7,375 research outputs found
DC CONDUCTANCE OF CUPC FILMS PREPARED BY PLASMA ACTIVATED EVAPORATION
No full textA CuPc film with good mechanical and gas sensing properties was prepared by the plasma activated evaporation method. The conductivity of the CuPc film approximately satisfies the following equation: sigma = sigma (o) exp(-E/kT) where E is the activation energy. The activation energies of the films deposited at high pressures (200 and 300mtorr) are 0.7 similar to 0.8eV which are almost the same with Eg/2 of the sublimated CuPc film. For the films deposited at low pressures (20 and 100mtorr), the activation energies are 0.1 similar to 0.4 eV depending on the gas environment. As the deposition pressure of the CuPc film decreases, the porosity of the film increases and thus the surface area where NOx gas molecules can be adsorbed increases. This results in the increases of the DC conductivity and the NOx gas sensing sensitivity with decreasing CuPc deposition pressure
Visual characteristics including lift-off, of the jet flames in a cross-flow high-temperature burner
No full textSince flame modes, lift-off and stability are of much practical importance in the design of burners, these characteristics of the jet flames in a cross-flow at normal temperatures have been studied. Regarding general characteristics at high temperature, however, little research has been reported, even though many practical burners utilize the benefits of high temperature. This study investigates the general characteristics of the jet flames in a cross-flow at high temperature. The characteristic flame modes observed Lire found to be fundamentally different from those at normal temperature, and the lift-off behaviour could be understood through the premixed concept, including the effects of the large structure. Jet flames in a cross-flow behave differently from those at normal temperature, and the distinct characteristics should be considered in the design of each burner. (C) 2003 Published by Elsevier Ltd
UNIK-OPT/NN - Neural network based adaptive optimal controller on optimization models
No full textWhen the future information for an optimization model is not complete, the model tends to incorporate such uncertainties as some assumptions on the coefficients. As time passes and more precise information is accumulated, the initial optimal solution may no longer be optimal, or even feasible. At this point, model builders want to modify the assumed and controllable coefficients to obtain the desired values of designated decision variables. To aid this process, a neural network could effectively be applied. So we develop a tool UNIK-OPT/NN which can support the construction and recall of the neural network model on top of the knowledge assisted optimization model formulator UNIK-OPT and the semantic neural network building aid UNIK-NEURO. By adopting a commonly interpretable semantic representation of optimization and neural network models, UNIK-OPT/NN can effectively automate most of the neural network construction and recall procedure for optimal. control
Novel Burst Suppression Segmentation in the Joint Time-Frequency Domain for EEG in Treatment of Status Epilepticus
No full textWe developed a method to distinguish bursts and suppressions for EEG burst suppression from the treatments of status epilepticus, employing the joint time-frequency domain. We obtained the feature used in the proposed method from the joint use of the time and frequency domains, and we estimated the decision as to whether the measured EEG was a burst segment or suppression segment by the maximum likelihood estimation. We evaluated the performance of the proposed method in terms of its accordance with the visual scores and estimation of the burst suppression ratio. The accuracy was higher than the sole use of the time or frequency domains, as well as conventional methods conducted in the time domain. In addition, probabilistic modeling provided a more simplified optimization than conventional methods. Burst suppression quantification necessitated precise burst suppression segmentation with an easy optimization; therefore, the excellent discrimination and the easy optimization of burst suppression by the proposed method appear to be beneficial.110Ysciescopu
rain metastases from early stage endometrial carcinoma 8 years after primary treatment: case report and review of the literature.
No full textField-aided thermal chemical vapor deposition of copper using Cu(I) organometallic precursor
No full textA de substrate bias which is not enough to make a plasma was applied during the chemical vapor deposition of copper to change the adsorption behavior of the reactant. Copper films were deposited on TiN and SiO2 from Cu(hfac)(tmvs) with and without the substrate bias. The surface morphology, the thickness, the sheet resistance, and the purity of the films were investigated. When a negative substrate bias of -30 V was applied to the substrate, the deposition rate of copper increased both on TiN and SiO2. The substrate bias did not cause the change in the chemical composition of the deposited copper film. It was calculated that Cu(hfac) has the dipole moment whose direction is from copper to hfac. The local electric fields due to surface roughness may affect the adsorption behavior of the precursor, especially the direction of the molecular dipole moment. Resulting from the overlapping population value analysis, the improvement of deposition rate under negative substrate bias was explained as due to the adsorption of the copper atom in the Cu(hfac) species directly onto the substrate by the local electric fields applied between the substrate and the gas showerhead
Superplasticity in PM 6061 Al alloy and elimination of strengthening effect by reinforcement in superplastic PM aluminum composites
No full textPlastic-flow behavior of a powder-metallurgy (PM) processed 6061 matrix alloy has been investigated in a wide range of elevated temperature between 430 and 620 degreesC. It was found that the 6061 Al alloy exhibits superplasticity in a relatively wide range of temperature from 520 to 620 degreesC at a high strain rate of 10(-2) s(-1). Deformation behavior of the present alloy could be divided into three regions when the presence of threshold stress for plastic how was assumed. They are D(L) controlled grain boundary sliding. D(L) controlled dislocation climb creep and powder-law breakdown, respectively. When temperature is as high as 590 degreesC, however. the activation energy increases significantly higher than that for self-diffusion in aluminum and flow stress decreases further than normally expected. This phenomenon is likely attributed to the presence of liquid phase above 590 degreesC. Comparison of the data in Region I below 610 degreesC with those for a number of superplastic aluminum composites indicates that strengthening effect by reinforcement does not exist. Several speculations including diffusional relaxation in vicinity of reinforcements were made to explain this phenomenon. (C) 2001 Elsevier Science B.V. All rights reserved.Korea research foundation
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Design of nonuniformly spaced linear-phase FIR filters using mixed integer linear programming
No full textAn optimization problem for designing a nonuniformly spaced, linear-phase FIR filter with minimal complexity is formulated and solved by mixed integer linear programming (MILP). Examples illustrate that the proposed method is useful for designing a wide range of filter types and can outperform subset selection-based design methods
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