Could past changes in El Niño inform its future?

<p>Paleoclimate records show pronounced changes in the El Niño/Southern Oscillation (ENSO) phenomenon over past climatic intervals, but the application of these results to understand future changes is not straightforward. To address this issue we propose the following mechanism controlling ENSO variability across altered climate states. Numerical simulations show that extreme El Niño – the warm phase of ENSO – could become more frequent in climatic states with a shallower ocean mixed layer, as predicted for the future, and extremely infrequent under climatic states with a deeper mixed layer, typical of glacial intervals. Wind fluctuations involved in the onset of El Niño transfer momentum more efficiently over a thinner ocean mixed layer, thus favoring stronger ocean currents and faster warming during the event. The robustness of this momentum coupling mechanism across climatic states, together with the evidence that ENSO was weaker under glacial conditions, increases our confidence in model predictions of more frequent extreme El Niño under greenhouse warming.</p>

Polyhydroxybutyrate Production from Natural Gas in A Bubble Column Bioreactor: Simulation Using COMSOL

In this study, the simulation of microorganism ability for the production of poly-β-hydroxybutyrate (PHB) from natural gas (as a carbon source) was carried out. Based on the Taguchi algorithm, the optimum situations for PHB production from natural gas in the columnar bubble reactor with 30 cm length and 1.5 cm diameter at a temperature of 32 °C was evaluated. So, the volume ratio of air to methane of 50:50 was calculated. The simulation was carried out by COMSOL software with two-dimensional symmetric mode. Mass transfer, momentum, density-time, and density-place were investigated. The maximum production of biomass concentration reached was 1.63 g/L, which shows a 10% difference in contrast to the number of experimental results. Furthermore, the consequence of inlet gas rate on concentration and gas hold up was investigated Andres the simulation results were confirmed to experimental results with less than 20% error.

Non-Hydrostatic Modeling of Waves Generated by Landslides with Different Mobility

Tsunamis are generated when landslides transfer momentum to water, and these waves are major hazards in the mountainous coastal areas of lakes, reservoir, and fjords. In this study, the influence of slide mobility on wave generation is investigated using new: (i) experimental observations; (ii) theoretical relationships; and (iii) non-hydrostatic numerical predictions of the water surface and flow velocity evolution. This is accomplished by comparing landslides with low and high mobility and computing the momentum flux from landslides to water based on data collected in laboratory experiments. These slides have different materials, different impact velocities, different submarine runout distances, and generate very different waves. The waves evolve differently along the length of the waves’ flume, and the experimental results are in close agreement with high-resolution phase-resolving simulations. In this short communication, we describe new research on landslide generated waves conducted at Queen’s University, Canada, and presented at Coastlab18 in Santander, Spain.

High spin resonances produced in π+π−π− and π−π0π0 systems at VES setup

A study of high spin resonances produced in π+π−π− and π−π0π0 systems with 29 GeV/c π− beam on Be target is presented. About 87 million events for the first one and 32 million events for the second one are collected with VES setup in a wide range of transfer momentum squared 0 < |t′| < 1 GeV2/c2. For both reactions this is the largest statistics in the world. The data are analysed using the PWA formalism of full rank density matrix and rank 1 density matrix. The a3(1875) and a4(2040) meson parameters are given and their production mechanism is discussed.

A Review of Dry Particulate Lubrication: Powder and Granular Materials

Research efforts related to dry particulates in sliding contacts are reviewed. In the tribology community, there are primarily two types of dry particulate lubricants that are studied—granular and powder. Granular lubricants usually refer to dry, cohesionless, hard particles that transfer momentum and accommodate surface velocity differences through shearing and rolling at low shear rates, and collisions at high shear rates. Powder lubricants refer to dry, cohesive, soft particles that accommodate surface velocity differences mostly by adhering to surfaces and shearing in the bulk medium, in a manner similar to hydrodynamic fluids. Spanning the past five decades, this review proposes a classification system for the scientific works in the dry particulate tribology literature in terms of theory, experiments, and numerical simulations. It also suggests that these works can be further categorized based on their tribosystem geometry—annular, parallel, and converging.