Estimation of the accuracy of determining the coordinates of a ground radio radiation source from aircraft by a passive single-position method by computer simulation.

The possibility of assessing the distance from the aircraft to an operating ground-based radar based on the totality of reflections of its signals from the terrain and local objects is evaluated. The peculiarity of the measurement algorithm is that a priori it is not necessary to know from which object one or the other signal was reflected. The coordinates of the reflectors are stored in the computer memory in the form of an electronic map of the area. The position of the radio emission source is determined by the difference in the arrival times of the direct and reflected signals, as well as the bearings measured from them.

Needle properties and a new higher altitude negative leader structure; observations by the LOFAR radio telescope

<p>Recently, Hare et al. 2020 found that individual leaders steps could be imaged in the VHF band, and for leaders below 5 km altitude, the radio emission from each step is mostly consistent with a point-source. We will report on new observations of negative leaders above 7 km altitude that behave significantly differently than lower altitude leaders. These higher- altitude leaders are a few 100 meters wide and have step lengths a few 100 meters long, as opposed to lower altitude leaders that are at most 10 meters wide with 10 meter stepping lengths. Furthermore, unlike lower altitude leaders, the radio emission from individual steps of higher altitude shows extensive structure. Each step shows a burst of radio radiation, followed by the growth of multiple filamentary structures. The nature of these filaments is presently unclear, but they could be long streamers or leader branches. We have observed one leader that clearly starts at low altitude and propagates to higher altitude. This leader shows that the transition from the low altitude mode of propagation to the higher altitude mode does not occur smoothly as one may expect, but occurs abruptly at around 6 km altitude within only one kilometer, somewhat similarly to a phase change.</p><p>Previous work has measured 100 m long stepping lengths of higher altitude leaders, and it is often assumed that this is a simple pressure scaling effect. However, our data shows that the stepping process at lower altitudes and higher altitudes appears very differently in VHF, and that the transition between the two modes occurs rapidly. This implies higher and lower altitude leaders actually have different propagation modes, and are not merely pressure-scaled versions of each other.</p><p>We will also present new detailed VHF measurements of needle activity. We will show that needle twinkles have a wide range of propagation speeds, from 10<sup>5</sup> to 10<sup>7</sup> m/s, and that needle twinkles sometimes show stepping behavior, which strongly implies that needle twinkles can propagate similar to stepped leaders or dart leaders depending on the conductivity of the needle. We will also show that recoil leaders can quench needle activity, which leads to a cycle of increasing needle activity followed by quenching by a recoil leader, as originally predicted by Hare et al. 2019.</p>

Estimation of trajectory parameters of radio radiation sources in multi-position complexes by the maximum likelihood method

The paper presents a new approach to the secondary processing of radar information in multi-position passive complexes. The proposed approach is based on the use of maximum likelihood estimates of discrete measurement counts at finite time intervals, taking into account the motion of the radio emission source. The advantage of the proposed approach is the possibility to work on non-full measurements. The disadvantage is the delay in the output of the solution, as well as a decrease in the rate of output of the solution. The article presents an analysis of the effectiveness of the proposed approach, as well as the results of testing the developed algorithm on real measurements.

Prospects for life increase for internal antirust coatings in pipes of oil assortment using SHF-radio-radiation impact

A review of ways for the operation increase of pipes with inner polymer antirust coatings is presented. A conclusion is drawn that the most promising method is a method of a non-thermal modification of coatings with SHF electromagnetic fields as one observes the increase of coating physical-mechanical properties at power consumption decrease. At that a small updating of a production line is required.

Fast radio bursts — A brief review: Some questions, fewer answers

Fast radio bursts (FRBs) are millisecond bursts of radio radiation at frequencies of about 1 GHz, recently discovered in pulsar surveys. They have not yet been definitively identified with any other astronomical object or phenomenon. The bursts are strongly dispersed, indicating passage through a high column density of low density plasma. The most economical interpretation is that this is the intergalactic medium, indicating that FRB are at “cosmological” distances with redshifts in the range 0.3–1.3. Their inferred brightness temperatures are as high as 10[Formula: see text] K, implying coherent emission by “bunched” charges, as in radio pulsars. I review the astronomical sites, objects and emission processes that have been proposed as the origin of FRB, with particular attention to soft gamma repeaters (SGRs) and giant pulsar pulses.