Diffusion multiple study of the Co-Fe-Ni system at 800 °C

The Co-Fe-Ni system is a key system in a wide range of industrial applications. Knowledge of the thermodynamic and kinetic properties of the system is crucial for the alloy and process design. Although the system has been studied extensively, there remain several unexplained discrepancies between different literature data and, for mediate low temperatures, the information is scarce. In this work, a high throughput diffusion multiple approach was applied. The isothermal phase diagram section at 800 °C was determined using the Co-Fe-Ni multiple. The interdiffusion coefficients of the binary Co-Fe, Co-Ni, Fe-Ni systems and their composition dependence were calculated using the Sauer-Freise method based on the compositional profiles obtained from the diffusion multiple. Different from previous experimental results for mediate low temperature, our results coincide with the extrapolated Arrhenius temperature dependence from diffusion coefficient data at high temperature range. These observations are important for a better understanding and modelling of the interdiffusion behavior in this key alloy system.     

Experimental investigation and thermodynamic assessment of the Mn–Zr system

The Mn–Zr binary system has been investigated via experimental measurements and thermodynamic calculations. In order to investigate phase equilibria in the Mn–Zr system, five alloys were prepared by arc melting under vacuum. All alloys were examined by means of X-ray diffraction, scanning electron microscopy and electron probe microanalysis after annealing at 650 °C for 70 days or 950 °C for 30 days. The homogeneity range of ZrMn₂ was determined to be from 25.0 to 33.2 at.% Zr at 950 °C and from 26.7 to 34.3 at.% Zr at 650 °C. The solubility of Mn in (αZr) was 1.6 at.% Mn, while that of Zr in (αMn) was 0.2 at.% Zr at 650 °C. The invariant reaction temperatures of liquid → ZrMn₂ + (βZr) and (βZr) → ZrMn₂ + (αZr) were determined to be 1131 and 785 °C, respectively. A thermodynamic assessment of the Mn–Zr system was conducted by taking into account the present experimental results and reliable literature data. The calculated results using the presently obtained parameters can well reproduce the experimental data.     

How consistent is the satellite derived SST–LHF relationship in comparison with observed values?

Time series data for sea surface temperature (moored buoy), wind speed, air temperature, sea level pressure, relative humidity, short wave radiation and rainfall were collected close to the Lakshadweep islands for five months from July 2000 to cover two seasons, namely summer monsoon and autumn. Day and night passes of TMI data for the same period were analysed to compare with the observed values. Daily mean values were then generated from both satellite‐derived as well as observed parameters and daily latent heat flux (LHF) values computed using the advanced COARE‐3.0 version of the model. In concurrence with earlier studies, the observed LHF–SST relationship was inverse as the SST during this season seldom fell below 27°C. On the contrary, the satellite derived LHF–SST relationship exhibited a direct correlation. It is also observed that the satellite underestimation of SST increases linearly on either side of a threshold value of 28.5°C. Although the SST over the eastern Arabian Sea was generally above 27°C, the satellite underestimation often produced SSTs less than 27°C, thereby supporting a linear relationship with LHF, as suggested by Zhang and McPhaden. Similarly for SSTs higher than 28°C, the satellite underestimation prevented a further decrease of LHF (to sustain the linear relationship) by virtue of the inverse relationship for SSTs higher than 28°C. The overestimation of SST and wind speed in the satellite scenario generates a virtual enhancement of LHF values without cooling the sea surface. The linear relationship between SST and LHF is thus nothing but a virtual display of the observed inverse SST–LHF relationship.     

Mass and energy flux estimates at different spatial resolutions in a heterogeneous area through a distributed energy–water balance model and remote-sensing data

A physically based, distributed energy–water balance model, Flash-Flood Event-Based Spatially Distributed Rainfall–Runoff Transformation-Energy Water Balance (FEST-EWB) model, and remote-sensing data were analysed to study the representativeness of mass and energy fluxes at different spatial resolutions. The analyses were performed in an agricultural area of Barrax (Spain) in the framework of the Sentinel-2 and Fluorescence Experiment (SEN2FLEX). In particular, there were two main objectives: (1) to evaluate the ability of the distributed hydrological model to compute energy and mass fluxes for a heterogeneous area compared to remote-sensing and ground data and (2) to define the length scales of different processes (evapotranspiration (ET) and land surface temperature (LST)) above which the variance of the different variables becomes insignificant for the process, so that bare soil and vegetation behaviours are no longer distinguishable. Mass and energy fluxes were collected from ground data and from an Airborne Hyperspectral Scanner (AHS), with a spatial resolution between 2 and 4 m, and from the Moderate Resolution Imaging Spectroradiometer (MODIS), with a spatial resolution of 1000 m, and then compared with hydrological model outputs. ET and LST spatial variability was analysed at different spatial resolutions using histograms, statistical parameters, and spatial autocorrelation functions.

Computed ET with the FEST-EWB model at high spatial resolution (10 m) showed for the three days of analysis a mean relative error of 9.4% compared to AHS data, whereas for land surface temperature comparison a relative error of 1.6% was found. Then, LSTs from AHS and FEST-EWB were aggregated at decreasing spatial resolutions (50, 150, 300, 400, 500, 600, 750, and 1000 m), showing that the thermodynamic variability tends to disappear with a lower number of classes in the histograms and with a decrease of the coefficient of variation (CV) and of standard deviation values. At each scale, a similar behaviour was reported between each pair of images, with the values of standard deviation starting, respectively, from 8.9°C and 9.6°C at 10 m of spatial resolution to 7.7°C and 7.9°C at 1000 m of spatial resolution. Similar results were obtained from the spatial aggregation of ET images. The decrease in standard deviation values of LST and ET with a decrease in the scale became substantial around pixel dimensions equal to 400 m.     

Calculation of phase diagrams for the metastable Al-Fe phases forming in direct-chill (DC)-cast aluminum alloy ingots

In direct-chill (DC)-cast 1xxx-and 5xxx-series Al sheet-ingots, the presence of mainly Fe and some Si, and cooling rates increasing from ≤1 °C/s in the ingot center to ~20 °C/s near the surface cause the formation of metastable intermetallic Al₆Fe and Al_mFe compounds in addition to the stable Al₃Fe, and hence the fir-tree defect. Since the Al-Fe and Al-Fe-Si phase diagrams are not useful in predicting the metastable phase formation, a binary phase diagram study was conducted to calculate the Al-Al₆Fe and Al-Al_mFe metastable phase equilibria using a thermodynamic software and an Al-alloy database. The Al-Al₃Fe phase diagram was calculated using the existing Gibbs energy data which gives the eutectic point at 1.85wt% Fe and the eutectic temperature as 654 °C. The missing Gibbs energy data for the metastable phases were estimated using substitutional and graphical methods and the phase diagrams were calculated. In the Al-Al₆Fe phase diagram, the eutectic temperature is depressed from 654 °C (equilibrium) to 648 °C and the eutectic point is shifted from 1.85wt% Fe to 3.4wt% Fe. In the Al-Al_mFe phase diagram, the eutectic temperature is 643 °C and the eutectic point is at 4.6wt% Fe. The verification of the calculated eutectic temperatures was carried out by DSC measurements which were conducted on samples removed from Al-Fe alloy rods directionally grown in a Bridgman-type solidification furnace. A good agreement is observed between the calculated and measured values.     

Landsat-TM data for estimating ground temperature and depth of subsurface coal fire in the Jharia coalfield,India

Coal fires are a ubiquitous problem in coal-mines, the world over. They burn our prime energy resource, lead to atmospheric pollution and render mining of coal hazardous. Processes leading to coal combustion and spread of subsurface fires are briefly examined in this paper and the role of remote sensing in surveillance of coal fires is presented.

The present study aims at developing a quick method for estimating the temperature of the ground surface directly above subsurface coal fires. Utility of TM6 and TM7-band data for temperature estimation is briefly reviewed. It is argued that temperature calculations of surface anomalies related to subsurface fires can only be done on the basis of 8–14 μm band data, due to the low temperatures involved.

In the Jharia coalfield, it is noted that subsurface fires in various coal-mines are associated with surface thermal anomalies, as has also been confirmed by ground checks. The pattern of TM6 data distribution and ground truth is used to isolate thermal anomalies, and the TM6 digital numbers are converted into kinetic temperature values. It is observed that for the Landsat-TM scene ( 28 November 1990) the kinetic temperatures range from 16·0°C to 31·6°C in the Jharia coalfield, with a threshold value of 25·6°C associated with the anomalies. Depth estimation of fire has been carried out using field structural geology data and pixel locations of thermal anomalies. It is inferred that the depth of subsurface coal fire ranges between 45–55 m, in most cases, which is in general agreement with the field data. Limitations of the method are indicated.     

Modeling of Trivalent Chromium Sorption onto Commercial Resins by Artificial Neural Network

In this research, artificial neural network (ANN) model having three layers was developed for precise estimation of Cr(III) sorption rate varying from 17% to 99% by commercial resins as a result of obtaining 38 experimental data. ANN was trained by using the data of sorption process obtained at different pH (2–7) values with Amberjet 1200H and Diaion CR11 amount (0.01–0.1 g) dosage, initial metal concentration (4.6–31.7 ppm), contact time (5–240 min), and a temperature of 25°C. A feed-forward back propagation network type with one hidden layer, different algorithm (transcg, trainlm, traingdm, traincgp, and trainrp), different transfer function (logsig, tansig, and purelin) for hidden layer and purelin transfer function for output layer were used, respectively. Each model trained for cross-validation was compared with the data that were not used. The trainlm algorithm and purelin transfer functions with five neurons were well fitted to training data and cross-validation. After the best suitable coefficient of determination and mean squared error values were found in the current network, optimal result was searched by changing the number of neurons range from 1 to 20 in the current network hidden layer.     

Observations of oceanic mesoscale features and variability in the Canary Islands area from ERS-1 altimeter data,satellite infrared imagery and hydrographic measurements

The main purposes of this paper are to identify and evaluate the oceanic mesoscale features that appear in the Atlantic Ocean eastern boundary, 20-40° N, 19-9° W, using ERS-1 (1992-1993) satellite altimeter data. The sea surface height anomalies and the eddy kinetic energy fields are calculated. High energy values, between 0.03 and 0.05 m 2 s -2, are observed with the altimeter data in the Canary region mainly in summer. These maximum values are associated with eddies located downstream of Gran Canaria and Tenerife (Canary Islands). Comparison with in situ measurements provided by the hydrographic surveys from a cruise in summer 1993 around the Canary Islands showed a good agreement. Dynamic heights relative to 300 dbar for August and the altimetric heights from ERS-1 data were averaged over 0.125° boxes for the duration of the cruise. The correlation coefficient was 0.7. Negative anomalies of the sea level calculated from ERS-1 between Cape Yubi and Cape Bojador (26.0°-27.5° N) were obtained in August 1993. Possibly these correspond with filaments from the north-west African upwelling coast. Also, the results of the altimetric data were compared with NOAA AVHRR (Advanced Very High Resolution Radiometer) sea surface temperature (SST) satellite images. A cyclonic and an anticyclonic eddy to the south-west of the island of Gran Canaria were identified during the same period in the SST images.     

Phase equilibria and thermodynamic evaluation of the Fe-V-O system in air

The Fe-V-O system in air was studied experimentally ranging from 700 °C to 1450 °C by high-temperature equilibration, quenching, scanning electron microscope and microprobe analysis. The thermodynamic evaluation was performed with FactSage 7.0. The solubility of V₂O₅(s) in Fe₂O₃(s) was described with the compound energy formalism. The properties of the liquid phase were described with both the quasichemical model and the associate species model. A set of self-consistent thermodynamic parameters were estimated within acceptable error limits. The calculated phase diagram of Fe-V-O in air is presented and compared to experimental observations and other literature data.     

Thermodynamic model for acidic Ni(II) sulfate from solubility data

Acidic nickel sulfate solutions are generated in a large scale in the hydro- and pyrometallurgical industries. They are also produced in many industrial processes from nickel refining to surface finishing of metals by electroplating. Acid mine drainage has long been a significant environmental problem in coal and metal mining. The demand of recycling and reuse of materials has increased significantly especially in EU. Dumping a neutralized deposit is not an option any more. Thus, several techniques of recycling and reuse of sulfuric acid and/or metal sulfates from the side streams are needed.When developing alternative solutions, a better understanding of the thermodynamic behavior of NiSO₄–H₂SO₄–H₂O system is needed. In this study a thermodynamic model of this system has been developed in order to yield a thermodynamically consistent set of values for the solubility of nickel sulfate in a wide temperature and concentration range. The current model presents the experimental data available with a good accuracy and consistently up to 90 °C, and sulfuric acid concentrations up to 10 mol/kg. The model also predicts well the solubility measurements available in dilute up to 1.55 mol/kg sulfuric acid solutions at 200–250 °C.     

Experimental investigation and thermodynamic calculation of the phase equilibria in the Fe–Ni–V system

The phase equilibria in the Fe–Ni–V ternary system were investigated by means of electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Three isothermal sections of the Fe–Ni–V ternary system at 1000 °C, 1100 °C and 1200 °C were established. On the basis of the obtained experimental data, the phase equilibria in the Fe–Ni–V system were thermodynamically assessed using (CALculation of PHAse Diagrams) CALPHAD method, and a consistent set of thermodynamic parameters leading to reasonable agreement between the calculated results and experimental data was obtained.     

Study on the estimation of near-surface air temperature from MODIS data by statistical methods

Spatially distributed air temperature is desired for various scientific studies, including climatalogical, hydrological, agricultural, environmental and ecological studies. In this study, empirical models with regard to land cover and spatial scale were introduced and compared to estimate air temperature from satellite-derived land surface temperature and other environmental parameters. Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) data and meteorological data obtained throughout 2005 in the Yangtze River Delta were adopted to develop statistical algorithms of air temperature. Four empirical regression models with different forms and different independent variables resulted in errors ranging from 2.20°C to 2.34°C. Considering the different relationships between air temperature and land surface temperature for different land types, these four models were evaluated and the most proper equation for each land-cover type was determined. The model containing these selected equations gave a slightly improved mean absolute error (MAE) of 2.18°C. Then the spatial scale effect of this empirical model was analysed with observed air temperature and spatially averaged land surface characteristics. The result shows that the estimation error of air temperature tends to be lower as spatial window size increases, suggesting that the model performances are improved by spatially averaging land surface characteristics. Comprehensively considering the accuracy and computational demand, 5 × 5 pixel size is the most favourable window size for estimating air temperature. The validation of the empirical model at 5 × 5 pixel size shows that it achieves an MAE of 1.98°C and an R ² of 0.9215. This satisfactory result indicates that this approach is proper for estimating air temperature, and spatial window size is an important factor that should be considered when calculating air temperature. It is expected that better accuracy will be achieved if the different weights of pixels at different distances can be set according to high-density micro-meteorological data.     

Effects of shoulder rotation combined with elbow flexion on discomfort and EMG activity of ECRB muscle

Work related MusculoSkeletal Disorders (WMSDs) are injuries or dysfunctions caused by occupational or non occupational tasks involving bad postures, high frequency of exertions or high force levels. In the present study, the effects of shoulder flexion/extension combined with elbow flexion angle on discomfort score were investigated for repetitive gripping task. A laboratory experimental simulation was conducted. Ten male participants volunteered in this study. Four levels of shoulder flexion/extension (−45° extension, 0° neutral, 45° & 90° flexion) with three levels of elbow flexion angle (45°, 90° & 135°) were taken as levels of independent variables. There were 12 combinations available for each participant and the experiment was conducted on the basis of random order of experimental combinations for each participant. Discomfort score on 100 mm visual analogue scale (VAS) and Electromyography (EMG) activity of Extensor Carpi Radialis Brevis (ECRB) muscle were dependent variables for the analyses. The task for the experiment was of 150N ± 5N grip force at a frequency of 15 exertions/minute for five minutes duration. After performing the MANOVA on the recorded data, the results showed that the shoulder flexion/extension and elbow flexion both were highly significant (p < 0.001). Also it was found that −45° shoulder extension combined with 45° elbow flexion angle was the most discomfort posture. The practical relevance of the study is that, in industrial tasks such posture should be avoided to minimize risk of WMSDs.Relevance to industryThe findings in terms of relationship between discomfort/EMG vs. shoulder rotation combined with elbowflexion are important to design Industrial tasks with the reduced risk of WMSDs. Such as, sheet metal cutting, fabrication of sheet metal work, die casting, and drilling operations may require the shoulder movements in extenion/flexion combined with elbowflexion.     

Calphad-type assessment of the Sb–Sn–Zn ternary system

The ternary Sb–Sn–Zn phase diagram was investigated experimentally by scanning electron microscopy (SEM) and differential thermal analysis (DTA) of long-term annealed samples. The overall composition of each sample was measured by energy-dispersive X-ray spectroscopy (EDX). The experimental results, together with additional available literature data, were used to perform a CALPHAD-type thermodynamic assessment of this ternary system. Two calculated isothermal sections (250 and 350 °C), an isopleth (x(Sn)=17.57%) and the Zn activity in liquid ternary Sb–Sn–Zn alloys at 550 °C for the composition ratio Sn/Sb=1/3 and at 650 °C for the ratio Sn/Sb=9 are presented with experimental points superimposed. The liquidus projection for the ternary Sb–Sn–Zn system is also presented. The agreement between calculated and experimental results is reasonable.     

Phase diagram of Ag–Pb–Sn system

The Ag–Pb–Sn ternary system is an important material system for both electronic packaging and thermoelectric applications. However, there is no experimental phase equilibria information of the ternary system. Ag–Pb–Sn alloys are prepared and their phase equilibria at various temperatures were determined. The focus was on the 500, 350, and 200 °C isothermal sections. Additional information was also obtained for 400, and 300 °C. Several samples were studied by DSC studies. No ternary compounds were found in the ternary system. The Ag–Sn binary compounds, Ag₃Sn(ε) and Ag₄Sn(ζ) at 350 °C and Ag₄Sn(ζ) at 500 °C, exhibit very small Pb solubility. The thermodynamic assessment of the ternary Ag–Pb–Sn system was carried out using the above mentioned experimental data.     

大温差应用环境下的MEMS陀螺零偏补偿研究

MEMS陀螺的工艺特点决定了其零偏随温度呈现非线性变化的特点。针对工业现场实际应用环境温度变化范围大、分段补偿模型断点处不连贯和补偿温度范围小等问题,提出了一种新型的无需分段、全温度区间线性回归补偿模型;并且针对MEMS陀螺启动不稳定性因素对零偏造成的影响,改进的补偿模型可有效抑制陀螺上电时刻的零偏。经过实验验证:该模型补偿后的数据较陀螺原始数据零偏提高了将近3个数量级,从2.9027°/s提高到0.0091°/s,并且该算法相对简单易于编程实现,具有很好的工程实用价值。     

Sensitivity of space-borne SAR data to forest parameters over sloping terrain. Theory and experiment

Recently, SAR data proved to be useful for the retrieval of forest biomass. However, the effects of terrain slope must be addressed towards the generalization of biomass retrieval for varied forest and environmental conditions. To this aim, we developed experimental and theoretical approaches allowing the study of multi-frequency/multi-polarization forest backscatter of a given forest type, as a function of forest parameters and SAR local incidence angle over the relief. The experimental results showed that the sensitivity of SAR data to biomass was similar to that obtained over a flat terrain, only if the backscatter data were calibrated for slope effects. Moreover, the backscatter must also be corrected for its angular decrease, which can be removed using a simple angular model developed under assumptions of theoretical equations. The highest correlation of corrected backscatter with forest parameters related to aboveground biomass (such as stand age and bole volume) was achieved at L-HV 55° (R ²     

Thermodynamic analysis of reactions in the Al-N-Ta and Al-N-V systems

The Al-N-Ta and Al-N-V ternary phase diagrams are calculated from the thermodynamic parameters of the corresponding binary systems. For the Al-N-Ta system, the direct extrapolation from the binary edges can describe the experimental information on the isothermal sections at 1000, 1250 and 1500 °C from the literature. In the case of the Al-N-V system, it is shown that the direct extrapolation from the binary edges can describe the experimental isothermal section at 1300 °C from the literature. For the isothermal section at 1000 °C, however, the extrapolation does not reproduce the reported AlN + (V) + VN_x phase equilibrium. The calculated Al-N-Ta and Al-N-V phase diagrams are also compared with the phase assemblage resulting from our own thin film diffusion couples Ta/AlN and V/AlN. It is plausible that these assemblage data are associated with intermediate states approaching true equilibrium states.