Parametric instability of the helical dynamo

We study the dynamo threshold of a helical flow made of a mean (stationary) plus a fluctuating part. Two flow geometries are studied, either (i) solid body or (ii) smooth. Two well-known resonant dynamo conditions, elaborated for stationary helical flows in the limit of large magnetic Reynolds numbers, are tested against lower magnetic Reynolds numbers and for fluctuating flows (zero mean). For a flow made of a mean plus a fluctuating part the dynamo threshold depends on the frequency and the strength of the fluctuation. The resonant dynamo conditions applied on the fluctuating (resp. mean) part seems to be a good diagnostic to predict the existence of a dynamo threshold when the fluctuation level is high (resp. low).Comment: 37 pages, 8 figure

The Marines Hymn

Title in middle with war pictures surrounding edgeshttps://scholarsjunction.msstate.edu/cht-sheet-music/11507/thumbnail.jp

The Marines\u27 Hymn

[Verse 1]From the halls of Montezuma to the shores of Tripoli,We fight our country’s battles on the land as on the sea;First to fight for right and freedom, and to keep our honor clean;We are proud to claim the title of United States Marine. [Verse 2]Our flag’s unfurl’d to ev’ry breeze from dawn to setting sun;We have fought in ev’ry clime and place where we could take a gun;In the snow of far off northern lands, and in sunny tropic scenes,You will find us always on the job the United States Marines. [Verse 3]Here’s health to you and to our Corps which we are proud to serve;In many a strife we’ve fought for life, and never lost our nerve;If the Army and the Navy ever look on heaven’s scenes,They will find the streets guarded by United States Marines

Elements of Study on Dynamic Materials

As a preliminary study to more complex situations of interest in small-scale technology, this paper envisages the elementary propagation properties of elastic waves in one-spatial dimension when some of the properties (mass density, elasticity) may vary suddenly in space or in time, the second case being of course more original. Combination of the two may be of even greater interest. Toward this goal, a critical examination of what happens to solutions at the crossing of pure space-like and time-like material discontinuities is given together with simple solutions for smooth transitions and numerical simulations in the discontinuous case. The effects on amplitude, speed of propagation, frequency changes and the appearance of a Doppler-like effect are demonstrated although the whole physical system remains linear

2012 Hampton Roads Station Tide Prediction Calendars

These calendars are produced monthly using David Evans\u27 Tidecal

2003 Hampton Roads Station Tide Prediction Calendars

These calendars are produced monthly using David Evans\u27 Tidecal

2012 Gloucester Point Station Tide Prediction Calendars

These calendars are produced monthly using David Evans\u27 Tidecal

1996 Gloucester Point Station Tide Prediction Calendars

These calendars are produced monthly using David Evans\u27 Tidecal

2006 Gloucester Point Station Tide Prediction Calendars

These calendars are produced monthly using David Evans\u27 Tidecal

2002 Gloucester Point Station Tide Prediction Calendars

These calendars are produced monthly using David Evans\u27 Tidecal