Estimation of optimal PDE-based denoising in the SNR sense.

This paper is concerned with finding the best partial differential equation-based denoising process, out of a set of possible ones. We focus on either finding the proper weight of the fidelity term in the energy minimization formulation or on determining the optimal stopping time of a nonlinear diffusion process. A necessary condition for achieving maximal SNR is stated, based on the covariance of the noise and the residual part. We provide two practical alternatives for estimating this condition by observing that the filtering of the image and the noise can be approximated by a decoupling technique, with respect to the weight or time parameters. Our automatic algorithm obtains quite accurate results on a variety of synthetic and natural images, including piecewise smooth and textured ones. We assume that the statistics of the noise were previously estimated. No a priori knowledge regarding the characteristics of the clean image is required. A theoretical analysis is carried out, where several SNR performance bounds are established for the optimal strategy and for a widely used method, wherein the variance of the residual part equals the variance of the noise.     

Skeletal isomerization of octadecane on bifunctional ZSM-23 zeolite catalyst

Octadecane was isomerized over three different Pt/H-ZSM-23 samples. The distributions of methylheptadecane and dimethylheptadecane skeletal isomers obtained on the Pt/ZSM-23 samples were very similar. Positional isomer distributions are fingerprints of the zeolite framework structure. The independence of skeletal isomer distributions from Al-gradients and particle size constitutes a strong argument in favor of pore-mouth catalysis.     

Strategic information systems research: An archival analysis

The Journal of Strategic Information Systems (JSIS) has been an international outlet for Information Systems research that focuses on strategic issues since 1991. This paper reports on an analysis of the research published in JSIS to date. The paper presents a preliminary classification system for research topics related to Strategic Information Systems into which all 316 JSIS research papers as at end 2009 are classified. Discussion on changing emphases in topics over time is provided, in the context of the editorial philosophy of the journal. The paper seeks to stimulate discussion on future directions for research in Strategic Information Systems.     

Steady-state simulation of Fluid Catalytic Cracking riser reactors using a decoupled solution method with feedback of the cracking reactions on the flow

A method is proposed to simulate reactive flow, fully taking into account the effect of the reactions on the flow. Operator splitting is used to separate the computation of convection and reaction. A fast solver for mildly stiff ordinary differential equations and parallelization of the reaction term evaluation have been implemented to reduce the CPU time. The proposed method is applied to the steady-state, two-phase gas–solid simulation of a Fluid Catalytic Cracking riser reactor. A relatively simple kinetic model with four lumped components is used to demonstrate the feasibility of the method. The results show that the method is able to handle reactive flow with significant feedback of the reactions on the flow.     

Identifiability of rate coefficients in linear reaction networks from isothermal transient experimental data

For linear reaction networks, graph-theoretical methods are used to find two types of kinetic transfer functions in the Laplace domain for isothermal uniform open systems under transient regime. Rules are formulated to find the functional form of these transfer functions from properties of the reaction network, viz the number of components and the length of shortest paths.In many cases, some reaction intermediates are not observed. This is typical in heterogeneous catalysis, where the intermediates are bound to the catalytic surface. The mechanistic details are then manifested only through some transfer functions. This often causes the rate coefficients to be unidentifiable. A graph-theoretical rule is derived which allows assessing whether reaction networks are structurally locally identifiable. It is applied to the interaction of propane with a copper oxide/ceria-catalyst, as studied with a temporal analysis of products (TAP) setup.     

The Fe–Zn–Al–Cr system and its impact on the galvanizing process in chromium-added zinc baths

The zinc rich corner of the Fe–Zn–Al–Cr at 460 °C is of interest for galvanizing because Al is a usual addition element in zinc bath, whereas Cr is naturally present because it is supplied by the stainless steel roller dipping in the Zn bath during the process. Indeed, it is used to understand the formation and growth mechanisms of the solid phases during galvanizing in Al and Cr-added Zn bath. By using additional experimental results in the Al–Cr–Zn and Fe–Zn–Al–Cr systems, the zinc rich corner of the Fe–Zn–Al–Cr system at 460 °C was determined with more accuracy. Thus, new equilibria between the liquid and quaternary phases have been pointed out, namely Al₂Cr₃ stabilized by Zn and enriched with Fe and τ₁, the latter being isotypic with δ-FeZn₉. This quaternary system was assessed with the CALPHAD method using the PARROT module of the Thermo-Calc Software. The liquid and solid solutions are described by the Redlich-Kister-Muggianu equations. All the modeled phases are considered as stoichiometric in the binary systems.     

Wall surface effects on particle-wall friction factor in upward gas-solid flows

The variation of the particle-wall friction factor along the riser is investigated in an Internal Circulating Fluidized Bed (ICFB) riser 1 m in length and 0.052 m in diameter. The results obtained are based on calculating the normal and the shear forces at the wall under dynamic conditions rather than the static ones usually obtained in shear box experiments.The strength of the method used resides in the measurement technique applied to measure the particle velocity field in the riser. The radioactive particle tracking program was developed for coaxial systems and is used to build dynamic pictures of particle trajectories in the vicinity of the wall of the ICFB riser.The experiments were conducted using sand (d_p = 250 µm) and alumina (d_p = 170 µm) materials in the gas velocity range between 2 and 12 m/s. The most common correlations for calculating the particle-wall friction factor are reviewed and compared to the results obtained in this work. The data obtained demonstrates that the particle-wall friction factor is not a constant value but changes along the riser and with change in the gas superficial velocity. The results also show the effect of the roughness of the wall surface and define the particle-wall friction factor area.     

Recognition of Borehole Radar Cable-Related Effects Using Variable Offset Sounding

Conductive cables can influence borehole radar measurements and introduce artifacts into data and therefore must be considered during data analysis and interpretation. This study presents examples of some cable-related effects in data acquired with a radar system that relies on conductive cables for signal transmission. Data show that measurements can be affected when energy radiated from the transmitter antenna induces currents on conductive cables, which can function as an electromagnetic waveguide, allowing fields to propagate along cables and be detected by the receiver antenna. Additionally, periodic artifacts can result when currents traveling on cables reflect at system impedance mismatches.Variable offset soundings (VOS) are not typically conducted during borehole radar studies, but can be useful for recognizing cable-related effects on recorded data and studying propagation characteristics in a borehole. In addition to single-hole VOS measurements, VOS measurements made on the ground surface using E-Plane and H-Plane configurations are shown to have the potential for providing additional insight in regards to coupling mechanisms between borehole antennas and cables.     

Knowledge Management Competence for Enterprise System Success

This study conceptualizes, operationalises and validates the concept of Knowledge Management Competence as a four-phase multidimensional formative index. Employing survey data from 310 respondents representing 27 organizations using the SAP Enterprise System Financial module, the study results demonstrate a large, significant, positive relationship between Knowledge Management Competence and Enterprise Systems Success (ES-success, as conceived by Gable et al., 2008); suggesting important implications for practice. Strong evidence of the validity of Knowledge Management Competence as conceived and operationalised, too suggests potential from future research evaluating its relationships with possible antecedents and consequences.