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One of the main tasks of using remote sensing in agriculture for precision farming purposes is to identify management zones or management zones within which the timing and parameters of agrotechnical measures differ significantly. To clarify the boundaries of these zones, it is proposed to use jointly data on soil moisture (electrical conductivity) and the normalized plant index (NDVI) in a field of about 70 hectares. Based on spatial variations of humidity data obtained using a bistatic radar system and electrical conductivity obtained using electromagnetic scanning, as well as NDVI indices obtained using multispectral cameras, maps of the spatial distribution of these parameters are constructed. To determine the control zones, a fuzzy clustering algorithm was used, three target classes for assessing the state of plant biomass with restrictions on the percentage of moisture in the soil were identified. An analysis of 813 points of the soil surface was carried out with reference to geographical coordinates, the elements of the array were assigned to one of the target classes corresponding to one of the three control zones. The results of the analysis of arrays formed by classes allow us to conclude that it is possible to use fuzzy clustering to determine the boundaries of control zones in conditions of significant heterogeneity of the studied fields in terms of physico-chemical properties and relief.

The study of soil agrophysical and agrochemical properties is based on ground-based point measurements and measurements conducted using radiometric remote sensing systems (satellite or airborne). A disadvantage of the existing remote sensing systems using normal surface irradiation is the insignificant depth of penetration of the probing radiation into the soil layer. It is proposed to use a radar system for remote sensing agricultural lands to eliminate this drawback. The system uses a method for assessing the soil's physical and chemical properties based on the interference measurements of direct and reflected electromagnetic waves at incidence angles that provide a total refraction effect, i.e., close to Brewster's angle. The possibility of using this method for remote assessment of soil's physical and chemical properties, including the subsurface layer moisture, was established. A feature of the bistatic system is that it is necessary to coordinate the mutual arrangement of the transmitting and receiving positions, which imposes special requirements on the UAVs' flight algorithm. The UAVs' relative position makes it possible to form the conditions for the manifestation of the total refraction effect, to determine the current value of Brewster's angle, and to fix these conditions for the subsequent flight, making it possible to measure the soil's physical and chemical parameters. The research results can be used to implement precision farming technology in hard-to-reach places, large agricultural areas, and digital agriculture. [ABSTRACT FROM AUTHOR]

A multifrequency electron cyclotron resonance heating (ECRH) system is currently under construction at the ASDEX Upgrade tokamak experiment. The system employs depressed collector gyrotrons, step tunable in the range of 105-140 GHz, with a maximum output power of 1 MW and a pulse length of 10 s. One two-frequency GYCOM gyrotron has been in routine operation at ASDEX Upgrade since 2006. A further extension of the system with three more gyrotrons is underway. An in situ calibration scheme for the broadband torus window has been developed. The system is equipped with fast steerable mirrors for real-time MHD control. The gyrotron and the mirrors are fully integrated into the discharge control system. The ECRH system turned out to be essential for the operation of H-modes after covering the plasma facing components of ASDEX Upgrade with tungsten. Deposition of ECRH inside [[rho].sub.tor] < 0.2 is necessary to prevent accumulation of W in plasmas with high pedestal temperatures. With respect to the limited loop voltage available in ITER, the use of ECRH for neutral-gas preionization to facilitate plasma breakdown and its application during the current ramp-up to increase the conductivity in order to save transformer flux have been demonstrated successfully for 105 GHz, 3.2 T (O1-mode) and 140 GHz, 2.2 T (X2-mode), corresponding to 170 GHz at ITER with the full and half values of its foreseen toroidal field of 5.3 T. Index Terms--Electron cyclotron resonance heating (ECRH), fast steerable launcher, step-tunable Gyrotron.

A new multifrequency electron cyclotron resonance heating system is under construction for the Axially Symmetric Divertor EXperiment (ASDEX) Upgrade tokamak experiment. For the first time in a fusion device, this system employs multifrequency gyrotrons that are step-tunable in the range 105-140 GHz. In its final stage the system will consist of four gyrotrons with a total power of 4 MW and a pulselength of 10 s. The first two gyrotrons, working at 105 and 140 GHz, were installed and tested. Transmission line elements such as corrugated waveguides, polarizer mirrors and vacuum windows are designed to cope with this frequency band. The system includes fast steerable launchers at the front end that will allow for localized feedback-controlled power deposition in the plasma. Index Terms--Electron cyclotron resonance heating (ECRH), fast steerable launcher, step-tunable gyrotron.