Comparison of shearography to scanning laser vibrometry as methods for local stiffness identification of beams

Local stiffness of Euler–Bernoulli beams can be identified by dividing the bending moment of a deformed beam by the local curvature. Curvature and moment distributions can be derived from the modal shape of a beam vibrating at resonance. In this article, the modal shape of test beams is measured by both scanning laser vibrometry (SLV) and shearography. Shearography is an interferometric optical method that produces full-field displacement gradients of the inspected surface. Curvature can be obtained by two steps of derivation of the modal amplitude (in the case of SLV) or one step of derivation of the modal shape slope (in the case of shearography). Three specially prepared aluminium beams with a known stiffness distribution are used for the validation of both techniques. The uncertainty of the identified stiffness distributions with both techniques is compared and related to their signal-to-noise ratios. A strength and weakness overview at the end of the article reveals that the shearography is the technique that shows the most advantages

Microcalcification and Macrocalcification Detection in Mammograms Based on GLCM and ODCM Texture Features Using SVM Classifier

Breast cancer is a common cancer in women and the second leading cause of cancer deaths worldwide. Photographing the changes in internal breast structure due to formation of masses and microcalcification for detection of Breast Cancer is known as Mammogram, which are low dose x-ray images. These images play a very significant role in early detection of breast cancer. Usually in pattern recognition texture analysis is used for classification based on content of image or in image segmentation based on variation of intensities of gray scale levels or colours. Similarly texture analysis can also be used to identify masses and microcalcification in mammograms. However Grey Level Co-occurrence Matrices (GLCM) technique introduced by Haralick was initially used in study of remote sensing images. Radiologists f i n d i t d i f f i c u l t to identify the mass in a mammogram, since the masses are surrounded by pectoral muscle and blood vessels. In breast cancer screening, radiologists usually miss approximately 10% - 30% of tumors because of the ambiguous margins of tumors resulting from long-time diagnosis. Computer-aided detection system is developed to aid radiologists in detecting ma mammographic masses which indicate the presence of breast cancer. In this paper the input image is pre-processed initially that includes noise removal, pectoral muscle removal, thresholding, contrast enhancement and suspicious mass is detected and the features are extracted based on the mass detected. A feature extraction method based on grey level co- occurrence matrix and optical density features called GLCM -OD features is used to describe local texture characteristics and the discrete photometric distribution of each ROI. Finally, a support vector machine is used to classify abnormal regions by selecting the individual performance of each feature. The results prove that the proposed system achieves an excellent detection performance using SVM classifier

Ultrasonic characterization of subsurface 2D corrugation

The ultrasonic backscattering technique is employed for the characterization of a 2D surface corrugation which is superposed on or hidden on the backside of a polycarbonate sample. In contrast to previous studies where the incident angle at well-defined and a-priori known symmetry orientations of the surface structure is varied in order to extract the characteristic periodicities, the backscatter polar scan method incorporates an additional variation of the orientation of the vertical insonification plane within the experimental measurement protocol. As such, the characteristic periodicities as well as the surface symmetries can be extracted without any prior knowledge of the surface structure. As a benefit compared to optical methods, we have also validated this extended methodology for the investigation of a 2D subsurface corrugation. Although the diffraction conditions do not change in comparison with a visible 2D surface corrugation, we remark that additional attention is required in the sense that the elastic properties of the substrate material put further restrictions to the range of applicable ultrasonic frequencies. The characterized periodicities and symmetries are in excellent agreement with the design parameters of the (hidden) 2D surface grating

A novel ultrasonic strain gauge for single-sided measurement of a local 3D strain field

A novel method is introduced for the measurement of a 3D strain field by exploiting the interaction between ultrasound waves and geometrical characteristics of the insonified specimen. First, the response of obliquely incident harmonic waves to a deterministic surface roughness is utilized. Analysis of backscattered amplitudes in Bragg diffraction geometry then yields a measure for the in-plane strain field by mapping any shift in angular dependency. Secondly, the analysis of the reflection characteristics of normal incident pulsed waves in frequency domain provides a measure of the out-of-plane normal strain field component, simply by tracking any change in the stimulation condition for a thickness resonance. As such, the developed ultrasonic strain gauge yields an absolute, contactless and single-sided mapping of a local 3D strain field, in which both sample preparation and alignment procedure are needless. Results are presented for cold-rolled DC06 steel samples onto which skin passing of the work rolls is applied. The samples have been mechanically loaded, introducing plastic strain levels ranging from 2% up to 35%. The ultrasonically measured strains have been validated with various other strain measurement techniques, including manual micrometer, longitudinal and transverse mechanical extensometer and optical mono- and stereovision digital image correlation. Good agreement has been obtained between the ultrasonically determined strain values and the results of the conventional methods. As the ultrasonic strain gauge provides all three normal strain field components, it has been employed for the extraction of Lankford ratios at different applied longitudinal plastic strain levels, revealing a strain dependent plastic anisotropy of the investigated DC06 steel sheet

Calibration and correction procedure for quantitative out-of-plane shearography

Quantitative shearography applications continue to gain practical importance. However, a study of the errors inherent in shearography measurements, related to calibration of the instrument and correction of the results, is most often lacking. This paper proposes a calibration and correction procedure for the out-of-plane shearography with a Michelson interferometer. The calibration is based on the shearography measurement of known rigid-body rotations of a flat plate and accounts for the local variability of the shearing distance. The correction procedure further compensates for the variability of the sensitivity vector and separates the two out-of-plane deformation gradients when they are coupled in the measurement. The correction procedure utilizes two shearography measurements of the same experiment with distinct shearing distances. The effectiveness of the proposed calibration procedure is demonstrated in the case of a static deformation of a centrally loaded plate, where the discrepancy between experimental and finite element analysis results is minimized

Errors in shearography measurements due to the creep of the PZT shearing actuator

Shearography is a modern optical interferometric measurement technique. It uses interferometric properties of coherent laser light to measure deformation gradients on the μm/m level. In the most common shearography setups, the ones employing Michelson interferometer, the deformation gradients in both x- and y-direction can be identified by setting angles on the shearing mirror. One of the mechanisms for setting the desired shearing angles in the Michelson interferometer is using the PZT actuators. This paper will reveal that the time-dependent creep behaviour of the PZT actuators is a major source of measurement errors. Measurements at long time spans suffer severely from this creep behaviour. Even for short time spans, which are typical for shearographic experiments, the creep behaviour of the PZT shear actuator induces considerable deviation in the measured response. In this paper the mechanism and the effect of the PZT creep is explored and demonstrated with measurements. For long time-span measurements in shearography, noise is a limiting factor. Thus, the time-dependent evolution of noise is considered in this paper, with particular interest in the influence of the external vibrations. Measurements with and without the external vibration isolation are conducted and the difference between the two setups is analyzed. At the end of the paper some recommendations are given for minimizing and correcting the here studied time-dependent effects

Chronic Kidney Disease Patients\u27 Experiences in the Decision Making Process: The Relationship Between Personal Characteristics and Decisional Self-Efficacy on Decisional Conflict and the Dialysis Decision in Patients who Participated in Shared Decision Making

Patients with End Stage Renal Disease (ESRD) experience a complex and stressful decision making when comes to dialysis modality selection. There are pros and cons to both hemodialysis (HD) and peritoneal dialysis (PD). Patients are often uncertain as to which one is the best modality for them. This decisional conflict increases the likelihood of making a decision that is not based on the patient’s values or preferences and may result in undesirable post-decisional consequences. Purpose The purpose of this study was to explore Chronic Kidney Diseases (CKD) patients\u27 experiences regarding their decision making process in selecting a dialysis modality. The study examined individual characteristics and explores the relationship between characteristics such as demographics, decisional self-efficacy, and decisional conflict on perceived participation in shared decision making in a sample of individuals with CKD. Research Objective The objective of this mixed-method study was twofold: (a) to provide a quantitative description of the sample of individuals with CKD who are currently considering any one of the treatment strategies or currently receiving treatment for CKD within the last three months of diagnosis; and (b) to explore relationships between individual characteristics and participation in shared decision making (SDM) as they predict their decisional conflict and satisfaction with the decision made. Method This study employed a mixed-methods approach with an exploratory and a descriptive correlation designed to evaluate constructs of individual characteristics that may impact the decisions of individuals with CKD participating in shared decision making as described by the Ottawa Decisional Support Framework. Sample Study participants were recruited directly from the Kidney Solutions website (kidneysolutions.org). A recruitment flyer was sent out with the researcher’s contact information to Kidney Solutions along with the survey questionnaire using Google Forms. Kidney Solutions then sent out the link directly to all the patients who qualify for the study based on the inclusion criteria via email. No participants were contacted directly by the researcher. Participants were informed that their participation was voluntary, confidential, and that they could opt-out at any time. Procedure Data were collected after obtaining approval from Molloy College IRB. The survey was integrated into a single web-based set of questions using Google Forms. Completing the questionnaire indicated the subject\u27s consent to participate. The online survey included four inclusion criteria questions: (a) 18 years of age and older; (b) individuals who self-identify as having CKD diagnosed by a healthcare provider; (c) individuals currently considering or within the last three months has decided on a treatment option for CKD; (d) individuals who can participate in English and have modest internet skills. Measures Suitable tools were selected after an intense literature review that would be useful in measuring the research concepts in shared decision making, and permission was obtained from the developers of the tool for the study. These instruments capture participants’ self-reported Decisional Self-Efficacy Scale (DSES), decisional conflict (SURE test), shared decision making (9-item Shared Decision Making Questionnaire), and Satisfaction with Decision Instrument. Results Statistical analysis was performed to determine relationships between individual characteristics and concepts in shared decision making using t test, Chi-square, ANOVA and Pearson product-moment correlation coefficient and multiple linear regression. Participants were predominantly White (63.6%), male (54.5%), between 45-64 years old (45.5%), married or partnered (54.5%), college educated (60.0%), with most reporting CKD stage 5 (63.6%). There was a statistically significant difference at the p \u3c .05 level in SDMQ9 scores for Decision making support (t = -2.582, p \u3c .05) and use of a decisional aid in decision making (t = -2.357, p \u3c .05). The study also found a statistically significant association between current treatment option (p = .021) and decisional conflict as measured by the SURE test. There was a statistically significant positive correlation between decisional self-efficacy (as measured by the DSES) and shared decision making (as measured by the 9-item Shared Decision Making Questionnaire) observed (r = .390, n = 55, p \u3c .01). There was a significant relationship between participation in shared decision making and decisional conflict (r = -0.362, p \u3c .01). The results indicated a negative correlation, which means as SDM increases, less decisional conflict is reported by the participants. There was a significant relationship between decisional self-efficacy and decisional conflict (r = -0.489, p \u3c .001). The results indicated a negative correlation, which means as Decisional Self-Efficacy increases, less decisional conflict is reported by the participants. There was also a positive correlation between shared decision making and satisfaction with the decision, r = .701, n = 55, p \u3c .01. There was also a positive correlation between decisional self-efficacy and satisfaction with decision, r = .624, n = 55, p \u3c .01. Prediction for satisfaction with decision (SWD) is significant using a multiple linear regression model by combining decisional self-efficacy (DSES) and SDM, with n = 55, R = 0.797, R square 0.636, Adjusted R square = 0.622, F = 45.408. Prediction for decisional conflict (SURE) was significant using a multiple linear regression model by combining DSES and SDM, with n = 55, R = 0.523, R square 0.273, Adjusted R square = 0.245, F = 9.781. In this model, decisional self-efficacy predicts decisional conflict more than shared decision making. Shared decision making had a non-significant impact on the dependent variable decisional conflict alone, but it adds to the prediction when combined with decisional self-efficacy. Qualitative findings supported several quantitative findings, adding depth to understanding participants’ views. Conclusions The findings contribute to understanding the importance of increasing patient involvement in determining treatment when more than one treatment option exists based on the goals of care. Providers must approach their patients’ critical decision points in their illness trajectory with an openness of sharing in the plan of care. There is a significant need to move away from a “one-size-fits-all” approach to dialysis and provide more individualized care that incorporates patient goals and preferences while still maintaining best practices for quality and safety