Steric stabilization of Stöber silica dispersions using organosilanes

Organosilanes of the general formula R _x Si(OR)_4–x (where R is an alkyl group and R = CH₃ or CH₂CH₃) were used to sterically stabilize hexane dispersions of submicrometre silica spheres. The dispersions were characterized according to sediment volume results. For 0.5m silica particles, the sediment density increased by more than a factor of three up to 50 to 55% of theoretical in the presence of organosilanes with 12 or more carbons in the R group. Solid-state¹³C nuclear magnetic resonance was used to characterize the powder-dispersant interaction; this technique can distinguish between carbons in the R group of the organosilane and residual organic groups in the silica. Scanning electron micrographs of filter compacts were used to further characterize the dispersions and indicated the presence of primary particles as well as small agglomerates.     

严重事故工况下 M31核电机组应急补水设施可用性研究

国内核电厂吸取福岛事故的经验教训,增加了严重事故后应急补水设施,完善了应急补水的相关功能,进一步提高了核电厂的安全水平.对M 310核电机组严重事故状态下的应急补水设施进行技术分析,分析计算结果表明,应急水源到应急补水泵接入点距离过长,水损过大,实际补水压力及流量无法满足设计要求.针对该问题提出一系列设计改进措施,优化改进后的应急补水设施可保证严重事故工况下M 310核电机组应急补水设施的可用性,从而进一步提高核电机组的安全性.     

Characteristics of heavy-oil-in-water emulsions containing produced sand

Heavy-oil-in-water (o/w) emulsions containing produced sand were prepared using commercially available emulsifiers. The emulsions were tested in beakers for emulsion type, quality, and sand-retention characteristics. The apparent viscosities of the o/w emulsions were measured. The effects of polymer addition on the apparent viscosity and sand-carrying capability of the emulsions were also studied. The results of the breaker tests indicate that most emulsifier solutions water-wet the beaker wall and temporarily improve heavy-oil flow characteristics. However, most of the chemicals also water-wet the sand particles and cause sand dropout. The Flothin F2 chemical alone showed stable oil dispersion and, in combination with the Flocon 4800C polymer, showed very good sand-retention, viscosity-reduction, and stable oil-dispersion characteristics.     

Effect of Composition and Size of Crystallite on Crystal Phase in Lead Barium Titanate

Lead titanate, barium titanate, and lead barium titanate powders (>99.9% pure), the particle size of which varied from 0.03 to 0.15 μm depending on the calcination temperature and the composition, was prepared from barium lead titanyl oxalate, which was previously prepared by reacting high-purity ammonium titanyl oxalate with barium and lead acetate. The critical crystallite size of BaTiO₃ powder from the cubic to the tetragonal phase is around 1 μm. Pb_0.3Ba_0.7TiO₃ powder with an average size of 0.057 μm showed the tetragonal phase.     

Amorphization Boost Multi-Ions Storage for High-Performance Aqueous Batteries

Regarding the complex properties of various cations, the design of aqueous batteries that can simultaneously store multi-ions with high capacity and satisfactory rate performance is a great challenge. Here an amorphization strategy to boost cation-ion storage capacities of anode materials is reported. In monovalent (H⁺, Li⁺, K⁺), divalent (Mg²⁺, Ca²⁺, Zn²⁺) and even trivalent (Al³⁺) aqueous electrolytes, the capacity of the resulting amorphous MoO_x is more than quadruple than that of crystalline MoO_x and exceeds those of other reported multiple-ion storage materials. Both experimental and theoretical calculations reveal the generation of ample active sites and isotropic ions in the amorphous phase, which accelerates cation migration within the electrode bulk. Amorphous MoO_x can be coupled with multi-ion storage cathodes to realize electrochemical energy storage devices with different carriers, promising high energy and power densities. The power density exceeded 15000 W kg⁻¹, demonstrating the great potential of amorphous MoO_x in advanced aqueous batteries.     

A multisource energy harvesting utilizing highly efficient ferroelectric PMN-PT single crystal

This paper demonstrates a multi-source energy harvester that is able to utilize simultaneously both piezoelectric and pyroelectric effects in lead magnesium niobate-lead titanate (PMN-PT) single crystal. The paper presents a study of PMN-PT single crystal with a (67:33) composition grown in our laboratory via a vertical gradient freeze method without any flux. The performance of the piezoelectric and pyroelectric energy harvester using unimorph device structure was evaluated via modeling and experiment. The theoretical study was implemented based on a distributed parameter electromechanical model and the modelling procedure was approximated using finite element analysis to predict the electromechanical behavior of the harvester. The maximum power density at a resonance frequency of 50 Hz and optimum resistance of 2 MΩ was 16.7 nW/(g² cm³) under a 1 g acceleration of vibration. The measured values of electrical output parameters were in good agreement with theoretical and modelling results using MATLAB and COMSOL Multiphysics, respectively. By using the pyroelectric effect along with the piezoelectric effect, the output voltage of the energy harvester was found to be enhanced at the optimum resistance and specific frequency values. It was noticed that the output voltage was increased monotonically with temperature-difference (ΔT) and reaches up to 180 % of its original value under temperature difference of 1.7 °C at a frequency value of 49 Hz.     

Algebraic approach to linking the semantics of web services

Web services have become more and more important in these years, and BPEL4WS (BPEL) is a de facto standard for the web service composition and orchestration. It contains several distinct features, including the scope-based compensation and fault handling mechanism. We have considered the operational semantics and denotational semantics for BPEL, where a set of algebraic laws can be achieved via these two models, respectively. In this paper, we consider the inverse work, deriving the operational semantics and denotational semantics from algebraic semantics for BPEL. In our model, we introduce four types of typical programs, by which every program can be expressed as the summation of these four types. Based on the algebraic semantics, the strategy for deriving the operational semantics is provided and a transition system is derived by strict proof. This can be considered as the soundness exploration for the operational semantics based on the algebraic semantics. Further, the equivalence between the derivation strategy and the derived transition system is explored, which can be considered as the completeness of the operational semantics. Finally, the derivation of the denotational semantics from algebraic semantics is explored, which can support to reason about more program properties easily.     

Linking denotational semantics with operational semantics for web services

Web Services have become more and more important in these years, and BPEL4WS (BPEL) is a de facto standard for the web service composition and orchestration. It contains several distinct features, including the scope-based compensation and fault handling mechanism. The denotational semantics and operational semantics have been explored for BPEL. The two semantic models should be consistent. This paper considers the linking of these two semantics. Our approach is to derive the denotational semantics from operational semantics for BPEL, which aims for the consistency of the two models. Moreover, the derivation can be applied in exploring the program equivalence easily, especially for parallel programs.     

Formal Versus Agile: Survival of the Fittest

Many research have focused on new formal methods, integrating formal methods into agile ones, and assessing the agility of formal methods. This paper proves that formal methods can survive in an agile world; they are not obsolete and can be integrated into it. The potential for combining agile and formal methods holds promise. It might not always be an easy partnership, and succeeding will depend on a fruitful interchange of expertise between the two communities. Conducting a realistic trial project using a combined approach with an appropriate formal methods tool in a controlled environment will help assess the effectiveness of such an approach.