Deep Learning Based Air-Writing Recognition with the Choice of Proper Interpolation Technique

The act of writing letters or words in free space with body movements is known as air-writing. Air-writing recognition is a special case of gesture recognition in which gestures correspond to characters and digits written in the air. Air-writing, unlike general gestures, does not require the memorization of predefined special gesture patterns. Rather, it is sensitive to the subject and language of interest. Traditional air-writing requires an extra device containing sensor(s), while the wide adoption of smart-bands eliminates the requirement of the extra device. Therefore, air-writing recognition systems are becoming more flexible day by day. However, the variability of signal duration is a key problem in developing an air-writing recognition model. Inconsistent signal duration is obvious due to the nature of the writing and data-recording process. To make the signals consistent in length, researchers attempted various strategies including padding and truncating, but these procedures result in significant data loss. Interpolation is a statistical technique that can be employed for time-series signals to ensure minimum data loss. In this paper, we extensively investigated different interpolation techniques on seven publicly available air-writing datasets and developed a method to recognize air-written characters using a 2D-CNN model. In both user-dependent and user-independent principles, our method outperformed all the state-of-the-art methods by a clear margin for all datasets.

Minimization of traffic delay in traffic flows with coordinated control

The method and results of transport research, carried out by field research method, on the determination of the main indicators of traffic flows with significant unevenness of the movement on the arterial street in conditions of coordinated control is reviewed in the paper. Time parameters of traffic light control for which a reduction in traffic delay is achieved in direct and opposite traffic flow by the change of permissive signal depending on traffic intensity are determined using the simulation method. Change (increase) of the duration of the permissive signal provides uninterrupted movement of vehicles` group during their passage of stop-line at traffic light objects. The proposed method can be used on sections of transport networks with coordinated control, where there is significant heterogeneity of traffic flow, and it prevents the dissipation of groups that consist of vehicles with different dynamic characteristics. Such a result is being performed in the case when in the system of automated control, which combines adjacent intersections on an arterial street, fixed-time program control of traffic light signalization is operating. In this condition, there is a possibility to adjust the duration of signals of traffic light groups by correcting the width (permissive signal duration) and angle of inclination (speed of movement) of the timeline in coordination graphs. The scientific novelty of this research is that the method of traffic delay minimization in conditions of coordinated control acquired further development. The essence of the method is in the controlled change of the range of permissive signal duration in conditions of simultaneous control of the speed of movement between adjacent intersections. Practical value is the application of different programs of traffic light control on sections of arterial streets in transport districts where a significant difference of values of traffic intensity by directions is in morning and evening peak periods.

Analysis of the effect of fast and slow multiplicative noise on the distortion of the radiation pattern of the «array-receiver» system.

The effect of fast and slow multiplicative noise on the distortion of the beam pattern of the «array-receiver» system in the conditions of the smoothing effect of the receiver and taking into account the time of relative lag from the grating elements was analyzed. Expressions are obtained for instantaneous beam patterns of the «array-receiver» system in the absence and presence of multiplicative noise. It is shown that in the case of action of multiplicative noise the beam pattern of the «array-receiver» system is obtained by averaging the instantaneous pattern on the grating correctness at a time interval equal to the signal duration. Influence of periodic multiplicative noise on distortion of beam pattern of system «array-receiver» is investigted. It is shown that for all signals except frequency-modulated, the beam pattern expression is maximized at the time t0=0. It is also shown that the beam pattern distortion of the «array-receiver» system when exposed to periodic multiplicative noise is less than for the separately considered phased antenna array. The degree of reduction of distortion from smoothing action of matched receiver filter is determined; and the distortion is less, the greater the ratio of the spectrum width of the noise modulation function to the signal spectrum width. Analysis of the influence of fluctuation multiplicative noise on the distortion of beam pattern of «array-receiver» system for the case of matching with signal of receiver filter is performed. The power-average beam pattern of the «array-receiver» system is determined through the energy spectrum of the noise modulation function. It is noted that multiplicative noise, all other things being equal, has less effect on the beam-receiver pattern of the system when using broadband pulse signals without intra-pulse modulation and at the same time resolution in range. It is noted that in case of deep phase distortions for gratings with reversible phases, the distortion of the beam pattern of the «array-receiver» system caused by multiplicative noise is significantly more than those distortions associated with the extremity of the signal spectrum width. The newly smoothing effect of the receiver reduces the expansion of the beam lobe caused by multiplicative noise. An expression is obtained for the average power of the beam pattern of the «array-receiver» system with normally distributed phase distortions of the signal. The effect of the signal duration on beam distortions caused by multiplicative noise was quantified.

Methods of synthesis and formation of a system of nonlinear discrete signals for modern information and communication systems

The paper presents the results of solving the urgent problem of improving the performance indicators of information and communication systems (ICS), in particular, information security, noise immunity, secrecy, the speed of formation and processing of information. The use of the distributed spectrum technology (broadband noise-like signals) is a promising direction for ensuring the security of information resources. The methods used for data formation and processing, as well as the classes of broadband signals used as physical data carriers, do not allow providing the necessary (especially for critical infrastructure facilities) indicators of information security and noise immunity. In this case, as discrete sequences (DS) that expand the spectrum (manipulate the carrier frequency), should be used DS based on nonlinear construction rules and having improved correlation, ensemble and structural properties. Methods for the synthesis and formation of nonlinear discrete complex signals, namely, the so-called cryptographic signals, are proposed. The first method, presented in the article, uses random (pseudo-random) processes. Another method is based on the implementation of the operation of decimation of the original discrete sequence of symbols obtained from the results of the implementation of the first method; it provides the synthesis of an ensemble of signals for a certain signal duration. Analytical expressions are obtained for determining the synthesis time of an ensemble of signals using the proposed methods. It is shown that the speed of the signal generation method based on the decimation operation for a certain signal duration is more than three orders of magnitude higher than the speed of the method based on the random (pseudo-random) processes used. At the same time, based on the carried out computer simulation, it is shown that the signals obtained using the proposed methods have identical correlation, ensemble, and structural properties.

Modeling of the influence of multiplicative interference on the resolution the ability of signals according to the Woodward criterion in aviation and rocket and space applications radio systems

Рассмотрены и проанализированы алгоритмы моделирования влияния квазидетерминированных и флуктуационных мультипликативных помех на разрешающую способность систем обработки радиосигналов по задержке и частоте на основе критерия Вудворда. Показано, что при очень широкополосных мультипликативных помехах интервал разрешения по времени определяется только огибающей сигнала и не зависит от его фазовой структуры. Для сигналов с прямоугольной и колоколообразной огибающей он равен эквивалентной длительности сигнала. Приведены примеры вычисления интервалов разрешения при воздействии мультипликативных помех. The influence of quasi-deterministic and fluctuating multiplicative noise on the resolution of radio signal processing systems in terms of delay and frequency based on the Woodward criterion is considered and analyzed. It is shown that for very wide-band multiplicative interference, the time resolution interval is determined only by the envelope of the signal and does not depend on its phase structure. For rectangular and bell-shaped envelope signals, it is equal to the equivalent signal duration. Examples of calculation of resolution intervals under the influence of multiplicative interference are given.

Bounds on the Transmit Power of b-Modulated NFDM Systems in Anomalous Dispersion Fiber

The performance of various nonlinear frequency division multiplexed (NFDM) fiber-optic transmission systems has been observed to decrease with increasing signal duration. For a class of NFDM systems known as b-modulators, we show that the nonlinear bandwidth, signal duration, and power are coupled when singularities in the nonlinear spectrum are avoided. When the nonlinear bandwidth is fixed, the coupling results in an upper bound on the transmit power that decreases with increasing signal duration. Signal-to-noise ratios are consequently expected to decrease, which can help explain drops in performance observed in practice. Furthermore, we show that there is often a finite bound on the transmit power of b-modulators even if spectral singularities are allowed.