Study on Structure Type and Operation Condition of UHVDC Wall Bushing

When the ±800kV UHVDC capacity is increased to 10000MW, the transmission current is 5kA and 6.25kA, which will put forward new requirements for the key technology of UHVDC through wall bushing: in UHV level, the key of through wall bushing lies in the research of basic technology of voltage sharing and field sharing. In the case of large current carrying capacity, the key lies in the basic technology research of current sharing and heat sharing. When the DC wall bushing, converter bushing and outgoing line device operate at the rated voltage, the central conductor is heated due to the carrying large DC current. Therefore, the temperature field distribution inside and at the tail of the bushing core is uneven, and the resistivity is the function of temperature, resulting in the change of resistivity with temperature and the change of potential and electric field distribution with resistivity during operation. Therefore, under the above high current operation conditions, in-depth key technology research is required for the design of bushing current carrying device, calculation of internal potential and electric field distribution, voltage sharing, field sharing, current sharing and heat sharing technology. The combined action of electrical and thermal stress will significantly affect the internal electric field distribution of converter transformer core and accelerate the aging rate of core composite insulation material, which introduces new research topic for the key technology of UHVDC converter bushing. The electric field and voltage distribution of UHVDC bushing are theoretically analyzed, the insulation structure is optimized from the aspects of material and structure, and the manufacturing process and the test technology are deeply and systematically studied.

Application of liquid and water-soluble special fertilizers and biostimulators in agropedocenoses of the forest-steppe zone

The value of foliar dressing is presented to achieve the maximum productivity of cultivated crops in agropedocenoses of the forest-steppe zone of the Russian Federation. When cultivating apple orchards in perennial agropedocenoses according to intensive technologies, the optimization of the nutritional regime is one of the most significant factors in obtaining a stably high crop yield of high-quality fruits. To fully provide apple trees with nutrient elements and growth biostimulators during the growing season, it is necessary to use special fat and water-soluble fertilizers and growth biostimulators. Most effectively, they are applied along the leaf surface as a foliar dressing. The leaf surface systems we developed and tested include the introduction of macro-, meso- and microelements and biological stimulating agents. The latter include various groups and types of amino acids, root, growth and development, flowering and setting, ripening and staining stimulating agents. The use of an integrated foliar dressing system has made it possible to provide the most complete need for apple trees with the necessary nutrients and compounds during the entire growing season. The obtained experimental data showed a high efficiency in changing a balanced system of foliar dressing in an intensive apple orchard. Compared to the control, there was a significant increase in the growth activity of the central conductor and fruit wood. Fruit setting rates, caliber and weight of apples and therefore more than 95% of the yield corresponded to the highest and first grade. The yield increased significantly compared to the control, it was from 28 to 66% for varieties and variants. Experimental studies showed high efficiency of foliar dressing with special fertilizers and growth biostimulating agents.

Load Matching for Giant Magnetoimpedance Sensor in Coaxial Configuration

Operation on the principle of the giant magnetoimpedace (GMI) magnetic field sensor was designed and tested for the case of CoFeSiB amorphous wire of 6 mm length. We considered magnetic field displacement of the order of 10 Oe. Piece of amorphous wire was placed as a central conductor of a coaxial cable. The maximum slope of the sensor GMI characteristic was observed at the terminator resistance RT = 50 Ohm, while the maximum of the GMI ratio variation was observed in the not “matched” (RT = 75 Ohm) but closer to the “short” mode. Amorphous wire placed as a central conductor of a coaxial cable serves as a sensitive element with high sensitivity with respect to applied field making possible to use a simple design with a miniature coil for magnetic field biasing.

Seismic Evaluation of Ultra-High Voltage Wall Bushing

A series of shaking table tests were carried out on a full-size polymer ultrahigh voltage wall bushing. In addition, a corresponding finite element model of the wall bushing was established. Four different earthquake ground motions—the El Centro, modulated Landers, Taft, and an artificial earthquake acceleration time history—were adopted in the study. Test results indicate that the safety factor of the wall bushing is less than the stipulated value of 1.67 in the Chinese code under the peak ground acceleration (PGA) of 2 × 0.4 g, where the factor 2 is used to simulate the amplification effect of the valve hall on the seismic responses of the wall bushing. Necessary slackness should be allowed for the conductors connected to the wall bushing because of the large displacement of the bushing terminals. There are relative displacements between the central conductor and polymer insulators during an earthquake. Increasing the out-of-plane stiffness of sealing plates at the terminals of the wall bushing could decrease the relative displacements. Moreover, a theoretical vibration model of the wall bushing was developed to demonstrate that the rocking effects of the installation plate and flange bottom plate have an influence on the seismic responses of the wall bushing.

The liver: conductor of systemic iron balance

Iron is a micronutrient essential for almost all organisms: bacteria, plants, and animals. It is a metal that exists in multiple redox states, including the divalent ferrous (Fe2+) and the trivalent ferric (Fe3+) species. The multiple oxidation states of iron make it excellent for electron transfer, allowing iron to be selected during evolution as a cofactor for many proteins involved in central cellular processes including oxygen transport, mitochondrial respiration, and DNA synthesis. However, the redox cycling of ferrous and ferric iron in the presence of H2O2, which is physiologically present in the cells, also leads to the production of free radicals (Fenton reaction) that can attack and damage lipids, proteins, DNA, and other cellular components. To meet the physiological needs of the body, but to prevent cellular damage by iron, the amount of iron in the body must be tightly regulated. Here we review how the liver is the central conductor of systemic iron balance and show that this central role is related to the secretion of a peptide hormone hepcidin by hepatocytes. We then review how the liver receives and integrates the many signals that report the body’s iron needs to orchestrate hepcidin production and maintain systemic iron homeostasis.

Repetitively pulsed high-current accelerators with transformer charging of forming lines

This article describes the principles of operation and the parameters of the SINUS setups designed at the Institute of High-Current Electronics, Siberian Division, Russian Academy of Science, over the period from 1990 to 2002. A characteristic feature of accelerators of the SINUS type is the use of coaxial forming lines (in particular, with a spiral central conductor) which are charged by a built-in Tesla transformer to produce the accelerating high-voltage pulses. This ensures a reasonable compactness and long lifetime of the setups.