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Thomas Heimburg
Onsager's phenomenological equations successfully describe irreversible thermodynamic processes. They assume a symmetric coupling matrix between thermodynamic fluxes and forces. It is easily shown that the antisymmetric part of a coupling matrix does not contribute to dissipation. Therefore, entropy production is exclusively governed by the symmetric matrix even in the presence of antisymmetric terms. In this paper we focus on the antisymmetric contributions which describe isentropic oscillations with well-defined equations of motion...
June 23, 2017: Physical Chemistry Chemical Physics: PCCP
Massimiliano Pau, Micaela Porta, Giancarlo Coghe, Federica Corona, Giuseppina Pilloni, Lorena Lorefice, Maria Giovanna Marrosu, Eleonora Cocco
BACKGROUND: In people with Multiple Sclerosis (pwMS), balance assessment is essential in estimating the risk of falls, monitoring disease progression and verifying the effectiveness of rehabilitative treatment. Clinical tools and instrumental techniques are available for testing static and dynamic balance, but the relationship between such abilities is still not clear. Having information about this link would be important in properly planning the type and number of tests to administer...
July 2017: Multiple Sclerosis and related Disorders
Torin K Clark, Laurence R Young
BACKGROUND: Increased gravito-inertial acceleration, or hypergravity, such as produced in a centrifuge or in an aircraft coordinated turn, causes humans to systematically overestimate their roll tilt in the dark. This is known as the "G-excess" illusion. We have previously modified a mathematical observer model of dynamic orientation perception to replicate these illusory tilt perceptions. This modified model also made a novel, previously untested, prediction that humans would underestimate acute roll tilt in reduced gravitational environments (hypogravity)...
July 1, 2017: Aerospace Medicine and Human Performance
Deepak G Skariah, Muthuvel Arigovindan
We develop a novel optimization algorithm, which we call Nested Non-Linear Conjugate Gradient algorithm (NNCG), for image restoration based on quadratic data fitting and smooth non-quadratic regularization. The algorithm is constructed as a nesting of two conjugate gradient (CG) iterations. The outer iteration is constructed as a preconditioned non-linear CG algorithm; the preconditioning is performed by the inner CG iteration that is linear. The inner CG iteration, which performs preconditioning for outer CG iteration, itself is accelerated by an another FFT based non-iterative preconditioner...
June 19, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Paul R MacNeilage, Stefan Glasauer
Achieved motor movement can be estimated using both sensory and motor signals. The value of motor signals for estimating movement should depend critically on the stereotypy or predictability of the resulting actions. As predictability increases, motor signals become more reliable indicators of achieved movement, so weight attributed to sensory signals should decrease accordingly. Here we describe a method to quantify this predictability for head movement during human locomotion by measuring head motion with an inertial measurement unit (IMU), and calculating the variance explained by the mean movement over one stride, i...
2017: Frontiers in Computational Neuroscience
Ryszard Zarzeczny, Agnieszka Nawrat-Szołtysik, Anna Polak, Jakub Maliszewski, Adam Kiełtyka, Beata Matyja, Magdalena Dudek, Joanna Zborowska, Adam Wajdman
Although the total "Timed-Up-and Go" test (TUG) performance time can characterize an age-related decline of general mobility, this result alone doesn't give any detailed information about the test subtasks. The primary objective of the study was to identify in nursing home women a variable extracted from instrumented TUG (iTUG) that is the best predictor of age. The secondary objective was to assess whether this variable is associated with the results of the isometric knee extension peak torque (IKEPT); lower limb strength measured by the 30-s chair stand test (30sCST), and walking capacity measured by the 6-min walk test (6MWT)...
June 20, 2017: Biogerontology
Nivedita Nivedita, Neha Garg, Abraham P Lee, Ian Papautsky
Numerous applications in biology and medicine require the efficient and reliable separation of cells for disease diagnosis, genetic analysis, drug screening, and therapeutics. In this work, we demonstrate a novel technology that integrates a passive and an active device to separate, enrich and release cells on-demand from a complex blood sample, or cancer cells derived from a tissue biopsy. We exploit the high throughput (>1 mL min(-1)), size-based sorting capability of the passive spiral inertial microfluidic (iMF) device to focus particles/cells towards an active lateral cavity acoustic transducer (LCAT) device for size-selective enrichment...
June 21, 2017: Analyst
Samira Shiri, James C Bird
The ability to enhance or limit heat transfer between a surface and impacting drops is important in applications ranging from industrial spray cooling to the thermal regulation of animals in cold rain. When these surfaces are micro/nanotextured and hydrophobic, or superhydrophobic, an impacting drop can spread and recoil over trapped air pockets so quickly that it can completely bounce off the surface. It is expected that this short contact time limits heat transfer; however, the amount of heat exchanged and precise role of various parameters, such as the drop size, are unknown...
June 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
Qingan Jiang, Wenqi Wu, Mingming Jiang, Yun Li
High-accuracy railway track surveying is essential for railway construction and maintenance. The traditional approaches based on total station equipment are not efficient enough since high precision surveying frequently needs static measurements. This paper proposes a new filtering and smoothing algorithm based on the IMU/odometer and landmarks integration for the railway track surveying. In order to overcome the difficulty of estimating too many error parameters with too few landmark observations, a new model with completely observable error states is established by combining error terms of the system...
June 19, 2017: Sensors
Qimin Xu, Xu Li, Ching-Yao Chan
In this paper, we propose a cost-effective localization solution for land vehicles, which can simultaneously adapt to the uncertain noise of inertial sensors and bridge Global Positioning System (GPS) outages. First, three Unscented Kalman filters (UKFs) with different noise covariances are introduced into the framework of Interacting Multiple Model (IMM) algorithm to form the proposed IMM-based UKF, termed as IMM-UKF. The IMM algorithm can provide a soft switching among the three UKFs and therefore adapt to different noise characteristics...
June 18, 2017: Sensors
Tao Zhang, Yongyun Zhu, Feng Zhou, Yaxiong Yan, Jinwu Tong
Initial alignment of the strapdown inertial navigation system (SINS) is intended to determine the initial attitude matrix in a short time with certain accuracy. The alignment accuracy of the quaternion filter algorithm is remarkable, but the convergence rate is slow. To solve this problem, this paper proposes an improved quaternion filter algorithm for faster initial alignment based on the error model of the quaternion filter algorithm. The improved quaternion filter algorithm constructs the K matrix based on the principle of optimal quaternion algorithm, and rebuilds the measurement model by containing acceleration and velocity errors to make the convergence rate faster...
June 17, 2017: Sensors
Jane H Burridge, Alan Chong W Lee, Ruth Turk, Maria Stokes, Jill Whitall, Ravi Vaidyanathan, Phil Clatworthy, Ann-Marie Hughes, Claire Meagher, Enrico Franco, Lucy Yardley
BACKGROUND AND PURPOSE: Stroke, predominantly a condition of older age, is a major cause of acquired disability in the global population and puts an increasing burden on health care resources. Clear evidence for the importance of intensity of therapy in optimizing functional outcomes is found in animal models, supported by neuroimaging and behavioral research, and strengthened by recent meta-analyses from multiple clinical trials. However, providing intensive therapy using conventional treatment paradigms is expensive and sometimes not feasible because of social and environmental factors...
July 2017: Journal of Neurologic Physical Therapy: JNPT
Li-Fong Lin, Yi-Jia Lin, Zi-Hao Lin, Li-Yun Chuang, Wei-Chun Hsu, Yuan-Hsiang Lin
BACKGROUND: Wearable devices based on inertial measurement units through wireless sensor networks have many applications such as real-time motion monitoring and functional outcome assessment of stroke rehabilitation. However, additional investigations are warranted to validate their clinical value, particularly in detecting the synergy patterns of movements after stroke. AIM: To explore the feasibility and efficacy of wearable devices for upper limb rehabilitation in patients with chronic stroke and to compare the intervention effects (e...
June 19, 2017: European Journal of Physical and Rehabilitation Medicine
Yanbin Gao, Meng Liu, Guangchun Li, Xingxing Guang
An accurate initial alignment must be required for inertial navigation system (INS). The performance of initial alignment directly affects the following navigation accuracy. However, the rapid convergence of meridians and the small horizontalcomponent of rotation of Earth make the traditional alignment methods ineffective in polar regions. In this paper, from the perspective of global inertial navigation, a novel alignment algorithm based on pseudo-Earth frame and backward process is proposed to implement the initial alignment in polar regions...
June 16, 2017: Sensors
Jian He, Shuang Bai, Xiaoyi Wang
Falls are one of the main health risks among the elderly. A fall detection system based on inertial sensors can automatically detect fall event and alert a caregiver for immediate assistance, so as to reduce injuries causing by falls. Nevertheless, most inertial sensor-based fall detection technologies have focused on the accuracy of detection while neglecting quantization noise caused by inertial sensor. In this paper, an activity model based on tri-axial acceleration and gyroscope is proposed, and the difference between activities of daily living (ADLs) and falls is analyzed...
June 16, 2017: Sensors
Carlos Ma, Michael Z Q Chen, James Lam, Kie Chung Cheung
In the common practice of designing an attitude tracker for an aerospacecraft, one transforms the Newton-Euler rotation equations to obtain the dynamic equations of some chosen inertial frame based attitude metrics, such as Euler angles and unit quaternions. A Lyapunov approach is then used to design a controller which ensures asymptotic convergence of the attitude to the desired orientation. Although this design methodology is pretty standard, it usually involves singularity-prone coordinate transformations which complicates the analysis process and controller design...
June 12, 2017: ISA Transactions
Milan Červenka, Michal Bednařík
Acoustic streaming in 2D rectangular resonant channels filled with a fluid with a spatial temperature distribution is studied within this work. An inertial force is assumed for driving the acoustic field; the temperature inhomogeneity is introduced by resonator walls with prescribed temperature distribution. The method of successive approximations is employed to derive linear equations for calculation of primary acoustic and time-averaged secondary fields including the streaming velocity. The model equations have a standard form which allows their numerical integration using a universal solver; in this case, COMSOL Multiphysics was employed...
June 2017: Journal of the Acoustical Society of America
I Sagert, W P Even, T T Strother
We perform two-dimensional implosion simulations using a Monte Carlo kinetic particle code. The application of a kinetic transport code is motivated, in part, by the occurrence of nonequilibrium effects in inertial confinement fusion capsule implosions, which cannot be fully captured by hydrodynamic simulations. Kinetic methods, on the other hand, are able to describe both continuum and rarefied flows. We perform simple two-dimensional disk implosion simulations using one-particle species and compare the results to simulations with the hydrodynamics code rage...
May 2017: Physical Review. E
Audun Skaugen, Luiza Angheluta
We establish a statistical relationship between the inverse energy cascade and the spatial correlations of clustered vortices in two-dimensional quantum turbulence. The Kolmogorov spectrum k^{-5/3} on inertial scales r corresponds to a pair correlation function between the vortices with different signs that decays as a power law with the pair distance given as r^{-4/3}. To test these scaling relations, we propose a forced and dissipative point vortex model that captures the turbulent dynamics of quantized vortices by the emergent clustering of same-sign vortices...
May 2017: Physical Review. E
E Jurčišinová, M Jurčišin
The influence of the uniaxial small-scale anisotropy on the kinematic magnetohydrodynamic turbulence is investigated by using the field theoretic renormalization group technique in the one-loop approximation of a perturbation theory. The infrared stable fixed point of the renormalization group equations, which drives the scaling properties of the model in the inertial range, is investigated as the function of the anisotropy parameters and it is shown that, at least at the one-loop level of approximation, the diffusion processes of the weak passive magnetic field in the anisotropically driven kinematic magnetohydrodynamic turbulence are completely equivalent to the corresponding diffusion processes of passively advected scalar fields in the anisotropic Navier-Stokes turbulent environments...
May 2017: Physical Review. E
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