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  2. Root locus analysis - Wikipedia

    en.wikipedia.org/wiki/Root_locus_analysis

    According to vector mathematics, the angle of the result of the rational polynomial is the sum of all the angles in the numerator minus the sum of all the angles in the denominator. So to test whether a point in the s-plane is on the root locus, only the angles to all the open loop poles and zeros need be considered. This is known as the angle ...

  3. Nyquist stability criterion - Wikipedia

    en.wikipedia.org/wiki/Nyquist_stability_criterion

    The Nyquist plot for () = + + with s = jω.. In control theory and stability theory, the Nyquist stability criterion or Strecker–Nyquist stability criterion, independently discovered by the German electrical engineer Felix Strecker [] at Siemens in 1930 [1] [2] [3] and the Swedish-American electrical engineer Harry Nyquist at Bell Telephone Laboratories in 1932, [4] is a graphical technique ...

  4. Foam Index - Wikipedia

    en.wikipedia.org/wiki/Foam_Index

    This point is difficult to judge at first. Run the same material several times in a row to help calibrate your “eye.” • Although the Foam Index test is not designed to determine the actual AEA dosage amounts needed for concrete, it is possible to standardize procedures [6] to determine AEA dosage amounts. It is also a good test to ...

  5. Flow table test - Wikipedia

    en.wikipedia.org/wiki/Flow_table_test

    The flow table test or slump-flow test is a method to determine consistency of fresh concrete. Flow table test is also used to identify transportable moisture limit of solid bulk cargoes. [ 1 ] It is used primarily for assessing concrete that is too fluid (workable) to be measured using the slump test , because the concrete will not retain its ...

  6. Sieve analysis - Wikipedia

    en.wikipedia.org/wiki/Sieve_analysis

    A sieve analysis (or gradation test) is a practice or procedure used in geology, civil engineering, [1] and chemical engineering [2] to assess the particle size distribution (also called gradation) of a granular material by allowing the material to pass through a series of sieves of progressively smaller mesh size and weighing the amount of material that is stopped by each sieve as a fraction ...

  7. Routh–Hurwitz stability criterion - Wikipedia

    en.wikipedia.org/wiki/Routh–Hurwitz_stability...

    In the control system theory, the Routh–Hurwitz stability criterion is a mathematical test that is a necessary and sufficient condition for the stability of a linear time-invariant (LTI) dynamical system or control system. A stable system is one whose output signal is bounded; the position, velocity or energy do not increase to infinity as ...

  8. Four-point flexural test - Wikipedia

    en.wikipedia.org/wiki/Four-point_flexural_test

    The four-point flexural test provides values for the modulus of elasticity in bending, flexural stress, flexural strain and the flexural stress-strain response of the material. This test is very similar to the three-point bending flexural test. The major difference being that with the addition of a fourth bearing the portion of the beam between ...

  9. Open-loop controller - Wikipedia

    en.wikipedia.org/wiki/Open-loop_controller

    In control theory, an open-loop controller, also called a non-feedback controller, is a control loop part of a control system in which the control action ("input" to the system [1]) is independent of the "process output", which is the process variable that is being controlled. [2]