Hot Loading Research Articles

Evaluating the efficiency of metallized siderite concentrate electric melting

The Bakal siderites belong to poor, hard-to-enrich carbonate iron ores. The low content of phosphorus and non-ferrous metals makes siderites a valuable raw material for obtaining highly metallized concentrate suitable for use in steelmaking processes. Reduction of siderites in a rotating furnace at 1300 – 1350 °C followed by magnetic separation of waste rock allows to obtain a concentrate with metallization degree over 90 % and a content of waste rock of about 5 % suitable for steelmaking as raw materials. The purpose of this work is to evaluate the efficiency of the process aimed at obtaining metal from siderite ore including obtaining of highly metallized siderite concentrate in a recovery furnace, as well as its hot loading into ore-thermal furnace and melting process itself. To do this, the electric melting was calculated in the electric ore melting furnace providing for determination of a large number of parameters including the electricity consumption required for melting. As raw materials we used a highly metallized siderite concentrate (φmet = 92.3 %) containing 35 % of waste rock and, for comparison, a briquetted metallized siderite concentrate obtained from a lump concentrate in which a significant amount of waste rock was removed by wet magnetic separation. The results analysis shows that increase in concentrate temperatures from 25 to 1000 °C decreases specific energy consumption and at the same time increases the furnace productivity to values comparable to the parameters of melting briquetted concentrate. This confirms the efficiency of the developed process. To reduce the melting point of high-magnesium slag, it is proposed to use colemanite as flux.

Grain size and orientation affected deformation inhomogeneity and local damage of hot-deformed Al-Zn-Mg alloy

The forming defects at elevated temperature caused by the microstructural evolution such as grain size, crystal orientations are the critical issue that induced deformation inhomogeneity and local damage which severely limits the application of Al-Zn-Mg alloys in thin-walled structure manufacturing. In this study, the hot deformation behavior and microstructural evolution were investigated via hot stretching tests, electron backscatter diffraction (EBSD) and the transmission electron microscopy (TEM) characterization. Then, an integrated multiscale constitutive model coupled dislocation density based crystal plasticity (CP) model and phase field method (PFM) was established through the reconstructed configuration of deformation gradient emphasized on a damaged part. The coupled CP-PFM model was numerically implemented into Düsseldorf Advanced Material Simulation Kit (DAMASK) software. Subsequently, a set of virtual polycrystalline RVE models assigned with different average grain sizes and two types of RVE models with realistic crystal orientations were constructed from EBSD data. The experimental and simulation results of the Al-Zn-Mg alloy under hot tensile loading showed that the grain size refinement leads to the increase of grain boundary density, which leads to the rapid increase of dislocation density, uniform damage distribution and better work hardening ability. In addition, the coordination of the activation of different slip systems between adjacent grains will lead to the uneven distribution of dislocation density and local damage.

Investigations of hybrid infill pattern in additive manufactured tablets: A novel approach towards tunable drug release.

The significance of 3D printing has risen exponentially in biomedical and pharmaceutical applications. Its potential in the field of fabricating drug delivery systems, by virtue of processing biocompatible polymers, has been very lucrative. This work aims to tap the interstitial drug delivery kinetics that are often inaccessible through machine-specific infill patterns in additive manufactured tablets fabricated using PVA biopolymer as an excipient. In this regard, a myo-inositol containing tablet has been printed using Fused Deposition Modeling preceded by Hot Melt Extrusion drug loading route. Two machine-specific infill patterns were taken, namely straight and grid. Later, these two distinct patterns were juxtaposed to obtain novel hybrid infill patterns in the tablets. Then, these tablets and their filament were subjected to various thermal, mechanical, imaging and pharmaceutical characterization tests to assess the feasibility of the research attempt. Finally, dissolution tests were conducted to evaluate their dissolution behavior over a time period. The characterization tests proved the scientific viability of this attempt along with amorphous existence of drug in the polymeric filament. The dissolution results showed favorable drug release by achieving interstitial dissolution timings with surface area/volume (SA/V) ratio being found to be the principal factor.

A Distributed Streaming Computing Model Management System

IoT big data has many dimensions, many business types and many customized requirements, and each business needs to be implemented using a stream computing model with a wide variety of stream computing models. This paper proposes a management method for streaming computing models, which can dynamically manage streaming computing models and achieve hot loading of streaming computing models. This makes it easier to manage computational models in a streaming computing cluster.

BISON validation of FeCrAl cladding mechanical failure during simulated reactivity-initiated accident conditions

A reactivity-initiated accident (RIA) is a postulated design basis accident in light water reactors (LWRs) in which a rapid reactivity insertion induces a fission rate increase and a fuel pellet temperature rise. During RIA, the fuel pellet thermally expands and may cause pellet-cladding mechanical interaction (PCMI). Separate effects PCMI tests were performed on C26M FeCrAl cladding tube samples, introducing biaxial stress via a well understood modified burst test (MBT) system. A high-speed camera in the MBT system captured the projections, covering a 360° view of the cladding deformation and enabling a digital image correlation (DIC) method to quantify the surface strains with high fidelity. Representative hot zero-power RIA mechanical loading conditions were applied to the sample, and the test duration ranged from 20 to 500 ms at an average temperature of 573 K. BISON finite element–based fuel performance code modeling was performed against the high-fidelity DIC data produced from the MBTs. Validation calculations were conducted with 2D models and systematically compared with test data of the burst time, burst pressure, burst hoop strains, and hoop strain rates. Based on the behaviors from the separate effects test, BISON calculations satisfactorily predicted the cladding deformation behaviors. Sensitivity analysis was conducted to identify highly influential mechanical properties responsible for the cladding failure behavior during the MBT experiments. The results highlight the significance of the cladding's mechanical strength in governing cladding strain, followed by the significance of the mechanical interactions between the pellet and the cladding.

PH-responsive release system of topiramate transported on silica nanoparticles by melting method

Incorporating drugs into silica matrices by the melting method can be applied to obtain drug delivery systems because they are governed by electrostatic type interactions, hydrogen bonding and hydrophilic-hydrophobic interactions between the drug and the silica surface. the melting method is an environmentally correct tool since it is free of organic solvent, low cost and with easy execution for the incorporation of drugs in silicas. Drugs delivery systems are very important for improving the treatment of chronic diseases. Topiramate (TPM) is a potent antiepileptic used in high daily doses as it has low bioavailability. In this context, silica nanoparticles (NPS) were used as an inorganic matrix for TPM transport in (in vitro) release studies. The TPM was incorporated into the NPS by hot melt loading employing a new carrier preparation methodology (NPS/TPM) using a thermobalance (by Thermogravimetry-TG) with high temperature control system. The release study using dissolution media simulating gastrointestinal at pH 1.2 (stomach) and 7.4 (intestine), showed that NPS release TPM in a prolonged and pH-responsive manner. The drug was released at intestinal pH ensuring greater absorption, allowing fewer daily doses and less adverse effects. The kinetic study demonstrated the best fit to the zero-order model proving the pH-responsive profile of the developed system.

Mechanical and Thermal Stress Behavior of a Conservative Proposed Veneer Preparation Design for Restoring Misaligned Anterior Teeth: A 3D Finite Element Analysis

The objective of this study was to evaluate the biomechanical and thermal behavior of a proposed preparation design as a conservative treatment option that aims to preserve both gingival and tooth health structures through a comparative finite element analysis with non-preparation and conventional designs. 3D solid models of laminate veneers with different preparation designs were obtained using cone-beam computed tomography (CBCT) scanning of the maxillary incisor. A 100-Newton load was applied with angulations of 60° and 125° to the longitudinal axis of the tooth to determine the stresses during mastication. In addition, transient thermal analysis was performed to compare the temperature and thermal distribution of the restored tooth models when subjected to thermal loads of 5 °C and 55 °C. Teeth prepared with the proposed design showed lower stress distributions and a repairable failure mode, followed by the non-preparation design, while teeth prepared with the conventional design showed the highest stress concentrations. Furthermore, cold thermal loading yielded larger thermal stress distributions than hot thermal loading, independent of the preparation type, and the effect of temperature changes were within the critical limit near the pulp and dentin regions. Thus, the preparation design geometry affects the long-term success of laminate restoration, and the proposed design yields more uniform and appropriate stress distributions than the other techniques.

Comparing Hot and Cold Loading in an Integrated Biomass Recovery Operation

The balance of production activities at the landing is pivotal to the success of any forest harvesting operation and has a direct impact on the cost and efficiency of the enterprise. The primary objective of this study was to understand the operational characteristics of the loader in a hot operation (handling both sawlog and biomass components concurrently) and cold operation (handling biomass and sawlogs separately) for harvesting sawlogs and biomass. Systematic work sampling techniques were employed to obtain “snapshots” of the loader activities for a cable logging operation, including the interaction of the loader with other operational phases and delay time for both hot and cold configurations. The results show that for hot loading at the landing, the yarder was the most utilized machine (85%), and was the bottleneck of the operation, followed by the loader (70%). In the hot loading configuration, 39% of operational delay during truck loading was caused by the loader and was predominantly due to movement of the loader within or between the landings. This was followed by the yarder (19%, due to rigging activities) and the chaser (15%, to maintain the crews’ safety). In the cold loading configuration, delays due to the unavailability of roll-off bins constituted up to 77% of the operational delay. This suggests that the number of bins and trucks hauling biomass has a crucial role in the overall efficiency of the biomass harvesting system, and should be well balanced with loading capacity. Additionally, the choice of hot or cold biomass loading operations is highly dependent on the site and operating conditions.

Simple Yet Powerful: Hot Galactic Outflows Driven by Supernovae

Abstract Supernovae (SNe) drive multiphase galactic outflows, impacting galaxy formation; however, cosmological simulations mostly use ad hoc feedback models for outflows, making outflow-related predictions from first principles problematic. Recent small-box simulations resolve individual SNe remnants in the interstellar medium (ISM), naturally driving outflows and permitting a determination of the wind loading factors of energy η E , mass , and metals . In this Letter, we compile small-box results, and find consensus that the hot outflows are much more powerful than the cool outflows: (i) hot outflows generally dominate the energy flux, and (ii) their specific energy e s,h is 10–1000 times higher than cool outflows. Moreover, the properties of hot outflows are remarkably simple: is almost invariant over four orders of magnitude of star formation surface density. Also, we find tentatively that 0.5. If corroborated by more simulation data, these correlations reduce the three hot phase loading factors into one. Finally, this one parameter is closely related to whether the ISM has a “breakout” condition. The narrow range of indicates that hot outflows cannot escape dark matter halos with log . This mass is also where the galaxy mass–metallicity relation reaches its plateau, implying a deep connection between hot outflows and galaxy formation. We argue that hot outflows should be included explicitly in cosmological simulations and (semi-)analytic modeling of galaxy formation.

Hot Loading Reduces Time to Intervention for ST-segment Elevation Myocardial Infarction Patients Being Transferred by Helicopter

ObjectiveThe aim of this study was to quantify the effect of helicopter hot loading on the time to percutaneous intervention (time-to-PCI) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing interhospital transfer. MethodsWe performed a retrospective cohort study using data from 2009 to 2014, looking at all patients who had an STEMI, were transferred from a single non-PCI hospital by helicopter emergency medical services, and who received PCI intervention at the PCI-capable hospital. Differences in loading method, flight details, and patient demographics were analyzed to measure the effectiveness of the intervention. ResultsDuring the 5-year study period, 134 STEMI patients were transferred. Sixty-four were hot loaded (47.7%), and 70 were cold loaded. Patients who were hot loaded had a median reduction in interhospital transfer and time-to-PCI of 22.3 minutes from 91.0 minutes (interquartile range, 65-117 minutes) by cold load to 69.5 minutes (interquartile range, 47.5-91.5 minutes) by hot load. There was no increase in reported safety-related events during the hot load process. The median length of hospital stay was equivalent for both groups at 3 days. ConclusionsThis protocol of helicopter hot loading STEMI patients presenting to a non-PCI hospital significantly reduced the median time of interhospital transfer and time-to-PCI without an increase in reported safety events.

Heating Regime and Thermostatic Control of Slabs During Hot Loading

A heating regime is proposed for steel slabs in a heating furnace during slab loading in a hot condition with which the process of slab soaking is replaced by a thermostat process. In this case overall contact duration of a slab surface with a furnace oxidizing atmosphere is reduced, scale formation decreases, and good uniformity is provided for the slab temperature field before rolling. On the basis of calculating the slab temperature field in a furnace the efficiency is demonstrated of the proposed heating and thermostat treatment compared with a classical slab heating and soaking regime.

Thermal-stress analysis of ceramic laminate veneer restorations with different incisal preparations using micro-computed tomography-based 3D finite element models

Main objective of this study is to investigate the thermal behavior of ceramic laminate veneer restorations of the maxillary central incisor with different incisal preparations such as butt joint and palatinal chamfer using finite element method. In addition, it is also aimed to understand the effect of different thermal loads which simulates hot and cold liquid imbibing in the mouth. Three-dimensional solid models of the sound tooth and prepared veneer restorations were obtained using micro-computed tomography images. Each ceramic veneer restoration was made up of ceramic, luting resin cement and adhesive layer which were generated based on the scanned images using computer-aided design software. Our solid model also included the remaining dental tissues such as periodontal ligament and surrounding cortical and spongy bones. Time-dependent linear thermal analyses were carried out to compare temperature changes and stress distributions of the sound and restored tooth models. The liquid is firstly in contact with the crown area where the maximum stresses were obtained. For the restorations, stresses on palatinal surfaces were found larger than buccal surfaces. Through interior tissues, the effect of thermal load diminished and smaller stress distributions were obtained near pulp and root-dentin regions. We found that the palatinal chamfer restoration presents comparatively larger stresses than the butt joint preparation. In addition, cold thermal loading showed larger temperature changes and stress distributions than those of hot thermal loading independent from the restoration technique.

Note: Contamination-free loading of lithium metal into a nozzle source.

This note describes a system for transferring a load of high purity lithium metal into a molecular or cluster beam source. A hot loading vessel is thoroughly baked out while empty and overpressured with argon. A clean Li rod is then dropped in through a long narrow tube. The thoroughly degassed interior of the vessel and the rapid melting of the inserted rod facilitate contamination-free transfer of the highly reactive liquid metal into the source oven.

Effect of densification rate on consolidation and properties of Al7075–B4C composite powder

Hot quasi-static pressing and dynamic compaction of Al7075–B4C composite powder are studied in this work. Micron sized Al7075 and B4C particles were milled to obtain uniform dispersion of B4C reinforcing phase. Samples with relative densities up to 97.5, 99 and 100% were fabricated using gas gun, drop hammer and hot quasi-statically compactions respectively. The results showed that the increase of B4C content improved the hardness of the compacts but did not improve the compressive strength in the samples compacted by the gas gun. However, the ductility of the samples was reduced significantly. The samples compacted using the drop hammer and under hot quasi-static loading experienced ∼25 and 11% enhancement in the compressive strength respectively. The investigation indicated that the dynamic compaction using the gas gun was more successful if it is performed after quasi-static pre-compaction and under warm compaction process. It was concluded that the quasi-static pressing is the best fabrication technique to achieve the highest density, microhardness and strength.

Local heating-aided hot blanking of quenched ultra-high-strength steel BR1500HS

Hot stamping and successive quenching can significantly improve the strength of the hot-stamped part to above 1.5 GPa and has been widely used in automobile manufacturing. However, ultra-high strength brings high difficulty in cold blanking of such hot-stamped part: low tool life and low surface quality of the sheared edge. Local heating-aided hot blanking of quenched ultra-high-strength steel (UHSS) is proposed in order to reduce the blanking loading and thus improve the tool life. In this method, conduction heating technology is employed to locally heat the shear zone of the blank prior to blanking. The surface quality of the sheared edge is investigated under different process parameters by experiments and simulations. Cooling methods used in obtaining the quenched blank and heating temperature (HT) play an important role in conditioning the surface quality of the sheared edge. Microstructure of the shear zone for different cooling methods and heating temperatures as well as its effect on the surface quality of the sheared edge and the mechanical properties of material in the vicinity of sheared edge are studied by experiments and simulations. A finite element (FE)-coupled thermo-mechanical model is developed to model hot blanking process. Good agreement between simulation and experimental results are achieved. Relationships among blanking force, heating temperature, and tool clearance (TC) are determined. Both experiment and simulation results demonstrate that for heating temperature at 800 °C, hot blanking loading decreases sharply and relative burnish height is significantly increased compared with the case of heating temperature at 400 °C.

Application the mechanism-based strain gradient plasticity theory to model the hot deformation behavior of functionally graded steels

Functionally graded steels (FGSs) are a family of functionally graded materials (FGMs) consisting of ferrite (<TEX>${\alpha}$</TEX>), austenite (<TEX>${\gamma}$</TEX>), bainite (<TEX>${\beta}$</TEX>) and martensite (M) phases placed on each other in different configurations and produced via electroslag remelting (ESR). In this research, the flow stress of dual layer austenitic-martensitic functionally graded steels under hot deformation loading has been modeled considering the constitutive equations which describe the continuous effect of temperature and strain rate on the flow stress. The mechanism-based strain gradient plasticity theory is used here to determine the position of each layer considering the relationship between the hardness of the layer and the composite dislocation density profile. Then, the released energy of each layer under a specified loading condition (temperature and strain rate) is related to the dislocation density utilizing the mechanism-based strain gradient plasticity theory. The flow stress of the considered FGS is obtained by using the appropriate coefficients in the constitutive equations of each layer. Finally, the theoretical model is compared with the experimental results measured in the temperature range <TEX>$1000-1200^{\circ}C$</TEX> and strain rate 0.01-1 s-1 and a sound agreement is found.

Temperature Holding Hood for Hot Charging of Continuous Casting Slab in Tangshan Iron and Steel Company

To improve the charging of high-temperature billets, it is crucial to produce them with zero defects and achieve effective insulation during their hot delivery. A mathematical model was developed based on the heat transfer characteristics of the billet during its hot delivery. The accuracy of the model was established by studying the thermal performance of the cover of the roller conveyer for small billets in Tangshan Iron and Steel Company. The results show that the cover of the roller conveyer of the continuous casting billet can effectively reduce the heat loss during the hot delivery of the billets, and the hot loading temperature was increased by 51.6 °C. The uniformity of the temperature of the casting billet section increased substantially. The temperature difference in the casting billet section was reduced by 120 °C. The heat preservation effects of temperature holding hoods of different materials were compared. It was found that the material of the temperature holding hood has slight effect on the heat preservation.

The flow stress assessment of austenitic-martensitic functionally graded steel under hot compression

Article history: Received September 20, 2013 Received in Revised form October, 14, 2013 Accepted 9 February 2014 Available online 12 February 2014 In this research, the flow stress of dual layer austenitic-martensitic functionally graded steels (FGSs) under hot deformation loading has been modelled considering the Zener-Hollomon constitutive equations as a function of temperature and strain rate. Functionally graded austenitic-martensitic steels consist of austenite (γ) and martensite (M) phases placed on each other in different configurations and produced via Electro Slag Remelting (ESR). The boundary layers properties are obtained by experimental investigation on single phase materials. Finally, the theoretical model is compared with the experimental results measured in the temperature range 1000-1200 °C and strain rate 0.01-1 s and a good agreement is found. © 2014 Growing Science Ltd. All rights reserved.

Sensitivity study of process parameters in membrane electrode assembly preparation and SO2 depolarized electrolysis

The hybrid sulfur (HyS) thermochemical process is a promising approach for massive hydrogen production with nuclear or solar energy, while the SO2 depolarized electrolysis (SDE) is the crucial part of the HyS process. The influences of electrolysis conditions including temperature and electrolyte concentration, as well as the preparation conditions of the membrane electrode assembly (MEA), i.e. the resin content in catalyst layers, hot press temperature and catalyst loading, on the SDE performance, are experimentally studied. Reliability of MEA preparation process is verified through repeating electrolysis, optimized parameters of the MEA preparation process are obtained. Additionally, the effects of SDE performance to electrolysis conditions are clarified. Finally, a cell voltage empirical formula is determined with trial-and-error method.

Hot and heavy volume loading in the heat‐stressed, haemorrhagic male: modulating the Frank–Starling curve

The Frank–Starling mechanism is a fundamental concept in understanding cardiovascular physiology. The ability of the heart to alter its contractile response to different volume loading stimuli enables the body to respond to numerous perturbations including exercise, hypohydration, and orthostatic challenges which can initiate both gradual and rapid shifts in central blood volume.