Airborne noise calculation for single-layer partitions with the concentrated parameters method

The article considers an approach to the calculation of sound insulation for building partitions with the method of concentrated parameters at the standard frequency range, which is specified in regulatory documents. The concepts of “reduced” and “concentrated” masses are introduced for objects that are sound conductors. It is noted that the physical model of sound insulation in the three conditionally allocated frequency ranges of the standard spectrum has differences. The calculated equations of sound insulation for three frequency ranges are given. Systems of equations for obtaining the calculation formulas at the first and the second frequency ranges are used. The systems consist of equations for the conservation of the amount of motion and the conservation of kinetic energy. The influence of the damping effect of air and resonant phenomena in the plate on the final value of sound insulation is described. The nature of sound propagation in the third frequency range is considered, in which, unlike the first two sections of the frequency spectrum, where the propagation of flexural waves is mainly recorded in the plate, shear and dilatational vibrations have a predominant influence on the sound insulation level. Examples of graphs for massive partitions obtained by the considered method are given. The accuracy of the proposed method is evaluated in comparison with the normative code’s method and the method based on the theory of self-matching of sound fields. A general algorithm for calculating sound insulation in the entire standard frequency range is presented.

Testing of Frequency Synthesizers for ZigBee Transceivers

ZigBee is a wireless standard defined for low data rate applications with ultra-low power requirements. Devices based on this standard are expected to be low cost with a large battery life or use energy harvesting techniques.As a part of a major project for developing a fully functional RF transceiver chip complying with the standard, frequency synthesizers have been designed based on integer-N phase lock loops which are expected to work as local oscillators for both the transmitter and the receiver. The standard required the PLLs to be programmable to 16 channels in the 2.4-2.5 GHz range. One of the PLLs used an LC VCO while the other used a ring VCO. This work was meant to test these PLLs to make sure that they met the specifications required of them as per the standard.

Register Variation in Chinese English and Language Variation between Chinese English and American English: A Case Study of Perhaps and Maybe

The study aims to explore the register variation in Chinese English and language variation between Chinese English and American English. A corpus-based and comparative methodology was used to analyse the discourse features of Chinese English in the use of the lexical items perhaps and maybe. The major findings of the study can be stated as follows: 1) the more formal word perhaps is used more frequently than the informal word maybe in all the four genres in Chinese English. This shows that the text of Chinese English is generally in a more formal style. 2) In the Chinese English text, the ratios of the standard frequency of perhaps to maybe are greater than those in American English in the all the four genres. This indicates that the text in Chinese English is generally in a more formal style than that in American English. 3) In the Chinese English text, the informal word maybe is used less frequently than in the American English text. This is a sign that Chinese English is more formal than American English.

The influence of the bimodal stimulation on the auditory ability of temporal ordering

ABSTRACT Objective: to analyze temporal ordering auditory ability in unilateral cochlear implant users with bimodal stimulation. Methods: the study included 15 unilateral cochlear implant users, six with bimodal stimulation and nine with exclusive cochlear implant and a control group consisting of 15 hearing individuals. Both groups underwent the standard duration and the standard frequency tests for temporal ordering auditory ability analysis. In the inferential analysis of the data, the nonparametric statistical tests Mann-Whitney and Kruskal-Wallis were used (p<0,05). Results: there was a significant difference in the performance of the standard frequency test, and subjects with bimodal stimulation presented a better performance than those with exclusive cochlear implants. The standard frequency test was associated with education and speech therapy. On the other hand, in the standard duration test, there was a relation with the implanted ear. The most frequent errors were discrimination for both temporal tests. Conclusion: bimodal stimulation, education and speech therapy influenced the performance of the frequency pattern test, while the implanted side influenced the performance of the duration pattern test.

Two wavelength frequency transfer over an optical fiber link

In this paper we present the theory and the experimental setup used to transfer a standard frequency, to synchronize two clocks linked by an optical fiber. In order to verify the accuracy on frequency transfer over fiber link, we prepared an experiment that allows testing the performance of the setup for a variable set of environmental conditions, namely associated to temperature and vibration variations. The experimental setup shows the fiber optic link between one laboratory, where the standard frequency is generated, and another laboratory, where the equipment for simulating temperatures and vibrations are installed. The standard frequency, traceable to UTC(IPQ), is used to modulate two lasers with different wavelength,, injected in the optical fiber. At the end of the optical fiber the signals will be out of phase due to the inherent chromatic dispersion, which is also dependent on the temperature of the propagation media. Measuring the phase variations, caused by temperature gradients in the fiber, we can compensate the frequency transfer and synchronize the clocks. Evaluating all uncertainty components in this model, allows the metrological characterization of the synchronization and obtain the associated uncertainty of this quantity.