Ethanol steam reforming over Pt/Al2O3 and Rh/Al2O3 catalysts: the effect of impurities on selectivity and catalyst deactivation

Bioethanol contains different types of organic impurities which can have a significant influence on the catalytic performance during steam reforming of bioethanol. Different C3 functional group impurities were added individually to the pure ethanol to investigate the influence of different functional groups on the ethanol steam reforming reaction over 0.2% Pt/Al2O3 and 0.2% Rh/Al2O3 catalysts at 773 K. It was established that the catalytic behaviour of both of the catalysts is significantly influenced by the different impurities. The addition of 1 mol% C3 alcohols (1-propanol and isopropyl alcohol) decreased the conversion of ethanol and increased the rate of catalyst deactivation. This deactivation of the catalyst in the presence of C3 alcohols was attributed to high olefin formation and incomplete decomposition of the C3 alcohols, which deposited over the catalysts as coke. Propanal, propylamine and acetone addition to the water/ethanol mixture resulted in rapid metal deactivation and a loss of steam reforming activity over the Pt/alumina although ethanol decomposition continued. In contrast the Rh/alumina did not lose all steam reforming activity when acetone and propylamine were added as impurities. On both the catalysts alcoholic impurities produced a large number of carbon nanotubes (CNTs)

Real decoupling ghost quantization of the CGHS model for two dimensional black holes

A complete RST quantization of a CGHS model plus Strominger term is carried out. In so doing a conformal invariant theory with $\kappa=\frac{N}{12}$ is found, that is, without ghosts contribution. The physical consequences of the model are analysed and positive definite Hawking radiation is found.Comment: 14 pages, latex, no figures, marginal errors correcte

Two Dimensional Quantum Dilaton Gravity and the Positivity of Energy

Using an argument due to Regge and Teitelboim, an expression for the ADM mass of 2d quantum dilaton gravity is obtained. By evaluating this expression we establish that the quantum theories which can be written as a Liouville-like theory, have a lower bound to energy, provided there is no critical boundary. This fact is then reconciled with the observation made earlier that the Hawking radiation does not appear to stop. The physical picture that emerges is that of a black hole in a bath of quantum radiation. We also evaluate the ADM mass for the models with RST boundary conditions and find that negative values are allowed. The Bondi mass of these models goes to zero for large retarded times, but becomes negative at intermediate times in a manner that is consistent with the thunderpop of RST.Comment: 16 pages, phyzzx, COLO-HEP-309. (Confusing points in previous version clarified, discussion of ADM and Bondi masses in RST case added.

A comparison between finite element analysis code and cosmos software

In order to fulfill various needs of different users in different applications, there must exist a mutual understanding between software house and the users. The software developers should know exactly what the users need in their work and the developed software should perform accordingly. The users could come from any discipline, and the designers and the engineers are amongst those. In this project, a study has been carried out to compare the effectiveness between COSMOS software and the finite element generated programming code in order to do stress analysis on 3D object. In this study, the amount of stress will be imposed on subject area, and the resulted effect will be visualized as a gradual changed of colors. The engineers and designers will benefit from this study in terms of increasing their skill in design and obtain a well defined design since the competition become higher day after day

Relating prepotentials and quantum vacua of N=1 gauge theories with different tree-level superpotentials

We consider N=1 supersymmetric U(N) gauge theories with Z_k symmetric tree-level superpotentials W for an adjoint chiral multiplet. We show that (for integer 2N/k) this Z_k symmetry survives in the quantum effective theory as a corresponding symmetry of the effective superpotential W_eff(S_i) under permutations of the S_i. For W(x)=^W(h(x)) with h(x)=x^k, this allows us to express the prepotential F_0 and effective superpotential W_eff on certain submanifolds of the moduli space in terms of an ^F_0 and ^W_eff of a different theory with tree-level superpotential ^W. In particular, if the Z_k symmetric polynomial W(x) is of degree 2k, then ^W is gaussian and we obtain very explicit formulae for F_0 and W_eff. Moreover, in this case, every vacuum of the effective Veneziano-Yankielowicz superpotential ^W_eff is shown to give rise to a vacuum of W_eff. Somewhat surprisingly, at the level of the prepotential F_0(S_i) the permutation symmetry only holds for k=2, while it is anomalous for k>2 due to subtleties related to the non-compact period integrals. Some of these results are also extended to general polynomial relations h(x) between the tree-level superpotentials.Comment: 27 pages, 10 figures, modified version to appear in JHEP, discussion of the physical meaning of the Z_k symmetry adde

Coset Character Identities in Superstring Compactifications

We apply the coset character identities (generalization of Jacobi's abstruse identity) to compact and noncompact Gepner models. In the both cases, we prove that the partition function actually vanishes due to the spacetime supersymmetry. In the case of the compact models and discrete parts of the noncompact models, the partition function includes the expected vanishing factor. But the character identities used to the continuous part of the noncompact models suggest that these models have twice as many supersymmetry as expected. This fact is an evidence for the conjecture that the holographically dual of the string theory on an actually singular Calabi-Yau manifold is a super CONFORMAL field theory. The extra SUSY charges are interpreted as the superconformal S generators.Comment: 23 pages, LaTeX, no figure. v2:corrected typos, added detailed calculations, added references. v3:corrected typo