Cold compaction molding and sintering of polystyrene

It is the objective of this paper to demonstrate the applicability of cold compaction molding followed by a sintering treatment to the processing of polystyrene powders. The influence of pressure, compaction speed, and peak pressure dwell time on the green (as compacted) density and the green tensile strength, as well as the effect of sintering on the tensile strength and dimensional change, were evaluated. The resulting data indicate that room temperature compaction alone is insufficient to provide adequate tensile strength for the compacts. Sintering the green compacts at temperatures of 150 to 173°C markedly improves the tensile strength while simultaneously causing a thickness change in the compacts. This thickness change results from gas evolution, pore shrinkage, and viscoelastic recovery of the residual stresses induced by pressure. For compacts of 0.225 in. thickness, an optimum sintering treatment of 173°C for 30 mins is recommended to provide a tensile strength of 4,000 psi and a thickness change of less than + 7 percent. Coining (repressing) the green compacts does not appreciably affect the sintered strength. However, a finer particle size improves the sintered properties. A review of the literature on the flow behavior of polystyrene suggests that a non-Newtonian viscous flow mechanism is followed by a Newtonian one as sintering progresses.     

Co-hydrothermal gasification of microbial sludge and algae Kappaphycus alvarezii for bio-hydrogen production: Study on aqueous phase reforming

In this study, wastewater obtained from a sewage treatment plant was treated successively by using microbial consortium and macroalgae Kappaphycus alvarezii to generate microbial sludge and algal biomass. The production of green fuel was carried out via co-gasification of microbial sludge and macroalgae Kappaphycus alvarezii for a duration of 60 min, feedstock to solvent ratio (5 to 20 g of feedstock in 200 mL), sludge to algae ratio (ranging from 1:1 to 3:1) and temperature (300–400 °C) respectively. Maximum bio-hydrogen yield was 36.1% and methane yield was 38.4% at a temperature of 360 °C at a feedstock to solvent ratio of 15:200 g/mL and sludge to algae ratio of 2:1 individually. The liquid by product of co-gasification process was later subjected to photocatalytic reforming, resulted in an enhanced hydrogen composition of 61.25%.     

Effect of hydrogen jets in supersonic mixing using strut injection schemes

The prevalence of complex phenomena associated with the fuel mixing of a supersonic stream in scramjet combustor is inherently occurred due to the short residence time. An efficient injection mechanism is required to enhance the mixing and improve combustion efficiency. This numerical simulation study aims to reveal the performance of modified strut injection strategies within a Mach 2.0 flow field. Two-dimensional steady and transient Navier-Stokes computations of the DLR scramjet experiment is performed for various strut injection locations. The Reynolds Averaged Navier Stokes equation with the SST k-ε turbulence model is utilized to solve the flow field under steady conditions. The critical parameters examined to investigate steady solutions are wall static pressure, flow Mach number, and total pressure loss across the combustor. The dual injection configuration in the flow considerably reduces the shock waves impact at the downstream of the strut and preserves the magnitude of internal forces acting on combustor walls and total pressure loss. Unsteady Detached Eddy Simulation (DES) results for hydrogen concentration and velocity field are analyzed by applying Dynamic Mode Decomposition (DMD). Multiple injections are observed to alter the frequency and the number of dominant modes.     

Noble metal-free FeN-CNFs as an efficient electrocatalyst for oxygen reduction reaction

Carbonaceous materials containing non-precious metal atoms and doped with nitrogen have enthralled stunning attention in the field of electrochemical energy conversion systems. Herein, we demonstrated a facile method to fabricate iron and nitrogen doped carbon nanofiber (FeN-CNFs) catalyst material from ferric chloride and interfacial synthesized polyaniline (PANI) nanofibers, by carbonization process in an inert atmosphere at 800 °C. Further, synthesized material was characterized by elemental analysis and X-ray photoelectron spectroscopy (XPS) that confirms the presence of FeN bonds. The structural and morphological features are studied using various microscopy and spectroscopy techniques. The oxygen reduction reaction (ORR) activity of synthesized catalyst materials was examined by rotating disk electrode experiments in 0.1 M KOH. Among all these synthesized materials FeN-CNFs material showed enhanced ORR activity regarding current density and onset potential. Also, FeN-CNFs catalyst exhibited tolerance to methanol and durability in comparison to commercial Pt/C catalyst. The superior performance of FeN-CNFs may be attributed due to the introduction of Fe and formation of FeN bond in catalyst material.     

Semantics of EqL

The formal semantics of a novel language, called EqL, are presented for first-order functional and Horn logic programming. An EqL program is a set of conditional pattern-directed rules, where the conditions are expressed as a conjunction of equations. The programming paradigm provided by this language may be called equational programming. The declarative semantics of equations is given in terms of their complete set of solutions, and the operational semantics for solving equations is an extension of reduction, called object refinement. The correctness of the operational semantics is established through the soundness and completeness theorems. Examples are given to illustrate the language and its semantics.<>     

The Wearable Motherboard™: The first generation of adaptive and responsive textile structures (ARTS) for medical applications

Virtual reality (VR) has been making inroads into medicine in a broad spectrum of applications, including medical education, surgical training, telemedicine, surgery and the treatment of phobias and eating disorders. The extensive and innovative applications of VR in medicine, made possible by the rapid advancements in information technology, have been driven by the need to reduce the cost of healthcare while enhancing the quality of life for human beings.In this paper, we discuss the design, development and realisation of an innovative technology known as the Georgia Tech Wearable Motherboard (GTWM), or the Smart Shirt. The principal advantage of GTWM is that it provides, for the first time, a very systematic way of monitoring the vital signs of humans in an unobtrusive manner. The flexible databus integrated into the structure transmits the information to monitoring devices such as an EKG machine, a temperature recorder, a voice recorder, etc. GTWM is lightweight and can be worn easily by anyone, from infants to senior citizens. We present the universal characteristics of the interface pioneered by the Georgia Tech Wearable Motherboard and explore the potential applications of the technology in areas ranging from combat to geriatric care. The GTWM is the realisation of a personal information processing system that gives new meaning to the termubiquitous computing. Just as the spreadsheet pioneered the field of information processing that brought computing to the masses, it is anticipated that the Georgia Tech Wearable Motherboard will bring personalised and affordable healthcare monitoring to the population at large.     

Effect of Process Parameters on Tensile Strength of Friction Stir Welded Cast LM6 Aluminium Alloy Joints

This paper reports the effect of friction stir welding(FSW)process parameters on tensile strength of cast LM6 aluminium alloy.Joints were made by using dierent combinations of tool rotation speed,welding speed and axial force each at four levels.The quality of weld zone was investigated using macrostructure and microstructure analysis.Tensile strength of the joints were evaluated and correlated with the weld zone hardness and microstructure.The joint fabricated using a rotational speed of 900 r/min,a weldin...