"unknown grounds" is a correct and usable phrase in written English.
It can be used to describe a situation or reason that is not understood or known. Example: The company's decision to close down its operations on unknown grounds has caused confusion among its employees.
Eusebius, on unknown grounds, dates the event to 107 or 108.
Simplicius says, on unknown grounds, that this Xuthus was a Pythagorean, and scholars have speculated that he was responding to Parmenides (DK I. 376. 20 26; Kirk and Raven 1957, 301 302; Barnes 1982, 616).
Things may recover quickly but we are on unknown ground there.
Native bees, especially the almost unknown ground-nesting types, are the unsung heroines of the bee world".
Last week, a security official in Islamabad gave the Guardian details of three hitherto unknown ground missions conducted by joint CIA-Pakistani teams to capture Bin Laden.
This kind of deterrent could be based on miniaturised arms or on remote-control robots operating on the battlefield; perhaps even on a type of intelligence hitherto unknown, grounded in revolutionary nanotechnology.
Then, unknown ground motion is subsequently estimated by the Newmark-β method.
A non-linear least square approach using the Levenberg Marquardt method is proposed to overcome the problem of unknown ground impedance.
The structural parameters and the unknown ground excitations were identified during the tests by using the proposed identification method with the measured control forces.
Recently, on the basis of extended Kalman filter (EKF), a time-domain integrated approach was proposed for the identification of structural parameters of the controlled buildings with unknown ground excitations.
The considered model is a seven DOF full-car vertical model subject to unknown ground disturbances whose effects on the estimated state variables are minimized using the H∞ framework.
