Computational analysis of micro wind turbine with bamboo blades for domestic applications

A domestic purpose micro wind turbine realised using bamboo blade is tested for the power generation at an interval of two years and compared the performance. A CFD analysis of turbine with five blade system is carried out for an average wind velocity of 2.5m/s and structural integrity of the bamboo blade unit based on the pressure distribution is assessed. For the input wind velocity, a stream lined out flow of 5.9 m/s is found when wind turbine rotates at 300 rpm and corresponding pressure distribution is found to be maximum at the expected location of blade tip as129 Pa. The static analysis shows a good margin. For 2.5 m/s, a wind turbine generates an average value of 3.8V with 0.25A (based on 15 <span>Ω</span>/10W load). The wind turbine has produced nearly the same power even after a period of two years.

Computational analysis of micro wind turbine with bamboo blades for domestic applications

A domestic purpose micro wind turbine realised using bamboo blade is tested for the power generation at an interval of two years and compared the performance. A CFD analysis of turbine with five blade system is carried out for an average wind velocity of 2.5m/s and structural integrity of the bamboo blade unit based on the pressure distribution is assessed. For the input wind velocity, a stream lined out flow of 5.9 m/s is found when wind turbine rotates at 300 rpm and corresponding pressure distribution is found to be maximum at the expected location of blade tip as 129 Pa. The static analysis shows a good margin. For 2.5 m/s, the wind turbine generates an average value of 3.8V with 0.25A (based on 15/10W load). The wind turbine has produced nearly the same power even after a period of two years.

Impact of Enclosure Boundary Patterns and Lift-Up Design on Optimization of Summer Pedestrian Wind Environment in High-Density Residential Districts

A comfortable wind environment favors the sustainable development of urban residential districts and public health. However, the rapid growth of high-rise urban residential districts leads to low wind velocity environments in summer. This study examines the influence of enclosure boundary patterns and lift-up design on the wind environment and proposes an optimization strategy to improve the low wind velocity environment in residential districts in summer. A typical residential district in Hangzhou was selected; the average wind velocity, calm wind zone ratio and comfortable wind zone ratio were selected as the evaluation indexes. The wind environment for different enclosure boundary patterns and lift-up designs were obtained via computational fluid dynamics (CFD) simulations. The results indicate that the pedestrian wind environment is greatly improved in residential districts by reducing the height/width of the enclosure boundary, increasing the permeability rate and adopting a lift-up design in all buildings within residential districts. A combination of permeable railings and lift-up design is recommended; this can increase the average wind velocity and the ratio of comfortable wind zones by 70% and 200%, respectively. This study provides practical guidelines for the optimization of a low wind velocity environment in Chinese high-density residential districts in summer.

Meteorological Factors and the Transmissibility of Hand, Foot, and Mouth Disease in Xiamen City, China

Background: As an emerging infectious disease, the prevention and control of hand, foot, and mouth disease (HFMD) poses a significant challenge to the development of public health in China. In this study, we aimed to explore the mechanism of the seasonal transmission characteristics of HFMD and to reveal the correlation and potential path between key meteorological factors and the transmissibility of HFMD.Methods: Combined with daily meteorological data such as average temperature, average relative humidity, average wind velocity, amount of precipitation, average air pressure, evaporation capacity, and sunshine duration, a database of HFMD incidence and meteorological factors was established. Spearman rank correlation was used to calculate the correlation between the various meteorological factors and the incidence of HFMD. The effective reproduction number (Reff) of HFMD was used as an intermediate variable to further quantify the dynamic relationship between the average temperature and Reff.Results: A total of 43,659 cases of HFMD were reported in Xiamen from 2014 to 2018. There was a significantly positive correlation between the average temperature and the incidence of HFMD (r = 0.596, p &lt; 0.001), and a significantly negative correlation between the average air pressure and the incidence of HFMD (r = −0.511, p &lt; 0.001). There was no correlation between the average wind velocity (r = 0.045, p &gt; 0.05) or amount of precipitation (r = 0.043, p &gt; 0.05) and incidence. There was a temperature threshold for HFMD's transmissibility. Owing to the seasonal transmission characteristics of HFMD in Xiamen, the temperature threshold of HFMD's transmissibility was 13.4–18.4°C and 14.5–29.3°C in spring and summer and in autumn and winter, respectively.Conclusions: HFMD's transmissibility may be affected by the average temperature; the temperature threshold range of transmissibility in autumn and winter is slightly wider than that in spring and summer. Based on our findings, we suggest that the relevant epidemic prevention departments should pay close attention to temperature changes in Xiamen to formulate timely prevention strategies before the arrival of the high-risk period.

Hazard forecasting techniques implementation in crane safety instruments using a crane anemometer

Introduction. This article describes an algorithm developed by the authors for the operation of a crane anemometer that measures the gust rate and average wind speed and determines the predicted wind speed on the basis of it. The main part. The main influencing parameters and their measurement intervals are defined for the construction of the anemometer algorithm. The method of calculation of gust velocity and average wind velocity from the data of the pulse sensor of the helicopter anemometer is presented. The method of wind speed forecasting based on the construction of an extrapolation function is given.Results. An anemometer program algorithm with extended capabilities relative to existing analogues has been developed. The instrument not only captures the hazard at the moment, but also predicts its future development. On the basis of the analysis of wind dynamics studies, a table has been compiled of the levels of the determined parameters (gust rate, average speed and projected average wind speed) and the signals given to the operator of the crane. For each type of signal, the value of the removal delay is defined.Conclusions. ZAO KROS Engineering and Technical Centre has made a prototype anemometer using the principles described in this article. The device meets all requirements of the regulatory and technical documentation. Further work on the improvement of the algorithm of its work will make it possible to increase the safety of technological processes carried out with the use of elevated structures.

Effects of Low Temperature and Wind Treatment on Physiological Indexes, Rumen Microbiota, Immune Responses and Hormones in Sheep

Background: Low-temperature environments can strongly affect the normal growth and health of livestock. Previous studies have shown that cold exposure can alter the intestinal microbiota and thereby affect other traits. In winter, cold weather can be accompanied by strong winds that aggravate the effects of cold on livestock. In this study, an experiment was conducted to investigate the effect of low temperature and wind speed on physiological indexes, rumen microbiota, and immune responses in sheep.Methods: The sheep were divided into control group and test group according to their ambient temperature.Sheep in the test group were divided into four groups according to wind-speed treatment: no wind (average wind velocity less than 0.5 m/s), low wind velocity (average wind velocity of 3 m/s), medium wind velocity (average wind velocity of 4 m/s) and high wind velocity (average wind velocity of 5 m/s).Results: Average daily gain and the utilization of forage, especially soluble fiber, decreased with increasing wind velocity in cold temperature (P<0.05). In rumen, the enzyme activity of cellulose degradation was also lowerwith increasing wind velocity (P<0.05). The abundance of potentially beneficial bacteria showed differedamong the wind treatments (P<0.05).The large fluctuations in the amount of bacteria provided a breeding opportunity forpotentially harmful bacteria (P<0.05). In addition, there were significant decreases in the serum levels of IL-2 and IFN-γ (P<0.05) and a large increase in IL-4 level (P<0.05), which indicated that the sheep underwent immune suppressionduring the trial. The significant increase in the activities of the antioxidant enzymes SOD, GSH-PX, and CAT (P<0.05) indicated that the production of oxygen free radicals was increased.Conclusions: The cold environment significantly reduced the growth of sheep and altered the composition of rumen microbiota, reducing the utilization of soluble fiber by the rumen flora. Furthermore, the sheep produced large amounts of enzymes to resist tissue damage and experienced immune suppression in the cold environment.

Numerical simulation of a wire–plate solid-state fan for ultra-quiet museum display cases

Conventional microenvironment control systems of a museum display case generally use mechanical fans which produce great noise and vibration for heat dissipation of semiconductor air-conditioning units. Solid-state fans (ionic wind) operate with no moving parts and can overcome noise and vibration issues of a microenvironment control system. In this study, a multi-electrode mathematical and physical model of wire–plate solid-state fans was developed, and its performance has been analysed in depth. Simulation results indicate that there is an optimal distance between discharge electrodes ( d), which corresponds to the largest average wind velocity at the exit of the simulation area ( ua). Under the same power consumption, ua and the vertical height from a discharge electrode to a collecting electrode ( H) exhibit a monotonically increasing relationship. Similarly, ua and the radius of a discharge electrode ( r) show a monotonically decreasing relationship. In addition, a manufactured solid-state fan with an average wind velocity of 1.48 m·s−1 shows a noise intensity of 4.3 dB(A), which is considerably lower than that of a mechanical fan, with the same power consumption. These positive results suggest that ultra-quiet microenvironment control technologies of a museum display case can be potentially developed in the near future.

Pengaruh Desain Interior Diffuser Terhadap Peningkatan Performa Diffuser Augmented Wind Turbine (DAWT)

The main objective of numerical simulation in thisstudies is to determine the effect of diffuser’s interior design onincreasing the diffuser augmented wind turbine (DAWT)performance by observing wind velocity increment. Numericalstudies were carried out using the computational Fluid Dynamics(CFD) method through a two-dimensional steady approach withAnsys Fluent 18.2 and Ansys Workbench 18.2 software. Thepresent studies spesifically investigate the shapes of diffuser,namely flat diffuser and curved diffuser. The studies demonstratethat the curved diffuser generates stronger increment of the windvelocity than flat diffuser (at centreline), which 1.842 times thefreestream velocity, while the flat diffuser is only able to increseup to 1.742 times the freestream velocity. The curved diffusershows the highest increment of the average wind velocity alongdiffuser with the greatest increment of 78.66 % and the flatdiffuser is only able to provide average wind velocity incrementup to 44.81%. The curved interor of diffuser is able to enlarge thewake area, so the effect of the suction flow entering the diffuserbecomes stronger. Therefore, curved diffuser is better to provideDAWT performance improvements.

Experimental Study on the Escape Velocity of Miners during Mine Fire Periods

The purpose of this study is to accurately calculate the escape velocity of miners under different roadway conditions during mine fire periods. The experiment to examine escape velocity was carried out in the roadway of the Mu Chengjian Coal Mine. In the experiment, the relationships between the miner escape velocity and the inclination of the roadway, the area of the accessible section of the roadway, and the average wind velocity of the roadway were obtained through single factor analysis, and two multiple regression equations of the escape velocity were developed through multivariable linear regression analysis. The escape velocities of the miners were then predicted, and the error was analyzed with multiple regression equations. The experimental results show that the miner escape velocity decreases with an increase in the absolute value of the inclination of the roadway and increases with an increase of the accessible section area of the roadway and the average wind velocity of the roadway. In addition, the multiple regression equations have the strongest significance if the independent variables are the inclination of the roadway, the accessible section area of the roadway, and the type of roadway, and the contribution rate of the inclination of the roadway to the escape velocity is the highest. The predicted results calculated by the multiple regression equations are close to the experimental data, and the prediction errors are less than 10%. Consequently, we conclude that the multiple regression equations can be used to predict the miner escape velocity during periods of mine fires.