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Neurofibromatosis is a genetic disorder arising de novo or with an autosomal dominant transmission that typically presents either at birth or in early childhood, manifesting through distinctive clinical features such as multiple café-au-lait spots, benign tumors in the skin, bone enlargement, and deformities. This literature review aims to resume the spectrum of maternal and fetal complications encountered in pregnant women with neurofibromatosis type 1 (NF1). Thorough research was conducted on databases such as Web of Science, PubMed, Science Direct, Google Scholar, and Wiley Online Library. This review includes 48 case reports, original studies, and reviews on NF1 in pregnancy. The research on the interlink between NF1 and fertility and its influence on human-assisted reproduction techniques is limited. Preimplantation testing (by in vitro fertilization) and prenatal diagnosis (by chorionic villus sampling or amniocentesis) are available to detect affected fetuses. However, genotype–phenotype correlation is difficult to predict. Preconceptional planning and targeted investigations are crucial in understanding the extent of maternal disease. Although in some cases lesions can evolve rapidly during pregnancy, most pregnancies and births in NF1 go well with careful planning. There is a higher incidence of pheochromocytomas and pre-eclampsia, vascular rupture, and cardio-respiratory issues. Anesthesia at birth is a challenge in most cases, and before offering spinal anesthesia, imaging tests should be performed to characterize spinal lesions. General anesthesia may also be challenging when the disease affects the face, neck, upper spine, or airways. Birth-related difficulties may arise because of large neurofibromas located at the level of skin incision or birth canal; uterine atony may be expected if there are uterine lesions. Some complications can develop in postpartum, and affected women should be carefully followed even after pregnancy. Fetal risks include preterm birth (spontaneous or iatrogenic), growth restriction and developmental issues, birth complications, cardiovascular risk, and fetal/neonatal demise. Pregnancies in women with NF1 should be regarded as high-risk and followed in a multidisciplinary fashion. Careful assessment of lesions is of utmost importance before and during pregnancy for anticipating potential maternal risks and before birth to plan anesthesia and delivery. [ABSTRACT FROM AUTHOR]

The rheological modeling of soil–drum interaction in the vibratory compaction process is a complex process. This paper aims to describe the behavior of soil–drum interaction through lumped parameter modeling. The amplitude of the vertical motion is evaluated for dynamic conditions using the rheological models (generalized and advanced Kelvin–Voigt-based models) and compared with the experimental results obtained from weakly cohesive soil compaction. Different modeling approaches are considered, and the results reveal that the properties of the soil as input play a vital role in the accuracy of the modeling. [ABSTRACT FROM AUTHOR]

Cellulose-based foams present a high potential for noise insulation applications. These materials are bio-degradable, eco-friendly by both embedded components and manufacturing process, have low density and high porosity, and are able to provide good noise insulation characteristics compared with available petroleum-based foams currently used on a large scale. This paper presents the results of some investigations performed by the authors in order to improve the functional characteristics in terms of free surface wettability and structural integrity. Native xylan and xylan-based derivatives (in terms of acetylated and hydrophobized xylan) were taken into account for surface treatment of cellulose foams, suggesting that hemicelluloses represent by-products of pulp and paper industry, and xylan polysaccharides are the most abundant hemicelluloses type. The investigations were mainly conducted in order to evaluate the level to which surface treatments have affected the noise insulation properties of basic cellulose foams. The results indicate that surface treatments with xylan derivatives have slowly affected the soundproofing characteristics of foams, but these clearly have to be taken into account because of their high decrease in wettability level and improving structural integrity. [ABSTRACT FROM AUTHOR]

Due to the widespread use and familiarity of austenitic stainless steels (SS) in many industries these alloys are often the first materials used when adapting new processing techniques. The rapid cooling and solidification rates that occur during fusion based additive manufacturing processes like powder bed fusion cause a fundamental shift in the solidification behavior of the material. While the effects that Cr and Ni have on the microstructure have been fairly well documented across a range of solidification conditions, the impact of alloying elements like Mo are not as well understood at rapid solidification rates. For this study, four custom SS alloy feedstocks were made with targeted modification of the Cr and Mo concentrations to maintain a constant Cr/Nieq ratio of ~ 1.7. Two-piston splat quenching was used to produce rapidly solidified samples and the solidification mode, phase, and cell size were investigated. Solidification rates were estimated to be between 0.4 and 1.5 m/s. A comparison of the microsegregation and partitioning behavior of Cr, Ni and Mo in ferrite solidified material was also performed for the different alloy compositions. Variations of the Mo concentration between each feedstock showed no measurable influence on the solidification/cooling rates, solidification morphology, or the partitioning of Mo. However, higher concentrations of Mo were found to significantly increase the amount of ferrite phase in the microstructure by suppressing the ferrite to austenite massive transformation. [ABSTRACT FROM AUTHOR]

For solidification rates at or near equilibrium solidification conditions the effects of chrome (Cr) and nickel (Ni) on stainless steel solidification modes and microstructures are well detailed. However, fusion-based additive manufacturing (FBAM) processes that rely on faster, more rapid solidification rates call for a more in-depth understanding of the effects of rapid solidification on the solidification behavior and how these change with variations in alloy composition. Eleven custom stainless steel (SS) alloys with unique compositions based on 316L were made using targeted alloying element additions to generate feedstock with Cr/Nieq ratios ranging from 0.9 to 2.1. Two-piston splat quenching (SQ) was used to produce rapid solidification conditions similar to those achieved in powder bed fusion processes in a fraction of the time and cost of traditional methods. Employing heat transfer simulations, SEM, TEM, and STEM characterization techniques, the SQ process was found to consistently produce solidification rates estimated to be between ~ 0.4 and 1.6 m/s. Five unique solidification microstructures were identified within the rapidly solidified SQ samples (primary austenite, massively transformed ferrite to austenite, primary austenite and massively transformed ferrite to austenite, primary ferrite, and primary ferrite and massively transformed ferrite to austenite). Both the primary ferrite solidification mode and primary ferrite phase were found to form at lower Cr/Nieq values than previously predicted. SQ samples with compositions that were within the compositional specifications for 316L SS, an alloy which is commonly used in FBAM processes, demonstrated a wider range of potential solidification modes and microstructures that could form at rapid solidification rates than expected. By using SQ as a means to simulate rapid solidification conditions similar to those observed in FBAM processes, potential new alloy compositions can be screened faster and more cost effectively than purchasing and running test batches of the metallic powder. [ABSTRACT FROM AUTHOR]

This paper examines effective and environmentally friendly materials intended for noise insulation and soundproofing applications, starting with materials that have gained significant attention within last years. Foam-formed materials based on cellulose fibers have emerged as a promising solution. The aim of this study was to obtain a set of foam-formed, porous, lightweight materials based on cellulose fibers from a resinous slurry pulp source, and to investigate the impact of surfactant percentage of the foam mixtures on their noise insulation characterisitcs. The basic foam-forming technique was used for sample assembly, with three percentages of sodium dodecyl sulphate (as anionic surfactant) related to fiber weight, and a standardised sound transmission loss tube procedure was used to evaluate noise insulation performance. Results were obtained as observations of internal structural configurations and material characteristics, and as measurements of sound absorption/reflection, sound transmission loss, and surface acoustic impedance. Based on the findings within this study, the conclusions highlight the strong potential of these cellulosic foams to replace widely used synthetic materials, at least into the area of practical noise insulation applications. [ABSTRACT FROM AUTHOR]

Collisionless and weakly collisional plasmas often exhibit non-thermal quasi-equilibria. Among these quasi-equilibria, distributions with power-law tails are ubiquitous. It is shown that the statistical-mechanical approach originally suggested by Lynden-Bell (Mon. Not. R. Astron. Soc. , vol. 136, 1967, p. 101) can easily recover such power-law tails. Moreover, we show that, despite the apparent diversity of Lynden-Bell equilibria, a generic form of the equilibrium distribution at high energies is a 'hard' power-law tail $\propto \varepsilon ^{-2}$ , where $\varepsilon$ is the particle energy. The shape of the 'core' of the distribution, located at low energies, retains some dependence on the initial condition but it is the tail (or 'halo') that contains most of the energy. Thus, a degree of universality exists in collisionless plasmas. [ABSTRACT FROM AUTHOR]

Violin studies can be classified into two main types: psychoacoustic studies, which are based on the artistic perception of audibility by violinists and vibro-acoustic studies, which are based on the spectral analysis of the vibrations and sounds produced by the instruments. The paper presents the acoustic analysis of violins by means of specialized software, their main acoustic characteristics being extracted in the form of frequency spectrum, spectrograms, specific modes and number of harmonics. These results were compared with the results of the opinion poll among musicians regarding the acoustic qualities of violins, based on musical auditions. The results highlighted the fact that the acoustic analysis technique cannot detect in totality the psycho-acoustic effects of musical sounds, therefore the establishment of the acoustic quality of the instruments on objective foundations, since the personal touch of an instrumental artist aims at the approach and articulation of the musical discourse, in a complex manner, combined with the interpretation of forms and styles. [ABSTRACT FROM AUTHOR]

A fully transient discrete-source 3D Additive Manufacturing (AM) process model was coupled with a 3D stochastic solidification structure model to simulate the grain structure evolution quickly and efficiently in metallic alloys processed through Electron Beam Powder Bed Fusion (EBPBF) and Laser Powder Bed Fusion (LPBF) processes. The stochastic model was adapted to rapid solidification conditions of multicomponent alloys processed via multi-layer multi-track AM processes. The capabilities of the coupled model include studying the effects of process parameters (power input, speed, beam shape) and part geometry on solidification conditions and their impact on the resulting solidification structure and on the formation of inter layer/track voids. The multi-scale model assumes that the complex combination of the crystallographic requirements, isomorphism, epitaxy, changing direction of the melt pool motion and thermal gradient direction will produce the observed texture and grain morphology. Thus, grain size, morphology, and crystallographic orientation can be assessed, and the model can assist in achieving better control of the solidification microstructures and to establish trends in the solidification behavior in AM components. The coupled model was previously validated against single-layer laser remelting IN625 experiments performed and analyzed at National Institute of Standards and Technology (NIST) using LPBF systems. In this study, the model was applied to predict the solidification structure and inter layer/track voids formation in IN718 alloys processed by LPBF processes. This 3D modeling approach can also be used to predict the solidification structure of Ti-based alloys processes by EBPBF. [ABSTRACT FROM AUTHOR]

Characterization of unsteady loads is critical for the development of control systems for next-generation air vehicles. Both Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) methods are prohibitively expensive, and existing Reynolds-Averaged Navier-Stokes (RANS) approaches have been shown to be inadequate in predicting both mean and unsteady loads. In recent years, scale-resolving methods, such as Partially Averaged Navier-Stokes (PANS) and Detached Eddy Simulation (DES), have been gaining acceptance and filling the gap between RANS and LES. In this study, we focus on a new variant of the PANS method, namely blended PANS or BPANS, which was shown to perform well in the incompressible regime for both wall-bounded and free shear flows. In this paper, we extend BPANS to compressible supersonic flows by adding a compressibility correction, leading to a new model called BPANS CC. The new model is tested using a well-known supersonic mixing layer case, and the results show good agreement with experimental data. The model is then used on a complex supersonic retropropulsion case and the results are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

In this work, we propose a cost-effective procedure to obtain magnetic single cotton yarns by employing commercially available magnetic powders and adhesives. Two different indirect magnetization methods are used on the yarns coated with several mixtures containing barium hexaferrite (BaFe12O19) as hard magnetic powder. The BH mass percentage is varied between 10% and 50%. Specific textile coating binders such as polyurethane and polyvinyl acetate are used as adhesives. A constant amount of 5% glycerol is employed as plasticizer agent. An in-house developed laboratory equipment is used to produce the magnetic cotton yarns. The equipment allows primary orientation of the magnetic particles along external field lines and subsequent magnetization until saturation. Our studies show that the diameter of the coated yarns is directly dependent on the amount of magnetic powder in the coating solution. Thus, the magnetic yarn diameter increases by 30% when compared to the 356 µm diameter of the reference (uncoated) yarn for a barium hexaferrite mass percentage of 50%. Also, our studies reveal that increasing the magnetic properties (residual magnetism and coercive field intensity) of the composite yarns is possible only by increasing the mass percentage of the magnetic powder content. The highest values of the magnetic properties have been measured when neodymium permanent magnets (NdFeB) were used for the magnetization instead of a toroidal coil. The residual magnetization and saturation increase with the amount of barium hexaferrite embedded in the textile yarn. However, the increase in mass percentage is limited by the degradation of the yarn properties which allow them to be used for textile applications. SEM images of the coated yarns reveal a relatively uniform deposition of magnetic layer on the reference cotton yarn. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study performed on seven violins obtained from a top plate made of resonance spruce and a back plate made of curly maple. Each pair of plates had a different modification to its thickness profile. Some were thickened and others were thinned compared to the classical thickness profile. Then, a soloist played a musical sequence on each violin and the acoustic signals were recorded. The sound quality of the signals was evaluated with a psycho-acoustic evaluation based on a blind questionnaire completed by listeners. It turned out that: (1) respondents with more musical experience (especially those with over 26 years of experience) were more demanding in assessing sound clarity and offered the widest range of scores in assessing this quality; (2) the musical experience of the respondents influenced to the highest degree the appreciation of the warm sound quality; (3) the scores for the violins with thinned plates were weaker, especially according to the psycho-acoustic analysis; and (4) the highest score was obtained by the violin with the thickest plates, which can be correlated with the two dominant frequencies extracted from the FFT analysis, whose values coincide with the frequencies of the B1− and B1+ modes. [ABSTRACT FROM AUTHOR]

The paper presents the interdisciplinary approach of two fields - the artistic (musical) and technical (forestry engineering, wood processing engineering, mechanical and physical engineering) apparently opposite but which can be happily exploited for both parties. Thus, we can speak of a new paradigm of education through which art can combine with the technical sciences for the benefit of all. The aim of the paper is to present experimental methods in mechanical and acoustic evaluation of violins from engineering and artistic perspectives. The presented results are part of a larger study carried out within an experimental demonstration research project. [ABSTRACT FROM AUTHOR]

This paper addresses the experimental and numerical dynamic analysis of curved bars used as percussion musical instruments. These structures are known as triangles, being made of various metal materials. The study was based on the experimental analysis of the dynamic response over time and the frequency of three types of triangles, different in material and size. Subsequently, finite element analysis of the same structures modeled with the SimCenter 12 program was performed. The results were compared, highlighting the contribution of material type and geometry in obtaining vibration modes, frequency spectrum, and structural damping coefficient. Between the experimental and the numerical analysis, the obtained errors were below 2.2% in terms of their natural frequencies. The study also highlights the complementarity of the two methods in understanding the vibration modes of triangles. [ABSTRACT FROM AUTHOR]

The structure of wind turbine blades (WTBs) is characterized by complex geometry and materials that must resist various loading over a long period. Because of the components' exposure to highly aggressive environmental conditions, the blade material suffers cracks, delamination, or even ruptures. The prediction of the damage effects on the mechanical behavior of WTBs, using finite element analysis, is very useful for design optimization, manufacturing processes, and for monitoring the health integrity of WTBs. This paper focuses on the sensitivity analysis of the effects of the delamination degree of fiberglass-reinforced polymer composites in the structure of wind turbine blades. Using finite element analysis, the composite was modeled as a laminated structure with five plies (0/45/90/45/0) and investigated regarding the stress states around the damaged areas. Thus, the normal and shear stresses corresponding to each element of delaminated areas were extracted from each ply of the composites. It was observed that the maximum values of normal and shear stresses occurred in relation to the orientation of the composite layer. Tensile stresses were developed along the WTB with maximum values in the upper and lower plies (Ply 1 and Ply 5), while the maximum tensile stresses were reached in the perpendicular direction (on the thickness of the composite), in the median area of the thickness, compared to the outer layers where compression stresses were obtained. Taking into account the delamination cases, there was a sinuous-type fluctuation of the shear stress distribution in relation to the thickness of the composite and the orientation of the layer. [ABSTRACT FROM AUTHOR]

The paper aims to investigate old and new violins from the perspective of the correlation between the anatomical structure of spruce and maple wood, and the dynamic response of violins. Thus, in the first stage, for each violin, the characteristics of the annual rings were measured on the entire width of the top plate, determining the degree of symmetry of the face with respect to the longitudinal axis of the violin body. Then, each violin was dynamically tested with the impact hammer, determining its own frequency spectrum, mainly the so-called "signature" mode and quality factors. The most important findings consist of identification of the first five modes for old violins, (known as provenance), current new violins, and violins whose origin is unknown, but which could correlate with anatomical, constructive and dynamic characteristics, in order to be able establish origins, and also the measurement of anatomical features of top and back plates in the violins' construction. [ABSTRACT FROM AUTHOR]

Background: Medical technology is far from reaching its full potential. An area that is currently expanding is that of precision medicine. The aim of this article is to present an application of precision medicine—a deep‐learning approach to computer‐aided diagnosis in the field of dermatology. Materials and Methods: The main dataset was proposed in the edition of the ISIC Challenge that took place in 2019 and included 25 331 dermoscopic images from eight different categories of lesions—three of them were malignant and five benign. The behavior of the model was also tested on a dataset collected from the second Department of Dermatology, of the Colentina Clinical Hospital. Results: The overall accuracy of the model was 78.11%. Of the total 5031 samples included in the test subset, 3958 were correctly classified. The accuracy of the model on the clinical dataset is lower than that obtained in the first instance. Conclusion: The architecture of the model can be considered of general use, being able to be adapted in an optimal way for a wide range of classifications. The model has achieved performance within the expected limits but can be further improved by new methods. [ABSTRACT FROM AUTHOR]

In this study, three machine learning (ML) models were developed to predict the secondary dendrite arm spacing (SDAS) and then predictions were validated experimentally. First, a three-layer artificial neural network (ANN) was built to predict the SDAS. Then, a linear regression model (LR) with backward selection method is applied to study the relationship of different elemental properties, processing parameters, and SDAS and make a prediction. A principle component analysis (PCA) further explores these relationships. The results show that the ANN model has the best performance compared with the LR and PCA models. Compared with the classical coarsening equation, the current SDAS predictions reveal a deviation from nearly linear relationship with the negative cubic root of cooling rate, which indicates there are other elemental properties that should be accounted for. [ABSTRACT FROM AUTHOR]

Climate change creates new challenges for preventing and protecting human health against different diseases that could appear and propagate. The Aedes albopictus mosquito species is an important vector for different diseases like dengue fever or zika. Although this species is not "indigenous" in Europe, its presence is noticed in many countries on the continent. The Ae. albopictus establishment is conditioned by the species' characteristics and environmental factors. To assess the possible spread of Ae. albopictus in the Dobrogea region (situated in the Southeast of Romania), we conducted the following analysis: (1) Investigation of the current distribution and climatic factors favoring Ae. albopictus' establishment in Europe; (2) Analysis of climate dynamics in Dobrogea in terms of the parameters identified at stage (1); (3) Testing the hypothesis that the climate from Dobrogea favors Ae. albopictus' establishment in the region; (4) Building a Geographic Information System (GIS)-based model of the potential geographic distribution of Ae. albopictus in Dobrogea. Results show that the climate of Dobrogea favors the apparition of the investigated species and its proliferation. [ABSTRACT FROM AUTHOR]

A 3D transient CFD–reaction coupled model is developed to predict the slag–metal reaction and desulphurization kinetics in ladle furnace with both molten slag and air layers considered. The coupled model is able to predict the circulating flow field, capture the transient fluctuation characteristics of slag–air and steel–slag phase interfaces as well as the reaction area. Results also indicate that the distribution and evolution of the steel composition under gas stirring is predicted well. The influence of the chemical compositions of molten steel and slag on sulphur removal efficiency is studied. It is displayed that the Al addition into liquid steel or CaO addition into slag would increase the sulphur distribution ratio, resulting in the improvement of desulphurization efficiency. [ABSTRACT FROM AUTHOR]

The residual strains in three high-pressure die cast A383 engine blocks were measured using neutron diffraction. Residual strains and stresses can be generated during high-pressure die casting process due to high thermal gradients and may cause fatigue failure or dimensional distortion. Neutron diffraction can measure the residual strain distributions deep inside castings with complex geometries, because neutrons can penetrate substantially more material than x-rays. In the present work, the residual strains (in the axial and hoop directions) along the whole cylinder bridge of high-pressure die cast A383 engine blocks in as-cast and heat-treated conditions were measured by neutron diffraction methods. The effect of heat treatment on the distribution and magnitude of residual strains was also investigated. The results indicate that the residual strain in the cylinder bridge is tensile in both the axial and hoop components for both the as-cast and the heat-treated engine blocks. The residual strain in the hoop direction is bigger in magnitude than the residual strain in the axial direction. Heat treatment significantly relaxes the residual strain in the axial direction but only slightly relaxes the residual strain in the hoop direction. [ABSTRACT FROM AUTHOR]

Laboratory scale experimental and modeling results of one-sided upward flame spread over wavy cellulosic paper samples are presented. The sinusoidal shaped samples with varying wavelength and amplitude are aligned perpendicular to the gravitational direction so the upward buoyant flow sees peaks and valleys along its flow path. Depending on the wave amplitude and wavelength, the flame can spread from sample peak to peak initially but may later sustain slow burning from isolated flamelets inside the sample valleys or become quenched. The degree of fuel burning completeness, pyrolysis front spread rate, and extinction limits (both local and overall) depend on the wavy parameters in a complex way as well as the ambient relative humidity. Flame spread over wavy samples thus has unique features not found in continuous flat samples nor in discrete samples. Video records of the experiments supplied in the paper present both the front and the side views of these interesting transient flame developments. A simplified two-dimensional numerical model was formulated and solved to show selected salient features of the complex fluid dynamics over wavy structure and the heat transfer and burning characteristics of the wavy samples. [ABSTRACT FROM AUTHOR]

In the present study, the fundamental model for interfacial heat transfer coefficient (IHTC) in high-pressure die-casting (HPDC) developed by Hamasaiid et al. is re-examined using numerical simulations and established literature. The role of impact pressure on the peak IHTC is re-evaluated for the Aluminum alloy Al-9Si-3Cu and the magnesium alloy AZ91D. Currently, ANSYS FLUENT does not have a mesh independent model for air gap evolution at the die-casting boundary. To address this, an implementation of the Hamasaiid model is built for ANSYS FLUENT 18.1 and its results are compared to experimental work. All the derivations and code for the simulations are offered as open source under the GNU General Public License v3.0. [ABSTRACT FROM AUTHOR]

In this study, a chromium carbide layer was fabricated by an in-situ casting technique on ductile iron cast components. The procedure consists of (i) applying a ferrochrome slurry at the surfaces of silica sand moulds to create a surface layer (e.g. coating) and (ii) use a ductile iron alloy to cast the coated moulds. The microstructure of the realised surface layer was characterised and analysed via Scanning Electron Microscopy (SEM), optical microscopy (OM) and X-ray Diffraction (XRD).The corrosion behaviour of the samples was analysed by an electrochemical method using 0.03 M NaCl. The wear tests and Vickers hardness measurements were performed to determine the properties of the surface layer. It was determined that the layer is composed of chromium carbide (Cr7C3), ledeburite and pearlite. The 'chromium carbide'constituent improved significantly both the wear resistance and the hardness of the surface layer. Electrochemical measurements have indicated that the carbide-based layer exhibits a lower corrosion resistance than the substrate (e.g. casting). [ABSTRACT FROM AUTHOR]

This work is focusing on electrospinning polyethylene oxide (PEO) with incorporated barium ferrite nano-particles (BaFe) and the characterization of the magnetic properties of the obtained composites fibers. The barium ferrite powders used belong to a group of ferrites with hexagonal crystal structure. PEO has low toxicity, is water soluble, and is available in a variety of molecular weights of which 600.000 g/mol was used in this study. Following successful electrospinning of magnetic composite fibers, we have selected two samples, denoted as S1 and S2, for further investigation. The process parameters corresponding to the production of S1 and S2 differ only by the needle tip-to-collector distance which is larger for S2 (70 mm as compared to 50 mm). SEM images and fiber diameter distributions reveal that, as previously shown for pure PEO electrospun fibers, the average fiber diameter is decreasing with decreasing tip-collector distance. In addition, the distribution of the fiber diameters for the S1 sample is wider than the one for S2. This is indicative of a less controlled electrospinning process in the case of the S1 sample. Magnetic measurements on composite fibers reveal an expected ferrimagnetic behavior and no major differences between the magnetic properties of S1 and S2. [ABSTRACT FROM AUTHOR]

Modelling of gas evolution during sand-mould castings is one of the most important technical and environmental issues facing the metal casting industry. The current effort focused on developing the capability of numerically predicting the gas evolution for the furan binder-silica sand system. Specifically, the decomposition of furan was experimentally analyzed and then predicted based upon the work developed in the current project. This methodology can be easily implemented into existing commercial casting codes. A parametric study was also performed for steel 4340 and aluminium A356 cylinders (D100 × H200 m) and bars (H50 mm × W50 mm × L250 mm) cast into silica sand moulds (furan binder) of 50-mm mould wall thickness to investigate the effects of superheat and heating/cooling conditions of the mould on the gas evolution. Such information would enable more technically and environmentally friendly decisions to be made concerning the process design used to make a given casting. [ABSTRACT FROM PUBLISHER]

In the present study, a numerical model was developed to investigate the heat transfer effect of single-phase turbulent flow in a "bubbler" geometry, typical for cooling channels in the high-pressure die-casting process. A steady-state k-ω model with fine near-wall resolution was compared with established empirical relations developed by Gnielinski et al. for pressure drop and Nusselt numbers in turbulent flow in smooth pipes and annular ducts. The empirical relations matched well with the simulations. At the "tip" of the bubblers, impingement of the flow to the channel wall was found to intensify heat transfer locally. Increasing the ratio between inner and outer pipe diameters caused the flow to separate, increasing the pressure drop at the bend and the intensification of heat transfer. [ABSTRACT FROM AUTHOR]

This article examines the influence of an induction coil position and configuration on the fluid flow and heat transfer characteristics in electromagnetic (EM) solidification processes. The mutual inductance technique was used to solve for the EM field, whereas a dual-zone model was used to describe the flow in the two-phase "mushy" region, and accounts for damping of the flow due to grain growth within the suspended particle region. Simulations were performed for a A319 aluminum alloy within a laboratory-scale casting apparatus surrounded by a six turn coil for three configurations and three locations with respect to the melt. It was found that the coil arrangement had only a small effect on the flow structure and velocities in comparison with the coil position. The implications with regard to solidification behavior are discussed. [ABSTRACT FROM AUTHOR]

This study deals with the area of nonlinear and random mechanical vibration. It was supposed a simple classical vibratory system with translational motion, simulated as a single degree of freedom system. It was additionally considered that the main parameters characterizing inertia, dissipation and rigidity were affected by some uncertainties during the system evolution under the external dynamic load. The paper presents a method and a computational tool being able to provide useful information regarding the possible response of this system subjected by external harmonic loads. The results were comparatively analyzed with those obtained by the method of extremes identification of variation interval. [ABSTRACT FROM AUTHOR]

A full-scale, three-dimensional, transient CFD modelling approach capable of predicting the three-phase fluid flow characteristics and the inclusion removal in a gas-stirred ladle was developed. The comparison with experimental data indicates that this model can accurately predict the multiphase fluid flow and slag eye behaviour. The transport and removal of the inclusions in the gas-stirred ladle were predicted by tracing the movement of individual inclusions through computing their particle trajectories and considering a fluctuant top slag layer. The effects of inclusion size, gas flow rates, and injected bubble diameters as well as various removal mechanisms including slag capture, bubble attachment, and ladle wall adhesion on the removal of inclusions were investigated. It is shown that the slag capture is the prevailing mechanism for inclusion removal and the gas flow rate is the most important parameter for enhancing the inclusion removal efficiency. [ABSTRACT FROM AUTHOR]

The aim of this paper is to evaluate the mechanical and surface properties of lignosellulosic fibres reinforced composite before and after photo-degradation exposure. This leads to decrease the mechanical properties of composite as modification of hydrophobic behavior of matrix. In the study, the lignocelluloses specimens were obtained by mix polyester resin type 440- M888 POLYLITE, in a volume percentage of 25 %, with different wood particles classified by size classes. The samples were exposed to UV-A radiations with a wavelength λ of 365 nm for 168 hours (7 days). The evaluation of the surface energy was carried out by the θ contact angle method. For mechanical properties, the dynamic mechanical analysis (DMA) was used to determine the variation of storage and loss modulus. The results showed that UV radiation induced structural morphological instability, which leads to hydrophilic effect. The loss modulus recorded an increasing with increases of wood particles sizes. [ABSTRACT FROM AUTHOR]

This study deals with estimation of milling shape accuracy and trajectory conformity for small CNC 3D milling machines, based on vibration monitoring during the regular working cycles. The author made a large number of experimental tests, acquiring the acceleration signals, both on the milling tool-holder and on the bed frame. In order to evaluate the appropriate spectral characteristics of different machine parts and their weights on equipment dynamics, it was analyzed both the complete and the partial working cycle (such as forward tool motion, with or without effective milling, with or without tool driving, exclusively the milling cutter transitory/stabilized regime) for different basic milling shapes. The acceleration signals were jointly time-frequency investigated in order to evaluate specific spectral indicators related to the real motion characteristic of milling tool. It was used short time fast Fourier transform (STFFT) and Hough transform (HT) algorithms, along with stochastic evaluation of signal parameters, within time and frequency domains. The results reveal an accurate correlation between the specific transitory dynamics of the machine and the imposed milling shape. Main implications of the results within this analysis involve the noninvasive and facile investigation for milling errors of the CNC machine, conformity of tool head trajectory, identification of potential failure source, or damaged machine part. [ABSTRACT FROM AUTHOR]

A three-dimensional discrete phase model-volume of fluid coupled model has been developed to study the argon/steel/slag/air multiphase flow and mixing phenomena in an industrial gas-stirred ladle taking the coalescence, expansion and breakup of the argon bubbles as well as the fluctuant slag layer into account. The simulated results of the flow rate and bubble size evolution of the water model, as well as the slag eye size, are in good agreement with the experimental results reported in the literature. The modeling results show that the expansion of bubbles has a significant impact on the bubble size evolution and multiphase flow in an industrial ladle. The effects of different plug configurations on the flow characteristics and mixing time in the ladle are also investigated. [ABSTRACT FROM AUTHOR]

The effect of ultrasonic treatment (UST) on the formation of Fe-rich intermetallics (including sludge) in the A383 alloy is investigated for different processing temperatures in the present study. Differential scanning calorimetry is used to analyze the precipitation temperature of the sludge phase. The results revealed that the sludge will precipitate at a temperature above that of the Al matrix and the precipitation temperature decreases with an increasing cooling rate. UST cavitation applied at different temperatures (600 °C to 750 °C) during the solidification process breaks the sludge into small island-like pieces. However, the aggregation trend of the sludge is not changed. Sludge with small size and uniform distribution is obtained when UST is applied at 600 °C, which is lower than the precipitation temperature of the sludge. At the highest temperature (850 °C), the application of UST has no effect on the formation of either sludge or α-Fe intermetallics. At 750 °C, UST promotes the formation of the sludge when applied at 750 °C. [ABSTRACT FROM AUTHOR]

This study deals with the area of nonlinear and random mechanical vibration. It was supposed a simple classical vibratory system with translational motion, simulated as a single degree of freedom system. It was additionally considered that the main parameters characterizing inertia, dissipation and rigidity were affected by some uncertainties during the system evolution under the external dynamic load. The paper presents a method and a computational tool being able to provide useful information regarding the possible response of this system subjected by external harmonic loads. The results were comparatively analyzed with those obtained by the method of extremes identification of variation interval. [ABSTRACT FROM AUTHOR]

This paper deals with the transitory dynamics of the dragline bucket during the starting or stopping short periods within various stages of the regular technological cycle. It has supposed the effects of the hoist and drag cables respectively, with bucket unloaded. In addition, it has considered that the bucket has no contact with the ground, meaning this component as a pendulum system with double restricted linkage. The main goal of this research tries to reveal the overloads induced into the dragline structure, especially into the driving and the boom-anchors systems, due to the random dynamics of the bucket oscillations. Computational application has been proposed in order to dignify the correlations of some theoretical approaches with the real-world equipments behaviour. The concluding remarks present the relevant aspects of the transitory tensions inside the drag and the hoist systems with straight influences upon the whole machine system dynamics. [ABSTRACT FROM AUTHOR]

A quick modeling analysis approach for predicting the slag-steel reaction and desulfurization kinetics in argon gas-stirred ladles has been developed in this study. The model consists of two uncoupled components: (i) a computational fluid dynamics (CFD) model for predicting the fluid flow and the characteristics of slag-steel interface, and (ii) a multicomponent reaction kinetics model for calculating the desulfurization evolution. The steel-slag interfacial area and mass transfer coefficients predicted by the CFD simulation are used as the processing data for the reaction model. Since the desulfurization predictions are uncoupled from the CFD simulation, the computational time of this uncoupled predictive approach is decreased by at least 100 times for each case study when compared with the CFD-reaction kinetics fully coupled model. The uncoupled modeling approach was validated by comparing the evolution of steel and slag compositions with the experimentally measured data during ladle metallurgical furnace (LMF) processing at Nucor Steel Tuscaloosa, Inc. Then, the validated approach was applied to investigate the effects of the initial steel and slag compositions, as well as different types of additions during the refining process on the desulfurization efficiency. The results revealed that the sulfur distribution ratio and the desulfurization reaction can be promoted by making Al and CaO additions during the refining process. It was also shown that by increasing the initial Al content in liquid steel, both Al oxidation and desulfurization rates rapidly increase. In addition, it was found that the variation of the initial Si content in steel has no significant influence on the desulfurization rate. Lastly, if the initial CaO content in slag is increased or the initial Al2O3 content is decreased in the fluid-slag compositional range, the desulfurization rate can be improved significantly during the LMF process. [ABSTRACT FROM AUTHOR]

In this study, the Euler-Euler and Euler-Lagrange modeling approaches were applied to simulate the multiphase flow in the water model and gas-stirred ladle systems. Detailed comparisons of the computational and experimental results were performed to establish which approach is more accurate for predicting the gas-liquid multiphase flow phenomena. It was demonstrated that the Euler-Lagrange approach is more accurate than the Euler-Euler approach. The Euler-Lagrange approach was applied to study the effects of the free surface setup, injected bubble size, gas flow rate, and slag layer thickness on the slag-steel interaction and mass transfer behavior. Detailed discussions on the flat/non-flat free surface assumption were provided. Significant inaccuracies in the prediction of the surface fluid flow characteristics were found when the flat free surface was assumed. The variations in the main controlling parameters (bubble size, gas flow rate, and slag layer thickness) and their potential impact on the multiphase fluid flow and mass transfer characteristics (turbulent intensity, mass transfer rate, slag-steel interfacial area, flow patterns, etc.,) in gas-stirred ladles were quantitatively determined to ensure the proper increase in the ladle refining efficiency. It was revealed that by injecting finer bubbles as well as by properly increasing the gas flow rate and the slag layer thickness, the ladle refining efficiency can be enhanced significantly. [ABSTRACT FROM AUTHOR]

A full-scale, three-dimensional, transient CFD modelling approach capable of predicting the three-phase fluid-flow characteristics and desulphurisation behaviour in an argon-stirred ladle was developed. The model can accurately predict the molten steel flow and slag eye behaviour. The predicted sulphur content in ladle as a function of time agrees well with the experimental data. The effects of the initial sulphur content, the gas flow rate and the slag layer thickness on the desulphurisation efficiency were also investigated. The predicted results show that the desulphurisation efficiency improves with the increase of the initial sulphur content, the gas flow rate and the slag layer thickness. Higher gas flow rate can improve the slag-steel interaction, which, in turn, helps improving the desulphurisation rate. The thinner the slag layer, the larger the slag eyes and the smaller the interfacial area between the slag and steel phases. The consequence is the decrease in the desulphurisation rate. [ABSTRACT FROM AUTHOR]

Recent studies have showed that the microstructure and mechanical properties of A356 alloy can be significantly improved when ultrasonic cavitation and solidification processing is used. This is because during the fabrication of A356 castings, ultrasonic cavitation processing plays an important role in degassing and refining the as-cast microstructure. In the present study, A356 alloy and Al2O3/SiC nanoparticles are used as the matrix alloy and the reinforcements, respectively. Nanoparticles are injected into the molten alloy and dispersed by ultrasonic cavitation. Ultrasonic cavitation was also applied during solidification of these nanocomposites. The microstructure and nanoparticle distribution of the cast samples have been investigated in detail. The current experimental results indicated that ultrasonic cavitation during solidification will greatly improve the microstructure of the samples. Al2O3 and SiC nanoparticle reinforced nanocomposites have different nanoparticle distributions in the matrix. [ABSTRACT FROM AUTHOR]