Many environmental sounds contain significant energy in the infrasonic and low-frequency (ISLF) ranges that have been associated with cases of annoyance and noise complaints. This study assessed the effect of sound duration on audibility and loudness of ISLF sounds. A first experiment evaluated detection thresholds for tones of 4, 16, and 32 Hz with durations up to 4000 ms. Furthermore, equal-loudness-level contours (ELCs) were obtained as function of duration up to 2000 ms. Tones of 1000 Hz were also included here. Results displayed the known pattern of general sound level decrease with increasing duration up to several hundred milliseconds. ELCs stabilized slightly earlier than thresholds, but after 1000 ms, levels remained roughly constant for both measures except for 4-Hz tones, where the decrease continued up to the longest durations tested. As 4-Hz cycles are perceptually resolved as separate pressure pulses, the authors hypothesized their duration dependence would resemble that of pulse trains. Hence, a second experiment evaluated pulse-train thresholds (1000-Hz carrier) for durations up to 4000 ms. For both pulse repetition rates of 4 and 32 Hz, threshold stabilized after 1000 ms as for tones ≥16 Hz, suggesting the continuing threshold decrease for a 4-Hz tone is specific to infrasound.
This paper concerns with the non-linear system having multiple-inputs multiple-outputs (MIMO). The plant mainly comprises: bench-top helicopter, tail and main rotor of a helicopter system. The dynamics are presented with control methodologies where a conventional strategy proves the instability of the system while the deadbeat and sliding mode control with linear matrix inequality regulates the future estimates. There have been disturbances like presence of unwanted ripples in the output of the non-linear systems (in case of stability also after 100[Formula: see text]s) and in the tracking of states accurately by updating the minimization error regularly. These problems originate mainly from the rotor section and are visited carefully by studying the dynamics of the blade, whereas, the design of filter makes the solution more appealing. The adaptive filter is capable of handling the frequency spectra of noise (reducing noise by 10[Formula: see text]dB), Euler angle deviations and travel angle accurately. Also, the stability analysis does not confirm the behavior in the case of bounded and a varying range of initial angular velocity. Hence, the problem of fluctuations is overcome by deadbeat and SMC-LMI approach which not only improved the ripples but also allowed the final response of the future states to be more exact and noiseless. As the previous research involved in position tracking (either translational or rotational) of these MIMO systems was concerned with software tools like MATLAB. This paper justifies its validation tested experimentally on OPAL RT hardware. The key findings involve the comparison of frequency spectra, the Euler deviation plot compared to CSL Helicopter and the three set-point variations providing accuracy in results in four modes — desired, actual, with controller-without filter and with controller-with filter. The use of adaptive filter with controllers have encouraged the suppression of noisy waveforms in the bench-top system very smoothly. The details regarding hardware setup are also discussed.
Anesthetic agent propofol needs to be administered at an appropriate rate to prevent hypotension and postoperative adverse reactions. To comprehend more suitable anesthetic drug rate during surgery is a crucial aspect. The main objective of this proposal is to design robust automated control system that work efficiently in most of the patients with smooth BIS and minimum variations of propofol during surgery to avoid adverse post reactions and instability of anesthetic parameters. And also, to design advanced computer control system that improves the health of patient with short recovery time and less clinical expenditures. Unlike existing research work, this system administrates propofol as a hypnotic drug to regulate BIS, with fast bolus infusion in induction phase and slow continuous infusion in maintenance phase of anesthesia. The novelty of the paper lies in possibility to simplify the drug sensitivity-based adaption with infusion delay approach to achieve closedloop control of hypnosis during surgery. Proposed work uses a brain concentration as a feedback signal in place of the BIS signal. Regression model based estimated sensitivity parameters are used for adaption to avoid BIS signal based frequent adaption procedure and large offset error. Adaptive smith predictor with lead-lag filter approach is applied on 22 different patients' model identified by actual clinical data. The actual BIS and propofol infusion signals recorded during clinical trials were used to estimate patient's sensitivity parameters EC 50 and λ. Simulation results indicate that patient's drug sensitivity parameters based adaptive strategy facilitates optimal controller performance in most of the patients. Results are obtained with proposed scheme having less settling time, BIS oscillations and small offset error leads to adequate depth of anesthesia. A comparison with manual control mode and previously reported system shows that proposed system achieves reduction in the total variations of the propofol dose. Proposed adaptive scheme provides better performance with less oscillation in spite of computation delay, surgical stimulations and patient variability. Proposed scheme also provides improvement in robustness and may be suitable for clinical practices.
An automobile disk brake is essential mechanical system used to slow down and stop the vehicle. During the operation of brake high amount of kinetic energy will generate high amount of heat energy and forces. The generated heat increases the rotor temperature, which lead disk brake rotor deformation due to combined effect of mechanical forces and temperature. During study, disk brake rotor will be investigated for frictional forces acting on it and heat generated due to friction between calliper pads and rotor surface. Brake rotor dimensions can be optimized for strength with reduction in weight using advance topology optimization method. Topology optimization is very useful engineering technique especially at the concept design stage. Topology optimization is able to produce reliable and satisfactory results with the verified structural model. Topological optimization will be performed on ANSYS 18.1 software. New disk brake rotor shape will produced with the Creo 3.0 based on the topology optimization result. The new disc brake rotor from topology optimization result will compared with the traditional concept model and topology optimization base model. It will analyse that a new rotor will not fail during an experiment test, and these results will verified with a fabricated real sample under the durability condition.
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