Network Theory and Distributive Infrastructure Systems

Question 1

What is physical dependence (between infrastructure systems)?

Answer 1

Systems share a direct material connection. The physical state of one changes the state of another.

Question 2

What is informative dependence (between infrastructure systems)?

Answer 2

Systems are connected via information (usually computational) flow. System state depends on signal of another.

Question 3

What is geographical dependence (between infrastructure systems)?

Answer 3

Systems are connected by geographic proximity. In the same location or close by.

Question 4

What is logical dependence (between infrastructure systems)?

Answer 4

Any other kind of connection (that isn’t physical, informative, or geographical), that is related to human decisions. Policy, procedural, societal, economic, …

Question 5

What is an interdependency matrix?

Answer 5

Rows (i) and columns (j) filled with civil/infrastructure systems. Matrix is filled with dependencies between systems (how does j depend on i).

Question 6

Define Network.
Define Graph.

Answer 6

Network: relational representation of a complex system
Graph: mathematical object that we analyse

Question 7

What are some network characteristics?

Answer 7

Direction: If links are directed, it is a directed network. If links are not directed, it is an undirected network.
Connection: Fully connected if every node connected by links (cliques). A disconnected network if not (subnetworks)
Planar/non-planar: A planar network is one where all links that cross form a node.

Question 8

What is the size of a network?

Answer 8

Number of nodes

Question 9

What is the shortest path of a network?

Answer 9

The shortest distance (usually the lowest number of links) between two nodes.

Question 10

What is the diameter of a network?

Answer 10

The length of shortest path between the most distanced nodes.

Question 11

What is the number of cycles of a network?

Answer 11

The number of loops in a network.
mu = L - N + S
higher mu = more complex

Question 12

What is the beta-index of a network?

Answer 12

A simple measure of network complexity.
Beta = L/N.
(Basically saying more links is more complex)

Question 13

What is the degree of connectivity

Answer 13

Ratio of actual to potential number of links. Symbol: gamma.
Non-planar: Gamma(np) = L /[1/2 * (N-1) *N]
Planar: Gamma(p) = L / (3N - 6)

Question 14

How would you represent an undirected network as a matrix?

Answer 14

Aij where:
A = 1 if connected
A = 0 if not connected

Question 15

How would you represent a directed network as a matrix?

Answer 15

Aij where:
A = 1 if there is a j -> i connection
A = 0 otherwise.

For example if there is a [Node 1] -> [Node 3] connection,
A31 = 1.

Question 16

What is the node degree?

Answer 16

The number of connections on node i.
For an undirected network:
ki = sum_j(Aij)
For a directed network:
ki(in) = sum_j(Aij)
ki(out) = sum_j(Aji)

Question 17

In node statistics, what is eigenvalue centrality?

Answer 17

Centrality based on importance of neighbours

Question 18

In node statistics, what is closeness centrality?

Answer 18

Centrality based on access to all other nodes

Question 19

In node, statistics, what is betweenness centrality?

Answer 19

Centrality based on usefulness connecting any node to another

Question 20

What are some examples of distributive systems (one-to-many)?

Answer 20

Energy/electricity, water supply, food, …
Note, these have connections to other systems too (interconnected)
One-to-many has one point-source (distributor) and many consumers.

Question 21

What is the energy system, according to the IPCC?

Answer 21

All components related to the production, conversion, delivery and use of energy (electricity, heat, transport).

Question 22

What is a primary energy source/fuel?

Answer 22

Original or undisturbed state (sun, waves, crude oil, coal).

Question 23

What is a secondary energy source/fuel?

Answer 23

Converted from primary energy (electricity, heat, …)
Note: conversion results in losses. It is never 100% efficient. Difference between E available, produced and consumed.

Question 24

NZ’s system is ~X% fossil fuel and ~Y% renewable.

Answer 24

60% FF
40% Renewable

Question 25

NZ energy consumption is dominated by ______ and _____.

Answer 25

Industry and transportation

Question 26

Electricity is a key piece in the energy system, so is it key for mitigation?

Answer 26

Yes. Not much of total energy comes from low-carbon sources, but more than one-third of global electricity does! 2 key strategies are to
1. Decarbonise/defossilise
2. Electrify (make more things rely on electricity in the future)

Question 27

Most modern electricity systems are ______ systems.

Answer 27

Centralised (distributive).
Traditional system structure is distributive, but “new” network designs are focused on system flexibility (decentralised generation, energy storage, mini/micro grid).

Question 28

Outline the stages of the grid (generation to consumption).

Answer 28

Generation –> Transmission –> Distribution –> Consumption (your house)

Question 29

Availability of good-quality water can be reduced because of …

Answer 29

Urban development, industrial growth, environmental pollution …
Broadly: built infrastructure.

Question 30

Our modern water supply infrastructure includes …

Answer 30

Storage, treatment, distribution (pipes), network (pumps, pipes, storage, treatment), energy inputs (pumps, storage, treatment) –> CO2 footprint.

Question 31

What are the main components of water supply?

Answer 31

Collect/store, treatment, distribution (about 18% losses in urban areas due to leakage from treatment through to distribution).

Question 32

What are some system innovations to combat water scarcity?

Answer 32

Desalination plant, “Purple Pipes” (recycled water), WSUD, alternative water sources (minimising water demand), alternative water uses.

Question 33

The largest source of emissions in the food system is from …

Answer 33

Livestock (enteric fermentation).

Question 34

Emissions from the NZ food system are heavily skewed towards …

Answer 34

Meat and dairy.
(Agriculture was 37.7% of NZs emissions in 2018 and most of that is livestock)

Question 35

The food system affects not just GHG emissions but also …

Answer 35

Biodiversity, eutrophication, freshwater use, land use.
(Food system relies on energy and water)

Question 36

How can we mitigate the climate change impact of the ENERGY system on the PRODUCTION side?

Answer 36

Transition away from F.F.

Question 37

How can we mitigate the climate change impact of the ENERGY system on the CONSUMPTION side?

Answer 37

Improve energy efficiency.

Question 38

How can we mitigate the climate change impact of the ELECTRICITY system on the PRODUCTION side?

Answer 38

Zero/low carbon electricity generation (hydro, solar, wind, geothermal, biomass, nuclear).

Question 39

How can we mitigate the climate change impact of the ELECTRICITY system on the CONSUMPTION side?

Answer 39

Minimising energy use (at different times of day/year). Efficiency.

Question 40

How can we mitigate the climate change impact of the WATER SUPPLY system on the PRODUCTION side?

Answer 40

Energy-efficient improvements (or maybe minimisation of energy required), especially in distribution and treatment.

Question 41

How can we mitigate the climate change impact of the WATER SUPPLY system on the CONSUMPTION side?

Answer 41

Reduce demand for treated water (water efficiency, water re-use/alternative water use).

Question 42

How can we mitigate the climate change impact of the FOOD system on the PRODUCTION side?

Answer 42

Minimise emissions from enteric fermentation (CH4). Minimise energy and fertiliser requirements.

Question 43

How can we mitigate the climate change impact of the FOOD system on the CONSUMPTION side?

Answer 43

Reduce demand for high-emissions ‘products’. (E.g. meat)

Question 44

What is energy?

Answer 44

Capacity to do work.

Question 45

Distributive systems are represented with:

Answer 45

A point-source provider and many end users

Question 46

Emissions in the food system are mostly:

Answer 46

Methane emitted from enteric fermentation.