Once operating trains are disabled on the railway lines,an efficient manner is to utilize the train for train rescue.Owning to the different train and coupler types,it is difficult to formulate uniform regulations for...Once operating trains are disabled on the railway lines,an efficient manner is to utilize the train for train rescue.Owning to the different train and coupler types,it is difficult to formulate uniform regulations for train to train rescue.In this paper,the longitudinal train dynamics of electric multiple units under rescue were analyzed by field and laboratory tests.The angling behavior of the brakinginduced coupler under compressed in-train forces was analyzed.A dynamic model for the train and draft gear system was developed considering accurate boundary limitations and braking characteristics.The safety indices and their limits for the coupled rescue train were defined.Thedynamic evaluations of different train to train rescue scenarios were analyzed.It is indicated that the coupler vertical rotation occurs during the emergency braking applied by the assisting train.The vertical force components of intrain forces lead to the carbody pitch behavior and even cause local destructions to the coupler system.The carbody pitch motion can arise the inference of in-train devices.Based on the safety evaluation of train and coupler system,the regulations for typical train to train rescue scenarios were formulated.展开更多
Hatcheries are frequently called upon to produce catchable-sized fish for stocking community fishing ponds.Desirable attributes of fish selected for stocking into community ponds are that they are easy to produce in a...Hatcheries are frequently called upon to produce catchable-sized fish for stocking community fishing ponds.Desirable attributes of fish selected for stocking into community ponds are that they are easy to produce in a hatchery system to sizes anglers are interested in catching and they provide anglers with high catch rates once stocked.Hybrid sunfish[male Bluegill(Lepomis macrochirus)×female Green Sunfish(L.cyanellus)]have attributes that potentially make them attractive for use in community fishing ponds.We assessed initial angler catch rates of 100 stocked hybrid sunfish in a 0.12-ha hatchery pond and after being subjected to angling(four,1-hr catch-and-release fishing events with five anglers).We also investigated whether catch rates would change following a supplemental stocking of an additional 100 hybrid sunfish(four,1-hr catch-and-release fishing events with five anglers).The anal fin of each fish in the second stocking was hole punched to differentiate them from those of the first stocking and fish caught by anglers were hole punched in the caudal fin each time they were caught before being released back into the pond.Angler catch rates were highest during initial fishing events that followed stocking(9.2 fish/angler hr and 18.0 fish/angler hr)and substantially declined in subsequent events(≤3.4 fish/angler hr).Catches of the newly stocked fish and previously stocked fish contributed to the high catch following the supplemental stocking.Most(80%)of the fish were caught in the first 30 min of each event and 45%were caught during the first 10 min.Anglers were able to catch 88%of the fish from the first stocking and 67%from the second stocking at least once.No mortality occurred during the study as all fish were recovered when the pond was drained.Our results suggest that hybrid sunfish will potentially provide high initial catch rates following stocking into community ponds,but managers should expect reduced catch rates following initial fishing even without harvest.Additional stocking will be needed to 展开更多
基金supported by the National Natural Science Foundation of China [No.U1334206]the National Key R&D Program of China [No.2016YFB1200500]
文摘Once operating trains are disabled on the railway lines,an efficient manner is to utilize the train for train rescue.Owning to the different train and coupler types,it is difficult to formulate uniform regulations for train to train rescue.In this paper,the longitudinal train dynamics of electric multiple units under rescue were analyzed by field and laboratory tests.The angling behavior of the brakinginduced coupler under compressed in-train forces was analyzed.A dynamic model for the train and draft gear system was developed considering accurate boundary limitations and braking characteristics.The safety indices and their limits for the coupled rescue train were defined.Thedynamic evaluations of different train to train rescue scenarios were analyzed.It is indicated that the coupler vertical rotation occurs during the emergency braking applied by the assisting train.The vertical force components of intrain forces lead to the carbody pitch behavior and even cause local destructions to the coupler system.The carbody pitch motion can arise the inference of in-train devices.Based on the safety evaluation of train and coupler system,the regulations for typical train to train rescue scenarios were formulated.
文摘Hatcheries are frequently called upon to produce catchable-sized fish for stocking community fishing ponds.Desirable attributes of fish selected for stocking into community ponds are that they are easy to produce in a hatchery system to sizes anglers are interested in catching and they provide anglers with high catch rates once stocked.Hybrid sunfish[male Bluegill(Lepomis macrochirus)×female Green Sunfish(L.cyanellus)]have attributes that potentially make them attractive for use in community fishing ponds.We assessed initial angler catch rates of 100 stocked hybrid sunfish in a 0.12-ha hatchery pond and after being subjected to angling(four,1-hr catch-and-release fishing events with five anglers).We also investigated whether catch rates would change following a supplemental stocking of an additional 100 hybrid sunfish(four,1-hr catch-and-release fishing events with five anglers).The anal fin of each fish in the second stocking was hole punched to differentiate them from those of the first stocking and fish caught by anglers were hole punched in the caudal fin each time they were caught before being released back into the pond.Angler catch rates were highest during initial fishing events that followed stocking(9.2 fish/angler hr and 18.0 fish/angler hr)and substantially declined in subsequent events(≤3.4 fish/angler hr).Catches of the newly stocked fish and previously stocked fish contributed to the high catch following the supplemental stocking.Most(80%)of the fish were caught in the first 30 min of each event and 45%were caught during the first 10 min.Anglers were able to catch 88%of the fish from the first stocking and 67%from the second stocking at least once.No mortality occurred during the study as all fish were recovered when the pond was drained.Our results suggest that hybrid sunfish will potentially provide high initial catch rates following stocking into community ponds,but managers should expect reduced catch rates following initial fishing even without harvest.Additional stocking will be needed to
