Torsion-induced spin precession

We investigate the motion of a spinning test particle in a spatially-flat FRW-type space-time in the framework of the Einstein–Cartan theory. The space-time has a torsion arising from a spinning fluid filling the space-time. We show that, for spinning particles with non-zero transverse spin components, the torsion induces a precession of the particle spin around the direction of the spin of the fluid. We also show that a charged spinning particle moving in a torsion-less spatially-flat FRW space-time in the presence of a uniform magnetic field undergoes a precession of a different character.     

Nanostructured Conducting Polymer/Copper Oxide as a Modifier for Fabrication of L‐DOPA and Uric Acid Electrochemical Sensor

A modified electrode was prepared by modification of the carbon paste electrode (CPE) with a nanostructured material. This nanostructure with electrocatalytic activity was synthesized by combination of poly pyrrole and copper oxide nanoparticles (PPy/CuO). The structure and morphology of PPy/CuO was studied. The fabricated modified electrode (CPE‐PPy/CuO) exhibited an excellent electrocatalytic activity toward levodopa (L‐DOPA) and uric acid (UA) oxidation because of high conductivity, low electron transfer resistance and catalytic effect. The CPE‐PPy/CuO had a lower overvoltage and enhanced electrical current with respect to the bare CPE for both L‐DOPA and UA. Also, the modified electrode showed a good resolution for the overlapped anodic peaks of L‐DOPA and UA. This electrode was used for the successful simultaneous determination of L‐DOPA and UA. The electrochemical sensor responded to L‐DOPA and UA in the concentration range of 0.050–1200 μM and 0.040–2000 μM, respectively. The detection limits were obtained by differential pulse voltammetry as 15 nM for L‐DOPA and 20 nM for UA. Finally, the proposed electrode was used for determination of L‐DOPA and UA in real samples using standard addition method.     

Applications of nanofluids in condensing and evaporating systems

Nanofluids can be utilized as efficient heat transfer fluids in many thermal energy systems to improve the system’s thermal efficiency. This survey reviews and summarizes the experimental and numerical studies performed to determine the effect of nanofluids on the performance of condensing and evaporating systems. Advantages and disadvantages of nanofluid implementation in condensing and evaporating systems are evaluated and summarized. Moreover, some suggestions and recommendations are presented for future studies. This review shows that the nanoparticle deposition and nanoparticle suspension are two important factors affecting the thermal system’s efficiency. These factors should be considered when using different nanofluids in condensing and evaporating systems.     

Vacuum sampling in the landscape during inflation

We consider the phenomenological consequences of sampling multiple vacua during inflation motivated by an enormous landscape. A generic consequence of this sampling is the formation of domain walls, characterized by the scale mu of the barriers that partition the accessed vacua. We find that the success of big bang nucleosynthesis (BBN) implies mu > or = 10 TeV, as long as the sampled vacua have a nondegeneracy larger than O(MeV4). Otherwise, the walls will dominate and eventually form black holes that must reheat the universe sufficiently for BBN to take place; in this case, we obtain mu > or = 10(-5)MP. These black holes are not allowed to survive and contribute to cosmic dark matter density.     

Natural draft dry cooling tower modelling

Predictions based on a numerical simulation of a natural draft dry cooling tower (NDDCT) has been compared with those obtained theoretically and experimentally. Experiments are conducted in a lab-scale NDDCT and are validated with a three-dimensional numerical simulation of the flow in and around the heat exchangers, which is modelled as a porous medium. Both vertical and horizontal arrangements of the heat exchangers are examined. The experimental, numerical and theoretical approaches lead to very close prediction for the air velocity and temperature at the exit of the cooling tower. Results of this study are expected to be useful for future work on the development of air-cooled condensers for geothermal power plants in Australia.     

Thermal Analysis of Flow in a Porous Medium Over a Permeable Stretching Wall

This work presents a similarity solution for boundary layer flow through a porous medium over a stretching porous wall. Two considered wall boundary conditions are power-law distribution of either wall temperature or heat flux which are general enough to cover the isothermal and isoflux cases. In addition to momentum, both first and second laws of thermodynamics analyses of the problem are investigated. Independent numerical simulations are also performed for verification of the proposed analytical solution. The results, from the two independent approaches, are found to be in complete agreement. A comprehensive parametric study is presented and it is shown that heat transfer and entropy generation rates increase with Reynolds number, Prandtl number, and suction to the surface.     

Approximate Entropy in Canonical and Non-Canonical Fiction

Computational textual aesthetics aims at studying observable differences between aesthetic categories of text. We use Approximate Entropy to measure the (un)predictability in two aesthetic text categories, i.e., canonical fiction (‘classics’) and non-canonical fiction (with lower prestige). Approximate Entropy is determined for series derived from sentence-length values and the distribution of part-of-speech-tags in windows of texts. For comparison, we also include a sample of non-fictional texts. Moreover, we use Shannon Entropy to estimate degrees of (un)predictability due to frequency distributions in the entire text. Our results show that the Approximate Entropy values can better differentiate canonical from non-canonical texts compared with Shannon Entropy, which is not true for the classification of fictional vs. expository prose. Canonical and non-canonical texts thus differ in sequential structure, while inter-genre differences are a matter of the overall distribution of local frequencies. We conclude that canonical fictional texts exhibit a higher degree of (sequential) unpredictability compared with non-canonical texts, corresponding to the popular assumption that they are more ‘demanding’ and ‘richer’. In using Approximate Entropy, we propose a new method for text classification in the context of computational textual aesthetics.     

Performance of tubular aluminum foam heat exchangers in multiple row bundles

Two sets of aluminum foam cylinders, 5 and 15 mm thick, are being tested in two-row and three-row bundles for their thermo-hydraulic performance. The bundles are formed using fixed transversal and longitudinal pitch distances and subject to airflow between 0.5 and 5.0 at 0.5 m s^?1 interval under cross-flow. The effects of foam layer thickness and the number of row under staggered configuration are investigated. Thermo-hydraulic results are benchmarking against those of a conventional finned tube bundle of similar dimensions with pre-determined number of fins and assembled using the same pitch distances.