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121.
Future systems will be too complex to design and implement explicitly. Instead, we will have to learn to engineer complex behaviours indirectly: through the discovery and application of local rules of behaviour, applied to simple process components, from which desired behaviours predictably emerge through dynamic interactions between massive numbers of instances. This paper describes a process-oriented architecture for fine-grained concurrent systems that enables experiments with such indirect engineering. Examples are presented showing the differing complex behaviours that can arise from minor (non-linear) adjustments to low-level parameters, the difficulties in suppressing the emergence of unwanted (bad) behaviour, the unexpected relationships between apparently unrelated physical phenomena (shown up by their separate emergence from the same primordial process swamp) and the ability to explore and engineer completely new physics (such as force fields) by their emergence from low-level process interactions whose mechanisms can only be imagined, but not built, at the current time. 相似文献
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Franz B. Spingler Adam Phillips Tobias Schuler Michael C. Tucker Adam Z. Weber 《International Journal of Hydrogen Energy》2017,42(19):13960-13969
Reducing mass-transport losses in polymer-electrolyte fuel cells (PEFCs) is essential to increase their power density and reduce overall stack cost. At the same time, cost also motivates the reduction in expensive precious-metal catalysts, which results in higher local transport losses in the catalyst layers. In this paper, we use a hydrogen-pump limiting-current setup to explore the gas-phase transport losses through PEFC catalyst layers and various gas-diffusion and microporous layers. It is shown that the effective diffusivity in the gas-diffusion layers is a strong function of liquid saturation. In addition, it is shown how the catalyst layer unexpectedly contributes significantly to the overall measured transport resistance. This is especially true for low catalyst loadings. It is also shown how the various losses can be separated into different mechanisms including diffusional processes and mass-dependent and independent ones, where the data suggests that a large part of the transport resistance in catalyst layers cannot be attributed to a gas-phase diffusional process. The technique is promising for deconvoluting transport losses in PEFCs. 相似文献
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Andrew Gyekenyesi Adam C. Wroblewski 《Journal of Materials Engineering and Performance》2014,23(2):378-383
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. 相似文献
127.
Adam Rudziński 《Circuits, Systems, and Signal Processing》2014,33(1):197-209
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. 相似文献
128.
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. 相似文献
129.
Adam J. Hall Michael J. Chappell John A.D. Aston Stephen A. Ward 《Computer methods and programs in biomedicine》2014
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. 相似文献
130.
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). 相似文献