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971.
Mary Beth Walsh Connie M. Moss Benny G. Johnson Dale A. Holder Jeffry D. Madura 《The Chemical Educator》2002,7(6):379-383
The need for improved interactive tutoring capabilities in educational software for chemistry problem solving is an important one clearly articulated by teachers and students. To deliver the next generation of individualized interactive capabilities users demand, it is necessary to go beyond the conventional computer-assisted instruction methodology. The focus of this paper is the assessment with first-semester general chemistry students of a recently developed artificial intelligence (AI) tutor for balancing chemical equations. This is the first such assessment of an AI-based learning tool in chemistry. Students in CHEM 121 in the Fall 2001 semester at Duquesne University (N = 273) participated in the study. Students were divided into a test group that used the AI tutor as part of their study activities and a control group that did not use the tutor. It was found that the tutor improved the performance of the test group students to a statistically significant degree, helping the weakest students the most. This study establishes the feasibility of an AI-based approach to creating advanced new tutoring software for chemistry problem solving. Access to a Web-based demonstration of the equation-balancing tutor may be obtained by emailing the corresponding author. 相似文献
972.
Laser gas-assisted material processing finds wide application in industry. The modelling of heating, elastic response of the substrate material, and the wave analysis gives insight into the laser workpiece interaction. In the present study, laser gas-assisted heating of steel is considered. The normal component of the thermal stress is taken as the source of load for the flexural wave generation in the material. The flexural wave generated is simulated and the wave characteristics are analyzed at four locations at the workpiece surface. The numerical scheme employing a control volume approach is introduced when solving the governing equations of flow and heat transfer while finite element and spectran element methods are used when solving the stress and wave equations. It is found that the normal component of the stress is tensile. The dispersion effect of the workpiece material, interference of the reflected beam, and partial overlapping of second mode of the travelling wave enable to identify a unique pattern in the travelling wave in the substrate. 相似文献
973.
M. Z. Rovinskii 《Functional Analysis and Its Applications》1991,25(1):74-77
M. V. Lomonosov Moscow State University. Translated from Funktsional'nyi Analiz i Ego Prilozheniya, Vol. 25, No. 1, pp. 88–91, January–March, 1991. 相似文献
974.
M. Pappalardo 《Journal of Optimization Theory and Applications》1991,70(1):97-107
We prove a property of the Bouligand tangent cone to the epigraph (or to the graph) of a locally Lipschitz function. It is also shown how this result can be used in determining Dini sequences. Finally, some relationships between such a cone and Dini derivatives are provided. 相似文献
975.
E. R. Bauminger E. Fibach A. M. Konijn S. Ofer E. A. Rachmilewitz 《Hyperfine Interactions》1991,66(1-4):11-23
Mössbauer studies in murine (MEL) and human K-562 erythroleukemia cell lines have been utilized to study the fate of iron during intracellular Hb synthesis and denaturation. The results showed that ferritin can serve as an intermediate iron pool for Hb synthesis and for storage of iron released during intracellular Hb denaturation. 相似文献
976.
M. Carme Calderer 《Mathematical Methods in the Applied Sciences》1994,17(3):171-188
This article deals with flow phenomena in liquid crystal materials. The model that I analyse is that due to Ericksen for liquid crystals with variable degree of orientation. One of the goals is understanding the role of the order parameter in the model. I examine the multiplicity of solutions, phases, that occur in shear flow regimes and analyse their stability under physically realistic conditions. In particular, I show that ellipticity of the linearized system of governing equations is a consequence of the Clausius–Duhem inequality. 相似文献
977.
H. M. Soroush 《The Journal of the Operational Research Society》1994,45(3):287-300
The classical PERT approach uses the path with the largest expected duration as the critical path to estimate the probability of completing a project by a given deadline. However, in general, such a path is not the ‘most critical’ path and does not provide the smallest estimate for the probability of completion time. This paper studies the ‘most critical path’ problem and formulates it as an optimal path problem in a deterministic network with a two-attribute fractional objective function. An exact solution approach is presented for the optimal path problem which also gives the solution to the most critical path problem. The illustrative examples as well as our computational results demonstrate that the proposed algorithm provides estimates for the probabilities of completion time that are much more accurate than those of the classical approach. 相似文献
978.
V. Ivanova E. Emamilova M. SedlÀK J. PazlarovÀ 《Applied biochemistry and biotechnology》1991,30(2):193-202
Two bacterial α-amylases from new industrial strains were studied: α-amylase fromBacillus amyloliquefaciens CCM 3502 (Czechoslovak) and thermostable α-amylase fromBacillus licheniformis 44MB82 (Bulgarian). The thermostable enzyme hydrolyzed starch mainly to dextrins, and after 1 h, 30% of the products were oligosaccharides. TheB. amyloliquefaciens enzyme produced more maltooligosaccharides than the first enzyme (B. licheniformis). Within 1 h, up to 80% of the substrate were hydrolyzed, giving different spectrum of oligosaccharides in comparison with the thermostable one. 相似文献
979.
M. Sato 《Journal of mathematical chemistry》1991,7(1):341-352
In the first part, a topological characterization of various zeolite frameworks is performed on the basis of the Hamiltonian graph. It affords a simple representation of the framework connectivity, and presents some possibility of the classification as well as the prediction of unknown frameworks. In the second part, a simple and direct method based on the connectivity matrix is presented, by which all the possible Al distributions in a given framework are derived exhaustively under the restriction of Loewenstein's rule. An example of Al preference site determination is applied for zeolite ZSM-5 and compared with the result by the SCF-MO method. 相似文献
980.
We estimate the possible influence of spectral line profile (Lorentz profile, Van Vleck–Weisskopf profile, and profile obtained by solving kinetic equation) on the rotation part of the dielectric permittivity of water-vapor monomers. Spectral regions corresponding to long-wavelength (static) and high-frequency (optical) limiting cases as well as regions in close proximity to resonances of various intensities are considered. The studied effects are compared with the corresponding effects on water-vapor absorption coefficient, which are related to factors determining the line-shape structure. 相似文献