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The understanding of the flow characteristics and effect of gas-solid interactions in pneumatic risers is fundamental to investigate to ensure effective design cost-effective operation. Thus, to understand the effect of gas-solid interactions on the hydrodynamics of newly proposed conversing risers, this study mainly focused on predicting pressure drop in the dilute phase pneumatic conveying system. The experiments were conducted in a converging riser having a convergence angle of 0.2693°. Various solid particles such as sago, black mustard, and alumina have been considered to study the effect of particle sizes and density on the pressure drop. The experimental outcomes indicate that the total pressure drop increases with an increase in the solid density and gas mass flow rate. Moreover, smaller particle sizes are also increased the pressure drop. An empirical correlation is developed for the prediction of total pressure drop ΔPT in converging pneumatic riser via dimensional analysis. All dependent variables such as particle and air density, drag force, acceleration due to gravity, the mass flow rate of air and particle, the diameter of particle and converging riser, the height of converging riser were considered to develop the empirical correlation. The established relationship is tested, and experimental data have been fitted for its validation. The estimated relative error of less than 0.05 proved the significance of the developed correlation. Hence, it can be stated that the established relationship is useful in studying the effects of various parameters on the pressure drop across the length of the conversing riser.

Synthetic aperture radar (SAR) is a valuable tool for lake ice monitoring. The recently proposed SAR configuration for Earth observation called compact polarimetric (CP) SAR could be a good compromised choice between conventional (single or dual) and fully polarimetric (FP) SAR for operational ice applications, including lake ice. Given its enhanced radar target information compared with conventional SAR systems over wider swath coverage compared with FP SAR, CP systems could play important role in the new generation of Earth observation systems. Herein, we study the evolution of CP SAR parameters from simulated CP SAR data in relation to early ice growth. Focus of the study is on four lakes located in Cornwallis Island, Canadian Central Arctic. We adopt parameters extracted from dual circular polarimetric and right circular transmit, linear (horizontal and vertical) receive configurations. In this study, we consider the ice thickness calculated from an established empirical model. Meteorological and ice climatological data were used to support the analysis. Results demonstrated a potential connection between a number of CP parameters and lake ice growth. Furthermore, we were able to highlight the relationship between the density of air bubbles in ice layer and the intensity of volume scattering mechanism, leading to the identification of lakes with increased gas production activities. Thus, differences between lakes in terms of density of air bubbles were detected and statistically evaluated.

In this paper, we use the correlation between the average wind speed and the elevation above sea level to present a regression model for calculating the average wind speed and evaluating the wind potential in the southern region of Ecuador. After obtaining the regression model, an adjustment factor based on the topographic slope has been included, mainly since the wind speed could vary largely as it blows across the lower slope regions or intermediate hills of mountains. Once the wind speed was obtained, both at 10 m and 100 m, the wind power density was calculated, which includes the impact of wind speed and air density. Finally, the model accuracy was obtained by comparing other free access data sources including actual data from meteorological stations, using statistical parameters to quantify the error. According to the results obtained, we find that wind speed has a good correlation with the terrain elevation of the southern region of Ecuador. The simulated wind speed compared to the actual data has errors between 7.75% and 16.89%, which indicates that the model can predict with > 83% accuracy. In addition, both the root means square error and the standard deviations have around 1 m/s of error.

The question from the title is raised because in almost all introductory physics courses/textbooks the atmospheric pressure has been attributed to the weight of the column of air from a given level in the atmosphere up to its top. “Air is pressing on air.” However the same textbooks, in the chapter on the kinetic theory of gases, tell students that a pressure in a gas enclosed in a container is due to variation of momentum suffered by the molecules, as a consequence of their impacts against the walls or against the surface of a test object placed inside the gas. The higher the number and average energy of molecules, the higher the pressure. Despite the fact that the atmosphere consists of matter that is mostly in the gas state, introductory physics textbooks do not justify why the concept of pressure from the kinetic theory of gases would not explain the physical nature of pressure in the atmosphere. Ricci-Torricelli’s experiments realized by scientists from the Academia del Cimento suggest to abandon the “weight based” explanation in favor of a density-based explanation of atmospheric pressure. The dependence on altitude of air density, as well as of air pressure, is caused by Earth’s gravitational force acting on all chaotically moving molecules in the atmosphere.

The article discusses the calibration results of reference standards-copies according to the State Primary Standard of the Mass Unit using the new CCL 1007 vacuum comparator and buoyancy artifacts. The authors provided historical data on the calibrations of copies of the International Prototype of the Kilogram (IPK) starting from 1892, including the Russian prototype № 12. The instability of the prototype of the kilogram No. 12 corresponds to international values and is assessed at 5 · 10–11 kg per year. Changes in the mass of copies are assessed in relation to the mass of the IPK, but it is impossible to determine to what extent it has changed. This was the reason for the adoption of a new value of the kilogram. Following the adoption at the 26th meeting of the General Conference on Weights and Measures (CGPM) held in Paris in November 2018, Planck constant was numerically established with absolute accuracy, and total uncer tainty of 1 · 10–8 kg was assigned to the mass of the IPK. Thus, the authors set the aim to preserve the numerical value of the total uncertainty of the reference standards-copies by reducing the transfer error of the State Primary Standard by 10 times. The article presents the calibration results of six reference standards-copies in relation to prototype No. 12 with the primary data processing using the method of least squares, and the uncertainty budget is provided. The calibration results of the reference standards-copies confirmed the accuracy increase of the transfer unit by 10 times in the range from 6 · 10–9 kg to 6 · 10–10 kg by the use of a vacuum comparator graduated 0.1 μg and buoyancy and sorption artifacts in direct measurements of air density. This has made it possible to compensate for the additional uncertainty attributed to the IPK based on the determination of the Planck constant value and to ensure the mass calibration of all accuracy grades preserving the entire hierarchical system of transferring the mass unit in the country.

Theoretically, the output power of a wind farm is mainly under influence of wind speed as an atmospheric parameter. However, there are other factors that impact wind power generation. Atmospheric s...

Air temperature forecasting has been a vital climatic factor required for different applications in many areas such as energy, industry, agriculture, health, environment, and meteorology. This study compares the performances of two static neural networks (NNs) used for the prediction of hourly ambient air temperatures in a coastal area of Turkey. Thirteen parameters from Land Surface Diagnostics and Surface Flux Diagnostics Collections from the MERRA-2 reanalysis dataset including pressure, surface specific humidity, wind speed, wind direction, air density at surface, evaporation, planetary boundary layer height, total precipitable water vapor, total precipitation, total cloud area fraction, total column ozone, greenness fraction, and leaf area index were used as input parameters for the models. Feed-Forward Neural Network (FFNN) and Cascade Forward Neural Network (CFNN) models were applied to forecast hourly ambient air temperatures at 2 m height from the surface. The results indicated that the most accurate and reliable predictions were obtained by the CFNN model with 30 neurons, while the lowest prediction performance was obtained by the FFNN model with 5 neurons. The root mean squares error (RMSE), mean absolute error (MAE) and coefficient of determination (R-2) values for training (and testing) of the CFNN model with 30 neurons were 0.358 (0.376), 0.273 (0.283), and 0.997 (0.992), respectively, whereas the same parameters were 0.430 (0.447), 0.334 (0.343), and 0.996 (0.989) for the FFNN model with 5 neurons. The CFNN model had a lower RMSE and MAE, and a higher R-2 than the FFNN model. These results showed that increasing the number of neurons of hidden layers from 5 to 30 provided better model performance.

The thermal buoyancy generated by the difference in air density in a building can drive hot-pressed natural ventilation, which is an energy-efficient means of ventilation used to obtain higher air quality. Therefore, the effect of a single-point heat source with limited sides at different heights on stratified flow was studied in a naturally ventilated room in this paper. Based on the classical plume diffusion law of an independent point heat source and the mirroring principle, a calculation model of the thermal stratification height with a restricted source elevated to different levels was derived and validated. The quantitative effects of the heat source height from the floor, the effective opening area and other factors on the natural ventilation of hot pressure were analyzed. A threshold xT for the separation between a point source and a sidewall was defined to estimate whether the thermal plume was independent or restricted by a sidewall. And a method for calculating the threshold xT was obtained. This research can provide a reference basis for designing natural ventilation for buildings with a restricted heat source at different levels to achieve a desired indoor environment.

The deployment of the use of inshore wind farms is an important for the preservation of the environmental aspects of the Mediterranean Sea zone, and seeks to achieve this goal all major industrialized countries bordering it. To assess the wind profile and its economic feasibility for the coastal area in Sidi Barrani province, a meteorological station with mast of 10 m was constructed near the Mediterranean Sea shore in Egypt. The density of wind power was assessed at the level of 100 m monthly and seasonally after taking into account the correction of air density. On the annual basis, the station is rated with high potential 441 kW/m2. This is an ideal location for large-scale wind turbine to generate sustainable electricity. A performance assessment was executed using three commercialized wind generators having capacity of 2000 kW from different manufacturers and were also equal in height and rotor diameter, for choosing the best unit suitable for the target area. The economic analysis of a 200 MW coastal wind farm in the studied area was done using the advanced method of present value costs. The findings prove that the proposed project could produce approximately 988 GWh per year of electrical energy with an economic price of 1.7 US cents per kWh.

We demonstrate that ultralight carbon aerogels with skeletal densities lesser than the air density can levitate in air, based on Archimedes' principle, when heated with light. Porous materials, such as aerogels, facilitate the fabrication of materials with density less than that of air. However, their apparent density increases because of the air inside the materials, and therefore, they cannot levitate in air under normal conditions. Ultralight carbon aerogels, fabricated using carbon nanotubes, have excellent light absorption properties and can be quickly heated by a lamp owing to their small heat capacity. In this study, an ultralight carbon aerogel was heated with a halogen lamp and levitated in air by expanding the air inside as well as selectively reducing its density. We also show that the levitation of the ultralight carbon aerogel can be easily controlled by turning the lamp on and off. These findings are expected to be useful for various applications of aerogels, such as in communication and transportation through the sky.

The present study introduces a Binary Integer Programming (BIP) method to minimize the number of wind turbines needed to be installed in a wind farm. The locations of wind turbines are selected in a virtual grid which is constructed considering a minimum distance between the wind turbines to avoid the wake effect. Additional equality constraints are also included to the proposed formulation to prohibit or enforce the installation of wind turbines placement at specific locations of the wind farmland. Moreover, a microscopic wind turbine placement considering the local air density is studied. To verify the efficiency of this proposal, a square site was subdivided into 25 square cells providing a virtual grid with 36 candidate placement locations. Moreover, a virtual grid with 121 vertices related with a Greek island is also tested. All simulations conducted considering the area of geographical territory, the length of wind turbine blades, as well as the capacity of each turbine.

The possibility of reconstructing the spatial distribution of average air density in a supersonic jet from results of laser transillumination is considered. It is shown that the reconstruction procedure for axisymmetric flows can be performed based on Abel transforms by results of measurements of local wavefront tilts. An algorithm for reconstructing the average density of air in a medium from the deviations of the front of the transillumination wave relative to the jet axis is developed. The algorithm is tested in experiments on the vertical jet facility of the Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences. The results agree well both with contact measurement data known from the literature and with the numerical solution of the hydrodynamic problem.

The relationship between ambient conditions and light-duty vehicle energy consumption has been widely researched. Relatively little effort, however, has been dedicated to understanding representati...

Single-cylinder SI engine normally supply air to operate above ambient pressure. Pressurized air is necessary to scavenge the exhaust gas cylinder and the load of air was delivered to the next power stroke by mechanical air compressors or by reciprocating compressors using the space beneath the piston. The engine provided the air-pressure capacity, which reduces the useful work obtained by the engine by the same quantity. In order to operate efficiently, the turbo charge uses between 7 and 8% of total power, i.e. 20 to 25%. A spinning compressor is powered by the rotor shaft. Owing to compression, the intake temperature changes. If the compressed air is chilled in a refrigerator, it would be cheaper to maximise the air density. The engine's output is increasing with the turbocharger being implemented.

This letter presents a systematic approach to estimate the annual energy production (AEP) of variable-speed wind turbines erected at high-altitude sites. Compared with the existing empirical-model based approaches, the proposed approach models the influence of the air density on the power production while employing the theoretical power curve. Consequently, the proposed approach provides a precise estimation of AEP, which can serve as a foundation of the optimum turbine-site matching design at different-altitude sites.

We develop a new method for characterizing the lift force on a baseball. The methodology addresses this task from the novel perspective of considering a large set of radar measurements acquired outside of a laboratory setting. The reduced degree of standardization in the measurements is countered by several elements of the approach. A new optimization method is developed that incorporates domain knowledge and constraints derived from optical measurements. The optimization accounts for the uncertainty in the different data sources while exploiting the size and diversity of the radar measurements to mitigate the effects of systematic biases, outliers, and the lack of geometric information that is typically available in laboratory experiments. Fine-grained weather data is associated with each radar measurement to enable compensation for the local air density. By applying this methodology to a set of over two million trajectory measurements, we achieve unprecedented accuracy in the characterization of the lift force. We show that the lift coefficient is more than six percent greater than measured by previous laboratory experiments. We also demonstrate the ability to predict increases in the lift coefficient in response to changes in seam height on the order of a thousandth of an inch. Previous methods based on smaller sets of laboratory measurements have been unable to discern changes in the lift coefficient in response to changes in seam height of 0.02 inches. We demonstrate the statistical significance of the results. This work benefits several important application areas including the monitoring of sensor calibration systems and the definition of ball specifications that constrain trajectories to acceptable ranges.

A quantitative technique was conducted at Rosh Pinah Zinc mine, Namibia with its main purpose to determine airways resistance which is a function of the parameters; roughness of the airways and the friction factor. The 32 branch points (i.e. a-ag) that stand for ventilation circuit have been selected. Data collected includes, length and width of airways, air velocity; air density, and roughness of the airways which were used to determine coefficient of frictions, friction factors and airway resistances. A ventilation model was developed. In order to improve the current ventilation model, airways resistance of the mine was determined and simulated in a modified model using VentSimTM software. An average total airways resistance of 0.32027 Ns2/m8 has been achieved for Rosh Pinah mine. It should be pointed out that, as the mine advances its production faces deeper, this value would increases suddenly. Simulation revealed that as much as 34.4 m3/s of air can be received at the production faces, compared to the measured received amount of 19.3 m3/s. Therefore, volumetric efficiency of the mine was improved from 29.3% to 68.3%. It was also noticed that after importing the resistance values into the model together with other parameters, the model was greatly improved and no cause for concern.

The growth in sustainable generation technology such as fuel cell, wind energy conversion system, photovoltaic system, increase in fuel cost, energy necessity and the reduction in the fossil fuel reserve, for better power quality and reliability, is obliging the power sector to use the renewable based energy sources. In India, wind energy is gradually becoming an important and significant energy resource. Keeping in opinion the aforementioned wind energy prediction is becoming an essential study for harnessing the wind energy prospective. This paper proposes an effective technique based on intelligent approach for predicting wind power in different areas. This technique is based on using an intelligent model concerning the predicted gap to its similar one and two year old data. There are many intelligent and conventional models existed in literature for the wind power prediction like support vector machines (SVM), back propagation (BP) prediction etc. In this paper an effective fuzzy logic and model predictive control based models have been developed and offered for the wind power prediction for microgrid application by using air density and wind speed as the input parameters for fuzzy system. The outcomes are compared with the computed data and existing models and it can be observed that the different errors are found within the permissible limits. The outcomes obtained from fuzzy based technique are very close to calculated values if compared with model predictive based technique. Hence, the proposed models can be employed for the prediction of wind speed and wind power generation in the selected stations. The existing models results are compared with Kolkata city outcomes. The Error RMSE with Support vector machine, Back propagation, Model of forecast error correction +SVM and Model of forecast errors correction +BP, Neural Network method, model predictive based system, and proposed fuzzy logic based system are 30.48%, 32.83%, 26.81%, 28.58%, 1.1431%, 1.38% and 1.12% respectively. Therefore, the proposed techniques provide the best results and even these are observed within the suitable limits. Additionally, the achieved outcomes can be used for Microgrid/SmartGrid applications.

As intriguing optical phenomena that occur in nature, mirages are widely known and often mentioned in physics classes when introducing the basics of optics. In the atmosphere, a mirage occurs under the condition of vertical variations in air density, which are usually caused by a temperature gradient. The light rays are continuously refracted and follow a curved path when passing through the air, because the refractive index of air changes with its density. Hence, the image observed in an optical manner is displaced from the location of the object. An upward-shifted image is known as a superior mirage, whereas a downward-shifted one is known as an inferior mirage. There are several simple experiments that can create both superior and inferior mirages, using a non-uniform liquid solution to simulate the refractive index gradient in the air. These experiments not only demonstrate the curved paths of light rays, but also produce artificial multiple-image mirages. This paper introduces a simplified method of creating inferior mirages in a liquid solution. Using this method, we further demonstrate several different facets of mirages and explain their origins through computer simulations.

Air density is a parameter used in numerous applications. Its correct determination can have a key impact on the outcome of an experiment. In calculation of the drag coefficient or pneumatic piping energy loss air density value is crucial for obtaining accurate results. In order to precisely measure this parameter, the electronic air density measuring device was designed and built. The following article presents design, construction, calibration and tests of the mentioned device. The device was designed with a target of reaching set assumptions. It was constructed with open-source programming environment and easily accessible components. Calibration of the device’s sensors was performed in order to ensure high accuracy of results. Calibration of the humidity sensor was performed with use of saturated salt solutions. Exemplary measurement was made to ensure device performance. Created tool provides excellent and cheap fulfillment of the assumptions set in the article.

Motor transport is the main consumer of energy resources in most countries. Atmospheric conditions, along with the vehicle design, its technical condition, driver's skill, road, and transport conditions significantly affect fuel consumption. However, in mathematical modeling, they are often taken into account by average values which can affect the accuracy of the results. The nature of the relationship between ambient temperature and fuel consumption by city diesel buses was established on the basis of experimental and analytical studies. According to the results of the analysis of experimental data, it was found that this relationship is described by polynomial regressions of the second order. The accuracy of the regression model was confirmed by Fisher's test for two city routes. Analytical studies of the effect of air density, rolling resistance, transmission efficiency, and all three factors together on fuel consumption were performed using mathematical modeling using the Physical Emission Rate Estimator methodology. It was found that rolling resistance and transmission efficiency have the greatest impact on fuel consumption. In both cases, the difference between the highest and lowest estimated value was 2.5%. However, in absolute units, the difference is greater by 0.2l/100km for rolling resistance. The obtained results can be used in mathematical models of vehicle movement, in particular city buses, to take into account the dynamics of changes in fuel consumption depending on the ambient temperature. They will also be useful in mathematical models for determining harmful emissions to calculate fuel consumption at various ambient temperatures

A model of a single reed instrument is studied in which the reed is described as an Euler-Bernoulli beam, and the air flow through the instrument is calculated using the Navier-Stokes equations. The hypothetical instrument resembles a clarinet, but is smaller than a real clarinet to keep the numerical modeling feasible on available supercomputers. This article explores the conditions under which the frequency of the reed oscillations and the emitted sound are determined by the resonant frequency of the bore of the instrument. The effect of the contact between the reed and the player's lips is also studied, and quantitative results for the air density and pressure in the mouthpiece and throughout the instrument bore are also presented.

The potential of low-calorie gases, in particular, biogas, which Ukrainian agriculture and industry produce in significant quantities, is almost never used here. The number of available domestic facilities for recycling such gases is scanty, although, in most developed countries, the significant number of such factories is operating. Landfill biogas is one of the promising energy sources, still, today, it is either emitted into the atmosphere, polluting it, or burned in flares. The use of biogas as fuel in automotive internal combustion engines is not sufficiently studied. However, the substitution of gasoline for biogas reduces engine power and increases fuel consumption. Especially this should be taken into account when operating vehicles in mountainous terrain under the conditions of reduced atmospheric pressure and temperature. Nevertheless, researching how mountain conditions can influence the performance of biogas-powered automobile engines is not given enough attention yet in Ukraine and in the world. Operation of cars on the mountain roads of the Carpathian region at the altitudes of 1000 ÷ 2000 m above sea level with rises and descents up to 12% and the section length up to 10 ÷ 15 km is difficult. The higher is the level of the terrain above the sea, the lower become the atmospheric pressure, air density and temperature, which deteriorates the filling of the car engine cylinders. The engine cooling rate decreases because of the air dilution and small speeds on steep slopes. Simultaneously, running engines on an excessively enriched fuel-air mixture and moving mainly in lower gears lead to engine overheating. Under the mountainous terrain conditions, Air to Boil temperature decreases. As we know the blend composition of biogas, it is possible to calculate its combustion value as well as the combustion value of the gas-air mixtures. Based on analytical research, we have plotted some graphs that reflect the dependence of the changes in the effective power and effective specific biogas consumption on the changes in ambient temperature and atmospheric pressure.

The aerothermodynamic parameters of air are studied in shafts of mines of NorNickel’s Polar Division. The total pressure and temperature measurements, as well as the air density calculations in KS-2, GS and VC-4 shafts in Oktyabrsky Mine show the linear total pressure dependence on the shaft depth and the essentially nonlinear dependence of air temperature and density on the depth of shafts at intersections with ventilation channels and horizons. The lengths of sections of leveling of air parameters behind the intersections are estimated. The authors propose a new method to determine aerodynamic drag coefficients in mine shafts and calculate ADC for 28 mine shafts in the Norilsk Region. The calculation results are used in mathematical modeling of mine ventilation networks and in ventilation designs for new mine sites.

This paper analyses the influence of the variation of meteorological and operational parameters on estimation of the power output of a dispatchable wind farm (WF). The active power set-points (APSPs), established to regulate the wind farm power output (WFPO), are one of the analysed parameters. The WF considered as case study is integrated in the Gorona del Viento wind-hydro power plant (El Hierro-Canary Islands-Spain), which supplies the primary energy demand of the island. Statistical inference between the errors generated by different WFPO estimation models, each fed with different input features, is performed. These models are based on supervised machine learning (ML) regression algorithms, namely support vector regression, random forest, and a combination of the strengths of these two base learning algorithms constructed using stacked regression ensemble techniques. From the results obtained, the following conclusions are drawn: a) There is a marked difference between the errors obtained with the model that only considers wind speed and direction and that which additionally incorporates the APSP parameter, showing the importance of considering this particular parameter; b) the model which incorporates air density and turbulence intensity in addition to the APSP improves the values of all the metrics, independently of the ML technique employed.

Aim: To evaluate the effect of lockdown amid COVID 19 pandemic on water vapors in atmosphere under subtemperate and subtropical zones of Jammu region. Methodology: To study the variation in atmospheric chemistry, the data was analyzed on fortnightly basis in order to assess the water vapor presence in the atmosphere during complete lockdown, i.e. from 24th March to 17th May 2020. The data of Temperature and Relative Humidity were recorded from Agrometeorological Observatory situated at respective locations under study. The water vapor attributing parameters were calculated by adopting different formulae. Results: The analysis of weather data was done by adopting different statistical techniques and it was found that ambient temperature was below normal with a deviation of -5.99% and -3.69% under subtropical and subtemperate zone. With the downshifting pattern observed in temperature, the density of air also decreased with deviation of -0.29% in subtropical zone and -0.46 % in subtemperate zone. The relative humidity, mixing ratio and dew point temperature under subtropical conditions were increased by 8.19, 1.03 and 1.61% respectively, while under subtemperate zone the parameters increased by 3.98, 4.51 and 10.3% respectively. The saturated mixing ratio, enthalpy and absolute humidity were deviated by -4.53%, -5.45 and -1.50% in subtropical zone and 5.94, 6.62 and 8.28 % in subtemperate zone. Conclusion: Variable significant patterns were observed for each parameter and thus it can be concluded that lockdown had a plausible impact on all humidity or water vapor attributes.

Wind power generation is considerably dependent on the weather condition and it is correlated closely with the air density, wind speed, and its direction through considering the transformer tap change cost. Therefore, an accurate prediction model is required to forecast and adopt with the complicated signals. In this article, an accurate prediction method trained with improved wavelet transform (IWT) to decompose the original signal to subsignals, new feature selection based on the maximum dependence, maximum relevancy, and minimum redundancy to filter the signal and select the best candidate inputs and a synthetic forecasting engine with minimum forecasting error is proposed. The proposed method of forecasting engine composed two-dimensional convolution neural network (TDCNN) and trained by improved optimization algorithm based on particle swarm optimization. The proposed improved optimization algorithm will fine-tune the weights of TDCNN to increase the prediction accuracy of the forecast engine. The training optimization processes and effectual fast classification are the main duty of the proposed intelligent algorithm. The efficiency of the suggested prediction approach is widely evaluated and compared to other prediction approaches using the practical power market data. A simulation study is conducted over the trained model and the results are discussed in detail. Obtained numerical results and also analysis in short-term and long-term forecasting horizons validate the high performance and advantages of the introduced approach.

DG technology has always been an interface for improving power efficiency and power quality in distribution system. The objective of the work is to minimize the distribution system line losses with wind energy as DG. A wind farm is formed with irregularly placed wind turbines to generate maximum energy with minimum wake loss caused by single wake as well as multi wake effect. The wake losses are analyzed with varying inter turbine horizontal distance for the same wind farm. A new reconfigured wind farm is designed which minimizes the wake loss due to wake effect on downstream turbines and enhances the power generation from the wind farm. This paper presents the complete analysis of wake losses caused to each individual turbine. The hourly wind speed data is generated from previously available thousands of wind speed data using Kernel Density Estimation (KDE). Load Impedance Matrix (LIM) based Distribution System Load Flow (DSLF) method is implemented to find the power losses and bus voltages in the system. For the study, effect of air density on wind, wake effect on wind and hourly load variation are considered. Two standard test cases, IEEE-28 and IEEE-69 bus Radial Distribution System (RDS) are considered for the optimal DG placement. The optimal location of DG is found out using Grey Wolf Optimization (GWO) Technique.

In solar chimney the flow of air in the system plays a dominant role. Solar chimney systems are usually large and have a low efficiency. In this research a redesigned experimental solar chimney power plant with a modified collector layout was evaluated. A tracking mirror reflector was used to enhance the thermal concentration effect underneath the chimney. The emphasis was on increasing the temperature at the transition zone between the collector and the chimney base and creating an improved overall temperature difference. Mathematical analysis of the thermal and flow behavior of the currents, under the influence of the concentration effect from the reflector, led to the development of a simulation algorithm to assist in the evaluation process. A comparative analysis was applied to investigate the effect of thermal concentration on the air flow velocity under the chimney. The indicators were the variation of the overall thermal radiation in the transition zone and the instigated temperature rise with hourly ambient temperature change. The obtained results suggested up to 10.25% increase in the maximum temperature obtained at the chimney base. This induced a maximum air flow velocity improvement of 22.22%. The impeding effect of density reduction at the considered temperature range was checked against the total theoretical output power. At peak output when the power scored 56.867% rise from the average for the day, air flow velocity showed 25.316% increase while the air density was reduced by only 2.069% from the mean values for the day.

Метою даного дослідження є попередній розрахунок і моделювання технологічних параметрів процесу висікання картонних розгорток у пневматичній системі засобами автоматизованого проектування SolidWorks. У даний час проектування, модернізація і удосконалення ротаційного обладнання вимагає оригінальних технічних рішень, особливо для виробництва різнопрофільних картонних паковань. Йдеться про якісний технологічний процес висікання в зоні «ніж—контрніж» і взагалі про виконання завершальних робіт. Проблема дослідження стосується ріжучих і обробних виконавчих механізмів. Відповідно використання пневматичних систем може істотно спростити процес висікання. Розроблений на кафедрі модуль для висікання може бути вбудованим у транспортувальну систему. Наприклад, у стрічковий конвеєр. Таке комбінування транспортера і ротаційного модуля для висікання картонних заготовок вимагає додаткових теоретичних і експериментальних досліджень. Equipment for the manufacture of cardboard products is constantly being improved. New sections for die cutting are being designed. As well as devices for carrying out technological processes of die-cutting and cutting down of cardboard products. The tendency to improve the rotational method of trimming and die cutting of sheet materials is increasing. The main problem in the design of die cutting equipment is the quality of the processes performed. The advantages of the rotary die cutting sections include high productivity. Therefore, improving this process is very important. This article deals with the technological process of cutting in the knife-counter—knife zone. The problem of the interaction of cutting actuators is considered. The use of pneumatic systems greatly simplifies the die cutting process. An advantage of the pneumatic die cutting module is that it can be integrated into the transport system. This combination of conveyor and rotary module allows for curved separation of cardboard sweep. The aim of this study is to simulate the technological parameters of the process of cutting cardboard reamers in a pneumatic system. The calculation was carried out by computer aided design. Accordingly, in the working area of die cutting of the pneumatic system, the air pressure changes. Therefore, temperature parameters of air are important parameters. As previous studies have shown, air temperature can affect the performance of the rotary die cutting module. With increasing temperature, the required air flow rate increases to maintain the required working pressure. This is directly related to a decrease in air density with increasing temperature. Improving the geometry of the nozzle of a pneumatic system is an important study. A partial drop in pressure in the working areas of the die cutting can lead to a decrease in the quality of material processing. The basis of the work is research on the influence of air flow and its temperature variables as a characteristic working fluid. Additional studies carried out using the SolidWorks computer-aided design system show the dependence of the air volumetric flow rate on its variable temperature in the working area of the pneumatic rotary die cutting section.

Amethod of calculating pressure losses during pneumatic transport with the objective of choosing the most efficient operating mode, which allows reducing the consumption of compressed air, is observed. It has been found that the generally used formulas for calculating pressure losses along the path, determined as the sum of the pressure losses for pure gas and material, do not explain why the initial pressure losses decrease with increasing air flow rate, and their further growth. The importance of considering changes of air density and air flow velocity along the length of the pipe, as well as the necessity of considering the blockage of part of the pipeline cross section with material in case of high concentrations, is shown. It is proposed to determine the pressure losses using the Bernoulli equation in integral form, for example, using the eight nodes Gauss method. The applicability of the method of calculating both straight and inclined sections of pipelines is established. The experimental results of researching and analyzing the proposed isothermal model in a vacuum pneumatic transport laboratory facility are given. An example of calculating the pressure losses for an industrial pneumatic transport system with a pipe length of 450 m and an inner diameter of 147 mm at various expendable concentrations of material is shown.

Air density strongly constrains the characteristics of an airflow and the resulting flow of sand and therefore, it should not be neglected in sand transport models. Although the potential importance of air density is well known, most studies on threshold velocity, saltation trajectory, and dust emission have been conducted near sea level, at a “normal” atmospheric density. In this study, utilizing the observational data from 12 meteorological stations in the Tarim Basin (TB) from 2009 to 2018, we used air density as the basis to discuss the necessity of model parameter localization. It was found that there was a significant difference in the horizontal dust flux estimated using the normal and local air densities. Using the localized air density, we re-evaluated the temporal and spatial distribution characteristics of the threshold velocity, horizontal dust flux, and wind erosion events in the TB and further quantified their distributions in all directions. The results demonstrated that the threshold velocity gradually increased from east to west and from north to south, with the maximum value occurring in the southwestern TB. The horizontal dust fluxes and wind erosion events could be classified into three types according to the seasonal variation characteristics; however, one of the main distribution characteristics was spring > summer > autumn > winter. Tazhong, Qiemo, and Ruoqiang are sand- and dust-incident frequent zones. Taking Minfeng when passing from Tazhong to Shaya as the line of demarcation, it was found that the horizontal dust fluxes and wind erosion events in the eastern region mostly occurred in the eastern direction, whereas those in the western region primarily occurred in the western direction. The results suggested that it was extremely important and necessary to localize the parameters in sand–dust models, which would also provide a more accurate climate background for the study of sand and dust in the TB.

Measurement, monitoring and recording of the environmental condition is the essential and sometimes statutory requirements, to observe the small change or deviation in the results of measurements in calibration and testing laboratories as well as other scientific applications. This motivated the authors to develop a precision wireless environment conditions, measurement, monitoring and recording (WEMMR) device. The present paper describes the design and development of an indigenous precision WEMMR device. The WEMMR is comprised of a micro-electromechanical sensor (MEMS; BME-280) capable to measure, monitor and record three parameters related to prevailing environmental conditions in the room, i.e., ambient temperature (T) in the range (0–100) °C, ambient pressure (P) in the range (300–1100) mbar and relative humidity (H) from (0–100)%. The system was developed using microcontroller (ATmega328) and Wi-Fi module (ESP8266) for wireless operation. These environmental conditions were also used to determine the prevailing air density (ρair) in the room and display the same on the monitoring panel. The monitoring and recording of ρair are extremely important parameters in measurement and realization of mass and mass-related quantities, i.e., force, pressure, flow and ultrasonic power. Apart from monitoring, recording of the data device is also capable to transmit the data to remotely located computer through internet connectivity. The developed WEMMR device had been calibrated against national standards available at the National Physical Laboratory, India, for ambient temperature, ambient pressure and humidity ranged for (10–50) °C, (300–1100) mbar and (30–80)%, respectively. The uncertainty in the ambient temperature, ambient pressure and relative humidity has been evaluated as ± 0.37 °C, ± 0.31 mbar and ± 0.71%, respectively.

The magnitudes of the kinematic parameters of projectiles motion in the air depends on deterministic (form of projectile, its mass, temperature of air and charge, atmospheric pressure, derivation) and nondeterministic (muzzle velocity, magnitude and direction of wind velocity) values. During the projectile movement, its weight and frontal air resistance force have a determining influence on its dynamics. In the article it is investigated proposed by authors the mathematical model of determination of the functional dependence of the magnitude of the frontal air resistance force of the projectile’s motion on its velocity, mass and caliber, geometric characteristics, temperature and density of air, atmospheric pressure, sound speed in air. Since the trajectory of movement of the BM1 projectile released from the T-12 (MT-12) is canopy, it is assumed that during the projectile’s flight the air temperature and atmospheric pressure are unchanged and equal to their value at the point of the gun.

A method for calculating pressure losses during pneumatic transport is considered with the aim of choosing the most favorable operating mode, which allows to reduce the consumption of compressed air. It has been established that the generally accepted formulas for calculating pressure losses along the path, calculated as the sum of the pressure losses for pure gas and material, do not explain the fact of the initial decrease in pressure losses with increasing air flow rate, and then their growth. The importance of accounting for changes in air density and air flow velocity along the length of the pipe, as well as the need to take into account the overlap of part of the pipeline section with material in the case of high concentrations, is shown. It is proposed to determine the pressure loss using the Bernoulli equation in integral form, for example, the Gauss method using eight nodes. The applicability of the method for calculating both straight and inclined sections of pipelines is established. The experimental results of studying and analyzing the proposed isothermal model in a vacuum pneumatic transport laboratory installation are presented. An example of calculating the pressure loss for an industrial pneumatic conveying system with a pipe length of 450 m and an inner diameter of 147 mm at various flow rates of the material is shown. Ill. 4. Ref. 21. Tab. 1.

Despite many commercial applications make extensive use of Unmanned Aircraft Systems (UAS), there is still lack of published data about their performance under unconventional weather conditions. In the last years, multirotors and fixed wing vehicles, commonly referred to as drones, have been studied in wind environments so that stability and controllability have been improved. However, other important weather variables have impact on UAS performance and they should be properly investigated for a deeper understanding of such vehicles. The primary objective of our study is the preliminary characterization of a propeller in a climate-controlled chamber. Mechanical and electrical data have been measured while testing the propeller at low pressure and cold temperatures. Test results point out that thrust and electric power are strongly affected by air density. A comparison between the experimental data and the results of the Blade Element Theory is carried out to assess the theory capability to estimate thrust in unconventional environments. The overlap between experimental data and theory computation is appropriate despite geometrical uncertainties and corroborate the need of a reliable aerodynamic database. Propeller performance data under unconventional atmospheres will be leveraged to improve UAS design, propulsion system modelling as well as provide guidelines to certify operations in extreme environments.

Purpose The purpose of this paper is to investigate wind power potential of site using wind speed, wind direction and other meteorological data including temperature and air density collected over a period of one year. Design/methodology/approach The site-specific air density, wind shear, wind power density, annual energy yield and capacity factors have been calculated at 30 and 10 m above the ground level (AGL). The Weibull parameters have been calculated using empirical, maximum likelihood, modified maximum likelihood, energy pattern and graphical methods to determine the other dependent parameters. The accuracies of these methods are determined using correlation coefficient (R²) and root mean square error (RMSE) values. Findings The site-specific wind shear coefficient was found to be 0.18. The annual mean wind speeds were found to be 5.174 and 4.670 m/s at 30 and 10 m heights, respectively, with corresponding standard deviations of 2.085 and 2.059. The mean wind power densities were found to be 59.50 and 46.75 W/m² at 30 and 10 m heights, respectively. According to the economic assessment, the wind turbine A is capable of producing wind energy at the lowest value of US$ 0.034/kWh. Practical implications This assessment provides the sustainable solution of energy which minimizes the dependence on continuous supply of oil and gas to run the conventional power plants that is a major cause of increasing load shedding in the significant industrial and thickly populated city of Pakistan. Also, this will minimize the quarrel between the local power producer and oil and gas supplier during the peak season. Social implications This wind resource assessment has some important social implications including decreasing the environmental issues, enhancing the uninterrupted supply of electricity and decreasing cost of energy per kWh for the masses of Karachi. Originality/value The results are showing that the location can be used for installing the wind energy power plant at the lower cost per kWh compared to other energy sources. The wind energy is termed as sustainable solution at the lowest cost.

A spatial distribution model for air density perturbations during the propagation of internal gravity waves (IGWs) is used to derive estimates for gravity perturbations generated by these waves. The estimates show that superconducting gravimeters are capable of detecting IGWs generated by any wave source in the lower atmosphere. Series of barometric and gravimetric measurements at Moxa, Germany (50.6° N, 11.6° E), for 2000–2018 are processed using digital filtering to search for pressure and gravity perturbations with time scales of ~10 min to ~10 h. The annual change in the atmospheric pressure variation with variation scales on the order of and less than 1 h shows a summer maximum, which disappears at higher scales. The summer maximum can be attributed to the effect of IGWs with periods on the order of and less than 1 h from convective clouds that occur in the summer half of the year. The annual change in the gravity variation shows maximums in winter and summer for all the variation scales under consideration. They can be explained by modulating the solar semidiurnal gravitational tide by a semiannual change in the perturbation of the Earth’s gravitational potential.

After the revision of the International System of Units (SI) in May 2019, the Planck constant h became the top of the dissemination system for the kilogram. However, the Planck constant is difficult or impractical to use in daily calibrations. Thus, in many applications, alternative physical artefacts are used as mass standards for dissemination. Mass measurements of silicon spheres for the determination of Avogadro and Planck constants have shown that silicon spheres possess stability with high accuracy, thus can be utilized as mass standards. However, the material and the geometry properties of silicon spheres are different from classic mass standards commonly used for the dissemination of the kilogram. It is therefore necessary to determine mass corrections of silicon spheres to improve mass measurements. The effect of air density fluctuations in air buoyancy correction of silicon spheres mass measurements is investigated in this article. Six types of air density fluctuations for three different weighing processes are summarized. In addition, a method to minimize the impact of air density fluctuation by applying real-time air density data to estimate the air buoyancy correction is proposed. Mass comparisons using a 1 kg silicon sphere and classic mass standards in various materials were conducted for method verification. Results show that the improved method using the real-time air density of each alternative weighing process can reduce the measurement errors by 8.7 μg to 39.0 μg in the air buoyancy correction, which is not negligible when performing high accuracy mass measurements for the dissemination of the redefined SI mass unit using silicon spheres.

Assuming thermal convection takes place continuously inside the North Pacific High, an application of physics to the rising sea-warmed air plumes increases understanding of the relatively high air pressure at the sea surface and at the bases of the plumes. Since the ocean is warmer than the air under the NPH, heat is transferred upward decreasing the air density, which should then accelerate upward when no other forces are around to stop it. By Newton’s 3rd law the upward accelerating air will cause an equal but opposite (downward) reaction resulting in high pressure in the air under the rising column. That is the central proposal offered, which is consistent with available observations. New data that confirm the upward acceleration of the heated air are especially needed. Perhaps dye or neutrally buoyant particles could be released from a ship or buoy to make the upward air motion visible.

The paper discusses the issues of ventilating in deep quarries caused by the intensification of blasting operations at great depths, the increased distance of ore truck transportation to the daylight area, constant change in the geometrical parameters of the quarry, its microrelief and direction of mining, and increased isolation of the mined space from the environment. We provide a brief analysis of the current tools for forced airflow in deep quarries, which showed that the use of forced ventilation is often challenging since it leads to high energy consumption, high level of noise exceeding the permissible parameters, and high speeds of forced air flows may blow the dust off the quarry surfaces. The article presents methods and tools developed at the Siberian Federal University for intensifying the natural airflow in deep quarries by changing the air density at the entrance and exit points of the pit, as well as heating the shady areas using mirrors and solar energy, which do not interfere with mining and blasting operations.

The unfavorable effects of non-uniform temperature inlet flow on gas turbine engine operations have always been a hindrance on the performance of turbo-fan engines. The propulsive efficiency is a function of the overall efficiency of turbofan engine which itself is dependent on other ambient parameters. Variation of inlet compressor temperature due to increase or decrease of aircraft altitude, air density, relative humidity, and geographical climate conditions affects the compressor performance. This research focuses on the turbofan transonic compressor performance due to ambient temperature distortion. A novel predictive approach based on neural network model has been implemented to predict the compressor performance and behavior at different ambient temperature conditions. The model produces substantially accurate results when compared to the results of CFD analysis. Computational results from CFD analysis show that engine thrust decreases at higher altitude, lower density and lower pressure regions.

The aim of this work is to investigate the effect of extreme high ambient air temperature on the performance of a wind farm operating in Algeria Saharan area. The analysis is carried out using in-s...

The binary mixture of magnetite powder and fine coal was used to investigate the adjustment of bed density and fluidization stability of air dense medium gas-solid fluidized bed (ADMGFB) through theoretical and experimental approaches. An optimum calculated model was selected to predict incipient fluidization velocities with different weight proportions of fine coal (xc). A modified model of the bed density of ADMGFB using binary dense media was derived based on the two-phase fluidization theory with experimental verification. Bed density stability and fluidization uniformity were achieved based on the investigation distribution of bed density and fine coal of each bed layer. The separation experiments of raw coal using ADMGFB were carried out with N of 1.3. When xc was less than 16%, the probable errors were no more than 0.07 g/cm3. Results indicated that the satisfactory separation performance of raw coal was achieved using ADMGFB based on the binary dense media.

In recent works, we developed a model of balanced gas flow, where the momentum equation possesses an additional mean field forcing term, which originates from the hard sphere interaction potential between the gas particles. We demonstrated that, in our model, a turbulent gas flow with a Kolmogorov kinetic energy spectrum develops from an otherwise laminar initial jet. In the current work, we investigate the possibility of a similar turbulent flow developing in a large-scale two-dimensional setting, where a strong external acceleration compresses the gas into a relatively thin slab along the third dimension. The main motivation behind the current work is the following. According to observations, horizontal turbulent motions in the Earth atmosphere manifest in a wide range of spatial scales, from hundreds of meters to thousands of kilometers. However, the air density rapidly decays with altitude, roughly by an order of magnitude each 15–20 km. This naturally raises the question as to whether or not there exists a dynamical mechanism which can produce large-scale turbulence within a purely two-dimensional gas flow. To our surprise, we discover that our model indeed produces turbulent flows and the corresponding Kolmogorov energy spectra in such a two-dimensional setting.

Aviation operations are significantly affected by weather conditions, such as high-temperature days. Under global warming, rising temperatures decrease the air density and thus, reduce the maximum takeoff weight of an aircraft. In this study, we investigate the impact of global warming on the aircraft takeoff performance in 53 airports in China by combining observational data and CMIP6 climate projections. There is a distinct geographic inhomogeneity of critical temperature, above which the takeoff weight decreases significantly with the increasing air temperature, mostly due to differences in airport elevations. By the end of the century, under the SSP5-8.5 scenario (with average warming of 5.2 °C in China), the daily maximum temperature for nearly all summer days in West China and for about half of the summer days in East China exceeds critical temperature, indicating that frequent weight restriction will be necessary. We further examine the reduction in carrying capacity due to climate change. By the end of the century, under the SSP5-8.5 scenario, the summer total carrying capacity will be reduced by about 2.8% averaged over all 53 airports. The impacts on airports in West China are nearly four times greater than those in East China, due to the higher vulnerability and stronger warming in West China.

Background: Mountaineers must control and regulate their thermal comfort and heat balance to survive the rigors of high altitude environment. High altitudes feature low air pressure and temperatures, strong winds and intense solar radiation, key factors affecting an expedition’s success. All these climatic elements stress human heat balance and survival. We assess components of human heat balance while climbing Mt. Everest.Materials and Methods: We calculated climbers’ heat balance using the Man-ENvironment heat EXchange model (MENEX-2005) and derived meteorological data from the National Geographic Expedition’s in situ dataset. Three weather stations sited between 3810 and 7945 m a.s.l. provided data with hourly resolution. We used data for summer (1 May–15 August 2019) and winter (16 October 2019–6 January 2020) seasons to analyze heat balance elements of convection, evaporation, respiration and radiation (solar and thermal).Results: Meteorological and other factors affecting physiology—such as clothing insulation of 3.5–5.5 clo and activity levels of 3–5 MET—regulate human heat balance. Elevation above sea level is the main element affecting heat balance. In summer two to three times more solar radiation can be absorbed at the summit of the mountain than at the foot. Low air pressure reduces air density, which reduces convective heat loss at high altitude by up to half of the loss at lower locations with the same wind speed and air temperature.Conclusion: 1. Alpinists face little risk of overheating or overcooling while actively climbing Mt. Everest, despite the potential risk of overcooling at extreme altitudes on Mt. Everest in winter. 2. Convection and evaporation are responsible for most of the heat lost at altitude. 3. Levels of physical activity and clothing insulation play the greatest role in counteracting heat loss at high altitude.

A recent formula for the lift force on a low speed wing of circular arc cross-section [1] is adapted to the upward pressure force on the crests of a surface gravity wave propagating in the wind. In both cases, the main feature is the utilization of the air’s compressibility. At and near a wave crest, it is predicted that the air density is increased over the ambient value and that the air density decreases inversely as the square of the upward distance from the radius of curvature of the crest. As a consequence, the air pressure also decreases upward inversely as the square of the same distance. Therefore, an upward pressure force on each crest occurs which presumably will make the crests grow. Growth rates are largest for small wavelengths and large mean slopes of the wave surface. Contrary winds should produce wave growth (not damping) as well as no wind at all.