in recent years wireless sensor networks have attracted researchers' attention due to vast applications. one of the most prominent issues regarding these networks is coverage which is considered as a quality of service parameter. in this study, we try to address energy shortage in wsns through finding a set of optimal coverage nodes in a specific environment. this is performed utilizing effecti...

purpose: to determine the prevalence of refractive errors and rate of need for spectacles in students of region one in mashhad, 2006. methods: by randomized cluster sampling, 2510 students were selected and underwent eye exami-nations including refraction (cycloplegic, manifest), visual acuity, cover test and determination of the spectacle prescription as well as best corrected visual acuity. e...

In order to monitor a region for target intrusion, sensors can be deployed to perform collaborative target detection. To adequately deploy sensors, metrics need to be define to measure the ability of a given deployment to successfully complete this task. Recently, the measure of exposure was defined to evaluate the coverage of the region by a sensor network. Exposure is a versatile metric that ...

Coverage is critical for wireless sensor networks to monitor a region of interest and to provide a good quality of service. In most cases we need to achieve full coverage which means every point inside the region (excluding the obstacles) must be covered by at least one sensor. The problem of placing the minimum number of sensors to achieve full coverage for a region with obstacles is NP-hard. ...

Introduction In 2010, the Global Vaccine Action Plan called on all countries to reach and sustain 90% national coverage and 80% coverage in all districts for the third dose of diphtheria-tetanus-pertussis vaccine (DTP3) by 2015 and for all vaccines in national immunization schedules by 2020. The aims of this study are to analyze recent trends in national vaccination coverage in the World Health...

In this paper an on-line distributed algorithm, namely, Voronoi Partition-based Coverage (VPC), is proposed to solve the problem of complete coverage of a geographical region with known boundary and unknown obstacles using multiple robots. The region is decomposed into Voronoi cells based on the initial positions of robots. Each robot is responsible for covering its Voronoi cell. It is shown th...