A Rapid Method for the Determination of Principal Stresses Across Sections of Symmetry From Photoelastic Data

1938 ◽  
Vol 5 (1) ◽  
pp. A24-A28
Author(s):  
M. M. Frocht
Keyword(s):  
Free Boundary ◽  
Rapid Method ◽  
Circular Hole ◽  
Characteristic Curve ◽  
Principal Stresses ◽  
Recent Improvement ◽  
Tangential Stresses ◽  
Circular Holes ◽  
Photoelastic Data

Abstract The author discusses: (a) Mesnager’s theorem of isoclinics, (b) the characteristic curve of tangential stresses across a section of symmetry, (c) a formula for the maximum tangential stresses for the case of a central circular hole between fields of pure tension, (d) the slope of the p curve at a point corresponding to a cupic point, (e) recent improvement in the determination of free boundary stresses, and (f) formulas for the position of cupic points for two cases. A new method for the determination of the principal stresses across sections of symmetry from photoelastic data is illustrated with three examples: (1) Bars in tension or compression with central circular holes, (2) grooved beams in bending, and (3) rings or disks with circular central holes subjected to two concentrated diametral loads.

Experimental analysis of high-frequency stress waves in a ring

1969 ◽  
Vol 4 (4) ◽  
pp. 297-305 ◽  
Author(s):  
A J Durelli ◽  
J A Clark ◽  
A Kochev
Keyword(s):  
High Frequency ◽  
Stress Waves ◽  
Stress Distributions ◽  
Principal Stresses ◽  
Tangential Stresses ◽  
Photoelastic Analysis ◽  
Photoelastic Data ◽  
Axis Of Symmetry ◽  
Capacitance Gauge

This paper deals with the photoelastic analysis of stress waves in a thick ring subjected to transient high-frequency loading. The device used to apply the loading is a piezo-electric transducer which initially produces four cycles of a 31·25 kHz toneburst. The loading pulse can be reproduced with high precision. The ring is illuminated with a flash of approximately 0·5 μs duration which can be delayed in a continuously adjustable manner. Isochromatics and isoclinics can be directly observed as static patterns. Photoelastic data are supplemented by measurements obtained with a capacitance gauge used as a dynamic lateral extensometer. Satisfactory agreement is found between tangential stresses near the free boundary of the ring determined from photoelastic data and those determined from capacitance-gauge measurements. As examples of complete determination of stress distributions, the separated principal stresses are obtained along an axis of symmetry and a vectorial representation of the principal stresses is given. A wave interpretation of the data is developed and comparisons are made with available solutions of related problems.

Optical Stress Analysis of Flexural Waves in a Bar

1970 ◽  
Vol 37 (2) ◽  
pp. 331-338 ◽  
Author(s):  
J. A. Clark ◽  
A. J. Durelli
Keyword(s):  
High Speed ◽  
Sine Wave ◽  
Good Precision ◽  
Stress Distributions ◽  
Flexural Waves ◽  
Principal Stresses ◽  
Full Field ◽  
Modified Method ◽  
Photoelastic Data

A complete, direct, full-field optical determination of dynamic stress distributions by a combination of photoelastic and interferometric measurements is illustrated. The method is applied to the study of flexural waves propagating in a photoelastic, urethane rubber bar. A displacement type of transverse, dynamic loading (which has approximately the form of a decaying sine wave) is applied at one end of the bar. The loading pulse can be repeated with good precision. Individual isochromatics and isoclinics are obtained, using a still camera with a short duration (0.5 micro sec) flash. A series of isochromatics have also been obtained with a Fastax high-speed motion picture camera. Photoelastic data are supplemented by isopachic patterns obtained by a modified method of holographic interferometry recently developed by the authors. As an example of complete determination of stress distributions, a vectorial representation of the principal stresses at one instant is given. Comparisons are made with approximate theories.

The determination of principal stresses from photoelastic data

Strain ◽  
1992 ◽  
Vol 28 (4) ◽  
pp. 153-158 ◽  
Author(s):  
S. J. Haake ◽  
E. A. Patterson
Keyword(s):  
Principal Stresses ◽  
Photoelastic Data

A Rapid Method for Determination of Buprenorphine and Norbuprenorphine in Urine by UPLC-MS/MS

2020 ◽  
Vol 16 ◽  
Author(s):  
Aykut Kul ◽  
Murat Ozdemir ◽  
Selma Ozilhan ◽  
Olcay Sagirli
Keyword(s):  
Forensic Science ◽  
Rapid Method ◽  
Proficiency Testing ◽  
Mass Spectrometer ◽  
Illicit Market ◽  
Analysis Methods ◽  
Accuracy And Precision ◽  
Lower Limits

Background: Buprenorphine is quite common in the illicit market. Buprenorphine-containing drugs abuse is frequently encountered in patients. The analysis methods used to determine the abuse of buprenorphine and norbuprenorphine are important for forensic science. Buprenorphine is metabolized to norbuprenorphine by the liver. Objective: Therefore, the determination of buprenorphine and norbuprenorphine in urine is one of the methods to determine the abuse of buprenorphine. Methods: In this study, we have developed a precise, simple, and rapid ultra-performance liquid chromatographytandem mass spectrometer method for the determination of buprenorphine and norbuprenorphine simultaneously. Results: The developed method was validated in terms of selectivity and linearity, which was in the range of 9–1800 ng/mL for both buprenorphine and norbuprenorphine. The intra-assay and inter-assay accuracy and precision were found within acceptable limits of the EMA guideline. Lower limits of quantitation were 9 ng/mL for both buprenorphine and norbuprenorphine. Conclusion: The developed method was successfully applied for the determination of both analytes in the proficiency testing samples.

Determination of Dimetridazole and Ipronidazole in Feeds at Cross-Contamination Levels

1988 ◽  
Vol 71 (3) ◽  
pp. 474-477 ◽  
Author(s):  
Duane D Hughes
Keyword(s):  
Thin Layer ◽  
Rapid Method ◽  
Aqueous Phase ◽  
Borate Buffer ◽  
Cross Contamination ◽  
Chromatographic System ◽  
Arsanilic Acid ◽  
Contamination Levels ◽  
Benzene Extract

Abstract A rapid method for the determination of dimetridazole and ipronidazole in feeds is described. The compounds are extracted from a borate buffer (pH 8.65) with benzene, partitioned into IN HC1, and then partitioned back into benzene from a basic aqueous phase. The benzene extract is concentrated and injected onto a nonpolar (Apiezon L) gas chromatographic column for determination by 63Ni electroncapture detection. Recoveries from feeds of various composition, spiked at 0.2 ppm with both dimetridazole and ipronidazole, ranged from 70 to 115%; for the same feeds spiked at 1 ppm or more, the recoveries were greater than 80%. Carbadox, furazolidone, levamisole, oxytetracycline, chlortetracycline, sulfamethazine, sulfaquinoxaline, arsanilic acid, piperazine, penicillin, and commonly added vitamins and minerals do not interfere. A 2-dimensional thin layer chromatographic system is presented as a means of additional identification.

scholarly journals A RAPID METHOD FOR THE DETERMINATION OF CITRIC ACID

1948 ◽  
Vol 175 (2) ◽  
pp. 849-855 ◽  
Author(s):  
Murray. Saffran ◽  
Orville F. Denstedt
Keyword(s):  
Citric Acid ◽  
Rapid Method

scholarly journals Deep Learning Based HPV Status Prediction for Oropharyngeal Cancer Patients

Cancers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 786
Author(s):  
Daniel M. Lang ◽  
Jan C. Peeken ◽  
Stephanie E. Combs ◽  
Jan J. Wilkens ◽  
Stefan Bartzsch
Keyword(s):  
Deep Learning ◽  
Cancer Patients ◽  
Oropharyngeal Cancer ◽  
Characteristic Curve ◽  
Learning Models ◽  
Convolutional Network ◽  
Hpv Status ◽  
3D Information ◽  
External Test

Infection with the human papillomavirus (HPV) has been identified as a major risk factor for oropharyngeal cancer (OPC). HPV-related OPCs have been shown to be more radiosensitive and to have a reduced risk for cancer related death. Hence, the histological determination of HPV status of cancer patients depicts an essential diagnostic factor. We investigated the ability of deep learning models for imaging based HPV status detection. To overcome the problem of small medical datasets, we used a transfer learning approach. A 3D convolutional network pre-trained on sports video clips was fine-tuned, such that full 3D information in the CT images could be exploited. The video pre-trained model was able to differentiate HPV-positive from HPV-negative cases, with an area under the receiver operating characteristic curve (AUC) of 0.81 for an external test set. In comparison to a 3D convolutional neural network (CNN) trained from scratch and a 2D architecture pre-trained on ImageNet, the video pre-trained model performed best. Deep learning models are capable of CT image-based HPV status determination. Video based pre-training has the ability to improve training for 3D medical data, but further studies are needed for verification.

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