Network Theory and Distributive Infrastructure Systems Flashcards by Jay Kang

What is physical dependence (between infrastructure systems)?

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

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What is informative dependence (between infrastructure systems)?

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

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What is geographical dependence (between infrastructure systems)?

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

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What is logical dependence (between infrastructure systems)?

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

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What is an interdependency matrix?

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

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Define Network.
Define Graph.

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

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What are some network characteristics?

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.

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What is the size of a network?

Number of nodes

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What is the shortest path of a network?

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

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What is the diameter of a network?

The length of shortest path between the most distanced nodes.

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What is the number of cycles of a network?

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

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What is the beta-index of a network?

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

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What is the degree of connectivity

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)

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How would you represent an undirected network as a matrix?

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

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How would you represent a directed network as a matrix?

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.

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What is the node degree?

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)

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In node statistics, what is eigenvalue centrality?

Centrality based on importance of neighbours

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In node statistics, what is closeness centrality?

Centrality based on access to all other nodes

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In node, statistics, what is betweenness centrality?

Centrality based on usefulness connecting any node to another

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

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.

What is the energy system, according to the IPCC?

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

What is a primary energy source/fuel?

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

What is a secondary energy source/fuel?

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

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

60% FF
40% Renewable

NZ energy consumption is dominated by ______ and _____.

Industry and transportation

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

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)

Most modern electricity systems are ______ systems.

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

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

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

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

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

Our modern water supply infrastructure includes ...

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

What are the main components of water supply?

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

What are some system innovations to combat water scarcity?

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

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

Livestock (enteric fermentation).

Emissions from the NZ food system are heavily skewed towards ...

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

The food system affects not just GHG emissions but also ...

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

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

Transition away from F.F.

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

Improve energy efficiency.

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

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

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

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

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

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

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

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

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

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

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

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

What is energy?

Capacity to do work.

Distributive systems are represented with:

A point-source provider and many end users

Emissions in the food system are mostly:

Methane emitted from enteric fermentation.