How does volcanic outgassing differ on geological time scales between planets with and without plate tectonics?

<div>One of the main factors to assess the possible habitability of a rocky planet (either in or beyond our solar system) is its capability to maintain an atmosphere that allows for moderate temperatures at the surface and would allow water to occur in a liquid form, and that can help shield surface life from harmful radiation.</div> <div>The existence of an atmosphere depends on several factors - possible accretion from the nebula and catastrophic degassing from the crystallizing magma ocean during planet formation, later delivery of volatiles via comets, sinks of atmosphere gases to the surface or to space, and last, but definitely not least, volcanic release of volatiles from the mantle that where stored in the planet's interior during its formation stage.</div> <div>For planets of masses not too different from Earth, volcanic degassing plays a major role for the question if the planet could have an atmosphere. Lower-mass planets might not be able to keep an atmosphere but loose it entirely to space, and much more massive super-Earth planets will likely keep the primordial, catastrophically outgassed atmosphere during magma ocean crystallization, and may never be habitable at their surface due to a thick atmosphere rather comparable to Venus. The "Goldilocks zone" for potentially habitable rocky planets is therefore limited to a range from above Mars' mass to a few Earth masses. However, planets of a few Earth masses may not be able to efficiently outgas volcanic gases, if they are in a stagnant-lid regime. This may be different, though, for planets experiencing plate tectonics like Earth, where hot, molten material reaches the surface at plate boundaries and may therefore build up or replenish an atmosphere. The work presented here compares the efficiency of interior volatile depletion and degassing to the surface for rocky planets of different size and composition, either in the stagnant-lid or in the plate-tectonics regime.</div>

Multi-Camera Based Setup for Geometrical Measurement of Free-Falling Molten Glass Gob

High temperatures complicate the direct measurements needed for continuous characterization of the properties of molten materials such as glass. However, the assumption that geometrical changes when the molten material is in free-fall can be correlated with material characteristics such as viscosity opens the door to a highly accurate contactless method characterizing small dynamic changes. This paper proposes multi-camera setup to achieve accuracy close to the segmentation error associated with the resolution of the images. The experimental setup presented shows that the geometrical parameters can be characterized dynamically through the whole free-fall process at a frame rate of 600 frames per second. The results achieved show the proposed multi-camera setup is suitable for estimating the length of free-falling molten objects.

Influência da Densidade de Preenchimento e do Número de Perímetros nas Propriedades Mecânicas de Peças Fabricadas em PLA a Partir de Impressão 3D

<p>With the dissemination of the additive manufacturing by deposition of molten material, popularly known as 3D printing, studies on the mechanical properties of the pieces manufactured through this process are necessary to increase the understanding of their behaviors, as well as to know how to expand the application horizons of the technology in the manufacture of items that will<br />work under mechanical stresses. Therefore, the aim of this article is to analyze the influence of two printing parameters (number of perimeters and filling density) on the mechanical properties of specimens manufactured in PLA from 3D printing. For the study, the specimens made of PLA filament with a diameter of 1.75 mm, using the FDM technique and a 3D Cloner DH Plus model machine, were submitted to tensile test. From the analyzes carried out, it was possible to verify that the number of perimeters is more relevant with regard to the mechanical resistance to traction. The results were satisfactory and allow to trace interesting parallels with the data obtained in other studies used as references in present work.</p><p><br /><strong>Key words</strong>: PLA; 3D printing; number of perimeters; filling density; mechanical properties.</p><p>==================================================================</p><p>Com a disseminação da manufatura aditiva por deposição de material fundido, popularmente conhecida como impressão 3D, fazem-se necessários estudos a respeito das propriedades mecânicas das peças fabricadas por este processo a fim de aumentar a compreensão do comportamento destes objetos e expandir os horizontes de aplicação da tecnologia na fabricação de itens que irão trabalhar sob solicitações mecânicas. Portanto, o objetivo deste artigo é analisar a influência de dois parâmetros de impressão (número de perímetros e densidade de preenchimento) sobre as propriedades mecânicas de corpos de prova fabricados em PLA a partir da impressão 3D. Para o estudo, os corpos de prova foram confeccionados a partir do filamento de PLA com diâmetro de 1,75 mm, por meio da técnica FDM, utilizando uma máquina 3D Cloner, modelo DH Plus, e submetidos ao ensaio de tração. A partir das análises efetuadas, foi possível constatar que o parâmetro “número de perímetros” é mais relevante no que tange a resistência mecânica à tração. Os resultados foram satisfatórios e permitem traçar paralelos interessantes com dados obtidos em outros estudos utilizados como referência na elaboração deste artigo.</p><p><br /><strong>Palavras-chave</strong>: PLA; impressão 3D; número de perímetros; densidade de preenchimento; propriedades mecânicas</p>

Novel Study for Energy Recovery from the Cooling–Solidification Stage of Synthetic Slag Manufacturing: Estimation of the Potential Energy Recovery

Herein, a novel method for energy recovery from molten synthetic slags is analyzed. In this work, the potential energy that could be recovered from the production of synthetic slag is estimated by means of an integrated experimental–theoretical study. The energy to be recovered comes from the cooling–solidification stage of the synthetic slag manufacturing. Traditionally, the solidification stage has been carried out through quick cooling with water, which does not allow the energy recovery. In this paper, a novel cooling method based on metal spheres is presented, which allows the energy recovery from the molten slags. Two points present novelty in this work: (1) the method for measuring the metal spheres temperature (2) and the estimation of the energy that could be recovered from these systems in slag manufacturing. The results forecasted that the temperature achieved by the metal spheres was in the range of 295–410 °C in the center and 302–482 °C on the surface. Furthermore, we estimated that 325–550 kJ/kg of molten material could be recovered, of which 15% of the energy consumption is in the synthetic slag manufacturing process. Overall, the results obtained confirmed the potential of our proposal for energy recovery from the cooling–solidification stage of synthetic slag manufacturing.

Numerical Simulation of Liquid Jet Behavior in Shallow Pool by Interface Tracking Method

In the severe accident (SA) of nuclear reactors, fuel and components melt, and melted materials fall to a lower part of a reactor vessel. In the lower part of a reactor vessel, in some sections of the SAs, it is considered that there is a water pool. Then, the melted core materials fall into a water pool in the lower plenum as a jet. The molten material jet is broken up, and heat transfer between molten material and coolant may occur. This process is called a fuel-coolant interaction (FCI). FCI is one of the important phenomena to consider the coolability and distribution of core materials. In this study, the numerical simulation of jet breakup phenomena with a shallow pool was performed by using the developed method (TPFIT). We try to understand the hydrodynamic interaction under various, such as penetration, reach to the bottom, spread, accumulation of the molten material jet. Also, we evaluated a detailed jet spread behavior and examined the influence of lattice resolution and the contact angle. Furthermore, the diameters of atomized droplets were evaluated by using numerical simulation data.

Experimental Investigation of Behavior of Impinging Liquid Jet in a Shallow Pool by 3D-LIF

In some scenarios of severe accidents, the core materials melt and fall into a water pool in the lower plenum as a jet. The molten material jet is broken up, and heat transfer between molten material and coolant occurs. The aim of this study is to clarify the behavior of liquid jet falling into a shallow pool. In a previous study, it is clarified that, in a shallow pool, the jet spread radially after bottoming, and the atomization occurs with high flow velocity in a shallow pool. the detail of atomization and the spreading of the jet cannot be measured by the limitation of a 2D visualization method. In this study, a 3D-LIF method is used to obtain the detail 3D shape data of the jet. The 3D visualization of the jet is conducted. Using 3D shape data, the liquid film and the atomized droplet are measured. The initial jet velocity is selected as a parameter. As a result, following knowledge is obtained. The thickness of liquid film increases suddenly, and the radius of thin liquid flow increases with the increase of the initial jet velocity. The number of atomized droplets increases with the increase of the initial jet velocity. However, the size of the droplets are not influenced by the initial jet velocity.

Distortion and Mechanical Characteristics of Single-V and Single Bevel Welded Low Carbon Steel

Welding is a fabrication or sculptural process that joints the materials, usually metals or thermoplastics, by inducing fusion. It is as distinct process from lower temperature metal-joining techniques such as brazing and soldering, to high temperature welding process and this process keep the base metal from melted. In addition, to melt the base metal, a filler material is typically added to the joint to form a pool of molten material that cools at room temperature, forming a joint that is usually stronger than the base material. Pressure may also be used along with heat, or by itself, to produce a weldment. The current study presents the effects of distortion that occurred in single-V and single bevel welded mild steel. It also includes the macro and microstructure analysis, mechanical properties and also the consumable usage along the time needed to complete the bevel and welding process. As a result, single- V is way more safe and reliable to use to withhold large load compare to single bevel.In term of financial, single bevel way more ahead.

CHROMITE DEPOSITS OF PAKISTAN: A SHORT REVIEW

Chromite is an important source for the manufacturing of stainless steel, nichrome, paint, and chemicals industries and has wide industrial utilization. In Pakistan, the chromite deposits are mostly associated with the ophiolitic sequence resulting as an outpouring of molten material in the fractured zones of the Indian plate and the Neo-Tethys Ocean through the Cretaceous era. The discovery and documentation of chromite in Pakistan is traveling back to 1960s, but unfortunately, most of the reports are lacking authentication in reserve estimation and grading. If the modern and proper geophysical and geochemical analysis is performed to the reported area, then there are more bright chances of acquiring the more authenticate reservoir estimation, its distribution in the prospect zone and chemical composition per metric ton. The current article is an effort towards making a composite record of all the published/unpublished reports and articles regarding the chromite discovery, estimation, and extraction in Pakistan.