37
disaggregation. Such an approach also has limited ability to identify and quantify
ecological impacts and environmental trade-offs.
The pros and cons of different approaches to modeling systems are addressed
later in the book (especially Chap. 15).
2.2 Complex Systems
Complex systems have attributes that distinguish them from simpler systems;
including:
• Heterogeneity: The many parts of the system are diverse (heterogeneous) in their
characteristics and modes of operation. In the systems that we are considering,
there can be both many distinct biophysical and human elements operating in
diverse ways. Subsystems are of many types; operate at many scales; can process
mass, energy, or information; and can be quantified with many different units. For
example, the biophysical aspects of food production are quite different to the financial and policy aspects. A second example is that electrical power production typically occurs at a few large generation facilities of a few types, but food production
is widely distributed across the landscape and takes on near- infinite forms.
• Interconnections: Components (subsystems) of the system are interdependent.
That is, the behavior of subsystems is dependent on the behavior of other subsystems. Components can act on each other directly and indirectly through other
parts of the system. There can be interactions operating under the laws of nature
and interactions operating under the influence of cultural norms, governmental
laws, human motivations, and economic principles as applied by independent
decision-makers. Physical and human elements are interrelated because of the
way they impact each other and depend on each other (recognizing that natural
ecosystems could function without human intervention while human activities
shape how many ecosystems function). For example, policies and laws governing natural water bodies are connected to food consumption through a series of
interconnections; water law > water body > water use by farmers > food availability and price > food retail > food consumer.
Often interconnections can be described by a set of mathematical expressions.
This can allow systems to be described by a computational model where many
mathematically described interactions between subsystems are calculated simultaneously and influence the next set of projected interactions between subsystems. These types of models are referred to as Process Networks.
Process Networks are typically represented by graphs of nodes (representing
subsystems) connected by “edges” (lines representing interactions) and studied
within a field of mathematics called “Network Theory.” Social networks, communication systems, and FEW infrastructures are subtypes of process networks.
An electric grid is an excellent example of a process network because generation and demand must be kept in balance at all times to the grid to function. As a
2 Systems Science
disaggregation. Such an approach also has limited ability to identify and quantify
ecological impacts and environmental trade-offs.
The pros and cons of different approaches to modeling systems are addressed
later in the book (especially Chap. 15).
2.2 Complex Systems
Complex systems have attributes that distinguish them from simpler systems;
including:
• Heterogeneity: The many parts of the system are diverse (heterogeneous) in their
characteristics and modes of operation. In the systems that we are considering,
there can be both many distinct biophysical and human elements operating in
diverse ways. Subsystems are of many types; operate at many scales; can process
mass, energy, or information; and can be quantified with many different units. For
example, the biophysical aspects of food production are quite different to the financial and policy aspects. A second example is that electrical power production typically occurs at a few large generation facilities of a few types, but food production
is widely distributed across the landscape and takes on near- infinite forms.
• Interconnections: Components (subsystems) of the system are interdependent.
That is, the behavior of subsystems is dependent on the behavior of other subsystems. Components can act on each other directly and indirectly through other
parts of the system. There can be interactions operating under the laws of nature
and interactions operating under the influence of cultural norms, governmental
laws, human motivations, and economic principles as applied by independent
decision-makers. Physical and human elements are interrelated because of the
way they impact each other and depend on each other (recognizing that natural
ecosystems could function without human intervention while human activities
shape how many ecosystems function). For example, policies and laws governing natural water bodies are connected to food consumption through a series of
interconnections; water law > water body > water use by farmers > food availability and price > food retail > food consumer.
Often interconnections can be described by a set of mathematical expressions.
This can allow systems to be described by a computational model where many
mathematically described interactions between subsystems are calculated simultaneously and influence the next set of projected interactions between subsystems. These types of models are referred to as Process Networks.
Process Networks are typically represented by graphs of nodes (representing
subsystems) connected by “edges” (lines representing interactions) and studied
within a field of mathematics called “Network Theory.” Social networks, communication systems, and FEW infrastructures are subtypes of process networks.
An electric grid is an excellent example of a process network because generation and demand must be kept in balance at all times to the grid to function. As a
2 Systems Science