Search results for "Memory."
showing 10 items of 1949 documents
Hardware-accelerated spike train generation for neuromorphic image and video processing
2014
Recent studies concerning Spiking Neural Networks show that they are a powerful tool for multiple applications as pattern recognition, image tracking, and detection tasks. The basic functional properties of SNN reside in the use of spike information encoding as the neurons are specifically designed and trained using spike trains. We present a novel and efficient frequency encoding algorithm with Gabor-like receptive fields using probabilistic methods and targeted to FPGA for online pro-cessing. The proposed encoding is versatile, modular and, when applied to images, it is able to perform simple image transforms as edge detection, spot detection or removal, and Gabor-like filtering without a…
Fast spiking neural network architecture for low-cost FPGA devices
2012
Spiking Neural Networks (SNN) consist of fully interconnected computation units (neurons) based on spike processing. This type of networks resembles those found in biological systems studied by neuroscientists. This paper shows a hardware implementation for SNN. First, SNN require the inputs to be spikes, being necessary a conversion system (encoding) from digital values into spikes. For travelling spikes, each neuron interconnection is characterized by weights and delays, requiring an internal neuron processing by a Postsynaptic Potential (PSP) function and membrane potential threshold evaluation for a postsynaptic output spike generation. In order to model a real biological system by arti…
Frequency spike encoding using Gabor-like receptive fields
2014
Abstract Spiking Neural Networks (SNN) are a popular field of study. For a proper development of SNN algorithms and applications, special encoding methods are required. Signal encoding is the first step since signals need to be converted into spike trains as the primary input to an SNN. We present an efficient frequency encoding system using receptive fields. The proposed encoding is versatile and it can provide simple image transforms like edge detection, spot detection or removal, or Gabor-like filtering. The proposed encoding can be used in many application areas as image processing and signal processing for detection and classification.
Do coaching style and game circumstances predict athletes' perceived justice of their coach? A longitudinal study in elite handball and volleyball te…
2018
Objective: The present longitudinal study is the first to examine game to game fluctuations of perceived justice of elite volleyball and handball coaches. More specifically, we studied whether coaching style (i.e., need support versus control), coach behaviors (decision justifications), player’s status (i.e., starter or substitute), and game result (win/loss) predicted athletes’ perceived justice and its fluctuations. Methods: A longitudinal questionnaire study was performed during 6 consecutive weeks among Belgian female volleyball (N = 57) and male handball players (N = 39). We administered a general questionnaire (i.e., need support/control) the first week, and game-specific questionnair…
The shifting evocations of squadrismo: remembering the massacre of Palazzo d'Accursio in Fascist Bologna
2016
The massacre of Palazzo d’Accursio is considered one of the first events in the rise of the Fascist squads. This article analyzes the ways in which the event was described in Bologna during the twenty years that followed it. It is believed that in the first few years, commemorations that emphasized the role of the Fascist squads were not very common. Instead, they concentrated on the life of Giulio Giordani, a murdered lawyer and opposition councilor, who became a martyr. Members of the city’s ruling class, especially lawyers, developed their own rituals of commemoration, but the establishment of the regime led to the acquisition of the commemorations of Giordani by Fascism, reflecting the …
Magnetic domain-wall racetrack memory for high density and fast data storage
2012
The racetrack memory device is a new concept of Magnetic RAM (MRAM) based on controlling domain wall (DW) motion in ferromagnetic nanowires. It promises ultra-high storage density thanks to the possibility to store multiple narrow DWS per memory cell. By using read and write heads based on magnetic tunnel junctions (MTJ) with perpendicular magnetic anisotropy (PMA) fast data access speed can also be achieved. Thereby the racetrack memory can be used as universal storage to address both embedded and standalone applications. In this paper, we present the device physics, integration circuit and architecture designs of a racetrack memory based on MTJs with PMA. Mixed SPICE simulations at 65 nm …
Lone Star Stack: Architecture of a Disk-Based Archival System
2014
The need for huge storage systems rises with the ever growing creation of data. With growing capacities and shrinking prices, "write once read sometimes" workloads become more common. New data is constantly added, rarely updated or deleted, and every stored byte might be read at any time - a common pattern for digital archives or big data scenarios. We present the Lone Star Stack, a disk based archival storage system building block that is optimized for high reliability and energy efficiency. It provides a POSIX file system interface that uses flash based storage for write-offloading and metadata and the disk-based Lone Star RAID for user data storage. The RAID attempts to spin down disks a…
LoneStar RAID
2016
The need for huge storage archives rises with the ever growing creation of data. With today’s big data and data analytics applications, some of these huge archives become active in the sense that all stored data can be accessed at any time. Running and evolving these archives is a constant tradeoff between performance, capacity, and price. We present the LoneStar RAID, a disk-based storage architecture, which focuses on high reliability, low energy consumption, and cheap reads. It is designed for MAID systems with up to hundreds of disk drives per server and is optimized for “write once, read sometimes” workloads. We use dedicated data and parity disks, and export the data disks as individu…
Variable Length Memory Chains: Characterization of stationary probability measures
2021
Variable Length Memory Chains (VLMC), which are generalizations of finite order Markov chains, turn out to be an essential tool to modelize random sequences in many domains, as well as an interesting object in contemporary probability theory. The question of the existence of stationary probability measures leads us to introduce a key combinatorial structure for words produced by a VLMC: the Longest Internal Suffix. This notion allows us to state a necessary and sufficient condition for a general VLMC to admit a unique invariant probability measure. This condition turns out to get a much simpler form for a subclass of VLMC: the stable VLMC. This natural subclass, unlike the general case, enj…
Non-Markovianity and memory of the initial state
2017
We explore in a rigorous manner the intuitive connection between the non-Markovianity of the evolution of an open quantum system and the performance of the system as a quantum memory. Using the paradigmatic case of a two-level open quantum system coupled to a bosonic bath, we compute the recovery fidelity, which measures the best possible performance of the system to store a qubit of information. We deduce that this quantity is connected, but not uniquely determined, by the non-Markovianity, for which we adopt the BLP measure proposed in \cite{breuer2009}. We illustrate our findings with explicit calculations for the case of a structured environment.