scholarly journals Determination of mercury thermospecies in South African coals in the enhancement of mercury removal by pre-combustion technologies

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mpho Wendy Mathebula ◽  
Nikolai Panichev ◽  
Khakhathi Mandiwana
Keyword(s):  
South African ◽  
Bituminous Coal ◽  
Total Mercury ◽  
Mean Value ◽  
Thermal Release ◽  
Power Stations ◽  
Coal Classification ◽  
Specific Temperature ◽  
Selection Of

Abstract Samples of South African bituminous coals were analysed for total mercury (Hg) and Hg thermospecies concentrations using an RA-915 + Zeeman Mercury Analyser. Total mercury concentrations in samples of coals (n = 57) ranged between 10 ng g−1 and 493 ng g−1 with a mean value of 150 ± 53 ng g−1. Thermospecies of Hg were determined by monitoring Hg response as a function of sample temperature, increasing at 0.8 °C/s from ambient to 720 °C. This approach provides important information on thermal release of Hg species, as indicated by their appearance over specific temperature intervals. This permits identification of the presence of Hg thermospecies in coal and their quantification in each time (temperature) interval. It was found that 76% of tested bituminous coal samples release Hg species within low temperature intervals (20–180 °C and180–360 °C). The information generated in this study will aid in the selection of suitable coals for pre-combustion treatment that can lead to significant reduction of atmospheric Hg emission during coal combustion at power stations. This analytical approach can also be used for the creation of a system of coal classification based on the temperature of release of various Hg thermospecies.

scholarly journals Assessing terpene content variability of whitebark pine in order to estimate representative sample size

2013 ◽  
pp. 193-204
Author(s):  
Milena Stefanovic ◽  
Slobodanka Mitrovic ◽  
Dragica Obratov-Petkovic ◽  
Vera Vidakovic ◽  
Zorica Popovic ◽  
...  
Keyword(s):  
Sample Size ◽  
Representative Sample ◽  
Mean Value ◽  
Whitebark Pine ◽  
Initial Sample ◽  
Basic Set ◽  
Chemical Content ◽  
The Mean ◽  
Selection Of

In studies of population variability, particular attention has to be paid to the selection of a representative sample. The aim of this study was to assess the size of the new representative sample on the basis of the variability of chemical content of the initial sample on the example of a whitebark pine population. Statistical analysis included the content of 19 characteristics (terpene hydrocarbons and their derivates) of the initial sample of 10 elements (trees). It was determined that the new sample should contain 20 trees so that the mean value calculated from it represents a basic set with a probability higher than 95 %. Determination of the lower limit of the representative sample size that guarantees a satisfactory reliability of generalization proved to be very important in order to achieve cost efficiency of the research.

Damping Properties of Hard Coatings for Engine Applications

2010 ◽  
Vol 66 ◽  
pp. 126-135 ◽  
Author(s):  
Peter J. Torvik
Keyword(s):  
Hard Coatings ◽  
Thermal Barrier ◽  
Proper Selection ◽  
Coating Materials ◽  
Transition Range ◽  
Material Parameters ◽  
Specific Temperature ◽  
Plasma Sprayed ◽  
Selection Of

Although blade coating materials dissipate vibratory energy while acting as thermal barrier coatings or protecting the substrate against corrosion or erosion, the inherent nonlinearity of these materials complicates the determination of the necessary material parameters. While plasma-sprayed ceramics alone do not appear to provide the desired levels of dissipation, notable increases in damping have been found to result from the inclusion of small amounts of viscoelastic materials. With proper selection of the added component, the resulting coating may be tailored for high damping in a specific temperature range. Vacuum infiltration of polymeric components into plasma-sprayed ceramics raise the dissipation to desired levels for temperatures of 93-135 oC; co-spraying mixtures of ceramics and glass frits leads to extremely high damping in the transition range of the glass, typically 550-800 oC.

Development of Performance Grading Map of Nepal Based on Superpave System

2020 ◽  
Vol 8 ◽  
pp. 61-64
Author(s):  
Sunita Kharbuja ◽  
Thusitha Chandani Shahi ◽  
Rajan Duwal
Keyword(s):  
Prediction Models ◽  
Daily Maximum ◽  
Climatic Zones ◽  
Performance Grade ◽  
Specific Temperature ◽  
Analysis System ◽  
Performance Grading ◽  
Selection Of

The Performance of the bituminous binder plays important role in the overall performance of the pavement system. One of the major cause of pavement failure is the bitumen grade, i.e selection of suitable grade of bitumen. Therefore, performance grading of bituminous binder is inevitable for the specific temperature and climatic zones. This study is focused on the determination of performance grading of bituminous binder for various temperature zones in Nepal. In this study, twenty one years’ daily maximum and minimum secondary temperature data of 70 meteorological stations were collected and were analyzed for temperature zoning. Performance grading of bituminous binder was conducted with the help of Strategic Highway Research Program (SHRP) and Long-Term Pavement Performance Program (LTPP) prediction models. The concept of Superpave has been adopted for the analysis, which stands for superior performing asphalt pavement. The Superpave mix design includes a new analysis system based on performance characteristics of the pavement layer. The bituminous binder grades for Nepal have been determined on the basis of air temperature thereafter predicting the pavement temperatures. The study has determined seven different performance grade zones based on SHRP and four different performance grade zones based on LTPP model. The study synthesized the Performance Grade (PG) map of the country.

scholarly journals The application of statistical and/or non-statistical sampling techniques by internal audit functions in the South African banking industry

2015 ◽  
Vol 5 (1) ◽  
pp. 71-80
Author(s):  
Daniel P. van der Nest ◽  
Louis Smidt ◽  
Dave Lubbe
Keyword(s):  
South African ◽  
Banking Sector ◽  
Internal Audit ◽  
Sampling Techniques ◽  
Statistical Sampling ◽  
Internal Auditors ◽  
Evidence Gathering ◽  
Audit Sampling ◽  
Selection Of

This article explores the use by internal audit functions of audit sampling techniques in order to test the effectiveness of controls in the banking sector. The article focuses specifically on the use of statistical and/or non-statistical sampling techniques by internal auditors. The focus of the research for this article was internal audit functions in the banking sector of South Africa. The results discussed in the article indicate that audit sampling is still used frequently as an audit evidence-gathering technique. Non-statistical sampling techniques are used more frequently than statistical sampling techniques for the evaluation of the sample. In addition, both techniques are regarded as important for the determination of the sample size and the selection of the sample items.

In vitro determination of the skin anti-aging potential of eleven South African plants

Planta Medica ◽  
2013 ◽  
Vol 79 (13) ◽  
Author(s):  
GN Ndlovu ◽  
G Fouche ◽  
W Cordier ◽  
V Steenkamp ◽  
M Tselanyane
Keyword(s):  
South African ◽  
South African Plants ◽  
African Plants

Detection of Circulating Tissue Factor and Factor VII in a Normal Population

1996 ◽  
Vol 75 (05) ◽  
pp. 772-777 ◽  
Author(s):  
Sybille Albrecht ◽  
Matthias Kotzsch ◽  
Gabriele Siegert ◽  
Thomas Luther ◽  
Heinz Großmann ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Normal Population ◽  
Mean Value ◽  
Factor Vii ◽  
Significant Difference ◽  
Age Dependent ◽  
The Mean ◽  
Highly Correlated ◽  
And Gender

SummaryThe plasma tissue factor (TF) concentration was correlated to factor VII concentration (FVIIag) and factor VII activity (FVIIc) in 498 healthy volunteers ranging in age from 17 to 64 years. Immunoassays using monoclonal antibodies (mAbs) were developed for the determination of TF and FVIIag in plasma. The mAbs and the test systems were characterized. The mean value of the TF concentration was 172 ± 135 pg/ml. TF showed no age- and gender-related differences. For the total population, FVIIc, determined by a clotting test, was 110 ± 15% and the factor VIlag was 0.77 ± 0.19 μg/ml. FVII activity was significantly increased with age, whereas the concentration demonstrated no correlation to age in this population. FVII concentration is highly correlated with the activity as measured by clotting assay using rabbit thromboplastin. The ratio between FVIIc and FVIIag was not age-dependent, but demonstrated a significant difference between men and women. Between TF and FVII we could not detect a correlation.

Determination of Plasminogen in Clots and Thrombi

1966 ◽  
Vol 16 (01/02) ◽  
pp. 038-050 ◽  
Author(s):  
Ulla Hedner ◽  
Inga Marie Nilsson ◽  
B Robertson
Keyword(s):  
Mean Value ◽  
Main Mechanism ◽  
Clot Lysis ◽  
Post Mortem ◽  
Digestion Time ◽  
Normal Volunteers ◽  
Casein Solution ◽  
The Mean

SummaryThe plasminogen content was determined by a casein method in plasma and serum from 20 normal volunteers. The mean plasminogen content was found to be 10.1 ACU (the arbitrary caseinolytic unit defined in such a way that using a 3% casein solution and a digestion time of 20 min. at 37°C, 10 ACU gave an extinction of 0.300). No difference between serum and plasma regarding the plasminogen content was found.Plasminogen was determined in drained and drained plus washed clots prepared from 2 ml plasma. The highest values found in the drained clots were 0.9 ACU/clot and 0.2 ACU/clot in the drained plus washed clots.Plasminogen was also determined in drained and drained plus washed clots prepared from plasma with added purified plasminogen. The plasminogen was recovered in the washing fluid. According to these tests, then, purified added plasminogen is washed out of the clots.The plasminogen content of 20 thrombi obtained post mortem was also determined. The mean value was found to be 0.7 ACU/cm thrombus. Judging from our results, the “intrinsic clot lysis theory” is not the main mechanism of clot dissolution.

Apartheid Aesthetics and Insignificant Art

2016 ◽  
Vol 33 (1) ◽  
pp. 45-69
Author(s):  
Stephanus Muller
Keyword(s):  
South Africa ◽  
Secondary School ◽  
South African ◽  
Cultural Production ◽  
Art Songs ◽  
Cultural Significance ◽  
European Culture ◽  
Small House ◽  
The Rich ◽  
Selection Of

Stephanus Le Roux Marais (1896−1979) lived in Graaff-Reinet, South Africa, for nearly a quarter of a century. He taught music at the local secondary school, composed most of his extended output of Afrikaans art songs, and painted a number of small landscapes in the garden of his small house, nestled in the bend of the Sunday’s River. Marais’s music earned him a position of cultural significance in the decades of Afrikaner dominance of South Africa. His best-known songs (“Heimwee,” “Kom dans, Klaradyn,” and “Oktobermaand”) earned him the local appellation of “the Afrikaans Schubert” and were famously sung all over the world by the soprano Mimi Coertse. The role his ouevre played in the construction of a so-called European culture in Africa is uncontested. Yet surprisingly little attention has been paid to the rich evocations of landscape encountered in Marais’s work. Contextualized by a selection of Marais’s paintings, this article glosses the index of landscape in this body of cultural production. The prevalence of landscape in Marais’s work and the range of its expression contribute novel perspectives to understanding colonial constructions of the twentieth-century South African landscape. Like the vast, empty, and ancient landscape of the Karoo, where Marais lived during the last decades of his life, his music assumes specificity not through efforts to prioritize individual expression, but through the distinct absence of such efforts. Listening for landscape in Marais’s songs, one encounters the embrace of generic musical conventions as a condition for the construction of a particular national identity. Colonial white landscape, Marais’s work seems to suggest, is deprived of a compelling musical aesthetic by its very embrace and desired possession of that landscape.

Determination of the Probability Distribution of the Mean Sound Level

2010 ◽  
Vol 35 (4) ◽  
pp. 543-550 ◽  
Author(s):  
Wojciech Batko ◽  
Bartosz Przysucha
Keyword(s):  
Probability Distribution ◽  
Probability Distribution Function ◽  
Mean Value ◽  
Sound Level ◽  
Function Form ◽  
Noise Levels ◽  
Logarithmic Mean ◽  
The Mean ◽  
Estimation Of Uncertainty

AbstractAssessment of several noise indicators are determined by the logarithmic mean <img src="/fulltext-image.asp?format=htmlnonpaginated&src=P42524002G141TV8_html\05_paper.gif" alt=""/>, from the sum of independent random resultsL1;L2; : : : ;Lnof the sound level, being under testing. The estimation of uncertainty of such averaging requires knowledge of probability distribution of the function form of their calculations. The developed solution, leading to the recurrent determination of the probability distribution function for the estimation of the mean value of noise levels and its variance, is shown in this paper.

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