초록 ▼

A gas sensor for detection of oxidizing and reducing gases, including O2,CO2,CO, and H2,monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temper

A gas sensor for detection of oxidizing and reducing gases, including O2,CO2,CO, and H2,monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temperature rise of the metallic line is inversely proportional to the thermal conductivity of the oxide coating. The oxide coating contains multi-valent cation species that change their valence, and hence the oxygen stoichiometry of the coating, in response to changes in the partial pressure of the detected gas. Since the thermal conductivity of the coating is dependent on its oxygen stoichiometry, the temperature rise of the metallic line depends on the partial pressure of the detected gas. Nanocrystalline (<100 nm grain size) oxide coatings yield faster sensor response times than conventional larger-grained coatings due to faster oxygen diffusion along grain boundaries rather than through grain interiors.

대표청구항 ▼

A gas sensor for detection of oxidizing and reducing gases, including O2,CO2,CO, and H2,monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temper

A gas sensor for detection of oxidizing and reducing gases, including O2,CO2,CO, and H2,monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temperature rise of the metallic line is inversely proportional to the thermal conductivity of the oxide coating. The oxide coating contains multi-valent cation species that change their valence, and hence the oxygen stoichiometry of the coating, in response to changes in the partial pressure of the detected gas. Since the thermal conductivity of the coating is dependent on its oxygen stoichiometry, the temperature rise of the metallic line depends on the partial pressure of the detected gas. Nanocrystalline (10while the driven roller has a diameter D27,and the other shaft is positioned lower than the one shaft in a vertical direction by a height difference which is up to 1/2,000 of the smaller one of the diameter D10and diameter D27. . 9. The method of claim 8 wherein the least-mean-square fit used to estimate the coefficients a and b is in accordance with minimizing Jmgiven by the following expression: 10. The method of claim 9 wherein the determination of the coefficients comprises: determining a partial derivative of Jmwith respect to am; determining a partial derivative of Jmwith respect to bm; setting both the partial derivatives equal to zero; and, solving the two resulting equations for the coefficients amand bm. 11. The method of claim 10 wherein the determination of the mthestimate of the resonant frequency comprises estimating the resonant frequency in accordance with the following equation: wherein fmis the mthestimate of the resonant frequency based upon m+2 consecutive input data samples used to compute amand bm; and wherein T is a sampling period. 12. The method of claim 11 wherein the envelope of the decaying sinusoidal output is given by the following equation: wherein yn,mthe nthsample of the envelope of the decaying sinusoidal output when the mthset of amand bmparameter estimates are used in the envelope generation, wherein xn,xn-1,and xn-2are samples of the decaying sinusoidal output, and wherein a and b are the coefficients of the linear difference equation. 13. The method of claim 1 wherein the gyro comprises a vibrating quartz gyro. 14. The method of claim 1 wherein the gyro comprises parallel tines. 15. A method comprising: delaying an input by one sample period to produce a first delayed quantity; delaying the input by two sample periods to produce a second delayed quantity; squaring the second delayed quantity; averaging the squared second delayed quantity to produce a first output P0; multiplying the first and second delayed quantities to produce a first product; averaging the first product to produce a second output P1; squaring the first delayed quantity; subtracting a square of a first sample of the input from the squared first delayed quantity to form a first difference; dividing the first difference by a total number of samples of the input to produce a first result; adding the first output P0to the first result to produce a third output P2; multiplying the input and the first delayed quantity to produce a second product; subtracting a product of the first sample and a second sample of the input from the second product to form a second difference; dividing the second difference by the total number of samples of the input to produce a second result; adding the second output P1to the second result to produce a fourth output R0; multiplying the input and the second delayed quantity to produce a third product; averaging the third product to produce a fifth output R1; and, determining a resonant frequency f of a device providing the input based upon the first, second, third, fourth, and fifth outputs. 16. The method of claim 15 wherein the gyro comprises a vibrating quartz gyro. 17. The method of claim 15 wherein the gyro comprises parallel tines. 18. The method of claim 15 wherein the determining of the resonant frequency f comprises: determining a coefficient amaccording to the following equation: determining a coefficient bmaccording to the following equation: and, determining the resonant frequency f according to the following equation: wherein Dmis given by the following equation: Dm=P0(m)P2(m)=[P1(m)]2. 19. The method of claim 18 further comprising: applying the coefficient bmto the second delayed quantity to produce a sixth output; subtracting the sixth output from the input to produce a seventh output; squaring the seventh output; applying a factor Km2to the squared seventh output to produce an eighth output; applying the coefficient bmto the squared first delayed quantity to produce a ninth output; adding the eighth and ninth outputs to produce an envelope yn; estimating a decay parameter c for the envelope yn; and, estimating a Q of the device in accordance with the following equation: wherein Qm,fm,and cmare the mthestimates of Q, frequency f, and decay parameter c, respectively, and wherein Km2is determined in accordance with the following equation: 20. The method of claim 15 wherein the delaying of the input by two sample periods comprises delaying the first delayed quantity by one sample period to produce the second delayed quantity. 21. The method of claim 15 wherein the first sample comprises an initial sample, and wherein the second sample comprises a sample next following the initial sample. 22. A method comprising: delaying an input by one sample period to produce a first delayed quantity; delaying the input by two sample periods to produce a second delayed quantity; squaring the second delayed quantity; averaging the squared second delayed quantity to produce P0; combining an expected value S0of the square of a noise sample with P0to produce a first output P'0; multiplying the first and second delayed quantities to produce a first product; averaging the first product to produce P1; combining an expected value S1of a product of two adjacent noise samples with P1to produce a second output P'1; squaring the first delayed quantity; subtracting a square of a first sample of the input from the squared first delayed quantity to form a first difference; dividing the first difference by a total number of samples of the input to produce a first result; adding the first output P'0to the first result to produce a third output P'2; multiplying the input and the first delayed quantity to produce a second product; subtracting a product of the first sample and a second sample of the input from the second product to form a second difference; dividing the second difference by the total number of samples of the input to produce a second result; adding the second output P'1to the second result to produce a fourth output R'0; multiplying the input and the second delayed quantity to produce a third product; averaging the third product to produce R1; combining an expected value S2of a product of two noise samples separated by one sampling period with R1to produce a fifth output R'1; and, determining a resonant frequency f of a device providing the input based upon the first, second, third, fourth, and fifth outputs. 23. The method of claim 22 wherein the gyro comprises a vibrating quartz gyro. 24. The method of claim 22 wherein the gyro comprises parallel tines. 25. The method of claim 22 wherein the determining of the resonant frequency f comprises: determining a coefficient amaccording to the following equation: determining a coefficient bmaccording to the following equation: and, determining the resonant frequency f according to the following equation: wherein D'mis given by the following equation: D'm=P'0(m)P'2(m)-[P'1(m)]2. 26. The method of claim 25 further comprising: applying the coefficient bmto the second delayed quantity to produce a sixth output; subtracting the sixth output from the input to produce a seventh output; squaring the seventh output; applying a factor Km2to the squared seventh output to produce an eighth output; applying the coeffic