Claims
- 1. A method for measuring sizes of particles in a falling state comprising the steps of:
- transmitting electromagnetic waves having different frequencies onto particles in the falling state at a predetermined angle with respect to the particle falling direction;
- receiving reflected electromagnetic waves having the different frequencies reflected from said particles in the falling state;
- detecting the intensities of said received reflected electromagnetic waves having different frequencies; and
- deriving data as to the distribution of sizes of said particles and the average size of said particles from the detected intensities of said received reflected electromagnetic waves, said data being derived based on the fact that said detected intensities are related to the sizes of said particles, the frequencies of said electromagnetic waves and the vertical gaps between said particles which are dependent on the particle sizes, an initial velocity of a respective one of the particles and a velocity of the respective particle in the falling state.
- 2. A method according to claim 1, wherein said predetermined angle with respect to the particle falling direction is a right angle.
- 3. A method according to claim 2, wherein the transmission and reception of the electromagnetic waves having different frequencies are carried out via transmission through a waveguide.
- 4. A method according to claim 3, wherein the transmission and reception of the electromagnetic waves having different frequencies are carried out by transmission through a dielectric lens for converging the electromagnetic waves.
- 5. A method according to claim 1, wherein said transmission and reception of electromagnetic waves having different frequencies are carried out by transmitting and receiving a first and a second electromagnetic wave of different frequencies through an upper waveguide and a lower waveguide respectively, and said derivation of data of the distribution of sizes of said particles and the average size of said particles is carried out using the result of a calculation of the correlation between the signals of said first and second electromagnetic waves.
- 6. A method according to claim 1, wherein said predetermined angle is greater than or less than 90.degree. with respect to the particle falling direction, and said derivation of data of the distribution of sizes of said particles and the average size of said particles is carried out using the result of a calculation of a Doppler effect.
- 7. A method according to claim 1, wherein the implementations of said steps of transmitting an electromagnetic wave and receiving reflected electromagnetic waves having different frequencies are carried out by a plurality of transmitting circuits and a plurality of receiving circuits respectively corresponding to said different frequencies.
- 8. A method according to claim 1, wherein the implementations of said steps of transmitting an electromagnetic wave and receiving reflected electromagnetic waves having different frequencies are carried out by a frequency sweep process using a single oscillator device.
- 9. A method according to claim 1, wherein said step of deriving the average size of said particles and the distribution of the sizes of said particles is carried out on the basis of the following equations with a change of a normalized scattering cross-section being effected by changing frequency of the electromagnetic wave: ##EQU24## where: R.sub.ant is a reflectance of an electromagnetic wave at an antenna,
- A is an area of an antenna,
- D is a distance between an end of an antenna and an end of a probe,
- .sigma..sub.n is a normalized scattering cross-section,
- d.sub.a is an average size of particles,
- R is a transmission rate of an electromagnetic wave,
- l is a distance between adjacent particles at a level of a probe,
- d is a diameter of a particle,
- V.sub.0 is an initial velocity of a particle falling from a charging hopper, and
- V is a velocity of a particle at a level of a probe.
- 10. A method according to claim 1, wherein said step of deriving data is carried out by calculating reflectances, each of the reflectances corresponding to a respective one of the frequencies of the transmitted electromagnetic waves, the reflectance at each of the frequencies corresponding to a particle size.
- 11. A method according to claim 10, wherein the distribution of the particles is derived based on the reflectances.
- 12. A method according to claim 1, wherein the frequencies of the transmitted waves are in the microwave wave-length range, and the electromagnetic waves are transmitted by means of an antenna.
- 13. A method according to claim 1, wherein at least one of the frequencies is smaller than d.sub.a /0.4, where d.sub.a is the average size of the particles.
- 14. A method according to claim 1, wherein at least one of the frequencies is greater than d.sub.a /0.4, where d.sub.a is the average size of the particles.
- 15. An apparatus for measuring sizes of particles in the falling state comprising:
- electromagnetic wave transmission and reception means for transmitting electromagnetic waves having different frequencies onto particles in the falling state at a predetermined angle with respect to the particle falling direction and receiving the electromagnetic waves having different frequencies reflected from said particles in the falling state;
- detection means for detecting the intensities of said received electromagnetic waves having different frequencies and outputting signals; and
- signal processing means for processing said signals to derive data on the distribution of sizes of said particles and an average size of said particles on the basis of the following equations, with a change of a normalized scattering cross-section being effected by changing a frequency of the electromagnetic wave: ##EQU25## where: R is a reflectance of an electromagnetic wave at an antenna,
- A is an area of an antenna,
- D is a distance between an end of an antenna and an end of a probe,
- .sigma..sub.n is a normalized scattering cross-section,
- d is an average size of particles,
- R is a transmission rate of an electromagnetic wave,
- l is a distance between adjacent particles at a level of a probe,
- d is a diameter of a particle,
- V is an essential velocity of a particle falling from a charging hopper, and
- V is a velocity of a particle at a level of a probe,
- said signal processing means deriving the data based on the fact that said detected intensities are related to the sizes of said particles, the frequencies of said electromagnetic waves and the vertical gaps between said particles which are dependent on the particle sizes, an initial velocity of a respective one of the particles and a velocity of the respective particle in the falling state.
Priority Claims (2)
Number |
Date |
Country |
Kind |
60-077343 |
Apr 1985 |
JPX |
|
60-284445 |
Dec 1985 |
JPX |
|
Parent Case Info
This is a continuation-in-part of application Ser. No. 851,148 filed on Apr. 11, 1986, claiming priority based on Japanese patent application Nos. 60-77343 and 60-284445 filed on Apr. 11, 1985 and Dec. 19, 1985 respectively.
US Referenced Citations (14)
Foreign Referenced Citations (2)
Number |
Date |
Country |
60-55252 |
Mar 1985 |
JPX |
0807141 |
Feb 1981 |
SUX |
Non-Patent Literature Citations (3)
Entry |
Translation of Hirata '252 cited above. |
Definition "Electromagnetic Spectrum"; American Heritage Dictionary. |
Inaba et al.; "IR Lasar Radar Technique Using Heterodyne Detection for Range-Resolved Sensing of Air Pollutants"; Optics Communication; vol. 14, No. 1; May 1975. |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
851148 |
Apr 1986 |
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