How to Measure Specific Deposit Washout and Backwash Efficiency of Granular Filters

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
S. J. van Staden ◽  
J. Haarhoff
Keyword(s):  
Water Treatment ◽  
South African ◽  
Good Condition ◽  
High Water ◽  
Practical Experience ◽  
Great Promise ◽  
Filter Media ◽  
Long Run ◽  
Specific Deposit ◽  
Over Time

Practical experience shows that water treatment filters develop problems over time due to the routine running of the filter, including backwashing. There are difficulties in maintaining filters in good condition, given the eutrophic state of many South African raw waters, high water temperatures and the development of difficult-to-remove biofilm as a result. Such difficulties are often related to deposits accumulated on the filter media and it is, therefore, expected that the backwash system should be good enough to ensure that the filter is kept clean in the long run. This paper deals with a fairly simple operational option to significantly improve backwash efficiency at treatment plants where air and water are used consecutively. The paper describes methods used and typical results obtained in the testing of the quantitative benefits of multiple wash cycles. Multiple washing shows great promise for improving backwash efficiency, with an average of an additional 40% to 50% of the solids that would have been washed out with a single wash, removed by a second wash. Furthermore, third and even fourth washes continue to remove additional dirt from the filter. Multiple washing, therefore, may be a useful tool for the effective rehabilitation of a filter, as well as for routine operation procedures.

scholarly journals Top incomes in South Africa in the twentieth century

Cliometrica ◽  
2021 ◽  
Author(s):  
Facundo Alvaredo ◽  
A. B. Atkinson
Keyword(s):  
South Africa ◽  
South African ◽  
Top Incomes ◽  
Long Run ◽  
Hard Evidence ◽  
Trends Over Time ◽  
Changes Over Time ◽  
The Impact ◽  
First Time ◽  
Over Time

AbstractThere have been important studies of recent income inequality and of poverty in South Africa, but very little is known about the long-run trends over time. There is speculation about the extent of inequality when the Union of South Africa was formed in 1910, but no hard evidence. In this paper, we provide evidence that is partial—being confined to top incomes—but which for the first time shows how the income distribution changed on a (near) annual basis from 1913 onwards. We present estimates of the shares in total income of groups such as the top 1% and the top 0.1%, covering the period from colonial times to the twenty-first century. For a number of years during the apartheid period, we have data classified by race. The estimates for recent years bear out the picture of South Africa as a highly unequal country, but allow this to be placed in historical and international context. The time series presented here will, we hope, provide the basis for detailed investigation of the impact of South African institutions and policies, past and present. But the similarity of the changes over time in top incomes across the four ex-dominions suggests that national developments have to be seen in the light of common global forces.

scholarly journals A Central Element of Europe’s Football Ecosystem: Competitive Intensity in the “Big Five”

2021 ◽  
Vol 13 (6) ◽  
pp. 3097
Author(s):  
Fabio Wagner ◽  
Holger Preuss ◽  
Thomas Könecke
Keyword(s):  
Big Five ◽  
Central Element ◽  
Quantitative Approach ◽  
Competitive Intensity ◽  
Entrepreneurial Ecosystems ◽  
Long Run ◽  
The Future ◽  
European Football ◽  
Over Time

This study perceives professional European football as one of the most relevant event-related entrepreneurial ecosystems (EEs) worldwide. It also identifies a healthy sporting competition in the five most popular European football leagues (Spain, England, Germany, Italy, and France), the “big five,” as a key pillar for the functioning of this ecosystem. By applying a quantitative approach, competitive intensity (CI) is measured for all big five leagues for 21 seasons (1998/99 to 2018/19). The chosen method does not only convey an overall indication of the competitive health of the entire league but also provides detailed information on the four important sub-competitions (championship race, qualification for Champions League or Europa League, and the fight against relegation). In all five leagues, seasonal CI tends to decrease over time, and especially over the last decade. The main reason is a decline in the intensity of the championship race while all other sub-competitions show relatively robust CI values. Overall, it can be concluded that the competitive health of the big five is intact, but the dwindling CI of the championship races can harm the EE of professional European football in the long run. Accordingly, it should be closely monitored in the future.

scholarly journals Recent Advances of Photocatalytic Application in Water Treatment: A Review

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1804
Author(s):  
Guangmin Ren ◽  
Hongtao Han ◽  
Yixuan Wang ◽  
Sitong Liu ◽  
Jianyong Zhao ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Water Treatment ◽  
High Efficiency ◽  
Low Cost ◽  
Great Promise ◽  
Rapid Progress ◽  
Recent Advances ◽  
Photocatalytic Application ◽  
Oxidation Technology ◽  
Performance Challenges

Photocatalysis holds great promise as an efficient and sustainable oxidation technology for application in wastewater treatment. Rapid progress developing novel materials has propelled photocatalysis to the forefront of sustainable wastewater treatments. This review presents the latest progress on applications of photocatalytic wastewater treatment. Our focus is on strategies for improving performance. Challenges and outlooks in this promising field are also discussed. We hope this review will help researchers design low-cost and high-efficiency photocatalysts for water treatment.

scholarly journals Forces Necessary to Initiate Dispersal for Three Tumbleweeds

2008 ◽  
Vol 1 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Dirk V. Baker ◽  
K. George Beck ◽  
Bogusz J. Bienkiewicz ◽  
Louis B. Bjostad
Keyword(s):  
Water Treatment ◽  
Conversion Factor ◽  
Common Garden ◽  
High Water ◽  
Western United States ◽  
Field Collection ◽  
Stem Strength ◽  
Wind Velocities ◽  
Diffuse Knapweed ◽  
Water Treatments

AbstractAlthough diffuse knapweed, kochia, and Russian thistle are important tumbleweeds of the western United States, environmental factors contributing to their dispersal are not well understood. Bolting rosettes of these species were transplanted to pots and reared in a common garden to determine the affect of postsenescence water on stem strength. There were no differences in stem strength among three water treatments for Russian thistle. Kochia, under moderate water treatment, required more than twice the force to break compared to plants under the zero and high water treatments. In contrast, diffuse knapweed plants under zero water treatment required four to six times greater force to break compared to plants under the moderate and high water treatments. There was a strong difference in diffuse knapweed stem strength between field collection sites that corresponded to observed differences in proportion of plants tumbling. A wind tunnel was used to develop a conversion factor between force and wind velocity. Wind velocities necessary to break diffuse knapweed stems ranged from 16 to 37 m/s (36 to 77 mph).

scholarly journals Reading Practices and Literacy of Boer Combatants in the South African War of 1899–1902

2017 ◽  
Vol 24 (3) ◽  
pp. 286-307
Author(s):  
Fransjohan Pretorius
Keyword(s):  
Decision Making ◽  
South African ◽  
Practical Experience ◽  
The State ◽  
Reading Practices ◽  
The South ◽  
Planning Strategy ◽  
The Bible ◽  
South African War ◽  
Reading Matter

In investigating the reading practices of Boer combatants during the South African War, diaries, letters, and reminiscences were consulted. The state of literacy reveals a picture of a small number of highly literate men, a larger group of adequately literate men, a still larger group of semi-literates, and the illiterate. Reading matter included the Bible, newspapers, and books. Issues raised are: Did literacy (or illiteracy) influence military decision-making or troop morale? Were certain works making some impact on the battlefield? Was the practical experience the Boers had gained before the war more successful in planning strategy and tactics than literacy?

Long-Run Effects in Dynamic Systems: New Tools for Cross-Lagged Panel Models

2021 ◽  
pp. 109442812199322
Author(s):  
Ali Shamsollahi ◽  
Michael J. Zyphur ◽  
Ozlem Ozkok
Keyword(s):  
Recent Work ◽  
Dynamic Systems ◽  
Quantitative Methods ◽  
Simulated Dataset ◽  
Impulse Responses ◽  
Panel Models ◽  
Long Run ◽  
Short Run ◽  
User Friendly ◽  
Over Time

Cross-lagged panel models (CLPMs) are common, but their applications often focus on “short-run” effects among temporally proximal observations. This addresses questions about how dynamic systems may immediately respond to interventions, but fails to show how systems evolve over longer timeframes. We explore three types of “long-run” effects in dynamic systems that extend recent work on “impulse responses,” which reflect potential long-run effects of one-time interventions. Going beyond these, we first treat evaluations of system (in)stability by testing for “permanent effects,” which are important because in unstable systems even a one-time intervention may have enduring effects. Second, we explore classic econometric long-run effects that show how dynamic systems may respond to interventions that are sustained over time. Third, we treat “accumulated responses” to model how systems may respond to repeated interventions over time. We illustrate tests of each long-run effect in a simulated dataset and we provide all materials online including user-friendly R code that automates estimating, testing, reporting, and plotting all effects (see https://doi.org/10.26188/13506861 ). We conclude by emphasizing the value of aligning specific longitudinal hypotheses with quantitative methods.

An Evaluation of Mono-product Economies & examining the sine qua non for diversification - In West Asian Region

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Sushmita .
Keyword(s):  
Nuclear Energy ◽  
Renewable Energy Sources ◽  
The West ◽  
Capitalist System ◽  
Asian Region ◽  
Long Run ◽  
Asian Economies ◽  
On Line ◽  
Mode Of Development ◽  
Over Time

The discovery of oil in West Asia has contributed to its integration into the international capitalist system. The mono-commodity, oil, has brought tremendous wealth to West Asia. But a rising population and an ever growing demonstration effect, has caused imports to grow exorbitantly, with oil prices expected to fall, depicted explicitly by recent oil price drop, also over time as interest in climate change increases after RIO-20, and more options of renewable energy sources coming on line like Gas, Solar Energy, wind power and nuclear energy etc. the rentier mode of development followed by west Asian economies is clearly unsustainable. Further the oil producing nations are so over-specialized that they do not possess the necessary flexibility to shift their resources from one sector to another, or to develop substitution if and when the need arises. Moreover, the ability of oil producing countries to respond to deliberate or accidental economic measures taken abroad is limited. This paper theoretically analyses the standing of the West Asian mono product economies, their specific traits, benefits and disbenefit of current condition and looks into the case for diversification of West Asian Region. As diversification is a sine qua non in long Run for the sustainability of the West Asian economies.

A Fitting Approach to Construct and Measurement Alignment

2017 ◽  
Vol 21 (3) ◽  
pp. 592-632 ◽  
Author(s):  
Margaret M. Luciano ◽  
John E. Mathieu ◽  
Semin Park ◽  
Scott I. Tannenbaum
Keyword(s):  
Big Data ◽  
Data Streams ◽  
Iterative Process ◽  
Emerging Technologies ◽  
Measurement Techniques ◽  
Great Promise ◽  
Big Data Technologies ◽  
Nearly Continuous ◽  
Dynamic Phenomena ◽  
Over Time

Many phenomena of interest to management and psychology scholars are dynamic and change over time. One of the primary impediments to the examination of dynamic phenomena has been challenges associated with collecting data at a sufficient frequency and duration to accurately model such changes. Emerging technologies that produce nearly continuous streams of big data offer great promise to address those challenges; however, they introduce new methodological challenges and construct validity concerns. We seek to integrate the emerging big data technologies into the existing repertoire of measurement techniques and advance an iterative process to enhance their measurement fit. First, we provide an overview of dynamic constructs and temporal frameworks, highlighting their measurement implications. Second, we discuss different data streams and feature emerging technologies that leverage big data as a means to index dynamic constructs. Third, we integrate the previous sections and advance an iterative approach to achieving measurement fit, highlighting factors that make some measurement choices more suitable and viable than others. In so doing, we hope to accelerate the advancement of dynamic theories and methods.

scholarly journals Analysis of the Keynesian Theory of Employment and Sectoral Job Creation: The Case of the South African Manufacturing Sector

2018 ◽  
Vol 18 (1) ◽  
pp. 123-143
Author(s):  
Thomas Habanabakize ◽  
Paul-Francois Muzindutsi
Keyword(s):  
South African ◽  
Manufacturing Sector ◽  
Job Creation ◽  
The South ◽  
Economic Sectors ◽  
Vector Autoregressive ◽  
Integration Approach ◽  
Long Run ◽  
Short Run ◽  
Investment Spending

Abstract The manufacturing sector is one of the backbones of the South African economy, and yet is one of the economic sectors facing challenges in job creation. This study analysed the long-run and short-run effects of aggregate expenditure components on job creation in the South African manufacturing sector. A Vector Autoregressive (VAR) with Johansen co-integration approach was used to analyse quarterly data from 1994 to 2015. The findings are that there is a long-run relationship between aggregate expenditure and job creation in the South African manufacturing sector, with government and investment spending being the major components of aggregate expenditure that create jobs in the South African manufacturing sector. Conversely, consumption spending destroys jobs in the manufacturing sector, while net exports have no significant effect on job creation. The short-run relationship between variables was not significant. Recommendations are that more effort should be put into investment spending, and government should spend more on investment than on consumption spending - in order to increase job creation in the manufacturing sector.

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