience. It is obvious that using a suitable post-processing algorithm for simulating weather consultation is an interesting and important topic. MOML is a post-processing method based on machine learning, which matches NWP forecasts against observations through a regression function. By adopting different feature engineering of datasets and training periods, the observational and model data can be processed into the corresponding training set and test set. The MOML regression function uses an existing machine learning algorithm with the processed dataset to revise the output of NWP models combined with the observations, so as to improve the results of weather forecasts. To test the new approach for grid temperature forecasts, the 2-m surface air temperature in the Beijing area from the ECMWF model is used. MOML with different feature engineering is compared against the ECMWF model and modified model output statistics (MOS) method. MOML shows a better numerical performance than the ECMWF model and MOS, especially for winter. The results of MOML with a linear algorithm, running training period, and dataset using spatial interpolation ideas, are better than others when the forecast time is within a few days. The results of MOML with the Random Forest algorithm, year-round training period, and dataset containing surrounding gridpoint information, are better when the forecast time is longer.
文摘Polymer Electrolyte Fuel Cell(PEFC)is desired to be operated at temperature around 90℃ for stationary applications during the period from 2020 to 2025 in Japan.It can be expected thinner polymer electrolyte membrane(PEM)and gas diffusion layer(GDL)would promote the power generation performance of PEFC at this temperature.The aim of this study is to understand the impact of thickness of PEM and GDL on the temperature profile of interface between PEM and catalyst layer at the cathode(i.e.,the reaction surface)in a single PEFC with an initial operation temperature(Tini).An 1D multi-plate heat transfer model based on temperature data of separator measured using thermograph in power generation process was developed to evaluate temperature of the reaction surface(Treact).This study investigated the effect of Tini,flow rate and relative humidity of supply gas on Treact distribution.The study finds that when using thin GDL,the even distribution of Treact – Tini is obtained irrespective of thickness of PEM,Tini and relative humidity conditions.Treact – Tini using Nafion 115 is higher than the other thin PEMs irrespective of Tini and relative humidity conditions.It can be concluded that the even temperature distribution could be achieved by using thin PEM and GDL.
基金The Higher Institutional Centre of Excellent Universiti Malaysia Terengganu under contract No.TJ66928the Malaysia Coastal Observation Network Project under the Institute of Oceanography and Environment,Universiti Malaysia Terengganu of Malaysia
文摘The effects of tidal currents(i.e., barotropic and internal tides) are important in the biogeochemistry of a coastal shelf sea. The high-frequency of currents and near-bottom temperatures collected in three consecutive southwest monsoon seasons(May, June, July and August of 2013 until 2015) is presented to reveal the role of the tidal currents to the temperature variability in the coastal shelf sea of the east coast of Peninsular Malaysia(ECPM),south of the South China Sea(SCS). The results of a spectral density and harmonic analysis demonstrate that the near-bottom temperature variability and the tidal currents are influenced by diurnal(O_1 and K_1) and semidiurnal(M_2) tidal currents. The spectral density of residual currents(detided data) at 5, 10 and 16 m depth also shows significant peaks at the diurnal tidal frequency(K_1) and small peaks at the semidiurnal tidal frequency(M_2)indicating the existence of internal tides. The result of the horizontal kinetic energy(HKE) shows a strong intermittent energy of internal tides in the ECPM with the strongest energy is found at 16 m depth during a sporadic cooling event in June and July. A high horizontal cross-shore heat flux(16 m) also indicates strong intrusions of cooler water into the ECPM in June and July. During the short duration of cold pulse water observed in June and July, a cross-wavelet analysis also reveals the strong relationship between the near-bottom temperatures and the internal tidal currents at the diurnal tidal frequency. The intrusion of this cooler water is probably related to the monsoon-induced upwelling in June. It is loosely interpreted that the interaction between the strong barotropic tides and the steep slope in the central basin of the SCS under the stratified condition in southwest monsoon has generated these internal tides. The dissipation of internal tides from the slope area probably has driven the cold-upwelled water into the ECPM coastal shelf sea when the upwelling intensity is the highest in June and July.
文摘This paper presents,using Lyapunov-Krasovskii functional technique combined with reciprocal convex lemma is considered for a networked control temperature control system with additive time-varying-delays.In the stability analysis,a new LK functional is assumed,and take the time-derivative of the(LK)functional,using reciprocal convex combination technique was employed to obtain less conservative stability criteria.Finally,the proposed stability analysis culminates into a stability criterion in the LMI(linear matrix inequalities)framework.The results obtained are in accordance with the theoretically obtained in the temperature control system and they are closer to the standard benchmark temperature-control system.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea Program(No.RS-2025-02603127,Innovation Research Center for Zero-carbon Fuel Gas Turbine Design,Manufacture,and Safety)。
文摘Understanding the temperature dependent deformation behavior of Mg alloys is crucial for their expanding use in the aerospace sector.This study investigates the deformation mechanisms of hot-rolled AZ61 Mg alloy under uniaxial tension along rolling direction(RD)and transverse direction(TD)at-50,25,50,and 150℃.Results reveal a transition from high strength with limited elongation at-50℃ to significant softening and maximum ductility at 150℃.TD samples consistently showed 2%-6%higher strength than RD;however,this yield anisotropy diminished at 150℃ due to the shift from twinning to thermally activated slip and recovery.Fractography indicated a change from semi-brittle to fully ductile fracture with increasing temperature.Electron backscattered diffraction(EBSD)analysis confirmed twinning-driven grain refinement at low temperatures,while deformation at high temperatures involved grain elongation along shear zones,enabling greater strain accommodation before material failure.
基金financially supported by the National Natural Science Foundation of China(11672153,11232008)
文摘In this study, an etched-SiO-film grating fabrication technique based on solute-solvent separation soft lithography is developed. By using this new technique, high temperature grating with frequency of 600 lines/mm is successfully fabricated on the surface of thermal barrier coatings(TBCs). During the fabrication process, the microstructure and chemical compositions of ceramic coating before and after polishing is analyzed with a digital microscope and the energy dispersive X-ray spectroscope(EDS) in scanning electron microscope(SEM). And then the grating on TBCs is heated at the temperature ranging from 300℃ to 1000℃ for examining the high temperature resistance. In the practical application, the displacement and strain field around the crack on the ceramic surface are investigated with geometry phase analysis(GPA). The successful results verify that the etched-SiO-film grating has a good oxidation resistance and can be applied to high temperature deformation measurement of TBCs.
基金This work was financially supported by the Iran National Science Foundation(No.96000854).
文摘Hydrostatic cyclic expansion extrusion(HCEE) process at elevated temperatures is proposed as a method for processing less deformable materials such as magnesium and for producing long ultrafine-grained rods. In the HCEE process at elevated temperatures, high-pressure molten linear low-density polyethylene(LLDPE) was used as a fluid to eliminate frictional forces. To study the capability of the process,AM60 magnesium rods were processed and the properties were investigated. The mechanical properties were found to improve significantly after the HCEE process. The yield and ultimate strengths increased from initial values of 138 and 221 MPa to 212 and 317 MPa, respectively.Moreover, the elongation was enhanced due to the refined grains and the existence of high hydrostatic pressure. Furthermore, the microhardness was increased from HV 55.0 to HV 72.5. The microstructural analysis revealed that ultrafine-grained structure could be produced by the HCEE process. Moreover, the size of the particles decreased, and these particles thoroughly scattered between the grains. Finite element analysis showed that the HCEE was independent of the length of the sample, which makes the process suitable for industrial applications.
基金National Key Basic Research and Development Planning Program of China(Program 973)(2013CB430202)China Special Fund for Meteorological Research in the Public Interest(Major Projects)(GYHY201506001-1)National Natural Science Foundation of China(91337109,41305080)
文摘By adopting characteristic index data for the Western Pacific Subtropical High(WPSH) from the National Climate Center of China, U.S. National Centers for Environmental Prediction-National Center for Atmospheric Research(NCEP/NCAR) reanalysis data, and the National Oceanic and Atmospheric Administration(NOAA) sea surface temperature(SST) data, we studied the WPSH variability considering the background of climate warming by using a Gaussian filter, moving averages, correlation analysis, and synthetic analysis. Our results show that with climate warming over the past 60 years, significant changes in the WPSH include its enlarged area, strengthened intensity,westward extended ridge point and southward expanded southern boundary, as well as enhanced interannual fluctuations in all these indices. The western ridge point of the WPSH consistently varies with temperature changes in the Northern Hemisphere, but the location of the ridgeline varies independently. The intensity and area of the WPSH were both significantly increased in the late 1980 s. Specifically, the western ridge point started to significantly extend westward in the early 1990 s, and the associated interannual variability had a significant increase in the late 1990 s; in addition, the ridgeline was swaying along the north-south-north direction, and the corresponding variability was also greatly enhanced in the late 1990 s. With climate warming, the SST increase becomes more weakly correlated with the WPSH intensity enhancement but more strongly correlated with the westward extension of the ridge point in the equatorial central and eastern Pacific Ocean in winter, corresponding to an expanding WPSH in space. In the northern Pacific in winter, the SST decrease has a weaker correlation with the southerly location of the ridgeline but also a stronger correlation with the westward extension of the ridge point. In the tropical western Pacific in winter, the correlations of the SST decrease with the WPSH intensity enhancement, and the westward extension of the ridge point is strengthened. These observations can be explained by strengthened Hadley circulations, the dominant effects of the southward shift, and additional effects of the weakened ascending branch of the Walker circulation during warm climatological periods,which consequently lead to strengthened intensities, increased areas, and southward expansions of the WPSH in summer.
