Spiking neural networks (SNNs) are more energy- and resource-efficient than artificial neural networks (ANNs). However, supervised SNN learning is a challenging task due to non-differentiability of ...spikes and computation of complex terms. Moreover, the design of SNN learning engines is not an easy task due to limited hardware resources and tight energy constraints. In this article, a novel hardware-efficient SNN back-propagation scheme that offers fast convergence is proposed. The learning scheme does not require any complex operation such as error normalization and weight-threshold balancing, and can achieve an accuracy of around 97.5% on MNIST dataset using only 158,800 synapses. The multiplier-less inference engine trained using the proposed hard sigmoid SNN training (HaSiST) scheme can operate at a frequency of 135 MHz and consumes only 1.03 slice registers per synapse, 2.8 slice look-up tables, and can infer about 0.03Formula: see text features in a second, equivalent to 9.44 giga synaptic operations per second (GSOPS). The article also presents a high-speed, cost-efficient SNN training engine that consumes only 2.63 slice registers per synapse, 37.84 slice look-up tables per synapse, and can operate at a maximum computational frequency of around 50 MHz on a Virtex 6 FPGA.
Recent technical advancements in neural engineering allow for precise recording and control of neural circuits simultaneously, opening up new opportunities for closed-loop neural control. In this ...work, a rapid spike sorting system was developed based on template matching to rapidly calculate instantaneous firing rates for each neuron in a multi-unit extracellular recording setting. Cluster templates were first generated by a desktop computer using a non-parameter spike sorting algorithm (Super-paramagnetic clustering) and then transferred to a field-programmable gate array digital circuit for rapid sorting through template matching. Two different matching techniques-Euclidean distance (ED) and correlational matching (CM)-were compared for the accuracy of sorting and the performance of calculating firing rates. The performance of the system was first verified using publicly available artificial data and was further confirmed with pre-recorded neural spikes from an anesthetized Mongolian gerbil. Real-time recording and sorting from an awake mouse were also conducted to confirm the system performance in a typical behavioral neuroscience experimental setting. Experimental results indicated that high sorting accuracies were achieved for both template-matching methods, but CM can better handle spikes with non-Gaussian spike distributions, making it more robust for in vivo recording. The technique was also compared to several other off-line spike sorting algorithms and the results indicated that the sorting accuracy is comparable but sorting time is significantly shorter than these other techniques. A low sorting latency of under 2 ms and a maximum spike sorting rate of 941 spikes/second have been achieved with our hybrid hardware/software system. The low sorting latency and fast sorting rate allow future system developments of neural circuit modulation through analyzing neural activities in real-time.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A new temperature fiber ring laser (FRL) sensor based on a cascaded Sagnac loops fiber structure is proposed and experimentally demonstrated. The optical FRL sensor consists of cascaded Sagnac loops ...by inserting two polarization-maintaining optical fibers (PMF) with slightly different lengths. PMF with length of 56 cm and 75 cm are used in Sagnac loops as a filter and sensing unit in laser cavity. The working principle of the sensor is based on the phase shift (θ) caused by birefringence between two principal polarization modes and enhance the sensitivity by constructing a Vernier-scale. In an appropriate temperature range (25 °C - 31 °C), the detection sensitivity of FRL sensor based on a cascaded Sagnac structure is significantly higher than other FRL sensors. Thanks to the laser sensing system, the sensitivity can be modulated by changing the free spectral range (FSR). The experimental results show that the temperature sensitivity of the cascade Sagnac structure sensor is - 4.031 nm / °C, which is five times higher than that of FRL sensor base on the single Sagnac structure.
Intrabody communication (IBC) can achieve better power efficiency and higher levels of security than other traditional wireless communication technologies. Currently, the majority of research on the ...body channel characteristics of galvanic coupling IBC are motionless and have only been evaluated in the frequency domain. Given the long measuring times of traditional methods, the access to dynamic variations and the simultaneous evaluation of the time-frequency domain remains a challenge for dynamic body channels such as the cardiac channel. To address this challenge, we proposed a parallel measurement methodology with a multi-tone strategy and a time-parameter processing approach to obtain a time-frequency evaluation for dynamic body channels. A group search algorithm has been performed to optimize the crest factor of multitone excitation in the time domain. To validate the proposed methods, in vivo experiments, with both dynamic and motionless conditions were measured using the traditional method and the proposed method. The results indicate that the proposed method is more time efficient (
= 1 ms) with a consistent performance (
> 98%). Most importantly, it is capable of capturing dynamic variations in the body channel and provides a more comprehensive evaluation and richer information for the study of IBC.
We demonstrate a highly sensitive and practical fiber-based temperature sensor system. The sensor is constructed based on a fiber ring laser (FRL) as well as a side-polished fiber filled with ...isopropanol. The laser cavity of the sensing part fiber is polished by the wheel fiber polishing system with residual thickness (RT) is selected to detect the temperature in the FRL. Thanks to the high thermo-optic coefficient of isopropanol, the sensitivity of the proposed temperature sensor could be effectively improved by filling isopropanol in the cost-less side polished single mode fiber. Refractive index (RI) of isopropanol changes with the surrounding temperature variation allowing high-sensitivity temperature sensing. Experimental results demonstrate that the side polished fiber can efficiently excite high-order cladding modes which enhance the modular interference increase the interaction between the evanescent wave and the isopropanol. Besides, the results show that the sensitivity can be as high as 2 nm/°C in the temperature range of 25–35 °C.
Optical fiber sensors are of splendid strength for electrical field intensity sensor due to characteristics including the immunity to electromagnetic interference, lightweight, high sensitivity, and ...large bandwidth. In this paper, we proposed an electric field intensity sensor based on Mach-Zehnder interferometer (MZI) based liquid crystal (LC) filled photonic crystal fiber (PCF) embedded in optical fiber ring laser (FRL). The air hole of PCF combines the LC and fiber core together. When LC is introduced into air holes, it can maintain the waveguide based on external parameters. The photonic bandgap effect significantly improved the sensitivity between light and external electrical field intensity. Thanks to the FRL demodulation, a high signal to noise ratio (SNR) spectrum about 35 dB is obtained. Besides, in comparison with traditional LC-PCF structures, the sensitivity of ours is as high as 1.1 nm/Vrms which is about twice than traditional sensors. At the same time, the stability of proposed sensor was verified which fluctuation was 0.15 nm around 2.5 hours. Therefore, our structure is expected to practical applications in remote electric field monitor and such electric modulate electro-optical devices.
Spatial hearing allows animals to rapidly detect and localize auditory events in the surrounding environment. The auditory brainstem plays a central role in processing and extracting binaural spatial ...cues through microsecond-precise binaural integration, especially for detecting interaural time differences (ITDs) of low-frequency sounds at the medial superior olive (MSO). A series of mechanisms exist in the underlying neural circuits for preserving accurate action potential timing across multiple fibers, synapses and nuclei along this pathway. One of these is the myelination of afferent fibers that ensures reliable and temporally precise action potential propagation in the axon. There are several reports of fine-tuned myelination patterns in the MSO circuit, but how specifically myelination influences the precision of sound localization remains incompletely understood. Here we present a spiking neural network (SNN) model of the Mongolian gerbil auditory brainstem with myelinated axons to investigate whether different axon myelination thicknesses alter the sound localization process. Our model demonstrates that axon myelin thickness along the contralateral pathways can substantially modulate ITD detection. Furthermore, optimal ITD sensitivity is reached when the MSO receives contralateral inhibition via thicker myelinated axons compared to contralateral excitation, a result that is consistent with previously reported experimental observations. Our results suggest specific roles of axon myelination for extracting temporal dynamics in ITD decoding, especially in the pathway of the contralateral inhibition.
Muon detector for a Muon Collider Aimè, C.; Calzaferri, S.; Casarsa, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2023, Letnik:
1046
Journal Article
Recenzirano
A Muon Collider represents a promising possibility to combine the high energy and luminosity of hadron machines with very precise measurements of lepton colliders. The main challenges, that impact ...both the machine and detector design, arise from the short muon lifetime and the harsh Beam-induced Background (BIB).
Therefore, a full simulation is crucial to understand the feasibility of the experiment implementation. Focusing in particular on the muon system, a preliminary simulation of sensitivity and hit rate reveals that the technology inherited from CLIC, i.e. glass Resistive Plate Chambers, is already at the limit of its rate capability. Thus, alternative MicroPattern Gaseous Detector solutions are under investigation to try to match the required performance. In parallel, studies of muon reconstruction are ongoing.
Results of the muon reconstruction efficiency and BIB sensitivity are presented for multimuon final state processes at a centre-of-mass energy of 1.5TeV. Besides, PICOSEC technology, based on a Micromegas detector coupled to a Cherenkov radiator and equipped with a photocathode, is discussed.
We demonstrate a new concept for an all-fiber inclinometer based on a tapered fiber Bragg grating (tFBG) in a fiber ring laser (FRL) with the capability of measuring the tilt angle and temperature ...simultaneously. The sensor performance is analyzed theoretically and investigated experimentally. The dependence of tilt angle on the spectral response in variable temperature conditions was measured. Two inclinometers with different lengths have been fabricated and characterized in FRL. The sensitivity is 0.583 dB/° and 0.849 dB/°, respectively, in the range of 0° to 90°. Thanks to the FRL system, narrow 3-dB bandwidth (<0.1 nm) and high optical signal-to-noise ratio (~60 dB) are achieved. The tFBG in the FRL system can be used for working as a temperature insensitive inclinometer. The results suggested that the proposed inclinometer has the advantages of compact size and convenient manufacture, enhancing its potential for application prospect.
An optical fiber temperature sensor based on Mach–Zehnder interferometer and thermo-optic effect of the liquid crystal (LC) in fiber ring laser (FRL) system is proposed and experimentally ...demonstrated. The LC is infiltrated into the core of hollow core fiber, and the resonant wavelength is more sensitive to temperature variation due to the interaction between the incident light and the cavity infiltrating liquid crystal with high thermal light coefficient. Meanwhile, the FRL system was further used to make the sensor have good performance in the case of high signal-to-noise ratio (∼35 dB), narrow half-height width (FWHM = 0.15 nm), and high sensitivity in the temperature range from 20 °C to 50 °C, with the maximum sensitivity of 1.318 nm/°C. As far as we know, in the FRL system, the liquid crystal material has a better temperature sensing performance than the previous fiber. Nevertheless, the system has the advantages of good repeatability, low cost, simple production, small volume, high sensitivity. In marine microbial culture and detection, it is necessary to carry out high sensitivity measurement within a small temperature variation range. This reliable and excellent temperature performance has a potential application prospect.
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