Numerical Study of a Thermal Energy Storage Device Utilizing Graphite Foam Infiltrated with a Phase Change Material

Phase change materials (PCM) utilized for energy storage have notoriously low thermal conductivities. As a result, systems based only on a PCM have large internal thermal gradients and slow reaction times making them impractical for most applications. To overcome these issues, various approaches have been utilized to increase the conductivity of the PCM systems. One approach includes the utilization of porous, high thermal conductivity graphite foam infiltrated with a PCM. Here, a numerical approach was employed in order to study the graphite foam/PCM thermal energy storage system (TES). The numerical model was constructed to emulate an experimental set-up allowing for comparisons between the two. The numerical simulation results exhibited accurate time-dependent temperatures at various locations as well as a history of the melt-front’s progression when compared to the experimental data. Due to the model’s successful capture of the transient response of the TES, it is feasible to employ the numerical procedure for designing subsequent thermal energy storage systems.     

Effective Number of Samples and Pseudo-Random Nonlinear Distortions in Digital OFDM Coded Signal

This paper concerns the theoretical modeling of OFDM coded signal’s degradation caused by pseudo-random nonlinear distortions introduced by an analog-to-digital or digital-to-analog converter. A new quantity, the effective number of samples, is defined and used for the derivation of accurate expressions for the autocorrelation function and the total power of the distortions. The derivation is based on a probabilistic model of the signal and its transition probability. It is shown that for digital (discrete and quantized) signals the effective number of samples replaces the total number of samples and is the proper quantity defining their properties.     

Design and statistical analysis of plasma coatings on superalloy for gas turbine applications

The Influence of plasma sprayed NiCr–Cr₂O₃ and Al₂O₃–40% TiO₂ (A40T) coatings on Inconel 617 are investigated at 900 and 1000 °C under mixed salt environment for gas turbine applications. The results revealed that the plasma coated alloy exhibits lower mass change than bare alloy in the Na₂SO₄ and NaCl salt mixture with and without V₂O₅. The response to the experimental analysis is statistically evaluated using 2³ factorial design. Further the exposed samples were analyzed by means of optical image, SEM, EDS and XRD results. The EDS and XRD analysis revealed that the oxides are rich in Ni and Mo on the surface of the samples. The coated samples exhibited better corrosion resistance in A40T when compared to NiCr–Cr₂O₃ coatings than bare alloy.     

Reprint of “Pharmacokinetic modelling of the anti-malarial drug artesunate and its active metabolite dihydroartemisinin”

A four compartment mechanistic mathematical model is developed for the pharmacokinetics of the commonly used anti-malarial drug artesunate and its principle metabolite dihydroartemisinin following oral administration of artesunate. The model is structurally unidentifiable unless additional constraints are imposed. Combinations of mechanistically derived constraints are considered to assess their effects on structural identifiability and on model fits. Certain combinations of the constraints give rise to locally or globally identifiable model structures.     

Thiazolidinediones: An In–Depth Study of Their Synthesis and Application to Medicinal Chemistry in the Treatment of Diabetes Mellitus

2,4-Thiazolidinedione (TZD) is a privileged and highly utilised scaffold for the development of pharmaceutically active compounds. This sulfur-containing heterocycle is a versatile pharmacophore that confers a diverse range of pharmacological activities. TZD has been shown to exhibit biological action towards a vast range of targets interesting to medicinal chemists. In this review, we attempt to provide insight into both the historical conventional and the use of novel methodologies to synthesise the TZD core framework. Further to this, synthetic procedures utilised to substitute the TZD molecule at the activated methylene C₅ and N₃ position are reviewed. Finally, research into developing clinical agents, which act as modulators of peroxisome proliferator-activated receptors gamma (PPARγ), protein tyrosine phosphatase 1B (PTP1B) and aldose reductase 2 (ALR2), are discussed. These are the three most targeted receptors for the treatment of diabetes mellitus (DM).     

Failure Analysis of a Composite Rudder Stock Using 3D X-ray Microcomputed Tomography

Journal of Failure Analysis and Prevention - A failure analysis investigation was performed on the remnants of a carbon fiber rudder stock that fractured during operation on a vessel in an offshore...     

Fabrication of BSCF-based mixed oxide ionic-electronic conducting multi-layered membrane by sequential electrophoretic deposition process

The Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF)-based multi-layered oxygen separation membrane was fabricated by the sequential electrophoretic deposition (EPD) process. A thin porous/dense bi-layer of BSCF was formed on a thick porous support of BSCF. The porous support prepared by a sacrificial template method using BSCF powder mixed with wheat starch (30 wt%) as a pore-forming agent, followed by uniaxial pressing and low-temperature sintering, was directly used as an EPD electrode. A thin BSCF layer was first formed on the porous support, and then a thin BSCF + PMMA (polymethyl methacrylate) layer was sequentially formed on the thin BSCF layer using a bimodal suspension of BSCF and PMMA. A 30-μm thin porous/dense bi-layer of BSCF of which the total thickness was obtained by optimizing the processes of EPD and subsequent co-sintering. The oxygen separation performance of 3.7 ml (STP) min^?1 cm^?2 at 860 °C was achieved for the BSCF-based multi-layered oxygen separation membrane.     

Virtual fencing technology to intensively graze lactating dairy cattle. II: Effects on cow welfare and behavior

Virtual fencing technology uses a neckband-mounted device to deliver an audio cue when an animal nears a virtual boundary that is set via a global positioning system, followed by an electrical stimulus if it crosses the boundary. The flexibility offered by this technology could revolutionize grazing management on dairy farms, but its application and effects on lactating dairy cattle have not been assessed. This experiment reports on the effects of an electric or a virtual front-fence on dairy cow behavior and welfare. Two temporally separated treatments were applied to a herd of 30 multiparous cows. Cows were provided an estimated 14 to 15 kg of dry matter/cow of fresh pasture in a new paddock every 24 h. From d 1 to 10 cows were grazed using a conventional electric front-fence (control treatment) and from d 14 to 23 they were grazed using a virtual front-fence (eShepherd, Agersens Pty Ltd.). Cows were trained to the technology from d 11 to 13. The milk production and live weight of individual cows were recorded daily. Cortisol concentrations were obtained from milk samples collected from individual cows on 3 d during each of the control and the virtual fence grazing periods, plus the first day of training. From d 6 of the experiment, 6 focal cows were fitted with a RumiWatch (Itin + Hoch GmbH) noseband sensor to monitor grazing and ruminating time, and 8 focal cows were fitted with an IceTag (IceRobotics Ltd.) sensors to monitor activity. Milk production, live weight, and the time cows spent standing and lying did not differ between the electric and virtual fence periods. Milk cortisol concentrations, activity, and the times spent ruminating and grazing were comparable between the electric and early virtual fence periods (i.e., d 1–3 with a virtual fence). However, at d 4 to 6 with a virtual fence, activity (steps taken and motion index) and time spent grazing were lower, and time spent ruminating was greater, compared with an electric fence. Further, least significant difference tests suggest milk cortisol concentrations were higher at d 5 with a virtual fence than at d 8 with an electric fence and d 1 with a virtual fence. We conclude there is no evidence of behavioral and welfare effects of virtual fencing on dairy cows in the days immediately following implementation of the technology in a simple intensive grazing regimen, but a longer study is required to fully elucidate effects beyond this period.