Escape behavior is a common antipredator strategy among wild animals.Here,we investigated the effect of four factors on the vigilance behavior of the endemic Cyprus rock agama(Laudakia cypriaca).Flight initiation dist...Escape behavior is a common antipredator strategy among wild animals.Here,we investigated the effect of four factors on the vigilance behavior of the endemic Cyprus rock agama(Laudakia cypriaca).Flight initiation distance(FID,the minimum distance to which an observer can approach a lizard before it flees)was measured in relation to the type of location(tourist vs.nontourist area),the observer’s starting distance,air temperature,and substrate temperature.We collected data for 39 agamas in tourist areas and 34 of these lizards in nontourist areas.As a whole,the mean starting distance was 10.5 m and the FID was 3.6 m.The average substrate temperature was 34.0℃ and the average air temperature 29.6℃.Only the type of area affected the agamas’escape decisions with FID being 1.8 m shorter in tourist areas than in nontourist areas(2.7 m vs.4.5 m).This is probably due to the habituation of lizards to the presence of humans in the former areas.This study shows that tourism strongly affects the behavior of lizards,which may have consequences for the functioning of the population.Tourists can increase the safety of lizards by creating a human shield to deter predators.Once the tourist season is over,lizards may become more vulnerable to predators.展开更多
Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation.Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of bioph...Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation.Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers'management behavior.The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity(CLDI)to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas.The study was based on both plot survey and household interview data,collected from six typical catchments in mountainous areas of southwestern China.Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index.The rough set theory was referenced to avoid subjectivity during weight allocation.The results show that conventional tillage,deep fertilization,and manual weeding are the main causes of cropland soil erosion,whereas manure application in combination with seasonal fallow reduces soil erosion.Different crop types as well as cropland location factors determine the spatial pattern of CLDI.Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI,and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance.These results are critical to help better protect rural environments in mountainous areas.Based on the results,methods to reduce cropland soil erosion are suggested.展开更多
This paper proposes a quadrant glitch compensation method to achieve nanometer-level accuracy of contouring control for a feed drive system using linear ball guides.The proposed method is a combination of a modified d...This paper proposes a quadrant glitch compensation method to achieve nanometer-level accuracy of contouring control for a feed drive system using linear ball guides.The proposed method is a combination of a modified disturbance observer(“disturbance suppressor”)and an improved repetitive control scheme.Sinusoidal motion tests with 1 mm amplitude and 0.1 Hz driving frequency were conducted using a single-axis feed drive system to verify the quadrant glitch compensation ability of this method.First,the repeatability of the quadrant glitches in the experimental system was verified,which is the most important characteristic required for compensation via repetitive control.Then,by applying the combination of disturbance suppressor and conventional repetitive control,the amplitudes of the quadrant glitches were decreased to less than 1 nm;in other words,the ratio of the magnitude of the quadrant glitch to the amplitude of the position reference was less than 1/1,000,000.However,for both compensation schemes mentioned before,vibrations were generated when the feed speed increased.Moreover,the amplitudes increased with the number of repetitions.The reason for the vibrations was identified as the repetitive control mechanism.To suppress these vibrations,the repetitive control was applied only to narrowed regimes near the quadrant glitches.Thus,the maximum contouring error was decreased to 2 nm.In addition,the nonlinear spring behavior of the linear ball guides was confirmed to affect the stability of the control systems.展开更多
文摘Escape behavior is a common antipredator strategy among wild animals.Here,we investigated the effect of four factors on the vigilance behavior of the endemic Cyprus rock agama(Laudakia cypriaca).Flight initiation distance(FID,the minimum distance to which an observer can approach a lizard before it flees)was measured in relation to the type of location(tourist vs.nontourist area),the observer’s starting distance,air temperature,and substrate temperature.We collected data for 39 agamas in tourist areas and 34 of these lizards in nontourist areas.As a whole,the mean starting distance was 10.5 m and the FID was 3.6 m.The average substrate temperature was 34.0℃ and the average air temperature 29.6℃.Only the type of area affected the agamas’escape decisions with FID being 1.8 m shorter in tourist areas than in nontourist areas(2.7 m vs.4.5 m).This is probably due to the habituation of lizards to the presence of humans in the former areas.This study shows that tourism strongly affects the behavior of lizards,which may have consequences for the functioning of the population.Tourists can increase the safety of lizards by creating a human shield to deter predators.Once the tourist season is over,lizards may become more vulnerable to predators.
基金jointly funded by the National Key Basic Research Program of China (973 program) (Grant NO.2015CB452702)the National Natural Science Foundation of China (Grant NO.41371539)partially supported by the CDM Fund Grant Project in China (Grant NO. 2013030)
文摘Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation.Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers'management behavior.The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity(CLDI)to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas.The study was based on both plot survey and household interview data,collected from six typical catchments in mountainous areas of southwestern China.Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index.The rough set theory was referenced to avoid subjectivity during weight allocation.The results show that conventional tillage,deep fertilization,and manual weeding are the main causes of cropland soil erosion,whereas manure application in combination with seasonal fallow reduces soil erosion.Different crop types as well as cropland location factors determine the spatial pattern of CLDI.Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI,and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance.These results are critical to help better protect rural environments in mountainous areas.Based on the results,methods to reduce cropland soil erosion are suggested.
文摘This paper proposes a quadrant glitch compensation method to achieve nanometer-level accuracy of contouring control for a feed drive system using linear ball guides.The proposed method is a combination of a modified disturbance observer(“disturbance suppressor”)and an improved repetitive control scheme.Sinusoidal motion tests with 1 mm amplitude and 0.1 Hz driving frequency were conducted using a single-axis feed drive system to verify the quadrant glitch compensation ability of this method.First,the repeatability of the quadrant glitches in the experimental system was verified,which is the most important characteristic required for compensation via repetitive control.Then,by applying the combination of disturbance suppressor and conventional repetitive control,the amplitudes of the quadrant glitches were decreased to less than 1 nm;in other words,the ratio of the magnitude of the quadrant glitch to the amplitude of the position reference was less than 1/1,000,000.However,for both compensation schemes mentioned before,vibrations were generated when the feed speed increased.Moreover,the amplitudes increased with the number of repetitions.The reason for the vibrations was identified as the repetitive control mechanism.To suppress these vibrations,the repetitive control was applied only to narrowed regimes near the quadrant glitches.Thus,the maximum contouring error was decreased to 2 nm.In addition,the nonlinear spring behavior of the linear ball guides was confirmed to affect the stability of the control systems.
