Crystallization Mechanisms and Rates of Cyclopentane Hydrates Formation in Brine

Clathrate hydrates most often grow at the interface between liquid water and another fluid phase (hydrocarbon) acting as a provider for the hydrate guest molecules, and some transfer through this shell is required for the hydrate growth to proceed, thus self‐limiting the reaction rate. An optical microscope and a horizontal reaction cell are utilized to capture the shell growth phenomenology and to estimate the hydrate layer growth rates from sequential pictures. Cyclopentane (CP) is chosen as the hydrate‐forming molecule to obtain hydrates at low pressure. Experimental hydrate layer growth rates are provided for the CP+brine system, using various combinations of salts and degrees of subcooling.     

A new tangible user interface for machine learning document review

This paper describes a tool for assisting lawyers and paralegal teams during document review in eDiscovery. The tool combines a machine learning technology (CategoriX) and advanced multi-touch interface capable of not only addressing the usual cost, time and accuracy issues in document review, but also of facilitating the work of the review teams by capitalizing on the intelligence of the reviewers and enabling collaborative work.     

5G meets satellite: Non-terrestrial network architecture and 3GPP

With 3GPP Release-17, global 5G standards now support non-terrestrial mobile networks comprising radio access network, terminals, and core network. This enables multi-vendor interoperability as well as interoperability with 3GPP-compliant 5G systems. This paper describes the key features enabling the NG-RAN architecture defined for 5G to support non-terrestrial networks. Starting from a general overview of NG-RAN and of the new paradigms of NTN, we introduce the NTN functionality in NG-RAN specifications with respect to feeder link switchover, cell handling, terminal registration, and OAM aspects. We also discuss different scenarios combining satellite access with 3GPP-defined core networks. We also describe some further enhancements expected to be seen in the next 3GPP release (Rel-18). We believe current and upcoming 3GPP work for NTN represents a solid basis on which 5G satellite networks can be built in the upcoming future.     

Performance analyses of VHTR plants with direct and indirect closed Brayton cycles and different working fluids

This paper investigated the performance of Very High Temperature Reactor (VHTR) power plants with helium working fluid and direct and indirect Closed Brayton Cycles (CBCs), and with binary mixture working fluids of He–Xe and He–N₂ (molecular weight of 15 g/mole) and indirect CBCs. Also investigated are the effects of using low- and high-pressure compressors with intercooling, versus a single compressor, using bleed cooling the reactor pressure vessel in direct CBC helium plants, and varying the reactor exit temperature from 700 °C to 950 °C on the plant thermal efficiency, cycle pressure ratio and the size of and number of stages in the turbine and compressor. Analyses are performed for a shaft rotation speed of 3000 rpm, reactor thermal power of 600 MW and a temperature pinch of 50 °C in the intermediate heat exchanger (IHX) for the indirect CBCs.     

Ionic conductivity of amorphous mNaFnMF3 thin films (M=Al,Cr)

Evaporated 0.5 to 0.7 μm thick thin films of mNaFnAlF₃ or mNafnCrF₃ were prepared in a 1 mPa vacuum on glass substrates kept at room temperature. Chemical analysis and AC conductivity measurement revealed that in each case studied, a high ionic conductivity plateau existed for the composition range $\text{0.1 <}\text{n}\text{(m+n)}\text{< 0.4}$. The maximum conductivities at room temperature were σ = 1 × 10^?6 S/mm for NaFAlF₃ and σ = 2 × 10^?5 S/m for NaFCrF₃. Those high conductivities were discussed in terms of arrangement of MF₆ octahedra.     

An investigation on thermal, metallurgical and mechanical states in weld cracking of Inconel 738LC superalloy

The influence of various conditions of Inconel 738 superalloy welding or deposition welding has been studied in order to shed light on the coupling between thermal, metallurgical and mechanical states in the heat affected zone (HAZ) in which cracking may occur particularly during welding and post-weld heat treatment. Predominant crack controlling factors have been highlighted thanks to different pre-weld and post-weld heat treatments, in addition to various welding rates and pre-heating prior to welding. These factors are mainly the material ductility related to the morphology and volume fraction of intermetallic precipitates and thermally induced residual stress. It has appeared that reducing thermally induced residual stress could be more effective for preventing cracking than controlling the material ductility in the related zones thanks to adjustment of pre-weld and post-weld heat treatments. With the objective of cracking remediation, welding on preheated parts leads to lower weld power, to reduce significantly thermal gradients, decreases thermally induced stress and impedes cracks formation despite some localized and temporary decrease in alloy ductility.     

Caractérisation et résultats de fiabilité de transistors à haute mobilité électronique (HEMT)

The telecommunication systems require introduction of high performance devices especially for microwave applications. The emergence of molecular beam epitaxy as a growth technique allows the fabrication of heterostructure-based performing devices. Thus, this communication will focus on the reliability of technologies used for the development of field effect transistor using heterostructures and called HEMT (high electron mobility transistor).     

Thoughts about drying shrinkage: Scale effects and modelling

In this article, we propose a theoretical approach based on the mechanics of porous media that can be used to determine, simply and rigorously (some decoupling assumptions are proposed and defended), the expression for the drying shrinkage of a concrete element subjected to drying. We show that the expression for this drying shrinkage reveals a double nonlinearity with respect to relative humidity, in the form φ¹ln(h), where φ¹ is the porosity occupied by the liquid phase and h is the relative humidity. In light of this model, we analyze the two hypotheses, both classical and yet different, that, as an initial approximation, treat drying shrinkage as being proportional to the change of relative humidity, Δh, or to the change of water content, ΔC, in the material. We then establish, within a general framework, the well-known scale effect on the water content versus the size of a test specimen of any shape (i.e. not just cylindrical or spherical). From this result, we can identify the scale effects that follow—both on the weight loss and on the drying shrinkage and drying-related stresses. We show that the expressions proposed to account for these scale effects remain valid for different constitutive laws of concrete, provided that time is a factor only through the diffusion of water in the concrete. This therefore rules out,de facto, all laws of the viscoelastic, viscoplastic types etc., where time appears as such in the expression of the law of mechanical behaviour. Finally, for three simple constitutive laws—perfectly elastic, brittle elastic, and perfectly plastic—we establish the expression for the drying shrinkage of a drying specimen.