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Search Results: 1 - 10 of 42415 matches for " Han Q. Le "
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Semiconductor Laser Multi-Spectral Sensing and Imaging
Han Q. Le,Yang Wang
Sensors , 2010, DOI: 10.3390/s100100544
Abstract: Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.
Literature Review on Diversification Strategy, Enterprise Core Competence and Enterprise Performance  [PDF]
Han Le
American Journal of Industrial and Business Management (AJIBM) , 2019, DOI: 10.4236/ajibm.2019.91008
Abstract: Diversification is a strategic choice for enterprise expansion. Looking at the world, American companies in the 1960s and 1970s opened up a diversified path through large-scale mergers and acquisitions. However, by the 1980s and 1990s, American companies began to change from diversification to specialization, gradually returning to their main business, and the adjustment of this phenomenon made the performance of those companies significantly improved. Since then, how should companies abandon the choice of specialization and diversification strategy, and whether diversification is beneficial or unfavorable to corporate performance have become topics that domestic and foreign scholars are eager to study. Based on the concept, motivation and type of diversification strategy, this paper sorts out the relationship between corporate diversification strategy and corporate performance in domestic and foreign literatures. It is found that there is still no definitive answer to whether diversification strategy is beneficial to corporate performance. There are four different relationships: positive correlation, negative correlation and no significant correlation, and nonlinear correlation. The core competence of an enterprise is the fundamental support of diversified business operations and a deep-seated factor in the formulation and implementation of diversified business strategies. Research on the core competence of enterprises as a regulation or mediator of the relationship between diversification strategy and firm performance is still
Severe Plastic Deformation of Steel Induced by Ultrasonic Vibrations  [PDF]
C. Xu,Y. Cui,Q. Han
Open Journal of Metal (OJMetal) , 2013, DOI: 10.4236/ojmetal.2013.31001
Abstract: High-intensity ultrasonic vibration was focused on the tip of conical steel specimens to induce severe plastic deformation at room temperature. We found, for the first time, that grain size smaller than 200 nm was obtained. Furthermore, the sharp tip of the conical specimen became umbrella-shaped or disk-shaped. The tip size changed from 0.5 mm diameter to a disk about 5 mm diameter, representing a large amount of plastic deformation in the metal at the tip of the conical specimen.
Severe Plastic Deformation of Steel Induced by Ultrasonic Vibrations  [PDF]
C. Xu, Y. Cui, Q. Han
Open Journal of Metal (OJMetal) , 2013, DOI: 10.4236/ojmetal.2013.31001
Abstract:  

High-intensity ultrasonic vibration was focused on the tip of conical steel specimens to induce severe plastic deformation at room temperature. We found, for the first time, that grain size smaller than 200 nm was obtained. Furthermore, the sharp tip of the conical specimen became umbrella-shaped or disk-shaped. The tip size changed from 0.5 mm diameter to a disk about 5 mm diameter, representing a large amount of plastic deformation in the metal at the tip of the conical specimen.

The Colored Jones Polynomial and the A-Polynomial of Knots
Thang T. Q. Le
Mathematics , 2004,
Abstract: We study relationships between the colored Jones polynomial and the A-polynomial of a knot. We establish for a large class of 2-bridge knots the AJ conjecture (of Garoufalidis) that relates the colored Jones polynomial and the A-polynomial. Along the way we also calculate the Kauffman bracket skein module of all 2-bridge knots. Some properties of the colored Jones polynomial of alternating knots are established.
On the convergence of the Ohta-Kawasaki Equation to motion by nonlocal Mullins-Sekerka Law
Nam Q. Le
Mathematics , 2009,
Abstract: In this paper, we establish the convergence of the Ohta-Kawasaki equation to motion by nonlocal Mullins-Sekerka law on any smooth domain in space dimensions $N\leq 3$. These equations arise in modeling microphase separation in diblock copolymers. The only assumptions that guarantee our convergence result are $(i)$ well-preparedness of the initial data and $(ii)$ smoothness of the limiting interface. Our method makes use of the "Gamma-convergence" of gradient flows scheme initiated by Sandier and Serfaty and the constancy of multiplicity of the limiting interface due to its smoothness. For the case of radially symmetric initial data without well-preparedness, we give a new and short proof of the result of M. Henry for all space dimensions. Finally, we establish transport estimates for solutions of the Ohta-Kawasaki equation characterizing their transport mechanism.
On the Asymptotic Limit of the Cahn-Hilliard Equation
Nam Q. Le
Mathematics , 2009,
Abstract: This paper has been withdrawn by the author due to a coming paper completely superseding it.
On the second inner variation of the Allen-Cahn Functional and its applications
Nam Q. Le
Mathematics , 2010,
Abstract: In this paper, we study the relation between the second inner variations of the Allen-Cahn functional and its Gamma-limit, the area functional. Our result implies that the Allen-Cahn functional only approximates well the area functional up to the first order. However, as an application of our result, we prove, assuming the single-multiplicity property of the limiting energy, that the Morse indices of critical points of the Allen-Cahn functional are bounded from below by the Morse index of the limiting minimal hypersurface.
Growth of regulators in finite abelian coverings
Thang T. Q. Le
Mathematics , 2012, DOI: 10.2140/agt.2013.13.2383
Abstract: We show that the regulator, which is the difference between the homology torsion and the combinatorial Ray-Singer torsion, of fnite abelian coverings of a fixed complex has sub-exponential growth rate.
On Kauffman Bracket Skein Modules at Root of Unity
Thang T. Q. Le
Mathematics , 2013,
Abstract: We reprove and expand results of Bonahon and Wong on central elements of the Kauffman bracket skein modules at root of 1 and on the existence of the Chebyshev homomorphism, using elementary skein methods.
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