2,777 research outputs found

    Exponential stabilization of neural networks with various activation functions and mixed time-varying delays

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    This paper presents some results on the global exponential stabilization for neural networks with various activation functions and time-varying continuously distributed delays. Based on augmented time-varying Lyapunov-Krasovskii functionals, new delay-dependent conditions for the global exponential stabilization are obtained in terms of linear matrix inequalities. A numerical example is given to illustrate the feasibility of our results

    Processing and Properties of Metal Matrix Composites

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    The study was conducted to investigate the general properties and processing methods of metal matrix composites in comparison with polymer matrix composites and ceramic matrix composites. In addition, the properties of the most widely used metal matrix composites (aluminum and magnesium) were also studied. The information was collected from published online articles and journals on metal matrix composites. From the study, I found out that while metal matrix composites have been widely used in the aerospace and automobile industry, their properties are still being researched for further development and applications

    Delay and reliability analysis of p-persistent carrier sense multiple access for multi-event industrial wireless sensor networks

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    In industrial environments various events can concurrently occur and may require different quality of service (QoS) provision based on different priority levels. To reduce the chances of collision and to improve efficiency in multi-event occurrence, Carrier Sense Multiple Access (CSMA) is a preferable choice for Medium Access Control (MAC) protocols. However, it also increases the overall delay. In this paper, a Priority MAC protocol for Multi-Event industrial wireless sensor networks (PMME) is proposed. In PMME, use of different p values/sequences is proposed to enable multi-priority operation, which can be optimized to suit different operational classes within industrial applications including emergency, regulatory control, supervisory control, open-loop control, alerting and monitoring systems. In this work, novel mathematical model as well as simulations are presented to validate the accuracy and performance of the proposed protocol. Mathematical analysis shows that the proposed PMME can prioritize data packets effectively while ensuring ultra-reliable and low latency communications for high priority nodes. Simulations in Castalia verify that PMME with different p values/sequences notably reduces packet delay for all four priority classes. The PMME also returns a high packet success rate compared to other two well-known priority enabled MAC protocols, QoS aware energy-efficient (QAEE) and multi-priority based QoS (MPQ), in multi-event industrial wireless sensor networks

    Saran Wrap Handling Device

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    A non-contact measurement system for the range of motion of the hand

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    An accurate and standardised tool to measure the active range of motion (ROM) of the hand is essential to any progressive assessment scenario in hand therapy practice. Goniometers are widely used in clinical settings for measuring the ROM of the hand. However, such measurements have limitations with regard to inter-rater and intra-rater reliability and involve direct physical contact with the hand, possibly increasing the risk of transmitting infections. The system proposed in this paper is the first non-contact measurement system utilising Intel Perceptual Technology and a Senz3D Camera for measuring phalangeal joint angles. To enhance the accuracy of the system, we developed a new approach to achieve the total active movement without measuring three joint angles individually. An equation between the actual spacial position and measurement value of the proximal inter-phalangeal joint was established through the measurement values of the total active movement, so that its actual position can be inferred. Verified by computer simulations, experimental results demonstrated a significant improvement in the calculation of the total active movement and successfully recovered the actual position of the proximal inter-phalangeal joint angles. A trial that was conducted to examine the clinical applicability of the system involving 40 healthy subjects confirmed the practicability and consistency in the proposed system. The time efficiency conveyed a stronger argument for this system to replace the current practice of using goniometers

    Characterization of the nitrogen split interstitial defect in wurtzite aluminum nitride using density functional theory

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    We carried out Heyd-Scuseria-Ernzerhof hybrid density functional theory plane wave supercell calculations in wurtzite aluminum nitride in order to characterize the geometry, formation energies, transition levels and hyperfine tensors of the nitrogen split interstitial defect. The calculated hyperfine tensors may provide useful fingerprint of this defect for electron paramagnetic resonance measurement.Comment: 5 pages, 3 figure

    Curvature suppresses the Rayleigh-Taylor instability

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    The dynamics of a thin liquid film on the underside of a curved cylindrical substrate is studied. The evolution of the liquid layer is investigated as the film thickness and the radius of curvature of the substrate are varied. A dimensionless parameter (a modified Bond number) that incorporates both geometric parameters, gravity, and surface tension is identified, and allows the observations to be classified according to three different flow regimes: stable films, films with transient growth of perturbations followed by decay, and unstable films. Experiments and theory confirm that, below a critical value of the Bond number, curvature of the substrate suppresses the Rayleigh-Taylor instability
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