The relevance of local magnetic records when using extreme space weather events as benchmarks

Space weather indices introduced for scientific purposes are commonly used to quantify operational nowcast of the geospace state during extreme space weather events. Some indices, such as the Disturbance storm time (Dst) index, have been applied to situations for which they are not originally intended. This raises a question about suitability as a space weather benchmark. In analysing historical records for different magnetometers at low- and mid-latitude, we find periods with longitudinal asymmetry in magnetic response that suggest important signals from individual magnetometers are being averaged out of the Dst record. This asymmetry develops as a double spike in the H-component: one negative in the observatories in the day sector and one positive in the observatories in the night sector. These spikes develop in short-time (about 2 hours) and pose a potential hazardous effect for users affected by space weather. The results from historical events have been reinforced with the systematic study of magnetic records during extreme events (Dst ≤ -200 nT and AL ≤ -2000 nT) in the period 1998-2017 from six magnetic observatories at about 40° magnetic latitude. Moreover, we show that the largest asymmetries take place during the early main phase and are recorded in narrow local time sectors. An important outcome of these results is that space weather benchmarks should be based on local records instead of the commonly used global indices. This action improves two important aspects of space weather: the assessment of historical extreme events and that of the needs of users.

Directed flow of D mesons at RHIC and LHC: non-perturbative dynamics, longitudinal bulk matter asymmetry and electromagnetic fields

We present a study of the directed flow v1 for D mesons discussing both the impact of initial vorticity and electromagnetic field. Recent studies predicted that v1 for D mesons is expected to be surprisingly much larger than that of light charged hadrons; we clarify that this is due to a different mechanism leading to the formation of a directed flow with respect to the one of the bulk matter at both relativistic and non-relativistic energies. We point out that the very large v1 for D mesons can be generated only if there is a longitudinal asymmetry between the bulk matter and the charm quarks and if the latter have a large non-perturbative interaction in the QGP medium. A quite good agreement with the data of STAR and ALICE is obtained if the diffusion coefficient able to correctly predict the RAA(pT), v2(pT) and v3(pT) of D meson is employed. Furthermore, the mechanism for the build-up of the v1(y) is associated to a quite small formation time that can be expected to be more sensitive to the initial high-temperature dependence of the charm diffusion coefficient.We discuss also the splitting of v1 for D0 and $$ {\overline{D}}^0 $$ D ¯ 0 due to the electromagnetic field that is again much larger than the one observed for charged particles and in agreement with the data by STAR that have however still error bars comparable with the splitting itself, while at LHC standard electromagnetic profile assuming a constant conductivity is not able to account for the huge splitting observed.

Trends in Improving Sensors for Controlling the Condition of Track Sections

Various principles can be used to implement intelligent track circuits: voltage regulation of the power supply, compensation methods for switching on rail lines and track circuit devices, receiver sensitivity adjustment, comparison of two electrical parameters of one, two, or more track circuits, as well as a combination of these methods. At present, such improvement of track circuits is becoming relevant, which would make it possible to exclude from the circuits one of the most unreliable elements - an insulating joint, use a modern microprocessor element base in devices for monitoring the state of track sections, thus ensure their reliable operation. This will significantly reduce the costs of building and operating interval control systems and increase train traffic safety. These requirements are met by intelligent track circuits, which consider the current value of the insulation resistance, the rate of change of this resistance, and the longitudinal asymmetry.

Development of the methods of calculation of the electrical installations working operation in case of quality supply disturbance

This paper proposes a method of calculating of asymmetrical modes of operation of electrical installations where simple and adequate loads equivalent circuits are available with working electrical equipment. So the mathematical model of equation system is derived as universal way for calculating the systems operating modes when it is subjected to a disturbance due to asymmetry. With the help of the obtained model we can calculate different cases of symmetry disturbances, all types of short circuits, between phase short circuits, any type of longitudinal asymmetry, open circuits when there is a resistance for the fault current at the place of damage In the given method, specific types of asymmetry are considered as particular cases and easily calculated from the generalized formula, which is essentially reduces the calculation and allows us to consider cases of asymmetry of any complexity. Therefore this method is offered as a basic for calculation of asymmetry when the system is subjected to a disturbance.

INFLUENCE ESTIMATION OF ASYMMETRY EXTRA HIGH VOLTAGE TRANSMISSION LINE ON DETERMINATION OF COMPENSATING REACTOR PARAMETERS

The article shows the urgency of the problem of studying resonant processes in extra high voltage power lines. The research of processes in extra high voltage power transmission lines is carried out to develop and implement measures to prevent overvoltages. Resonant overvoltages arising because of open phase modes of operation of the extra high voltage transmission line are considered. The paper shows the influence of the levels of longitudinal asymmetry on the calculation of the resistances of compensating reactors to reduce the values of overvoltages in the pause of single-phase automatic reclose. The degree of influence of the wire transposition scheme on the choice of the resistance of the compensation reactor and on the values of resonant overvoltages in the cycle of single-phase automatic reclose is considered. Estimation of asymmetry coefficients for different transposition schemes is performed. To select the resistance of the compensation reactor, the data of the existing high-voltage transmission lines of 750 kV were taken. Recommendations for the implementation of measures to prevent and limit resonant overvoltages are given. The current theoretical and practical problems of operation of the extra high voltage power line are considered and the ways of further research are shown. References 14, figures 5, tables 2.

Variations of Poynting Flux in the Northern Hemisphere during Quiet Times

<p><span>Poynting flux energy is deposited from the magnetosphere in high latitudes, and measures the electromagnetic energy transmitted between the magnetosphere and the ionosphere. Little attention has been paid on the seasonal variation of the longitudinal pattern of the Poynting flux. Here, using long-term measurements of the ion drifts and the magnetic field by the DMSP satellite in the topside ionosphere, a statistical investigation of the longitudinal distributions of the Poynting flux in polar region during quiet times is conducted. Both case study and statistics show that there is a local maximum in downward Poynting flux in the pre-noon sector. Generally, the maximum is centered around geographic longitude of 120° west and geographic latitude of 80°, meaning that the total energy transferred into the ionosphere is the greatest in this region. The longitudinal distribution of the Poynting flux also exhibit clear seasonal variations with the longitudinal asymmetry the most significant in norther summer. The results could provide some new sights in future investigations of magnetosphere-ionosphere coupling in the polar region with observations and simulations.</span></p>

Measurement of P-Violation in 139La(n,γ)140La – a first step towards a T-Violation search

We performed a polarized neutron transmission asymmetry measurement utilizing the 139La(n,γ)140La reaction. This measurement involved the use of a recently developed 3He spin filter mounted on the J-PARC MLF beam line number 4 (BL04). The resulting value of the longitudinal asymmetry AL = (11.7 ± 1.1)% was found to be in good agreement with existing values in the literature suggesting that the method by which we polarize the neutron beam is not a significant source of uncertainty. This preliminary work represents a first step toward future measurements of the angular correlation in (n̅,Υ) reactions necessary in the search for enhanced T-Violation in compound nuclei.