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Search Results: 1 - 10 of 256130 matches for " K. Wang "
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Using Optimized Distributional Parameters as Inputs in a Sequential Unsupervised and Supervised Modeling of Sunspots Data  [PDF]
K. Mwitondi, J. Bugrien, K. Wang
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.67B007

Detecting naturally arising structures in data is central to knowledge extraction from data. In most applications, the main challenge is in the choice of the appropriate model for exploring the data features. The choice is generally poorly understood and any tentative choice may be too restrictive. Growing volumes of data, disparate data sources and modelling techniques entail the need for model optimization via adaptability rather than comparability. We propose a novel two-stage algorithm to modelling continuous data consisting of an unsupervised stage whereby the algorithm searches through the data for optimal parameter values and a supervised stage that adapts the parameters for predictive modelling. The method is implemented on the sunspots data with inherently Gaussian distributional properties and assumed bi-modality. Optimal values separating high from lows cycles are obtained via multiple simulations. Early patterns for each recorded cycle reveal that the first 3 years provide a sufficient basis for predicting the peak. Multiple Support Vector Machine runs using repeatedly improved data parameters show that the approach yields greater accuracy and reliability than conventional approaches and provides a good basis for model selection. Model reliability is established via multiple simulations of this type.

Estimation of Phosphorus Bioavailability in the Water Column of the Bronx River, New York  [PDF]
Jingyu Wang, Hari K. Pant
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.34040
Abstract: Phosphorus (P) is a primary limiting nutrient in rivers and streams, and excessive P results in eutrophication of freshwater systems, in turn, excessive algal growth/toxic algal blooms, oxygen depletion, and water quality degradation. This study analyzed P pool, and hydrolysis of organic P (OP) by native phosphatases (NPase) in the water samples collected in the Bronx River. The soluble reactive P (SRP) of most of the sites’ water collected in 2006 and 2007 were higher (average 67 μg?L–1 and 68 μg?L–1, respectively) than the US Environmental Protection Agency’s (EPA) standard of 15 μg?L–1. The SRP% (SRP/TP%) average was 27% in 2006, much lower than in 2007 of SRP% average 83%. The OP% (OP/TP%) average was 73% in 2006, which was much higher than the OP% in 2007 (which was only 17%). The SRP concentrations and distributions (%), and the total P (TP) concentrations were in substantial amounts compared with other rivers. The NPase hydrolyzed OP % was up to 100% in 2006 and 2007 water samples. The average of NPase% was 59% in 2006 and 73% in 2007. The NPase average concentrations were 348 μg?L–1 in 2006, and 175 μg?L–1 in 2007. The NPase hydrolyzed up to 100% of OP% in the Bronx River water samples at 37?C, indicating a potential threat of eutrophication of freshwater systems as the global rise in temperature may continue to occur.
Evaluation of the tropospheric flows to a major Southern Hemisphere stratospheric warming event using NCEP/NCAR Reanalysis data with a PSU/NCAR nudging MM5V3 model
K. Wang
Atmospheric Chemistry and Physics Discussions , 2008,
Abstract: Previous studies of the exceptional 2002 Southern Hemisphere (SH) stratospheric warming event lead to some uncertainty, namely the question of whether excessive heat fluxes in the upper troposphere and lower stratosphere are a symptom or cause of the 2002 SH warming event. In this work, we use a hemispheric version of the MM5 model with nudging capability and we devised a novel approach to separately test the significance of the stratosphere and troposphere for this year. We paired the flow conditions from 2002 in the stratosphere and troposphere, respectively, against the conditions in 1998 (a year with displaced polar vortex) and in 1948 (a year with strong polar vortex that coincided with the geographical South Pole). Our experiments show that the flow conditions from below determine the stratospheric flow features over the polar region. Regardless of the initial stratospheric conditions in 1998 or 1948, when we simulated these past stratospheres with the troposphere/lower stratosphere conditions constrained to 2002 levels, the simulated middle stratospheres resemble those observed in 2002 stratosphere over the polar region. On the other hand, when the 2002 stratosphere was integrated with the troposphere/lower stratosphere conductions constrained to 1948 and 1998, respectively, the simulated middle stratospheric conditions over the polar region shift toward those of 1948 and 1998. Thus, our experiments further support the wave-forcing theory as the cause of the 2002 SH warming event.
Natural Quark Mass Patterns
K. Wang
Physics , 1996, DOI: 10.1103/PhysRevD.54.5750
Abstract: We incorporate the idea of natural mass matrices into the construction of phenomenologically viable quark mass matrix patterns. The general texture pattern for natural Hermitian mass matrices is obtained and several applications of this result are made.
A Practical Target Tracking Technique in Sensor Network Using Clustering Algorithm  [PDF]
Luke K. Wang, Chien-Chang Wu
Wireless Sensor Network (WSN) , 2012, DOI: 10.4236/wsn.2012.411038
Abstract: Sensor network basically has many intrinsic limitations such as energy consumption, sensor coverage and connectivity, and sensor processing capability. Tracking a moving target in clusters of sensor network online with less complexity algorithm and computational burden is our ultimate goal. Particle filtering (PF) technique, augmenting handoff and K-means classification of measurement data, is proposed to tackle the tracking mission in a sensor network. The handoff decision, an alternative to multi-hop transmission, is implemented for switching between clusters of sensor nodes through received signal strength indication (RSSI) measurements. The measurements being used in particle filter processing are RSSI and time of arrival (TOA). While non-line-of-sight (NLOS) is the dominant bias in tracking estimation/accuracy, it can be easily resolved simply by incorporating K-means classification method in PF processing without any priori identification of LOS/NLOS. Simulation using clusters of sensor nodes in a sensor network is conducted. The dependency of tracking performance with computational cost versus number of particles used in PF processing is also investigated.
Land-Use and Land-Cover Change in the Sahel Area of Keita Valley, Republic of Niger  [PDF]
Boureima K. Yacouba, Zhanqi Wang, Yamba Boubacar
Journal of Environmental Protection (JEP) , 2016, DOI: 10.4236/jep.2016.74050

Keita region is largely dependent on agriculture and livestock as the main economic activities with about 90% of the population are actively engaged in rural activities. However, these activities are dwindling at a rate that corresponds with increase in the ecosystem’s vulnerability. The following study focused on land use/land cover change in Keita. The study aims to better understand changes through diachronic analysis by integrating remote sensing and GIS. There was an interpretation of satellites imagery (1975, 1984, 1995 and 2001), and statistical techniques were used to provide quantitative analysis of land use/cover change information and drivers underlying in the study area. The changes are affected by simultaneous influence of successive droughts (1973-1974 and 1983-1984) that have transformed ecological balance, anthropogenic and livestock impacts, ecosystems degradation and policies. The land use temporal dynamics are undergone continual degradation of vegetation, the state of land saturation results in conflicts between farmer and herders, the drop in grazing areas, bare land expansion, the erosion of stream bed, and the decline in flooded plain.

The role of XPC protein deficiency in tobacco smoke-induced DNA hypermethylation of tumor suppressor genes  [PDF]
Gan Wang, Le Wang, Vanitha Bhoopalan, Yue Xi, Deepak K. Bhalla, David Wang, Xiaoxin S. Xu
Open Journal of Genetics (OJGen) , 2013, DOI: 10.4236/ojgen.2013.34032

DNA hypermethylation of tumor suppressor genes has been frequently observed in cancer patients, and therefore, may provide a valuable biomarker for cancer prevention and treatment. DNA hypermethylation may also provide an important mechanism in cancer progression. Lung cancer is strongly associated with exposure to environmental carcinogens, especially tobacco smoke. DNA damage generated by tobacco smoke is believed to play an important role in lung cancer development. XPC is a DNA damage recognition protein required for DNA repair and other DNA damage responses and attenuated XPC protein levels have been detected in many lung cancer patients. We studied the role of XPC protein deficiency in tobacco smoke-caused DNA hypermethylation of important tumor suppressor genes. Using both normal human fibroblasts (NF) and XPC-deficient hu man fibroblasts (XPC), our DNA methylation studies demonstrated that the XPC deficiency caused elevated levels of DNA hypermethylation in both Brca1 and Mlh1 tumor suppressor genes following exposure to tobacco smoke condensate (TSC). The results of our ChIP studies revealed that the XPC deficiency led to an increased binding of DNA methyltransferase 3A (DNMT3A) at the promoter region CpG island-containing sequences of these genes under the TSC treatment; however, this increase was partially diminished with prior treatment with caffeine. The results of our immuno-precipitation (IP) studies demonstrated a protein-protein interaction of the ATR with DNMT3A. Our western blots revealed that the

XPC deficiency caused an increase in TSC-induced ATR phosphorylation at serine 428, an indicator of ATR activation. All these results suggest that XPC deficiency causes an accelerated DNA hypermethylation in important tumor suppressor genes under tobacco smoke exposure and activation of the ATR signaling pathway is involved in this DNA hypermethylation process.

THz Oscillations in a GaN Based Planar Nano-Device  [PDF]
K. Y. Xu, Y. N. Wang, Z. N. Wang, J. W. Xiong, G. Wang
Journal of Computer and Communications (JCC) , 2013, DOI: 10.4236/jcc.2013.17012

Gunn oscillations in a GaN based planar nano-device have been studied by ensemble Monte Carlo (EMC) method. Simulation results show that when the channel length of the device reduces to 450 nm, THz oscillations (about 0.3 THz) can be obtained. Also the phase of the oscillations can be controlled by the initial conditions that excite the Gunn domains. Moreover, through adjusting the phase difference between the oscillations in a double-channels device, which attained by parallel connecting two single-channel devices, the frequency of the device shifts from 0.3 THz to 0.6 THz. This phenomenon remains in devices with shorter channel-length, unless the channel-length is too short to support Gunn oscillations. The possible underlying mechanisms are also discussed.

Generation of predictive price and trading volume patterns in a model of dynamically evolving free market supply and demand
J. K. Wang
Discrete Dynamics in Nature and Society , 2001, DOI: 10.1155/s1026022601000048
Abstract: I present a model of stock market price fluctuations incorporating effects of share supply as a history-dependent function of previous purchases and share demand as a function of price deviation from moving averages. Price charts generated show intervals of oscillations switching amplitude and frequency suddenly in time, forming price and trading volume patterns well-known in market technical analysis. Ultimate price trends agree with traditional predictions for specific patterns. The consideration of dynamically evolving supply and demand in this model resolves the apparent contradiction with the Efficient Market Hypothesis: perceptions of imprecise equity values by a world of investors evolve over non-negligible periods of time, with dependence on price history.
Comparison of Admittance Plots for Glass Carbon (GC) and Edge Plane Pyrolytie Graphite (EPPG) Electrodes in Three Typical Kinds of Electrolytes
Ding,K.; Wang,Q.;
Portugaliae Electrochimica Acta , 2007,
Abstract: electrochemical response of glass carbon (gc) and edge plane pyrolytic graphite (eppg) electrodes was investigated using electrochemical impedance spectroscopy (eis) method in three kinds of electrolytes, i.e., 0.1 m na2so4 (aqueous solution), 0.1 m tetraethylammonium perchlorate (teap) (acetonitrile solution) and pure room temperature ionic liquids (rtils) of 1-ethyl-3-methylimidazolium tetrafluorobroate (emibf4). the marked difference in the admittance plots was exhibited by the gc electrode, suggesting that the double layer occurring on gc electrode differed from each other when immersed in different electrolytes, indirectly proving the meso-porosity structure of gc electrode. while for eppg electrode, similar results were obtained in these three selected electrolytes, which were interpreted by the "defects" in eppg electrode.
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