249 research outputs found
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Dynamic Recofiguration Techniques for Wireless Sensor Networks
The need to achieve extended service life by battery powered Wireless Sensor Networks (WSNs) requires new concepts and technqiues beyond the state-of-the-art low-power designs based on fixed hardware platforms or energy-efficient protocols. This thesis investigates reconfiguration techniques that enable sensor hardware to adapt its energy consumption to external dynamics, by means of Dynamic Voltage Scaling (DVS), Dynamic Modulation Scaling (DMS), and other related concepts. For sensor node-level reconfiguration, an integration of DVS and DMS techniques was proposed to minimize the total energy consumption. A dynamic time allocation algorithm was developed, demonstrating an average of 55% energy reduction. For network-level reconfiguration, a node activation technique was presented to reduce the cost of recharging energy-depleted sensor nodes. Network operation combined with node activation was modeled as a stochastic decision process, where the activation decisions directly affected the energy efficiency of the network. An experimental test bed based on the Imote2 sensor node platform was realized, which demonstrated energy reduction of up to 50%. Such energy saving can be effectively translated into prolonged service life of the sensor network
Nondestructive Measurement Material Characterization of Thermal Sprayed Nickel Aluminum Coatings by using Laser Ultrasound Technique
AbstractThis research focused on characterization of mechanical properties in Nickel-Aluminum coating with different thermal technique and processing parameters at high temperature environment up to 295°C. With the laser ultrasound technique (LUT), guided acoustic waves are generated to propagate on the Ni-Al sprayed coatings. By measuring dispersive phase velocity followed by SCE-UA inversion algorithm. The Young's modulus of coatings which fabricated by HVOF technique is higher than APS technique. This technique is potentially useful to probe the material characterization at high temperature environment in a remote and non-destructive way
Exploring the value co-destruction model for on-line deviant behaviors of hotel customers
© 2019 Elsevier Ltd This study aims to build a value co-destruction model by exploring the online deviant behavior of hotel customers. Desire for revenge and desire for recovery are considered mediators. Hotel guests in notable Taiwan locations were surveyed via the Internet (no. = 601 valid responses). This study finds that negative emotion indirectly impacts negative electronic word of mouth (eWOM) with desire for revenge as a mediator. Furthermore, desire for recovery has the potential to mitigate the impact of negative emotion on negative eWOM. However, the desire for recovery is less intense than the desire for revenge. Based on these findings, this study concludes that emotion, by itself, does not result in action. Respondents only commit negative eWOM because they want to hurt the firm that wronged them. Respondents are also willing to entertain the idea of service recovery. However, desire for revenge is a stronger mediating factor
Perturbative Approach to Higher Derivative and Nonlocal Theories
We review a perturbative approach to deal with Lagrangians with higher or
infinite order time derivatives. It enables us to construct a consistent
Poisson structure and Hamiltonian with only first time derivatives order by
order in coupling. To the lowest order, the Hamiltonian is bounded from below
whenever the potential is. We consider spacetime noncommutative field theory as
an example.Comment: 19 pages, Latex, reference adde
A novel smart somatosensory wearable assistive device for older adults’ home rehabilitation during the COVID-19 pandemic
BackgroundDue to the Coronavirus disease 19 (COVID-19) related social distancing measures and health service suspension, physical activity has declined, leading to increased falling risk and disability, and consequently, compromising the older adult health. How to improve the quality of older adult life has become a crucial social issue.ObjectiveIn traditional rehabilitation, manual and repetitive muscle training cannot identify the patient’s rehabilitation effect, and increasing the willingness to use it is not easy. Therefore, based on the usability perspective, this study aims to develop a novel smart somatosensory wearable assistive device (called SSWAD) combined with wireless surface electromyography (sEMG) and exergame software and hardware technology. The older adult can do knee extension, ankle dorsiflexion, and ankle plantar flexion rehabilitation exercises at home. Meanwhile, sEMG values can be digitally recorded to assist physicians (or professionals) in judgment, treatment, or diagnosis.MethodsTo explore whether the novel SSWAD could improve the older adult willingness to use and motivation for home rehabilitation, 25 frail older adult (12 males and 13 females with an average age of 69.3) perform the rehabilitation program with the SSWAD, followed by completing the system usability scale (SUS) questionnaire and the semi-structured interview for the quantitative and qualitative analyses. In addition, we further investigate whether the factor of gender or prior rehabilitation experience would affect the home rehabilitation willingness or not.ResultsAccording to the overall SUS score, the novel SSWAD has good overall usability performance (77.70), meaning that the SSWAD makes older adult feel interested and improves their willingness for continuous rehabilitation at home. In addition, the individual item scores of SUS are shown that female older adult with prior rehabilitation experience perform better in “Learnability” (t = 2.35, p = 0.03) and “Confidence” (t = −3.24, p = 0.01). On the contrary, male older adult without rehabilitation experience are more willing to adopt new technologies (t = −2.73, p = 0.02), and perform better in “Learnability” (t = 2.18, p = 0.04) and “Confidence” (t = −3.75, p < 0.001) with the SSWAD. In addition, the result of the semi-structured interview shows that the operation of the SSWAD is highly flexible, thus reducing older adult burden during the rehabilitation exercise and using them long-term.ConclusionThis novel SSWAD receives consistently positive feedback regardless of the gender or prior rehabilitation experience of elders. The SSWAD could be used as a novel way of home rehabilitation for elders, especially during the COVID-19 pandemic. Older adult can do rehabilitation exercises at home, and physicians could make proper judgments or adjust suitable treatments online according to the sEMG data, which older adult can know their rehabilitation progress at the same time. Most importantly, older adult do not have to go to the hospital every time for rehabilitation, which significantly reduces time and the risk of infection
Serotonin receptor HTR6-mediated mTORC1 signaling regulates dietary restriction-induced memory enhancement
Dietary restriction (DR; sometimes called calorie restriction) has profound beneficial effects on physiological, psychological, and behavioral outcomes in animals and in humans. We have explored the molecular mechanism of DR-induced memory enhancement and demonstrate that dietary tryptophan-a precursor amino acid for serotonin biosynthesis in the brain-and serotonin receptor 5-hydroxytryptamine receptor 6 (HTR6) are crucial in mediating this process. We show that HTR6 inactivation diminishes DR-induced neurological alterations, including reduced dendritic complexity, increased spine density, and enhanced long-term potentiation (LTP) in hippocampal neurons. Moreover, we find that HTR6-mediated mechanistic target of rapamycin complex 1 (mTORC1) signaling is involved in DR-induced memory improvement. Our results suggest that the HTR6-mediated mTORC1 pathway may function as a nutrient sensor in hippocampal neurons to couple memory performance to dietary intake
Perturbative Approach to Higher Derivative Theories with Fermions
We extend the perturbative approach developed in an earlier work to deal with
Lagrangians which have arbitrary higher order time derivative terms for both
bosons and fermions. This approach enables us to find an effective Lagrangian
with only first time derivatives order by order in the coupling constant. As in
the pure bosonic case, to the first order, the quantized Hamiltonian is bounded
from below whenever the potential is. We show in the example of a single
complex fermion that higher derivative interactions result in an effective mass
and change of vacuum for the low energy modes. The supersymmetric
noncommutative Wess-Zumino model is considered as another example. We also
comment on the higher derivative terms in Witten's string field theory and the
effectiveness of level truncation.Comment: Latex, 21 pages, minor modification, ref. adde
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