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Your search keyword '"YUAN, MEI-CHUN"' showing total 10 results
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10 results on '"YUAN, MEI-CHUN"'

2. Effects of shallow water bottom interface roughness and volume fluctuations on broadband pulse resolution

Author

Smith, Kevin B., Atchley, Anthony A., Engineering Acoustics Academic Group, Yuan, Mei-Chun, Smith, Kevin B., Atchley, Anthony A., Engineering Acoustics Academic Group, and Yuan, Mei-Chun

Abstract

Typical acoustic propagation in shallow water environments is dominated by bottom-interacting paths. The effects of rough bottom interfaces and sediment volume fluctuations are investigated using model simulations. A numerical study of low-frequency (approx. 200 Hz) broadband pulse propagation is presented and several characterizations of bottom factors are examined. In particular, the variations of the interface rms roughness and a volume fluctuation strength constant on the time resolution of the broadband pulse are investigated. It is shown that interface roughness is the dominant factor in the degradation of pulse resolution, http://archive.org/details/effectsofshallow109458294, Lieutenant Commander, Republic of China Navy, Approved for public release; distribution is unlimited.

Published
2012

4. Effects of shallow water bottom interface roughness and volume fluctuations on broadband pulse resolution

Author

Yuan, Mei-Chun, Smith, Kevin B., Atchley, Anthony A., and Engineering Acoustics Academic Group

Subjects
Scattering, Pulse Resolution, Beamforming, Underwater Acoustic Propagation, PE Model
Abstract

Typical acoustic propagation in shallow water environments is dominated by bottom-interacting paths. The effects of rough bottom interfaces and sediment volume fluctuations are investigated using model simulations. A numerical study of low-frequency (approx. 200 Hz) broadband pulse propagation is presented and several characterizations of bottom factors are examined. In particular, the variations of the interface rms roughness and a volume fluctuation strength constant on the time resolution of the broadband pulse are investigated. It is shown that interface roughness is the dominant factor in the degradation of pulse resolution http://archive.org/details/effectsofshallow109458294 Lieutenant Commander, Republic of China Navy Approved for public release; distribution is unlimited.

Published
1996

8. Effects of Shallow Water Bottom Interface Roughness and Volume Fluctuations on Broadband Pulse Resolution.

Author

NAVAL POSTGRADUATE SCHOOL MONTEREY CA, Yuan, Mei-Chun, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, and Yuan, Mei-Chun

Abstract

Typical acoustic propagation in shallow water environments is dominated by bottom-interacting paths. The effects of rough bottom interfaces and sediment volume fluctuations are investigated using model simulations. A numerical study of low-frequency (approx. 2OO Hz) broadband pulse propagation is presented and several characterizations of bottom factors are examined. In particular, the variations of the interface rms roughness and a volume fluctuation strength constant on the time resolution of the broadband pulse are investigated. It is shown that interface roughness is the dominant factor in the degradation of pulse resolution.

Published
1996

9. Effects of shallow water bottom interface roughness and volume fluctuations on broadband pulse resolution

Author

Smith, Kevin B., Atchley, Anthony A., Engineering Acoustics Academic Group, Yuan, Mei-Chun, Smith, Kevin B., Atchley, Anthony A., Engineering Acoustics Academic Group, and Yuan, Mei-Chun

Abstract

Typical acoustic propagation in shallow water environments is dominated by bottom-interacting paths. The effects of rough bottom interfaces and sediment volume fluctuations are investigated using model simulations. A numerical study of low-frequency (approx. 200 Hz) broadband pulse propagation is presented and several characterizations of bottom factors are examined. In particular, the variations of the interface rms roughness and a volume fluctuation strength constant on the time resolution of the broadband pulse are investigated. It is shown that interface roughness is the dominant factor in the degradation of pulse resolution

Published
1996

10. The risk of cataract associated with repeated head and neck CT studies: a nationwide population-based study.

Author

Yuan MK, Tsai DC, Chang SC, Yuan MC, Chang SJ, Chen HW, and Leu HB

Subjects
Adolescent, Adult, Case-Control Studies, Cataract epidemiology, Child, Female, Humans, Male, Middle Aged, Radiation Dosage, Risk, Taiwan epidemiology, Cataract etiology, Head and Neck Neoplasms diagnostic imaging, Tomography, X-Ray Computed adverse effects
Abstract

Objective: Medical radiation-induced cataracts, especially those resulting from head and neck CT studies, are an issue of concern. The current study aimed to determine the risk of cataract associated with repeated radiation exposure from head and neck CT., Materials and Methods: This study used information from a random sample of 2 million persons enrolled in the nationally representative Taiwan National Health Insurance Research Database. Exposed cases consisted of patients with head and neck tumor 10-50 years old who underwent at least one CT between 2000 and 2009. The nonexposed control group was composed of subjects who were never exposed to CT studies but who were matched by time of enrollment, age, sex, history of coronary artery disease, hypertension, and diabetes., Results: There were 2776 patients in the exposed group and 27,761 matched subjects in the nonexposed group. The exposed group had higher overall incidence of cataracts (0.97% vs 0.72%; adjusted hazard ratio [HR], 1.76; 95% CI, 1.18-2.63). Further stratifying the number of CT studies in the exposed group into one or two, three or four, and five or more revealed that cataract incidence increased gradually with increasing frequency of CT studies (0.79%, 0.93%, and 1.45%, respectively) (p=0.001, adjusted for trend). Radiation exposure due to repeated head and neck CT studies was independently associated with an increased risk of developing cataracts when the cumulative CT exposure frequency involved more than four studies (adjusted HR, 2.12; 95% CI, 1.09-4.14)., Conclusion: Repeated exposure to head and neck CT is significantly associated with increased risk of cataract.

Published
2013
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