Information technologies for creating spatiotemporal modems multiposition active-passive radar systems

The methods of synthesis of the directional diagram of active transmitting antenna arrays when receiving signals reflected from radar targets are considered. It is shown that when using multifrequency orthogonal coherent signals in the elements and addressable access at their reception it is possible to provide a small level of the side lobes of the spatial uncertainty function in a given sector of observation by selecting the type of intrapulse modulation of partial signals. Orthogonalization of antenna basis of transmitting and receiving antennas allows digital spectral-correlation processing of samples of aggregate signal from each target to solve the technological problem of multidimensional observation space in multiposition systems of coherent radiolocation when detecting, resolving, estimating coordinates and motion parameters of targets. The results of simulation modeling of spatio-temporal radar modems implemented according to the stated principles are given.

Optimizing RDF Stream Processing for Uncertainty Management

RDF Stream Processing (RSP) has been proposed as a way of bridging the gap between the Complex Event Processing (CEP) paradigm and the Semantic Web standards. Uncertainty has been recognized as a critical aspect in CEP, but it has received little attention within the context of RSP. In this paper, we investigate the impact of different RSP optimization strategies for uncertainty management. The paper describes (1) an extension of the RSP-QL⋆ data model to capture bind expressions, filter expressions, and uncertainty functions; (2) optimization techniques related to lazy variables and caching of uncertainty functions, and a heuristic for reordering uncertainty filters in query plans; and (3) an evaluation of these strategies in a prototype implementation. The results show that using a lazy variable mechanism for uncertainty functions can improve query execution performance by orders of magnitude while introducing negligible overhead. The results also show that caching uncertainty function results can improve performance under most conditions, but that maintaining this cache can potentially add overhead to the overall query execution process. Finally, the effect of the proposed heuristic on query execution performance was shown to depend on multiple factors, including the selectivity of uncertainty filters, the size of intermediate results, and the cost associated with the evaluation of the uncertainty functions.

Long-time coherent accumulation algorithms for reflected signal with non-zero higher derivatives of the range to radar target in the spectral domain

The purpose of the article is to present computationally economical algorithms for long-term coherent accumulation of signals reflected from a point target with compensation for range and frequency migration and accumulation of signals in the spectral region. The algorithms include intra-period processing with simultaneous correction of range and frequency migration and inter-period processing with coherent accumulation of signals at the output of intra-period processing. In the first variant of the algorithm, intra-period processing is implemented by calculating the spectra of the received signals in each repetition period, multiplying the samples of the spectra by the samples of the amplitude-phase-frequency characteristic of the matched filter of a single signal and correcting phase coefficients determined by the number of the repetition period and the values of the range derivatives, and the inverse Fourier transform of the transformed spectra. The difference between the second version of the algorithm at the stage of intraperiod processing is the correction of only the quadratic and subsequent components of the range and frequency migration and the use of the keystone transformation, which eliminates the linear range migration. Coherent accumulation for both variants is realized due to the fast Fourier transform of the signal samples over the repetition periods for all samples over the range. The concept of “rough speed resolutionˮ is introduced, which determines the arrangement of channels when compensating for range migration. The uncertainty function in the coordinates “velocity–acceleration” is obtained. The equivalence of the two variants of the algorithm is shown and estimates for the required number of receiver channels are given. The simulation results confirming the operability of the proposed algorithms are presented.

#3131 Stimulation of the ventrolateral prefrontal cortex speeds up evidence accumulation in conflictual-uncertain environments

IntroductionEvaluation of the available choices, an integral step in decision-making, leads to the selection of the optimal and most rewarding one. This process of choice selection depends on its features such as value and reward-likelihood, which form the basis for constructs such as Conflict- easy or difficult (difference between reward probabilities of the stimuli-pairs) and Uncertainty- low, medium, or high (inverse U-shaped probability-uncertainty function).The ventrolateral prefrontal cortex (vlPFC) has been implicated in various processes ranging from uncertainty processing to washing behaviours in Obsessive-compulsive disorder (OCD). Here, we target the vlPFC using trans-cranial stimulation, to modulate decision-making behaviours in the context of conflict and uncertainty.MethodsUsing a single-blinded design, we tested 60 healthy controls (30 per group) randomly allocated to either active (continuous theta burst protocol c-TBS) or sham group. The c-TBS protocol used the standard three-pulse burst design repeated every 200ms, with a total of 600 pulses delivered at stimulation intensity set at 80% of the participants Active Motor Threshold. The sham stimulation was delivered with the coil positioned at a 90 angle to the target. Post-stimulation (active or sham), the participants completed 134 trials of the sequential learning paradigm, which consisted of 2 stages. We focused on the second stage of the task, specifically on Conflict and Uncertainty which were used as model dependents of a hierarchical drift-diffusion model(HDDM) to extract the parameters (a- amount of evidence accumulated before making a decision) and the drift rates (v- information processing speed).ResultsUsing the choice and reaction time information as inputs to the HDDM model, we extracted the threshold and drift rates for all conflict and uncertainty conditions. A Bayesian repeated-measures ANOVA on threshold showed a very strong evidence for the main effect of conflict-uncertainty condition (BF10 = 5.2 x 1010) and stimulation by condition interaction (BF10 = 6.4 x 103) but no main effect of stimulation (BF10 = 0.46). A Bayesian Independent samples t-test showed strong evidence (BF10 = 77.54) for stimulation to speed up the decision-making process, by decreasing the amount of evidence accumulated (threshold)whilst selecting a choice in a difficult uncertain scenario.ConclusionsBy applying an inhibitory based stimulation protocol tovlPFC, we show a modulation in behaviour specific to context, where the choices are similar in value but their reward likelihood being uncertain. This finding has key implications to the design of novel interventions for OCD.

A Model for Quantifying the Agent of a Complex Network in Conditions of Incomplete Awareness

Purpose of the article: development of a mechanism for quantitative evaluation of elements of complex information systems in conditions of insufficient information about the presence of vulnerabilities. Research method: mathematical modeling of uncertainty estimation based on binary convolution and Kolmogorov complexity. Data banks on vulnerabilities and weaknesses are used as initial data for modeling. The result: it is shown that the operation of an element of a complex network can be represented by data transformation procedures, which consist of a sequence of operations in time, described by weaknesses and related vulnerabilities. Each operation can be evaluated at a qualitative level in terms of the severity of the consequences in the event of the implementation of potential weaknesses. The use of binary convolution and universal coding makes it possible to translate qualitative estimates into a binary sequence – a word in the alphabet {0,1}. The sequence of such words — as the uncertainty function — describes the possible negative consequences of implementing data transformation procedures due to the presence of weaknesses in an element of a complex system. It is proposed to use the Kolmogorov complexity to quantify the uncertainty function. The use of a Turing machine for calculating the uncertainty function provides a universal mechanism for evaluating elements of complex information systems from the point of view of information security, regardless of their software and hardware implementation.

АЛГОРИТМЫ ПЕРВИЧНОЙ И ВТОРИЧНОЙ ОБРАБОТКИ СИГНАЛОВ В СИСТЕМАХ АКТИВНОГО АПЕРТУРНОГО СИНТЕЗА

A method for processing spatio-temporal radio signals, which allows the formation of high spatial resolution images from aerospace carriers, has been synthesized. In this case, a swath is ±15° from the nadir relative to the flight line is considered. Traditionally this swath is not visible from aerospace carriers. A block diagram of an active-passive type radar is proposed. Initially the image obtained at the output of such a radar has a low quality of visual perception. Such image is called primary, since it was obtained at the stage of primary signal processing. The physical sense of such image is investigated. It approximately represents the operation of convolution of the ambiguity function with a spatial function proportional to the ideal image. The physical sense of the ideal image depends on the characteristics of the imaging system. In the problem under consideration, this is the specific radar cross section. In order to improve the quality of the image it is proposed additional processing (filtering). The paper substantiates the method of filtering (secondary processing) of images based on the solution of the inverse integral equation. It is shown that the exact solution to this equation is difficult to obtain because the form of the ambiguity function is not known exactly and can be estimated only approximately and, in addition, not for each ambiguity function it is possible to obtain a non-singular solution of the inversion equation. Therefore, an approximate solution to the problem is given. It solution is sufficient to solve practical problems of improving image quality. Using numerical simulation methods, the influence of the error in determining the shape of the uncertainty function on the task of improving image quality is studied. Examples of primary and secondary images obtained at the output of wideband active aperture synthesis systems with various geometries of spatially distributed antenna systems are given.