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transportation and movement between nodes in the system. Nodes and edges on the
graph are located in space and time. The edges in the graph are the “couplings”
between agents, and these edges represent directional (or bidirectional) and flows of
mass, energy, information, goods, and services. These stocks and flows change over
time. This FEW system process network structure is a close relation to the environmentally extended and multi-regional input–output data models (I/O, Miller and
Blair 2009). However, the FEW system is more complicated than I/O, because it
considers stocks, storage, environmental impacts, and boundaries in the system in
addition to the characterization of the system’s nodes and their inputs and outputs.
Inputs and Outputs are the flows of goods and services in and out of a process.
These inputs and outputs may include raw materials, finished products and services,
and wastes. Input–output coefficients describe the efficiency of a process and the
connectedness between input and output stocks and flows. Stocks are accounted for
quantities of material, goods, currency, and so on that exist at a specific space-time
location. Stocks may be human (e.g., bank account, gasoline tank) or natural (e.g.,
aquifer, coal seam), and are often synonymous with storage or buffers in the system.
Flows are accounted quantities of material, good, currency, and so on that move
from one space-time location to another—that is, from an origin to a destination,
from a producer to a consumer, and so on. Flows may be human (e.g., currency payment, oil by pipeline) or natural (e.g., water in a river). Natural flows are often
considered ecosystem services. Flows may be valuable, as in the instance of goods
and services or currencies, but they may also be undesirable, such as flows of wastes
and pollutants. Information also flows. Origins and Destinations identify the
space-time locations where a good or service was transported (or flowed) from, and
to, respectively. Route identifies the precise mode of transport, pathway, and waypoints followed by a flow that transports a good or service. Agents are the natural
or human entities who control stocks, and who produce, consume, originate, terminate, and take inputs and outputs concerning flows; natural processes may be characterized as agents with predictable behavior.
Ontologies name and describe the categories of objects in a dataset and the relationships between these types. Subtypes of ontologies include controlled vocabularies or codesheets which are lists of categories and objects that are allowable in a
dataset, and data models (or object–entity relationship diagrams) detail the formats
and relationships between different objects in a dataset (e.g. Ruddell and
Kumar 2006).
An ontology is a conceptualization of categories that captures their qualitative
types and describes the relationships between different types. Establishments and
processes (or aggregations thereof) need to be named using controlled vocabularies. “Codes” are a very simple type of controlled vocabulary. For example, the
North American Industry Classification System (NAICS, OMB 2017) is a coding
system that categorizes different types of business establishments according to the
general type of goods and services they produce. NAICS was created for the
U.S. Census Bureau in partnership with Canadian and Mexican authorities to
track business and tax statistics in North America—but not for FEW systems
B. L. Ruddell
transportation and movement between nodes in the system. Nodes and edges on the
graph are located in space and time. The edges in the graph are the “couplings”
between agents, and these edges represent directional (or bidirectional) and flows of
mass, energy, information, goods, and services. These stocks and flows change over
time. This FEW system process network structure is a close relation to the environmentally extended and multi-regional input–output data models (I/O, Miller and
Blair 2009). However, the FEW system is more complicated than I/O, because it
considers stocks, storage, environmental impacts, and boundaries in the system in
addition to the characterization of the system’s nodes and their inputs and outputs.
Inputs and Outputs are the flows of goods and services in and out of a process.
These inputs and outputs may include raw materials, finished products and services,
and wastes. Input–output coefficients describe the efficiency of a process and the
connectedness between input and output stocks and flows. Stocks are accounted for
quantities of material, goods, currency, and so on that exist at a specific space-time
location. Stocks may be human (e.g., bank account, gasoline tank) or natural (e.g.,
aquifer, coal seam), and are often synonymous with storage or buffers in the system.
Flows are accounted quantities of material, good, currency, and so on that move
from one space-time location to another—that is, from an origin to a destination,
from a producer to a consumer, and so on. Flows may be human (e.g., currency payment, oil by pipeline) or natural (e.g., water in a river). Natural flows are often
considered ecosystem services. Flows may be valuable, as in the instance of goods
and services or currencies, but they may also be undesirable, such as flows of wastes
and pollutants. Information also flows. Origins and Destinations identify the
space-time locations where a good or service was transported (or flowed) from, and
to, respectively. Route identifies the precise mode of transport, pathway, and waypoints followed by a flow that transports a good or service. Agents are the natural
or human entities who control stocks, and who produce, consume, originate, terminate, and take inputs and outputs concerning flows; natural processes may be characterized as agents with predictable behavior.
Ontologies name and describe the categories of objects in a dataset and the relationships between these types. Subtypes of ontologies include controlled vocabularies or codesheets which are lists of categories and objects that are allowable in a
dataset, and data models (or object–entity relationship diagrams) detail the formats
and relationships between different objects in a dataset (e.g. Ruddell and
Kumar 2006).
An ontology is a conceptualization of categories that captures their qualitative
types and describes the relationships between different types. Establishments and
processes (or aggregations thereof) need to be named using controlled vocabularies. “Codes” are a very simple type of controlled vocabulary. For example, the
North American Industry Classification System (NAICS, OMB 2017) is a coding
system that categorizes different types of business establishments according to the
general type of goods and services they produce. NAICS was created for the
U.S. Census Bureau in partnership with Canadian and Mexican authorities to
track business and tax statistics in North America—but not for FEW systems
B. L. Ruddell