Article

Principles of photoelectric sensing: Part II

August 1995

Authors:

The principles of photoelectric sensing, with particular emphasis on excess gain measurement, are discussed. The relationship between excess gain and sensing distance is examined using an opposed mode sensor pair as an example. The retroreflective excess gain curves are plotted using a Model BRT-3 3-in. diameter retroreflector. Proximity mode sensing and its effect on excess gain is also examined.

Laser-based fibre-optic sensor for measurement of surface properties

Thesis

Full-text available

May 1998

Brian Cahill

This project deals with the design and development of an optoelectronic sensor system and its possible use in online applications There are two different configurations of this sensor a sensor for surface roughness and another for defect detection. In each configuration the mechanical and optical design are almost identical-optical fibres convey light to and from a surface. Light source driving circuits and photodetection circuits were developed for each sensor. Data acquisition and analysis algorithms were developed for each sensor.

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Article

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Design and Experimental Analysis of Novel Refractometer Based on Photoelectric Sensor Technology

November 2011 · Advanced Materials Research

A novel refractometer based on photoelectric sensor technology and differential method is proposed. Sensing principle and mathematical model are introduced; structure and key parameters of sensing probe are designed through detail calculation. Theoretical solution shows resolution reaches order of 10-5. Preliminary experiments verify the feasibility of the design, experimental results show ... [Show full abstract] stability error better than ±1.02×10-4, error caused by temperature is 6.65×10-6/°C.

Article

Implementing chemical sensors in industry: novel approaches

August 1991 · Sensors and Actuators B Chemical

In the chemical industry, the need for real-time process and environmental control has elicited a great interest in chemical sensors. However, their successful introduction has not been achieved in spite of promising results at university laboratories. Ways of filling this gap will be demonstrated here. In many industrial applications, the measurand must be detected in the midst of many ... [Show full abstract] interfering substances which can be present in large excess. Because applications and their associated matrices vary widely, the sensing principle must be incorporated into a total analysis system (TAS), which will perform sample pretreatment, protect the sensor from aggressive matrices, and even provide a preliminary separation. This modular system is configured according to its exact application. Realized state-of-the-art TASs for process and environmental analytical applications as well as novel systems now containing chemical sensors will be presented.

Conference Paper

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Twin-core fiber-based sensor for measuring the strain and bending simultaneously

August 2013 · Proceedings of SPIE - The International Society for Optical Engineering

A novel composite interferometer sensor is presented and its sensing characteristics are investigated. Based on the infiber integrated Michelson interferometer, a quartz tube is used to encapsulate the ends of the twin-core fiber and single mode fiber to form the dual extrinsic FP cavities. Thereby, the Michelson and FP configurations are integrated into a single fiber, which we call it ... [Show full abstract] Michelson-FP composite interferometer sensor. The novel sensor can respond to the axial strain and radial bending simultaneously. We have derived and analyzed the interferometer principle of the new structure. The analysis results show that the interferometer sensor could be considered as the superposition of Michelson interferometer and FP interferometer. Moreover, we establish a testing system and conduct a series of experiments to investigate the strain and bending characteristics. We measure the reflection spectra with the spectrum analyzer. The spectral response of the composite interferometer sensor presents two pattern fringes with different frequencies due to the respective optical path interferometers. The experimental results indicate that the composite interferometer sensor is very sensitive to the strain and bending characteristics, and the presented sensor has different strain and bending sensitivity coefficients. Due to these characteristics, the presented sensor might be able to measure the strain and bending characteristics simultaneously. In conclusion, the presented novel interferometer sensor is of compact structure, high integration and good strain and bending sensing characteristics. Thus, many types of fiber-optic sensors may be built based on it.

Article

Design and realization on novel fiber torsional angle sensor with bidirectional tuning

September 2002

The basic principle and the sensing structure of a novel torsion sensor are proposed. The theoretical formulas of torsional angle sensing are derived and the torsional angle of this sensor is linear to the power loss of the multi-mode fiber. In the range of the torsional angle between -40° and +40°, the torsion sensing has been realized technologically with the sensitivities 0.375 dB/degree for ... [Show full abstract] the symmetrically bidirectional linear torsion sensing and 0.592 dB/degree for the bidirectional unsymmetrical linear torsion sensing.

Article

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Solutions for Measuring Weight of Bead Wires

June 2016 · Applied Mechanics and Materials

This article describes the design options of sensing weight based on the principle of strain gauges. Measuring method is based on the measurement of deformations on the surface of the body, which is converted to the change in electrical resistance. This is an electrical resistance sensor, which consists of smaller cross-section wire of a suitable material and substrate for wire attached. ... [Show full abstract] Depending on what principle the sensor works, there are various types: such as bending, membrane, staple, ring and other. Moreover, the sensor can be made of different materials, most often of steel or aluminum alloy. The article describes two options of measuring the bead wires: measurement about the effector and measurement on the measuring stand.

Article

A New Potentiometric Sensor for the Detection of Trace Metallic Contaminants in Hydrofluoric Acid

October 1996 · Journal of The Electrochemical Society

Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions was demonstrated using a silicon-based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open-circuit potential shift generated by the charge-transfer reaction between metallic ions and the silicon-based sensing surface. For instance, the silicon-based sensor ... [Show full abstract] is capable of detecting parts per-trillion to parts-per billion level of Ag+ ions in HF solutions with a detection sensitivity of ca. +150 mV shift per decade change of [Ag+].The new sensor can have practical applications in the on-line monitoring of microelectronic chemical processing.

Article

Detecting natural gas pipeline leakage with optical fiber sensing system

August 2006

To carry out on-line detection of pipeline leakage and its location, sensor temperature characteristics are good advantage for optical fiber grating and distributed optical fiber. Combined with the changing rule of temperature field at the leakage point of the gas pipeline, leakage detection using the optical fiber grating system and the distributed optical fiber system was studied. The sensor ... [Show full abstract] system and its principle both the pseudo-distributed optical fiber grating the sensor system and the distributed optical based on the Laman light reflex were analyzed. Temperature sensing detection technology of optical fiber grating and distributed optical fiber were adopted to detect the key points of the line and continuous temperature detection along the whole pipeline. In this way, any leakage could be found out and pointed directly and exactly by detecting abnormal variation of the temperature field around the gas pipeline.

Article

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A Location Temporal based Access Control Model for IoTs

December 2013 · AASRI Procedia

Internet of things (IoTs) is a hot topic in recent years, and its various applications have been applied in several fields. The essence of IoTs is to connect all the things including the devices embedded RFID, sensors, etc. together, to help people utilizing the information from the things to improve their life. The things are always located at different places at different times, and the ... [Show full abstract] information of the thing may have different access right at different location during different time. Therefore, the access control mechanism in IoTs should consider location and temporary constraints in order to enhance the security of an application. In this paper, we propose a model that combines location and time with security level to control access to the information within the sensing layer of the IoTs. This model is called Location-Temporal Access Control Model(LTAC). The main principle of LTAC is its use of a lattice approach to decrease the size of policy bases. We show that how the different components in the model are related with location and how this location information can be used to determine whether a subject has access to a given object.

Article

Study of a new principle for digital sensors

January 1970

M. Chatanier

A principle of digital sensing is proposed that makes use of the magnetostrictive and anisotropic properties of a thin ferromagnetic film. These properties make it possible to quantify a signal as a function of the stress applied to the film. The phenomenon of reversal of magnetization in the film depending on the stress is the central characteristic applied. Preliminary experimental results ... [Show full abstract] concerning the new principle are presented.

Article

A Sensing Data Driven Clustering Algorithm for Adaptive Sampling in Wireless Sensor Networks

June 2012 · Applied Mechanics and Materials

The objective of environmental observation with wireless sensor networks is to extract the synoptic structures of the phenomena of region of interest (ROI) in order to make effective predictive and analytical characterizations. Adaptive sampling strategy is regarded as a much promising method for improving energy efficiency in recent years. However due to distributed characteristics of wireless ... [Show full abstract] sensor networks adaptive sampling schemes should be operated in a distributed manner with clustering algorithm. In this paper we dedicate to investigating appropriate sensing-aware clustering algorithm for adaptive sampling. The principle of SAC algorithm follows such metric: sensor nodes that are similar to each other in terms of their observed sensory data should be clustered into one group. Besides sensor nodes will join in its nearest cluster for the sake of spatial correlation model with Euclidean physical distance. By emphasizing on the sensing-aware clustering it helps to derive better spatial correlation to guarantee adaptive sampling. The simulation results verify SAC algorithm at the aspect of correlation factor.

Article

The Longitudinal Temperature Detection System and Its Application of the Distributed Optical Fiber F...

June 2015 · The Open Automation and Control Systems Journal

The modeling illustrates the equation of the relation between the temperature of the freezer and the radius of the tjaele, so the horizon tjaele radius can be calculated by the temperature of the horizon freezer. Compared with the single bus temperature sensor system, the former can measure the continuous longitudinal temperature distribution at the spatial resolution of 1m, thus the relevant ... [Show full abstract] tjaele radius can be calculated, the same is of the whole longitudinal direction, therefore, the closure plans of ice wall can be examined by the freezer overlay. The thesis firstly gives us an introduction of the construction, working principle and methods of the distributed optical fiber freezer, and then shows some examples.

Article

Effect of Sensor Gauge Length on Strain Sensitivity of a Fiber Bragg Grating System

October 2011 · Chinese Journal of Physics

This study explores the effect of sensor length on the strain sensitivity of a fiber Bragg grating system. The sensitive system, protection of the grating region, sensor pre-tensioning, adhesive, and choice of sensor length are the concerns which must be considered before/during the testing and installation of a fiber Bragg grating sensor. A simple experimental setup, including a detector and ... [Show full abstract] light source, may be utilized to obtain the wavelength shift and hence the strain measurements. The sensing principle is based on tracking the wavelength shift due to the change of the lateral stress that was applied by turning the screw gauge on the fiber grating bonded on a material. It is inferred from the results that if the effective gauge length is smaller, then the shift in the wavelength and strain is larger and vice versa. It has also been demonstrated that the fiber Bragg grating system is more sensitive to a smaller sensor length and less to a larger sensor length. The measured strain sensitivity of a 10 cm and a 15 cm sensor is 0.0011 nm/με and 0.0016 nm/με, respectively, under the same loading conditions. The experimental results also show the capability of the proposed system to perform strain measurements.