bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of pattern recognition for dendritic microstructures
Authors: Strickland J , Nenchev B , Dong H B 
Published: June 2020

Abstract
The Primary Dendrite Arm Spacing (PDAS) is the most important length scale in directionally solidified single crystal alloys. It determines the propensity for defect formation, solution heat treatment times and mechanical properties of the material. In this work a CMSX4 single crystal sample was imaged under a Scanning Electron Microscope (SEM). An automatic dendritic mapping (DenMap) algorithm using Normalised Cross-Correlation (NCC) is combined with Shape-Limited Primary Spacing (SLPS) to determine the local nearest neighbour dendrites and the corresponding dendritic packing. The algorithm located the dendritic centres, calculated the local PDAS, packing pattern, and relationship between PDAS and packing pattern for 256 dendrites in 1 minute 10 seconds. This is the first fully automatic method to produce a clear Gaussian distribution of local PDAS and packing pattern; thus, enabling rapid data gathering potential for single-crystal microstructures.
Cellular automaton modelling to predict multi-phase solidification microstructures for Fe-C peritectic alloys
Authors: Ogawa J , Natsume Y 
Published: June 2020

Abstract
In this study, we developed a cellular automaton (CA) model to simulate the multiphase microstructural evolution of the solidification of Fe-C binary peritectic alloys. Three phases were considered in the model: δ, γ, and liquid (L). To simulate microstructures formed by the peritectic transformation, moving interfaces at δ-γ, δ-L, and γ-L transformations were introduced for diffusion-controlled growth. The coarsening growth of γ grains after solidification of peritectic alloys was modelled using the CA method. Numerical simulations of multi-phase microstructure evolution for hyper-peritectic and hypo-peritectic alloys were performed in two and three dimensions. In these simulations, the nuclei of γ phases were formed at the δ/L interface below the peritectic temperature. After nucleation of the γ phase in hyper-peritectic alloys, the δ phase in the calculation domain disappeared before γ solidification was completed. Conversely, in hypo-peritectic alloys, the L phase disappeared before the δ-γ transformation was complete. Moreover, the coarsening of γ grains occurred for both alloys after the end of the peritectic transformation. These outcomes agree with the fact that the phase transformation of alloys involves the solidification of peritectic alloys. Thus, we confirmed that the proposed model was a valid approach to simulating multi-phase microstructures formed by the solidification of peritectic alloys.
A cellular automaton approach for the prediction of grain size in grain refined alloys
Authors: Jacot A 
Published: June 2020

Abstract
Grain refinement by inoculation is widely practised in metal casting, in particular for aluminium alloys. During the last decades several modelling techniques have emerged to quantitatively predict solidification microstructures. The prediction of grain size remains however a challenge due to the complex competition between nucleation and growth, and physical phenomena taking place at very different length scales. Models often address the thermal recalescence and sometimes the suppression of nucleation by the solute boundary layers. The possible clustering tendency of the nucleant particles is however usually not considered, although it can play an important influence on the final grain size. This effect is particularly difficult to quantify because it requires a small-scale approach to describe the clusters, while a large computational domain is needed for grain size statistics. A cellular automaton (CA) model tracking the grain envelopes was developed to address this challenge. The spatial distribution of the nucleant particles and the solute diffusion field in the intergranular liquid were represented directly on the CA grid. Predicted grain sizes were first compared successfully with published experimental and modelling data. An investigation of the role of clustering of nucleant particles was then carried out, which demonstrated the potential of the model to address this topic.
Castings distortion of gas turbine engine parts during solidification and cooling
Authors: Inozemtsev A , Dubrovskaia A , Dongauzer K , Alapanova A , Maleev A 
Published: June 2020

Abstract
The paper studies the matters of numeric simulation of the processes of casting, crystallizing and cooling down to room temperature, and addresses the related problem of the stress-strain state of the casting process in manufacturing the cast parts of a gas turbine engine. The influence of the technological parameters of casting onto the development of the deformation defects was evaluated. The works were performed on incorporating predeformation into the burn-out model for compensating temperature deformations during casting, and on production and control of the above casting with predeformation.
Molecular dynamics study of composition dependence of solid-liquid interfacial energy of Fe-Ni binary alloy
Authors: Ueno K , Shibuta Y 
Published: June 2020

Abstract
Interfacial properties strongly affect solidification microstructure of practical alloy materials. Therefore, it is essential to understand interfacial properties including composition dependence for target alloys. In this study, composition dependence of solid-liquid interfacial energy of Fe-Ni alloy is investigated by molecular dynamics simulations in conjunction with a capillary fluctuation method. The solid-liquid interfacial energy of Ni-rich composition taking FCC-solid phase is larger than that of Fe-rich composition taking BCC-solid phase. Moreover, solid-liquid interfacial energy has a high anisotropy at the composition with FCC-solid phase compared to the one with BCC-solid phase.
Concurrent and coupled resolution of fluid flow and solid deformation in solidification processes
Authors: Zhang S , Guillemot G , Gandin C-A , Bellet M 
Published: June 2020

Abstract
Control of macrosegregation phenomena and deformation related defects is the main issue in solidification processes. Numerical modelling of casting provides an answer to industrial needs to master these defects. As a first step, it is essential to achieve a concurrent computation of the fluid flow in the bulk liquid and stress-strain evolution in the already solidified regions. For this specific purpose, a partitioned solution algorithm is developed to model both ingot casting and continuous casting processes: liquid flow induced by natural convection or filling step, solidification shrinkage as well as thermal deformation of solid phase are all taken into consideration. This article is mainly composed of two parts. In the first part, details of the model itself are described. In the second part, applications dedicated to steel solidification are proposed.
The ultrasound effects on the formation of the solidification structure of A356 ingots processed via a 2-zone induction melting furnace
Authors: Dong A , Nastac L 
Published: June 2020

Abstract
To study the formation of the solidification structure including the columnar-to-equiaxed transition (CET) under the influence of ultrasound, a 2-zone furnace system and an ultrasound equipment were utilized. The 2-zone furnace system consists of an induction furnace with a top coil and a bottom coil, a graphite crucible, and. a water-cooled chill block located at the bottom of the crucible. By controlling both the top and bottom coil output power independently, the furnace can create various temperature gradients and cooling rates in different regions of the graphite crucible. The ultrasound probe was inserted at the top of the crucible. The top of the crucible was also thermally insulated. Temperature measurements were performed at different locations in the crucible. Optical microscopy was used to characterize the microstructure of the A356 cylindrical ingots. The effects of ultrasound on the microstructure formation during solidification of A356 alloy was studied. A numerical model was developed to compute the temperature gradients and mushy zone evolution in the crucible and to assist in developing of solidification maps.
In situ X-ray observations of transient states in arc weld pools
Authors: Wu F , Falch K V , Drakopoulos M , Mirihanage W U 
Published: June 2020

AbstractMetallic alloys coalesce via extremely rapid melting and subsequent solidification to form fusion welded joints. The melt pool evolution in melting and solidification sequences during the welding process determines the formation of the final weld joint shape, microstructure and defects. The scientific insight on weld pool evolution and related phenomena can be a key contribution to enhance structural integrity and resilience of the welded structures or components. However, inherent complexity with multi-physics phenomena, associated high temperatures and the rapidness of the processes make direct experimental investigation of welding is extremely demanding. Thus, internal flow behaviour during welding or other melt-pool-based metal processing such as additive manufacturing remains unclear and hinders progression to process optimisation. In this contribution we report the observation of melt pool dynamics that take place during electric arc welding, obtained through in situ synchrotron imaging at millisecond scale. The analysis flow patterns along with the quantified weld pool surface dynamics revealed us to how different contributing forces dictate the flow conditions over the distinct durations of the relatively short existence of the liquid phase. Our preliminary results suggest the existence of arc, surface tension and gravity dominant regimes during the evaluation of the weld pool. Further, we present our observations on how different welding parameters influence these regimes and develop into different transient conditions.
Phase-field study on microstructure formation in Mar-M247 during electron beam welding and correlation to hot cracking susceptibility
Authors: Böttger B , Apel M , Jokisch T , Senger A 
Published: June 2020

Abstract
Ni-base superalloys are frequently used for cast components in the aero-engine and power generation industries. For joining and repair of these components, beam welding is often the method of choice in industrial praxis. However, precipitation-strengthened nickel alloys generally present poor weldability as a consequence of their high weld cracking susceptibility, with high segregating alloys like Mar-M247 even being considered unweldable. Therefore, strong efforts are taken on optimizing techniques and parameters to reduce crack formation during welding of these alloys. Optimization of welding parameters can be assisted by virtual modelling methods through different scales. To be able to focus onto the factors which eventually are responsible for crack formation during welding, comprehensive modelling of the whole process chain is required, starting from a realistic model of the base material and a simulation of the heat source on the macro-scale, and including melting and microstructure formation during welding on the micro-scale. Then, based on the thermal history and the exact microstructure, cracking susceptibilities during solidification can be deduced by hot cracking models adapted to the specific conditions. In this paper, results of microstructure simulations are presented for the technical superalloy MAR-M247 using the phase-field software MICRESS with coupling to Calphad databases. Based on prior phase-field simulations of equiaxed and columnar microstructures of the base material as well as results of a macroscopic simulation of the heat source, melting and subsequent solidification of MAR-M247 has been simulated for two different welding parameter sets. As-weld microstructures are compared to experimental welds, and the virtual hot cracking susceptibility, obtained from the simulation results using a modified Rappaz–Drezet–Gremaud (RDG) hot cracking criterion, is discussed against experimental crack observations.
Simulation study on the effect of fuel injection and air intake boundary setup on the brake torque response by using comprehensive vehicle model for natural gas vehicle (NGV)
Authors: Rahim M F A , Jaafar A A , Taha Z , Mamat R 
Published: June 2020

Abstract
An analytical, dynamic and comprehensive vehicle model, replicated a high-pressure direct injection compressed natural gas (HPDI-CNG) engine in a vehicle is proposed with the objective to study the effect of fuel injection and air intake boundary condition on the brake torque response. The model simulated the output torque in transient simulations of the natural gas vehicle (NGV) in speed-sweep mode test. The vehicle model has coupled an analytical engine model developed in Simulink with a Simscape driveline model which consists of a clutch model, a simple transmission gear and a simplified vehicle model. In all problem, independent input to the model is the throttle opening ramp. The adjusted parameter in the first study is the methods to calculate the mass of fuel inlet which is based on i) fully experimental data, ii) measured air to fuel ratio (AFR) and (iii) constant injector mass flow rate. In the second problem, the pressure limit of the manifold absolute pressure (MAP) is adjusted as (i) fully experimental data (ii) 1.2 bar (iii) 1.5 bar and (iv) unlimited pressure limit. The dependent parameter in all problem is engine output torque. The results have been compared with the actual data of torque from chassis dynamometer measurement. For the effect of fuel inlet boundary set up, in the fully predictive mode, the model predicted an almost constant maximum torque at a value about 70 Nm, whereas the measured data only produced the same peak value at a very limited instant. If the model used measured AFR as the fuel input boundary, the model overpredicted the maximum peak torque of 70 Nm. In the study on the effect of MAP limit, the maximum torque for 1.2 bar, 1.5 bar and unlimited pressure set up has produced a maximum torque of 45, 62 and 70 Nm, respectively. Results of the first study showed that the use of constant injector mass flow rate has a tendency to simulate an ideal engine acceleration process. The prediction is closed to the measured data if the fuel mass is calculated based on the measured AFR. However, the use of measured AFR in our opinion have reduced the model predictability. In the second study, the increased MAP limit significantly increased the maximum brake torque response. However, the model cannot predict the abnormalities found in the experimental data. The use of MAP limit demonstrated the sensitivity of the output torque on the maximum value of the engine MAP. The results indicated that the injection fuel inlet boundary and the MAP limit have a strong significance on the model prediction and need to be improved for future use of the model.
A review of ultra-high temperature materials for thermal protection system
Authors: Al-Jothery H K M , Albarody T M B , Yusoff P S M , Abdullah M A , Hussein A R 
Published: June 2020

Abstract
Ultra-High Temperature Materials (UHTMs) are at the base of entire aerospace industry; these high stable materials at temperatures exceeding 1600 °C are used to manage the heat shielding to protect vehicles and probes during the hypersonic flight through reentry trajectory against aerodynamic heating and reducing plasma surface interaction. Those materials are also recognized as Thermal Protection System Materials (TPSMs). The structural materials used during the high-temperature oxidizing environment are mainly limited to SiC, oxide ceramics, and composites. In addition to that, silicon-based ceramic has a maximum-use at 1700 °C approximately; as it is an active oxidation process over low temperature and water vapor environment condition. However, a great emphasis is required for developing structural materials in oxidation and rapid heating environment where the temperature is greater than 1700 °C. This review covers briefly all main types of Thermal Protection Systems (TPSs) and all the materials are used to fabricate them with the maximum operational temperatures. Also, it covers the promised UHTMs (SiC, ZrB2, HfB2, SiB6 and B4C) which are currently using for several aerospace applications, especially for TPS. Besides, it discusses the oxidation of SiC, B4C, SiB6, ZrB2 and HfB2. Therefore, the carbides and borides of the transition metals, Zr and Hf have a high-melting temperature and good stability in forming high-melting temperature oxides.
The effects of temperature, residence time and particle size on a charcoal produced from coconut shell
Authors: Ahmad R K , Sulaiman S A , Inayat M , Umar H A 
Published: June 2020

Abstract
Coconut shell charcoal is an important product obtained from coconut shells, which are widely used as domestic and industrial fuel. Wastes of coconut residues (shells, husks and coir) from processing of coconut milk and oil industries are widely generated everywhere all over the world. They have the potential of use as a fuel in renewable energy for different applications. In this study, the production of charcoal from coconut shell through the process of pyrolysis was conducted to determine the influence of particle size, temperature and residence time on the charcoal weight loss. Pyrolysis is a thermochemical conversion method which converts biomass into more valuable products in form of solid (charcoal, bio-char and activated carbon), liquid (oil) and gas in the absence of oxygen. The process was carried out under various process conditions of temperature (300 °C, 400 °C, and 500 °C), residence time (15 minutes, 30 minutes, and 60 minutes), and particle size (5.0 mm and 25.0 mm). It was found that for both the temperature and the residence time, the weight loss from the coconut shell increase linearly with increase in temperature and residence time. The particle size has influence in percentage weight loss. The resulting charcoal obtained can be utilized as an alternative energy resource for different applications.
Effect of reaction time and microwave power on coil temperature during microwave-metal interaction pyrolysis of plastics
Authors: Arshad H , Sulaiman S A , Hussain Z , Moni M N Z 
Published: June 2020

Abstract
Rapid rise in production of plastic waste has posed a threat to environment due to its nonbiodegradable nature. In recent years, microwave assisted pyrolysis of plastic waste has emerged as a promising solution toward reduction of waste and recovery of value-added products and fuels. Previous works on microwave-metal interaction pyrolysis estimated only the peak value of coil temperature at a constant microwave power without monitoring complete reaction. The current study was directed toward investigating the effect of reaction time and variable microwave power on the coil temperature during microwave-metal interaction pyrolysis of plastics. The experiment was performed on individual plastics PS (polystyrene), PP (polypropylene) and LDPE (low density polyethylene) for comparative analysis. Pyrolysis was carried out for a reaction time of 30 minutes at different values of microwave power in the range of 500-2500 W. Type K thermocouple was used to monitor temperature of metal coil. Fluctuation in temperature of coil was found to be a consequence of interaction of coil and thermocouple with the microwaves. Maximum heating rate was observed in the first 5 minutes of microwave exposure. The slopes of average temperature versus microwave power were found to be nearly equal estimated as: PS = 0.24 °C/W, PP = 0.20 °C/W, LDPE = 0.18 °C/W, which indicated consistency in heating process for each plastic, achieved by the current set-up. Further, it was inferred that nature of plastic pyrolyzed had insignificant influence on coil temperature due to absence of direct contact between plastic and the coil.
Characterisation of oil palm trunk and frond as fuel for biomass thermochemical
Authors: Umar H A , Sulaiman S A , Ahmad R K , Tamili S N 
Published: June 2020

Abstract
The rate of oil palm production in Malaysia increases annually and as a result, the oil palm wastes, especially oil palm trunk (OPT) and oil palm fronds (OPF) remain abundant. A suitable way of converting this abundant waste to renewable energy is through thermochemical conversion. Thus, this study investigates the characteristics of OPT and OPF biomass, for use as feedstock in thermochemical processes like gasification, pyrolysis, and combustion. The analysis carried out includes; ultimate (CHNSO) and proximate (thermogravimetric) analysis, calorific value, field emission scanning electron microscopy (FESEM) and x-ray fluorescence (XRF). Both feedstocks exhibited potential for use as fuel in biomass thermochemical conversion. The CHNSO analysis showed the presence of sufficient carbon, hydrogen and oxygen elements in both feedstocks, with carbon being the highest 45.42% in OPT and 43.35% in OPF. The percentages of nitrogen and sulphur which are required to be less for a good fuel were also obtained in low quantities for both fuel; 0.47% and 0.13% in OPT and 0.76% and 0.45% in OPF, respectively. The thermogravimetric analysis revealed both feedstocks to be having high volatile matter 62.28% in OPT and 66.10% in OPF. Meanwhile, sufficient fixed carbon content of 26.18% in OPT and 25.68% in OPF with low ash content of 9.82% in OPT and 6.32% in OPF were obtained in the analysis. FESEM and XRF were used to investigate the surface morphology, elemental and mineralogical nature of the samples. The findings were compared with those of other biomass and non-biomass materials. The EDX graph showed the presence of carbon and oxygen in a higher amount while in the XRF analysis CaO and K2O were the major oxides present in both OPT and OPF, with a low amount of SiO making the feedstocks less prone to agglomeration during thermochemical conversion.
Study of effect of moisture and temperature on thermal and physical properties of limestone using a transient plane source technique
Authors: Anjum F , Rasool F , Mohyudin F , Ameen A , Naz M Y , Ghaffar A , Shukrullah S 
Published: June 2020

AbstractThis study investigated the thermophysical properties of limestone in its dry and moist states. A thermal constant analyser, based on Transient Plane Source (TPS) technique, was used to study the thermophysical properties. Temperature dependence of thermophysical properties of limestone was investigated by elevating the temperature up to 433 K. The chemical and mineral composition of samples were studied using SEM-EDS and XRD analysis. The thermal conductivity of dry and moist limestone showed that in situ measurements are necessary for the precise determination of thermal properties. The variations in thermal properties of limestones as a function of temperature were described by mineral composition and heat transfer mechanism. The thermal conductivity of limestone was measured in the range of 2.586 to 3.054 Wm−1K−1. The thermal diffusivity of samples was ranged from 1.390 to 1.601 mm2s−1while specific heat capacity of limestone was in the range of 1.847 to 2.066 MJm−3K−1. A noticeable change in thermal properties of moist limestone was observed as compared to the dry limestone.