scholarly journals Prediction on freezing fraction and collision coefficient in ice accretion model of transmission lines using icing mass growth rate

2021 ◽  
Author(s):  
Lin Yang ◽  
Zhihao Hu ◽  
Lupeng Nian ◽  
Yanpeng Hao ◽  
Licheng Li
Keyword(s):  
Growth Rate ◽  
Transmission Lines ◽  
Ice Accretion ◽  
Mass Growth ◽  
Accretion Model

Ice Accretion of Glaze Loads Model on Wires of Power Transmission Lines

2011 ◽  
Vol 189-193 ◽  
pp. 3225-3229
Author(s):  
Chun Cheng Liu ◽  
Jiao Liu
Keyword(s):  
Wind Speed ◽  
Transmission Lines ◽  
Prediction Models ◽  
Power Transmission ◽  
Time Dependent ◽  
Ice Accretion ◽  
Power Transmission Lines ◽  
Collision Efficiency ◽  
Accretion Model ◽  
Median Volume

In connection with the process of glaze ice, prediction models about height and thickness of ice coating under uniform and non-uniform ice accretion of wire are presented by taking into account local collision efficiency, freeze coefficient and collection coefficient based on the existing model at home and abroad. The time-dependent ice models on the conditions of different median volume diameter of super-cooled droplets, wind speed and wire diameter are analyzed. Compared with the existing model, the proposed ice accretion model performed well in predicting ice’s weight and thickness. At the same time, it can give some lights on ice disaster and anti-icing design for power transmission lines.

scholarly journals Icing Measurements on Fixed and Rotating Cylinders

1983 ◽  
Vol 4 ◽  
pp. 174-179
Author(s):  
P. McComber ◽  
J.-L. Laforte ◽  
D. Bouchard ◽  
D. D. Nguyen
Keyword(s):  
Transmission Lines ◽  
Liquid Water ◽  
Collection Efficiency ◽  
Droplet Diameter ◽  
Ice Accretion ◽  
Rotating Cylinders ◽  
Wind Velocities ◽  
Method Of Measurement ◽  
Temperature Constant ◽  
Water Contents

There is at present a need to develop a better technique for measuring the rate of icing on structures such as, for example, overhead transmission lines. For aircraft and helicopter icing, the most widely used method of measurement is the rotating cylinder. However, for measuring the icing of structures, this method is difficult to apply and also less accurate due to lower wind velocities. Different approaches are now being developed using fixed cylinders.Icing tests were conducted with fixed and rotating cylinders in a wind tunnel. The rate of icing was obtained through measurements of volume, accretion cross-section and time of deposition. Tests were made using five different liquid water contents and droplet diameter spectra, and four cylinder diameters, keeping the wind velocity and temperature constant. The rate of icing is presented as a function of the diameters of the fixed and rotating cylinders for each of the liquid water contents tested. Results indicate that at lower wind velocities the accretion rate is overestimated for the smaller rotating cylinders. This difference is probably due to the variation of the collection efficiency with diameter. From these results it is suggested that the rate of ice accretion on structures should be based on at least two fixed cylinders of different small sizes in order to take into account the effect of the collection efficiency.

scholarly journals Evaluation of Thymidylate Synthase Protein Expression by Western Blotting and Immunohistochemistry on Human Colon Carcinoma Xenografts in Nude Mice

2002 ◽  
Vol 50 (12) ◽  
pp. 1633-1640 ◽  
Author(s):  
Massimo Derenzini ◽  
Lorenzo Montanaro ◽  
Alessandra Chillà ◽  
Elena Tosti ◽  
Claudio Ceccarelli ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cell Growth ◽  
Protein Expression ◽  
Western Blotting ◽  
Thymidylate Synthase ◽  
Human Colon ◽  
Growth Fraction ◽  
Tumor Cell Growth ◽  
Mass Growth ◽  
Tumor Mass

In this study we investigated the relationship between thymidylate synthase (TS) protein expression, evaluated by Western blotting analysis and by immunohistochemistry (IHC), and growth rate in human colon xenograft tumors in nude mice. Human colon cancer cell lines were used to induce xenograft tumors and the tumor mass growth rate was calculated by measuring tumor size variations over time. TS 106 monoclonal antibody was used for both Western blotting and IHC TS detection. Tumor cell growth fraction was measured by Ki67/MIB1 immunolabeling and tumor cell growth rate by evaluating the mean nucleolar size in silver-stained sections. TS Western blotting values were related to tumor mass growth rate ( p<0.001) and cell growth rate ( p=0.002) but not to cell growth fraction ( p=0.676). The degree of the IHC staining showed only a trend to be associated with TS protein expression measured on Western blotting, and was not related either to tumor mass growth or cell proliferation rate. Tumor xenografts were also characterized for TS promoter tandem repeat and p53 status. No relationship was observed between these variables and TS expression evaluated by both Western blotting and IHC analysis. Our results demonstrate that TS expression evaluated by Western blotting analysis is directly related to the tumor mass growth rate and question the use of the IHC approach to obtain precise quantitative information on TS expression in tumor samples.

Experimental Researches on Micro-Droplet Freezing on a Solid Surface Under Atmospheric Conditions: Part I

2008 ◽  
Author(s):  
Heyun Liu ◽  
Xiaohui Ma
Keyword(s):  
Transmission Lines ◽  
Power Transmission ◽  
Electrostatic Force ◽  
Droplet Diameter ◽  
Ccd Camera ◽  
Freezing Process ◽  
Ice Accretion ◽  
Power Transmission Lines ◽  
Atmospheric Conditions ◽  
Air Stream

Atmospheric ice accretion on structures is a problem of fundamental importance to a number of industries. Examples of engineering problems caused by ice accretion involving aircraft, power transmission lines, telecommunication towers, electrical railway contact-wires, and other structures. Under atmospheric icing conditions two basic types of ice may form; rime or glaze. The supercooled micro-droplets in clouds are an important factor in icing. The objective of this study was to develop a new experimental method to investigate a single supercooled micro-droplet freezing process, in order to better understand the mechanism of rime or glaze ice accretion. The experimental device and principles are described in this paper. The experimental set has two small cold rooms, which is separated by a board with a central hole. A droplet with diameter of 15∼40 μm, temperature of 0∼−5°C was levitated in the cold air stream by electrostatic force. A CCD camera tracked its trace. The air temperature is from 0∼−10°C, the micro-droplet diameter is from 15∼40μm, and its temperature is from 0∼−5°C in the experimental study. This article focused on the experimental set and the experimental principles, and the next article will focus on the experimental data analysis.

A Study of Ice Accretion Shape on Cables Under Freezing Rain Conditions

2002 ◽  
Vol 124 (3) ◽  
pp. 162-168 ◽  
Author(s):  
Krzysztof Szilder ◽  
Edward P. Lozowski ◽  
Gerhard Reuter
Keyword(s):  
Heat Flux ◽  
Transmission Lines ◽  
Center Of Mass ◽  
Flux Ratio ◽  
Horizontal Cylinder ◽  
Ice Accretion ◽  
Atmospheric Conditions ◽  
Freezing Rain ◽  
Ice Load ◽  
Air Temperatures

The influence of atmospheric conditions (specifically precipitation rate and external heat flux) on the freezing rain ice accretion forming on a non-rotating, horizontal cylinder is studied, using an analytical model based on a simple form of the equations for conservation of mass and heat balance. In keeping with the freezing rain application, but in order to simplify this first step, we have assumed vertical incidence of precipitation (no wind) and no dripping from the accretion (hence light to moderate precipitation rates with relatively low air temperatures). The initial ice accretion shape and the location of its center of mass are examined as a function of the ratio of the precipitation mass flux to the total heat flux lost from the ice surface. An increase in the flux ratio leads to a quantifiable downward displacement of the accretion center of mass. We complement this analysis with numerical simulations, using an improved, two-dimensional version of the Szilder-Lozowski morphogenetic model that predicts the evolution of the accretion shape. For the first time, the freezing probability, which is the critical model parameter, is expressed as a function of location and atmospheric conditions for an accretion shape evolving with time. Using the morphogenetic model, we examine the influence of atmospheric conditions on the accretion shape and ice load. In particular, we address the question of what gives rise to extreme ice loads by identifying the range of atmospheric conditions that tends to maximize (or minimize) the ice load for a given amount of precipitation. The results of this research are applicable to predicting ice formation on overhead transmission lines.

Experimental Research on Conductor's Ice Accretion and Aerodynamic Characteristics

2014 ◽  
Vol 889-890 ◽  
pp. 497-500
Author(s):  
Han Jie Huang ◽  
Xin Min Li
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Wind Speed ◽  
Experimental Research ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Ice Thickness ◽  
Sudden Increase ◽  
Ice Accretion ◽  
Power Project

For conductor commonly used in power project, research was conducted on its ice accretion and aerodynamic characteristics. Ice mass and ice shape were examined under various icing condition: time, temperature and wind speed. Ice mass increases linearly with time, while the growth rate varies significantly with wind speed. Ice mass does not increase with the fall of temperature; it reaches the max value in a relatively high temperature range of-5°C~-10°C. Ice shape and ice thickness are both important factors that determine conductors aerodynamic characteristics. Sudden increase of lift coefficient may happen at low attack angle for conductor with thick crescent ice shape.

scholarly journals Indirect measurement of pasture mass and pasture growth rate on sheep and beef pastures

2008 ◽  
pp. 137-144 ◽  
Author(s):  
A.J. Litherland ◽  
R. Webby ◽  
T.J. Fraser ◽  
C. Matthew ◽  
K. Mccleod ◽  
...  
Keyword(s):  
Growth Rate ◽  
Dry Matter ◽  
Indirect Measurement ◽  
Mass Growth

This study aimed to develop calibrations for the measurement of pasture mass and pasture growth rate on sheep and beef pastures. Herbage within quadrats (0.12-0.2 m2) was measured with either an electronic rising plate meter (RPM) (n=2279), capacitance pasture meter (CPM) (n=693) or pasture ruler (n=2528) for the development of linear and curvilinear seasonal calibrations for pasture mass. Keywords: pasture mass, growth, rising plate meter, capacitance height, dead, dry matter, sheep, cattle

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