Simulation of Coal Combustion by AUSM Turbulence-Chemistry Char Combustion Model and a Full Two-Fluid Model

An algebraic unified second-order moment (AUSM) turbulence-chemistry model of char combustion is introduced in this paper, to calculate the effect of particle temperature fluctuation on char combustion. The AUSM model is used to simulate gas-particle flows, in coal combustion in a pulverized coal combustor, together with a full two-fluid model for reacting gas-particle flows and coal combustion, including the sub-models as the k-epsilon-k(p) two-phase turbulence niodel, the EBU-Arrhenius volatile and CO combustion model, and the six-flux radiation model. A new method for calculating particle mass flow rate is also used in this model to correct particle outflow rate and mass flow rate for inside sections, which can obey the principle of mass conservation for the particle phase and can also speed up the iterating convergence of the computation procedure effectively. The simulation results indicate that, the AUSM char combustion model is more preferable to the old char combustion model, since the later totally eliminate the influence of particle temperature fluctuation on char combustion rate.

Comparison of quantum chemistry calculation methods of nucleic acid base-quartets

Nine base-quartets were calculated by six semi-empirical methods and ab initio Hartree-Fork method using STO-3G basis set. The results showed that PM3 method can be use to calculate base quartets, the results of PM3 calculations are close to the ab initio

Effect of high dietary starch levels on the growth performance, blood chemistry and body composition of gibel carp (Carassius auratus var. gibelio)

An 8-week growth trial was carried out in a semi-recirculation system to investigate the effect of high dietary starch levels on the growth performance, blood chemistry, starch utilization and body composition of gibel carp (Carassius auratus var. gibelio). Five isonitrogenous and isocarloric experimental diets were formulated to contain different starch levels (24%, 28%, 32%, 36% and 40% respectively). Triplicate groups of fish (24 fish per tank with an average body weight, of 8.5 g) were assigned to each diet. The results showed that dietary carbohydrate levels significantly affected the growth performance, hepatopancreatic lipid content, pyruvate kinase (PK) activity and whole-body lipid content. Growth performance, body crude lipid and plasma glucose concentrations showed a decreasing trend with an increase in dietary starch from 24% to 40%. Pyruvate kinase activities and hepatopancreatic lipid content showed an increasing trend with the dietary starch increasing from 24% to 32%, and then a decreasing trend with the dietary starch increasing from 32% to 40%. No significant difference in the hepatopancreatic hexokinase (HK) activity, plasma triglyceride contents, body crude protein, ash and calcium (Ca) and phosphorus (P) contents was observed between different treatments. In conclusion, higher dietary starch levels (32-40%) significantly (P < 0.05) decreased the growth of gibel carp in the present study.

First-principles study on rutile TiO2 quantum dots

The electronic structure of rutile TiO2 quantum dots (QDs) are investigated via the first-principles band structure method. We first propose a model to passivate the rutile TiO2 surfaces for the local density approximation calculations. In this model pseudohydrogen atoms are used to passivate the surface dangling bonds, which remove the localized in-cap surface states in the TiO2 QDs. As the size of the QD decreases, the band gap evolves as E-g(dot) = E-g(bulk) + 73.70/d(1.93), where E-g(dot) and d are the band gap and diameter of the QD, and E-g(bulk) is the band gap of the bulk rutile TiO2. The valence band maximum and the conduction band minimum states of the QDs are distributed mostly in the interior of the QDs, and they well inherit the atomic characteristics of those states of the bulk rutile TiO2.

Electro-mass olfactory multi-sensor (EMMS)

For an olfactory sensor or electronic nose, the task is not only to detect the object concentration, but also to recognize it. It is well known that all the elements can be identified by their charge to mass ratio e(+)/m. We tried to imitate this principle for molecular recognition. Two kinds of sensors are used simultaneously in testing. One is quartz crystal microbalance (QCM) for detecting the change in mass, the other is interdigital electrode (IE) for detecting the change in conduction, as an electro-mass multi-sensor (EMMS). in this paper, the principle and the feasibility of this method are discussed. The preliminary results on the recognition of alcohol by EMMS coated with lipids are presented. Meanwhile, the multi-sensor can also be used as an instrument for research on some physico-chemistry problems. The change in conduction of coated membrane caused by one absorbed molecule is reported. It is found that when a QCM is coated with membrane, it still obeys the relationship Delta F (frequency change of QCM) = K Delta m (mass change of absorbed substance) and the proportional coefficient, K, depends not only on quartz properties but also on membrane characteristics as well. (C) 2000 Elsevier Science S.A. All rights reserved.

Optical and structural properties of self-assembled ZnO QD chains by L-MBE

ZnO complex 3D nano-structures have been self-organized on Al2O3 (0 0 0 1) substrate by laser molecular beam epitaxy (L-MBE). It is shown by AFM morphology that the structure is composed of ID quantum dot chains (QDCs) and larger nano-islands at the nodes of QDCs. The formation mechanism of the nano-structure is also investigated. XRD results indicate that the nano-structure is highly c-axis oriented, with the aligned in-plane oriented domains. Time-integrated photoluminescence (TIPL) of the sample shows obvious blue-shift and broadening of the near band-edge (NBE) emission at room temperature, which are related to the quantum confinement effects. Time-resolved PL (TRPL) result shows bi-exponential decay behavior of ZnO QDCs, with a fast decay time of 38.21 ps and a low decay time of 138.19ps, respectively, which is considered to be originated from the interdot coupling made by coherent emission and reabsorption of the photons in QDCs. (C) 2007 Elsevier B.V. All rights reserved.

Electro-mass olfactory multi-sensor (EMMS)

For an olfactory sensor or electronic nose, the task is not only to detect the object concentration, but also to recognize it. It is well known that all the elements can be identified by their charge to mass ratio e(+)/m. We tried to imitate this principle for molecular recognition. Two kinds of sensors are used simultaneously in testing. One is quartz crystal microbalance (QCM) for detecting the change in mass, the other is interdigital electrode (IE) for detecting the change in conduction, as an electro-mass multi-sensor (EMMS). in this paper, the principle and the feasibility of this method are discussed. The preliminary results on the recognition of alcohol by EMMS coated with lipids are presented. Meanwhile, the multi-sensor can also be used as an instrument for research on some physico-chemistry problems. The change in conduction of coated membrane caused by one absorbed molecule is reported. It is found that when a QCM is coated with membrane, it still obeys the relationship Delta F (frequency change of QCM) = K Delta m (mass change of absorbed substance) and the proportional coefficient, K, depends not only on quartz properties but also on membrane characteristics as well. (C) 2000 Elsevier Science S.A. All rights reserved.