Based on our successful technology of conductance liquid level sensor, combined with the long-period fiber Bragg
grating sensor technology, a floating optical-electrical (OE) sensor array system is designed aimed at the early
monitoring of oil contamination of offshore marine oil spill and pollution control as well as the safety at sea.
A discrete liquid level sensor based on fiber Bragg grating (FBG) that is suitable for liquid level monitoring is proposed.
FBG (fiber Bragg grating) is embedded in a cantilever beam which is made of carbon fiber composite. And an iron sheet
is bonded with the end of cantilever beam. For the float, a magnet is bonded with the float. When the liquid level rises or
fall, the float will move up or down. The cantilever beam will bend downward or upward, it will induce strain on the
FBG. Therefore, the Bragg wavelength of FBG will shift. An extra reference grating was utilized for temperature
compensation.
In this paper, a novel pressure sensor based on carbon fiber laminate tube (CFLT) and fiber Bragg grating is proposed.
Theoretical analysis and investigation are conducted. Experiment results indicate that the pressure sensitivity is
138pm/MPa. Pressure sensitivity is improved due to the hollow tube structure compared with solid structure of pressure
sensor that we proposed before.
A novel liquid-level sensor based on a fiber Bragg grating and carbon fiber composite diaphragm is proposed and demonstrated. The sensing principle and finite element analysis result are described. Because the carbon fiber composite diaphragm's thickness is 0.2 mm and thinner than that of other materials, the sensitivity of the liquid-level sensor is improved. The experimental results show that sensitivity can reach 0.185 nm/m of water height. Based on the high sensitivity and the simple structure of the sensor, this sensor can find applications in the area of liquid level sensing.
A temperature-compensated strain-sensing sensor based on fiber Bragg gratings (FBGs) that is suitable for strain
mapping of rock in coal exploring application is demonstrated. FBGs were bonded to carbon fiber laminated composite
(CFLC) and they were arranged in a FBG rosette configuration used to determine the direction and magnitude of the
principal strain, information that is required for strain mapping. An extra reference grating was utilized for temperature
compensation measurement.
A novel liquid-level sensor based on fiber Bragg grating and carbon fiber composite diaphragm is proposed and
demonstrated. The sensing principle and finite element analysis result are described. From the experimental result, this
sensor shows high sensitivity and good repeatability. This sensor can find applications in the area of the liquid level
sensing.
An optical fiber pressure sensor based on fiber Bragg grating (FBG) and metal bellows is presented in this paper. Due to
the lower spring rate of metal bellows, the sensitivity is improved to 48pm/kPa. The relationship between Bragg
wavelength and the applied pressure is derived. Experimental data indicates that there is good linear relation between the
Bragg wavelength shift and the applied pressure. This sensor can be utilized in low pressure measurement.
A novel structure of an optical fiber pressure sensor based on a fiber Bragg grating (FBG) and metal bellows is presented. Due to the novel structure, the sensitivity is improved to 48 pm/kPa. The relationship between Bragg wavelength and the applied pressure is derived. Experimental data indicates that there is a good linear relation between the Bragg wavelength shift and the applied pressure. This sensor can be utilized in low-pressure measurement.
A portable, multi-function WIM sensing system based on Fiber Bragg Grating (FBG) technology is developed to
measure the total weight, the distribution of weight of vehicle in motion (the weights of left front, right front, left rear
and right rear wheels respectively), the distance of wheels axles and distance between left and right wheels. Currently the
speed of vehicle to be tested can be up to 15 mph, the full scope of measurement for this system is 4000 lbs, and the
static sensitivity of sensor head is 20 lbs. This system has been tested respectively at Stevens' campus and Army base.
Compared to other schemes, our method has a number of advantages such as immune to electromagnetic interference,
high repeatability, lightweight, low power consumption, high sensitivity to dynamic strain caused by load of vehicles in
high-speed. The accuracy of whole system can be improved by simulating the mathematical model of sensor heads and
improving the quality of manufacture as well as the calibration condition in the future.
Because methane is an inflammable and explosive gas, it is indispensable to monitor methane. It is very useful to develop a portable methane detector in order for the application multiple purpose, such as coal mine safety monitoring. This paper gives a prototype design of a portable methane gas sensor with 1.65μm LED. Sensor is made by a 1.65μm LED and high responsivity photo receiver. The experimental result shows nearly linear at low methane concentration. And a prototype portable gas sensor has been demonstrated.
According to the chromatic theory, the color sensitive characteristic of light source are studied in the widely used CIE1976L*a*b* color space and color difference. The mathematics formulae of characteristic are deduced. The color sensitive characteristics of D65 and A light source are studied. The general laws of the color sensitive characteristic are concluded. The mathematics models of light source can be used in some fields such as making light source.
Hyperspectral image can be analyzed by Convex Geometry Analysis(CGA) method. CGA method can unmix endmembers from hyperspectral image. The endmember proportions of mixed pixels can be calculated in inherent dimensional space, and a proportion image, which is called inherent proportion image, is obtained. The endmember proportions of mixed pixels can be calculated in n-space by the Constrained Least Squares, and a proportion image, which is called CLS proportion image, is obtained. In this paper, the inherent proportion image and CLS proportion image of a 30-band remote sensing image are obtained. The two proportion images are similar. The targets that are smaller than earth surface pixel can be identified by the inherent proportion image.
We analyze the inherent channels of hyperspectral data with convex geometry analysis method. In this paper, a method-Volume Method, which selects the inherent channels of hyperspectral data, is presented. The concept of convexity geometry can be used to great advantage in the analysis of hyperspectral data. Convex simplex and inherent dimensionality concept is discussed on base of convex geometry. A set of 252-band hyperspectral data is applied to testify the Volume Method. The endmember proportions are calculated in the inherent dimensional space whose channels are selected by the Volume Method, compared with Constrained Least Squares Method in 252-space.
On the basis of spectrophotometric color matching, the color difference weight factor is proposed and used in the thesis. The weight factor can be expressed as ωj = {{[(x(λj)]2 + [y(λj)]2 + [z(λj)]2}[S(λj)]2}½ and obtained according to the assumption of Σj(ΔXj)2+(ΔYj)2+(ΔZj)2 -> min, i. e., in the range of visible spectrum it is assumed that the square sum of tri-stimulus value deviation produced by spectrum deviation at each wavelength is minimal.Through comparison with spectrophotometric color matching, we find a new weight factor. The new factor multiplied by the variety of reflectivity is the color difference, which is cause by the difference of reflectivity between standard color and matching color. So we name the weight factor: color difference weight factor. The prediction of computer shows the color difference produced by the weight factor is smaller than that produced by the two weight factors which were designed by Schmid and Strockash.
Color sensitive functions of object is defined in the widely used CIE1976L*a*b* color space and color difference. Mathematics formulae are deduced. The general law of color sensitive functions is concluded. Mathematics models can be used in some fields such as computer color matching.
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