Dry catalytic partial oxidation of diesel-fuel distillates into syngas

Volatile compounds distilled below 205 °C from diesel fuel are reformed into synthesis gas by dry catalytic partial oxidation using porous membrane reactors, eliminating complex liquid-fuel injectors and fuel-air mixers, greatly simplifying reformers for applications with solid-oxide fuel cells and NO_x traps. For distillates utilizing 20 wt% of the diesel fuel, 88 mol% of the carbon is converted into CO and 75 mol% of the hydrogen into H₂. Rationale is as follows: Long-chain n-alkanes such as n-hexadecane, with normal boiling point, 286.5 °C, but autoignition temperature, 205 °C, are the least thermally stable hydrocarbons in diesel fuel. If attempts are made to vaporize diesel fuel under oxygen-lean conditions without precautions, long-chain n-alkanes crack at autoignition temperatures forming radicals that initiate polymerization. By eliminating more troublesome compounds by distillation, and by effusing cooler air through porous ceramic membranes to react radicals with oxygen, carbon deposition is largely suppressed. A perovskite catalyst, fed pre-heated air at >900 °C, provides a reservoir of mobile lattice oxygen to react with adsorbed carbon. In continuous runs of 72 h, carbon deposition was negligible in the reactor, on the catalyst, and in the exhaust, except for minor graphite deposited onto walls near the catalytic hot zone.     

Physicochemical Investigation of Biocompatible Mixed Surfactant Reverse Micelles: III. Aqueous NaCl Solubilization, Thermodynamic Parameters of Desolubilization Process and Conductometric Studies

Solubilization of water and aqueous NaCl in mixed reverse micelles (RMs) comprising sodium bis(2‐ethylhexyl) sulfosuccinate (AOT), and polyoxyethylene (20) sorbitan trioleate or polyoxyethylene (20) sorbitan monooleate has been studied at different compositions (X_nonionic = 0–1.0) at a total surfactant concentration, S_T = 0.10 × 10³ mol m^?3 in biocompatible oils of different chemical structures; viz., ethyl oleate (EO), isopropyl myristate (IPM) and isopropyl palmitate (IPP) at 303 K. The enhancement in water solubilization (i.e., synergism) has been evidenced by the addition of nonionic surfactant to dioctyl sulfosuccinate/oil(s)/water systems. Addition of NaCl in these systems at different X_nonionic enhances their solubilization capacities further until a maximum, ω_NaCl,max is reached. ω_NaCl,max and [NaCl]_max (concentration at which maximization of NaCl solubilization occurs) depend on type of nonionic surfactant, its content (X_nonionic) and oil. A new solubilization efficiency parameter (SP*_water or SP*_NaCl) has been proposed to compare solubilization phenomena in these oils. The energetic parameters of the desolubilization process of water or aqueous NaCl in single and mixed RMs have been estimated. Energetically, the water dissolution process in oil has been found to be more exothermic as well as more organized in IPP. Overall, the dissolution of water and aqueous NaCl in mixed RMs is entropically driven process. Conductance behavior of these systems in the presence of NaCl has been investigated under different [NaCl] at 303 K. An attempt has been made to give an insight to the mechanism of solubilization phenomena, percolation in conductance and microstructures vis‐à‐vis role of biocompatible oils in these systems.     

Ge/SiGe Superlattices for Thermoelectric Devices Grown by Low-Energy Plasma-Enhanced Chemical Vapor Deposition

Ge/SiGe multiple quantum wells are presented as efficient material for room-temperature thermoelectric generators monolithically integrated onto silicon. We have deposited and characterized 10-μm-thick heterostructures engineered for lateral devices, in which both heat and current flow parallel to the multilayer. In this paper we investigate in detail the structural and interface quality by means of x-ray diffraction and transmission electron microscopy. Thermoelectric measurements, giving a figure of merit of 0.04 to 0.08, together with mobility spectra and defect analysis suggest possibilities of even higher efficiency. Nevertheless, the high power factor of 2 mW/K²m to 6 mW/K²m is promising for applications.     

Dynamic behaviour of railway tracks on transitions zones

Transition zones between structures as bridges or box culverts frequently present higher degradation rates compared to the remaining railway. This paper presents a numerical model for the dynamic loads on the ballast caused by trains passing a transition. The model was validated with field data obtained from an extensive field survey conducted in two transition zones in the Netherlands. Results show that the forces on the ballast vary significantly both in time and space on a transition, especially with the appearance of voids under the sleepers. Implications of the results on the long-term behaviour of transition zones are presented.     

Aging and task switching: A meta-analysis.

A meta-analysis of 26 published articles (with 36 independent participant groups) was conducted to analyze the relationship between task-switching effects and aging. Latency served as the dependent measure. Multilevel modeling was used to test for additive and multiplicative complexity effects in local and global switch costs. Global task switching was found to add 1 or more stages to processing and resulted in a marked age deficit. Local task-switching costs, on the other hand, showed a multiplicative complexity effect but no specific attention-related age deficits. Cueing or switch predictability did not affect age differences. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

另类集成

正与使用SoC相比,用单独的晶粒或芯片来构建你的系统,也许是聪明的另类方式。SoC历史上曾代表电子业的最高境界,这是因为如果使用这些芯片,电子系统设计者就能把很多数字电路装到一小块区域中。但是,细线CMOS不适合用在模拟、电源和射频功能     

Cohesive model approach to the nucleation and propagation of cracks due to a thermal shock

This paper studies the initiation of cohesive cracks in the thermal shock problem through a variational analysis. A two-dimensional semi-infinite slab with an imposed temperature drop on its free surface is considered. Assuming that cracks are periodically distributed and orthogonal to the surface, at short times we show that the optimum is a distribution of infinitely close cohesive cracks. This leads us to introduce a homogenized effective behavior which reveals to be stable for small times, thanks to the irreversibility. At a given loading cracks with a non-cohesive part nucleate. We characterize the periodic array of these macro-cracks between which the micro-cracks remain. Finally, for longer times, the cohesive behavior converges towards that from Griffith’s evolution law. Numerical investigations complete and quantify the analytical results.