The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeogr...The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeographic studies(Wagner and Liebherr 1992;Peeters and Ito 2001;Helms 2018).展开更多
The rocket sled system is not only a high-speed dynamic ground test system,but also one of the future aerospace horizontal launch schemes.The winged load,as a common type of payload,has greater vibration and noise int...The rocket sled system is not only a high-speed dynamic ground test system,but also one of the future aerospace horizontal launch schemes.The winged load,as a common type of payload,has greater vibration and noise intensity than the wingless load.Due to the severe aerodynamic instability prior to separation,the head-up or head-down phenomena are more evident and the test accuracy significantly decreases.The high-precision computer fluid dynamics and aeroacoustic analysis are employed to explore the multifield coupling mechanism of a rocket sled with the winged payload in the wide speed range(Ma=0.5–2).The results show that as the incoming velocity increases,the cone angle of the shock wave of the rocket sled decreases,the shock pressure increases quickly,and the vortex between the slippers splits and gradually shrinks in size.The velocity of the rocket sled exerts little influence on the modal resonance frequency.The wing has a significant impact on aerodynamic noise,and as the sound pressure level rises,the propagation direction gradually shifts towards the rear and upper regions of the wing.展开更多
Synthetic analysis is conducted to the wind tunnel experiment results of zero lift drag coefficient and lift coefficient for large aspect ratio winged rigid body.By means of wind tunnel experiment data,the dynamics mo...Synthetic analysis is conducted to the wind tunnel experiment results of zero lift drag coefficient and lift coefficient for large aspect ratio winged rigid body.By means of wind tunnel experiment data,the dynamics model of the zero lift drag coefficient and lift coefficient for the large aspect ratio winged rigid body is amended.The research indicates that the change trends of zero lift drag coefficient and lift coefficient to Mach number are similar.The calculation result and wind tunnel experiment data all verify the validity of the amended dynamics model by which to estimate the zero lift drag coefficient and lift coefficient for the large aspect ratio winged rigid body,and thus providing some technical reference to aerodynamics character analysis of the same types of winged rigid body.展开更多
A total of 16 specimens of fossil-winged fruits were found from the Middle Miocene marine deposits, Duho Formation, Pohang Basin, Korea. They were identified into two structurally different groups： 15 specimens into ...A total of 16 specimens of fossil-winged fruits were found from the Middle Miocene marine deposits, Duho Formation, Pohang Basin, Korea. They were identified into two structurally different groups： 15 specimens into a winged fruit of Fraxinus, and one specimen of Liriodendron. The most samaras （13 specimens） were identified as Fraxinus oishii, which is characterized by narrowly ovate or ovate-elliptic shapes that are 2.7-3.6 cm in length and 0.7-1 cm in width （i/w ratio=3.4-4）. The apexes of the Fraxinus oishii samara are round or slightly emarginated, and a seed of the samara is always located at the base, of which the general shape is narrow rhombic-ellipsoidal. The seed is 1.2-2 cm long and 0.5-0.7 cm wide. Two specimens are different from the samara of Fraxinus oishii. They have a 6.6 length/width ratio （3.3 cm long and 0.5 cm wide）, and thus, are temporarily classified into the Fraxinus sp. One specimen was recognized as a winged seed of Liriodendron meisenense. The wing is broadly lanceolate to elliptic in shape, has a smooth, acute apex, and is approximately 3 cm long and 0.7 cm wide. Samaras of Fraxinus oishii and Liriodendron meisenense were early reported from the Middle Miocene deposits from North Korea, but these specimens are the first discovery in South Korea. Further study of the Duho Formation may connect flora relationships between North and South Korea.展开更多
Winged bean[Psophocarpus tetragonolobus(L.)DC.]is a vegetable legume crop.The center of origin,diversity and domestication of this crop are not known.In this study,we assessed the genetic diversity and population stru...Winged bean[Psophocarpus tetragonolobus(L.)DC.]is a vegetable legume crop.The center of origin,diversity and domestication of this crop are not known.In this study,we assessed the genetic diversity and population structure of 457 accessions of winged bean collected from six geographical regions(North,Northeast,East,West,and central,and South)in Thailand using 14 simple sequence repeat(SSR)markers.In total,the SSR markers detected only 55 alleles with an average of 3.9 alleles per locus.Observed heterozygosity was relatively high(0.15)and overall gene diversity was moderate(0.487).Gene diversity,allelic richness and observed heterozygosity in the six regions were comparable,while the estimated out-crossing rate was relatively high(16.4%).STRUCTURE analysis grouped the 457 winged bean accessions into three subpopulations.Neighbor-joining(NJ)analysis grouped all the accessions into two major clusters.Genetic groups identified by both STRUCTURE analysis and NJ analysis were unrelated to geographical origins.Principal coordinate analysis revealed no clear clustering of the winged bean accessions.Although genetic groups were not unrelated to geographical origins,most of the winged bean accessions with long pods(30 cm or higher in length)or having purple seed coats or purple young pods were grouped together.This suggested that the winged beans with long pods or with purple seed or purple young pods may have a single origin.Altogether,these results demonstrated that the genetic diversity of winged bean in Thailand was moderate with high genetic admixture.We argue that the high genetic admixture of the winged bean in Thailand is due to seed migration and relatively high outcrossing rate.展开更多
Brandisia hancei(Paulowniaceae)is a widely distributed shrub in karst regions in southwestern China.Its seeds have a membranous wing,and they mature just before the rainy season begins.To assess the effect of the wing...Brandisia hancei(Paulowniaceae)is a widely distributed shrub in karst regions in southwestern China.Its seeds have a membranous wing,and they mature just before the rainy season begins.To assess the effect of the wing on seed dispersal and germination of B.hancei,we measured the dispersal distance at varying wind speeds and release heights,falling duration from different release heights,floating duration on still water,rates of imbibition of water,and drying and soil adherence to seeds.Germination experiments were conducted on intact and de-winged seeds immediately after harvest.The wing increased the falling duration in still air and the floating ability on water.Dispersal distance of winged and de-winged seeds did not differ at a wind speed of 2.8 m s1,but at 3.6 and 4.0 m s1 dispersal distances were greater for de-winged than for winged seeds.Seed wing had little effect of absorption and retention of water,but significantly increased soil adherence to the seeds.Mature seeds were non-dormant and germinated to over 90%with a mean germination time of about 10 days.By combining the environmental conditions in karst habitat with the seed traits of B.hancei,we conclude that dispersal and germination of winged seeds are adapted to the precipitation seasonality in heterogeneous habitats absence of soil.展开更多
We analyze morphometrics from a sample of 276 White-winged Black Tern(Chlidonias leucopterus) caught in north-west Australia on 4 March 2011. An estimated 40000 terns were present — the largest concentration of this ...We analyze morphometrics from a sample of 276 White-winged Black Tern(Chlidonias leucopterus) caught in north-west Australia on 4 March 2011. An estimated 40000 terns were present — the largest concentration of this species yet reported from Australia. When comparing juveniles with adults, only wing length and body mass differed significantly; however, juveniles were still easily recognized by plumage and wing molt as late as March. There was little evidence of any dramatic weight gain in adults before their northward migration. No morphological characteristic distinguishing sex was found. We confirmed that terns caught in this study did not appear to differ morphologically from those of the western palearctic populations. We describe wing molt based on data from 354 individuals captured and banded in Australia over 28 years. Wing molt proceeds in much the same way as found in other small terns.展开更多
Ethnic people living on the Tibetan Plateau during the Tubo period have been well-known as not only strong and brave on horses,but they were also an ethnic group enriched with powerful creativity and rich imagination....Ethnic people living on the Tibetan Plateau during the Tubo period have been well-known as not only strong and brave on horses,but they were also an ethnic group enriched with powerful creativity and rich imagination.From Tubo’s cultural art,we can observe a large amount of extremely fine artifacts.For instance,among展开更多
In December 2021, the Datong Archaeological Research Institute conducted an excavation of the Lv Xu’s tomb in Zhijiabao Village, Pingcheng District, Datong. The Lv Xu’s tomb is a newly excavated tomb of the Pingchen...In December 2021, the Datong Archaeological Research Institute conducted an excavation of the Lv Xu’s tomb in Zhijiabao Village, Pingcheng District, Datong. The Lv Xu’s tomb is a newly excavated tomb of the Pingcheng period of Northern Wei Dynasty, which contains a rare painted shallow relief stone coffin. On the northern side of the coffin, there is a picture of ascending owner flanked by an ox-headed bird with wings and a mouse-headed bird with wings on each side. There are also images of azure dragon, white tiger and vermilion bird in the lower part of the east, west and north walls respectively. The identity information and the roles these images played in the tomb are not to be clarified yet. This paper aims to use iconographic methods to interpret the painted shallow relief carvings of winged divine beasts on the stone coffin, to identify their characteristics, schematic sources, and cultural attributes, and to provide some foundational work for further research on the stone coffin of the Lv Xu’s tomb.展开更多
In this paper,we present the development of our latest flapping-wing micro air vehicle(FW-MAV),named Explobird,which features two wings with a wingspan of 195 mm and weighs a mere 25.2 g,enabling it to accomplish vert...In this paper,we present the development of our latest flapping-wing micro air vehicle(FW-MAV),named Explobird,which features two wings with a wingspan of 195 mm and weighs a mere 25.2 g,enabling it to accomplish vertical take-off and hover flight.We devised a novel gear-based mechanism for the flapping system to achieve high lift capability and reliability and conducted extensive testing and analysis on the wings to optimise power matching and lift performance.The Explobird can deliver a peak lift-to-weight ratio of 1.472 and an endurance time of 259 s during hover flight powered by a single-cell LiPo battery.Considering the inherent instability of the prototype,we discuss the derivatives of its longitudinal system,underscoring the importance of feedback control,position of the centre of gravity,and increased damping.To demonstrate the effect of damping enhancement on stability,we also designed a passive stable FW-MAV.Currently,the vehicle is actively stabilised in roll by adjusting the wing root bars and in pitch through high-authority tail control,whereas yaw is passively stabilised.Through a series of flight tests,we successfully demonstrate that our prototype can perform vertical take-off and hover flight under wireless conditions.These promising results position the Explobird as a robust vehicle with high lift capability,paving the way towards the use of FW-MAVs for carrying load equipment in multiple tasks.展开更多
Understanding soil disturbance behaviors under the impact of the winged subsoiler is critical for designing or optimizing the winged subsoiler(a primary subsoiling tool).In this study,a soil-winged subsoiler interacti...Understanding soil disturbance behaviors under the impact of the winged subsoiler is critical for designing or optimizing the winged subsoiler(a primary subsoiling tool).In this study,a soil-winged subsoiler interaction model was developed and the effects of winged subsoiler on soil disturbance behaviors were investigated using the discrete element method(DEM)simulations and lab soil-bin tests.The results showed that wings mainly affected the disturbance range and fragmentation degree of soil above them.The draught forces of share section(SS),arc section in the hardpan(ASHP),arc section in the top layer(ASTL)and line section(LS)were accounted for 69.53%,25.22%,4.73%and 0.52%of the total draught force of winged subsoiler;the lateral disturbance range from high to low of the soil at different depths followed the ranking:top layer(TL),hardpan disturbed by arc section(HDAS)and hardpan disturbed by share section(HDSS).Wings had the greatest influence on the draught force of ASHP.Adding wings to an arc-shaped subsoiler increased the disturbance areas of HDAS,TL and HDSS by 47.52%,7.74%and 4.59%,respectively,but meanwhile increased the total draught force by 36%.Compared with a non-winged subsoiler,winged subsoiler had higher soil looseness(15.83%),soil disturbance coefficient(58.59%),furrow width(448.65 mm)and soil disturbance area ratio(0.3835),but poorer soil surface flatness(19.79 mm)and lower soil loosening efficiency(39.35 mm²/N).This study provided critical information for optimizing winged subsoilers on aspects of improving soil loosening effectiveness and reducing draught force.展开更多
The core components of an aircraft and the source of its lift are its wings,but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired.Here,to inv...The core components of an aircraft and the source of its lift are its wings,but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired.Here,to investigate how this process influences the aerodynamic parameters of aircraft wings,the k-ωshearstress-transport turbulence model and the nested dynamic grid technique are used to analyze numerically the transient process of the muzzle jet of a 30-mm small-caliber aircraft gun in highaltitude(10 km)flight with an incoming Mach number of Ma=0.8.For comparison,two other models are established,one with no projectile and the other with no wing.The results indicate that when the aircraft gun is fired,the muzzle jet acts on the wing,creating a pressure field thereon.The uneven distribution of high pressure greatly reduces the lift of the aircraft,causing oscillations in its drag and disrupting its dynamic balance,thereby affecting its flight speed and attitude.Meanwhile,the muzzle jet is obstructed by the wing,and its flow field is distorted and deformed,developing upward toward the wing.Because of the influence of the incoming flow,the shockwave front of the projectile changes from a smooth spherical shape to an irregular one,and the motion parameters of the projectile are also greatly affected by oscillations.The present results provide an important theoretical basis for how the guns of fighter aircraft influence the aerodynamic performance of the wings.展开更多
Wing design is a critical factor in the aerodynamic performance of flapping-wing(FW)robots.Inspired by the natural wing structures of insects,bats,and birds,we explored how bio-mimetic wing vein morphologies,combined ...Wing design is a critical factor in the aerodynamic performance of flapping-wing(FW)robots.Inspired by the natural wing structures of insects,bats,and birds,we explored how bio-mimetic wing vein morphologies,combined with a bio-inspired double wing clap-and-fling mechanism,affect thrust generation.This study focused on increasing vertical force and payload capacity.Through systematic experimentation with various vein configurations and structural designs,we developed innovative wings optimized for thrust production.Comprehensive tests were conducted to measure aerodynamic forces,power consumption,and wing kinematics across a range of flapping frequencies.Additionally,wings with different aspect ratios,a key factor in wing design,were fabricated and extensively evaluated.The study also examined the role of bio-inspired vein layouts on wing flexibility,a critical component in improving flight efficiency.Our findings demonstrate that the newly developed wing design led to a 20%increase in thrust,achieving up to 30 g-force(gf).This research sheds light on the clap-and-fling effect and establishes a promising framework for bio-inspired wing design,offering significant improvements in both performance and payload capacity for FW robots.展开更多
Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or ...Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or attitude instability,seriously compromising mission reliability.To address this engineering challenge,this paper proposes a multi-point low-impact locking/release mechanism based on the mobility model and energy conversion strategy.Through establishing a DOF constraint framework system,this paper systematically analyzes the energy transfer and conversion characteristics during the wing separation process,reveals the generation mechanism of impact loads,and conducts research on low-impact design based on energy conversion strategy.Building on this foundation,a single-point locking/release mechanism employing parallel trapezoidal key shaft structure was designed,which increases frictional contact time and reduces the energy release rate,thereby achieving low-impact characteristics.The mechanism's performance was validated through physical prototype development and systematic functional testing(including unlocking force,synchronization,and impact tests).Experimental results demonstrate:(1)Under 14 kN preload condition,the maximum unlocking force was only 92.54 N,showing a linear relationship with preload that satisfies the"strong-connection/weak-unlock"design requirement;(2)Wing separation was completed within 46 ms,with synchronization time difference among three separation mechanisms stably controlled within 12-14 ms,proving rapid and reliable operation;(3)The unlocking impact acceleration ranged between 26 and 73 g,below the 100 g design limit,confirming the effectiveness of the energy conversion strategy.The proposed low-impact locking/release mechanism design method based on energy conversion strategy resolves the traditional challenges of high impact and synchronization deficiencies.The synergistic optimization mechanism of"structural load reduction and performance improvement"provides a highly reliable technical solution for wing separable mechanisms while offering novel design insights for wing connection/separation systems engineering.展开更多
[Objectives]To explore the effect of selenium(Se)on inhibiting embryo abortion and enhancing seedling cultivation quality of Red sandalwood(Pterocarpus santalinus).[Methods]Based on prior cultivation practices and exp...[Objectives]To explore the effect of selenium(Se)on inhibiting embryo abortion and enhancing seedling cultivation quality of Red sandalwood(Pterocarpus santalinus).[Methods]Based on prior cultivation practices and experimental research,three categories comprising 13 forest soil nutrient management schemes were designed to investigate the synergistic effects of Se,NPK compound fertilizers,and enzyme-microbe fermented organic fertilizers(EFOF)on embryo abortion,winged pod development,and seedling quality of Red sandalwood.[Results]Increasing the Se content in the soil,particularly in the form of selenite/Se(IV),within one month following the harvest of Red sandalwood pods and within two months prior to flower withering,significantly reduced embryo abortion percentage(EAP),and consequently improved seed quality and yield per plant.The effect of Se application was markedly greater than that of the single application of nitrogen(N),phosphorus(P),potassium(K),boron(B)fertilizers,or organic fertilizers.Furthermore,when Se was applied in combination with NPK compound fertilizers and EFOF,these beneficial effects were significantly enhanced.When Se(IV)was applied individually,the EAP decreased by 62.4%,reaching 24.8% at 8 weeks after flower withering(compared to 65.9%in the unmanaged control,UMC).Following winged pod maturation,the percentage of empty winged pods(PEWP)declined by 65.2% to 16.8%(UMC:48.2%),the average individual winged pod weight(IWPW)increased by 69.1%to 0.690 g per fruit(UMC:0.408 g),and the winged pod yield(WPY)rose by 214.8% to 4.03 kg(UMC:1.28 kg).Additionally,the blasted seed percentage(BSP)was reduced by 51.2% to 29.9%(UMC:61.3%),and the 100-seed weight(HSW)increased by 96.0%to 8.37 g(UMC:4.27 g).Following sowing in the nursery,the seedling emergence rate(SER)increased by 6.57-fold,reaching 59.8%(UMC:7.9%).Additionally,the whole plant biomass of 6-month-old seedlings increased by 52.9%,attaining 1.56 g(UMC:1.02 g).The combined application of EFOF+NPK+Se(IV)significantly reduced the EAP,PEWP,and BSP by 56.5%,46.0%,and 56.3%,respectively,compared to the single application of Se(IV).Furthermore,these percentages decreased by 79.7%,78.9%,and 71.8%,respectively,relative to the single application of NPK compound fertilizers,and by 79.0%,74.5%,and 72.1%,respectively,compared to the single application of EFOF.Additionally,the SER increased by 34.6%,141.0%,and 287.0%,respectively,when compared to the single application of Se(IV),NPK compound fertilizers,and EFOF.[Conclusions]Enhancing the nutrient status of forest soils,particularly the concentration of Se(IV),constitutes a critical technical approach to improving the resistance of Red sandalwood to low-temperature stress during its flowering and fruiting stages,thereby preventing embryo abortion.展开更多
Some of the most interesting areas in aerospace science and technologies are on either higher,faster,and larger systems or lower,slower,and smaller flying capabilities.In this paper,we present our perspectives on the ...Some of the most interesting areas in aerospace science and technologies are on either higher,faster,and larger systems or lower,slower,and smaller flying capabilities.In this paper,we present our perspectives on the aerodynamics related to small,fixed-wing as well as flapping-wing flight vehicles.From an evolutionary viewpoint,flyers have gone through many iterations,adaptations,and optimizations to balance their biological functions,including flight.In the low-Reynolds-number regime,the aerodynamic characteristics around a solid object differ from those observed at the scale of passenger-airplanes.Consequently,the optimal airfoil and wing shapes vary with vehicle size.As vehicle dimensions vary,non-proportional scaling between surface areas and weight shifts the dominance of physical mechanisms,leading to distinct operational parameters and technical requirements.With smaller flight vehicles,structural flexibility as well as anisotropic material properties become more pronounced,which causes qualitative changes in aerodynamics.The flapping motion of the wings,the interactions between wings,the synergistic characteristics of wing and tail,and the development of soft structures for better agility and flight performance are discussed.Low-Reynolds-number aerodynamics require collaborative innovation to optimize shape,motion,and structure of vehicles in accordance with the scaling laws.Together,progress on these fronts is reshaping the design paradigm of air vehicles and other types of robots with shrinking physical dimensions and more versatile capabilities to meet wider ranges of missions.展开更多
The optimization of wings typically relies on computationally intensive high-fidelity simulations,which restrict the quick exploration of design spaces.To address this problem,this paper introduces a methodology dedic...The optimization of wings typically relies on computationally intensive high-fidelity simulations,which restrict the quick exploration of design spaces.To address this problem,this paper introduces a methodology dedicated to optimizing box wing configurations using low-fidelity data driven machine learning approach.This technique showcases its practicality through the utilization of a tailored low-fidelity machine learning technique,specifically designed for early-stage wing configuration.By employing surrogate model trained on small dataset derived from low-fidelity simulations,our method aims to predict outputs within an acceptable range.This strategy significantly mitigates computational costs and expedites the design exploration process.The methodology's validation relies on its successful application in optimizing the box wing of PARSIFAL,serving as a benchmark,while the primary focus remains on optimizing the newly designed box wing by Bionica.Applying this method to the Bionica configuration led to a notable 14%improvement in overall aerodynamic effciency.Furthermore,all the optimized results obtained from machine learning model undergo rigorous assessments through the high-fidelity RANS analysis for confirmation.This methodology introduces innovative approach that aims to streamline computational processes,potentially reducing the time and resources required compared to traditional optimization methods.展开更多
基金funded by the“Departments of Excellence”program of the Italian Ministry for University and Research(MIUR,2018-2022 and MUR,2023-2027).
文摘The ability of queens and males of most ant species to disperse by flight has fundamentally contributed to the group’s evolutionary and ecological success and is a determining factor to take into account for biogeographic studies(Wagner and Liebherr 1992;Peeters and Ito 2001;Helms 2018).
基金supported by the National Natural Science Foundation of China(No.12104047)。
文摘The rocket sled system is not only a high-speed dynamic ground test system,but also one of the future aerospace horizontal launch schemes.The winged load,as a common type of payload,has greater vibration and noise intensity than the wingless load.Due to the severe aerodynamic instability prior to separation,the head-up or head-down phenomena are more evident and the test accuracy significantly decreases.The high-precision computer fluid dynamics and aeroacoustic analysis are employed to explore the multifield coupling mechanism of a rocket sled with the winged payload in the wide speed range(Ma=0.5–2).The results show that as the incoming velocity increases,the cone angle of the shock wave of the rocket sled decreases,the shock pressure increases quickly,and the vortex between the slippers splits and gradually shrinks in size.The velocity of the rocket sled exerts little influence on the modal resonance frequency.The wing has a significant impact on aerodynamic noise,and as the sound pressure level rises,the propagation direction gradually shifts towards the rear and upper regions of the wing.
文摘Synthetic analysis is conducted to the wind tunnel experiment results of zero lift drag coefficient and lift coefficient for large aspect ratio winged rigid body.By means of wind tunnel experiment data,the dynamics model of the zero lift drag coefficient and lift coefficient for the large aspect ratio winged rigid body is amended.The research indicates that the change trends of zero lift drag coefficient and lift coefficient to Mach number are similar.The calculation result and wind tunnel experiment data all verify the validity of the amended dynamics model by which to estimate the zero lift drag coefficient and lift coefficient for the large aspect ratio winged rigid body,and thus providing some technical reference to aerodynamics character analysis of the same types of winged rigid body.
基金supported by BK21 project of Department of Geology,Kyungpook National University, KNU
文摘A total of 16 specimens of fossil-winged fruits were found from the Middle Miocene marine deposits, Duho Formation, Pohang Basin, Korea. They were identified into two structurally different groups： 15 specimens into a winged fruit of Fraxinus, and one specimen of Liriodendron. The most samaras （13 specimens） were identified as Fraxinus oishii, which is characterized by narrowly ovate or ovate-elliptic shapes that are 2.7-3.6 cm in length and 0.7-1 cm in width （i/w ratio=3.4-4）. The apexes of the Fraxinus oishii samara are round or slightly emarginated, and a seed of the samara is always located at the base, of which the general shape is narrow rhombic-ellipsoidal. The seed is 1.2-2 cm long and 0.5-0.7 cm wide. Two specimens are different from the samara of Fraxinus oishii. They have a 6.6 length/width ratio （3.3 cm long and 0.5 cm wide）, and thus, are temporarily classified into the Fraxinus sp. One specimen was recognized as a winged seed of Liriodendron meisenense. The wing is broadly lanceolate to elliptic in shape, has a smooth, acute apex, and is approximately 3 cm long and 0.7 cm wide. Samaras of Fraxinus oishii and Liriodendron meisenense were early reported from the Middle Miocene deposits from North Korea, but these specimens are the first discovery in South Korea. Further study of the Duho Formation may connect flora relationships between North and South Korea.
基金supported by Kasetsart University Research and Development Institute,Kasetsart University,Thailandfunded by the Thailand Research Fund through the Senior Research Scholar Project(Grant No.RTA6180002)。
文摘Winged bean[Psophocarpus tetragonolobus(L.)DC.]is a vegetable legume crop.The center of origin,diversity and domestication of this crop are not known.In this study,we assessed the genetic diversity and population structure of 457 accessions of winged bean collected from six geographical regions(North,Northeast,East,West,and central,and South)in Thailand using 14 simple sequence repeat(SSR)markers.In total,the SSR markers detected only 55 alleles with an average of 3.9 alleles per locus.Observed heterozygosity was relatively high(0.15)and overall gene diversity was moderate(0.487).Gene diversity,allelic richness and observed heterozygosity in the six regions were comparable,while the estimated out-crossing rate was relatively high(16.4%).STRUCTURE analysis grouped the 457 winged bean accessions into three subpopulations.Neighbor-joining(NJ)analysis grouped all the accessions into two major clusters.Genetic groups identified by both STRUCTURE analysis and NJ analysis were unrelated to geographical origins.Principal coordinate analysis revealed no clear clustering of the winged bean accessions.Although genetic groups were not unrelated to geographical origins,most of the winged bean accessions with long pods(30 cm or higher in length)or having purple seed coats or purple young pods were grouped together.This suggested that the winged beans with long pods or with purple seed or purple young pods may have a single origin.Altogether,these results demonstrated that the genetic diversity of winged bean in Thailand was moderate with high genetic admixture.We argue that the high genetic admixture of the winged bean in Thailand is due to seed migration and relatively high outcrossing rate.
基金This research was funded by the National Natural Science Foundation of China to Xiaoling Tian(No.31901237)it was supported by the Young Academic and Technical Leader Raising Foundation of Yunnan Province to Yongpeng Ma(No.2018HB066).
文摘Brandisia hancei(Paulowniaceae)is a widely distributed shrub in karst regions in southwestern China.Its seeds have a membranous wing,and they mature just before the rainy season begins.To assess the effect of the wing on seed dispersal and germination of B.hancei,we measured the dispersal distance at varying wind speeds and release heights,falling duration from different release heights,floating duration on still water,rates of imbibition of water,and drying and soil adherence to seeds.Germination experiments were conducted on intact and de-winged seeds immediately after harvest.The wing increased the falling duration in still air and the floating ability on water.Dispersal distance of winged and de-winged seeds did not differ at a wind speed of 2.8 m s1,but at 3.6 and 4.0 m s1 dispersal distances were greater for de-winged than for winged seeds.Seed wing had little effect of absorption and retention of water,but significantly increased soil adherence to the seeds.Mature seeds were non-dormant and germinated to over 90%with a mean germination time of about 10 days.By combining the environmental conditions in karst habitat with the seed traits of B.hancei,we conclude that dispersal and germination of winged seeds are adapted to the precipitation seasonality in heterogeneous habitats absence of soil.
文摘We analyze morphometrics from a sample of 276 White-winged Black Tern(Chlidonias leucopterus) caught in north-west Australia on 4 March 2011. An estimated 40000 terns were present — the largest concentration of this species yet reported from Australia. When comparing juveniles with adults, only wing length and body mass differed significantly; however, juveniles were still easily recognized by plumage and wing molt as late as March. There was little evidence of any dramatic weight gain in adults before their northward migration. No morphological characteristic distinguishing sex was found. We confirmed that terns caught in this study did not appear to differ morphologically from those of the western palearctic populations. We describe wing molt based on data from 354 individuals captured and banded in Australia over 28 years. Wing molt proceeds in much the same way as found in other small terns.
文摘Ethnic people living on the Tibetan Plateau during the Tubo period have been well-known as not only strong and brave on horses,but they were also an ethnic group enriched with powerful creativity and rich imagination.From Tubo’s cultural art,we can observe a large amount of extremely fine artifacts.For instance,among
文摘In December 2021, the Datong Archaeological Research Institute conducted an excavation of the Lv Xu’s tomb in Zhijiabao Village, Pingcheng District, Datong. The Lv Xu’s tomb is a newly excavated tomb of the Pingcheng period of Northern Wei Dynasty, which contains a rare painted shallow relief stone coffin. On the northern side of the coffin, there is a picture of ascending owner flanked by an ox-headed bird with wings and a mouse-headed bird with wings on each side. There are also images of azure dragon, white tiger and vermilion bird in the lower part of the east, west and north walls respectively. The identity information and the roles these images played in the tomb are not to be clarified yet. This paper aims to use iconographic methods to interpret the painted shallow relief carvings of winged divine beasts on the stone coffin, to identify their characteristics, schematic sources, and cultural attributes, and to provide some foundational work for further research on the stone coffin of the Lv Xu’s tomb.
基金supported by the National Natural Science Foundation of China under Grant No.51975023&52322501supported in part by the National Natural Science Foundation of China under Grant No.U22B2040.
文摘In this paper,we present the development of our latest flapping-wing micro air vehicle(FW-MAV),named Explobird,which features two wings with a wingspan of 195 mm and weighs a mere 25.2 g,enabling it to accomplish vertical take-off and hover flight.We devised a novel gear-based mechanism for the flapping system to achieve high lift capability and reliability and conducted extensive testing and analysis on the wings to optimise power matching and lift performance.The Explobird can deliver a peak lift-to-weight ratio of 1.472 and an endurance time of 259 s during hover flight powered by a single-cell LiPo battery.Considering the inherent instability of the prototype,we discuss the derivatives of its longitudinal system,underscoring the importance of feedback control,position of the centre of gravity,and increased damping.To demonstrate the effect of damping enhancement on stability,we also designed a passive stable FW-MAV.Currently,the vehicle is actively stabilised in roll by adjusting the wing root bars and in pitch through high-authority tail control,whereas yaw is passively stabilised.Through a series of flight tests,we successfully demonstrate that our prototype can perform vertical take-off and hover flight under wireless conditions.These promising results position the Explobird as a robust vehicle with high lift capability,paving the way towards the use of FW-MAVs for carrying load equipment in multiple tasks.
基金The authors gratefully acknowledge the financial assistance received from the National Key Research and Development Program of China(Grant No.2016YFD0200601,2016YFD020060101)and the Key Industry Chain Innovation Project of Shaanxi Province(Grant No.2018ZDCXL-NY-03-06).
文摘Understanding soil disturbance behaviors under the impact of the winged subsoiler is critical for designing or optimizing the winged subsoiler(a primary subsoiling tool).In this study,a soil-winged subsoiler interaction model was developed and the effects of winged subsoiler on soil disturbance behaviors were investigated using the discrete element method(DEM)simulations and lab soil-bin tests.The results showed that wings mainly affected the disturbance range and fragmentation degree of soil above them.The draught forces of share section(SS),arc section in the hardpan(ASHP),arc section in the top layer(ASTL)and line section(LS)were accounted for 69.53%,25.22%,4.73%and 0.52%of the total draught force of winged subsoiler;the lateral disturbance range from high to low of the soil at different depths followed the ranking:top layer(TL),hardpan disturbed by arc section(HDAS)and hardpan disturbed by share section(HDSS).Wings had the greatest influence on the draught force of ASHP.Adding wings to an arc-shaped subsoiler increased the disturbance areas of HDAS,TL and HDSS by 47.52%,7.74%and 4.59%,respectively,but meanwhile increased the total draught force by 36%.Compared with a non-winged subsoiler,winged subsoiler had higher soil looseness(15.83%),soil disturbance coefficient(58.59%),furrow width(448.65 mm)and soil disturbance area ratio(0.3835),but poorer soil surface flatness(19.79 mm)and lower soil loosening efficiency(39.35 mm²/N).This study provided critical information for optimizing winged subsoilers on aspects of improving soil loosening effectiveness and reducing draught force.
基金supported by the National Natural Science Foundation of China(Grant No.12402268)the Fundamental Research Funds for the Central Universities(Grant No.30925010410)。
文摘The core components of an aircraft and the source of its lift are its wings,but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired.Here,to investigate how this process influences the aerodynamic parameters of aircraft wings,the k-ωshearstress-transport turbulence model and the nested dynamic grid technique are used to analyze numerically the transient process of the muzzle jet of a 30-mm small-caliber aircraft gun in highaltitude(10 km)flight with an incoming Mach number of Ma=0.8.For comparison,two other models are established,one with no projectile and the other with no wing.The results indicate that when the aircraft gun is fired,the muzzle jet acts on the wing,creating a pressure field thereon.The uneven distribution of high pressure greatly reduces the lift of the aircraft,causing oscillations in its drag and disrupting its dynamic balance,thereby affecting its flight speed and attitude.Meanwhile,the muzzle jet is obstructed by the wing,and its flow field is distorted and deformed,developing upward toward the wing.Because of the influence of the incoming flow,the shockwave front of the projectile changes from a smooth spherical shape to an irregular one,and the motion parameters of the projectile are also greatly affected by oscillations.The present results provide an important theoretical basis for how the guns of fighter aircraft influence the aerodynamic performance of the wings.
基金Nguyen Tat Thanh University,Ho Chi Minh City,Vietnam for supporting this study。
文摘Wing design is a critical factor in the aerodynamic performance of flapping-wing(FW)robots.Inspired by the natural wing structures of insects,bats,and birds,we explored how bio-mimetic wing vein morphologies,combined with a bio-inspired double wing clap-and-fling mechanism,affect thrust generation.This study focused on increasing vertical force and payload capacity.Through systematic experimentation with various vein configurations and structural designs,we developed innovative wings optimized for thrust production.Comprehensive tests were conducted to measure aerodynamic forces,power consumption,and wing kinematics across a range of flapping frequencies.Additionally,wings with different aspect ratios,a key factor in wing design,were fabricated and extensively evaluated.The study also examined the role of bio-inspired vein layouts on wing flexibility,a critical component in improving flight efficiency.Our findings demonstrate that the newly developed wing design led to a 20%increase in thrust,achieving up to 30 g-force(gf).This research sheds light on the clap-and-fling effect and establishes a promising framework for bio-inspired wing design,offering significant improvements in both performance and payload capacity for FW robots.
文摘Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or attitude instability,seriously compromising mission reliability.To address this engineering challenge,this paper proposes a multi-point low-impact locking/release mechanism based on the mobility model and energy conversion strategy.Through establishing a DOF constraint framework system,this paper systematically analyzes the energy transfer and conversion characteristics during the wing separation process,reveals the generation mechanism of impact loads,and conducts research on low-impact design based on energy conversion strategy.Building on this foundation,a single-point locking/release mechanism employing parallel trapezoidal key shaft structure was designed,which increases frictional contact time and reduces the energy release rate,thereby achieving low-impact characteristics.The mechanism's performance was validated through physical prototype development and systematic functional testing(including unlocking force,synchronization,and impact tests).Experimental results demonstrate:(1)Under 14 kN preload condition,the maximum unlocking force was only 92.54 N,showing a linear relationship with preload that satisfies the"strong-connection/weak-unlock"design requirement;(2)Wing separation was completed within 46 ms,with synchronization time difference among three separation mechanisms stably controlled within 12-14 ms,proving rapid and reliable operation;(3)The unlocking impact acceleration ranged between 26 and 73 g,below the 100 g design limit,confirming the effectiveness of the energy conversion strategy.The proposed low-impact locking/release mechanism design method based on energy conversion strategy resolves the traditional challenges of high impact and synchronization deficiencies.The synergistic optimization mechanism of"structural load reduction and performance improvement"provides a highly reliable technical solution for wing separable mechanisms while offering novel design insights for wing connection/separation systems engineering.
基金Supported by National Natural Science Foundation of China(31270674)Science and Technology Plan Project of Zhaoqing City(2019N012)National Undergraduate Science and Technology Innovation Training Program of China(202210580007).
文摘[Objectives]To explore the effect of selenium(Se)on inhibiting embryo abortion and enhancing seedling cultivation quality of Red sandalwood(Pterocarpus santalinus).[Methods]Based on prior cultivation practices and experimental research,three categories comprising 13 forest soil nutrient management schemes were designed to investigate the synergistic effects of Se,NPK compound fertilizers,and enzyme-microbe fermented organic fertilizers(EFOF)on embryo abortion,winged pod development,and seedling quality of Red sandalwood.[Results]Increasing the Se content in the soil,particularly in the form of selenite/Se(IV),within one month following the harvest of Red sandalwood pods and within two months prior to flower withering,significantly reduced embryo abortion percentage(EAP),and consequently improved seed quality and yield per plant.The effect of Se application was markedly greater than that of the single application of nitrogen(N),phosphorus(P),potassium(K),boron(B)fertilizers,or organic fertilizers.Furthermore,when Se was applied in combination with NPK compound fertilizers and EFOF,these beneficial effects were significantly enhanced.When Se(IV)was applied individually,the EAP decreased by 62.4%,reaching 24.8% at 8 weeks after flower withering(compared to 65.9%in the unmanaged control,UMC).Following winged pod maturation,the percentage of empty winged pods(PEWP)declined by 65.2% to 16.8%(UMC:48.2%),the average individual winged pod weight(IWPW)increased by 69.1%to 0.690 g per fruit(UMC:0.408 g),and the winged pod yield(WPY)rose by 214.8% to 4.03 kg(UMC:1.28 kg).Additionally,the blasted seed percentage(BSP)was reduced by 51.2% to 29.9%(UMC:61.3%),and the 100-seed weight(HSW)increased by 96.0%to 8.37 g(UMC:4.27 g).Following sowing in the nursery,the seedling emergence rate(SER)increased by 6.57-fold,reaching 59.8%(UMC:7.9%).Additionally,the whole plant biomass of 6-month-old seedlings increased by 52.9%,attaining 1.56 g(UMC:1.02 g).The combined application of EFOF+NPK+Se(IV)significantly reduced the EAP,PEWP,and BSP by 56.5%,46.0%,and 56.3%,respectively,compared to the single application of Se(IV).Furthermore,these percentages decreased by 79.7%,78.9%,and 71.8%,respectively,relative to the single application of NPK compound fertilizers,and by 79.0%,74.5%,and 72.1%,respectively,compared to the single application of EFOF.Additionally,the SER increased by 34.6%,141.0%,and 287.0%,respectively,when compared to the single application of Se(IV),NPK compound fertilizers,and EFOF.[Conclusions]Enhancing the nutrient status of forest soils,particularly the concentration of Se(IV),constitutes a critical technical approach to improving the resistance of Red sandalwood to low-temperature stress during its flowering and fruiting stages,thereby preventing embryo abortion.
基金supported by the Research Grants Council(RGC)of the Government of Hong Kong Special Administrative Region(HKSAR)with RGC/GRF Project(Grant Nos.16206321 and 14113824).
文摘Some of the most interesting areas in aerospace science and technologies are on either higher,faster,and larger systems or lower,slower,and smaller flying capabilities.In this paper,we present our perspectives on the aerodynamics related to small,fixed-wing as well as flapping-wing flight vehicles.From an evolutionary viewpoint,flyers have gone through many iterations,adaptations,and optimizations to balance their biological functions,including flight.In the low-Reynolds-number regime,the aerodynamic characteristics around a solid object differ from those observed at the scale of passenger-airplanes.Consequently,the optimal airfoil and wing shapes vary with vehicle size.As vehicle dimensions vary,non-proportional scaling between surface areas and weight shifts the dominance of physical mechanisms,leading to distinct operational parameters and technical requirements.With smaller flight vehicles,structural flexibility as well as anisotropic material properties become more pronounced,which causes qualitative changes in aerodynamics.The flapping motion of the wings,the interactions between wings,the synergistic characteristics of wing and tail,and the development of soft structures for better agility and flight performance are discussed.Low-Reynolds-number aerodynamics require collaborative innovation to optimize shape,motion,and structure of vehicles in accordance with the scaling laws.Together,progress on these fronts is reshaping the design paradigm of air vehicles and other types of robots with shrinking physical dimensions and more versatile capabilities to meet wider ranges of missions.
基金The funding for this publication was provided by Johannes Kepler University(JKU),Linz.Special thanks to Prof.Zongmin DENG from Beihang University for his invaluable guidance,insightful feedback,and constructive criticism,which greatly enhanced the quality of this manuscript.We extend our heartfelt gratitude to the PARSIFAL team for providing the supporting materials,which inspired this study.
文摘The optimization of wings typically relies on computationally intensive high-fidelity simulations,which restrict the quick exploration of design spaces.To address this problem,this paper introduces a methodology dedicated to optimizing box wing configurations using low-fidelity data driven machine learning approach.This technique showcases its practicality through the utilization of a tailored low-fidelity machine learning technique,specifically designed for early-stage wing configuration.By employing surrogate model trained on small dataset derived from low-fidelity simulations,our method aims to predict outputs within an acceptable range.This strategy significantly mitigates computational costs and expedites the design exploration process.The methodology's validation relies on its successful application in optimizing the box wing of PARSIFAL,serving as a benchmark,while the primary focus remains on optimizing the newly designed box wing by Bionica.Applying this method to the Bionica configuration led to a notable 14%improvement in overall aerodynamic effciency.Furthermore,all the optimized results obtained from machine learning model undergo rigorous assessments through the high-fidelity RANS analysis for confirmation.This methodology introduces innovative approach that aims to streamline computational processes,potentially reducing the time and resources required compared to traditional optimization methods.
