Investigation of the hydrodynamic impact of a planing small vessel on a water body

Рассмотрен экологический аспект использования маломерных глиссирующих судов. В статье представлен способ оценки характеристик потока, возмущённого движением глиссирующего судна. Способ основан на использовании численного метода гидродинамики. Выбраны параметры и зоны исследования потока вокруг корпуса рассмотренного судна, и разработана последовательность действий их определения. Проанализированы качественные картины изменения потока с ростом скорости глиссирующего судна с заданной геометрией, и выделены составляющие наиболее значимые составляющие. Оценены количественные характеристики возмущённого потока: вызванные скорости, расстояние от транца до точки зарождения системы волн, волновые характеристики. Оценка гидродинамического воздействия на водоём была проведена для двух притоков Волги – р.Керженец и р.Сура. Выполнено определение придонных касательных напряжений в выбранных водных объектах в их естественном и возмущённом присутствием судна состоянии. Проведено сравнение рассчитанных касательных напряжений с пороговыми значениями, что позволило оценить влияние движения маломерного судна на донный грунт. The ecological aspect of the use of small-sized planing vessels is considered. The article presents a method for assessing the characteristics of a flow disturbed by the movement of a planing vessel. The method is based on the use of the numerical method of hydrodynamics. The parameters and zones of the flow study around the hull of the vessel under consideration are selected, and a sequence of actions for their determination is developed. Qualitative patterns of flow changes with an increase in the speed of a planing vessel with a given geometry are analyzed, and the most significant components are identified. Quantitative characteristics of the perturbed flow are estimated: induced velocities, distance from the transom to the point of origin of the wave system, wave characteristics. The assessment of the hydrodynamic impact on the reservoir was carried out for two tributaries of the Volga - the Kerzhenets River and the Sura River. The determination of bottom tangential stresses in selected water bodies in their natural and disturbed state by the presence of the vessel was performed. The calculated tangential stresses were compared with threshold values, which made it possible to assess the impact of the movement of a small vessel on the bottom soil.

Trends of Scots pine forest health and element flow changes in the ICP Forests monitoring sites in Latvia

Scots pine (Pinus sylvestris L.) is one of the most widespread and economically most important tree species in Latvia. Scots pine forest health and element flow changes have been monitored in Latvia within the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) with assessment of crown condition and damaging agents at 115 Level I monitoring sites (mostly oligothrophic and mesotrophic Vacciniosa, Myrtillosa and Hylocomiosa forests) and with sampling and analyses of environmental samples at three Level II monitoring sites representing typical Scots pine forests (Myrtillosa) in hemiboreal conditions in Latvia. This study summarizes the background information and presents the trends of forest health, carbon turnover and environment condition in Scots pine forest since 2009. In general, defoliation rate in Scots pine stands remains stable for the studied period, with some yearly fluctuations, possibly related to regional insect outbreaks, especially well demonstrated in two Level II plots. The share of damaged trees varied by year from 12.8% to 19% of the total number; the main cause of damage was direct action of man. Chemical element flows in Scots pine forests in Level II monitoring plots have been relatively stable as well except the decreasing trend in total N concentration in deposition and SO4-S concentration in soil solution and increasing trends in DOC concentration in soil solution that is in line with common trends in Europe. Carbon input with above-ground litter was relatively stable during the whole period; however, interannual variations were rather wide.

Influence of mechanical action on the development of electrodynamic phenomena in ionized gas

A special feature of this work is the study of the effect of mechanical mode disturbances on the discharge and plasma flow. It is found that the mechanical impact of a shock wave in a dense gas in an electric field of high intensity almost to the ignition voltage causes an electrical “breakdown” as current peaks. The ultrasonic effect on the flow of the reacting plasma of the air as shown by the analytical study of the thin layer of the plasma flow changes the type of flow.

Identifying Tourists as Stakeholders in Destination Marketing Cooperation:

Recent studies began to notice the significance of taking tourists into destination stakeholders, because the essence of destination is the primary place for tourist consumption. With empirical experience from a case study in Jing-Jin-Ji region, China, this paper classifies tourists’ stakeholder type as Dominant Stakeholders in destination marketing cooperation within Mitchell’s salience theory’ typology according to their salience attributes of legitimacy and urgency. Then, to explore factors influencing the success of cooperation from tourist stakeholder’s perspective, this paper analyzes tourist flow changes responding to the progress of destination marketing cooperation, and further understands these factors with the support of interviews with tourist’s group and other critical stakeholders. Finally, three major factors are found including the priority of tourism industry to destination governments, the priority of tourism cooperation to destination marketing organizations, and involvement of tourism enterprises in cooperation.

Doppler Ultrasonography of the Fetal Tibial Artery in High-Risk Pregnancy and Its Value in Predicting and Monitoring Fetal Hypoxia in IUGR Fetuses

Background and Objectives: Intrauterine growth restriction (IUGR) is the term used to describe a fetus whose estimated weight is less than the 10th percentile of its age growth curve. IUGR is the second most common cause of perinatal death. In many cases there is a deficiency in the standardization of optimal management, prenatal follow-up and timing of delivery. Doppler examination is the most sensitive test that can assess the condition of the fetus and indicate fetal intrauterine hypoxia. Numerous studies of the fetal intrauterine state focus on the umbilical artery and the fetal cerebral blood vessels, while the peripheral arteries have so far received insufficient attention. Materials and Methods: We present a case of an IUGR fetus monitored with a non-stress test (NST) and a Doppler examination of the fetal arteries (tibial, umbilical, middle cerebral and uterine) and the ductus venosus. In this case the first early sign of fetal hypoxia was revealed by blood flow changes in the tibial artery. Results: We hypothesize that peripheral vascular changes (in the tibial artery) may more accurately reflect the onset of deterioration in the condition of the IUGR fetus, such that peripheral blood flow monitoring ought to be employed along with other techniques already in use. Conclusion: This paper describes the clinical presentation of an early detection of late IUGR hypoxia and claims that blood flow changes in the tibial artery signal the worsening of the fetus’s condition.

Contributions of Human Activities and Climatic Variability to Changes in River Rwizi Flows in Uganda, East Africa

This study employed Soil and Water Assessment Tool (SWAT) to analyze the impacts of climate variability and human activities on River Rwizi flows. Changes in land use and land cover (LULC) types from 1997 to 2019 were characterized using remotely sensed images retrieved from Landsat ETM/TM satellites. SWAT was calibrated and validated over the periods 2002–2008 and 2009–2013, respectively. Correlation between rainfall and river flow was analyzed. By keeping the optimal values of model parameters fixed while varying the LULC maps, differences in the modeled flows were taken to reflect the impacts of LULC changes on rainfall–runoff generation. Impacts due to human activities included contributions from changes in LULC types and the rates of water abstracted from the river as a percentage of the observed flow. Climate variability was considered in terms of changes in climatic variables such as rainfall and evapotranspiration, among others. Variability of rainfall was analyzed with respect to changes in large-scale ocean-atmosphere conditions. From 2000 to 2014, the portion of River Rwizi catchment area covered by cropland increased from 23.0% to 51.6%, grassland reduced from 63.3% to 37.8%, and wetland decreased from 8.1% to 4.7%. Nash–Sutcliffe Efficiency values for calibration and validation were 0.60 and 0.71, respectively. Contributions of human activities to monthly river flow changes varied from 2.3% to 23.5%. Impacts of human activities on the river flow were on average found to be larger during the dry (14.7%) than wet (5.8%) season. Using rainfall, 20.9% of the total river flow variance was explained. However, climate variability contributed 73% of the river flow changes. Rainfall was positively and negatively correlated with Indian Ocean Dipole (IOD) and Niño 3, respectively. The largest percentages of the total rainfall variance explained by IOD and Niño 3 were 12.7% and 9.8%, respectively. The magnitude of the correlation between rainfall and IOD decreased with increasing lag in time. These findings are relevant for developing River Rwizi catchment management plans.

Utility of the Color-Coded Duplex Neurosonographic Spectrum in Critically Ill Children in Resource-Limited Centers: A Case Series

Ultrasound in pediatric neurocritical care has a wide variety of indications, such as the study of vasospasm in subarachnoid hemorrhage, flow changes in intracranial stenosis, endocranial hypertension and to evaluate some therapeutic measures. The following is a series of five most relevant cases collected from Pediatric Intensive Care with abnormal images in transcranial duplex (TCD) and their typical findings in this type of studies. Transcranial duplex offers a diagnostic method of rapid evaluation that provides reliable information for decision making in pediatric intensive care, but it is a tool with which there is little experience in the country, so these findings are didactic and should be complemented with studies of greater diagnostic relevance.