Experimental and numerical prediction of extrusion load at different lubricating conditions of aluminium 6063 alloy in backward cup extrusion

In the present research work using a backward cup extrusion (BCE) die profile, different lubricating conditions on aluminum alloy AA6063 have been experimentally and numerically investigated to predict the extrusion load. It was obvious that due to an increase in applications of the extrusion process, many researchers have worked on the extrusion process using different methods to achieve their aims. This experiment was conducted with three different lubricants namely: Castor oil, Palm Oil and tropical coconut oil; as well as without lubricants. Different lubricating conditions were employed of varying strain rates ranges from 1.5×10-3s-1, 2.0×10-3s-1, 2.5×10-3s-1, and 3.0×10-3s-1; Numerical analysis and simulation for dry and lubricated conditions during extrusion load were also performed using DEFORM 3D software. The results show that prediction extrusion load increases with increasing strain rates. The maximum extrusion load was found to be higher for extrusion without lubricants. In all cases of strain rate, palm oil showed a lower extrusion load compared to the other lubricants. Castor oil indicated the highest extrusion load when the experiment was carried out using lubrication. There was a consistent agreement between the result gotten from the experiment and simulation results of the extrusion load-strike curve.Peer reviewedFinal Published versio

Numerical Implementation of lepton-nucleus interactions and its effect on neutrino oscillation analysis

We discuss the implementation of the nuclear model based on realistic nuclear spectral functions in the GENIE neutrino interaction generator. Besides improving on the Fermi gas description of the nuclear ground state, our scheme involves a new prescription for $Q^2$ selection, meant to efficiently enforce energy momentum conservation. The results of our simulations, validated through comparison to electron scattering data, have been obtained for a variety of target nuclei, ranging from carbon to argon, and cover the kinematical region in which quasi elastic scattering is the dominant reaction mechanism. We also analyse the influence of the adopted nuclear model on the determination of neutrino oscillation parameters.Comment: 19 pages, 35 figures, version accepted by Phys. Rev.

Rapid degradation of mutant SLC25A46 by the ubiquitin-proteasome system results in MFN1/2-mediated hyperfusion of mitochondria.

SCL25A46 is a mitochondrial carrier protein that surprisingly localizes to the outer membrane and is distantly related to Ugo1. Here we show that a subset of SLC25A46 interacts with mitochondrial dynamics components and the MICOS complex. Decreased expression of SLC25A46 results in increased stability and oligomerization of MFN1 and MFN2 on mitochondria, promoting mitochondrial hyperfusion. A mutation at L341P causes rapid degradation of SLC25A46, which manifests as a rare disease, pontocerebellar hypoplasia. The E3 ubiquitin ligases MULAN and MARCH5 coordinate ubiquitylation of SLC25A46 L341P, leading to degradation by organized activities of P97 and the proteasome. Whereas outer mitochondrial membrane-associated degradation is typically associated with apoptosis or a specialized type of autophagy termed mitophagy, SLC25A46 degradation operates independently of activation of outer membrane stress pathways. Thus SLC25A46 is a new component in mitochondrial dynamics that serves as a regulator for MFN1/2 oligomerization. Moreover, SLC25A46 is selectively degraded from the outer membrane independently of mitophagy and apoptosis, providing a framework for mechanistic studies in the proteolysis of outer membrane proteins

Medium earth orbit and inclined geosynchronous orbit satellite control strategies optimization based on the function approximation method

The article proposes an optimization method based on the function approximation in control strategies design of medium earth orbit (MEO) and inclined geosynchronous orbit (IGSO) satellites. As an extension of the functional approximation method (FAM), this method is suitable to solve a single-variable or a multivariable optimization question with equality or inequality constraints. This ensures that the optimal control strategies for MEO and IGSO satellites to manoeuvre along the ideal control arc can be easily determined, and finally make satellites enter the designed orbits as soon as possible after satellites being launched under restrictions of the limited propellant and number of revolutions around the earth. In the current article, the basic FAM model is first introduced, and then the method applications and the simulation results are discussed in detail. Compared with the conventionally adopted exhaust search in the process of the optimal strategy design for the MEOand IGSO satellites, this method has the advantages of simplicity, less dependence on the initial parameter range, and requires much less computational effort

Investigating thermal performance of PCM plates for free cooling applications in South Africa

Abstract: Free cooling involves using a thermal energy storage medium such as a phase change material (PCM) in order to store the ambient “cold” during the night when ambient air temperatures are lower compared to the indoor building temperatures and release this stored “cold” by using a heat transfer fluid (i.e. air) into the building during the day when higher ambient temperatures are experienced especially during the summer months. This paper assesses the free cooling potential in South Africa by using a set of Rubitherm RT25HC PCM plates. The performance of these PCM plates is assessed by benchmarking the ambient air cooled by the PCM plates during the day against the defined thermal comfort temperatures requirements. The influence of varying the air flow rate on the availability of thermal comfort temperatures at the PCM rig outlet is also studied. The results clearly show the potential of using PCM’s as a means of cooling higher ambient air temperature which is experienced in hot summer months to within thermal comfort temperatures for human occupancy in a building

Enantioselective Organocatalytic Intramolecular Diels−Alder Reactions. The Asymmetric Synthesis of Solanapyrone D

The first direct enantioselective organocatalytic intramolecular Diels−Alder reaction has been accomplished. The use of iminium catalysis has provided a new catalytic strategy for the enantioselective [4 + 2] cycloisomerization of a wide variety of tethered diene-enal systems. The use of imidazolidinones 1 and 2 as the asymmetric catalysts has been found to mediate the enantioselective construction of [4.4.0] and [4.3.0] ring systems. Application of this methodology to the highly efficient asymmetric synthesis of the marine metabolite solanpyrone D has also been accomplished. A diverse spectrum of aldehyde substrates can also be accommodated in this new organocatalytic transformation. Importantly, this technology has been utilized to execute the first enantioselective, catalytic Type II IMDA reaction

Positive-P phase space method simulation in superradiant emission from a cascade atomic ensemble

The superradiant emission properties from an atomic ensemble with cascade level configuration is numerically simulated. The correlated spontaneous emissions (signal then idler fields) are purely stochastic processes which are initiated by quantum fluctuations. We utilize the positive-P phase space method to investigate the dynamics of the atoms and counter-propagating emissions. The light field intensities are calculated, and the signal-idler correlation function is studied for different optical depths of the atomic ensemble. Shorter correlation time scale for a denser atomic ensemble implies a broader spectral window needed to store or retrieve the idler pulse.Comment: To be published in Phys. Rev.