Performance analysis of a metal hydride refrigeration system

The varying applications of metal hydride refrigeration systems, such as cold storage and space air conditioning, grant them important advantages over conventional ones. These advantages include being a low-grade heat driven, more environmentally friendly and renewable working fluid with greater compactness and fewer moving parts. However, a metal hydride refrigeration system always operates under unsteady conditions due to the cyclic hydriding and dehydriding processes involved. To analyse and optimise the metal hydride refrigeration system’s design and performance, in this paper, a comprehensive transient system model has been developed with a new and revised intrinsic kinetic correlation inclusive of the essential operating controls and applicable process conditions of regeneration, cooling and transitions in between. In addition, the correlative model on the characterisation process of pressure, concentration and temperature (PCT) profiles for the metal hydride alloys employed in the system has been developed and is introduced briefly in this paper. It is integrated in the system model and ensures the accurate prediction of maximum capacities for the metal hydride isothermal desorption and absorption processes. The developed transient system model has been validated through comparison with experimental results from literature on the medium-temperature cooling process of a metal hydride refrigeration system. The model simulation is conducted for a specially designed low-temperature metal hydride refrigeration system at different operating conditions and controls. In quantity, when the high-grade heat source temperature increases from 90 ◦C to 120 ◦C, the low-grade heat source temperature increases from − 20 ◦C to 10 ◦C, the medium-grade heat sink temperature decreases from 30 ◦C to 15 ◦C, and the time period for regeneration or cooling process decreases from 10 min to 4 min, the cooling COP increases by 112.0%, 136.6%, 19.3% and 31.8% respectively. The optimisation strategies for the system operating conditions and controls are therefore recommended based on the detailed performance analyses of the system simulation results

The question of ‘alternatives’ within food and drink markets and marketing: introduction to the special issue

The question of 'alternatives' within food and drink markets and marketing: introduction to the special issu

FeynEdit - a tool for drawing Feynman diagrams

We describe the FeynEdit tool for drawing Feynman diagrams. Input and output is done using the LaTeX macros of FeynArts, which also implies that diagrams drawn by FeynArts can be edited with FeynEdit. The LaTeX code can be conveniently transferred using copy-and-paste.Comment: 9 pages, uses feynarts.st

Coexisting periodic attractors in injection locked diode lasers

We present experimental evidence for coexisting periodic attractors in a semiconductor laser subject to external optical injection. The coexisting attractors appear after the semiconductor laser has undergone a Hopf bifurcation from the locked steady state. We consider the single mode rate equations and derive a third order differential equation for the phase of the laser field. We then analyze the bifurcation diagram of the time periodic states in terms of the frequency detuning and the injection rate and show the existence of multiple periodic attractors.Comment: LaTex, 14 pages, 6 postscript figures include

Modular differential equations for torus one-point functions

It is shown that in a rational conformal field theory every torus one-point function of a given highest weight state satisfies a modular differential equation. We derive and solve these differential equations explicitly for some Virasoro minimal models. In general, however, the resulting amplitudes do not seem to be expressible in terms of standard transcendental functions.Comment: 19 pages, LaTeX; reference adde

Genome characterization and population genetic structure of the zoonotic pathogen, streptococcus canis

Background - Streptococcus canis is an important opportunistic pathogen of dogs and cats that can also infect a wide range of additional mammals including cows where it can cause mastitis. It is also an emerging human pathogen. Results - Here we provide characterization of the first genome sequence for this species, strain FSL S3-227 (milk isolate from a cow with an intra-mammary infection). A diverse array of putative virulence factors was encoded by the S. canis FSL S3-227 genome. Approximately 75% of these gene sequences were homologous to known Streptococcal virulence factors involved in invasion, evasion, and colonization. Present in the genome are multiple potentially mobile genetic elements (MGEs) [plasmid, phage, integrative conjugative element (ICE)] and comparison to other species provided convincing evidence for lateral gene transfer (LGT) between S. canis and two additional bovine mastitis causing pathogens (Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. dysgalactiae), with this transfer possibly contributing to host adaptation. Population structure among isolates obtained from Europe and USA [bovine = 56, canine = 26, and feline = 1] was explored. Ribotyping of all isolates and multi locus sequence typing (MLST) of a subset of the isolates (n = 45) detected significant differentiation between bovine and canine isolates (Fisher exact test: P = 0.0000 [ribotypes], P = 0.0030 [sequence types]), suggesting possible host adaptation of some genotypes. Concurrently, the ancestral clonal complex (54% of isolates) occurred in many tissue types, all hosts, and all geographic locations suggesting the possibility of a wide and diverse niche. Conclusion - This study provides evidence highlighting the importance of LGT in the evolution of the bacteria S. canis, specifically, its possible role in host adaptation and acquisition of virulence factors. Furthermore, recent LGT detected between S. canis and human bacteria (Streptococcus urinalis) is cause for concern, as it highlights the possibility for continued acquisition of human virulence factors for this emerging zoonotic pathogen