Showing papers by "Clarkson University published in 2003"
TL;DR: This three part series of papers is to provide a systematic and comparative study of various diagnostic methods from different perspectives and broadly classify fault diagnosis methods into three general categories and review them in three parts.
2,263 citations
TL;DR: This final part discusses fault diagnosis methods that are based on historic process knowledge that need to be addressed for the successful design and implementation of practical intelligent supervisory control systems for the process industries.
1,902 citations
TL;DR: This part of the paper reviews qualitative model representations and search strategies used in fault diagnostic systems and broadly classify them as topographic and symptomatic search techniques.
1,415 citations
TL;DR: It is shown that the immunization threshold is dramatically reduced with the suggested strategy, for all studied cases, and analytically the critical threshold for complete immunization is studied.
Abstract: We present an effective immunization strategy for computer networks and populations with broad and, in particular, scale-free degree distributions. The proposed strategy, acquaintance immunization, calls for the immunization of random acquaintances of random nodes (individuals). The strategy requires no knowledge of the node degrees or any other global knowledge, as do targeted immunization strategies. We study analytically the critical threshold for complete immunization. We also study the strategy with respect to the susceptible-infected-removed epidemiological model. We show that the immunization threshold is dramatically reduced with the suggested strategy, for all studied cases.
1,092 citations
TL;DR: In this paper, the authors examined the factor analysis of matrices where the proportion of signal and noise is very different in different columns (variables) and found that if a few weak variables are scaled to too high a weight in the analysis, the errors in computed factors would grow, possibly obscuring the weakest factor(s) by the increased noise level.
554 citations
01 Apr 2003
TL;DR: Stable concentrated aqueous dispersions of silver nanoparticles of narrow size distribution were prepared by reducing silver nitrate solutions with ascorbic acid in the presence of Daxad 19 (sodium salt of a high-molecular-weight naphthalene sulfonate formaldehyde condensate) as stabilizing agent.
Abstract: Stable concentrated aqueous dispersions of silver nanoparticles of narrow size distribution were prepared by reducing silver nitrate solutions with ascorbic acid in the presence of Daxad 19 (sodium salt of a high-molecular-weight naphthalene sulfonate formaldehyde condensate) as stabilizing agent. The latter has excellent ability to prevent the aggregation of nanosize silver at high ionic strength and high concentration of metal (up to 0.3 mol dm(-3)). The presence of the dispersing agent on the surface of silver particles was confirmed by ATR-FTIR spectroscopy and electrokinetic measurements, explaining both the negative charge over the entire pH range and the electrosteric effect responsible for their long-term stability. The other experimental conditions, i.e., the pH of the reacting solutions, the concentration of the stabilizing agent, and the metal/dispersant ratio, also have a significant impact on the size and stability of these dispersions. The final nanosize silver can be obtained as dried powder, and can be fully redispersed in deionized water by sonication.
426 citations
TL;DR: Data characterizing daily integrated particulate matter samples collected at the Jefferson Street monitoring site in Atlanta, GA, were analyzed through the application of a bilinear positive matrix factorization (PMF) model and agreed well with the locations of known local point sources.
Abstract: Data characterizing daily integrated particulate matter (PM) samples collected at the Jefferson Street monitoring site in Atlanta, GA, were analyzed through the application of a bilinear positive matrix factorization (PMF) model. A total of 662 samples and 26 variables were used for fine particle (particles < or = 2.5 microm in aerodynamic diameter) samples (PM2.5), and 685 samples and 15 variables were used for coarse particle (particles between 2.5 and 10 microm in aerodynamic diameter) samples (PM10-2.5). Measured PM mass concentrations and compositional data were used as independent variables. To obtain the quantitative contributions for each source, the factors were normalized using PMF-apportioned mass concentrations. For fine particle data, eight sources were identified: SO4(2-) -rich secondary aerosol (56%), motor vehicle (22%), wood smoke (11%), NO(3-) -rich secondary aerosol (7%), mixed source of cement kiln and organic carbon (OC) (2%), airborne soil (1%), metal recycling facility (0.5%), and mixed source of bus station and metal processing (0.3%). The SO4(2-) -rich and NO(3-) -rich secondary aerosols were associated with NH(4+). The SO4(2-) -rich secondary aerosols also included OC. For the coarse particle data, five sources contributed to the observed mass: airborne soil (60%), NO(3-)-rich secondary aerosol (16%), SO4(2-) -rich secondary aerosol (12%), cement kiln (11%), and metal recycling facility (1%). Conditional probability functions were computed using surface wind data and identified mass contributions from each source. The results of this analysis agreed well with the locations of known local point sources.
365 citations
TL;DR: In this article, results of three hybrid receptor models, including potential source contribution function (PSCF), concentration weighted trajectory (CWT), and residence time weighted concentration (RTWC), were compared for locating polychlorinated biphenyl (PCB) sources contributing to the atmospheric concentrations in Chicago.
346 citations
TL;DR: Well-ordered nanostructured thin polymer films have been fabricated from the supramolecular assembly of poly(styrene-block-4-vinylpyridine) (PS-PVP) and 2-hydroxybenzeneazo)benzoic acid (HABA, consisting of cylindrical nanodomains formed by PVP-HABA associates surrounded by PS.
Abstract: We report on a unique, very simple method of preparation of reactive membranes and nanotemplates with nanoscopic cylindrical channels on the surface of various inorganic and polymeric substrates. W...
304 citations
TL;DR: In this paper, the authors present a review of the improvements in the factor analysis methods that are applied in receptor modeling as well as easier application of trajectory methods for airborne particulate matter detection.
Abstract: Receptor modeling is the application of data analysis methods to elicit information on the sources of air pollutants. Typically, it employs methods of solving the mixture resolution problem using chemical composition data for airborne particulate matter samples. In such cases, the outcome is the identification of the pollution source types and estimates of the contribution of each source type to the observed concentrations. It can also involve efforts to identify the locations of the sources through the use of ensembles of air parcel back trajectories. In recent years, there have been improvements in the factor analysis methods that are applied in receptor modeling as well as easier application of trajectory methods. These developments are reviewed. Copyright © 2003 John Wiley & Sons, Ltd.
292 citations
TL;DR: It is found that the ALS estimated models are generally of a better quality than any of the alternatives even when overfactoring the model, but it is also found that ALS is significantly slower.
TL;DR: In this paper, the authors examine the changes in ownership patterns of franchise systems as they mature and compare the predictions made by three alternative theories within the context of the fast food industry, concluding that although franchisors value the benefits of the mix of ownership types and do maintain that mix over time, there is some evidence of a greater tendency to permanently convert existing franchised outlets to company-owned outlets as fast food systems mature and gain greater access to resources.
Book•
01 Jan 2003TL;DR: In this article, the authors discuss the role played by interfacial shear in the role of a viscous jet and its role in liquid sheet breaking and nonlinear capillary instability of liquid jets and sheets.
Abstract: Notation list Preface 1. Introduction 2. Uniform inviscid liquid sheets 3. Nonuniform inviscid liquid sheets 4. Viscous liquid sheets 5. Waves on liquid sheets 6. Phenomena of jet breakup 7. Inviscid jets 8. A viscous jet 9. Roles played by interfacial shear 10. Annular liquid jets 11. Nonlinear capillary instability of liquid jets and sheets 12. Epilogue Appendices Author index Subject Index.
TL;DR: In this paper, the use of the biharmonic operator for deforming a mesh in an arbitrary-Lagrangian-Eulerian simulation is investigated, where two conditions can be specified on each boundary of the mesh.
Abstract: The use of the biharmonic operator for deforming a mesh in an arbitrary-Lagrangian-Eulerian simulation is investigated. The biharmonic operator has the advantage that two conditions can be specified on each boundary of the mesh. This allows both the position and the normal mesh spacing along a boundary to be controlled, which is important for two-fluid interfaces and periodic boundaries. At these boundaries, we can simultaneously fix the position of the boundary and ensure that the normal mesh spacing is continuous across the boundary. In addition, results for deforming surfaces show that greater surface deformation can be tolerated when using biharmonic equations compared to approaches using second-order partial differential equations. A final advantage is that with the biharmonic operator, the integrity of a grid in a moving boundary layer can be preserved as the boundary moves. The main disadvantage of the approach is its increased computational expense.
TL;DR: In this article, a model developed to simulate the behavior of oil and gas accidentally released from deep water is presented, which incorporates the phase changes of gas, associated changes in thermodynamics and its impact on the hydrodynamics of the jet/plume Hydrate formation, hydrate decomposition, gas dissolution, non-ideal behavior of the gas, and possible gas separation from the main plume due to strong cross currents.
Abstract: A model developed to simulate the behavior of oil and gas accidentally released from deep water is presented This model presents major modifications to a three-dimensional model developed earlier (Yapa and Zheng, 1997) that simulate the behaviour of oil from under water accidents (shallow water) In deepwater, the ultra-high pressure and cold temperature causes phase changes in gases These combined with relatively strong currents in some deepwater regions presents extraordinary challenges to modeling jets/plumes from deepwater oil and gas blowouts The present model incorporates the phase changes of gas, associated changes in thermodynamics and its impact on the hydrodynamics of the jet/plume Hydrate formation, hydrate decomposition, gas dissolution, non-ideal behavior of the gas, and possible gas separation from the main plume due to strong cross currents are integrated with the jet/plume hydrodynamics and thermodynamics This paper presents the complete model development and testing of various comput
12 Oct 2003
TL;DR: In this paper, the amplitude, phase and frequency of a single sinusoid embedded in a nonstationary waveform is extracted for motor current signature analysis of induction machines operating during transients and the residual current is then analyzed using wavelets for the detection of broken rotor bars.
Abstract: A new algorithm is introduced for motor current signature analysis of induction machines operating during transients. The algorithm is able to extract the amplitude, phase and frequency of a single sinusoid embedded in a nonstationary waveform. The algorithm is applied to the detection of broken rotor bars in induction machines during startup transients. The fundamental component of current, which varies in amplitude, phase, and frequency, is extracted using the algorithm. The residual current is then analyzed using wavelets for the detection of broken rotor bars. This method of condition monitoring does not require parameters such as speed or number of rotor bars, is not load dependent and can be applied to motors that operate continuously in the transient mode, e.g., wind generators or motor-operated valves.
TL;DR: Titanium dioxide nanoparticles with a diameter in the 5 nm range were prepared by the sol−gel method, in an acidic environment, under several finely tuned experimental conditions as mentioned in this paper, which led to samples that contained 72.4 wt % anatase, rutile and amorphous phases.
Abstract: Titanium dioxide nanoparticles with a diameter in the 5 nm range were prepared by the sol−gel method, in an acidic environment, under several finely tuned experimental conditions. The titanium dioxide nanoparticles prepared were subjected to hydrothermal treatment and calcination. Using absorption spectrophotometry, X-ray diffraction, dynamic light scattering, and transmission electron microscopy permitted the assessments of the diameters of the nanoparticles and their composition (in terms of percentages of anatase, rutile, and amorphous phases). One of the methods of preparation led to samples that contained 72.4 wt % anatase and 27.6 wt % amorphous phase. Using montmorillonite and hectorite clay mineral platelets and titanium dioxide nanoparticles, nanocomposites were also prepared and calcinated under a variety of experimental conditions. Two major experimental conditions were employed. Method A involved the preadsorption of the titanium alkoxides into/onto the clay mineral platelets and their subsequ...
TL;DR: In this paper, a two-step grafting procedure was applied to graft polystyrene in the first step and poly(2-vinylpyridine) in the second step.
Abstract: We develop the route to fabricate mixed brushlike layers on polyamide substrates (PA-6, PA-6I, PA-66) by the “grafting from” approach. The PA substrates were functionalized by NH3 plasma. The azo initiator of radical polymerization was covalently bound to the functionalized PA surface. A two-step grafting procedure was applied to graft polystyrene in the first step and poly(2-vinylpyridine) in the second step. We found remarkable differences between grafting on Si wafers and on the PA substrates. “Grafting from” the PA surface results in a dramatic increase of the surface roughness of the film which can be explained by grafting in a swollen surface layer of PA. Because of this effect, we found a substantial amount of grafted polymers even on not functionalized PA substrates, which was explained by grafting via chain transfer reaction. The synthesized mixed polymer brushes form responsive coatings which switch their morphology due to the interplay between lateral and vertical phase segregation upon exposur...
TL;DR: In this article, positive matrix factorization (PMF) was used to deduce the sources of PM2.5 from both motor vehicles and vegetative burning, and conditional probability functions were computed using surface wind data and the PMF deduced mass contributions from each source and were used to identify local point sources.
TL;DR: The development of chemometrics as a subfield of chemistry and particularly analytical chemistry is presented with a view of the current state-of-the-art and the prospects for the future will be presented.
TL;DR: A fuzzy-reasoning approach is proposed to ensure robustness to the inherent uncertainty in the identified trends and to provide succinct mapping in fault diagnosis of an exothermic reactor case study.
TL;DR: In this article, the impact of rotor solidity and blade number on the aerodynamic performance of small wind turbines was examined. And the effect of blade number and solidity on wind turbine performance was investigated.
Abstract: A numerical study was conducted to examine the impact of rotor solidity and blade number on the aerodynamic performance of small wind turbines. Blade element momentum theory and lifting line based wake theory were utilized to parametrically assess the effects of blade number and solidity on rotor performance. Increasing the solidity beyond what is traditionally used for electric generating wind turbines led to increased power coefficients at lower tip speed ratios, with an optimum between 3 and 4. An increase in the blade number at a given solidity also increased the maximum C p for all cases examined. The possibility of a higher aerodynamic power extraction from solidity or blade number increases could lead to a higher overall system power production. Additional advantages over current 5% to 7% solidity, high speed designs would include lower noise, lower cut-in wind speed, and less blade erosion.
23 Jun 2003
TL;DR: Analysis and numerical experiments examining the behavior and performance of p-multigrid for solving hp-finite element (FEM) discretizations are presented and it is found that the slowest converging mode is long-wavelength along the streamwise direction and short wavelength normal to this direction.
Abstract: Analysis and numerical experiments examining the behavior and performance of p-multigrid (p = polynomial degree) for solving hp-finite element (FEM) discretizations are presented. We begin by demonstrating the mesh and order independent properties of p-multigrid when used to solve a C0 continuous FEM discretization of the Laplace equation. We then apply pmultigrid to both continuous and discontinuous FEM discretizations of the convection equation. Although 1D Fourier analysis predicts that mesh independent results should be possible for both discretizations, in 2D the results are sensitive to both the mesh resolution and the degree of polynomial approximation. Examining the solutions, we find that for both discretizations, the slowest converging mode is long-wavelength along the streamwise direction and short wavelength normal to this direction. Because of the isotropic coarsening of p-multigrid, this mode is not damped on coarse levels.
TL;DR: In this article, modified alternating least squares (MALS) regression was compared with ordinary alternating least square regression (ALS) and fast non-negative least square (FNNLS) regression in applications of spectroscopic image analysis and self-modeling curve resolution (SMCR).
TL;DR: In this article, the authors examined the n-variant case utilizing relaxation theory and produced a seemingly obvious but very powerful observation regarding a lower bound to the quasi-convex relaxation that makes practical evolutionary computations possible.
Abstract: The construction of effective models for materials that undergo martensitic phase transformations requires usable and accurate functional representations for the free energy density. The general representation of this energy is known to be highly non-convex; it even lacks the property of quasi-convexity. A quasi-convex relaxation, however, does permit one to make certain estimates and powerful conclusions regarding phase transformation. The general expression for the relaxed free energy is however not known in the n-variant case. Analytic solutions are known only for up to 3 variants, whereas cases of practical interests involve 7–13 variants. In this study we examine the n-variant case utilizing relaxation theory and produce a seemingly obvious but very powerful observation regarding a lower bound to the quasi-convex relaxation that makes practical evolutionary computations possible. We also examine in detail the 4-variant case where we explicitly show the relation between three different forms of the free energy of mixing: upper bound by lamination, the Reus lower bound, and a lower estimate of the H -measure bound. A discussion of the bounds and their utility is provided; sample computations are presented for illustrative purposes.
TL;DR: In this paper, a new mass transfer correlation was developed using NAPL dissolution data from a small 2D experimental cell that contained a well-characterized heterogeneous distribution of grain sizes.
Abstract: [1] The application of existing correlations for nonaqueous phase liquid (NAPL) dissolution, which were developed in small, one-dimensional columns, to larger-scale, heterogeneous or multidimensional systems has shown the predicted dissolution behavior depends greatly on the correlation used. Variation among existing correlations is due to the system scale, NAPL-water interfacial area, and the nature of mass transfer or hydrodynamic mechanisms that are lumped in the correlation. In this paper, new mass transfer correlation is developed using NAPL dissolution data from a small 2-D experimental cell that contained a well-characterized heterogeneous distribution of grain sizes. The new correlation can be used for quantifying NAPL dissolution rates over a wide range of NAPL saturations and aqueous phase velocities within the NAPL source zone. When incorporated in a finite difference transport model, the correlation provides reasonably good predictions for systems with initially high NAPL saturations that are then reduced through the dissolution process. It is shown that NAPL dissolution is slower in this case due to the larger amorphous blobs that result from preferential flow and dissolution pathways. These large blobs have significantly less surface area in comparison with small discrete blobs that result from capillary entrapment. In comparison with other published dissolution correlations, the slower mass transfer rate is characterized with a significantly higher exponent on the NAPL saturation term.
TL;DR: Preliminarily results indicate that the sludge may emit up to 90 kg/yr of PCBs to the air, but this amount is probably not a significant contribution to the Chicago atmosphere on the basis of dispersion modeling results and a simple box model.
Abstract: Potential source contribution function (PSCF) modeling using polychlorinated biphenyl (PCB) concentrations measured in the Chicago area resolved three PCB source sectors. They were (i) the directio...
TL;DR: In this article, single molecule conformations and associate morphologies for polystyrene/poly(2-vinylpyridine) (PS7−P2VP7) heteroarm star copolymer, formed in controlled environment and deposited onto mica or Si wafers, have been studied by atomic force microscopy (AFM) with molecular resolution.
Abstract: Single molecule conformations and associate morphologies for polystyrene/poly(2-vinylpyridine) (PS7−P2VP7) heteroarm star copolymer, formed in controlled environment and deposited onto mica or Si wafers, have been studied by atomic force microscopy (AFM) with molecular resolution. At concentrations below 0.01 mg/mL PS7−P2VP7 exists in the molecularly dissolved state in both selective (acidic water, toluene) and common good (chloroform, tetrahydrofuran) solvents. In acid conditions PS7−P2VP7 forms either unimolecular or multimolecular micelles depending on concentration and pH. The core of the micelles is constituted of the collapsed PS arms surrounded by protonated P2VP shell. PS7−P2VP7 undergoes inverse intramolecular segregation upon addition of toluene. In this case, P2VP arms form the dense core of the micelles embedded in the swollen PS shell. The transition between those two inverse types of micelles is strongly modified by interaction with the mica substrate. The micelles deposited onto mica from a...
TL;DR: In this article, a measurement program has been undertaken to measure the concentrations of particles and Hg0 in rural areas of New York State during the summer of 2000 and 2001, and the data from these measurements were used in paired receptor models to assess the origins of the measured concentrations.