Experimental and numerical investigation of catalytic PM combustion in a fluidized bed type PM removal device for low-temperature continuous regeneration

A fluidized bed filter can perform highly efficient PM collection and low-temperature continuous regeneration. However, to further reduce continuous regeneration temperature, a rough surface bed particle was selected herein. It is expected that the rough surface increases and stabilizes doped catalyst on bed particle even in fluidized bed. This bed particle can stably support 9.48 g-catalyst/kg-bed particle of doped catalyst versus 1.58 g-catalyst/kg-bed particle in previous research. This increase in catalyst amount increases the probability of good PM-catalyst contact, and collection efficiency can easily maintain its initial value due to catalytic PM combustion. PM combustion also depends on fluidization. Thus, combustion kinetics in a fluidized bed was investigated via a newly developed thermogravimetric analyzer that considered PM-gas relative velocity, and a constructed kinetic model was applied to numerical simulation. PM combustion obeyed an Arrhenius relationship, and the effect of PM-gas relative velocity was included in the kinetic model as a mass transfer term. A continuous regeneration experiment was conducted under optimal conditions, and the continuous regeneration temperature is 330 °C. As water vapor occurs in combustor exhaust, we added 10 vol% water vapor and found that the continuous regeneration is further reduced to 300 °C.     

New adaptive vector control methods for induction motors with simpler structure and better performance

This paper deals with the vector control, including both the direct vector control(DVC) and the indirect vector control(Id VC),of induction motors. It is well known that the estimation of rotor flux plays a fundamental role in the DVC and the estimation of rotor resistance is vital in the slip compensation of the Id VC. In these estimations, the precision is significantly affected by the motor resistances. Therefore, online estimation of motor resistances is indispensable in practice.For a fast estimation of motor resistances, it is necessary to slow down the convergence rate of the current estimate. On the other hand, for a fast estimation of the rotor flux, it is necessary to speed up its convergence rate. It is very difficult to realize such a trade-off in convergence rates in a full order observer.In this paper, we propose to decouple the current observer from the flux observer so as to realize independent convergence rates. Then, the resistance estimation algorithm is applied to both DVC and Id VC. In particular, in the application to Id VC the flux observer needs not be used, which leads to a simpler structure. Meanwhile, independent convergence rates of current observer and flux observer yield an improved performance. A superior performance in the torque and flux responses in both cases is verified by numerous simulations.     

Robust combinatorial auction protocol against false-name bids

This paper presents a new combinatorial auction protocol that is robust against false-name bids. Internet auctions have become an integral part of Electronic Commerce (EC) and a promising field for applying agent and Artificial Intelligence technologies. Although the Internet provides an excellent infrastructure for combinatorial auctions, we must consider the possibility of a new type of cheating, i.e., an agent tries to profit from submitting several bids under fictitious names (false-name bids). If there exists no false-name bid, the Generalized Vickrey Auction protocol (GVA) satisfies individual rationality, Pareto efficiency, and incentive compatibility. On the other hand, when false-name bids are possible, it is theoretically impossible for a combinatorial auction protocol to simultaneously satisfy these three properties.

Our newly developed Leveled Division Set (LDS) protocol, which is a modification of the GVA, utilizes reservation prices of auctioned goods for making decisions on whether to sell goods in a bundle or separately. The LDS protocol satisfies individual rationality and incentive compatibility even if agents can submit false-name bids, although it is not guaranteed to achieve a Pareto efficient social surplus. Simulation results show that the LDS protocol can achieve a better social surplus than that for a protocol that always sells goods in one bundle.     

Preparation of carbon fibers from syndiotactic 1,2-polybutadiene

Carbon fibers having good mechanical properties were produced from syndiotactic 1,2-polybutadiene (s-PB). Melt-spun s-PB fibers were made infusible by oxidation, irradiation, or treatments with Lewis acids, protonic acids, or peroxides. The infusibilized fibers were dehydrogenated with oxygen, chloranil, or sulfur and then carbonized. The preparative method by the AlBr₃–sulfur–heat treatment process gave carbon fibers with good mechanical strength in a high yield. A filaments bundle was immersed in a benzene solution of AlBr₃ (2g/100mL) at 42°C for 78 min under tension, washed with methanol, and then immersed in molten sulfur at 275°C for 14 min. After the adhering sulfur was purged with nitrogen at 290°C for 7 min, the bundle was heated up to a temperature of 700–3000°C under tension in a flow of nitrogen or argon for a few minutes. Carbon fibers heated to 1400°C were obtained with the tensile strength of 16.6 t/cm² and the modulus of 1420 t/cm² in a carbon yield of 82% and strain-graphitized fibers at 3000°C with 20 t/cm² and 4010 t/cm² in 70%.     

DNA-lipid complexes carrying carbazole and triphenylamine moieties: Synthesis, and chiroptical and photoelectronic properties

Novel DNA-lipid complexes carrying carbazole and triphenylamine moieties were prepared by substituting the sodium counter cation with cationic amphiphilic lipids, namely lipid(Cz) and lipid(TPA), in which the actual mole ratios of phosphate to lipid were 1:1.10 and 1:0.83, respectively. The DNA-lipid(Cz) and DNA-lipid(TPA) complexes were soluble in common organic solvents including CHCl₃, CH₂Cl₂, methanol and ethanol, while insoluble in THF, toluene, and aqueous solutions. CD spectroscopy revealed that the DNA-lipid complexes took a predominantly double helical structure in CHCl₃ and methanol and that the helical structure was fairly stable against heating. Solutions of DNA-lipid(Cz) and DNA-lipid(TPA) complexes emitted fluorescence in 5.7 and 76.4% quantum yields, which were higher than those of the corresponding lipid(Cz) and lipid(TPA) (4.4 and 55.3%). The cyclic voltammograms of the complexes indicated that the oxidation potentials of DNA-lipid(Cz) and DNA-lipid(TPA) were 0.95 and 0.85 V, respectively. The onset temperatures of weight loss of the DNA-lipid complexes were both 220 °C according to TGA in air.     

Polyethylene ionomer-based nano-composite foams prepared by a batch process and MuCell® injection molding

To understand the correlation between foamability and melt rheology of polyethylene-based ionomers having different degrees of the neutralization and corresponding nano-composites, we have conducted the foam processing via a batch process in an autoclave and microcellular foam injection molding (FIM) process using the MuCell^® technology. We have discussed the obtainable morphological properties in both foaming processes. All cellular structures were investigated by using field emission scanning electron microscopy. The competitive phenomenon between the cell nucleation and the cell growth including the coalescence of cell was discussed in light of the interfacial energy and the relaxation rate as revealed by the modified classical nucleation theory and rheological measurement, respectively. The FIM process led to the opposite behavior in the cell growth and coalescence of cell as compared with that of the batch process, where the ionic cross-linked structure has significant contribution to retard the cell growth and coalescence of cell. The mechanical properties of the structural foams obtained by FIM process were discussed.     

Classification of heavy-metal toxicity by human DNA microarray analysis

Microarray technology is proving to be a useful tool to classify undefined environmental toxicants, to investigate underlying mechanisms of toxicity, and to identify candidate toxicant-specific genetic markers by examining global effects of putative toxicants on gene expression profiles. The aim of this study was to evaluate the toxicities of six heavy metals through the comparison with gene expression patterns induced by well-known chemicals. For this purpose, we first identified the genes altered specifically in HepG2 under the exposure of 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), phenol, and N-nitrosodimethylamine (DMN), which were selected as the model chemicals, using DNA microarray. On the basis of the expression profiles of these genes, toxicities of six heavy metals, arsenic, cadmium, nickel, antimony, mercury, and chromium, were evaluated. The specific gene alteration and hierarchical clustering revealed that biological action of six heavy metals was clearly related to that of DMNQ which has been reported to be a reactive oxygen species (ROS) generating chemical and which induced the genes associated with cell proliferative responses. These results suggest that cell proliferative responses which are probably caused by ROS are a major apparent biological action of high-dose heavy metals, supporting the previous reports. Overall, a mechanism-based classification by DNA microarray would be an efficient method for evaluation of toxicities of environmental samples.     

Hugoniot measurement by hyper-velocity impact at velocities up to 9 km/s using a two-stage light-gas gun under optimized shot conditions

The optimization for acceleration of a projectile was performed by varying piston mass in consideration with the correlation with projectile mass and the engineering limits of the two-stage light-gas gun, and the projectile velocity has been achieved 9.2 km/s using the optimum acceleration conditions. Moreover, the Hugoniot measurements of oxygen-free copper were performed using the line reflection method at pressures up to 380 GPa by symmetric impact. The tilt and curvature of shock front were investigated according to the impact velocity, and it is proved to be important that the continuous spatial profile of shock front would be recorded.     

Dynamic deformation and fracture of mullite (3Al2O3·2SiO2) ceramics under hypervelocity impact

Shock-recovery experiments have been performed on mullite ceramics to clarify the effect of a phase transition on the microstructural change and deformation mechanism under shock loading. The recovered samples have been examined using the X-ray diffraction method and transmission electron microscope observation. In the samples shocked above the phase-transition pressure, an amorphization of mullite occurs. Mullite nano-crystals with grain sizes less than 10 nm are dispersed in the amorphous phase, indicating that the relatively large starting mullite crystals become nano-crystals accompanied with the amorphization. Mullite bumper-shield experiments have also been performed to examine the influence of shock-induced microstructural changes to ultimate fracture under hypervelocity impact. The results suggest that the phase transition of mullite has an effect on protection against high-velocity impact.     

Foam processing of polyethylene ionomers with supercritical CO2

Via a batch process, the foam processing of polyethylene-based ionomers having two different degree of the neutralization has been conducted using supercritical CO₂. The cellular structures obtained from various ranges of foaming temperature-CO₂ pressure were investigated by using field emission scanning electron microscopy. For comparison, the corresponding nano-composite also has been examined. The ionic cross-linked structure in the ionomer exhibited significant contribution to retard the cell growth and coalescence of cell, especially in ionomer having higher degree of the neutralization. For nano-composite foaming, experimentally, nano-clay particles led to an increase in cell density after foaming. However, the dispersed nano-clay particles did not act as nucleating sites for cell formation. The competitive phenomenon between the cell nucleation and the cell growth including the coalescence of cell was discussed in the light of the interfacial energy and the relaxation rate as revealed by the modified classical nucleation theory and rheological measurement, respectively.