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Huang Y, Janabi-Sharifi F, Liu Y, Hung YY. Dynamic phase measurement in shearography by clustering method and Fourier filtering. Opt Express 2011; 19:606-615. [PMID: 21263600 DOI: 10.1364/oe.19.000606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Quantitative phase extraction is a key step in optical measurement. While phase shifting technique is widely employed for static or semi-static phase measurement, it requires several images with known phase shifts at each deformed stage, thus is not suitable for dynamic phase measurement. Fourier transform offer a solution to extract phase information from a single fringe pattern. However, a high frequency spatial carrier which is sometimes not easy to generate is required to solve the phase ambiguity problem. In this paper, we aim to propose an ideal solution for dynamic phase measurement. Four images with known phase shift are captured at the reference stage to analyze the initial phase information. After the object starts continuous deformation, only one image is captured at each deformed stage. A clustering phase extraction method is then applied for deformation phase extraction utilizing the phase clustering effect within a small region. This method works well for speckle image with low and medium fringe density. When the fringe density is high, especially in the case of shearographic fringe, information insufficiency inherent with merely one deformed speckle image often results in poor quality wrapped phase map with plenty of phase residues, which make phase unwrapping a difficult task. In the light of this limitation, a Fourier transform based phase filtering method is proposed for fringe frequency analysis and adaptive filtering, and effectively removes most of the phase residues to reconstruct a high quality wrapped phase map. Several real experiments based on shearography are presented. Comparison between the proposed solution and standard phase evaluation methods is also given. The results demonstrate the effectiveness of the proposed integrated dynamic phase extraction method.
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Affiliation(s)
- Yuanhao Huang
- State Key Laboratory of CAD&CG, Zhejiang University, Hangzhou, China
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Hung YY, Huang YH, Liu L, Ng SP, Chen YS. Computerized tomography technique for reconstruction of obstructed phase data in shearography. Appl Opt 2008; 47:3158-3167. [PMID: 18545289 DOI: 10.1364/ao.47.003158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Shearography is an interferometric method that overcomes several limitations of holography by eliminating the reference beam. It greatly simplifies the optical setup and has much higher tolerance to environmental disturbances. Consequently, the technique has received considerable industrial acceptance, particularly for nondestructive testing. Shearography, however, is generally not applicable to the measurement of an obstructed area, as the area to be measured must be accessible to both illumination and imaging. We present an algorithm based on the principle of tomography that permits the reconstruction of the unavailable phase distribution in an obstructed area from the measured boundary phase distribution. In the process, a set of imaginary rays is projected from many different directions across the area. For each ray, integration of the phase directional derivative along the ray is equal to the phase difference between the boundary points intercepted by the ray. Therefore, a set of linear equations can be established by considering the multiple rays. Each equation expresses the unknown phase derivatives in the obstructed area in terms of the measured boundary phase. Solution of the set of simultaneous equations yields the unknown phase distribution in the blind area. While its applications to shearography are demonstrated, the technique is potentially applicable to all full-field optical measurement techniques such as holography, speckle interferometry, classical interferometry, thermography, moiré, photoelasticity, and speckle correlation techniques.
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Affiliation(s)
- Y Y Hung
- Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, Hong Kong, China
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Kuppahally SS, Valantine HA, Weisshaar D, Parekh H, Hung YY, Haddad F, Fowler M, Vagelos R, Perlroth MG, Robbins RC, Hunt SA. Outcome in cardiac recipients of donor hearts with increased left ventricular wall thickness. Am J Transplant 2007; 7:2388-95. [PMID: 17845572 DOI: 10.1111/j.1600-6143.2007.01930.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The ongoing shortage of donors for cardiac transplantation has led to a trend toward acceptance of donor hearts with some structural abnormalities including left ventricular hypertrophy. To evaluate the outcome in recipients of donor hearts with increased left ventricular wall thickness (LVWT), we retrospectively analyzed data for 157 cardiac donors and respective recipients from January 2001 to December 2004. There were 47 recipients of donor heart with increased LVWT >or=1.2 cm, which constituted the study group and 110 recipients of a donor heart with normal LVWT < 1.2 cm that formed the control group. At 3 +/- 1.5 years, recipient survival was lower (50% vs. 82%, p = 0.0053) and incidence of allograft vasculopathy was higher (50% vs. 22%, p = 0.05) in recipients of donor heart with LVWT > 1.4 cm as compared to LVWT <or= 1.4 cm. By Cox regression, donor LVWT > 1.4 cm (p = 0.003), recipient preoperative ventricular assist device (VAD) support (p = 0.04) and bypass time > 150 min (p = 0.05) were predictors of reduced survival. Our results suggest careful consideration of donor hearts with echocardiographic evidence of increased LVWT in the absence of hypovolemia, because they may be associated with poorer outcomes; such hearts should potentially be reserved only for the most desperately ill recipients.
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Affiliation(s)
- S S Kuppahally
- Department of Cardiac Transplant, Stanford University, Stanford, CA, USA.
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Lin SJ, Shyue SK, Hung YY, Chen YH, Ku HH, Chen JW, Tam KB, Chen YL. Superoxide Dismutase Inhibits the Expression of Vascular Cell Adhesion Molecule-1 and Intracellular Cell Adhesion Molecule-1 Induced by Tumor Necrosis Factor-α in Human Endothelial Cells Through the JNK/p38 Pathways. Arterioscler Thromb Vasc Biol 2005; 25:334-40. [PMID: 15576639 DOI: 10.1161/01.atv.0000152114.00114.d8] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective—
Expression of adhesion molecules on endothelial cells and subsequent leukocyte recruitment are critical early events in the development of atherosclerosis. We tried to study possible effects of Cu/Zn superoxide dismutase (SOD) on adhesion molecule expression and its underlying mechanism in the prevention and treatment of cardiovascular disorders.
Methods and Results—
Human aortic endothelial cells (HAECs) were transfected with adenovirus carrying the human SOD gene (AdSOD) to investigate whether SOD expression in HAECs attenuated tumor necrosis factor (TNF)-α–induced reactive oxygen species production and adhesion molecule expression and to define the mechanisms involved. SOD expression significantly suppressed TNF-α–induced expression of vascular cell adhesion molecule-1 and intercellular cell adhesion molecule-1 and reduced the binding of the human neutrophils to TNF-α–stimulated HAECs. SOD expression suppressed c-JUN N-terminal kinase and p38 phosphorylation. It also attenuated intracellular superoxide anion production and NADPH oxidase activity in TNF-α–treated HAECs.
Conclusions—
These results provide evidence that SOD expression in endothelial cells attenuates TNF-α–induced superoxide anion production and adhesion molecule expression, and that this protective effect is mediated by decreased JNK and p38 phosphorylation and activator protein-1 and nuclear factor κB inactivation. These results suggest that SOD has antiinflammatory properties and may play important roles in the prevention of atherosclerosis and inflammatory response.
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Affiliation(s)
- Shing-Jong Lin
- Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University, Taiwan, Republic of China
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Abstract
We examined the relationship between patterns of alcohol consumption and health care costs among adult members of the Kaiser Permanente Medical Care Program (KPMCP) in Northern California. A telephone survey of a random sample of the KPMCP membership aged 18 and over was conducted between June 1994 and February 1996 (n=10,175). The survey included questions on sociodemographic characteristics, general and mental health status, patterns of past and current alcohol consumption; inpatient and outpatient costs were obtained from Kaiser Permanentes cost management information system. Results showed that current non-drinkers with a history of heavy drinking had higher health costs than other non-drinkers and current drinkers. The per person per year costs for non-drinkers with a heavy drinking history were $2421 versus $1706 for other non-drinkers and $1358 for current drinkers in 1995 US dollars. A history of heavy drinking has a significant effect on costs after controlling for sociodemographic characteristics, health status and health practices. Current drinkers have the lowest costs, suggesting that they may be more likely than non-drinkers to delay seeking care until they are sick and require expensive medical care.
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Affiliation(s)
- E M Hunkeler
- Division of Research, Kaiser Permanente Medical Care Program, 3505 Broadway, 7th Floor, Oakland, CA 94611-5463, USA.
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Newacheck PW, Hung YY, Marchi KS, Hughes DC, Pitter C, Stoddard JJ. The impact of managed care on children's access, satisfaction, use, and quality of care. Health Serv Res 2001; 36:315-34. [PMID: 11409815 PMCID: PMC1089226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Abstract
OBJECTIVE To examine the impact of managed care on children's access, satisfaction, use, and quality of care using nationally representative household survey data. DATA SOURCE The 1996 Medical Expenditure Panel Survey (MEPS). STUDY DESIGN Bivariate and multivariate analyses are used to detect independent effects of managed care on access, satisfaction, utilization, and quality of pediatric health services. DATA COLLECTION/EXTRACTION METHODS Data were obtained from rounds 1, 2, and 3 of the 1996 MEPS. MEPS collects data on health care use, insurance, access, and satisfaction, along with basic demographic and health status information for a representative sample of the U. S. civilian, noninstitutionalized population. Our sample consists of 5,995 children between the ages of 0 and 17. FINDINGS Among the 18 outcome indicators examined, the bivariate analysis revealed only three statistically significant differences between children enrolled in managed care and children in traditional health plans: children enrolled in managed care were more likely to receive physician services, more likely to have access to office-based care during evening or weekend hours, and less likely to report being very satisfied with overall quality of care. However, after controlling for confounding factors, none of these differences remained statistically significant. CONCLUSIONS Our findings suggest that there are no statistically significant differences in self-reported outcomes for children enrolled in managed care and traditional health plans. This conclusion is provisional, however, because of limitations in the data set.
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Affiliation(s)
- P W Newacheck
- Institute for Health Policy Studies, San Francisco, CA 94118, USA
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Shang HM, Quan C, Tay CJ, Hung YY. Generation of carrier fringes in holography and shearography. Appl Opt 2000; 39:2638-2645. [PMID: 18345182 DOI: 10.1364/ao.39.002638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Double-exposure holography and double-exposure shearography are often used together with the carrier fringe technique, which requires additional shifting of the light source in a prescribed manner between exposures. In the holographic carrier fringe technique, difficulty in prescribing a suitable movement of the light source may be alleviated through visualization of the moiré fringes that are reconstructed by slight displacement of two overlaid families of ellipsoids in a holodiagram. Because shearography is the first differential of holography, it is often impractical to perform two successive optical differentiations on the ellipsoids to visualize the shearographic carrier fringes. A simple method of discerning holographic and shearographic carrier fringes is described. The method is based on the hyperboloids in a holodiagram that represent Young's (interference) fringes produced by the interference of two point sources. The hyperboloids are analogous to holographic carrier fringes, whereas the moiré patterns reconstructed from two overlaid hyperboloids are analogous to shearographic carrier fringes. Use of this method for explaining the formation of deformation fringes in plate bending, as well as the effect of light-source movement on the deformation fringes, is also illustrated.
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Affiliation(s)
- H M Shang
- Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore.
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Abstract
OBJECTIVE To assess the role health insurance plays in influencing access to care and use of services by children with special health care needs. METHODS We analyzed data on 57 553 children younger than 18 years old included in the 1994-1995 National Health Interview Survey on Disability. The survey obtained information on special health care needs, insurance status, and access to and use of health services. Bivariate and multivariate analyses were used to assess the association of insurance with several measures of access and utilization, including usual source of care, site of usual care, missed or delayed care, and use of ambulatory physician services. RESULTS Using the federal Maternal and Child Health Bureau definition of children with special health care needs, we estimate that 18% of US children under 18 years old had an existing special health care need in 1994-1995. An estimated 89% of these children had some form of health insurance coverage, most often private health insurance. Insured children were more likely than uninsured children to have a usual source of care (96.9% vs 79.2%). Among those with a usual source of care, insured children were more likely than uninsured children to have an identified regular clinician (87. 6% vs 80.7%). Insured children were less likely to report unmet health needs, including medical care (2.2% vs 10.5%), dental care (6. 1% vs 23.9%), prescriptions, and/or eyeglasses (3.1% vs 12.3%), and mental health care (.9% vs 3.4%). Insured children were also more likely to have a physician contact in the past year (89.3% vs 73.6%) and have more physician contacts on an annual basis (8.5 vs 4.1 contacts). Unexpectedly, no differences were found between insured and uninsured children in availability of after hours medical care (evenings and weekends) or satisfaction with care. We also found some modest differences in access between publicly and privately insured children. Privately insured children were more likely to have a usual source of care (97.6% vs 95.3%) and a regular clinician (91.0% vs 81.1%). Privately insured children were also less likely to report dissatisfaction with care at their usual site of care (14. 9% vs 21.0%) and have access to care on evenings and weekends (6.8% vs 13.4%). No substantial differences were found between privately and publicly insured children in prevalence of unmet health needs or delays in obtaining care due to cost. CONCLUSIONS This study illustrates the importance of health insurance for children with special health care needs. Continued efforts are needed to ensure that all children with special health care needs have insurance and that remaining access and utilization barriers for currently insured children with special health care needs are also addressed.
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Affiliation(s)
- P W Newacheck
- Institute for Health Policy Studies, San Francisco, CA 94118, USA.
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Newacheck PW, Hughes DC, Hung YY, Wong S, Stoddard JJ. The unmet health needs of America's children. Pediatrics 2000; 105:989-97. [PMID: 10742361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
OBJECTIVE Unmet need for health care is a critical indicator of access problems. Among children, unmet need for care has special significance inasmuch as the failure to obtain treatment can affect health status and functioning in the near- and long-term. The purpose of this study was to present current prevalence estimates and descriptive characteristics of children with unmet health needs using nationally representative household survey data. METHODS We analyzed 4 years of National Health Interview Survey data spanning 1993 through 1996. Our analysis included 97 206 children <18 years old. Measures of unmet need for medical care, dental care, prescription medications, and vision care were obtained from an adult household member (usually the mother) responding for the child. Bivariate and multivariate analyses were used to assess the degree to which unmet need was related to the demographic and socioeconomic characteristics of the child and family. RESULTS Overall, 7.3% (4.7 million) of US children experienced at least 1 unmet health care need. Dental care was the most prevalent unmet need. After adjustment for confounding factors, near-poor and poor children were both about 3 times more likely to have an unmet need as nonpoor children (adjusted odds ratio [95% confidence interval] = 2.89 [2.52, 3.32], 3.0 [2.53, 3.56], respectively). Uninsured children were also about 3 times more likely to have an unmet need as privately insured children (adjusted odds ratio [95% confidence interval] = 2. 92 [2.58, 3.32]). CONCLUSIONS Despite the nation's great wealth, unmet health needs remain prevalent among US children. A combined public policy that addresses financial and nonfinancial barriers to care is required to reduce the prevalence of unmet need for health care.
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Affiliation(s)
- P W Newacheck
- Institute for Health Policy Studies, University of California, San Francisco, CA 94143, USA
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Ueng YF, Liu C, Lai CF, Meng LM, Hung YY, Ueng TH. Effects of cadmium and environmental pollution on metallothionein and cytochrome P450 in tilapia. Bull Environ Contam Toxicol 1996; 57:125-131. [PMID: 8661470 DOI: 10.1007/s001289900165] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- Y F Ueng
- Institute of Toxicology, College of Medicine, National Taiwan University, 1 Jen Ai Road, Section 1, Taipei, Taiwan, Republic of China
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Abstract
An iteration algorithm for the analysis of speckle interference patterns is presented. First, four digitized phase-shifted patterns are locally averaged. The phase information is then extracted by the usual phase shift algorithm. The wrapped phase is in turn used to reconstruct four new phase-shifted patterns. These three steps form a cycle. Repetition of the three steps has a great effect on suppressing speckle noise. Theoretical study shows that the iterated phase converges to a perfect result under ideal conditions. In general, the iteration causes little error but improves the phase information a great deal. The signal-to-noise ratio rises when additional iterations are performed.
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Abstract
A novel edge extraction method that employs an active defocusing technique is presented. The method is based on the principle that a Laplacian-of-Gaussian (LOG) operation can be approximated by a Difference-of-Gaussian (DOG) operation. While such an operation is usually done in digital image processing, it can also be very effective conducted in a combination of optical techniques and digital processing. In this edge extraction method, a focused image of an object in a scene is first acquired. The image of the scene is then slightly defocused by changing the focal length of the camera. A real time subtraction operation is applied to subtract the defocused image from the previously acquired image. It produces a residual image that emphasizes abrupt intensity variations. An objective evaluation, called an edge index, is performed on the resulting image. The amount of defocusing is carefully adjusted according to this measurement so that a desired edge image is generated. Boundaries of objects can then be obtained by further enhancement of the edge image. Since this edge detection method is an optical-based process aided by digital processing, it is fast and relatively inexpensive.
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Affiliation(s)
- Q M Zhu
- Department of Mathematics and Computer Science, University of Nebraska, Omaha 68182
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Abstract
A fast technique for automatic 3-D shape measurement is proposed and verified by experiments. The technique, based on the principle of phase measurement of the deformed grating pattern which carries the 3-D information of the measured object, can automatically and accurately obtain the phase map or the height information of a measured object at every pixel point without assigning fringe orders and interpreting data in the regions between the fringe orders. Only one image pattern is sufficient for obtaining the phase map. In contrast to the fast Fourier transform based technique, the technique processes a fringe pattern in the real-signal domain instead of the frequency domain by using demodulation and convolution techniques, can process an arbitrary number of pixel points, and is much faster. Theoretical analysis, simulation results, and experimental results are presented.
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Abstract
This paper describes a new image-shearing camera which focuses two laterally sheared images at the film plane. With coherent illumination, this camera becomes a shearing interferometer, which directly measures the derivatives of the surface displacements. This strain measuring tool enjoys several advantages over the conventional, holographic, and speckle interferometry, namely, (1) better fringe quality (than speckle interferometry); (2) does not require special vibration isolation; (3) very simple optical setup; (4) direct determination of strains; and (5) extended controllable range of sensitivity.
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Hung YY, Turner JL, Tafralian M, Hovanesian JD, Taylor CE. Optical method for measuring contour slopes of an object. Appl Opt 1978; 17:128-131. [PMID: 20174364 DOI: 10.1364/ao.17.000128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This paper presents a new coherent optical method whereby the partial derivatives of the contour of an object are measured. The object to be studied is immersed in a refractive medium and is imaged by a camera with a shearing device. The processed photographic plate which has been doubly exposed in the image plane with the refractive medium changed between the exposures can be Fourier filtered to yield a fringe pattern depicting derivatives of the surface contour with respect to the direction of shearing. This new method enjoys the advantages of being simple and less demanding in vibration isolation, coherence of light source, and film resolution.
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Abstract
A time-averaged shadow-moiré method is presented which permits the determination of the amplitude distribution of the deflection of a plate in steady state vibration. No stroboscope is required, and the recording is done statically. The method is less sensitive than holographic methods and is therefore suitable for studying relatively large amplitudes.
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Abstract
An improved speckle-shearing interferometric method is presented that allows simultaneous determination of derivatives of surface displacements of a structure with respect to four different directions. The technique relaxes several limitations associated with conventional interferometry and thus is adaptable to nonlaboratory environments. The relevant theory is presented, and the method demonstrated by determining spatial derivatives of in-plane and out-of-plane displacements of statically loaded and vibrated structures.
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Abstract
A grid is projected onto an object and focused into a viewing camera which is offset from the angle of illumination. When the image is superimposed by double exposure or by filtering with the image of another object, contour-difference moiré fringes appear. By the use of two offset projectors, measurements of contour sums or contour doubling may be accomplished. The properties, limitations, sensitivity, and procedures are analyzed and discussed. The method lends itself to image enhancement and is extended to the study of vibration analysis in real time. In the latter application, time-average moiré fringes appear according to the zeroth-order Bessel function, which contains the modal amplitude function in its argument.
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