Search results for "Computer network"
showing 10 items of 1634 documents
Bluetooth Base Station Minimal Deployment for High Definition Positioning
2005
This paper discusses our approach to the problem of arranging a Bluetooth based positioning system capable of providing people coordinates in a given area with an accuracy as high as possible. Our strategy focuses on optimizing the disposition of a minimal number of available Bluetooth base stations in a subset of locations which are the only ones permitted by site characteristics and constraints. We used a genetic algorithm to this purpose and a layout chromosome whose best evolution suggested us how to deploy a minimal set of Bluetooth base stations. As a case study, we discuss our experiments and results which deal with a late middle age castle in Sicily where we carried out many trials.
New facets and an enhanced branch-and-cut for the min-max K -vehicles windy rural postman problem
2011
[EN] The min-max windy rural postman problem is a multiple vehicle version of the windy rural postman problem, WRPP, which consists of minimizing the length of the longest route to find a set of balanced routes for the vehicles. In a previous paper, an ILP formulation and a partial polyhedral study were presented, and a preliminary branch-and-cut algorithm that produced some promising computational results was implemented. In this article, we present further results for this problem. We describe several new facet-inducing inequalities obtained from the WRPP, as well as some inequalities that have to be satisfied by any optimal solution. We present an enhanced branch-and-cut algorithm that t…
Smart grid-aware scheduling in data centres
2015
In several countries the expansion and establishment of renewable energies result in widely scattered and often weather-dependent energy production, decoupled from energy demand. Large, fossil-fuelled power plants are gradually replaced by many small power stations that transform wind, solar and water power into electrical power. This leads to changes in the historically evolved power grid that favours top-down energy distribution from a backbone of large power plants to widespread consumers. Now, with the increase of energy production in lower layers of the grid, there is also a bottom-up flow of the grid infrastructure compromising its stability. In order to locally adapt the energy deman…
Optimal Design of an X-Band, Fully-Coaxial, Easily-Tunable Broadband Power Equalizer for a Microwave Power Module
2020
A microwave power module (MPM), which is a hybrid combination of a solid-state power amplifier (SSPA) as a driver and a traveling-wave tube amplifier (TWT) as the final high power stage, is a high-power device largely used for radar applications. A gain equalizer is often required to flatten the TWT output power gain owing to its big gain fluctuations over the operating frequency range. In this paper, the design of an X-band, fully-coaxial, easily-tunable broadband power equalizer for an MPM is presented. The structure is composed of a coaxial waveguide as the main transmission line and a coaxial cavity loaded with absorbing material as a resonant unit. Sensitivity analyses of the attenuati…
Compliance of IEEE 802.22 WRAN for field area network in smart grid
2016
Distributed power system network is going to be complex, and it will require high-speed, reliable and secure communication systems for managing intermittent generation with coordination of centralised power generation, including load control. Cognitive Radio (CR) is highly favourable for providing communications in Smart Grid by using spectrum resources opportunistically. The IEEE 802.22 Wireless Regional Area Network (WRAN) having the capabilities of CR use vacant channels opportunistically in the frequency range of 54 MHz to 862 MHz occupied by TV band. A comprehensive review of using IEEE 802.22 for Field Area Network in power system network using spectrum sensing (CR based communication…
A low power protocol to broadcast real-time data traffic in a clustered ad hoc network
2002
Energy saving is an extremely important design criteria for mobile ad hoc networks. We present the intra-cluster data-dissemination protocol (Icdp). The Icdp is used to group nodes around a special one, called the cluster leader (CL). The CL centralizes the power management mechanism and acts as a proxy for data transfer between the cluster and the rest of the nodes in the region. When a cluster node enables the power management it goes into "sleep" mode, to minimize power consumption. The CL buffers data frames for power saving stations and delivers them on the stations' request. We periodically distribute the cluster leader role among all the nodes inside the cluster, to not overload a si…
A review of fuel cell based hybrid power supply architectures and algorithms for household appliances
2014
Abstract Nowadays, renewable power system solutions are widely investigated for residential applications. Grid-connected systems including energy storage elements are designed. Advanced research is actually focused on improving the reliability and energy density of renewable systems reducing the whole utility cost. Source and load modeling, power architectures and algorithms are only a few topics to be addressed. Designers have to carefully deal with each subtopic prior to design efficient renewable energy systems. In the literature, each topic is separately discussed and the lack of a unique reference guide is clear to power electronics designers. In this paper, each design step including …
Energy-Efficient Protocol Design
2015
Recent studies have shown that the total energy consumed by the Internet has followed an increasing trend over the years. A considerable part of this energy is wasted due to an inefficient utilization of edge devices , that is, Personal Computers (PCs) and other user equipment in homes and offices. PCs are often left on even when they are not used (e.g., overnight or during weekends), while other edge devices, such as printers, IP phones, and displays, are typically kept always on , especially in public buildings. A number of solutions have been proposed for eliminating, or reducing, energy wastes caused by edge devices. In this chapter, we propose a general taxonomy for their classificatio…
Comparison between Different Dynamic Reconfigurations of Electrical Connections for partially shaded PV Modules
2018
This paper presents an economical investigation on the benefits related to the employment of reconfiguration systems for photovoltaic plants. More in detail, different structures of reconfigurators are proposed and, in order to evaluate the economical convenience on their installation, the Net Present Value is used as a validation element. Significant results are carried out from the proposed analysis.
A Low-level Simulation Study of Prioritization in IEEE 802.11e Contention-based Networks
2006
This work deals with the performance evaluation of the IEEE 802.11e EDCA proposal for service prioritization in Wireless LANs. A large amount of study has been carried out in the scientific community to evaluate the performance of the EDCA proposal, mainly in terms of throughput and access delay differentiation. However, we argue that further performance insights are needed in order to fully understand the principles behind the EDCA prioritization mechanisms. To this purpose, rather than limit our investigation on throughput and delay performance figures, we take a closer look to their operation also in terms of low-level performance metrics (such as probability of accessing specific channe…