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51.
This paper investigates the influence of uncertainties in geometrical coordinates on calculated torso and epicardial potentials. Two types of sources, spherical epicardial and multipolar, are both considered. A concentric sphere model with the epicardial surface represented by a unit sphere and the torso surface represented by a spherical surface of radius 1.4 is utilized. While the representation of biological surfaces with spheres is a highly idealized situation, the dimensions chosen and the approximations utilized are such that the results should be indicative of those using measured biological coordinates. 相似文献
52.
The T-stress term of DCDC specimens is computed using the Boundary Collocation procedure and limit case consideratons. This parameter allows to understand path stability as found in literature for subcritical crack growth in galss. 相似文献
53.
54.
Pavan TZ Almeida TW Carneiro AA 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(5):909-915
The dynamic behavior of a rigid magnetic sphere induced by an acoustic radiation force was investigated. The sphere was suspended in water in a simple pendulum configuration. The drag force acting on the pendulum during its motion was considered to follow a modified Stokes law for a low Reynolds number, accounting for phenomena related to its oscillatory movement. Steady forces of long (a few seconds) and short (a few milliseconds) durations were used. The movement of the magnetic sphere was tracked using a magnetoresistive sensor. From the new equilibrium position of the sphere in response to the long-duration static radiation force, the amplitude of this force was estimated. To assess the water viscosity, the relaxation movement after the acoustic force had stopped was fitted to a harmonic-motion model. Based on the results for the acoustic force and water viscosity, a theoretical profile of the sphere's micro-order displacement as a function of time caused by short-duration acoustic radiation force agreed well with experimental results. 相似文献
56.
Om Prakash Singh Andrea Bocchino Theo Guillerm Yuan Hu Frank Stam Conor O'Mahony 《Advanced Materials Technologies》2024,9(3):2301606
Microneedle-based electrodes have attracted significant attention due to their potential applications in high-quality, long-term electrophysiological monitoring. In this study, micromoulding technology is used to develop a flexible, conductive fabric microneedle (CF–MN) electrode by bonding a conductive textile to polymeric microneedle arrays. The resulting electrode conforms to the curved surfaces of the body, and the use of a conductive textile backing reduces metallization time and costs by 50% over double-sided dry electrodes. The electrode-skin impedance of the CF–MN electrodes is significantly lower than that of gel electrodes over a wide frequency range, and tests on healthy volunteers, both at rest and under a range of ambulatory conditions, showed that the electrodes are capable of acquiring electrocardiography (ECG) and electromyography (EMG) signals that have a comparable kurtosis and signal-to-noise ratio to those recorded using conventional electrodes, but without the need for skin preparation or the use of a wet gel. The biomechanical properties of the electrode are also characterized. This is the first demonstration of CF–MN electrodes that can ultimately be integrated into clothing, which in turn can facilitate personalized cardiac health management by enabling continuous, long-term ECG/EMG monitoring during daily activities. 相似文献
57.
Elizaveta Semenova Yidan Xu Adam Howes Theo Rashid Samir Bhatt Swapnil Mishra Seth Flaxman 《Journal of the Royal Society Interface》2022,19(191)
Gaussian processes (GPs), implemented through multivariate Gaussian distributions for a finite collection of data, are the most popular approach in small-area spatial statistical modelling. In this context, they are used to encode correlation structures over space and can generalize well in interpolation tasks. Despite their flexibility, off-the-shelf GPs present serious computational challenges which limit their scalability and practical usefulness in applied settings. Here, we propose a novel, deep generative modelling approach to tackle this challenge, termed PriorVAE: for a particular spatial setting, we approximate a class of GP priors through prior sampling and subsequent fitting of a variational autoencoder (VAE). Given a trained VAE, the resultant decoder allows spatial inference to become incredibly efficient due to the low dimensional, independently distributed latent Gaussian space representation of the VAE. Once trained, inference using the VAE decoder replaces the GP within a Bayesian sampling framework. This approach provides tractable and easy-to-implement means of approximately encoding spatial priors and facilitates efficient statistical inference. We demonstrate the utility of our VAE two-stage approach on Bayesian, small-area estimation tasks. 相似文献
58.
Chunliang Li Theo Veldhuis Bart Reuvers Rafaël J Sablong Cor E Koning 《Polymer International》2020,69(1):24-30
Limonene‐derived polycarbonate‐based alkyd resins (ARs) have been prepared by copolymerization of limonene dioxide with CO2, catalysed by a β‐diiminate zinc–bis(trimethylsilyl)amido complex, and subsequent chemical modification with soybean oil fatty acids using triphenylethylphosphonium bromide as the catalyst. This quantitative partial modification was realized via epoxy–carboxylic acid chemistry, affording ARs with higher oil lengths, lower polydispersities and higher glass transition temperatures (Tg) in comparison to a conventional polyester AR based on phthalic acid, multifunctional polyol pentaerythritol and soybean fatty acid. The novel limonene polycarbonate AR and the conventional polyester AR were evaluated as coatings and both the physical drying (without the presence of the oxidative drying accelerator Borchi® Oxy Coat) and chemical curing (with Borchi® Oxy Coat) processes of these coatings were monitored by measuring the König hardness and complex modulus development with time. A better performance was obtained for the alkyd paint containing polycarbonates modified with fatty acids (FA‐PCs), which showed a faster chemical drying, a higher König hardness and a higher Tg in coating evaluation, demonstrating that the fully renewable FA‐PCs are promising resins for alkyd paint applications. © 2019 Society of Chemical Industry 相似文献
59.
Peter Weiss Makthoum Peer Mohamed Thibaud Gobert Yann Chouard Nisheet Singh Theo Chalal Sibylle Schmied Matthias Schweins Thomas Stegmaier Gtz T. Gresser Gernot Groemer Nina Sejkora Shumit Das Riccardo Rampini Ma&#x;gorzata Ho&#x;y&#x;ska 《Advanced Materials Technologies》2020,5(9)
This review focuses on advanced materials already used and suitable for application in (future) lunar extravehicular activity space suits. A historical and current literature/market survey is presented. Different functional layers of an astronaut garment are defined with emphasis on the external layers subjected to abrasive action of lunar regolith and degradation via exposure to space radiation/vacuum environment. Requirements are defined that would need to be fulfilled by these layers and suitable materials candidates are reviewed based on their key properties, including mechanical durability. Smart materials, combining additional functionalities, such as garment health monitoring, are also considered. The lead topic is the subject of an ongoing ESA‐funded research activity. 相似文献
60.
Guenthner Christian Peereboom Sophie Marie Dillinger Hannes McGrath Charles Albannay Mohammed Masoud Vishnevskiy Valery Fuetterer Max Luechinger Roger Jenneskens Theo Sturzenegger Urs Overweg Johan Koken Peter Börnert Peter Kozerke Sebastian 《Magma (New York, N.Y.)》2023,36(3):355-373
Object
Lower-field MR is reemerging as a viable, potentially cost-effective alternative to high-field MR, thanks to advances in hardware, sequence design, and reconstruction over the past decades. Evaluation of lower field strengths, however, is limited by the availability of lower-field systems on the market and their considerable procurement costs. In this work, we demonstrate a low-cost, temporary alternative to purchasing a dedicated lower-field MR system.
Materials and MethodsBy ramping down an existing clinical 3 T MRI system to 0.75 T, proton signals can be acquired using repurposed 13C transmit/receive hardware and the multi-nuclei spectrometer interface. We describe the ramp-down procedure and necessary software and hardware changes to the system.
ResultsApart from presenting system characterization results, we show in vivo examples of cardiac cine imaging, abdominal two- and three-point Dixon-type water/fat separation, water/fat-separated MR Fingerprinting, and point-resolved spectroscopy. In addition, the ramp-down approach allows unique comparisons of, e.g., gradient fidelity of the same MR system operated at different field strengths using the same receive chain, gradient coils, and amplifiers.
DiscussionRamping down an existing MR system may be seen as a viable alternative for lower-field MR research in groups that already own multi-nuclei hardware and can also serve as a testing platform for custom-made multi-nuclei transmit/receive coils.
相似文献