Method and system for monitoring icicles based on adhesive optical fibers

A system for monitoring icicles based on adhesive optical fibers, comprising:

• a data acquisition module, configured to acquire a temperature signal, a strain signal and a vibration signal of an eaves surface to be monitored by using adhesive optical fibers, and preprocess the acquired signals;
• wherein, the adhesive optical fibers are adhered to the eaves surface in an array form;
• a growth condition monitoring module, configured to construct an icicle growth model (IGM) based on the acquired signals, and monitor a growth status of the icicles based on the IGM;
• wherein, constructing the IGM according to the acquired signals comprises:
• using an icing rate of icicle to reflect an ice layer expansion rate;
• using a strain abrupt change to reflect a severe degree of a local deformation of an optical fiber;
• and
• quantifying a vibration energy to describe cracks inside the icicles;
• wherein, using the icing rate of icicle to reflect the ice layer expansion rate, comprises:
• G
• =
• ∂
• T
• ·
• k
• ice
• ·
• A
• contact
• ∂
• t
• ·
• Q
• latent
• ,
• A
• contact
• =
• N
• fiber
• ·
• ω
• fiber
• ·
• d
• ;
• wherein, Acontact represents the icing rate of icicle,
• ∂
• T
• ∂
• t
• represents temperature change rate with time;
• kice is ice thermal conductivity;
• Qlatent is ice latent heat;
• d is a node spacing of FBG;
• Nfiber is a deployment density of the optical fiber;
• G is ice spreading speed, one of the criteria for measuring the risk rating of icicle falling;
• using the strain abrupt change to reflect the severe degree of the local deformation of the optical fiber comprises:
• S
• =
• max
• ⁡
• (
• ❘
• "\[LeftBracketingBar]"
• ε
• t
• +
• 1
• -
• 2
• ⁢
• ε
• t
• +
• ε
• t
• -
• 1
• ❘
• "\[RightBracketingBar]"
• )
• ;
• wherein, εt is a corrected strain at time t;
• εt+1 and εt−1 are strain values at adjacent times;
• S is a mutation coefficient, one of the criteria for measuring the risk rating of icicle falling;
• quantifying the vibration energy to describe the cracks inside the icicles comprises:
• V
• =
• ∫
• 1
• ⁢
• Hz
• 100
• ⁢
• Hz
• ❘
• "\[LeftBracketingBar]"
• F
• ⁡
• (
• ω
• )
• ❘
• "\[RightBracketingBar]"
• 2
• ⁢
• d
• ⁢
• ω
• ;
• wherein, F(ω) is the Fourier transform of a moving signal, and represents energy distribution of the signal in a frequency domain;
• V represents an accumulated vibration energy, one of the criteria for measuring the risk rating of icicle falling;
• a risk index determining module, configured to select a risk indicator and determine a risk index of a current risk indicator according to a real-time growth status of the icicles;
• a risk assessment module, configured to perform a multi-parameter fusion analysis according to the risk index, and assess a risk of icicles falling;
• and
• a decision early warning module, configured to perform a risk decision and an early warning according to a method of combining results of risk of falling with a dynamic threshold, and periodically perform component calibration and dynamic baseline correction according to the results of risk of falling.