The presentation of clinical symptoms due to decompression during diving, varies significantly, as mainly minor disturbances for the gastrointestinal tract in particular have been reported. The following case debates ...The presentation of clinical symptoms due to decompression during diving, varies significantly, as mainly minor disturbances for the gastrointestinal tract in particular have been reported. The following case debates whether diving can cause severe symptoms from the gastrointestinal system. We describe a clinical case of ischemic colitis presented in a 27-year-old male, who manifested abdominal pain while in the process of scuba diving 20 meters undersea, followed by bloody diarrhoea as soon as he ascended to sea level. Taking into account his past medical history, the thorough, impeccable clinical and laboratory examinations and presence of no other factors predisposing to ischemia of the colon, we assume that a possible relationship between diving conditions and the pathogenesis of ischemic colitis may exist. This unusual case might represent a hematologic manifestation of decompression sickness, due to increased coagulability and/or transient air emboli, occurring during a routine scuba diving ascent to sea level.展开更多
With the development of society and the progress of technology,more and more ocean activities are carried out.It results in booming of deep-sea diving.The use of helium-oxygen mixture(as a kind of breathing gas)solves...With the development of society and the progress of technology,more and more ocean activities are carried out.It results in booming of deep-sea diving.The use of helium-oxygen mixture(as a kind of breathing gas)solves the physiological problems of divers in saturated diving,but it brings about the Heliumspeech voice communication problem,the drop of speech intelligibility.There is no doubt that the effective speech communication must be provided for supporting the life and work of divers in deep-sea.This paper describes the mechanism of forming heliumspeech,discusses the effects of pressure and helium environment on the speech spectrum,compares the pros and cons of the time-domain and frequency-domain unscrambling techniques,shows the challenges in heliumspeech communications.Finally,it briefly introduces the deep learning,and points out that deep learning/machine learning may be a perfectly unscrambling technique.展开更多
This paper concentrates on the cross-range resolution of Synthetic Aperture Radar(SAR) based on diving model.In comparison to the azimuth resolution,the cross-range resolution can manifest the two-dimensional resoluti...This paper concentrates on the cross-range resolution of Synthetic Aperture Radar(SAR) based on diving model.In comparison to the azimuth resolution,the cross-range resolution can manifest the two-dimensional resolution ability of the imaging sensor SAR correctly.The diving model of SAR is an extended model from the conventional stripmap model,and the cross-range resolution expression is deduced from the equivalent linear frequency modulation pulses' compression.This expression points out that only the cross-range velocity component of the horizontal velocity contributes to the cross-range resolution.Also the cross-range resolution expressions and the performance of the conventional stripmap operation,squint side-look operation and beam circular-scanning operation are discussed.The cross-range resolution expression based on diving model will provide more general and more accurate reference.展开更多
Background: The foraging and diving behavior of waterfowl are affected by a number of important factors. Hence, learning more about these major factors is of great concern in order to protect endangered species. In th...Background: The foraging and diving behavior of waterfowl are affected by a number of important factors. Hence, learning more about these major factors is of great concern in order to protect endangered species. In this study, we verified the effect of sex, temperature, time and flock size on the diving behavior of the Scaly-sided Merganser(Mergus squamatus).Methods: The study was conducted by means of focal animal sampling in the Wuyuan section of the Poyang Lake watershed in Jiangxi Province, China from December 2015 to March 2016. We used one-way ANOVA and LSD tests to investigate the differences among these factors. Pearson correlations were used to test the relation between pause duration and the previous or subsequent dive duration. The relations between these factors and dive/pause duration are illustrated using Spearman correlations.Results: Mean dive duration and mean time on the pause of males were significantly higher than those of females. With an increase in temperature, dive duration significantly increased. Along with the passage of time of year and daytime, dive duration significantly increased, while dive duration decreased significantly with the increase in flock size.Conclusions: Sex, temperature, time and flock size have an effect on the diving behavior of the wintering Scalysided Merganser. The difference of diving behavior between males and females is related to differences in body mass. The difference of diving behavior among various temperatures and time periods may be related to a low minimum rate of oxygen consumption, while the difference among various flock sizes may be caused by rising intraspecific competition.展开更多
-The chief purpose of the research was to understand the physiological function change regularity, performance and adaptability of the human body living and working under high pressure for prolonged time.In January 19...-The chief purpose of the research was to understand the physiological function change regularity, performance and adaptability of the human body living and working under high pressure for prolonged time.In January 1989, 4 naval divers entered the habital of NMRI's 500 msw saturation diving system after a series of adaptive diving training. The breathing mixture was helium-oxygen. After 55 h compression (including intermediate stages) the 350 msw depth was reached, where the divers lived and worked for 72 h 10 min. No sign of discomfort or significant HPNS was found in the 4 divers.The second and third day of the saturation exposure, the divers carried out 370 msw dry and wet chamber excursion diving 2 man-time each, the divers effectively carried out operational work under water, the total excursion time was 1 h each excursion dive.Saturation decompression started after 3-day storage exposure, the divers were gradually brought toward the surface 25 msw a day on the average by employing the linear steady rate of decompression. During decompression, no case of DCS occurred. Immediate post-dive medical check-ups shows that they were physically normal.More than 120 biomedical indices were monitored and measured on the divers at different period of the experiment. The organisms showed a good adaptability and certain operating capability, and both the compression and decompression profiles were proved to be satisfactory.The detailed experimental data obtained provided sound scientific basis for the practical application of future great depth open sea saturation diving.展开更多
Herein, we present the results of our experimental investigation of splashes formed by a frog diving into water from the ground or from a leaf and the accompanying sound generated by the impact of the frog on the wate...Herein, we present the results of our experimental investigation of splashes formed by a frog diving into water from the ground or from a leaf and the accompanying sound generated by the impact of the frog on the water. The experiments are performed by visualizing the flow with a high-speed camera. In addition, we used physical models comprising hydrophilic bodies made from hydrogel or acrylic resin to experimentally study how hydrophilicity affects the splash. In these experiments, we use the degree of swelling to define the hydrophilicity degree. The results show that different splashes are caused by the increase in water-film velocity upon an increase in hydrophilicity. For a body with strong hydrophilicity, at a relatively high film velocity, the water film forms when the body impacts the water surface separates from the body surface. In addition, an aircavity forms when the film separates from the body. We empirically examine the relation between the hydrophilicity degree and film velocity. The results indicate that increased hydrophilicity does not reduce the splash. Therefore, we conclude that reducing of the formation of water from the biomimetic point of view is related to the shape of body.展开更多
Based on our preceding studies on the aerodynamics of a falcoperegrinus in diving flight along a vertical dam it is known that even when the body shape of the bird is rather streamlined in V-shape some feathers tips m...Based on our preceding studies on the aerodynamics of a falcoperegrinus in diving flight along a vertical dam it is known that even when the body shape of the bird is rather streamlined in V-shape some feathers tips may elevate in certain regions of the body. These regions were identified in wind tunnel tests for typical diving flight conditions as regions of locally separated flow. A life-size model in V-shape of a falcoperegrinus with artificial feathers fixed along the body was studied in a wind tunnel to focus on the fluid-structure interaction of feathers located in this sector. The distal ends of the feathers show flow-induced vibrations at typical flight conditions which grow linear in amplitude with increasing angle of incidence until incipient separation. In light of the proven existence of vibration-sensitive mechanoreceptors in the follicles of secondary feathers in birds it is hypothesized that this linear amplitude response offers the bird to sense the angle of incidence during the diving flight using the vibration magnitude as sensory stimulus. Thus the bird in streamlined shape has still a good measure to control its attitude to be in the narrow window of safe angle of incidence. This might have implications also for other birds or technical applications of airfoil sensors regarding incipient separation detection.展开更多
The 300 msw Simulated Saturation Diving Chamber Complex was designed and built by ourselves. It was completed at the end of 1985. A 300 msw trimixed saturation diving experiment was successfully conducted in the compl...The 300 msw Simulated Saturation Diving Chamber Complex was designed and built by ourselves. It was completed at the end of 1985. A 300 msw trimixed saturation diving experiment was successfully conducted in the complex by Chinese Underwater Technology Institute(CUTI) from May 22 to June 12 of 1987. During the experiment, 4 divers habitated in the complex for 20 days, and they performed 16 person-time excursion dives and 8 other tests. The result of the experiment indicates that the complex is well designed, suitably configurated, wholly integrated and steadily run, as well as of low leakage. The main functions of the complex have approached to those of the same kind in the world. The complex can be used as a basic facility for serving the nation's saturation diving technology, underwater operation, personnel training, etc.展开更多
The bistratified lobula giant type 1(BLG1) neuron is an identified looming-sensitive neuron in crab's visual brain that demonstrates special sensitivity to diving targets, or descending approaching motions. In thi...The bistratified lobula giant type 1(BLG1) neuron is an identified looming-sensitive neuron in crab's visual brain that demonstrates special sensitivity to diving targets, or descending approaching motions. In this paper, a novel neural model is proposed to shape such unique selectivity through incorporating a bio-plausible feedforward contrast inhibition synapse and a radially extending spatial enhancement distribution. Herein the synaptic connections and neuronal functions of this model are placed within a framework for matching and describing underlying biological findings. The systematic and comparative experiments have validated the proposed computational model that reconciles with the characteristics of BLG1 neurons in crab.展开更多
In the mysterious depths of the ocean,robots glide between reefs and corals,avoid obstacles,navigate independently,and fulfil their tasks as if they had a vision that could penetrate the murkiness of the water.The Chi...In the mysterious depths of the ocean,robots glide between reefs and corals,avoid obstacles,navigate independently,and fulfil their tasks as if they had a vision that could penetrate the murkiness of the water.The Chinese company Chasing has developed a robot capable of diving to a depth of 350 metres.As an underwater photographer,lifeguard or swimming pool cleaner,it demonstrates the expertise the company has acquired over years of research and development work.展开更多
High-nickel ternary silicon-carbon lithium-ion batteries,which use silicon-carbon materials as anodes and high-nickel ternary materials as cathodes,have already been commercialized as power batteries.The increasing de...High-nickel ternary silicon-carbon lithium-ion batteries,which use silicon-carbon materials as anodes and high-nickel ternary materials as cathodes,have already been commercialized as power batteries.The increasing demand for high-energy density and rapid charging characteristics has heightened the urgency of improving their fast charging cycle performance while establishing degradation mechanisms.Based on a pouch battery design with an energy density of 285 Wh·kg^(-1),this work studied 3 Ah pouch batteries for fast charging cycles ranging from 0.5C to 3C.Non-destructive techniques,such as differential voltage,incremental capacity analysis,and electrochemical impedance spectroscopy,were employed to investigate the effects of charging rates on battery cycling performance and to establish the degradation mechanisms.The experimental results indicated that capacity diving was observed at all charging rates.However,at lower rates(0.5C-2C),more cycles were achieved,while at higher rates(2C-3C),the cycle life remained relatively stable.Computed tomography,electrochemical performance analysis,and physicochemical characterizations were obtained,using scanning electron microscopy with energy dispersive spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,and inductively coupled plasma optical emission spectrometry.The mechanisms of capacity decrease during 3C fast charging cycles were investigated.It is proposed that the primary causes of capacity diving during 3C fast charging are the degradation of SiOx,anode polarization,and the simultaneous dissolution of metal ions in the cathode which were deposited at the anode,resulting the continuous growth and remodeling of the SEI membrane at the anode,thereby promoting more serious side reactions.展开更多
Aim To present an adaptive missile control system adaped to the external disturbance and the mobility of target movement. Methods Model reference adaptive control (MRAC) was applied and modified in the light of the ...Aim To present an adaptive missile control system adaped to the external disturbance and the mobility of target movement. Methods Model reference adaptive control (MRAC) was applied and modified in the light of the traits of the anti tank missile. Results Simulation results demonstrated this control system satisfied the requirement of anti tank missile of dive overhead attack. Conclusion It is successful to use MRAC in missile control system design, the quality is better than that designed by classical control theory.展开更多
Underwater robot technology has shown impressive results in applications such as underwater resource detection.For underwater applications that require extremely high flexibility,robots cannot replace skills that requ...Underwater robot technology has shown impressive results in applications such as underwater resource detection.For underwater applications that require extremely high flexibility,robots cannot replace skills that require human dexterity yet,and thus humans are often required to directly perform most underwater operations.Wearable robots(exoskeletons)have shown outstanding results in enhancing human movement on land.They are expected to have great potential to enhance human underwater movement.The purpose of this survey is to analyze the state-of-the-art of underwater exoskeletons for human enhancement,and the applications focused on movement assistance while excluding underwater robotic devices that help to keep the temperature and pressure in the range that people can withstand.This work discusses the challenges of existing exoskeletons for human underwater movement assistance,which mainly includes human underwater motion intention perception,underwater exoskeleton modeling and human-cooperative control.Future research should focus on developing novel wearable robotic structures for underwater motion assistance,exploiting advanced sensors and fusion algorithms for human underwater motion intention perception,building up a dynamic model of underwater exoskeletons and exploring human-in-theloop control for them.展开更多
Composition and abundance of submerged marine litter at one selected site within a coral reef area along the Jordanian coast of the Gulf of Aqaba has been estimated. The litter was collected in a clean up voluntarily ...Composition and abundance of submerged marine litter at one selected site within a coral reef area along the Jordanian coast of the Gulf of Aqaba has been estimated. The litter was collected in a clean up voluntarily campaigns that took place in the period 19 September 2006. A total of 14613 items weighing 4112.2 kg were collected during the survey. Mean litter density in the individual sampling sites varied between about 1 and 6 items/m2 with an over all mean density of 2 items/m2. The mean weight of the collected items per sampling site varied between 0.06 and 1.81 kg/m2 with an overall mean of 0.85 kg/m2. Cans accounted for 41% of the collected items, plastic was the second most popular (38%) while glass litter was the third most abundant item (17%). By comparison, other items formed only 4% of the total items collected during the campaigns. Approximately 46% of the plastic litter consisted of fragments followed by bottles bags and containers (18%). Potential sources are pointed out and recommendations and actions to deal with the problem are suggested.展开更多
BACKGROUND: Human activity in wilderness areas has increased globally in recent decades, leading to increased risk of injury and illness. Wilderness medicine has developed in response to both need and interest.METHODS...BACKGROUND: Human activity in wilderness areas has increased globally in recent decades, leading to increased risk of injury and illness. Wilderness medicine has developed in response to both need and interest.METHODS: The field of wilderness medicine encompasses many areas of interest. Some focus on special circumstances(such as avalanches) while others have a broader scope(such as trauma care). Several core areas of key interest within wilderness medicine are discussed in this study.RESULTS: Wilderness medicine is characterized by remote and improvised care of patients with routine or exotic illnesses or trauma, limited resources and manpower, and delayed evacuation to definitive care. Wilderness medicine is developing rapidly and draws from the breadth of medical and surgical subspecialties as well as the technical fields of mountaineering, climbing, and diving. Research, epidemiology, and evidence-based guidelines are evolving. A hallmark of this field is injury prevention and risk mitigation. The range of topics encompasses high-altitude cerebral edema, decompression sickness, snake envenomation, lightning injury, extremity trauma, and gastroenteritis. Several professional societies, academic fellowships, and training organizations offer education and resources for laypeople and health care professionals.CONCLUSIONS: The future of wilderness medicine is unfolding on multiple fronts: education, research, training, technology, communications, and environment. Although wilderness medicine research is technically difficult to perform, it is essential to deepening our understanding of the contribution of specific techniques in achieving improvements in clinical outcomes.展开更多
The extent to which prey abundance influences both bottlenose dolphin foraging behavior and group size in the presence of human activities has not previously been studied.The primary aim of this study was to identify ...The extent to which prey abundance influences both bottlenose dolphin foraging behavior and group size in the presence of human activities has not previously been studied.The primary aim of this study was to identify and quantify how wild bottlenose dolphins respond,individually and as groups,to the relative abundance of prey around a fish farm.Detailed views of dolphins' behavior were obtained by focal following individual animals whilst simultaneously collecting surface and underwater behavioral data.A total of 2150 dive intervals were analyzed,corresponding to 342 focal samples,lasting over 34 hours.Bottlenose dolphins remained submerged for a mean duration of 46.4 seconds and a maximum of 249 seconds.This study provides the first quantified data on bottlenose dolphin diving behavior in a marine fin-fish farm area.This study's results indicate that within a fish farm area used intensively by bottlenose dolphins for feeding,dolphins did not modify dive duration.Additionally,underwater observations confirmed that dolphins find it easier to exploit a concentrated food source and it appears that hunting tactic and not group size plays an important role during feeding activities.Thus,bottlenose dolphins appear capable of modifying their hunting tactics according to the abundance of prey.When top predators display behavioral responses to activities not directed at them,the task of studying all possible effects of human activities can become even more challenging.展开更多
Aquatic and semi-aquatic mammals, while resting at the water surface or ashore, breathe with a low frequency （f） by comparison to terrestrial mammals of the same body size, the difference increasing the larger the s...Aquatic and semi-aquatic mammals, while resting at the water surface or ashore, breathe with a low frequency （f） by comparison to terrestrial mammals of the same body size, the difference increasing the larger the species. Among various interpretations, it was suggested that the low-f breathing is a consequence of the end-inspiratory breath-holding pattern adopted by aquatic mammals to favour buoyancy at the water surface, and evolved to be part of the genetic makeup. If this interpretation was correct it could be expected that, differently from f, the heart rate （HR, beats/min） of aquatic and semi-aquatic mammals at rest would not need to differ from that of terrestrial mammals and that their HR-fratio would be higher than in terrestrial species. Literature data for HR （beats/min） in mammals at rest were gathered for 56 terrestrial and 27 aquatic species. In aquatic mammals the allometric curve （HR=191 .M^18; M= body mass, kg） did not differ from that of terrestrial species （HR=212.M^-0.22） and their HR-fratio （on average 32±5） was much higher than in terrestrial species （5±1） （P〈0.0001）. The comparison of these HR allometric curves to those forfpreviously published indicated that the HR-fratio was body size-independent in terrestrial species while it increased significantly with M in aquatic species. The similarity in HR and differences in f between aquatic and terrestrial mammals agree with the possibility that the lowfof aquatic and semi-aquatic mammals may have evolved for a non-respiratory function, namely the regulation of buoyancy at the water surface [Current Zoology 61（4）： 569-577, 2015].展开更多
文摘The presentation of clinical symptoms due to decompression during diving, varies significantly, as mainly minor disturbances for the gastrointestinal tract in particular have been reported. The following case debates whether diving can cause severe symptoms from the gastrointestinal system. We describe a clinical case of ischemic colitis presented in a 27-year-old male, who manifested abdominal pain while in the process of scuba diving 20 meters undersea, followed by bloody diarrhoea as soon as he ascended to sea level. Taking into account his past medical history, the thorough, impeccable clinical and laboratory examinations and presence of no other factors predisposing to ischemia of the colon, we assume that a possible relationship between diving conditions and the pathogenesis of ischemic colitis may exist. This unusual case might represent a hematologic manifestation of decompression sickness, due to increased coagulability and/or transient air emboli, occurring during a routine scuba diving ascent to sea level.
基金supported by National Natural Science Foundation of China(No.61871241,No.61771263)Science and Technology Program of Nantong(No.JC2018129,No.JC2018127)Fund of Nantong University-Nantong Joint Research Center for Intelligent Information Technology(No.KFKT2016A01,No.KFKT2017A05)。
文摘With the development of society and the progress of technology,more and more ocean activities are carried out.It results in booming of deep-sea diving.The use of helium-oxygen mixture(as a kind of breathing gas)solves the physiological problems of divers in saturated diving,but it brings about the Heliumspeech voice communication problem,the drop of speech intelligibility.There is no doubt that the effective speech communication must be provided for supporting the life and work of divers in deep-sea.This paper describes the mechanism of forming heliumspeech,discusses the effects of pressure and helium environment on the speech spectrum,compares the pros and cons of the time-domain and frequency-domain unscrambling techniques,shows the challenges in heliumspeech communications.Finally,it briefly introduces the deep learning,and points out that deep learning/machine learning may be a perfectly unscrambling technique.
基金Supported by the Chinese Postdoctoral Science Foundation(No. 20080440300)the Fundamental Research Funds for the Central Universities
文摘This paper concentrates on the cross-range resolution of Synthetic Aperture Radar(SAR) based on diving model.In comparison to the azimuth resolution,the cross-range resolution can manifest the two-dimensional resolution ability of the imaging sensor SAR correctly.The diving model of SAR is an extended model from the conventional stripmap model,and the cross-range resolution expression is deduced from the equivalent linear frequency modulation pulses' compression.This expression points out that only the cross-range velocity component of the horizontal velocity contributes to the cross-range resolution.Also the cross-range resolution expressions and the performance of the conventional stripmap operation,squint side-look operation and beam circular-scanning operation are discussed.The cross-range resolution expression based on diving model will provide more general and more accurate reference.
基金supported by the National Natural Science Foundation of China(Grant No.31560597)
文摘Background: The foraging and diving behavior of waterfowl are affected by a number of important factors. Hence, learning more about these major factors is of great concern in order to protect endangered species. In this study, we verified the effect of sex, temperature, time and flock size on the diving behavior of the Scaly-sided Merganser(Mergus squamatus).Methods: The study was conducted by means of focal animal sampling in the Wuyuan section of the Poyang Lake watershed in Jiangxi Province, China from December 2015 to March 2016. We used one-way ANOVA and LSD tests to investigate the differences among these factors. Pearson correlations were used to test the relation between pause duration and the previous or subsequent dive duration. The relations between these factors and dive/pause duration are illustrated using Spearman correlations.Results: Mean dive duration and mean time on the pause of males were significantly higher than those of females. With an increase in temperature, dive duration significantly increased. Along with the passage of time of year and daytime, dive duration significantly increased, while dive duration decreased significantly with the increase in flock size.Conclusions: Sex, temperature, time and flock size have an effect on the diving behavior of the wintering Scalysided Merganser. The difference of diving behavior between males and females is related to differences in body mass. The difference of diving behavior among various temperatures and time periods may be related to a low minimum rate of oxygen consumption, while the difference among various flock sizes may be caused by rising intraspecific competition.
文摘-The chief purpose of the research was to understand the physiological function change regularity, performance and adaptability of the human body living and working under high pressure for prolonged time.In January 1989, 4 naval divers entered the habital of NMRI's 500 msw saturation diving system after a series of adaptive diving training. The breathing mixture was helium-oxygen. After 55 h compression (including intermediate stages) the 350 msw depth was reached, where the divers lived and worked for 72 h 10 min. No sign of discomfort or significant HPNS was found in the 4 divers.The second and third day of the saturation exposure, the divers carried out 370 msw dry and wet chamber excursion diving 2 man-time each, the divers effectively carried out operational work under water, the total excursion time was 1 h each excursion dive.Saturation decompression started after 3-day storage exposure, the divers were gradually brought toward the surface 25 msw a day on the average by employing the linear steady rate of decompression. During decompression, no case of DCS occurred. Immediate post-dive medical check-ups shows that they were physically normal.More than 120 biomedical indices were monitored and measured on the divers at different period of the experiment. The organisms showed a good adaptability and certain operating capability, and both the compression and decompression profiles were proved to be satisfactory.The detailed experimental data obtained provided sound scientific basis for the practical application of future great depth open sea saturation diving.
文摘Herein, we present the results of our experimental investigation of splashes formed by a frog diving into water from the ground or from a leaf and the accompanying sound generated by the impact of the frog on the water. The experiments are performed by visualizing the flow with a high-speed camera. In addition, we used physical models comprising hydrophilic bodies made from hydrogel or acrylic resin to experimentally study how hydrophilicity affects the splash. In these experiments, we use the degree of swelling to define the hydrophilicity degree. The results show that different splashes are caused by the increase in water-film velocity upon an increase in hydrophilicity. For a body with strong hydrophilicity, at a relatively high film velocity, the water film forms when the body impacts the water surface separates from the body surface. In addition, an aircavity forms when the film separates from the body. We empirically examine the relation between the hydrophilicity degree and film velocity. The results indicate that increased hydrophilicity does not reduce the splash. Therefore, we conclude that reducing of the formation of water from the biomimetic point of view is related to the shape of body.
文摘Based on our preceding studies on the aerodynamics of a falcoperegrinus in diving flight along a vertical dam it is known that even when the body shape of the bird is rather streamlined in V-shape some feathers tips may elevate in certain regions of the body. These regions were identified in wind tunnel tests for typical diving flight conditions as regions of locally separated flow. A life-size model in V-shape of a falcoperegrinus with artificial feathers fixed along the body was studied in a wind tunnel to focus on the fluid-structure interaction of feathers located in this sector. The distal ends of the feathers show flow-induced vibrations at typical flight conditions which grow linear in amplitude with increasing angle of incidence until incipient separation. In light of the proven existence of vibration-sensitive mechanoreceptors in the follicles of secondary feathers in birds it is hypothesized that this linear amplitude response offers the bird to sense the angle of incidence during the diving flight using the vibration magnitude as sensory stimulus. Thus the bird in streamlined shape has still a good measure to control its attitude to be in the narrow window of safe angle of incidence. This might have implications also for other birds or technical applications of airfoil sensors regarding incipient separation detection.
文摘The 300 msw Simulated Saturation Diving Chamber Complex was designed and built by ourselves. It was completed at the end of 1985. A 300 msw trimixed saturation diving experiment was successfully conducted in the complex by Chinese Underwater Technology Institute(CUTI) from May 22 to June 12 of 1987. During the experiment, 4 divers habitated in the complex for 20 days, and they performed 16 person-time excursion dives and 8 other tests. The result of the experiment indicates that the complex is well designed, suitably configurated, wholly integrated and steadily run, as well as of low leakage. The main functions of the complex have approached to those of the same kind in the world. The complex can be used as a basic facility for serving the nation's saturation diving technology, underwater operation, personnel training, etc.
基金supported by the National Natural Science Foundation of China (No.12031003)the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement (No.778062 ULTRACEPT)。
文摘The bistratified lobula giant type 1(BLG1) neuron is an identified looming-sensitive neuron in crab's visual brain that demonstrates special sensitivity to diving targets, or descending approaching motions. In this paper, a novel neural model is proposed to shape such unique selectivity through incorporating a bio-plausible feedforward contrast inhibition synapse and a radially extending spatial enhancement distribution. Herein the synaptic connections and neuronal functions of this model are placed within a framework for matching and describing underlying biological findings. The systematic and comparative experiments have validated the proposed computational model that reconciles with the characteristics of BLG1 neurons in crab.
文摘In the mysterious depths of the ocean,robots glide between reefs and corals,avoid obstacles,navigate independently,and fulfil their tasks as if they had a vision that could penetrate the murkiness of the water.The Chinese company Chasing has developed a robot capable of diving to a depth of 350 metres.As an underwater photographer,lifeguard or swimming pool cleaner,it demonstrates the expertise the company has acquired over years of research and development work.
基金supported by the New Energy Vehicle Power Battery Life Cycle Testing and Verification Public Service Platform Project(No.2022-235-224).
文摘High-nickel ternary silicon-carbon lithium-ion batteries,which use silicon-carbon materials as anodes and high-nickel ternary materials as cathodes,have already been commercialized as power batteries.The increasing demand for high-energy density and rapid charging characteristics has heightened the urgency of improving their fast charging cycle performance while establishing degradation mechanisms.Based on a pouch battery design with an energy density of 285 Wh·kg^(-1),this work studied 3 Ah pouch batteries for fast charging cycles ranging from 0.5C to 3C.Non-destructive techniques,such as differential voltage,incremental capacity analysis,and electrochemical impedance spectroscopy,were employed to investigate the effects of charging rates on battery cycling performance and to establish the degradation mechanisms.The experimental results indicated that capacity diving was observed at all charging rates.However,at lower rates(0.5C-2C),more cycles were achieved,while at higher rates(2C-3C),the cycle life remained relatively stable.Computed tomography,electrochemical performance analysis,and physicochemical characterizations were obtained,using scanning electron microscopy with energy dispersive spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,and inductively coupled plasma optical emission spectrometry.The mechanisms of capacity decrease during 3C fast charging cycles were investigated.It is proposed that the primary causes of capacity diving during 3C fast charging are the degradation of SiOx,anode polarization,and the simultaneous dissolution of metal ions in the cathode which were deposited at the anode,resulting the continuous growth and remodeling of the SEI membrane at the anode,thereby promoting more serious side reactions.
文摘Aim To present an adaptive missile control system adaped to the external disturbance and the mobility of target movement. Methods Model reference adaptive control (MRAC) was applied and modified in the light of the traits of the anti tank missile. Results Simulation results demonstrated this control system satisfied the requirement of anti tank missile of dive overhead attack. Conclusion It is successful to use MRAC in missile control system design, the quality is better than that designed by classical control theory.
基金supported in part by the National Key Research and Development Program of China(2021YFF0501600)the National Natural Science Foundation of China(U1913601)+6 种基金the Major Science and Technology Projects of Anhui Province(202103a05020004)the China Postdoctoral Science Foundation(2021M693079)the Fundamental Research Funds for the Central Universities(WK2100000020)the State Key Laboratory of Mechanical System and Vibration(MSV202219)the Ministry of Science and Higher Education of the Russian Federation as Part of World-Class Research Center Program:Advanced Digital Technologies(075-15-2020-903)the Open Research Project of the State Key Laboratory of Industrial Control Technology,Zhejiang UniversityChina(ICT2022B42)。
文摘Underwater robot technology has shown impressive results in applications such as underwater resource detection.For underwater applications that require extremely high flexibility,robots cannot replace skills that require human dexterity yet,and thus humans are often required to directly perform most underwater operations.Wearable robots(exoskeletons)have shown outstanding results in enhancing human movement on land.They are expected to have great potential to enhance human underwater movement.The purpose of this survey is to analyze the state-of-the-art of underwater exoskeletons for human enhancement,and the applications focused on movement assistance while excluding underwater robotic devices that help to keep the temperature and pressure in the range that people can withstand.This work discusses the challenges of existing exoskeletons for human underwater movement assistance,which mainly includes human underwater motion intention perception,underwater exoskeleton modeling and human-cooperative control.Future research should focus on developing novel wearable robotic structures for underwater motion assistance,exploiting advanced sensors and fusion algorithms for human underwater motion intention perception,building up a dynamic model of underwater exoskeletons and exploring human-in-theloop control for them.
文摘Composition and abundance of submerged marine litter at one selected site within a coral reef area along the Jordanian coast of the Gulf of Aqaba has been estimated. The litter was collected in a clean up voluntarily campaigns that took place in the period 19 September 2006. A total of 14613 items weighing 4112.2 kg were collected during the survey. Mean litter density in the individual sampling sites varied between about 1 and 6 items/m2 with an over all mean density of 2 items/m2. The mean weight of the collected items per sampling site varied between 0.06 and 1.81 kg/m2 with an overall mean of 0.85 kg/m2. Cans accounted for 41% of the collected items, plastic was the second most popular (38%) while glass litter was the third most abundant item (17%). By comparison, other items formed only 4% of the total items collected during the campaigns. Approximately 46% of the plastic litter consisted of fragments followed by bottles bags and containers (18%). Potential sources are pointed out and recommendations and actions to deal with the problem are suggested.
文摘BACKGROUND: Human activity in wilderness areas has increased globally in recent decades, leading to increased risk of injury and illness. Wilderness medicine has developed in response to both need and interest.METHODS: The field of wilderness medicine encompasses many areas of interest. Some focus on special circumstances(such as avalanches) while others have a broader scope(such as trauma care). Several core areas of key interest within wilderness medicine are discussed in this study.RESULTS: Wilderness medicine is characterized by remote and improvised care of patients with routine or exotic illnesses or trauma, limited resources and manpower, and delayed evacuation to definitive care. Wilderness medicine is developing rapidly and draws from the breadth of medical and surgical subspecialties as well as the technical fields of mountaineering, climbing, and diving. Research, epidemiology, and evidence-based guidelines are evolving. A hallmark of this field is injury prevention and risk mitigation. The range of topics encompasses high-altitude cerebral edema, decompression sickness, snake envenomation, lightning injury, extremity trauma, and gastroenteritis. Several professional societies, academic fellowships, and training organizations offer education and resources for laypeople and health care professionals.CONCLUSIONS: The future of wilderness medicine is unfolding on multiple fronts: education, research, training, technology, communications, and environment. Although wilderness medicine research is technically difficult to perform, it is essential to deepening our understanding of the contribution of specific techniques in achieving improvements in clinical outcomes.
基金Funding for this research came from the Bottlenose Dolphin Research Institute-BDRI and private donations
文摘The extent to which prey abundance influences both bottlenose dolphin foraging behavior and group size in the presence of human activities has not previously been studied.The primary aim of this study was to identify and quantify how wild bottlenose dolphins respond,individually and as groups,to the relative abundance of prey around a fish farm.Detailed views of dolphins' behavior were obtained by focal following individual animals whilst simultaneously collecting surface and underwater behavioral data.A total of 2150 dive intervals were analyzed,corresponding to 342 focal samples,lasting over 34 hours.Bottlenose dolphins remained submerged for a mean duration of 46.4 seconds and a maximum of 249 seconds.This study provides the first quantified data on bottlenose dolphin diving behavior in a marine fin-fish farm area.This study's results indicate that within a fish farm area used intensively by bottlenose dolphins for feeding,dolphins did not modify dive duration.Additionally,underwater observations confirmed that dolphins find it easier to exploit a concentrated food source and it appears that hunting tactic and not group size plays an important role during feeding activities.Thus,bottlenose dolphins appear capable of modifying their hunting tactics according to the abundance of prey.When top predators display behavioral responses to activities not directed at them,the task of studying all possible effects of human activities can become even more challenging.
文摘Aquatic and semi-aquatic mammals, while resting at the water surface or ashore, breathe with a low frequency （f） by comparison to terrestrial mammals of the same body size, the difference increasing the larger the species. Among various interpretations, it was suggested that the low-f breathing is a consequence of the end-inspiratory breath-holding pattern adopted by aquatic mammals to favour buoyancy at the water surface, and evolved to be part of the genetic makeup. If this interpretation was correct it could be expected that, differently from f, the heart rate （HR, beats/min） of aquatic and semi-aquatic mammals at rest would not need to differ from that of terrestrial mammals and that their HR-fratio would be higher than in terrestrial species. Literature data for HR （beats/min） in mammals at rest were gathered for 56 terrestrial and 27 aquatic species. In aquatic mammals the allometric curve （HR=191 .M^18; M= body mass, kg） did not differ from that of terrestrial species （HR=212.M^-0.22） and their HR-fratio （on average 32±5） was much higher than in terrestrial species （5±1） （P〈0.0001）. The comparison of these HR allometric curves to those forfpreviously published indicated that the HR-fratio was body size-independent in terrestrial species while it increased significantly with M in aquatic species. The similarity in HR and differences in f between aquatic and terrestrial mammals agree with the possibility that the lowfof aquatic and semi-aquatic mammals may have evolved for a non-respiratory function, namely the regulation of buoyancy at the water surface [Current Zoology 61（4）： 569-577, 2015].
