Home About us Contact
|
Home About us Contact | ||
|
|
||
Melting Process (melting + process)
Selected AbstractsFabrication of Fe,Cr,Al Oxide Dispersion Strengthened PM2000 Alloy Using Selective Laser Melting,ADVANCED ENGINEERING MATERIALS, Issue 7 2009John C. Walker Rapid prototyping using the selective laser melting process has been successfully used in the manufacture of solid walls from melt sensitive mechanically alloyed PM2000 FeCrAl ODS powder. Despite melting of the powder, the technique allowed the retention of the nanoscale oxide dispersion due to the high cooling rates. Results showed that coarsening and agglomeration of ODS particles was more dependent on laser scan speed than the maximum laser power. [source] On the compensation of non-active current components of three-phase loads with quickly changing unsymmetryEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2001V. Staudt Some types of loads, like arc furnaces, present a special challenge to compensation strategies. They vary quickly and have a very high rated power. For example the arcs of an arc furnace are not burning continuously especially when starting the melting process. This causes variations of the line voltage with frequencies well below the line frequency commonly known as voltage flicker. Because of cost efficiency the energy storage capability of compensators for the mitigation of voltage flicker effects can still only be small compared to the energy taken by the arc furnace during one period of the line voltage. This paper discusses the use of a compensation tool which quickly detects negative sequence current components in comparison to the calculation of an equivalent conductance using the so-called FBD method (Fryze-Buchholz-Depenbrock method). Simulations are used to demonstrate the advantages and disadvantages of the tool for detecting negative sequence current components. It is shown that the quick detection and compensation of negative sequence current components can reduce the amount of voltage flicker considerably. [source] Melting of a vertical ice cylinder inside a rotating cylindrical cavity filled with binary aqueous solutionHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2008Yoshimi Komatsu Abstract The melting of a vertical ice cylinder into a homogeneous calcium chloride aqueous solution inside a rotating cylindrical cavity with several rotating speeds is considered experimentally. The melting mass and temperature are measured on four initial conditions of the solution and four rotating speeds of the cavity. The temperature of the liquid layer becomes uniform by the mixing effect resulting from cavity rotation and it enhances the melting rate of the ice cylinder. As the cavity-rotating speed increases, the melting rate increases. The dimensionless melting mass is related to the Fourier number and the rotating Reynolds number in each initial condition, therefore an experimental equation that is able to quantitatively calculate the dimensionless melting mass is presented. It is seen that the melting Nusselt numbers increase again in the middle of the melting process. The ice cylinder continues to melt in spite of the small temperature difference between the ice cylinder and the solution. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(6): 359,373, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20211 [source] Molecular Dynamics of Podand Studied by Broadband Dielectric and Nuclear Magnetic Resonance Spectroscopies,,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 19-20 2007Bakyt Orozbaev Abstract Nuclear magnetic resonance (NMR) and broadband dielectric spectroscopies (BDS) were used to analyze the molecular dynamics in P10.3H Podand. The temperature studies of NMR line and magnetic spin,lattice relaxation times accompanied by DS investigation enabled us to distinguish three main dynamical processes connected with the motions of the P10.3H Podand chains. In the low-temperature region the magnetic relaxation was associated with fast axial C3 rotation of methyl groups. Moreover, two other independent processes were observed and interpreted as (i) segmental motion of both oxyethylene and ethylene units, and (ii) the overall motion involved in the melting process. [source] DETECTING FORGERIES AMONG ANCIENT GOLD OBJECTS USING THE U,Th,4He DATING METHOD,ARCHAEOMETRY, Issue 4 2009O. EUGSTER Forgeries of ancient gold objects are prevalent in almost every collection and some public exhibitions in the past have been exposed as containing forgeries to an embarrassing extent. This situation comes from the fact that it is sometimes impossible to unequivocally recognize forgeries based on their patina or manufacturing and decoration characteristics. We demonstrate that for 13 ancient gold objects the time of their last melting process can be estimated using the U,Th,4He dating technique. The extremely small quantities of radiogenic 4He found, due to the young age and small sample size, require the use of a specially designed ultrasensitive mass spectrometer. We show that the proposed method is a powerful, and the only, quantitative tool in archaeometry for discriminating between fake and genuine ancient gold objects. [source] Enthalpy/Entropy Compensation in the Melting of Thermotropic Nitrogen-Containing Chelating Ligands and Their Lanthanide Complexes: Successes and Failures,,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2010Aude Escande Abstract In this short overview dedicated to the thermodynamics of liquid crystalline chelating nitrogen-containing ligands and their lanthanide complexes (i.e., lanthanidomesogens), we first go through the initial successes obtained with the introduction of the concept of enthalpy/entropy compensation for rationalizing and programming melting and clearing temperatures in thermotropic mesophases. In the second part, the failures encountered during our attempts for switching from a qualitative toward a quantitative interpretation of the melting processes in polycatenar lanthanidomesogens are discussed, together with the delicate correlations established between the thermodynamic parameters of intermolecular cohesion measured in noncoordinating solvents and those operating in pure mesophases. [source] A geochronological approach to understanding the role of solar activity on Holocene glacier length variability in the Swiss AlpsGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 4 2006Anne Hormes ABSTRACT. We present a radiocarbon data set of 71 samples of wood and peat material that melted out or sheared out from underneath eight presentday mid-latitude glaciers in the Central Swiss Alps. Results indicated that in the past several glaciers have been repeatedly less extensive than they were in the 1990s. The periods when glaciers had a smaller volume and shorter length persisted between 320 and 2500 years. This data set provides greater insight into glacier variability than previously possible, especially for the early and middle Holocene. The radiocarbon-dated periods defined with less extensive glaciers coincide with periods of reduced radio-production, pointing to a connection between solar activity and glacier melting processes. Measured long-term series of glacier length variations show significant correlation with the total solar irradiance. Incoming solar irradiance and changing albedo can account for a direct forcing of the glacier mass balances. Long-term investigations of atmospheric processes that are in interaction with changing solar activity are needed in order to understand the feedback mechanisms with glacier mass balances. [source] Experimental study and analysis of the application of ice-storage capsules in an air conditioning systemHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2002Shuiquan Ye Abstract Ice-storage capsules are used in an energy-efficient air conditioning system. Experiments and numerical simulations were conducted to investigate the effects of different structural configurations of the capsules on the freezing and melting processes of the refrigerant solution sealed inside the capsules. The predictions of the numerical simulation are in good agreement with the test results. The results show that the freezing speed of the capsules equipped with a metal core is 30% to 50% faster than for capsules without the metal core. In addition, it was found that the special refrigerant solution used in the experiment had a lower freezing point and a higher freezing speed than water. The effects of the size of the metal core, and the coolant temperatures are also investigated. © 2001 Scripta Technica, Heat Trans Asian Res, 31(1): 21,27, 2002 [source] Assessment of climate-change impacts on alpine discharge regimes with climate model uncertaintyHYDROLOGICAL PROCESSES, Issue 10 2006Pascal Horton Abstract This study analyses the uncertainty induced by the use of different state-of-the-art climate models on the prediction of climate-change impacts on the runoff regimes of 11 mountainous catchments in the Swiss Alps having current proportions of glacier cover between 0 and 50%. The climate-change scenarios analysed are the result of 19 regional climate model (RCM) runs obtained for the period 2070,2099 based on two different greenhouse-gas emission scenarios (the A2 and B2 scenarios defined by the Intergovernmental Panel on Climate Change) and on three different coupled atmosphere-ocean general circulation models (AOGCMs), namely HadCM3, ECHAM4/OPYC3 and ARPEGE/OPA. The hydrological response of the study catchments to the climate scenarios is simulated through a conceptual reservoir-based precipitation-runoff transformation model called GSM-SOCONT. For the glacierized catchments, the glacier surface corresponding to these future scenarios is updated through a conceptual glacier surface evolution model. The results obtained show that all climate-change scenarios induce, in all catchments, an earlier start of the snowmelt period, leading to a shift of the hydrological regimes and of the maximum monthly discharges. The mean annual runoff decreases significantly in most cases. For the glacierized catchments, the simulated regime modifications are mainly due to an increase of the mean temperature and the corresponding impacts on the snow accumulation and melting processes. The hydrological regime of the catchments located at lower altitudes is more strongly affected by the changes of the seasonal precipitation. For a given emission scenario, the simulated regime modifications of all catchments are highly variable for the different RCM runs. This variability is induced by the driving AOGCM, but also in large part by the inter-RCM variability. The differences between the different RCM runs are so important that the predicted climate-change impacts for the two emission scenarios A2 and B2 are overlapping. Copyright © 2006 John Wiley & Sons, Ltd. [source] Disequilibrium partial melting experiments on the Leedey L6 chondrite: Textural controls on melting processesMETEORITICS & PLANETARY SCIENCE, Issue 11 2001S. N. Feldstein Chips of the L6 chondrite, Leedey, were heated at 1200 °C and log ,O2 = IW-1 for durations of 1 h to 21 days. We observed a progression of kinetically-controlled textural changes in melt and restite minerals and changes in the liquidus mineralogy in response to factors such as volatile loss. During the course of the experiments, both olivine and orthopyroxene recrystallized at different times. Rare relic chondrules could still be identified after 21 days. The silicate melts that form are very heterogeneous, in terms of both major and trace element chemistry, reflecting heterogeneity of the localized mineral assemblage, particularly with respect to phosphates and clinopyroxene. Metal-sulfide melts formed in short-duration runs are also heterogeneous. The experimental data are relevant to aspects of the genesis of primitive achondrites such as the acapulcoites. The observed textures are consistent with a model for acapulcoite petrogenesis in which silicate melting was limited to only a few volume percent of the chondritic source rock. The experiments are also relevant to the behavior of chondritic material that has been partially melted in an impact environment. [source] | ||||||||||||||||