Method of ice distribution and data processing for ship ice resistance experiment in broken ice field

Patent metadata

Field	Value
Publication number	US-11397127-B2
Application number	US-201916957804-A
Country	US
Kind code	B2
Filing date	Aug 9, 2019
Priority date	Jan 5, 2019
Publication date	Jul 26, 2022
Grant date	Jul 26, 2022

Abstract

In a method of ice distribution and data processing for ship ice resistance experiment in broken ice field, the ice floe is uniformly distributed in the broken ice field before each ship ice resistance experiment with eliminating the mutually overlapped broken ice to make it close to the experimental design working condition, and independent repeated experiments are carried out on each ship ice resistance experiment to reduce the influence of accidental factors; after finishing the experiment, the experimental data are divided into intervals and the experimental data corresponding to unreasonable subdomains are eliminated by mathematical statistics, and the uncertainty analysis is carried out; image correction is carried out for pictures of in broken ice field in the pre-experimental data, and the pictures are divided to obtain subdomain pictures to calculate the actual coverage rate of each subdomain; the ice resistance in the experimental data corresponding to each remaining subdomain is modified.

First claim

The invention claimed is:

1. A method of ice distribution and data processing for ship ice resistance experiment in broken ice field, comprising the following steps:
S1. uniformly distributing ice floes in a broken ice field, eliminating overlapped ice floes, and recording pre-experiment data;
carrying out a ship ice resistance experiment by passing a ship through the broken ice field, and recording experimental data;
S2. repeating step S1 at least three times;
S3. dividing the broken ice field into a plurality of subdomains;
S4. conducting an outlier data point judgment for the experimental data corresponding to each subdomain, discarding experimental data corresponding to abnormal subdomains among the plurality of subdomains, and conducting uncertainty analysis for the experimental data corresponding to remaining subdomains among the plurality of subdomains;
S5. performing a geometric correction on pictures of the broken ice field in the pre-experimental data to eliminate perspective deformation;
assigning at least one subdomain picture to each of the plurality of subdomains;
performing image binarization processing to the at least one subdomain picture for each subdomain;
calculating an actual coverage rate for each subdomain picture after binarization processing, wherein the actual coverage rate equals a number of white pixels in the picture after binarization processing divided by a total number of pixels in the picture after binarization processing;
and
S6. according to the actual coverage rate and a design coverage rate of each subdomain, modifying ice resistance in the experimental data corresponding to each remaining subdomain to obtain a final ice resistance corresponding to each remaining subdomain.

2. The method according to claim 1 , wherein the ship passes through the broken ice field at a constant speed during the ship ice resistance experiment in the broken ice field, and the ice floes are polyethylene plates with a uniform thickness.

3. The method according to claim 1 , wherein, in step S3:
a length of each subdomain is 1.5-2.5 times a length of the ship; and
the ship has at least 10 collisions with the ice floes in each subdomain.

4. The method according to claim 3 , wherein a number of the plurality of subdomains in step S3 is 10-15.

5. The method according to claim 4 , wherein step S4 comprises:
selecting one kind of data from the experimental data corresponding to each subdomain, and judging the data according to equation (1),

(

Chauv
⁢
#

)

Mean

=



F

T
⁢

⁢
_
⁢

⁢
mean

-

(

Mean_
⁢

⁢

F

T
⁢

⁢
_
⁢

⁢
mean

)

(

STD
⁢

⁢
_
⁢

⁢

F

T
⁢

⁢
_
⁢

⁢
mean

)



,

(
1
)

wherein, (Chauv #) Mean represents a Chauvenet value of the kind of data, F T_mean represents a mean value of the selected data of each subdomain, Mean_F T_mean represents a mean value of the mean values of the selected data of all subdomains, STD_F T_mean represents a variance of the mean values of the selected data of all subdomains;
when the value of (Chauv #) Mean of the subdomain is not within the range of 1.96-2.13, determining the subdomain as abnormal and discarding the corresponding experimental data, and
conducting uncertainty analysis of the experimental data corresponding to the remaining subdomains according to equation (2):

U
⁡

(

F

T
⁢

⁢
_
⁢

Assignees

• Univ Dalian Tech

Inventors

• Zong Zhi
• Yin Zhihong
• Zhang Guiyong
• Sun Zhe
• Wang Hao
• Yang Biye
• Jiang Yuyan
• Chen Zhaoyang
• Yang Tao

Classifications

• G06V10/28

  Quantising the image, e.g. histogram thresholding for discrimination between background and foreground patterns · CPC title

• Y02T70/10

  Measures concerning design or construction of watercraft hulls · CPC title

• G01M10/00 Primary

  Hydrodynamic testing; Arrangements in or on ship-testing tanks or water tunnels · CPC title