3,786 research outputs found
Effects of creatine supplementation on power output during repeated bouts of supramaximal cycling
This study examined the effect of creatine supplementation on power output during repeated bouts of high intensity cycling.
[This is an excerpt from the abstract. For the complete abstract, please see the document.
Limits of small functors
For a small category K enriched over a suitable monoidal category V, the free
completion of K under colimits is the presheaf category [K*,V]. If K is large,
its free completion under colimits is the V-category PK of small presheaves on
K, where a presheaf is small if it is a left Kan extension of some presheaf
with small domain. We study the existence of limits and of monoidal closed
structures on PK.Comment: 17 page
Optimizing Compressed Air Storage for Energy Efficiency
Compressed air storage is an important, but often misunderstood, component of compressed air systems. This paper discusses methods to properly size compressed air storage in load-unload systems to avoid short cycling and reduce system energy use. First, key equations relating storage, pressure, and compressed air flow are derived using fundamental thermodynamic relations. Next, these relations are used to calculate the relation between volume of storage and cycle time in load-unload compressors. It is shown that cycle time is minimized when compressed air demand is 50% of compressor capacity. The effect of pressure drop between compressor system and storage on cycle time is discussed. These relations are used to develop guidelines for compressed air storage that minimize energy consumption. These methods are demonstrated in two case study examples
Ultra-narrow (sub-MHz) linewidth emission from discrete mode laser diodes
A class of laser which exhibits ultra-narrow sub MHz linewidth emission necessary for numerous applications in optical communications and sensors is described. The spectral performance of commercial discrete mode (DM) and distributed feedback (DFB) lasers is compared. The devices used in this work are asymmetrically coated ridge waveguide Fabry Perot lasers which incorporated etched slot features and emitting around lambda = 1.55 mum. The active region of the devices consisted of a strained compensated InAlGaAs MQW structure
Low sensitivity to optical feedback and optical injection of discrete mode lasers
In this paper, we demonstrate the low sensitivity to both external optical feedback and external optical injection of a new type of extremely low cost single-mode lasers, called "discrete mode" (DM) lasers. The DM lasers are obtained from ridge waveguide Fabry Perot (FP) lasers, in which the effective refractive index of the lasing mode has been perturbed. These lasers exhibit a low sensitivity to external optical feedback since the coherence collapse threshold is around 5 dB higher in comparison to a commercial DFB laser
Discrete mode lasers for applications in access networks
Fast development of the modern telecommunication networks such as fiber-to-the-home or radio-over-fiber systems require an inexpensive yet reliable optical transmitter for electro-optic conversion. Such devices should be able to generate stable, single moded optical signals suitable for athermal operation. Discrete Mode Lasers (DMLs) are able to fulfill all the above-mentioned requirements with the added benefit of low sensitivity to optical feedback. DMLs are essentially Fabry-Perot lasers in which the refractive index is modified by introducing perturbations along very small sections of the laser cavity. These modifications result in a single mode laser output with a very narrow linewidth (order of 400 kHz). In this paper, we demonstrate how a DML can outperform the commonly used/commercially available DFB lasers in terms of linewidth, sensitivity to optical feedback and transmission performance in the presence of feedback
Keeping it Simple: Simplified Frameworks for Long-Lived Particles at Neutrino Facilities
Modern-day accelerator neutrino facilities are excellent venues for searches
for new-physics particles. Many distinct new-physics models predict overlapping
signatures and phenomenology in these experiments. In this work, we advocate
for the adoption of simplified frameworks when studying these types of
new-physics signatures, which are characterized by a small number of primary
variables, including particle masses, lifetimes, and production and decay
modes/rates that most directly control signal event rates and kinematics. In
particular, taking the example of long-lived particles that decay inside a
neutrino detector as a test case, we study formulate and study simplified
frameworks in the context of light scalars/fermions produced in kaon decays
which then decay into final states containing an electron-positron pair. We
show that using these simplified frameworks can allow for individual
experimental analyses to be applicable to a wide variety of specific model
scenarios. As a side benefit, we demonstrate that using this approach can allow
for the T2K collaboration, by reinterpreting its search for Heavy Neutral
Leptons, to be capable of setting world-leading limits on the Higgs-Portal
Scalar model. Furthermore, we argue the simplified framework interpretation can
serve as a bridge to model identification in the hopeful detection of a
new-physics signal. As an illustration, we perform a first determination of the
likelihood that, in the presence of a new-physics signal in a detector like the
DUNE ND-GAr, multiple different new-physics hypotheses (such as the
Higgs-Portal Scalar and Heavy Neutral Lepton ones) can be disentangled. We
demonstrate that this model discrimination is favorable for some portions of
detectable new-physics parameter space but for others, it is more challenging.Comment: 22 pages, 10 figures. Updated to JHEP versio
Advantages of 3D time-of-flight range imaging cameras in machine vision applications
Machine vision using image processing of traditional intensity images is in wide spread use. In many situations environmental conditions or object colours or shades cannot be controlled, leading to difficulties in correctly processing the images and requiring complicated processing algorithms. Many of these complications can be avoided by using range image data, instead of intensity data. This is because range image data represents the physical properties of object location and shape, practically independently of object colour or shading. The advantages of range image processing are presented, along with three example applications that show how robust machine vision results can be obtained with relatively simple range image processing in real-time applications
Ecological values of Hamilton urban streams (North Island, New Zealand): constraints and opportunities for restoration
Urban streams globally are characterised by degraded habitat conditions and low aquatic biodiversity, but are increasingly becoming the focus of restoration activities. We investigated habitat quality, ecological function, and fish and macroinvertebrate community composition of gully streams in Hamilton City, New Zealand, and compared these with a selection of periurban sites surrounded by rural land. A similar complement of fish species was found at urban and periurban sites, including two threatened species, with only one introduced fish widespread (Gambusia affinis). Stream macroinvertebrate community metrics indicated low ecological condition at most urban and periurban sites, but highlighted the presence of one high value urban site with a fauna dominated by sensitive taxa. Light-trapping around seepages in city gullies revealed the presence of several caddisfly species normally associated with native forest, suggesting that seepage habitats can provide important refugia for some aquatic insects in urban environments. Qualitative measures of stream habitat were not significantly different between urban and periurban sites, but urban streams had significantly lower hydraulic function and higher biogeochemical function than periurban streams. These functional differences are thought to reflect, respectively, (1) the combined effects of channel modification and stormwater hydrology, and (2) the influence of riparian vegetation providing shade and enhancing habitat in streams. Significant relationships between some macroinvertebrate community metrics and riparian vegetation buffering and bank protection suggest that riparian enhancement may have beneficial ecological outcomes in some urban streams. Other actions that may contribute to urban stream restoration goals include an integrated catchment approach to resolving fish passage issues, active reintroduction of wood to streams to enhance cover and habitat heterogeneity, and seeding of depauperate streams with native migratory fish to help initiate natural recolonisation
- âŠ