Rake angle measurement of inclined slotting cutter
This paper analyses the blade shape, the parameters of rake angle of slotting cutter. The theoretical analysis process of a novel rake angle error measurement is introduced, which is built on the theory that the rake face of the inclined slotting cutter is a flat surface. For the systematic errors is caused by inaccurate measurement, the paper give in-depth analysis in various situation. By testing in the GD40-type CNC Gear Measurement Center, the accuracy testing results validate the correctness of the method.
Notice of Retraction3D probe radius compensation in measurement of characterized curves of complex helicoidal surface
Probe radius bias processing is a key technology in CNC measuring center. Based on the principal that the trace of the center of the probe is the offset surface of the measured helicoidal surface, a theoretical model is established for describing the trace surface. And three-dimensional probe radius compensation is proposed. Finally, the measuring example is given. The result shows that the three-dimensional probe compensation is accurate and convenient to measuring characterized curves of complex helicoidal surface.
The Vascular Theory of Migraine‐Resuscitated or More Moribund?
Your decision to publish an important paper on cerebral blood flow (CBF) in migraine1 as the first in Headache for 1989 is to be applauded. But does it clarify or cloud the issue? After 20 years of CBF studies in migraine the results show 1) a reduction of at least 25 30% in classical migraine1, 2) an average increase of 31% in common and classical migraine2, 3) or no change in common migraine3. Now we learn that the measurements need modifying by 40% to allow for scattering of radiation the Compton scatter effect which has led to "an unbalanced interpretation of the data"1 So the results are as contradictory as they can be, the measurements require adjustment, and the interpretation is therefore doubly doubtful. From the clinical point of view the neurological aura, the enlarging scotoma, the scintillations, the migration of the paraesthesiae up the arm or visual disturbances across the visual field, have not been seen in cerebrovascular disease.4 The headache is throbbing in only 47% of 750 patients questioned during a migraine5; but even when the pain is pulsatlie, it throbs for only a portion of the time at the maximum of the headache (Blau unpublished observations). The evidence for a neurological aetiology has been examined6: the most potent argument against a vascular cause is that the common triggers stress, light and hunger go direct to the nervous system, not via blood vessels. No one denies that vascular changes occur in migraine but are they primary or secondary to a neurological disturbance? Sokoloff7 concluded that the stimulated rat and monkey cortex showed increased glucose uptake, and that the increased local blood flow occurred "in response (my italics) to changes in local functional activity". The evidence, therefore, points to an underlying neurological basis with secondary vascular responses. The vascular theory may need resuscitation but who is going to give it the kiss of life?