Database-driven Jc function using lookup tables. More...

#include <cl_JcFunction_Database.hpp>

Inheritance diagram for belfem::material::JcFunctionDatabase:

Collaboration diagram for belfem::material::JcFunctionDatabase:

Public Member Functions
	JcFunctionDatabase (const string &aPath, const string &aLabel)
	Constructor - loads database from file.
void	load_self_field (const string &aPath, const string &aLabel)
	Read the measured B = 0 level from the table's /source.
void	reduce_self_field_rows (const Matrix< real > &aPoints, const index_t aColT, const index_t aColB, const index_t aColV, const real aScale, Vector< real > &aT, Vector< real > &aValue) const
	Bin the B = 0 rows by temperature and average over angle.
	~JcFunctionDatabase () override=default
	Destructor - deletes the database.
real	min_value () const override
void	finalize_self_field ()
real	self_field (const real T, real &aDT) const
void	edge (const real angle, const real T, const bool aWithT, const bool aWithAngle, Edge &aEdge) const
bool	continued (const real normB) const
	true if B lies on the continuation of this label
real	anchor (const real a, const real V, const real S, const real aA_q, const real aV_q, const real aS_q, real &aJ_q) const
real	jc_join (const real x, const real J, const real V, const real S, const real aJ_q, const real aV_q, const real aS_q, real &aValue_q, real &aDB) const
real	continuation (const real normB, const real angle, const real T, const uint aMode, real &aDerivative) const
bool	angle_is_snapped (const real angle) const
	Wrap the caller's angle into the table window.
real	wrap_angle (const real angle) const
real	eval (const real normB, const real angle, const real T) const override
	Evaluate Jc or n at given field, angle, and temperature.
real	deval_dB (const real normB, const real angle, const real T) const override
	d(value)/d\|B\|, the exact derivative of eval
real	deval_dbeta (const real normB, const real angle, const real T) const override
	d(value)/dθ, the exact derivative of eval
real	deval_dT (const real normB, const real angle, const real T) const override
	d(value)/dT, the exact derivative of eval
Public Member Functions inherited from belfem::material::JcFunction
	JcFunction ()=default
virtual	~JcFunction ()=default
bool	depends_on (const JcParameter aParameter) const
bool	is_constant () const
virtual real	eval (const real normB, const real angle) const
	Evaluate with field and angle dependence.

Static Public Member Functions
static Database *	open_checked (const string &aPath, const string &aLabel)
	Open the table and refuse one the reader cannot serve.
static real	interp_curve (const Vector< real > &aT, const Vector< real > &aValue, const real T, real &dJ0dT)

Additional Inherited Members
Protected Member Functions inherited from belfem::material::JcFunction
void	set_dependency (const JcParameter aParameter)
	Mark function as depending on a parameter.
Protected Attributes inherited from belfem::material::JcFunction
JcDependency	mDependency

Detailed Description

Database-driven Jc function using lookup tables.

Implements Jc(B, angle, T) or n(B, angle, T) through interpolation of tabulated data stored in HDF5 format.

The database uses a structured tensor grid with higher-order finite element interpolation (quad4/9/16 for 2D, hex8/27/64 for 3D).

Coordinate system:

Dimension 0: Temperature T [K] (linear scale)
Dimension 1: Magnetic field log10(B) [-] (log scale, B in T)
Dimension 2: Angle θ between n and B [rad]
Values: log10(Jc) or log10(n)

The database clamps out-of-range T and high-field inputs to the valid domain and handles periodic angle wrapping (angle ± π). Below Bmin, n and a jc table with a measured self-field curve continue the table C1 and non-increasing in |B| ( see the low-field notes below ); a jc table without that curve keeps the clamp.

Dependencies: normB, angleNxB, T

Database file format:

HDF5 file with structured tensor mesh
Dataset name matches material label
See Database class documentation for detailed format

Usage:

JcFunction* jc = factory.create_jc_function(
    "path/to/ybco.hdf5", "jc"   // group name; "jc" or "n" for the shipped tables
);
material->set_jc_function(jc);  // Material takes ownership

Constructor & Destructor Documentation

◆ JcFunctionDatabase()

belfem::material::JcFunctionDatabase::JcFunctionDatabase	(	const string &	aPath,
		const string &	aLabel )

inline

Constructor - loads database from file.

Parameters

aPath	Path to HDF5 database file
aLabel	Group name inside the HDF5 file — "jc" or "n" for the shipped tables. Only "jc" reads the measured self-field curve ( icw column, Icw/t_eff calibration ); anything else is an n table, continued below Bmin from the table alone.

Loads a database-driven Jc or n function from file. The constructor reads the database dimensions and extracts the valid ranges for each coordinate.

The database stores:

T in linear scale [K]
log10(B) where B is in [T]
angle in [rad]
log10(Jc) or log10(n) as values

Example database creation (Python with h5py):

# Create 3D grid: T × log10(B) × angle
T = np.linspace(4, 90, 50)      # [K]
logB = np.linspace(-2, 1, 40)   # log10(B), B in 0.01-10 T
angle = np.linspace(0, np.pi, 30)  # [rad]
# Store log10(Jc) values on this grid

◆ ~JcFunctionDatabase()

belfem::material::JcFunctionDatabase::~JcFunctionDatabase ( )

overridedefault

Destructor - deletes the database.

Member Function Documentation

◆ anchor()

real belfem::material::JcFunctionDatabase::anchor	(	const real	a,
		const real	V,
		const real	S,
		const real	aA_q,
		const real	aV_q,
		const real	aS_q,
		real &	aJ_q ) const

inline

the jc anchor J = smax( a, b ) and its derivative along one of T or angle; aA_q, aV_q, aS_q are that derivative of a, V, S

◆ angle_is_snapped()

bool belfem::material::JcFunctionDatabase::angle_is_snapped ( const real angle ) const

inline

Wrap the caller's angle into the table window.

theta in [ 0, pi ] passes through untouched; values within the same 1e-6 tolerance the ctor coverage guard uses are snapped onto the boundary — a table whose endpoints sit an ulp inside 0 or pi must not swap poles at exactly theta = 0 or pi. Anything further out uses the +-pi periodicity.

true where wrap_angle holds the angle on a window end, so the value does not change with it

◆ continuation()

real belfem::material::JcFunctionDatabase::continuation	(	const real	normB,
		const real	angle,
		const real	T,
		const uint	aMode,
		real &	aDerivative ) const

inline

value below Bmin and one derivative of it: aMode 0 d/dB, 1 d/dT, 2 d/dangle

◆ continued()

bool belfem::material::JcFunctionDatabase::continued ( const real normB ) const

inline

true if B lies on the continuation of this label

◆ deval_dB()

real belfem::material::JcFunctionDatabase::deval_dB	(	const real	normB,
		const real	angle,
		const real	T ) const

inlineoverridevirtual

d(value)/d|B|, the exact derivative of eval

The table stores f = log10( value ) over u = log10 B, so d(value)/dB = value · (∂f/∂u) / B — ln10 cancels. Zero where eval clamps B ( above Bmax, and below Bmin for a jc table without a measured self-field curve ); at Bmin itself the continuation and the table share the slope.

Reimplemented from belfem::material::JcFunction.

◆ deval_dbeta()

real belfem::material::JcFunctionDatabase::deval_dbeta	(	const real	normB,
		const real	angle,
		const real	T ) const

inlineoverridevirtual

d(value)/dθ, the exact derivative of eval

θ is stored linearly, so d(value)/dθ = value · ln10 · ∂f/∂θ; the ±π wrap is a shift ( dθ_wrapped/dθ = 1 ), and the snap onto a window end holds the value ( zero ).

Reimplemented from belfem::material::JcFunction.

◆ deval_dT()

real belfem::material::JcFunctionDatabase::deval_dT	(	const real	normB,
		const real	angle,
		const real	T ) const

inlineoverridevirtual

d(value)/dT, the exact derivative of eval

T is stored linearly: d(value)/dT = value · ln10 · ∂f/∂T. Outside the temperature window the value is held, so the tangent is zero.

Reimplemented from belfem::material::JcFunction.

◆ edge()

void belfem::material::JcFunctionDatabase::edge	(	const real	angle,
		const real	T,
		const bool	aWithT,
		const bool	aWithAngle,
		Edge &	aEdge ) const

inline

the table on the face log10 B = log10 Bmin; d/dT and d/dangle terms only when asked for

◆ eval()

real belfem::material::JcFunctionDatabase::eval	(	const real	normB,
		const real	angle,
		const real	T ) const

inlineoverridevirtual

Evaluate Jc or n at given field, angle, and temperature.

Parameters

normB	Magnetic field magnitude [T]
angle	Angle between surface normal and field [rad]
T	Temperature [K]

Returns: Jc [A/m²] or n [-]

T is clamped to [ Tmin, Tmax ] and B above Bmax to Bmax; the angle is wrapped into the table window. Below Bmin the value is the continuation described above ( a jc table without a measured self-field curve keeps the clamp ).

Reimplemented from belfem::material::JcFunction.

◆ finalize_self_field()

void belfem::material::JcFunctionDatabase::finalize_self_field ( )

inline

isotonic projection ( the running maximum from high to low T ) of the measured curve, and its knot slopes ( Fritsch & Butland 1984, Eq. 5; one-sided secants at the ends ), which keep every segment monotone ( Fritsch & Carlson 1980, §4 )

◆ interp_curve()

real belfem::material::JcFunctionDatabase::interp_curve	(	const Vector< real > &	aT,
		const Vector< real > &	aValue,
		const real	T,
		real &	dJ0dT )

inlinestatic

linear interpolation on the raw curve, clamped at both ends; used only to calibrate the curve at 77.5 K

◆ jc_join()

real belfem::material::JcFunctionDatabase::jc_join	(	const real	x,
		const real	J,
		const real	V,
		const real	S,
		const real	aJ_q,
		const real	aV_q,
		const real	aS_q,
		real &	aValue_q,
		real &	aDB ) const

inline

the jc Hermite on [ 0, Bmin ]: value, and the slope at B = 0 with its derivative along T or angle

◆ load_self_field()

void belfem::material::JcFunctionDatabase::load_self_field	(	const string &	aPath,
		const string &	aLabel )

inline

Read the measured B = 0 level from the table's /source.

The rebuilt tables embed their raw measurement rows as /source/points with /source/columns naming them, and those rows include the self-field scans the log10 B axis structurally cannot hold ( log10( 0 ) is undefined ). Rows at exactly B = 0 are binned by temperature and averaged over the stage angles – the average is the whole point, the measured angular scatter there being only a few tenths of a percent.

Silently inert on any file without /source: mHaveSelfField stays false and the jc table keeps the clamp below Bmin.

◆ min_value()

real belfem::material::JcFunctionDatabase::min_value ( ) const

inlineoverridevirtual

smallest value the table can produce; values are stored as log10, so exponentiate the raw minimum

Reimplemented from belfem::material::JcFunction.

◆ open_checked()

Database * belfem::material::JcFunctionDatabase::open_checked	(	const string &	aPath,
		const string &	aLabel )

inlinestatic

Open the table and refuse one the reader cannot serve.

Runs before any member reads the database, and owns it until every check has passed, so a refusal does not leak it. Every rank holds the same values ( Database broadcasts them ), so every rank refuses together.

◆ reduce_self_field_rows()

void belfem::material::JcFunctionDatabase::reduce_self_field_rows	(	const Matrix< real > &	aPoints,
		const index_t	aColT,
		const index_t	aColB,
		const index_t	aColV,
		const real	aScale,
		Vector< real > &	aT,
		Vector< real > &	aValue ) const

inline

Bin the B = 0 rows by temperature and average over angle.

The angular average IS the physics: at zero field there is no field direction, and the measured rows scatter only a few tenths of a percent across the stage angles. A temperature is a distinct bin when it differs by more than the tolerance, which is loose enough to merge one setpoint's jitter ( 77.48-77.51 K ) and tight enough to keep 2.5 K spacing apart.

◆ self_field()

real belfem::material::JcFunctionDatabase::self_field	(	const real	T,
		real &	aDT ) const

inline

the measured anchor and its dT: the C1 Hermite of the knots, continued linearly from the end knots outside them

◆ wrap_angle()

real belfem::material::JcFunctionDatabase::wrap_angle ( const real angle ) const

inline

The documentation for this class was generated from the following file:

src/physics/materials/cl_JcFunction_Database.hpp

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ JcFunctionDatabase()

◆ ~JcFunctionDatabase()

Member Function Documentation

◆ anchor()

◆ angle_is_snapped()

◆ continuation()

◆ continued()

◆ deval_dB()

◆ deval_dbeta()

◆ deval_dT()

◆ edge()

◆ eval()

◆ finalize_self_field()

◆ interp_curve()

◆ jc_join()

◆ load_self_field()

◆ min_value()

◆ open_checked()

◆ reduce_self_field_rows()

◆ self_field()

◆ wrap_angle()