Resilience

Resilience generally means the ability to recover from (or to resist being affected by) some shock, insult, or disturbance. However, it is used quite differently in different fields.

Materials
In physics and engineering, resilience is the property of a material to absorb energy when it is deformed elastically and then, upon unloading to have this energy recovered. In other words, it is the maximum energy per volume that can be elastically stored. It is represented by the area under the curve in the elastic region in the Stress-Strain diagram.

Modulus of Resilience, $$U_r$$, can be calculated using the following formula: $$U_r=\frac{\sigma^2}{2E}=0.5\sigma\epsilon=0.5 \sigma(\frac{\sigma}{E})$$, where $$ \sigma $$ is yield stress, E is Young's modulus, and $$ \epsilon $$ is strain.

An example of a biomaterial which has a high resilience is articular cartilage, the substance lining the ends of bones in articulating joints such as the knee and hip.

Network
"Resilience is the ability of the network to provide and maintain an acceptable level of service in the face of various faults and challenges to normal operation.

Resilient networks aim to provide acceptable service to applications: Note that resilience is a superset of survivability."
 * ability for users and applications to access information when needed, e.g.:
 * Web browsing
 * distributed database access
 * sensor monitoring
 * situational awareness
 * maintenance of end-to-end communication association, e.g.:
 * computer-supported cooperative work
 * video conference
 * teleconference (including VoIP calls)
 * operation of distributed processing and networked storage, e.g.:
 * ability for distributed processes to communicate with one another
 * ability for processes to read and write networked storage

Ecology
In ecology, resilience has been defined in two competing fashions that emphasize two different aspects of stability. The consequences of those different aspects for ecological systems were first emphasized by the Canadian ecologist C. S. Holling in order to draw attention to tradeoffs between efficiency on the one hand and persistence on the other, or between constancy and change, or between predictability and unpredictability. It is defined by the Resilience Alliance as "the capacity of an ecosystem to tolerate disturbance without collapsing into a qualitatively different state that is controlled by a different set of processes. A resilient ecosystem can withstand shocks and rebuild itself when necessary. Resilience in social systems has the added capacity of humans to anticipate and plan for the future." Resilence is conferred in human and ecological systems by adaptive capacity.

Industrial and organisational safety
Within the broad domain of industrial safety, the term resilience has come into use to emphasise that safety must be proactive as well as reactive. Whereas conventional risk management approaches are based on hindsight and emphasise error tabulation and calculation of failure probabilities, Resilience Engineering looks for ways to enhance the ability of organisations to create processes that are robust yet flexible, to monitor and revise risk models, and to use resources proactively in the face of disruptions or ongoing production and economic pressures. In Resilience Engineering failures do not stand for a breakdown or malfunctioning of normal system functions, but rather represent the converse of the adaptations necessary to cope with the real world complexity. Individuals and organisations must always adjust their performance to the current conditions; and because resources and time are finite it is inevitable that such adjustments are approximate. Success has been ascribed to the ability of groups, individuals, and organisations to anticipate the changing shape of risk before damage occurs; failure is simply the temporary or permanent absence of that.

Resiliency applied to the critical infrastructure
Resiliency is the ability to avoid, minimize, withstand, and recover from the effects of adversity, whether natural or manmade, under all circumstances of use. Resiliency applied to the nation’s critical infrastructure is trustworthiness under stress and spans high availability, continuous operations, and disaster recovery. The operations within the industry sectors of the critical infrastructure are diverse and complex. These operations are evolving into large systems of systems. In normal times these operations may operate satisfactorily in a loosely coupled arrangement. However, for these operations to be resilient under stress, more than a loosely coupled arrangement is needed. A defined engineering challenge of adopting resilience throughout the nation's critical infrastructure is needed. The recovery time objectives among industry sectors must be coordinated, interoperability of information sharing and platform operations must be assured, distributed supervisory control protocols must be in place, and operation sensing and monitoring must be embedded. These capabilities cannot be expected to evolve in a loosely coupled environment. They must be holistically specified, architected, designed, implemented, and tested if they are to operate with resilience under stress. A management, process, and engineering maturity framework is necessary to advance the assurance of software security, business continuity, system survivability, and system of system resiliency capabilities.

Psychology
Resilience (or "psychological resilience") is a term used in psychology that refers to an ability to cope with adversity. Whether outcomes are successful or not is determined by the presence (and balance) of both risk factors and protective factors over time. Risk factors tend to exacerbate vulnerability and increase the likelihood of negative outcomes while protective factors have an insulating effect and are predictive of positive outcomes. Promoting competence is a key factor in building resilience.

In children, positive developmental outcomes in the face of adversity are a characteristic of resilience. Risk factors include family violence and parental mental illness.

Single mothers may increase protective factors of resilience in their children by fostering positive relationships, interests, and gratitude for life

Economic and business
Economic resilience is the ability of a local economy to retain function, employment and prosperity in the face of the perturbation caused by the shock of the loss of a particular type of local industry or employer. Communities with resilient economies find that the loss of an employer results in rapid reabsorbtion of workers made redundant by the closure of an enterprise or industry into new, and frequently more satisfying and stable employment than before.

In business terms, resilience is the ability of an organization, resource, or structure to sustain the impact of a business interruption and recover and resume its operations to continue to provide minimum services.

Economic and business resilience, according to the Resilience Alliance, is enhanced "when the management of a resource is shared by a diverse group of stakeholders (e.g., local resource users, research scientists, community members with traditional knowledge, government representatives, etc.), decision-making is better informed and more options exist for testing policies. Active adaptive management whereby management actions are designed as experiments encourages learning and novelty, thus increasing resilience in social-ecological systems."