Rotation, Strain, and Translation Sensors Performance Tests with Active Seismic Sources

Interest in measuring displacement gradients, such as rotation and strain, is growing in many areas of geophysical research. This results in an urgent demand for reliable and field-deployable instruments measuring these quantities. In order to further establish a high-quality standard for rotation and strain measurements in seismology, we organized a comparative sensor test experiment that took place in November 2019 at the Geophysical Observatory of the Ludwig-Maximilians University Munich in Fürstenfeldbruck, Germany. More than 24 different sensors, including three-component and single-component broadband rotational seismometers, six-component strong-motion sensors and Rotaphone systems, as well as the large ring laser gyroscopes ROMY and a Distributed Acoustic Sensing system, were involved in addition to 14 classical broadband seismometers and a 160 channel, 4.5 Hz geophone chain. The experiment consisted of two parts: during the first part, the sensors were co-located in a huddle test recording self-noise and signals from small, nearby explosions. In a second part, the sensors were distributed into the field in various array configurations recording seismic signals that were generated by small amounts of explosive and a Vibroseis truck. This paper presents details on the experimental setup and a first sensor performance comparison focusing on sensor self-noise, signal-to-noise ratios, and waveform similarities for the rotation rate sensors. Most of the sensors show a high level of coherency and waveform similarity within a narrow frequency range between 10 Hz and 20 Hz for recordings from a nearby explosion signal. Sensor as well as experiment design are critically accessed revealing the great need for reliable reference sensors.

Управляемая дисперсия постоянных распространения TE-=SUB=-2-=/SUB=--мод тонкой левоориентированной пленки на керровской подложке вблизи частот нуля групповой скорости

The dispersion of the propagation constants of TE2-modes in a thin left-handed film on a substrate with the Kerr effect has been considered in a narrow frequency range near the zero of a group velocity of the mode. It is shown that such dispersion can be controlled by varying the intensity of the light field with a change in frequency. The conditions, under which the propagation constants remain constant when the frequency changes, have been determined. Soliton-like wave packets have been considered.

Transmission of high-frequency vocalizations from hummingbirds living in diverse habitats

Some species of Andean hummingbirds produce high-frequency vocalizations which exceed the vocal range of most birds. They also challenge our understanding of the role of habitat structure in the evolution of vocal signals because these hummingbirds live in strikingly different habitats, ranging from cloud forest to high-altitude grasslands. Although these vocalizations are produced at high frequencies, they exhibit considerable variation in frequency content and temporal structure. The calls of the hummingbirds from the cloud forest are simpler and have a narrow frequency range compared to the complex song of the grasslands hummingbird. We hypothesized that each of the three high-frequency vocalizations is adapted for transmission in their habitat. We characterized the transmission of high-frequency vocal signals in the cloud forest and in the grasslands. All vocalizations attenuated and degraded substantially at short distances, suggesting that they are adapted for short-range communication. The simple vocalizations of the cloud-forest species transmitted better in both environments compared to the complex song of the grasslands hummingbird, probably due to relaxed constraints for high-frequency sounds in open habitats.

Model-Based Design of Magnetorheological Hydromounts

The widespread use of hydromounts as universal means of vibration protection is constrained by a number of factors: the narrow frequency range and the lack of unified calculation methods. The first problem can be solved by integrating a magnetorheological transformer, which is an electromagnet that controls the viscosity of the magnetorheological fluid in the hydraulic channels by changing the magnetic field. To overcome the second problem, calculation methods for hydromounts with magnetorheological control were developed. The physical model of the hydromount was obtained using the well-known Kwok algebraic model. In describing the shear deformation processes of a magnetorheological fluid in the hydromount throttle channel, the Shvedov-Bingham model for nonlinear plastic media was applied. Using the methods developed by the authors, prototypes of magnetorheological hydromounts were developed and manufactured. The results of load and vibration tests confirmed the adequacy of the proposed methods. The experimental study of frequency responses showed the possibility of their “detuning” from the resonance modes and the high efficiency of the hydromounts in the above-resonant region.

Analisis Ketepatan Pengukur Tegangan True RMS Jala-Jala Listrik Berbasis Mikrokontroler ATmega 328P

The analog AC-voltmeter usually can only measure the ideal-sinusoid voltage with narrow frequency range. Meanwhile, in fact the grid voltage is often not in the form of an ideal sinusoidal. To be able to measure a non-sinusoidal AC voltage with a wide range of frequency, a true-RMS voltmeter is needed. The research designed a true RMS measuring system using an ATmega 328P microcontroller. The input voltage is converted to pulse using Schmit triger and fed to the microcontroller’s external interrupt pin to calculate the input signal frequency. Meanwhile the microcontroller’s ADC sampled the input signal with a frequency of 128 times the signal’s frequency. RMS voltage calculations are performed using arithmetic operations for 16 and 32 bit integer variables. The test results show that the system can measure voltages with zero errors from 100 to 275 volts with a frequency of 50 Hz. The system can also measure voltages with zero errors at 220 volt with frequencies from 40 Hz to 150 Hz. However, this system can still be used to measure voltages ranging from 25 volts to 300 volts at frequencies from 35 Hz to 195 Hz with an average error of 0.21%. During RMS voltage calculation, the microcontroller’s CPU usage was 13.35%, so that this system can be further developed.

Overtone focusing in biphonic tuvan throat singing

Khoomei is a unique singing style originating from the republic of Tuva in central Asia. Singers produce two pitches simultaneously: a booming low-frequency rumble alongside a hovering high-pitched whistle-like tone. The biomechanics of this biphonation are not well-understood. Here, we use sound analysis, dynamic magnetic resonance imaging, and vocal tract modeling to demonstrate how biphonation is achieved by modulating vocal tract morphology. Tuvan singers show remarkable control in shaping their vocal tract to narrowly focus the harmonics (or overtones) emanating from their vocal cords. The biphonic sound is a combination of the fundamental pitch and a focused filter state, which is at the higher pitch (1–2 kHz) and formed by merging two formants, thereby greatly enhancing sound-production in a very narrow frequency range. Most importantly, we demonstrate that this biphonation is a phenomenon arising from linear filtering rather than from a nonlinear source.

Ultrawideband combined vibrator-slot Clavin type radiator

Background. Ultrawideband communication is a promising way of transmitting information that uses short electromagnetic pulses. It has great potential due to higher bandwidth than other methods of information transfer. This allows you to create ultra-fast wireless communication networks. But the implementation of ultra-wideband communication requires the use of compact and efficient pulsed emitters. Object. Create a compact pulsed combined antenna of electric and magnetic type, ultra-wideband analogue of the Clavin radiator, in which the necessary characteristics are provided by a strong interaction of its components. It is also necessary to analyze the directional, frequency and time characteristics of such a radiator. Methods: The numerical method of finite differences in time domain (FDTD) is used for the final calculation and optimization of the radiator. The initial design is calculated in a narrow frequency range by the method of electric and magnetomotive forces. Results. The multiparameter optimization of the antenna is carried out in order to find the optimal interaction between the electric and magnetic emitter while providing the required directional and frequency characteristics. The radiation patterns in the H and E planes for a number of frequencies are obtained, and the time dependences of the radiated field in these planes are constructed. Conclusions.The analog of the Clavin radiator can concentrate the energy of the radiation in a given direction and provide a wide range of operating frequencies, which in this implementation of antenna reaches 1 GHz. It should be noted the compactness of this structure and the presence of a number of geometric parameters, the change of which can improve the time parameters of the radiated field. The ultra-wideband combined vibrator-slot structure has several directions for further optimization of time, frequency and directional characteristics in accordance with the requirements of specific applications.

Design of Discretely Tunable Resonant Actuators Using Additive Inertial Units

Resonance is known to reduce the input energy requirements of various actuator systems. The favorable effects of resonance, however, are limited to a narrow frequency range. To overcome this limitation, we describe a general framework for using discrete units of inertia that can be activated in a binary sense to move a resonant frequency across a desired frequency range. We also enumerate the generalized physical cases in which actuators can energetically benefit from resonance. We develop closed-form optimal results for the idealized case of two binary additive inertial units and extend this to a general optimization scheme for higher numbers of units that introduce parasitic friction and added stiffness. We illustrate the concept of binary tuning with a representative linear translational system powered by a voice coil motor (VCM). The experimental results show good agreement with the intended theoretical design and show the general utility of the binary additive inertia approach.

Modeling of digital converter for GSM signals with MATLAB

In this study will simulate steady state of Digital Down Convertor (DDC) for GSM signal with a narrow frequency range. The MATLAB model that is described in this article simulates the work of the TIGC4016 Quad Digital Down Converter. This converter is used for digital mixing (down conversion) of signals, narrow band low-pass filtering and decimation. To implementation of the model, we use high sample-rate (69,333 MSPS) bandpass signal. The result contains low sample-rate (270.83 KSPS) baseband signal, thus facilitating the demodulation process.