Variability of CPT and tropopause characteristics over the Arabian Peninsula

. The climatology of the cold-point tropopause (CPT) and tropopause characteristics in a subtropical area like The Arabian Peninsula is examined using the radiosonde data of the CPT characteristics and NCEP Reanalysis data of the tropopause characteristics. The monthly mean data for January and July are analyzed for three stations, namely Medina, Tabuk and Dammam in Saudi Arabia. The trends of CPT and tropopause characteristics of pressure, height, temperature, temperature anomalies, relative humidity, wind speed and potential temperature are also analyzed. The trends of these characteristics show that they experienced a sharp change during the 1990s and a significant change for the period from 2000 to 2016. For the whole period of study, the month of July, CPT and tropopause pressure decreased for about 5 hPa, whereas the height increased for more than 100 m. The temperature experienced a sudden drop during the beginning of the 1990s and a smooth decrease during the following years in January. Furthermore, a strong correlation is found between the CPT temperature and the Solar Cycle during the ‘90s period then it decreased sharply after this period.

Investigation of Condensate Retention on Horizontal Pin-Fin Tubes Using Water-Propanol Mixture

Condensers are an integral part of air conditioning systems. The thermal efficiency of condensers solely depends on the rate of heat transfer from the cooling medium. Fin tubes are extensively used for heat transfer applications due to their enhanced heat transfer capabilities. Fins provide appreciable drainage because surface tension produces pressure gradients. Much research, contributed by several scientists, has focused on adjusting parameters, such as fin design, flow rates and retention angles. In this study, a setup with an observing hole was used to inspect the influence on retention angle of adjusting the flow rates of the fluid. The increase in retention angle was examined using several velocities and concentration mixtures. Pin-fin tubes were used to obtain coherent results using a photographic method. The experimental setup was designed to monitor the movement of fluid through the apparatus. The velocity was varied using dampers and visibility was enhanced using dyes. Photographs were taken at 20 m/s velocities after every 20 s. and 0.1% concentration and the flooding point observed. The experimental results were verified by standard observation which showed little variation at lower velocity. For water/water-propanol mixtures, a vapor velocity of 12 m/s and concentration ratio of 0.04% was the optimal combination to achieve useful improvement in retention angle. With increase of propanol from 0% to 0.04%, the increase in retention angle was greater compared to 0.04% to 0.1%. For velocities ranging from 0 to 12 m/s, the increase in retention angle was significant. A sharp change was observed for concentration ratios ranging from 0.01% to 0.05% compared to 0.05% to 0.1%.

The current state of hydrochemical indicators of Lake Kenon– the cooling reservoir of the TPP

A characteristic is given of the current hydrochemical state of the water of Lake Kenon, which is used as a reservoir - a cooler for the Chita TPP. For over 50-years of operation of the station located on its shore, under the conditions of anthropogenic impact, there has been a sharp change in the chemical type of the lakeʼs water. Currently, the predominant anion is the sulfate ion. Above the MPC standard for water of water bodies of fishery significance are the content of magnesium and sulfates and the trace elements: fluorine, vanadium, strontium, molybdenum, copper, tungsten. The concentrations of boron, lithium, bromine are relatively increased, in some samples - iron, manganese, aluminum and barium.

Diagnostics of the presence of a fatigue crack in the compressor blade using the spectrum of vibration amplitudes at the superharmonic resonance

In this study, the solution of the forced vibration response of a structural element with a fatigue crack was carried out using the finite element method to determine the influence of its presence on the flexural forced vibration behaviour of the compressor blade airfoil at the superharmonic resonance of the order 1/2. The blade airfoil with a low twisted angle was used as an object of investigation to perform the computational analysis. Its vibrations in the plane of minimum stiffness were excited by the kinematic displacement of root edge elements. The fatigue crack was modelled as a mathematical cut. Two locations of the crack were investigated – on the leading edge and convex side of the blade airfoil. The nonlinearity due to the intermittent contact of the crack surfaces, which is caused by the opening and closing of the crack during each vibration cycle, was taken into account by solving the contact problem. To quantify this kind of nonlinear dynamic behaviour, the vibration diagnostic parameter was defined as the displacement amplitude ratio of the dominant harmonics at the superharmonic resonance of the order 1/2. Based on the results of the calculations it has been found that regardless of the crack location, the ratio nature is the same for all vibration axes. However, with vibrations in the plane of minimum stiffness, the crack on the convex side of the airfoil has an opening mode propagation, which makes it possible to fix its location due to a sharp change in the ratio of the amplitudes of the dominant harmonics along the corresponding axis.

Reducing the hydrodynamic force in the hydraulic distributor by modernizing the spool coupe parts

Due to a sharp change in the direction and velocity of the fluid flow in the hydraulic distributor, hydrodynamic forces arise. When positioning and holding the spool, the magnitude of the above forces determines the required control power. The aim of the article was to find an optimal constructive solution that would reduce the influence of hydrodynamic forces. In the article we have considered the theoretical foundations laid in the analytical solution of the problem of calculating the magnitude of the hydrodynamic force acting on the plunger of the spool. In addition, a numerical experiment was carried out using CAD Solidworks and the Flow Simulation application package and a comparison of the results obtained with the analytical solution of the problem. During the numerical experiment, it was found that by upgrading the spool sleeve, it is possible to reduce the value of the hydrodynamic force by 4.5 times, compared with the original design. At the same time, it was found that the modernization of the plunger does not further reduce the maximum hydrodynamic forces. The article highlights the economic benefits of reducing the required power to control the hydraulic distributor. The article may be of interest to both researchers whose research interests lie in the field of hydrodynamics, and manufacturers of hydraulics.

The Effect of Climate Changes on The Fluctuation of The Water Level of Al- Razzaza Lake, Iraq

One of the serious environmental challenges that Iraq faces is climate changes and impacts of changing weather patterns and extreme global weather events. This paper addresses changes in the temporal and spatial characteristics of water levels of Razzaza Lake and response to climatic changes using archived series of Multispectral satellite images Landsat. TM, ETM+ and OLI images acquired on 1990, 2000 and of 2016. In order to extract, mapping the water surface area of the Razzaza Lake, Multispectral spectral band rationing the Normalized Difference Water Index (NDWI) technique was adopted, and the climatic elements data for the period (1990-2016) were analyzed which provide significant information of surface water. The results show that Razzaza Lake has a particularly sharp change rate in the water level and there are significant fluctuations on lake level and water surface area over the time.

Drawing and Painting for Future Graphic Designers in the Conditions of Distance Learning

Strict quarantine restrictions related to the Covid-19 pandemic have significantly changed the social reality. The pandemic has become a catalyst for a significant number of processes that have affected all areas of human activity, including education. The learning process in the extreme mode was transferred into a distance format, which, on the one hand, was a better solution than its termination. On the other hand, a sharp change in the format of education has particularly affected practice-oriented and creative disciplines. The advantages and disadvantages of this approach are considered in this article on the example of the discipline "Drawing and Painting", by observing the results of its teaching in the online format. The purpose of the study is to identify ways to adapt the methodology of teaching the discipline "Drawing and Painting" to the conditions of quarantine, to identify opportunities for new educational and communication online platforms in the art process, while not losing the classic tradition of mastering the basics of visual literacy. When students have direct contact with the teacher. Research methodology. The author, based on their own practical experience of a professional artist, analyzes the advantages and disadvantages of online learning and determines the direction of solving problems identified in the implementation of the discipline program “Drawing and Painting” in a distance format. The scientific novelty of research lies in the following aspects: expansion of ideas about the peculiarities of teaching art disciplines in the extreme mode of the pandemic, identifying the specifics of transferring traditional teaching methods to distance learning platforms, new structuring of the curriculum "Drawing and Painting". Conclusions. It is proved that distance technologies cannot replace all other methods and types of teaching in the discipline "Drawing and Painting" and should be considered only as an effective addition to traditional methods. We conclude that the main part of practical classes, where an important task is the formation of students’ motivation, professional values and independent non-stereotypical thinking, cannot be carried out without live communication between teacher and student.

Theoretical Analysis of Entropy Generation at the Blade Interface of a Tubular Turbine Under Cooperative Conditions

To study the influence of the blade entropy production range on the efficiency of a tubular turbine under coassociated conditions, the renormalization group K–ε turbulence model was used to simulate the full flow passage of the tubular turbine based on the Navier–Stokes equation, and the blade interface was analyzed using the eddy analysis method and entropy production theory. The results reveal that there is a strong correlation between the size of the high-entropy production area and the level of association. If the level of association is high, the size of the high-entropy production is small, and the turbine efficiency is high. Furthermore, if the level of association is low, the size of the high-entropy production area is large, and the turbine efficiency is low. Under small opening and small flow conditions, the blade entropy generation is due to the sharp change in the velocity gradient caused by the vortex on the blade. Under large opening and large flow conditions, the blade entropy production is mainly due to the friction loss caused by the impact of high-speed water flow.

Evaluation of the thermal stability of composite powder materials in a plasma jet

The results of studies of the thermal stability of materials operating in a plasma jet at high temperatures and a sharp change in thermal loads are presented. It has been proven that the use of plasma generators with the introduction of various powder materials makes it possible to simulate the operating conditions of parts in high-temperature gas flows with heated particles. The effect of the introduced powder materials on the thermal stability of samples prepared by plasma spraying from molybdenum, as well as tungsten and tungsten-based compositions is investigated. An installation is proposed for assessing the thermal stability of composite materials and protective hardening coatings operating under high-temperature gas flows, which makes it possible to determine their erosion resistance.

Formation of an Innovative Business Model of a Trade Organization in the Context of Economic Globalization

The development of Ukrainian trade organizations in ordinary conditions is characterized by a high degree of inertia. Therefore, when situations that need to change arise, business strategies of market participants also change dramatically. Most often, such transformations are connected with external factors, such as the overall economic crisis, a sharp change in the state “rules of the game” in a particular sector of economic relations, as well as another external factor bond to the occurrence of new serious competitors. The development of organizational and economic mechanism to ensure the innovative development of retail trade, requires comprehensive consideration of internal and external factors of the studied system, the formation of strategies and programs to increase the innovation potential of its participants, their active interaction, increasing the use of innovative technologies, generating ideas and transformations. The article considers the issues related to the impact of business globalization processes on the transformation of business models of trade organizations and their operation strategy, as the degree of trade development indicates the standard of living and the state of the economy and society. The authors of the article suggest that retail organizations adapt to the changes in the macro and micro environment, using innovative components in economic and financial activities, which will ensure their competitiveness and prevent crises. The proposed model of an innovative trade organization allows to identify the goals components of innovation activities, which combine the strategic guidelines of the state regulation and help to improve the economic condition of trade organizations