Search results for "Computer Networks and Communications"
showing 10 items of 766 documents
On asymmetric periodic solutions in relay feedback systems
2021
Abstract Asymmetric self-excited periodic motions or periodic solutions which are produced by relay feedback systems that have symmetric characteristics are studied in the paper. Two different mechanisms of producing an asymmetric oscillation by a system with symmetric properties are noted and analyzed by the locus of a perturbed relay system (LPRS) method. Bifurcation between the ability to excite symmetric and asymmetric oscillation with variation of system parameters is analyzed. An algorithm of finding asymmetric solutions is proposed.
A Nonisovelocity Geometry-Based Underwater Acoustic Channel Model
2018
This paper proposes a new geometry-based shallow underwater acoustic (UWA) channel model allowing for nonisovelocity ocean conditions. The fact that the isovelocity assumption does not hold in many real-world scenarios motivates the need for developing channel models for nonisovelocity UWA propagation environments. Starting from a geometrical model, we develop a stochastic channel model for a single-input single-output (SISO) vehicle-to-vehicle UWA channel assuming that the ocean surface and bottom are rough and that the speed of sound varies with depth. The effect of the nonisovelocity condition has been assessed regarding its influence on the temporal autocorrelation function, the frequen…
Surgical implantation of electronic tags does not induce medium-term effect: insights from growth and stress physiological profile in two marine fish…
2020
Abstract Background Telemetry applied to aquatic organisms has recently developed greatly. Physiological sensors have been increasingly used as tools for fish welfare monitoring. However, for the technology to be used as a reliable welfare indicator, it is important that the tagging procedure does not disrupt fish physiology, behaviour and performance. In this communication, we share our medium-term data on stress physiological profile and growth performance after surgical tag implantation in two important marine fish species for European aquaculture, the sea bream (Sparus aurata) and the European sea bass (Dicentrarchus labrax). Results Blood samples after surgical tag implantation (46 day…
Novel Wood Resistance Measurement Method Reducing the Initial Transient Instabilities Arising in DC Methods Due to Polarization Effects
2019
A novel method for measuring the electrical resistance in wood is presented. It is based on applying an Alternating Current (AC) to two electrodes rammed into the wood. The method reduces the transient time for value stabilization. In case of Direct Current (DC) resistance measurement methods, typically used in wood measurement, an initial transient exists, invalidating the measured value during an initial transient period. This measurement method uses an electronic circuit based on a relaxation oscillator where the wood automatically sets the oscillation frequency depending on its electrical resistance. Compared to other AC methods, this circuit greatly simplifies the measurement process, …
Low-Power, Subthreshold Reference Circuits for the Space Environment : Evaluated with -rays, X-rays, Protons and Heavy Ions
2019
The radiation tolerance of subthreshold reference circuits for space microelectronics is presented. The assessment is supported by measured results of total ionization dose and single event transient radiation-induced effects under &gamma
Hybrid P2P schemes for remote terrain interactive visualization systems
2013
Over the last few years, there has been a lot of development of interactive terrain visualization applications using remote databases. One of the main problems that these applications must face is scalability. These applications usually use a client-server model that cannot support a large number of concurrent requests without using a considerable number of servers. In this paper, we present a full comparative study of new hybrid P2P schemes for terrain interactive visualization systems. The performance evaluation results show that the best strategy consists of avoiding the periodical reporting among peer nodes about the current information contained in each node, while using some servers a…
Experimental trade-offs between different strategies for multihop communications evaluated over real deployments of wireless sensor network for envir…
2018
Although much work has been done since wireless sensor networks appeared, there is not a great deal of information available on real deployments that incorporate basic features associated with these networks, in particular multihop routing and long lifetimes features. In this article, an environmental monitoring application (Internet of Things oriented) is described, where temperature and relative humidity samples are taken by each mote at a rate of 2 samples/min and sent to a sink using multihop routing. Our goal is to analyse the different strategies to gather the information from the different motes in this context. The trade-offs between ‘sending always’ and ‘buffering locally’ approac…
Bit-parallel approximate pattern matching: Kepler GPU versus Xeon Phi
2016
Advanced SIMD features on GPUs and Xeon Phis promote efficient long pattern search.A tiled approach to accelerating the Wu-Manber algorithm on GPUs has been proposed.Both the GPU and Xeon Phi yield two orders-of-magnitude speedup over one CPU core.The GPU-based version with tiling runs up to 2.9 × faster than the Xeon Phi version. Approximate pattern matching (APM) targets to find the occurrences of a pattern inside a subject text allowing a limited number of errors. It has been widely used in many application areas such as bioinformatics and information retrieval. Bit-parallel APM takes advantage of the intrinsic parallelism of bitwise operations inside a machine word. This approach typica…
Cost-Effective eHealth System Based on a Multi-Sensor System-on-Chip Platform and Data Fusion in Cloud for Sport Activity Monitoring
2018
eHealth systems provide medical support to users and contribute to the development of mobile and quality health care. They also provide results on the prevention and follow-up of diseases by monitoring health-status indicators and methodical data gathering in patients. Telematic management of health services by means of the Internet of Things provides immediate support and it is cheaper than conventional physical presence methods. Currently, wireless communications and sensor networks allow a person or group to be monitored remotely. The aim of this paper is to develop and assess a system for monitoring physiological parameters to be applied in different scenarios, such as health or sports.…
Cross-Layer MAC Protocol for Unbiased Average Consensus Under Random Interference
2019
Wireless Sensor Networks have been revealed as a powerful technology to solve many different problems through sensor nodes cooperation. One important cooperative process is the so-called average gossip algorithm, which constitutes a building block to perform many inference tasks in an efficient and distributed manner. From the theoretical designs proposed in most previous work, this algorithm requires instantaneous symmetric links in order to reach average consensus. However, in a realistic scenario wireless communications are subject to interferences and other environmental factors, which results in random instantaneous topologies that are, in general, asymmetric. Consequently, the estimat…