New method equivalent for the calculation of g-functions

[MassimoCimmino]

This issue is to implement a new calculation method for g-functions introduced in [1]. The method uses hierarchical agglomerative clustering to identify an optimal number of equivalent boreholes sufficient for the evaluation of g-functions in large bore fields.

This method is an approximation of the already implemented methods (detailed and similarities). It provides significant reductions in calculation time and memory usage.

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[1] Prieto, C. & Cimmino, M., 2021. Thermal interactions in large irregular fields of geothermal boreholes: the method of equivalent borehole. Journal of Building Performance Simulation, 14 (4): 446-460.

[MassimoCimmino]

Same test cases as in #78.

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Case 1 : Rectangular fields up to 20 by 20

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Case 2 : Number of segments for a 5 by 5 bore field

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Case 3 : Field of 100 boreholes with 2 different lengths

[MassimoCimmino]

Case 1' : Rectangular fields up to 20 by 20 (kClusters=2)