The Diver Gas Recovery Installation (DGRI) was evaluated at 80 msw saturation - 100 msw excursion diving on HeO2 in the Naval Medical Research Institute (NMRI) of China in April, 1995. The diving depth, lockout time, ...The Diver Gas Recovery Installation (DGRI) was evaluated at 80 msw saturation - 100 msw excursion diving on HeO2 in the Naval Medical Research Institute (NMRI) of China in April, 1995. The diving depth, lockout time, breathing gas flow rate and consumption, inspired oxygen partial pressure (PO2) and carbon dioxide partial pressure (PCO2) were monitored. The results indicated that PO2 was controlled to fluctuate from 64.3 to 84.0 kPa and PCO2 went up from 0.01 kPa up to O.I kPa during 4 hours excursion diving; recovery of breathing gas reached 95%; three divers felt well and breathed comfortably during simulating heavy work. The test showed that it met desired performance goals. The DGRI is a kind of important equipment for long duration deep dive. It enables the gases exhaled by the divers to be re-cycled, and therefore it has great social, military and economic significance for diving operation and submarine rescue.展开更多
While performing its maiden mission in a recent scientific survey in the West Pacific,a domestic ROV (remotely operated vehicle) system achieved a national record by diving 6,001 meters underwater.Named SeaStar 6000。
The study deals with the observation of the changes in the electrical activities of 8 healthy divers in the 80 msw saturation-100 msw excursion heliox dive by DCG. Results showed significant changes in the 24 h of ave...The study deals with the observation of the changes in the electrical activities of 8 healthy divers in the 80 msw saturation-100 msw excursion heliox dive by DCG. Results showed significant changes in the 24 h of average heart rate, the decrease of heart rate at saturation storage depth and decompression periods being 15.5% and 19.7% respectively. Fortuitous supraventricular premature beats appeared in 8 divers and ventricular premature beats in 5 divers during exposure. Transient ischemic ST-T changes in 6 divers occurred repeatedly during diving operations. The discussion puts up the view that the ST-T changes were due to the stress reaction of the body induced by the combined effect of such stress factors as hyperbaric pressure per se, high partial pressure of oxygen, noise and the closed restricted chamber environment.展开更多
Diving is a recreational activity of growing significance in many countries.In the recreational SCUBA diving industry,a liveaboard service offers tourists to stay on board for several nights and that allows time to tr...Diving is a recreational activity of growing significance in many countries.In the recreational SCUBA diving industry,a liveaboard service offers tourists to stay on board for several nights and that allows time to travel to more distant dive sites.SCUBA diving belongs to an adventure tourism,while cruise is much more leisure tourism activity.However,they share a similar travel mode,so it is very interesting to find the reason behind.Do cruise tourists be the potential diving tourists?The paper adopted the cruising motivation scale for diving tourists to develop a scale for SCUBA divers’motivations of liveaboard.Convenience sampling was used to select participants for the study.After exploratory factor analysis(EFA),the results showed that there were six dimension of SCUBA divers’liveaboard motivation,and the added dimension of divers’preference was valid.Finally,a measurement scale of SCUBA divers’liveaboard motivation was proposed in this study,and the discussion and implication were also presented in the paper.展开更多
Background It is very common for professional divers to have damage on the retinas.Severe retinal lesions can profoundly affect athletes＆#39; training efficacy and their daily lives.At present,it is not clear if ther...Background It is very common for professional divers to have damage on the retinas.Severe retinal lesions can profoundly affect athletes＆#39; training efficacy and their daily lives.At present,it is not clear if there is effective preventive action.Thus,in our study,we continuously tracked the ocular changes in athletes and closely monitored the risk factors associated with retinal detachment.Also,we analyzed possible interventions,their associated factors,and efficacies for timely preventions to protect the retina from damage in professional divers.Methods Between 2009 and 2012,a total of 39 professional divers enrolled in follow-up management.The conducted examinations included ocular examination,record screening on retinal lesion,monitoring best-corrected visual acuity,and checking intraocular pressure （lOP） and the scope of retinal lesion.The management included optimizing training methods,taking customized follow-up based on different retinal lesions,laser treatments for definite cases of retinal tear,retinal degeneration caused by retinal layer thinning or vitreous traction,and observing the changes in the scope of retinopathy.Results Every year,the percentage of divers who have various degrees of retinal lesions is between 43.3% and 56.2%.During the 4 years,there were no statistically significant differences in divers＆#39; best-corrected visual acuity and retinal lesions.There were also no statistically significant differences between male and female athletes.However,there were statistically significant differences in lOP during these years.Moreover there were statistically significant differences in IOP and the scope of retinal lesions between platform divers and springboard divers.Conclusions Our management of retinal lesions could be effective to prevent severe retinopathy in professional divers.At the same time,platform divers are more likely to have retinal lesions than springboard divers.展开更多
Three-dimensional(3D)nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper.It constructs the complete nonlinear coupl...Three-dimensional(3D)nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper.It constructs the complete nonlinear coupling motion equation without any approximations based on diving relative motion relationship directly,and converts it into linear state space equation with the same relative degree by feedback linearization.With the linear equation,slide mode control with strong robustness is employed to design the guidance law,and 3D diving guidance law which can satisfy terminal impact point and falling angle constraints with high precision is obtained by substituting the previous control law into the origin nonlinear guidance system.Besides,regarding lateral overload as the standard,hybrid control strategy which can take full advantage of the excellent characters of both bank-to-turn(BTT)and skid-to-turn(STT)controls is designed to improve the guidance accuracy further.Finally,the results of CAV-H vehicle guidance test show that the algorithm can realize high accuracy guidance even if serious motion coupling exists,and has strong robustness to the path disturbances and navigation errors as well.展开更多
The northern Chilean Patagonia region is a key feeding ground and a nursing habitat in the southern hemisphere for blue whales(Balaenoptera musculus).From 2014 to 2019,during 6 separate research cruises,the dive behav...The northern Chilean Patagonia region is a key feeding ground and a nursing habitat in the southern hemisphere for blue whales(Balaenoptera musculus).From 2014 to 2019,during 6 separate research cruises,the dive behavior of 28 individual blue whales was investigated using bio-logging tags(DTAGs),generating≈190 h of data.Whales dove to significantly greater depths during the day compared to nighttime(day:32.6±18.7 m;night:6.2±2.7 m;P<0.01).During the night,most time was spent close to the surface(86%±9.4%;P<0.01)and at depths of less than 12 m.From 2016 to 2019,active acoustics(scientific echosounders)were used to record prey(euphausiids)density and distribution simultaneously with whale diving data.Tagged whales appeared to perform dives relative to the vertical migration of prey during the day.The association between diurnal prey migration and shallow nighttime dive behavior suggests that blue whales are at increased risk of ship collisions during periods of darkness since the estimated maximum ship draft of vessels operating in the region is also≈12 m.In recent decades,northern Chilean Patagonia has seen a large increase in marine traffic due to a boom in salmon aquaculture and the passenger ship industry.Vessel strike risks for large whales are likely underestimated in this region.Results reported in this study may be valuable for policy and mitigation decisions regarding conservation of the endangered blue whale.展开更多
文摘The Diver Gas Recovery Installation (DGRI) was evaluated at 80 msw saturation - 100 msw excursion diving on HeO2 in the Naval Medical Research Institute (NMRI) of China in April, 1995. The diving depth, lockout time, breathing gas flow rate and consumption, inspired oxygen partial pressure (PO2) and carbon dioxide partial pressure (PCO2) were monitored. The results indicated that PO2 was controlled to fluctuate from 64.3 to 84.0 kPa and PCO2 went up from 0.01 kPa up to O.I kPa during 4 hours excursion diving; recovery of breathing gas reached 95%; three divers felt well and breathed comfortably during simulating heavy work. The test showed that it met desired performance goals. The DGRI is a kind of important equipment for long duration deep dive. It enables the gases exhaled by the divers to be re-cycled, and therefore it has great social, military and economic significance for diving operation and submarine rescue.
文摘While performing its maiden mission in a recent scientific survey in the West Pacific,a domestic ROV (remotely operated vehicle) system achieved a national record by diving 6,001 meters underwater.Named SeaStar 6000。
文摘The study deals with the observation of the changes in the electrical activities of 8 healthy divers in the 80 msw saturation-100 msw excursion heliox dive by DCG. Results showed significant changes in the 24 h of average heart rate, the decrease of heart rate at saturation storage depth and decompression periods being 15.5% and 19.7% respectively. Fortuitous supraventricular premature beats appeared in 8 divers and ventricular premature beats in 5 divers during exposure. Transient ischemic ST-T changes in 6 divers occurred repeatedly during diving operations. The discussion puts up the view that the ST-T changes were due to the stress reaction of the body induced by the combined effect of such stress factors as hyperbaric pressure per se, high partial pressure of oxygen, noise and the closed restricted chamber environment.
文摘Diving is a recreational activity of growing significance in many countries.In the recreational SCUBA diving industry,a liveaboard service offers tourists to stay on board for several nights and that allows time to travel to more distant dive sites.SCUBA diving belongs to an adventure tourism,while cruise is much more leisure tourism activity.However,they share a similar travel mode,so it is very interesting to find the reason behind.Do cruise tourists be the potential diving tourists?The paper adopted the cruising motivation scale for diving tourists to develop a scale for SCUBA divers’motivations of liveaboard.Convenience sampling was used to select participants for the study.After exploratory factor analysis(EFA),the results showed that there were six dimension of SCUBA divers’liveaboard motivation,and the added dimension of divers’preference was valid.Finally,a measurement scale of SCUBA divers’liveaboard motivation was proposed in this study,and the discussion and implication were also presented in the paper.
文摘Background It is very common for professional divers to have damage on the retinas.Severe retinal lesions can profoundly affect athletes＆#39; training efficacy and their daily lives.At present,it is not clear if there is effective preventive action.Thus,in our study,we continuously tracked the ocular changes in athletes and closely monitored the risk factors associated with retinal detachment.Also,we analyzed possible interventions,their associated factors,and efficacies for timely preventions to protect the retina from damage in professional divers.Methods Between 2009 and 2012,a total of 39 professional divers enrolled in follow-up management.The conducted examinations included ocular examination,record screening on retinal lesion,monitoring best-corrected visual acuity,and checking intraocular pressure （lOP） and the scope of retinal lesion.The management included optimizing training methods,taking customized follow-up based on different retinal lesions,laser treatments for definite cases of retinal tear,retinal degeneration caused by retinal layer thinning or vitreous traction,and observing the changes in the scope of retinopathy.Results Every year,the percentage of divers who have various degrees of retinal lesions is between 43.3% and 56.2%.During the 4 years,there were no statistically significant differences in divers＆#39; best-corrected visual acuity and retinal lesions.There were also no statistically significant differences between male and female athletes.However,there were statistically significant differences in lOP during these years.Moreover there were statistically significant differences in IOP and the scope of retinal lesions between platform divers and springboard divers.Conclusions Our management of retinal lesions could be effective to prevent severe retinopathy in professional divers.At the same time,platform divers are more likely to have retinal lesions than springboard divers.
基金supported by the National Natural Science Foundation of China(Grant No.61104200)the National University of Defense Technology Innovation Foundation for Postgraduates(Grant No.B140103)
文摘Three-dimensional(3D)nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper.It constructs the complete nonlinear coupling motion equation without any approximations based on diving relative motion relationship directly,and converts it into linear state space equation with the same relative degree by feedback linearization.With the linear equation,slide mode control with strong robustness is employed to design the guidance law,and 3D diving guidance law which can satisfy terminal impact point and falling angle constraints with high precision is obtained by substituting the previous control law into the origin nonlinear guidance system.Besides,regarding lateral overload as the standard,hybrid control strategy which can take full advantage of the excellent characters of both bank-to-turn(BTT)and skid-to-turn(STT)controls is designed to improve the guidance accuracy further.Finally,the results of CAV-H vehicle guidance test show that the algorithm can realize high accuracy guidance even if serious motion coupling exists,and has strong robustness to the path disturbances and navigation errors as well.
基金supported by the National Key Research and Development Program of China(Grant number 2016YFC0300802)the biodiversity investigation,observation and assessment program(2019-2023)of the Ministry of Ecology and Environment of ChinaIndian Ocean Ninety-east Ridge Ecosystem and Marine Environment Monitoring and Protection,supported by the China Ocean Mineral Resources R&D Association(no.DY135-E2-4).
文摘The northern Chilean Patagonia region is a key feeding ground and a nursing habitat in the southern hemisphere for blue whales(Balaenoptera musculus).From 2014 to 2019,during 6 separate research cruises,the dive behavior of 28 individual blue whales was investigated using bio-logging tags(DTAGs),generating≈190 h of data.Whales dove to significantly greater depths during the day compared to nighttime(day:32.6±18.7 m;night:6.2±2.7 m;P<0.01).During the night,most time was spent close to the surface(86%±9.4%;P<0.01)and at depths of less than 12 m.From 2016 to 2019,active acoustics(scientific echosounders)were used to record prey(euphausiids)density and distribution simultaneously with whale diving data.Tagged whales appeared to perform dives relative to the vertical migration of prey during the day.The association between diurnal prey migration and shallow nighttime dive behavior suggests that blue whales are at increased risk of ship collisions during periods of darkness since the estimated maximum ship draft of vessels operating in the region is also≈12 m.In recent decades,northern Chilean Patagonia has seen a large increase in marine traffic due to a boom in salmon aquaculture and the passenger ship industry.Vessel strike risks for large whales are likely underestimated in this region.Results reported in this study may be valuable for policy and mitigation decisions regarding conservation of the endangered blue whale.
