Product multi-source adaptive change propagation influence intensity calculation method based on path coupling

Abstract

The invention relates to a product multi-source adaptive change propagation influence intensity calculation method based on path coupling, and belongs to the technical field of engineering change. The method comprises the following steps: constructing a product adaptive change propagation network according to a propagation influence relationship among product parts, identifying coupling nodes and coupling paths of multi-source adaptive change propagation, and determining the correlation of structure change attribute changes of corresponding parts caused when the coupling nodes are influenced by different change source propagation; and calculating the direct propagation influence intensity of the front-end node of the coupling path on the rear-end node during multi-source change, and calculating the multi-source adaptive change propagation influence intensity of the product according to the correlation of the coupling path, the direct propagation influence intensity of the coupling node and the change complexity of the part. According to the method, the coupling nodes and the coupling paths of multi-source adaptive change can be effectively identified, the product design efficiency can be improved, the change cost can be reduced, and a basis is provided for adaptive change in a product personalized customization process.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering changes, and in particular to a method for calculating the propagation impact intensity of multi-source adaptive changes of products based on path coupling. Background Art

[0002] Adaptive change is the process of redesigning products in response to changes in customer personalized needs, with the aim of meeting market and customer needs through adjustments to product structure. In the actual process of product adaptive change, sometimes several parts initiate changes at the same time, which is called multi-source change. The propagation path and propagation range of multi-source changes will change. During the multi-source change propagation process, the propagation path may be coupled, making the entire adaptive change propagation process more complicated. The coupling path has an important impact on the adaptive change propagation network, which increases the complexity and change risk of the network and increases the possibility of change conflicts. By analyzing the coupling path, we can better evaluate the risk of adaptive changes and predict the scope of change, so as to carry out targeted design optimization and improvement and improve the adaptability of product design.

[0003] The existing publicly available method for calculating the propagation intensity of product design changes is based on the propagation risk or propagation probability between nodes, and uses complex network analysis technology to calculate the propagation intensity of nodes or select the optimal path, thereby realizing the influence judgment of nodes or modules.

[0004] CN 117236449 A discloses a method for identifying the influence of parts which is suitable for both single-source changes and multi-source changes. The difference between the propagation intensity calculation of multi-source changes and single-source changes is only that the propagation reachability index and the part change complexity index are different due to the different total number of nodes in the change propagation network. The method does not involve the role of coupling paths in the propagation of multi-source changes. In actual multi-source changes, path coupling is inevitable, which will make the change propagation process more complicated and affect the product change time and change cost.

[0005] CN118295695A discloses a method for module type identification and adaptive change impact calculation of an open architecture product. Based on the physical connection relationship between modules, the dependency level between modules is determined, and the dependency coupling between modules is calculated, thereby determining the adaptive change impact between modules. However, it only targets the direct propagation impact between modules, and does not involve indirect propagation of modules or propagation path coupling. Summary of the invention

[0006] The purpose of the present invention is to analyze the propagation process of multi-source adaptive changes of products. Considering the coupling of propagation paths, the present invention proposes a method for calculating the impact intensity of multi-source adaptive changes of products based on path coupling, which provides method guidance for effectively managing product customization and adaptive changes.

[0007] The method for calculating the propagation impact intensity of multi-source adaptive changes of products based on path coupling of the present invention specifically comprises the following steps:

[0008] Step 1: Based on the propagation influence relationship between product parts, a product adaptive change propagation network is constructed to analyze the nodes and paths of the common propagation influence of multi-source adaptive changes, and identify the coupling nodes and coupling paths of multi-source adaptive change propagation;

[0009] Step 2, for the coupling nodes and coupling paths determined in step 1, analyzing the change propagation properties of the nodes on the coupling paths, and determining the complete negative correlation, irrelevance, and complete positive correlation of the structural change property changes of the corresponding parts caused by the coupling nodes being affected by the propagation of different change sources;

[0010] Step 3, for the coupling nodes and coupling paths determined in step 1, analyzing the change propagation properties of the nodes on the coupling paths, and calculating the correlation between the coupling paths when the coupling nodes are affected by different change source propagations;

[0011] Step 4, for the complete negative correlation, irrelevance and complete positive correlation of the structural change attribute changes of the coupling nodes determined in step 2, calculate the direct propagation influence intensity of the front-end node of the coupling path on the back-end node when different change sources are used;

[0012] Step 5, for the correlation between the coupling paths determined in step 3, calculate the direct propagation influence intensity of the front-end node of the coupling path on the back-end node when different change sources are used;

[0013] Step 6, according to the correlation of the coupling path, the direct propagation impact strength of the coupling node, and the change complexity of the part, the multi-source adaptive change propagation impact strength of the part corresponding to the uncoupled node is calculated;

[0014] Step 7, according to the correlation of the coupling path, the direct propagation impact strength of the coupling node, and the change complexity of the part, calculate the multi-source adaptive change propagation impact strength of the part corresponding to the coupling node.

[0015] In step 1, according to the propagation influence relationship between product parts, a product adaptive change propagation network is constructed, the nodes and paths of the common propagation influence of multi-source adaptive changes are analyzed, and the coupling nodes and coupling paths of the multi-source adaptive change propagation are identified;

[0016] The reachability matrix is ​​used to determine the nodes affected by each change source propagation. Nodes affected by different change sources are called coupled nodes. When two nodes A and B are both change sources, the coupled node set can be expressed as V A×B =V A ∩V B , where VA and V B They represent the node sets affected by the propagation when nodes A and B are independent change sources. The direct propagation path between coupled nodes is called the coupling path. When the direct propagation path between two nodes is generated by the joint propagation of two or more change sources, it is called path coupling. If the coupled node v i Direct propagation affects the coupling node v j , then the coupling path can be expressed as where v i 、v j ∈V A×B .

[0017] In step 2, for the coupling nodes and coupling paths determined in step 1, the change propagation properties of the nodes on the coupling paths are analyzed to determine the complete negative correlation, irrelevance, and complete positive correlation of the structural change property changes of the corresponding parts caused by the coupling nodes being affected by the propagation of different change sources;

[0018] According to the changed attributes of the change source, determine the corresponding part structure change attributes of each node on the multi-source adaptive change propagation path, and judge the correlation of the change of the part structure change attributes corresponding to the coupling node; when node A is the change source, the coupling path Previous node v j When the structural attribute changes with node B as the change source Previous node v j The coupling path is considered to be Not relevant, remember When the coupling path Previous node v j When nodes A and B are both change sources, the same structural attribute is affected by the propagation and the change trend is the same, then the coupling paths are considered to be completely positively correlated, and the When the coupling path Previous node v j When nodes A and B are both change sources, the same structural attribute is affected by the propagation and the change trends are opposite, then the coupling path is considered to be completely negatively correlated, and is recorded as

[0019] In step 3, for the coupling nodes and coupling paths determined in step 1, the change propagation properties of the nodes on the coupling paths are analyzed, and the correlation between the coupling paths when the coupling nodes are affected by different change source propagations is calculated;

[0020] The structural property changes of the parts corresponding to the nodes are regarded as vectors, and the correlation between the two vectors is measured by the vector cosine value. Previous node v jWhen node A is the source of the change, the structural attribute change affected by the propagation is X, and node v j When node B is the source of change, the change in the structural attribute affected by the propagation is Y, then the correlation between the two is

[0021]

[0022] Where |X| and |Y| represent the moduli of X and Y respectively, and X·Y represents the dot product of X and Y.

[0023] In step 4, for the complete negative correlation, irrelevance and complete positive correlation of the structural change attribute changes of the coupling nodes determined in step 2, the direct propagation influence intensity of the front-end node of the coupling path on the back-end node is calculated for different change sources;

[0024] For the coupling path v i is the front node of the propagation path, v j is the back-end node of the propagation path, denoted by I(A) vi,j When node A is the source of changes, node v i v j The direct transmission impact intensity, I(B) vi,j When node B is the source of changes, node v i v j The direct propagation influence strength of node v is i v j The direct transmission impact intensity is recorded as

[0025] The direct transmission impact intensity between nodes when node A is a single source change can be calculated as follows:

[0026] I(A) vi,j =p i,j ×S(A) Sj ,

[0027] In the formula, p i,j For node v i v j Adaptive change propagation probability, S(A) Sj When node A is the source of changes, node v j The adaptive change complexity index of the corresponding parts;

[0028] S(A) Sj =S(A) Cj / S(A) Cmax ,

[0029]

[0030] In the formula, C(A) vj When node A is the source of the change, node v j Corresponding parts change cost, T(A) vj For node v j Corresponding parts change time, C(A) P is the sum of the cost of changing all parts of the product, T(A) P is the sum of the change times of all parts of the product, S(A) Cmax The maximum value of the adaptive change complexity of all parts when node A is the change source;

[0031] The same method can be used to calculate the direct inter-node propagation impact intensity I(B) when node B is a single source change. vi,j ;

[0032] but It can be expressed as

[0033]

[0034] In step 5, for the correlation between the coupling paths determined in step 3, the direct propagation influence intensity of the front-end node of the coupling path on the back-end node is calculated for different change sources;

[0035] when , which means that nodes A and B are both sources of change when the coupling path Has partial correlation, then node v i v j The direct transmission impact intensity is calculated as follows;

[0036] when hour,

[0037]

[0038] when hour,

[0039]

[0040] In step 6, the multi-source adaptive change propagation impact intensity of the parts corresponding to the uncoupled nodes is calculated according to the correlation of the coupling paths, the direct propagation impact intensity of the coupled nodes, and the change complexity of the parts;

[0041] When nodes A and B are both change sources, if v i is an uncoupled node, then v i Adaptive change propagation impact strength for

[0042]

[0043] Where N vi For node v i The number of other nodes affected by direct propagation, R vi Node v i The number of other nodes affected by indirect propagation, N is the total number of nodes in the adaptively changed propagation network, and w 1 and w 2 is the weight, w 1 +w 2 =1;

[0044] In step 7, the multi-source adaptive change propagation impact intensity of the part corresponding to the coupling node is calculated according to the correlation of the coupling path, the direct propagation impact intensity of the coupling node, and the change complexity of the part;

[0045] When nodes A and B are both change sources, if v i When it is a coupling node, v i Adaptive change propagation impact strength for

[0046]

[0047] Where N 1vi For node v i Direct propagation affects the number of other coupled nodes, N 2vi For node v i Direct propagation affects the number of other uncoupled nodes;

[0048] When node v i To change the termination node,

[0049] For multi-source changes where three or more nodes are simultaneously the change source, the direct propagation influence intensity between the coupled nodes in the formula is The coupling paths of the corresponding multiple node change sources should be considered, and the correlation of the structural change attribute changes of the coupled nodes also needs to be analyzed according to the corresponding multiple node change sources.

[0050] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0051] (1) According to the change attributes of different change sources, the structural change attribute correlation of the parts corresponding to the nodes on the coupling path is determined, and the direct propagation influence intensity of the front-end node of the coupling path on the back-end node when multiple sources are changed is calculated. This is consistent with the actual product multi-source design changes and quantifies the coupling influence of the propagation path.

[0052] (2) The correlation of the coupling path, the direct propagation impact strength of the coupling node, and the change complexity of the parts are used to calculate the multi-source adaptive change propagation impact strength of the parts. This can effectively reflect the coupling impact of the multi-source adaptive change propagation path, and the calculation is simple and effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is the adaptive change propagation network when part 1 is the sole change source;

[0054] Figure 2 It is the adaptive change propagation network when part 9 is the sole change source;

[0055] Figure 3 It is the adaptive change propagation network when parts 1 and 9 are both change sources. DETAILED DESCRIPTION

[0056] This embodiment provides a method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling, including the following steps:

[0057] Step 1: Based on the propagation influence relationship between product parts, a product adaptive change propagation network is constructed to analyze the nodes and paths of the common propagation influence of multi-source adaptive changes, and identify the coupling nodes and coupling paths of multi-source adaptive change propagation;

[0058] Step 2, for the coupling nodes and coupling paths determined in step 1, analyzing the change propagation properties of the nodes on the coupling paths, and determining the complete negative correlation, irrelevance, and complete positive correlation of the structural change property changes of the corresponding parts caused by the coupling nodes being affected by the propagation of different change sources;

[0059] Step 3, for the coupling nodes and coupling paths determined in step 1, analyzing the change propagation properties of the nodes on the coupling paths, and calculating the correlation between the coupling paths when the coupling nodes are affected by different change source propagations;

[0060] Step 4, for the complete negative correlation, irrelevance and complete positive correlation of the structural change attribute changes of the coupling nodes determined in step 2, calculate the direct propagation influence intensity of the front-end node of the coupling path on the back-end node when different change sources are used;

[0061] Step 5, for the correlation between the coupling paths determined in step 3, calculate the direct propagation influence intensity of the front-end node of the coupling path on the back-end node when different change sources are used;

[0062] Step 6, according to the correlation of the coupling path, the direct propagation impact strength of the coupling node, and the change complexity of the part, the multi-source adaptive change propagation impact strength of the part corresponding to the uncoupled node is calculated;

[0063] Step 7, according to the correlation of the coupling path, the direct propagation impact strength of the coupling node, and the change complexity of the part, calculate the multi-source adaptive change propagation impact strength of the part corresponding to the coupling node.

[0064] The following uses a certain type of automobile loading and unloading tailgate as an application example of a method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling in this embodiment. The parts list of the automobile loading and unloading tailgate is shown in the following table;

[0065] Serial number name Serial number name 1 Tailgate Panel 7 Side inclined beam 2 Front leaf plate 8 Straight beam 3 Small and medium beams 9 Lifting arm 4 Medium and large beam 10 Lifting cylinder 5 Diagonal beam 11 Closing cylinder 6 Side beam 12 Safety guardrail

[0066] The specific implementation process is as follows:

[0067] The adaptive change propagation network of the tailgate is constructed by taking the tailgate parts as nodes, the dependencies between the parts as edges, and the adaptive change propagation probability as the edge weight.

[0068] When the node v 1 As a single source of changes, the adaptive change propagation network is Figure 1 As shown; node v 1 The changes to v are not propagated to node v 9 、v 10 、v 11 ;according to Figure 1 Adaptively change the propagation network and calculate the number of other nodes affected by direct propagation of the node and the number of other nodes affected by indirect propagation, as shown in the following table;

[0069] Node number <![CDATA[N vi ]]> <![CDATA[R vi ]]> 1 4 8 2 2 7 3 2 2 4 1 1 5 4 4 6 0 0 7 0 0 8 3 3 12 0 0

[0070] According to the structural complexity of the tailgate parts of automobile loading and unloading, the adaptive change time and change cost of the parts are analyzed, and the adaptive change complexity and adaptive change complexity index of the parts are calculated as shown in the following table;

[0071]

[0072]

[0073] According to the adaptability between parts, the propagation probability, the number of nodes directly propagated and affected by other nodes, the number of nodes indirectly propagated and affected by other nodes, the structural change complexity index of the parts, and the weight w 1 and w 2 Set them to 0.5 respectively and calculate v 1 The adaptive change propagation strength of the parts when the source is changed individually is shown in the following table;

[0074] Node number Adaptively change the propagation strength 1 0.5294 2 0.4514 3 0.1578 4 0.0733 5 0.2874 6 0 7 0 8 0.2112 12 0

[0075] When the node v 1 As a separate change source, v1 The change propagation intensity of is the largest, that is, it has the greatest influence, followed by v 2 、v 5 and v 8 . Node v 6 、v 7 、v 12 The change propagation impact strength is 0 because they are adaptive changes to the terminal nodes;

[0076] When the node v 9 As a single source of change, adaptive change propagation directed weighted networks such as Figure 2 As shown; node v 9 The changes to v are not propagated to node v 1 、v 2 、v 8 、v 12 ;according to Figure 2 Adaptive change propagation directed weighted network, calculate the number of nodes directly propagated to affect other nodes and the number of nodes indirectly propagated to affect other nodes, as shown in the following table;

[0077]

[0078] According to the adaptability between parts, the propagation probability, the number of nodes directly propagated and affected by other nodes, the number of nodes indirectly propagated and affected by other nodes, the structural change complexity index of the parts, and the weight w 1 and w 2 Set them to 0.5 respectively and calculate v 9 The adaptive change propagation strength of the parts when the source is changed individually is shown in the following table;

[0079] Node number Adaptively change the propagation strength 3 0.1717 4 0.0802 5 0.2965 6 0 7 0 9 1.0375 10 0 11 0.3722

[0080] When the node v 9 As a separate change source, v 9 The change propagation intensity of is the largest, that is, it has the greatest influence, followed by v 11 、v 5 and v 3 . Node v 6 、v 7 、v 10 The change propagation impact strength of is 0, because they are adaptive changes to the terminal node;

[0081] When the node v 1 and v 9 When acting as a change source, the adaptive change propagation network is Figure 3 As shown; node v 3 、v 4 、v 5 、v 6 and v7 Receiving point v 1 and v 9 The common influence of Figure 3 Adaptive change propagation directed weighted network, calculate the number of nodes directly propagated to affect other nodes and the number of nodes indirectly propagated to affect other nodes, as shown in the following table;

[0082] Node number <![CDATA[N vi ]]> <![CDATA[R vi ]]> Node number <![CDATA[N vi ]]> <![CDATA[R vi ]]> 1 4 8 7 0 0 2 2 7 8 3 3 3 2 2 9 2 7 4 1 1 10 0 0 5 4 4 11 1 6 6 0 0 12 0 0

[0083] According to the adaptability between parts, the propagation probability, the number of nodes directly propagated and affected by other nodes, the number of nodes indirectly propagated and affected by other nodes, the structural change complexity index of the parts, and the weight w 1 and w 2 Set them to 0.5 respectively and calculate v 1 and v 9 The adaptive change propagation strength of the parts when both are change sources is shown in the following table;

[0084]

[0085] When the node v 1 and v 9 When used as a change source, v 9 The change propagation intensity of is the largest, that is, it has the greatest influence, followed by v 1 、v 2 and v 11 . Node v 6 、v 6 、v 10 、v 12 The change propagation impact strength of is 0, because they are adaptive changes to the terminal node;

[0086] It can be seen that when different parts of the automobile loading and unloading tailgate are used as change sources, their propagation paths and ranges are also different, and the propagation impact intensity of the adaptive change of the nodes is also different.

Claims

1. A method for calculating the propagation impact intensity of multi-source adaptive changes of products based on path coupling, characterized in that: The method comprises the following steps: Step 1: Based on the propagation influence relationship between product parts, construct the product adaptive change propagation network, analyze the nodes and paths of the common propagation influence of multi-source adaptive changes, and identify the coupling nodes and coupling paths of multi-source adaptive change propagation; Step 2: For the coupling nodes and coupling paths determined in step 1, analyze the change propagation properties of the nodes on the coupling paths, and determine the complete negative correlation, irrelevance, and complete positive correlation of the structural change property changes of the corresponding parts caused by the coupling nodes being affected by the propagation of different change sources; Step 3: For the coupling nodes and coupling paths determined in step 1, analyze the change propagation properties of the nodes on the coupling paths, and calculate the correlation between the coupling paths when the coupling nodes are affected by different change source propagations; Step 4: For the complete negative correlation, irrelevance and complete positive correlation of the structural change attribute changes of the coupling nodes determined in step 2, calculate the direct propagation influence intensity of the front-end node of the coupling path on the back-end node when different change sources are used; Step 5: For the correlation between the coupling paths determined in step 3, calculate the direct propagation influence intensity of the front-end node of the coupling path on the back-end node when different change sources are used; Step 6: Calculate the multi-source adaptive change propagation impact intensity of the corresponding parts of the uncoupled nodes according to the correlation of the coupling paths, the direct propagation impact intensity of the coupling nodes, and the change complexity of the parts; Step 7: According to the correlation of the coupling path, the direct propagation impact strength of the coupling node, and the change complexity of the part, calculate the multi-source adaptive change propagation impact strength of the part corresponding to the coupling node.

2. According to the method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling in claim 1, it is characterized in that: In step 1, Nodes that are affected by different change sources are called coupled nodes. When two nodes A and B are change sources at the same time, the set of coupled nodes can be represented as V A×B =V A ∩V B , where V A and V B They represent the node sets affected by the propagation when nodes A and B are independent change sources. The direct propagation path between coupled nodes is called the coupling path. When the direct propagation path between two nodes is generated by the joint propagation of two or more change sources, it is called path coupling. If the coupled node v i Direct propagation affects the coupling node v j , then the coupling path can be expressed as Path(A⊕B) vi→vj , where v i 、v j ∈V A×B .

3. According to the method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling in claim 1, it is characterized in that: In step 2, According to the changed attributes of the change source, determine the part structure change attributes corresponding to each node on the multi-source adaptive change propagation path, and judge the correlation of the part structure change attribute changes corresponding to the coupling node; When node A is the source of change, the coupling path Path (A⊕B) vi→vj Previous node v j When the structural attribute changes and node B is the change source, Path(A⊕B) vi→vj Previous node v j If there is no correlation between the structural property changes of , then the coupling path Path(A⊕B) is considered vi→vj Not related, record R(A⊕B) i，j =0; When the coupling path Path(A⊕B) vi→vj Previous node v j When nodes A and B are both change sources, the same structural attribute is affected by the propagation and the change trend is the same, then the coupling paths are considered to be completely positively correlated, and are recorded as R(A⊕B) i，j =1; when coupling path Path(A⊕B) vi→vj Previous node v j When nodes A and B are both change sources, the same structural attribute is affected by the propagation and the change trends are opposite, then the coupling paths are considered to be completely negatively correlated, denoted by R(A⊕B) i，j =-1.

4. According to the method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling in claim 1, it is characterized in that: In step 3, The structural property changes of the parts corresponding to the nodes are regarded as vectors, and the correlation between the two vectors is measured by the vector cosine value. Previous node v j When node A is the source of the change, the structural attribute change affected by the propagation is X, and node v j When node B is the source of change, the change in the structural attribute affected by the propagation is Y, then the correlation between the two is Where |X| and |Y| represent the moduli of X and Y respectively, and X·Y represents the dot product of X and Y.

5. According to the method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling in claim 1, it is characterized in that: In step 4, For the coupling path v i is the front node of the propagation path, v j is the back-end node of the propagation path, denoted by I(A) vi,j When node A is the source of changes, node v i v j The direct transmission impact intensity, I(B) vi,j When node B is the source of changes, node v i v j The direct propagation influence strength of node v is i v j The direct transmission impact intensity is recorded as I(A⊕B) vi，j ; The direct transmission impact intensity between nodes when node A is a single source change can be calculated as follows: I(A) vi,j =p i,j ×S(A) Sj , In the formula, p i,j For node v i v j Adaptive change propagation probability, S(A) Sj When node A is the source of changes, node v j The adaptive change complexity index of the corresponding parts; S(A) Sj =S(A) Cj / S(A) Cmax , In the formula, C(A) vj When node A is the source of the change, node v j Corresponding parts change cost, T(A) vj For node v j Corresponding parts change time, C(A) P is the sum of the cost of changing all parts of the product, T(A) P is the sum of the change times of all parts of the product, S(A) Cmax is the maximum value of the adaptive change complexity of all parts when node A is the change source; The same method can be used to calculate the direct inter-node propagation impact intensity I(B) when node B is a single source change. vi,j ; Then when hour, It can be expressed as 6. According to the method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling in claim 1, it is characterized in that: In step 5, when , which means that nodes A and B are both sources of change when the coupling path Has partial correlation, then node v i v j The direct transmission impact intensity is calculated as follows; when hour, when hour, 7. According to the method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling in claim 1, it is characterized in that: In step 6, When nodes A and B are both change sources, if v i is an uncoupled node, then v i Adaptive change propagation impact strength for Where N vi For node v i The number of other nodes affected by direct propagation, R vi Node v i Indirect propagation affects the number of other nodes, N is the total number of nodes in the adaptive change propagation network, w1 and w2 are weights, w1+w2=1.

8. The method for calculating the impact intensity of multi-source adaptive change propagation of products based on path coupling according to claim 1 is characterized in that: In step 7, When nodes A and B are both change sources, if v i When it is a coupling node, v i Adaptive change propagation impact strength for Where N 1vi For node v i Direct propagation affects the number of other coupled nodes, N 2vi For node v i Direct propagation affects the number of other uncoupled nodes.

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