Melting Research Papers - Academia.edu (original) (raw)

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- Environmental Science, Geochemistry, Oceanography, Heat Transfer

1] We present a new statistical method to construct a model for the chemical composition of Earth's primitive mantle along with its variance. Earth's primitive mantle is located on the melting trend exhibited by the global compilation of mantle peridotites, using cosmochemical constraints on the relative abundances of refractory lithophile elements (RLE). This so-called pyrolite approach involves the least amount of assumptions, thereby being probably most satisfactory compared to other approaches. Its previous implementations, however, suffer from questionable statistical treatment of noisy geochemical data, leaving the uncertainty of model composition poorly quantified. In order to properly take into account how scatters in peridotite data affect this geochemical inference, we combine the following statistical techniques: (1) modeling a nonlinear melting trend in the multidimensional compositional space through the principal component analysis, (2) determining the primitive mantle composition on the melting trend by simultaneously imposing all of cosmochemical constraints with least squares, and (3) mapping scatters in original data into the variance of the final model through the bootstrap resampling technique. Whereas our model is similar to previous models in terms of Mg, Si, and Fe abundances, the RLE contents are at $2.16 ± 0.37 times the CI chondrite concentration, which is lower than most of previous estimates. The new model is depleted by >20% in a number of incompatible elements including heat-producing elements, U, Th, and K, and this depleted nature is further amplified (up to 60%) in terms of predicted composition for the present-day mantle.

- by lb karki
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- Convection, Principal Component Analysis, Statistical Analysis, Theory

Phase change materials (PCMs) are classified according to their phase change process, temperature, and composition. The utilization of PCMs lies mainly in the field of solar energy and building applications as well as in industrial processes. The main advantage of such materials is the use of latent heat, which allows the storage of a large amount of thermal energy with small temperature variation, improving the energy efficiency of the system. The study of PCMs using computational fluid dynamics (CFD) is widespread and has been documented in several papers, following the tendency that CFD nowadays tends to become increasingly widespread. Numerical studies of solidification and melting processes use a combination of formulations to describe the physical phenomena related to such processes, these being mainly the latent heat and the velocity transition between the liquid and the solid phases. The methods used to describe the latent heat are divided into three main groups: source term...

Using thermal analysis as well as isothermal gravimetric measurements, the thermal stability of the zinc nitrate(V) hexahydrate has been determined. Some intermediate products are the results of melting, evaporation, hydrolysis, polycondensation and decomposition processes occurring in the saltwater system up to 300°C. Solid phases were characterized by means of chemical analyses and X-ray powder diffraction method.

- by Krystyna Wieczorek-Ciurowa
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- Water, Decomposition, Zinc, Thermal Analysis

In Turkey, pyrite, copper melting gases and sulfur are used as a raw material in sulfuric acid production. Pyrite ashes are obtained as a result of the sulfuric acid production process during the roasting of pyrite ores. These wastes are generally landfilled or dumped into the sea. Pyrite ash wastes can be utilized as a raw material in the production of iron ore, and thus environmental pollution can be avoided; however, these wastes need to achieve certain physical and chemical properties before they are used. Pyrite ashes are agglomerated into pellets to allow them acquire the required properties for use as iron ore in a blast furnace. The essential parameters affecting the pelletization of pyrite ashes are studied using bentonite as a binder. The metallurgical properties of pyrite ash, bentonite, a mixture of pyrite ash and bentonite, and sintered pellets are studied using X-ray analyses. Wet-drop, wet-crush, dry-crush and sintered-crush tests are carried out to investigate the strength of the pyrite ash wastes pellets prepared from feeds with different sieve size and bentonite content. The results of this analysis demonstrate that pyrite ashes can be agglomerated into pellets and used as feed for the blast furnace in the iron production industry.

- by Emek Derun
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- Mechanical Engineering, Chemical Engineering, Environmental Science, Production
- by Andrew Barron
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- Thin Films, Chemicals, Temperature, Deposition

Particle size distribution (PSD) and temper influences on dark chocolate fat crystallization were studied using differential scanning calorimetry (DSC) and microscopy to establish relationships with their melting properties and microstructure. Variations in PSD had no influence on crystallinity of products at all temper regimes. Particle size (PS) increases had limited effects on T onset , T peak , and DH melt independent of temper regime but significant decreases in T end and T index were noted. Contrary, varying temper regime influenced the crystallinity and melting properties (T end , T index and DH melt ) of products. Under-tempered chocolate showed widened crystal size distribution (CSD) with significant changes in T end , T index and DH melt of products. Over-tempering caused moderate increases in CSD and melting properties, with significant effect on T end , T index and DH melt but no changes were noted in T onset , T peak of products. Fat-sugar melting profiles showed similar levels in all products independent of temper regime, suggesting fat and sugar components are present in similar amounts in under-, over-and optimally-tempered products. Micrographs revealed clear crystalline network structure and well defined inter-crystal networks among tempered and over-tempered samples. Under-tempered products showed re-arrangement and re-crystallization of unstable fat crystals to smaller numbers of larger agglomerates with formation of solid bridges between the crystalline network structures. Attainment of optimal temper regime during precrystallization of dark chocolate is necessary for the achievement of premium quality products and avoidance of defects in structure and melting character.

- by Joselio Vieira
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- Chemical Engineering, Microbiology, Food, Scanning Electron Microscopy

The mathematical analysis of a one-phase Lamé-Clapeyron-Stefan problem with nonlinear thermal coefficients following [G.A. Tirskii, Two exact solutions of Stefan's nonlinear problem, Sov. Phys. Dokl. 4 (1959) 288-292] is obtained. Two related cases are considered; one of them has a temperature condition on the fixed face x = 0 and the other one has a flux condition of the type −q 0 / √ t (q 0 > 0). We obtain in both cases sufficient conditions for data in order to have the existence of an explicit solution of a similarity type which is given by using a double fixed point.

- by Domingo A . Tarzia
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- Applied Mathematics, Pure Mathematics, Multidisciplinary, Nonlinear Analysis

Résumé Dans cet article, plusieurs stratégies de fusion d'images multi-résolution P/XS basées sur le principe d'Egalisation de Statistiques Locales (ESL) sont expliquées : transformations entre espaces colorimétriques RGB-ITS et... more

- by Marc Binard
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- Geography, Statistics, Remote Sensing, Colorimetry

Object. The term “fusion rate” is generally denoted in the literature as the percentage of patients with successful fusion over a specific range of follow up. Because the time to fusion is a time-to-event phenomenon a more accurate method of representation may be made using the Kaplan—Meier method of estimation. Methods. The current study was performed to illustrate that fusion rate is more accurately represented by median times as calculated using survival analysis. Patients undergoing a cervical decompressive corpectomy and reconstruction formed the basis of the primary analysis. A secondary analysis was made to evaluate the difference in the fusion times for one- compared with multilevel corpectomy cases. Data were collected at a tertiary care institution over a 5-year period with 6-month follow up after the last recruitment. Descriptive statistics of baseline patient characteristics, the extent of disease, and the surgical intervention were obtained. Fusion was the final outcome...

- by Peng Chen
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- Surgery, Treatment, Survival Analysis, Treatment Outcome

The main purpose of this chapter is to briefly recapitulate what is learned in a first course in classical thermodynamics (Only those portions of a typical undergraduate curriculum that are relevant to combustion calculations are given emphasis). As defined in Chap. 1, thermodynamics is the science of relationships among heat, work, and the properties of the system. Our first task, therefore, will be to define the keywords in this definition: system, heat, work, and properties. The relationships among these quantities are embodied in the First and the Second laws of thermodynamics. The laws enable one to evaluate the change in the states of the system, as identified by the changes in its properties. In thermodynamics, this change is called a process, although, in common everyday language, the processes maybe identified with terms such as cooling, heating, expansion, compression, phase change (melting, solidification, evaporation, condensation), or chemical reaction (such as combustion, catalysis, etc.). As such, it is important to define two additional terms: state and process.

- by anil date
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- Aerospace Engineering, Law, Universe, Ideal Gas

Snow hydrology is a specialized field of hydrology that is of particular importance for high latitudes and mountainous terrain. In many parts of the world, river and groundwater supplies for domestic, irrigation, industrial, and ecosystem needs are generated from snowmelt, and an in-depth understanding of snow hydrology is of clear importance. Study of the impacts of global warming has also stimulated interest in snow hydrology because increased air temperatures are projected to have major impacts on the snow hydrology of cold regions.

- by David DeWalle
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- Remote Sensing, Image Analysis, Land Use, Forests

1] Imaging spectroscopy is a tool that can be used to spectrally identify and spatially map materials based on their specific chemical bonds. Spectroscopic analysis requires significantly more sophistication than has been employed in conventional broadband remote sensing analysis. We describe a new system that is effective at material identification and mapping: a set of algorithms within an expert system decision-making framework that we call Tetracorder. The expertise in the system has been derived from scientific knowledge of spectral identification. The expert system rules are implemented in a decision tree where multiple algorithms are applied to spectral analysis, additional expert rules and algorithms can be applied based on initial results, and more decisions are made until spectral analysis is complete. Because certain spectral features are indicative of specific chemical bonds in materials, the system can accurately identify and map those materials. In this paper we describe the framework of the decision making process used for spectral identification, describe specific spectral feature analysis algorithms, and give examples of what analyses and types of maps are possible with imaging spectroscopy data. We also present the expert system rules that describe which diagnostic spectral features are used in the decision making process for a set of spectra of minerals and other common materials. We demonstrate the applications of Tetracorder to identify and map surface minerals, to detect sources of acid rock drainage, and to map vegetation species, ice, melting snow, water, and water pollution, all with one set of expert system rules. Mineral mapping can aid in geologic mapping and fault detection and can provide a better understanding of weathering, mineralization, hydrothermal alteration, and other geologic processes. Environmental site assessment, such as mapping source areas of acid mine drainage, has resulted in the acceleration of site cleanup, saving millions of dollars and years in cleanup time. Imaging spectroscopy data and Tetracorder analysis can be used to study both terrestrial and planetary science problems. Imaging spectroscopy can be used to probe planetary systems, including their atmospheres, oceans, and land surfaces. Imaging spectroscopy: Earth and planetary remote sensing with the USGS Tetracorder and expert systems,

- by R. McDougal
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- Algorithms, Expert Systems, Remote Sensing, Spectroscopy

Expanded graphite is a promising heat transfer promoter due to its high conductivity, which improves the thermal conductivity of organic phase change materials. Moreover, it can also serve as supporting materials to keep the shape of the blends stable during the phase transition. After various investigation, the results showed that the maximum weight percentage of polyethylene glycol was as high as 90% in this paper without any leakage during the melting period, with the latent heat of 161.2 J g À1 and the melting point of 61.46°C. It was found that the value of the latent heat was related to the polyethylene glycol portion, increased with the increase in polyethylene glycol content. Moreover, the measured enthalpy of the composite phase change materials was proportional to the mass ratio of the polyethylene glycol component. The melting temperatures were almost the same with different ratios of composites. The conductivity of blends was improved significantly with the high value of 1.324 W m À1 K À1 compared to the pure polyethylene glycol conductivity of 0.2985 W m À1 K À1 .

- by Memet Kahraman
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- Engineering, Materials Engineering, Economics, Heat Transfer

The textural, melting and sensory properties of low-fat fresh kashar cheeses (B70% fat reduction) produced by using two proteinbased fat replacers (1.0% w/w Simplesse s D-100 and 1.0% w/w Dairy-Lot) and one carbohydrate-based fat replacer (5.0% w/w Raftiline s HP) were examined during the storage period for 90 days. The low-fat cheese without fat replacer and the full-fat cheese were also produced, for comparison.

- by Nurcan KOCA
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- Fusion, Dairy, Texture, Clinical Sciences

The melting of ice and the subsequent production of regelation ice from the melt water in a large-scale closed system beneath sub-polar and polar glaciers produces progressive fractionation between the melt water and the regelation ice derived from it. A theory is developed which predicts the change of isotopic composition in regelation ice in a subglacial zone of freezing and in the water from which it is derived. The theory is tested against data from the Byrd Station bore hole in West Antarctica, and applied to explain features of the isotopic composition in several other glaciers where thick sequences of regelation ice have formed. The principal conclusions are: 1. Basal isotopic profiles can be used to reconstruct important features of a glacier’s hydrological system. 2. Isotopic profiles in basal regelation ice do not simply reflect isotopic characteristics of ancient atmospheres but also, by using the theory, some of the isotopic characteristics of the normal glacier ice whic...

- by Ulrich Spring
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- Glaciology, Fusion, Glacier, Melting

When the latent heat of a phase change material (PCM) with a lower melting point than ambient temperature was assessed according to the standard T-history method using a vertically oriented test tube, a temperature gradient occurred in the longitudinal direction of the tube due to natural convection. This led to a decrease in the accuracy of the latent heat of fusion measurement. In this study, the accuracy of the measurement with the original T-history method was improved without decreasing the test's simplicity and convenience by setting the test tube horizontally. The heat transfer to the vapor-layer of the tube under volume change during melting was assumed to be negligible and the results were calculated using the two inflection points of temperature as the start and end of latent heat period. Under these assumptions, the results agree closely with other reference data. And, the new method proposed in this study showed a remarkable reduction in data scattering.

- by Chaedong Kang
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- Engineering, History, Materials Science, Refrigeration

In the present work, the interactions between double-stranded (ds) or single-stranded (ss) DNA and nonionic ethylene oxide (EO) surfactants, with special attention to the possible contributions from hydrophobic interactions, have been investigated using a multitechnique approach. It was found that the presence of ss as well as dsDNA induces a slight decrease of the cloud point of pentaethylene glycol monododecyl ether (C 12 E 5 ). Assessment of the partitioning of DNA between the surfactant-rich and surfactant-poor phases formed above the cloud point showed that the polymer was preferably located in the surfactant-poor phase. Surface tensiometry experiments revealed that neither of the DNA forms induced surfactant micellization. Finally, it was shown by DNA melting measurements that another EO surfactant (C 12 E 8 ) did not affect the relative stabilities of ss and dsDNA. To summarize, all experiments suggest that the net interaction between DNA and nonionic surfactants of the EO type is weakly repulsive, which can be attributed mainly to steric effects. In general, the results were practically identical for the ds and ss forms of DNA, except those from the cloud point experiments, where the decrease of the cloud point was less pronounced with ssDNA. This finding indicates the presence of an attractive component in the interaction, which can reasonably be ascribed to hydrophobic effects.

- by Björn Lindman
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- Stability, Multidisciplinary, DNA, Fusion

Binary NiTi based shape memory alloys can be produced starting from the pure elements (Ni-pellets, Ti-rods) by using vacuum induction melting (VIM). VIM ingot metallurgy is known to produce materials with a good chemical homogeneity; it, moreover, is cheaper than vacuum arc melting (VAM) when small quantities of laboratory materials are needed. In a VIM procedure, graphite crucibles are attractive because they have appropriate electrical properties. For NiTi melting, graphite crucibles are interesting because they are reasonably priced and they show a good resistance against thermal cracking. On the other hand, it is well known that melting of Ti alloys in graphite crucibles is associated with a vigorous interface reaction. And the carbon concentration of NiTi alloys needs to be kept below a certain minimum in order to assure that the functional properties of the alloys meet the required targets. Therefore, it is important to minimize the carbon pick up of the melt. The present work presents experimental results and discusses thermodynamic and kinetic aspects of the reaction of NiTi melts with graphite crucibles; a method is suggested to keep the carbon dissolution into the melt at a minimum.

- by G. Eggeler
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- Materials Engineering, Condensed Matter Physics, Thermodynamics, Kinetics

Oat b-glucans were extracted (water at 47 8C) from milled seeds of two Greek cultivars (A. sativa cv. Pallini and A. bysantina cv. Kassandra) and partially purified by pH adjustment of the b-glucan solutions to 4.5. Chemical analysis of the extracted gums revealed that they were composed mainly of b-glucans (. 85% d.b.) together with some contaminating proteins (, 9% d.b.). The fine structure of the b-glucan preparations was assessed by 13 C-NMR spectroscopy and high-performance anion-exchange chromatography of the cellulosic oligomers released by the action of lichenase. The tri-and tetra-saccharides accounted for 90.9 -92.3% of the total oligomers analyzed and the calculated molar ratios of trimers/tetramers varied between 1.99 -2.11. Molecular size characterization was carried out with high performance size exclusion chromatography combined with a multi-angle laser light scattering and a refractive index detector; for samples with weight average molecular weight (M w ) ranging between 0.27 and 0.78 £ 10 6 , the values of limiting viscosity ([h ]), critical concentration (c**) and coil overlap parameter (c**[h ]) were within 4.9-6.4 dl/g, 1.2-2.0 g/dl and 7.8 -10.1, respectively. The shear thinning behavior was dependent on the molecular weight and concentration of the b-glucan preparations. All b-glucan samples were able to form gels, as revealed by dynamic rheometry; the low molecular weight samples exhibited shorter gelation times and higher gelation rates (I E ¼ [dlog G 0 /dt ] max ) than their high molecular weight counterparts. The gelation rate increased with increasing concentration and gel curing temperatures reaching a maximum at 32 8C; for higher temperatures the I E values decreased. For small molecular size b-glucans, a biphasic melting behavior was observed for gels at curing temperatures of 2 -32 8C, whereas at higher temperatures melting of the gel network occurred as one-step process. Differential scanning calorimetry showed that gels cured at 24 8C exhibit a broad melting transition; Tm , 63 8C and DH , 5 mJ/mg. The mechanical properties of casted (dispersions) films from two b-glucan preparations, differing in molecular weight, with or without sorbitol, were examined by tensile measurements. The large deformation mechanical tests showed decreases in tensile (Young's) modulus (E) and strength (s max ), and an increase in percentage elongation with increasing water content and/or addition of sorbitol. The relationships between tensile parameters (E and s max ) and water content showed an increase in stiffness of the films from 2 -7% moisture, and a strong softening effect at higher water contents. q

- by Costas Biliaderis
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- Engineering, Structure, NMR Spectroscopy, Structural Analysis
- by Pengfu Tan
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- Chemical Engineering, Modeling, Gibbs Free Energy, Smelting

Laser beam machining (LBM) is one of the most widely used thermal energy based non-contact type advance machining process which can be applied for almost whole range of materials. Laser beam is focussed for melting and vaporizing the unwanted material from the parent material. It is suitable for geometrically complex profile cutting and making miniature holes in sheetmetal. Among various type of lasers used for machining in industries, CO 2 and Nd:YAG lasers are most established. In recent years, researchers have explored a number of ways to improve the LBM process performance by analysing the different factors that affect the quality characteristics. The experimental and theoretical studies show that process performance can be improved considerably by proper selection of laser parameters, material parameters and operating parameters. This paper reviews the research work carried out so far in the area of LBM of different materials and shapes. It reports about the experimental and theoretical studies of LBM to improve the process performance. Several modelling and optimization techniques for the determination of optimum laser beam cutting condition have been critically examined. The last part of this paper discusses the LBM developments and outlines the trend for future research.

- by Vinod Yadava
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- Computer Science, Modeling, Optimization, Machine Tools

Urea has a listed melting range of 132.5°C-133°C and trans-cinnamic acid has a listed melting range of 132.5°C-133°C. Experimental results for urea resulted in a range of 132.8°C-133.1°C. Experimental results for transcinnamic acid resulted in a range of 132.8°C-133.4°C. The initial results confirmed proper calibration of the melt station with listed values. Contamination samples consisting of 1:4, 1:1, and 4:1 ratio of urea and trans-cinnamic acid respectively were prepared with their mass measured in hundredths of grams. Observations were made regarding the initial melting point of each sample as well as the full melting point where all of the substance had dissolved. Solution with 1:4 ratio had a range of 104.5°C-114.6°C. Solution with a 1:1 ratio had a range of 103°C-109.4°C. Solution with a 4:1 ratio had a range of 113.5°C-126.9°C. The experimentally derived initial melting point, complete melting point, and melting range of the contaminated samples were at a lower temperature and larger range than the pure samples of urea and trans-cinnamic acid. Based on these data it can be inferred that if a substance is contaminated from its pure state the Siavosh Naji-Talakar Lab Report 1 9-3-15 melting point is reduced and the substance has a much larger temperature range from which it initially melts to when it is completely melted. Using this information an unknown sample labeled 'B5' was tested and the melting range was 81.3°C-83.7°C. Using this information and conferring with listed values from Table 3.2 in Macroscale and Microscale Organic Experiments (6e)

- by Siavosh Naji-Talakar
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- Melting

Water scarcity is now acting as an enormous problem threaten the human-beings and whole the world. In addition, it leads to world climate changes and drought. So, now all work is going to the way of perfect using of all water supplies and finding new ways to desalinate the salty-water. This project depends on freezing the seawater into pure water and the salt is get in the ice crystals form, which permits easy separation of pure water, then melt it into liquid form and then get into suitable drinking water.
This method’s advantage is the less fuel power consumptions as in evaporation desalination process which decreases the piping leakages.
This method can be integrated with AC systems to take the advantage from the ice formed in the purpose of conditioning, or as a thermal storage that can be used later.
The model is taking place in underground water applications with various salt concentrations.
This project include the designing of tanks, ice scrappers, and washing and melting systems, and then collecting the pure fresh water induced. And also contains the designing of heat exchangers and freezing systems.

- by Mostafa Atwa
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- Mechanical Engineering, Water quality, Water resources, Energy
- by Anthony Bruce Murphy
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- Computational Modeling, Welding, Plasmas, Melting

The melting behaviour of poly(aryl-ether-ether-ketone) (PEEK) was investigated using Fourier transform infra-red (F Ti.r.) spectroscopy and differential scanning calorimetry (d.s.c.) as part of a study of a carbon fibre reinforced PEEK composite. Digital spectral subtraction was utilized to derive the characteristic spectra of the amorphous and crystalline phases of the polymer. Local order in the amorphous phase of PEEK was observed when the polymer was melted below its equilibrium melting temperature (T* = 395°C). The local order is associated with the diphenyl ether moiety. Molecular segments in the ordered regions may assume different orientations on the surface of potassium bromide salt crystals, depending upon whether PEEK is processed at 380°C or 400°C. Molecular analysis by FTi.r. correlates well with data obtained by d.s.c.

- by Huyen Nguyen
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- Engineering, Polymer, CHEMICAL SCIENCES, Thermal Analysis

La presente investigación tuvo como objetivo determinar la masa molar de crudos por crioscopía; para ello se realizaron pruebas de laboratorio midiendo la temperatura de fusión de mezclas con un diseño factorial de 2x3 para cada uno de los solventes utilizados, los factores son respectivamente crudos y proporciones de solvente - crudo. El marco teórico contiene conceptos básicos para la comprensión de la investigación, resume las propiedades coligativas de soluciones no conductivas enfatizando en el principio aplicado (disminución del punto de fusión), y presentando el estado del arte del mismo; también exhibe una reseña de algunas propiedades y métodos para caracterizar crudos, incluyendo los utilizados para obtener la masa molar. En la metodología se exponen los criterios y el proceso de selección de 1) los ocho solventes más propicios para las pruebas desarrolladas, partiendo de un listado de novecientos once; 2) la proporción de solvente y crudo; 3) el montaje; 4) volumen de muestra y pruebas previas; 5) diseño experimental y análisis estadístico; y 6) el procedimiento crioscópico. Los resultados fueron comparados con determinaciones de vapor osmótica y algunas correlaciones; además, se identificaron afinidades entre crudos y solventes. No se logró determinar las masas molares de los crudos. En dos de los cuatro ANVA realizados se observó variación de la masa molar en función de la cantidad de solvente, por lo que se cuestiona la idealidad de las soluciones, además si las concentraciones son las adecuadas para el método. Los otros dos ANVA sevieron influenciados por el error estadístico tipo II, ocasionado por dos casos aberrantes.
En cuanto a la concordancia, el 50% de las mediciones presentaron diferencias menores a 20 g/gn entre réplicas, se obtuvieron concordancias aceptables y perfectas con el coeficientes de Kendall; tres ANVA presentaron coeficientes de correlación intraclase superiores al 70%, el cuarto alcanzó un 44%. Se presentaron recomendaciones para optimizar y evaluar esta metodología. Se obtuvo un protocolo para el desarrollo de las pruebas crioscópicas que se presenta como anexo.

- by DARWIN SMITH VASQUEZ MENDOZA
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- Protocols, ANOVA, Colligative Properties, Fusion
- by Martin Sommerkorn
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- Climate Change, Global Warming, Weather, Climatic Change

In recent years the Steel Rolling Mills have undergone a significant change regarding quality requirements, productivity and the thickness of the products being rolled. The Hot Strip Mills have emerged with higher productivity, excellent surface finish of coils with thinner gauge rolling. Stringent dimensional tolerance, strip finish and profile flatness requirements and higher mill productivity have called for improved wear resistance and fatigue crack resistance of the rolls used in the finishing stands. For the finishing stands of hot strip mills Duplex ICDP and ICDP-EC rolls are nowadays produced through either Vertical Centrifugal Casting (VCC) or Horizontal Centrifugal Casting (HCC) process. These duplex rolls generally consist of a Shell made of alloy cast iron and the Core made of spheroidal graphitic Iron. It has been observed that the Performance of the imported ICDP-EC Rolls manufactured by the Market leaders far superseded the Performance of the indigenous rolls due to higher wear and fatigue crack resistance of the imported rolls. Use of the imported rolls also improved the surface quality of products rolled and improved the campaign life of the rolls. A study of few Imported and Indigenous rolls was carried out to find out the deficiencies of the Indigenous Rolls in comparison to the Imported Rolls manufactured by the market leaders. In this paper the chemical compositions and microstructure of the imported rolls have been benchmarked with those of the indigenous rolls. The morphology and content of

- by Mausumi Kar
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- Casting, Forging, Melting, Rolling

In this study, the latent heat thermal energy storage system of the shell-and-tube type is analyzed experimentally. A novel design for the storage unit whose geometry is consistent with the melting/solidification characteristics of phase change materials (PCMs) is introduced. Three kinds of paraffin with different melting temperatures are used as PCMs. Water is used as the heat transfer fluid (HTF). At first, the thermophysical properties of the paraffins used are determined through the differential scanning calorimeter (DSC) analysis. The effects of the Reynolds number and the Stefan number on the melting and solidification behaviors are determined. It is disclosed the novel tube-in-shell storage geometry introduced in this study suggests promising results.

- by Kamil Kaygusuz
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- Mechanical Engineering, Performance, Geometry, Differential scanning calorimetry

The present work demonstrates that friction stir welding (FSW) is a feasible route for joining 6061 aluminium (Al) alloy to AISI 1018 steel. The weld has a good weld quality and is free of cracks and porosity. The tensile failure happened at the boundary between the nugget and thermomechanically affected zone of the base Al alloy, indicating that the weld has a higher joining strength. Despite the fact that the hardness fluctuates strongly within the nugget, the average hardness of the nugget is substantially higher than that of the base Al alloy. During FSW, localized melting of the Al alloy in the nugget occurred, and the molten Al alloy reacted strongly with steel pieces spread through the nugget, which resulted in the formation of the Al-Fe intermetallic compounds, Al 13 Fe 4 and Al 5 Fe 2 . The nugget consists of secondary phases including coarse steel pieces and Al-Fe intermetallic compounds, and an Al alloy matrix. These secondary phases contribute to the hardness of the weld.

- by Radovan Kovacevic
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- Mechanical Engineering, Feasibility Study, Friction Welding, Porosity

The charge for silicomangansese production consists of manganese ore (often mixed with ferromanganese slag) dolomite or calcite, quartz, and in some cases, other additions. These materials have different melting properties, which have a strong effect on reduction and smelting reactions in the production of a silicomanganese alloy. This article discusses properties of Assman, Gabonese, and Companhia Vale do Rio Doce (CVRD) ores, CVRD sinter and highcarbon ferromanganese (HC FeMn) slag, and their change during silicomanganese production. The melting and reduction temperatures of these manganese sources were measured in a carbon monoxide atmosphere, using the sessile drop method and a differential thermal analysis/ thermogravimetric analysis. Equilibrium phases were analyzed using FACTSage (CRCT, Montreal, Canada and GTT, Aachen, Germany) software. Experimental investigations and an analysis of equilibrium phases revealed significant differences in the melting behavior and reduction of different manganese sources. The difference in smelting of CVRD ore and CVRD sinter was attributed to a faster reduction of sinter by the graphite substrate and carbon monoxide. The calculation of equilibrium phases in the reduction process of manganese ores using FACTSage correctly reflects the trends in the production of manganese alloys. The temperature at which the manganese oxide concentration in the slag was reduced below 10 wt pct can be assigned to the top of the coke bed in the silicomanganese furnace. This temperature was in the range 1823 K to 1883 K (1550°C to 1610°C).

- by Merete Tangstad and +1
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- Chemical Engineering, Fusion, Melting, Differential Thermal Analysis

This paper is concerned with the systems aspects of the Solid Free- form Fabrication (SFF) technology, i.e., the issues that deal with getting an external geometric CAD model to automatically control the physical layering fabrication process as directly as possible, regardless of the source of the model. The general systems issues are described, the state of systems research is given, and open research questions are posed.

- by Joseph Beaman
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- Computer Aided Design, Control, Composite Materials, Models

A numerical investigation is adopted for a two dimensional thermal energy storage system (TES), employing finite element method to compute the time of charging or discharging energy from a phase change material (PCM) during day or night to utilize it in free cooling of space applying Baghdad Summer climate conditions (ambient temperature). A computer program is developed to analyze the thermal energy unit for different tube diameters, air flow rates and inlet air temperature for both solidification and melting processes. This study shows that utilizing small tube diameter, low flow rates or air inlet temperature near the fusion temperature lead to increase time of phase change process. It was also shown that the time duration of melting is larger than solidification.

- by Karima a
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- Mechanical Engineering, Renewable Energy, Heat Transfer, FEM

The effect of organo-modified clay (Cloisite 93A) on the crystal structure and isothermal crystallization behavior of isotactic polypropylene (iPP) in iPP/clay nanocomposites prepared by latex technology was investigated by wide angle X-ray diffraction, differential scanning calorimetry and polarized optical microscopy. The X-ray diffraction results indicated that the higher clay loading promotes the formation of the β-phase crystallites, as evidenced by the appearance of a new peak corresponding to the (300) reflection of β-iPP. Analysis of the isothermal crystallization showed that the PP nanocomposite (1% C93A) exhibited higher crystallization rates than the neat PP. The unfilled iPP matrix and nanocomposites clearly shows double melting behavior; the shape of the melting transition progressively changes toward single melting with increasing crystallization temperature. The fold surface free energy (σe) of polymer chains in the nanocomposites was lower than that in the PP latex (PPL). It should be reasonable to treat C93A as a good nucleating agent for the crystallization of PPL, which plays a determinant effect on the reduction in σe during the isothermal crystallization of the nanocomposites. The activation energy, ΔEa, decreased with the incorporation of clay nanoparticles into the matrix, which in turn indicates that the nucleation process is facilitated by the presence of clay. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1927–1938, 2010

- by Luljeta Raka
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- Engineering, Materials Engineering, Composites, Kinetics

We present a review of experimental, theoretical, and molecular simulation studies of confinement effects on freezing and melting. We consider both simple and more complex adsorbates that are confined in various environments (slit or cylindrical pores and also disordered porous materials). The most commonly used molecular simulation, theoretical and experimental methods are first presented. We also provide a brief description of the most widely used porous materials. The current state of knowledge on the effects of confinement on structure and freezing temperature, and the appearance of new surfacedriven and confinement-driven phases are then discussed. We also address how confinement affects the glass transition.

In this paper, the melting process inside an irregular geometry filled with high thermal conductivity porous matrix saturated with phase change material PCM is investigated numerically. The numerical model is resting on solving the volume averaged conservation equations for mass, momentum and energy with phase change (melting) in the porous medium. The convection motion of the liquid phase inside the porous matrix is solved considering the Darcy, Brinkman and Forchiemer effects. A local thermal non-equilibrium assumption is considered due to the large difference in thermal properties between the solid matrix and PCM by applying a two energy equation model. The numerical code shows good agreement for pure PCM melting with another published numerical work. Through this study it is found that the presence of the porous matrix has a great effect on the heat transfer and melting rate of the PCM energy storage. Decreasing the porosity of the matrix increases the melting rate, but it also damps the convection motion. It is also found that the best technique to enhance the response of the PCM storage is to use a solid matrix with high porosity and high thermal conductivity.

- by Osama Mesalhy and +1
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- Heat Transfer, Energy Conversion, Phase Change, Phase Change Material

The sunflower seed waxes obtained from two sources (i) seed hull as astandard and (ii) crude wax from oil refineries were studied for theircrystallization, melting characteristics and morphology of crystals. Theresults of differential scanning calorimetry of wax obtained from seed hullsshowed the melting temperature range of 13.18 °C with the onsetat 62.32 °C, for purified wax, compared to the melting range of24.73 °C with the onset at 42.3 °C, for crude wax. Theenthalpy of fusion for both waxes were 57.55 mcal/mg and 7.63 mcal/mg,respectively. The DSC melt crystallization temperature range was15.79 °C with the onset of 64.58 °C for purified wax andtemperature range of 31.45 °C with an onset of 57.76 °C forcrude wax. A similar pattern was observed of wax obtained from thecrude wax of oil refineries. The enthalpy of crystallization was –64.27mcal/mg and –7.67 mcal/mg, respectively. The purified wax obtained fromthe two sources (i) and (ii) were comparable with completion temperaturesof 75.5 °C and 75.1 °C, respectively. The effect of inhibitor(lecithin) on crystallization of purified wax under light microscope andsurface structure by scanning electron microscope were observed. Lecithinat 0.2% inhibited the crystallization but nucleation was unaltered. Thewax crystal was inhibited to around 60% of the original size with 0.2%lecithin. It is concluded that the sunflower waxes studied were notcomparable in their crystal properties of crude and purified states.Lecithin inhibited the crystallization of sunflower seed wax.

An experimental investigation of ice formation on cold vertical banks of horizontal tubes subjected to falling-film-jet mode-is conducted. In the charging process, a set of internally cooled vertical banks of horizontal tubes of brine is subjected to a falling film of water. The formed ice is periodically observed, photographed and measured in falling-film jet mode at specific internal coolant (ethylene-glycol solution) flow rates and temperatures. In the discharge process, the same solution is heated and used internally to release ice. Different thicknesses of the released ice are observed and measured. The maximum quantity of released ice is obtained and the optimum ice formation is determined. The results indicate that the ice formation and the solid ice released are controlled by the thermal resistance of the ice, time and pitch between tubes. The maximum gained ice has a thickness that is approximately equal to half of the tube spacing between the tubes utilized, which is formed in approximately 45 min and released in 12.5 min. The variation in heating solution temperature has a slight effect on the gained ice and discharging time.

- by Hani Sait
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- Melting, Electrical And Electronic Engineering

In this study, boron doped and undoped poly(vinyl) alcohol/zirconium-barium acetate (PVA/Zr-Ba) nanofibers were prepared using an electrospinning technique then calcinated at three different temperatures; 250 oC, 500 oC, 800 oC for 2 h. The
originality of this study is the addition of boron to metal acetates. The fibers were characterized by FT-IR, DSC, XRD and SEM. The addition of boron did not only increase the thermal stability of the fibers, but also increased their diameters, which gave stronger fibers. The FT-IR spectra of the fibers were in good accordance with literature data. The DSC results indicate that the glass transition (Tg) and melting temperatures (Tm) showed a change with the addition of boron. Also, boron doped fibers were observed to degrade at higher temperatures. XRD analyses showed that after further heat treatment at 800 oC, zirconia exists in two phases of tetragonal and monoclinic modifications. The systematic evolution of morphological features in the spun and the processed fibers were studied by scanning electron microscopy. The SEM appearance of the fibers showed
that the addition of boron resulted in the formation of cross linked bright surfaced fibers.

Recycled bottle-grade poly(ethylene terephthalate), PET, can be mixed with virgin resin in different concentrations to be used by the food packaging industry. This will contribute to the growth of mechanical recycling of PET, but it is important to have an experimental method to detect the presence of recycled polymer in a batch. Differential scanning calorimetry was used to study the influences of the presence of post-consumption bottlegrade PET and of thermo-mechanical processing on the thermal properties of bottle-grade PET. When the virgin resin is subjected to thermo-mechanical processing (pre-forms, softdrink bottles production, recycling or PET mixtures preparation), the crystallization rate is affected and a clearly defined crystallization peak, T c , is observed. A bimodal melting temperature, T m , behavior is observed for samples that were subjected to processing. When post-consumption PET is present in the mixtures, the T m bimodal behavior is followed by a narrowing and a shift of the T c to higher temperatures. Therefore, the crystallization rate, T m and T c are the principal thermal properties that can be used to distinguish between virgin and post-consumption resins submitted to thermo-mechanical processing.

- by Marco Aurelio De Paoli
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- Materials Engineering, Mechanical Engineering, Recycling, Polymer Blends

The freshwater flux from the Greenland Ice Sheet (GrIS) to the ocean is of considerable importance to the global eustatic sea level rise. A physical modelling approach using SnowModel, a state-of-the-art snow-evolution modelling system that includes four submodels (MicroMet, EnBal, SnowPack,, was used to quantify the 1995-2007 GrIS surface massbalance (SMB), including freshwater flux. Meteorological observations from 26 meteorological stations located on the GrIS (Greenland Climate Network; GC-Net stations) and in coastal Greenland (Danish Meteorological Institute (DMI) WMOstations) were used as model inputs. The GrIS minimum surface melt extent of 29% occurred in 1996, while the greatest extent of 51% was present in 2007. The 2007 melt extent was 20% greater than the average for 1995-2006. The year 2007 had the highest GrIS surface runoff (523 km 3 y 1 ) and the lowest SMB ( 3 km 3 y 1 ); the only year with a negative GrIS SMB. Runoff in 2007 was approximately 35% greater than average for 1995-2006. From 1995 through 2007 overall,

- by Sebastian Mernild
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- Environmental Engineering, Civil Engineering, Climate, Sea Level