Enhanced removal of benzene in nonthermal plasma with ozonation,flow recycling,and flow recirculation

A double stage AC/DC sequential high voltage reactor has been developed to study the decomposition of benzene in the air stream at atmospheric pressure. The removal efficiency was measured as a function of ozonation, flow recycling, and flow recirculation. Ozonation in the inlet, and recycling of the exhaust stream increased the removal of benzene, also with increasing of specific input energy (J l⁻¹) the effect of inlet flow ozonation on benzene decomposition was enhanced. The highest removal efficiency was obtained up to >99% in recirculation six times, while CO₂ selectivity reached 99.9% and energy efficiency was 0.59 g kWh⁻¹. O₃ production/ decomposition > production of OH radicals > electronic and ionic collisions were indicated as the main mechanisms influencing benzene abatement in this research.     

Compositional mapping of bitumen using local electrostatic force interactions in atomic force microscopy

In recent years, many researchers have investigated bitumen surface morphology, especially the so‐called bee‐like structures, in an attempt to relate the chemical composition and molecular conformation to bitumen micromechanics and ultimately performance properties. Even though recent studies related surface morphology and its evolution to stiffness and stress localization, the complex chemical nature of bitumen and its time‐ and temperature‐dependent properties still engender significant questions about the nature and origin of the observed morphological features and how they evolve due to exposure to various environmental and loading conditions. One such question is whether the observed surface features are formed from wax or from the coprecipitation of wax and asphaltene. Our prior work was mainly theoretical; it used density functional theory and showed that the coprecipitation theory may not stand, mainly because wax–asphaltene interactions are not thermodynamically favourable compared to wax–wax interactions. This paper presents a comprehensive approach based on experiments to study surface morphology of bitumen and conduct compositional mapping to shed light on the origin of the bee‐like surface morphological features. We used Atomic Force Microscopy (AFM), with the main focus being on single‐pass detection and mapping of local electric properties, as a novel approach to enhance existing compositional mapping techniques. This method was found to be highly effective in differentiating various domains with respect to their polarity. The results of our study favour the hypothesis that the bee‐like features are mainly composed of wax, including a variety of alkanes.     

Two-dimensional analysis of a negative differential conductance gate transistor as a THz emitter

We investigate plasma modes in a transistor including a negative differential conductance in the gate.The analytical results show that the plasma wave generation is substantially influenced by the lateral direction (width of the transistor),gate leakage current and viscosity.The injection from the gate (opposed to the gate leakage current) can improve the plasma oscillations and their amplitude with respect to ordinary transistors.We also estimate,which to our best knowledge has been derived for the first time,the total power emitted by the transistor and the emitted pattern which qualitatively gives reasonable agreement with the experimental data.The results show that the radiated power depends on various parameters such as drift velocity,momentum relaxation time,gate leakage current and especially the lateral direction.A negative gate current enhances the power while the gate leakage current decreases the power.     

Influence of gum tragacanth,Astragalus gossypinus,addition on stability of nonfat Doogh,an Iranian fermented milk drink

In this study, the stabilising property of various concentrations of gum tragacanth in nonfat doogh, an Iranian fermented milk drink, was investigated by measuring phase separation, particle size, flow behaviour and viscoelastic properties. Moreover, light microscopy was used to get more insight into morphological characteristic of protein–polysaccharide complexes in doogh samples. The addition of gum tragacanth improved stabilisation of doogh samples which was associated with an increase in apparent viscosity and storage modulus. Furthermore, the particle size distribution showed an increase in polydispersity and a pronounced reduction in median diameter of protein–polysaccharide complexes which was accompanied by no phase separation at 0.3% concentration of gum tragacanth.     

Surfactant cleaning of ultrafiltration membranes fouled by whey

A polyethersulphone ultrafiltration membrane was prepared for concentration of whey. The membrane was fouled by whey and the effect of different cleaning agents on flux recovery of the fouled membrane was studied. The optimum cleaning procedure for membrane regeneration was elucidated. The results showed that a combination of surfactants (anionic, cationic and nonionic) may be employed as the optimum cleaning agent for maximum flux recovery. The fluorescence studies revealed that the cationic surfactant interact with proteins by breaking the intra‐chain hydrophobic bonding and providing electrostatic repulsion. Changing the alkyl chain from dodecyl to hexadecyl increases the interaction of surfactant–protein. Dodecyltrimethylammonium bromide (DTAB) provided a weak interaction with whey proteins than to tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB). All data obtained in this study support a surfactant–protein interaction in which hydrophobic forces play a dominant role. The nonionic surfactants poly(oxyethylene) isooctyl phenyl ether (TX‐100) and anionic surfactants SDS interact with amino acids in the inner protein structure thus denaturate tertiary protein structure and reduce hydrophobic interaction of proteins by membrane surface.     

硅含量对TIG焊Al-Si/SiCp复合层包覆A380铝合金显微组织的影响

采用钨极惰性气体（TIG）在铸态A380铝合金表面制备复合涂层。将Al,Si和SiC粉末混合物与硅酸钠溶液混合后涂覆在基材上,采用TIG焊进行表面熔化,在基体表面制备Al-SiC涂层。采用XRD、SEM和EDS研究显微组织的变化,采用显微硬度和滑动磨损试验研究包覆层的性能。结果表明,SiC粒子均匀分布在树枝状的铝基体中。加入过量的硅造成包覆层共晶和粗大硅粒子的形成,从而导致包覆层具有较高的硬度和耐磨性。     

TRANSIENT ANALYSIS OF CAPACITOR SWITCHING IN UNBALANCED DISTRIBUTION SYSTEM WITH HARMONIC DISTORTION

ABSTRACT

The wide application of shunt capacitor banks in distribution systems for economic reasons, have raised concern about over-voltage transients and harmonic magnification in unbalanced distribution systems. This paper introduces a new method for transient analysis during capacitor switching. Presence of harmonic sources, unbalance in feeder configuration, and combinations of single-and three-phase loads are accounted for. The new method is a frequency domain-based approach using a three-phase Z-Bus algorithm. The paper reviews the concepts of the building algorithm of a three-phase Z-bus matrix in the complex frequency domain. Untransposed feeders and different types of loads are considered. Finally, the boundary conditions for different capacitor switching cases and the results with harmonic distortion are reported.