Indoor measurement of photovoltaic device characteristics at varying irradiance, temperature and spectrum for energy rating

This was accepted for publication in the journal Measurement Science and Technology. The definitive published version can be found at: http://dx.doi.org/10.1088/0957-0233/21/11/115701The first three-dimensional performance matrix for use in photovoltaic (PV) energy rating is reported utilizing a novel energy rating solar simulator based on LEDs. Device characteristics are measured indoors at varying irradiance (G), temperature (T) and spectrum (E). This opens the possibility for a more accurate measurement system for energy yield prediction of PV devices, especially for devices with high spectral dependence such as wide bandgap solar cells as they take into account spectral changes in the light. The main aspects of the LED-based solar simulator used are briefly described. A measurement method is developed and detailed in the paper, which takes into account the current imperfections in the achievable spectrum. Measurement results for a crystalline silicon solar cell are used to demonstrate the measurement approach. An uncertainty analysis of the measurement system is given, resulting in an overall absolute uncertainty of 4.3% (coverage factor k = 2) in maximum power measurements at 765 W m−2 irradiance with scope for further improvements

Facial masculinity:How the choice of measurement method enables to detect its influence on behaviour

Recent research has explored the relationship between facial masculinity, human male behaviour and males' perceived features (i.e. attractiveness). The methods of measurement of facial masculinity employed in the literature are quite diverse. In the present paper, we use several methods of measuring facial masculinity to study the effect of this feature on risk attitudes and trustworthiness. We employ two strategic interactions to measure these two traits, a first-price auction and a trust game. We find that facial width-to-height ratio is the best predictor of trustworthiness, and that measures of masculinity which use Geometric Morphometrics are the best suited to link masculinity and bidding behaviour. However, we observe that the link between masculinity and bidding in the first-price auction might be driven by competitiveness and not by risk aversion only. Finally, we test the relationship between facial measures of masculinity and perceived masculinity. As a conclusion, we suggest that researchers in the field should measure masculinity using one of these methods in order to obtain comparable results. We also encourage researchers to revise the existing literature on this topic following these measurement methods

Role of water chemistry in the selective flocculation and dispersion of iron ore

Fine-grained hematite ore can be concentrated by the process of selective flocculation and dispersion, which relies on proper reagent selection and control of water chemistry. While many previous studies have been performed analyzing the effects of different reagents on this process in a laboratory environment, this paper focuses on investigating the water chemistry within the process in a pilot-scale continuous deslime thickener. The pH, sodium concentration, calcium concentration and magnesium concentration were varied to determine their effects on the iron concentrate grade and recovery, and the phosphorus concentrate grade and rejection in the pilotscale selective deslime thickener. The ideal pH for the iron grade and recovery of the process using a starch selective flocculant was found to be 10.5. Phosphorus rejection, however, was increased at lower pH values. Minimization of sodium concentration was shown to improve iron grade, iron recovery and phosphorus rejection. Calcium acted as a nonselective flocculant showing higher iron recovery, lower iron grade and lower phosphorus rejection with increasing concentration. Conclusions could not be drawn from the experiments that varied magnesium concentration. The zeta potential of the solid-liquid interface of particles in each sample taken was also analyzed to show relationships between zeta potential and process performance. In all cases, a maximization of the magnitude of zeta potential correlated with increased iron grade and recovery. This supports the hypothesis that a higher level of dispersion enhances the selective flocculation and separation process

Aqueous ions in process water and cake moisture during iron ore filtration

© 2015 Taylor & Francis Group, LLC. In mineral beneficiation plants, aqueous ions from the process water concentrate within the filter cake moisture. These high concentrations of ions can lead to operational issues during downstream processes. This paper examines the ionic content of iron ore slurry before it was filtered at an operating hematite beneficiation plant and compared it with the ionic content of the moisture in the resultant filter cake. Water analyses were conducted to determine the sodium, potassium, calcium, magnesium, fluoride, chloride, nitrate, nitrite, carbonate, sulfate, and phosphate concentrations in both filter feed slurry and filter cake moisture. Results have shown that all tested ions within the process are more concentrated within the filter cake moisture than in the filter feed slurry. This has been attributed to the physical and chemical interactions of these ions with the iron ore particle surfaces. Of these ions, phosphorus concentrates most with the filter cake moisture content having a phosphorus content that is 24.67 times that of the filter feed slurry

Effects of water chemistry on hematite selective flocculation and dispersion

Copyright © 2015 Taylor & Francis Group, LLC. The only industrially proven method for the beneficiation of fine-grained ( \u3c 25 μm) hematite ores is selective flocculation and dispersion desliming followed by reverse cationic flotation. This process is reliant upon both water chemistry and proper reagent selection and dosing for effective separation of the hematite from gangue minerals. This study was performed to assess the effects of water chemistry on the beneficiation process in a pilot-scale deslime thickener. Grade versus recovery curves were constructed at varying water chemistries. In each set of experiments the concentration of one water chemistry parameter was varied while all others were held constant. The varied parameters included pH, sodium concentration and calcium concentration.The optimal pH for the separation of hematite from silica was found to be around 10.5. This was hypothesized to be due to a maximization in starch selective adsorption. Minimization in the sodium concentration showed increases in both the grade and the recovery of iron. Minimization in the calcium concentration showed increases in the grade of iron but losses in the recovery of iron. This study showed that the most effective way at increasing both the grade and recovery of the process was to optimize the pH and minimize the sodium concentrations

Design of a continuous pilot-scale deslime thickener

Copyright 2017, Society for Mining, Metallurgy & Exploration Inc. Thickening is used during two primary mineral processing operations: Water removal and desliming. During water removal, the pulp density is increased through the injection of flocculants. These flocs settle and create a dense pulp while clarified water is removed through the overflow. During desliming, fine particles are removed through the overflow. Desliming can also be used as a mineral separation process known as selective flocculation-dispersion, where valuable minerals are flocculated and gangue minerals remain dispersed and exit through the overflow. There are many ways to analyze thickener performance on a laboratory scale, but these analyses often do not correlate well with full-scale performance. Some pilot-scale systems have been designed using a semicontinuous approach, but the amount of material required to perform their tests can make semicontinuous pilot thickeners impractical for most applications. This paper focuses on the design and optimization of a continuous pilot-scale deslime thickener that requires minimal material to operate. The design, optimization strategy, and an example study of reagent selection are demonstrated

The effect of CO \u3c inf\u3e 2 sparging on the flocculation and filtration rate of concentrated hematite slurries

Filtration of hematite ore slurries can be a bottleneck in some hematite processing plants due to inadequate filtration rates caused by the dispersion of fine particles. Flocculation of fine particles in the slurry decreases the specific cake resistance of the filter cake allowing for increased filtration rates. CO 2 sparging of hematite slurry was shown to increase the filtration rate by altering the pH and the surface chemistry of the particles. It was shown that an increase in filtration rate of 278% can be accomplished by lowering the pH from 11 to 6.5 using CO 2 at a lab scale. This was attributed to increased flocculation of hematite and silica particles in the ore. © 2012 Elsevier B.V

Specifically Adsorbed Ions in the Reverse Cationic Flotation of Iron Ore

Although extensive research has been conducted on the effect of water chemistry in flotation, no single study exists which describes the effect of calcium and magnesium on the adsorption of starch onto the hematite in iron ore flotation. In this work flotation, entrainment, zeta potential, and settling tests were performed to determine the differing impact of calcium and magnesium in iron ore flotation. Results showed that magnesium is more detrimental to the flotation process at far lower concentrations than calcium. Performing flotation with 45 ppm of calcium resulted in a comparable impact on the process as performing flotation with 7 ppm of magnesium. While calcium promotes the adsorption of starch onto the hematite and reduces entrainment, past an optimal dosage magnesium is promoting the adsorption of starch to everything in solution causing low grades and recoveries. It was found that the starch adsorption onto the hematite is strongly impacted by the presence of magnesium, suggesting that starch is collecting the magnesium and self-flocculating prior to adsorption onto the hematite. Thus, the presence of magnesium can significantly reduce the flotation performance far more than what would be expected from calcium