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Search Results: 1 - 10 of 78338 matches for " Ligang Chen "
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Experimental Study of Multi Optical Parameter Imaging Technology under the Fog Condition  [PDF]
Weiwei Feng, Ligang Chen
Optics and Photonics Journal (OPJ) , 2017, DOI: 10.4236/opj.2017.78B012
Abstract:
A multi optical parametric imaging system is introduced and established in order to improve the contrast of object in the fog. A few targets are observed in the fog weather based on the system level radiation model of multi optical parametric imaging and the calibrated model parameters. The results show that the building’s windows can be distinguished clear in the linear polariza-tion, circular polarization and angle of polarization images because of the strong reflected polarization light of the glass; The vehicles in intersection can hardly be seen in the intensity image, and it is fuzzy in degree of linear polarization and angle of polarization image because of the doped polarization information of trees near in fog; The circular polarization image raises the contrast of the vehicles by 20% because the circle polarization of the trees is less in the fog.
Two-Dimensional Diffusion in the Presence of Topological Disorder
Ligang Chen,Michael W. Deem
Physics , 2003, DOI: 10.1103/PhysRevE.68.021107
Abstract: How topological defects affect the dynamics of particles hopping between lattice sites of a distorted, two-dimensional crystal is addressed. Perturbation theory and numerical simulations show that weak, short-ranged topological disorder leads to a finite reduction of the diffusion coefficient. Renormalization group theory and numerical simulations suggest that longer-ranged disorder, such as that from randomly placed dislocations or random disclinations with no net disclinicity, leads to subdiffusion at long times.
Strategies for High-Throughput, Templated Zeolite Synthesis
Ligang Chen,Michael W. Deem
Physics , 2002, DOI: 10.1080/00268970110118222
Abstract: How best to design and redesign high-throughput experiments for zeolite synthesis is addressed. A model that relates materials function to chemical composition of the zeolite and the structure directing agent is introduced. Using this model, several Monte Carlo-like design protocols are evaluated. Multi-round protocols are found to be effective, and strategies that use a priori information about the structure-directing libraries are found to be the best.
Reaction, Levy Flights, and Quenched Disorder
Ligang Chen,Michael W. Deem
Physics , 2001, DOI: 10.1103/PhysRevE.65.011109
Abstract: We consider the A + A --> emptyset reaction, where the transport of the particles is given by Levy flights in a quenched random potential. With a common literature model of the disorder, the random potential can only increase the rate of reaction. With a model of the disorder that obeys detailed balance, however, the rate of reaction initially increases and then decreases as a function of the disorder strength. The physical behavior obtained with this second model is in accord with that for reactive turbulent flow, indicating that Levy flight statistics can model aspects of turbulent fluid transport.
Monte Carlo Methods for Small Molecule High-Throughput Experimentation
Ligang Chen,Michael W. Deem
Physics , 2001,
Abstract: By analogy with Monte Carlo algorithms, we propose new strategies for design and redesign of small molecule libraries in high-throughput experimentation, or combinatorial chemistry. Several Monte Carlo methods are examined, including Metropolis, three types of biased schemes, and composite moves that include swapping or parallel tempering. Among them, the biased Monte Carlo schemes exhibit particularly high efficiency in locating optimal compounds. The Monte Carlo strategies are compared to a genetic algorithm approach. Although the best compounds identified by the genetic algorithm are comparable to those from the better Monte Carlo schemes, the diversity of favorable compounds identified is reduced by roughly 60%.
Outflow Vessel in the Plane of Main Vortex of Large Cerebral Aneurysms: A Study of Hemodynamic Analyses  [PDF]
Hao Li, Tangming Peng, Jing Wu, Changren Huang, Yong Jiang, Ligang Chen
Neuroscience & Medicine (NM) , 2015, DOI: 10.4236/nm.2015.62012
Abstract:
Purpose: This study was designed to quantify and characterize the variations of hemodynamic parameters for those large cerebral aneurysms with outflow vessel in the plane of main vortex. Materials and Methods: A total of 19 consecutive patients with large cerebral aneurysms were constructed with the data of digital subtraction angiography. Those large cerebral aneurysms with outflow vessel in the plane of main vortex were included. Blood flow was hypothesized to be laminar and incompressible and blood Newtonian fluid. Computational fluid dynamics ICEM and Fluent software were used to simulate the computational hemodynamics of large cerebral aneurysms. Results: Hemodynamics parameters result of computational fluid dynamics showed that the velocity in the aneurysm neck, impact fields and the origin area of outflow vessels was obvious higher than that in the aneurysm sac and aneurysm dome. Wall shear stress was obvious higher in aneurysm neck, impact fields and the origin area of outflow vessels than that in the aneurysm sac and aneurysm dome. Conclusions: The location of outflow vessel played an impact on the level of blood flow within aneurysm sac for those large cerebral aneurysms with outflow vessel in the plane of main vortex.
Disorder-Induced Time-Dependent Diffusion in Zeolites
Ligang Chen,Marco Falcioni,Michael W. Deem
Physics , 1999,
Abstract: We suggest that disordered framework aluminums and non-framework cations can create a disordered electrostatic potential in zeolites that can lead to a discrepancy between diffusivities measured by microscopic and macroscopic experimental techniques. We calculate the value of the discrepancy and the characteristic time scale at which it occurs for several ionic and polarizable species diffusing in zeolites. For ionic species, a discrepancy is almost inevitable. For polarizable species, a significant discrepancy may occur in some zeolites only for long alkanes or large species such as benzene.
RETRACTED: Hemodynamic Features of Unruptured Cerebral Aneurysms before Rupture: A CFD Study  [PDF]
Hao Li, Ligang Chen, Changren Huang, Yong Jiang, Weifeng Wan, Jinghu Dong, Tangming Peng
Computational Molecular Bioscience (CMB) , 2015, DOI: 10.4236/cmb.2015.51002
Abstract: Short Retraction Notice The paper does not meet the standards of \"Computational Molecular Bioscience\". This article has been retracted to straighten the academic record. In making this decision the Editorial Board follows COPE's Retraction Guidelines. The aim is to promote the circulation of scientific research by offering an ideal research publication platform with due consideration of internationally accepted standards on publication ethics. The Editorial Board would like to extend its sincere apologies for any inconvenience this retraction may have caused. Editor guiding this retraction: Dr. Christo Z. Christov (EiC of CMB) The full retraction notice in PDF is preceding the original paper, which is marked \"RETRACTED\".
Roller Bearing Fault Diagnosis Based on Nonlinear Redundant Lifting Wavelet Packet Analysis
Lixin Gao,Zijing Yang,Ligang Cai,Huaqing Wang,Peng Chen
Sensors , 2011, DOI: 10.3390/s110100260
Abstract: A nonlinear redundant lifting wavelet packet algorithm was put forward in this study. For the node signals to be decomposed in different layers, predicting operators and updating operators with different orders of vanishing moments were chosen to take norm ?of the scale coefficient and wavelet coefficient acquired from decomposition, the predicting operator and updating operator corresponding to the minimal norm value were used as the optimal operators to match the information characteristics of a node. With the problems of frequency alias and band interlacing in the analysis of redundant lifting wavelet packet being investigated, an improved algorithm for decomposition and node single-branch reconstruction was put forward. The normalized energy of the bottommost decomposition node coefficient was calculated, and the node signals with the maximal energy were extracted for demodulation. The roller bearing faults were detected successfully with the improved analysis on nonlinear redundant lifting wavelet packet being applied to the fault diagnosis of the roller bearings of the finishing mills in a plant. This application proved the validity and practicality of this method.
The Effect of Maize Plumule Extracts on Rat Mammary Gland Hyperplasia
Ligang Tang,Wuqing Ouyang,Dongying Yang,Yunjia Liu,Hong Chen
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.1995.1999
Abstract: The goal of this study was to examine the effect of maize plumule extracts on mammary gland tissue and serum hormone levels in SD rats suffering from mammary gland hyperplasia and to investigate the mechanism by which maize plumule extracts inhibit mammary gland hyperplasia. About 56 rats were subcutaneously injected with progesterone combined with estradiol benzoate for the induction of mammary gland hyperplasia and were then randomly divided into 7 groups. Maize plumule extracts were subsequently given to the rats at doses of 0, 1.25, 2.5, 5, 10, 20 and 40 mg kg-1 daily for 20 days. Following treatment, hormone levels in the blood were measured and the morphology of the rat mammary glands was observed by microscopy. Results showed that high doses of maize plumule extracts significantly improved the morphology of lesional tissue and significantly reduced the levels of Follicle-Stimulating Hormone (FSH), serum Estradiol (E2) and Testosterone (T) in the serum and increased the levels of Prolactin (PRL) and serum Luteinizing Hormone (LH). However, the treatment did not have a substantial effect on serum Progesterone (P) levels. It can be concluded that maize plumule extracts containing rich adenine derivatives administered at doses of 2.5-40 mg/kg/day could effectively prevent and treat rat mammary gland hyperplasia.
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