The phrase "a valid approximation of" is correct and usable in written English.
You can use it when discussing a measurement, calculation, or representation that is close to the actual value but not exact.
Example: "The model provides a valid approximation of the system's behavior under certain conditions."
Alternatives: "an accurate estimate of" or "a reasonable representation of".
The linear model of TV-DCO in (4) was also widely adopted in literatures [28 36] as a valid approximation of TV-DCO at output of HPF.
Therefore, it seems that a static scanning protocol, together with fixed rate constants, is a valid approximation of full kinetic modeling in the case of healthy volunteers.
In matched data, conditional logistic (partial likelihood) analysis provides a valid approximation of the rate ratio and adjusts for the sampling variability found in estimating standard error and confidence intervals.
The "Talk Test" (cycling at an intensity at which a conversation was possible) was used to prescribe cycling intensity and has been shown to be a valid approximation of ventilatory threshold [27].
The simulation results show that the properties derived based on the control-oriented model hold also for the complex model presented in "A complex model of underwater snake robots", something which supports the assumption that the control-oriented model is a valid approximation of the complex model for analysis and control design.
These differences are sufficiently weak to imply that simplified BRBs constitute a valid approximation of CRBs or BCRBs when relocations are acquired frequently on a regular time basis (so as to minimize inter-bridge variations in time T).
Recent investigations have shown that the Pareto class of models provide a valid approximation for the statistical structure of the backscattering from the sea, for high resolution X-band maritime surveillance radar.
We now also have a viable strategy to compare the heuristic and full CMEs under conditions of timescale separation: one obtains the noise statistics from the hLNA and the ssLNA and compares them for rate constants such that the deterministic QSSA is a valid approximation (for an illustration of the comparison method, see Figure 2).
Over the range in which eq 26 is a valid approximation, a plot of R S against ln(V/ N) yields a straight line of slope b and intercept R0.
The Hillson and Rideal expression is shown to be a valid approximation when illumination of the electrode only slightly perturbs the electrodic charge-transfer reactions.
