There exist various service systems that have hierarchical structure. In hierarchical service networks, facilities at different levels provide different types of services. For example, in health care systems, general centers provide low-level services such as primary health care services, while the specialized hospitals provide high-level services. Because of demand congestion in service networ...

The Partial Vertex Cover problem is to decide whether a graph contains at most k nodes covering at least t edges. We present deterministic and randomized algorithms with run times of O(1.396) and O(1.2993), respectively. For graphs of maximum degree three, we show how to solve this problem in O(1.26) steps. Finally, we give an O(3) algorithm for Exact Partial Vertex Cover, which asks for at mos...

Monitoring the long-distance pipelines, rivers, roads and boundary lines with wireless sensor networks belongs to one-dimensional region monitoring. This paper primarily studies the coverage problems of the sensor networks in one-dimensional regions. Firstly, the onedimensional random coverage model is processed for the sensor nodes in one-dimensional monitoring region, and a formula is given t...

In the facility location problem usually reducing total transferring cost and time are common objectives. Designing of a network with hub facilities can improve network efficiency. In this study a new model is presented for P-hub covering location problem. In the p-hub covering problem it is attempted to locate hubs and allocate customers to established hubs while allocated nodes to hubs are in...

Energy consumption in datacenters has recently become a major concern due to the rising operational costs and scalability issues. Recent solutions to this problem propose the principle of energy proportionality, i.e., the amount of energy consumed by the server nodes must be proportional to the amount of work performed. For data parallelism and fault tolerance purposes, most common file systems...

Wireless sensor nodes are electronic devices capable of collecting, storing, and processing environmental information, and communicating with other sensor nodes through wireless communications. Hundreds or thousands of wireless sensor nodes deployed in a region of interest comprise a wireless sensor network (WSN), where all members cooperatively monitor the whole region, barriers, or targets (p...

hub covering location problem, network design,   single machine scheduling, genetic algorithm,   shuffled frog leaping algorithm   hub location problems (hlp) are synthetic optimization problems that appears in telecommunication and transportation networks where nodes send and receive commodities (i.e., data transmissions, passengers transportation, express packages, postal deliveries, etc.) th...

Abstact: A WSN is a specialized wireless network made up of a large number of sensors and at least one base station. Recent technological advances in communications and computation have enabled the development of low-cost, low-power,small in size, and multifunctional sensor nodes in a Wireless Sensor Network (WSN). Since the radio transmission and reception consumes a lot of energy, one of the ...