Exponential gravitational search algorithm-based VM migration strategy for load balancing in cloud computing

With the advancement in the science and technology,cloud computing has become a recent trend in environment with immense requirement of infrastructure and resources.Load balancing of cloud computing environments is an important matter of concern.The migration of the overloaded virtual machines(VMs)to the underloaded VM with optimized resource utilization is the effective way of the load balancing.In this paper,a new VM migration algorithm for the load balancing in the cloud is proposed.The migration algorithm proposed(EGSA-VMM)is based on exponential gravitational search algorithm which is the integration of gravitational search algorithm and exponential weighted moving average theory.In our approach,the migration is done based on the migration cost and QoS.The experimentation of proposed EGSA-based VM migration algorithm is compared with ACO and GSA.The simulation of experiments shows that the proposed EGSA-VMM algorithm achieves load balancing and reasonable resource utilization,which outperforms existing migration strategies in terms of number of VM migrations and number of SLA violations.

Migration routes and differences in migration strategies of Whooper Swans between spring and autumn

Long-distance migratory birds travel more rapidly in spring than in autumn,as they face temporal breeding constraints.However,several species travel slower in spring owing to environmental influences,such as food availability and wind conditions.GPS trackers were attached to 17 Whooper Swans(Cygnus cygnus) inhabiting northeastern Mongolia,to determine their migration routes and stopover sites in spring and autumn.Differences between spring and autumn migrations,migration-influencing parameters,and the effect of spring stopover site temperatures were analyzed.Six swans completed perfect tours between their wintering and breeding sites,and these data were used for analysis.Spring migration lasted 57 days,with 49.2 days spent at 3.7 stopover sites.Autumn migration lasted 21.5 days,with 17.5 days spent at 1.0 stopover sites.Thus,the swans traveled more rapidly in autumn than in spring.Migration distance,number of stopovers,migration speed,and straightness were important migration determinants in both spring and autumn.Migration distance,stopover duration,number of stopovers,daily travel speed,travel duration,and migration speed differed significantly between spring and autumn.During spring migration,the temperature at the current stopover sites and that at the future stopover sites displayed significant variations(t=1585.8,df=631.6,p <0.001).These findings are critical for the conservation and management of Whooper Swans and their key habitats in East Asian regions,and the data are anticipated to make a particularly significant contribution toward developing detailed management plans for the conservation of their key habitats.

Migration routes and strategies of Grey Plovers (Pluvialis squatarola) on the East Atlantic Flyway as revealed by satellite tracking

Background:While the general migration routes of most waders are known,details concerning connectivity between breeding grounds, stopover sites and wintering grounds are often lacking.Such information is critical from the conservation perspective and necessary for understanding the annual cycle.Studies are especially needed to identify key stopover sites in remote regions. Using satellite transmitters, we traced spring and autumn migration routes and connectivity of Grey Plovers on the East Atlantic Flyway.Our findings also revealed the timing,flight speed, and duration of migrations. Methods:We used ARGOS satellite transmitters to track migration routes of 11 Grey Plovers that were captured at the German Wadden Sea where they had stopped during migration.Birds were monitored for up to 3 years,2011-2014.Results:Monitoring signals indicated breeding grounds in the Taimyr and Yamal regions;important staging sites on the coasts of the southern Pechora Sea and the Kara Sea;and wintering areas that ranged from NW-Ireland to Guinea Bissau.The average distance traveled from wintering grounds to breeding grounds was 5534 km. Migration duration varied between 42 and 152 days;during this period birds spent about 95% of the time at staging sites.In spring most plovers crossed inland Eastern Europe, whereas in autumn most followed the coastline.Almost all of the birds departed during favorable wind conditions within just 4 days (27-30 May) on northward migration from the Wadden Sea.In spring birds migrated significantly faster between the Wadden Sea and the Arctic than on return migration in autumn (12 vs.37 days),with shorter stopovers during the northward passage.Conclusions:Our study shows that satellite tags can shed considerable light on migration strategies by revealing the use of different regions during the annual cycle and by providing detailed quantitative data on population connectivity and migration timing.

Time and energy minimization strategy codetermine the loop migration of demoiselle cranes around the Himalayas

Tens of thousands of demoiselle cranes’crossing the Himalayas to the Indian subcontinent have been reported for decades,but their exact spring migration route remained a mystery until our previous study found they made a detour in spring along the western edge of the Himalayas and crossed the Mongolian Plateau to their breeding areas based on satellite telemetry of 3 birds.To corroborate the loop migration pattern and explore whether demoiselle crane’s loop migration route is shaped by time-and energy-minimization strategies in spring and autumn and how the temporal and spatial variation of environmental conditions contribute to crane’s selection of migration routes,we tracked 11 satellite-tagged demoiselle cranes from their breeding area in China and Russia,simulated 2 pseudo migration routes,and then compared the environmental conditions,time,and energy cost between true and pseudo routes in the same season.Results show that demoiselles’spring migration obeyed time-minimization hypothesis,avoiding the colder Qinghai-Tibet Plateau,benefited by abundant food and higher thermal and orographic uplift along the route;autumn migration follows energy-minimization hypothesis with the shorter route.Our research will contribute to uncover the mechanical reasons why demoiselle crane avoids crossing the giant barrier of the Himalayas in spring,and shapes a loop migration route.