地下机动车道空气质量标准和设计通风量计算方法

分析了机动车排放的主要污染物,探讨了地下机动车道可借鉴应用的空气质量标准.通过分析机动车在地下车道内的运行特点,研究了地下车道的分类及不同分类下的通风量计算指标.给出了地下车道设计通风量的计算公式,通过实例论证了地下空间采用稀释污染物计算方法的必要性.     

Smart Dynamic Resource Allocation Model for Patient-Driven Mobile Medical Information System Using C4.5 Algorithm

A mobile medical information system (MMIS) is an integrated application (app) of traditional hospital information systems (HIS) which comprise a picture archiving and communications system (PACS), laboratory information system (LIS), pharmaceutical management information system (PMIS), radiology information system (RIS), and nursing information system (NIS). A dynamic resource allocation table is critical for optimizing the performance to the mobile system, including the doctors, nurses, or other relevant health workers. We have designed a smart dynamic resource allocation model by using the C4.5 algorithm and cumulative distribution for optimizing the weight of resource allocated for the five major attributes in a cooperation communications system. Weka is used in this study. The class of concept is the performance of the app, optimal or suboptimal. Three generations of optimization of the weight in accordance with the optimizing rate are shown.     

Poly(hydromethylsiloxane)-derived high internal phase emulsion-templated materials (polyHIPEs) containing palladium for catalytic applications

Journal of Materials Science - Cross-linking of poly(hydromethylsiloxane) (PHMS) with 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (D4Vi) in water-in-oil high internal phase emulsion...     

Visualizing Thermally Activated Memristive Switching in Percolating Networks of Solution-Processed 2D Semiconductors

Memristive systems present a low-power alternative to silicon-based electronics for neuromorphic and in-memory computation. 2D materials have been increasingly explored for memristive applications due to their novel biomimetic functions, ultrathin geometry for ultimate scaling limits, and potential for fabricating large-area, flexible, and printed neuromorphic devices. While the switching mechanism in memristors based on single 2D nanosheets is similar to conventional oxide memristors, the switching mechanism in nanosheet composite films is complicated by the interplay of multiple physical processes and the inaccessibility of the active area in a two-terminal vertical geometry. Here, the authors report thermally activated memristors fabricated from percolating networks of diverse solution-processed 2D semiconductors including MoS₂, ReS₂, WS₂, and InSe. The mechanisms underlying threshold switching and negative differential resistance are elucidated by designing large-area lateral memristors that allow the direct observation of filament and dendrite formation using in situ spatially resolved optical, chemical, and thermal analyses. The high switching ratios (up to 10³) that are achieved at low fields (≈4 kV cm⁻¹) are explained by thermally assisted electrical discharge that preferentially occurs at the sharp edges of 2D nanosheets. Overall, this work establishes percolating networks of solution-processed 2D semiconductors as a platform for neuromorphic architectures.     

How to control the selectivity in the reduction of NOx with H2 over Pt-Ba/Al2O3 Lean NOx Trap catalysts

The reduction process of NO_x species stored over Pt-Ba/Al₂O₃ Lean NO_x Trap systems is analysed in this paper when H₂ is used as a reductant. The effect of different experimental conditions (temperature, reductant concentration, adsorption lengths, etc.) is addressed and discussed in relation to the selectivity and the efficiency of the reduction process.     

Sol–Gel Synthesis of λ–Na2O·xAl2O3 Films

Na₂O· x Al₂O₃ ( x = 9, 11)films have been obtained by sol–gel method. Crystallization processes during heat treatments have been investigated by X–ray diffraction analysis. A metastable phase with the mullite structure, λ–Na₂O· x Al₂O₃, has been observed starting from 800°C. Films remained stable after a heat treatment at 1000°C for 250 h. Impedance spectroscopy measurements showed that the films of λ-Na₂O· x Al₂O₃ possess a large three–dimensional ionic conductivity at 400°C.     

Dynamics and Selectivity of N<Subscript>2</Subscript>O Formation/Reduction During Regeneration Phase of Pt-Based Catalysts

The formation of N₂O has been studied by means of isothermal lean-rich experiments at 150, 180 and 250 °C over Pt–Ba/Al₂O₃ and Pt/Al₂O₃ catalysts with H₂ and/or C₃H₆ as reductants. This allows to provide further insights on the mechanistic aspects of N₂O formation and on the influence of the storage component. Both gas phase analysis and surface species studies by operando FT-IR spectroscopy were performed. N₂O evolution is observed at both lean-to-rich (primary N₂O) and rich-to-lean (secondary N₂O) transitions. The production of both primary and secondary N₂O decreases by increasing the temperature. The presence of Ba markedly decreases secondary N₂O formation. FT-IR analysis shows the presence of adsorbed ammonia at the end of the rich phase only for Pt/Al₂O₃ catalyst. These results suggest that: (i) primary N₂O is formed when undissociated NO in the gas phase and partially reduced metal sites are present; (ii) secondary N₂O originates from reaction between adsorbed NH₃ and residual NO_x at the beginning of the lean phase. Moreover, N₂O reduction was studied performing temperature programming temperature experiments with H₂, NH₃ and C₃H₆ as reducing agents. The reduction is completely selective to nitrogen and occurs at temperature higher than 250 °C in the case of Pt–Ba/Al₂O₃ catalyst, while lower temperatures are detected for Pt/Al₂O₃ catalyst. The reactivity order of the reductants is the same for the two catalysts, being hydrogen the more efficient and propylene the less one. Having H₂ a high reactivity in the reduction of N₂O, it could react with N₂O when the regeneration front is developing. Moreover, also ammonia present downstream to the H₂ front could react with N₂O, even if the reaction with stored NO_x seems more efficient.     

Isotactic polypropylene–vapor grown carbon nanofibers composites: Electrical properties

Nanocomposites have been obtained by dispersing various amounts of vapor grown carbon nanofibers within isotactic polypropylene. Thermal investigations done by differential scanning calorimetry and dynamic mechanical analysis revealed the effect of the vapor grown carbon nanofibers on the melting, crystallization, α, and β relaxations. Direct current electrical features of these nanocomposites have been investigated and related to the thermal features of these nanocomposites. The effect of the loading with carbon nanofibers on the electrical properties of these nanocomposites is discussed within the percolation theory. The percolation threshold was estimated at about 5.5% wt carbon nanofibers. The temperature dependence of the direct current conductivity is analyzed in detail and it is concluded that the electronic hopping is the dominant transport mechanism. A transition from one‐dimensional hopping towards a three‐dimensional hopping was noticed as the concentration of carbon nanofibers was increased from 10% wt to 20% wt carbon nanofiber. The possibility of a differential negative resistivity is suggested. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45297.