Published catalogues

A library that computes with a density has to get it from somewhere. This one gets it from a page, and keeps the page: every row below names the book, the table, the PDF page and the printed folio it was read on, and says what its cell actually said. A density printed as an interval is an interval here, a loss factor printed as an upper bound is a bound, and a tortuosity a page prints as the word model is that word, because the quantity is frequency dependent there and no single number stands for it.

Three things follow from that discipline and are visible in the tables.

The books disagree, and the key says which one is speaking. Four of them print a steel at 7 800 kg/m³ and no two agree on its modulus. That is not a defect to be averaged away: it is the spread of the literature, and a catalogue that picked one would be hiding it. Rows are keyed by the table they came off, and the library’s lookups return every book’s reading of a name rather than choosing between them.

A number this library worked out is marked as such. A page that prints a modulus and a density has printed a bar speed without writing it down, so the row carries it; but it is shown in italics, and what it was computed from is one hover away. No derived value is ever stored as if it had been read. Two other kinds of cell hold the page’s own number and say how it got there: a value the page gives in a unit this library does not hold, degrees Fahrenheit, psi or sabins, is converted, and the mark names the page’s figure and its unit; and a cell the page leaves blank because it prints the value once for a block of rows is carried, and the mark names the row that prints it. A value the source itself calls an estimate is marked as one.

A material marked with an asterisk carries a note its page made about it, and the note reads on the name. So does the reason behind any cell that is not a plain number.

Nothing here is a specification. Block densities vary by manufacturer, foams vary by batch, and the books say so by printing ranges where a range is what is known. Use a row to reproduce a worked example, to sanity-check a measurement or to get an order of magnitude; measure the specimen for anything that has to be right.

Every catalogue is a mapping from '<table>/<row>' to a row, and a row hands back what its page printed. A quantity the page gave is an attribute; a quantity it did not answers None, and the row says why.

from phonometry import materials

foam = materials.PUBLISHED_POROUS["allard-2009-table-13-1/foam"]
print(foam.source)
print(foam.printed("flow_resistivity_pa_s_m2"), "Pa s/m2")

screen = materials.PUBLISHED_POROUS["allard-2009-table-11-5/screen_2"]
print(screen.tortuosity)
print(screen.why_missing("tortuosity"))

printed is the strict reading: it returns the number the page printed or refuses, naming the page and what the cell held instead. Use it wherever a wrong number would be worse than an exception.

Asking for a name gives every book at once, which is the comparison no single book can make:

for row in materials.porous_materials_named("Mineral wool"):
    interval = row.ranges.get("porosity")
    print(row.table, row.porosity if interval is None else interval)

The ground catalogue works the same way, and feeds the models that ask for a flow resistivity:

from phonometry import environment

pasture = environment.PUBLISHED_GROUND["bies-2017-table-5-2/normal_uncompacted_ground"]
print(pasture.harmonoise_class, pasture.printed("flow_resistivity_pa_s_m2"))

over_pasture = environment.ground_effect(
    [125.0, 250.0, 500.0, 1000.0],
    1.0,
    1.5,
    50.0,
    flow_resistivity=pasture.printed("flow_resistivity_pa_s_m2"),
)
print(over_pasture.excess_attenuation.round(2), "dB")

A fluid state is a Fluid like any other, so it drops into the same calls; what tells it apart is that its model names a table rather than a closed form.

from phonometry import fluids

sea = fluids.PUBLISHED_FLUIDS["bies-2017-table-c1-fluids/sea_water"]
print(sea.model)
print(sea.validity)

Elastic constants, wave speeds and loss factors, read from nine tables in eight books. Seven of those books print a steel and they are not the same steel, which is why a key names the table it came from. Three polymers are printed by one book as the expanded form and by another as the solid one under the same bare name, with densities a factor of twelve to twenty-five apart; both are kept, and each row’s own modulus and speed say which it describes.