1. A method for continuous determination of the properties of a wood fibre flow for fibreboard fabrication, characterized in that a fibre flow sample is illuminated with light, and, from measured ensuring reflectance spectrum, one or more of the properties fibre length distribution, resin content, fibre moisture and optical properties for the fibre flow sample isare determined from predetermined relations between measured spectral values and the absolute magnitudes of said properties.
2. The method according to claim 1, characterized in that light spectra in the 400-2500 nm wavelength range are used.
3. The method according to claim 1 or 2, characterized in that a reference fibre length distribution is determined for calibration samples of the fibre flow, and a fibre length distribution, determined from the reflectance spectrum measured for the same calibration samples, is modelled in a calibration procedure against said reference fibre length distribution with the aid of multivariate statistical regression methods for determining said predetermined relations between measured spectral values and fibre length distribution.
4. The method according to any of the previous claims, characterized in that a reference fibre moisture is determined for calibration samples of the fibre flow, and reference fibre moisture, determined from the reflectance spectrum measured for the same calibration samples, is correlated in a calibration procedure against said reference fibre moisture with the aid of multivariate statistical regression methods for determining said predetermined relations between measured spectral values and fibre moisture.
5. The method according to any of the previous claims, characterized, in that a reference resin content is determined for calibration samples of the fibre flow, and spectral values, determined from the reflectance spectrum measured for the same calibration samples, are correlated in a calibration procedure against said reference resin content with the aid of multivariate statistical regression methods for determining said predetermined relations between measured spectral values and resin content.
6. The method according to any of the previous claims, characterized in that reference values for optical characteristics are determined for calibration samples of the fibre flow, and spectral values, determined from the reflectance spectrum measured for the same calibration sample, are correlated in a calibration procedure against said optical reference values with the aid of multivariate statistical regression methods for determining said relations between spectral values and optical properties.
7. The method according to any of claims 3-6, characterized in that calibration samples are prepared according to a test plan with varying levels for test variables selected to produce a good spread of fibre length distribution, fibre moisture, resin content and optical properties in the different calibration samples.
8. The method according to any of the previous claims, characterized in that one or more of the parameters fibre length distribution, resin content, fibre moisture and optical properties, determined from the reflectance spectrum, isare used in a feedback procedure for on-line control of the fibre preparation process in order to impart the desired properties to the wood fibre used.
9. The method according to claim 8, whereby the fibre is produced in a refining process, characterized in that one or more of the parameters fibre length distribution, resin content, fibre moisture and optical properties isare fed back to control of the defibering process.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A core comprising:
a base having an outer edge and a top region,
a first post disposed on the top region of the base at the outer edge,
a second post disposed on the top region of the base at the outer edge,
a third post disposed on the top region of the base at the outer edge,
a fourth post disposed on the top region of the base at the outer edge,
a shared common center portion disposed on the base,
a top disposed on the posts and opposite the base,
wherein the first post and the center portion are separated on the base to thereby define a first window, the second post and the center portion are separated on the base to thereby define a second window, the third post and the center portion are separated on the base to thereby define a third window, the fourth post and the center portion are separated on the base to thereby define a fourth window, and the top and center portion are spaced apart to thereby define an air gap,
eight primary windings and eight secondary windings in an arrangement on the core, the arrangement defining four cells each comprising two primary windings and two secondary windings, and
a control circuit having an output connected to the primary windings, the control circuit having at least two phases, said phases being power transfer phases, in which current runs from the output in a first direction during a first power transfer phase and in the opposite direction during a second power transfer phase, two of the cells being powered by the control circuit during the first power transfer phase and the other two cells being powered by the control circuit during the second power transfer phase, said arrangement forming a power converter suitable for providing a load current to a load.
2. The core of claim 1, wherein the first post, the second post, the third post, the fourth post are disposed on the base in a rectangular matrix.
3. The core of claim 2, wherein the rectangular matrix is square.
4. The core of claim 1, wherein the base has a square shape and the posts are each disposed at a different corner of the square shape.
5. The core of claim 4, wherein the center portion has plural legs in a plus shape.
6. The core of claim 1, wherein the posts are disposed on the base in a symmetrical pattern.
7. The core of claim 1, wherein the windings have respective directions, and the directions provide for additive flux in the center portion when the windings are energized as inductors.
8. The core of claim 1, wherein the base, the posts and the center portion are an integrated unit.
9. The core of claim 1, wherein the base, the posts and the center portion are formed of a single material.
10. The core of claim 1, wherein the posts have a common height measured from the base, and the center portion has a height which is less than the common height of the posts.
11. The core of claim 1, wherein the posts have a common shape.
12. The core of claim 1, wherein the posts have a rectangular shape.
13. The core of claim 1, wherein each of said first, second, third and fourth posts has two of said primary windings and two of said secondary windings.
14. The core of claim 13, wherein the directions of said windings are arranged such that magnetic fluxes generated in said posts are additive in said common center portion.
15. The core of claim 13, wherein said control circuit is further arranged to have a freewheeling phase during which the currents in all of said primary windings are zero and the currents in the secondary windings of all four cells deliver said load current.
16. The core of claim 13, wherein said control circuit energizes said windings such that said power converter is a current doubler rectifier (CDR).
17. The core of claim 16, wherein said control circuit is further arranged to have a freewheeling phase during which the currents in all of said primary windings are zero and the currents in the secondary windings of all four cells deliver said load current.
18. The core of claim 17, wherein the control circuit energizes said windings such that said CDR has said first and second power transfer phases and a freewheeling phase, the load current provided by said CDR divided into four parallel paths during said power transfer phases when power is transferred across said core from said primary windings to said secondary windings, and into eight parallel paths during said freewheeling phase.
19. A current doubler rectifier (CDR), comprising:
a core structure, comprising:
a base having an outer edge and a top region,
a first post disposed on the top region of the base at the outer edge,
a second post disposed on the top region of the base at the outer edge,
a third post disposed on the top region of the base at the outer edge,
a fourth post disposed on the top region of the base at the outer edge,
a shared common center portion disposed on the base,
a top disposed on the posts and opposite the base,
wherein the first post and the center portion are separated on the base to thereby define a first window, the second post and the center portion are separated on the base to thereby define a second window, the third post and the center portion are separated on the base to thereby define a third window, the fourth post and the center portion are separated on the base to thereby define a fourth window, and the top and center portion are spaced apart to thereby define an air gap,
eight primary windings and eight secondary windings in an arrangement on the core, wherein each of said first, second, third and fourth posts has two of said primary windings and two of said secondary windings, the arrangement defining four cells each comprising two primary windings and two secondary windings, and
a control circuit having an output connected to the primary windings, the control circuit having first and second power transfer phases and a freewheeling phase, in which current runs from the output in a first direction during said first power transfer phase and in the opposite direction during said second power transfer phase and the currents in all of said primary windings are zero during said freewheeling phase, two of the cells being powered by the control circuit during the first power transfer phase and the other two cells being powered by the control circuit during the second power transfer phase,
said arrangement forming a CDR suitable for providing a load current to a load such that the load current provided by said CDR is divided into four parallel paths during said power transfer phases when power is transferred across said core from said primary to said secondary windings, and into eight parallel paths during said freewheeling phase when the currents in the secondary windings of all four cells deliver said load current.