Prototype Measurement System Research Articles

볼렌즈를 이용한 광학식 진직도 측정시스템

This paper proposes a simple method to improve a sensitivity of a straightness measurement system for a linear stage, which is applied to a system based on a geometric optic method. An optical system for this method is composed of a corner-cube retro-reflector, a ball-lens and a two-dimensional position sensitive detector (2D PSD). The effectiveness of the proposed method was examined theoretically, and verified experimentally using a prototype measurement system. The results show that the measuring sensitivity was dependent on the size of the ball-lens and the setup position of PSD from the ball-lens, and that the proposed method is efficient method to improve the measuring sensitivity.

Contactless Liquid-Level Measurement With Frequency-Modulated Millimeter Wave Through Opaque Container

A novel contactless method for measuring liquid level through an opaque container is proposed. A millimeter-wave Doppler sensor is developed to “see” (i.e., sense) through a target container and measure the liquid level on the basis of the absorption of millimeter waves in liquid. One of the challenges is to accurately measure liquid level (within sub-millimeter error) despite the inherently large beam diameter of the millimeter wave due to diffraction. A piezoelectric vibrator enables accurate measurement by reflecting a limited portion of the spread beam and modulating it in frequency to distinguish it from the other portion of the beam. A prototype measurement system is fabricated and evaluated. The feasibility of our proposed method for clearly detecting an air-liquid interface concealed in an opaque container is confirmed experimentally. The nonlinearity error of the measured liquid level is within ±0.5 mm .

Continuous minimally invasive peri-operative monitoring of cardiac output by pulmonary capnotracking: comparison with thermodilution and transesophageal echocardiography

A number of technologies are available for minimally-invasive cardiac output measurement in patients during surgery but remain little used. A system has been developed based on CO(2) elimination (VCO(2)) by the lungs for use in ventilated patients, which can be fully integrated into a modern anesthesia/monitoring platform, and provides semi-automated, continuous breath-by-breath cardiac output monitoring. A prototype measurement system was constructed to measure VCO(2) and end-tidal CO(2) concentration with each breath. A baseline measurement of non-shunt cardiac output was made during a brief change in ventilator rate, according to the differential CO(2) Fick approach. Continuous breath-by-breath monitoring of cardiac output was then performed from measurement of VCO(2), using a derivation of the Fick equation applied to pulmonary CO(2) elimination. Automated recalibration was done periodically and data was processed and cardiac output displayed in real time. Measurements were compared with simultaneous measurements by bolus thermodilution in 77 patients undergoing cardiac surgery or liver transplantation. Overall mean bias [sd] for agreement in cardiac output measurement was -0.1 [1.2] L/min, percentage error +44.2%, r=0.92. Concordance in measurement of changes of at least 15% in cardiac output was 80%. The method followed sudden changes in cardiac output due to arrythmias and run onto cardiopulmonary bypass in real time. The accuracy and precision were comparable to other clinical techniques. The method is relatively seamless and largely automated and has potential for continuous, cardiac output monitoring in ventilated patients during anesthesia and critical care.

Measurement of Grain Size of Hot-rolled Steel Sheets Using Laser-Based ultrasonics

The relationship between grain size of hot-rolled steel sheet and ultrasonic attenuation coefficient has been evaluated in laboarory and pilot plant using laser-based ultrasonic technology. For the measurement of ultrasonics in pilot plant, the Fabry-Perot interferometer was optimized to increase the signal to noise ratio. Also, the efficiency of ultrasonic generation using multiple laser pulses was evaluated experimentally for generation of ultrasonics in slightly ablative condition. The prototype measurement system was installed in pilot rolling plant and ultrasonic signals were measured during hot-rolling process. According to the results of laboratory and pilot plant, possibility of on-line measurement of grain size of hot-rolled steel sheet in production line has been confirmed.

Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor

A prototype fiber-optic reflectance-mode pulse oximetry sensor and measurement system is developed for the purposes of estimating arterial oxygen saturation in the esophagus. A dedicated probe containing miniature right-angled glass prisms coupled to light sources and a photodetector by means of optical fibers is designed and used to record photoplethysmographic (PPG) signals from the esophageal epithelium in anesthetized patients. The probe is inserted simply by an anesthesiologist in all cases, and signals are recorded successfully in all but one of 20 subjects, demonstrating that esophageal PPG signals can be reliably obtained. The mean value of the oxygen saturation recorded from the esophagus for all subjects is 94.0 ± 4.0%. These results demonstrate that SpO(2) may be estimated in the esophagus using a fiber-optic probe.

Optical method for inspecting surface defects inside a small bore

Most automotive powertrain parts made of castings have surface defects such as pores. However, detecting pores inside small diameter bores is a challenge because of the limited dimensional accessibility. Adding to this difficulty is the auto industry's desire to conduct the porosity inspection in-line, i.e. within the machining production cycle time of a part. A technique or equipment that meets these requirements currently does not exist. In order to meet these demands, it is necessary to develop an entire new methodology to inspect the inner surface of small diameter bores. This paper presents an innovative methodology to inspect the porosity of the inner surface of small bores and to provide their characteristics such as size and location. A prototype measurement system was built and tested in the lab. Experimental results showed the proposed method to be reliable and consistent.

A high speed and compact system for profile measurement of scroll compressors

Profile measurement of a scroll compressor is important for improving compression efficiency. This paper describes the height profile measurement of a scroll compressor in the manufacturing line using a prototype measurement system. A commercial CMM is also employed for comparison. The measurement repeatability of the height profile by the prototype measurement system is approximately ±1 µm, which satisfies the requirements from the manufacturing line. Through compensation of the tilt component, result of the prototype measurement system is in good agreement with that of the commercial CMM.

Preliminary Study for Determination of Distal Dose Edge by Measuring 90-deg Prompt Gammas with an Array-Type Prompt Gamma Detection System

A scanning-type prompt gamma measurement system, called prompt gamma scanner (PGS), was constructed and used to determine the relationship between the proton dose distribution and the longitudinal profile of the prompt gammas generated by the nuclear interaction from the proton beam passage in a medium. However, the PGS system entails insuperable difficulties when used in clinical proton therapy owing to its scanning process. In order to measure the prompt gamma distribution without the scanning process, it was proposed to develop an array-type prompt gamma measurement system that can measure the prompt gammas with a linear array of radiation detectors through multiple collimation slits. Prior to constructing a full-scale measurement system with many detectors and multiple data acquisition channels, a simplified prototype measurement system, using only one detector moving from one measurement location to the next, was constructed in the present study and applied to a 39-MeV proton beam. The results are very encouraging, as the prototype measurement system predicted the distal dose edge very accurately within a few millimeters of error despite the fact that the level of background gammas increased as a result of reduced collimator shielding.

An Electronic Method for Measuring the Fit of Removable Partial Denture Frameworks to Dental Casts

It is well established that the Removable Partial Denture (RPD) is an effective treatment prosthesis. The objectives of a successful RPD are: to preserve the health of remaining oral structure, restore function and restore esthetics. To achieve these objectives, an RPD framework must fit accurately to the supporting structures. This paper presents a method for measuring the gaps or spaces present between the RPD framework and supporting structures which will enable the dentist and the dental technician to evaluate the accuracy of fitting of the prosthesis before it is delivered to the patient. The method used in this research is based on the principle of electric capacitance and uses a specially designed prototype measurement system.

Development and testing of a micro-thruster impulse characterization system utilizing pendulum swing time measurements

A new method for measuring the performance of a micro-thruster is suggested in this paper. A few thrust stands have been developed for measuring micro-level thrusts. This paper describes a different measurement method that can minimize the calibration involved in the measurements, while providing the capability of directly measuring the produced minimum impulse bit. The underlying theory and the theoretical background for the measurement mechanism are described here. The theory and method is verified using a computer simulation, and the result is given in this paper. The theory has also been tested on an actual hardware. The prototype measurement system has been tested inside a vacuum chamber for verification of theoretical and simulation results. Actual experimental data was used to verify the theory and a test cold gas thruster was also employed for final testing and verification of the measurement system.

Non-invasive automated measurement of cardiac output during stable cardiac surgery using a fully integrated differential CO2 Fick method

To re-evaluate the accuracy and precision of a non-invasive method for measurement of cardiac output based on the differential CO(2) Fick approach using an automated change in respiratory rate delivered by a ventilator under control by a prototype measurement system. Twenty-four patients during coronary artery bypass surgery, pre- and postcardiopulmonary bypass were recruited. After routine cannulation including pulmonary artery catheter, relaxant general anesthesia was induced. After hemodynamic and ventilatory stability were achieved, simultaneous paired measurements were made by the differential Fick method and by bolus thermodilution. Measurements were generated by inducing a change in respiratory rate by the ventilator under computer control. In Group 1, this involved an increase in respiratory rate from 8 to 12 breaths/min. In Group 2, this involved a decrease from 12 to 6 breaths/min. Nineteen measurements were made in each Group, 12 pre-CPB and 7 post-CPB. In Group 1 mean bias was -0.06 l/min, with a precision of agreement of 0.87 l/min, r = 0.91. In Group 2 (excluding one outlier) mean bias was -0.07 l/min, with a precision of 1.12 l/min, r = 0.71. Acceptable agreement with thermo- dilution during surgery was found, particularly where the ventilatory change involved an increase in respiratory rate from a lower baseline. This approach has potential to be readily integrated into modern anesthesia delivery platforms, allowing routine non-invasive cardiac output measurement.

Continuous liquid level measurement using a linear electrode array

This paper describes a novel continuous liquid level measurement technique based on a linear electrode array, which is vertically immersed in the liquid to inject an electric current into it and measure the voltage profile at different depths. We develop models that describe the relationship between voltage and liquid level for several vessel geometries of practical interest. Then, an inverse problem iterative algorithm is used to calculate the liquid level from the set of voltage measurements. The level accuracy values are far smaller than the interelectrode spacing and no calibration procedure is required. We describe a prototype measurement system to measure the water level in a 100 cm deep rectangular tank with a level accuracy of 3 mm when the electrodes are 5 cm apart.

Objective measurement of the quality of airport lighting whilst in service

This paper contributes to the science of measurement and control by outlining a unique methodology for objectively assessing the luminous intensity of all luminaires forming an airport landing lighting pattern, whilst in service, to check that the lighting pattern conforms to the strict standards set by airports’ governing body within the UK the Civil Aviation Authority (CAA). Central to this methodology is a novel air-based measurement system consisting of charge-coupled device (CCD) cameras and dedicated image-processing software. This prototype measurement system is placed inside the cockpit of an aircraft and is used to take images of the airport landing lighting system whilst the aircraft approaches the airport. Developed image-processing techniques then allow unique luminaire identification and extraction from the hundreds of luminaires within the airport lighting pattern. The corresponding luminous intensity and alignment of each luminaire is derived using dynamic position and orientation information estimated from a visual environment model. By obtaining luminous intensity and alignment information for each luminaire within the pattern, it is then possible to derive its associated isocandela diagram. This then allows an assessment to be made regarding the luminaires’ conformity to the CAA standards. The unique system has been tested at Belfast International Airport, the results of which are documented within this paper. The results indicate that further work is necessary if the system is to be fully functional. Currently it takes approximately 35 h to filter the results for one complete pattern. In addition, a maximum error of 40% is reported between derived and actual luminous intensity measurements for a given luminaire. The reasons for this discrepancy are highlighted in the discussion and improvements are currently being made to the system to account for these. However, the results and the work reported within this paper reflect the belief that digital imaging can be utilized to automate many physically large photometry problems within the fields of science and engineering. The methodology described for the development of this measurement system is unique and we believe extends the science of automated dynamic measurement systems.

Noninvasive, Automated and Continuous Cardiac Output Monitoring by Pulmonary Capnodynamics

Cardiac output monitoring is most important where cardiovascular stability is potentially threatened, such as during major surgery and in critically ill patients. However, continuous monitoring of cardiac output is still not performed routinely during anesthesia and critical care, because of invasiveness, expense, and inaccuracy of available technologies. A technique termed the capnodynamic method was tested for breath-to-breath measurement of pulmonary blood flow from lung carbon dioxide mass balance, using measured carbon dioxide elimination and end-tidal concentration. A prototype measurement system was constructed for a feasibility study in six anesthetized sheep. Large and rapid fluctuations in cardiac output were generated by repeated dobutamine and esmolol challenge. Measurements were compared with an indwelling ultrasonic flow probe placed on the ascending aorta or pulmonary artery. Cardiac output measured by the flow probe varied between zero and 8.67 l/min, with a mean of 3.50 l/min. Overall mean bias [SD of the difference] between the methods (capnodynamic - flow probe) was -0.25 [0.94] l/min, r = 0.79 (P < 0.001). During periods of stability in cardiac output of 5 min or more, mean bias was -0.20 [0.55] l/min. The method successfully indicated two cardiac arrest events, which were induced in one of the animals. The method satisfactorily tracked wide fluctuations in cardiac output in real time. The capnodynamic method may have potential for continuous noninvasive cardiac output monitoring in patients undergoing anesthesia for major surgery, and in critical care, on a routine basis.

Suppression of phase-noise interference due to closely spaced data and calibration signals

At high frequencies, phase noise, which occurs at frequencies surrounding a data frequency, may seriously interfere with the measurement of nearby signals. Our motivation for removing phase noise was based on our use of simultaneous data and calibration signals, which were closely spaced in frequency. We found that by measuring the source phase noise, we are able to effectively remove phase-noise interference from the measured data and calibration signals. In order to accomplish this phase-noise suppression, a normalization procedure has been developed so that signals on differing measurement channels can be compared. Using this phase-noise suppression procedure and a prototype measurement system, we were able to improve magnitude measurements by 36 dB. We were able to improve phase measurements by a factor of 70. We propose that this procedure can significantly improve measurement accuracy in many situations where two closely spaced signals, which have a common source, must be measured with high accuracy. This procedure can also be used to monitor, and thereby remove, other types of interference besides just phase noise.

Does sacral posterior rhizotomy suppress autonomic hyper-reflexia in patients with spinal cord injury?

To study the occurrence of autonomic hyper-reflexia (AHR) after intradural sacral posterior rhizotomy combined with intradural sacral anterior root stimulation, performed to manage the neurogenic hyper-reflexic bladder and to determine the pathophysiological basis of the uncontrolled hypertensive crisis after sacral de-afferentation. Ten patients with spinal cord injury operated using Brindley's method between September 1990 and February 1994 were reviewed. Systematic continuous non-invasive recordings of cardiovascular variables (using a photoplethysmograph) were made during urodynamic recordings and the pre- and post-operative vesico-urethral and cardiovascular data compared. Nine of the 10 patients were examined using a new prototype measurement system; one woman refused the last urodynamic assessment. Eight of the nine patients who presented with AHR before operation still had the condition afterward. There was a marked elevation in systolic and diastolic blood pressure during the urodynamic examination in all eight patients, despite complete intra-operative de-afferentation of the bladder in five. The elevation of blood pressure started during the stimulation-induced bladder contractions and increased during voiding in all cases. Five patients showed a decrease in heart rate during the increase in blood pressure. However, in three patients the heart rate did not change or even sometimes slightly increased as the arterial blood pressure exceeded 160 mmHg, when the blood pressure and heart rate then increased together. These results confirm that even after complete sacral de-afferentation. AHR persisted in patients with spinal cord injury and always occurred during the stimulation-induced voiding phase. In cases of incomplete de-afferentation, small uninhibited bladder contractions without voiding occurred during the filling phase. The blood pressure then increased but never reached the value recorded during stimulation-induced micturition. Stimulation of afferents that enter the spinal cord by the thoracic and lumbar roots and that are not influenced by sacral rhizotomy could explain why AHR increases during urine flow. The distinct threshold of decreased heart rate by increasing blood pressure to > 160 mmHg focuses attention on the chronotropic influences of the sympathetic nerves in the heart by an exhausted baroreceptor reflex.

An electro-optic-based RMS voltage measurement techniquea)

A new electro-optic-based technique for measuring the rms value of an applied voltage is presented. The technique incorporates a ratiometric method whereby the requirement for absolute laser power information is unnecessary. Description, analysis, and experimental results of the prototype measurement system are presented.

Range image acquisition with a single binary-encoded light pattern

The problem of strike identification in range image acquisition systems based on triangulation with periodically structured illumination is discussed. A coding scheme is presented based on a single fixed binary encoded illumination pattern, which contains all the information required to identify the individual strikes visible in the camera image. Every sample point indicated by the light pattern is made identifiable by means of a binary signature, which is locally shared among its closest neighbors. The applied code is derived from pseudonoise sequences, and it is optimized so that it can make the identification fault-tolerant to the largest extent. A prototype measurement system based on this coding principle is presented. Experimental results obtained with the measurement system are also presented. >

An In-Process Measurement Technique Using Laser for Non-Contact Monitoring of Surface Roughness and Form Accuracy of Ground Surfaces

Summary An optical in-process technique using laser for non-contact measurement of roughness and form accuracy of a ground surface is presented. Form accuracy is measured based on a triangulation method using a photodiode array, while surface roughness is monitored by analysing the radiational pattern of a laser beam from the surface. Detailed design aspects of a prototype measurement system built fully utilising modern opto-electronic instruments and its experimental results are discussed.

An instrumentation system to measure user performance in interactive systems

Many software tools are interactive in nature and require a close match between the user's knowledge of how a task is to be performed and the capabilities the tool provides. This paper describes the current status of an instrumentation and analysis package to measure user performance in an interactive system. A prototype measurement system is considered to evaluate a screen editor and to develop models of user behavior.