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Your search keyword '"Yan, Shikui"' showing total 35 results
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35 results on '"Yan, Shikui"'

2. Simultaneous near-infrared diffusive light and ultrasound imaging

Author

Chen, Nan Guang, Guo, Puyun, Yan, Shikui, Piao, Daqing, and Zhu, Quing

Subjects
Near infrared spectroscopy -- Testing, Diffusion -- Research, Ultrasound imaging -- Research, Astronomy, Physics
Abstract

We have constructed a near-real-time combined imager suitable for simultaneous ultrasound and near-infrared diffusive light imaging and coregistration. The imager consists of a combined hand-held probe and the associated electronics for data acquisition. A two-dimensional ultrasound array is deployed at the center of the combined probe, and 12 dual-wavelength laser source fibers (780 and 830 nm) and 8 optical detector fibers are deployed at the periphery. We have experimentally evaluated the effects of missing optical sources in the middle of the combined probe on the accuracy of the reconstructed optical absorption coefficient and assessed the improvements of a reconstructed absorption coefficient with the guidance of the coregistered ultrasound. The results have shown that, when the central ultrasound array area is in the neighborhood of 2 cm x 2 cm, which corresponds to the size of most commercial ultrasound transducers, the optical imaging is not affected. The results have also shown that the iterative inversion algorithm converges quickly with the guidance of a priori three-dimensional target distribution, and only one iteration is needed to reconstruct an accurate optical absorption coefficient. OCIS codes: 170.0170, 170.3010, 170.5270, 170.7170, 170.3830.

Published
2001

3. Noise silencing technology for manifold flow noise based on ANSYS fluent

Author

Yan Shikui, Yong Jiang, Liyu Huang, Enbin Liu, and Shanbi Peng

Subjects
Engineering, 020209 energy, Noise reduction, Acoustics, Energy Engineering and Power Technology, 02 engineering and technology, 01 natural sciences, law.invention, Physics::Fluid Dynamics, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Sound pressure, 010301 acoustics, Muffler, geography, geography.geographical_feature_category, business.industry, Geotechnical Engineering and Engineering Geology, Inlet, Noise, Fuel Technology, Transmission (telecommunications), business, Manifold (fluid mechanics), Large eddy simulation
Abstract

Fluid dynamic noise, namely, flow noise, produced by eddy disturbances and friction along the pipe walls becomes a significant problem in a natural gas transmission and distribution station. The Sound Pressure Level (SPL) distribution of the manifold flow noise is studied based on a theoretical method that combines large eddy simulations with the Ffowcs Williams–Hawkings (FW–H) acoustic analogy theory. The results shows that decreased with the inlet pipe diameter, the acoustic energy and the SPL of the flow noise at the end of the inlet pipe gradually increased. A small-hole muffler is designed and installed to address the manifold flow noise, and their noise reduction effects are subsequently analyzed. The results show that the small-hole muffler effectively reduced low-frequency noise up to 37.4 dB, and the mean noise reduction is about 20.9 dB.

Published
2016

4. Large Eddy Simulation and FW-H Acoustic Analogy of Flow-Induced Noise in Elbow Pipe

Author

Liyu Huang, Di Wang, Yan Shikui, and Enbin Liu

Subjects
Computational Mathematics, Noise, medicine.anatomical_structure, Flow (mathematics), Acoustics, Elbow, medicine, Environmental science, General Materials Science, General Chemistry, Electrical and Electronic Engineering, Condensed Matter Physics, Large eddy simulation
Published
2015

6. Cancellation of coherent artifacts in optical coherence tomography imaging

Author

Piao, Daqing, Zhu, Quing, Dutta, Niloy K., Yan, Shikui, and Otis, Linda L.

Subjects
Optics -- Research, Coherence (Optics) -- Analysis, Optical tomography -- Analysis, Astronomy, Physics
Abstract

Coherent artifacts in optical coherence tomography (OCT) images can severely degrade image quality by introducing false targets if no targets are present at the artifact locations. Coherent artifacts can also add constructively or destructively to the targets that are present at the artifact locations. This constructive or destructive interference will result in cancellation of the true targets or in display of incorrect echo amplitudes of the targets. We introduce the use of a nonlinear deconvolution algorithm, CLEAN, to cancel coherent artifacts in OCT images of extracted human teeth. The results show that CLEAN can reduce the coherent artifacts to the noise background, sharpen the air-enamel and enamel-dentin interfaces, and improve the image contrast. OCIS codes: 170.4500, 170.3880, 170.3890, 170.1850.

Published
2001

12. A photoacoustic imaging system employing a curved-phased ultrasonic array and parallel electronics

Author

Oraevsky, Alexander A., Wang, Lihong V., Maurudis, Anastasios, Huang, Fei, Guo, Puyun, Yan, Shikui, Castillo, Diego, Zhu, Quing, Oraevsky, Alexander A., Wang, Lihong V., Maurudis, Anastasios, Huang, Fei, Guo, Puyun, Yan, Shikui, Castillo, Diego, and Zhu, Quing

Abstract

Real-time photoacoustic imaging requires ultrasonic array receivers and parallel data acquisition systems for the simultaneous detection of weak photoacoustic signals. In this paper, we introduce a newly completed ultrasonic receiving array system and report preliminary results of our measured point spread function. The system employs a curved ultrasonic phased array consisting of 128-elements, which span a quarter of a complete circle. The center frequency of the array is 5 MHz and the bandwidth is greater than 60%. In order to maximize the signal-to-noise ratio for photoacoustic signal detection, we utilized special designs for the analog front-end electronics. First, the 128 transducer-element signals were routed out using a 50-Ohm impedance matching PCB board to sustain signal integrity. We also utilize 128 low-noise pre-amplifiers, connected directly to the ultrasonic transducer, to amplify the weak photoacoustic signals before they were multiplexed to a variable-gain multi-stage amplifier chain. All front-end circuits were placed close to the transducer array to minimize signal lose due to cables and therefore improve the signal-to-noise ratio. Sixteen analog-to-digital converters were used to sample signals at a rate of 40 mega-samples per second with a resolution of 10-bits per sample. This allows us to perform a complete electronic scan of all 128 elements using just eight laser pulses.

Published
2006

35. Fluorescence-enhanced optical tomography and nuclear imaging system for small animals

Author

Tan, I-Chih, Lu, Yujie, Darne, Chinmay, Rasmussen, John C., Zhu, Banghe, Azhdarinia, Ali, Yan, Shikui, Smith, Anne M., and Sevick-Muraca, Eva M.

Abstract

Near-infrared (NIR) fluorescence is an alternative modality for molecular imaging that has been demonstrated in animals and recently in humans. Fluorescence-enhanced optical tomography (FEOT) using continuous wave or frequency domain photon migration techniques could be used to provide quantitative molecular imaging in vivo if it could be validated against "gold-standard," nuclear imaging modalities, using dual-labeled imaging agents. Unfortunately, developed FEOT systems are not suitable for incorporation with CT/PET/SPECT scanners because they utilize benchtop devices and require a large footprint. In this work, we developed a miniaturized fluorescence imaging system installed in the gantry of the Siemens Inveon PET/CT scanner to enable NIR transillumination measurements. The system consists of a CCD camera equipped with NIR sensitive intensifier, a diode laser controlled by a single board compact controller, a 2-axis galvanometer, and RF circuit modules for homodyne detection of the phase and amplitude of fluorescence signals. The performance of the FEOT system was tested and characterized. A mouse-shaped solid phantom of uniform optical properties with a fluorescent inclusion was scanned using CT, and NIR fluorescence images at several projections were collected. The method of high-order approximation to the radioactive transfer equation was then used to reconstruct the optical images. Dual-labeled agents were also used on a tumor bearing mouse to validate the results of the FEOT against PET/CT image. The results showed that the location of the fluorophore obtained from the FEOT matches the location of tumor obtained from the PET/CT images. Besides validation of FEOT, this hybrid system could allow multimodal molecular imaging (FEOT/PET/CT) for small animal imaging.

Published
2012
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