An optical sensor for local strain measuring of an object by means of a speckle correlation method

Czech Academy of Sciences Publication Activity Database

Horváth, P.; Šmíd, Petr; Hrabovský, M.; Hamarová, Ivana

2012-01-01

Roč. 106, s3 (2012), s. 425-427 ISSN 0009-2770 R&D Projects: GA AV ČR KAN301370701 Institutional research plan: CEZ:AV0Z10100521 Keywords : non-contact measurement * strain * speckle * speckle correlation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.453, year: 2012

Proceedings of the Second Noncontact Temperature Measurement Workshop

Science.gov (United States)

Hale, Robert R. (Editor)

1989-01-01

The state of the art in noncontact temperature measurement (NCTM) technology was reviewed and the NCTM requirements of microgravity materials processing community identified. The workshop included technical presentations and discussions which ranged from research on advanced concepts for temperature measurement to laboratory research and development regarding measurement principles and state-of-the-art engineering practices for NCTM methodology in commercial and industrial applications. Technical presentations were made concerning: NCTM needs as perceived by several NASA centers, recent ground-based NCT, research and development of industry, NASA, academia, and selected national laboratories, work-in-progress communication, and technical issues of the implementation of temperature measurement in the space environment to facilitate future U.S. materials science investigations.

An investigation of highly accurate and precise robotic hole measurements using non-contact devices

Directory of Open Access Journals (Sweden)

Usman Zahid

2016-01-01

Full Text Available Industrial robots arms are widely used in manufacturing industry because of their support for automation. However, in metrology, robots have had limited application due to their insufficient accuracy. Even using error compensation and calibration methods, robots are not effective for micrometre (μm level metrology. Non-contact measurement devices can potentially enable the use of robots for highly accurate metrology. However, the use of such devices on robots has not been investigated. The research work reported in this paper explores the use of different non-contact measurement devices on an industrial robot. The aim is to experimentally investigate the effects of robot movements on the accuracy and precision of measurements. The focus has been on assessing the ability to accurately measure various geometric and surface parameters of holes despite the inherent inaccuracies of industrial robot. This involves the measurement of diameter, roundness and surface roughness. The study also includes scanning of holes for measuring internal features such as start and end point of a taper. Two different non-contact measurement devices based on different technologies are investigated. Furthermore, effects of eccentricity, vibrations and thermal variations are also assessed. The research contributes towards the use of robots for highly accurate and precise robotic metrology.

Comparison of intraocular pressure measurements with the portable PT100 noncontact tonometer and goldmann applanation tonometry.

Science.gov (United States)

Salim, Sarwat; Linn, Daniel J; Echols, James R; Netland, Peter A

2009-01-01

Noncontact tonometers are useful when regulations preclude use of contact tonometers by medical students and other nonophthalmologists. Our study compared the measurements by the portable, noncontact tonometer (PT100) with Goldmann applanation tonometry (GAT). This was a prospective study of 98 eyes from 98 patients. Intraocular pressure (IOP) was measured by GAT and the PT100 (Reichert, Buffalo, NY). Mean IOP measurements showed no significant differences in measurements performed by the two tonometers (P = 0.64). Measurements by the two tonometers were in agreement by tonometer provides IOP measurements comparable to GAT within the normal range of IOP.

PREFACE: Non-contact AFM Non-contact AFM

Science.gov (United States)

Giessibl, Franz J.; Morita, Seizo

2012-02-01

This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of these conferences are a useful source of information, several key developments warrant devoting a special issue to this subject. In the theoretic field, the possibility of supplementing established techniques such as scanning tunneling microscopy (STM) and Kelvin probe microscopy with atomically resolved force micrsoscopy poses many challenges in the calculation of contrast and contrast reversal. The surface science of insulators, self-assembled monolayers and adsorbates on insulators is a fruitful field for the application of non-contact AFM: several articles in this issue are devoted to these subjects. Atomic imaging and manipulation have been pioneered using STM, but because AFM allows the measurement of forces, AFM has had a profound impact in this field as well. Three-dimensional force spectroscopy has allowed many important insights into surface science. In this issue a combined 3D tunneling and force microscopy is introduced. Non-contact AFM typically uses frequency modulation to measure force gradients and was initially used mainly in a vacuum. As can be seen in this issue, frequency modulation is now also used in ambient conditions, allowing better spatial and force resolution. We thank all of the contributors for their time and efforts in making this special issue possible. We are also very grateful to the staff of IOP Publishing for handling the administrative aspects and for steering the refereeing process. Non-contact AFM contents Relation between the chemical force and the tunnelling current in atomic point contacts: a simple model Pavel Jelínek, Martin Ondrácek and Fernando Flores Theoretical simulation of

Progress of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting Radial Growth on a Rotating Disk

Science.gov (United States)

Clem, Michelle M.; Abdul-Aziz, Ali; Woike, Mark R.; Fralick, Gustave C.

2015-01-01

The modern turbine engine operates in a harsh environment at high speeds and is repeatedly exposed to combined high mechanical and thermal loads. The cumulative effects of these external forces lead to high stresses and strains on the engine components, such as the rotating turbine disks, which may eventually lead to a catastrophic failure if left undetected. The operating environment makes it difficult to use conventional strain gauges, therefore, non-contact strain measurement techniques is of interest to NASA and the turbine engine community. This presentation describes one such approach; the use of cross correlation analysis to measure strain experienced by the engine turbine disk with the goal of assessing potential faults and damage.

Strain sensing systems tailored for tensile measurement of fragile wires

Science.gov (United States)

Nyilas, Arman

2005-12-01

Fundamental stress versus strain measurements were completed on superconducting Nb3Sn wires within the framework of IEC/TC90 and VAMAS/TWA16. A key task was the assessment of sensing systems regarding resolution, accuracy, and precision when measuring Young's modulus. Prior to actual Nb3Sn wire measurements metallic wires, consisting of copper and stainless steel having diameters similar to the Nb3Sn wire, were extensively investigated with respect to their elastic line properties using different types of extensometers. After these calibration tests Nb3Sn wire measurements of different companies resulted in several important facts with respect to total size and weight of the used extensometers. The size could be correlated to the initial stage of stress versus strain behaviour. In fact, the effect of wire curls resulting from the production line had a profound effect on Young's modulus measurements. Within this context, the possibility of determining Young's modulus from unloading compliance lines in the plastic regime of the stress-strain curve was considered. The data obtained using this test methodology were discussed under consideration of the composite nature of Nb3Sn wire. In addition, a non-contacting sensing system based on a double-beam laser extensometer was used to investigate the potential of this new sensing system.

Strain sensing systems tailored for tensile measurement of fragile wires

International Nuclear Information System (INIS)

Nyilas, Arman

2005-01-01

Fundamental stress versus strain measurements were completed on superconducting Nb 3 Sn wires within the framework of IEC/TC90 and VAMAS/TWA16. A key task was the assessment of sensing systems regarding resolution, accuracy, and precision when measuring Young's modulus. Prior to actual Nb 3 Sn wire measurements metallic wires, consisting of copper and stainless steel having diameters similar to the Nb 3 Sn wire, were extensively investigated with respect to their elastic line properties using different types of extensometers. After these calibration tests Nb 3 Sn wire measurements of different companies resulted in several important facts with respect to total size and weight of the used extensometers. The size could be correlated to the initial stage of stress versus strain behaviour. In fact, the effect of wire curls resulting from the production line had a profound effect on Young's modulus measurements. Within this context, the possibility of determining Young's modulus from unloading compliance lines in the plastic regime of the stress-strain curve was considered. The data obtained using this test methodology were discussed under consideration of the composite nature of Nb 3 Sn wire. In addition, a non-contacting sensing system based on a double-beam laser extensometer was used to investigate the potential of this new sensing system

Non-Contact Conductivity Measurement for Automated Sample Processing Systems

Science.gov (United States)

Beegle, Luther W.; Kirby, James P.

2012-01-01

A new method has been developed for monitoring and control of automated sample processing and preparation especially focusing on desalting of samples before analytical analysis (described in more detail in Automated Desalting Apparatus, (NPO-45428), NASA Tech Briefs, Vol. 34, No. 8 (August 2010), page 44). The use of non-contact conductivity probes, one at the inlet and one at the outlet of the solid phase sample preparation media, allows monitoring of the process, and acts as a trigger for the start of the next step in the sequence (see figure). At each step of the muti-step process, the system is flushed with low-conductivity water, which sets the system back to an overall low-conductivity state. This measurement then triggers the next stage of sample processing protocols, and greatly minimizes use of consumables. In the case of amino acid sample preparation for desalting, the conductivity measurement will define three key conditions for the sample preparation process. First, when the system is neutralized (low conductivity, by washing with excess de-ionized water); second, when the system is acidified, by washing with a strong acid (high conductivity); and third, when the system is at a basic condition of high pH (high conductivity). Taken together, this non-contact conductivity measurement for monitoring sample preparation will not only facilitate automation of the sample preparation and processing, but will also act as a way to optimize the operational time and use of consumables

Comparison of intraocular pressure measurement with Scheimpflug-based noncontact tonometer with and without hydrogel contact lenses.

Science.gov (United States)

Kumar, Mukesh; Shetty, Rohit; Jayadev, Chaitra; Dutta, Debarun; Nicolsan, Maneck D; Nagaraj, Sriharsha; Kumar, Rajesh S

2015-04-01

The objective was to determine the repeatability of intraocular pressure (IOP) measurements made through a soft contact lens (CL) using the Scheimpflug noncontact tonometry in healthy subjects. This prospective, randomized, single-center study included one eye of 88 subjects (40 male and 48 female). Only participants without glaucoma or any other ocular pathology were included in this study. Three consecutive IOP measurements by the Scheimpflug noncontact tonometry were performed with and without daily disposable hydrogel CLs (-0.50 DS) (Dailies-nelfilcon A, 69% water, 8.7 mm base curve, 14 mm diameter, center thickness 0.10 mm) by a single operator. To avoid any bias arising from diurnal variation, all measurements were made at a similar time of day (11 am ± 1 h). The repeatability of IOP measurements using the Scheimpflug noncontact tonometry with and without CLs was evaluated using Pearson's correlation analysis. Bland-Altman plotting was used to assess the limits of agreement between the measurements with and without CLs. The mean (± standard deviation) IOPs with and without CL were 13.80 ± 2.70 and 13.79 ± 2.54 mm of Hg respectively. The mean difference was 0.01 ± 0.16 (95% confidence interval, +1.97 to - 2.00) mm Hg. Statistical analysis via paired t-test showed no statistical difference between the two groups with (P = 0.15). A good correlation was found for IOP measurements with and without CL (r = 0.93, P < 0.001). Good test-retest reliability was found when IOP was measured with and without CL. There was no significant difference between IOP measured with and without CLs by Scheimpflug noncontact tonometry.

Noncontact vibration measurements using magnetoresistive sensing elements

Science.gov (United States)

Tomassini, R.; Rossi, G.

2016-06-01

Contactless instrumentations is more and more used in turbomachinery testing thanks to the non-intrusive character and the possibility to monitor all the components of the machine at the same time. Performances of blade tip timing (BTT) measurement systems, used for noncontact turbine blade vibration measurements, in terms of uncertainty and resolution are strongly affected by sensor characteristics and processing methods. The sensors used for BTT generate pulses, used for precise measurements of turbine blades time of arrival. Nowadays proximity sensors used in this application are based on optical, capacitive, eddy current and microwave measuring principle. Pressure sensors has been also tried. This paper summarizes the results achieved using a novel instrumentation based on the magnetoresistive sensing elements. The characterization of the novel probe has been already published. The measurement system was validated in test benches and in a real jet-engine comparing different sensor technologies. The whole instrumentation was improved. The work presented in this paper focuses on the current developments. In particular, attention is given to the data processing software and new sensor configurations.

[Effect of intraocular pressure measurement through therapeutic soft contact lenses by noncontact tonometer].

Science.gov (United States)

Sugimoto-Takeuchi, R; Yamamoto, R; Kuwayama, Y; Kinoshita, S

1991-09-01

The measurement of intraocular pressure (IOP) was compared with and without soft contact lenses by a non-contact tonometer. The soft contact lenses examined were Plano-T and Plano-B4 therapeutic contact lenses and Breath-O refractive lens. Twenty-nine eyes of 18 patients with an IOP ranging from 9 to 48mmHg were studied. The measurements of IOP were 19.7 +/- 8.6mmHg with Plano-T and 18.9 +/- 9.2mmHg with Plano-B4. Both numbers were not statistically different, when compared with controls (19.3 +/- 9.8mmHg without lens). There was, however, a significant difference significant difference with (44.7 +/- 10.7mmHg) and without the Breath-O (p less than 0.01). The results suggest that accurate IOP measurements can be obtained through therapeutic soft contact lens by a non-contact tonometer.

Soft tissue strain measurement using an optical method

Science.gov (United States)

Toh, Siew Lok; Tay, Cho Jui; Goh, Cho Hong James

2008-11-01

Digital image correlation (DIC) is a non-contact optical technique that allows the full-field estimation of strains on a surface under an applied deformation. In this project, the application of an optimized DIC technique is applied, which can achieve efficiency and accuracy in the measurement of two-dimensional deformation fields in soft tissue. This technique relies on matching the random patterns recorded in images to directly obtain surface displacements and to get displacement gradients from which the strain field can be determined. Digital image correlation is a well developed technique that has numerous and varied engineering applications, including the application in soft and hard tissue biomechanics. Chicken drumstick ligaments were harvested and used during the experiments. The surface of the ligament was speckled with black paint to allow for correlation to be done. Results show that the stress-strain curve exhibits a bi-linear behavior i.e. a "toe region" and a "linear elastic region". The Young's modulus obtained for the toe region is about 92 MPa and the modulus for the linear elastic region is about 230 MPa. The results are within the values for mammalian anterior cruciate ligaments of 150-300 MPa.

A high-stability non-contact dilatometer for low-amplitude temperature-modulated measurements

Energy Technology Data Exchange (ETDEWEB)

Luckabauer, Martin; Sprengel, Wolfgang; Würschum, Roland [Institute of Materials Physics, Graz University of Technology, A-8010 Graz (Austria)

2016-07-15

Temperature modulated thermophysical measurements can deliver valuable insights into the phase transformation behavior of many different materials. While especially for non-metallic systems at low temperatures numerous powerful methods exist, no high-temperature device suitable for modulated measurements of bulk metallic alloy samples is available for routine use. In this work a dilatometer for temperature modulated isothermal and non-isothermal measurements in the temperature range from room temperature to 1300 K is presented. The length measuring system is based on a two-beam Michelson laser interferometer with an incremental resolution of 20 pm. The non-contact measurement principle allows for resolving sinusoidal length change signals with amplitudes in the sub-500 nm range and physically decouples the length measuring system from the temperature modulation and heating control. To demonstrate the low-amplitude capabilities, results for the thermal expansion of nickel for two different modulation frequencies are presented. These results prove that the novel method can be used to routinely resolve length-change signals of metallic samples with temperature amplitudes well below 1 K. This high resolution in combination with the non-contact measurement principle significantly extends the application range of modulated dilatometry towards high-stability phase transformation measurements on complex alloys.

ChemCam-like Spectrometer for Non-Contact Measurements of Key Isotopes, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — This project addresses the need for a non-contact instrument capable of measuring the isotopic ratios O-18/O-16 and D/H from water ice and other solid materials...

Comparison of intraocular pressure measurement with Scheimpflug-based noncontact tonometer with and without hydrogel contact lenses

Directory of Open Access Journals (Sweden)

Mukesh Kumar

2015-01-01

Full Text Available Objectives: The objective was to determine the repeatability of intraocular pressure (IOP measurements made through a soft contact lens (CL using the Scheimpflug noncontact tonometry in healthy subjects. Methods: This prospective, randomized, single-center study included one eye of 88 subjects (40 male and 48 female. Only participants without glaucoma or any other ocular pathology were included in this study. Three consecutive IOP measurements by the Scheimpflug noncontact tonometry were performed with and without daily disposable hydrogel CLs (−0.50 DS (Dailies-nelfilcon A, 69% water, 8.7 mm base curve, 14 mm diameter, center thickness 0.10 mm by a single operator. To avoid any bias arising from diurnal variation, all measurements were made at a similar time of day (11 am ± 1 h. The repeatability of IOP measurements using the Scheimpflug noncontact tonometry with and without CLs was evaluated using Pearson′s correlation analysis. Bland-Altman plotting was used to assess the limits of agreement between the measurements with and without CLs. Results: The mean (± standard deviation IOPs with and without CL were 13.80 ± 2.70 and 13.79 ± 2.54 mm of Hg respectively. The mean difference was 0.01 ± 0.16 (95% confidence interval, +1.97 to − 2.00 mm Hg. Statistical analysis via paired t-test showed no statistical difference between the two groups with (P = 0.15. A good correlation was found for IOP measurements with and without CL (r = 0.93, P < 0.001. Good test-retest reliability was found when IOP was measured with and without CL. Conclusion: There was no significant difference between IOP measured with and without CLs by Scheimpflug noncontact tonometry.

Contact and non-contact ultrasonic measurement in the food industry: a review

International Nuclear Information System (INIS)

Mohd Khairi, Mohd Taufiq; Ibrahim, Sallehuddin; Md Yunus, Mohd Amri; Faramarzi, Mahdi

2016-01-01

The monitoring of the food manufacturing process is vital since it determines the safety and quality level of foods which directly affect the consumers’ health. Companies which produce high quality products will gain trust from consumers. This factor helps the companies to make profits. The use of efficient and appropriate sensors for the monitoring process can also reduce cost. The food assessing process based on an ultrasonic sensor has attracted the attention of the food industry due to its excellent capabilities in several applications. The utilization of low or high frequencies for the ultrasonic transducer has provided an enormous benefit for analysing, modifying and guaranteeing the quality of food. The contact and non-contact ultrasonic modes for measurement also contributed significantly to the food processing. This paper presents a review of the application of the contact and non-contact mode of ultrasonic measurement focusing on safety and quality control areas. The results from previous researches are shown and elaborated. (topical review)

Contact and non-contact ultrasonic measurement in the food industry: a review

Science.gov (United States)

Taufiq Mohd Khairi, Mohd; Ibrahim, Sallehuddin; Yunus, Mohd Amri Md; Faramarzi, Mahdi

2016-01-01

The monitoring of the food manufacturing process is vital since it determines the safety and quality level of foods which directly affect the consumers’ health. Companies which produce high quality products will gain trust from consumers. This factor helps the companies to make profits. The use of efficient and appropriate sensors for the monitoring process can also reduce cost. The food assessing process based on an ultrasonic sensor has attracted the attention of the food industry due to its excellent capabilities in several applications. The utilization of low or high frequencies for the ultrasonic transducer has provided an enormous benefit for analysing, modifying and guaranteeing the quality of food. The contact and non-contact ultrasonic modes for measurement also contributed significantly to the food processing. This paper presents a review of the application of the contact and non-contact mode of ultrasonic measurement focusing on safety and quality control areas. The results from previous researches are shown and elaborated.

Non-contact measurement of rotation angle with solo camera

Science.gov (United States)

Gan, Xiaochuan; Sun, Anbin; Ye, Xin; Ma, Liqun

2015-02-01

For the purpose to measure a rotation angle around the axis of an object, a non-contact rotation angle measurement method based on solo camera was promoted. The intrinsic parameters of camera were calibrated using chessboard on principle of plane calibration theory. The translation matrix and rotation matrix between the object coordinate and the camera coordinate were calculated according to the relationship between the corners' position on object and their coordinates on image. Then the rotation angle between the measured object and the camera could be resolved from the rotation matrix. A precise angle dividing table (PADT) was chosen as the reference to verify the angle measurement error of this method. Test results indicated that the rotation angle measurement error of this method did not exceed +/- 0.01 degree.

Long wavelength infrared radiation thermometry for non-contact temperature measurements in gas turbines

Science.gov (United States)

Manara, J.; Zipf, M.; Stark, T.; Arduini, M.; Ebert, H.-P.; Tutschke, A.; Hallam, A.; Hanspal, J.; Langley, M.; Hodge, D.; Hartmann, J.

2017-01-01

The objective of the EU project "Sensors Towards Advanced Monitoring and Control of Gas Turbine Engines (acronym STARGATE)" is the development of a suite of advanced sensors, instrumentation and related systems in order to contribute to the developing of the next generation of green and efficient gas turbine engines. One work package of the project deals with the design and development of a long wavelength infrared (LWIR) radiation thermometer for the non-contact measurement of the surface temperature of thermal barrier coatings (TBCs) during the operation of gas turbine engines. For opaque surfaces (e.g. metals or superalloys) radiation thermometers which are sensitive in the near or short wavelength infrared are used as state-of-the-art method for non-contact temperature measurements. But this is not suitable for oxide ceramic based TBCs (e.g. partially yttria stabilized zirconia) as oxide ceramics are semi-transparent in the near and short wavelength infrared spectral region. Fortunately the applied ceramic materials are non-transparent in the long wavelength infrared and additionally exhibit a high emittance in this wavelength region. Therefore, a LWIR pyrometer can be used for non-contact temperature measurements of the surfaces of TBCs as such pyrometers overcome the described limitation of existing techniques. For performing non-contact temperature measurements in gas turbines one has to know the infrared-optical properties of the applied TBCs as well as of the hot combustion gas in order to properly analyse the measurement data. For reaching a low uncertainty on the one hand the emittance of the TBC should be high (>0.9) in order to reduce reflections from the hot surrounding and on the other hand the absorbance of the hot combustion gas should be low (<0.1) in order to decrease the influence of the gas on the measured signal. This paper presents the results of the work performed by the authors with focus on the implementation of the LWIR pyrometer and the

[Comparative pressure measurements with the non-contact tonometer and the Goldmann applanation tonometer].

Science.gov (United States)

Langmann, G; Schuhmann, G; Schwaiger, W

1985-11-01

The intraocular pressure of 400 patients was measured with both the Non-Contact Tonometer II (NCT II) and the Goldmann applanation tonometer (GAT) and was statistically evaluated. The clinical experience gained, as well as advantages and limitations in application, are discussed.

Analysis of a non-contact magnetoelastic torque transducer

International Nuclear Information System (INIS)

Andreescu, R.; Spellman, B.; Furlani, E.P.

2008-01-01

Results are presented for the performance of a magnetoelastic torque transducer that converts a torque-induced strain in a non-magnetic shaft into changes in a measurable magnetic field. The magnetic field is generated by a thin magnetostrictive layer that is coated onto the circumference of the shaft. The layer is magnetized and has an initial residual strain. The magnetization within the layer rotates in response to changes in the strain which occur when the shaft is torqued. The magnetic field produced by the layer changes with the magnetization and this can be sensed by a magnetometer to monitor the torque on the shaft. In this paper, a phenomenological theory is developed for predicting the performance of the transducer. The theory can be used to predict the magnetic field distribution of the transducer as a function of the physical properties of the magnetic coating, its residual strain, and the applied torque. It enables rapid parametric analysis of transducer performance, which is useful for the development and optimization of novel non-contact torque sensors

Noncontact ballistic motion measurement using a fiber-optic confocal sensor

International Nuclear Information System (INIS)

Shafir, E.; Berkovic, G.; Horovitz, Y.; Appelbaum, G.; Moshe, E.; Horovitz, E.; Skutelski, A.; Werdiger, M.; Perelmutter, L.; Sudai, M.

2007-01-01

A fiber-optic confocal sensor for noncontact ballistic measurements is described. Determination of motion at velocities of 1.7 km/s with an uncertainty as small as ±0.3% is demonstrated for both a projectile and a free-surface target. The fibers detect the passage of the object at their conjugate image points created by low F/ optics. This results in an output signal comprising a train of sharp pulses each precisely identifying when the ballistic object traverses an image point. Since the ballistic object does not contact the sensor at the time of imaging, the measurements do not perturb the motion, enabling multi-fragment measurement, as well as repetitive measurements of the same object point

Measuring Pulse Rate Variability using Long-Range, Non-Contact Imaging Photoplethysmography

Science.gov (United States)

2016-08-20

contains color . 14. ABSTRACT Camera-based measurement of the blood volume pulse via non-contact, imaging photoplethysmography is a very popular approach...ECG) for each window were calculated in beats per minute (bpm). The periodogram method with a Hamming window was used to estimate mean pulse...11 Hz. Independent component analysis (ICA) was then used to decompose the normalized, bandpass-filtered, color -channel signals into independent

Enhancement to Non-Contacting Stress Measurement of Blade Vibration Frequency

Science.gov (United States)

Platt, Michael; Jagodnik, John

2011-01-01

A system for turbo machinery blade vibration has been developed that combines time-of-arrival sensors for blade vibration amplitude measurement and radar sensors for vibration frequency and mode identification. The enabling technology for this continuous blade monitoring system is the radar sensor, which provides a continuous time series of blade displacement over a portion of a revolution. This allows the data reduction algorithms to directly calculate the blade vibration frequency and to correctly identify the active modes of vibration. The work in this project represents a significant enhancement in the mode identification and stress calculation accuracy in non-contacting stress measurement system (NSMS) technology when compared to time-of-arrival measurements alone.

The non-contact tonometer. Its value and limitations.

Science.gov (United States)

Shields, M B

1980-01-01

A review of the literature and a comparative study against Goldmann applanation tonometers suggest that the non-contact tonometer is reliable for measuring intraocular pressures within the normal range. In addition, the non-contact tonometer eliminates the need for corneal contact and topical anesthesia, thereby avoiding the potential problems of corneal abrasion, spread of infection, and drug reactions. The instrument can be used reliably by paramedical personnel and has particular value in mass screening and possibly in studies of topical antiglaucoma drugs. The non-contact tonometer is less reliable in patients with elevated intraocular pressure, since comparative studies against the Goldmann applanation tonometers have shown poorer correlations in the higher pressure ranges. The instrument is also limited by an abnormal cornea or poor fixation, which may interfere with accurate pressure measurements. Furthermore, the non-contact tonometer is less portable than many tonometers and more expensive than most.

On repeated corneal applanation with the Goldmann and two non-contact tonometers.

Science.gov (United States)

Almubrad, Turki M; Ogbuehi, Kelechi C

2010-03-01

Several authors believe it is necessary to randomise the order in which contact and non-contact tonometers are used in comparison studies. This study was carried out to investigate the effect of repeated applanation on the measured intraocular pressure. One set of measurements per session was made on each of three sessions (one session per day) with the Goldmann and two non-contact tonometers (Topcon CT80 and Keeler Pulsair EasyEye), in a pre-determined order, on one randomly selected eye of 120 subjects randomised to one of two groups. For session one, only the non-contact tonometers were used to assess the intraocular pressure of both groups. For session two, either non-contact or Goldmann tonometry was performed first and this order was reversed for session 3. Average intraocular pressures were compared between sessions to determine the presence or absence of effects on the intraocular pressure caused by prior repeated applanation with the Goldmann or either one (or both) of the non-contact tonometers. Prior applanation with a non-contact tonometer did not cause a significant (p > 0.05) reduction of the mean pressure measured with either non-contact tonometer. The mean pressure was slightly but significantly (p contact tonometers in both subject groups) when non-contact tonometry was performed after Goldmann tonometry. There was no significant difference (p > 0.05) between the pressures measured with the Goldmann tonometer prior to and subsequent to non-contact tonometry, in both subject groups. A small but statistically significant reduction in the intraocular pressure was found following applanation with the Goldmann tonometer but not with either one of two non-contact tonometers.

Noncontact measurement of guided ultrasonic wave scattering for fatigue crack characterization

Science.gov (United States)

Fromme, P.

2013-04-01

Fatigue cracks can develop in aerospace structures at locations of stress concentration such as fasteners. For the safe operation of the aircraft fatigue cracks need to be detected before reaching a critical length. Guided ultrasonic waves offer an efficient method for the detection and characterization of fatigue cracks in large aerospace structures. Noncontact excitation of guided waves was achieved using electromagnetic acoustic transducers (EMAT). The transducers were developed for the specific excitation of the A0 Lamb mode. Based on the induced eddy currents in the plate a simple theoretical model was developed and reasonably good agreement with the measurements was achieved. However, the detection sensitivity for fatigue cracks depends on the location and orientation of the crack relative to the measurement locations. Crack-like defects have a directionality pattern of the scattered field depending on the angle of the incident wave relative to the defect orientation and on the ratio of the characteristic defect size to wavelength. The detailed angular dependency of the guided wave field scattered at crack-like defects in plate structures has been measured using a noncontact laser interferometer. Good agreement with 3D Finite Element simulation predictions was achieved for machined part-through and through-thickness notches. The amplitude of the scattered wave was quantified for a variation of angle of the incident wave relative to the defect orientation and the defect depth. These results provide the basis for the defect characterization in aerospace structures using guided wave sensors.

Measurement of stress strain and vibrational properties of tendons

Science.gov (United States)

Revel, Gian Marco; Scalise, Alessandro; Scalise, Lorenzo

2003-08-01

The authors present a new non-intrusive experimental procedure based on laser techniques for the measurement of mechanical properties of tendons. The procedure is based on the measurement of the first resonance frequency of the tendon by laser Doppler vibrometry during in vitro tensile experiments, with the final aim of establishing a measurement procedure to perform the mechanical characterization of tendons by extracting parameters such as the resonance frequency, also achievable during in vivo investigation. The experimental procedure is reported, taking into account the need to simulate the physiological conditions of the Achilles tendon, and the measurement technique used for the non-invasive determination of tendon cross-sectional area during tensile vibration tests at different load levels is described. The test procedure is based on a tensile machine, which measures longitudinal tendons undergoing controlled load conditions. Cross-sectional area is measured using a new non-contact procedure for the measurement of tendon perimeter (repeatability of 99% and accuracy of 2%). For each loading condition, vibration resonance frequency and damping, cross-sectional area and tensile force are measured, allowing thus a mechanical characterization of the tendon. Tendon stress-strain curves are reported. Stress-strain curves have been correlated to the first vibration resonance frequency and damping of the tendon measured using a single-point laser Doppler vibrometer. Moreover, experimental results have been compared with a theoretical model of a vibrating cord showing discrepancies. In vitro tests are reported, demonstrating the validity of the method for the comparison of different aged rabbit tendons.

Noncontact evaluation for interface states by photocarrier counting

Science.gov (United States)

Furuta, Masaaki; Shimizu, Kojiro; Maeta, Takahiro; Miyashita, Moriya; Izunome, Koji; Kubota, Hiroshi

2018-03-01

We have developed a noncontact measurement method that enables in-line measurement and does not have any test element group (TEG) formation. In this method, the number of photocarriers excited from the interface states are counted which is called “photocarrier counting”, and then the energy distribution of the interface states density (D it) is evaluated by spectral light excitation. In our previous experiment, the method used was a preliminary contact measurement method at the oxide on top of the Si wafer. We developed, at this time, a D it measurement method as a noncontact measurement with a gap between the probes and the wafer. The shallow trench isolation (STI) sidewall has more localized interface states than the region under the gate electrode. We demonstrate the noncontact measurement of trapped carriers from interface states using wafers of three different crystal plane orientations. The demonstration will pave the way for evaluating STI sidewall interface states in future studies.

Noncontact simultaneous dual wavelength photoplethysmography: A further step toward noncontact pulse oximetry

International Nuclear Information System (INIS)

Humphreys, Kenneth; Ward, Tomas; Markham, Charles

2007-01-01

We present a camera-based device capable of capturing two photoplethysmographic (PPG) signals at two different wavelengths simultaneously, in a remote noncontact manner. The system comprises a complementary metal-oxide semiconductor camera and dual wavelength array of light emitting diodes (760 and 880 nm). By alternately illuminating a region of tissue with each wavelength of light, and detecting the backscattered photons with the camera at a rate of 16 frames/wavelength s, two multiplexed PPG wave forms are simultaneously captured. This process is the basis of pulse oximetry, and we describe how, with the inclusion of a calibration procedure, this system could be used as a noncontact pulse oximeter to measure arterial oxygen saturation (S p O 2 ) remotely. Results from an experiment on ten subjects, exhibiting normal S p O 2 readings, that demonstrate the instrument's ability to capture signals from a range of subjects under realistic lighting and environmental conditions are presented. We compare the signals captured by the noncontact system to a conventional PPG signal captured concurrently from a finger, and show by means of a J. Bland and D. Altman [Lancet 327, 307 (1986); Statistician 32, 307 (1983)] test, the noncontact device to be comparable to a contact device as a monitor of heart rate. We highlight some considerations that should be made when using camera-based ''integrative'' sampling methods and demonstrate through simulation, the suitability of the captured PPG signals for application of existing pulse oximetry calibration procedures

Noncontact simultaneous dual wavelength photoplethysmography: A further step toward noncontact pulse oximetry

Science.gov (United States)

Humphreys, Kenneth; Ward, Tomas; Markham, Charles

2007-04-01

We present a camera-based device capable of capturing two photoplethysmographic (PPG) signals at two different wavelengths simultaneously, in a remote noncontact manner. The system comprises a complementary metal-oxide semiconductor camera and dual wavelength array of light emitting diodes (760 and 880nm). By alternately illuminating a region of tissue with each wavelength of light, and detecting the backscattered photons with the camera at a rate of 16frames/wavelengths, two multiplexed PPG wave forms are simultaneously captured. This process is the basis of pulse oximetry, and we describe how, with the inclusion of a calibration procedure, this system could be used as a noncontact pulse oximeter to measure arterial oxygen saturation (SpO2) remotely. Results from an experiment on ten subjects, exhibiting normal SpO2 readings, that demonstrate the instrument's ability to capture signals from a range of subjects under realistic lighting and environmental conditions are presented. We compare the signals captured by the noncontact system to a conventional PPG signal captured concurrently from a finger, and show by means of a J. Bland and D. Altman [Lancet 327, 307 (1986); Statistician 32, 307 (1983)] test, the noncontact device to be comparable to a contact device as a monitor of heart rate. We highlight some considerations that should be made when using camera-based "integrative" sampling methods and demonstrate through simulation, the suitability of the captured PPG signals for application of existing pulse oximetry calibration procedures.

Full area covered 3D profile measurement of special-shaped optics based on a new prototype non-contact profiler.

Science.gov (United States)

Du, Hui-Lin; Zhou, Zhao-Zhong; Sun, Ze-Qing; Ju, Bing-Feng; Xu, Shaoning; Sun, Anyu

2017-06-01

A new prototype non-contact profiler based on surface tracking has been specially developed. Surface tracking is carried out by a specially designed dual stage probe system with the aid of a four-Degree Of Freedom high-precision motion platform. The dual stage probe system keeps a short-range optical probe constantly tracking the surface by a self-developed voice coil motor servo, by which a wide measuring range of up to 10 mm is realized. The system performance evaluation including resolution, repeatability, and scanning speed proved the good capability of the new prototype non-contact profiler. To realize a full area covered 3D profile measurement of special-shaped optics within one scanning procedure, a signal intensity monitor integrated in the surface tracking controller is specially developed. In the experiment, a snip-single-corner-rectangular-shaped freeform surface was successfully measured over full area by the new non-contact profiler. This work provides an effective solution for 3D profile measurement of special-shaped optical surfaces over full reflecting area. Experimental results demonstrate that the proposed measuring system is of great significance in quality evaluation of optical surfaces.

Investigation of human body potential measured by a non-contact measuring system.

Science.gov (United States)

Ichikawa, Norimitsu

2016-12-07

A human body is occasionally electrified in a room. This charged object will be a source of electrostatic accidents, including the malfunction of electronic equipment. Hence, prevention of these accidents is required. Accidents occasionally occur, even though antistatic clothes and shoes are used. One of the causes for these accidents is that there is a lack of the preventive measures. This situation occurs when using, for example, unconductive wax. In this study, human body potential (voltage) is measured using a non-contact measuring system. An investigation of the human body's voltage when using this system is conducted. The result demonstrates that the voltage of a human body wearing antistatic clothes and shoes or light clothes and slippers exceeds a malfunctioning voltage of a microelectronics device when the body walks on floors. Thus, accidents may occur even if a human body wearing the antistatic clothes walks on flooring. These results will be useful in estimating determination whether electrostatic accidents occur or not.

New method of noncontact temperature measurement in on-line textile production

Science.gov (United States)

Cheng, Xianping; Song, Xing-Li; Deng, Xing-Zhong

1993-09-01

Based on the condition of textile production the method of infrared non-contact temperature measurement is adcpted in the heat-setting and drying heat-treatment process . This method is used to monitor the moving cloth. The temperature of the cloth is displayed rapidly and exactly. The principle of the temperature measurement is analysed theoretically in this paper. Mathematical analysis and calculation are used for introducing signal transmitting method. Adopted method of combining software with hardware the temperature is corrected and compensated with the aid of a single-chip microcomputer. The results of test indicate that the application of temperature measurement instrument provides reliable parameters in the quality control. And it is an important measure on improving the quality of products.

A non-contact shape measuring system using an artificial neural network

International Nuclear Information System (INIS)

Jeon, Woo Tae; Lee, Myung Chan; Koh, Duck Joon; Cho, Hyung Suck

1996-01-01

We developed a non-contact shape measuring device using computer image processing technology. We present a method of calibrating a CCD video camera and a laser range finder which is the most important step toward making an accurate shape measuring system. An artificial neural network is used for the calibration. Our measurement system is composed of a semiconductor laser, a CCD video camera, a personal computer, and a linear motion table. We think that the developed system could be used for measuring the change in shape of the spent nuclear fuel rod before and after irradiation which is one of the most important tasks for developing a better nuclear fuel. A radiation shield is suggested for the possible utilization of the range finder in radioactive environment

Non-contact ultrasound techniques

International Nuclear Information System (INIS)

Khazali Mohd Zin

2001-01-01

Non-contact ultrasound plays significant role in material characterisation and inspection. Unlike conventional ultrasonic techniques, non-contact ultrasonic is mostly applicable to areas where the former has its weaknesses and limitations. It is interesting to note that the non-contact ultrasonic technique has an important significant application in industry. The technique is signified by the fact that the object to be inspected is further away from the ultrasonic source, no couplant is needed and inconsistent pressure between the transducer and the specimen can be eliminated. The paper discusses some of the non-contact ultrasound technique and its applications. (Author)

Procedure of non-contacting local mass density and mass density distribution measurements

International Nuclear Information System (INIS)

Menzel, M.; Winkler, K.

1985-01-01

The invention has been aimed at a procedure of non-contacting local mass density and/or mass density distribution measurements i.e. without the interfering influence of sensors or probes. It can be applied to installations, apparatuses and pipings of chemical engineering, to tank constructions and transportation on extreme temperature and/or pressure conditions and aggressive media influences respectively. The procedure has utilized an ionizing quantum radiation whereby its unknown weakening and scattering is compensated by a suitable combination of scattering and transmission counter rate measurements in such a way that the local mass densities and the mass density distribution respectively are determinable

Experimental technologies comparison for strain measurement of a composite main landing gear bay specimen

Science.gov (United States)

Viscardi, Massimo; Arena, Maurizio; Ciminello, Monica; Guida, Michele; Meola, Carosena; Cerreta, Pietro

2018-03-01

The development of advanced monitoring system for strain measurements on aeronautical components remain an important target both when related to the optimization of the lead-time and cost for part validation, allowing earlier entry into service, and when related to the implementation of advanced health monitoring systems dedicated to the in-service parameters verification and early stage detection of structural problems. The paper deals with the experimental testing of a composite samples set of the main landing gear bay for a CS-25 category aircraft, realized through an innovative design and production process. The test have represented a good opportunity for direct comparison of different strain measurement techniques: Strain Gauges (SG) and Fibers Bragg Grating (FBG) have been used as well as non-contact techniques, specifically the Digital Image Correlation (DIC) and Infrared (IR) thermography applied where possible in order to highlight possible hot-spot during the tests. The crucial points identification on the specimens has been supported by means of advanced finite element simulations, aimed to assessment of the structural strength and deformation as well as to ensure the best performance and the global safety of the whole experimental campaign.

New strain measurement method at axial tensile test of thin films through direct imaging

Energy Technology Data Exchange (ETDEWEB)

Ha, Jong-Eun [Department of Automotive Engineering, Seoul National Uinversity of Technolgy, 172 Gongneung-2 Dong, Nowon-Gu, Seoul (Korea, Republic of); Park, Jun-Hyub [Department of Mechatronics Engineering, College of Engineering, Tongmyong University, 535, Yongdang-Dong, Nam-Gu, Busan 608-711 (Korea, Republic of); Kang, Dong-Joong [School of Mechanical Eng., Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)], E-mail: jhyubpark@korea.com

2008-09-07

This paper proposes a new method for measuring strain during a tensile test of the specimen with micrometre size through direct imaging. A specimen was newly designed for adoption of direct imaging which was the main contribution of the proposed system. The structure of the specimen has eight indicators that make it possible to adopt direct imaging and it is fabricated using the same process of microelectromechanical system (MEMS) devices to guarantee the feasibility of the tensile test. We implemented a system for non-contact in situ measurement of strain with the specimen, the image-based displacement measurement system. Extension of the gauge length in the specimen could be found robustly by computing the positions of the eight rectangular-shape indicators on the image. Also, for an easy setup procedure, the region of interest was found automatically through the analysis of the edge projection profile along the horizontal direction. To gain confidence in the reliability of the system, the tensile test for the Al-3%Ti thin film was performed, which is widely used as a material in MEMS devices. Tensile tests were performed and displacements were measured using the proposed method and also the capacitance type displacement sensor for comparison. It is demonstrated that the new strain measurement system can be effectively used in the tensile test of the specimen at microscale with easy setup and better accuracy.

[Correlation between Goldmann and non-contact tonometry based on corneal thickness].

Science.gov (United States)

Schepens, G; Urier, N; Bechetoille, A; De Potter, P

2001-01-01

In this transversal study, we measure the intra ocular pressure by means of the Goldmann tonometer and a Non-Contact tonometer along with the central cornea thickness in 136 eyes of 73 patients. The statistical analysis of the collected data doesn't allow us to establish a correlation between the variation of the corneal thickness and the difference between the Goldmann tonometer and Non-Contact tonometer measures. The relative precision of the Non-Contact tonometer compared with the Goldmann tonometer doesn't seem influenced by the central cornea thickness.

A Vision-Based Sensor for Noncontact Structural Displacement Measurement

Science.gov (United States)

Feng, Dongming; Feng, Maria Q.; Ozer, Ekin; Fukuda, Yoshio

2015-01-01

Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for real-time displacement extraction from video images. By simply adjusting the upsampling factor, better subpixel resolution can be easily achieved to improve the measurement accuracy. The performance of the vision sensor is first evaluated through a laboratory shaking table test of a frame structure, in which the displacements at all the floors are measured by using one camera to track either high-contrast artificial targets or low-contrast natural targets on the structural surface such as bolts and nuts. Satisfactory agreements are observed between the displacements measured by the single camera and those measured by high-performance laser displacement sensors. Then field tests are carried out on a railway bridge and a pedestrian bridge, through which the accuracy of the vision sensor in both time and frequency domains is further confirmed in realistic field environments. Significant advantages of the noncontact vision sensor include its low cost, ease of operation, and flexibility to extract structural displacement at any point from a single measurement. PMID:26184197

Development of a baby friendly non-contact method for measuring vital signs: First results of clinical measurements in an open incubator at a neonatal intensive care unit

Science.gov (United States)

Klaessens, John H.; van den Born, Marlies; van der Veen, Albert; Sikkens-van de Kraats, Janine; van den Dungen, Frank A.; Verdaasdonk, Rudolf M.

2014-02-01

For infants and neonates in an incubator vital signs, such as heart rate, breathing, skin temperature and blood oxygen saturation are measured by sensors and electrodes sticking to the skin. This can damage the vulnerable skin of neonates and cause infections. In addition, the wires interfere with the care and hinder the parents in holding and touching the baby. These problems initiated the search for baby friendly 'non-contact' measurement of vital signs. Using a sensitive color video camera and specially developed software, the heart rate was derived from subtle repetitive color changes. Potentially also respiration and oxygen saturation could be obtained. A thermal camera was used to monitor the temperature distribution of the whole body and detect small temperature variations around the nose revealing the respiration rate. After testing in the laboratory, seven babies were monitored (with parental consent) in the neonatal intensive care unit (NICU) simultaneously with the regular monitoring equipment. From the color video recordings accurate heart rates could be derived and the thermal images provided accurate respiration rates. To correct for the movements of the baby, tracking software could be applied. At present, the image processing was performed off-line. Using narrow band light sources also non-contact blood oxygen saturation could be measured. Non-contact monitoring of vital signs has proven to be feasible and can be developed into a real time system. Besides the application on the NICU non-contact vital function monitoring has large potential for other patient groups.

Non-contact transportation using near-field acoustic levitation

Science.gov (United States)

Ueha; Hashimoto; Koike

2000-03-01

Near-field acoustic levitation, where planar objects 10 kg in weight can levitate stably near the vibrating plate, is successfully applied both to non-contact transportation of objects and to a non-contact ultrasonic motor. Transporting apparatuses and an ultrasonic motor have been fabricated and their characteristics measured. The theory of near-field acoustic levitation both for a piston-like sound source and a flexural vibration source is also briefly described.

Diffraction grating strain gauge method: error analysis and its application for the residual stress measurement in thermal barrier coatings

Science.gov (United States)

Yin, Yuanjie; Fan, Bozhao; He, Wei; Dai, Xianglu; Guo, Baoqiao; Xie, Huimin

2018-03-01

Diffraction grating strain gauge (DGSG) is an optical strain measurement method. Based on this method, a six-spot diffraction grating strain gauge (S-DGSG) system has been developed with the advantages of high and adjustable sensitivity, compact structure, and non-contact measurement. In this study, this system is applied for the residual stress measurement in thermal barrier coatings (TBCs) combining the hole-drilling method. During the experiment, the specimen’s location is supposed to be reset accurately before and after the hole-drilling, however, it is found that the rigid body displacements from the resetting process could seriously influence the measurement accuracy. In order to understand and eliminate the effects from the rigid body displacements, such as the three-dimensional (3D) rotations and the out-of-plane displacement of the grating, the measurement error of this system is systematically analyzed, and an optimized method is proposed. Moreover, a numerical experiment and a verified tensile test are conducted, and the results verify the applicability of this optimized method successfully. Finally, combining this optimized method, a residual stress measurement experiment is conducted, and the results show that this method can be applied to measure the residual stress in TBCs.

Non-Contact Thickness and Profile Measurements of Rolled Aluminium Strip Using EMAT

International Nuclear Information System (INIS)

Hobbis, A.; Aruleswaran, A.

2006-01-01

Accurate measurement of strip thickness is a very high priority for the aluminium rolled product industry. This paper presents the findings of trials to measure the thickness of aluminium strip using a send-receive, radially polarised Electromagnetic Acoustic Transducer (EMAT). A broadband EMAT system, developed at Warwick University, UK with a centre frequency of approximately 5 MHz and frequency content up to 12 MHz was used. The resultant ultrasonic waveforms have been processed using Fourier analysis. Static measurements of aluminium alloy samples in the thickness range between 0.28 mm to 2.8 mm have been measured using this non-contact approach at stand-offs of up to 2 mm. Measurements across the aluminium strip width to evaluate its profile for quality control was also carried out successfully. Some of the experiments and results obtained are described in detail

Development of an Image Colorimeter for Noncontact Skin Color Measurement and Application to the Dermatological Treatment

Science.gov (United States)

Akimoto, Makio; Chen, Yu; Miyazaki, Michio; Yamashita, Toyonobu; Miyakawa, Michio; Hata, Mieko

The skin is unique as an organ that is highly accessible to direct visual inspection with light. Visual inspection of cutaneous morphology is the mainstay of clinical dermatology, but relies heavily on subjective assessment by the skilled dermatologists. We present an imaging colorimeter of non-contact skin color measuring system and some experimented results using such instrument. The system is comprised by a video camera, light source, a real-time image processing board, magneto optics disk and personal computer which controls the entire system. The CIE-L*a*b* uniform color space is used. This system is used for monitoring of some clinical diagnosis. The instrument is non-contact, easy to operate, and has a high precision unlike the conventional colorimeters. This instrument is useful for clinical diagnoses, monitoring and evaluating the effectiveness of treatment.

Biometric Changes After Trabeculectomy with Contact and Non-contact Biometry.

Science.gov (United States)

Alvani, Azam; Pakravan, Mohammad; Esfandiari, Hamed; Yaseri, Mehdi; Yazdani, Shahin; Ghahari, Elham

2016-02-01

To compare biometric changes measured with contact and noncontact methods after mitomycin-C-augmented trabeculectomy. In this prospective study, 31 eyes from 31 glaucoma patients scheduled for primary trabeculectomy were enrolled. Biometric parameters including axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) were measured using contact ultrasound biometry (UD-6000 Ultrasonic A/B scanner biometer; Tomey Corporation, Nagoya, Japan) and a noncontact optical biometry device (Lenstar; Haag-Streit AG, Koeniz, Switzerland). Measurements were taken the day before trabeculectomy and then compared with measurements obtained 3 and 6 months after surgery. The AL and ACD were significantly decreased at 3 and 6 months compared with baseline values taken with each biometry method. There was a significant increase in LT measured by the Lenstar device at the 3- and 6-month follow-up. At both the 3- and 6-month follow-up, the mean AL measurement reduction with the Lenstar device was significantly lower than that of the A-scan ultrasound measurements. The mean ACD changes between the two devices were not significantly different. There is a small but significant decrease in the AL and ACD after trabeculectomy as measured with both the contact and noncontact methods. The amount of AL reduction measured is significantly smaller using the noncontact method, making it the preferable method for intraocular lens power calculation for patients who need cataract surgery combined with or after trabeculectomy. The LT measured by the Lenstar device increased significantly after the operation, which can be an early sign of the progression of cataractous changes after trabeculectomy.

A Review of Surface Deformation and Strain Measurement Using Two-Dimensional Digital Image Correlation

Directory of Open Access Journals (Sweden)

Khoo Sze-Wei

2016-09-01

Full Text Available Among the full-field optical measurement methods, the Digital Image Correlation (DIC is one of the techniques which has been given particular attention. Technically, the DIC technique refers to a non-contact strain measurement method that mathematically compares the grey intensity changes of the images captured at two different states: before and after deformation. The measurement can be performed by numerically calculating the displacement of speckles which are deposited on the top of object’s surface. In this paper, the Two-Dimensional Digital Image Correlation (2D-DIC is presented and its fundamental concepts are discussed. Next, the development of the 2D-DIC algorithms in the past 33 years is reviewed systematically. The improvement of 2DDIC algorithms is presented with respect to two distinct aspects: their computation efficiency and measurement accuracy. Furthermore, analysis of the 2D-DIC accuracy is included, followed by a review of the DIC applications for two-dimensional measurements.

Advances in Non-contact Measurement of Creep Properties

Science.gov (United States)

Hyers, Robert W.; Canepari, Stacy; Rogers, Jan. R.

2009-01-01

Our team has developed a novel approach to measuring creep at extremely high temperatures using electrostatic levitation (ESL). This method has been demonstrated on niobium up to 2300 C, while ESL has melted tungsten (3400 C). High-precision machined spheres of the sample are levitated in the NASA MSFC ESL, a national user facility, and heated with a laser. The laser is aligned off-center so that the absorbed photons transfer their momentum to the sample, causing it to rotate at up to 250,000+ RPM. The rapid rotation loads the sample through centripetal acceleration, causing it to deform. The deformation of the sample is captured on high-speed video, which is analyzed by machine-vision software from the University of Massachusetts. The deformations are compared to finite element models to determine the constitutive constants in the creep relation. Furthermore, the noncontact method exploits stress gradients within the sample to determine the stress exponent in a single test. This method was validated in collaboration with the University of Tennessee for niobium at 1985 C, with agreement within the uncertainty of the conventional measurements. A similar method is being employed on Ultra-High-Temperature ZrB2- SiC composites, which may see application in rocket nozzles and sharp leading edges for hypersonic vehicles.

Strain measurement technique

International Nuclear Information System (INIS)

1987-01-01

The 10 contributions are concerned with selected areas of application, such as strain measurements in wood, rubber/metal compounds, sets of strain measurements on buildings, reinforced concrete structures without gaps, pipes buried in the ground and measurements of pressure fluctuations. To increase the availability and safety of plant, stress analyses were made on gas turbine rotors with HT-DMS or capacitive HT-DMS (high temperature strain measurements). (DG) [de

A Study on non-contact measurements of laser-generated lamb waves

International Nuclear Information System (INIS)

Jang, Tae Seong; Lee, Jung Ju; Lee, Seung Seok

2002-01-01

Generation and detection of Lamb waves offer an effective non-destructive testing technique that will detect defects quickly and reliably. Lamb waves are generated in a thin plate by Q-switched Nd:YAG pulsed laser. Symmetric and antisymmetric Lamb modes in low-frequency-thickness regime are excited by illuminating a thin plate with an array of laser-generated line sources. The propagation of laser-generated Lamb waves is detected by measuring the out-of-plane displacements in a non-contact manner using the fiber optic Sagnac interferometer and all commercial adaptive reference-beam interferometer. The characteristics of laser-generated Lamb wave due to its frequency are investigated. Fundamental understanding of laser-generated Lamb modes is presented.

Noncontact Optical Fiber Sensor for Measuring the Refractive Index of Liquids

Directory of Open Access Journals (Sweden)

R. Selvas-Aguilar

2016-01-01

Full Text Available A noncontact optical fiber sensor for measuring the refractive index of transparent liquids is proposed. It operates by calculating the path of a focused laser beam at 635 nm that travels across the boundaries of a liquid sample. The optical power Fresnel reflections are detected and, subsequently, the refractive index is determined as the ratio between the traveled beam paths when the liquid is deposited versus a reference without the liquid sample. Additionally, a mathematical analysis of the geometrical case is included. The theoretical data from our sensor are in good agreement with the experimental results. The resolution achieved by the sensor is better than 10−3 RIU.

Influence of corneal thickness on comparative intraocular pressure measurements with Goldmann and non-contact tonometers in keratoconus.

Science.gov (United States)

Stabuc Silih, Mirna; Hawlina, Marko

2003-12-01

The influence of corneal thickness and curvature on the difference between intraocular pressure (IOP) measurements obtained with non-contact (NCT) and those with the Goldmann applanation tonometer (GAT) was studied in patients with keratoconus. We examined 113 patients with keratoconus. IOP was measured by the Canon TX 10 non-contact tonometer and the Goldmann tonometer, corneal curvature and thickness were obtained by Humphrey Automatic Refractometer Keratometer and Orbscan Version 3.0 Bausch & Lomb Surgical. The IOP measured by NCT was significantly lower than that measured by GAT. The mean pachymetry of the thinnest point was 423.15 +/- 98.43 microm for the right eyes and 426.7 +/- 93.88 microm for the left eyes. The difference between NCT-GAT and corneal thickness showed a significant negative correlation (r = - 0.427, p < 0.0001; t = - 3.677, p < 0.0001). Values of NCT measurements were significantly increasing with corneal thickness (F = 6.505, p < 0.0001 for right eyes and F = 4.37, p = 0.004 for left eyes), whilst GAT measurements did not show a significant influence of the corneal thickness. The keratometry had no effect on the difference between NCT-GAT measurements (t = 1.090, p = 0.278). The thin cornea has more influence on the measurement with NCT than GAT. The relative precision of NCT compared with GAT seems to be influenced by the corneal thickness.

Radiation thermometry - non-contact temperature measurements; Strahlungsthermometrie - Temperaturen beruehrungslos messen

Energy Technology Data Exchange (ETDEWEB)

Hollandt, J. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Fachbereich Hochtemperatur- und Vakuumphysik; Hartmann, J. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Arbeitsgruppe Hochtemperaturskala; Gutschwager, B. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Arbeitsgruppe Infrarot-Strahlungsthermometrie; Struss, O. [HEITRONICS Infrarot Messtechnik GmbH (Germany)

2007-09-15

The temperature is one of the measurands most frequently determined, as it decisively influences physical, chemical and biological processes. To be able to evaluate, optimize, repeat and compare industrial procedures, temperatures must be measured with sufficient accuracy and worldwide uniformity. This is done with the aid of the regulations and instructions of the international temperature scale. Today, non-contact measurements of surface temperatures can be performed without problems with radiation thermometers over a temperature range from -100 C up to 3000 C. Compared to contacting measurements, radiation-thermometric temperature measurement offers a series of advantages. Radiation thermometers react very fast and the measurement is not influenced by heat supply or dissipation. This allows objects to be measured which move very fast, are energized or may experience fast temperature changes. Consequently, radiation thermometry is increasingly used for the monitoring and control of thermal processes, for maintenance and in building services engineering. The present contribution shall inform of the fundamentals of radiation-thermometric temperature measurement as well as of the construction and popular types of radiation thermometers. It will be explained how exact and worldwide uniform temperature measurement is guaranteed via the international temperature scale and the calibration of radiation thermometers. The emissivity of surfaces which is important in practical temperature measurements and some examples of industrial applications of radiation thermometers will be described. (orig.)

Radiation thermometry - non-contact temperature measurements; Strahlungsthermometrie - Temperaturen beruehrungslos messen

Energy Technology Data Exchange (ETDEWEB)

Hollandt, J.; Hartmann, J.; Gutschwager, B. [Physikalisch-Technische Bundesanstalt, Berlin (Germany); Struss, O. [HEITRONICS Infrarot Messtechnik GmbH, Wiesbaden (Germany)

2006-07-01

The temperature is one of the measurands most frequently determined, as it decisively influences physical, chemical and biological processes. To be able to evaluate, optimize, repeat and compare industrial procedures, temperatures must be measured with sufficient accuracy and worldwide uniformity. This is done with the aid of the regulations and instructions of the international temperature scale. Today, non-contact measurements of surface temperatures can be performed without problems with radiation thermometers over a temperature range from -100 C up to 3000 C. Compared to contacting measurements, radiation-thermometric temperature measurement offers a series of advantages. Radiation thermometers react very fast and the measurement is not influenced by heat supply or dissipation. This allows objects to be measured which move very fast, are energized or may experience fast temperature changes. Consequently, radiation thermometry is increasingly used for the monitoring and control of thermal processes, for maintenance and in building services engineering. The present contribution shall inform of the fundamentals of radiation-thermometric temperature measurement as well as of the construction and popular types of radiation thermometers. It will be explained how exact and worldwide uniform temperature measurement is guaranteed via the international temperature scale and the calibration of radiation thermometers. The emissivity of surfaces which is important in practical temperature measurements and some examples of industrial applications of radiation thermometers will be described. (orig.)

Non-Contact Measurements of Creep Properties of Refractory Materials

Science.gov (United States)

Lee, Jonghyun; Bradshaw, Richard C.; Hyers, Robert W.; Rogers, Jan R.; Rathz, Thomas J.; Wall, James J.; Choo, Hahn; Liaw, Peter

2006-01-01

State-of-the-art technologies for hypersonic aircraft, nuclear electric/thermal propulsion for spacecraft, and more efficient jet engines are driving ever more demanding needs for high-temperature (>2000 C) materials. At such high temperatures, creep rises as one of the most important design factors to be considered. Since conventional measurement techniques for creep resistance are limited to about 17OO0C, a new technique is in demand for higher temperatures. This paper presents a non-contact method using electrostatic levitation (ESL) which is applicable to both metallic and non-metallic materials. The samples were rotated quickly enough to cause creep deformation by centrifugal acceleration. The deformation of the samples was captured with a high speed camera and then the images were analyzed to estimate creep resistance. Finite element analyses were performed and compared to the experiments to verify the new method. Results are presented for niobium and tungsten, representative refractory materials at 2300 C and 2700 C respectively.

Non-Contact Measurement of Thermal Diffusivity in Ion-Implanted Nuclear Materials

Science.gov (United States)

Hofmann, F.; Mason, D. R.; Eliason, J. K.; Maznev, A. A.; Nelson, K. A.; Dudarev, S. L.

2015-11-01

Knowledge of mechanical and physical property evolution due to irradiation damage is essential for the development of future fission and fusion reactors. Ion-irradiation provides an excellent proxy for studying irradiation damage, allowing high damage doses without sample activation. Limited ion-penetration-depth means that only few-micron-thick damaged layers are produced. Substantial effort has been devoted to probing the mechanical properties of these thin implanted layers. Yet, whilst key to reactor design, their thermal transport properties remain largely unexplored due to a lack of suitable measurement techniques. Here we demonstrate non-contact thermal diffusivity measurements in ion-implanted tungsten for nuclear fusion armour. Alloying with transmutation elements and the interaction of retained gas with implantation-induced defects both lead to dramatic reductions in thermal diffusivity. These changes are well captured by our modelling approaches. Our observations have important implications for the design of future fusion power plants.

Non-Contact Measurement of Thermal Diffusivity in Ion-Implanted Nuclear Materials

International Nuclear Information System (INIS)

Hofmann, F.; Mason, D. R.; Eliason, J. K.; Maznev, A. A.; Nelson, K. A.; Dudarev, S. L.

2015-01-01

Knowledge of mechanical and physical property evolution due to irradiation damage is essential for the development of future fission and fusion reactors. Ion-irradiation provides an excellent proxy for studying irradiation damage, allowing high damage doses without sample activation. Limited ion-penetration-depth means that only few-micron-thick damaged layers are produced. Substantial effort has been devoted to probing the mechanical properties of these thin implanted layers. Yet, whilst key to reactor design, their thermal transport properties remain largely unexplored due to a lack of suitable measurement techniques. Here we demonstrate non-contact thermal diffusivity measurements in ion-implanted tungsten for nuclear fusion armour. Alloying with transmutation elements and the interaction of retained gas with implantation-induced defects both lead to dramatic reductions in thermal diffusivity. These changes are well captured by our modelling approaches. Our observations have important implications for the design of future fusion power plants

Non-contact and contact measurement system for detecting projectile position in electromagnetic launch bore

Science.gov (United States)

Xu, Weidong; Yuan, Weiqun; Xu, Rong; Zhao, Hui; Cheng, Wenping; Zhang, Dongdong; Zhao, Ying; Yan, Ping

2017-12-01

This paper introduces a new measurement system for measuring the position of a projectile within a rapid fire electromagnetic launching system. The measurement system contains both non-contact laser shading and metal fiber contact measurement devices. Two projectiles are placed in the rapid fire electromagnetic launch bore, one in the main accelerating segment and the other in the pre-loading segment. The projectile placed in the main accelerating segment should be shot first, and then the other is loaded into the main segment from the pre-loading segment. The main driving current (I-main) can only be discharged again when the second projectile has arrived at the key position (the projectile position corresponds to the discharging time) in the main accelerating segment. So, it is important to be able to detect when the second projectile arrives at the key position in the main accelerating segment. The B-dot probe is the most widely used system for detecting the position of the projectile in the electromagnetic launch bore. However, the B-dot signal is affected by the driving current amplitude and the projectile velocity. There is no current in the main accelerating segment when the second projectile moves into this segment in rapid fire mode, so the B-dot signal for detecting the key position is invalid. Due to the presence of a high-intensity magnetic field, a high current, a high-temperature aluminum attachment, smoke and strong vibrations, it is very difficult to detect the projectile position in the bore accurately. So, other measurements need to be researched and developed in order to achieve high reliability. A measurement system based on a laser (non-contact) and metal fibers (contact) has been designed, and the integrated output signal based on this detector is described in the following paper.

Simulation of non-contact tonometer - Ocular response analyzer

Directory of Open Access Journals (Sweden)

M. Arsalan Khan

2016-04-01

Simultaneous explosion of ophthalmic knowledge and medical instrument, being made in the 19th century, has led to the invention of tonometers of varied designs and principles, and Non-Contact Tonometers (NCTs are among them. Glodmann Applanation Tonometer (GAT is considered the ‘gold standard’ in measuring IOP; however, IOP measurement using GAT is now known to be affected by various factors like corneal thickness, curvature and material properties as demonstrated by Khan [1]. Due to inaccuracies in measuring IOP by GAT, this ‘gold standard’ has been challenged. Therefore, the present research aims to develop a multi-parametric correction equation to determine the True Intraocular Pressure (IOPT using Non-Contact Tonometer and the current article focuses on evaluating the influence of individual parameters on IOP by NCT.

Research on the nonintrusive measurement of the turbine blade vibration

Science.gov (United States)

Zhang, Shi hai; Li, Lu-ping; Rao, Hong-de

2008-11-01

It's one of the important ways to monitor the change of dynamic characteristic of turbine blades for ensuring safety operation of turbine unit. Traditional measurement systems for monitoring blade vibration generally use strain gauges attached to the surface of turbine blades, each strain gauge gives out an analogue signal related to blade deformation, it's maximal defect is only a few blades could be monitored which are attached by strain gauge. But the noncontact vibration measurement will be discussed would solve this problem. This paper deals with noncontact vibration measurement on the rotor blades of turbine through experiments. In this paper, the noncontact vibration measurement - Tip Timing Measurement will be presented, and will be improved. The statistics and DFT will be used in the improved measurement. The main advantage of the improved measurement is that only two sensors over the top of blades and one synchronous sensor of the rotor are used to get the exact vibration characteristics of the each blade in a row. In our experiment, we adopt NI Company's DAQ equipment: SCXI1001 and PCI 6221, three optical sensors, base on the graphics program soft LabVIEW to develop the turbine blade monitor system. At the different rotational speed of the rotor (1000r/m and 1200r/m) we do several experiments on the bench of the Turbine characteristic. Its results indicated that the vibration of turbine blade could be real-time monitored and accurately measured by the improved Tip Timing Measurement.

Non-Contact Thermal Properties Measurement with Low-Power Laser and IR Camera System

Science.gov (United States)

Hudson, Troy L.; Hecht, Michael H.

2011-01-01

As shown by the Phoenix Mars Lander's Thermal and Electrical Conductivity Probe (TECP), contact measurements of thermal conductivity and diffusivity (using a modified flux-plate or line-source heat-pulse method) are constrained by a number of factors. Robotic resources must be used to place the probe, making them unavailable for other operations for the duration of the measurement. The range of placement is also limited by mobility, particularly in the case of a lander. Placement is also subject to irregularities in contact quality, resulting in non-repeatable heat transfer to the material under test. Most important from a scientific perspective, the varieties of materials which can be measured are limited to unconsolidated or weakly-cohesive regolith materials, rocks, and ices being too hard for nominal insertion strengths. Accurately measuring thermal properties in the laboratory requires significant experimental finesse, involving sample preparation, controlled and repeatable procedures, and, practically, instrumentation much more voluminous than the sample being tested (heater plates, insulation, temperature sensors). Remote measurements (infrared images from orbiting spacecraft) can reveal composite properties like thermal inertia, but suffer both from a large footprint (low spatial resolution) and convolution of the thermal properties of a potentially layered medium. In situ measurement techniques (the Phoenix TECP is the only robotic measurement of thermal properties to date) suffer from problems of placement range, placement quality, occupation of robotic resources, and the ability to only measure materials of low mechanical strength. A spacecraft needs the ability to perform a non-contact thermal properties measurement in situ. Essential components include low power consumption, leveraging of existing or highly-developed flight technologies, and mechanical simplicity. This new in situ method, by virtue of its being non-contact, bypasses all of these

Noncontact spirometry with a webcam

Science.gov (United States)

Liu, Chenbin; Yang, Yuting; Tsow, Francis; Shao, Dangdang; Tao, Nongjian

2017-05-01

We present an imaging-based method for noncontact spirometry. The method tracks the subtle respiratory-induced shoulder movement of a subject, builds a calibration curve, and determines the flow-volume spirometry curve and vital respiratory parameters, including forced expiratory volume in the first second, forced vital capacity, and peak expiratory flow rate. We validate the accuracy of the method by comparing the data with those simultaneously recorded with a gold standard reference method and examine the reliability of the noncontact spirometry with a pilot study including 16 subjects. This work demonstrates that the noncontact method can provide accurate and reliable spirometry tests with a webcam. Compared to the traditional spirometers, the present noncontact spirometry does not require using a spirometer, breathing into a mouthpiece, or wearing a nose clip, thus making spirometry test more easily accessible for the growing population of asthma and chronic obstructive pulmonary diseases.

Profile measurement of a bent neutron mirror using an ultrahigh precision non-contact measurement system with an auto focus laser probe

International Nuclear Information System (INIS)

Morita, S; Guo, J; Yamagata, Y; Yamada, N L; Torikai, N; Takeda, S; Furusaka, M

2016-01-01

A bent neutron mirror has been considered as one of the best solutions for focusing neutron beams from the viewpoint of cost-benefit performance. Although the form deviation of the bent profile is expected because of the large spot size, it is difficult to measure due to its geometric limitation. Here, we propose a non-contact measurement system using an auto focus (AF) laser probe on an ultrahigh precision machine tool to precisely evaluate the form deviation of the bent mirror. The AF laser probe is composed of a diode laser, a position sensitive sensor, a charge-coupled device (CCD) camera and a microscope objective lens which is actuated by an electromagnetic motor with 1 nm resolution for position sensing and control. The sensor enables a non-contact profile measurement of a high precision surface without any surface damage in contrast with contact-type ultrahigh precision coordinate measurement machines with ruby styli. In the on-machine measurement system, a personal computer simultaneously acquires a displacement signal from the AF laser probe and 3-axis positional coordinates of the ultrahigh machine tool branched between the linear laser scales and the numerical controller. The acquisition rate of the 4-axis positional data in 1 nm resolution is more than 10 Hz and the simultaneity between the axes is negligible. The profile of a neutron bent mirror was measured from a transparent side using the developed system, and the result proves that the form deviation of the mirror enlarged the the spot size of focused neuron beam. (paper)

Measurement of Creep Properties of Ultra-High-Temperature Materials by a Novel Non-Contact Technique

Science.gov (United States)

Hyers, Robert W.; Lee, Jonghyun; Rogers, Jan R.; Liaw, Peter K.

2007-01-01

A non-contact technique for measuring the creep properties of materials has been developed and validated as part of a collaboration among the University of Massachusetts, NASA Marshall Space Flight Center Electrostatic Levitation Facility (ESL), and the University of Tennessee. This novel method has several advantages over conventional creep testing. The sample is deformed by the centripetal acceleration from the rapid rotation, and the deformed shapes are analyzed to determine the strain. Since there is no contact with grips, there is no theoretical maximum temperature and no concern about chemical compatibility. Materials may be tested at the service temperature even for extreme environments such as rocket nozzles, or above the service temperature for accelerated testing of materials for applications such as jet engines or turbopumps for liquid-fueled engines. The creep measurements have been demonstrated to 2400 C with niobium, while the test facility, the NASA MSFC ESL, has processed materials up to 3400 C. Furthermore, the ESL creep method employs a distribution of stress to determine the stress exponent from a single test, versus the many tests required by conventional methods. Determination of the stress exponent from the ESL creep tests requires very precise measurement of the surface shape of the deformed sample for comparison to deformations predicted by finite element models for different stress exponents. An error analysis shows that the stress exponent can be determined to about 1% accuracy with the current methods and apparatus. The creep properties of single-crystal niobium at 1985 C showed excellent agreement with conventional tests performed according to ASTM Standard E-139. Tests on other metals, ceramics, and composites relevant to rocket propulsion and turbine engines are underway.

Non-contact remote monitoring technique of reactor structural elements

International Nuclear Information System (INIS)

Inoue, Hideo; Mori, Kazuo; Ozawa, Norimitsu; Akedo, Jun; Seimiya, Koichi; Chikamori, Kunio; Umezawa, Akihiko

1998-01-01

This study aims at development of technique to measure and estimate, at high precision, fine machining scratch, crack and so on formed on grinding tubular elements, especially inner faces of small diameter tube at an optical mirror grade, and at establishment of estimation technique on reliability and soundness of the tubular elements. In this fiscal year, on optical type non-contact monitoring technique, investigations on optical illumination condition and holding accuracy required for the non-contact holding mechanism were conducted by using a sensor head trially produced in 1995 fiscal year. And, in order to realize a high precision non-contact holding in a tube of optical detection system to upgrade static holding properties (holding stiffness, holding attitude, and so on) of pneumatic type inner tube non-contact holding mechanism, realization of increase in supplying air pressure and experiments using a holding mechanism to increase pore numbers of air injecting nozzle were conducted. And, on materials surface technique, effect of difference in pre-machining method (cutting and bright annealing) at inner face of small diameter stainless tube on their smooth machining property was examined. (G.K.)

Method for 3D noncontact measurements of cut trees package area

Science.gov (United States)

Knyaz, Vladimir A.; Vizilter, Yuri V.

2001-02-01

Progress in imaging sensors and computers create the background for numerous 3D imaging application for wide variety of manufacturing activity. Many demands for automated precise measurements are in wood branch of industry. One of them is the accurate volume definition for cut trees carried on the truck. The key point for volume estimation is determination of the front area of the cut tree package. To eliminate slow and inaccurate manual measurements being now in practice the experimental system for automated non-contact wood measurements is developed. The system includes two non-metric CCD video cameras, PC as central processing unit, frame grabbers and original software for image processing and 3D measurements. The proposed method of measurement is based on capturing the stereo pair of front of trees package and performing the image orthotranformation into the front plane. This technique allows to process transformed image for circle shapes recognition and calculating their area. The metric characteristics of the system are provided by special camera calibration procedure. The paper presents the developed method of 3D measurements, describes the hardware used for image acquisition and the software realized the developed algorithms, gives the productivity and precision characteristics of the system.

A noncontact laser system for measuring soil surface topography

International Nuclear Information System (INIS)

Huang, C.; White, I.; Thwaite, E.G.; Bendeli, A.

1988-01-01

Soil surface topography profoundly influences runoff hydrodynamics, soil erosion, and surface retention of water. Here we describe an optical noncontact system for measuring soil surface topography. Soil elevation is measured by projecting a laser beam onto the surface and detecting the position of the interception point. The optical axis of the detection system is oriented at a small angle to the incident beam. A low-power HeNe (Helium-Neon) laser is used as the laser source, a photodiode array is used as the laser image detector and an ordinary 35-mm single lens reflex camera provides the optical system to focus the laser image onto the diode array. A wide spectrum of measurement ranges (R) and resolutions are selectable, from 1 mm to 1 m. These are determined by the laser-camera distance and angle, the focal length of the lens, and the sensing length of the diode array and the number of elements (N) contained in the array. The resolution of the system is approximately R/2N. We show for the system used here that this resolution is approximately 0.2%. In the configuration selected, elevation changes of 0.16 mm could be detected over a surface elevation range of 87 mm. The sampling rate of the system is 1000 Hz, which permits soil surfaces to be measured at speeds of up to 1 m s −1 with measurements taken at 1-mm spacing. Measurements of individual raindrop impacts on the soil and of soil surfaces before and after rain show the versatility of the laser surface profiler, which has applications in studies of erosion processes, surface storage and soil trafficability

Use of radars to monitor stream discharge by noncontact methods

Science.gov (United States)

Costa, J.E.; Cheng, R.T.; Haeni, F.P.; Melcher, N.; Spicer, K.R.; Hayes, E.; Plant, W.; Hayes, K.; Teague, C.; Barrick, D.

2006-01-01

Conventional measurements of river flows are costly, time‐consuming, and frequently dangerous. This report evaluates the use of a continuous wave microwave radar, a monostatic UHF Doppler radar, a pulsed Doppler microwave radar, and a ground‐penetrating radar to measure river flows continuously over long periods and without touching the water with any instruments. The experiments duplicate the flow records from conventional stream gauging stations on the San Joaquin River in California and the Cowlitz River in Washington. The purpose of the experiments was to directly measure the parameters necessary to compute flow: surface velocity (converted to mean velocity) and cross‐sectional area, thereby avoiding the uncertainty, complexity, and cost of maintaining rating curves. River channel cross sections were measured by ground‐penetrating radar suspended above the river. River surface water velocity was obtained by Bragg scattering of microwave and UHF Doppler radars, and the surface velocity data were converted to mean velocity on the basis of detailed velocity profiles measured by current meters and hydroacoustic instruments. Experiments using these radars to acquire a continuous record of flow were conducted for 4 weeks on the San Joaquin River and for 16 weeks on the Cowlitz River. At the San Joaquin River the radar noncontact measurements produced discharges more than 20% higher than the other independent measurements in the early part of the experiment. After the first 3 days, the noncontact radar discharge measurements were within 5% of the rating values. On the Cowlitz River at Castle Rock, correlation coefficients between the USGS stream gauging station rating curve discharge and discharge computed from three different Doppler radar systems and GPR data over the 16 week experiment were 0.883, 0.969, and 0.992. Noncontact radar results were within a few percent of discharge values obtained by gauging station, current meter, and hydroacoustic methods

Non-Contact Surface Roughness Measurement by Implementation of a Spatial Light Modulator

Directory of Open Access Journals (Sweden)

Laura Aulbach

2017-03-01

Full Text Available The surface structure, especially the roughness, has a significant influence on numerous parameters, such as friction and wear, and therefore estimates the quality of technical systems. In the last decades, a broad variety of surface roughness measurement methods were developed. A destructive measurement procedure or the lack of feasibility of online monitoring are the crucial drawbacks of most of these methods. This article proposes a new non-contact method for measuring the surface roughness that is straightforward to implement and easy to extend to online monitoring processes. The key element is a liquid-crystal-based spatial light modulator, integrated in an interferometric setup. By varying the imprinted phase of the modulator, a correlation between the imprinted phase and the fringe visibility of an interferogram is measured, and the surface roughness can be derived. This paper presents the theoretical approach of the method and first simulation and experimental results for a set of surface roughnesses. The experimental results are compared with values obtained by an atomic force microscope and a stylus profiler.

Strain measurement based battery testing

Science.gov (United States)

Xu, Jeff Qiang; Steiber, Joe; Wall, Craig M.; Smith, Robert; Ng, Cheuk

2017-05-23

A method and system for strain-based estimation of the state of health of a battery, from an initial state to an aged state, is provided. A strain gauge is applied to the battery. A first strain measurement is performed on the battery, using the strain gauge, at a selected charge capacity of the battery and at the initial state of the battery. A second strain measurement is performed on the battery, using the strain gauge, at the selected charge capacity of the battery and at the aged state of the battery. The capacity degradation of the battery is estimated as the difference between the first and second strain measurements divided by the first strain measurement.

High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

Science.gov (United States)

Aksoy, B.; Rehman, A.; Bayraktar, H.; Alaca, B. E.

2017-04-01

Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µm are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

International Nuclear Information System (INIS)

Aksoy, B; Alaca, B E; Rehman, A; Bayraktar, H

2017-01-01

Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µ m are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

The in vitro and in vivo validation of a mobile non-contact camera-based digital imaging system for tooth colour measurement.

Science.gov (United States)

Smith, Richard N; Collins, Luisa Z; Naeeni, Mojgan; Joiner, Andrew; Philpotts, Carole J; Hopkinson, Ian; Jones, Clare; Lath, Darren L; Coxon, Thomas; Hibbard, James; Brook, Alan H

2008-01-01

To assess the reproducibility of a mobile non-contact camera-based digital imaging system (DIS) for measuring tooth colour under in vitro and in vivo conditions. One in vitro and two in vivo studies were performed using a mobile non-contact camera-based digital imaging system. In vitro study: two operators used the DIS to image 10 dry tooth specimens in a randomised order on three occasions. In vivo study 1:25 subjects with two natural, normally aligned, upper central incisors had their teeth imaged using the DIS on four consecutive days by one operator to measure day-to-day variability. On one of the four test days, duplicate images were collected by three different operators to measure inter- and intra-operator variability. In vivo study 2:11 subjects with two natural, normally aligned, upper central incisors had their teeth imaged using the DIS twice daily over three days within the same week to assess day-to-day variability. Three operators collected images from subjects in a randomised order to measure inter- and intra-operator variability. Subject-to-subject variability was the largest source of variation within the data. Pairwise correlations and concordance coefficients were > 0.7 for each operator, demonstrating good precision and excellent operator agreement in each of the studies. Intraclass correlation coefficients (ICCs) for each operator indicate that day-to-day reliability was good to excellent, where all ICC's where > 0.75 for each operator. The mobile non-contact camera-based digital imaging system was shown to be a reproducible means of measuring tooth colour in both in vitro and in vivo experiments.

Robust, accurate, and non-contacting vibration measurement systems: Summary of comparison measurements of the robust laser interferometer and typical accelerometer systems. Volume 1

International Nuclear Information System (INIS)

Goodenow, T.C.; Shipman, R.L.; Holland, H.M.

1995-06-01

Epoch Engineering, Incorporated (EEI) has completed a series of vibration measurements comparing their newly-developed Robust Laser Interferometer (RLI) with accelerometer-based instrumentation systems. EEI has successfully demonstrated, on several pieces of commonplace machinery, that non-contact, line-of-sight measurements are practical and yield results equal to or, in some cases, better than customary field implementations of accelerometers. The demonstration included analysis and comparison of such phenomena as nonlinearity, transverse sensitivity, harmonics, and signal-to-noise ratio. Fast Fourier Transformations were performed on the accelerometer and the laser system outputs to provide a comparison basis. The RLI was demonstrated, within the limits of the task, to be a viable, line-of-sight, non-contact alternative to accelerometer systems. Several different kinds of machinery were instrumented and compared, including a small pump, a gear-driven cement mixer, a rotor kit, and two small fans. Known machinery vibration sources were verified and RLI system output file formats were verified to be compatible with commercial computer programs used for vibration monitoring and trend analysis. The RLI was also observed to be less subject to electromagnetic interference (EMI) and more capable at very low frequencies

CLINICAL-EVALUATION OF 2 NONCONTACT TONOMETERS

NARCIS (Netherlands)

KOOPMANS, SA; KOOIJMAN, AC; VANRIJ, G; EISSES, J; DEGROOTWOLTJER, J

1991-01-01

The precision and speed of two non-contact tonometers were examined and compared. The Goldmann applanation tonometer was used as the standard for precision. On the average the results obtained with the non-contact tonometers were not significantly different from those obtained with the Goldmann

Validation and qualification of surface-applied fibre optic strain sensors using application-independent optical techniques

International Nuclear Information System (INIS)

Schukar, Vivien G; Kadoke, Daniel; Kusche, Nadine; Münzenberger, Sven; Gründer, Klaus-Peter; Habel, Wolfgang R

2012-01-01

Surface-applied fibre optic strain sensors were investigated using a unique validation facility equipped with application-independent optical reference systems. First, different adhesives for the sensor's application were analysed regarding their material properties. Measurements resulting from conventional measurement techniques, such as thermo-mechanical analysis and dynamic mechanical analysis, were compared with measurements resulting from digital image correlation, which has the advantage of being a non-contact technique. Second, fibre optic strain sensors were applied to test specimens with the selected adhesives. Their strain-transfer mechanism was analysed in comparison with conventional strain gauges. Relative movements between the applied sensor and the test specimen were visualized easily using optical reference methods, digital image correlation and electronic speckle pattern interferometry. Conventional strain gauges showed limited opportunities for an objective strain-transfer analysis because they are also affected by application conditions. (paper)

Accuracy and reliability of the Keeler Pulsair EasyEye non-contact tonometer.

Science.gov (United States)

Ogbuehi, Kelechi C; Almubrad, Turki M

2008-01-01

To evaluate the accuracy and reliability of the Keeler Pulsair EasyEye noncontact tonometer in a normotensive population. This masked prospective clinical study included 72 right eyes of 72 subjects. Two sets of intraocular pressure measurements were made 1 week apart. Intraocular pressure assessment with the Goldmann tonometer was always subsequent to that with the noncontact tonometer. Each method was assessed for within-session and test-retest repeatability and both methods were assessed for limits of agreement, twice. The level of significance for this study was 0.05. Both methods were repeatable within-sessions to within +/-2 mm Hg, and between sessions to within +/-3 mm Hg. Neither the within-session differences nor the between session differences differed significantly between the Goldmann tonometer and the Pulsair EasyEye noncontact tonometer. The mean differences (+/-SD) between both methods (0.1 +/- 1.6 mm Hg and 0.05 +/- 1.7 mm Hg, for the first and second sessions, respectively) were not statistically significant, but the intraocular pressure measured with the Pulsair EasyEye tonometer was consistently higher than that measured with the Goldmann tonometer. The Pulsair EasyEye noncontact tonometer is considered an accurate reliable method in the normotensive population studied but because of a systematic bias in a small number of subjects, it cannot be used interchangeably with the Goldmann tonometer.

Footwear traction and lower extremity noncontact injury.

Science.gov (United States)

Wannop, John W; Luo, Geng; Stefanyshyn, Darren J

2013-11-01

Football is the most popular high school sport; however, it has the highest rate of injury. Speculation has been prevalent that foot fixation due to high footwear traction contributes to injury risk. Therefore, the purpose of the study was to determine whether a relationship exists between the athlete's specific footwear traction (measured with their own shoes on the field of play) and lower extremity noncontact injury in high school football. For 3 yr, 555 high school football athletes had their footwear traction measured on the actual field of play at the start of the season, and any injury the athletes suffered during a game was recorded. Lower extremity noncontact injury rates, grouped based on the athlete's specific footwear traction (both translational and rotational), were compared. For translational traction, injury rate reached a peak of 23.3 injuries/1000 game exposures within the midrange of translational traction, before decreasing to 5.0 injuries/1000 game exposures in the high range of traction. For rotational traction, there was a steady increase in injury rate as footwear traction increased, starting at 4.2 injuries/1000 game exposures at low traction and reaching 19.2 injuries/1000 game exposures at high traction. A relationship exists between footwear traction and noncontact lower extremity injury, with increases in rotational traction leading to a greater injury rate and increases in translational traction leading to a decrease in injury. It is recommended that athletes consider selecting footwear with the lowest rotational traction values for which no detriment in performance results.

Non-Contact Acousto-Thermal Signatures of Plastic Deformation in TI-6AL-4V

Science.gov (United States)

Welter, J. T.; Malott, G.; Schehl, N.; Sathish, S.; Jata, K. V.; Blodgett, M. P.

2010-02-01

Plastic deformation introduces changes in a material which include increases in: dislocations, strains, residual stress, and yield stress. However, these changes have a very small impact on the material properties such as elastic modulus, conductivity and ultrasonic wave speed. This is due to the fact that interatomic forces govern these properties, and they are not affected by plastic deformation to any large degree. This is evident from the fact that the changes in electrical resistance and ultrasonic velocity in plastically deformed and virgin samples are very small and can only be determined by highly controlled experiments. Except for X-ray diffraction, there are no direct nondestructive methods for measuring strain and the residual stress. This paper presents an application of the non-contact acousto-thermal signature (NCATS) NDE methodology to detect plastic deformation in flat dog bone Ti-6Al-4V samples. Results of the NCATS measurements on samples subjected to incremental amounts of plastic deformation are presented. The maximum temperature attained by the sample due to acoustic excitation is found to be sensitive to the amount of plastic strain. It is observed that the temperature induced by acoustic excitation increases to a peak followed by a decrease to failure. The maximum temperature peak occurs at plastic strains of 12-14%. It is observed that there is a correlation between the peak in maximum temperature rise and the strain at the experimentally determined ultimate tensile strength. A microstructural based explanation for this will be presented. The results are discussed in reference to utilizing this technique for detection and evaluation of plastic deformation.

A portable non-contact displacement sensor and its application of lens centration error measurement

Science.gov (United States)

Yu, Zong-Ru; Peng, Wei-Jei; Wang, Jung-Hsing; Chen, Po-Jui; Chen, Hua-Lin; Lin, Yi-Hao; Chen, Chun-Cheng; Hsu, Wei-Yao; Chen, Fong-Zhi

2018-02-01

We present a portable non-contact displacement sensor (NCDS) based on astigmatic method for micron displacement measurement. The NCDS are composed of a collimated laser, a polarized beam splitter, a 1/4 wave plate, an aspheric objective lens, an astigmatic lens and a four-quadrant photodiode. A visible laser source is adopted for easier alignment and usage. The dimension of the sensor is limited to 115 mm x 36 mm x 56 mm, and a control box is used for dealing with signal and power control between the sensor and computer. The NCDS performs micron-accuracy with +/-30 μm working range and the working distance is constrained in few millimeters. We also demonstrate the application of the NCDS for lens centration error measurement, which is similar to the total indicator runout (TIR) or edge thickness difference (ETD) of a lens measurement using contact dial indicator. This application has advantage for measuring lens made in soft materials that would be starched by using contact dial indicator.

Sub-Angstrom oscillation amplitude non-contact atomic force microscopy for lateral force gradient measurement

International Nuclear Information System (INIS)

Atabak, Mehrdad; Unverdi, Ozhan; Ozer, H. Ozguer; Oral, Ahmet

2009-01-01

We report the first results from novel sub-Angstrom oscillation amplitude non-contact atomic force microscopy developed for lateral force gradient measurements. Quantitative lateral force gradients between a tungsten tip and Si(1 1 1)-(7 x 7) surface can be measured using this microscope. Simultaneous lateral force gradient and scanning tunnelling microscope images of single and multi atomic steps are obtained. In our measurement, tunnel current is used as feedback. The lateral stiffness contrast has been observed to be 2.5 N/m at single atomic step, in contrast to 13 N/m at multi atomic step on Si(1 1 1) surface. We also carried out a series of lateral stiffness-distance spectroscopy. We observed lateral stiffness-distance curves exhibit sharp increase in the stiffness as the sample is approached towards the surface. We usually observed positive stiffness and sometimes going into slightly negative region.

Non-Contact Laser Based Ultrasound Evaluation of Canned Foods

Science.gov (United States)

Shelton, David

2005-03-01

Laser-Based Ultrasound detection was used to measure the velocity of compression waves transmitted through canned foods. Condensed broth, canned pasta, and non-condensed soup were evaluated in these experiments. Homodyne adaptive optics resulted in measurements that were more accurate than the traditional heterodyne method, as well as yielding a 10 dB gain in signal to noise. A-Scans measured the velocity of ultrasound sent through the center of the can and were able to distinguish the quantity of food stuff in its path, as well as distinguish between meat and potato. B-Scans investigated the heterogeneity of the sample’s contents. The evaluation of canned foods was completely non-contact and would be suitable for continuous monitoring in production. These results were verified by conducting the same experiments with a contact piezo transducer. Although the contact method yields a higher signal to noise ratio than the non-contact method, Laser-Based Ultrasound was able to detect surface waves the contact transducer could not.

Performance of a commercial backscatter instrument adapted for noncontacting areal density measurements on small-diameter surfaces

International Nuclear Information System (INIS)

Higgins, P.B.

1980-12-01

Measuring the local areal density of a sensitive explosive deposited on a small-diameter surface requires noncontacting technique and good resolution. The side effects of spacing the sensing platen of an NX-500 Betascope 2.54 mm from the surface of cylinders as small as 13-mm diameter are examined. Resolution in two directions and offset error sensitivity of the system are defined and determined using coatings of simulated explosive. An eddy-current system is described which can be easily added to reduce offset errors caused by fixture misalignment

Assessment of human respiration patterns via noncontact sensing using Doppler multi-radar system.

Science.gov (United States)

Gu, Changzhan; Li, Changzhi

2015-03-16

Human respiratory patterns at chest and abdomen are associated with both physical and emotional states. Accurate measurement of the respiratory patterns provides an approach to assess and analyze the physical and emotional states of the subject persons. Not many research efforts have been made to wirelessly assess different respiration patterns, largely due to the inaccuracy of the conventional continuous-wave radar sensor to track the original signal pattern of slow respiratory movements. This paper presents the accurate assessment of different respiratory patterns based on noncontact Doppler radar sensing. This paper evaluates the feasibility of accurately monitoring different human respiration patterns via noncontact radar sensing. A 2.4 GHz DC coupled multi-radar system was used for accurate measurement of the complete respiration patterns without any signal distortion. Experiments were carried out in the lab environment to measure the different respiration patterns when the subject person performed natural breathing, chest breathing and diaphragmatic breathing. The experimental results showed that accurate assessment of different respiration patterns is feasible using the proposed noncontact radar sensing technique.

Development of a high cycle vibration fatigue diagnostic system with non-contact vibration sensing

International Nuclear Information System (INIS)

Nekomoto, Yoshitsugu; Tanaka, Masanori; Nishimura, Moritatsu; Matsumoto, Kenji; O'shima, Eiji

2004-01-01

Nuclear power plants have a large number of pipes. These small-diameter pipe branches in particles are often damaged due to high-cycle fatigue. In order to ensure the reliability of a plant it is important to detect fatigue damages in pipe branches at an early stage and to develop the technology to predict and diagnose the advancement of fatigue. Further, in order to carry out the diagnosis of the piping system effectively during operation, non-contact evaluation is useful. Hence, we have developed a ''high-cycle fatigue diagnostic system with non-contact vibration sensing'', which measures the vibration of the pipe branch using a non-contact sensor. (author)

Robust, accurate, and non-contacting vibration measurement systems: Supplemental appendices presenting comparison measurements of the robust laser interferometer and typical accelerometer systems. Volume 2

International Nuclear Information System (INIS)

Goodenow, T.C.; Shipman, R.L.; Holland, H.M.

1995-06-01

Epoch Engineering, Incorporated (EEI) has completed a series of vibration measurements comparing their newly-developed Robust Laser Interferometer (RLI) with accelerometer-based instrumentation systems. EEI has successfully demonstrated, on several pieces of commonplace machinery, that non-contact, line-of-sight measurements are practical and yield results equal to or, in some cases, better than customary field implementations of accelerometers. The demonstration included analysis and comparison of such phenomena as nonlinearity, transverse sensitivity, harmonics, and signal-to-noise ratio. Fast Fourier Transformations were performed on the accelerometer and the laser system outputs to provide a comparison basis. The RLI was demonstrated, within the limits o the task, to be a viable, line-of-sight, non-contact alternative to accelerometer systems. Several different kinds of machinery were instrumented and. compared, including a small pump, a gear-driven cement mixer, a rotor kit, and two small fans. Known machinery vibration sources were verified and RLI system output file formats were verified to be compatible with commercial computer programs used for vibration monitoring and trend analysis. The RLI was also observed to be less subject to electromagnetic interference (EMI) and more capable at very low frequencies. This document, Volume 2, provides the appendices to this report

Intraocular pressure measurement with the noncontact tonometer through soft contact lenses.

Science.gov (United States)

Liu, Yi-Chun; Huang, Jehn-Yu; Wang, I-Jong; Hu, Fung-Rong; Hou, Yu-Chih

2011-03-01

To assess the accuracy of measuring intraocular pressure (IOP) through a soft contact lens (SCL) with different refractive powers using a noncontact tonometer (NCT). Thirty-two healthy adult volunteers free of glaucoma or corneal disease participated in this study. IOP was measured in the right eyes without SCLs and with different lens powers, from -3.0 to -12.0 D as measured by NCT. IOP of the left eyes was also measured, as an internal control. Corneal curvature was measured in both eyes using an autokeratometer. Sixteen volunteers wore one brand of SCL (group A) and the other 16 wore a different brand, with 2 different curvatures (groups B and C). Statistical data were analyzed by SPSS using the Wilcoxon signed rank test for comparison of IOP readings and multiple linear regression analysis for the relationship among power of contact lenses, corneal power, and difference in IOP measurements. The difference in mean IOP between eyes without lenses and those with lenses was statistically significant in lens with -6.0 D and below in all 3 groups. The decrease in IOP significantly correlated with the refractive power of contact lenses in all 3 groups. The difference in IOP measurements was influenced by the mean K in group A but not in group B or C. There was no statistically significant difference in the IOP measurements in the left eyes or in the mean K between the right and left eyes. IOP measurement through myopic SCLs by NCT may be inaccurate and tends toward underestimation, especially in high myopic lenses. A strong relationship exists between IOP reduction and myopic lens power.

Non-contact translation-rotation sensor using combined effects of magnetostriction and piezoelectricity.

Science.gov (United States)

Yang, Bintang; Liu, Qingwei; Zhang, Ting; Cao, Yudong; Feng, Zhiqiang; Meng, Guang

2012-10-15

Precise displacement sensors are an important topic in precision engineering. At present, this type of sensors typically have a single feature of either translation or rotation measurement. They are also inconvenient to integrate with the host devices. In this report we propose a new kind of sensor that enables both translation and rotation measurement by using the combined effect of magnetostriction and piezoelectricity. As a proof of concept, we experimentally realized a prototype of non-contact translation-rotation precise sensor. In the current research stage, through both theoretical and experimental study, the non-contact displacement sensor is shown to be feasible for measuring both translation and rotation either in coarse or fine measurement. Moreover, owing to its compact, rigid structure and fewer components, it can be easily embedded in host equipment.

Non-Contact Translation-Rotation Sensor Using Combined Effects of Magnetostriction and Piezoelectricity

Directory of Open Access Journals (Sweden)

Guang Meng

2012-10-01

Full Text Available Precise displacement sensors are an important topic in precision engineering. At present, this type of sensors typically have a single feature of either translation or rotation measurement. They are also inconvenient to integrate with the host devices. In this report we propose a new kind of sensor that enables both translation and rotation measurement by using the combined effect of magnetostriction and piezoelectricity. As a proof of concept, we experimentally realized a prototype of non-contact translation-rotation precise sensor. In the current research stage, through both theoretical and experimental study, the non-contact displacement sensor is shown to be feasible for measuring both translation and rotation either in coarse or fine measurement. Moreover, owing to its compact, rigid structure and fewer components, it can be easily embedded in host equipment.

Analysis of Non-contact Acousto Thermal Signature Data (Postprint)

Science.gov (United States)

2016-02-01

AFRL-RX-WP-JA-2016-0321 ANALYSIS OF NON-CONTACT ACOUSTO-THERMAL SIGNATURE DATA (POSTPRINT) Amanda K. Criner AFRL/RX...October 2014 – 16 September 2015 4. TITLE AND SUBTITLE ANALYSIS OF NON-CONTACT ACOUSTO-THERMAL SIGNATURE DATA (POSTPRINT) 5a. CONTRACT NUMBER...words) The non-contact acousto-thermal signature (NCATS) is a nondestructive evaluation technique with potential to detect fatigue in materials such as

Quantitative sub-surface and non-contact imaging using scanning microwave microscopy

International Nuclear Information System (INIS)

Gramse, Georg; Kasper, Manuel; Hinterdorfer, Peter; Brinciotti, Enrico; Rankl, Christian; Kienberger, Ferry; Lucibello, Andrea; Marcelli, Romolo; Patil, Samadhan B.; Giridharagopal, Rajiv

2015-01-01

The capability of scanning microwave microscopy for calibrated sub-surface and non-contact capacitance imaging of silicon (Si) samples is quantitatively studied at broadband frequencies ranging from 1 to 20 GHz. Calibrated capacitance images of flat Si test samples with varying dopant density (10 15 –10 19 atoms cm −3 ) and covered with dielectric thin films of SiO 2 (100–400 nm thickness) are measured to demonstrate the sensitivity of scanning microwave microscopy (SMM) for sub-surface imaging. Using standard SMM imaging conditions the dopant areas could still be sensed under a 400 nm thick oxide layer. Non-contact SMM imaging in lift-mode and constant height mode is quantitatively demonstrated on a 50 nm thick SiO 2 test pad. The differences between non-contact and contact mode capacitances are studied with respect to the main parameters influencing the imaging contrast, namely the probe tip diameter and the tip–sample distance. Finite element modelling was used to further analyse the influence of the tip radius and the tip–sample distance on the SMM sensitivity. The understanding of how the two key parameters determine the SMM sensitivity and quantitative capacitances represents an important step towards its routine application for non-contact and sub-surface imaging. (paper)

Comparison of central corneal thickness with four noncontact devices: An agreement analysis of swept-source technology

OpenAIRE

Erhan Ozyol; Pelin Özyol

2017-01-01

Purpose: The purpose of this study was to compare the central corneal thickness (CCT) measurements of four noncontact devices in healthy eyes. Materials and Methods: In a sample of 45 healthy controls, CCT was measured using an optical biometer (IOLMaster 700) based on swept-source optical coherence tomography (SS-OCT), high-resolution rotating Scheimpflug camera system (Pentacam HR), spectral-domain OCT (SD-OCT) device with an anterior segment module (Spectralis), and noncontact pachymetry (...

Comparative study of three non-contact tonometers and the Goldmann tonometer.

Science.gov (United States)

Moreno-Montañés, J; Gómez-Demmel, E; Lajara-Blesa, J; Aliseda-Pérez de Madrid, D

1994-01-01

The main objective of this study was to find out how well three non-contact tonometers (Pulsair, Xpert-NCT and CT-20) compare with the Goldmann tonometer (GT). Sensitivity, specificity, positive and negative predictive values were all evaluated for an intraocular pressure (IOP) > or = 21 mm Hg. We also calculated the mean IOP, the correlation and the dispersion of the results. The difficulty in using the instruments, the patient's attitude and subjective comfort of IOP measuring were also evaluated. We describe the advantages and shortcomings of non-contact tonometers as screening tools to detect elevated IOP in the general population.

Nondestructive quality assurance of ceramic filters using noncontact dynamic characterization

Energy Technology Data Exchange (ETDEWEB)

Yue, P.; Chen, S.E.; Nishihama, Y. [University of Alabama, Birmingham, AL (United States). Dept. of Civil & Environmental Engineering

2005-06-01

Ceramic candle filters are stiff cylindrical structures arranged in rosettes in a hot gas vessel. Custom-made with strong composite materials, these filters are designed to withstand heating and cooling cycles of very high temperature gradients during coal energy production processes. To ensure consistency in the manufactured filters, noncontact dynamic characterization using laser vibrometry is proposed as a factory quality control technique. To evaluate the proposed technique, a sensitivity study using both contact and noncontact vibration measurements is first conducted. The shift in natural vibration frequencies is used as a quality indicator for likely manufacturing variables. Six candle filters are tested using dynamic impact tests. Contact and noncontact results are compared with theoretical natural frequency values, which show that laser results were 'noisier' due to dropout from speckle noises. The results are used to establish the sensitivity of the technique, which indicates that dynamic characterization is a valid nondestructive testing technique for quality assurance of the ceramic filters, provided that the manufactured filters have a quality variation greater than 3.21%.

Freeform optics: a non-contact "test plate" for manufacturing, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The goal of this NASA SBIR Phase I study is to determine the feasibility of measuring precision (fractional wave) freeform optics using non-contact areal (imaging)...

3D Blade Vibration Measurements on an 80 m Diameter Wind Turbine by Using Non-contact Remote Measurement Systems

Science.gov (United States)

Ozbek, Muammer; Rixen, Daniel J.

Non-contact optical measurement systems photogrammetry and laser interferometry are introduced as cost efficient alternatives to the conventional wind turbine/farm monitoring systems that are currently in use. The proposed techniques are proven to provide an accurate measurement of the dynamic behavior of a 2.5 MW—80 m diameter—wind turbine. Several measurements are taken on the test turbine by using 4 CCD cameras and 1 laser vibrometer and the response of the turbine is monitored from a distance of 220 m. The results of the infield tests and the corresponding analyses show that photogrammetry (also can be called as videogrammetry or computer vision technique) enable the 3D deformations of the rotor to be measured at 33 different points simultaneously with an average accuracy of ±25 mm, while the turbine is rotating. Several important turbine modes can also be extracted from the recorded data. Similarly, laser interferometry (used for the parked turbine only) provides very valuable information on the dynamic properties of the turbine structure. Twelve different turbine modes can be identified from the obtained response data.

Pulse electrochemical machining on Invar alloy: Optical microscopic/SEM and non-contact 3D measurement study of surface analyses

International Nuclear Information System (INIS)

Kim, S.H.; Choi, S.G.; Choi, W.K.; Yang, B.Y.; Lee, E.S.

2014-01-01

Highlights: • Invar alloy was electrochemically polished and then subjected to PECM (Pulse Electro Chemical Machining) in a mixture of NaCl, glycerin, and distilled water. • Optical microscopic/SEM and non-contact 3D measurement study of Invar surface analyses. • Analysis result shows that applied voltage and electrode shape are factors that affect the surface conditions. - Abstract: In this study, Invar alloy (Fe 63.5%, Ni 36.5%) was electrochemically polished by PECM (Pulse Electro Chemical Machining) in a mixture of NaCl, glycerin, and distilled water. A series of PECM experiments were carried out with different voltages and different electrode shapes, and then the surfaces of polished Invar alloy were investigated. The polished Invar alloy surfaces were investigated by optical microscope, scanning electron microscope (SEM), and non-contact 3D measurement (white light microscopes) and it was found that different applied voltages produced different surface characteristics on the Invar alloy surface because of the locally concentrated applied voltage on the Invar alloy surface. Moreover, we found that the shapes of electrode also have an effect on the surface characteristics on Invar alloy surface by influencing the applied voltage. These experimental findings provide fundamental knowledge for PECM of Invar alloy by surface analysis

3d noncontact humidity sensing technologies and methods of use thereof

KAUST Repository

Tai, Yanlong; Lubineau, Gilles

2017-01-01

Noncontact sensing components are provided herein, in an aspect, they can be for an electronic device. The noncontact sensing components can contain a semiconductor layer having a r-GO portion and a CNT portion. The noncontact sensing components can

Assessment of the accuracy and reliability of the Topcon CT80 non-contact tonometer.

Science.gov (United States)

Ogbuehi, Kelechi C

2006-09-01

The reliability of non-contact tonometers has been reported extensively in the literature. This study was designed to assess reliability of the new Topcon CT80 non-contact tonometer in normotensive subjects, using the Goldmann tonometer as the standard. The accuracy of the Topcon CT 80 non-contact tonometer was assessed by comparing its IOP assessments with those of the Goldmann applanation tonometer, on 60 right eyes of young healthy subjects with normal intraocular pressures. Each subject's intraocular pressure was assessed with each technique on two separate occasions, one week apart. The reliability of each technique was determined by the assessment of its inter-session repeatability using the Bland-Altman method. The 95 per cent limits of agreement for the two methods were also determined. No statistically significant difference was found between the average intraocular pressures measured with the two techniques (p > 0.05). The inter-session repeatability indices for the two techniques did not differ significantly (p > 0.05). The mean difference in intraocular measurements between the two techniques was 0.2 +/- 1.5 mmHg (mean +/- SD) and the 95 per cent limits of agreement were -3.14 and +2.74 mmHg, with the non-contact tonometer returning higher readings than the Goldmann tonometer. In this sample of normotensive subjects, the Topcon CT80 non-contact tonometer proved to be accurate and as reliable as the Goldmann tonometer in the assessment of intraocular pressure. Thus, it can be used as an objective clinical method for the assessment of normal intraocular pressure.

Incidence of open-angle glaucoma and screening of the intraocular pressure with a non-contact tonometer.

Science.gov (United States)

Rouhiainen, H; Teräsvirta, M

1990-06-01

New equipment for measuring intraocular pressure have been introduced lately. One of these is the Keeler Pulsair non-contact tonometer which uses pressurized air in measurement. It is found to be safe and easy to use in practice, but it seems to give 1.5-2.0 mmHg lower reading than the Goldmann applanation tonometer. This was confirmed by the present study, where non-contact tonometry was controlled by applanation tonometry with a 2-3 week delay between the measurements. However, for screening procedures the accuracy of the apparatus can be considered as sufficient.

EPro Non-contact erosion profiling

DEFF Research Database (Denmark)

Meinert, Palle

Pro is a profiling program build to measure the same surface or work piece multiple times and track changes due to erosion. It was developed during 2001 - 2002 at Aalborg University and was part of a Master of Science project dealing with stability of rubble mound breakwaters. The goal was to aut......Pro is a profiling program build to measure the same surface or work piece multiple times and track changes due to erosion. It was developed during 2001 - 2002 at Aalborg University and was part of a Master of Science project dealing with stability of rubble mound breakwaters. The goal...... was to automate the measuring of profiles in order to save manpower and to increase the number of possible measure points. Additional requirement was that measurements should be done in a non-contact way and that the measuring should not be hindered by the presence of water....

The influence of central corneal thickness and age on intraocular pressure measured by pneumotonometry, non-contact tonometry, the Tono-Pen XL, and Goldmann applanation tonometry

OpenAIRE

Tonnu, P-A; Ho, T; Newson, T; El Sheikh, A; Sharma, K; White, E; Bunce, C; Garway-Heath, D

2005-01-01

Aims: To evaluate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements made with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT).

Non-contact temperature Raman measurement in YSZ and alumina ceramics

Science.gov (United States)

Thapa, Juddha; Chorpening, Benjamin T.; Buric, Michael P.

2018-02-01

Yttria-stabilized zirconia (YSZ: ZrO2 + Y2O3) and alumina (Al2O3) are widely used in high-temperature applications due to their high-temperature stability, low thermal conductivity, and chemical inertness. Alumina is used extensively in engineered ceramic applications such as furnace tubes and thermocouple protection tubes, while YSZ is commonly used in thermal barrier coatings on turbine blades. Because they are already often found in high temperature and combustion applications, these two substances have been compared as candidates for Raman thermometry in high-temperature energy-related applications. Both ceramics were used with as-received rough surfaces, i.e., without polishing or modification. This closely approximates surface conditions in practical high-temperature situations. A single-line argon ion laser at 488nm was used to excite the materials inside a cylindrical furnace while measuring Raman spectra with a fixed-grating spectrometer. The shift in the peak positions of the most intense A1g peak at 418cm-1 (room temperature position) of alumina ceramic and relatively more symmetric Eg peak at 470cm-1 (room temperature position) of YSZ were measured and reported along with a thermocouple-derived reference temperature up to about 1000°C. This study showed that alumina and YSZ ceramics can be used in high-temperature Raman thermometry with an accuracy of 4.54°C and 10.5°C average standard deviations respectively over the range of about 1000°C. We hope that this result will guide future researchers in selecting materials and utilizing Raman non-contact temperature measurements in harsh environments.

3d noncontact humidity sensing technologies and methods of use thereof

KAUST Repository

Tai, Yanlong

2017-09-08

Noncontact sensing components are provided herein, in an aspect, they can be for an electronic device. The noncontact sensing components can contain a semiconductor layer having a r-GO portion and a CNT portion. The noncontact sensing components can be used to detect the presence or movement of a humidity source in the vicinity of the noncontact sensing component. The resistance/humidity response of the component can be based on the combined contribution of carbon nanotube (positive resistance variation) and reduced-graphene oxide (negative resistance variation) behaviors.

COMPARISON OF INTRAOCULAR PRESSURE MEASUREMENT WITH NON-CONTACT TONOMETRY AND APPLANATION TONOMETRY AMONG VARIOUS CENTRAL CORNEAL THICKNESS GROUPS

Directory of Open Access Journals (Sweden)

Radhakrishnan B

2018-02-01

Full Text Available BACKGROUND Glaucoma is the second leading cause of blindness worldwide. Intraocular Pressure (IOP is the only known modifiable risk factor that has been shown to delay progression in both ocular hypertension and glaucoma patients. Clinical measurement of IOP has undergone several technical advances from the initial digital tension measurements, through indentation tonometry, to applanation tonometry and non-contact tonometry. This study was done to compare the intraocular pressure (IOP measurements with Non Contact Tonometry (NCT and Goldmann Applanation tonometry (GAT and to compare NCT IOP and GAT IOP among various central corneal thickness (CCT groups. MATERIALS AND METHODS IOP measurements were done by NCT and then by GAT followed by CCT. All IOP readings were taken in the sitting position over fifteen minutes. NCT was performed before the GAT to avoid the known mild reduction of IOP by anterior chamber compression with GAT. RESULTS The study included 200 eyes of 100 patients. Mean age of the patients was 58.14 ± 11.7 years (range 35- 81 years. The study population consisted of 58 males and 42 females. The mean ± SD intraocular pressure measurements were 23.39 ± 4.6 mmHg and 22.41 ± 5.9 mmHg for NCT and GAT, respectively. The difference between the NCT and GAT IOP was 0.98 ± 4.7 mm Hg. Mean CCT of the study group was 545.74 ± 38.23 microns. The IOP measured with both GAT and NCT showed no significant change with increasing CCT. The difference between the means increases with increasing CCT upto 600 microns. At lower IOPs ≤ 20 mm Hg, GAT measures are higher than NCT and this relationship is reversed at high IOPs. CONCLUSION Intraocular pressure measurement by NCT was consistently higher than GAT. There was a tendency for NCT to underestimate IOP at lower ranges and overestimates IOP at higher ranges. By applying appropriate correction factor for CCT, Noncontact tonometry could be used as a good screening tool for glaucoma evaluation.

Analysis of non-contact and contact probe-to-sample thermal exchange for quantitative measurements of thin film and nanostructure thermal conductivity by the scanning hot probe method

Science.gov (United States)

Wilson, Adam A.

The ability to measure thermal properties of thin films and nanostructured materials is an important aspect of many fields of academic study. A strategy especially well-suited for nanoscale investigations of these properties is the scanning hot probe technique, which is unique in its ability to non-destructively interrogate the thermal properties with high resolution, both laterally as well as through the thickness of the material. Strategies to quantitatively determine sample thermal conductivity depend on probe calibration. State of the art calibration strategies assume that the area of thermal exchange between probe and sample does not vary with sample thermal conductivity. However, little investigation has gone into determining whether or not that assumption is valid. This dissertation provides a rigorous study into the probe-to-sample heat transfer through the air gap at diffusive distances for a variety of values of sample thermal conductivity. It is demonstrated that the thermal exchange radius and gap/contact thermal resistance varies with sample thermal conductivity as well as tip-to-sample clearance in non-contact mode. In contact mode, it is demonstrated that higher thermal conductivity samples lead to a reduction in thermal exchange radius for Wollaston probe tips. Conversely, in non-contact mode and in contact mode for sharper probe tips where air contributes the most to probe-to-sample heat transfer, the opposite trend occurs. This may be attributed to the relatively strong solid-to-solid conduction occurring between probe and sample for the Wollaston probes. A three-dimensional finite element (3DFE) model was developed to investigate how the calibrated thermal exchange parameters vary with sample thermal conductivity when calibrating the probe via the intersection method in non-contact mode at diffusive distances. The 3DFE model was then used to explore the limits of sensitivity of the experiment for a range of simulated experimental conditions. It

Dynamic contour tonometry vs. non-contact tonometry and their relation with corneal thickness

OpenAIRE

Briceño, Adriana; Mas, David; Domenech, Begoña

2016-01-01

The purpose of this study is to evaluate the concordance between intraocular pressure (IOP) values obtained with a dynamic contour tonometer (DCT) and a non-contact tonometer (NCT) in healthy patients and to investigate the effect of central corneal thickness (CCT) on IOP readings for each of the two measuring systems. The mean IOP yielded by DCT, NCT and corrected non-contact tonometer (CNCT) was 17.1 mmHg, 15.5 mmHg and 12.2 mmHg, respectively. The average CCT was 563.6 μm and the ocular pu...

Development of a high cycle vibration fatigue diagnostic system with non-contact vibration sensing

International Nuclear Information System (INIS)

Yoshitsugu, Nekomoto; Satoshi, Kiriyama; Moritatsu, Nishimura; Kenji, Matsumoto; Eiji, O'shima

2001-01-01

Nuclear power plants have a large number of pipes. Of these small-diameter pipe branches in particular are often damaged due to high-cycle fatigue. In order to ensure the reliability of a plant it is important to detect the fatigues in pipe branches at an early stage and to develop the technology to predict and diagnose the advancement of fatigue. Further, in order to carry out the diagnosis of the piping system effectively during operation, non-contact evaluation is useful. Hence, we have developed a 'high-cycle fatigue diagnostic system with non-contact vibration sensing', where the vibration of the pipe branch is measured using a non-contact sensor. Since the contents of the developed sensor technology has already been reported, this paper mainly describes the newly developed high-cycle fatigue diagnostic system. (authors)

Noncontact measurement of high temperature using optical fiber sensors

Science.gov (United States)

Claus, R. O.

1990-01-01

The primary goal of this research program was the investigation and application of noncontact temperature measurement techniques using optical techniques and optical fiber methods. In particular, a pyrometer utilizing an infrared optical light pipe and a multiwavelength filtering approach was designed, revised, and tested. This work was motivated by the need to measure the temperatures of small metallic pellets (approximately 3 mm diameter) in free fall at the Microgravity Materials Processing Drop Tube at NASA Marshall Space Flight Center. In addition, research under this program investigated the adaptation of holography technology to optical fiber sensors, and also examined the use of rare-earth dopants in optical fibers for use in measuring temperature. The pyrometer development effort involved both theoretical analysis and experimental tests. For the analysis, a mathematical model based on radiative transfer principles was derived. Key parameter values representative of the drop tube system, such as particle size, tube diameter and length, and particle temperature, were used to determine an estimate of the radiant flux that will be incident on the face of an optical fiber or light pipe used to collect radiation from the incandescent falling particle. An extension of this work examined the advantage of inclining or tilting the collecting fiber to increase the time that the falling particle remains in the fiber field-of-view. Those results indicate that increases in total power collected of about 15 percent may be realized by tilting the fiber. In order to determine the suitability of alternative light pipes and optical fibers, and experimental set-up for measuring the transmittance and insertion loss of infrared fibers considered for use in the pyrometer was assembled. A zirconium fluoride optical fiber and several bundles of hollow core fiber of varying diameters were tested. A prototype two-color pyrometer was assembled and tested at Virginia Tech, and then

Dynamic torsional response analysis of mechanoluminescent paint and its application to non-contacting automotive torque transducers

International Nuclear Information System (INIS)

Kim, Gi-Woo; Kim, Ji-Sik

2014-01-01

This paper presents the result of a preliminary experimental study on the dynamic torsional response analysis of mechanoluminescent (ML) paint for potential development as a new type of non-contacting torque transducer. The torsional torque applied to a transmission shaft is measured by sensing the ML intensity emitting from an ML paint coating a transmission shaft. This study provides the fundamental knowledge for the development of new non-contacting torque sensing technology based on the ML intensity detection. The proposed measurement principle appears to offer potential applications in automotive torque measurement systems, even though the loading rate-dependent characteristics of the ML intensity needs to be examined further. (paper)

Dynamic torsional response analysis of mechanoluminescent paint and its application to non-contacting automotive torque transducers

Science.gov (United States)

Kim, Gi-Woo; Kim, Ji-Sik

2014-01-01

This paper presents the result of a preliminary experimental study on the dynamic torsional response analysis of mechanoluminescent (ML) paint for potential development as a new type of non-contacting torque transducer. The torsional torque applied to a transmission shaft is measured by sensing the ML intensity emitting from an ML paint coating a transmission shaft. This study provides the fundamental knowledge for the development of new non-contacting torque sensing technology based on the ML intensity detection. The proposed measurement principle appears to offer potential applications in automotive torque measurement systems, even though the loading rate-dependent characteristics of the ML intensity needs to be examined further.

The high-sensitive magnetic levitated electrode ionization chamber of the noncontacting type

International Nuclear Information System (INIS)

Kawaguchi, Toshiro; Yoshimura, Atsushi

1999-01-01

There are two types of ionization chamber using magnetically levitated electrode: one is that by Tanaka et al. and the other, by authors'. The latter lacks the sensitivity relative to the former and thereby to solve the problem, authors made an improvement so that the electrode charge could be readout by noncontact after the leviated electrode was electrified by noncontact for an interval. This new type ionization chamber made it possible to measure the quite low dose radiation with stability and high sensitivity. Actually, the electrode was suspended by the teflon thread fixed on the steel cup levitated magnetically in the ionization chamber of which wall was covered by Al and equipped with an electrostatic charger for the electrode by noncontact. After measurement, the electrode was moved in the Faraday cage placed under the chamber to readout the voltage. For operation conditions of the apparatus, observation was done on the relationship between ionization current by 137 Cs and the applied voltage. For actual measurement, ionizations by low dose γ ray derived from KCl which containing 40 K in a small amount and by Rn at the fine and rainy days were measured. The exposure rate by KCl (500 g bottle) was found to be 12.7 x 10 -10 C/kg·h with the background value of 9.8 x 10 -10 . Rn concentrations in the air were 112.3 and 18.34 Bq/m 3 for 1 hr in the rainy and fine day, respectively, in Fukuoka City. (K.H.)

Detection of driving fatigue by using noncontact EMG and ECG signals measurement system.

Science.gov (United States)

Fu, Rongrong; Wang, Hong

2014-05-01

Driver fatigue can be detected by constructing a discriminant mode using some features obtained from physiological signals. There exist two major challenges of this kind of methods. One is how to collect physiological signals from subjects while they are driving without any interruption. The other is to find features of physiological signals that are of corresponding change with the loss of attention caused by driver fatigue. Driving fatigue is detected based on the study of surface electromyography (EMG) and electrocardiograph (ECG) during the driving period. The noncontact data acquisition system was used to collect physiological signals from the biceps femoris of each subject to tackle the first challenge. Fast independent component analysis (FastICA) and digital filter were utilized to process the original signals. Based on the statistical analysis results given by Kolmogorov-Smirnov Z test, the peak factor of EMG (p fatigue of drivers. The discriminant criterion of fatigue was obtained from the training samples by using Mahalanobis distance, and then the average classification accuracy was given by 10-fold cross-validation. The results showed that the method proposed in this paper can give well performance in distinguishing the normal state and fatigue state. The noncontact, onboard vehicle drivers' fatigue detection system was developed to reduce fatigue-related risks.

Non-contact evaluation of milk-based products using air-coupled ultrasound

Science.gov (United States)

Meyer, S.; Hindle, S. A.; Sandoz, J.-P.; Gan, T. H.; Hutchins, D. A.

2006-07-01

An air-coupled ultrasonic technique has been developed and used to detect physicochemical changes of liquid beverages within a glass container. This made use of two wide-bandwidth capacitive transducers, combined with pulse-compression techniques. The use of a glass container to house samples enabled visual inspection, helping to verify the results of some of the ultrasonic measurements. The non-contact pulse-compression system was used to evaluate agglomeration processes in milk-based products. It is shown that the amplitude of the signal varied with time after the samples had been treated with lactic acid, thus promoting sample destabilization. Non-contact imaging was also performed to follow destabilization of samples by scanning in various directions across the container. The obtained ultrasonic images were also compared to those from a digital camera. Coagulation with glucono-delta-lactone of skim milk poured into this container could be monitored within a precision of a pH of 0.15. This rapid, non-contact and non-destructive technique has shown itself to be a feasible method for investigating the quality of milk-based beverages, and possibly other food products.

Contact Versus Non-Contact Measurement of a Helicopter Main Rotor Composite Blade

Science.gov (United States)

Luczak, Marcin; Dziedziech, Kajetan; Vivolo, Marianna; Desmet, Wim; Peeters, Bart; Van der Auweraer, Herman

2010-05-01

The dynamic characterization of lightweight structures is particularly complex as the impact of the weight of sensors and instrumentation (cables, mounting of exciters…) can distort the results. Varying mass loading or constraint effects between partial measurements may determine several errors on the final conclusions. Frequency shifts can lead to erroneous interpretations of the dynamics parameters. Typically these errors remain limited to a few percent. Inconsistent data sets however can result in major processing errors, with all related consequences towards applications based on the consistency assumption, such as global modal parameter identification, model-based damage detection and FRF-based matrix inversion in substructuring, load identification and transfer path analysis [1]. This paper addresses the subject of accuracy in the context of the measurement of the dynamic properties of a particular lightweight structure. It presents a comprehensive comparative study between the use of accelerometer, laser vibrometer (scanning LDV) and PU-probe (acoustic particle velocity and pressure) measurements to measure the structural responses, with as final aim the comparison of modal model quality assessment. The object of the investigation is a composite material blade from the main rotor of a helicopter. The presented results are part of an extensive test campaign performed with application of SIMO, MIMO, random and harmonic excitation, and the use of the mentioned contact and non-contact measurement techniques. The advantages and disadvantages of the applied instrumentation are discussed. Presented are real-life measurement problems related to the different set up conditions. Finally an analysis of estimated models is made in view of assessing the applicability of the various measurement approaches for successful fault detection based on modal parameters observation as well as in uncertain non-deterministic numerical model updating.

Contact Versus Non-Contact Measurement of a Helicopter Main Rotor Composite Blade

International Nuclear Information System (INIS)

Luczak, Marcin; Dziedziech, Kajetan; Peeters, Bart; Van der Auweraer, Herman; Vivolo, Marianna; Desmet, Wim

2010-01-01

The dynamic characterization of lightweight structures is particularly complex as the impact of the weight of sensors and instrumentation (cables, mounting of exciters...) can distort the results. Varying mass loading or constraint effects between partial measurements may determine several errors on the final conclusions. Frequency shifts can lead to erroneous interpretations of the dynamics parameters. Typically these errors remain limited to a few percent. Inconsistent data sets however can result in major processing errors, with all related consequences towards applications based on the consistency assumption, such as global modal parameter identification, model-based damage detection and FRF-based matrix inversion in substructuring, load identification and transfer path analysis [1]. This paper addresses the subject of accuracy in the context of the measurement of the dynamic properties of a particular lightweight structure. It presents a comprehensive comparative study between the use of accelerometer, laser vibrometer (scanning LDV) and PU-probe (acoustic particle velocity and pressure) measurements to measure the structural responses, with as final aim the comparison of modal model quality assessment. The object of the investigation is a composite material blade from the main rotor of a helicopter. The presented results are part of an extensive test campaign performed with application of SIMO, MIMO, random and harmonic excitation, and the use of the mentioned contact and non-contact measurement techniques. The advantages and disadvantages of the applied instrumentation are discussed. Presented are real-life measurement problems related to the different set up conditions. Finally an analysis of estimated models is made in view of assessing the applicability of the various measurement approaches for successful fault detection based on modal parameters observation as well as in uncertain non-deterministic numerical model updating.

Methodology to measure strains at high temperatures using electrical strain gages with free filaments

International Nuclear Information System (INIS)

Atanazio Filho, Nelson N.; Gomes, Paulo T. Vida; Scaldaferri, Denis H.B.; Silva, Luiz L. da; Rabello, Emerson G.; Mansur, Tanius R.

2013-01-01

An experimental methodology used for strains measuring at high temperatures is show in this work. In order to do the measurements, it was used electric strain gages with loose filaments attached to a stainless steel 304 beam with specific cements. The beam has triangular shape and a constant thickness, so the strain is the same along its length. Unless the beam surface be carefully prepared, the strain gage attachment is not efficient. The showed results are for temperatures ranging from 20 deg C to 300 deg C, but the experimental methodology could be used to measure strains at a temperature up to 900 deg C. Analytical calculations based on solid mechanics were used to verify the strain gage electrical installation and the measured strains. At a first moment, beam deformations as a temperature function were plotted. After that, beam deformations with different weighs were plotted as a temperature function. The results shown allowed concluding that the experimental methodology is trustable to measure strains at temperatures up to 300 deg C. (author)

Instrument for measuring fuel cladding strain

International Nuclear Information System (INIS)

Billeter, T.R.

1976-01-01

Development work to provide instrumentation for the continuous measurement of strain of material specimens such as nuclear fuel cladding has shown that a microwave sensor and associated instrumentation hold promise. The cylindrical sensor body enclosing the specimen results in a coaxial resonator absorbing microwave energy at frequencies dependent upon the diameter of the specimen. Diametral changes of a microinch can be resolved with use of the instrumentation. Very reasonable values of elastic strain were measured at 75 0 F and 1000 0 F for an internally pressurized 20 percent C.W. 316 stainless steel specimen simulating nuclear fuel cladding. The instrument also indicated the creep strain of the same specimen pressurized at 6500 psi and at a temperature of 1000 0 F for a period of 700 hours. Although the indicated strain appears greater than actual, the sensor/specimen unit experienced considerable oxidation even though an inert gas purge persisted throughout the test duration. By monitoring at least two modes of resonance, the measured strain was shown to be nearly independent of sensor temperature. To prevent oxidation, a second test was performed in which the specimen/sensor units were contained in an evacuated enclosure. The strain of the two prepressurized specimens as indicated by the microwave instrumentation agreed very closely with pre- and post-test measurements obtained with use of a laser interferometer

Sequence of oral bacterial co-adhesion and non-contact brushing

NARCIS (Netherlands)

van der Mei, H. C.; Rustema-Abbing, M.; Bruinsma, G. M.; Gottenbos, B.; Busscher, H. J.

Non-contact plaque removal offers advantages in interproximal spaces, fissures, and pockets. It requires the generation of strong fluid flows and the inclusion of air bubbles to become effective. A pair of co-adhering streptococci and actinomyces has been used previously to demonstrate non-contact

Applanation optical coherence elastography: noncontact measurement of intraocular pressure, corneal biomechanical properties, and corneal geometry with a single instrument

Science.gov (United States)

Singh, Manmohan; Han, Zhaolong; Nair, Achuth; Schill, Alexander; Twa, Michael D.; Larin, Kirill V.

2017-02-01

Current clinical tools provide critical information about ocular health such as intraocular pressure (IOP). However, they lack the ability to quantify tissue material properties, which are potent markers for ocular tissue health and integrity. We describe a single instrument to measure the eye-globe IOP, quantify corneal biomechanical properties, and measure corneal geometry with a technique termed applanation optical coherence elastography (Appl-OCE). An ultrafast OCT system enabled visualization of corneal dynamics during noncontact applanation tonometry and direct measurement of micro air-pulse induced elastic wave propagation. Our preliminary results show that the proposed Appl-OCE system can be used to quantify IOP, corneal biomechanical properties, and corneal geometry, which builds a solid foundation for a unique device that can provide a more complete picture of ocular health.

Non-contact optoacoustic imaging with focused air-coupled transducers

Energy Technology Data Exchange (ETDEWEB)

Deán-Ben, X. Luís [Institute for Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Neuherberg (Germany); Pang, Genny A.; Razansky, Daniel, E-mail: dr@tum.de [Institute for Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Neuherberg (Germany); School of Medicine, Technische Universität München (TUM), Munich (Germany); Montero de Espinosa, Francisco [CSIC, Institute of Physics and Communication Technologies, Madrid (Spain)

2015-08-03

Non-contact optoacoustic imaging employing raster-scanning of a spherically focused air-coupled ultrasound transducer is showcased herein. Optoacoustic excitation with laser fluence within the maximal permissible human exposure limits in the visible and near-infrared spectra is applied to objects with characteristic dimensions smaller than 1 mm and absorption properties representative of the whole blood at near-infrared wavelengths, and these signals are shown to be detectable without contact to the sample using an air-coupled transducer with reasonable signal averaging. Optoacoustic images of vessel-mimicking tubes embedded in an agar phantom captured with this non-contact sensing technique are also showcased. These initial results indicate that an air-coupled ultrasound detection approach can be suitable for non-contact biomedical imaging with optoacoustics.

Strain measurement on a compact nuclear reactor steam generator

International Nuclear Information System (INIS)

Scaldaferri, Denis Henrique Bianchi; Gomes, Paulo de Tarso Vida; Mansur, Tanius Rodrigues; Pozzo, Renato del; Mola, Jairo

2011-01-01

This work presents the strain measurement procedures applied to a compact nuclear reactor steam generator, during a hydrostatic test, using strain gage technology. The test was divided in two steps: primary side test and secondary side test. In the primary side test twelve points for strain measurement using rectangular rosettes, three points (two external and one internal) for temperature measurement using special strain gages and one point for pressure measurement using a pressure transducer were monitored. In the secondary side test 18 points for strain measurement using rectangular rosettes, four points (two external and two internal) for temperature measurement using special strain gages and one point for pressure measurement using a pressure transducer were monitored. The measurement points on both internal and external pressurizer walls were established from pre-calculated stress distribution by means of numerical approach (finite elements modeling). Strain values using a quarter Wheatstone bridge circuit were obtained. Stress values, from experimental strain were determined, and to numerical calculation results were compared. (author)

Non-contact finger vein acquisition system using NIR laser

Science.gov (United States)

Kim, Jiman; Kong, Hyoun-Joong; Park, Sangyun; Noh, SeungWoo; Lee, Seung-Rae; Kim, Taejeong; Kim, Hee Chan

2009-02-01

Authentication using finger vein pattern has substantial advantage than other biometrics. Because human vein patterns are hidden inside the skin and tissue, it is hard to forge vein structure. But conventional system using NIR LED array has two drawbacks. First, direct contact with LED array raise sanitary problem. Second, because of discreteness of LEDs, non-uniform illumination exists. We propose non-contact finger vein acquisition system using NIR laser and Laser line generator lens. Laser line generator lens makes evenly distributed line laser from focused laser light. Line laser is aimed on the finger longitudinally. NIR camera was used for image acquisition. 200 index finger vein images from 20 candidates are collected. Same finger vein pattern extraction algorithm was used to evaluate two sets of images. Acquired images from proposed non-contact system do not show any non-uniform illumination in contrary with conventional system. Also results of matching are comparable to conventional system. We developed Non-contact finger vein acquisition system. It can prevent potential cross contamination of skin diseases. Also the system can produce uniformly illuminated images unlike conventional system. With the benefit of non-contact, proposed system shows almost equivalent performance compared with conventional system.

SensInDenT-Noncontact Sensors Integrated Into Dental Treatment Units.

Science.gov (United States)

Teichmann, Daniel; Teichmann, Maren; Weitz, Philippe; Wolfart, Stefan; Leonhardt, Steffen; Walter, Marian

2017-02-01

This paper presents the first system design (SensInDenT) for noncontact cardiorespiratory monitoring during dental treatment. The system is integrated into a dental treatment unit, and combines sensors based on electromagnetic, optical, and mechanical coupling at different sensor locations. The measurement principles and circuits are described and a system overview is presented. Furthermore, a first proof of concept is provided by taking measurements in healthy volunteers under laboratory conditions.

Clinical performance of the Reichert AT550: a new non-contact tonometer.

Science.gov (United States)

Jorge, J; Díaz-Rey, J A; González-Méijome, J M; Almeida, J B; Parafita, M A

2002-11-01

The aim of the present study was to assess the level of accuracy for measurements of intra-ocular pressure (IOP) obtained with a new non-contact tonometer (NCT) the Reichert AT550. Measurements were compared against those obtained with the Reichert Xpert Plus, Goldmann applanation tonometer and Perkins tonometer. Thirty-five university students were assessed with the four tonometers in a randomised order, with non-contact tonometry performed first. Each of the four measurement devices had its own trained clinical observer. Plots of differences of IOP as a function of the mean for each pair of instruments were obtained. No statistically significant differences were found when comparing the AT550 NCT with contact applanation tonometry (AT) (p> 0.05), displaying the closest level of agreement (as represented by the lowest mean difference and the narrowest confidence interval) with the Goldmann tonometer (limits of agreement, 0.12+/-2.17). In conclusion, readings of IOP with the AT550 NCT are clinically comparable with those obtained with Goldmann tonometry in a population with IOP within the normal range.

Thermal strain measurement of EAST W/Cu divertor structure using electric resistance strain gauges

Energy Technology Data Exchange (ETDEWEB)

Wang, Xingli [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Wang, Wanjing, E-mail: wjwang@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Wang, Jichao [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Wei, Ran; Sun, Zhaoxuan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Li, Qiang; Xie, Chunyi [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Chen, Hong-En; Wang, Kaiqiang; Wu, Lei; Chen, Zhenmao [State Key Lab for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University (China); Luo, Guang-Nan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Science Island Branch of Graduate School, University of Science & Technology of China, Hefei, 230031 (China); Hefei Center for Physical Science and Technology, Hefei, 230022 (China); Hefei Science Center of Chinese Academy of Sciences, Hefei, 230027 (China)

2016-12-15

Highlights: • To understand the service behavior of W/Cu divertor, an electrical resistance strain gauge system had been introduced in a thermal strain measurement experiment. • The measurement system successfully finished the experiment and obtained valued thermal strain data. • Two thermomechanical analyses had also been carried out and compared with the measurement results. • Experiment results corresponded well to simulations and threw a light upon the failure of W/Cu divertor in the previous baking tests. - Abstract: W/Cu divertor has complex structure and faces extreme work environment in EAST Tokamak device. To measure its thermal strain shall be a valued way to understand its service behavior and then optimize its design and manufacturing process. This work presents a preliminary study on measuring thermal strain of EAST W/Cu divertor structure using electric resistance strain gauges. Eight gauges had been used in the experiment and the heating temperature had been set to 230 °C with respect to the work temperature. To realize the measuring experiment, an appropriate fixing method of gauges in divertor narrow spaces had been taken and tested, which could not only withstand high temperature but also had no damage to the divertor sample. The measurement results were that three gauges showed positive strain while other three showed negative strain after having been compensated, which corresponded to tensile stress and compressed stress respectively. Two thermomechanical simulations had also been carried out and used for comparing with the experiment.

Creep Measurement Video Extensometer

Science.gov (United States)

Jaster, Mark; Vickerman, Mary; Padula, Santo, II; Juhas, John

2011-01-01

Understanding material behavior under load is critical to the efficient and accurate design of advanced aircraft and spacecraft. Technologies such as the one disclosed here allow accurate creep measurements to be taken automatically, reducing error. The goal was to develop a non-contact, automated system capable of capturing images that could subsequently be processed to obtain the strain characteristics of these materials during deformation, while maintaining adequate resolution to capture the true deformation response of the material. The measurement system comprises a high-resolution digital camera, computer, and software that work collectively to interpret the image.

[Comparative study of intraocular pressure measurements by Goldmann applanation tonometer, noncontact tonometer and TonoPen].

Science.gov (United States)

Ceská, Burdová M; Ferrová, K; Filous, A; Oskorypová, K; Lezatková, P; Sedlácková, P

2012-02-01

The purpose of the study was to compare the levels of the intraocular pressure (NOT) measured in one eye at the same moment by three different methods: by Goldmann applanation tonometer (AT), non-contact tonometer (BT) and Tono-Pen (TP). It was further set the average variability of the performed measurements for particular tonometric methods. NOT was assessed in 106 eyes of 106 subjects aged 7-77 years (average 34.3 +/- 17.1 years). NOT was measured at the same moment with BT, TP and AT. The obtained data were statistically analyzed. The average NOT was 16.55 +/- 2.95, 17.95 +/- 4.47 and 16.13 +/- 3.4 mmHg when AT, BT and TP were applied. Average variability of three measurements for AT, BT and TP was 1.51 +/- 0.96, 1.78 +/- 1.08 and 1.47 +/- 0.9 mmHg. Average NOT levels of the measured AT and TP were almost identical with a difference of 0.42 mmHg (p = 0.236). Average level of the intraocular pressure measured by BT was higher by 1.40 mmHg and 1.82 mmHg in comparison with AT and TP (p = 0.00002), respectively. NOT measurement produced almost identical average levels at AT and TP, whereas at BT the levels were much higher. Average variability of the three subsequent NOT measurements was the highest at BT, whereas at AT and TP the average variability was lower and nearly identical.

Simultaneous epicardial and noncontact endocardial mapping of the canine right atrium: simulation and experiment.

Science.gov (United States)

Sabouri, Sepideh; Matene, Elhacene; Vinet, Alain; Richer, Louis-Philippe; Cardinal, René; Armour, J Andrew; Pagé, Pierre; Kus, Teresa; Jacquemet, Vincent

2014-01-01

Epicardial high-density electrical mapping is a well-established experimental instrument to monitor in vivo the activity of the atria in response to modulations of the autonomic nervous system in sinus rhythm. In regions that are not accessible by epicardial mapping, noncontact endocardial mapping performed through a balloon catheter may provide a more comprehensive description of atrial activity. We developed a computer model of the canine right atrium to compare epicardial and noncontact endocardial mapping. The model was derived from an experiment in which electroanatomical reconstruction, epicardial mapping (103 electrodes), noncontact endocardial mapping (2048 virtual electrodes computed from a 64-channel balloon catheter), and direct-contact endocardial catheter recordings were simultaneously performed in a dog. The recording system was simulated in the computer model. For simulations and experiments (after atrio-ventricular node suppression), activation maps were computed during sinus rhythm. Repolarization was assessed by measuring the area under the atrial T wave (ATa), a marker of repolarization gradients. Results showed an epicardial-endocardial correlation coefficients of 0.80 and 0.63 (two dog experiments) and 0.96 (simulation) between activation times, and a correlation coefficients of 0.57 and 0.46 (two dog experiments) and 0.92 (simulation) between ATa values. Despite distance (balloon-atrial wall) and dimension reduction (64 electrodes), some information about atrial repolarization remained present in noncontact signals.

Simultaneous epicardial and noncontact endocardial mapping of the canine right atrium: simulation and experiment.

Directory of Open Access Journals (Sweden)

Sepideh Sabouri

Full Text Available Epicardial high-density electrical mapping is a well-established experimental instrument to monitor in vivo the activity of the atria in response to modulations of the autonomic nervous system in sinus rhythm. In regions that are not accessible by epicardial mapping, noncontact endocardial mapping performed through a balloon catheter may provide a more comprehensive description of atrial activity. We developed a computer model of the canine right atrium to compare epicardial and noncontact endocardial mapping. The model was derived from an experiment in which electroanatomical reconstruction, epicardial mapping (103 electrodes, noncontact endocardial mapping (2048 virtual electrodes computed from a 64-channel balloon catheter, and direct-contact endocardial catheter recordings were simultaneously performed in a dog. The recording system was simulated in the computer model. For simulations and experiments (after atrio-ventricular node suppression, activation maps were computed during sinus rhythm. Repolarization was assessed by measuring the area under the atrial T wave (ATa, a marker of repolarization gradients. Results showed an epicardial-endocardial correlation coefficients of 0.80 and 0.63 (two dog experiments and 0.96 (simulation between activation times, and a correlation coefficients of 0.57 and 0.46 (two dog experiments and 0.92 (simulation between ATa values. Despite distance (balloon-atrial wall and dimension reduction (64 electrodes, some information about atrial repolarization remained present in noncontact signals.

Simultaneous Epicardial and Noncontact Endocardial Mapping of the Canine Right Atrium: Simulation and Experiment

Science.gov (United States)

Sabouri, Sepideh; Matene, Elhacene; Vinet, Alain; Richer, Louis-Philippe; Cardinal, René; Armour, J. Andrew; Pagé, Pierre; Kus, Teresa; Jacquemet, Vincent

2014-01-01

Epicardial high-density electrical mapping is a well-established experimental instrument to monitor in vivo the activity of the atria in response to modulations of the autonomic nervous system in sinus rhythm. In regions that are not accessible by epicardial mapping, noncontact endocardial mapping performed through a balloon catheter may provide a more comprehensive description of atrial activity. We developed a computer model of the canine right atrium to compare epicardial and noncontact endocardial mapping. The model was derived from an experiment in which electroanatomical reconstruction, epicardial mapping (103 electrodes), noncontact endocardial mapping (2048 virtual electrodes computed from a 64-channel balloon catheter), and direct-contact endocardial catheter recordings were simultaneously performed in a dog. The recording system was simulated in the computer model. For simulations and experiments (after atrio-ventricular node suppression), activation maps were computed during sinus rhythm. Repolarization was assessed by measuring the area under the atrial T wave (ATa), a marker of repolarization gradients. Results showed an epicardial-endocardial correlation coefficients of 0.80 and 0.63 (two dog experiments) and 0.96 (simulation) between activation times, and a correlation coefficients of 0.57 and 0.46 (two dog experiments) and 0.92 (simulation) between ATa values. Despite distance (balloon-atrial wall) and dimension reduction (64 electrodes), some information about atrial repolarization remained present in noncontact signals. PMID:24598778

Apt strain measurement technique for impulsive loading applications

International Nuclear Information System (INIS)

Nanda, Soumya Ranjan; Kulkarni, Vinayak; Sahoo, Niranjan

2017-01-01

The necessity of precise measurement of strain time history for impulsive loading applications has been addressed in the present investigation. Finite element modeling is initially carried out for a hemispherical test model and stress bar assembly to arrive at an appropriate location for strain measurement. In dynamic calibration experiments, strain measurements are performed using two wire and three wire quarter bride arrangements along with half bridge circuit. Usefulness of these arrangements has been verified by analyzing strain signals in time and frequency domains. Comparison of recovered force time histories proved that the half bridge circuit is the most suitable for such applications. Actual shock tube testing of the instrumented hemispherical test model confirmed the applicability of half bridge circuit for short duration strain measurements. (technical note)

Non-contact multi-frequency magnetic induction spectroscopy system for industrial-scale bio-impedance measurement

International Nuclear Information System (INIS)

O'Toole, M D; Marsh, L A; Davidson, J L; Tan, Y M; Armitage, D W; Peyton, A J

2015-01-01

Biological tissues have a complex impedance, or bio-impedance, profile which changes with respect to frequency. This is caused by dispersion mechanisms which govern how the electromagnetic field interacts with the tissue at the cellular and molecular level. Measuring the bio-impedance spectra of a biological sample can potentially provide insight into the sample’s properties and its cellular structure. This has obvious applications in the medical, pharmaceutical and food-based industrial domains. However, measuring the bio-impedance spectra non-destructively and in a way which is practical at an industrial scale presents substantial challenges. The low conductivity of the sample requires a highly sensitive instrument, while the demands of industrial-scale operation require a fast high-throughput sensor of rugged design. In this paper, we describe a multi-frequency magnetic induction spectroscopy (MIS) system suitable for industrial-scale, non-contact, spectroscopic bio-impedance measurement over a bandwidth of 156 kHz–2.5 MHz. The system sensitivity and performance are investigated using calibration and known reference samples. It is shown to yield rapid and consistently sensitive results with good long-term stability. The system is then used to obtain conductivity spectra of a number of biological test samples, including yeast suspensions of varying concentration and a range of agricultural produce, such as apples, pears, nectarines, kiwis, potatoes, oranges and tomatoes. (paper)

Strain localization band width evolution by electronic speckle pattern interferometry strain rate measurement

Energy Technology Data Exchange (ETDEWEB)

Guelorget, Bruno [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)], E-mail: bruno.guelorget@utt.fr; Francois, Manuel; Montay, Guillaume [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

2009-04-15

In this paper, electronic speckle pattern interferometry strain rate measurements are used to quantify the width of the strain localization band, which occurs when a sheet specimen is submitted to tension. It is shown that the width of this band decreases with increasing strain. Just before fracture, this measured width is about five times wider than the shear band and the initial sheet thickness.

Evaluation of anti-tuberculosis antibodies in healthy contact and non-contacts persons

International Nuclear Information System (INIS)

Aziz, N; Bukhari, M.H; Muneer, M; Tayyab, M; Chaudhry, N.A.

2006-01-01

This study was conducted to see the presence of the antimycobacterial antibodies in healthy household contacts of tuberculosis patients and healthy normal subjects who have never been in contact with tuberculosis patients. A total of 200 subjects, 120 with history of household contact and 80 without such history were included in the study. Routine Haematological investigations were performed and all the sera of 200 subjects were tested who 19M, 19G and IgA anti tuberculosis antibodies using ELISA technique. There was no difference in the average age of the household contacts and non-contacts. The complaints of pyrexia, night sweats and loss of weight was more in house hold contacts as compared to non-contacts. The awareness about BCG vaccination was equal among the household contacts and non-contacts. The combined serological positivity of the household contacts was 65.8% and the combined serological positivity for non-contacts was 34.1%. There was no statistically significant difference in the presence of 19M among household contacts as compared to non-contacts. However both IgG and 19A were present in significantly higher number of household contacts as compared to non contacts. This study concludes that the persons living in the house with a patient suffering from active pulmonary tuberculosis (household contact) have more chances of being infected with Mycobacterium tuberculosis as compared to the healthy non-contacts. (author)

Feasibility on Ultrasonic Velocity using Contact and Non-Contact Nondestructive Techniques for Carbon/Carbon Composites

Science.gov (United States)

Im, K. H.; Chang, M.; Hsu, D. K.; Song, S. J.; Cho, H.; Park, J. W.; Kweon, Y. S.; Sim, J. K.; Yang, I. Y.

2007-03-01

Advanced materials are to be required to have specific functions associated with extremely environments. One of them is carbon/carbon(C/C) composite material, which has obvious advantages over conventional materials. The C/Cs have become to be utilized as parts of aerospace applications and its low density, high thermal conductivity and excellent mechanical properties at elevated temperatures make it an ideal material for aircraft brake disks. Because of permeation of coupling medium such as water, it is desirable to perform contact-less nondestructive evaluation to assess material properties and part homogeneity. In this work, a C/C composite material was characterized with non-contact and contact ultrasonic methods using a scanner with automatic-data acquisition function. Also through transmission mode was performed because of the main limitation for air-coupled transducers, which is the acoustic impedance mismatch between most materials and air. Especially ultrasonic images and velocities for C/C composite disk brake were compared and found to be consistent to some degree with the non-contact and contact ultrasonic measurement methods. Low frequency through-transmission scans based on both amplitude of the ultrasonic pulse was used for mapping out the material property inhomogeneity. Measured results were compared with those obtained by the dry-coupling ultrasonic UT system and through transmission method in immersion. Finally, feasibility has been found to measure and compare ultrasonic velocities of C/C composites with using the contact/noncontact peak-delay measurement method based on the pulse overlap method.

Non-contact radiation thickness gauge

International Nuclear Information System (INIS)

Tsujii, T.; Okino, T.

1983-01-01

A noncontact thickness gauge system for measuring the thickness of a material comprising a source of radiation, a detector for detecting the amount of radiation transmitted through the material which is a function of the absorptance and thickness of the material, a memory for storing the output signals of the detector and curve-defining parameters for a plurality of quadratic calibration curves which correspond to respective thickness ranges, and a processor for processing the signals and curve defining parameters to determine the thickness of the material. Measurements are made after precalibration to obtain calibration curves and these are stored in the memory, providing signals representative of a nominal thickness and an alloy compensation coefficient for the material. The calibration curve corresponding to a particular thickness range is selected and the curve compensated for drift; the material is inserted into the radiation path and the detector output signal processed with the compensated calibration curve to determine the thickness of the material. (author)

Analysis of strain in reinforced concrete components by laser speckle photography

International Nuclear Information System (INIS)

Gross, K.P.

1982-01-01

Laser speckle photography is an optical process for non-contact measurement of strain in a plane at right angles to the axis of the optical system. The material composition and relief of the surface of a test sample have a great effect on the applicability of the process. Bodies with too smooth or too rough surfaces, and bodies of a transparent structure (salt bearing rocks) cannot be examined by speckle photography without previous surface treatment. The principle of the process and its application to the examination of reinforced concrete components is described. The capability of speckle photography, the accuracy of measurement which can be achieved and possible sources of error are discussed. (orig./RW) [de

Non-contact assessment of electrical performance for rapidly sintered nanoparticle silver coatings through colorimetry

International Nuclear Information System (INIS)

Cherrington, M.; Claypole, T.C.; Gethin, D.T.; Worsley, D.A.; Deganello, D.

2012-01-01

The color change during the ultrafast near-infrared sintering process of a nanoparticle silver ink has been correlated to its electrical performance through colorimetry using the CIELAB industry standard. Nanoparticle silver ink films, deposited over a flexible polyethylene terephthalate substrate, presented significant shifting in the a* and b* color coordinates during sintering, exhibiting the best conductivity with an a* coordinate of approximately 0 and a b* coordinate of approximately + 10. This color change has been associated with the Lorenz–Mie theory of electromagnetic scattering. This indirect measurement technique is potentially a breakthrough technology for fast in-line non-contact characterization of the drying and sintering process of nanoparticle conductive inks for use in large area roll-to-roll processing of printed electronics. - Highlights: ► Color change of a nanoparticle silver coating was measured during sintering ► Color change was correlated to the electrical performance of the coating. ► Potential in-line non-contact measurement method for roll-to-roll printed electronics

The Pulsair-Keeler non-contact tonometer in self-tonometry: preliminary results.

Science.gov (United States)

Boles Carenini, B; Brogliatti, B; Tonetto, C; Renis, E

1992-09-01

The authors considered the possibility of using the Pulsair-Keeler non-contact tonometer in self-tonometry. For this reason, 45 patients have been trained to use the instrument and, after a reasonable trial period, were able to self-measure their IOP. The results have been compared to the tonometric values measured with Goldmann tonometer to evaluate statistically the limits and the dependability of this method of measurement. The results shows that self-tonometry with the Pulsair-Keeler tonometer can be used in monitoring glaucomatous patients at home.

A Noncontact Measurement Technique for the Density and Thermal Expansion Coefficient of Solid and Liquid Materials

Science.gov (United States)

Chung, Sang K.; Thiessen, David B.; Rhim, Won-Kyu

1996-01-01

A noncontact measurement technique for the density and the thermal expansion refractory materials in their molten as well as solid phases is presented. This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2-3 mm diameter samples can be levitated, melted, and radiatively cooled in a vacuum. Due to the axisymmetric nature of the molten samples when levitated in the HTESL, a rather simple digital image analysis can be employed to accurately measure the volumetric change as a function of temperature. Density and the thermal expansion coefficient measurements were made on a pure nickel sample to test the accuracy of the technique in the temperature range of 1045-1565 C. The result for the liquid phase density can be expressed by p = 8.848 + (6.730 x 10(exp -4)) x T (degC) g/cu cm within 0.8% accuracy, and the corresponding thermal expansion coefficient can be expressed by Beta=(9.419 x 10(exp -5)) - (7.165 x 10(exp -9) x T (degC)/K within 0.2% accuracy.

Non-contact procedure to measure heart and lung activities in preterm pediatric patients with skin disorders

Science.gov (United States)

Marchionni, P.; Scalise, L.; Antognoli, L.; Nobile, S.; Carnielli, V. P.

2018-04-01

Preterm patients can have an higher risk of fatalities and can be subjected to long-term disability. With many organs still in the phase of development, the earlier the delivery, the higher the risk and they are therefore hospitalized in specialized neonatal intensive care units) where heart rate and lungs activity are continuously assessed. These are mostly monitored by set of electrodes placed in contact with skin (two in thorax area and one in abdominal area). This paper address the problem of preterm cardiac and respiratory monitoring in a patient with severe skin disorders who can not monitored with standard electrodes because of his dry, thickened, scaly skin. As a solution, we propose a fully non-contact measurement method, based on laser Doppler vibrometry, able to continuously record the movements of wall-chest and extract from this signal, the heart rate and the respiratory activity of the patient. The results show a good agreement between the standard contact measurement methods and the proposed one (no statistical difference between data) with a data uncertainty of 2.9% for the heart rate data and of 9.5% for the respiration rate (k=2), in line with the classical measurement methods.

Measurement of intraocular pressure using the NT-4000: a new non-contact tonometer equipped with pulse synchronous measurement function.

Science.gov (United States)

Yaoeda, Kiyoshi; Shirakashi, Motohiro; Fukushima, Atsushi; Funaki, Shigeo; Funaki, Haruko; Ofuchi, Nobutaka; Nakatsue, Tomoko; Abe, Haruki

2005-06-01

NT-4000 (Nidek Co. Ltd., Gamagori, Japan) is a new non-contact tonometer (NCT) equipped with pulse synchronous measurement function that can measure intraocular pressure (IOP) synchronized with the ocular pulse. The purpose of this study was to evaluate the usefulness of NT-4000 in normal subjects and in patients with glaucoma and ocular hypertension. This study included 175 eyes of 175 subjects. Firstly, the IOP was measured using NT-4000 without the pulse synchronous measurement function (NTn). Secondly, the IOP at peak, middle, and trough phases of the pulse signal were measured using NT-4000 with the pulse synchronous measurement function (NTp, NTm, NTt, respectively). Additionally, the IOP was measured with Goldmann applanation tonometer (GT). The coefficient of variation (CV) of three readings in the NCT measurements was used to evaluate the intra-session reproducibility. Statistical comparisons were performed using Wilcoxon signed rank test and one-way analysis of variance with Scheffe's test. Linear regression analysis was used to calculate correlation coefficients. P values less than 0.05 were accepted as statistically significant. The CV of NTn, NTp, NTm, and NTt were 6.4%, 5.5%, 4.9%, and 5.2%, respectively. The CV of NTp, NTm, and NTt were significantly smaller than that of NTn (P = 0.007, P < 0.001, P < 0.001, respectively). NTp was significantly higher than NTt (P = 0.038). GT was significantly correlated with NTn, NTp, NTm, and NTt (r = 0.898, P < 0.001; r = 0.912, P < 0.001; r = 0.908, P < 0.001; r = 0.900, P < 0.001, respectively). NT-4000 can detect the fluctuation of IOP associated with the ocular pulse.

Structural, Functional, and Metabolic Brain Markers Differentiate Collision versus Contact and Non-Contact Athletes.

Science.gov (United States)

Churchill, Nathan W; Hutchison, Michael G; Di Battista, Alex P; Graham, Simon J; Schweizer, Tom A

2017-01-01

There is growing concern about how participation in contact sports affects the brain. Retrospective evidence suggests that contact sports are associated with long-term negative health outcomes. However, much of the research to date has focused on former athletes with significant health problems. Less is known about the health of current athletes in contact and collision sports who have not reported significant medical issues. In this cross-sectional study, advanced magnetic resonance imaging (MRI) was used to evaluate multiple aspects of brain physiology in three groups of athletes participating in non-contact sports ( N  = 20), contact sports ( N  = 22), and collision sports ( N  = 23). Diffusion tensor imaging was used to assess white matter microstructure based on measures of fractional anisotropy (FA) and mean diffusivity (MD); resting-state functional MRI was used to evaluate global functional connectivity; single-voxel spectroscopy was used to compare ratios of neural metabolites, including N -acetyl aspartate (NAA), creatine (Cr), choline, and myo-inositol. Multivariate analysis revealed structural, functional, and metabolic measures that reliably differentiated between sport groups. The collision group had significantly elevated FA and reduced MD in white matter, compared to both contact and non-contact groups. In contrast, the collision group showed significant reductions in functional connectivity and the NAA/Cr metabolite ratio, relative to only the non-contact group, while the contact group overlapped with both non-contact and collision groups. For brain regions associated with contact sport participation, athletes with a history of concussion also showed greater alterations in FA and functional connectivity, indicating a potential cumulative effect of both contact exposure and concussion history on brain physiology. These findings indicate persistent differences in brain physiology for athletes participating in contact and collision sports

Noncontact blood species identification method based on spatially resolved near-infrared transmission spectroscopy

Science.gov (United States)

Zhang, Linna; Sun, Meixiu; Wang, Zhennan; Li, Hongxiao; Li, Yingxin; Li, Gang; Lin, Ling

2017-09-01

The inspection and identification of whole blood are crucially significant for import-export ports and inspection and quarantine departments. In our previous research, we proved Near-Infrared diffuse transmitted spectroscopy method was potential for noninvasively identifying three blood species, including macaque, human and mouse, with samples measured in the cuvettes. However, in open sampling cases, inspectors may be endangered by virulence factors in blood samples. In this paper, we explored the noncontact measurement for classification, with blood samples measured in the vacuum blood vessels. Spatially resolved near-infrared spectroscopy was used to improve the prediction accuracy. Results showed that the prediction accuracy of the model built with nine detection points was more than 90% in identification between all five species, including chicken, goat, macaque, pig and rat, far better than the performance of the model built with single-point spectra. The results fully supported the idea that spatially resolved near-infrared spectroscopy method can improve the prediction ability, and demonstrated the feasibility of this method for noncontact blood species identification in practical applications.

Noncontact inspection laser system for characterization of piezoelectric samples

International Nuclear Information System (INIS)

Jimenez, F.J.; Frutos, J. de

2004-01-01

In this work measurements on a piezoelectric sample in dynamic behavior were taken, in particular, around the frequencies of resonance for the sample where the nonlineal effects are accentuated. Dimension changes in the sample need to be studied as that will allow a more reliable characterization of the piezoelectric samples. The goal of this research is to develop an inspection system able to obtain measurements, using a noncontact laser displacement transducer, also able to visualize, in three-dimensional graphic environment, the displacement that takes place in a piezoelectric sample surface. In resonant mode, the vibration mode of the sample is visualized

Microwave non-contact imaging of subcutaneous human body tissues.

Science.gov (United States)

Kletsov, Andrey; Chernokalov, Alexander; Khripkov, Alexander; Cho, Jaegeol; Druchinin, Sergey

2015-10-01

A small-size microwave sensor is developed for non-contact imaging of a human body structure in 2D, enabling fitness and health monitoring using mobile devices. A method for human body tissue structure imaging is developed and experimentally validated. Subcutaneous fat tissue reconstruction depth of up to 70 mm and maximum fat thickness measurement error below 2 mm are demonstrated by measurements with a human body phantom and human subjects. Electrically small antennas are developed for integration of the microwave sensor into a mobile device. Usability of the developed microwave sensor for fitness applications, healthcare, and body weight management is demonstrated.

Strain gauge measurement uncertainties on hydraulic turbine runner blade

International Nuclear Information System (INIS)

Arpin-Pont, J; Gagnon, M; Tahan, S A; Coutu, A; Thibault, D

2012-01-01

Strains experimentally measured with strain gauges can differ from those evaluated using the Finite Element (FE) method. This difference is due mainly to the assumptions and uncertainties inherent to each method. To circumvent this difficulty, we developed a numerical method based on Monte Carlo simulations to evaluate measurement uncertainties produced by the behaviour of a unidirectional welded gauge, its position uncertainty and its integration effect. This numerical method uses the displacement fields of the studied part evaluated by an FE analysis. The paper presents a study case using in situ data measured on a hydraulic turbine runner. The FE analysis of the turbine runner blade was computed, and our numerical method used to evaluate uncertainties on strains measured at five locations with welded strain gauges. Then, measured strains and their uncertainty ranges are compared to the estimated strains. The uncertainty ranges obtained extended from 74 με to 165 με. Furthermore, the biases observed between the median of the uncertainty ranges and the FE strains varied from −36 to 36 με. Note that strain gauge measurement uncertainties depend mainly on displacement fields and gauge geometry.

Measuring autogenous strain of concrete with corrugated moulds

DEFF Research Database (Denmark)

Tian, Qian; Jensen, Ole Mejlhede

2008-01-01

A reliable technique to quantify autogenous strain is a prerequisite to numerical modeling in stress calculations for high performance concrete. The introducing of a special kind of corrugated tube mould helps to transforming volume strain measurement into liner strain measurement in horizontal...... direction for fluid concrete, which not only realizes the continuous monitoring of the autogenous shrinkage since casting, but also effectively eliminates the disturbance resulting from gravity, temperature variation and mould restraint on measuring results. Based on this measuring technique, this paper...

Photogrammetry for rapid prototyping: development of noncontact 3D reconstruction technologies

Science.gov (United States)

Knyaz, Vladimir A.

2002-04-01

An important stage of rapid prototyping technology is generating computer 3D model of an object to be reproduced. Wide variety of techniques for 3D model generation exists beginning with manual 3D models generation and finishing with full-automated reverse engineering system. The progress in CCD sensors and computers provides the background for integration of photogrammetry as an accurate 3D data source with CAD/CAM. The paper presents the results of developing photogrammetric methods for non-contact spatial coordinates measurements and generation of computer 3D model of real objects. The technology is based on object convergent images processing for calculating its 3D coordinates and surface reconstruction. The hardware used for spatial coordinates measurements is based on PC as central processing unit and video camera as image acquisition device. The original software for Windows 9X realizes the complete technology of 3D reconstruction for rapid input of geometry data in CAD/CAM systems. Technical characteristics of developed systems are given along with the results of applying for various tasks of 3D reconstruction. The paper describes the techniques used for non-contact measurements and the methods providing metric characteristics of reconstructed 3D model. Also the results of system application for 3D reconstruction of complex industrial objects are presented.

Standard guide for high-temperature static strain measurement

CERN Document Server

American Society for Testing and Materials. Philadelphia

1998-01-01

1.1 This guide covers the selection and application of strain gages for the measurement of static strain up to and including the temperature range from 425 to 650°C (800 to 1200°F). This guide reflects some current state-of-the-art techniques in high temperature strain measurement, and will be expanded and updated as new technology develops. 1.2 This practice assumes that the user is familiar with the use of bonded strain gages and associated signal conditioning and instrumentation as discussed in Refs. (1) and (2). The strain measuring systems described are those that have proven effective in the temperature range of interest and were available at the time of issue of this practice. It is not the intent of this practice to limit the user to one of the gage types described nor is it the intent to specify the type of system to be used for a specific application. However, in using any strain measuring system including those described, the proposer must be able to demonstrate the capability of the proposed sy...

Coupon Test of an Elbow Component by Using Vision-based Measurement System

International Nuclear Information System (INIS)

Kim, Sung Wan; Jeon, Bub Gyu; Choi, Hyoung Suk; Kim, Nam Sik

2016-01-01

Among the various methods to overcome this shortcoming, vision-based methods to measure the strain of a structure are being proposed and many studies are being conducted on them. The vision-based measurement method is a noncontact method for measuring displacement and strain of objects by comparing between images before and after deformation. This method offers such advantages as no limitations in the surface condition, temperature, and shape of objects, the possibility of full filed measurement, and the possibility of measuring the distribution of stress or defects of structures based on the measurement results of displacement and strain in a map. The strains were measured with various methods using images in coupon test and the measurements were compared. In the future, the validity of the algorithm will be compared using stain gauge and clip gage, and based on the results, the physical properties of materials will be measured using a vision-based measurement system. This will contribute to the evaluation of reliability and effectiveness which are required for investigating local damages

Coupon Test of an Elbow Component by Using Vision-based Measurement System

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung Wan; Jeon, Bub Gyu; Choi, Hyoung Suk; Kim, Nam Sik [Pusan National University, Busan (Korea, Republic of)

2016-05-15

Among the various methods to overcome this shortcoming, vision-based methods to measure the strain of a structure are being proposed and many studies are being conducted on them. The vision-based measurement method is a noncontact method for measuring displacement and strain of objects by comparing between images before and after deformation. This method offers such advantages as no limitations in the surface condition, temperature, and shape of objects, the possibility of full filed measurement, and the possibility of measuring the distribution of stress or defects of structures based on the measurement results of displacement and strain in a map. The strains were measured with various methods using images in coupon test and the measurements were compared. In the future, the validity of the algorithm will be compared using stain gauge and clip gage, and based on the results, the physical properties of materials will be measured using a vision-based measurement system. This will contribute to the evaluation of reliability and effectiveness which are required for investigating local damages.

Engineering strain measurements using the NPD at LANSCE

International Nuclear Information System (INIS)

Bourke, M.A.M.; Goldstone, J.A.; Lovell, K.J.

1991-01-01

The presence of residual stress in engineering components can affect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can provide spatially resolved non-destructive strain measurements in the interior of a component. By recording the change in the interplanar spacings elastic strains can be measured for individual lattice reflections. Also on a pulsed source, where all lattice reflections are recorded, profile refinement is an option which allows the strain to be obtained from changes in the lattice parameter. Measurements made at LANSCE demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. (author)

Performance of the PT100 noncontact tonometer in healthy eyes

Directory of Open Access Journals (Sweden)

AlMubrad T

2011-05-01

Full Text Available Turki M AlMubradCornea Research Chair, Department of Optometry, College of Applied Medical Sciences, King Saud University, Riyadh, Kingdom of Saudi ArabiaBackground: The purpose of this study was to assess the repeatability and reproducibility of the PT100 noncontact tonometer and to compare its consistency with the Goldmann applanation tonometer (GAT in measuring intraocular pressure (IOP.Methods: Triplicate IOP measurements were obtained on two separate occasions using the PT100 and GAT from randomly selected eyes in 66 healthy volunteers aged 22 ± 1 years. The repeatability and reproducibility of each techniques was assessed. Agreement between the techniques was statistically quantified using intrasession repeatability for each technique as the basis for comparison.Results: Both techniques returned equal IOP values in the first measurement session (15 ± 3 mmHg. The second session showed a mean difference in average IOP (1 ± 0.71. The 95% limits of agreement between the techniques were –5.2 to 5.5 mmHg and –4.0 to 4.7 mmHg (sessions 1 and 2, respectively. These mean differences were not statistically significant (P > 0.05, paired t-test, with the PT100 underestimating IOP measurement by 1.00 mmHg. The mean intrasession IOP for GAT sessions 1 and 2 was 0 ± 0.90 mmHg and 0.04 ± 1.06 mmHg, respectively, and the corresponding mean IOP measurement difference for the PT100 was –0.06 ± 0.96 and –0.39 ± 0.94 mmHg (sessions 1 and 2, respectively; P > 0.05, paired t-test. Repeatability coefficients for the GAT IOP measurements were 1.8 mmHg and 2.1 mmHg for sessions 1 and 2, while the PT100 repeatability coefficient was 1.9 mmHg and 1.8 mmHg for sessions 1 and 2, respectively. The intrasession repeatability coefficient of both techniques for test–retest differences were within ±5 mmHg.Conclusion: The PT100 noncontact tonometer produced greater repeatability than the GAT in assessment of IOP, whereas GAT resulted in more reproducible

Automatic detection of measurement points for non-contact vibrometer-based diagnosis of cardiac arrhythmias

Science.gov (United States)

Metzler, Jürgen; Kroschel, Kristian; Willersinn, Dieter

2017-03-01

Monitoring of the heart rhythm is the cornerstone of the diagnosis of cardiac arrhythmias. It is done by means of electrocardiography which relies on electrodes attached to the skin of the patient. We present a new system approach based on the so-called vibrocardiogram that allows an automatic non-contact registration of the heart rhythm. Because of the contactless principle, the technique offers potential application advantages in medical fields like emergency medicine (burn patient) or premature baby care where adhesive electrodes are not easily applicable. A laser-based, mobile, contactless vibrometer for on-site diagnostics that works with the principle of laser Doppler vibrometry allows the acquisition of vital functions in form of a vibrocardiogram. Preliminary clinical studies at the Klinikum Karlsruhe have shown that the region around the carotid artery and the chest region are appropriate therefore. However, the challenge is to find a suitable measurement point in these parts of the body that differs from person to person due to e. g. physiological properties of the skin. Therefore, we propose a new Microsoft Kinect-based approach. When a suitable measurement area on the appropriate parts of the body are detected by processing the Kinect data, the vibrometer is automatically aligned on an initial location within this area. Then, vibrocardiograms on different locations within this area are successively acquired until a sufficient measuring quality is achieved. This optimal location is found by exploiting the autocorrelation function.

Non-Contact Smartphone-Based Monitoring of Thermally Stressed Structures

Science.gov (United States)

Ozturk, Turgut; Mas, David; Rizzo, Piervincenzo

2018-01-01

The in-situ measurement of thermal stress in beams or continuous welded rails may prevent structural anomalies such as buckling. This study proposed a non-contact monitoring/inspection approach based on the use of a smartphone and a computer vision algorithm to estimate the vibrating characteristics of beams subjected to thermal stress. It is hypothesized that the vibration of a beam can be captured using a smartphone operating at frame rates higher than conventional 30 Hz, and the first few natural frequencies of the beam can be extracted using a computer vision algorithm. In this study, the first mode of vibration was considered and compared to the information obtained with a conventional accelerometer attached to the two structures investigated, namely a thin beam and a thick beam. The results show excellent agreement between the conventional contact method and the non-contact sensing approach proposed here. In the future, these findings may be used to develop a monitoring/inspection smartphone application to assess the axial stress of slender structures, to predict the neutral temperature of continuous welded rails, or to prevent thermal buckling. PMID:29670034

Field-expedient screening and injury risk algorithm categories as predictors of noncontact lower extremity injury.

Science.gov (United States)

Lehr, M E; Plisky, P J; Butler, R J; Fink, M L; Kiesel, K B; Underwood, F B

2013-08-01

In athletics, efficient screening tools are sought to curb the rising number of noncontact injuries and associated health care costs. The authors hypothesized that an injury prediction algorithm that incorporates movement screening performance, demographic information, and injury history can accurately categorize risk of noncontact lower extremity (LE) injury. One hundred eighty-three collegiate athletes were screened during the preseason. The test scores and demographic information were entered into an injury prediction algorithm that weighted the evidence-based risk factors. Athletes were then prospectively followed for noncontact LE injury. Subsequent analysis collapsed the groupings into two risk categories: Low (normal and slight) and High (moderate and substantial). Using these groups and noncontact LE injuries, relative risk (RR), sensitivity, specificity, and likelihood ratios were calculated. Forty-two subjects sustained a noncontact LE injury over the course of the study. Athletes identified as High Risk (n = 63) were at a greater risk of noncontact LE injury (27/63) during the season [RR: 3.4 95% confidence interval 2.0 to 6.0]. These results suggest that an injury prediction algorithm composed of performance on efficient, low-cost, field-ready tests can help identify individuals at elevated risk of noncontact LE injury. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Engineering strain measurements using the NPD at LANSCE

International Nuclear Information System (INIS)

Bourke, M.A.M.; Goldstone, J.A.; Lovell, K.J.

1990-01-01

The presence of residual stress in engineering components can affect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can provide spatially resolved non-destructive strain measurements in the interior of a component. By recording the change in the interplanar spacings elastic strains can be measured for individual lattice reflections. Also on a pulsed source, where all lattice reflections are recorded, profile refinement is an option which alloys the strain to be obtained from changes in the lattice parameter. Measurements made at LANSCE demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. 5 refs., 5 figs

Dark field electron holography for strain measurement

Energy Technology Data Exchange (ETDEWEB)

Beche, A., E-mail: armand.beche@fei.com [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)

2011-02-15

Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

Rail inspection using noncontact laser ultrasonics

International Nuclear Information System (INIS)

Kim, Nak Hyeon; Sohn, Hoon; Han, Soon Woo

2012-01-01

In this study, a noncontact laser ultrasonic system is proposed for rail defect detection. An Nd Yag pulse laser is used for generation of ultrasonic waves, and the corresponding ultrasonic responses are measured by a laser Doppler vibrometer. For the detection of rail surface damages, the shape of the excitation laser beam is transformed into a line. On the other hand, a point source laser beam is used for the inspection of defects inside a rail head. Then, the interactions of propagating ultrasonic waves with defects are examined using actual rail specimens. Amplitude attenuation was mainly observed for a surface crack, and reflections were most noticeable from an internal damage. Finally, opportunities and challenges associated with real time rail inspection from a high speed train are discussed

Fully Noncontact Wave Propagation Imaging in an Immersed Metallic Plate with a Crack

Directory of Open Access Journals (Sweden)

Jung-Ryul Lee

2014-01-01

Full Text Available This study presents a noncontact sensing technique with ultrasonic wave propagation imaging algorithm, for damage visualization of liquid-immersed structures. An aluminum plate specimen (400 mm × 400 mm × 3 mm with a 12 mm slit was immersed in water and in glycerin. A 532 nm Q-switched continuous wave laser is used at an energy level of 1.2 mJ to scan an area of 100 mm × 100 mm. A laser Doppler vibrometer is used as a noncontact ultrasonic sensor, which measures guided wave displacement at a fixed point. The tests are performed with two different cases of specimen: without water and filled with water and with glycerin. Lamb wave dispersion curves for the respective cases are calculated, to investigate the velocity-frequency relationship of each wave mode. Experimental propagation velocities of Lamb waves for different cases are compared with the theoretical dispersion curves. This study shows that the dispersion and attenuation of the Lamb wave is affected by the surrounding liquid, and the comparative experimental results are presented to verify it. In addition, it is demonstrated that the developed fully noncontact ultrasonic propagation imaging system is capable of damage sizing in submerged structures.

Non-contact assessment of electrical performance for rapidly sintered nanoparticle silver coatings through colorimetry

Energy Technology Data Exchange (ETDEWEB)

Cherrington, M.; Claypole, T.C.; Gethin, D.T. [Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom); Worsley, D.A. [SPECIFIC, College of Engineering, Swansea University, Baglan Bay Innovation Centre, Central Avenue, Baglan Energy Park, Port Talbot, SA12 7AX (United Kingdom); Deganello, D., E-mail: d.deganello@swansea.ac.uk [Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom)

2012-11-01

The color change during the ultrafast near-infrared sintering process of a nanoparticle silver ink has been correlated to its electrical performance through colorimetry using the CIELAB industry standard. Nanoparticle silver ink films, deposited over a flexible polyethylene terephthalate substrate, presented significant shifting in the a* and b* color coordinates during sintering, exhibiting the best conductivity with an a* coordinate of approximately 0 and a b* coordinate of approximately + 10. This color change has been associated with the Lorenz-Mie theory of electromagnetic scattering. This indirect measurement technique is potentially a breakthrough technology for fast in-line non-contact characterization of the drying and sintering process of nanoparticle conductive inks for use in large area roll-to-roll processing of printed electronics. - Highlights: Black-Right-Pointing-Pointer Color change of a nanoparticle silver coating was measured during sintering Black-Right-Pointing-Pointer Color change was correlated to the electrical performance of the coating. Black-Right-Pointing-Pointer Potential in-line non-contact measurement method for roll-to-roll printed electronics.

SAFE for PTSD: noncontact psychophysiological measure based on high-resolution thermal imaging to aid in PTSD diagnosis and assessment of treatment

Science.gov (United States)

Familoni, Babajide O.; Ma, Lein; Hutchinson, J. Andrew; Morgan, C. Andrew, III; Rasmusson, Ann; O'Kane, Barbara L.

2012-06-01

Post Traumatic Stress Disorder (PTSD) sometimes develops following exposure to very stressful or traumatic events such as motor vehicle accidents, rape, and war. It is arguably the signature injury of the conflicts in Iraq and Afghanistan. Previous studies have demonstrated that PTSD sufferers exhibit autonomic hyper-responsiveness to both neutral and trauma-related stimuli. In this study, we propose using high resolution thermal imaging of sweat-pores to obtain a noncontact, remote, and quantifiable measure of the sympathetic autonomic nervous reactivity to guide diagnosis, assess response to treatment, and tease out important cues to suicidality as a PTSD comorbidity.

IOP measurement in silicone oil tamponade eyes by Corvis ST tonometer, Goldmann applanation tonometry and non-contact tonometry.

Science.gov (United States)

Zhang, Yang; Zheng, Lin; Bian, Ailing; Zhou, Qi

2018-04-01

To compare the postoperative intraocular pressure (IOP) of eyes following pars plana vitrectomy (PPV) combined with intravitreal silicone oil (SO) tamponade by Corneal Visualization Scheimpflug Technology (CST), Goldmann applanation tonometry (GAT) and non-contact tonometry (NCT). Thirty-eight participants who had undergone PPV combined with SO tamponade to treat vitreoretinal diseases were enrolled. Postoperative IOP measurements were obtained using CST, NCT and GAT. Inter-device agreement was assessed by Bland-Altman analysis. The correlation coefficient was used to describe the potential postoperative factors affecting the postoperative IOP differences between each device. Bland-Altman analysis revealed the bias between CST and GAT, between CST and NCT, and between GAT and NCT to be -0.2, 2.1 and 2.4 mmHg, respectively. CST and GAT correlated well with each other. NCT values were lower than those of GAT and CST (all p contact method for measuring postoperative IOP in SO tamponade eyes.

Quantitative shearography: error reduction by using more than three measurement channels

International Nuclear Information System (INIS)

Charrett, Tom O. H.; Francis, Daniel; Tatam, Ralph P.

2011-01-01

Shearography is a noncontact optical technique used to measure surface displacement derivatives. Full surface strain characterization can be achieved using shearography configurations employing at least three measurement channels. Each measurement channel is sensitive to a single displacement gradient component defined by its sensitivity vector. A matrix transformation is then required to convert the measured components to the orthogonal displacement gradients required for quantitative strain measurement. This transformation, conventionally performed using three measurement channels, amplifies any errors present in the measurement. This paper investigates the use of additional measurement channels using the results of a computer model and an experimental shearography system. Results are presented showing that the addition of a fourth channel can reduce the errors in the computed orthogonal components by up to 33% and that, by using 10 channels, reductions of around 45% should be possible.

Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

International Nuclear Information System (INIS)

Guelorget, Bruno; Francois, Manuel; Vial-Edwards, Cristian; Montay, Guillaume; Daniel, Laurent; Lu, Jian

2006-01-01

In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force (ε t ≅ 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements

Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

Energy Technology Data Exchange (ETDEWEB)

Guelorget, Bruno [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)]. E-mail: bruno.guelorget@utt.fr; Francois, Manuel [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Vial-Edwards, Cristian [Departemento de Ingenieria Mecanica y Metalurgica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, 6904411 Santiago (Chile); Montay, Guillaume [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Daniel, Laurent [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Lu, Jian [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

2006-01-15

In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force ({epsilon} {sup t} {approx_equal} 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements.

An ultrasonically levitated noncontact stage using traveling vibrations on precision ceramic guide rails.

Science.gov (United States)

Koyama, Daisuke; Ide, Takeshi; Friend, James R; Nakamura, Kentaro; Ueha, Sadayuki

2007-03-01

This paper presents a noncontact sliding table design and measurements of its performance via ultrasonic levitation. A slider placed atop two vibrating guide rails is levitated by an acoustic radiation force emitted from the rails. A flexural traveling wave propagating along the guide rails allows noncontact transportation of the slider. Permitting a transport mechanism that reduces abrasion and dust generation with an inexpensive and simple structure. The profile of the sliding table was designed using the finite-element analysis (FEA) for high levitation and transportation efficiency. The prototype sliding table was made of alumina ceramic (Al2O3) to increase machining accuracy and rigidity using a structure composed of a pair of guide rails with a triangular cross section and piezoelectric transducers. Two types of transducers were used: bolt-clamped Langevin transducers and bimorph transducers. A 40-mm long slider was designed to fit atop the two rail guides. Flexural standing waves and torsional standing waves were observed along the guide rails at resonance, and the levitation of the slider was obtained using the flexural mode even while the levitation distance was less than 10 microm. The levitation distance of the slider was measured while increasing the slider's weight. The levitation pressure, rigidity, and vertical displacement amplitude of the levitating slider thus were measured to be 6.7 kN/m2, 3.0 kN/microm/m2, and less than 1 microm, respectively. Noncontact transport of the slider was achieved using phased drive of the two transducers at either end of the vibrating guide rail. By controlling the phase difference, the slider transportation direction could be switched, and a maximum thrust of 13 mN was obtained.

A piezoelectric transducer for measurement of dynamic strain in pipes

Energy Technology Data Exchange (ETDEWEB)

Lannes, Daniel P.; Gama, Antonio L. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Mecanica

2009-07-01

This work presents a new strain transducer developed mainly for the inspection and evaluation of piping systems with excessive vibration. Vibration is one of the most common causes of piping failures. These failures could be avoided if the vibration problems were identified and quickly evaluated. Procedures for evaluation of piping vibration are usually based on pipe velocity or displacement. Although simple and fast, these procedures do not provide precise information on the risk of piping fatigue failure. Through the measurement of pipe dynamic strains the risk of failure due to vibration can be determined more accurately. The measurement of strain is usually performed using the conventional strain gauge method. Although efficient and accurate, the implementation of the conventional strain gauge technique may become a difficult task in certain industrial scenarios. Motivated by the need of a simple and rapid method for pipe dynamic strain measurement, a piezoelectric dynamic strain transducer was developed. This work presents a description of the piezoelectric strain transducer and the preliminary results of pipe strain measurements. The transducer can be applied directly to the pipe through magnetic bases allowing for the quick measurement of the dynamic strains in many points of the pipe. The transducer signal can be read with the same commercial data collectors used for accelerometers. (author)

Mobile Cloud-Computing-Based Healthcare Service by Noncontact ECG Monitoring

Directory of Open Access Journals (Sweden)

Ee-May Fong

2013-12-01

Full Text Available Noncontact electrocardiogram (ECG measurement technique has gained popularity these days owing to its noninvasive features and convenience in daily life use. This paper presents mobile cloud computing for a healthcare system where a noncontact ECG measurement method is employed to capture biomedical signals from users. Healthcare service is provided to continuously collect biomedical signals from multiple locations. To observe and analyze the ECG signals in real time, a mobile device is used as a mobile monitoring terminal. In addition, a personalized healthcare assistant is installed on the mobile device; several healthcare features such as health status summaries, medication QR code scanning, and reminders are integrated into the mobile application. Health data are being synchronized into the healthcare cloud computing service (Web server system and Web server dataset to ensure a seamless healthcare monitoring system and anytime and anywhere coverage of network connection is available. Together with a Web page application, medical data are easily accessed by medical professionals or family members. Web page performance evaluation was conducted to ensure minimal Web server latency. The system demonstrates better availability of off-site and up-to-the-minute patient data, which can help detect health problems early and keep elderly patients out of the emergency room, thus providing a better and more comprehensive healthcare cloud computing service.

Non-contact biopotential sensor for remote human detection

Energy Technology Data Exchange (ETDEWEB)

Mahdi, A E [Department of Electronic and Computer Engineering, University of Limerick, Limerick (Ireland); Faggion, L, E-mail: hussain.mahdi@ul.ie, E-mail: lorenzo.faggion@jrc.ec.europa.eu [Joint Research Centre of the European Commission, Institute for the Protection and Safety of the Citizen, Ispra (Italy)

2011-08-17

This paper describes a new low-cost, low-noise displacement current sensor developed for non-contact measurements of human biopotentials and well suited for detection of human presence applications. The sensor employs a simple, improvised transimpedance amplifier that eliminates the need for ultra high values resistors normally needed in current amplifiers required for this type of measurements. The sensor provides an operational bandwidth of 0.5 - 250 Hz, and a noise level of 7.8{mu}V{radical}Hz at 1 Hz down to 30nV/{radical}Hz at 1 kHz. Reported experimental results demonstrate the sensor's capability in measuring heart related biopotentials within 0.5m off-body distance, and muscle related biopotentials within 10m no obstacles off-body distance, and 5m off-body distance with a concrete wall in between.

Strain measurement in concrete using embedded carbon roving-based sensors

International Nuclear Information System (INIS)

Quadflieg, Till; Gries, Thomas; Stolyarov, Oleg

2016-01-01

This paper presents the results of the application of carbon rovings as strain sensors for measuring the strain in concrete. In this work, three types of electrically conductive carbon roving with different characteristics were used. The possibility of using carbon rovings as a strain sensor is demonstrated via measurements in tensile and four point bending tests. The experimental setups and methods for measuring the electrical resistance of carbon roving in the roving and concrete are described. The results of the characterization of the electrical behavior as a function of strain of carbon rovings and concrete are presented and discussed. The obtained results indicate that the strain range of carbon rovings optimally corresponds to the strain range of concrete. This characteristic behavior makes the carbon rovings well suited for the use as strain sensors. A good correlation has been found between the electrical resistance-strain curve of the carbon roving and the measurements in the concrete.

Neonatal non-contact respiratory monitoring based on real-time infrared thermography

Directory of Open Access Journals (Sweden)

Abbas Abbas K

2011-10-01

Full Text Available Abstract Background Monitoring of vital parameters is an important topic in neonatal daily care. Progress in computational intelligence and medical sensors has facilitated the development of smart bedside monitors that can integrate multiple parameters into a single monitoring system. This paper describes non-contact monitoring of neonatal vital signals based on infrared thermography as a new biomedical engineering application. One signal of clinical interest is the spontaneous respiration rate of the neonate. It will be shown that the respiration rate of neonates can be monitored based on analysis of the anterior naris (nostrils temperature profile associated with the inspiration and expiration phases successively. Objective The aim of this study is to develop and investigate a new non-contact respiration monitoring modality for neonatal intensive care unit (NICU using infrared thermography imaging. This development includes subsequent image processing (region of interest (ROI detection and optimization. Moreover, it includes further optimization of this non-contact respiration monitoring to be considered as physiological measurement inside NICU wards. Results Continuous wavelet transformation based on Debauches wavelet function was applied to detect the breathing signal within an image stream. Respiration was successfully monitored based on a 0.3°C to 0.5°C temperature difference between the inspiration and expiration phases. Conclusions Although this method has been applied to adults before, this is the first time it was used in a newborn infant population inside the neonatal intensive care unit (NICU. The promising results suggest to include this technology into advanced NICU monitors.

Airborne non-contact and contact broadband ultrasounds for frequency attenuation profile estimation of cementitious materials.

Science.gov (United States)

Gosálbez, J; Wright, W M D; Jiang, W; Carrión, A; Genovés, V; Bosch, I

2018-08-01

In this paper, the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous cementitious materials is addressed. To accurately determine the attenuation over a wide frequency range, it is necessary to have suitable excitation techniques. We have analysed two kinds of ultrasound techniques: contact ultrasound and airborne non-contact ultrasound. The mathematical formulation for frequency-dependent attenuation has been established and it has been revealed that each technique may achieve similar results but requires specific different calibration processes. In particular, the airborne non-contact technique suffers high attenuation due to energy losses at the air-material interfaces. Thus, its bandwidth is limited to low frequencies but it does not require physical contact between transducer and specimen. In contrast, the classical contact technique can manage higher frequencies but the measurement depends on the pressure between the transducer and the specimen. Cement specimens have been tested with both techniques and frequency attenuation dependence has been estimated. Similar results were achieved at overlapping bandwidth and it has been demonstrated that the airborne non-contact ultrasound technique could be a viable alternative to the classical contact technique. Copyright © 2018 Elsevier B.V. All rights reserved.

Noncontact measurement of elasticity for the detection of soft-tissue tumors using phase-sensitive optical coherence tomography combined with a focused air-puff system.

Science.gov (United States)

Wang, Shang; Li, Jiasong; Manapuram, Ravi Kiran; Menodiado, Floredes M; Ingram, Davis R; Twa, Michael D; Lazar, Alexander J; Lev, Dina C; Pollock, Raphael E; Larin, Kirill V

2012-12-15

We report on an optical noncontact method for the detection of soft-tissue tumors based on the measurement of their elasticity. A focused air-puff system is used to excite surface waves (SWs) on soft tissues with transient static pressure. A high-speed phase-sensitive optical coherence tomography system is used to measure the SWs as they propagate from the point of excitation. To evaluate the stiffness of soft tissues, the Young's modulus is quantified based on the group velocity of SWs. Pilot experiments were performed on ex vivo human myxoma and normal fat. Results demonstrate the feasibility of the proposed method to measure elasticity and differentiate soft-tissue tumors from normal tissues.

Phenomenological modeling of long range noncontact friction in micro- and nanoresonators

International Nuclear Information System (INIS)

Gusso, Andre

2011-01-01

Motivated by the results of an experiment using atomic force microscopy performed by Gotsmann and Fuchs [Phys. Rev. Lett. 86, 2597 (2001)], where a strong energy loss due to the tip-sample interaction was measured, we investigate the potential implications of this energy loss channel to the quality factor of suspended micro- and nanoresonators. Because the observed tip-sample dissipation remains without a satisfactory theoretical explanation, two phenomenological models are proposed to generalize the experimental observations. In the minimal phenomenological model the range of validity of the power law found experimentally for the damping coefficient is assumed to be valid for larger separations. A more elaborate phenomenological model assumes that the noncontact friction is a consequence of the Casimir force acting between the closely spaced surfaces. Both models provide quantitative results for the noncontact friction between any two objects which are then used to estimate the energy loss for suspended bar micro- and nanoresonators. It is concluded that the energy loss due to the unknown mechanism has the potential to seriously restrict the quality factor of both micro- and nanoresonators.

Study of non-contact measurement of the thermal expansion coefficients of materials based on laser feedback interferometry

Energy Technology Data Exchange (ETDEWEB)

Zheng, Fasong [The State Key Lab of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing 100084 (China); Departments of Physics, College of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Tan, Yidong; Zhang, Shulian, E-mail: zsl-dpi@mail.tsinghua.edu.cn [The State Key Lab of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing 100084 (China); Lin, Jing; Ding, Yingchun [Departments of Physics, College of Science, Beijing University of Chemical Technology, Beijing 100029 (China)

2015-04-15

The noncooperative and ultrahigh sensitive length measurement approach is of great significance to the study of a high-precision thermal expansion coefficient (TEC) determination of materials at a wide temperature range. The novel approach is presented in this paper based on the Nd:YAG microchip laser feedback interferometry with 1064 nm wavelength, the beam frequency of which is shifted by a pair of acousto-optic modulators and then the heterodyne phase measurement technique is used. The sample is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams are perpendicular and coaxial on each surface of the sample, the configuration which can not only achieve the length measurement of sample but also eliminate the influence of the distortion of the sample supporter. The reference beams inject on the reference mirrors which are put as possible as near the holes, respectively, to eliminate the air disturbances and the influence of thermal lens effect out of the furnace chamber. For validation, the thermal expansion coefficients of aluminum and steel 45 samples are measured from room temperature to 748 K, which proved measurement repeatability of TECs is better than 0.6 × 10{sup −6}(K{sup −1}) at the range of 298 K–598 K and the high-sensitive non-contact measurement of the low reflectivity surface induced by the oxidization of the samples at the range of 598 K–748 K.

Ocular surface displacement with and without contact lenses during non-contact tonometry.

Science.gov (United States)

Rimayanti, Ulfah; Kiuchi, Yoshiaki; Uemura, Shohei; Takenaka, Joji; Mochizuki, Hideki; Kaneko, Makoto

2014-01-01

To evaluate the displacement of the central ocular surface during non-contact tonometry with and without soft contact lenses and determine the factors associated with the displacement of the central ocular surface and intraocular pressure (IOP) reading changes caused by wearing soft contact lenses (CLs). One eye each in 21 subjects was studied. The cornea was photographed using a high-speed camera at 5,000 frames/sec during non-contact tonometry without contact lenses (NCL), with -5.0 diopters (D), -0.5 D and +5.0 D CL. The displacement of the ocular surface and the factors affecting displacement at the IOP reading and maximum displacement time were investigated. The IOP readings while wearing +5 D CL were significantly higher than those obtained while wearing -5 D CL. The ocular surface displacement between +5 D CL and other groups were significantly different. A significant positive correlation was found between the ocular surface displacement of subjects at the IOP reading time and the IOP obtained with the non-contact tonometer. A significant negative correlation was found between the ocular surface curvature and the IOP obtained using the non-contact tonometer. The radius of curvature of the ocular surface affected the displacement during the IOP reading and maximum displacement time. Our results indicate that soft contact lens use changes the ocular surface behavior and IOP readings during non-contact tonometry. The radius of curvature of the eye affects the ocular surface displacement and IOP readings in this situation.

Non-Contact Monitoring of Heart and Lung Activity by Magnetic Induction Measurement

Directory of Open Access Journals (Sweden)

M. Steffen

2008-01-01

Full Text Available In many clinical applications, the monitoring of heart and lung activity is of vital importance. State-of-the-art monitoring involves the use of electrodes or other contact based sensors (electrocardiogram (ECG, impedance cardiography (ICG, pulse oximetry or equivalent. With the equipment that is used, side effects like skin irritation, difficult application or additional cabling may occur. In contrast, this paper describes a method for non-contact monitoring of heart and lung activity, which is solely based on magnetic induction. This method allows simultaneous monitoring of heart and lung activity, and has the potential of an integrated application in a personal healthcare scenario. To illustrate the performance, a simple test-setup has been developed and the first results are presented here (some of which have been previously presented on the Poster 2008 [10]. 

Non-contact micro mass evaluation method using an X-ray microscope

Energy Technology Data Exchange (ETDEWEB)

Kim, Jiseok; Sun, Gwang Min; Baek, Ha Ni; Hoang, Sy Minh Tuan; Park, Sun Ae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2017-07-15

For the mass inspection of attached foils such as printed electrodes, mass should be measured by a non-contact method with the capacity to measure a small mass of micrograms. In this study, the masses of 1 mg to 10 mg electrodes were evaluated using an X-ray microscope. The results were compared with the masses determined by using a digital scale with a 0.005 mg error. The average of the relative error between the mass measurements using the X-ray microscope and those using the digital scale was less than 2.51%. The results show that X-ray mass evaluation method can be used for mass measurement of micro objects by replacing a digital scale.

Measurement of Strain and Strain Rate during the Impact of Tennis Ball Cores

Directory of Open Access Journals (Sweden)

Ben Lane

2018-03-01

Full Text Available The aim of this investigation was to establish the strains and strain rates experienced by tennis ball cores during impact to inform material characterisation testing and finite element modelling. Three-dimensional surface strains and strain rates were measured using two high-speed video cameras and corresponding digital image correlation software (GOM Correlate Professional. The results suggest that material characterisation testing to a maximum strain of 0.4 and a maximum rate of 500 s−1 in tension and to a maximum strain of −0.4 and a maximum rate of −800 s−1 in compression would encapsulate the demands placed on the material during impact and, in turn, define the range of properties required to encapsulate the behavior of the material during impact, enabling testing to be application-specific and strain-rate-dependent properties to be established and incorporated in finite element models.

Non-contact magnetic coupled power and data transferring system for an electric vehicle

International Nuclear Information System (INIS)

Matsuda, Y.; Sakamoto, H.

2007-01-01

We have developed a system which transmits electric power and communication data simultaneously in a non-contact method using a magnetic coupling coil. Already, we are developing the fundamental technology of a non-contact charging system, and this is applied in electric shavers, electric toothbrushes, etc. Moreover, basic experiments are being conducted for applying this non-contact charging system to electric equipments such as an electric vehicle (EV), which is a zero emission vehicle and environmentally excellent and will be the transportation means of the next generation. The technology can also be applied in other electronic equipment, etc. However, since the power supply route for these individual devices is independent, the supply system is complicated. EV also has to perform the transmission of electric power and the transmission of information (data), such as the amount of the charge, in a separate system, and thus is quite complicated. In this study, by performing simultaneously the transmission of electric power and information (data) using magnetic coupling technology in which it does not contact, the basic experiment aimed at attaining and making unification of a system simple was conducted, and the following good results were obtained: (1) Electric power required for load can be transmitted easily by non-contact. (2) A signal can easily be transmitted bidirectionally by non-contact. (3) This system is reliable, and is widely applicable

Noncontact ultrasound imaging applied to cortical bone phantoms.

Science.gov (United States)

Bulman, J B; Ganezer, K S; Halcrow, P W; Neeson, Ian

2012-06-01

The purpose of this paper was to take the first steps toward applying noncontact ultrasound (NCU) to the tasks of monitoring osteoporosis and quantitative ultrasound imaging (QUS) of cortical bone. The authors also focused on the advantages of NCU, such as its lack of reliance on a technologist to apply transducers and a layer of acoustical coupling gel, the ability of the transducers to operate autonomously as specified by preprogrammed software, and the likely reduction in statistical and systematic errors associated with the variability in the pressure applied by the clinician to the transmitting transducer that NCU might provide. The authors also undertook this study in order to find additional applications of NCU beyond its past limited usage in assessing the severity of third degree burns. A noncontact ultrasound imaging system using a pair of specially designed broadband, 1.5 MHz noncontact piezoelectric transducers and cortical bone phantoms, were used to determine bone mineral density (BMD), speed of sound (SOS), integrated response (IR), and ultrasonic transmittance. Air gaps of greater than 3 cm, two transmission and two reflection paths, and a digital signal processor were also used in the collection of data from phantoms of nominal mass densities that varied from 1.17 to 2.25 g/cm(3) and in bone mineral density from 0 to 1.7 g/cm(3). Good correlations between known BMD and measured SOS, IR, and transmittance were obtained for all 17 phantoms, and methods for quantifying and minimizing sources of systematic errors were outlined. The BMD of the phantom sets extended through most of the in vivo range found in cortical bone. A total of 16-20 repeated measurements of the SOS, thickness, and IR for the phantom set that were conducted over a period of several months showed a small variation in the range of measurements of ±1%-2%. These NCU data were shown to be in agreement with similar results using contact ultrasound to be within 1%-2%. Transmittance

Ocular surface displacement with and without contact lenses during non-contact tonometry.

Directory of Open Access Journals (Sweden)

Ulfah Rimayanti

Full Text Available PURPOSE: To evaluate the displacement of the central ocular surface during non-contact tonometry with and without soft contact lenses and determine the factors associated with the displacement of the central ocular surface and intraocular pressure (IOP reading changes caused by wearing soft contact lenses (CLs. METHODS: One eye each in 21 subjects was studied. The cornea was photographed using a high-speed camera at 5,000 frames/sec during non-contact tonometry without contact lenses (NCL, with -5.0 diopters (D, -0.5 D and +5.0 D CL. The displacement of the ocular surface and the factors affecting displacement at the IOP reading and maximum displacement time were investigated. RESULTS: The IOP readings while wearing +5 D CL were significantly higher than those obtained while wearing -5 D CL. The ocular surface displacement between +5 D CL and other groups were significantly different. A significant positive correlation was found between the ocular surface displacement of subjects at the IOP reading time and the IOP obtained with the non-contact tonometer. A significant negative correlation was found between the ocular surface curvature and the IOP obtained using the non-contact tonometer. The radius of curvature of the ocular surface affected the displacement during the IOP reading and maximum displacement time. CONCLUSIONS: Our results indicate that soft contact lens use changes the ocular surface behavior and IOP readings during non-contact tonometry. The radius of curvature of the eye affects the ocular surface displacement and IOP readings in this situation.

Dynamic contour tonometry (DCT) versus non-contact tonometry (NCT): a comparison study.

Science.gov (United States)

Burvenich, H; Burvenich, E; Vincent, C

2005-01-01

In a prospective study we measured the intraocular pressure (IOP) by means of a Non-Contact Tonometer (NCT) and by means of a Pascal Dynamic Contour Tonometer (DCT), and the Central Corneal Thickness (CCT) by means of a contact pachymeter in 294 emmetropic or ametropic eyes. There is a linear relation between NCT and CCT. This linear relation doesn't exist between DCT and CCT. The same measurements were done before and 6 weeks after a Lasik intervention in 58 myopic eyes. Lasik intervention influences NCT but doesn't influence DCT.

Cardiorespiratory interactions: Noncontact assessment using laser Doppler vibrometry.

Science.gov (United States)

Sirevaag, Erik J; Casaccia, Sara; Richter, Edward A; O'Sullivan, Joseph A; Scalise, Lorenzo; Rohrbaugh, John W

2016-06-01

The application of a noncontact physiological recording technique, based on the method of laser Doppler vibrometry (LDV), is described. The effectiveness of the LDV method as a physiological recording modality lies in the ability to detect very small movements of the skin, associated with internal mechanophysiological activities. The method is validated for a range of cardiovascular variables, extracted from the contour of the carotid pulse waveform as a function of phase of the respiration cycle. Data were obtained from 32 young healthy participants, while resting and breathing spontaneously. Individual beats were assigned to four segments, corresponding with inspiration and expiration peaks and transitional periods. Measures relating to cardiac and vascular dynamics are shown to agree with the pattern of effects seen in the substantial body of literature based on human and animal experiments, and with selected signals recorded simultaneously with conventional sensors. These effects include changes in heart rate, systolic time intervals, and stroke volume. There was also some evidence for vascular adjustments over the respiration cycle. The effectiveness of custom algorithmic approaches for extracting the key signal features was confirmed. The advantages of the LDV method are discussed in terms of the metrological properties and utility in psychophysiological research. Although used here within a suite of conventional sensors and electrodes, the LDV method can be used on a stand-alone, noncontact basis, with no requirement for skin preparation, and can be used in harsh environments including the MR scanner. © 2016 Society for Psychophysiological Research.

Dynamic strain measurements in a sliding microstructured contact

International Nuclear Information System (INIS)

Bennewitz, Roland; David, Jonathan; Lannoy, Charles-Francois de; Drevniok, Benedict; Hubbard-Davis, Paris; Miura, Takashi; Trichtchenko, Olga

2008-01-01

A novel experiment is described which measures the tangential strain development across the contact between a PDMS (polydimethylsiloxane) block and a glass surface during the initial stages of sliding. The surface of the PDMS block has been microfabricated to take the form of a regular array of pyramidal tips at 20 μm separation. Tangential strain is measured by means of light scattering from the interface between the block and surface. Three phases are observed in all experiments: initial shear deformation of the whole PDMS block, a pre-sliding tangential compression of the tip array with stepwise increase of the compressive strain, and sliding in stick-slip movements as revealed by periodic variation of the strain. The stick-slip sliding between the regular tip array and the randomly rough counter surface always takes on the periodicity of the tip array. The fast slip can cause either a sudden increase or a sudden decrease in compressive strain

Measured Strain of Nb3Sn Coils During Excitation and Quench

International Nuclear Information System (INIS)

Caspi, S.; Bartlett, S.E.; Dietderich, D.R.; Ferracin, P.; Gourlay, S.A.; Hannaford, C.R.; Hafalia, A.R.; Lietzke, S.; Mattafirri, M.; Nyman, M.; Sabbi, G.

2005-01-01

The strain in a high field Nb 3 Sn coil was measured during magnet assembly, cool-down, excitation and spot heater quenches. Strain was measured with a full bridge strain gauge mounted directly over the turns and impregnated with the coil. Two such coils were placed in a ''common coil'' fashion capable of reaching 11T at 4.2K. The measured steady state strain in the coil is compared with results obtained using the FEM code ANSYS. During quenches, the transient strain (due to temperature rise) was also measured and compared with the calculated mechanical time response to a quench

Resonant tunneling measurements of size-induced strain relaxation

Science.gov (United States)

Akyuz, Can Deniz

Lattice mismatch strain available in such semiconductor heterostructures as Si/SiGe or GaAs/AlGaAs can be employed to alter the electronic and optoelectronic properties of semiconductor structures and devices. When deep submicron structures are fabricated from strained material, strained layers relax by sidewall expansion giving rise to size- and geometry-dependent strain gradients throughout the structure. This thesis describes a novel experimental technique to probe the size-induced strain relaxation by studying the tunneling current characteristics of strained p-type Si/SiGe resonant tunneling diodes. Our current-voltage measurements on submicron strained p-Si/SiGe double- and triple-barrier resonant tunneling structures as a function of device diameter, D, provide experimental access to both the average strain relaxation (which leads to relative shifts in the tunneling current peak positions) and strain gradients (which give rise to a fine structure in the current peaks due to inhomogeneous strain-induced lateral quantization). We find that strain relaxation is significant, with a large fraction of the strain energy relaxed on average in D ≤ 0.25 m m devices. Further, the in-plane potentials that arise from inhomogeneous strain gradients are large. In the D ˜ 0.2 m m devices, the corresponding lateral potentials are approximately parabolic exceeding ˜ 25 meV near the perimeter. These potentials create discrete hole states in double-barrier structures (single well), and coupled hole states in triple-barrier structures (two wells). Our results are in excellent agreement with finite-element strain calculations in which the strained layers are permitted to relax to a state of minimum energy by sidewall expansion. Size-induced strain relaxation will undoubtedly become a serious technological issue once strained devices are scaled down to the deep submicron regime. Interestingly, our calculations predict and our measurements are consistent with the appearance of

Analytical, Numerical, and Experimental Investigation on a Non-Contact Method for the Measurements of Creep Properties of Ultra-High-Temperature Materials

Science.gov (United States)

Lee, Jonghyun; Hyers, Robert W.; Rogers, Jan R.; Rathz, Thomas J.; Choo, Hahn; Liaw, Peter

2006-01-01

Responsive access to space requires re-use of components such as rocket nozzles that operate at extremely high temperatures. For such applications, new ultra-hightemperature materials that can operate over 2,000 C are required. At the temperatures higher than the fifty percent of the melting temperature, the characterization of creep properties is indispensable. Since conventional methods for the measurement of creep is limited below 1,700 C, a new technique that can be applied at higher temperatures is strongly demanded. This research develops a non-contact method for the measurement of creep at the temperatures over 2,300 C. Using the electrostatic levitator in NASA MSFC, a spherical sample was rotated to cause creep deformation by centrifugal acceleration. The deforming sample was captured with a digital camera and analyzed to measure creep deformation. Numerical and analytical analyses have also been conducted to compare the experimental results. Analytical, numerical, and experimental results showed a good agreement with one another.

Noncontact 3-D Speckle Contrast Diffuse Correlation Tomography of Tissue Blood Flow Distribution.

Science.gov (United States)

Huang, Chong; Irwin, Daniel; Zhao, Mingjun; Shang, Yu; Agochukwu, Nneamaka; Wong, Lesley; Yu, Guoqiang

2017-10-01

Recent advancements in near-infrared diffuse correlation techniques and instrumentation have opened the path for versatile deep tissue microvasculature blood flow imaging systems. Despite this progress there remains a need for a completely noncontact, noninvasive device with high translatability from small/testing (animal) to large/target (human) subjects with trivial application on both. Accordingly, we discuss our newly developed setup which meets this demand, termed noncontact speckle contrast diffuse correlation tomography (nc_scDCT). The nc_scDCT provides fast, continuous, portable, noninvasive, and inexpensive acquisition of 3-D tomographic deep (up to 10 mm) tissue blood flow distributions with straightforward design and customization. The features presented include a finite-element-method implementation for incorporating complex tissue boundaries, fully noncontact hardware for avoiding tissue compression and interactions, rapid data collection with a diffuse speckle contrast method, reflectance-based design promoting experimental translation, extensibility to related techniques, and robust adjustable source and detector patterns and density for high resolution measurement with flexible regions of interest enabling unique application-specific setups. Validation is shown in the detection and characterization of both high and low contrasts in flow relative to the background using tissue phantoms with a pump-connected tube (high) and phantom spheres (low). Furthermore, in vivo validation of extracting spatiotemporal 3-D blood flow distributions and hyperemic response during forearm cuff occlusion is demonstrated. Finally, the success of instrument feasibility in clinical use is examined through the intraoperative imaging of mastectomy skin flap.

Modeling leukocyte-leukocyte non-contact interactions in a lymph node.

Directory of Open Access Journals (Sweden)

Nicola Gritti

Full Text Available The interaction among leukocytes is at the basis of the innate and adaptive immune-response and it is largely ascribed to direct cell-cell contacts. However, the exchange of a number of chemical stimuli (chemokines allows also non-contact interaction during the immunological response. We want here to evaluate the extent of the effect of the non-contact interactions on the observed leukocyte-leukocyte kinematics and their interaction duration. To this aim we adopt a simplified mean field description inspired by the Keller-Segel chemotaxis model, of which we report an analytical solution suited for slowly varying sources of chemokines. Since our focus is on the non-contact interactions, leukocyte-leukocyte contact interactions are simulated only by means of a space dependent friction coefficient of the cells. The analytical solution of the Keller-Segel model is then taken as the basis of numerical simulations of interactions between leukocytes and their duration. The mean field interaction force that we derive has a time-space separable form and depends on the chemotaxis sensitivity parameter as well as on the chemokines diffusion coefficient and their degradation rate. All these parameters affect the distribution of the interaction durations. We draw a successful qualitative comparison between simulated data and sets of experimental data for DC-NK cells interaction duration and other kinematic parameters. Remarkably, the predicted percentage of the leukocyte-leukocyte interactions falls in the experimental range and depends (~25% increase upon the chemotactic parameter indicating a non-negligible direct effect of the non-contact interaction on the leukocyte interactions.

Modeling leukocyte-leukocyte non-contact interactions in a lymph node.

Science.gov (United States)

Gritti, Nicola; Caccia, Michele; Sironi, Laura; Collini, Maddalena; D'Alfonso, Laura; Granucci, Francesca; Zanoni, Ivan; Chirico, Giuseppe

2013-01-01

The interaction among leukocytes is at the basis of the innate and adaptive immune-response and it is largely ascribed to direct cell-cell contacts. However, the exchange of a number of chemical stimuli (chemokines) allows also non-contact interaction during the immunological response. We want here to evaluate the extent of the effect of the non-contact interactions on the observed leukocyte-leukocyte kinematics and their interaction duration. To this aim we adopt a simplified mean field description inspired by the Keller-Segel chemotaxis model, of which we report an analytical solution suited for slowly varying sources of chemokines. Since our focus is on the non-contact interactions, leukocyte-leukocyte contact interactions are simulated only by means of a space dependent friction coefficient of the cells. The analytical solution of the Keller-Segel model is then taken as the basis of numerical simulations of interactions between leukocytes and their duration. The mean field interaction force that we derive has a time-space separable form and depends on the chemotaxis sensitivity parameter as well as on the chemokines diffusion coefficient and their degradation rate. All these parameters affect the distribution of the interaction durations. We draw a successful qualitative comparison between simulated data and sets of experimental data for DC-NK cells interaction duration and other kinematic parameters. Remarkably, the predicted percentage of the leukocyte-leukocyte interactions falls in the experimental range and depends (~25% increase) upon the chemotactic parameter indicating a non-negligible direct effect of the non-contact interaction on the leukocyte interactions.

Lattice strain measurements on sandstones under load using neutron diffraction

Science.gov (United States)

Frischbutter, A.; Neov, D.; Scheffzük, Ch.; Vrána, M.; Walther, K.

2000-11-01

Neutron diffraction methods (both time-of-flight- and angle-dispersive diffraction) are applied to intracrystalline strain measurements on geological samples undergoing uniaxial increasing compressional load. The experiments were carried out on Cretaceous sandstones from the Elbezone (East Germany), consisting of >95% quartz which are bedded but without crystallographic preferred orientation of quartz. From the stress-strain relation the Young's modulus for our quartz sample was determined to be (72.2±2.9) GPa using results of the neutron time-of-flight method. The influence of different kinds of bedding in sandstones (laminated and convolute bedding) could be determined. We observed differences of factor 2 (convolute bedding) and 3 (laminated bedding) for the elastic stiffness, determined with angle dispersive neutron diffraction (crystallographic strain) and with strain gauges (mechanical strain). The data indicate which geological conditions may influence the stress-strain behaviour of geological materials. The influence of bedding on the stress-strain behaviour of a laminated bedded sandstone was indicated by direct residual stress measurements using neutron time-of-flight diffraction. The measurements were carried out six days after unloading the sample. Residual strain was measured for three positions from the centre to the periphery and within two radial directions of the cylinder. We observed that residual strain changes from extension to compression in a different manner for two perpendicular directions of the bedding plane.

Visual Measurement of Suture Strain for Robotic Surgery

Directory of Open Access Journals (Sweden)

John Martell

2011-01-01

Full Text Available Minimally invasive surgical procedures offer advantages of smaller incisions, decreased hospital length of stay, and rapid postoperative recovery to the patient. Surgical robots improve access and visualization intraoperatively and have expanded the indications for minimally invasive procedures. A limitation of the DaVinci surgical robot is a lack of sensory feedback to the operative surgeon. Experienced robotic surgeons use visual interpretation of tissue and suture deformation as a surrogate for tactile feedback. A difficulty encountered during robotic surgery is maintaining adequate suture tension while tying knots or following a running anastomotic suture. Displaying suture strain in real time has potential to decrease the learning curve and improve the performance and safety of robotic surgical procedures. Conventional strain measurement methods involve installation of complex sensors on the robotic instruments. This paper presents a noninvasive video processing-based method to determine strain in surgical sutures. The method accurately calculates strain in suture by processing video from the existing surgical camera, making implementation uncomplicated. The video analysis method was developed and validated using video of suture strain standards on a servohydraulic testing system. The video-based suture strain algorithm is shown capable of measuring suture strains of 0.2% with subpixel resolution and proven reliability under various conditions.

Features of the non-contact carotid pressure waveform: Cardiac and vascular dynamics during rebreathing

Science.gov (United States)

Casaccia, S.; Sirevaag, E. J.; Richter, E. J.; O'Sullivan, J. A.; Scalise, L.; Rohrbaugh, J. W.

2016-10-01

This report amplifies and extends prior descriptions of the use of laser Doppler vibrometry (LDV) as a method for assessing cardiovascular activity, on a non-contact basis. A rebreathing task (n = 35 healthy individuals) was used to elicit multiple effects associated with changes in autonomic drive as well as blood gases including hypercapnia. The LDV pulse was obtained from two sites overlying the carotid artery, separated by 40 mm. A robust pulse signal was obtained from both sites, in accord with the well-described changes in carotid diameter over the blood pressure cycle. Emphasis was placed on extracting timing measures from the LDV pulse, which could serve as surrogate measures of pulse wave velocity (PWV) and the associated arterial stiffness. For validation purposes, a standard measure of pulse transit time (PTT) to the radial artery was obtained using a tonometric sensor. Two key measures of timing were extracted from the LDV pulse. One involved the transit time along the 40 mm distance separating the two LDV measurement sites. A second measure involved the timing of a late feature of the LDV pulse contour, which was interpreted as reflection wave latency and thus a measure of round-trip travel time. Both LDV measures agreed with the conventional PTT measure, in disclosing increased PWV during periods of active rebreathing. These results thus provide additional evidence that measures based on the non-contact LDV technique might provide surrogate measures for those obtained using conventional, more obtrusive assessment methods that require attached sensors.

Non-contact Real-time heart rate measurements based on high speed circuit technology research

Science.gov (United States)

Wu, Jizhe; Liu, Xiaohua; Kong, Lingqin; Shi, Cong; Liu, Ming; Hui, Mei; Dong, Liquan; Zhao, Yuejin

2015-08-01

In recent years, morbidity and mortality of the cardiovascular or cerebrovascular disease, which threaten human health greatly, increased year by year. Heart rate is an important index of these diseases. To address this status, the paper puts forward a kind of simple structure, easy operation, suitable for large populations of daily monitoring non-contact heart rate measurement. In the method we use imaging equipment video sensitive areas. The changes of light intensity reflected through the image grayscale average. The light change is caused by changes in blood volume. We video the people face which include the sensitive areas (ROI), and use high-speed processing circuit to save the video as AVI format into memory. After processing the whole video of a period of time, we draw curve of each color channel with frame number as horizontal axis. Then get heart rate from the curve. We use independent component analysis (ICA) to restrain noise of sports interference, realized the accurate extraction of heart rate signal under the motion state. We design an algorithm, based on high-speed processing circuit, for face recognition and tracking to automatically get face region. We do grayscale average processing to the recognized image, get RGB three grayscale curves, and extract a clearer pulse wave curves through independent component analysis, and then we get the heart rate under the motion state. At last, by means of compare our system with Fingertip Pulse Oximeter, result show the system can realize a more accurate measurement, the error is less than 3 pats per minute.

Development and validation of a noncontact spectroscopic device for hemoglobin estimation at point-of-care

Science.gov (United States)

Sarkar, Probir Kumar; Pal, Sanchari; Polley, Nabarun; Aich, Rajarshi; Adhikari, Aniruddha; Halder, Animesh; Chakrabarti, Subhananda; Chakrabarti, Prantar; Pal, Samir Kumar

2017-05-01

Anemia severely and adversely affects human health and socioeconomic development. Measuring hemoglobin with the minimal involvement of human and financial resources has always been challenging. We describe a translational spectroscopic technique for noncontact hemoglobin measurement at low-resource point-of-care settings in human subjects, independent of their skin color, age, and sex, by measuring the optical spectrum of the blood flowing in the vascular bed of the bulbar conjunctiva. We developed software on the LabVIEW platform for automatic data acquisition and interpretation by nonexperts. The device is calibrated by comparing the differential absorbance of light of wavelength 576 and 600 nm with the clinical hemoglobin level of the subject. Our proposed method is consistent with the results obtained using the current gold standard, the automated hematology analyzer. The proposed noncontact optical device for hemoglobin estimation is highly efficient, inexpensive, feasible, and extremely useful in low-resource point-of-care settings. The device output correlates with the different degrees of anemia with absolute and trending accuracy similar to those of widely used invasive methods. Moreover, the device can instantaneously transmit the generated report to a medical expert through e-mail, text messaging, or mobile apps.

Automatic Bowel Motility Evaluation Technique for Noncontact Sound Recordings

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Ryunosuke Sato

2018-06-01

Full Text Available Information on bowel motility can be obtained via magnetic resonance imaging (MRIs and X-ray imaging. However, these approaches require expensive medical instruments and are unsuitable for frequent monitoring. Bowel sounds (BS can be conveniently obtained using electronic stethoscopes and have recently been employed for the evaluation of bowel motility. More recently, our group proposed a novel method to evaluate bowel motility on the basis of BS acquired using a noncontact microphone. However, the method required manually detecting BS in the sound recordings, and manual segmentation is inconvenient and time consuming. To address this issue, herein, we propose a new method to automatically evaluate bowel motility for noncontact sound recordings. Using simulations for the sound recordings obtained from 20 human participants, we showed that the proposed method achieves an accuracy of approximately 90% in automatic bowel sound detection when acoustic feature power-normalized cepstral coefficients are used as inputs to artificial neural networks. Furthermore, we showed that bowel motility can be evaluated based on the three acoustic features in the time domain extracted by our method: BS per minute, signal-to-noise ratio, and sound-to-sound interval. The proposed method has the potential to contribute towards the development of noncontact evaluation methods for bowel motility.

Quantitative performance characterization of three-dimensional noncontact fluorescence molecular tomography

Science.gov (United States)

Favicchio, Rosy; Psycharakis, Stylianos; Schönig, Kai; Bartsch, Dusan; Mamalaki, Clio; Papamatheakis, Joseph; Ripoll, Jorge; Zacharakis, Giannis

2016-02-01

Fluorescent proteins and dyes are routine tools for biological research to describe the behavior of genes, proteins, and cells, as well as more complex physiological dynamics such as vessel permeability and pharmacokinetics. The use of these probes in whole body in vivo imaging would allow extending the range and scope of current biomedical applications and would be of great interest. In order to comply with a wide variety of application demands, in vivo imaging platform requirements span from wide spectral coverage to precise quantification capabilities. Fluorescence molecular tomography (FMT) detects and reconstructs in three dimensions the distribution of a fluorophore in vivo. Noncontact FMT allows fast scanning of an excitation source and noninvasive measurement of emitted fluorescent light using a virtual array detector operating in free space. Here, a rigorous process is defined that fully characterizes the performance of a custom-built horizontal noncontact FMT setup. Dynamic range, sensitivity, and quantitative accuracy across the visible spectrum were evaluated using fluorophores with emissions between 520 and 660 nm. These results demonstrate that high-performance quantitative three-dimensional visible light FMT allowed the detection of challenging mesenteric lymph nodes in vivo and the comparison of spectrally distinct fluorescent reporters in cell culture.

Utilizing Photogrammetry and Strain Gage Measurement to Characterize Pressurization of an Inflatable Module

Science.gov (United States)

Valle, Gerard D.; Selig, Molly; Litteken, Doug; Oliveras, Ovidio

2012-01-01

This paper documents the integration of a large hatch penetration into an inflatable module. This paper also documents the comparison of analytical load predictions with measured results utilizing strain measurement. Strain was measured by utilizing photogrammetric measurement and through measurement obtained from strain gages mounted to selected clevises that interface with the structural webbings. Bench testing showed good correlation between strain measurement obtained from an extensometer and photogrammetric measurement especially after the fabric has transitioned through the low load/high strain region of the curve. Test results for the full-scale torus showed mixed results in the lower load and thus lower strain regions. Overall strain, and thus load, measured by strain gages and photogrammetry tracked fairly well with analytical predictions. Methods and areas of improvements are discussed.

Unsteady Aerodynamic Force Sensing from Measured Strain

Science.gov (United States)

Pak, Chan-Gi

2016-01-01

A simple approach for computing unsteady aerodynamic forces from simulated measured strain data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady strain using the two-step approach. Velocities and accelerations of the structure are computed using the autoregressive moving average model, on-line parameter estimator, low-pass filter, and a least-squares curve fitting method together with analytical derivatives with respect to time. Finally, aerodynamic forces over the wing are computed using modal aerodynamic influence coefficient matrices, a rational function approximation, and a time-marching algorithm. A cantilevered rectangular wing built and tested at the NASA Langley Research Center (Hampton, Virginia, USA) in 1959 is used to validate the simple approach. Unsteady aerodynamic forces as well as wing deflections, velocities, accelerations, and strains are computed using the CFL3D computational fluid dynamics (CFD) code and an MSC/NASTRAN code (MSC Software Corporation, Newport Beach, California, USA), and these CFL3D-based results are assumed as measured quantities. Based on the measured strains, wing deflections, velocities, accelerations, and aerodynamic forces are computed using the proposed approach. These computed deflections, velocities, accelerations, and unsteady aerodynamic forces are compared with the CFL3D/NASTRAN-based results. In general, computed aerodynamic forces based on the lifting surface theory in subsonic speeds are in good agreement with the target aerodynamic forces generated using CFL3D code with the Euler equation. Excellent aeroelastic responses are obtained even with unsteady strain data under the signal to noise ratio of -9.8dB. The deflections, velocities, and accelerations at each sensor location are independent of structural and aerodynamic models. Therefore, the distributed strain data together with the current proposed approaches can be used as distributed deflection

Utilizing Photogrammetry and Strain Gage Measurement to Characterize Pressurization of Inflatable Modules

Science.gov (United States)

Mohammed, Anil

2011-01-01

This paper focuses on integrating a large hatch penetration into inflatable modules of various constructions. This paper also compares load predictions with test measurements. The strain was measured by utilizing photogrammetric methods and strain gages mounted to select clevises that interface with the structural webbings. Bench testing showed good correlation between strain data collected from an extensometer and photogrammetric measurements, even when the material transitioned from the low load to high load strain region of the curve. The full-scale torus design module showed mixed results as well in the lower load and high strain regions. After thorough analysis of photogrammetric measurements, strain gage measurements, and predicted load, the photogrammetric measurements seem to be off by a factor of two.

Non-Destructive Measurement of Residual Strain in Connecting Rods Using Neutrons

Energy Technology Data Exchange (ETDEWEB)

Ikeda, Tomohiro [Honda R& D; Bunn, Jeffrey R. [ORNL; Fancher, Christopher M. [ORNL; Seid, Alan [Honda R& D; Motani, Ryuta [Honda R& D; Matsuda, Hideki [Honda R& D; Okayama, Tatsuya [Honda R& D

2018-04-01

Increasing the strength of materials is effective in reducing weight and boosting structural part performance, but there are cases in where the residual strain generated during the process of manufacturing of high-strength materials results in a decline of durability. It is therefore important to understand how the residual strain in a manufactured component changes due to processing conditions. In the case of a connecting rod, because the strain load on the connecting rod rib sections is high, it is necessary to clearly understand the distribution of strain in the ribs. However, because residual strain is generally measured by using X-ray diffractometers or strain gauges, measurements are limited to the surface layer of the parts. Neutron beams, however, have a higher penetration depth than X-rays, allowing for strain measurement in the bulk material. The research discussed within this paper consists of non-destructive residual strain measurements in the interior of connecting rods using the 2nd Generation Neutron Residual Stress Mapping Facility (NRSF2) at Oak Ridge National Laboratory, measuring the Fe (211) diffraction peak position of the ferrite phase. The interior strain distribution of connecting rod, which prepared under different manufacturing processes, was revealed. By the visualization of interior strains, clear understandings of differences in various processing conditions were obtained. In addition, it is known that the peak width, which is also obtained during measurement, is suggestive of the size of crystallites in the structure; however the peak width can additionally be caused by microstresses and material dislocations.

Engineering related neutron diffraction measurements probing strains, texture and microstructure

Energy Technology Data Exchange (ETDEWEB)

Clausen, Bjorn [Los Alamos National Laboratory; Brown, Donald W [Los Alamos National Laboratory; Tome, Carlos N [Los Alamos National Laboratory; Balogh, Levente [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory

2010-01-01

Neutron diffraction has been used for engineering applications for nearly three decades. The basis of the technique is powder diffraction following Bragg's Law. From the measured diffraction patterns information about internal, or residual, strain can be deduced from the peak positions, texture information can be extracted from the peak intensities, and finally the peak widths can provide information about the microstructure, e.g. dislocation densities and grain sizes. The strains are measured directly from changes in lattice parameters, however, in many cases it is non-trivial to determine macroscopic values of stress or strain from the measured data. The effects of intergranular strains must be considered, and combining the neutron diffraction measurements with polycrystal deformation modeling has proven invaluable in determining the overall stress and strain values of interest in designing and dimensioning engineering components. Furthelmore, the combined use of measurements and modeling has provided a tool for elucidating basic material properties, such as critical resolved shear stresses for the active deformation modes and their evolution as a function of applied deformation.

Development of Non-contact Respiratory Monitoring System for Newborn Using a FG Vision Sensor

Science.gov (United States)

Kurami, Yoshiyuki; Itoh, Yushi; Natori, Michiya; Ohzeki, Kazuo; Aoki, Yoshimitsu

In recent years, development of neonatal care is strongly hoped, with increase of the low-birth-weight baby birth rate. Especially respiration of low-birth-weight baby is incertitude because central nerve and respiratory function is immature. Therefore, a low-birth-weight baby often causes a disease of respiration. In a NICU (Neonatal Intensive Care Unit), neonatal respiration is monitored using cardio-respiratory monitor and pulse oximeter at all times. These contact-type sensors can measure respiratory rate and SpO2 (Saturation of Peripheral Oxygen). However, because a contact-type sensor might damage the newborn's skin, it is a real burden to monitor neonatal respiration. Therefore, we developed the respiratory monitoring system for newborn using a FG (Fiber Grating) vision sensor. FG vision sensor is an active stereo vision sensor, it is possible for non-contact 3D measurement. A respiratory waveform is calculated by detecting the vertical motion of the thoracic and abdominal region with respiration. We attempted clinical experiment in the NICU, and confirmed the accuracy of the obtained respiratory waveform was high. Non-contact respiratory monitoring of newborn using a FG vision sensor enabled the minimally invasive procedure.

Noncontact measurement of electrostatic fields: Verification of modeled potentials within ion mobility spectrometer drift tube designs

International Nuclear Information System (INIS)

Scott, Jill R.; Tremblay, Paul L.

2007-01-01

The heart of an ion mobility spectrometer is the drift region where ion separation occurs. While the electrostatic potentials within a drift tube design can be modeled, no method for independently validating the electrostatic field has previously been reported. Two basic drift tube designs were modeled using SIMION 7.0 to reveal the expected electrostatic fields: (1) A traditional alternating set of electrodes and insulators and (2) a truly linear drift tube. One version of the alternating electrode/insulator drift tube and two versions of linear drift tubes were then fabricated. The stacked alternating electrodes/insulators were connected through a resistor network to generate the electrostatic gradient in the drift tube. The two linear drift tube designs consisted of two types of resistive drift tubes with one tube consisting of a resistive coating within an insulating tube and the other tube composed of resistive ferrites. The electrostatic fields within each type of drift tube were then evaluated by a noncontact method using a Kelvin-Zisman type electrostatic voltmeter and probe (results for alternative measurement methods provided in supplementary material). The experimental results were then compared with the electrostatic fields predicted by SIMION. Both the modeling and experimental measurements reveal that the electrostatic fields within a stacked ion mobility spectrometer drift tube are only pseudo-linear, while the electrostatic fields within a resistive drift tube approach perfect linearity

Short-Range Noncontact Sensors for Healthcare and Other Emerging Applications: A Review

Directory of Open Access Journals (Sweden)

Changzhan Gu

2016-07-01

Full Text Available Short-range noncontact sensors are capable of remotely detecting the precise movements of the subjects or wirelessly estimating the distance from the sensor to the subject. They find wide applications in our day lives such as noncontact vital sign detection of heart beat and respiration, sleep monitoring, occupancy sensing, and gesture sensing. In recent years, short-range noncontact sensors are attracting more and more efforts from both academia and industry due to their vast applications. Compared to other radar architectures such as pulse radar and frequency-modulated continuous-wave (FMCW radar, Doppler radar is gaining more popularity in terms of system integration and low-power operation. This paper reviews the recent technical advances in Doppler radars for healthcare applications, including system hardware improvement, digital signal processing, and chip integration. This paper also discusses the hybrid FMCW-interferometry radars and the emerging applications and the future trends.

Active noncontact tonometer for glaucoma detection

Science.gov (United States)

Han, Yanmei; Bryanston-Cross, Peter J.; Lee, Wing K. A.; Hero, Mark

2002-09-01

Glaucoma is an increasingly common cause of visual impairment, and in some cases causes blindness. The approach to develop a low cost and non-contact tonometer for the detection of glaucoma, to replace the Goldmann tonometer used worldwide, is presented in this paper. The new tonometer exploits the vibration property of the cornea - the resonance frequency of the cornea rises with increasing intra-ocular pressure (IOP). An audio frequency signal is used to vibrate the cornea of the eye, the vibration of the cornea is measured using a fibre optic lever probe, and then the IOP can be calculated from the detected resonance frequency of the cornea. The initial PC-version experiment system of the new tonometer has been demonstrated and preliminary testing has been performed, showing a suitable sensitivity in detecting the resonance frequency against the IOP using both the simulated-eye model and the pig's eye. The initial system has been improved to be suitable for greater than 15mm detecting distance, and the measurement of vibrations of human cornea in-vivo has been carried out. Work is now focusing on increasing the sensitivity of the fibre probe, and reducing the measuring time to less than 1 second.

A new strain gage method for measuring the contractile strain ratio of Zircaloy tubing

International Nuclear Information System (INIS)

Hwang, S.K.; Sabol, G.P.

1988-01-01

An improved strain gage method for determining the contractile strain ratio (CSR) of Zircaloy tubing was developed. The new method consists of a number of load-unload cyclings at approximately 0.2% plastic strain interval. With this method the CSR of Zircaloy-4 tubing could be determined accurately because it was possible to separate the plastic strains from the elastic strain involvement. The CSR values determined by use of the new method were in good agreement with those calculated from conventional post-test manual measurements. The CSR of the tubing was found to decrease with the amount of deformation during testing because of uneven plastic flow in the gage section. A new technique of inscribing gage marks by use of a YAG laser is discussed. (orig.)

Hamstring and Quadriceps Isokinetic Strength Deficits Are Weak Risk Factors for Hamstring Strain Injuries: A 4-Year Cohort Study

NARCIS (Netherlands)

van Dyk, Nicol; Bahr, Roald; Whiteley, Rodney; Tol, Johannes L.; Kumar, Bhavesh D.; Hamilton, Bruce; Farooq, Abdulaziz; Witvrouw, Erik

2016-01-01

A hamstring strain injury (HSI) has become the most common noncontact injury in soccer. Isokinetic muscle strength deficits are considered a risk factor for HSIs. However, underpowered studies with small sample sizes unable to determine small associations have led to inconclusive results regarding

Acanthamoeba keratitis in a non-contact lens wearer with human immunodeficiency virus

DEFF Research Database (Denmark)

Hansen, Birgitte Rønde; Kronborg, Gitte

2003-01-01

, and was treated with various topical antibiotics and steroids. 13 months after symptom onset the eye was removed owing to serious scarring of cornea and unbearable pain. Microbiological and histopathological examination of the cornea showed Acanthamoeba. In non-contact lens wearers suffering from Acanthamoeba......Acanthamoeba keratitis is potentially blinding and often associated with contact lens wearing. A human immunodeficiency virus (HIV)-positive patient, a non-contact lens wearer, presented with keratitis. She experienced a protracted course of disease, characterized by exacerbations and remissions...

Non-contact measurement of partial gas pressure and distribution of elemental composition using energy-resolved neutron imaging

Directory of Open Access Journals (Sweden)

A. S. Tremsin

2017-01-01

Full Text Available Neutron resonance absorption imaging is a non-destructive technique that can characterize the elemental composition of a sample by measuring nuclear resonances in the spectrum of a transmitted beam. Recent developments in pixelated time-of-flight imaging detectors coupled with pulsed neutron sources pose new opportunities for energy-resolved imaging. In this paper we demonstrate non-contact measurements of the partial pressure of xenon and krypton gases encapsulated in a steel pipe while simultaneously passing the neutron beam through high-Z materials. The configuration was chosen as a proof of principle demonstration of the potential to make non-destructive measurement of gas composition in nuclear fuel rods. The pressure measured from neutron transmission spectra (∼739 ± 98 kPa and ∼751 ± 154 kPa for two Xe resonances is in relatively good agreement with the pressure value of ∼758 ± 21 kPa measured by a pressure gauge. This type of imaging has been performed previously for solids with a spatial resolution of ∼ 100 μm. In the present study it is demonstrated that the high penetration capability of epithermal neutrons enables quantitative mapping of gases encapsulate within high-Z materials such as steel, tungsten, urania and others. This technique may be beneficial for the non-destructive testing of bulk composition of objects (such as spent nuclear fuel assemblies and others containing various elements opaque to other more conventional imaging techniques. The ability to image the gaseous substances concealed within solid materials also allows non-destructive leak testing of various containers and ultimately measurement of gas partial pressures with sub-mm spatial resolution.

Strain Measurement System Developed for Biaxially Loaded Cruciform Specimens

Science.gov (United States)

Krause, David L.

2000-01-01

A new extensometer system developed at the NASA Glenn Research Center at Lewis Field measures test area strains along two orthogonal axes in flat cruciform specimens. This system incorporates standard axial contact extensometers to provide a cost-effective high-precision instrument. The device was validated for use by extensive testing of a stainless steel specimen, with specimen temperatures ranging from room temperature to 1100 F. In-plane loading conditions included several static biaxial load ratios, plus cyclic loadings of various waveform shapes, frequencies, magnitudes, and durations. The extensometer system measurements were compared with strain gauge data at room temperature and with calculated strain values for elevated-temperature measurements. All testing was performed in house in Glenn's Benchmark Test Facility in-plane biaxial load frame.

Study and Experiment on Non-Contact Voltage Sensor Suitable for Three-Phase Transmission Line.

Science.gov (United States)

Zhou, Qiang; He, Wei; Xiao, Dongping; Li, Songnong; Zhou, Kongjun

2015-12-30

A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase difference exists between detection signal and voltage signal to be measured, and the detection signal cannot accurately and timely reflect the change of conductor voltage signal to be measured. By aiming at the current problems of electric transformation, based on electrostatic induction principle, this paper designed a non-contact voltage sensor and gained detection signal of the sensor through electrostatic coupling for the electric field generated by electric charges of the conductor to be measured. The insulation structure design of the sensor is simple and its volume is small; phase difference of sensor measurement is effectively reduced through optimization design of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage sensor was tested on the experimental platform of simulating three-phase transmission line. According to the result, the designed non-contact voltage sensor can realize accurate and real-time measurement for the conductor voltage. It can be applied to online monitoring for the voltage of three-phase transmission line or three-phase distribution network line, which is in accordance with the development direction of the smart grid.

Measurement of the thermophysical properties of industrial liquid metallic alloys by non-contact calorimetry under reduced gravity

International Nuclear Information System (INIS)

Wunderlich, R.K.; Fecht, H.-J.

2001-01-01

Full Text: The numerical modeling of casting and solidification is becoming of increased importance in industrial process design. While the numerical algorithms have made large progress towards real process design and optimization, there is a pronounced lack of precise thermophysical input data. This lack is caused by the high chemical reactivity of many metallic alloys in the liquid phase making conventional measurement techniques such as differential thermal analysis difficult if at all possible to apply. In this contribution we report about a project planning to use containerless electromagnetic processing under reduced gravity conditions for thermophysical property measurement of industrially relevant alloys. Alloys of interest are, among others, Ti-alloys, Ni-base superalloys, and steels. In preparation of this project, a survey among leading European industries was conducted revealing properties such as melting range, fraction solid/liquid, specific heat capacity, enthalpy, as well as density, viscosity and surface tension as properties most in need. Non-contact calorimetry of electromagnetically levitated specimens was developed for an investigation of the thermophysical properties of Zr-alloys in the liquid phase. These methods have been applied successfully under reduced gravity conditions on board spacelab to the measurement of the specific heat capacity by modulation calorimetry, the enthalpy of fusion, the total hemispherical emissivity and for an effective thermal conductivity. Specific examples from these experiments demonstrating the applicability of these methods for quantitative calorimetry as well as application at higher Biot numbers will be discussed. New developments include modulation calorimetry in the two phase region for the measurement of the fraction solid. (author)

A production of non-strain spacing of lattice planes measurement equipment and a measurement of general structure material

International Nuclear Information System (INIS)

Minakawa, Nobuaki; Moriai, Atsushi; Morii, Yukio

2001-01-01

It is necessary to determine Δd/d in the internal stress measurement by the neutron diffraction method. Therefore, in case the non-strain spacing of lattice planes d 0 (hkl) is measured using bulk material, even though it does and attaches in a sample table length or every width and it is performing the diffraction measurement, it is difficult to determine for a true non-strain spacing of lattice planes by a processing strain, the grain-orientation, etc. It is available for the infinite thing spacing of lattice planes near non-strain condition to be measured by doing random rotation for bulk material in a beam center, and measuring an average spacing of lattice planes. Practical non-strain spacing of lattice planes measurement equipment was made, and the measurement was performed about much structure material. (author)

Measuring systolic ankle and toe pressure using the strain gauge technique--a comparison study between mercury and indium-gallium strain gauges

DEFF Research Database (Denmark)

Broholm, Rikke; Wiinberg, Niels; Simonsen, Lene

2014-01-01

BACKGROUND: Measurement of the ankle and toe pressures are often performed using a plethysmograph, compression cuffs and a strain gauge. Usually, the strain gauge contains mercury but other alternatives exist. From 2014, the mercury-containing strain gauge will no longer be available in the Europ......BACKGROUND: Measurement of the ankle and toe pressures are often performed using a plethysmograph, compression cuffs and a strain gauge. Usually, the strain gauge contains mercury but other alternatives exist. From 2014, the mercury-containing strain gauge will no longer be available...... in the European Union. The aim of this study was to compare an indium-gallium strain gauge to the established mercury-containing strain gauge. METHODS: Consecutive patients referred to the Department of Clinical Physiology and Nuclear Medicine at Bispebjerg and Frederiksberg Hospitals for measurements of systolic...... ankle and toe pressures volunteered for the study. Ankle and toe pressures were measured twice with the mercury and the indium-gallium strain gauge in random order. Comparison of the correlation between the mean pressure using the mercury and the indium-gallium device and the difference between the two...

Continuous control systems for non-contact ECG

Science.gov (United States)

Kodkin, Vladimir L.; Yakovleva, Galina V.; Smirnov, Alexey S.

2017-03-01

South Ural State University is still conducting the research work dedicated to innovations in biomedicine. Development of system for continuous control and diagnosis of the functional state in large groups of people is based on studies of non-contact ECG recording reported by the authors at the SPIE conference in 2016. The next stage of studies has been performed this year.

Clinical evaluation of the Non-Contact Tonometer Mark II.

Science.gov (United States)

Chauhan, B C; Henson, D B

1988-09-01

The purpose of this investigation was to test the reliability of the American Optical Non-Contact Tonometer Mark II (NCT II) using the Goldmann Applanation Tonometer (GAT) as the validating instrument. The sample contained 102 consecutive patients from our University Eye Clinic, of whom one-half had 4 NCT II measurements first, followed by 4 GAT measurements; the other one-half had 4 GAT measurements first, followed by 4 NCT II measurements. No significant change in intraocular pressure (IOP) was noted over the measurement sequence with either instrument. There was no significant difference between paired NCT II and GAT readings when the NCT II was used first; however, a highly significant difference between paired readings was obtained when the GAT was used first, indicating that the GAT measurement produced a delayed reduction in the IOP. This effect did not occur with the NCT II. Although the NCT II is shown to have a good overall reliability when compared to the GAT in both protocols, the agreement between any two tonometers may be influenced greatly by the very process of taking a measurement and by the dynamic nature of the IOP.

Non-contact feature detection using ultrasonic Lamb waves

Science.gov (United States)

Sinha, Dipen N [Los Alamos, NM

2011-06-28

Apparatus and method for non-contact ultrasonic detection of features on or within the walls of hollow pipes are described. An air-coupled, high-power ultrasonic transducer for generating guided waves in the pipe wall, and a high-sensitivity, air-coupled transducer for detecting these waves, are disposed at a distance apart and at chosen angle with respect to the surface of the pipe, either inside of or outside of the pipe. Measurements may be made in reflection or transmission modes depending on the relative position of the transducers and the pipe. Data are taken by sweeping the frequency of the incident ultrasonic waves, using a tracking narrow-band filter to reduce detected noise, and transforming the frequency domain data into the time domain using fast Fourier transformation, if required.

A real-time non-contact monitoring method of subsea pipelines

Directory of Open Access Journals (Sweden)

Song Dalei

2015-01-01

Full Text Available To monitoring the subsea pipeline in real-time, a special potentiometric sensor array and a potential prediction model are presented in this paper. Firstly, to measure the potential of seawater, a special potentiometric sensor array with Ag/AgCl all-solid-state reference electrodes is first developed in this paper. Secondly, according to the obtained distribution law of electric field intensities a prediction model of the pipeline potentials is developed. Finally, the potentiometric sensor array is applied in sink experiment and the prediction model is validated by the sink measurements. The maximum error for pipeline potential prediction model is 1.1 mV. The proposed non-contact monitoring method for subsea pipeline can predict the potential of sea pipeline in real-time, thus providing important information for further subsea pipeline maintenance.

The use of pulsed neutron diffraction to measure strain in composites

International Nuclear Information System (INIS)

Bourke, M.A.M.; Goldstone, J.A.; Shi, N.; Gray, G.T. III; James, M.R.

1994-01-01

Neutron diffraction is a technique for measuring strain in crystalline materials. It is non destructive, phase discriminatory and more penetrating than X rays. Pulsed neutron sources (in contrast with steady state reactor sources) are particularly appropriate for examining heterogeneous materials or for recording the polycrystalline response of all lattice reflections. Several different aspects of composite behavior can be characterized and examples are given of residual strain measurements, strain relaxation during heating, applied loading, and determination of the strain distribution function

Development of shearography for surface strain measurement of non planar objects

International Nuclear Information System (INIS)

Groves, Roger Michael

2001-01-01

The subject of this thesis is the development of optical instrumentation for surface strain measurement of non-planar objects. The speckle interferometry technique of shearography is used to perform quantitative measurements of surface strain on non-planar objects and to compensate these measurements for the errors that are due to the shape and slope of the object. Shearography is an optical technique that is usually used for defect location and for qualitative strain characterisation. In this thesis a multi-component shearography system is described that can measure the six components of displacement gradient. From these measurements the surface strain can be fully characterised. For non-planar objects an error is introduced into the displacement gradient measurement due to the variation of the sensitivity vector across the field of view and the variation in the magnitude of applied shear due to the curvature of the object surface. To correct for these errors requires a knowledge of the slope and shape of the object. Shearography may also be used to measure object slope and shape by a source displacement technique. Therefore slope, shape and surface strain may be measured using the same optical system. The thesis describes a method of multiplexing the shear direction using polarisation switching, a method of measuring the source position using shadow Moire and the shearography source displacement technique for measuring the surface slope and shape of objects. The multi-component shearography system is used to perform measurements of the six components of surface strain, on an industrial component, with a correction applied for errors due to the shape and slope of the object. (author)

DistancePPG: Robust non-contact vital signs monitoring using a camera

Science.gov (United States)

Kumar, Mayank; Veeraraghavan, Ashok; Sabharwal, Ashutosh

2015-01-01

Vital signs such as pulse rate and breathing rate are currently measured using contact probes. But, non-contact methods for measuring vital signs are desirable both in hospital settings (e.g. in NICU) and for ubiquitous in-situ health tracking (e.g. on mobile phone and computers with webcams). Recently, camera-based non-contact vital sign monitoring have been shown to be feasible. However, camera-based vital sign monitoring is challenging for people with darker skin tone, under low lighting conditions, and/or during movement of an individual in front of the camera. In this paper, we propose distancePPG, a new camera-based vital sign estimation algorithm which addresses these challenges. DistancePPG proposes a new method of combining skin-color change signals from different tracked regions of the face using a weighted average, where the weights depend on the blood perfusion and incident light intensity in the region, to improve the signal-to-noise ratio (SNR) of camera-based estimate. One of our key contributions is a new automatic method for determining the weights based only on the video recording of the subject. The gains in SNR of camera-based PPG estimated using distancePPG translate into reduction of the error in vital sign estimation, and thus expand the scope of camera-based vital sign monitoring to potentially challenging scenarios. Further, a dataset will be released, comprising of synchronized video recordings of face and pulse oximeter based ground truth recordings from the earlobe for people with different skin tones, under different lighting conditions and for various motion scenarios. PMID:26137365

Uncertainties in forces extracted from non-contact atomic force microscopy measurements by fitting of long-range background forces

Directory of Open Access Journals (Sweden)

Adam Sweetman

2014-04-01

Full Text Available In principle, non-contact atomic force microscopy (NC-AFM now readily allows for the measurement of forces with sub-nanonewton precision on the atomic scale. In practice, however, the extraction of the often desired ‘short-range’ force from the experimental observable (frequency shift is often far from trivial. In most cases there is a significant contribution to the total tip–sample force due to non-site-specific van der Waals and electrostatic forces. Typically, the contribution from these forces must be removed before the results of the experiment can be successfully interpreted, often by comparison to density functional theory calculations. In this paper we compare the ‘on-minus-off’ method for extracting site-specific forces to a commonly used extrapolation method modelling the long-range forces using a simple power law. By examining the behaviour of the fitting method in the case of two radically different interaction potentials we show that significant uncertainties in the final extracted forces may result from use of the extrapolation method.

Neuromuscular Retraining in Female Adolescent Athletes: Effect on Athletic Performance Indices and Noncontact Anterior Cruciate Ligament Injury Rates

Directory of Open Access Journals (Sweden)

Frank R. Noyes

2015-05-01

Full Text Available While many anterior cruciate ligament (ACL prevention programs have been published, few have achieved significant reductions in injury rates and improvements in athletic performance indices; both of which may increase compliance and motivation of athletes to participate. A supervised neuromuscular retraining program (18 sessions was developed, aimed at achieving both of these objectives. The changes in neuromuscular indices were measured after training in 1000 female athletes aged 13–18 years, and the noncontact ACL injury rate in 700 of these trained athletes was compared with that of 1120 control athletes. There were significant improvements in the drop-jump test, (p < 0.0001, effect size [ES] 0.97, the single-leg triple crossover hop (p < 0.0001, ES 0.47, the t-test (p < 0.0001, ES 0.64, the multi-stage fitness test (p < 0.0001, ES 0.57, hamstring strength (p < 0.0001, and quadriceps strength (p < 0.01. The trained athletes had a significant reduction in the noncontact ACL injury incidence rate compared with the controls (1 ACL injury in 36,724 athlete-exposures [0.03] and 13 ACL injuries in 61,244 exposures [0.21], respectively, p = 0.03. The neuromuscular retraining program was effective in reducing noncontact ACL injury rate and improving athletic performance indicators.

[Comparison of tonometry with the Keeler air puff non-contact tonometer "Pulsair" and the Goldmann applanation tonometer].

Science.gov (United States)

Yücel, A A; Stürmer, J; Gloor, B

1990-10-01

Intraocular pressure (IOP) readings were performed with the Keeler Air-Puff Non-Contact Tonometer "Pulsair" in 126 patients before (NCT1) and after (NCT2) applanation-tonometry with the Goldmann device (GAT). For the whole population of 126 patients, in each of whom only one eye was selected, there was a significant difference of the mean IOP measurement, but the difference between the two measurement methods was only slightly significant when the NCT was applied before the GAT, and highly significant vice versa. Also the variation of the NCT-measurements was significantly larger than that for the GAT, while the before- and after GAT measurements had equal variations. If only the measurements under 18 mmHg mean GAT are taken into account (n = 101), the difference between GAT and NCT1 was not significant (p = 0.437), as opposed to the GAT-measurements above 18 mmHg, where a highly significant difference between the means was found (p = 0.0033). In most cases, the IOP-readings were underestimated using NCT. The Non Contact Tonometer "Pulsair" could be used for IOP-readings in patients with increased risk of infection, as well as in those with known allergic reactions to topical anesthetic agents, with poor or absent fixation ability, with corneal edema, and postoperative after anterior-segment surgery. The possibility of IOP-measurement in a reclined position is a true advantage of the Non-Contact Tonometer presented here. A measuring strategy for the above-mentioned applications is presented.

Characterization of a time-resolved non-contact scanning diffuse optical imaging system exploiting fast-gated single-photon avalanche diode detection

Energy Technology Data Exchange (ETDEWEB)

Di Sieno, Laura, E-mail: laura.disieno@polimi.it; Dalla Mora, Alberto; Contini, Davide [Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Wabnitz, Heidrun; Macdonald, Rainer [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany); Pifferi, Antonio [Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Mazurenka, Mikhail [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany); Hannoversches Zentrum für Optische Technologien, Nienburger Str. 17, 30167 Hannover (Germany); Hoshi, Yoko [Department of Biomedical Optics, Medical Photonics Research Center, Hamamatsu University School of Medicine, Hamamatsu 431-3192 (Japan); Boso, Gianluca; Tosi, Alberto [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Becker, Wolfgang [Becker and Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Martelli, Fabrizio [Dipartimento di Fisica e Astronomia dell’Università degli Studi di Firenze, Via G. Sansone 1, Sesto Fiorentino, Firenze 50019 (Italy)

2016-03-15

We present a system for non-contact time-resolved diffuse reflectance imaging, based on small source-detector distance and high dynamic range measurements utilizing a fast-gated single-photon avalanche diode. The system is suitable for imaging of diffusive media without any contact with the sample and with a spatial resolution of about 1 cm at 1 cm depth. In order to objectively assess its performances, we adopted two standardized protocols developed for time-domain brain imagers. The related tests included the recording of the instrument response function of the setup and the responsivity of its detection system. Moreover, by using liquid turbid phantoms with absorbing inclusions, depth-dependent contrast and contrast-to-noise ratio as well as lateral spatial resolution were measured. To illustrate the potentialities of the novel approach, the characteristics of the non-contact system are discussed and compared to those of a fiber-based brain imager.

Characterization of a time-resolved non-contact scanning diffuse optical imaging system exploiting fast-gated single-photon avalanche diode detection

International Nuclear Information System (INIS)

Di Sieno, Laura; Dalla Mora, Alberto; Contini, Davide; Wabnitz, Heidrun; Macdonald, Rainer; Pifferi, Antonio; Mazurenka, Mikhail; Hoshi, Yoko; Boso, Gianluca; Tosi, Alberto; Becker, Wolfgang; Martelli, Fabrizio

2016-01-01

We present a system for non-contact time-resolved diffuse reflectance imaging, based on small source-detector distance and high dynamic range measurements utilizing a fast-gated single-photon avalanche diode. The system is suitable for imaging of diffusive media without any contact with the sample and with a spatial resolution of about 1 cm at 1 cm depth. In order to objectively assess its performances, we adopted two standardized protocols developed for time-domain brain imagers. The related tests included the recording of the instrument response function of the setup and the responsivity of its detection system. Moreover, by using liquid turbid phantoms with absorbing inclusions, depth-dependent contrast and contrast-to-noise ratio as well as lateral spatial resolution were measured. To illustrate the potentialities of the novel approach, the characteristics of the non-contact system are discussed and compared to those of a fiber-based brain imager.

Noncontact Detection and Analysis of Respiratory Function Using Microwave Doppler Radar

Directory of Open Access Journals (Sweden)

Yee Siong Lee

2015-01-01

Full Text Available Real-time respiratory measurement with Doppler Radar has an important advantage in the monitoring of certain conditions such as sleep apnoea, sudden infant death syndrome (SIDS, and many other general clinical uses requiring fast nonwearable and non-contact measurement of the respiratory function. In this paper, we demonstrate the feasibility of using Doppler Radar in measuring the basic respiratory frequencies (via fast Fourier transform for four different types of breathing scenarios: normal breathing, rapid breathing, slow inhalation-fast exhalation, and fast inhalation-slow exhalation conducted in a laboratory environment. A high correlation factor was achieved between the Doppler Radar-based measurements and the conventional measurement device, a respiration strap. We also extended this work from basic signal acquisition to extracting detailed features of breathing function (I : E ratio. This facilitated additional insights into breathing activity and is likely to trigger a number of new applications in respiratory medicine.

New test structures and techniques for measurement of mechanical properties of MEMS materials

Science.gov (United States)

Sharpe, William N., Jr.; Yuan, Bin; Vaidyanathan, Ranji; Edwards, Richard L.

1996-09-01

This paper presents techniques and procedures for addressing the three major problems of mechanical testing of the thin films used in surface micromachined microelectromechanical systems--specimen handling, friction, and strain measurement. The polysilicon tensile specimens are fabricated with two supporting side strips on silicon wafers at the Microelectronic Center of North Carolina. The tensile specimen is released by etching away the wafer, and the two support strips are cut after the specimen is glued in the test machine. Friction is reduced by a linear air bearing in the load train, and strain is measured with a noncontacting technique based on laser interferometry between two gold lines on the tensile specimen. The Young's modulus of polysilicon is 170 +/- 7 GPa and the strength is 1.21 +/- 0.16 GPa from a series of 29 tests. preliminary measurements have been made of Poisson's ratio and the fatigue behavior, and an attempt is underway to measure the fracture toughness.

INNOVATIVE NON-CONTACT METROLOGY SOLUTIONS FOR LARGE OPTICAL TELESCOPES, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NASA has unique non-contact precision metrology requirements for dimensionally inspecting the global position and orientation of large and highly-polished...

Effects of gauge volume on pseudo-strain induced in strain measurement using time-of-flight neutron diffraction

International Nuclear Information System (INIS)

Suzuki, Hiroshi; Harjo, Stefanus; Abe, Jun; Xu, Pingguang; Aizawa, Kazuya; Akita, Koichi

2013-01-01

Spurious or pseudo-strains observed in time-of-flight (TOF) neutron diffraction due to neutron attenuation, surface-effects and a strain distribution within the gauge volume were investigated. Experiments were carried out on annealed and bent ferritic steel bars to test these effects. The most representative position in the gauge volume corresponds to the neutron-weighted center of gravity (ncog), which takes into account variations in intensity within the gauge volume due to neutron attenuation and/or absence of material in the gauge volume. The average strain in the gauge volume was observed to be weighted towards the ncog position but following an increase in the size of the gauge volume the weighted average strain was changed because of the change in the ncog position when a strain gradient appeared within the gauge volume. On the other hand, typical pseudo-strains, which are well known, did appear in through-surface strain measurements when the gauge volume was incompletely filled by the sample. Tensile pseudo-strains due to the surface-effect increased near the sample surface and exhibited a similar trend regardless of the size of the gauge volume, while the pseudo-strains increased faster for the smaller gauge volume. Furthermore, a pseudo-strain due to a change in the ncog position was observed even when the gauge volume was perfectly filled in the sample, and it increased with an increase in the size of the gauge volume. These pseudo-strains measured were much larger than those simulated by the conventional modeling, whereas they were simulated by taking into account an incident neutron beam divergence additionally in the model. Therefore, the incident divergence of the incident neutron beam must be carefully designed to avoid pseudo-strains in time-of-flight neutron diffractometry

Intrinsic risk factors of noncontact ankle sprains in soccer: a prospective study on 100 professional players.

Science.gov (United States)

Fousekis, Konstantinos; Tsepis, Elias; Vagenas, George

2012-08-01

Ankle sprain is an extremely common injury in soccer players. Despite extensive research, the intrinsic cause of this injury under noncontact conditions remains unclear. To identify intrinsic risk factors for noncontact ankle sprains in professional soccer players. Cohort study; Level of evidence, 2 One hundred professional soccer players were assessed in the preseason for potential risk factors of noncontact ankle sprains. The assessment included (A) ankle joint asymmetries (right-left) in isokinetic muscle strength, flexibility, proprioception, and stability; (B) somatometric asymmetries; (C) previous injuries; and (D) lateral dominance traits. Noncontact ankle sprains were prospectively recorded and diagnosed for a full competition period (10 months). Seventeen of the players sustained at least 1 noncontact ankle sprain. Logistic regression revealed that players with (A) eccentric isokinetic ankle flexion strength asymmetries (odds ratio [OR] = 8.88; 95% confidence interval [CI], 1.95-40.36, P = .005), (B) increased body mass index (OR = 8.16; 95% CI, 1.42-46.63, P = .018), and (C) increased body weight (OR = 5.72; 95% CI, 1.37-23.95, P = .017 ) each had a significantly higher risk of a noncontact ankle sprain. A trend for younger players (OR = 0.28; 95% CI, 0.061-1.24, P = .092) and for players with ankle laxity asymmetries (OR = 3.38; 95% CI, 0.82-14.00, P = .093) to be at greater risk for ankle sprain was also apparent to the limit of statistical significance (.05 ankle flexors and increased body mass index and body weight raise the propensity for ankle sprains in professional soccer players. Age and asymmetries in ankle laxity are potential factors worth revisiting, as there was an indication for younger players and players with ankle instability to be at higher risk for ankle injury. Proper preseason evaluation may improve prevention strategies for this type of injury in soccer.

An imaging colorimeter for noncontact tissue color mapping.

Science.gov (United States)

Balas, C

1997-06-01

There has been a considerable effort in several medical fields, for objective color analysis and characterization of biological tissues. Conventional colorimeters have proved inadequate for this purpose, since they do not provide spatial color information and because the measuring procedure randomly affects the color of the tissue. In this paper an imaging colorimeter is presented, where the nonimaging optical photodetector of colorimeters is replaced with the charge-coupled device (CCD) sensor of a color video camera, enabling the independent capturing of the color information for any spatial point within its field-of-view. Combining imaging and colorimetry methods, the acquired image is calibrated and corrected, under several ambient light conditions, providing noncontact reproducible color measurements and mapping, free of the errors and the limitations present in conventional colorimeters. This system was used for monitoring of blood supply changes of psoriatic plaques, that have undergone Psoralens and ultraviolet-A radiation (PUVA) therapy, where reproducible and reliable measurements were demonstrated. These features highlight the potential of the imaging colorimeters as clinical and research tools for the standardization of clinical diagnosis and for the objective evaluation of treatment effectiveness.

Noncontact thermometry via laser pumped, thermographic phosphors: Characterization of systematic errors and industrial applications

International Nuclear Information System (INIS)

Gillies, G.T.; Dowell, L.J.; Lutz, W.N.; Allison, S.W.; Cates, M.R.; Noel, B.W.; Franks, L.A.; Borella, H.M.

1987-10-01

There are a growing number of industrial measurement situations that call for a high precision, noncontact method of thermometry. Our collaboration has been successful in developing one such method based on the laser-induced fluorescence of rare-earth-doped ceramic phosphors like Y 2 O 3 :Eu. In this paper, we summarize the results of characterization studies aimed at identifying the sources of systematic error in a laboratory-grade version of the method. We then go on to present data from measurements made in the afterburner plume of a jet turbine and inside an operating permanent magnet motor. 12 refs., 6 figs

Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes.

Science.gov (United States)

Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi

2017-05-23

This work describes the measurement procedure and principles of a sampling moiré technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moiré method or the spatial phase-shifting sampling moiré method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moiré fringes are generated to reconstruct a multiplication moiré pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moiré method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moiré fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moiré techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

Measurement of the uniaxial mechanical properties of rat skin using different stress-strain definitions.

Science.gov (United States)

Karimi, A; Navidbakhsh, M

2015-05-01

The mechanical properties of skin tissue may vary according to the anatomical locations of a body. There are different stress-strain definitions to measure the mechanical properties of skin tissue. However, there is no agreement as to which stress-strain definition should be implemented to measure the mechanical properties of skin at different anatomical locations. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are employed to determine the mechanical properties of skin tissue at back and abdomen locations of a rat body. The back and abdomen skins of eight rats are excised and subjected to a series of tensile tests. The elastic modulus, maximum stress, and strain of skin tissues are measured using three stress definitions and four strain definitions. The results show that the effect of varying the stress definition on the maximum stress measurements of the back skin is significant but not when calculating the elastic modulus and maximum strain. No significant effects are observed on the elastic modulus, maximum stress, and strain measurements of abdomen skin by varying the stress definition. In the true stress-strain diagram, the maximum stress (20%), and elastic modulus (35%) of back skin are significantly higher than that of abdomen skin. The true stress-strain definition is favored to measure the mechanical properties of skin tissue since it gives more accurate measurements of the skin's response using the instantaneous values. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Development of a quick and easy-to-install strain measurement tool for piping stress evaluation

International Nuclear Information System (INIS)

Takahama, Tsunemichi; Nishimura, Kazuma; Ninomiya, Seiichiro; Matsumoto, Yoshihiro; Harada, Yutaka

2015-01-01

To avoid failures of small bore piping connections caused by high cycle fatigue, it is important to measure the stresses around the connections. To measure such stresses, the authors have developed an easily-attachable and detachable strain measurement tool which utilizes strain gauges in combination with our patented strain gauge holder. Traditionally, strain gauges have been bonded to piping surfaces using adhesive; however, with the newly-developed measurement tool, bonding adhesive is no longer necessary. The tool can be installed quickly and easily on a piping surface and measure the strains on the piping as accurately as adhesively-bonded strain gauges. Accordingly, the new strain measurement tool significantly reduces the work time without affecting the measurement accuracy. (author)

Hybrid MEFPI/FBG sensor for simultaneous measurement of strain and magnetic field

Science.gov (United States)

Chen, Mao-qing; Zhao, Yong; Lv, Ri-qing; Xia, Feng

2017-12-01

A hybrid fiber-optic sensor consisting of a micro extrinsic Fabry-Perot Interferometer (MEFPI) and an etched fiber Bragg grating (FBG) is proposed, which can measure strain and magnetic field simultaneously. The etched FBG is sealed in a capillary with ferrofluids to detect the surrounding magnetic field. FBG with small diameter will be more sensitive to magnetic field is confirmed by simulation results. The MEFPI sensor that is prepared through welding a short section of hollow-core fiber (HCF) with single-mode fiber (SMF) is effective for strain detection. The experiment shows that strain and magnetic field can be successfully simultaneously detected based on hybrid MEFPI/FBG sensor. The sensitivities of the strain and magnetic field intensity are measured to be up to 1.41 pm/με and 5.11 pm/mT respectively. There is a negligible effect on each other, hence simultaneously measuring strain and magnetic field is feasible. It is anticipated that such easy preparation, compact and low-cost fiber-optic sensors for simultaneous measurement of strain and magnetic field could find important applications in practice.

Speckle-based off-axis holographic detection for non-contact photoacoustic tomography

Directory of Open Access Journals (Sweden)

Buj C.

2015-09-01

Full Text Available A very fast innovative holographic off-axis non-contact detection method for Photoacoustic Tomography (PAT is introduced. It overcomes the main problems of most state-of-the-art photoacoustic imaging approaches that are long acquisition times and the requirement of acoustic contact. In order to increase the acquisition speed significantly, the surface displacements of the object, caused by the photoacoustic pressure waves, are measured interferometrically in two dimensions. Phase alterations in the observed speckle field are used to identify changes in the object’s topography. A sampling rate of up to 80 MHz is feasible, which reduces the occurrence of motion artefacts.

A non-contact time-domain scanning brain imaging system: first in-vivo results

Science.gov (United States)

Mazurenka, M.; Di Sieno, L.; Boso, G.; Contini, D.; Pifferi, A.; Dalla Mora, A.; Tosi, A.; Wabnitz, H.; Macdonald, R.

2013-06-01

We present results of first in-vivo tests of an optical non-contact scanning imaging system, intended to study oxidative metabolism related processes in biological tissue by means of time-resolved near-infrared spectroscopy. Our method is a novel realization of the short source-detector separation approach and based on a fast-gated single-photon avalanche diode to detect late photons only. The scanning system is built in quasi-confocal configuration and utilizes polarizationsensitive detection. It scans an area of 4×4 cm2, recording images with 32×32 pixels, thus creating a high density of source-detector pairs. To test the system we performed a range of in vivo measurements of hemodynamic changes in several types of biological tissues, i.e. skin (Valsalva maneuver), muscle (venous and arterial occlusions) and brain (motor and cognitive tasks). Task-related changes in hemoglobin concentrations were clearly detected in skin and muscle. The brain activation shows weaker, but yet detectable changes. These changes were localized in pixels near the motor cortex area (C3). However, it was found that even very short hair substantially impairs the measurement. Thus the applicability of the scanner is limited to hairless parts of body. The results of our first in-vivo tests prove the feasibility of non-contact scanning imaging as a first step towards development of a prototype for biological tissue imaging for various medical applications.

Polymer film strain gauges for measuring large elongations

Science.gov (United States)

Kondratov, A. P.; Zueva, A. M.; Varakin, R. S.; Taranec, I. P.; Savenkova, I. A.

2018-02-01

The paper shows the possibility to print polymer strain gages, microstrip lines, coplanar waveguides, and other prints for avionics using printing technology and equipment. The methods of screen and inkjet printing have been complemented by three new operations of preparing print films for application of an electrically conductive ink layer. Such additional operations make it possible to enhance the conductive ink layer adhesion to the film and to manufacture strain gages for measuring large elongations.

Acanthamoeba keratitis in a non-contact lens wearer with human immunodeficiency virus

DEFF Research Database (Denmark)

Hansen, Birgitte Rønde; Kronborg, Gitte

2003-01-01

Acanthamoeba keratitis is potentially blinding and often associated with contact lens wearing. A human immunodeficiency virus (HIV)-positive patient, a non-contact lens wearer, presented with keratitis. She experienced a protracted course of disease, characterized by exacerbations and remissions......, and was treated with various topical antibiotics and steroids. 13 months after symptom onset the eye was removed owing to serious scarring of cornea and unbearable pain. Microbiological and histopathological examination of the cornea showed Acanthamoeba. In non-contact lens wearers suffering from Acanthamoeba...... keratitis the diagnosis is delayed, pathognomonic features are often not seen and visual outcome is usually poor. There is no known relation between HIV infection and Acanthamoeba keratitis....

Thermal image analysis of plastic deformation and fracture behavior by a thermo-video measurement system

International Nuclear Information System (INIS)

Ohbuchi, Yoshifumi; Sakamoto, Hidetoshi; Nagatomo, Nobuaki

2016-01-01

The visualization of the plastic region and the measurement of its size are necessary and indispensable to evaluate the deformation and fracture behavior of a material. In order to evaluate the plastic deformation and fracture behavior in a structural member with some flaws, the authors paid attention to the surface temperature which is generated by plastic strain energy. The visualization of the plastic deformation was developed by analyzing the relationship between the extension of the plastic deformation range and the surface temperature distribution, which was obtained by an infrared thermo-video system. Furthermore, FEM elasto-plastic analysis was carried out with the experiment, and the effectiveness of this non-contact measurement system of the plastic deformation and fracture process by a thermography system was discussed. The evaluation method using an infrared imaging device proposed in this research has a feature which does not exist in the current evaluation method, i.e. the heat distribution on the surface of the material has been measured widely by noncontact at 2D at high speed. The new measuring technique proposed here can measure the macroscopic plastic deformation distribution on the material surface widely and precisely as a 2D image, and at high speed, by calculation from the heat generation and the heat propagation distribution. (paper)

Improved protein structure reconstruction using secondary structures, contacts at higher distance thresholds, and non-contacts.

Science.gov (United States)

Adhikari, Badri; Cheng, Jianlin

2017-08-29

Residue-residue contacts are key features for accurate de novo protein structure prediction. For the optimal utilization of these predicted contacts in folding proteins accurately, it is important to study the challenges of reconstructing protein structures using true contacts. Because contact-guided protein modeling approach is valuable for predicting the folds of proteins that do not have structural templates, it is necessary for reconstruction studies to focus on hard-to-predict protein structures. Using a data set consisting of 496 structural domains released in recent CASP experiments and a dataset of 150 representative protein structures, in this work, we discuss three techniques to improve the reconstruction accuracy using true contacts - adding secondary structures, increasing contact distance thresholds, and adding non-contacts. We find that reconstruction using secondary structures and contacts can deliver accuracy higher than using full contact maps. Similarly, we demonstrate that non-contacts can improve reconstruction accuracy not only when the used non-contacts are true but also when they are predicted. On the dataset consisting of 150 proteins, we find that by simply using low ranked predicted contacts as non-contacts and adding them as additional restraints, can increase the reconstruction accuracy by 5% when the reconstructed models are evaluated using TM-score. Our findings suggest that secondary structures are invaluable companions of contacts for accurate reconstruction. Confirming some earlier findings, we also find that larger distance thresholds are useful for folding many protein structures which cannot be folded using the standard definition of contacts. Our findings also suggest that for more accurate reconstruction using predicted contacts it is useful to predict contacts at higher distance thresholds (beyond 8 Å) and predict non-contacts.

Dynamic strain measurement of hydraulic system pipeline using fibre Bragg grating sensors

Directory of Open Access Journals (Sweden)

Qiang Wang

2016-04-01

Full Text Available Fatigue failure is a serious problem in hydraulic piping systems installed in the machinery and equipment working in harsh operational conditions. To alleviate this problem, health monitoring of pipes can be conducted by measuring and analysing vibration-induced strain. Fibre Bragg grating is considered as a promising sensing approach for dynamic load monitoring. In this article, dynamic strain measurements based on fibre Bragg grating sensors for small-bore metal pipes have been investigated. The quasi-distributed strain sensing of fibre Bragg grating sensors is introduced. Two comparison experiments were carried out under vibration and impact loads among the methods of electrical strain gauge, piezoelectric accelerometer and fibre Bragg grating sensor. Experimental results indicate that fibre Bragg grating sensor possesses an outstanding ability to resist electromagnetic interference compared with strain gauge. The natural frequency measurement results, captured by fibre Bragg grating sensor, agree well with the modal analysis results obtained from finite element analysis. In addition, the attached fibre Bragg grating sensor brings a smaller impact on the dynamic characteristics of the measured pipe than the accelerometer due to its small size and lightweight. Fibre Bragg grating sensors have great potential for the quasi-distributed measurement of dynamic strain for the dynamic characteristic research and health monitoring of hydraulic system pipeline.

Measurement of strains by means of electro-optics holography

Science.gov (United States)

Sciammarella, Cesar A.; Bhat, Gopalakrishna K.; Albertazzi, Armando, Jr.

1991-03-01

The use of a TV camera as a recording medium and the observation of whole field displacements in real time makes holographic TV a very interesting and powerful tool in a variety of areas from NDE to research and development. The paper presents new developments in the field that add to the versatility of the technique by introducing portability and methods to obtain accurate quantitative results. Examples of applications are given to the measurement of strains both at room and at high temperatures and strain measurements at the microscopic level. 1.

Technique for measurements of plane waves of uniaxial strain

International Nuclear Information System (INIS)

Graham, R.A.

1977-01-01

The measurement of plane waves in uniaxial strain, in which large surface areas are loaded and the measurements are restricted to a central region that is not influenced by lateral boundaries, is discussed. Measuring techniques are covered and instruments are discussed

Non-contact radio frequency shielding and wave guiding by multi-folded transformation optics method.

Science.gov (United States)

Madni, Hamza Ahmad; Zheng, Bin; Yang, Yihao; Wang, Huaping; Zhang, Xianmin; Yin, Wenyan; Li, Erping; Chen, Hongsheng

2016-11-14

Compared with conventional radio frequency (RF) shielding methods in which the conductive coating material encloses the circuits design and the leakage problem occurs due to the gap in such conductive material, non-contact RF shielding at a distance is very promising but still impossible to achieve so far. In this paper, a multi-folded transformation optics method is proposed to design a non-contact device for RF shielding. This "open-shielded" device can shield any object at a distance from the electromagnetic waves at the operating frequency, while the object is still physically open to the outer space. Based on this, an open-carpet cloak is proposed and the functionality of the open-carpet cloak is demonstrated. Furthermore, we investigate a scheme of non-contact wave guiding to remotely control the propagation of surface waves over any obstacles. The flexibilities of such multi-folded transformation optics method demonstrate the powerfulness of the method in the design of novel remote devices with impressive new functionalities.

Assessment of the reliability of human corneal endothelial cell-density estimates using a noncontact specular microscope.

Science.gov (United States)

Doughty, M J; Müller, A; Zaman, M L

2000-03-01

We sought to determine the variance in endothelial cell density (ECD) estimates for human corneal endothelia. Noncontact specular micrographs were obtained from white subjects without any history of contact lens wear, or major eye disease or surgery; subjects were within four age groups (children, young adults, older adults, senior citizens). The endothelial image was scanned, and the areas from > or =75 cells measured from an overlay by planimetry. The cell-area values were used to calculate the ECD repeatedly so that the intra- and intersubject variation in an average ECD estimate could be made by using different numbers of cells (5, 10, 15, etc.). An average ECD of 3,519 cells/mm2 (range, 2,598-5,312 cells/mm2) was obtained of counts of 75 cells/ endothelium from individuals aged 6-83 years. Average ECD estimates in each age group were 4,124, 3,457, 3,360, and 3,113 cells/mm2, respectively. Analysis of intersubject variance revealed that ECD estimates would be expected to be no better than +/-10% if only 25 cells were measured per endothelium, but approach +/-2% if 75 cells are measured. In assessing the corneal endothelium by noncontact specular microscopy, cell count should be given, and this should be > or =75/ endothelium for an expected variance to be at a level close to that recommended for monitoring age-, stress-, or surgery-related changes.

Measurement of intraocular pressure with pressure phosphene tonometry in children.

Science.gov (United States)

Fan, Dorothy S P; Chiu, Thomas Y H; Congdon, Nathan; Chan, Jeffrey C W; Cheung, Eva Y Y; Lam, Dennis S C

2011-01-01

To study the accuracy and acceptability of intraocular pressure (IOP) measurement by the pressure phosphene tonometer, non-contact tonometer, and Goldmann tonometer in children. Fifty children (5 to 14 years old) participated in this prospective comparative study. IOP was measured with the pressure phosphene tonometer, non-contact tonometer, and Goldmann tonometer by three different examiners who were masked to the results. The children were also asked to grade the degree of discomfort from 0 to 5 (0 = no discomfort; 5 = most discomfort). The mean IOPs measured by the Goldmann tonometer, pressure phosphene tonometer, and non-contact tonometer were 15.9 mm Hg (standard deviation [SD]: = 5.5 mm Hg; range: 10 to 36 mm Hg), 16.0 mm Hg (SD: 2.9 mm Hg; range: 12 to 25 mm Hg), and 15.7 mm Hg (SD = 5.1 mm Hg; range: 8 to 32 mm Hg), respectively (P = .722). The mean difference between pressure phosphene tonometer and Goldmann tonometer readings was 2.9 mm Hg and that between non-contact tonometer and Goldmann tonometer readings was 2.1 mm Hg. The 95% confidence interval of the mean difference between pressure phosphene tonometer and Goldmann tonometer readings was -1.07 and 1.19, and that between non-contact tonometer and Goldmann tonometer readings was -1.07 and 0.53. The mean discomfort ratings for the pressure phosphene tonometer, non-contact tonometer, and Goldmann tonometer were 0.6, 2.0, and 2.3, respectively (P tonometer was less accurate than the non-contact tonometer compared with Goldmann tonometer, it gave a reasonably close estimate and had a high specificity of raised IOP. In addition, measurement by the pressure phosphene tonometer is most acceptable to children. The pressure phosphene tonometer can be considered as an alternative method of IOP measurement in children. Copyright 2011, SLACK Incorporated.

Noncontacting Measurement With a Thermocouple

Science.gov (United States)

Weatherill, W. T.; Schoreder, C. J.; Freitag, H. J.

1986-01-01

Tentlike covering brings thermocouple to within few degrees of surface temperature. Technique originally developed for measuring surface temperature of quartz fabric under radiant heating requires no direct contact with heated surface. Technique particularly useful when measuring surface temperatures of materials damaged if thermocouple or other temperature sensor attached.

Stress strain tensors with their application to x-ray stress measurement

International Nuclear Information System (INIS)

Kurita, Masanori

2015-01-01

This paper describes in detail the method of obtaining the formulas of stress-strain tensor that express the directional dependence of stress-strain, that is, how these values change in response to coordinate transformation, and clarifies the preconditions for supporting both formulas. The two conversion formulas are both the second order of tensor, and the formula of strain tensor not only does not use the relational expression of stress and strain at all, but also is obtained completely independently of the formula of stress tensor. Except for the condition that the strain is very small (elastic deformation) in the conversion formula of strain, both formulas unconditionally come into effect. In other words, both formulas hold true even in the isotropic elastic body or anisotropic elastic body. It was shown that the conversion formula of strain can be derived from the conversion formula of stress using the formula of Hooke for isotropic elastic body. From these three-dimensional expressions, the two-dimensional stress-strain coordinate conversion formula that is used for Mohr's stress-strain circle was derived. It was shown that these formulas hold true for three-dimensional stress condition with stress-strain components in the three-axial direction that are not plane stress nor plane strain condition. In addition, as an application case of this theory, two-dimensional and three-dimensional X-ray stress measurements that are effective for residual stress measurement were shown. (A.O.)

Design of novel non-contact multimedia controller for disability by using visual stimulus.

Science.gov (United States)

Pan, Jeng-Shyang; Lo, Chi-Chun; Tsai, Shang-Ho; Lin, Bor-Shyh

2015-12-01

The design of a novel non-contact multimedia controller is proposed in this study. Nowadays, multimedia controllers are generally used by patients and nursing assistants in the hospital. Conventional multimedia controllers usually involve in manual operation or other physical movements. However, it is more difficult for the disabled patients to operate the conventional multimedia controller by themselves; they might totally depend on others. Different from other multimedia controllers, the proposed system provides a novel concept of controlling multimedia via visual stimuli, without manual operation. The disabled patients can easily operate the proposed multimedia system by focusing on the control icons of a visual stimulus device, where a commercial tablet is used as the visual stimulus device. Moreover, a wearable and wireless electroencephalogram (EEG) acquisition device is also designed and implemented to easily monitor the user's EEG signals in daily life. Finally, the proposed system has been validated. The experimental result shows that the proposed system can effectively measure and extract the EEG feature related to visual stimuli, and its information transfer rate is also good. Therefore, the proposed non-contact multimedia controller exactly provides a good prototype of novel multimedia controlling scheme. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Non-contact tonometry in the postoperative eye.

OpenAIRE

Vernon, S A

1989-01-01

The Keeler Pulsair non-contact tonometer was compared with the Goldmann applanation tonometer in a series of 48 eyes after operation. A correlation coefficient of 0.92 (p less than 0.001) was found between the two instruments, with the Pulsair having a statistically significant tendency to overread the Goldmann slightly in this situation. The Pulsair was, however, shown to be effective in the identification of postoperative ocular hypertension with a high degree of sensitivity and specificity...

Biomechanical responses of healthy and keratoconic corneas measured using a noncontact scheimpflug-based tonometer.

Science.gov (United States)

Ali, Noor Q; Patel, Dipika V; McGhee, Charles N J

2014-05-15

To examine the repeatability of measurements obtained using a noncontact Scheimpflug-based tonometer (Corvis ST) and investigate potential differences in these parameters between healthy and keratoconic (KC) corneas. Forty-five keratoconic eyes and 103 healthy eyes were examined using biomicroscopy, corneal tomography and the Corvis ST (CST). Intraocular pressure and central corneal thickness (CCT) were highly repeatable (intraclass correlation [ICC] > 0.70, coefficient of variation [CV] 0.60, CV < 0.20). There was no association between DA and age, sex, or ethnicity in healthy eyes. There was a greater mean DA in the KC group compared with 46 age-matched healthy eyes (KC 1.37 ± 0.21 mm, healthy 1.05 ± 0.11 mm, P < 0.001). Multivariate analysis showed DA in KC was predicted by IOP, CCT, and the steepest simulated keratometry value (P = 0.03, P = 0.03, P = 0.001 respectively, R(2) = 0.75). A subgroup analysis of healthy and KC eyes with comparable mean CCT and IOP highlighted a statistically significant difference in mean DA (KC 1.25 ± 0.08 mm, thin healthy 1.13 ± 0.09 mm, P = 0.006). Receiver-operating characteristic analysis showed an area under the curve of 0.77 (95% CI 0.61-0.93, P = 0.006) but no ideal cutoff value for DA. Key parameters assessed by the CST are repeatable. Keratoconus is associated with greater DA than in healthy eyes, even when controlled for CCT and IOP. Deformation amplitude may be a useful adjunct in keratoconus assessment and monitoring, but cannot solely discriminate between healthy and keratoconic corneas. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Local, atomic-level elastic strain measurements of metallic glass thin films by electron diffraction

Energy Technology Data Exchange (ETDEWEB)

Ebner, C. [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Sarkar, R. [Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Rajagopalan, J. [Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Department of Mechanical and Aerospace Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe 85287 (United States); Rentenberger, C., E-mail: christian.rentenberger@univie.ac.at [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria)

2016-06-15

A novel technique is used to measure the atomic-level elastic strain tensor of amorphous materials by tracking geometric changes of the first diffuse ring of selected area electron diffraction patterns (SAD). An automatic procedure, which includes locating the centre and fitting an ellipse to the diffuse ring with sub-pixel precision is developed for extracting the 2-dimensional strain tensor from the SAD patterns. Using this technique, atomic-level principal strains from micrometre-sized regions of freestanding amorphous Ti{sub 0.45}Al{sub 0.55} thin films were measured during in-situ TEM tensile deformation. The thin films were deformed using MEMS based testing stages that allow simultaneous measurement of the macroscopic stress and strain. The calculated atomic-level principal strains show a linear dependence on the applied stress, and good correspondence with the measured macroscopic strains. The calculated Poisson’s ratio of 0.23 is reasonable for brittle metallic glasses. The technique yields a strain accuracy of about 1×10{sup −4} and shows the potential to obtain localized strain profiles/maps of amorphous thin film samples. - Highlights: • A TEM method to measure elastic strain in metallic glass films is proposed. • Method is based on tracking geometric changes in TEM diffraction patterns. • An automatic procedure is developed for extracting the local strain tensor. • Atomic-level strain in amorphous TiAl film was analysed during in-situ deformation. • Capability of the method to obtain micrometer scale strain profiles/maps is shown.

Analytical stiffness matrices with Green-Lagrange strain measure

DEFF Research Database (Denmark)

Pedersen, Pauli

2005-01-01

Separating the dependence on material and stress/strain state from the dependence on initial geometry, we obtain analytical secant and tangent stiffness matrices. For the case of a linear displacement triangle with uniform thickness and uniform constitutive behaviour closed-form results are listed...... a solution based on Green-Lagrange strain measure. The approach is especially useful in design optimization, because analytical sensitivity analysis then can be performed. The case of a three node triangular ring element for axisymmetric analysis involves small modifications and extension to four node...

Measurement of in-plane strain with dual beam spatial phase-shift digital shearography

International Nuclear Information System (INIS)

Xie, Xin; Chen, Xu; Li, Junrui; Yang, Lianxiang; Wang, Yonghong

2015-01-01

Full-field in-plane strain measurement under dynamic loading by digital shearography remains a big challenge in practice. A phase measurement for in-plane strain information within one time frame has to be achieved to solve this problem. This paper presents a dual beam spatial phase-shift digital shearography system with the capacity to measure phase distribution corresponding to in-plane strain information within a single time frame. Two laser beams with different wavelengths are symmetrically arranged to illuminate the object under test, and two cameras with corresponding filters, which enable simultaneous recording of two shearograms, are utilized for data acquisition. The phase information from the recorded shearograms, which corresponds to the in-plane strain, is evaluated by the spatial phase-shift method. The spatial phase-shift shearography system realizes a measurement of the in-plane strain through the introduction of the spatial phase-shift technique, using one frame after the loading and one frame before loading. This paper presents the theory of the spatial phase-shift digital shearography for in-plane strain measurement and its derivation, experimental results, and the technique’s potential. (paper)

Application of a fiber optic grating strain sensor for the measurement of strain under irradiation environment

International Nuclear Information System (INIS)

Kaji, Yoshiyuki; Matsui, Yoshinori; Kita, Satoshi; Ide, Hiroshi; Tsukada, Takashi; Tsuji, Hirokazu

2002-01-01

In the Japan Atomic Energy Research Institute (JAERI), in-pile strain measurement techniques have been developed using the Japan Materials Testing Reactor (JMTR). In order to evaluate the performance of fiber optic grating sensors under irradiation environment, heat-up and performance tests at elevated temperatures before irradiation and in-pile tests were performed in JMTR. It was determined that it is possible to measure strain under irradiation environment below 1x10 23 n m -2 (E>1 MeV) by a fiber optic grating sensor, because in-pile temperature characteristics were in good agreement with out-of-pile test results

Air-coupled acoustic radiation force for non-contact generation of broadband mechanical waves in soft media

Energy Technology Data Exchange (ETDEWEB)

Ambroziński, Łukasz [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); AGH University of Science and Technology, Krakow 30059 (Poland); Pelivanov, Ivan, E-mail: ivanp3@uw.edu [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Faculty of Physics, Moscow State University, Moscow 119991 (Russian Federation); Song, Shaozhen; Yoon, Soon Joon; Gao, Liang; O' Donnell, Matthew [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Li, David [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Department of Chemical Engineering, University of Washington Seattle, Washington 98195 (United States); Shen, Tueng T.; Wang, Ruikang K. [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Department of Ophthalmology, University of Washington, Seattle, Washington 98104 (United States)

2016-07-25

A non-contact method for efficient, non-invasive excitation of mechanical waves in soft media is proposed, in which we focus an ultrasound (US) signal through air onto the surface of a medium under study. The US wave reflected from the air/medium interface provides radiation force to the medium surface that launches a transient mechanical wave in the transverse (lateral) direction. The type of mechanical wave is determined by boundary conditions. To prove this concept, a home-made 1 MHz piezo-ceramic transducer with a matching layer to air sends a chirped US signal centered at 1 MHz to a 1.6 mm thick gelatin phantom mimicking soft biological tissue. A phase-sensitive (PhS)-optical coherence tomography system is used to track/image the mechanical wave. The reconstructed transient displacement of the mechanical wave in space and time demonstrates highly efficient generation, thus offering great promise for non-contact, non-invasive characterization of soft media, in general, and for elasticity measurements in delicate soft tissues and organs in bio-medicine, in particular.

Imaging contrast and tip-sample interaction of non-contact amplitude modulation atomic force microscopy with Q -control

International Nuclear Information System (INIS)

Shi, Shuai; Guo, Dan; Luo, Jianbin

2017-01-01

Active quality factor ( Q ) exhibits many promising properties in dynamic atomic force microscopy. Energy dissipation and image contrasts are investigated in the non-contact amplitude modulation atomic force microscopy (AM-AFM) with an active Q -control circuit in the ambient air environment. Dissipated power and virial were calculated to compare the highly nonlinear interaction of tip-sample and image contrasts with different Q gain values. Greater free amplitudes and lower effective Q values show better contrasts for the same setpoint ratio. Active quality factor also can be employed to change tip-sample interaction force in non-contact regime. It is meaningful that non-destructive and better contrast images can be realized in non-contact AM-AFM by applying an active Q -control to the dynamic system. (paper)

Comparison of a new non-contact tonometer with Goldmann applanation.

Science.gov (United States)

Moseley, M J; Evans, N M; Fielder, A R

1989-01-01

A comparison of a new non-contact tonometer (Keeler Pulsair: Keeler UK Ltd) with the Goldmann applanation tonometer is reported. Measurements of intraocular pressure were obtained from 182 eyes of 94 patients. At low pressures (less than 10 mmHg) the candidate tonometer tended to overestimate pressures obtained with the Goldmann tonometer whilst at high pressures (greater than 19 mmHg) those obtained by Goldmann applanation were underestimated. Between 10 and 19 mmHg there was no significant difference between readings obtained with either method. Up to 71% of averaged Pulsair measurements fell within +/- 3 mmHg of those obtained with the Goldmann tonometer increasing to 78% if pressures greater than or equal to 30 mmHg obtained with the Pulsair tonometer were excluded. Adopting a screening criterion of greater than or equal to 21 mmHg (Goldmann) resulted in a sensitivity of 85% and a specificity of 95%. Some evidence that serial Pulsair readings are influenced by the ocular pulse is presented. It is concluded that the Pulsair tonometer can provide clinically useful measurements of intraocular pressure.

Comparison of intraocular pressure as measured by three different non-contact tonometers and goldmann applanation tonometer for non-glaucomatous subjects.

Science.gov (United States)

Bang, Seung Pil; Lee, Chong Eun; Kim, Yu Cheol

2017-11-02

To compare the measurement of intraocular pressure (IOP) among the three different non-contact tonometers (NCT) and the Goldmann applanation tonometer (GAT) for non-glaucomatous subjects. In 52 eyes of 52 non-glaucomatous subjects, IOP was measured sequentially with the Canon TX-20P, the Nidek NT-530P, the Topcon CT-1P, and the GAT at the same time. We evaluated the IOP-measurement agreement among the tonometers as well as the factors affecting the measurements. A significant positive correlation was shown between the IOP values obtained with GAT and each NCT. The Canon TX-20P showed statistically the most significant agreement with the GAT (ICC 0.906, 95% CI 0.837-0.946). In an analysis of the Bland-Altman plots, the Canon TX-20P also showed the largest mean bias (1.38 mmHg) but the narrowest limits of agreement (LoA) (95% LoA; ± 3.43 mmHg). The Topcon CT-1P showed the smallest mean bias (0.48 mmHg) but the widest LoA (95% LoA; ± 4.16 mmHg). The Topcon CT-1P and Nidek NT-530P both showed a significantly positive correlation between increasing central corneal thickness (CCT) and increasing IOP. There was a statistically significant correlation between each of the three different NCT and the GAT measurements. IOP measured with the Canon TX-20P and Topcon CT-1P tended to be higher, and with the Nidek NT-530P lower, than with the GAT. Practitioners need to know the properties of their own NCTs and their respective measurement tendencies.

Photonic Crystal Fiber Sensors for Strain and Temperature Measurement

Directory of Open Access Journals (Sweden)

Jian Ju

2009-01-01

Full Text Available This paper discusses the applications of photonic crystal fibers (PCFs for strain and temperature measurement. Long-period grating sensors and in-fiber modal interferometric sensors are described and compared with their conventional single-mode counterparts. The strain sensitivities of the air-silica PCF sensors are comparable or higher than those implemented in conventional single-mode fibers but the temperature sensitivities of the PCF sensors are much lower.

Modeling of stress-strain diagram on the basis of magnetic measurements

International Nuclear Information System (INIS)

Gorkunov, Eh.S.; Fedotov, V.P.; Bukhvalov, A.B.; Veselov, I.N.

1997-01-01

The model of a stress-strain diagram with taking into account the strain hardening and the growth of metal damageing is proposed. The model is applied to calculate a stress-strain curve for continuous cast 45 steel using the results of magnetic properties measuring. The latter permits predicting the durability of construction elements with the use of nondestructive magnetic testing

Intraocular pressure measurement in patients with previous LASIK surgery using pressure phosphene tonometer.

Science.gov (United States)

Cheng, Arthur C K; Leung, Dexter Y L; Cheung, Eva Y Y; Fan, Dorothy S P; Law, Ricky W K; Lam, Dennis S C

2005-04-01

To compare intraocular pressure (IOP) assessment in post-LASIK patients using non-contact tonometry, pressure phosphene tonometry and applanation tonometry. Sixty-two consecutive LASIK patients were analysed preoperatively and postoperatively with non-contact, pressure phosphene and applanation tonometry. Comparisons among these values were assessed with paired sample Student t-test, Pearson's correlation test and Bland-Altman plotting. There was no significant difference for preoperative IOP measurement between non-contact, pressure phosphene and applanation tonometry. The mean +/-SD difference between the preoperative non-contact tonometry and postoperative pressure phosphene tonometry IOP measurements was 0.80 +/- 2.77 mmHg (P contact tonometry significantly underestimated IOP measurement by 9.96 +/- 2.25 mmHg (P < 0.001). Pressure phosphene tonometry may provide an alternative method for the assessment of IOP in post-LASIK patients.

Measurement of strains at high temperatures by means of electro-optics holography

Science.gov (United States)

Sciammarella, Cesar A.; Bhat, G.; Vaitekunas, Jeffrey

Electro-optics holographic-moire interferometry is used to measure strains at temperatures up to 1000 C. A description of the instrumentation developed to carry out the measurements is given. The data processing technique is also explained. Main problems encountered in recording patterns at high temperatures are analyzed and possible solutions are outlined. Optical results are compared with strain gage values obtained with instrumented specimens and with theoretical results. Very good agreement is found between optical, strain gage and theoretical results.

Comparison of central corneal thickness and endothelial cell measurements by Scheimpflug camera system and two noncontact specular microscopes.

Science.gov (United States)

Karaca, Irmak; Yilmaz, Suzan Guven; Palamar, Melis; Ates, Halil

2017-07-03

To investigate the correlation of Scheimpflug camera system and two noncontact specular microscopes in terms of central corneal thickness (CCT) and corneal endothelial cell morphology measurements. One hundred eyes of 50 healthy subjects were examined by Pentacam Scheimpflug Analyzer, CEM-530 (Nidek Co, Ltd, Gamagori, Japan) and CellChek XL (Konan Medical, California, USA) via fully automated image analysis with no corrections made. Measurement differences and agreement between instruments were determined by intraclass correlation analysis. The mean age of the subjects was 36.74 ± 8.59 (range 22-57). CCTs were well correlated among all devices, with having CEM-530 the thinnest and CellChek XL the thickest measurements (intraclass correlation coefficient (ICC) = 0.83; p < 0.001 and ICC = 0.78; p < 0.001, respectively). Mean endothelial cell density (ECD) given by CEM-530 was lower than CellChek XL (2613.17 ± 228.62 and 2862.72 ± 170.42 cells/mm 2 , respectively; ICC = 0.43; p < 0.001). Mean value for coefficient of variation (CV) was 28.57 ± 3.61 in CEM-530 and 30.30 ± 3.53 in CellChek XL. Cell hexagonality (HEX) with CEM-530 was higher than with CellChek XL (68.70 ± 4.16% and 45.19 ± 6.58%, respectively). ECDs with CellChek XL and CEM-530 have good correlation, but the values obtained by CellChek XL are higher than CEM-530. Measurements for HEX and CV differ significantly and show weak correlation. Thus, we do not recommend interchangeable use of CellChek XL and CEM-530. In terms of CCTs, Pentacam, CEM-530 and CellChek XL specular microscopy instruments are reliable devices.

A novel compliance measurement in radial arteries using strain-gauge plethysmography

International Nuclear Information System (INIS)

Liu, Shing-Hong; Tyan, Chu-Chang; Chang, Kang-Ming

2009-01-01

We propose a novel method for assessing the compliance of the radial artery by using a two-axis mechanism and a standard positioning procedure for detecting the optimal measuring site. A modified sensor was designed to simultaneously measure the arterial diameter change waveform (ADCW) and pressure pulse waveform with a strain gauge and piezoresistor. In the x-axis scanning, the sensor could be placed close to the middle of the radial artery when the ADCW reached the maximum amplitude. In the z-axis scanning, the contact pressure was continuously increased for data measurement. Upon the deformation of the strain gauge following the change in the vascular cross-section, the ADCW was transferred to the change of the vascular radius. The loaded strain compliance of the radial artery (C strain ) can be determined by dividing the dynamic changed radius by the pulse pressure. Twenty-three untreated, mild or moderate hypertensive patients aged 29–85 were compared with 14 normotensive patients aged 25–62. The maximum strain compliance between the two groups was significantly different (p < 0.005). Of the hypertensive patients, 14 were at risk of developing hyperlipidemia. There was a significant difference between this and the normotension group (p < 0.005)

A novel compliance measurement in radial arteries using strain-gauge plethysmography.

Science.gov (United States)

Liu, Shing-Hong; Tyan, Chu-Chang; Chang, Kang-Ming

2009-09-01

We propose a novel method for assessing the compliance of the radial artery by using a two-axis mechanism and a standard positioning procedure for detecting the optimal measuring site. A modified sensor was designed to simultaneously measure the arterial diameter change waveform (ADCW) and pressure pulse waveform with a strain gauge and piezoresistor. In the x-axis scanning, the sensor could be placed close to the middle of the radial artery when the ADCW reached the maximum amplitude. In the Z-axis scanning, the contact pressure was continuously increased for data measurement. Upon the deformation of the strain gauge following the change in the vascular cross-section, the ADCW was transferred to the change of the vascular radius. The loaded strain compliance of the radial artery (C(strain)) can be determined by dividing the dynamic changed radius by the pulse pressure. Twenty-three untreated, mild or moderate hypertensive patients aged 29-85 were compared with 14 normotensive patients aged 25-62. The maximum strain compliance between the two groups was significantly different (p < 0.005). Of the hypertensive patients, 14 were at risk of developing hyperlipidemia. There was a significant difference between this and the normotension group (p < 0.005).

Fabrication and evaluation of hybrid silica/polymer optical fiber sensors for large strain measurement

Science.gov (United States)

Huang, Haiying

2007-04-01

Silica-based optical fiber sensors are widely used in structural health monitoring systems for strain and deflection measurement. One drawback of silica-based optical fiber sensors is their low strain toughness. In general, silica-based optical fiber sensors can only reliably measure strains up to 2%. Recently, polymer optical fiber sensors have been employed to measure large strain and deflection. Due to their high optical losses, the length of the polymer optical fibers is limited to 100 meters. In this paper, we present a novel economical technique to fabricate hybrid silica/polymer optical fiber strain sensors for large strain measurement. First, stress analysis of a surface-mounted optical fiber sensor is performed to understand the load distribution between the host structure and the optical fiber in relation to their mechanical properties. Next, the procedure of fabricating a polymer sensing element between two optical fibers is explained. The experimental set-up and the components used in the fabrication process are described in details. Mechanical testing results of the fabricated silica/polymer optical fiber strain sensor are presented.

[The influence of corneal thickness and curvature on the difference between intraocular pressure measurements obtained with a non-contact tonometer and those with a Goldmann applanation tonometer].

Science.gov (United States)

Matsumoto, T; Makino, H; Uozato, H; Saishin, M; Miyamoto, S

2000-05-01

The influence of corneal thickness and curvature on the difference between intraocular pressure (IOP) measurements obtained with a non-contact tonometer (NCT) and those with a Goldmann applanation tonometer (GAT) was studied. The corneal thickness and curvature were obtained in 230 eyes of 115 subjects. The correlation between them and ratios of measurement with NCT to that with GAT ([NCT/GAT]) were examined. [NCT/GAT] and corneal thickness showed a significant positive correlation (r = 0.556, p < 0.01), but, the correlation between [NCT/GAT] and the radius of corneal curvature was not statistically significant (r = -0.035, p = 0.30). The thick cornea has more influence on the measurement with NCT than GAT, because IOP is measured with NCT over a wider applanation area. The corneas with steeper curvature also cause higher corneal rigidity and produce more overestimation of NCT measurement, while they have stronger capillary attraction of the precorneal tear film for the GAT tip and also produce overestimation of GAT measurement. As a result, [NCT/GAT] was believed to be not influenced by the corneal curvature.

The Influence of Corneal Thickness and Curvature on the Difference Between Intraocular Pressure Measurements Obtained with a Non-contact Tonometer and Those with a Goldmann Applanation Tonometer.

Science.gov (United States)

Matsumoto; Makino; Uozato; Saishin; Miyamoto

2000-11-01

Purpose: The influence of corneal thickness and curvature on the difference between intraocular pressure (IOP) measurements obtained with a non-contact tonometer (NCT) and those with a Goldmann applanation tonometer (GAT) was studied.Methods: The corneal thickness and curvature were obtained in 230 eyes of 115 subjects. The correlation between them and ratios of measurement with NCT to that with GAT ([NCT/GAT]) were examined.Results: [NCT/GAT] and corneal thickness showed a significant positive correlation (r = 0.556, P <.01), but, the correlation between [NCT/GAT] and the radius of corneal curvature was not statistically significant (r = -0.035, P =.30).Conclusion: The thick cornea has more influence on the measurement with NCT than GAT, because IOP is measured with NCT over a wider applanation area. The corneas with steeper curvature also cause higher corneal rigidity and produce more overestimation of NCT measurement, while they have stronger capillary attraction of the precorneal tear film for the GAT tip and also produce overestimation of GAT measurement. As a result, [NCT/GAT] was believed to be not influenced by the corneal curvature.

Application of computer picture processing to dynamic strain measurement under electromagnetic field

International Nuclear Information System (INIS)

Yagawa, G.; Soneda, N.

1987-01-01

For the structural design of fusion reactors, it is very important to ensure the structural integrity of components under various dynamic loading conditions due to a solid-electromagnetic field interaction, an earthquake, MHD effects and so on. As one of the experimental approaches to assess the dynamic fracture, we consider the strain measurement near a crack tip under a transient electromagnetic field, which in general involves several experimental difficulties. The authors have developed a strain measurement method using a picture processing technique. In this method, locations of marks printed on a surface of specimen are determined by the picture processing. The displacement field is interpolated using the mark displacements and finite elements. Finally the strain distribution is calculated by differentiating the displacement field. In the present study, the method is improved and automated apply to the measurement of dynamic strain distribution under an electromagnetic field. Then the effects of dynamic loading on the strain distribution are investigated by comparing the dynamic results with the static ones. (orig./GL)

Passive wireless strain measurement based upon the Villari effect and giant magnetoresistance

Science.gov (United States)

Windl, Roman; Bruckner, Florian; Abert, Claas; Huber, Christian; Vogler, Christoph; Huber, Thomas; Oezelt, Harald; Suess, Dieter

2016-12-01

A passive wireless radio frequency-identification (RFID) stress/strain sensor is presented. Stress is transformed into a change of magnetic field by utilizing an amorphous metal ribbon. This magnetic field change is measured by a giant magnetoresistance magnetic field sensor and converted into a digital value with a RFID chip for wireless access. Standard metal foil strain gauges have a gauge factor GF from around 2 to 5 and suffer from the disadvantage of a physically connected power supply and measurement equipment. For the presented sensor, a strain range of -10 μm/m to 190 μm/m results in a linear sensor response, a gauge factor of GF ≈ 245, and a detectivity of 4.10 nm/m 1/√{Hz } . The detectivity of the presented sensor is similar to the detectivity of a reference metal foil strain gauge. Due to low power consumption and easy signal analysis, this sensor is well suited for long term strain measurement inside closed spaces. RFID adds features like multiple tag detection, wireless passive operation and a user data storage.

Non-contact fluid characterization in containers using ultrasonic waves

Science.gov (United States)

Sinha, Dipen N [Los Alamos, NM

2012-05-15

Apparatus and method for non-contact (stand-off) ultrasonic determination of certain characteristics of fluids in containers or pipes are described. A combination of swept frequency acoustic interferometry (SFAI), wide-bandwidth, air-coupled acoustic transducers, narrowband frequency data acquisition, and data conversion from the frequency domain to the time domain, if required, permits meaningful information to be extracted from such fluids.

Enhanced Strain Measurement Range of an FBG Sensor Embedded in Seven-Wire Steel Strands.

Science.gov (United States)

Kim, Jae-Min; Kim, Chul-Min; Choi, Song-Yi; Lee, Bang Yeon

2017-07-18

FBG sensors offer many advantages, such as a lack of sensitivity to electromagnetic waves, small size, high durability, and high sensitivity. However, their maximum strain measurement range is lower than the yield strain range (about 1.0%) of steel strands when embedded in steel strands. This study proposes a new FBG sensing technique in which an FBG sensor is recoated with polyimide and protected by a polyimide tube in an effort to enhance the maximum strain measurement range of FBG sensors embedded in strands. The validation test results showed that the proposed FBG sensing technique has a maximum strain measurement range of 1.73% on average, which is 1.73 times higher than the yield strain of the strands. It was confirmed that recoating the FBG sensor with polyimide and protecting the FBG sensor using a polyimide tube could effectively enhance the maximum strain measurement range of FBG sensors embedded in strands.

[Effects of central corneal thickness and corneal curvature on measurement of intraocular pressure with Goldmann applanation tonometer and non-contact tonometer].

Science.gov (United States)

Zhang, Yang; Zhao, Jia-liang; Bian, Ai-ling; Liu, Xiao-li; Jin, Yu-mei

2009-08-01

To investigate the effects of central corneal thickness (CCT) and corneal curvature (CC) on intraocular pressure (IOP) measurements by the Goldmann applanation tonometer (GAT) and the non-contact tonometer (NCT). One hundred and twenty patients were recruited from the clinic of Peking Union Medical College Hospital. The CCT was measured by ultrasound pachymetry and the mean radius of CC by using Canon PK-5 refractometer. The IOP of each eye was measured by both GAT and NCT. Linear regression was used to compare the measurements of GAT and NCT; multi regression was used to analyze the relationships between CCT, CC and the measurements of GAT and NCT. Bland-Altman method was used to compare the effect of NCT and GAT on the IOP measurements. The results of the right eyes were reported in this paper. The mean and standard deviation of IOP measured by GAT and NCT was (18.4 + or - 4.0) mm Hg (1 mm Hg = 0.133 kPa) and (17.0 + or - 4.6) mm Hg, respectively, the difference was statistically significant (r = 0.835, P = 0.000). IOP measured using GAT increased by 0.039 mm Hg per microm increase in CCT. IOP measured using NCT increased by 0.064 mm Hg per microm increase in CCT. For an increase of 1 mm of mean corneal curvature there was decrease in IOP of 2.648 mm Hg measured by the GAT and of 3.190 mm Hg measured by the NCT. Compared to the GAT, NCT underestimated at low IOP level and overestimated at higher IOP level. The IOP measurement obtained with both GAT and NCT varied with CCT and CC. CCT affected IOP measurements by NCT more than that by GAT.

Preseason Workload Volume and High-Risk Periods for Noncontact Injury Across Multiple Australian Football League Seasons.

Science.gov (United States)

Colby, Marcus J; Dawson, Brian; Heasman, Jarryd; Rogalski, Brent; Rosenberg, Michael; Lester, Leanne; Peeling, Peter

2017-07-01

Colby, MJ, Dawson, B, Heasman, J, Rogalski, B, Rosenberg, M, Lester, L, and Peeling, P. Preseason workload volume and high-risk periods for noncontact injury across multiple Australian Football League seasons. J Strength Cond Res 31(7): 1821-1829, 2017-The purpose of this study was to assess the association between preseason workloads and noncontact injury risk in Australian football players. Individual player injury data were recorded over 4 full seasons (2012-15) from one professional club. Noncontact injury incidence (per 1,000 "on legs" field training and game hours) was compared across the preseason, precompetition, and in-season phases to determine relative noncontact injury risk. Preseason workloads (global positioning system-derived total distance run and sprint distance) and individual (fixed) injury risk factors (age, previous injury history) were incorporated into the analysis. A generalized estimating equation with a binary logistic function modeled potential risk factors with noncontact injury for selected periods across the annual cycle. Odds ratios were calculated to determine the relative injury risk. The (preseason) precompetition phase (19.1 injuries per 1,000 hours) and (in-season) rounds 12-17 (16.0 injuries per 1,000 hours) resulted in the highest injury incidence. Low cumulative total distances in late preseason (<108 km) and precompetition (76-88 km) periods were associated with significantly (p ≤ 0.05) greater injury risk during the in-season phase. In conclusion, these results suggest players are at the greatest injury risk during the precompetition period, with low preseason cumulative workloads associated with increased in-season injury risk. Therefore, strength and conditioning staff should place particular emphasis on achieving at least moderate training loads during and leading into this phase, where competitive game play is first introduced.

Secondary seal effects in hydrostatic non-contact seals for reactor coolant pump shaft

International Nuclear Information System (INIS)

Fujita, T.; Koga, T.; Tanoue, H.; Hirabayashi, H.

1987-01-01

The paper presents a seal flow analysis in a hydrostatic non-contact seal for a PWR coolant pump shaft. A description is given of the non-contact seal for the reactor coolant pump. Results are presented for a distortion analysis of the seal ring, along with the seal flow characteristics and the contact pressure profiles of the secondary seals. The results of the work confirm previously reported findings that the seal ring distortion is sensitive to the o-ring location (which was placed between the ceramic seal face and the seal ring retainer). The paper concludes that the seal flow characteristics and the tracking performance depend upon the dynamic properties of the secondary seal. (U.K.)

Interpretation of strain measurements on nuclear pressure vessels

International Nuclear Information System (INIS)

Andersen, S.I.; Engbaek, P.

1979-11-01

Selected results from strain measurements on 4 nuclear pressure vessels are presented and discussed. The measurements were made in several different regions of the vessels: transition zones in vessel heads, flanges and bottom parts, nozzels, internal vessel structure and flange bolts. The results presented are based on data obtained by approximately 700 strain-gauges, and a comprehensive knowledge of the quality obtained by such measurements is established. It is shown that a thorough control procedure before and after the test as well as detailed knowledge of the behaviour of the signal from the individual gauges during the test is necessary. If this is omitted, it can be extremely difficult to distinguish between the real structural behaviour and a malfunctioning of a specific gauge installation. In general, most of the measuring results exhibit a very linear behaviour with a negligible zeroshift. However, deviations from linear behaviour are observed in several cases. This nonlinearity can be explained by friction (flange connections) or by gaps (concentrical nozzles) in certain regions, whereas local plastic deformations during the first pressure loadings of the vessel seem to be the reason in other regions. (author)

Reliability Assessment for PSC Box-Girder Bridges Based on SHM Strain Measurements

Directory of Open Access Journals (Sweden)

Chuang Chen

2017-01-01

Full Text Available A reliability assessment method for prestressed concrete (PSC continuous box-girder bridges based on structural health monitoring (SHM strain measurements was proposed. First, due to the fact that measured strain was compositive and the variation periods of its components were different, a series of limit state equations under normal use limit state were given. Then, a linear fitting method was used to determine the relationship between the ambient temperature and the measured strain, which was aimed at extracting the vehicle load effect and the temperature load effect from the measured strain. Finally, according to the equivalent normalization method, the load effects unsatisfying the normal distribution by probability density function fitting were transformed, and the daily failure probabilities of monitored positions were calculated for evaluating the safety state of the girder. The results show that (1 the top plate of the box girder is more sensitive than the bottom plate to the high temperature, (2 the daily and seasonal strain variations induced by uniform temperature reveal an inconsistent tendency to the seasonal variation for mid-span cross sections, and (3 the generalized extreme value distribution is recommended for temperature gradient stress and vehicle induced stress fitting for box-girder bridges.

Stressed and strained state for cermetic-rod-type fuel element

International Nuclear Information System (INIS)

Kulikov, I.S.

1987-01-01

Calculation technique for designing the stress-strained state of a cermetic rod-type fuel element has been proposed. The technique is based on the time-dependent step-by-step method and the solution of the deformation equilibrium equation for continuous and thick-wall long cylinders at every temporal step by the finite difference method. Additional strains, caused by thermal expansion and radiation swelling, have been taken into account. The transion from the non-contact model to the stiff-contact model has been provided in the case of cladding-fuel gap dissappearing in one or a number of cross-sections along the fuel element height. The method is supplemented by the formula for fuel cans stability estimation in the case of high coolant external pressure. The example of estimation of the cermetic-rod-type fuel elements are considered as an example

Measurement test on creep strain rate of uranium-zirconium solid solutions

International Nuclear Information System (INIS)

Ogata, Takanari; Akabori, Mitsuo; Ogawa, Toru

1996-11-01

In order to measure creep strain rate of a small specimen of U-Zr solid solution, authors proposed an estimation method which was based upon the stress relaxation after compression. It was applied to measurement test on creep strain rate of the U-10wt%Zr specimen in the temperature range of 757 to 911degC. It may be concluded that the proposed method is valid, provided that the strain is within the appropriate range and that sufficient amount of the load decrement is observed. The obtained creep rate of U-10wt%Zr alloy indicated significantly smaller value, compared to the experimental data for pure U metal and evaluated data for U-Pu-Zr alloy. However, more careful measurement is desired in future since the present data are thought to be influenced by the precipitations included in the specimen. (author)

X-Ray-Scattering Measurements Of Strain In PEEK

Science.gov (United States)

Cebe, Peggy; Lowry, Lynn E.; Chung, Shirley Y.; Yavrouian, Andre H.; Gupta, Amitava

1988-01-01

Internal stress relieved by heating above glass-transition temperature. Report describes wide-angle x-ray scattering and differential scanning calorimetry of specimens of poly(etheretherketone) having undergone various thermal treatments. Wide-angle x-ray scattering particularly useful in determining distances between atoms, crystallinity, and related microstructurally generated phenomena, as thermal expansion and strain. Calorimetric measurements aid interpretation of scattering measurements by enabling correlation with thermal effects.

Distributed strain measurement in perfluorinated polymer optical fibres using optical frequency domain reflectometry

International Nuclear Information System (INIS)

Liehr, Sascha; Wendt, Mario; Krebber, Katerina

2010-01-01

We present the latest advances in distributed strain measurement in perfluorinated polymer optical fibres (POFs) using backscatter techniques. Compared to previously introduced poly(methyl methacrylate) POFs, the measurement length can be extended to more than 500 m at improved spatial resolution of a few centimetres. It is shown that strain in a perfluorinated POF can be measured up to 100%. In parallel to these investigations, the incoherent optical frequency domain reflectometry (OFDR) technique is introduced to detect strained fibre sections and to measure distributed length change along the fibre with sub-millimetre resolution by applying a cross-correlation algorithm to the backscatter signal. The overall superior performance of the OFDR technique compared to the optical time domain reflectometry in terms of accuracy, dynamic range, spatial resolution and measurement speed is presented. The proposed sensor system is a promising technique for use in structural health monitoring applications where the precise detection of high strain is required

Measuring techniques for autogenous strain of cement paste

DEFF Research Database (Denmark)

Lura, Pietro; Jensen, Ole Mejlhede

2006-01-01

of the volumetric method. Water absorption is driven by a lowering of the water activity in the cement paste due to dissolved salts in the pore fluid and to self-desiccation. From the moment of casting, significant water uptake was registered in all experiments. This water uptake influenced the volumetric...... measurements by the same order of magnitude as the autogenous strain itself. By performing the measurements in a paraffin oil bath instead of a water bath, this artefact was eliminated. Furthermore, volumetric measurements performed in paraffin oil gave almost identical results as linear measurements performed...

Novel method for measuring a dense 3D strain map of robotic flapping wings

Science.gov (United States)

Li, Beiwen; Zhang, Song

2018-04-01

Measuring dense 3D strain maps of the inextensible membranous flapping wings of robots is of vital importance to the field of bio-inspired engineering. Conventional high-speed 3D videography methods typically reconstruct the wing geometries through measuring sparse points with fiducial markers, and thus cannot obtain the full-field mechanics of the wings in detail. In this research, we propose a novel system to measure a dense strain map of inextensible membranous flapping wings by developing a superfast 3D imaging system and a computational framework for strain analysis. Specifically, first we developed a 5000 Hz 3D imaging system based on the digital fringe projection technique using the defocused binary patterns to precisely measure the dynamic 3D geometries of rapidly flapping wings. Then, we developed a geometry-based algorithm to perform point tracking on the precisely measured 3D surface data. Finally, we developed a dense strain computational method using the Kirchhoff-Love shell theory. Experiments demonstrate that our method can effectively perform point tracking and measure a highly dense strain map of the wings without many fiducial markers.

Comparison of the Keeler Pulsair 2000 non-contact tonometer with Goldmann applanation.

Science.gov (United States)

Moseley, M J; Thompson, J R; Deutsch, J; Misson, G P; Naylor, G; Tan-Yee, A; Taylor, R H; Fielder, A R

1993-01-01

The Pulsair 2000 non-contact tonometer (Keeler Ltd, UK) is compared with the Goldmann applanation tonometer. Data from 80 eyes were acquired by four experienced observers. A linear regression analysis showed the relationship between the instruments to be: Pulsair = 0.66 + 0.95 Goldmann. Individual components of variation were analysed by analysis of variance which indicated a significant variation in the slope of the regression equation due to observers (p = 0.02) but not to the order in which topical anaesthesia was administered. Differences between two Pulsair instruments were of marginal significance (p = 0.07). The intercept of the regression equation was unaffected by any of the components of variation. Seventy-nine per cent of averaged intraocular pressure measurements obtained with the Pulsair 2000 fell on or within +/- 3 mmHg of those measured with the Goldmann tonometer. It is concluded that the Pulsair 2000 can provide clinically useful measurements of intraocular pressure.

Noncontact ultrasound imaging applied to cortical bone phantoms

OpenAIRE

Bulman, J. B.; Ganezer, K. S.; Halcrow, P. W.; Neeson, Ian

2012-01-01

Purpose: The purpose of this paper was to take the first steps toward applying noncontact ultrasound (NCU) to the tasks of monitoring osteoporosis and quantitative ultrasound imaging (QUS) of cortical bone. The authors also focused on the advantages of NCU, such as its lack of reliance on a technologist to apply transducers and a layer of acoustical coupling gel, the ability of the transducers to operate autonomously as specified by preprogrammed software, and the likely reduction in statisti...

Inverse calculation of strain profiles from ETDR measurements using artificial neural networks

Directory of Open Access Journals (Sweden)

R. Höhne

2017-12-01

Full Text Available A novel carbon fibre sensor is developed for the spatially resolved strain measurement. A unique feature of the sensor is the fibre-break resistive measurement principle and the two-core transmission line design. The electrical time domain reflectometry (ETDR is used in order to realize a spatially resolved measurement of the electrical parameters of the sensor. In this contribution, the process of mapping between the ETDR signals to the existing strain profile is described. Artificial neural networks (ANNs are used to solve the inverse electromagnetic problem. The investigations were carried out with a sensor patch in a cantilever arm configuration. Overall, 136 experiments with varying strain distribution over the sensor length were performed to generate the necessary training data to learn the ANN model. The validation of the ANN highlights the feasibility as well as the current limits concerning the quantitative accuracy of mapping ETDR signals to strain profiles.

Estimation of piping temperature fluctuations based on external strain measurements

International Nuclear Information System (INIS)

Morilhat, P.; Maye, J.P.

1993-01-01

Due to the difficulty to carry out measurements at the inner sides of nuclear reactor piping subjected to thermal transients, temperature and stress variations in the pipe walls are estimated by means of external thermocouples and strain-gauges. This inverse problem is solved by spectral analysis. Since the wall harmonic transfer function (response to a harmonic load) is known, the inner side signal will be obtained by convolution of the inverse transfer function of the system and of the strain measurement enables detection of internal temperature fluctuations in a frequency range beyond the scope of the thermocouples. (authors). 5 figs., 3 refs

POLYELECTROLYTE MULTILAYER STAMPING IN AQUEOUS PHASE AND NON-CONTACT MODE

Science.gov (United States)

Mehrotra, Sumit; Lee, Ilsoon; Liu, Chun; Chan, Christina

2011-01-01

Polyelectrolyte multilayer (PEM) transfer printing has been previously achieved by stamping under dry conditions. Here, we show for the first time, that PEM can be transferred from a stamp to the base substrate under aqueous conditions whereby the two surfaces are in a non-contact mode. Degradable multilayers of (PAA/PEG)10.5 followed by non-degradable multilayers of (PDAC/SPS)80.5 were fabricated under acidic pH conditions on either PDMS or glass (stamp), and subsequently transferred over top of another multilayer prepared on a different substrate (base substrate), with a spacing of ~ 200 μm between the stamping surface and the base substrate. This multilayer transfer was performed under physiological pH conditions. This process is referred to herein as non-contact, aqueous-phase multilayer (NAM) transfer. NAM transfer can be useful for applications such as fabricating three-dimensional (3-D) cellular scaffolds. We attempted to create a 3-D cellular scaffold using NAM transfer, and characterized the scaffolds with conventional and fluorescence microscopy. PMID:21860540

Non-Contact Sensor for Long-Term Continuous Vital Signs Monitoring: A Review on Intelligent Phased-Array Doppler Sensor Design

Science.gov (United States)

Hall, Travis; Nguyen, Tam Q.; Mayeda, Jill C.; Lie, Paul E.; Lopez, Jerry; Banister, Ron E.

2017-01-01

It has been the dream of many scientists and engineers to realize a non-contact remote sensing system that can perform continuous, accurate and long-term monitoring of human vital signs as we have seen in many Sci-Fi movies. Having an intelligible sensor system that can measure and record key vital signs (such as heart rates and respiration rates) remotely and continuously without touching the patients, for example, can be an invaluable tool for physicians who need to make rapid life-and-death decisions. Such a sensor system can also effectively help physicians and patients making better informed decisions when patients’ long-term vital signs data is available. Therefore, there has been a lot of research activities on developing a non-contact sensor system that can monitor a patient’s vital signs and quickly transmit the information to healthcare professionals. Doppler-based radio-frequency (RF) non-contact vital signs (NCVS) monitoring system are particularly attractive for long term vital signs monitoring because there are no wires, electrodes, wearable devices, nor any contact-based sensors involved so the subjects may not be even aware of the ubiquitous monitoring. In this paper, we will provide a brief review on some latest development on NCVS sensors and compare them against a few novel and intelligent phased-array Doppler-based RF NCVS biosensors we have built in our labs. Some of our NCVS sensor tests were performed within a clutter-free anechoic chamber to mitigate the environmental clutters, while most tests were conducted within the typical Herman-Miller type office cubicle setting to mimic a more practical monitoring environment. Additionally, we will show the measurement data to demonstrate the feasibility of long-term NCVS monitoring. The measured data strongly suggests that our latest phased array NCVS system should be able to perform long-term vital signs monitoring intelligently and robustly, especially for situations where the subject is

Non-Contact Sensor for Long-Term Continuous Vital Signs Monitoring: A Review on Intelligent Phased-Array Doppler Sensor Design.

Science.gov (United States)

Hall, Travis; Lie, Donald Y C; Nguyen, Tam Q; Mayeda, Jill C; Lie, Paul E; Lopez, Jerry; Banister, Ron E

2017-11-15

It has been the dream of many scientists and engineers to realize a non-contact remote sensing system that can perform continuous, accurate and long-term monitoring of human vital signs as we have seen in many Sci-Fi movies. Having an intelligible sensor system that can measure and record key vital signs (such as heart rates and respiration rates) remotely and continuously without touching the patients, for example, can be an invaluable tool for physicians who need to make rapid life-and-death decisions. Such a sensor system can also effectively help physicians and patients making better informed decisions when patients' long-term vital signs data is available. Therefore, there has been a lot of research activities on developing a non-contact sensor system that can monitor a patient's vital signs and quickly transmit the information to healthcare professionals. Doppler-based radio-frequency (RF) non-contact vital signs (NCVS) monitoring system are particularly attractive for long term vital signs monitoring because there are no wires, electrodes, wearable devices, nor any contact-based sensors involved so the subjects may not be even aware of the ubiquitous monitoring. In this paper, we will provide a brief review on some latest development on NCVS sensors and compare them against a few novel and intelligent phased-array Doppler-based RF NCVS biosensors we have built in our labs. Some of our NCVS sensor tests were performed within a clutter-free anechoic chamber to mitigate the environmental clutters, while most tests were conducted within the typical Herman-Miller type office cubicle setting to mimic a more practical monitoring environment. Additionally, we will show the measurement data to demonstrate the feasibility of long-term NCVS monitoring. The measured data strongly suggests that our latest phased array NCVS system should be able to perform long-term vital signs monitoring intelligently and robustly, especially for situations where the subject is sleeping

Non-Contact Sensor for Long-Term Continuous Vital Signs Monitoring: A Review on Intelligent Phased-Array Doppler Sensor Design

Directory of Open Access Journals (Sweden)

Travis Hall

2017-11-01

Full Text Available It has been the dream of many scientists and engineers to realize a non-contact remote sensing system that can perform continuous, accurate and long-term monitoring of human vital signs as we have seen in many Sci-Fi movies. Having an intelligible sensor system that can measure and record key vital signs (such as heart rates and respiration rates remotely and continuously without touching the patients, for example, can be an invaluable tool for physicians who need to make rapid life-and-death decisions. Such a sensor system can also effectively help physicians and patients making better informed decisions when patients’ long-term vital signs data is available. Therefore, there has been a lot of research activities on developing a non-contact sensor system that can monitor a patient’s vital signs and quickly transmit the information to healthcare professionals. Doppler-based radio-frequency (RF non-contact vital signs (NCVS monitoring system are particularly attractive for long term vital signs monitoring because there are no wires, electrodes, wearable devices, nor any contact-based sensors involved so the subjects may not be even aware of the ubiquitous monitoring. In this paper, we will provide a brief review on some latest development on NCVS sensors and compare them against a few novel and intelligent phased-array Doppler-based RF NCVS biosensors we have built in our labs. Some of our NCVS sensor tests were performed within a clutter-free anechoic chamber to mitigate the environmental clutters, while most tests were conducted within the typical Herman-Miller type office cubicle setting to mimic a more practical monitoring environment. Additionally, we will show the measurement data to demonstrate the feasibility of long-term NCVS monitoring. The measured data strongly suggests that our latest phased array NCVS system should be able to perform long-term vital signs monitoring intelligently and robustly, especially for situations where the

Strain measurement in and analysis for hydraulic test of CPR1000 reactor pressure vessel

International Nuclear Information System (INIS)

Zhou Dan; Zhuang Dongzhen

2013-01-01

The strain measurement in hydraulic test of CPR1000 reactor pressure vessel performed in Dongfang Heavy Machinery Co., Ltd. is introduced. The detail test scheme and method was introduced and the measurement results of strain and stress was given. Meanwhile the finite element analysis was performed for the pressure vessel, which was generally matched with the measurement results. The reliability of strain measurement was verified and the high strength margin of vessel was shown, which would give a good reference value for the follow-up hydraulic tests and strength analysis of reactor pressure vessel. (authors)

Development of a fiber optic pavement subgrade strain measurement system

Science.gov (United States)

Miller, Craig Emerson

2000-11-01

This dissertation describes the development of a fiber optic sensing system to measure strains within the soil subgrade of highway pavements resulting from traffic loads. The motivation to develop such a device include improvements to: (1)all phases of pavement design, (2)theoretical models used to predict pavement performance, and (3)pavement rehabilitation. The design of the sensing system encompasses selecting an appropriate transducer design as well as the development of optimal optical and demodulation systems. The first is spring based, which attempts to match its spring stiffness to that of the soil-data indicate it is not an optimal transducer design. The second transducer implements anchoring plates attached to two telescoping tubes which allows the soil to be compacted to a desired density between the plates to dictate the transducer's behavior. Both transducers include an extrinsic Fabry- Perot cavity to impose the soil strains onto a phase change of the optical signal propagating through the cavity. The optical system includes a low coherence source and allows phase modulation via path length stretching by adding a second interferometer in series with the transducer, resulting in a path matched differential interferometer. A digitally implemented synthetic heterodyne demodulator based on a four step phase stepping algorithm is used to obtain unambiguous soil strain information from the displacement of the Fabry-Perot cavity. The demodulator is calibrated and characterized by illuminating the transducer with a second long coherence source of different wavelength. The transducer using anchoring plates is embedded within cylindrical soil specimens of varying soil types and soil moisture contents. Loads are applied to the specimen and resulting strains are measured using the embedded fiber optic gage and LVDTs attached to the surface of the specimen. This experimental verification is substantiated using a finite element analysis to predict any differences

The measurement of the modal strain fields using digital shearography

Directory of Open Access Journals (Sweden)

Gomes J.M.

2010-06-01

Full Text Available This work presents a Michelson shearography interferometer configuration associated with stroboscopic double illumination technique for the measurement of modal rotation fields and their strain fields on a clamped circular aluminium plate. The speckle pattern is frozen by the synchronization between the LASER illumination and the modal vibration of the object. The quantitative evaluation is performed for each digital shearogram using a time modulation technique. The setup of double illumination LASER with out-of-plane opposite sensitivity allows the two phase maps measurement of the modal spatial gradient. The modal rotation and strain fields are extracted by the combination of this two digital phase maps. Image processing techniques are applied on the phase maps to obtain full-field measurements using a dedicated post-processing algorithm. Finally, is presented a comparison between the experimental measurement and the numerical solution.

3D optical measuring technologies for dimensional inspection

International Nuclear Information System (INIS)

Chugui, Yu V

2005-01-01

The results of the R and D activity of TDI SIE SB RAS in the field of the 3D optical measuring technologies and systems for noncontact 3D optical dimensional inspection applied to atomic and railway industry safety problems are presented. This activity includes investigations of diffraction phenomena on some 3D objects, using the original constructive calculation method, development of hole inspection method on the base of diffractive optical elements. Ensuring the safety of nuclear reactors and running trains as well as their high exploitation reliability takes a noncontact inspection of geometrical parameters of their components. For this tasks we have developed methods and produced the technical vision measuring systems LMM, CONTROL, PROFILE, and technologies for non-contact 3D dimensional inspection of grid spacers and fuel elements for the nuclear reactor VVER-1000 and VVER-440, as well as automatic laser diagnostic system COMPLEX for noncontact inspection of geometrical parameters of running freight car wheel pairs. The performances of these systems and the results of the industrial testing at atomic and railway companies are presented

Noncontact Er:YAG laser ablation: clinical evaluation.

Science.gov (United States)

Dostálová, T; Jelínková, H; Kucerová, H; Krejsa, O; Hamal, K; Kubelka, J; Procházka, S

1998-10-01

The aim of this study is to evaluate the quality of laser ablation in comparison with the classical drilling preparation. For the experiment, the Er:YAG laser drilling machine was used. The system had a laser head, water cooler, and power supply with automatic control. Spot size of 300-350 microns was used for the preparation. Repetition rate of 1-4 Hz, and pulse energies of 100-400 mJ with water spray were chosen. Cavity shape in comparison with classical drill, time of preparation, and influence of cavity shape on filling materials retention in accordance with the U.S. Public Health Service System were used. The evaluation criteria for noncontact Er:YAG ablation were done. The cavity shape is irregular, but spot surface has larger area and microretentive appearance. Caries of enamel and dentin were treated with a noncontact preparation. It was possible to remove the old insufficient fillings, except for amalgam or metal alloys. The average number of pulses was 111.22 (SE 67.57). Vibrations of microexplosions during preparation were felt by patients on 14 cavities; however, nobody felt unpleasant pain. The qualities of filling materials in laser cavities were very stable; however, cavo surface margin discoloration of 82-86% of Alfa rating could be a problem. Changes of the color and anatomic form of the tooth were observed in 4-8%. In comparison with the classical treatment, it could be said that the retention and quality of filling materials is the same or very similar.

Pipeline Bending Strain Measurement and Compensation Technology Based on Wavelet Neural Network

Directory of Open Access Journals (Sweden)

Rui Li

2016-01-01

Full Text Available The bending strain of long distance oil and gas pipelines may lead to instability of the pipeline and failure of materials, which seriously deteriorates the transportation security of oil and gas. To locate the position of the bending strain for maintenance, an Inertial Measurement Unit (IMU is usually adopted in a Pipeline Inspection Gauge (PIG. The attitude data of the IMU is usually acquired to calculate the bending strain in the pipe. However, because of the vibrations in the pipeline and other system noises, the resulting bending strain calculations may be incorrect. To improve the measurement precision, a method, based on wavelet neural network, was proposed. To test the proposed method experimentally, a PIG with the proposed method is used to detect a straight pipeline. It can be obtained that the proposed method has a better repeatability and convergence than the original method. Furthermore, the new method is more accurate than the original method and the accuracy of bending strain is raised by about 23% compared to original method. This paper provides a novel method for precisely inspecting bending strain of long distance oil and gas pipelines and lays a foundation for improving the precision of inspection of bending strain of long distance oil and gas pipelines.

[Contemporary possibilities of intraocular pressure measurement].

Science.gov (United States)

Hornová, J; Baxant, A

2013-10-01

Authors introduced current possibilities of measuring intraocular pressure (IOP). A list of available methods of monitoring IOP is published; contact measurement method IOP directly on the cornea, but also over upper lid, methodology of minimal contact and non-contact measurement. Following contact methods are described; former measurements of IOP by impression Schiotz tonometer and the current methodology applanation. So far as the gold standard measurement Goldmann applanation tonometer (GAT) is considered, another methodology with applanation measurements are compared: Pascal dynamic contoured tonometer (DCT ), BioResonator - resonant applanation tonometer (ART ), digital applanation tonometer Tonopen and last hit: continuous measurement of IOP by Sensimed Triggerfish. Orientation and rapid assessment is palpation pressure control over the lid and measuring by tonometer Diaton. Rebound tonometer (RBT) iCare belongs to measurements with minimal contact, no need anesthetic drops and fluorescein, therefore a self - home version of IOP measurements (Icare ONE) is developed. Non-contact measurement of IOP by different pneumotonometers is popular for screening assessment of IOP. Reichert Ocular Response Analyzer (ORA) is a non-contact applanation IOP measurement and reveals additional properties of the cornea. In the discussion of a range methodology is evaluated, the experience of other authors and their own experience is compared. For monitoring of patients is necessary to select the most suitable methodology, measure repeatedly and accurately to allow long-term monitoring of intraocular pressure.

Coupled biomechanical response of the cornea assessed by non-contact tonometry. A simulation study.

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Miguel Á Ariza-Gracia

Full Text Available The mechanical response of the cornea subjected to a non-contact air-jet tonometry diagnostic test represents an interplay between its geometry, the corneal material behavior and the loading. The objective is to study this interplay to better understand and interpret the results obtained with a non-contact tonometry test. A patient-specific finite element model of a healthy eye, accounting for the load free configuration, was used. The corneal tissue was modeled as an anisotropic hyperelastic material with two preferential directions. Three different sets of parameters within the human experimental range obtained from inflation tests were considered. The influence of the IOP was studied by considering four pressure levels (10-28 mmHg whereas the influence of corneal thickness was studied by inducing a uniform variation (300-600 microns. A Computer Fluid Dynamics (CFD air-jet simulation determined pressure loading exerted on the anterior corneal surface. The maximum apex displacement showed a linear variation with IOP for all materials examined. On the contrary, the maximum apex displacement followed a cubic relation with corneal thickness. In addition, a significant sensitivity of the apical displacement to the corneal stiffness was also obtained. Explanation to this behavior was found in the fact that the cornea experiences bending when subjected to an air-puff loading, causing the anterior surface to work in compression whereas the posterior surface works in tension. Hence, collagen fibers located at the anterior surface do not contribute to load bearing. Non-contact tonometry devices give useful information that could be misleading since the corneal deformation is the result of the interaction between the mechanical properties, IOP, and geometry. Therefore, a non-contact tonometry test is not sufficient to evaluate their individual contribution and a complete in-vivo characterization would require more than one test to independently determine

Measurements and predictions of strain pole figures for uniaxially compressed stainless steel

International Nuclear Information System (INIS)

Larsson, C.; Clausen, B.; Holden, T.M.; Bourke, M.A.M.

2004-01-01

Strain pole figures representative of residual intergranular strains were determined from an -2.98% uniaxially compressed austenitic stainless steel sample. The measurements were made using neutron diffraction on the recently commissioned Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory, USA. The measurements were compared with predictions from an elasto-plastic self-consistent model and found to be in good agreement

Measurements and predictions of strain pole figures for uniaxially compressed stainless steel

Energy Technology Data Exchange (ETDEWEB)

Larsson, C. [Division of Engineering Materials, Department of Mechanical Engineering, Linkoeping University, 58183 Linkoeping (Sweden)]. E-mail: clarsson@cfl.rr.com; Clausen, B. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Holden, T.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, M.A.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2004-09-15

Strain pole figures representative of residual intergranular strains were determined from an -2.98% uniaxially compressed austenitic stainless steel sample. The measurements were made using neutron diffraction on the recently commissioned Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory, USA. The measurements were compared with predictions from an elasto-plastic self-consistent model and found to be in good agreement.

Application of Digital Image Correlation to Measurement of Packaging Material Mechanical Properties

Directory of Open Access Journals (Sweden)

Jian-Wei Zhou

2013-01-01

Full Text Available Among various packaging materials, papers and polymer plastics are the most common due to their light weights, low costs, and other advantages. However, their mechanical properties are difficult to measure precisely because of their softness. To overcome the difficulty, a new measure instrument prototype is proposed based on an optical method known as the digital image correlation (DIC. Experiments are designed to apply the DIC to measure mechanical properties of flexible packaging materials, including the stress-strain relationship, the Poisson ratio, the coefficient of heat expansion, the creep deformation, and the top-pressure deformation of corrugated box. In addition, the low frequency vibration of package is simulated, and the vibration frequencies are measured by DIC. Results obtained in the experiments illustrate the advantages of the DIC over traditional methods: noncontact, no reinforced effect, high precision over entire area, wide measurement range, and good measurement stability.

A three-dimensional strain measurement method in elastic transparent materials using tomographic particle image velocimetry.

Directory of Open Access Journals (Sweden)

Azuma Takahashi

Full Text Available The mechanical interaction between blood vessels and medical devices can induce strains in these vessels. Measuring and understanding these strains is necessary to identify the causes of vascular complications. This study develops a method to measure the three-dimensional (3D distribution of strain using tomographic particle image velocimetry (Tomo-PIV and compares the measurement accuracy with the gauge strain in tensile tests.The test system for measuring 3D strain distribution consists of two cameras, a laser, a universal testing machine, an acrylic chamber with a glycerol water solution for adjusting the refractive index with the silicone, and dumbbell-shaped specimens mixed with fluorescent tracer particles. 3D images of the particles were reconstructed from 2D images using a multiplicative algebraic reconstruction technique (MART and motion tracking enhancement. Distributions of the 3D displacements were calculated using a digital volume correlation. To evaluate the accuracy of the measurement method in terms of particle density and interrogation voxel size, the gauge strain and one of the two cameras for Tomo-PIV were used as a video-extensometer in the tensile test. The results show that the optimal particle density and interrogation voxel size are 0.014 particles per pixel and 40 × 40 × 40 voxels with a 75% overlap. The maximum measurement error was maintained at less than 2.5% in the 4-mm-wide region of the specimen.We successfully developed a method to experimentally measure 3D strain distribution in an elastic silicone material using Tomo-PIV and fluorescent particles. To the best of our knowledge, this is the first report that applies Tomo-PIV to investigate 3D strain measurements in elastic materials with large deformation and validates the measurement accuracy.

Thermal screening of facial skin arterial hot spots using non-contact infrared radiometry

International Nuclear Information System (INIS)

Williams, E M; Heusch, A I; McCarthy, P W

2008-01-01

Non-contact infrared thermometry of facial skin offers advantages over less accessible internal body sites, especially when considering mass screening for febrile infectious disease. The forehead offers an obvious site, but does not present an isothermic surface, as various small arteries passing close to the surface create 'hot-spots'. The aim of this study is to use non-contact infrared (IR) thermometry to determine the link between the temperature at specific facial skin sites and clinical body temperature. A sample of 169 asymptomatic adults (age range 18–54 years) was screened with IR thermometers (Braun Thermoscan proLT for auditory meatus (AM) temperature representing clinical body temperature, and a Raytek, Raynger MX for skin surface temperature). Peak IR skin temperature was measured over the course of each posterior auricular artery (PAA) and each superficial temporal artery (STA). In a sub-group (n = 54) the peak skin temperature of the forehead's metopic region (MR) was also recorded. There were no differences (P > 0.05) between the PAA and STA at 34.2 ± 0.9 °C and 34.2 ± 0.7 °C, respectively, which were 2.5 °C cooler than the AM temperature (36.7 ± 0.5 °C, p 2 = 0.63, p < 0.001) between PAA and STA. There were no asymmetric temperature differences between the left and right sides and males had warmer skin over the MR (F, 33.6 ± 0.7 °C versus M, 34.4 ± 0.6 °C, p < 0.001). Although a lack of correlation between either PAA or STA and AM was apparent in asymptomatics, further research in symptomatics is required to determine the usefulness of these measurements in mass screening of conditions such as fever

Comparison of two methods of tonometry in glaucoma patients: Goldmann applanation tonometer and non-contact tonometer

Directory of Open Access Journals (Sweden)

Hong-Feng Li

2015-01-01

Full Text Available AIM: To compare the two methods for the measurement of glaucoma patients' intraocular pressure(IOPbetween Goldmann applanation tonometer(GATand non-contact tonometer(NCTand find the laws of the two methods.METHODS: The IOP of 108 glaucoma patients(206 eyeswere measured by GAT and NCT respectively. RESULTS: In 108 glaucoma patients, the average IOP of 206 eyes was 29.77±10.27mmHg by GAT and 24.59±8.58mmHg by NCT. There was significant difference between GAT and NCT(PCONCLUSION: The measurement results with NCT were lower than that of GAT. The higher of IOP, the difference between GAT and NCT was greater. It's better to measure IOP by GAT for the glaucoma patients, in order to avoid the misdiagnosis and mistreatment of glaucoma.

Application of fiber optic grating strain sensor for measurement of strain under irradiation environment

International Nuclear Information System (INIS)

Kaji, Y.; Matsui, Y.; Kita, S.; Ide, H.; Tsukada, T.; Tsuji, H.

2001-01-01

In Japan Atomic Energy Research Institute (JAERI), in-pile strain measurement techniques have been developed using Japan Materials Testing Reactor (JMTR). In order to evaluate the performance of fiber optic grating sensor under irradiation environment, heat-up and performance tests at elevated temperature before irradiation and in-pile tests were performed in JMTR. (author)

NDE (Nondestructive examination) by ultrasonic, photo-elastic, strain measuring and FEM (Finite Element Method)

International Nuclear Information System (INIS)

Gu Fangyu; Zeng Xiao

1990-01-01

It is considered impossible to inspect flaw by using ordinary mechanical measuring methods. In this paper, it is found that the stree and strain distortions of pressure vessel with 2D linear shape crack in the deep location appear the 'cat effect' on the surface of stracture, and that the location and size of the crack can be determined with strain measuring and FEM according to 'cat effect' of strain distortion

An Approach for the Dynamic Measurement of Ring Gear Strains of Planetary Gearboxes Using Fiber Bragg Gratings

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Hang Niu

2017-12-01

Full Text Available The strain of the ring gear can reflect the dynamic characteristics of planetary gearboxes directly, which makes it an ideal signal to monitor the health condition of the gearbox. To overcome the disadvantages of traditional methods, a new approach for the dynamic measurement of ring gear strains using fiber Bragg gratings (FBGs is proposed in this paper. Firstly, the installation of FBGs is determined according to the analysis for the strain distribution of the ring gear. Secondly, the parameters of the FBG are determined in consideration of the accuracy and sensitivity of the measurement as well as the size of the ring gear. The strain measured by the FBG is then simulated under non-uniform strain field conditions. Thirdly, a dynamic measurement system is built and tested. Finally, the strains of the ring gear are measured in a planetary gearbox under normal and faulty conditions. The experimental results showed good agreement with the theoretical results in values, trends, and the fault features can be seen from the time domain of the measured strain signal, which proves that the proposed method is feasible for the measurement of the ring gear strains of planetary gearboxes.

An Approach for the Dynamic Measurement of Ring Gear Strains of Planetary Gearboxes Using Fiber Bragg Gratings.

Science.gov (United States)

Niu, Hang; Zhang, Xiaodong; Hou, Chenggang

2017-12-16

The strain of the ring gear can reflect the dynamic characteristics of planetary gearboxes directly, which makes it an ideal signal to monitor the health condition of the gearbox. To overcome the disadvantages of traditional methods, a new approach for the dynamic measurement of ring gear strains using fiber Bragg gratings (FBGs) is proposed in this paper. Firstly, the installation of FBGs is determined according to the analysis for the strain distribution of the ring gear. Secondly, the parameters of the FBG are determined in consideration of the accuracy and sensitivity of the measurement as well as the size of the ring gear. The strain measured by the FBG is then simulated under non-uniform strain field conditions. Thirdly, a dynamic measurement system is built and tested. Finally, the strains of the ring gear are measured in a planetary gearbox under normal and faulty conditions. The experimental results showed good agreement with the theoretical results in values, trends, and the fault features can be seen from the time domain of the measured strain signal, which proves that the proposed method is feasible for the measurement of the ring gear strains of planetary gearboxes.

Defect-detection algorithm for noncontact acoustic inspection using spectrum entropy

Science.gov (United States)

Sugimoto, Kazuko; Akamatsu, Ryo; Sugimoto, Tsuneyoshi; Utagawa, Noriyuki; Kuroda, Chitose; Katakura, Kageyoshi

2015-07-01

In recent years, the detachment of concrete from bridges or tunnels and the degradation of concrete structures have become serious social problems. The importance of inspection, repair, and updating is recognized in measures against degradation. We have so far studied the noncontact acoustic inspection method using airborne sound and the laser Doppler vibrometer. In this method, depending on the surface state (reflectance, dirt, etc.), the quantity of the light of the returning laser decreases and optical noise resulting from the leakage of light reception arises. Some influencing factors are the stability of the output of the laser Doppler vibrometer, the low reflective characteristic of the measurement surface, the diffused reflection characteristic, measurement distance, and laser irradiation angle. If defect detection depends only on the vibration energy ratio since the frequency characteristic of the optical noise resembles white noise, the detection of optical noise resulting from the leakage of light reception may indicate a defective part. Therefore, in this work, the combination of the vibrational energy ratio and spectrum entropy is used to judge whether a measured point is healthy or defective or an abnormal measurement point. An algorithm that enables more vivid detection of a defective part is proposed. When our technique was applied in an experiment with real concrete structures, the defective part could be extracted more vividly and the validity of our proposed algorithm was confirmed.

Direct Strain and Slope and Slope Measurement Using 2D DSPSI

International Nuclear Information System (INIS)

Dandach, W.; Molimard, J.; Picart, P.

2011-01-01

Large variety of optical full-field measurement techniques are being developed and applied to solve mechanical problems. Since each technique possesses its own merits, it is important to know the capabilities and limitations of such techniques. Among these optical full-field methods, interferometry techniques take an important place. They are based on illumination with coherent light (laser). In shearing interferometry the difference of the out of-plane displacement in two neighboring object points is directly measured. Since object displacement does not result in interferometry fringes, the method is suited for localization of strain concentrations and is indeed used in industry for this purpose. DSPSI possesses the advantage over conventional out-of-plane displacement-sensitive interferometry, that only a single difference of the unwrapped phase map is required to obtain flexural strains, thereby relieving problems with noise and reduction in the field of view. A first work in this domain (DSPSI) [1] was made in 1973, later recent studies emerged to provide a quantitative system of measurements [2]. This work aims to present the results of strain and slope measurements using digital speckle pattern shearing interferometry (DSPSI). (author)

Validation Tests of Fiber Optic Strain-Based Operational Shape and Load Measurements

Science.gov (United States)

Bakalyar, John A.; Jutte, Christine

2012-01-01

Aircraft design has been progressing toward reduced structural weight to improve fuel efficiency, increase performance, and reduce cost. Lightweight aircraft structures are more flexible than conventional designs and require new design considerations. Intelligent sensing allows for enhanced control and monitoring of aircraft, which enables increased structurally efficiency. The NASA Dryden Flight Research Center (DFRC) has developed an instrumentation system and analysis techniques that combine to make distributed structural measurements practical for lightweight vehicles. Dryden's Fiber Optic Strain Sensing (FOSS) technology enables a multitude of lightweight, distributed surface strain measurements. The analysis techniques, referred to as the Displacement Transfer Functions (DTF) and Load Transfer Functions (LTF), use surface strain values to calculate structural deflections and operational loads. The combined system is useful for real-time monitoring of aeroelastic structures, along with many other applications. This paper describes how the capabilities of the measurement system were demonstrated using subscale test articles that represent simple aircraft structures. Empirical FOSS strain data were used within the DTF to calculate the displacement of the article and within the LTF to calculate bending moments due to loads acting on the article. The results of the tests, accuracy of the measurements, and a sensitivity analysis are presented.

Acute non-contact anterior cruciate ligament tears are associated with relatively increased vastus medialis to semimembranosus cross-sectional area ratio: a case-control retrospective MR study

International Nuclear Information System (INIS)

Wieschhoff, Ged G.; Mandell, Jacob C.; Czuczman, Gregory J.; Nikac, Violeta; Shah, Nehal; Smith, Stacy E.

2017-01-01

Hamstring muscle deficiency is increasingly recognized as a risk factor for anterior cruciate ligament (ACL) tears. The purpose of this study is to evaluate the vastus medialis to semimembranosus cross-sectional area (VM:SM CSA) ratio on magnetic resonance imaging (MRI) in patients with ACL tears compared to controls. One hundred knee MRIs of acute ACL tear patients and 100 age-, sex-, and side-matched controls were included. Mechanism of injury, contact versus non-contact, was determined for each ACL tear subject. The VM:SM CSA was measured on individual axial slices with a novel method using image-processing software. One reader measured all 200 knees and the second reader measured 50 knees at random to assess inter-reader variability. The intraclass correlation coefficient (ICC) was calculated to evaluate for correlation between readers. T-tests were performed to evaluate for differences in VM:SM CSA ratios between the ACL tear group and control group. The ICC for agreement between the two readers was 0.991 (95% confidence interval 0.984-0.995). Acute ACL tear patients have an increased VM:SM CSA ratio compared to controls (1.44 vs. 1.28; p = 0.005). Non-contact acute ACL tear patients have an increased VM:SM CSA ratio compared to controls (1.48 vs. 1.20; p = 0.003), whereas contact acute ACL tear patients do not (1.23 vs. 1.26; p = 0.762). Acute non-contact ACL tears are associated with increased VM:SM CSA ratios, which may imply a relative deficiency in hamstring strength. This study also demonstrates a novel method of measuring the relative CSA of muscles on MRI. (orig.)

Acute non-contact anterior cruciate ligament tears are associated with relatively increased vastus medialis to semimembranosus cross-sectional area ratio: a case-control retrospective MR study.

Science.gov (United States)

Wieschhoff, Ged G; Mandell, Jacob C; Czuczman, Gregory J; Nikac, Violeta; Shah, Nehal; Smith, Stacy E

2017-11-01

Hamstring muscle deficiency is increasingly recognized as a risk factor for anterior cruciate ligament (ACL) tears. The purpose of this study is to evaluate the vastus medialis to semimembranosus cross-sectional area (VM:SM CSA) ratio on magnetic resonance imaging (MRI) in patients with ACL tears compared to controls. One hundred knee MRIs of acute ACL tear patients and 100 age-, sex-, and side-matched controls were included. Mechanism of injury, contact versus non-contact, was determined for each ACL tear subject. The VM:SM CSA was measured on individual axial slices with a novel method using image-processing software. One reader measured all 200 knees and the second reader measured 50 knees at random to assess inter-reader variability. The intraclass correlation coefficient (ICC) was calculated to evaluate for correlation between readers. T-tests were performed to evaluate for differences in VM:SM CSA ratios between the ACL tear group and control group. The ICC for agreement between the two readers was 0.991 (95% confidence interval 0.984-0.995). Acute ACL tear patients have an increased VM:SM CSA ratio compared to controls (1.44 vs. 1.28; p = 0.005). Non-contact acute ACL tear patients have an increased VM:SM CSA ratio compared to controls (1.48 vs. 1.20; p = 0.003), whereas contact acute ACL tear patients do not (1.23 vs. 1.26; p = 0.762). Acute non-contact ACL tears are associated with increased VM:SM CSA ratios, which may imply a relative deficiency in hamstring strength. This study also demonstrates a novel method of measuring the relative CSA of muscles on MRI.

Acute non-contact anterior cruciate ligament tears are associated with relatively increased vastus medialis to semimembranosus cross-sectional area ratio: a case-control retrospective MR study

Energy Technology Data Exchange (ETDEWEB)

Wieschhoff, Ged G.; Mandell, Jacob C.; Czuczman, Gregory J.; Nikac, Violeta; Shah, Nehal; Smith, Stacy E. [Brigham and Women' s Hospital, Harvard Medical School, Division of Musculoskeletal Imaging and Intervention, Department of Radiology, Boston, MA (United States)

2017-11-15

Hamstring muscle deficiency is increasingly recognized as a risk factor for anterior cruciate ligament (ACL) tears. The purpose of this study is to evaluate the vastus medialis to semimembranosus cross-sectional area (VM:SM CSA) ratio on magnetic resonance imaging (MRI) in patients with ACL tears compared to controls. One hundred knee MRIs of acute ACL tear patients and 100 age-, sex-, and side-matched controls were included. Mechanism of injury, contact versus non-contact, was determined for each ACL tear subject. The VM:SM CSA was measured on individual axial slices with a novel method using image-processing software. One reader measured all 200 knees and the second reader measured 50 knees at random to assess inter-reader variability. The intraclass correlation coefficient (ICC) was calculated to evaluate for correlation between readers. T-tests were performed to evaluate for differences in VM:SM CSA ratios between the ACL tear group and control group. The ICC for agreement between the two readers was 0.991 (95% confidence interval 0.984-0.995). Acute ACL tear patients have an increased VM:SM CSA ratio compared to controls (1.44 vs. 1.28; p = 0.005). Non-contact acute ACL tear patients have an increased VM:SM CSA ratio compared to controls (1.48 vs. 1.20; p = 0.003), whereas contact acute ACL tear patients do not (1.23 vs. 1.26; p = 0.762). Acute non-contact ACL tears are associated with increased VM:SM CSA ratios, which may imply a relative deficiency in hamstring strength. This study also demonstrates a novel method of measuring the relative CSA of muscles on MRI. (orig.)

Development of a strain measurement method for non-plane specimens by means of computer picture processing

International Nuclear Information System (INIS)

Yoshioka, Akira; Soneda, Naoki; Yagawa, Genki; Miyoshi, Akio.

1988-01-01

Integrity Tests of the Fast Breeder Reactor components are often conducted at an elevated temperature, say 550deg C. Since high-temperature strain measurement using special strain gauges is costly and unappropriate for large and repeated strains, the authors have developed an optical strain measurement method and system based on computer picture processing and the triangulation principle. The present method enables us to measure the strain in specimen with curved surfaces. Its operation is also easy, because of the automatic distinction of marks from noises. The verification tests with a plate specimen and a cylindrical one are performed under elevated temperatures. The results show that the present method is very suitable to the tests under elevated temperatures and that the measurement error of strain is within 0.2 % (2000μ), which is reasonable considering the limitation of hardware. (author)

Noninjured Knees of Patients With Noncontact ACL Injuries Display Higher Average Anterior and Internal Rotational Knee Laxity Compared With Healthy Knees of a Noninjured Population.

Science.gov (United States)

Mouton, Caroline; Theisen, Daniel; Meyer, Tim; Agostinis, Hélène; Nührenbörger, Christian; Pape, Dietrich; Seil, Romain

2015-08-01

Excessive physiological anterior and rotational knee laxity is thought to be a risk factor for noncontact anterior cruciate ligament (ACL) injuries and inferior reconstruction outcomes, but no thresholds have been established to identify patients with increased laxity. (1) To determine if the healthy contralateral knees of ACL-injured patients have greater anterior and rotational knee laxity, leading to different laxity profiles (combination of laxities), compared with healthy control knees and (2) to set a threshold to help discriminate anterior and rotational knee laxity between these groups. Case-sectional study; Level of evidence, 3. A total of 171 healthy contralateral knees of noncontact ACL-injured patients (ACL-H group) and 104 healthy knees of control participants (CTL group) were tested for anterior and rotational laxity. Laxity scores (measurements corrected for sex and body mass) were used to classify knees as hypolax (score 1). Proportions of patients in each group were compared using χ(2) tests. Receiver operating characteristic curves were computed to discriminate laxity between the groups. Odds ratios were calculated to determine the probability of being in the ACL-H group. The ACL-H group displayed greater laxity scores for anterior displacement and internal rotation in their uninjured knee compared with the CTL group (P knees of patients with noncontact ACL injuries display different laxity values both for internal rotation and anterior displacement compared with healthy control knees. The identification of knee laxity profiles may be of relevance for primary and secondary prevention programs of noncontact ACL injuries. © 2015 The Author(s).

Measuring techniques for autogenous strain of cement paste

DEFF Research Database (Denmark)

Lura, Pietro; Jensen, Ole Mejlhede

2007-01-01

Volumetric measurement of autogenous strain is frequently performed by placing the fresh cement paste in a rubber membrane submerged in water. The volume change of the cement paste is measured by the amount of water displaced by the submerged sample. Volumetric and linear measurements of autogenous...... of the volumetric method. Water absorption is driven by a lowering of the water activity in the cement paste due to dissolved salts in the pore fluid and to self-desiccation. From the moment of casting, significant water uptake was registered in all experiments. This water uptake influenced the volumetric...... on the same cement pastes....

[Prospective comparison of the new indentation tonometer TGdC-01, the non-contact tonometer PT100 and the conventional Goldmann applanation tonometer].

Science.gov (United States)

Müller, A; Godenschweger, L; Lang, G E; Kampmeier, J

2004-09-01

This study aimed to compare the results of newer tonometric techniques with standard tonometry for the examples of the Goldmann applanation tonometry (GAT), the indentation tonometer "TGDc-01" and the non-contact tonometer "PT 100". The study was conducted on a total of 52 healthy subjects. The IOP was measured in each subject on both eyes with all three methods. There were 27 males (51.9 %), 25 females (48.1 %) with an average age of 28.5 years, with a minimum of 13 and a maximum of 79 years. There was no statistically significant difference between the non-contact and the Goldmann applanation tonometry. The measurements were 0.4 mmHg lower, no difference for the left or right side was seen. For IOP higher than 15 mmHg - 0.88 mmHg lower and for IOP lower 15 mmHg - 0.15 mmHg. The results for the "TGDc01" were 0.82 mmHg lower than GAT, the standard deviation was a little higher with 2.9 mmHg compared to 2.67 mmHg for GAT. For IOP higher than 15 mmHg they rose up to - 2.28 mmHg, for IOP lower than 15 mmHg the results for "TGDc-01" were only - 0.2 mmHg lower. There was also an effect with respect to the side, on the right eye the difference was significant with 3.03 mmHg (p = 0.006), in contrast to the left eye with 2.69 mmHg (p = 0.235). For "TGDc01" the standard deviation was higher with 2.9 mmHg compared to 2.6 mmHg for "PT 100". The non-contact tonometer showed no clinical relevant difference compared with GAT for measuring IOP. The indentation tonometer showed differences for precision, for higher tension IOP the measurement was lower compared with GAT. There was also a significant side difference using the "TGDc-01".

Reliability of the non-contact tono-pachymeter Tonopachy NT-530P in healthy eyes.

Science.gov (United States)

García-Resúa, Carlos; Pena-Verdeal, Hugo; Miñones, Mercedes; Giraldez, M Jesus; Yebra-Pimentel, Eva

2013-05-01

Non-contact Tonopachy NT-530P (Nidek Co., LTD) provides intraocular pressure (IOP) and central corneal thickness (CCT) measurements. This study assesses the reliability and repeatability of its IOP measurements in young healthy adult subjects. IOP was determined in the right eye of 64 healthy patients using Tonopachy followed by the Canon TX-10 non-contact and Goldmann applanation (GAT) tonometers. Tonopachy IOP measurements were corrected (Tonopachy-C) or not (Tonopachy-NC) by the instrument for central corneal thickness. Central corneal thickness measurements provided by Tonopachy were also used to correlate (Pearson's coefficient) central corneal thickness with the GAT and Canon TX-10 IOPs. Repeatability of Tonopachy and GAT was assessed in the right eye of 31 subjects in two separate sessions one week apart. Differences between pairs of instruments and between sessions were determined using Bland-Altman plots. The coefficient of repeatability was calculated as the 95% limits of agreement (LoA) of differences between the two sessions. Tonopachy-NC, Tonopachy-C, Canon TX-10 and the Goldmann tonometers showed a mean IOP of 14.62, 15.64, 15.02 and 14.68 mmHg, respectively. Tonopachy-NC and Canon TX-10 readings did not differ significantly from the Goldmann (p > 0.05), with close agreement with both tonometers (GAT versus Tonopachy-NC: -3.84 to 3.96 mmHg; Goldmann versus Canon TX-10: -4.75 to 4.07 mmHg). Tonopachy-C readings differed significantly from Goldmann (mean difference -0.96 mmHg, p = 0.001, LoA from -5.09 to 3.17). Coefficients of repeatability were ± 3.70, ± 3.14 and ± 3.33 mmHg for GAT, Tonopachy-NC and Tonopachy-C, respectively. Central corneal thickness measured with Tonopachy was 530.42 ± 34.96 μm. There was a significant correlation between central corneal thickness and IOP for all tonometers except Tonopachy-C. Reasonable agreement was observed between the Goldmann and Tonopachy. This instrument provides reliable and repeatable IOP

Noncontact fatigue crack evaluation using thermoelastic

Energy Technology Data Exchange (ETDEWEB)

Kim, Ji Min; An, Yun Kyu; Sohn, Hoon [KAIST, Daejeon (Korea, Republic of)

2012-12-15

This paper proposes a noncontact thermography technique for fatigue crack evaluation under a cyclic tensile loading. The proposed technique identifies and localizes an invisible fatigue crack without scanning, thus making it possible to instantaneously evaluate an incipient fatigue crack. Based on a thermoelastic theory, a new fatigue crack evaluation algorithm is proposed for the fatigue crack tip localization. The performance of the proposed algorithm is experimentally validated. To achieve this, the cyclic tensile loading is applied to a dog bone shape aluminum specimen using a universal testing machine, and the corresponding thermal responses induced by thermoelastic effects are captured by an infrared camera. The test results confirm that the fatigue crack is well identified and localized by comparing with its microscopic images.

Clinical comparison of the XPERT non-contact tonometer and the conventional Goldmann applanation tonometer.

Science.gov (United States)

Hansen, M K

1995-04-01

Intraocular pressure (IOP) in the right eye of 113 patients was measured with one XPERT NCT air-puff non-contact tonometer (XPERT) and compared with IOP measured with one Goldmann applanation tonometer (GAT). Precision of the methods was judged by variance analysis, indicating that GAT was slightly more precise than XPERT. The slope of the linear relationship between the methods did not differ significantly from 1.0. Mean difference between the methods was 0.92 mmHg, XPERT measuring lower than GAT, p = 0.00017. The intra-individual difference between methods ranged from -8.00 to 8.67 mmHg, and standard deviation (SD) of differences was 2.52 mmHg. The 95% limits of agreement between the two methods were -5.85 to 4.01 mmHg. The SD of differences is of approximately the same size as previous XPERT vs GAT as well as previous GAT vs GAT studies.

Stress and strain measurements in solids

International Nuclear Information System (INIS)

Askegaard, V.

1978-01-01

A design basis is given for stress- and strain cells to be used in a solid either externally loaded or with a stressfree strain field (for example shrinkage). A stress- and a strain cell has been designed for use in granular materials. Calibration tests show either good or reasonably good correspondance with calculated values. (orig.) [de

Non-contacting "snubber bearing" for passive magnetic bearing systems

Science.gov (United States)

Post, Richard F

2017-08-22

A new non-contacting magnetic "snubber" bearing is provided for application to rotating systems such as vehicular electromechanical battery systems subject to frequent accelerations. The design is such that in the equilibrium position the drag force of the snubber is very small (milliwatts). However in a typical case, if the rotor is displaced by as little as 2 millimeters a large restoring force is generated without any physical contact between the stationary and rotating parts of the snubber bearing.

Temperature and strain measurements in concrete using micro-structure optical fiber sensors

Energy Technology Data Exchange (ETDEWEB)

Areias, Lou [EURIDICE/SCK - CEN, Mol (Belgium); Vrije Univ. Brussels (Belgium); Geernaert, Thomas; Sulejmani, Sanne [Vrije Univ. Brussels (Belgium); and others

2015-07-01

A recent test carried out to evaluate the construction feasibility of the Belgian supercontainer concept incorporated several types of state-of-the-art sensors and innovative monitoring techniques, including the use of different types of optical fiber sensors. One of these is a relatively new type of sensor developed by the Brussels Photonics Team (B-PHOT) of the Vrije Universiteit Brussel. The sensor uses highly birefringent microstructured optical fibers equipped with fiber Bragg gratings (MOFBGs) sensors. They were embedded in a carbon-fiber reinforced composite plate to provide protection against the concrete's highly alkaline environment, facilitate installation in the concrete mould and allow the transfer of strain onto the fiber. The double reflection spectrum of the MOFBGs allows monitoring strain and temperature simultaneously. This paper presents results of temperature and strain measurements obtained with MOFBG sensors during a {sup 1}/{sub 2}-scale test performed in 2013. The results compare well with similar measurements obtained using conventional thermocouples and vibrating wire strain gauges.

Fast recovery strain measurements in a nuclear test environment

International Nuclear Information System (INIS)

Kitchen, W.R.; Nauman, W.J.; Vollmer, D.W.

1979-01-01

The recovery of early-time (50 μs or less) strain gage data on structural response experiments in underground nuclear tests has been a continuing problem for experimenters at the Nevada Test Site. Strain measurement is one of the primary techniques used to obtain experimental data for model verification and correlation with predicted effects. Peak strains generally occur within 50 to 100 μs of the radiation exposure. Associated with the exposure is an intense electromagnetic impulse that produces potentials of kilovolts and currents of kiloamperes on the experimental structures. For successful operation, the transducer and associated recording system must recover from the initial noise overload and accurately track the strain response within about 50 μs of the nuclear detonation. A gaging and fielding technique and a recording system design that together accomplish these objectives are described. Areas discussed include: (1) noise source model; (2) experimental cassette design, gage application, grounding, and shielding; (3) cable design and shielding between gage and recorder; (4) recorder design including signal conditioner/amplifier, digital encoder, buffer memory, and uphole data transmission; and (5) samples of experimental data

Strain measurements during pressurized thermal shock experiment

International Nuclear Information System (INIS)

Tarso Vida Gomes, P. de; Julio Ricardo Barreto Cruz; Tanius Rodrigues Mansur; Denis Henrique Bianchi Scaldaferri; Miguel Mattar Neto

2005-01-01

For the life extension of nuclear power plants, the residual life of most of their components must be evaluated along all their operating time. Concerning the reactor pressure vessel, the pressurized thermal shock (PTS) is a very important event to be considered. For better understanding the effects of this kind of event, tests are made. The approach described here consisted of building a simplified in-scale physical model of the reactor pressure vessel, submitting it to the actual operating temperature and pressure conditions and provoking a thermal shock by means of cold water flow in its external surface. To conduct such test, the Nuclear Technology Development Center (CDTN) has been conducting several studies related to PTS and has also built a laboratory that has made possible the simulation of the PTS loading conditions. Several cracks were produced in the external surface of the reactor pressure vessel model. Strain gages were fixed by means of electrical discharge welding over the cracks regions in both external and internal surfaces. The temperature was monitored in 10 points across the vessel wall. The internal pressure was manually controlled and monitored using a pressure transducer. Two PTS experiments were conducted and this paper presents the strain measurement procedures applied to the reactor pressure vessel model, during the PTS, using strain gages experimental methodology. (authors)

Evaluation of resilient abutment components on measured strain using dynamic loading conditions.

Science.gov (United States)

Morton, D; Stanford, C M; Aquilino, S A

1998-07-01

Factors that affect transmission of strain from prostheses to bone may affect the long-term success of loaded implants. Current in vitro models are theoretically predictive (finite element modeling) or facsimile (photoelastic) in nature. A more clinically relevant in vitro model for strain evaluation should be investigated. This study attempted: (1) to validate a human cadaver bone model for vitro measurement of cortical bone strain, and (2) to evaluate the effect on cortical strain measurements of a resilient plastic component incorporated within a titanium implant in response to variable dynamic loading. Two IMZ (Interpore International) abutment alternatives were used: the titanium Abutment Complete and the polyoxymethylene Intra-mobile Element. The model system consisted of two implants placed in unfixed human cadaver ulna bone to simulate an implant bound edentulous region. Four biaxial rosette strain gauges simultaneously recorded cortical bone strain immediately mesial and distal to each implant. During experimentation a simulated prosthetic framework supported by either titanium or polyoxymethylene abutments was dynamically loaded 6 min from the terminal abutment along a cantilever extension. Cyclic nominal peak loads were applied with a materials testing machine at 20-N intervals from 20 to 200 N at a crosshead speed of 5 mm/minute. The protocol allowed frequency of load application to vary. A Newtonian linear correlation (r2 > or = 0.98) between load application and strain output was determined for each gauge position except for the terminal gauge located opposite the cantilever. Cortical strains recorded were within reported physiologic ranges involved in bone modeling and remodeling. Further, the polyoxymethylene abutment components did not result in reduction of peak microstrain at any gauge position. The Intra-mobile Element abutments, however, did increase the time required to complete 10 loading cycles when compared with the titanium Abutment

Internal strain measurement using pulsed neutron diffraction at LANSCE

International Nuclear Information System (INIS)

Goldstone, J.A.; Bourke, M.A.M.; Shi, N.

1994-01-01

The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction in the only technique that can make nondestructive measurements in the interior of components. By recording the change in crystalline lattice spacings, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all lattice reflections are recorded in each measurement, which allows for easy examination of heterogeneous materials such as metal matrix composites. Measurements made at the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) demonstrate the potential at pulsed sources for in-situ stress measurements at ambient and elevated temperatures

Up-taper-based Mach-Zehnder interferometer for temperature and strain simultaneous measurement.

Science.gov (United States)

Kang, Zexin; Wen, Xiaodong; Li, Chao; Sun, Jiang; Wang, Jing; Jian, Shuisheng

2014-04-20

A novel all-fiber sensing configuration for simultaneous measurements of temperature and strain based on the up-taper Mach-Zehnder interferometer (MZI) with an in-line embedded fiber Bragg grating (FBG) is proposed and experimentally demonstrated. This configuration consists of two up-tapers fabricated by an excessive fusion splicing method and a short segment of inscribed FBG. Due to the different responses of the up-taper MZI and the FBG to the uniform variation of temperature and strain, the simultaneous measurement for these two variables could be achieved by real-time monitoring the transmission spectrum. For 0.01 nm wavelength resolution, a resolution of 0.311°C in temperature can be achieved, and the average strain resolution is 10.07 με.

Design and Testing of the Strain Transducer for Measuring Deformations of Pipelines Operating in the Mining-deformable Ground Environment

Directory of Open Access Journals (Sweden)

Gawedzki Waclaw

2015-10-01

Full Text Available Design and laboratory test results of the strain transducer intended for monitoring and assessing stress states of pipelines sited in mining areas are presented in this paper. This transducer allows measuring strains of pipelines subjected to external forces - being the mining operations effect. Pipeline strains can have a direct influence on a tightness loss and penetration of the transported fluid into the environment. The original strain gauge transducer was proposed for performing measurements of strains. It allows measuring circumferential strains and determining the value and direction of the main longitudinal strain. This strain is determined on the basis of measuring component longitudinal strains originating from axial forces and the resultant bending moment. The main purpose of investigations was the experimental verification of the possibility of applying the strain transducer for measuring strains of polyethylene pipelines. The obtained results of the transducer subjected to influences of tensile and compression forces are presented and tests of relaxation properties of polyethylene are performed.

Knee Kinematics During Noncontact Anterior Cruciate Ligament Injury as Determined From Bone Bruise Location.

Science.gov (United States)

Kim, Sophia Y; Spritzer, Charles E; Utturkar, Gangadhar M; Toth, Alison P; Garrett, William E; DeFrate, Louis E

2015-10-01

The motions causing noncontact anterior cruciate ligament (ACL) injury remain unclear. Tibiofemoral bone bruises are believed to be the result of joint impact near the time of ACL rupture. The locations and frequencies of these bone bruises have been reported, but there are limited data quantifying knee position and orientation near the time of injury based on these contusions. Knee position and orientation near the time of noncontact ACL injury include extension and anterior tibial translation. Descriptive laboratory study. Magnetic resonance images of 8 subjects with noncontact ACL injuries were acquired within 1 month of injury and were subsequently analyzed. All subjects exhibited bruises on both the femur and tibia in both medial and lateral compartments. The outer margins of bone and the bone bruise surfaces were outlined on each image to create a 3-dimensional model of each subject's knee in its position during magnetic resonance imaging (MRI position). Numerical optimization was used to maximize overlap of the bone bruises on the femur and tibia and to predict the position of injury. Flexion angle, valgus orientation, internal tibial rotation, and anterior tibial translation were measured in both the MRI position and the predicted position of injury. Differences in kinematics between the MRI position, which served as an unloaded reference, and the predicted position of injury were compared by use of paired t tests. Flexion angle was near full extension in both the MRI position and the predicted position of injury (8° vs 12°; P = .2). Statistically significant increases in valgus orientation (5°; P = .003), internal tibial rotation (15°; P = .003), and anterior tibial translation (22 mm; P injury relative to the MRI position. These results suggest that for the bone bruise pattern studied, landing on an extended knee is a high risk for ACL injury. Extension was accompanied by increased anterior tibial translation (22 mm), internal tibial rotation (15�

Three-Axis Distributed Fiber Optic Strain Measurement in 3D Woven Composite Structures

Science.gov (United States)

Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

2013-01-01

Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading. Keywords: fiber optic, distributed strain sensing, Rayleigh scatter, optical frequency domain reflectometry

In-situ measurement of texture and elastic strains with HIPPO-CRATES

International Nuclear Information System (INIS)

Hartig, Ch.; Vogel, S.C.; Mecking, H.

2006-01-01

In this paper, the micromechanical interaction between constituents of a metallic material during elastic and plastic deformation are analyzed by comparing experimental results with modeling predictions. This comparison aims at determining the locally acting internal stresses, the spatial distribution of strains and the rules allowing deriving the macroscopic behavior of the material from the behavior of its microscopic constituents. We report the application of a new deformation apparatus CRATES, which allows measuring texture and crystal lattice spacings, and from these crystal lattice strains, using neutron diffraction. From the in-situ measured elastic lattice strains ε hkl the corresponding local stresses can be derived. The deformation apparatus allows uni-axial tensile or compressive deformation up to 100 kN and is specifically designed for use in the HIPPO neutron time-of-flight diffractometer. In this paper, we report initial results on an iron-copper model system (Fe100, Fe33Cu67, Fe67Cu33, vol.%) and commercial magnesium alloys (Mg-AZ31 and Mg-AZ80). Finite element calculations using a crystal-plastic constitutive law, allowing for shear and hardening of crystallographic slip-systems, were used for the interpretation of the measurements

Detection of subclinical keratoconus through non-contact tonometry and the use of discriminant biomechanical functions.

Science.gov (United States)

Peña-García, Pablo; Peris-Martínez, Cristina; Abbouda, Alessandro; Ruiz-Moreno, José M

2016-02-08

The purpose of the present study was to develop a discriminant function departing from the biomechanical parameters provided by a non-contact tonometer (Corvis-ST, Oculus Optikgeräte, Wetzlar, Germany) to distinguish subclinical keratoconus from normal eyes. 212 eyes (120 patients) were divided in two groups: 184 healthy eyes of 92 patients aged 32.99 ± 7.85 (21-73 years) and 28 eyes of 28 patients aged 37.79 ± 14.21 (17-75 years) with subclinical keratoconus. The main outcome measures were age, sex, intraocular pressure (IOP), corneal central thickness (CCT) and other specific biomechanical parameters provided by the tonometer. Correlations between all biomechanical parameters and the rest of variables were evaluated. The biomechanical measures were corrected in IOP and CCT (since these variable are not directly related with the corneal structure and biomechanical behavior) to warrant an accurate comparison between both types of eyes. Two discriminant functions were created from the set of corrected variables. The best discriminant function created depended on three parameters: maximum Deformation Amplitude (corrected in IOP and CCT), First Applanation time (corrected in CCT) and CCT. Statistically significant differences were found between groups for this function (p=2·10(-10); Mann-Withney test). The area under the Receiving Operating Characteristic was 0.893 ± 0.028 (95% confidence interval 0.838-0.949). Sensitivity and specificity were 85.7% and 82.07% respectively. These results show that the use of biomechanical parameters provided by non-contact tonometry, previous normalization, combined with the theory of discriminant functions is a useful tool for the detection of subclinical keratoconus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Strain Measurements of Chondrules and Refraction Inclusion in Allende

Science.gov (United States)

Tait, Alastair W.; Fisher, Kent R.; Simon, Justin I.

2013-01-01

This study uses traditional strain measurement techniques, combined with X-ray computerized tomography (CT), to evaluate petrographic evidence in the Allende CV3 chondrite for preferred orientation and to measure strain in three dimensions. The existence of petrofabrics and lineations was first observed in carbonaceous meteorites in the 1960's. Yet, fifty years later only a few studies have reported that meteorites record such features. Impacts are often cited as the mechanism for this feature, although plastic deformation from overburden and nebular imbrication have also been proposed. Previous work conducted on the Leoville CV3 and the Parnallee LL3 chondrites, exhibited a minimum uniaxial shortening of 33% and 21%, respectively. Petrofabrics in Allende CV3 have been looked at before; previous workers using Electron Back Scatter Diffraction (EBSD) found a major-axis alignment of olivine inside dark inclusions and an "augen"-like preferred orientation of olivine grains around more competent chondrules

Application of electronic speckle-pattern interferometry to measure in-plane thermal displacement in flip-chip packages

International Nuclear Information System (INIS)

Lee, Baik-Woo; Jang, Woosoon; Kim, Dong-Won; Jeong, Jeung-hyun; Nah, Jae-Woong; Paik, Kyung-Wook; Kwon, Dongil

2004-01-01

Electronic speckle-pattern interferometry (ESPI) was applied for noncontact, real-time evaluation of thermal deformation in a flip-chip package. The spatial resolution of ESPI was increased to submicron scale by magnifying the areas studied in order to measure the deformation of such small-scale components as the solder in the flip-chip package. Thermal deformation in the horizontal and vertical directions around the solder joints was measured as two-dimensional mappings during heating from 25 to 125 deg. C. ESPI was successful in obtaining information on the complicated deformation field around the solder joints. Furthermore, the shear strain could also be calculated using the measured thermal deformation around each solder joint. The applicability of ESPI to flip-chip packages was verified by comparing the ESPI results with those of finite-element analysis (FEA)

Measuring strain and rotation fields at the dislocation core in graphene

Science.gov (United States)

Bonilla, L. L.; Carpio, A.; Gong, C.; Warner, J. H.

2015-10-01

Strain fields, dislocations, and defects may be used to control electronic properties of graphene. By using advanced imaging techniques with high-resolution transmission electron microscopes, we have measured the strain and rotation fields about dislocations in monolayer graphene with single-atom sensitivity. These fields differ qualitatively from those given by conventional linear elasticity. However, atom positions calculated from two-dimensional (2D) discrete elasticity and three-dimensional discrete periodized Föppl-von Kármán equations (dpFvKEs) yield fields close to experiments when determined by geometric phase analysis. 2D theories produce symmetric fields whereas those from experiments exhibit asymmetries. Numerical solutions of dpFvKEs provide strain and rotation fields of dislocation dipoles and pairs that also exhibit asymmetries and, compared with experiments, may yield information on out-of-plane displacements of atoms. While discrete theories need to be solved numerically, analytical formulas for strains and rotation about dislocations can be obtained from 2D Mindlin's hyperstress theory. These formulas are very useful for fitting experimental data and provide a template to ascertain the importance of nonlinear and nonplanar effects. Measuring the parameters of this theory, we find two characteristic lengths between three and four times the lattice spacings that control dilatation and rotation about a dislocation. At larger distances from the dislocation core, the elastic fields decay to those of conventional elasticity. Our results may be relevant for strain engineering in graphene and other 2D materials of current interest.

Comparison of three methods of tonometry in normal subjects: Goldmann applanation tonometer, non-contact airpuff tonometer, and Tono-Pen XL

OpenAIRE

Yilmaz, Ihsan; Altan,Cigdem; Aygit,Ebru Demet; Alagoz,Cengiz; Baz,Okkes; Ahmet,Sibel; Urvasizoglu,Semih; Yaşa,Dilek; Demirok,Ahmet

2014-01-01

Ihsan Yilmaz, Cigdem Altan, Ebru Demet Aygit, Cengiz Alagoz, Okkes Baz, Sibel Ahmet, Semih Urvasizoglu, Dilek Yasa, Ahmet DemirokBeyoglu Eye Training and Research Hospital, Istanbul, TurkeyObjective: We aimed to compare intraocular pressure (IOP) measurements via three different tonometers: the Goldmann applanation tonometer (GAT), the Tono-Pen® XL (TPXL), and a non-contact airpuff tonometer (NCT).Methods: This was a cross-sectional study of 200 eyes from 20...

Pressure potential and stability analysis in an acoustical noncontact transportation

Science.gov (United States)

Li, J.; Liu, C. J.; Zhang, W. J.

2017-01-01

Near field acoustic traveling wave is one of the most popular principles in noncontact manipulations and transportations. The stability behavior is a key factor in the industrial applications of acoustical noncontact transportation. We present here an in-depth analysis of the transportation stability of a planar object levitated in near field acoustic traveling waves. To more accurately describe the pressure distributions on the radiation surface, a 3D nonlinear traveling wave model is presented. A closed form solution is derived based on the pressure potential to quantitatively calculate the restoring forces and moments under small disturbances. The physical explanations of the effects of fluid inertia and the effects of non-uniform pressure distributions are provided in detail. It is found that a vibration rail with tapered cross section provides more stable transportation than a rail with rectangular cross section. The present study sheds light on the issue of quantitative evaluation of stability in acoustic traveling waves and proposes three main factors that influence the stability: (a) vibration shape, (b) pressure distribution and (c) restoring force/moment. It helps to provide a better understanding of the physics behind the near field acoustic transportation and provide useful design and optimization tools for industrial applications.

A study on non-contact ultrasonic technique for on-line inspection of CFRP

International Nuclear Information System (INIS)

Lee, Seung-Joon; Park, Won-Su; Lee, Joon-Hyun; Byun, Joon-Hyung

2007-01-01

The advantages of carbon fiber reinforced plastic materials (CFRP) are: they are light structure materials, they have corrosion resistance, and higher specific strength and elasticity. The recently developed 3-dimentional fiber placement system is able to produce a more complex and various shaped structures due to less limitations of a product shape according to the problem in conventional fabrication process. This fiber placement system stacks the narrow prepreg tape on the mold according to the designed sequence and thickness. Non-destructive evaluation was rquired for these composites to evaluate changes in strength caused by defects such as delamination and porosity. Additionally, the expectent quality should be satisfied for the high cost fabrication process using the fiber placement system. Therefore, an on line non-destructive evaluation system is required and real-time complement is needed when the defects are detected [1]. Defect imaging by the ultrasonic C-scan method is a useful technique for defect detection in CFRP. However, the conventional ultrasonic C-scan technique cannot be applied during the fabrication process because the test piece should be immersed into the water. Therefore, non-contact ultrasonic techniques should be applied during the fabricating process. For the development of non-contact ultrasonic techniques available in non-destructive evaluation of CFRP, a recent laser-generated ultrasonic technique and an air-coupled transducer that transmit and receive ultrasounds in the air are studied [2-3]. In this study, generating and receiving techniques of laser-generated ultrasound and the characteristics of received signals upon the internal defects of CFRO were studied for non-contact inspection

Noncontact tomography and a pH-sensitive nanocomposite for monitoring osseointegrated prosthesis interfaces

Science.gov (United States)

Gupta, Sumit; Loh, Kenneth J.

2017-04-01

The main objective of this research is to develop a noncontact and noninvasive method for monitoring infections at the interface of human tissue and osseointegrated prostheses. The technique used here is centered on the theory of a noncontact permittivity imaging technique known as electrical capacitance tomography (ECT). This work is divided into two main parts. First, an ECT electrical permittivity reconstruction software and hardware system was developed. Second, a carbon nanotube-polyaniline nanocomposite thin film was designed and fabricated such that its electrical permittivity is sensitive to pH stimuli. The dielectric properties of this thin film were characterized as it was exposed to different pH buffer solutions. It is envisioned that osseointegrated implants can be pre-coated with the pH-sensitive nanocomposite prior to implant. When infection occurs and alters the local pH of tissue at the human-prosthesis interface, the dielectric property of the film would change accordingly. Then, ECT can interrogate the cross-section of the human limb and reconstruct its permittivity distribution, revealing localized changes in permittivity due to infection. To validate this concept, a prosthesis phantom was coated with the nanocomposite pH sensor and then immersed in different pH buffer solutions. ECT was conducted, and the results showed that the magnitude and location of subsurface, localized, pH changes could be detected. In general, noncontact tomography coupled with stimuliresponsive thin films could pave way for new modalities of noninvasive human body imaging, in particular, for patients with osseointegrated implants and prostheses.

Changes in intraocular pressure values measured with noncontact tonometer (NCT), ocular response analyzer (ORA) and corvis scheimpflug technology tonometer (CST) in the early phase after small incision lenticule extraction (SMILE).

Science.gov (United States)

Shen, Yang; Su, Xiangjian; Liu, Xiu; Miao, Huamao; Fang, Xuejun; Zhou, Xingtao

2016-11-18

Corneal biomechanical properties are always compromised after corneal refractive surgeries thus leading to underestimated intraocular pressure (IOP) that complicates the management of IOP. We investigated the changes in postoperative baseline of IOP values measured with noncontact tonometer (NCT), ocular response analyzer (ORA) and corvis scheimpflug technology (CST) in the early phase after small incision lenticule extraction (SMILE). Twenty-two eyes (-6.76 ± 1.39D) of 22 moderate and high myopes, (28.36 ± 7.14 years, 12 male and 10 female) were involved in this prospective study. IOP values were measured using a non-contact tomometer (NCT-IOP), an ocular response analyzer (corneal-compensated IOP, IOPcc and Goldmann-correlated IOP, IOPg) and a Corvis scheimpflug technology tonometer (CST-IOP) preoperatively, at 20 min and 24 h, postoperatively. Repeated measures analysis of variance (RM-ANOVA), Pearson's correlation analysis and multiple linear regression models (stepwise) were performed. Cut-off P values were 0.05. Except for IOPcc, NCT-IOP, IOPg, and CST-IOP values significantly decreased after SMILE procedure (All P values 0.05). Multiple linear regression models (stepwise) showed that the practical post-operative IOP value was the main predictor of the theoretical post-operative NCT-IOP, IOPcc and IOPg values (all P values <0.001). The postoperative applanation time 1 (AT1) value (B = 8.079, t = 4.866, P < 0.001), preoperative central corneal thickness (CCT) value (B = 0.035, t = 2.732, P = 0.014) and postoperative peak distance (PD) value (B = 0.515, t = 2.176, P = 0.043) were the main predictors of the theoretical post-operative CST-IOP value. IOP values are underestimated when assessed after SMILE by using NCT-IOP, IOPg and CST-IOP. The practical postoperative IOPcc value and theoretical post-operative CST-IOP value may be more preferable for IOP assessment in the early phase after SMILE. Current Controlled

Comparison of central corneal thickness with four noncontact devices: An agreement analysis of swept-source technology.

Science.gov (United States)

Ozyol, Erhan; Özyol, Pelin

2017-06-01

The purpose of this study was to compare the central corneal thickness (CCT) measurements of four noncontact devices in healthy eyes. In a sample of 45 healthy controls, CCT was measured using an optical biometer (IOLMaster 700) based on swept-source optical coherence tomography (SS-OCT), high-resolution rotating Scheimpflug camera system (Pentacam HR), spectral-domain OCT (SD-OCT) device with an anterior segment module (Spectralis), and noncontact pachymetry (NCP) device (Topcon TRK-2P). Agreement among the devices was analyzed using mean differences (i.e., bias) and Bland-Altman analysis with 95% limits of agreement (LoA). Mean CCT measurements were 537.5 ± 47.5 μm for SS-OCT optical biometer, 532.3 ± 43.8 μm for Scheimpflug system, 521.3 ± 44.7 μm for SD-OCT device, and 518.0 ± 43.1 μm for NCP (P < 0.001). The SD-OCT device and NCP showed the closest agreement, with a bias of 2.6 μm (95% LoA, -3.6-8.8 μm), whereas the SS-OCT optical biometer and NCP showed the least agreement, with a bias of 18.7 μm (95% LoA, -2.1-39.5 μm). Bias was 16.1 μm (95% LoA, -3.1-35.3 μm) for SS-OCT optical biometer and SD-OCT, 5.1 μm (95% LoA, -6.8-17.0 μm) for SS-OCT optical biometer and Scheimpflug system, 10.9 μm (95% LoA, -15.1-36.9 μm) for SD-OCT device and Scheimpflug system, and 13.6 μm (95% LoA, -5-32.2 μm) for Scheimpflug system and NCP. SS-OCT optical biometer overestimates CCT measurements compared to Scheimpflug system, SD-OCT device, and NCP. Given mean differences and range variations in CCT measurements between devices, SS-OCT optical biometer and Scheimpflug system are interchangeable as are SD-OCT and NCP.

Neutron-diffraction measurement of the evolution of strain for non-uniform plastic deformation

CERN Document Server

Rogge, R B; Boyce, D

2002-01-01

Neutrons are particularly adept for the validation of modeling predictions of stress and strain. In recent years, there has been a significant effort to model the evolution of both the macroscopic stresses and the intergranular stress during plastic deformation. These have had broad implications with regard to understanding the evolution of residual stress and to diffraction-based measurements of strain. Generally the modeling and associated measurements have been performed for simple uniaxial tension, leaving questions with regard to plastic deformation under multi-axial stress and non-uniform stress. Extensive measurements of the strain profile across a plastic hinge for each of a series of loading and unloading cycles to progressively higher degrees of plastic deformation are presented. These measurements are used to assess multiple-length-scale finite-element modeling (FEM) of the plastic hinge, in which the elements will range in size from single crystallites (as used in successful simulations of uniaxia...

Neutron-diffraction measurement of the evolution of strain for non-uniform plastic deformation

International Nuclear Information System (INIS)

Rogge, R.B.; Dawson, P.R.; Boyce, D.

2002-01-01

Neutrons are particularly adept for the validation of modeling predictions of stress and strain. In recent years, there has been a significant effort to model the evolution of both the macroscopic stresses and the intergranular stress during plastic deformation. These have had broad implications with regard to understanding the evolution of residual stress and to diffraction-based measurements of strain. Generally the modeling and associated measurements have been performed for simple uniaxial tension, leaving questions with regard to plastic deformation under multi-axial stress and non-uniform stress. Extensive measurements of the strain profile across a plastic hinge for each of a series of loading and unloading cycles to progressively higher degrees of plastic deformation are presented. These measurements are used to assess multiple-length-scale finite-element modeling (FEM) of the plastic hinge, in which the elements will range in size from single crystallites (as used in successful simulations of uniaxial tension) to macroscopic elements (as typically used in FEM simulations). (orig.)

Distributed strain measurement with polymer optical fibers integrated into multifunctional geotextiles

Science.gov (United States)

Liehr, Sascha; Lenke, Philipp; Krebber, Katerina; Seeger, Monika; Thiele, Elke; Metschies, Heike; Gebreselassie, Berhane; Münich, Johannes Christian; Stempniewski, Lothar

2008-04-01

Fiber optic sensors based on polymer optical fibers (POF) have the advantage of being very elastic and robust at the same time. Unlike silica fibers, standard PMMA POF fibers can be strained to more than 40% while fully maintaining their light guiding properties. We investigated POF as a distributed strain sensor by analysing the backscatter increase at the strained section using the optical time domain reflectometry (OTDR) technique. This sensing ability together with its high robustness and break-down strain makes POF well-suited for integration into technical textiles for structural health monitoring purposes. Within the European research project POLYTECT (Polyfunctional textiles against natural hazards) technical textiles with integrated POF sensors, among others sensors are being developed for online structural health monitoring of geotechnical structures. Mechanical deformation in slopes, dams, dikes, embankments and retrofitted masonry structures is to be detected before critical damage occurs. In this paper we present the POF strain sensor properties, reactions to disturbing influences as temperature and bends as well as the results of the different model tests we conducted within POLYTECT. We further show the potential of perfluorinated graded-index POF for distributed strain sensing with increased spatial resolution and measurement lengths.

Simultaneous measurement of dynamic strain and temperature distribution using high birefringence PANDA fiber Bragg grating

Science.gov (United States)

Zhu, Mengshi; Murayama, Hideaki

2017-04-01

New approach in simultaneous measurement of dynamic strain and temperature has been done by using a high birefringence PANDA fiber Bragg grating sensor. By this technique, we have succeeded in discriminating dynamic strain and temperature distribution at the sampling rate of 800 Hz and the spatial resolution of 1 mm. The dynamic distribution of strain and temperature were measured with the deviation of 5mm spatially. In addition, we have designed an experimental setup by which we can apply quantitative dynamic strain and temperature distribution to the fiber under testing without bounding it to a specimen.

Assessment of strain and strain rate by two-dimensional speckle tracking in mice: comparison with tissue Doppler echocardiography and conductance catheter measurements.

Science.gov (United States)

Ferferieva, V; Van den Bergh, A; Claus, P; Jasaityte, R; La Gerche, A; Rademakers, F; Herijgers, P; D'hooge, J

2013-08-01

This study was designed in order to compare the strain and strain rate deformation parameters assessed by speckle tracking imaging (STI) with those of tissue Doppler imaging (TDI) and conductance catheter measurements in chronic murine models of left ventricular (LV) dysfunction. Twenty-four male C57BL/6J mice were assigned to wild-type (n = 8), myocardial infarction (n = 8) and transaortic constriction (n = 8) groups. Echocardiographic and conductance measurements were simultaneously performed at rest and during dobutamine infusion (5 µg/kg/min) in all animals 10 weeks post-surgery. The LV circumferential strain (Scirc) and the strain rate (SRcirc) were derived from grey scale and tissue Doppler data at frame rates of 224 and 375 Hz, respectively. Scirc and SRcirc by TDI/STI correlated well with the preload recruitable stroke work (PRSW) (r = -0.64 and -0.71 for TDI; r = -0.46 and -0.50 for STI, P < 0.05). Both modalities showed a good agreement with respect to Scirc and SRcirc (r = 0.60 and r = 0.63, P < 0.05). During stress, however, TDI-estimated Scirc and SRcirc values were predominantly higher than those measured by STI (P < 0.05). The similarity of Scirc and SRcirc measurements with respect to the STI/TDI data was examined by the Bland-Altman analysis. In mice, the STI- and TDI-derived strain and strain rate deformation parameters relate closely to intrinsic myocardial function. At low heart rate-to-frame rate ratios (HR/FR), both STI and TDI are equally acceptable for assessing the LV function non-invasively in these animals. At HR/FR (e.g. dobutamine challenge), however, these methods cannot be used interchangeably as STI underestimates S and SR at high values.

A method of non-contact reading code based on computer vision

Science.gov (United States)

Zhang, Chunsen; Zong, Xiaoyu; Guo, Bingxuan

2018-03-01

With the purpose of guarantee the computer information exchange security between internal and external network (trusted network and un-trusted network), A non-contact Reading code method based on machine vision has been proposed. Which is different from the existing network physical isolation method. By using the computer monitors, camera and other equipment. Deal with the information which will be on exchanged, Include image coding ,Generate the standard image , Display and get the actual image , Calculate homography matrix, Image distort correction and decoding in calibration, To achieve the computer information security, Non-contact, One-way transmission between the internal and external network , The effectiveness of the proposed method is verified by experiments on real computer text data, The speed of data transfer can be achieved 24kb/s. The experiment shows that this algorithm has the characteristics of high security, fast velocity and less loss of information. Which can meet the daily needs of the confidentiality department to update the data effectively and reliably, Solved the difficulty of computer information exchange between Secret network and non-secret network, With distinctive originality, practicability, and practical research value.

Measurement of body temperature in 300 dogs with a novel noncontact infrared thermometer on the cornea in comparison to a standard rectal digital thermometer.

Science.gov (United States)

Kreissl, Hannah; Neiger, Reto

2015-01-01

To assess the accuracy of obtaining body temperatures in dogs with a noncontact infrared thermometer (NCIT) on the cornea compared with a rectal digital thermometer (RDT). Prospective single center study. University teaching hospital. Three hundred dogs presented with low, normal, or high body temperatures. Three body temperature readings were measured by an RDT and by an NCIT on the cornea of the left eye by 2 investigators (experienced and inexperienced). Results obtained by the 2 methods were compared. Median body temperature measured by the experienced investigator with the RDT and the NCIT were 38.3°C (range 35.5°C-41.1°C; 95% CI: 38.2-38.4°C) and 37.7°C (35.9°C-40.1°C; 95% CI: 37.7°C-37.9°C), respectively. Measurement of RDT as well as of NCIT correlated well between both investigators (rRDT = 0.94; rNCIT = 0.82; respectively, P temperature correlated poorly (r = 0.43; P temperature >39.0°C) showed an area under the curve of 0.76. Mean discomfort score was significantly lower using NCIT compared to RDT measurement (P temperatures obtained by RDT and NCIT. The corneal NCIT measurement tends to underrecognize hypothermic and hyperthermic conditions. Although the use of the NCIT yields faster results and is significantly more comfortable for the dog than the RDT measurement, it cannot be recommended in dogs at this time. © Veterinary Emergency and Critical Care Society 2015.

Measurement of strain and strain relaxation in free-standing Si membranes by convergent beam electron diffraction and finite element method

International Nuclear Information System (INIS)

Gao, H.; Ikeda, K.; Hata, S.; Nakashima, H.; Wang, D.; Nakashima, H.

2011-01-01

Bridge-shaped free-standing Si membranes (FSSM), strained by low-pressure (LP) Si x N y , plasma-enhanced (PE) Si x N y and Si x Ge 1-x stressors, were measured by convergent beam electron diffraction (CBED) and the finite element method (FEM). The results of CBED show that, while the strain along the length of the FSSM is compressive in an LPSi x N y /Si sample, those along the length of the FSSM are tensile in PESi x N y /Si and Si x Ge 1-x /Si samples. The average absolute values of strains are different in FSSM with LPSi x N y , PESi x N y and Si x Ge 1-x as stressors. The FEM was used to compensate the results of CBED taking into account the strain relaxation in transmission electron microscopy (TEM) sample preparation. The FEM results give the strain properties in three dimensions, and are in good agreement with the results of CBED. There is approximately no strain relaxation along the length of FSSM, and the elastic strains along the other two axes in FSSM are partially relaxed by thinning down for the preparation of TEM samples.

Clinical evaluation of the new TGDc-01 "PRA" palpebral tonometer: comparison with contact and non-contact tonometry.

Science.gov (United States)

García Resúa, Carlos; Giráldez Fernández, Maria J; Cerviño Expósito, Alejandro; González Pérez, Javier; Yebra-Pimentel, Eva

2005-02-01

The TGDc-01 "PRA" (Ryazan State Instrument, Ryazan, Russia) tonometer is a new portable small-sized tonometer that measures intraocular pressure (IOP) through the eyelid. The purpose of this study is to assess the repeatability of the TGDc-01 IOP measurements by comparing them against those obtained with Goldmann tonometer and with those from Perkins applanation tonometer, Xpert (Reichert, Depew, NY) noncontact tonometer, and Tono-Pen XL (Medtronic Solan, Jacksonville, FL) digital tonometer. Fifty-eight right eyes of 58 young subjects were measured with each of the tonometers. Noncontact tonometry was performed first, followed by Goldmann and Perkins applanation tonometer (in random order), digital Tono-Pen XL, and finally TGDc-01 tonometer (sitting and supine position). Correlation analysis was used to evaluate the relationship between the Goldmann tonometer and the remaining tonometers used in this study. Plotting the difference between the methods against mean was also done to compare the tonometers. The hypothesis of zero bias was examined by a paired t-test. The 95% limits of agreement (LoA) were also calculated. TGDc-01 showed no statistical difference between the IOP measurements obtained in sitting and supine positions. A poor relationship between the TGDc-01 and Goldmann tonometer was found (r = 0.173; p = 0.001). Although the mean differences between Goldmann and Tonopen XL, Xpert, and TGDc-01 IOP measurements were statistically significant, the wider 95% LoA was observed when comparing the Goldmann and TGDc-01 tonometers. Computation of the 95% LoA resulted in a wide bias range when comparing the TGDc-01 with all the tonometers used in this study. The TGDc-01 "PRA" tonometer was not comparable with the other techniques used in the study. The wide dispersion range of the values obtained shows low repeatability of the TGDc-01 for screening purposes. These results could be because of the technique of measurement and/or interindividual variables.

Electric Field Effects in RUS Measurements

Energy Technology Data Exchange (ETDEWEB)

Darling, Timothy W [Los Alamos National Laboratory; Ten Cate, James A [Los Alamos National Laboratory; Allured, Bradley [UNIV NEVADA, RENO; Carpenter, Michael A [CAMBRIDGE UNIV. UK

2009-09-21

Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material - a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the 'statistical residual' strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods.

Measurement of stress-strain behaviour of human hair fibres using optical techniques.

Science.gov (United States)

Lee, J; Kwon, H J

2013-06-01

Many studies have presented stress-strain relationship of human hair, but most of them have been based on an engineering stress-strain curve, which is not a true representation of stress-strain behaviour. In this study, a more accurate 'true' stress-strain curve of human hair was determined by applying optical techniques to the images of the hair deformed under tension. This was achieved by applying digital image cross-correlation (DIC) to 10× magnified images of hair fibres taken under increasing tension to estimate the strain increments. True strain was calculated by summation of the strain increments according to the theoretical definition of 'true' strain. The variation in diameter with the increase in longitudinal elongation was also measured from the 40× magnified images to estimate the Poisson's ratio and true stress. By combining the true strain and the true stress, a true stress-strain curve could be determined, which demonstrated much higher stress values than the conventional engineering stress-strain curve at the same degree of deformation. Four regions were identified in the true stress-strain relationship and empirical constitutive equations were proposed for each region. Theoretical analysis on the necking condition using the constitutive equations provided the insight into the failure mechanism of human hair. This analysis indicated that local thinning caused by necking does not occur in the hair fibres, but, rather, relatively uniform deformation takes place until final failure (fracture) eventually occurs. © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Noncontact ultrasonic nondestructive evaluation/inspection using laser generation and air coupled transducer

International Nuclear Information System (INIS)

Jhang, Kyung Young; Kim, Hong Joon; Cemiglia, Donatella; Djordjevic, Boro

2001-01-01

Ultrasonic MDE/I methods have been demonstrated as very effective tool in characterization of cracks and structural defects such as bond-line failures. Most of the ultrasonic testing is performed using conventional contact ultrasonic transducers that cannot be readily adapted to automation and field application. However, for large area inspection contact type is time consuming and as a result, it is important to develop a rapid and more efficient ultrasonic technique. In this paper, laser generation and air-coupled detection of ultrasound is proposed as a solution of non-contact method with no requirement of a coupling medium, and the bond quality of adhesively bonded and riveted aluminum lap splice joints is investigated as an application. A Q-switched Nd:YAG laser and a periodic transmission mask are used to generate a selected Lamb mode. The experimental show that multi-line laser source produces significant directed ultrasound and that the presence of defects can be detected reliably from the attenuation of signal amplitude. These results demonstrate that the proposed technique is well suitable and flexible for non-contact NDE/I applications.

Non-contact test of coating by means of laser-induced ultrasonic excitation and holographic sound representation

International Nuclear Information System (INIS)

Crostack, H.A.; Pohl, K.Y.; Radtke, U.

1991-01-01

In order to circumvent the problems of introducing and picking off sound, which occur in conventional ultrasonic testing, a completely non-contact test process was developed. The ultrasonic surface wave required for the test is generated without contact by absorption of laser beams. The recording of the ultrasound also occurs by a non-contact holographic interferometry technique, which permits a large scale representation of the sound. Using the example of MCrAlY and ZrO 2 layers, the suitability of the process for testing thermally sprayed coatings on metal substrates is identified. The possibilities and limits of the process for the detection and description of delamination and cracks are shown. (orig.) [de

Design of triaxial test with controlled suction: measure of strain

International Nuclear Information System (INIS)

Gasc-Barbier, M.; Cosenza, Ph.; Ghoreychi, M.; Chanchole, S.; Cosenza, Ph.; Tessier, D.

2000-01-01

Experimental study of mechanical behavior of clayey materials under hygrometric condition is usually performed either on unloaded samples or by means of classical odometer tests used in soil mechanics. Such methods are not well adapted to hard deep clayey rocks with little deformability, porosity and permeability. Moreover, stress and strain tensors having a significant effect on hygro-mechanical behaviour and properties cannot be measured and investigated appropriately by classical tests. This is why a specific triaxial test was designed in which the sample is surrounded by a fiber glass tissue allowing air circulation and then by silicon on which confining pressure is applied. Thus, equilibrium between air and sample was reduced. Stress and strain tensors were also measured in time on the sample subjected to a mechanical loading and to a controlled suction. After presentation of the test, preliminary results are given. (authors)

Discussion on accuracy of weld residual stress measurement by neutron diffraction. Influence of strain free reference

International Nuclear Information System (INIS)

Suzuki, Hiroshi; Akita, Koichi

2012-01-01

It is required to evaluate a strain-free reference, α 0 , to perform accurate stress measurement using neutron diffraction. In this study, accuracy of neutron stress measurement was quantitatively discussed from α 0 evaluations on a dissimilar metal butt-weld between a type 304 austenitic stainless steel and an A533B low alloy ferritic steel. A strain-free standard specimen and a sliced specimen with 10 mm thickness taken from the dissimilar metal butt-weld were utilized. In the lattice constant evaluation using the standard specimen, average lattice constant derived from multiple hkl reflections was evaluated as the stress-free reference with cancelling out an intergranular strain. Comparing lattice constant distributions in each reflection with average lattice constant distribution in the standard specimen, αFe211 and γFe311 reflections were judged as a suitable reflection for neutron strain measurement to reduce intergranular strain effects. Residual stress distribution in the sliced specimen evaluated using α 0 measured here exhibited higher accuracy than that measured using strain gauges. On the other hand, α 0 distributions were evaluated using the sliced specimen under the plane-stress condition. Existence of slight longitudinal residual stresses near the weld center decreased accuracy of the α 0 evaluations, which means that it is required to optimize the thickness of the sliced specimen for accurate α 0 evaluation under plane strain condition. As a conclusion of this study, it was confirmed that procedures of accurate α 0 evaluation, optimization of the measurement condition, and multiple evaluations on the results play an important role to improve accuracy of the residual stress measurement using neutron diffraction. (author)

A non-contact high resolution piezoelectric film based sensor for monitoring breathing during sleep

Science.gov (United States)

Johnston, Robert; Nakano, Katsuya; Fujita, Kento; Misaki, Shinya; Fujii, Hiroyuki; Misaki, Yukinori

2017-07-01

Currently, research for measuring human breathing during sleep is actively being conducted into using technologies that include piezoelectric, ultrasonic, microwave and infrared rays. But various problems have led to not many practical applications. As such, it was decided to develop a PVDF (PolyVinylidene DiFluoride) based non-contact high resolution sensor for monitoring a subject's breathing as they sleep. Development of the high resolution respiration sensor was possible through the use of PVDF piezoelectric film and the development of a new sensor configuration. Although there was already an existing respiration sensor research resulting product available, is weak signal strength made it very sensitive to noise and difficult to measure respiration accurately. As such, complicated circuits and signal processing were needed. A new high resolution breathing sensor was developed with greater signal strength and with just the use of some simple circuits and signal processing, was able to accurately measure subject breathing. Also due to the greater signal strength, it became possible to measure both heart rate and respiration rate simultaneously.

Stress Measurement around a Circular Role in a Cantilever Beam under Bending Moment Using Strain Gage and Reflective Photoelasticity

Energy Technology Data Exchange (ETDEWEB)

Baek, Tae Hyun; Park, Tae Geun; Yang, Min Bok [Kunsan National University, Gunsan (Korea, Republic of)

2006-10-15

It is necessary to study on the stress concentration experimentally, which is the main reason to avoid mechanical dilapidation and failure, when designing a mechanical structure. Stress concentration factor of a specimen of cantilever beam with a circular hole in the center was measured using both strain gage and photoelastic methods in this paper. In strain-gage measurement, three strain gages along the line near a hole of the specimen were installed and maximum strain was extrapolated from three measurements. In photoelastic measurement, two methods were employed. First, the Babinet-Soleil compensation method was used to measure the maximum strain. Secondly, photoelastic 4-step phase shilling method was applied to observe the strain distribution around the hole. Measurements obtained by different experiments were comparable within the range of experimental error

Stress Measurement around a Circular Role in a Cantilever Beam under Bending Moment Using Strain Gage and Reflective Photoelasticity

International Nuclear Information System (INIS)

Baek, Tae Hyun; Park, Tae Geun; Yang, Min Bok

2006-01-01

It is necessary to study on the stress concentration experimentally, which is the main reason to avoid mechanical dilapidation and failure, when designing a mechanical structure. Stress concentration factor of a specimen of cantilever beam with a circular hole in the center was measured using both strain gage and photoelastic methods in this paper. In strain-gage measurement, three strain gages along the line near a hole of the specimen were installed and maximum strain was extrapolated from three measurements. In photoelastic measurement, two methods were employed. First, the Babinet-Soleil compensation method was used to measure the maximum strain. Secondly, photoelastic 4-step phase shilling method was applied to observe the strain distribution around the hole. Measurements obtained by different experiments were comparable within the range of experimental error

Estimation of strain from piezoelectric effect and domain switching in morphotropic PZT by combined analysis of macroscopic strain measurements and synchrotron X-ray data

International Nuclear Information System (INIS)

Kungl, Hans; Theissmann, Ralf; Knapp, Michael; Baehtz, Carsten; Fuess, Hartmut; Wagner, Susanne; Fett, Theo; Hoffmann, Michael J.

2007-01-01

Morphotropic PZT ceramics are State of the art materials for ferroelectric actuators. Essential performance parameters for these materials are strain and hysteresis. On a microscopic scale the strain provided by an electric field is due to two different mechanisms. The piezoelectric effect causes an elongation of the unit cells, whereas domain switching changes their crystallographic orientation by aligning the polarization axis towards the field direction. A method is outlined to estimate the contribution of the two mechanisms to total strain by combining macroscopic strain measurements and X-ray diffraction (XRD) data. Results from macroscopic measurements of remanent and unipolar strain with the corresponding data on texture, derived from in situ synchrotron radiation XRD patterns, are analyzed and evaluated by a semi-empirical approach. The method was applied to six morphotropic, LaSr doped PZT materials of different Zr/Ti ratios. Results are discussed with respect to the differences between the materials

Comparison of three methods of tonometry in normal subjects: Goldmann applanation tonometer, non-contact airpuff tonometer, and Tono-Pen XL

Directory of Open Access Journals (Sweden)

Yilmaz I

2014-06-01

Full Text Available Ihsan Yilmaz, Cigdem Altan, Ebru Demet Aygit, Cengiz Alagoz, Okkes Baz, Sibel Ahmet, Semih Urvasizoglu, Dilek Yasa, Ahmet DemirokBeyoglu Eye Training and Research Hospital, Istanbul, TurkeyObjective: We aimed to compare intraocular pressure (IOP measurements via three different tonometers: the Goldmann applanation tonometer (GAT, the Tono-Pen® XL (TPXL, and a non-contact airpuff tonometer (NCT.Methods: This was a cross-sectional study of 200 eyes from 200 patients. Right eyes of all patients were included in this study. IOP was measured via GAT, NCT, and TPXL by three physicians. Each physician used one of the tonometers. Measurements via the three devices were compared.Results: The mean IOP was 15.5±2.2 mmHg (range 10–22 with the GAT, 16.1±3.0 (range 9–25 with the TPXL, and 16.1±2.8 (range 10–26 with the NCT. Bland–Altman analysis showed that the mean difference between measurements from the NCT and the GAT was 0.6±2.3 mmHg. The mean difference between the TPXL and GAT measurements was 0.7±2.5 mmHg. The mean difference between the NCT and TPXL measurements was −0.02±3.0 mmHg. There was no significant difference between the groups according to a one-way analysis of variance (ANOVA test. P-values were 0.998 for NCT–TPXL, 0.067 for NCT–GAT, and 0.059 for TPXL–GAT.Conclusion: The NCT and TPXL provide IOP measurements comparable to those of the gold standard GAT in normotensive eyes.Keywords: tonometry, noncontact tonometry, Goldmann applanation tonometer, Tono-Pen

Strain measurements in a rotary engine housing

Science.gov (United States)

Lee, C. M.; Bond, T. H.; Addy, H. E.; Chun, K. S.; Lu, C. Y.

1989-01-01

The development of structural design tools for Rotary Combustion Engines (RCE) using Finite Element Modeling (FEM) requires knowledge about the response of engine materials to various service conditions. This paper describes experimental work that studied housing deformation as a result of thermal, pressure and mechanical loads. The measurement of thermal loads, clamping pressure, and deformation was accomplished by use of high-temperature strain gauges, thermocouples, and a high speed data acquisition system. FEM models for heat transfer stress analysis of the rotor housing will be verified and refined based on these experimental results.

Method for independent strain and temperature measurement in polymeric tensile test specimen using embedded FBG sensors

DEFF Research Database (Denmark)

Pereira, Gilmar Ferreira; McGugan, Malcolm; Mikkelsen, Lars Pilgaard

2016-01-01

to calculate independently the strain and temperature are presented in the article, together with a measurement resolution study. This multi-parameter measurement method was applied to an epoxy tensile specimen, tested in a unidirectional tensile test machine with a temperature controlled cabinet. A full......A novel method to obtain independent strain and temperature measurements using embedded Fibre Bragg Grating (FBG) in polymeric tensile test specimens is presented in this paper. The FBG strain and temperature cross-sensitivity was decoupled using two single mode FBG sensors, which were embedded...... of temperature, from 40 C to -10 C. The consistency of the expected theoretical results with the calibration procedure and the experimental validation shows that this proposed method is applicable to measure accurate strain and temperature in polymers during static or fatigue tensile testing. Two different...

Notch root strain measurement of WE43-T6 magnesium alloy using electronic speckle pattern interferometry

International Nuclear Information System (INIS)

Liew, H.L.; Ahmad, A.; Ramesh, S.; Purbolaksono, J.

2013-01-01

Highlights: • The use of ESPI for measuring total strains at the notch root of specimens. • Fine meshing in micron scale at the notch root regions. • The maximum elastic strain is shifted to be further away from the notch root tip. - Abstract: The notch root elasto-plastic strains of circumferentially grooved round specimen of cast magnesium WE43-T6 were experimentally measured using the electronic speckle pattern interferometry (ESPI) and numerically evaluated using the finite element analysis (FEA). The specimens have notch radii of 1.6 mm and 0.8 mm and an opening angle of 60°. The technique of ESPI showed its accuracy in measuring three-dimensional surface deformations on large negatively curved manifolds. The measured nominal stress for rupture is well beyond the ultimate strength, suggesting the existence of significant biaxial stress at the notch root region. The ESPI-based strains on the notch tips were shown to be in agreement with those evaluated by the FEA. The FEA also showed that the maximum elastic strain is shifted away from the notch root surface as the plastic strain is predominant

Quantitative analysis of tip-sample interaction in non-contact scanning force spectroscopy

International Nuclear Information System (INIS)

Palacios-Lidon, Elisa; Colchero, Jaime

2006-01-01

Quantitative characterization of tip-sample interaction in scanning force microscopy is fundamental for optimum image acquisition as well as data interpretation. In this work we discuss how to characterize the electrostatic and van der Waals contribution to tip-sample interaction in non-contact scanning force microscopy precisely. The spectroscopic technique presented is based on the simultaneous measurement of cantilever deflection, oscillation amplitude and frequency shift as a function of tip-sample voltage and tip-sample distance as well as on advanced data processing. Data are acquired at a fixed lateral position as interaction images, with the bias voltage as fast scan, and tip-sample distance as slow scan. Due to the quadratic dependence of the electrostatic interaction with tip-sample voltage the van der Waals force can be separated from the electrostatic force. Using appropriate data processing, the van der Waals interaction, the capacitance and the contact potential can be determined as a function of tip-sample distance. The measurement of resonance frequency shift yields very high signal to noise ratio and the absolute calibration of the measured quantities, while the acquisition of cantilever deflection allows the determination of the tip-sample distance

Localized strain measurements of the intervertebral disc annulus during biaxial tensile testing.

Science.gov (United States)

Karakolis, Thomas; Callaghan, Jack P

2015-01-01

Both inter-lamellar and intra-lamellar failures of the annulus have been described as potential modes of disc herniation. Attempts to characterize initial lamellar failure of the annulus have involved tensile testing of small tissue samples. The purpose of this study was to evaluate a method of measuring local surface strains through image analysis of a tensile test conducted on an isolated sample of annular tissue in order to enhance future studies of intervertebral disc failure. An annulus tissue sample was biaxial strained to 10%. High-resolution images captured the tissue surface throughout testing. Three test conditions were evaluated: submerged, non-submerged and marker. Surface strains were calculated for the two non-marker conditions based on motion of virtual tracking points. Tracking algorithm parameters (grid resolution and template size) were varied to determine the effect on estimated strains. Accuracy of point tracking was assessed through a comparison of the non-marker conditions to a condition involving markers placed on tissue surface. Grid resolution had a larger effect on local strain than template size. Average local strain error ranged from 3% to 9.25% and 0.1% to 2.0%, for the non-submerged and submerged conditions, respectively. Local strain estimation has a relatively high potential for error. Submerging the tissue provided superior strain estimates.

Straining and wrinkling processes during turbulence-premixed flame interaction measured using temporally-resolved diagnostics

Energy Technology Data Exchange (ETDEWEB)

Steinberg, Adam M.; Driscoll, James F. [Department of Aerospace Engineering, The University of Michigan, Ann Arbor, MI 48109 (United States)

2009-12-15

The dynamical processes of flame surface straining and wrinkling that occur as turbulence interacts with a premixed flame were measured using cinema-stereoscopic PIV (CS-PIV) and orthogonal-plane cinema-stereoscopic PIV (OPCS-PIV). These diagnostics provided temporally resolved measurements of turbulence-flame interaction at frame rates of up to 3 kHz and spatial resolutions as small as 280{mu} m. Previous descriptions of flame straining and wrinkling have typically been derived based on a canonical interaction between a pair of counter-rotating vortices and a planar flame surface. However, it was found that this configuration did not properly represent real turbulence-flame interaction. Interactions resembling the canonical configuration were observed in less than 10% of the recorded frames. Instead, straining and wrinkling were generally caused more geometrically complex turbulence, consisting of large groups of structures that could be multiply curved and intertwined. The effect of the interaction was highly dependent on the interaction geometry. Furthermore, even when the turbulence did exist in the canonical geometry, the straining and wrinkling of the flame surface were not well characterized by the vortical structures. A new mechanistic description of the turbulence-flame interaction was therefore identified and confirmed by the measurements. In this description, flame surface straining is caused by coherent structures of fluid-dynamic strain-rate (strain-rate structures). The role of vortical structures is to curve existing flame surface, creating wrinkles. By simultaneously considering both forms of turbulent structure, turbulence-flame interactions in both the canonical configuration and more complex geometries could be understood. (author)

Algorithm describing pressure distribution of non-contact TNT explosion

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Radosław Kiciński

2014-12-01

Full Text Available [b]Abstract[/b]. The aim of this study is to develop a computational algorithm, describing the shock wave pressure distribution in the space induced by non-contact TNT explosion. The procedure describes pressure distribution on a damp surface of the hull. Simulations have been carried out using Abaqus/CAE. The study also shows the pressure waveform descriptions provided by various authors and presents them in charts. The formulated conclusions convince efficiency of the algorithm application.[b]Keywords:[/b] Underwater explosion, shock wave, CAE, TNT, Kobben class submarine

Modification method to reduce the impact of blood vessel on noncontact discrimination of human blood based on ;M+N; theory

Science.gov (United States)

Zhang, Linna; Ding, Hongyan; Lin, Ling; Wang, Yimin; Guo, Xin

2018-01-01

Noncontact discriminating human blood is significantly crucial for import-export ports and inspection and quarantine departments. We had already demonstrated that visible diffuse reflectance spectroscopy combining PLS-DA method can successfully realize noncontact human blood discrimination. However, the circulated blood vessels may be produced with different materials. The use of various kinds of blood tubes may have a negative effect on the discrimination, based on ;M+N; theory (Li et al., 2016). In this research, we explored the impact of different material of blood vessels, such as glass tube and plastic tube, on the prediction ability of the discrimination model. Furthermore, we searched for the modification method to reduce the influence from the blood tubes. Our work indicated that generalized diffuse reflectance method can greatly improve the discrimination accuracy. This research can greatly facilitate the application of noncontact discrimination method based on visible and near-infrared diffuse reflectance spectroscopy.

Study of V-OTDR stability for dynamic strain measurement in piezoelectric vibration

Science.gov (United States)

Ren, Meiqi; Lu, Ping; Chen, Liang; Bao, Xiaoyi

2016-09-01

In a phase-sensitive optical-time domain reflectometry (Φ-OTDR) system, the challenge for dynamic strain measurement lies in large intensity fluctuations from trace to trace. The intensity fluctuation caused by stochastic characteristics of Rayleigh backscattering sets detection limit for the minimum strength of vibration measurement and causes the large measurement uncertainty. Thus, a trace-to-trace correlation coefficient is introduced to quantify intensity fluctuation of Φ-OTDR traces and stability of the sensor system theoretically and experimentally. A novel approach of measuring dynamic strain induced by various driving voltages of lead zirconate titanate (PZT) in Φ-OTDR is also demonstrated. Piezoelectric vibration signals are evaluated through analyzing peak values of fast Fourier transform spectra at the fundamental frequency and high-order harmonics based on Bessel functions. High trace-to-trace correlation coefficients varying from 0.824 to 0.967 among 100 measurements are obtained in experimental results, showing the good stability of our sensor system, as well as small uncertainty of measured peak values.

The influence of central corneal thickness and age on intraocular pressure measured by pneumotonometry, non-contact tonometry, the Tono-Pen XL, and Goldmann applanation tonometry.

Science.gov (United States)

Tonnu, P-A; Ho, T; Newson, T; El Sheikh, A; Sharma, K; White, E; Bunce, C; Garway-Heath, D

2005-07-01

To evaluate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements made with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT). CCT was recorded for either eye (randomly selected) of each of 105 untreated patients with ocular hypertension and glaucoma attending the glaucoma research unit at Moorfields Eye Hospital. For each of the selected eyes, IOP was measured with the GAT (two observers), Tono-Pen, OBF, and NCT in a randomised order. The relation of measured IOP and of inter-tonometer differences with CCT and subject age was explored by linear regression analysis. A significant association between measured IOP and CCT was found with each instrument. The change in measured IOP for a 10 mum increase in CCT was 0.28, 0.31, 0.38, and 0.46 for the GAT, Tono-Pen, OBF, and NCT, respectively (all p< or = 0.05). There was a significant association between the NCT/GAT differences and CCT, with a tendency of NCT to overestimate GAT in eyes with thicker corneas. There was a significant association between GAT/Tono-Pen and OBF/Tono-Pen differences and age, with a tendency of GAT and OBF to overestimate the Tono-Pen in eyes of older subjects. IOP measurement by all four methods is affected by CCT. The NCT is affected by CCT significantly more than the GAT. Subject age has a differential effect on the IOP measurements made by the GAT and OBF compared to the Tono-Pen.

Strain measurements of nuclear power plant steam generator antiseismic supports

International Nuclear Information System (INIS)

Kulichevsky, R.

1997-01-01

The nuclear power plants steam generators have different types of structural supports. One of these types are the antiseismic supports, which are intended to be under stress only if a seismic event takes place. Nevertheless, the antiseismic supports lugs, that are welded to the steam generator vessel, are subjected to thermal fatigue because of the temperature cycles related with the shut down and start up operations performed during the life of the nuclear power plant. In order to evaluate the stresses that the lugs are subjected to, several strain gages were welded on two supports lugs, positioned at two heights of one of the Embalse nuclear power plant steam generators. In this paper, the instrumentation used and the strain measurements obtained during two start up operations are presented. The influence of the plant start up operation parameters on the lugs strain evolution is also analyzed. (author) [es

Measurement of strain and strain relaxation in free-standing Si membranes by convergent beam electron diffraction and finite element method

Energy Technology Data Exchange (ETDEWEB)

Gao, H., E-mail: hongye18@mm.kyushu-u.ac.jp [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Ikeda, K.; Hata, S.; Nakashima, H. [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Wang, D.; Nakashima, H. [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

2011-04-15

Bridge-shaped free-standing Si membranes (FSSM), strained by low-pressure (LP) Si{sub x}N{sub y}, plasma-enhanced (PE) Si{sub x}N{sub y} and Si{sub x}Ge{sub 1-x} stressors, were measured by convergent beam electron diffraction (CBED) and the finite element method (FEM). The results of CBED show that, while the strain along the length of the FSSM is compressive in an LPSi{sub x}N{sub y}/Si sample, those along the length of the FSSM are tensile in PESi{sub x}N{sub y}/Si and Si{sub x}Ge{sub 1-x}/Si samples. The average absolute values of strains are different in FSSM with LPSi{sub x}N{sub y}, PESi{sub x}N{sub y} and Si{sub x}Ge{sub 1-x} as stressors. The FEM was used to compensate the results of CBED taking into account the strain relaxation in transmission electron microscopy (TEM) sample preparation. The FEM results give the strain properties in three dimensions, and are in good agreement with the results of CBED. There is approximately no strain relaxation along the length of FSSM, and the elastic strains along the other two axes in FSSM are partially relaxed by thinning down for the preparation of TEM samples.

Dissipation measurement in high Tc superconductors with electromagnetic probes

International Nuclear Information System (INIS)

Telschow, K.L.; O'Brien, T.K.; Idaho State Univ., Pocatello, ID

1989-01-01

The new ceramic superconducting materials, which have transition temperatures above that of liquid nitrogen, have great potential. However, most fabrication schemes produce consolidated forms with relatively low critical currents; successful application of these materials requires a means of measuring their critical parameters (such as critical current) that can be used to monitor and control fabrication processes. This paper describes a technique for measuring the onset of dissipation in a superconducting coating in a local and noncontacting manner. This work begins the process of developing noncontacting techniques for the measurement of critical currents on a local scale with the capability of providing spatial information. 6 refs., 6 figs

Strain measurements using Fiber Bragg Grating sensors in Structural Health Monitoring

Directory of Open Access Journals (Sweden)

Daniela ENCIU

2017-06-01

Full Text Available The paper presents some results obtained within a project of the “NUCLEU” Program financed by the Ministry of Research and Innovation-ANCS. The project supposes, among others, the design and the realization of a demonstrator for strain and stress measurements made with Fiber Bragg Gratings optical sensors. The paper details the construction of the demonstrator. The strain measurements induced in a cantilevered aluminum plate are compared with the analytical values provided by a mathematical model, and with the numerical values obtained by FEM analysis. The consistency of these comparative data indicates the achievement within the project of a level of competence necessary for later use of FBG sensors in the applicative researches involving the aerospace structures monitoring.

Smart Garment Fabrics to Enable Non-Contact Opto-Physiological Monitoring.

Science.gov (United States)

Iakovlev, Dmitry; Hu, Sijung; Hassan, Harnani; Dwyer, Vincent; Ashayer-Soltani, Roya; Hunt, Chris; Shen, Jinsong

2018-03-29

Imaging photoplethysmography (iPPG) is an emerging technology used to assess microcirculation and cardiovascular signs by collecting backscattered light from illuminated tissue using optical imaging sensors. The aim of this study was to study how effective smart garment fabrics could be capturing physiological signs in a non-contact mode. The present work demonstrates a feasible approach of, instead of using conventional high-power illumination sources, integrating a grid of surface-mounted light emitting diodes (LEDs) into cotton fabric to spotlight the region of interest (ROI). The green and the red LEDs (525 and 660 nm) placed on a small cotton substrate were used to locally illuminate palm skin in a dual-wavelength iPPG setup, where the backscattered light is transmitted to a remote image sensor through the garment fabric. The results show that the illuminations from both wavelength LEDs can be used to extract heart rate (HR) reaching an accuracy of 90% compared to a contact PPG probe. Stretching the fabric over the skin surface alters the morphology of iPPG signals, demonstrating a significantly higher pulsatile amplitude in both channels of green and red illuminations. The skin compression by the fabric could be potentially utilised to enhance the penetration of illumination into cutaneous microvascular beds. The outcome could lead a new avenue of non-contact opto-physiological monitoring and assessment with functional garment fabrics.

Noncontact speckle-based optical sensor for detection of glucose concentration using magneto-optic effect

Science.gov (United States)

Ozana, Nisan; Beiderman, Yevgeny; Anand, Arun; Javidi, Baharam; Polani, Sagi; Schwarz, Ariel; Shemer, Amir; Garcia, Javier; Zalevsky, Zeev

2016-06-01

We experimentally verify a speckle-based technique for noncontact measurement of glucose concentration in the bloodstream. The final device is intended to be a single wristwatch-style device containing a laser, a camera, and an alternating current (ac) electromagnet generated by a solenoid. The experiments presented are performed in vitro as proof of the concept. When a glucose substance is inserted into a solenoid generating an ac magnetic field, it exhibits Faraday rotation, which affects the temporal changes of the secondary speckle pattern distributions. The temporal frequency resulting from the ac magnetic field was found to have a lock-in amplification role, which increased the observability of the relatively small magneto-optic effect. Experimental results to support the proposed concept are presented.

Measurement of internal forces in superconducting accelerator magnets with strain gauge transducers

International Nuclear Information System (INIS)

Goodzeit, C.L.; Anerella, M.D.; Ganetis, G.L.

1988-01-01

An improved method has been developed for the measurement of internal forces in superconducting accelerator magnets, in particular the compressive stresses in coils and the end restraint forces on the coils. The transducers have been designed to provide improved sensitivity to purely mechanical strain by using bending mode deflections for sensing the applied loads. Strain gauge resistance measurements are made with a new system that eliminates sources of errors due to spurious resistance changes in interconnecting wiring and solder joints. The design of the transducers and their measurement system is presented along with a discussion of the method of compensation for thermal and magnetic effects, methods of calibration with typical calibration data, and measured effect in actual magnets of the thermal stress changes from cooldown and the Lorentz forces during magnet excitation. 13 figs., 1 tab

Prevalence of non-contact and contact childhood sexual abuse: An Internet-based sample of men who have sex with men in China.

Directory of Open Access Journals (Sweden)

Wenjian Xu

Full Text Available The prevalence of childhood sexual abuse (CSA is high among Western men who have sex with men (MSM, and CSA is associated with certain socio-demographic variables and with human immunodeficiency virus (HIV status. Little is known about CSA among Chinese MSM; therefore, we explored the prevalence and frequency of non-contact (e.g., sexual invitations, exhibitionism and contact (e.g., intercourse, genital contact forms of CSA in an Internet-based sample of MSM in China. We also examined the associations between the participants' socio-demographic characteristics and HIV status, and their histories of CSA.We surveyed MSM from 30 Chinese provinces in 2014-2015; 1,030 (mean age = 25.15 years, SD = 6.32 and 1,020 (mean age = 25.05 years, SD = 5.95 respondents were eligible for inclusion in the non-contact and contact CSA groups, respectively.Prevalence of non-contact and contact CSA was 36.2% and 29.8%, respectively; 20.4% and 15.0% had experienced non-contact and contact CSA ≥ 3 times, respectively. Most respondents were young adults, well educated, single, had never "come out," and self-identified as gay or bisexual men. Univariate analyses showed that respondents who had experienced contact CSA were more likely to be HIV-positive than those who had never experienced contact CSA. Multivariate analyses showed that non-contact CSA was associated with less education, being in a relationship with a woman or a man, and having "come out." Contact CSA was associated with less education, higher income, and being in a relationship with a man. Respondents who had experienced non-contact CSA ≥ 3 times were more likely to be less educated, "out," and to be in a relationship with a woman or a man. Respondents who had experienced contact CSA ≥ 3 times were more likely to be less educated and to be in a relationship with a man.It is necessary to pay closer attention to CSA among MSM and other sexual minorities in China.

The applicability of correction factor for corneal thickness on non-contact tonometer measured intraocular pressure in LASIK treated eyes.

Science.gov (United States)

Jethani, Jitendra; Dave, Paaraj; Jethani, Monica; Desai, Yogesh; Patel, Purvi

2016-01-01

To determine the applicability of central corneal thickness (CCT) based correction factor for non-contact tonometer (NCT) measured intraocular pressure (IOP) readings. A prospective, non-randomized study involved 346 eyes of 173 consecutive patients with age ⩾21 years undergoing laser-assisted in situ keratomileusis (LASIK) for myopia and/or myopic astigmatism. The CCT and IOP were measured before and after the LASIK procedure. The IOP pre and post-LASIK was compared after applying the correction factor for CCT. Patients not completing the 3 month postoperative follow-up were excluded. The median spherical equivalent before undergoing LASIK was -4.25D (inter-quartile range, -3.25D). The mean preoperative CCT was 536.82 ± 33.71 μm which reduced to 477.55 ± 39.3 μm (p < 0.01) post-LASIK. The mean IOP reduced from a preoperative value of 14.6 ± 2.32 mmHg to 10.64 ± 2.45 mmHg postoperatively (p < 0.01). On applying correction for the corneal thickness, the pre and postoperative IOP was 15.14 ± 2.8 mmHg and 15.37 ± 2.65 mmHg (p = 0.06) respectively with a strong positive correlation (r = 0.7, p < 0.01). Three hundred eyes (86.7%) had an absolute difference in IOP of less than 3.0 mmHg post-CCT correction which is within the retest variability of NCT. Only 46 eyes (13.3%) had an absolute difference of more than 3.0 mmHg. The modified Ehler's correction algorithm used in this study can be effectively applied in the normal IOP range in a majority of patients.

Triaxial extensometer for volumetric strain measurement in a hydro-compression loading test for foam materials

International Nuclear Information System (INIS)

Feng, Bo; Xu, Ming-long; Zhao, Tian-fei; Zhang, Zhi-jun; Lu, Tian-jian

2010-01-01

A new strain gauge-based triaxial extensometer (radial extensometers x, y and axial extensometer z) is presented to improve the volumetric strain measurement in a hydro-compression loading test for foam materials. By the triaxial extensometer, triaxial deformations of the foam specimen can be measured directly, from which the volumetric strain is determined. Sensitivities of the triaxial extensometer are predicted using a finite-element model, and verified through experimental calibrations. The axial extensometer is validated by conducting a uniaxial compression test in aluminium foam and comparing deformation measured by the axial extensometer to that by the advanced optical 3D deformation analysis system ARAMIS; the result from the axial extensometer agrees well with that from ARAMIS. A new modus of two-wire measurement and transmission in a hydrostatic environment is developed to avoid the punching and lead sealing techniques on the pressure vessel for the hydro-compression test. The effect of hydrostatic pressure on the triaxial extensometer is determined through an experimental test. An application in an aluminium foam hydrostatic compression test shows that the triaxial extensometer is effective for volumetric strain measurement in a hydro-compression loading test for foam materials

Measurement of strain distribution in bonded joints by fiber Bragg gratings

Science.gov (United States)

Guemes, J. Alfredo; Diaz-Carrillo, Sebastian; Menendez, Jose M.

1998-07-01

Due to the small dimensions of the adhesive layer, the high non-uniformity of the strain field and the non linear elastic behavior of the adhesive material, the strain distribution at an adhesive joint can be predicted by FEM, but can not be experimentally obtained with classical approaches; only non standard procedures like Moire interferometry, or special artifacts like KGR extensometers may afford some insights on the behavior of the adhesive. Due to their small size, ensuring low perturbation of the strain field, and their innate ability to measure strain and strain gradient along the sensor, fiber Bragg gratings offer a good opportunity to solve this problem, and it is a good example of situations that may benefit from these new sensors. Fiber Bragg gratings may be placed or at the interface, within the adhesive layer, or embedded at the adherents, if these were made of composite material. Tests may be run at different temperatures, changing the adhesive characteristics from brittle to pseudoplastic without additional difficulties. When loading the joint, the strain field is obtained by analyzing the distorted spectrum of the reflected light pulse; the algorithm for doing it has already been published. A comparison with theoretical results is done, and the validity and utility of these sensors for this and similar applications is demonstrated.

A fiber-optic strain measurement and quench localization system for use in superconducting accelerator dipole magnets

NARCIS (Netherlands)

van Oort, J.M.; Scanlan, Ronald M.; ten Kate, Herman H.J.

1995-01-01

A novel fiber-optic measurement system for superconducting accelerator magnets is described. The principal component is an extrinsic Fabry-Perot interferometer to determine localized strain and stress in coil windings. The system can be used either as a sensitive relative strain measurement system

Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.

Science.gov (United States)

Alentorn-Geli, Eduard; Myer, Gregory D; Silvers, Holly J; Samitier, Gonzalo; Romero, Daniel; Lázaro-Haro, Cristina; Cugat, Ramón

2009-07-01

Soccer is the most commonly played sport in the world, with an estimated 265 million active soccer players by 2006. Inherent to this sport is the higher risk of injury to the anterior cruciate ligament (ACL) relative to other sports. ACL injury causes the most time lost from competition in soccer which has influenced a strong research focus to determine the risk factors for injury. This research emphasis has afforded a rapid influx of literature defining potential modifiable and non-modifiable risk factors that increase the risk of injury. The purpose of the current review is to sequence the most recent literature that reports potential mechanisms and risk factors for non-contact ACL injury in soccer players. Most ACL tears in soccer players are non-contact in nature. Common playing situations precluding a non-contact ACL injury include: change of direction or cutting maneuvers combined with deceleration, landing from a jump in or near full extension, and pivoting with knee near full extension and a planted foot. The most common non-contact ACL injury mechanism include a deceleration task with high knee internal extension torque (with or without perturbation) combined with dynamic valgus rotation with the body weight shifted over the injured leg and the plantar surface of the foot fixed flat on the playing surface. Potential extrinsic non-contact ACL injury risk factors include: dry weather and surface, and artificial surface instead of natural grass. Commonly purported intrinsic risk factors include: generalized and specific knee joint laxity, small and narrow intercondylar notch width (ratio of notch width to the diameter and cross sectional area of the ACL), pre-ovulatory phase of menstrual cycle in females not using oral contraceptives, decreased relative (to quadriceps) hamstring strength and recruitment, muscular fatigue by altering neuromuscular control, decreased "core" strength and proprioception, low trunk, hip, and knee flexion angles, and high

Stretching positions for the coracohumeral ligament: Strain measurement during passive motion using fresh/frozen cadaver shoulders

Directory of Open Access Journals (Sweden)

Izumi Tomoki

2011-01-01

Full Text Available Abstract Background Contracture of the coracohumeral ligament is reported to restrict external rotation of the shoulder with arm at the side and restrict posterior-inferior shift of the humeral head. The contracture is supposed to restrict range of motion of the glenohumeral joint. Methods To obtain stretching position of the coracohumeral ligament, strain on the ligament was measured at the superficial fibers of the ligament using 9 fresh/frozen cadaver shoulders. By sequential measurement using a strain gauge, the ligament strain was measured from reference length (L0. Shoulder positions were determined using a 3 Space Tracker System. Through a combination of previously reported coracohumeral stretching positions and those observed in preliminary measurement, ligament strain were measured by passive external rotation from 10° internal rotation, by adding each 10° external rotation, to maximal external rotation. Results Stretching positions in which significantly larger strain were obtained compared to the L0 values were 0° elevation in scapula plane with 40°, 50° and maximum external rotation (5.68%, 7.2%, 7.87%, 30° extension with 50°, maximum external rotation (4.20%, 4.79%, and 30° extension + adduction with 30°, 40°, 50° and maximum external rotation (4.09%, 4.67%, 4.78%, 5.05%(P Conclusions Significant strain of the coracohumeral ligament will be achieved by passive external rotation at lower shoulder elevations, extension, and extension with adduction.

Strain measurements at the HDR-pipe-system under LOCA-load: Effects on elbows and displaced weldings

International Nuclear Information System (INIS)

Hunger, H.

1985-01-01

This paper characterizes some effects which have been detected during strain gauge measurements on a test piping with feed water check valve oscillating under blowdown-load. The ovalization of a pipe elbow subjected to in-plane-bending affects the connected straight pipe; this is shown by means of circumferential stresses. Very high LOCA-load produces plastic strain and changes the pipe dynamics. Artificial displaced welds increase the local strain but no defects have occurred. One example compares stresses from measurement and post-calculation. Moreover there are given some remarks on the optimization of the comparison of measurement and calculation. (orig.)

Heat capacity measurements of Sr{sub 2}RuO{sub 4} under uni-axial strain