definition of a system
All systems have (a) inputs, outputs and feedback mechanisms, (b) maintain an internal steady-state (called homeostasis) despite a changing external environment, (c) display properties that are different than the whole (called emergent properties) but are not possessed by any of the individual elements, and (d) have boundaries that are usually defined by the system observer.
Although different types of systems (from a cell to the human body, soap bubbles to galaxies, ant colonies to nations) look very different on the surface, they have remarkable similarities. At the most basic level, systems are divided into two categories: (1) Closed systems: theoretical systems that do not interact with the environment and are not influenced by its surroundings. Only the components within the system are significant. Example: a sealed jar--nothing enters or exits the jar, but whatever is inside can interact. (2) Open systems: real-world systems whose boundaries allow exchanges of energy, material and information with the larger external environment or system in which they exist.
(2) The management of systems development, which includes systems analysis & design, application development and implementation. See system development life cycle.
PCMag.com is a leading authority on technology, delivering Labs-based, independent reviews of the latest products and services. Our expert industry analysis and practical solutions help you make better buying decisions and get more from technology.
In recent years, psychologists have proposed that there are two systems of the mind: System 1 and System 2. The brain is not literally divided like this, but it is a useful analogy.
System 1 is our faster, automatic, intuitive and emotional mode of thinking, while System 2 is slower, more effortful, and deliberate. Most of our daily decisions are made automatically and unconsciously using our System 1. We use our more logical System 2 for decisions we have to consciously make, but this is a limited resource that is easily depleted as we get tired.
Future directions in resilience research are discussed.
A comprehensive review of definitions and measures of system resilience.
The System Definition utility is a graphic view of existing table elements and properties and a quick way to define new tables. It enables you to accomplish the tasks traditionally handled by the database dictionary utility. The System Definition utility has two tabs: tables and fields. Service Manager displays SQL mapping information only when mapping information is available. Each time you double-click any table in the System Definition area of the System Navigator, the System Definition utility displays the Table tab first. You can access the other tabs by clicking the labeled tabs or links in the Editor.
If you change a table element, an asterisk marks the table and the element in the System Navigator until you click Save.