Simulation of periodic synchronization of UAV's clock

Unmanned aerial vehicles (UAVs) is one of the most fast progressing technologies. High space-time flexibility of UAV networks along with the ability to payload sensitive measuring equipment allows establishing aerial wireless sensor networks (AWSNs) with new qualities. However, establishing a rapidly reconfigurable phased antenna array system for precise spatially distributed measurements requires a high-quality frequency-phase synchronization of the AWSN drones. Particularly, this paper relates to the problem of designing a synchronized AWSN with a centralized architecture. By a computer simulation, we assess an accuracy of the periodic synchronization of two crystal oscillators installed at the AWSN drones as onboard clocks. Two synchronization methods are considered: based on the total phase of a single carrier frequency and based on the differential phase of two carrier frequencies. It is shown that for most practical tasks it is sufficient to transmit a synchronizing signal with a period ranging from 1 to 20 seconds. The corresponding synchronization error of two onboard clocks can be held under 1.5 ns in the case of using of OCXO-oscillators and under 10.5 ns when using TCXO-oscillators, respectively

Analysis of Interictal EEG Signal Correlations for Diagnostics of Epilepsy

© 2020, Allerton Press, Inc. Abstract: Principles are described for diagnosing epilepsy on the basis of the Memory Function Formalism. Auto- and cross-correlations of electroencephalograms from healthy subjects and patients with epilepsy recorded during the interictal period are studied. Characteristic types of the memory function power spectra and substantial changes in statistical memory effects in pathology are found. Disorders are revealed in the dynamic interconnection in areas of the cerebral cortex in epilepsy

Synthesis and interaction with model DNA of polyaniline and poly[N-(2-hydroxyethyl)aniline]

The associates of conjugated polymers with biopolymers offer an attractive basis for creating bioelectrosensors and biointerfaces. Nanostructured materials based on conjugated polymers and biopolymers allow to obtain hybrid electroactive biomaterials for applications in biosensors. Polyaniline and poly[N-(2-hydroxyethyl)aniline] have been synthesized by the method of mechanochemical oxidative polymerization. Ammonium persulfate has been used as an oxidant. The obtained polymers have been characterized by 1H NMR, IR, and MALDI mass spectroscopy. The methods of dynamic light scattering and scanning electron microscopy have shown the formation of nano-sized particles: polyaniline forms of particles with the average size of 250 nm (PDI = 0.2); in case of poly[N-(2-hydroxyethyl)aniline], the average size is about 2 ?m (PDI = 0.5). The interaction of conjugated polymer dispersions with model DNA from salmon sperm has been investigated by the dynamic light scattering method. The formation of micron-sized associates in the case of polyaniline has been revealed. Lower sizes of the associates have been recorded in the case of poly[N-(2-hydroxyethyl)aniline]. The introduction of hydroxyethyl fragments has resulted in deaggregation of particles forming smaller-sized associates with DNA having the average size of 1.2 ?m (PDI=0.3). Such difference in the aggregation of conjugated polymer particles and their associates with DNA is explained by the effect of hydrophilic hydroxyethyl groups that are capable of hydrogen bonding with a biopolymer and allow to achieve higher dispersion stability due to more effective solvation in water

Simulation of short-term instability of UAV's clock

Unmanned aerial vehicles (UAVs) is one of the most fast progressing technologies. High space-time flexibility of UAV networks along with the ability to payload sensitive measuring equipment allows establishing aerial wireless sensor networks (AWSNs) with new qualities. However, establishing a rapidly reconfigurable phased antenna array system for precise spatially distributed measurements requires a high-quality frequency-phase synchronization of the AWSN drones. In particular, this paper relates to the problem of designing a synchronized AWSN with a centralized architecture. A model for simulating random frequency offset of two TCXO or OCXO crystal oscillators used as onboard frequency standards installed at the AWSN drones is presented. Our simulation results show that under continuous real-time synchronization, the synchronization error of the master and slave drones can be held under 1.5 ns for at least 100-second intervals

Synchronous data acquisition system

This paper describes a complex that implements synchronous data collection from geophysical equipment. It includes several blocks. Each of them, in turn, consists of a data acquisition unit and a micro-switch unit. The communication between the blocks is carried out using the UDP protocol over a twisted pair of category 5 EIA-568. The data transmission channel is used to power the system and transmit clock signals. The micro-switch unit transfers data from the data collection unit to the local processor. The data collection unit converts analog signals from target loads (magnetometer, geophone) into digital form. Also, this block can adjust the level of the analog signal. The article presents the architecture of the complex and the structure of each of the blocks, presents the results of measurements and notes the features of the operation of the complex