Effects of special nanoparticles on fuel cell properties of sulfonated polyethersulfone membrane

Polyethersulfone was sulfonated by changing the reaction time with sulfuric acid. The degree of sulfonation and ion exchange capacity were determined. Sulfonation of polyethersulfone was confirmed by FT-IR analysis and a new peak at 1025 cm^?1. Inorganic materials such as carbon nanotubes, graphene, and kaolinite nanoparticles were synthesized. The effects of three nanoparticles on thermal stability and water uptake of sulfonated polyethersulfone were investigated. The morphology of membranes were also altered due to the addition of inorganic materials. The proton conductivity of the modified membranes increased with respect to increase in relative humidity.     

Defect Characterization Using Pulsed Thermography

Infrared Thermography is one of the advanced NDE methods that is becoming attractive due to its ability to inspect non invasively large areas in short times and provide full field images in a non contact nature. While initially the method started as a qualitative technique for defect detection alone, with the advent of lock in and pulsed techniques, quantitative defect detection was made possible. While these techniques have been applied in case of ceramics and composites for defect quantification, defect sizing and quantification using these methods have not been systematically attempted in case of stainless steels. A systematic study has been undertaken to evaluate the accuracy of these empirical Pulsed Thermography (PT) techniques for defect size and depth estimation in type 316 L austenitic stainless steels. Theoretical modelling based on finite difference analysis using Thermo Calc 6L software has also been done and the results compared.     

配给能源采集供电:无线传感器节点的功率约束

让周遭的系统能够自动感测环境变化并做出反应，势必将对于人类的生活造成重大改变。无线传感器网络是多个分布式传感器实作（节点）组成的系统，能够共同透过相互无线通信的方式响应实体变化。本文将重点介绍节点的最新进展，并推广对于系统层级设计方法的需求。     

Comparative study on the heat transfer performance of micro-grooved anodized thermosyphon with R134a,R600a and R717 for low-temperature applications

Journal of Mechanical Science and Technology - A comparative heat transfer performance of an internally grooved anodized thermosyphon with eco-friendly refrigerants is presented in this study....     

Optimisation of process parameters for electroless nickel plating on SS316L for refrigeration systems

Nowadays, refrigeration systems are important for industrial and domestic applications. The coefficient of performance of a vapour compression refrigeration system can be improved if a reduction in the work of compression can be achieved by a suitable technique for a specified heat removal rate. The present study investigates the effect of material coating of electroless nickel (EN) plating. The friction and wear experiments were performed using a four-ball machine tribo tester. Controlling the EN plating parameters plays an important role in the quality of coating. It depends on the wear scar rate of the coated material. So it is necessary to optimise the process parameters of EN plating. The experimental studies have been conducted under varying pressure, load and time on quality characteristics. In this paper, optimisation of process parameters using response surface methodology technique for EN plating was discussed.     

Collecting Statistics over Runtime Executions

By collecting statistics over runtime executions of a program we can answer complex queries, such as “what is the average number of packet retransmissions” in a communication protocol, or “how often does process P₁ enter the critical section while process P₂ waits” in a mutual exclusion algorithm. We present an extension to linear-time temporal logic that combines the temporal specification with the collection of statistical data. By translating formulas of this language to alternating automata we obtain a simple and efficient query evaluation algorithm. We illustrate our approach with examples and experimental results.     

Processing, physical and thermal properties of BlackglasTM matrix composites reinforced with NextelTM fabric

The cure and pyrolysis behavior of a BlackglasTM resin and NextelTM 440 impregnated with BlackglasTM resin were studied. Cure of the BlackglasTM resin is an exothermic process and DSC studies indicate that with an increase of catalyst content from 0.1 to 1.0%, the onset and peak temperature of cure are decreased coupled with an increase in the enthalpy of cure indicating a greater extent of cross linking. However, pyrolysis char yield of the pyrolyzate is relatively insensitive to cure conditions.Cure pressure and pyrolysis environment are variables in the processing of BlackglasTM matrix composite reinforced with NextelTM 440 Plain weave fabric. Variations in cure pressure from 30 to 80 psi had no discernible effect on the chemistry of the pryrolyzate. However, the higher cure pressure resulted in top and bottom ply damage. Pyrolysis in an Ar environment resulted in incorporationj of up to 12 wt % C of which 8 wt % as graphitic in nature in the ceramic matrix. Pyrolysis in NH3 resulted in 3.9 wt % nitrogen and 1.5 wt % carbon in the matrix, with all the nitrogen and carbon bonded to Si. The cured panels have to be pyrolyzed/densified between 6–7 times to achieve required density and porosity content. Oxidation behavior of the composites at 1000°C indicate that the argon pyrolyzed CMC's lose more weight due to decomposition of the pyrolytic carbon, whereas, NH3 pyrolyzed CMC's are stable as both the N and C are bonded to Si in the matrix. Dielectric constants K and K measured at 1 GHz in the as-processed condition are high in the argon pyrolyzed CMC, (K = 11–28) due to the presence of pyrolytic carbon. On the other hand NH3 pyrolyzed CMC exhibit low dielectric constant (K = 4). On oxidation, the dielectric constant in both the Ar and NH3 pyrolyzed panels is approximately 4.0.     

Small-signal conductance vs temperature: A rapid means of determining the nature of current transport in high-doped n-GaAs Schottky barrier diodes

Measurements of small-signal forward conductance vs temperature at a constant bias current, and the reverse conductance vs temperature at a constant bias voltage have been carried out on ion-implanted n-GaAs Schottky barrier diodes fabricated on semi-insulated substrates, for the temperature range of 97–340 K. The results obtained have been interpreted in terms of diode ideality factors and compared with those calculated using the thermionic field emission model for the forward bias case and the pure field emission model for the reverse bias case.