Consider the following statements for a network graph, if Bf is its fundamental tie set matrix, and Bt and Bl are its sub-matrices corresponding to twigs and links, respectively: 1. Bt is a unit matrix 2. Bl is a rectangular matrix 3. Rank of Bf is (b – n + 1) where b is the number of branches and n is the number of nodes. Which of the above statements are correct?
Consider the following statements for a network graph, if Bf is its fundamental tie set matrix, and Bt and Bl are its sub-matrices corresponding to twigs and links, respectively: 1. Bt is a unit matrix 2. Bl is a rectangular matrix 3. Rank of Bf is (b – n + 1) where b is the number of branches and n is the number of nodes. Which of the above statements are correct? Correct Answer 2 and 3 only
Fundamental loop: A fundamental loop is a closed path of a given graph with only one Link and the rest of them as twigs.
The number of fundamental loops for any given graph = b – (n – 1) = number of Links
These fundamental loop currents are called Tie set currents and the orientation of the tie set currents governed by the link.
=
= +1, If jth branch current is incident at ith tie set current at oriented in the same direction.
= –1, if jth branch current is incident at ith tie set current at oriented in the opposite direction.
= 0, If jth branch current is not incident with ith tie set current.
For the above graph, the tie set matrix is given by
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We can rearrange the matrix as given below.
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Tie set currents and branch currents together form an identity matrix as marked in the above Tie set matrix.
Now, from the above matrix, it is clear that,
- The submatrix corresponding to twigs (Bt) is not an identity matrix
- The submatrix corresponding to twigs (Bl) is an identity matrix and a rectangular matrix
- The rank of tie set matrix is b – (n – 1) i.e. 3 for the above matrix