992 resultados para fiber-optic sensor
Resumo:
We describe the design, calibration, and performance of surface forces apparatus with the capability of illumination of the contact interface for spectroscopic investigation using optical techniques. The apparatus can be placed in the path of a Nd-YAG laser for studies of the linear response or the second harmonic and sum-frequency generation from a material confined between the two surfaces. In addition to the standard fringes of equal chromatic order technique, which we have digitized for accurate and fast analysis, the distance of separation can be measured with a fiber-optic interferometer during spectroscopic measurements (2 Å resolution and 10 ms response time). The sample approach is accomplished through application of a motor drive, piezoelectric actuator, or electromagnetic lever deflection for variable degrees of range, sensitivity, and response time. To demonstrate the operation of the instrument, the stepwise expulsion of discrete layers of octamethylcyclotetrasiloxane from the contact is shown. Lateral forces may also be studied by using piezoelectric bimorphs to induce and direct the motion of one surface.
Resumo:
Visible and near infrared (vis-NIR) spectroscopy is widely used to detect soil properties. The objective of this study is to evaluate the combined effect of moisture content (MC) and the modeling algorithm on prediction of soil organic carbon (SOC) and pH. Partial least squares (PLS) and the Artificial neural network (ANN) for modeling of SOC and pH at different MC levels were compared in terms of efficiency in prediction of regression. A total of 270 soil samples were used. Before spectral measurement, dry soil samples were weighed to determine the amount of water to be added by weight to achieve the specified gravimetric MC levels of 5, 10, 15, 20, and 25 %. A fiber-optic vis-NIR spectrophotometer (350-2500 nm) was used to measure spectra of soil samples in the diffuse reflectance mode. Spectra preprocessing and PLS regression were carried using Unscrambler® software. Statistica® software was used for ANN modeling. The best prediction result for SOC was obtained using the ANN (RMSEP = 0.82 % and RPD = 4.23) for soil samples with 25 % MC. The best prediction results for pH were obtained with PLS for dry soil samples (RMSEP = 0.65 % and RPD = 1.68) and soil samples with 10 % MC (RMSEP = 0.61 % and RPD = 1.71). Whereas the ANN showed better performance for SOC prediction at all MC levels, PLS showed better predictive accuracy of pH at all MC levels except for 25 % MC. Therefore, based on the data set used in the current study, the ANN is recommended for the analyses of SOC at all MC levels, whereas PLS is recommended for the analysis of pH at MC levels below 20 %.
Resumo:
This report is divided into two volumes. This volume (Volume I) summarizes a structural health monitoring (SHM) system that was developed for the Iowa DOT to remotely and continuously monitor fatigue critical bridges (FCB) to aid in the detection of crack formation. The developed FCB SHM system enables bridge owners to remotely monitor FCB for gradual or sudden damage formation. The SHM system utilizes fiber bragg grating (FBG) fiber optic sensors (FOSs) to measure strains at critical locations. The strain-based SHM system is trained with measured performance data to identify typical bridge response when subjected to ambient traffic loads, and that knowledge is used to evaluate newly collected data. At specified intervals, the SHM system autonomously generates evaluation reports that summarize the current behavior of the bridge. The evaluation reports are collected and distributed to the bridge owner for interpretation and decision making. Volume II summarizes the development and demonstration of an autonomous, continuous SHM system that can be used to monitor typical girder bridges. The developed SHM system can be grouped into two main categories: an office component and a field component. The office component is a structural analysis software program that can be used to generate thresholds which are used for identifying isolated events. The field component includes hardware and field monitoring software which performs data processing and evaluation. The hardware system consists of sensors, data acquisition equipment, and a communication system backbone. The field monitoring software has been developed such that, once started, it will operate autonomously with minimal user interaction. In general, the SHM system features two key uses. First, the system can be integrated into an active bridge management system that tracks usage and structural changes. Second, the system helps owners to identify damage and deterioration.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
Resumo:
The ICN, a state agency, is the country’s premier fiber-optic Network, committed to continued enhancement of distance learning and providing Iowans with convenient, equal access to education, government, and healthcare. This newsletter is produced monthly by the ICN of all the programs and activities of this department.
