43,453 research outputs found

    An efficient adaptive reconfigurable routing protocol for optimized data packet distribution in network on chips

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    The deadlock-free and live lock-free routing at the same time is minimized in the network on chip (NoC) using the proposed adoptive reconfigurable routing protocol (ARRP). Congestion condition emergencies are avoided using the proposed algorithm. The input packet distribution process is improved among all its shortest paths of output points. The performance analysis has been initiated by considering different configuration (N*N) mesh networks, by sending various ranges of data packets to the network on chip. The average and maximum power dissipation of XY, odd-even, Dy-XY algorithm, and proposed algorithm are determined. In this paper, an analysis of gate utilization during data packet transfer in various mesh configurations is carried out. The number of cycles required for each message injection in different mesh configurations is analyzed. The proposed routing algorithm is implemented and compared with conventional algorithms. The simulation has been carried out using reconfigurable two-dimensional mesh for the NoC. The proposed algorithm has been implemented considering array size, the routing operating frequency, link width length, value of probability, and traffic types. The proposed ARRP algorithm reduces the average latency, avoids routing congestion, and is more feasible for NoC compared to conventional methods

    The role of forebody topology on aerodynamics and aeroacoustics characteristics of squareback vehicles using Computational Aeroacoustics (CAA)

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    This study investigates the influence of forebody configuration on aerodynamic noise generation and radiation in standard squareback vehicles, employing a hybrid computational aeroacoustics approach. Initially, a widely used standard squareback body is employed to establish grid-independent solutions and validate the applied methodology against previously published experimental data. Six distinct configurations are examined, consisting of three bodies with A-pillars and three without A-pillars. Throughout these configurations, the reference area, length, and height remain consistent, while systematic alterations to the forebody are implemented. The findings reveal that changes in the forebody design exert a substantial influence on both the overall aerodynamics and aeroacoustics performance of the vehicle. Notably, bodies without A-pillars exhibit a significant reduction in downforce compared to their A-pillar counterparts. For all configurations, the flow characteristics around the side-view mirror and the side window exhibit an asymmetrical horseshoe vortex with high-intensity pressure fluctuations, primarily within the confines of this vortex and the mirror wake. Side windows on bodies with A-pillars experience more pronounced pressure fluctuations, rendering these configurations distinctly impactful in terms of radiated noise. However, despite forebody-induced variations in pressure fluctuations impacting the side window and side-view mirror, the fundamental structure of the radiated noise remains relatively consistent. The noise pattern transitions from a cardioid-like shape to a monopole-like pattern as the probing distance from the vehicle increases

    Processador de sinal digital para uma antena Inteligente para comunicações por satélite

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    In many places around the globe a reliable connection to the Internet or other forms of communication are not a reality. The launch of Mega Low Earth orbits (Mega- LEO) satellites seeks to mitigate this problem, in providing broadband connection anywhere in the world. However, in order to make this technology widespread, it is necessary to develop an intelligent antenna capable of establishing a high-quality connection with at least one satellite. The goal of this dissertation is to implement a digital signal processor which can be used by an intelligent antenna with beamforming capabilities. The development platform is a Xilinx ZCU208 RF-SoC FPGA where the first goal is to generate and capture signals synchronously, respectively with RF-DACs and RF-ADCs. Once the RF-DACs and RF-ADCs can be synchronized and configured at runtime, the system becomes capable of performing digital beamforming. In this dissertation, two beamforming techniques are presented and described, one based on phase shifting, and the other based on true time delay (TTD) lines. The performed tests show that the approach based on these two solutions can provide a combination of a coarse and a fine control of the signal phase, in which TTD enable coarse delay adjustment, and phase shift a fine tuning. The implemented TTD lines proved to be computationally light, as these require few resources of the FPGA and have the advantage of being able to provide long delays, which may be usefull in different scenarios. Phase shifting proved to be a fine method, as it is able to adapt the phase with better accuracy. This dissertation presents in detail the development and validation of such digital signal processor.Em muitos lugares do mundo, uma ligação fiável à Internet ou a outras formas de comunicação não são uma realidade. O lançamento de mega constelações de satélites de baixa órbita procura mitigar este problema, ao fornecer ligação de banda larga em qualquer parte do mundo. No entanto, a fim de generalizar esta tecnologia, é necessário desenvolver uma antena inteligente capaz de estabelecer uma ligação de alta qualidade com pelo menos um satélite. O objectivo desta dissertação é implementar um processador de sinal digital que possa ser utilizado por uma antena inteligente com capacidades de beamforming. A plataforma de desenvolvimento é uma Xilinx ZCU208 RF-SoC FPGA onde o primeiro objectivo é gerar e capturar sinal sincronamente, com RF-DACs e RF-ADCs. Uma vez que as RF-DACs e as RF-ADCs possam ser sincronizadas e configuradas em tempo de execução, o sistema torna-se capaz de realizar beamforming. Nesta dissertação, são apresentadas e descritas duas técnicas de beamforming, uma baseada na mudança de fase, e outra baseada em linhas de atraso temporal. Os testes realizados mostram que a abordagem baseada nestas duas soluções pode fornecer uma combinação de um desvio de fase grosseiro e um controlo fino da fase do sinal, em que as linhas de atraso temporal permitem um ajuste do atraso grosseiro, e o desvio de fase uma afinação fina. As linhas TTD True Time Delay implementadas provaram ser computacionalmente leves, uma vez que estas requerem poucos recursos da FPGA e têm a vantagem de poderem proporcionar longos atrasos, o que pode ser útil em diferentes cenários. O deslocamento de fase provou ser um método de ajuste fino, pois é capaz de adaptar a fase com maior precisão. Esta dissertação apresenta em detalhe o desenvolvimento e validação de um processador de sinal digital.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

    Low-Cost Wide-Angle Beam-Scanning Transmitarray Antennas Using Lens-Loaded Patch Elements: A Proof-of-Concept Study

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    © 2022 IEEE. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1109/LAWP.2022.3201030In this letter, a novel design concept to achieve a low-cost wide-angle beam-scanning transmitarray (TA) using lens-loaded patch (LLP) elements is presented. In this design, each TA element consists of a beam switchable transmitting element, a group of receiving elements, and a signal via. The received powers of a 2×2 subarray are first combined and then transmitted to the corresponding LLP element, where the phases of the transmitted signals are manipulated for beamforming. Compared with the conventional designs, the phase shifters (PSs) can be multiplexed and the number of PSs is effectively eliminated by 75%, which significantly decreases the hardware cost. By employing multiple patches as the feed of the lenses, reconfigurable radiation patterns are obtained, and by properly choosing the transmitting patches, the developed TA achieves a wide-angle two-dimensional beam scanning within ±60° with stable gains. To validate the design concept, passive prototypes with a center frequency of 12.5 GHz are simulated, fabricated, and tested. The measured results show that the aperture efficiency is 30.1%, 19.4%, and 14.1% for beams steered to 0°, 30°, and 60° at 12.5 GHz, respectively. The beam coverage of ±60° with a less than 3.5 dB scanning loss in the H-plane is obtained.Peer reviewe

    Wire detection using ground penetrating radar using image processing techniques

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    [EMBARGOED UNTIL 5/1/2024] This thesis investigates wire detection using various techniques applied to Ground Penetrating Radar (GPR) images. In this study, a step-frequency GPR with a co-pole configuration was used to collect data. The first approach proposes the use of Hough Transform (HT) to detect surface wires. The collected data is processed by beamforming and projecting onto the surface plane before applying HT. The features extracted for wire detection include orientation, strength, and relative strength. The second and third approaches propose an ellipse fitting technique to detect surface-laid and shallowly buried wires. After filtering and edge detection in the cross-section image, ellipse fitting is applied to obtain an ellipse feature for indicating how well the shape fits to an ellipse. The third approach improves the ellipse feature extraction method to obtain the feature regardless of the orientation of a wire. The method first applies HT to the surface projection of an object image from the GPR, and then rotates the 3-D data image according to the orientation angle from the HT to align with the cross-track, before the extraction of ellipse feature. The fourth approach proposes features for curved wire detection from GPR images. The processing involves projecting the 3-D GPR beamformed image onto the ground plane, applying the Canny edge detector to extract the edge points, and fitting the edge points to a parabola through a voting scheme. The features consist of the orientation angle, the fitted parabolic parameters, and the fitting confidence. The combination of these approaches offers a comprehensive framework for wire detection in GPR images, with potential applications in explosive detection.Includes bibliographical references

    An Ultrasound Matrix Transducer for High-Frame-Rate 3-D Intra-cardiac Echocardiography

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    Objective: Described here is the development of an ultrasound matrix transducer prototype for high-frame-rate 3-D intra-cardiac echocardiography. Methods: The matrix array consists of 16 × 18 lead zirconate titanate elements with a pitch of 160 µm × 160 µm built on top of an application-specific integrated circuit that generates transmission signals and digitizes the received signals. To reduce the number of cables in the catheter to a feasible number, we implement subarray beamforming and digitization in receive and use a combination of time-division multiplexing and pulse amplitude modulation data transmission, achieving an 18-fold reduction. The proposed imaging scheme employs seven fan-shaped diverging transmit beams operating at a pulse repetition frequency of 7.7 kHz to obtain a high frame rate. The performance of the prototype is characterized, and its functionality is fully verified. Results: The transducer exhibits a transmit efficiency of 28 Pa/V at 5 cm per element and a bandwidth of 60% in transmission. In receive, a dynamic range of 80 dB is measured with a minimum detectable pressure of 10 Pa per element. The element yield of the prototype is 98%, indicating the efficacy of the manufacturing process. The transducer is capable of imaging at a frame rate of up to 1000 volumes/s and is intended to cover a volume of 70° × 70° × 10 cm. Conclusion: These advanced imaging capabilities have the potential to support complex interventional procedures and enable full-volumetric flow, tissue, and electromechanical wave tracking in the heart.</p

    Reliable indoor optical wireless communication in the presence of fixed and random blockers

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    The advanced innovation of smartphones has led to the exponential growth of internet users which is expected to reach 71% of the global population by the end of 2027. This in turn has given rise to the demand for wireless data and internet devices that is capable of providing energy-efficient, reliable data transmission and high-speed wireless data services. Light-fidelity (LiFi), known as one of the optical wireless communication (OWC) technology is envisioned as a promising solution to accommodate these demands. However, the indoor LiFi channel is highly environment-dependent which can be influenced by several crucial factors (e.g., presence of people, furniture, random users' device orientation and the limited field of view (FOV) of optical receivers) which may contribute to the blockage of the line-of-sight (LOS) link. In this thesis, it is investigated whether deep learning (DL) techniques can effectively learn the distinct features of the indoor LiFi environment in order to provide superior performance compared to the conventional channel estimation techniques (e.g., minimum mean square error (MMSE) and least squares (LS)). This performance can be seen particularly when access to real-time channel state information (CSI) is restricted and is achieved with the cost of collecting large and meaningful data to train the DL neural networks and the training time which was conducted offline. Two DL-based schemes are designed for signal detection and resource allocation where it is shown that the proposed methods were able to offer close performance to the optimal conventional schemes and demonstrate substantial gain in terms of bit-error ratio (BER) and throughput especially in a more realistic or complex indoor environment. Performance analysis of LiFi networks under the influence of fixed and random blockers is essential and efficient solutions capable of diminishing the blockage effect is required. In this thesis, a CSI acquisition technique for a reconfigurable intelligent surface (RIS)-aided LiFi network is proposed to significantly reduce the dimension of the decision variables required for RIS beamforming. Furthermore, it is shown that several RIS attributes such as shape, size, height and distribution play important roles in increasing the network performance. Finally, the performance analysis for an RIS-aided realistic indoor LiFi network are presented. The proposed RIS configuration shows outstanding performances in reducing the network outage probability under the effect of blockages, random device orientation, limited receiver's FOV, furniture and user behavior. Establishing a LOS link that achieves uninterrupted wireless connectivity in a realistic indoor environment can be challenging. In this thesis, an analysis of link blockage is presented for an indoor LiFi system considering fixed and random blockers. In particular, novel analytical framework of the coverage probability for a single source and multi-source are derived. Using the proposed analytical framework, link blockages of the indoor LiFi network are carefully investigated and it is shown that the incorporation of multiple sources and RIS can significantly reduce the LOS coverage blockage probability in indoor LiFi systems

    Listening to your partner: serotonin increases male responsiveness to female vocal signals in mice

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    The context surrounding vocal communication can have a strong influence on how vocal signals are perceived. The serotonergic system is well-positioned for modulating the perception of communication signals according to context, because serotonergic neurons are responsive to social context, influence social behavior, and innervate auditory regions. Animals like lab mice can be excellent models for exploring how serotonin affects the primary neural systems involved in vocal perception, including within central auditory regions like the inferior colliculus (IC). Within the IC, serotonergic activity reflects not only the presence of a conspecific, but also the valence of a given social interaction. To assess whether serotonin can influence the perception of vocal signals in male mice, we manipulated serotonin systemically with an injection of its precursor 5-HTP, and locally in the IC with an infusion of fenfluramine, a serotonin reuptake blocker. Mice then participated in a behavioral assay in which males suppress their ultrasonic vocalizations (USVs) in response to the playback of female broadband vocalizations (BBVs), used in defensive aggression by females when interacting with males. Both 5-HTP and fenfluramine increased the suppression of USVs during BBV playback relative to controls. 5-HTP additionally decreased the baseline production of a specific type of USV and male investigation, but neither drug treatment strongly affected male digging or grooming. These findings show that serotonin modifies behavioral responses to vocal signals in mice, in part by acting in auditory brain regions, and suggest that mouse vocal behavior can serve as a useful model for exploring the mechanisms of context in human communication

    An efficient unused integrated circuits detection algorithm for parallel scan architecture

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    In recent days, many integrated circuits (ICs) are operated parallelly to increase switching operations in on-chip static random access memory (SRAM) array, due to more complex tasks and parallel operations being executed in many digital systems. Hence, it is important to efficiently identify the long-duration unused ICs in the on-chip SRAM memory array layout and to effectively distribute the task to unused ICs in SRAM memory array. In the present globalization, semiconductor supply chain detection of unused SRAM in large memory arrays is a very difficult task. This also results in reduced lifetime and more power dissipation. To overcome the above-mentioned drawbacks, an efficient unused integrated circuits detection algorithm (ICDA) for parallel scan architecture is proposed to differentiate the ‘0’ and ‘1’ in a larger SRAM memory array. The proposed architecture avoids the unbalancing of ‘0’ and ‘1’ concentrations in the on-chip SRAM memory array and also optimizes the area required for the memory array. As per simulation results, the proposed method is more efficient in terms of reliability, the detection rate in both used and unused ICs and reduction of power dissipation in comparison to conventional methods such as backscattering side-channel analysis (BSCA) and network attached storage (NAS) algorithm
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