BACKGROUND Complicated cataract surgery is challenging,especially in cases of hard nuclear cataract with severe anterior capsule organization.It is important to avoid the risk of surgery and improve the surgical skill...BACKGROUND Complicated cataract surgery is challenging,especially in cases of hard nuclear cataract with severe anterior capsule organization.It is important to avoid the risk of surgery and improve the surgical skills of surgeons.CASE SUMMARY A 60-year-old man presented with severe cataract and visual impairment.The anterior capsule of the lens was irregularly organized and pulled to the surrounding capsule,and white porcelain organized cord and brown-black lens nucleus were clearly visible.In phacoemulsification,maintaining the anterior capsule round and intact plays a key role in a successful surgery.In this case,if the conventional capsule treatment method was used,the anterior capsule would be torn.Therefore,we adopted a segmented anterior capsule treatment method,and a blasting method to release energy when dealing with the lens nucleus,and achieved good surgical results.CONCLUSION Complicated cataract surgery is challenging and requires precise skills.Operation plans should be made reasonably to predict the risk of surgery,and improve the visual quality of the patients.展开更多
Sensing coverage is a fundamental design issue in wireless sensor networks(WSNs),while sensor scheduling ensures coverage degree to the monitored event and extends the network lifetime.In this paper,we address k-cover...Sensing coverage is a fundamental design issue in wireless sensor networks(WSNs),while sensor scheduling ensures coverage degree to the monitored event and extends the network lifetime.In this paper,we address k-coverage scheduling problem in dense WSNs,we maintain a connected k-coverage energy efficiently through a novel Hard-Core based Coordinated Scheduling(HCCS),in which hardcore is a thinning process in stochastic geometry that inhibits more than one active sensor covering any area redundantly in a minimum distance. As compared with existing coordinated scheduling,HCCS allows coordination between sensors with little communication overhead.Moreover,due to the traditional sensing models in k-coverage analysis is unsuitable to describe the characteristic of transmit channel in dense WSNs,we propose a novel sensing model integrating Rayleigh Fading and Distribution of Active sensors(RFDA),and derive the coverage measure and k-coverage probability for the monitored event under RFDA. In addition,we analyze the influence factors,i.e. the transmit condition and monitoring degree to the k-coverage probability. Finally,through Monte Carlo simulations,it is shown that the k-coverage probability of HCCS outperforms that of its random scheduling counterpart.展开更多
The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a ran...The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a range of studies. However, in consideration of the operability and available sample length in collecting hard sediments, these methods exhibit no advantages. In this paper, a new corer which can exploit both hydrostatic energy and gravity energy for hard sediments coting is presented. The hydrostatic energy is provided by pressure differential between ambient seawater pressure and air pressure in an empty cavity. During sampling process, the corer penetrates into the sediment like a gravity corer and then automatically shifts to the percussion mode. The experiments in the laboratory indicate that the corer can complete 40 cycles in the sea with a cycle time of 2.8 seconds in percussion mode and impact the sample tube with the velocity of 0.2 m/s during each cycle. Besides, its adjustable falling velocity can make the corer achieve the maximum efficiency in coring different sediments.展开更多
文摘BACKGROUND Complicated cataract surgery is challenging,especially in cases of hard nuclear cataract with severe anterior capsule organization.It is important to avoid the risk of surgery and improve the surgical skills of surgeons.CASE SUMMARY A 60-year-old man presented with severe cataract and visual impairment.The anterior capsule of the lens was irregularly organized and pulled to the surrounding capsule,and white porcelain organized cord and brown-black lens nucleus were clearly visible.In phacoemulsification,maintaining the anterior capsule round and intact plays a key role in a successful surgery.In this case,if the conventional capsule treatment method was used,the anterior capsule would be torn.Therefore,we adopted a segmented anterior capsule treatment method,and a blasting method to release energy when dealing with the lens nucleus,and achieved good surgical results.CONCLUSION Complicated cataract surgery is challenging and requires precise skills.Operation plans should be made reasonably to predict the risk of surgery,and improve the visual quality of the patients.
基金supported by the National Science Foundation of China under Grant 61271186
文摘Sensing coverage is a fundamental design issue in wireless sensor networks(WSNs),while sensor scheduling ensures coverage degree to the monitored event and extends the network lifetime.In this paper,we address k-coverage scheduling problem in dense WSNs,we maintain a connected k-coverage energy efficiently through a novel Hard-Core based Coordinated Scheduling(HCCS),in which hardcore is a thinning process in stochastic geometry that inhibits more than one active sensor covering any area redundantly in a minimum distance. As compared with existing coordinated scheduling,HCCS allows coordination between sensors with little communication overhead.Moreover,due to the traditional sensing models in k-coverage analysis is unsuitable to describe the characteristic of transmit channel in dense WSNs,we propose a novel sensing model integrating Rayleigh Fading and Distribution of Active sensors(RFDA),and derive the coverage measure and k-coverage probability for the monitored event under RFDA. In addition,we analyze the influence factors,i.e. the transmit condition and monitoring degree to the k-coverage probability. Finally,through Monte Carlo simulations,it is shown that the k-coverage probability of HCCS outperforms that of its random scheduling counterpart.
基金supported by the National Natural Science Foundation of China (Grant No. 40806043)
文摘The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a range of studies. However, in consideration of the operability and available sample length in collecting hard sediments, these methods exhibit no advantages. In this paper, a new corer which can exploit both hydrostatic energy and gravity energy for hard sediments coting is presented. The hydrostatic energy is provided by pressure differential between ambient seawater pressure and air pressure in an empty cavity. During sampling process, the corer penetrates into the sediment like a gravity corer and then automatically shifts to the percussion mode. The experiments in the laboratory indicate that the corer can complete 40 cycles in the sea with a cycle time of 2.8 seconds in percussion mode and impact the sample tube with the velocity of 0.2 m/s during each cycle. Besides, its adjustable falling velocity can make the corer achieve the maximum efficiency in coring different sediments.
