Light Winds Research Articles

Building stationary gas emissions concentration fields in the areas impacted by non-ferrous metals producers

This paper looks at the gas emissions balance in the wind corridor along the wind direction. An equation was found that describes the dependence of the emissions concentration inside the wind corridor along the wind direction when the concentration inside the wind corridor at the right angle to the wind flow is uniform. The authors propose a system of diffusion equations and its solution in a quasi-steady state for determining the concentration field in the whole space. It is shown that the transfer distance ratio has an approximate correspondence to the diffusion scope in the overall concentration. The diffusion scope was found to not exceed 0.01 %. And it becomes even lower as the wind speed rises and the time interval extends for which the diffusion transfer is analyzed. That’s why the wind transfer process can serve as a sufficient factor of changing concentration. To create a mathematical image of the concentration field for a given pollutant in the geographical coordinates, apart from the emission intensity and the chemical activity of such pollutant in air, one needs to know the wind rose of the region where the production site is situated. This helps determine the relationship between the maximum concentration of the pollutant and the distance (from the source of emission) in eight geographical directions, in eight points of the wind rose. It is noted that the use of the wind rose for mapping full information on the distribution of each pollutant helps superpose the fields of the maximum allowable concentrations (maximum hazard) of each pollutant with the geographical map of a particular production site. A relationship was defined between the maximum concentration of the pollutant and the source of emissions. The paper also describes the results of a study that looked at the transfer of emissions in air and determined the maximum distance for the maximum allowable concentration of sulphur dioxide emitted by Nornickel’s Norilsk site. It is demonstrated that when a light northeast wind blows (the average speed is around 3 m/sec), the SO2 concentration in the northeast sector of the wind rose along the wind path is likely to exceed the maximum allowable mean daily concentration as far as 2,500 km from the site.

Disentangling the roles of electric fields and wind in spider dispersal experiments

Observations of spiders' pre-dispersal behavior can be used to answer various ecological and evolutionary questions. So far, dispersal experiments have often used air currents as a stimulating factor. Effects of electric fields on the pre-dispersal behavior of spiders have recently been discovered. Electric fields may lead to unexplained variation in results and limit comparability between previous studies. Here we aim to disentangle the roles of wind and electric fields on the passive aerial dispersal of three linyphiid spider species. Our results confirm that strong electric fields in the air elicit pre-dispersal behavior, and in combination with a light wind, facilitate dispersal (take-off). Nevertheless, even the strong electric fields employed here played a rather supplementary role in spiders' dispersal with wind remaining the most influential factor. We recommend that studies of passive aerial dispersal should control for electric field strength but otherwise use wind as the primary stimulating factor.

A Comprehensive Analysis of Light Weight Steel Structure and Wind Load

Review to hot-rolled steel structures, cold-formed steel structures are susceptible to extreme winds because of the light weight of the building and its components. Many modern cold-formed steel structures have sustained significant structural damage ranging from loss of cladding to complete collapse in recent cyclones. This article first provides Review some real damage cases for light steel structures induced by the high winds. After that, the paper reviews research on the damage analysis and evaluation of light steel structures caused by strong winds, which include connection failure, fatigue failure, purlin buckling, and primary frame component instability problems. Moreover, this review will mention some applications of structure damage assessment methods in this area, such as vulnerability analysis and performance-based theory, etc.

Enhanced Turbulence in the Upper Mixed Layer Under Light Winds and Heating: Implications for Gas Fluxes

AbstractMeasurements of turbulence, as rate of dissipation of turbulent kinetic energy (ε), adjacent to the air‐water interface are rare but essential for understanding of gas transfer velocities (k) used to compute fluxes of greenhouse gases. Variability in ε is expected over diel cycles of stratification and mixing. Monin‐Obukhov similarity theory (MOST) predicts an enhancement in ε during heating (buoyancy flux, β+) relative to that for shear (u*w3/κz where u*w is water friction velocity, κ is von Karman constant, z is depth). To verify and expand predictions, we quantified ε in the upper 0.25 m and below from profiles of temperature‐gradient microstructure in combination with time series meteorology and temperature in a tropical reservoir for winds <4 m s−1. Maximum likelihood estimates of near‐surface ε during heating were independent of wind speed and high, ∼5 × 10−6 m2 s−3, up to three orders of magnitude higher than predictions from u*w3/κz, increased with heating, and were ∼10 times higher than during cooling. k, estimated using near‐surface ε, was ∼10 cm hr−1, validated with k obtained from chamber measurements, and 2–5 times higher than computed from wind‐based models. The flux Richardson number (Rf) varied from ∼0.4 to ∼0.001 with a median value of 0.04 in the upper 0.25 m, less than the critical value of 0.2. We extend MOST by incorporating the variability in Rf when scaling the influence of β+ relative to u*w3/κz in estimates of ε, and by extension, k, obtained from time series meteorological and temperature data.

Structural Stability Study of C/GFRP Composite material Traffic Light Fixture and Wind Load

Structural Stability Study of C/GFRP Composite material Traffic Light Fixture and Wind Load

PEMANFAATAN PANAS MATAHARI PADA DINDING LUAR BANGUNAN SEBAGAI SUMBER ENERGI LISTRIK MENGGUNAKAN GENERATOR TERMOELEKTRIK

This research utilizes solar thermal energy that absorbed by the outer wall of the building which facing north. The heat energy is converted into electrical energy using a thermoelectric generator type TEC 12706. To maintain the cold side area of TEC 12706 heatsinks are circulated with circulating water cooling fluid with a discharge of 1.8 lpm and the temperature is not more than 3oC. The study was conducted with a simulation tool composed of several materials such as glass, aluminum, styrofoam and heatsink. The test is conducted from 06.00 WIB until 18.00 WIB for 3 days. The parameters measured are light intensity, wind speed, water flow, temperature, electric voltage and electric current contained in the test equipment. The research results get a maximum output power of 0.0024 W, thermoelectric efficiency and system efficiency.

Drone measurements of surface-based winter temperature inversions in the High Arctic at Eureka

Abstract. The absence of sunlight during the winter in the High Arctic results in a strong surface-based atmospheric temperature inversion, especially during clear skies and light surface wind conditions. The inversion suppresses turbulent heat transfer between the ground and the boundary layer. As a result, the difference between the surface air temperature, measured at a height of 2 m, and the ground skin temperature can exceed several degrees Celsius. Such inversions occur very frequently in polar regions, are of interest to understand the mechanisms responsible for surface–atmosphere heat, mass, and momentum exchanges, and are critical for satellite validation studies. In this paper we present the results of operations of two commercial remotely piloted aircraft systems, or drones, at the Polar Environment Atmospheric Research Laboratory, Eureka, Nunavut, Canada, at 80∘ N latitude. The drones are the Matrice 100 and Matrice 210 RTK quadcopters manufactured by DJI and were flown over Eureka during the February–March field campaigns in 2017 and 2020. They were equipped with a temperature measurement system built on a Raspberry Pi single-board computer, three platinum-wire temperature sensors, a Global Navigation Satellite System receiver, and a barometric altimeter. We demonstrate that the drones can be effectively used in the extremely challenging High Arctic conditions to measure vertical temperature profiles up to 75 m above the ground and sea ice surface at ambient temperatures down to −46 ∘C. Our results indicate that the inversion lapse rates within the 0–10 m altitude range above the ground can reach values of ∼ 10–30 ∘C(100m)-1 (∼ 100–300 ∘Ckm-1). The results are in good agreement with the coincident surface air temperatures measured at 2, 6, and 10 m levels at the National Oceanic and Atmospheric Administration flux tower at the Polar Environment Atmospheric Research Laboratory. Above 10 m more gradual inversion with order-of-magnitude smaller lapse rates is recorded by the drone. This inversion lapse rate agrees well with the results obtained from the radiosonde temperature measurements. Above the sea ice drone temperature profiles are found to have an isothermal layer above a surface-based layer of instability, which is attributed to the heat flux through the sea ice. With the drones we were able to evaluate the influence of local topography on the surface-based inversion structure above the ground and to measure extremely cold temperatures of air that can pool in topographic depressions. The unique technical challenges of conducting drone campaigns in the winter High Arctic are highlighted in the paper.

Computer Mathematical Statistics and Comparative Analysis of Meteorological Conditions in the Bohai Rim Region through Big Data Digitization

Based on the data of environmental monitoring stations and meteorological stations in typical city in the Bohai Rim region in June 2021 and June 2020. The air quality in June 2021 was better than that in the same period in 2020. Ozone (O3) was the primary pollutant in June 2021 and June 2020. The overall meteorological conditions in May 2021 were relatively favorable. In June 2021, the number of light wind days and wind speed had no significant impact on air quality compared with the same period last year. The dominant wind direction in June 2021 was southeast wind, which was not conducive to the increase of ozone concentration compared with the southwest wind frequency in the same period in 2020; the relative humidity in June 2021 was slightly higher year-on-year, which was slightly conducive to the hygroscopic growth of pollution; the static stability index in June 2021 was lower year-on-year, and the weather conditions for comprehensive pollution diffusion were preferred year-on-year; the height of the mixed layer in June 2021 was lower year-on-year, the vertical diffusion weather conditions were deviated year-on-year; the average temperature, sunshine hours and total radiation in June 2021 were all low, which was not conducive to the generation of ozone.

Microclimatic factors and soil characteristics of Arroceros Forest Park in the City of Manila, Philippines

Abstract. Berame JS, Elazegui EP, Arenas MC, Orozco JA. 2021. 2021. Microclimatic factors and soil characteristics of Arroceros Forest Park in the City of Manila, Philippines. Biodiversitas 22: 4956-4962. Microclimatic factors affect many ecosystem functions. However, the challenge of acquiring consistent data has impeded the quantitative assessment of the spatial heterogeneity of soil-climate in Arroceros Forest Park as an artificial urban forest park known as the last lung of the City of Manila. With this unassisted urban forest park, this study aims to determine the microclimatic factors such as light intensity, air temperature, air humidity, wind speed and direction, soil temperature, soil pH, percent organic matter, percent soil moisture and soil texture by using a sieve analysis and textural triangle method to know the status of the forest park. These procedures reveal the soil type available in the park to be clay and loam suitable for growing plants abundantly. Results showed that four microclimate factors viz. air temperature, air humidity, percent organic matter, and soil texture, were highly significant (p<0.000). Additionally, it further revealed that microclimatic factors such as light intensity, wind speed, and soil pH are essential in an ecosystem. It also found that soil size is a significant parameter for soil characterizations in this kind of study. Finally, the division of soil microsites into different positions based on prevailing light or shade conditions helped assess the significant variations of soil characteristics and conditions within the study area.

Seasonality modulates wind-driven mixing pathways in a large lake

Turbulent mixing controls the vertical transfer of heat, gases and nutrients in stratified water bodies, shaping their response to environmental forcing. Nevertheless, due to technical limitations, the redistribution of wind-derived energy fuelling turbulence within stratified lakes has only been mapped over short (sub-annual) timescales. Here we present a year-round observational record of energy fluxes in the large Lake Geneva. Contrary to the standing view, we show that the benthic layers are the main locus for turbulent mixing only during winter. Instead, most turbulent mixing occurs in the water-column interior during the stratified summer season, when the co-occurrence of thermal stability and lighter winds weakens near-sediment currents. Since stratified conditions are becoming more prevalent –possibly reducing turbulent fluxes in deep benthic environments–, these results contribute to the ongoing efforts to anticipate the effects of climate change on freshwater quality and ecosystem services in large lakes.

Easy Potatoes for Two

Easy Potatoes for Two William Millar (bio) All he'd wanted was sex. Now he was preparing their supper. Bending over the old sink was making his back ache. But there were only a few potatoes left to peel. The baby stirred in its cot behind the screen at the back of the kitchen, until the gentle susurration of its breathing began once more. Hardly audible. It hadn't been asleep for long. Actually, life's what stomps on your head when you're not paying enough attention. Get it right, John. It's okay to admonish the dead. Don't let anyone tell you otherwise. There was still a bruised, puzzled look behind his eyes. Like that of the victim of a mugging. Maybe it would always be there. Pigeons chuckled in their cool, bubbling way on the ledge outside the window at the back of the sink. They shat on the stone all the time. He shooed at them. They clattered off. You win for now but we'll be back. We'll always be back. [End Page 55] Leaves blew across the communal grass down at ground level. Light rain. Light wind. Darkening sky. He liked this time of year. There was something French about it. It suited his mood. He'd parked the pram in the stairwell earlier after returning from father and son's daily outing. He'd once pushed it to the timber store to buy wood to build bookshelves, then all the way home again with the baby peeking out from behind the planks. Mothers had given him strange looks. The skin slid off easily under the knife, curling away with little concretions of soil, browning the water. . . . to have and to hold, from this day forward, for better, for worse, for richer, for poorer, in sickness and in health, to love and to cherish, till death do us part. . . He'd affirmed it all. Christ. At the rehearsal the minister had taken him aside and suggested he might pray for forgiveness. He'd politely but firmly declined. He'd wanted to tell the fat prick to fuck off, but it wasn't the right time. He'd keep though. On the day, tailcoats had been worn. Champagne drunk. A reception line, for God's sake. Toasts and speeches. All the proprieties. But no shotgun. The decision had been his after all. His alone. The first day she went out to work while he looked after the baby, a blackbird came down the chimney, entering the room via the old kitchen fireplace. The first day. It had a broken wing and flapped around depositing soot everywhere, or so it seemed. He'd killed it eventually before wrapping it in newspaper and putting it in a waste bag. The rest of the day was spent cleaning. Soot can really mess up a room. He'd blocked up the chimney that night. [End Page 56] The tiny child, blue-eyed with its little slick of golden hair, looked at him on occasion, looked at him as if he was the most wonderful creature in the world. Sometimes he wanted to put a pillow over its face until it just stopped its noise. He'd been present at the birth. Held her hand while she pushed. It hadn't been a long labour. And he'd felt no great outflow of emotion at the arrival, just mild curiosity. She'd been nauseous, so he'd eaten her hospital toast and drunk her hospital tea. Out of the sink with them now. Cut them in half and into the pan. In the mornings when it was asleep, he would often run down to the baker's for a scone and then the shop next door for a newspaper. He reckoned four minutes maximum. Nothing could happen in four minutes he told himself. That wasn't true and he felt guilty. Guilt was all he seemed to feel these days. Guilt for quitting a potential career. Guilt for getting her pregnant. Guilt for thinking of shuffling off this mortal fucking coil. Guilt for the dark, complex feelings he had which he didn't understand but which fucked him...

Characteristics of climate extremes in China during the recent global warming hiatus based upon machine learning

AbstractDuring 1998–2013, global surface air temperature increased more slowly than greenhouse gas concentrations, and therefore this period was defined as a “global warming hiatus.” The characteristics of climate extremes in China during this period are still not clear. In this study, based on 2,841 meteorological station observations in China, the trends of precipitation and temperature extremes during the global warming hiatus were investigated relative to the reference period (RF) (1982–1997) and the whole historical period (HIS) (1982–2017). Machine learning was used to capture the nonlinear regression of climate extremes, and the Theil–Sen method with the Mann–Kendall significant test was used to calculate the slopes of their linear trends. During the global warming hiatus, annual and summer (JJA) warmest days TXx and the number of summer days SU over the whole of China and most of its four subregions were found to decrease relative to the HIS and RF periods. Annual and winter (DJF) coldest nights TNn over China and its four subregions were found to decrease moderately relative to the HIS and RF periods, whereas the number of frost days FD increased consistently. Precipitation extremes showed more temporal and spatial variability than temperature extremes. Trends of annual and JJA wet extremes during the hiatus were found to decrease relative to the HIS and RF periods, whereas the dry extreme index during the hiatus was found to increase generally over China and in most subregions. Lighter winds and lower relative humidity over most areas of China might have contributed to less pronounced trends of wet extremes during the hiatus period.

Role of the crown in tree resistance against high winds.

Rather than using wooden sticks to simulate the breakage of trees in high winds as in most research, we employ fresh samples from camphor and Formosa gum with branches and leaves to certify the crucial role of the tree crown. By using a blowdown wind tunnel with a maximum wind speed of 50 m/s, we purposely reduce the number of leaves and show that the drag force will drop by as much as two thirds when half pruned. Based on real observations, we model the leaf by an open and full cone in the presence of light and strong winds, and calculate how their corresponding cross-sectional area A and drag force F vary with wind speed v. Different slopes before and after the formation of a full cone are predicted and confirmed when these two quantities are plotted in full-log scale. Compared to the empirical value, our simple model gave α=2/5 and 2/3 for A∝v^{-α} and β=4/5 and 2/3 for F∝v^{β} at low and high winds. Discrepancies can be accounted for by including further details, such as the reorientation of open cones and the movement of branches.

Distribution and transport characteristics of fine particulate matter in beijing with mobile lidar measurements from 2015 to 2018

Accurately quantifying the concentration and transport flux of atmospheric fine particulate matter (PM2.5) is vital when attempting to thoroughly identify the pollution formation mechanism. In this study, the mobile lidar measurements in Beijing on heavily polluted days in December from 2015 to 2018 are presented. The lidar was mounted on a vehicle, which could perform measurements along designated routes. On the basis of mobile lidar measurements along closed circuits of the 6th Ring Road around Beijing, the spatial distribution and transport flux of PM2.5 in Beijing were determined with information of wind field. In the spatial distribution, both the concentration and transport of PM2.5 were revealed to be more significant in the southern section of Beijing. The regional transport layer at heights < 1.3 km plays an important role in pollution formation. The maximum transport flux reached 1600 μg/(m2*sec) on 11 December 2016. With the aerosol boundary layer height determined from the image edge detection (IED) method, the inter-annual variations of the aerosol boundary layer height (ABLH) were also analysed. The ABLH decreased from 0.73 to 0.46 km during the same heavy pollution period from 2015 to 2018. Increasingly adverse aerosol boundary layer (ABL) meteorological factors, including lower ABLH, light winds, temperature inversions, and accumulated moisture, have become necessary for pollution formation in Beijing.

MOSS AS BIOINDICATORS FOR POLLUTION AT FRASER HILL AND CAMERON HIGHLAND PAHANG MALAYSIA

Tropical Montane Cloud Forest (TMCF) is one of Earth’s most neglected ecosystems around the globe. More than half of these forests are situated within Southeast Asia. Malaysia is known for its numerous mountains that are exceptionally rich in biodiversity and locally endemic species, but they are also threatened by expanding human activity such as forestry, agriculture, infrastructure, and climate change. The study aims to critically assess the current state of moist TMCF, focusing on their physical and biological potentials as Bio indicators through Bio monitoring at Fraser Hill and Cameron Highland, Pahang, Malaysia. The mix-methods of observation surveys are to identify physical attributes such as light intensity, altitudes, temperature, wind velocity and air humidity. Secondly, laboratory tests are to identify heavy metal contamination absorbed by mosses. Based on the findings collected around the trails, a connection between altitude and microclimate could be found. The study finds that as the altitude increases and the temperature decreases, the vegetation becomes more dwarfed. Secondly, results from the analysis at Abu Suradi trail within Fraser Hill and Brinchang Trail within Cameron Highland have a higher average of aluminium and iron concentration. Mosses were manifested as good key indicators of air pollution with heavy metals to Malaysia highland forest ecosystems. It showed differential accumulation of heavy metals located near sources of pollution. Thus, the moss data confirms the persistence of risk of pollution of highland forest ecosystems in Malaysia, which demands environmental management. Furthermore, decision makers, planners and designers around the region can evaluate and improve their local strategies related to Tropical Montane Cloud Forest (TMCF) conservation and preservation, especially highlands such as Fraser Hill and Cameron Highland.

Fast Optical‐Thermal Responsive Intelligent Glass Realized by Hydrated Poly(N‐Isopropylacrylamide) Film

AbstractGlass is widely applied in fields of architecture, automobiles, optics and instruments due to its light transmission, wind resistance, sound and heat insulation. However, the light transmittance of traditional glass cannot change after the glass is formed, which limits the practicability of glass. In this study, an intelligent glass that can quickly and freely switch between transparency and opacity based on an optical‐thermal responsive hydrated poly(N‐isopropylacrylamide) film triggered by white light, infrared light, and direct thermal stimuli is developed. The fastest response time is ≈21 s under white light or 5 s by hand touch. A fatigue test of 250 cycles showed no obvious performance degradation. The transmittance of the intelligent glass changed reversibly between 88.5%–93.2% (transparent) and 25.5%–41.6% (opaque). The optical‐thermal response of the intelligent glass is attributed to the reversible phase transition of the hydrated poly(N‐isopropylacrylamide) film. This intelligent glass not only has obvious advantages in energy savings and emission reduction but also may be very useful for privacy protection, for example, in car windows, house windows, and office windows.

The looping pendulum: optimization with analytical and computational analysis

A looping pendulum is a setup that consists of two loads connected by a light string, which in turn is put over a fixed rod, with the lighter load being held by a person, and the heavier close to the rod. When the lighter load is released, experience shows there is an instant when the heavier load stops falling, and the lighter winds around the rod, bringing the system to rest. This setup is used in science demonstrations to prevent a fragile object, such as a ceramic mug, from falling to the ground, using washers as the lighter load. In this paper we propose a mathematical model for this demonstration, which we use to analyze the main parameters that influence the effectiveness of the setup. We find its equations of motion analytically, and use numerical methods to relate relevant parameters (such as falling distance and trajectory) to the initial configuration, determine the conditions that allow the phenomenon to happen, and display results as plots and parameter spaces. Lastly, through careful experimentation we found strong evidence for the validity of our theoretical predictions. We found the looping pendulum to be an extremely useful problem for introductory college physics courses interested in strengthening analytical and computational physics skills, as its construction is easy, inexpensive, and its analysis encompasses various mechanics concepts, solving differential equations numerically, and data collection through video software.

Experimental investigation of the stable water isotope distribution in an Alpine lake environment (L-WAIVE)

Abstract. In order to gain understanding on the vertical structure of atmospheric water vapour above mountain lakes and to assess its link with the isotopic composition of the lake water and with small-scale dynamics (i.e. valley winds, thermal convection above complex terrain), the L-WAIVE (Lacustrine-Water vApor Isotope inVentory Experiment) field campaign was conducted in the Annecy valley in the French Alps during 10 d in June 2019. This field campaign was based on an original experimental synergy between a suite of ground-based, boat-borne, and two ultra-light aircraft (ULA) measuring platforms implemented to characterize the thermodynamic and isotopic composition above and in the lake. A cavity ring-down spectrometer and an in-cloud liquid water collector were deployed aboard one of the ULA to characterize the vertical distribution of the main stable water isotopes (H216O, H218O and H2H16O) both in the air and in shallow cumulus clouds. The temporal evolution of the meteorological structures of the low troposphere was derived from an airborne Rayleigh–Mie lidar (embarked on a second ULA), a ground-based Raman lidar, and a wind lidar. ULA flight patterns were repeated several times per day to capture the diurnal evolution as well as the variability associated with the different weather events encountered during the field campaign, which influenced the humidity field, cloud conditions, and slope wind regimes in the valley. In parallel, throughout the campaign, liquid water samples of rain, at the air–lake water interface, and at 2 m depth in the lake were taken. A significant variability of the isotopic composition was observed along time, depending on weather conditions, linked to the transition from the valley boundary layer towards the free troposphere, the valley wind intensity, and the vertical thermal stability. Thus, significant gradients of isotopic content have been revealed at the transition to the free troposphere, at altitudes between 2.5 and 3.5 km. The influence of the lake on the atmosphere isotopic composition is difficult to isolate from other contributions, especially in the presence of thermal instabilities and valley winds. Nevertheless, such an effect appears to be detectable in a layer of about 300 m thickness above the lake in light wind conditions. We also noted similar isotopic compositions in cloud drops and rainwater.

A parametric study of the effect of leading edge spherical tubercle amplitudes on the aerodynamic performance of a 2D wind turbine airfoil at low Reynolds numbers using computational fluid dynamics

The majority of wind power is currently produced on high wind speed sites by large wind turbine, whereas small wind turbines often operate in light wind conditions. Small capacity wind turbines have not received the same engineering attention as their larger counterparts. This is partially due to a number of unique problems that small wind turbines experience. The most relevant are: low operating Reynolds number (Re<500,000), and poor performance at high angles of attack. Low and medium wind speed sites (Class II–IV) are more common than high wind speed sites, meaning there is a large source of energy not being taken advantage of. Several studies have suggested that flow control devices such as the spherical tubercle could be used to increase lift before stall and generate more power in such situations. The aim of this study is to determine the effect of tubercle amplitude on aerodynamic performance of an airfoil at low-Re numbers (Re=300,000&Re=400,000). Three amplitudes were considered in this study: A1=0.005c, A2=0.01c, and A3=0.03c. A detailed 2D simulation study is carried out, using FLUENT (a commercial CFD software) and the TransitionSSTk−ω turbulence model, to obtain aerodynamic coefficients and flow characteristics. Results indicate that small tubercles perform better overall than larger tubercles. The airfoil with the smallest tubercle outperforms the unmodified airfoil at both studied Reynolds numbers at angles of attack 0° – 4 °. Moreover, the airfoil with the largest tubercle outperformed all of the airfoils at an angle of attack of 0° and Re=300,000. The analysis of the aerodynamic coefficients indicates that the improvement of the aerodynamic performance of airfoils with tubercles is due to the reduction of the drag coefficient. Pressure, intermittency and wall shear stress contours suggest that the overall drag reduction is achieved through the decrease of friction drag. The decrease in friction drag is attributed to the thickening of the laminar boundary layer, caused by a more favorable pressure distribution around the airfoils with the aerodynamic improvements. Moreover, the drastic deterioration in aerodynamic performance at higher angles of attack is attributed to the turbulence generated by the tubercles. This study suggests that spherical tubercles could have a potential application in small wind turbines.

Problems of primary processing of cotton and biotechnological method of their solution

T he aim of the research i s to solve the problems of preserving the natural properties of cotton fiber and seeds. After analyzing the reasons that deteriorate the quality of cotton fiber and seeds, a new non-waste technology for cleaning cotton is proposed, as well asadditional resources for making a profit, which are biofertilizer, bio-solution and alkali. Methods and results. In laboratory conditions, biofertilizers and a solution were obtained with properties close to those of biofertilizers and solutions with the addition of dust extracted during cotton cleaning. To do this, in 30 kg of land collected from the fields, which could be moved by a light wind, were added5 kg of sheep manure, 5 kg of cattle manure, 3 kg of chicken manure, 0.5 kg of nitrate, 0.5 kg of urea, 0.5 kg of phosphate fertilizers as catalysts, they were placed in a 100 liter container, filled with water and following the procedure the desired product was obtained. The use of biological solution and biofertilizer contributes to the restoration of the fertile structure of the soil, an increase in cotton yield by 25–30%, improvement of the natural properties of cotton fiber and seeds, ecology.