Ice accretion on aircraft encountering supercooled water droplets in clouds poses great risks to flight performance and safety.With the aim of optimizing the newly developed streamwise plasma heat knife method for ant...Ice accretion on aircraft encountering supercooled water droplets in clouds poses great risks to flight performance and safety.With the aim of optimizing the newly developed streamwise plasma heat knife method for anti-icing,a parametric investigation is carried out in this work.The influence of the detailed voltage profile on the heating effects of a Surface Dielectric Barrier Discharge driven by Nanosecond Pulses(NS-SDBD)is investigated,and a comparison of the antiicing performance among different configurations of streamwise plasma heat knife is made.The results show that columnar high-temperature regions produced by a multi-streamer discharge appear at small pulse rise time,but become diffuse as the pulse rise time increases.An optimal pulse rise time exists to provide a wide range and high value of temperature,which is found to be 150 ns for the setup in the present study.The influence of the pulse fall time is much weaker than that of the rise time.The range and value of the temperature decrease with increasing pulse fall time.A greater pulse width is found to improve the heating effect by increasing the discharge power.When a spanwise electrode is placed connecting the streamwise electrodes of the streamwise plasma heat knife at the airfoil leading edge,the anti-icing performance becomes poorer,whereas good performance is achieved when the spanwise electrode is at the edge of the streamwise electrodes.Based on this,a three-level configuration of the plasma heat knife is proposed,and its anti-icing performance is found to be much better than that of the original configuration.展开更多
Coastal erosion, subsidence, salt water intrusion, and hypoxia are forces that impact Louisiana and beyond. The objective of this research was to determine the extent of land loss due to erosion and establish the best...Coastal erosion, subsidence, salt water intrusion, and hypoxia are forces that impact Louisiana and beyond. The objective of this research was to determine the extent of land loss due to erosion and establish the best Spartina (S.) species to ameliorate the coast. Using graph theory in the Geometer’s Sketch Pad program, progressive land loss from Isles Dernieres was determined from 1853 to 2005. This was accomplished using Pick’s Theorem (A = I + B/2 - 1), where A = total land area, I = interior intersections, and B = boundary intersections. The analysis indicated that there had been more than ninety percent land loss from 1853 to 2005. Additionally, four plants from each Spartina species (alterniflora, patens, and spartinae) were planted and flooded in four containers, respectively, filled with potting soil, and a non-vegetated control was included in this same manner. Dissolved oxygen was measured three times a week under three different temperature regimes, twenty-two, thirty, and ten degrees Celsius, respectively. This resulted in the control group diffusing the most oxygen at twenty-two degrees Celsius, the S. alterniflora diffusing the most oxygen at thirty degrees Celsius, and all the species diffusing statistically similar oxygen levels at ten degrees Celsius. After six months of flooded conditions, penetration and subsidence were measured. The vegetated soils required the greatest penetration forces and subsided the least. Oxygen diffusion is dependent on plant species and temperature. The penetration and subsidence results also support the conclusion that plants can reduce land loss and preserve the coastline.展开更多
In the past 80 years, Louisiana has lost over one million acres in land, affecting plants and crustaceans that live in these environments. The first objective of this research was to determine the relationship between...In the past 80 years, Louisiana has lost over one million acres in land, affecting plants and crustaceans that live in these environments. The first objective of this research was to determine the relationship between diffused oxygen in water and time with the behavioral and physiological health of Callinectes sapidus (blue crab) and Procambarus clarkii (crawfish). After 24 hours, manual dexterity, or the amount of time it takes for a crustacean to flip itself over increased under hypoxic conditions. Hemolymph was extracted and tested for lactate, glucose, and protein. Crawfish were also exposed to this same procedure. An additional crawfish study comparing Spartina plants to assimilate oxygen for aeration compared to mechanical aeration was conducted. The hypoxic groups for all three studies at the 0.05 level had a significantly greater manual dexterity time and greater amounts of lactate and glucose. The protein was significantly higher in hypoxia-exposed crawfish. Time and aeration affect the health of crustaceans, and plants were shown to effectively provide normoxic oxygen levels at a similar level as mechanical aeration. These studies support the importance of marsh grasses for the coast and crustacean viability.展开更多
基金co-supported by the National Natural Science Foundation of China(Nos.12002384 and 11802341)National Science and Technology Major Project of China(No.J2019-Ⅱ-0014-0035)+1 种基金National Key Laboratory Fund of China(No.614220220200109)the Academician Workstation Foundation of the Green Aerotechnics Research Institute of Chongqing Jiaotong University,China(No.GATRI2020C06003)。
文摘Ice accretion on aircraft encountering supercooled water droplets in clouds poses great risks to flight performance and safety.With the aim of optimizing the newly developed streamwise plasma heat knife method for anti-icing,a parametric investigation is carried out in this work.The influence of the detailed voltage profile on the heating effects of a Surface Dielectric Barrier Discharge driven by Nanosecond Pulses(NS-SDBD)is investigated,and a comparison of the antiicing performance among different configurations of streamwise plasma heat knife is made.The results show that columnar high-temperature regions produced by a multi-streamer discharge appear at small pulse rise time,but become diffuse as the pulse rise time increases.An optimal pulse rise time exists to provide a wide range and high value of temperature,which is found to be 150 ns for the setup in the present study.The influence of the pulse fall time is much weaker than that of the rise time.The range and value of the temperature decrease with increasing pulse fall time.A greater pulse width is found to improve the heating effect by increasing the discharge power.When a spanwise electrode is placed connecting the streamwise electrodes of the streamwise plasma heat knife at the airfoil leading edge,the anti-icing performance becomes poorer,whereas good performance is achieved when the spanwise electrode is at the edge of the streamwise electrodes.Based on this,a three-level configuration of the plasma heat knife is proposed,and its anti-icing performance is found to be much better than that of the original configuration.
文摘Coastal erosion, subsidence, salt water intrusion, and hypoxia are forces that impact Louisiana and beyond. The objective of this research was to determine the extent of land loss due to erosion and establish the best Spartina (S.) species to ameliorate the coast. Using graph theory in the Geometer’s Sketch Pad program, progressive land loss from Isles Dernieres was determined from 1853 to 2005. This was accomplished using Pick’s Theorem (A = I + B/2 - 1), where A = total land area, I = interior intersections, and B = boundary intersections. The analysis indicated that there had been more than ninety percent land loss from 1853 to 2005. Additionally, four plants from each Spartina species (alterniflora, patens, and spartinae) were planted and flooded in four containers, respectively, filled with potting soil, and a non-vegetated control was included in this same manner. Dissolved oxygen was measured three times a week under three different temperature regimes, twenty-two, thirty, and ten degrees Celsius, respectively. This resulted in the control group diffusing the most oxygen at twenty-two degrees Celsius, the S. alterniflora diffusing the most oxygen at thirty degrees Celsius, and all the species diffusing statistically similar oxygen levels at ten degrees Celsius. After six months of flooded conditions, penetration and subsidence were measured. The vegetated soils required the greatest penetration forces and subsided the least. Oxygen diffusion is dependent on plant species and temperature. The penetration and subsidence results also support the conclusion that plants can reduce land loss and preserve the coastline.
文摘In the past 80 years, Louisiana has lost over one million acres in land, affecting plants and crustaceans that live in these environments. The first objective of this research was to determine the relationship between diffused oxygen in water and time with the behavioral and physiological health of Callinectes sapidus (blue crab) and Procambarus clarkii (crawfish). After 24 hours, manual dexterity, or the amount of time it takes for a crustacean to flip itself over increased under hypoxic conditions. Hemolymph was extracted and tested for lactate, glucose, and protein. Crawfish were also exposed to this same procedure. An additional crawfish study comparing Spartina plants to assimilate oxygen for aeration compared to mechanical aeration was conducted. The hypoxic groups for all three studies at the 0.05 level had a significantly greater manual dexterity time and greater amounts of lactate and glucose. The protein was significantly higher in hypoxia-exposed crawfish. Time and aeration affect the health of crustaceans, and plants were shown to effectively provide normoxic oxygen levels at a similar level as mechanical aeration. These studies support the importance of marsh grasses for the coast and crustacean viability.
