acoustic neuromas (AN) are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma (VS) causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumor is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR) or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few. The predominant clinical endpoints of AN treatment include tumor control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL) . It is uncertain if treating a small tumor leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment. In this paper we review the literature for the natural course, the treatment alternatives and the results of AN. Finally, we present our experience with a management strategy applied for more than 30 years.

Sound is one of the important factors in creating a good feeling in a mosque and it can play a role as a sensory medium to communicate spiritually with God. Therefore, the acoustic standards have defined the optimal level for the mosque in the field of various variables. In order to compare the acoustic conditions of the use of the mosque with the standard limits, the present research has carried out field measurements and software analysis of the standing position in order to simulate the prayer position. Form and volume are the two considered architectural parameters and Background Noise (BN), Reverberation Time (RT), and Sound Pressure Level (SPL) are the three acoustic variables of the study. A total number of 15 historical mosques in Tabriz are divided into three large, medium, and small volume categories and five form categories have been tested. The reference of the study is ISO3382-1 and ISO3382-2 and the measurements were made with B&K equipment. In addition to the direct achievements, the results have been adapted to international standards and show that the acoustic situation in the historical mosques of Tabriz, regardless of their volume and form, produces sound in the range of 60 to 90 phones, and in terms of RT, have the suitable design from the volume point of view, but the lack of carpet flooring in some of them has increased the RT. The background noise in these examples is less than NC-25, which provides a quiet space for the user and provides the necessary concentration for individual worship.

This paper aims at proposing a novel type tunable acoustic metamaterials with complete band gap composed of piezoelectric rods (Lithium Niobate) with square array as inclusion embedded polyimide aerogel background. The plane wave expansion method and the principles of Bloch-Floquet method used to get a band frequency and study the pass band for noise control. The results of this paper provide the required guidance for designing tunable wave filters or wave guide which might be useful in high-precision mechanical systems operated in certain frequency ranges, and switches made of piezoelectric; they also propose a novel type of tunable mechanical meta composite, where is independent of wave direction and has an equal sensitivity in all directions in which reacts omnidirectional and improves the aero acoustic noise control (e. g. bladeless fans) as well as general performance of vibrating structures (e. g. wind turbine).

Employing nonlinear dynamic signature of the host structure for early damage detection and remaining useful life estimation purposes, is an emerging idea in the area of piezoelectric patches based structural health monitoring. Clamped support loosening is one of the defects that not only may cause disorder in system’ s functioning, but also obstruct damage identification process through distorting the signals. In this study, support loosening induced contact acoustic nonlinearity (CAN) behavior was monitored by vibro-acoustic modulation (VAM) technique. Using miniaturized PZT patches with the capability to be installed on the host structure permanently for both pump and probe actuation as well as sensing the modulated signal, enabled online monitoring via VAM technique. An appropriate filter was designed to eliminate the unintentionally excited natural frequencies and to reveal the sidebands. In this study, the sensitivity of modulation strength to the pump excitation frequency was also investigated. According to the results, appearance of sidebands around the central probe frequency is an appropriate indicator for CAN identification. In order to study the mechanism of modulation phenomenon, a coupled field electromechanical finite element (FE) model was developed. Proper matching of the numerical and experimental results indicates sufficient accuracy of the developed FE model and its potential to predict the modulation behavior.

Insecurity, potential threats, and lack of sense of security lead to dissatisfaction and lack of confidence among citizens, especially tourists. Therefore, by utilizing the international security standard ISO and its localization, it is possible to provide services and create sustainable security. The aim of this study is to localize security standards and make them compatible with international security standards in ecotourism. The approach of this research is a mixed (qualitative-quantitative) approach, and document exploration techniques and interviews (in the form of the Delphi method) were used to collect data. Also, exploratory factor analysis was used to screen items and select the main items. The results of this study show that “maintaining and strengthening security and safety” has the highest rank. Also, among the independent variables, the construct “potential security and safety risks in tourism” is the most important. Another finding of this study is that the construct of “feeling of security” has the greatest impact on the goal construct (security), meaning that security is meaningful when the tourist feels it. Finally, in the final neural network model, it was determined that the three constructs of “rules regarding security and safety”, “potential safety and security risks in tourism” and “tourism in a standard location” have an impact on the construct of “security”.

Vehicle vibration and noise characteristics play a major role in ride comfort. Noise of tire in contact with the road is one of the main sources of noise in passenger cars, caused by the rolling of tire on uneven surfaces. Excitation is done through tread structure to fluid cavity and noise and vibrations transmission to the rims are of particular importance. In this paper, vibration analysis of coupled acoustic model of tire, rim and fluid acoustic cavity is performed. For this purpose, a coupled numerical finite element model is used. First, tire modeling has been addressed, taking into account the tread and two side walls and steel wheel rim. Then modal analysis has been performed to identify the structural and acoustic resonance frequencies and mode shapes. Then, using the harmonic environment coupled with static and modal analyses, acoustically coupled models of tire, rim and cavity are used to calculate the acoustic pressure of the fluid cavity and sound pressure level, and the harmonic frequency response of the wheel hub system including the forces of wheel hub is discussed. According to the presented model, the parameters affecting tire noise levels are discussed.

One of the efficient, cost-effective, and rapid methods for non-destructive quality evaluation of horticultural and agricultural products is the acoustic analysis response generated by impact. In this research, the possibility of using sound processing resulting from the collision of hazelnuts with a galvanized iron plate for separating large, medium, and small hazelnuts, as well as separating nutty and hollow types, has been investigated. First, hazelnuts were divided into four groups based on size: large, medium, small, and empty. The hazelnuts of each group were weighed to separate the nutty and hollow types from the composition. Based on this approach, a system was designed and developed using a single-impact method to generate sound from hazelnuts upon impact with an iron surface. Artificial intelligence techniques were employed to analyze and classify the product based on features extracted from their acoustic signals. Then, in order to take samples, all hazelnuts were dropped from a height of 35 and 45 cm and hit an iron plate. The sound of the collision was recorded by the microphone. The recorded data is taken from the time domain to the frequency domain by Fast Fourier Transform (FFT) and graded using the features obtained from the gradation. The results of audio tests show that by comparing the direct ratio of weight with amplitude and sound pressure level, a hazelnut that has a pass range of less than 0.121Pa, and a sound pressure level of less than 75.2 dB is hollow or has an immature kernels. The study also revealed that the drop height did not significantly affect the quality classification, and a height of 35 cm, along with a sound pressure level above 75.2 dB, yielded the best results for hazelnuts classification. The results of this research, in combination with the common methods of separating hazelnuts, show that acoustic response analysis as a non-destructive method of grading hazelnuts can reduce their damage in addition to increasing the speed and accuracy of calssification.

Cavitation phenomenon can cause deterioration of the hydraulic performance, damage by pitting, material erosion, structure vibration and noise in fluid machinery, turbo-machinery, ship propellers and in many other applications. Therefore, it is important to detect inception of cavitation phenomenon. An experimental study has been carried out in order to investigate the noise radiated by various cavitating sources to determine the validity of noise measurements for detecting the onset of cavitation. Measurements have been made measuring the noise radiated by a number of configurations in a water tunnel at various operating condition to determine the onset of cavitation. The measurements have been conducted over a frequency range of 31. 5 Hz to 31. 5 kHz in one-third octave bands. The onset of cavitation was measured visually through a Perspex side of the working section of the water tunnel. Moreover, a theoretical estimate of the pressure radiated from the cavitation nuclei at their critical radii and their frequency was presented. Tests indicated that, generally, at the point of visual inception there was a marked rise of the sound pressure level in the high-frequency noise, whilst the low-frequency noise increased as the cavitation developed. This finding was supported by the theoretical estimate of the pulsating frequency of cavitation nuclei. The results illustrated that the visual observations of inception confirm the noise measurements.