scholarly journals Experimental investigation of the stability of Bessel beams in the atmosphere

2019 ◽  
Vol 43 (3) ◽  
pp. 376-384 ◽  
Author(s):  
V.S. Vasilyev ◽  
A.I. Kapustin ◽  
R.V. Skidanov ◽  
V.V. Podlipnov ◽  
N.A. Ivliev ◽  
...  

We described an experiment on passing Bessel beams through the atmosphere with heat-trolled flows. We showed that at small distances, while passing through the region with a hot air flow, the Bessel beam can be distorted to a complete loss of the structure, but with further propagation over large distances it completely restores its structure. We also described an experiment with the passage of superpositions of vortex beams through the atmosphere with heat flows and aerosols.

2015 ◽  
Author(s):  
Nic van Vuuren ◽  
Gabriele Brizi ◽  
Giacomo Buitoni ◽  
Lucio Postrioti ◽  
Carmine Ungaro
Keyword(s):  
Air Flow ◽  

2014 ◽  
Vol 627 ◽  
pp. 153-157
Author(s):  
Nawadee Srisiriwat ◽  
Chananchai Wutthithanyawat

The temperature distribution of hot air flow in heating zone of a rectangular duct has been investigated for drying application. The experimental set-up consists of a heater and a fan to generate the hot air flow in the range of temperature from 40 to 100°C and the range of air velocity between 1.20 and 1.57 m/s. An increase of the heater power supply increases the hot air temperature in the heating zone while an increase of air velocity forced by fan decreases the initial temperature at the same power supply provided to generate the hot air flow. The temperature distribution shows that the hot air temperature after transferring through air duct decreases with an increase of the length of the rectangular duct. These results are very important for the air flow temperature and velocity control strategy to apply for heating zone design in the drying process.


2017 ◽  
Vol 890 ◽  
pp. 82-85 ◽  
Author(s):  
Reymark D. Maalihan ◽  
Bryan B. Pajarito

This work reports the effect of temperature on degradation of colored low-density polyethylene (PE) films during thermal aging. Film samples were formulated according to Taguchi design of experiments where colorant, thickness, and pro-oxidant concentration were varied accordingly. Tensile properties of films were monitored with time during heat aging in a hot air oven at 50, 70, and 90 °C. Likewise, surfaces of aged films were analyzed to evaluate the degree of oxidation of PE during thermal aging. The Arrhenius equation was then used to predict the lifetime of PE at an in-use temperature of 30 °C. Results indicate that increasing the temperature reduces the tensile strength and modulus of films. Formation of carbonyl groups as degradation products is also observed at higher temperatures. Consequently, thermal aging at 90 °C offers the highest extent of degradation of exposed films. Regression analysis reveals that white films degrade at a higher rate than yellow and non-colored films. The presence of TiO2 in white films shortens the lifetime of PE while amine stabilizer in yellow films enhances the stability of PE during thermal aging.


Author(s):  
H. R. Born

This paper presents an overview of the development of a reliable bearing system for a new line of small turbochargers where the bearing system has to be compatible with a new compressor and turbine design. The first part demonstrates how the increased weight of the turbine, due to a 40 % increase in flow capacity, influences the dynamic stability of the rotor-bearing system. The second part shows how stability can be improved by optimizing important floating ring parameters and by applying different bearing designs, such as profiled bore bearings supported on squeeze film dampers. Test results and stability analyses are included as well as the criteria which led to the decision to choose a squeeze film backed symmetrical 3-lobe bearing for this new turbocharger design.


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