Search results for "efficient"

Technologies for green radio communication networks

2011

Since the introduction of cellular communications in the early '80s, the demand for two-way mobile communication services has increased tremendously. Today there are over 4 billion mobile users and 4.6 million radio base station sites worldwide. This rapid growth of the cellular mobile industry has been at the price of increased energy consumption and a sizable carbon footprint.

On stiffness and damping of vibro-impact dynamics of backlash

2021

We consider the instantaneous stiffness and damping of the vibro-impact in a backlash pair. Opposed to the existing and mostly used models of the backlash, we address the problem of contact and separation, and the associated force propagation within a mechanical pair, from a viewpoint of the vibro-impact dynamics. We discuss the impact forces with the coefficient of restitution as a principal factor which shapes the transient backlash response.We show that a common approach to modeling the backlash by means of a dead-zone in a restoring force is unsuitable for correctly capturing the mechanical impact. We exemplary demonstrate a qualitative accord between an experimental backlash response a…

DTMC modeling for performance evaluation of DW-MAC in wireless sensor networks

2016

Synchronized duty cycling (DC) aligns sensor nodes to wake up at the same time in order to reduce idle listening for medium access control (MAC) in wireless sensor networks (WSNs). Demand wakeup MAC (DW-MAC) is a popular synchronous DC MAC protocol which allows nodes to compete and transmit multiple packets in one operational cycle. This multiple packet transmission (MPT) feature makes DW-MAC more energy efficient when comparing with other existing single time competition based protocols such as sensor MAC (S-MAC). In the literature, no analytical model exists to evaluate the performance of DW-MAC. In this paper, we develop two associated discrete time Markov chain (DTMC) models and incorpo…

Energy Efficient Optimization for Solar-Powered UAV Communications System

2021

In this work, we explore the energy efficiency optimization for a solar-powered unmanned aerial vehicle (UAV) communications system. We consider a scenario where a number of ground users (GUs) connect with a solar-powered multi-antenna UAV over a wireless link. First, we are able to derive the relations between the uplink data rate and heading angle of UAV and transmission power of GUs. In addition, the harvested energy from solar light is also affected by UAV’s angle. Accordingly, with the objective to maximize the energy efficiency that is related to uplink data rate and energy consumption, we propose to dynamically adjust the UAV trajectory and gesture, by optimizing its velocity, accele…

Energy consumption and optimal relay node placement for cooperative retransmissions

2010

Previous work on cooperative MAC design has shown significant performance improvement in terms of throughput and packet delivery ratio. However, little attention has been paid to extra energy cost at the relay node in order to achieve such benefit. In this paper, we focus on analyzing energy consumption at a relay node in cooperative retransmission networks with mixed Rayleigh and Rician fading channels. Furthermore, optimal relay location is studied with respect to energy efficiency in different scenarios. The simulation and calculation results coincide with each other, both showing the optimal location of the relay node is scenario-dependent and can be obtained under given channel conditi…

Optimization of process variables on physicochemical properties of milk during an innovative refractance window concentration

2020

Flexibility Services in a Mediterranean Small Island to Minimize Costs and Emissions Related to Electricity Production from Fossil Fuels

2020

In last years, the energy efficiency in non-interconnected islands became an important topic, since the electricity production is often based on diesel generators, thus contributing to the global warming. Italian government recently emitted two decrees to promote the introduction of renewable energy technologies in 21 non-interconnected islands, both for electrical and thermal uses. In this paper, the economic and environmental feasibility of the introduction of renewable energies in the island of Pantelleria was assessed adopting an optimization approach. Furthermore, the flexibility provided from the local desalination plant and the domestic water heaters was evaluated. The final demands …

Hidden Markov Random Field model and BFGS algorithm for Brain Image Segmentation

2016

Brain MR images segmentation has attracted a particular focus in medical imaging. The automatic image analysis and interpretation became a necessity. Segmentation is one of the key operations to provide a crucial decision support to physicians. Its goal is to simplify the representation of an image into items meaningful and easier to analyze. Hidden Markov Random Fields (HMRF) provide an elegant way to model the segmentation problem. This model leads to the minimization problem of a function. BFGS (Broyden-Fletcher-Goldfarb-Shanno algorithm) is one of the most powerful methods to solve unconstrained optimization problem. This paper presents how we combine HMRF and BFGS to achieve a good seg…

1 Hop or 2 hops: Topology analysis in Body Area Network

2014

Wireless Body Area Networks (WBANs) have recently received much attention due to the possibility to be used in healthcare applications. For these applications, link reliability and energy efficiency are critical issues, as in many cases, information carried can be vital for the patient and batteries cannot be easily replaced. The wireless on-body channel experiences significant temporal variation due to body movements and the use of relays is sometimes necessary in order to guarantee reliability or improve lifetime. In this paper, an experimental evaluation is used to give a better understanding about reliability, energy consumption and lifetime in a single hop or a two hops communication. …

Field testing of repurposed electric vehicle batteries for price-driven grid balancing

2019

Abstract As electric cars become more widespread, the disposal and recycling of used batteries will become an important challenge. Typically, vehicle batteries are replaced if their capacity drops to 70–80% of initial capacity. However, they may still be useful for stationary applications. In this paper, results from a field test of a molten salt high-temperature electric vehicle battery repurposed as stationary storage for grid balancing are presented. In a previous study, we have shown that a mixed integer linear programming control strategy driven by a spot-market price for electricity is best suited for an implementation on hardware with limited computational resources. A 14-day experim…