Offshore Wind Energy Conversion System Connected to the Electric Grid: Modeling and Simulation

This paper is on modeling and simulation for an offshore wind system equipped with a semi-submersible floating platform, a wind turbine, a permanent magnet synchronous generator, a multiple point clamped four level or five level full-power converter, a submarine cable and a second order filter. The drive train is modeled by three mass model considering the resistant stiffness torque, structure and tower in deep water due to the moving surface elevation. The system control uses PWM by space vector modulation associated with sliding mode and proportional integral controllers. The electric energy is injected into the electric grid either by an alternated current link or by a direct current link. The model is intend to be a useful tool for unveil the behavior and performance of the offshore wind system, especially for the multiple point clamped full-power converter, under normal operation or under malfunctions

ОЧЕРКИ ХИРУРГИЧЕСКОГО ЛЕЧЕНИЯ ГАСТРОЭЗОФАГЕАЛЬНОЙ РЕФЛЮКСНОЙ БОЛЕЗНИ

The most important historical stages of formation of scientific ideas of gastroesophageal reflux and its complications are presented in the article; the main milestones in the development of gastroesophageal reflux disease surgery are reflected.Рассмотрены наиболее важные исторические этапы формирования научных представлений о желудочно-пищеводном забросе и его осложнениях, отражены основные вехи развития хирургии гастроэзофагеальной рефлюксной болезни

Surgical treatment of types I–IV hiatal hernias

The article presents modern ideas of types II–IV hiatal hernias as a variant of visceral anatomical abnormality. The latest techniques of surgical removal of hiatal hernias aimed at improving the results of surgical treatment are described in this article

UNRESOLVED ISSUES OF SURGICAL TREATMENT OF GASTROESOPHAGEAL REFLUX DISEASES

The  paper highlights  the  main  issues of  prevalence, pathogenesis  and  diagnosis of  gastroesophageal reflux  disease. The  principles   and  key  problems of  surgical   treatment of  this  pathology are  highlighted

INFLUENCE OF FERTILIZERS ON ACCUMULATION OF HEAVY METAL IN SOIL AND PHYTO MASS OF GRAIN CROPS

It’s common knowledge that heavy metal (HM) can enter the soil together with fertilizers which contaminates agricultural landscapes. The purpose of the research is to study influence of fertilizers on accumulation and migration of Cd, Pb ,Zn, Cu, Co, Mn in soil and plants. The research was conducted during field experiments in chernozem (blacksoil). We studied two levels of plant fertilizing: the first one without fertilizers and the second one with fertilizing of norms of NPK. The fertilizers were distributed in the following way: spring wheat (Triticum vulgare) – N60P60K60; spring barley (Hordeum vulgare) and oats (Avena sativa) – N45P45K20; millet (Panicum miliaceum) – N30P40K40; peas (Pisum sativum) – N10P60K60; buckwheat (Fagopyrum esculentum) – N45P60K60.v We found out that fertilizing raises the amount of Сd, Рb Zn, Сu, Со and Мn on 10-36% in soil and increases mobility of Zn, Си, Со and Мn on 25%. The increase of fertilizing of spring wheat, barley, oats, millet and buckwheat reduces whole volume of HM migration in phyto mass on 5-30%.  But it also stimulates Pb migration in the plants of spring wheat, migration of Сd, Zn and Сu into bio mass of oats and barley, and migration of Cd and Mn into peas. The main portion of accumulated elements is stored in a root system of a plant, Zn and Cu are able to transport into inflorescence. The volume of HM accumulation in phyto mass of fertilized plants doesn’t exceed TLV

Soil salinity mapping by different interpolation methods in Mirzaabad district, Syrdarya Province

Abstract Soil salinity is an important global issue and especially on irrigated areas due to its great impact on a crop production system. Proper soil salinity mapping can improve land use management. The goal of this study was to improve the accuracy of soil salinity mapping with the two objectives (1) to evaluate different interpolation methods during soil salinity mapping and (2) to identify of differences in soil salinity assessments in irrigated land of Mirzaabad district which is most affected by salinity in Syrdarya province of Uzbekistan. Soil salinity data measured by EC meter was obtained from Syrdarya Hydromelioration Expedition. Different four interpolation methods such as Inverse Distance Weighted (IDW) with power 1, 2, and 3, and Kriging techniques were used for the generation continuous surface of soil salinity maps. The cross-Validation method with the assessment of Root Mean Square Errors (RMSE) shows that IDW with power 2 (IDW-2) most accurate. The maximum difference reached between IDW-2 and IDW-1 on the slightly saline area where the value decreased by 55% of the total irrigated land of the district. Minimum differences reached on IDW-3 on moderated saline class and higher than IDW-2 on 408.6 ha.</jats:p