Efficient Coxian duration modelling for activity recognition in smart environment with the hidden semi-Markov model

In this paper, we exploit the discrete Coxian distribution and propose a novel form of stochastic model, termed as the Coxian hidden semi-Makov model (Cox-HSMM), and apply it to the task of recognising activities of daily living (ADLs) in a smart house environment. The use of the Coxian has several advantages over traditional parameterization (e.g. multinomial or continuous distributions) including the low number of free parameters needed, its computational efficiency, and the existing of closed-form solution. To further enrich the model in real-world applications, we also address the problem of handling missing observation for the proposed Cox-HSMM. In the domain of ADLs, we emphasize the importance of the duration information and model it via the Cox-HSMM. Our experimental results have shown the superiority of the Cox-HSMM in all cases when compared with the standard HMM. Our results have further shown that outstanding recognition accuracy can be achieved with relatively low number of phases required in the Coxian, thus making the Cox-HSMM particularly suitable in recognizing ADLs whose movement trajectories are typically very long in nature.<br /

Analysis of Alfven eigenmodes destabilization by energetic particles in TJ-II using a Landau-closure model

Alfven Eigenmodes (AE) can be destabilized by energetic particles in neutral beam injection (NBI) heated plasmas through inverse Landau damping and couplings with gap modes in the shear Alfven continua. We describe the linear evolution of the poloidal flux and the toroidal component of the vorticity in a full 3D system using the reduced MHD equations, density and parallel velocity moments for the energetic particles as well as the geodesic acoustic wave dynamics. A closure relation adds the Landau damping and resonant destabilization effects in the model. We apply the model to study the Alfven modes stability in TJ-II, performing a parametric analysis in a range of realistic values of energetic particle beta (beta(f)), ratios of thermal/Alfven velocities (V-th/V-A0), energetic particle density profiles and toroidal modes (n) including toroidal and helical couplings. The study predicts a large helical coupling between different toroidal modes and the destabilization of helical Alfven eigenmodes (HAE) with frequencies similar to the AE activity measured in TJ-II, between 50-400 kHz. The analysis has also revealed the destabilization of GAE (global Alfven eigenmodes), TAE (toroidal Alfven eigenmodes) and EPM (energetic particle modes). For the modes considered here, optimized TJ-II operations require a t profile in the range of [0.845, 0.979] to stabilize AEs in the inner and middle plasma. AEs in the plasma periphery cannot be fully stabilized, although for a configuration with t = [0.945, 1.079], only n = 7, 11, 15 AE are unstable with a growth rate 4 times smaller compared to the standard t = [1.54, 1.68] case and a frequency of 100 kHz. We reproduce the frequency sweeping evolution of the AE frequency observed in TJ-II as the t profile is varied. The AE frequency sweeping is caused by consecutive changes of the instability dominant modes between different helical families.This material based on work is supported both by the U.S. Department of Energy, Office of Science, under Contract DE-AC05-00OR22725 with UT-Battelle, LLC. This research was sponsored in part by the Ministerio of Economia y Competitividad of Spain under project no. ENE2015-68265-P. We also want to acknowledge Alexander Melnikov and the TJ-II group at CIEMAT for providing us the initial VMEC equilibria and useful discussions regarding the experimental phenomena

Assessing the Test-Retest repeatability of the Vietnamese Version of the Natioal Eye Institute 25-Item Visual Function Questionnaire Among Bilateral Cataract Patients For a Vietnamese Population

Aim: To determine the test–retest repeatability of the National Eye Institute 25-item Visual Function Questionnaire (NEI VFQ-25) for use with older Vietnamese adults with bilateral cataract. Methods: The questionnaire was translated into Vietnamese and back-translated into English by two independent translators. Patients with bilateral cataract aged 50 and older completed the questionnaire on two separate occasions, one to two weeks after first administration of the questionnaire. Test–retest repeatability was assessed using the Cronbach's α and intraclass correlation coefficients. Results: The average age of participants was 67 ± 8 years and most participants were female (73%). Internal consistency was acceptable with the α coefficient above 0.7 for all subscales and intraclass correlation coefficients were 0.6 or greater in all subscales. Conclusion: The Vietnamese NEI VFQ-25 is reliable for use in studies assessing vision-related quality of life in older adults with bilateral cataract in Vietnam. We propose some modifications to the NEI-VFQ questions to reflect activities of older people in Vietnam

Two papers on Lyapunov exponents

SIGLETIB: RA 6154 (139) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman