Triggering Mechanism of Extreme Wind over the Complex Mountain Area in Dali Region on the Yunnan-Guizhou Plateau, China

Wind disasters are responsible for significant physical destruction, injury, loss of life, and economic damage. This study examined the extreme wind triggering mechanism over a typical mountain area with complex terrain, i.e., Dali city in Yunnan Province on the Yunnan-Guizhou Plateau in China. Using the observation data, we first optimized the Weather Research and Forecasting (WRF) model configuration and parametrization schemes for better simulating the wind in this area using a 1-month simulation. Then, the triggering mechanism of extreme wind was investigated by performing a series of sensitive experiments based on a typical extreme wind case. The results indicate that terrain uplift is critical for triggering the local 8–9-scale (the wind velocity between 17.2 and 24.4 m/s) extreme winds over high topography regions. When a large-scale atmospheric circulation is passing, accompanied with regional terrain lifting, the instantaneous wind velocity can reach 9- to 10-scale (the mean wind velocity between 20.8 and 28.4 m/s), causing broken power lines. These results suggest that it is essential to avoid sites where these factors can affect the operation of power transmission lines, or to establish warning systems in the existing systems.

A brief study on matrix converter for wind mill application

The wind energy is one of the low qualities because of change in direction and velocity of wind. So, the input power and the frequency will be varied which affects the operation of system. For a prescribed wind velocity, the mechanical power available from the wind turbine is function of shaft speed. The shaft speed is varying due to the change in the wind velocity; thereby change in frequency and voltage is developed at the output of the induction generator. Power electronics converters are used for stabilizing the varying parameters and to obtain a constant frequency of 50Hz. commonly used power electronic device is back-to-back converters or ACDC-AC converters which has many disadvantages like costly, bulky. Through matrix converter, the terminal voltage and frequency of the induction generator can be controlled in such a way that the wind turbine will be operating at a constant frequency of 50 Hertz.

Determining Firebrand Generation Rate Using Physics-Based Modelling from Experimental Studies through Inverse Analysis

Firebrand spotting is a potential threat to people and infrastructure, which is difficult to predict and becomes more significant when the size of a fire and intensity increases. To conduct realistic physics-based modeling with firebrand transport, the firebrand generation data such as numbers, size, and shape of the firebrands are needed. Broadly, the firebrand generation depends on atmospheric conditions, wind velocity and vegetation species. However, there is no experimental study that has considered all these factors although they are available separately in some experimental studies. Moreover, the experimental studies have firebrand collection data, not generation data. In this study, we have conducted a series of physics-based simulations on a trial-and-error basis to reproduce the experimental collection data, which is called an inverse analysis. Once the generation data was determined from the simulation, we applied the interpolation technique to calibrate the effects of wind velocity, relative humidity, and vegetation species. First, we simulated Douglas-fir (Pseudotsuga menziesii) tree-burning and quantified firebrand generation against the tree burning experiment conducted at the National Institute of Standards and Technology (NIST). Then, we applied the same technique to a prescribed forest fire experiment conducted in the Pinelands National Reserve (PNR) of New Jersey, the USA. The simulations were conducted with the experimental data of fuel load, humidity, temperature, and wind velocity to ensure that the field conditions are replicated in the experiments. The firebrand generation rate was found to be 3.22 pcs/MW/s (pcs-number of firebrands pieces) from the single tree burning and 4.18 pcs/MW/s in the forest fire model. This finding was complemented with the effects of wind, vegetation type, and fuel moisture content to quantify the firebrand generation rate.

CHEMICAL COMPOSITION OF RAIN WATER OVER BHUBANESWAR, ORISSA

Mon soon ram water over Bhubaneswar were collected and analysed during 198&. 1989 and 1991for CO}. HeO, . a . 50,.<NO}. Na. K Ca. Me. SiD: . EC and pH. The data shows that the chemical composition ofrain water is sready affected by meteorological cond itions. «r. intens ity, quantity and interva l between successiveshowers and al.so on wind velocity. II was round that with some exceprlon the ini tial showers are eenerally moresa lin e th an the subsequent o nes. the rati os between variou s co nstituents varyquite irregularly,Thesourcesofvariousconstituents have bee n discussed and th e amount of various ptant nutrients though sm all in relation 10 overallrequirem ent s of pla nu brought down by r-ain have been ca lcu lated in kg/hec.

Windtech – A Sensory Device for ‘Cold’ Sensation Measurements

Windtech device is a novel tool for measuring the sensation of the &lsquo;cold&rsquo;. Cold poses numerous challenges for industrial operations, human survival, and living convenience. The impact of the cold is not possible to be quantified just based on temperatures; however other factors such as wind speed, humidity, irradiance have to be taken into consideration. Efforts have been made to develop combined indices such as wind chill temperature (WCT), AccuWeather RealFeel&reg;, and others. The presented article discusses these along with the industrial standards that emphasize on the quantification of the &lsquo;cold&rsquo;. The following article introduces the Windtech device and its operating principle involving &lsquo;heated temperature&rsquo;, where the &lsquo;heated temperature&rsquo; is affected by environmental parameters including ambient temperature, humidity, wind velocity, and irradiance. The discussed Windtech device is calibrated for operation according to the ISO 11079:2007 standard.