Experimental and Numerical Model Investigations of the Underwater Towing of a Subsea Module

In underwater towing operations, the drag force and vertical offset angle of towropes are important considerations when choosing and setting up towing equipment. The aim of this paper is to study the variation in drag force, vertical offset angle, resistance, and attitude for towing operations with a view to optimizing these operations. An underwater experiment was conducted using a 1:8 scale physical model of a subsea module. A comprehensive series of viscous Computational Fluid Dynamics (CFD) simulations were carried out based on Reynolds-averaged Navier–Stokes equations for uniform velocity towing. The results of the simulation were compared with experimental data and showed good agreement. Numerical results of the vorticity field and streamlines at the towing speeds were presented to analyze the distribution of vortexes and flow patterns. The resistance components were analyzed based on the numerical result. It was found that the lateral direction was a better direction for towing operations because of the smaller drag force, resistance, and offset angle. Similar patterns and locations of streamlines and vortexes were present in both the longitudinal and lateral directions, the total resistance coefficient decreases at a Reynolds number greater than that of a cylinder

Study on Single Event Upsets in a 28 nm Technology Static Random Access Memory Device Based on Micro-Beam Irradiation

As an important spaceborne electronic device, the static random access memory (SRAM) device is inevitably affected by the radiation of high-energy particles in space during its space mission. To reveal the single event effect (SEE) mechanism of 28 nm technology SRAM caused by high-energy particles, the sensitive area positioning of single event upsets (SEUs) and the distribution characteristics of multi-cell upsets (MCUs) were studied based on the pinhole heavy ion micro-beam facility. The results show that the actual range of SEUs caused by micro-beam irradiation is 4.8 μm × 7.8 μm. By moving the device platform in small steps (1 μm each step), a one-dimensional positioning method for locating the sensitive area of SEUs was established, which can reduce the dependence of localization accuracy on beam spot size, and the positioning accuracy can be improved to 1 μm. The MCU test indicates that the upset pattern is closely related to the spacing of sensitive areas within adjacent SRAM cells, and the probability of MCUs is reduced by well contacts and bit interleaving

Study on Single Event Upsets in a 28 nm Technology Static Random Access Memory Device Based on Micro-Beam Irradiation

As an important spaceborne electronic device, the static random access memory (SRAM) device is inevitably affected by the radiation of high-energy particles in space during its space mission. To reveal the single event effect (SEE) mechanism of 28 nm technology SRAM caused by high-energy particles, the sensitive area positioning of single event upsets (SEUs) and the distribution characteristics of multi-cell upsets (MCUs) were studied based on the pinhole heavy ion micro-beam facility. The results show that the actual range of SEUs caused by micro-beam irradiation is 4.8 μm × 7.8 μm. By moving the device platform in small steps (1 μm each step), a one-dimensional positioning method for locating the sensitive area of SEUs was established, which can reduce the dependence of localization accuracy on beam spot size, and the positioning accuracy can be improved to 1 μm. The MCU test indicates that the upset pattern is closely related to the spacing of sensitive areas within adjacent SRAM cells, and the probability of MCUs is reduced by well contacts and bit interleaving

Controlled Epitaxial Growth and Atomically Sharp Interface of Graphene/Ferromagnetic Heterostructure via Ambient Pressure Chemical Vapor Deposition

The strong spin filtering effect can be produced by C-Ni atomic orbital hybridization in lattice-matched graphene/Ni (111) heterostructures, which provides an ideal platform to improve the tunnel magnetoresistance (TMR) of magnetic tunnel junctions (MTJs). However, large-area, high-quality graphene/ferromagnetic epitaxial interfaces are mainly limited by the single-crystal size of the Ni (111) substrate and well-oriented graphene domains. In this work, based on the preparation of a 2-inch single-crystal Ni (111) film on an Al2O3 (0001) wafer, we successfully achieve the production of a full-coverage, high-quality graphene monolayer on a Ni (111) substrate with an atomically sharp interface via ambient pressure chemical vapor deposition (APCVD). The high crystallinity and strong coupling of the well-oriented epitaxial graphene/Ni (111) interface are systematically investigated and carefully demonstrated. Through the analysis of the growth model, it is shown that the oriented growth induced by the Ni (111) crystal, the optimized graphene nucleation and the subsurface carbon density jointly contribute to the resulting high-quality graphene/Ni (111) heterostructure. Our work provides a convenient approach for the controllable fabrication of a large-area homogeneous graphene/ferromagnetic interface, which would benefit interface engineering of graphene-based MTJs and future chip-level 2D spintronic applications

Search for intermediate-mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo

International audienceIntermediate-mass black holes (IMBHs) span the approximate mass range 100−105 M⊙, between black holes (BHs) that formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass ∼150 M⊙ providing direct evidence of IMBH formation. Here, we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modeled (matched filter) and model-independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass 200 M⊙ and effective aligned spin 0.8 at 0.056 Gpc−3 yr−1 (90% confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to 0.08 Gpc−3 yr−1.Key words: gravitational waves / stars: black holes / black hole physicsCorresponding author: W. Del Pozzo, e-mail: [email protected]† Deceased, August 2020