Using the method "DoubleExponentialOscillatory" works, at least to a point, but it is slow:
AbsoluteTiming@
NIntegrate[Abs[Sin[x^4]]/(Sqrt[x] + x^2), {x, 0, \[Infinity]},
Method -> {"DoubleExponentialOscillatory",
Method -> {"GlobalAdaptive", "MaxErrorIncreases" -> 10^6},
"SymbolicProcessing" -> 0}, PrecisionGoal -> 4,
MaxRecursion -> 40]
NIntegrate::slwcon: Numerical integration converging too slowly; suspect one of the following: singularity, value of the integration is 0, highly oscillatory integrand, or WorkingPrecision too small.
NIntegrate::eincr: The global error of the strategy GlobalAdaptive has increased more than 1000000 times. The global error is expected to decrease monotonically after a number of integrand evaluations. Suspect one of the following: the working precision is insufficient for the specified precision goal; the integrand is highly oscillatory or it is not a (piecewise) smooth function; or the true value of the integral is 0. Increasing the value of the GlobalAdaptive option MaxErrorIncreases might lead to a convergent numerical integration. NIntegrate obtained 0.6184623212443172` and 0.0007604000503125842` for the integral and error estimates.
{117.819, 0.618462}
In[1]:= AbsoluteTiming@
NIntegrate[Abs[Sin[x^4]]/(Sqrt[x] + x^2), {x, 0, \[Infinity]},
Method -> {"DoubleExponentialOscillatory",
Method -> {"GlobalAdaptive", "MaxErrorIncreases" -> 10^6},
"SymbolicProcessing" -> 0}, PrecisionGoal -> 4,
MaxRecursion -> 40, WorkingPrecision -> 30]
DynamicNIntegrate::slwcon: Numerical integration converging too slowly; suspect one of the following: singularity, value of the integration is 0, highly oscillatory integrand, or WorkingPrecision too small.Dynamic
DynamicNIntegrate::eincr: The global error of the strategy GlobalAdaptive has increased more than 1000000 times. The global error is expected to decrease monotonically after a number of integrand evaluations. Suspect one of the following: the working precision is insufficient for the specified precision goal; the integrand is highly oscillatory or it is not a (piecewise) smooth function; or the true value of the integral is 0. Increasing the value of the GlobalAdaptive option MaxErrorIncreases might lead to a convergent numerical integration. NIntegrate obtained 0.618315690550426459312705456807`30. and 0.00046796568836866222451442302407`30. for the integral and error estimates.Dynamic
{6215.76, 0.618315690550426459312705456807}
From the messages it seems that we can trust the first three significant digits, 0.618
, and those results agree with the earlier posted results.