The object of research is thermal processes in Langevin-type piezoceramic electroacoustic transducers (PET), taking into account the housing. The piezoceramic electroacoustic transducers heat up during operation. Overheating of the converter leads to negative consequences, accompanied by a change in the parameters, characteristics of the device, as well as the failure of the converter. Or limitation on the duration and mode of operation, output power, current, amplitude and speed of oscillation of the converter. The paper investigates the effect of the housing on the temperature field of a Langevin-type PET by the finite element method, using modeling in SolidWorks. The results of temperature reduction of such cooling methods are shown: – filling the housing cavity with electrical insulating liquid, gas, a mixture of thermal paste; – use of holes in the housing; – changing the shape of the rear cover to have radiator side fins, vertical radiator fins, cylindrical radiator fins; – heat-resistant layer; – use of active air cooling at three different speeds. The most efficient 53 % and a uniform temperature field were found when filling with a mixture of thermal paste, but this solution is accompanied by additional experiments and a preparatory stage with the mixture. The cooling efficiency of 47 % was provided by active cooling – blowing with air, and this method requires additional equipment. Filling with insulating liquid gave a cooling efficiency of 27 % – an optimal result that does not require expensive investments. Slow blowing of the housing or adding only holes resulted in a decrease in the maximum heating temperature from 10 to 20 %, therefore, if the PET design allows the presence of holes, then it is necessary to rationally place them. Changing the shape of the back plate, heat-absorbing element, filling the housing with gas gave an efficiency decrease in the maximum temperature by 6–8 % compared to a closed housing with air. The research results make it possible to choose the optimal option for reducing the heating temperature of the Langevin-type PET to increase its efficiency and long-term trouble-free operation.
Radio and acoustic thermometry allow measuring the temperature of internal tissues at depths of several centimeters, which is of interest in early diagnosis of diseases, hearing diagnostics, identifying inflammatory processes, monitoring physiotherapy procedures, conducting surgical operations accompanied by patient cooling, long-term control of the engraftment process of transplanted organs, monitoring treatment of malignant neoplasms by hyperthermia and thermal ablation methods, as well as using synergistic effects in oncology.In the acoustothermometry research method, the internal temperature is measured by receiving and recording
Today the actual direction in psychoacoustics is the use of acoustic influences in order to correct the physiological, functional or psychological state of man. Various audio stimuli are used to achieve this goal, such as regulating heart rate, increasing the productivity of human work, improving mood and relieving depression. To study the effectiveness of music therapy with the help of modern electroencephalographic complexes, an electroencephalogram (EEG) is recorded and analyzed. Changes in the state of the brain can be assessed by changes in the frequency components (rhythms) of the EEG. Delta rhythm is registered during deep sleep, hyperventilation or anesthesia. The dominance of delta activity in adolescents and adults in the state of wakefulness is a sign of pathology. There is information that fluctuations in this rhythm can be identified in the EEG signal at rest under some forms of stress. The aim of this work is to analyze the ratio of the contribution of delta waves of the brain in its total activity in percentage when listening to low-frequency acoustic signals before and during the action of stressors. The experiments were conducted on 5 people, of whom 2 were men and 3 – women, all of them aged 18-22 years. A total of 14 experiments were conducted - 7 in male and female groups. Electroencephalogram (EEG) registration took place in 16 leads. The composition “Demon Wings” by Bohren & der Club of Gore was used as a musical impact factor. Research was conducted in time periods before and during the increased study load, which is actually considered as a factor that causes an increase in psycho-emotional stress. The results obtained in the periods before and during the influence of the stress factor are presented via the following data: mean values of the comparative levels, differences in mean values and the probability of error of the delta rhythms in the two hemispheres of the brain in periods during the first and third minutes of the experiment. The probability of error of the assumption was determined via using Student's t-criterion. Obtained results show that the average values of the test groups under the influence of stress factor increased significantly relative to the values obtained before this influence. In addition, if before the influence of stress factors there was a decrease in values in the third minute of the experiment relative to the first, then after this effect, the values did not vary. There is no statistically significant difference for the last two compared groups The data presented in the paper indicate that the level of delta rhythm increases significantly during the indirect influence of time-stretched stressors, despite the presence of another type of influence - acoustic, caused by a low-frequency music signal. This rhythm is abnormal for the human body, which is in good spirits. That is why the presence of a high level of this rhythm can affect the accuracy of experiments that investigate the effect of a musical signal on the psycho-emotional state of a person, regardless of the nature of the impact and spectral characteristics of the musical signal.
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