Analysis of electrochemical mechanism of coprecipitated nano-Ag4Bi2O5 as super high charge–discharge rate cathode materials for aqueous rechargeable battery

Nano Ag₄Bi₂O₅ as a novel cathode material of rechargeable alkaline batteries was successfully synthesized by precise control of precipitation reaction. KOH solution was used as precipitant and a mixture of AgNO₃ and Bi(NO₃)₃ as Ag–Bi source. The experimental results indicate that concentration of KOH, reaction temperature and PH value have the effects on the structure and electrochemical property of the product. The material was characterized by means of XRD, FSEM and TG–DSC. The results show that the sample is single crystals with 50–100 nm in width and 600–800 nm in length. The electrochemical performances of Ag₄Bi₂O₅ in the alkaline electrolyte were measured by galvanostatic method and cyclic voltammetry tests through film electrode. The sample shows three typical procedures during the charge–discharge, corresponding to Ag(II)–Ag(I), Ag(I)–Ag(0) and Bi(III)–Bi(0) transformation processes. This result is also verified by XRD tests. The Ag₄Bi₂O₅ electrode has excellent electrochemical properties. It undergoes a current density as high as 20 A g^?1, which greatly reduces charge time down to 55.9 s. The electrode offers a cycling capacity of 330 mAh g^?1 and a cycling life more than 400 cycles at 1–2 A g^?1.     

Corrosion behavior of a duplex stainless steel under cyclic loading: a scanning Kelvin probe force microscopy (SKPFM) based microscopic study

Corrosion fatigue behavior of the duplex stainless steel AISI 2205 was studied by the scanning Kelvin probe force microscopy (SKPFM) in the ambient temperature and pressure condition (25?°C, one standard atmospheric pressure). Surface-polished AISI 2205 samples were subject to a cyclic tensile stress while immersed in a 0.5?M NaCl solution. At specified time intervals, surface Volta potential of the samples was measured using the SKPFM in an oxygen and water regulated environment. The steel samples demonstrated a map of potentials with high contrasts between ferritic and austenitic grain domains, which was then linked to the actual corrosion potential (w.r.t. a saturated calomel electrode—SCE) based on a rigorous calibration procedure. The corrosion fatigue behavior of AISI 2205 was studied by comparing the SKPFM-measured Volta potentials of the same sample under applied cyclic strain and under no applied cyclic strain. It was found that AISI 2205 became more prone to corrosion when the applied tensile strain exceeds one percent (1?%).     

彩色清水混凝土施工工法

彩色混凝土产品是一种全新施工理念的装饰面层材料，清水混凝土一次浇筑成型，不作任何外装饰，直接采用混凝土自然色作为饰面。作为二者结合的彩色清水混凝土减少了饰面工序，具有平整光滑、色泽均匀、主体结构浑然天成等优点，但其较高的表面质量（无蜂窝、麻面、砂带等）与特性（色彩控制等）对施工工法提出了更高的要求。结合作者多年施工经验，在大量实验基础上，对彩色清水混凝土施工工法进行了总结，有效提高了产品质量及其稳定性，从而衬托出主体结构自然天成的风格。     

Provisioning virtualized Cloud services in IP/MPLS-over-EON networks

Cloud computing enables the provisioning of resources in a reliable and on-demand manner. With the increasing importance of the network bandwidth in the Cloud environment, the networking related resources need to be optimally allocated together with the traditional Cloud computing resources. In addition, the significant growth of the global data center traffic raises the challenge of supporting demands with large bandwidth requirements for the Cloud provider. In our paper, we consider the network-efficient virtualized cloud infrastructure provisioning problem in IP over elastic optical network (IP-over-EON) based on the data center as a service model. The elastic optical network is adopted to provide spectrum and cost-efficient networking resources for large bandwidth requests in our work. We develop mixed integer linear programming formulations to construct the mathematic model for this problem and propose a cost-optimized heuristic to solve this problem. To investigate the cost and blocking rate for the served demands, different modulation formats are compared in the EON layer, and the sliceable bandwidth-variable transponders and optical traffic grooming technology are considered. The experimental results show that different modulation formats that are adopted in the EON layer will have different impacts on the total cost and demand blocking rate for the same data set size. Also the use of SBVT will reduce the total cost no matter which modulation format is adopted, and the reduction is related to the bandwidth requirement of the demands.     

1 000 MW高效宽负荷率的超超临界锅炉开发

根据反平衡法对电站锅炉各项效率损失进行分析，潜力较大的是排烟损失和未完全燃烧损失，主要影响因素有过量空气系数、排烟温度、燃烧效率；1 000 MW高效宽负荷率超超临界煤粉锅炉的开发采用低过量空气系数设计理念，在炉膛选型、受热面布置、燃烧系统设计、降低锅炉漏风等方面采取措施。与传统设计相比，50% THA负荷下锅炉效率提升了0.96%。     

Rare earth element cerium substituted Ca–Si–Mg system bioceramics: From mechanism to mechanical and degradation properties

Cerium (Ce)-substituted diopsides (CaMgSi₂O₆) with enhanced mechanical strength and bioactivity were fabricated by precipitation method, followed by annealing at 1000 °C for 4 h. The mineralogical, morphological, in vitro biomineralization, degradation, and mechanical properties were investigated in order to assess the factors and mechanisms affecting the resultant properties. The X-ray diffractometer results showed that the onset of substitutional solid solubility in 0.25 mol Ce would result in new phase formation (cerium dioxide [CeO₂], and magnesium silicate [MgSiO₃]) further causing lattice instability. With increasing Ce dopant levels to 1.00 mol, the initial CaMgSi₂O₆ phase was completely replaced by new phases. The field-emission scanning electron microscopy results indicated that the 0.25 mol Ce had the best biomineralization performance in vitro, while less hydroxyapatite precipitates were found with further increasing Ce dopant levels, suggesting the new phases led to the hindrance of precipitates. The weight loss values indicated that the high dissolution rate of ions in the matrix was observed in the pure sample, while the high readsorption rate of ions in the simulated body fluid (SBF) occurred with increasing Ce dopant levels. The pH value and the inductively coupled plasma-mass spectrometer results suggested that the release of Ca and Mg ions controlled the pH value. The mechanical strength of matrices before SBF immersion was related to the phase transformation, the elastic modulus of CeO₂ and CaMgSi₂O₆, and the release of Mg ions, while the mechanical strength of matrices after SBF immersion was dominated by the structure of matrices.     

Combustion enhancement and inhibition of hydrogen-doped methane flame by HFC-227ea

Hydrogen enriched with compressed natural gas is an efficient and environment-friendly gaseous fuel. However, the safety issues of mixture and the method to control or weaken their combustion are highly concerned. To explore the inhibition effect of halogenated fire suppressants on the mixture, the effect of HFC-227ea on the laminar premixed methane/air flames, with different fractions of H₂, have been studied. Burning velocities have been measured with constant-volume combustion chamber and kinetically modelled a recently assembled kinetic mechanism. The fractions of H₂ influence the enhancement and inhibition effect of HFC-227ea, and it is less effective with the lean mixture. In stoichiometric condition, HFC-227ea showed good inhibition effect on the mixture flames. The HFC-227ea increased the burning velocities of CH₄-0% H₂-air and CH₄-10% H₂-air flames at leanest condition, whereas the increased burning velocity arising from HFC-227ea not occurred as the addition of H₂ above 20%. Experimental results coincided well with numerical results, however the agreement was poor for the leanest flames at low agent loading. Lastly, kinetic mechanism analysis was used to interpret the combustion enhancement and inhibition effect of hydrogen-doped methane flame by HFC-227ea.     

高压气淬设备与工艺

简要介绍了气体淬火介质及ECM气体淬火设备的特性,同时介绍了ECM气体分级淬火工艺的原理,并结合实际生产案例,论述了分级气淬工艺较普通气淬工艺的优越性。