Features of the next reversal of the geomagnetic field

В статье обсуждаются возможность проявления очередной инверсии геомагнитного поля (ГМП) и его некоторые особенности. Дипольное поле (ДП) приблизится к нулевой отметке, которую достигнет примерно в 3500 году. С 1500 года, на фоне понижения ДП происходит рост октупольного и квадрупольного компонент ГМП и их суммы (О+К). ДП, согласно нашей модели геомагнетизма, после прохождения нулевой отметки начнет расти с обратным знаком и противодействовать (О+К) полю, понижая его уровень до нуля. В этот момент (≈ 6000 год) поле (N) будет иметь минимальную величину. Затем начнется рост ДП обратного значения (R). Инверсия закончится при достижении этим полем устойчивой величины. The possibility of a new reversal of the geomagnetic field (GMF) and some of its features are discussed. In 3500 the dipole field (DF) will become near zero. Since 1500, along with the decrease of DF, there has been an increase of the octupole and quadrupole components of the GMF as well as their sum (O+Q). According to our model of geomagnetism, after passing the zero the reversing DF will start its rise counteracting the (O+Q) field and lowering its value to zero. In about 6000 the total field DF+O+Q (N) will be minimum. After DF reaches a stable value the reversal will complete.

Nonlinear Cylindrical Markers Using Metamaterials

In this paper, the research of nonlinear cylindrical metastructure was obtained. An algorithm for finding the total field of a nonlinearly loaded perfectly conducting cylinder covered with a metamaterial (MM) layer based on Maxwell’s equations with nonlinear boundary conditions on the surface of nonlinear loads (NL) was developed. A software package implementing this algorithm was created. Based on the results of numerical calculations of the program, the scattering diagrams of a metal cylinder with NL, covered with a layer of MM at the fundamental, second, and third harmonics were obtained. The dependences of the harmonics of the scattered field on the parameters of nonlinear loads were also studied. With the help of numerical simulation using Ansys HFSS, the extract procedure of the effective parameters of cylindrical MM was realized. Based on the results of calculation and numerical simulation, a model of a nonlinear cylindrical structure of two radii was made and an experimental study was carried out. As a result of the experiment, the frequency characteristics of the metastructure were obtained at various angles of incidence of the wave. The results of numerical simulation were confirmed by the results of the experiment. It is shown that the use of the provided nonlinear cylindrical marker with metamaterial makes it possible to obtain the levels of the first and second harmonics in a scattered field of the same order. This structure can be used as a nonlinear marker in both military and civilian areas.

Influences of Agrochemicals on Health and Ecology in Vietnamese Mango Cultivation

The study aims to identify risks of agrochemicals that impact farmworkers, consumers, and ecology in Vietnamese mango cultivation to enhance safety and friendly production. The study finds out the total numbers of root fertilizers (N-P-K) of the noncooperative and cooperative farmers are similar, approximately 1,400 kg/ha/year higher than those in other countries. Excessive fertilizer usage is a potential threat to soil, water, and air pollution. In addition, the findings indicate that the ecology component is undergoing the most negative impact from excessive agrochemical use in mango farming. The vast majority of agrochemicals in mango cultivation are fungicide and paclobutrazol over 90% of the total number of agrochemicals used in both noncooperative and cooperative farmer groups among the three seasons. Total field EIQ of the cooperative grower category is less than that of the noncooperative grower category. These results show that mango cultivation should consider rejecting the banned active ingredients of glyphosate, paraquat, and carbendazim as well as reducing fungicide and paclobutrazol usage and encouraging cooperative participation to safeguard the environment and human health. Moreover, science information needs to be closely linked and fed back to policy development to boost the management of the awareness of the ecological risks for farmers associated with reducing agrochemical use in mango cultivation.

On the Apparent Non-Uniqueness of the Electromagnetic Field Components of Return Strokes Revisited

Recent research work shows that there are four procedures that can be used to calculate the electromagnetic fields from a current source. These different procedures, even though producing the same total field, give rise to field components that differ from one procedure to another. This has led to the understanding that the various field terms that constitute the total field cannot be uniquely determined. In this paper, it is shown that all four field expressions can be reduced to a single field expression, and the various field terms arising from acceleration, uniformly moving, and stationary charges can be uniquely determined. The differences in the field terms arising from different techniques are caused by the different ways of summing up the contribution to the total electric field coming from the accelerating, moving, and stationary charges.

Using airborne vector magnetic data to calculate the projection of magnetic anomaly vector onto normal geomagnetic field

The total-field magnetic anomaly [Formula: see text] is an approximation of the projection [Formula: see text] of the magnetic anomaly vector [Formula: see text] onto the normal geomagnetic field [Formula: see text]. However, for highly magnetic sources, the approximation error of [Formula: see text] cannot be ignored. To reduce the error, we have developed a method for calculating [Formula: see text] by using airborne vector magnetic data based on the vector relationship of geomagnetic field [Formula: see text]. The calculation uses the magnitude of the vectors [Formula: see text], [Formula: see text], and [Formula: see text] through a simple approach. To ensure that each magnitude has the same level, we normalize the magnitude of [Formula: see text] using the total-field magnetic data measured by the scalar magnetic sensor. The method is applied to the measured airborne vector magnetic data at the Qixin area of the East Tianshan Mountains in China. The results indicate that the calculated [Formula: see text] has high precision and can distinguish the approximation error less than 3.5 nT. We also analyze the characteristics of the approximation error that are caused by the effects of different total magnetization inclinations. These error characteristics are used to predict the total magnetization inclination of a 2D magnetic source based on the measured airborne vector magnetic data.