1. A device comprising:
an ultrasound transducer configured to (i) fire pushing beams into a medium wherein each pushing beam comprises a pushing beam focus and is configured to produce a respective shear wave along a propagation path through the medium, the ultrasound transducer further configured to (ii) issue tracking beams, receive respective echoes, and measure in response to issued tracking beams and respective received echoes, shear-wave induced displacement in the medium at different spatial locations along the propagation path of the respective shear wave; and
an in-place displacement based weighter operatively connected with all the tracking beams, wherein the in-place displacement based weighter is configured (i) to use shear-waved-induced displacement measured at the different spatial locations along the propagation path for determining a center of mass (COM) time value for each of the different spatial locations, wherein time values are weighted, according to dispalcement of a time value of a corresponding displacement curve, that correspond to times associated with sampling that detects the displacement, and (ii) to compute, in response to a first sum divided by a second sum of displacements used in the weighting, a weighted average representative of arrival time of the corresponding shear wave at a respective location of the different spatial locations, each respective location of the different spatial locations having its respective weighted average.
2. The device of claim 1, wherein the ultrasound transducer is further configured to estimate shear-wave propagation speed based on a time a shear wave is present at a different location along said path.
3. The device of claim 2, wherein said shear-wave propagation speed comprises a magnitude of group velocity of said shear wave.
4.-6. (canceled)
7. The device of claim 1, wherein said in-place displacement based weighter is further configured to selectively exclude from computation of a given weighted average, a particular displacement, based on whether the particular displacement meets an instantaneous-displacement threshold.
8. The device of claim 7, wherein the instantaneous-displacement threshold varies with spatial location for which a respective weighted average is being computed.
9. The device of claim 7, wherein the medium comprises a material and further wherein the instantaneous-displacement threshold is based on peak displacement of the material of the medium comprises.
10. The device of claim 9, further wherein the instantaneous-displacement threshold is directly proportional to said peak displacement.
11. The device of claim 10, further wherein the in-place displacement based weighter uses a plurality of different spatial locations to compute respective weighted averages representative of respective arrival times, and wherein the instantaneous-displacement threshold is further equal to said peak displacement multiplied by a factor invariant with location, said peak displacement varying with location.)
12. The device of claim 11, wherein said factor is dynamically varying based on a criterion.
13. The device of claim 12, wherein said criterion is based on a noise metric.
14. The device of claim 1, wherein the different spatial locations corn rise a plurality of different spatial locations, and wherein said in-place displacement based weighter is further configured to selectively exclude one or more of the plurality of locations from computation of a given weighted average.
15. The device of claim 14, wherein the selectively excluding of the one or more of the plurality of locations is dynamically based on a criterion.
16. The device of claim 15, wherein said criterion comprises whether a respective peak displacement exceeds a peak-displacement threshold.
17. (canceled)
18. The device of claim 1, wherein the devices is implemented as one or more integrated circuits.
19. The device of claim 1, wherein said weighted average is equal to an arrival time of a corresponding shear wave at a respective location of the plurality of different spatial locations.
20. The device of claim 1, wherein said shear-wave induced displacement comprises displacement of body tissue.
21. A method for detecting shear-wave arrival, said method comprising:
configuring, via an ultrasound transducer, to (i) fire pushing beams into a medium, wherein each pushing beam comprises a pushing beam focus and is configured to produce a respective shear wave along a propagation path through the medium, and to (ii) issue tracking beams, receive respective echoes, and measure in response to issued tracking beams and respective received echoes, shear-wave induced displacement in the medium at different spatial locations along the propagation path of the respective shear wave; and
configuring, via an in-place displacement based weighter (i) to use shear-wave-induced displacement measured at the different spatial locations along the propagation path for determining a center of as (COM) time value for each of the different spatial locations, wherein time values are weighted, according to displacement of a time value of a corresponding displacement curve, that correspond to times associated with sampling that detects the displacement, and (ii) to compute, in response to a first sum divided by a second sum of displacements used in the weighting, a weighted average representative of arrival time of the corresponding shear wave at a respective location of the different spatial locations each respective location of the different spatial locations having its respective weighted average.
22. A computer software product for detecting shear-wave arrival, said product comprising a computer readable medium embodying a computer program that includes instructions executable by a processor for performing a plurality of acts, said acts according to the method of claim 21.
23.-24. (canceled)
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
We claim:
1. A method of preparing styrene or substituted styrene comprising:
(a) converting a mixture comprising alkylbenzene hydroperoxide or substituted alkylbenzene hydroperoxide and an alkene to a mixture comprising phenyl alkanol or substituted phenyl alkanol and an alkylene oxide in the presence of a heterogeneous catalyst; and
(b) dehydrating the phenyl alkanol or substituted phenyl alkanol or substituted phenyl alkanol in the presence of a homogeneous dehydration catalyst to obtain styrene or substituted styrene.
2. The method of claim 1, which is preceded by a non-catalyzed step wherein alkylbenzene or substituted alkylbenzene is oxidized to a mixture comprising alkylbenzene hydroperoxide or substituted alkylbenzene hydroperoxide.
3. The method of claim 1 in which the alkylbenzene hydroperoxide comprises ethylene hydroperoxide and the phenyl alkanol comprises 1-phenylethanol.
4. The method of claim 3 in which the heterogeneous catalyst is selected from the group consisting of supported titanium compounds, zirconium compounds, molybdenum compounds, vanadium compounds, and the homogeneous catalyst is selected from the group consisting of inorganic acids and organic compounds.
5. The method of claim 1 in which the heterogeneous catalyst comprises titanium on silica, and the homogeneous catalyst comprises an aromatic andor sulfonic acid.
6. The method of claim 5, in which the homogeneous catalyst comprises p-toluene sulfonic acid.