Disassembly sequence planning （DSP） plays a significant role in maintenance planning of the aircraft. It is used during the design stage for the analysis of maintainability of the aircraft. To solve product disassem...Disassembly sequence planning （DSP） plays a significant role in maintenance planning of the aircraft. It is used during the design stage for the analysis of maintainability of the aircraft. To solve product disassembly sequence planning problems efficiently, a product disassembly hybrid graph model, which describes the connection, non-connection and precedence relationships between the product parts, is established based on the characteristic of disassembly. Farther, the optimization model is provided to optimize disassembly sequence. And the solution methodology based on the genetic/simulated annealing algorithm with binaxy-tree algorithm is given. Finally, an example is analyzed in detail, and the result shows that the model is correct and efficient.展开更多
Foragers use several senses to locate food,and many animals rely on vision and smell.It is beneficial not to rely on a single sense,which might fail under certain conditions.We examined the contribution of vision and ...Foragers use several senses to locate food,and many animals rely on vision and smell.It is beneficial not to rely on a single sense,which might fail under certain conditions.We examined the contribution of vision and smell to foraging and maze exploration under laboratory conditions using Cataglyphis desert ants as a model.Foraging intensity,measured as the number of workers entering the maze and arriving at the target as well as target arrival time,were greater when food,blue light,or both were offered or presented in contrast to a control.Workers trained to forage for a combined food and light cue elevated their foraging intensity with experience.However,foraging intensity was not higher when using both cues simultaneously than in either one of the two alone.Following training,we split between the two cues and moved either the food or the blue light to the opposite maze corner.This manipulation impaired foraging success by either leading to fewer workers arriving at the target cell(when the light stayed and the food was moved)or to more workers arriving at the opposite target cell,empty of food(when the food stayed and the light was moved).This result indicates that ant workers use both senses when foraging for food and readily associate light with food.展开更多
Injury is common in nature resulting,for example,from fighting,partial predation,or the wear of body parts.Injury is costly,expressed in impaired performance,failure in competition,and a shorter life span.A survey of ...Injury is common in nature resulting,for example,from fighting,partial predation,or the wear of body parts.Injury is costly,expressed in impaired performance,failure in competition,and a shorter life span.A survey of the literature revealed the frequent occurrence of injury in ants and its various causes.We examined whether leg or antenna injury impacts food-discovery time and reduces the likelihood of reaching food in workers of the desert ant Cataglyphis niger.We examined the search-related consequences of injury in groups of either 4 or 8 workers searching for food in a short arena,a long arena,and a maze.We conducted a small field survey to evaluate the prevalence of injury in the studied population.Finally,we compared the survival rates of injured versus uninjured workers in the laboratory.Injury was common in the field,with almost 9%of the workers collected out of the nest,found to be injured.Injured workers survived shorter than uninjured ones and there was a positive link between injury severity and survival.However,we could not detect an effect of injury on any of the searching-related response variables,neither in the arenas nor in the mazes tested.We suggest that workers that survive such injury are only moderately affected by it.展开更多
Theories of forgetting highlight 2 active mechanisms through which animals forget prior knowledge by recipro-cal disruption of memories.According to“proactive interference,”information learned previously interferes ...Theories of forgetting highlight 2 active mechanisms through which animals forget prior knowledge by recipro-cal disruption of memories.According to“proactive interference,”information learned previously interferes with the acquisition of new information,whereas“retroactive interference”suggests that newly gathered information interferes with already existing information.Our goal was to examine the possible effect of both mechanisms in the desert ant Cataglyphis niger,which does not use pheromone recruitment,when learning spatial information while searching for food in a maze.Our experiment indicated that neither proactive nor retroactive interference took place in this system although this awaits confirmation with individual-level learning assays.Rather,the ants’persistence or readiness to search for food grew with successive runs in the maze.Elevated persistence led to more ant workers arriving at the food when retested a day later,even if the maze was shifted between runs.We support thisfinding in a second experiment,where ant workers reached the food reward at the maze end in higher numbers after encountering food in the maze entry compared to a treatment,in which food was present only at the maze end.This result suggests that spatial learning and search persistence are 2 parallel behavioral mechanisms,both assisting foraging ants.We suggest that their relative contribution should depend on habitat complexity.展开更多
We study the growth of epitaxial thin films on pre-patterned substrates that influence the surface diffusion of subsequently deposited material using a kinetic Monte Carlo algorithm that combines the use of inverted l...We study the growth of epitaxial thin films on pre-patterned substrates that influence the surface diffusion of subsequently deposited material using a kinetic Monte Carlo algorithm that combines the use of inverted lists with rejection.The resulting algorithm is well adapted to systems with spatially heterogeneous hopping rates.To evaluate the algorithm’s performance we compare it with an efficient,binary-tree based algorithm.A key finding is that the relative performance of the inverted list algorithm improves with increasing system size.展开更多
基金supported by the National High Technology Research and Development Program of China(2006AA04Z427).
文摘Disassembly sequence planning （DSP） plays a significant role in maintenance planning of the aircraft. It is used during the design stage for the analysis of maintainability of the aircraft. To solve product disassembly sequence planning problems efficiently, a product disassembly hybrid graph model, which describes the connection, non-connection and precedence relationships between the product parts, is established based on the characteristic of disassembly. Farther, the optimization model is provided to optimize disassembly sequence. And the solution methodology based on the genetic/simulated annealing algorithm with binaxy-tree algorithm is given. Finally, an example is analyzed in detail, and the result shows that the model is correct and efficient.
基金We thank the German Research Foundation for funding this research project(DFG,grant no.FO 298/31-1).
文摘Foragers use several senses to locate food,and many animals rely on vision and smell.It is beneficial not to rely on a single sense,which might fail under certain conditions.We examined the contribution of vision and smell to foraging and maze exploration under laboratory conditions using Cataglyphis desert ants as a model.Foraging intensity,measured as the number of workers entering the maze and arriving at the target as well as target arrival time,were greater when food,blue light,or both were offered or presented in contrast to a control.Workers trained to forage for a combined food and light cue elevated their foraging intensity with experience.However,foraging intensity was not higher when using both cues simultaneously than in either one of the two alone.Following training,we split between the two cues and moved either the food or the blue light to the opposite maze corner.This manipulation impaired foraging success by either leading to fewer workers arriving at the target cell(when the light stayed and the food was moved)or to more workers arriving at the opposite target cell,empty of food(when the food stayed and the light was moved).This result indicates that ant workers use both senses when foraging for food and readily associate light with food.
文摘Injury is common in nature resulting,for example,from fighting,partial predation,or the wear of body parts.Injury is costly,expressed in impaired performance,failure in competition,and a shorter life span.A survey of the literature revealed the frequent occurrence of injury in ants and its various causes.We examined whether leg or antenna injury impacts food-discovery time and reduces the likelihood of reaching food in workers of the desert ant Cataglyphis niger.We examined the search-related consequences of injury in groups of either 4 or 8 workers searching for food in a short arena,a long arena,and a maze.We conducted a small field survey to evaluate the prevalence of injury in the studied population.Finally,we compared the survival rates of injured versus uninjured workers in the laboratory.Injury was common in the field,with almost 9%of the workers collected out of the nest,found to be injured.Injured workers survived shorter than uninjured ones and there was a positive link between injury severity and survival.However,we could not detect an effect of injury on any of the searching-related response variables,neither in the arenas nor in the mazes tested.We suggest that workers that survive such injury are only moderately affected by it.
基金We thank the German Research Foundation for funding this research project(DFGgrant no.FO 298/31-1).
文摘Theories of forgetting highlight 2 active mechanisms through which animals forget prior knowledge by recipro-cal disruption of memories.According to“proactive interference,”information learned previously interferes with the acquisition of new information,whereas“retroactive interference”suggests that newly gathered information interferes with already existing information.Our goal was to examine the possible effect of both mechanisms in the desert ant Cataglyphis niger,which does not use pheromone recruitment,when learning spatial information while searching for food in a maze.Our experiment indicated that neither proactive nor retroactive interference took place in this system although this awaits confirmation with individual-level learning assays.Rather,the ants’persistence or readiness to search for food grew with successive runs in the maze.Elevated persistence led to more ant workers arriving at the food when retested a day later,even if the maze was shifted between runs.We support thisfinding in a second experiment,where ant workers reached the food reward at the maze end in higher numbers after encountering food in the maze entry compared to a treatment,in which food was present only at the maze end.This result suggests that spatial learning and search persistence are 2 parallel behavioral mechanisms,both assisting foraging ants.We suggest that their relative contribution should depend on habitat complexity.
基金MAS was supported by a grant from DOE(DE-FG02-03ER2558)TPS was supported by grants from DOE(DE-FG02-03ER2558)and NSF(NSF-DMS-0707443).
文摘We study the growth of epitaxial thin films on pre-patterned substrates that influence the surface diffusion of subsequently deposited material using a kinetic Monte Carlo algorithm that combines the use of inverted lists with rejection.The resulting algorithm is well adapted to systems with spatially heterogeneous hopping rates.To evaluate the algorithm’s performance we compare it with an efficient,binary-tree based algorithm.A key finding is that the relative performance of the inverted list algorithm improves with increasing system size.
