The systems science portal
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| Complex systems approach |
Systems science is an transdisciplinary[1] field that studies the nature of systems—from simple to complex—in nature, society, cognition, engineering, technology and science itself. To systems scientists, the world can be understood as a system of systems. The field aims to develop interdisciplinary foundations that are applicable in a variety of areas, such as psychology, biology, medicine, communication, business management, engineering, and social sciences.
Systems science covers formal sciences such as complex systems, cybernetics, dynamical systems theory, information theory, linguistics or systems theory. It has applications in the field of the natural and social sciences and engineering, such as control theory, operations research, social systems theory, systems biology, system dynamics, human factors, systems ecology, systems engineering and systems psychology. Themes commonly stressed in system science are (a) holistic view, (b) interaction between a system and its embedding environment, and (c) complex (often subtle) trajectories of dynamic behavior that sometimes are stable (and thus reinforcing), while at various 'boundary conditions' can become wildly unstable (and thus destructive). Concerns about Earth-scale biosphere/geosphere dynamics is an example of the nature of problems to which systems science seeks to contribute meaningful insights.
Selected article -
In mathematics and science, a nonlinear system (or a non-linear system) is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many other scientists since most systems are inherently nonlinear in nature. Nonlinear dynamical systems, describing changes in variables over time, may appear chaotic, unpredictable, or counterintuitive, contrasting with much simpler linear systems.
Typically, the behavior of a nonlinear system is described in mathematics by a nonlinear system of equations, which is a set of simultaneous equations in which the unknowns (or the unknown functions in the case of differential equations) appear as variables of a polynomial of degree higher than one or in the argument of a function which is not a polynomial of degree one.
In other words, in a nonlinear system of equations, the equation(s) to be solved cannot be written as a linear combination of the unknown variables or functions that appear in them. Systems can be defined as nonlinear, regardless of whether known linear functions appear in the equations. In particular, a differential equation is linear if it is linear in terms of the unknown function and its derivatives, even if nonlinear in terms of the other variables appearing in it. (Full article...)Selected picture
This image illustrates part of the Mandelbrot set fractal. The size of the JPEG file encoding the bitmap of this image is more than 17 kilobytes (approximately 140000 bits). The same file can be generated by a computer program much shorter than 140000 bits, however. Thus, the Kolmogorov complexity of the JPEG file encoding the bitmap is much less than 140000.
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Selected biography -
Peter (Petre) Stoica (born 1949) is a researcher and educator in the field of signal processing and its applications to radar/sonar, communications and bio-medicine. He is a professor of Signals and Systems Modeling at Uppsala University in Sweden, and a Member of the Royal Swedish Academy of Engineering Sciences, the United States National Academy of Engineering (International Member), the Romanian Academy (Honorary Member), the European Academy of Sciences, and the Royal Society of Sciences. He is also a Fellow of IEEE, EURASIP, IETI, and the Royal Statistical Society.
He is known for his theoretical contributions to system identification and modeling, spectral analysis, array signal processing, space-time coding, and waveform design for active sensing. His practical contributions include the areas of wireless communications, microwave imaging for breast cancer detection, radar/sonar systems, acoustic source mapping, landmine and explosive detection, and magnetic resonance spectroscopy and imaging. His books on System Identification, Spectral Analysis, and Space-Time Coding for Wireless Communications have been used in both undergraduate and graduate courses and are highly cited (his works rank in the top 1% by citations for the field of engineering).
He has been included on the ISI list of the 250 most highly cited researchers in engineering in the world. (Full article...)Did you know
- ... that a successful experimental system must be stable and reproducible enough for scientists to make sense of the system's behavior, but unpredictable enough that it can produce useful results?
- ... * and next a science of action, called "Interactive management".
- ... * then a science of complexity,
- ... * continuing vertically with a science of design,
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