Controlled sound interference has been extensively investigated using a prototype dual layer loudspeaker array comprised of 16 loudspeakers. Results are presented for measures of array performance such as input signal power, directivity of sound radiation and accuracy of sound reproduction resulting from the application of conventional control methods such as minimization of error in mean squared pressure, maximization of energy difference and minimization of weighted pressure error and energy. Procedures for selecting the tuning parameters have also been introduced. With these conventional concepts aimed at the production of acoustically bright and dark zones, all the control methods used require a tradeoff between radiation directivity and reproduction accuracy in the bright zone. An alternative solution is proposed which can achieve better performance based on the measures presented simultaneously by inserting a low priority zone named as the -gray‖ zone. This involves the weighted minimization of mean-squared errors in both bright and dark zones together with the gray zone in which the minimization error is given less importance. This results in the production of directional bright zone in which the accuracy of sound reproduction is maintained with less required input power. The results of simulations and experiments are shown to be in excellent agreement.
Objective. To explore how lifestyle and demographic, socioeconomic, and disease-related factors are associated with supervised exercise adherence in an osteoarthritis (OA) management program and the ability of these factors to explain exercise adherence.Methods. A cohort register-based study on participants from the Swedish Osteoarthritis Registry who attended the exercise part of a nationwide Swedish OA management program. We ran a multinomial logistic regression to determine the association of exercise adherence with the abovementioned factors. We calculated their ability to explain exercise adherence with the McFadden R 2 .Results. Our sample comprises 19,750 participants (73% female, mean ± SD age 67 ± 8.9 years). Among them, 5,862 (30%) reached a low level of adherence, 3,947 (20%) a medium level, and 9,941 (50%) a high level. After a listwise deletion, the analysis was run on 16,685 participants (85%), with low levels of adherence as the reference category. Some factors were positively associated with high levels of adherence, such as older age (relative risk ratio [RRR] 1.01 [95% confidence interval (95% CI) 1.01-1.02] per year), and the arthritis-specific self-efficacy (RRR 1.04 [95% CI 1.02-1.07] per 10-point increase). Others were negatively associated with high levels of adherence, such as female sex (RRR 0.82 [95% CI 0.75-0.89]), having a medium (RRR 0.89 [95% CI 0.81-0.98] or a high level of education ). Nevertheless, the investigating factors could explain 1% of the variability in exercise adherence (R 2 = 0.012).Conclusion. Despite the associations reported above, the poorly explained variability suggests that strategies based on lifestyle and demographic, socioeconomic, and disease-related factors are unlikely to improve exercise adherence significantly.
With unmanned aerial vehicles emerging as potential alternatives for people and cargo transport, their noise impact will be a determining factor in their acceptance by the general public. Contra-rotating propeller configurations are often explored due to their improved aerodynamic performance and redundancy in case of failure compared to conventional single-propeller aircraft, but can be much noisier than their single-propeller equivalent. This work describes the optimization of a custom-made contra-rotating propeller rig for reduced psychoacoustic impact. The rig consists of two electric motors mounted on a rotating stand, positioned inside an anechoic chamber. A far-field microphone arc is used to collect acoustic pressure data, and a load cell is used to measure total thrust. The axial distance between the propellers is varied between 0.1 and 1 rotor diameters, and the number of blades is varied between 2 and 6 on both propellers. Meanwhile, the rpm is adjusted to maintain constant thrust across the different configurations. Acoustic pressure signals are investigated in terms of their physical acoustic characteristics and psychoacoustic features (such as Loudness, Sharpness, Tonality, Fluctuation Strength, Roughness and Impulsiveness) in order to determine the trade-offs and optimal choices in reducing the psychoacoustic impact of the rig.
Neuropathic pain is characterized to arise without stimulation of nociceptors, but due to injury or dysfunction of Peripheral and Central Nervous Systems. It involves altered mechanisms of impulse transmission in somatosensory pathways, causing abnormal sensations. Quantitative sensory testing, by the detection of thermal stimuli, is a method used to characterize and study the neuropathic pain. Therefore, this work describes the development and application of portable custom built device for cutaneous thermal sensitivity assessment in spinal cord injured subjects (SCIS). Using method of levels, the assessment was applied in healthy subjects and SCIS with and without neuropathic pain. The thresholds determined for healthy subjects during thermal sensitivity assessment are consistent and other results provided by clinical trials are according to previous works, demonstrating the device feasibility as an auxiliary tool for neuropathic pain study.
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