Dwell Scheduling Algorithm for Digital Array Radar

Aiming at the problem of resource allocation for digital array radar（ DAR）,a dwell scheduling algorithm is proposed in this paper. Firstly,the integrated priority of different radar tasks is designed,which ensures that the imaging tasks are scheduled without affecting the search and tracking tasks; Then,the optimal scheduling model of radar resource is established according to the constraints of pulse interleaving; Finally,a heuristic algorithm is used to solve the problem and a sparse-aperture cognitive ISAR imaging method is used to achieve partial precision tracking target imaging. Simulation results demonstrate that the proposed algorithm can both improve the performance of the radar system,and generate satisfactory imaging results.

A global evaluation of the associations between long-term dynamics of seed falls and rodents

One classic system of pulsed resource and animal population is mast seeding and population dynamics of seedeating rodents in forests.However,we still lack an understanding of the global patterns regarding the contributions of seed falls to rodent outbreaks or population dynamics.We analyzed a global dataset of coupled long-term time series of seed abundances and rodent populations from published literature,including 66 and 89 time series(156 rodent-seed pairs from 37 studies)for rodent and seed abundances,respectively.We found only half of the examined rodent populations showed statistically significant coincidence between rodent outbreak and mastseeding years.Over all the coupled time series,seed abundance was found to positively correlate with rodent abundance with a one-year lag,and the relative importance of seed abundance was much lower than that of density dependence in affecting rodent population growth rates.We also found the relative importance of seed abundance decreased,but that of rodent density dependence increased with the latitude of study.For the first time,our work provides a global pattern on the associations between seed falls and rodent population dynamics mostly in midand high-latitude forests,and highlights the necessity of more long-term studies on this subject in more forest ecosystems.

From trees to fleas: masting indirectly affects flea abundance on a rodent host

Mast seeding causes strongfluctuations in populations of forest animals.Thus,this phenomenon can be used as a natural experiment to examine how variation in host abundance affects parasite loads.We investigatedfleas infesting yellow-necked mice in beech forest after 2 mast and 2 non-mast years.We tested 2 mutually exclusive scenarios:(1)as predicted by classical models of density-dependent transmission,an increase in host density will cause an increase in ectoparasite abundance(defined as the number of parasites per host),versus(2)an increase in host density will cause a decline inflea abundance(“dilution,”which is thought to occur when parasite population growth is slower than that of the host).In addition,we assessed whether masting alters the relationship between host traits(sex and body mass)andflea abundance.We found a hump-shaped relationship between host andflea abundance.Thus,the most basic predictions are too simple to describe ectoparasite dynamics in this system.In addition,masting modified seasonal dynamics offlea abundance,but did not affect the relationship between host traits andflea abundance(individuals with the highest body mass hosted the mostfleas;after controlling for body mass,parasite abundance did not vary between sexes).Our results demonstrate that pulses of tree reproduction can indirectly,through changes in host densities,drive patterns of ectoparasite infestation.