Benefit and Implementation of Groundwater Protection Zoning in South Africa

Groundwater studies in several African countries show that the contamination of water-supply aquifers is mainly due to improper placement of land-based activities such as agriculture, industries, waste disposal. In South Africa, groundwater pollution is also of increasing concern due to fast population growth and accompanying development. Groundwater protection zoning is a supplemental methodology for groundwater management that incorporates land use planning. The land is managed to minimize the potential of groundwater contamination by human activities that occur on or below the land surface. The various benefits associated with implementation of protection zoning are discussed for stakeholders such as communities, water supply companies, ecosystems and policy makers. A South African case study is presented comparing the cost of protection with the cost incurred due to the treatment of sick and dying people due to contaminated drinking water. These benefits must be communicated to the stakeholders to start the implementation at all management levels. Implementation steps of groundwater protection zones are discussed and can be tested even with low budgets and little data available. Monitoring and reassessment of protection zones are important to test the effectiveness and prove to decision makers that the money was well spent. The legal framework for implementation of groundwater protection zoning in a South African context is described, where the water law makes provision for tools like differentiated protection, licensing and recovery of cost. Challenges regarding implementation of groundwater protection are discussed with some action steps on how to move forward.     

Regularization, Scale-Space, and Edge Detection Filters

Computational vision often needs to deal with derivatives ofdigital images. Such derivatives are not intrinsic properties ofdigital data; a paradigm is required to make them well-defined.Normally, a linear filtering is applied. This can be formulated interms of scale-space, functional minimization, or edge detectionfilters. The main emphasis of this paper is to connect these theoriesin order to gain insight in their similarities and differences. We donot want, in this paper, to take part in any discussion of how edgedetection must be performed, but will only link some of the current theories. We take regularization (or functional minimization) as astarting point, and show that it boils down to Gaussian scale-space ifwe require scale invariance and a semi-group constraint to besatisfied. This regularization implies the minimization of afunctional containing terms up to infinite order of differentiation.If the functional is truncated at second order, the Canny-Deriche filter arises. It is also shown that higher dimensional regularizationboils down to a rotated version of the one dimensional case, whenCartesian invariance is imposed and the image is vanishing at theborders. This means that the results from 1D regularization can beeasily generalized to higher dimensions. Finally we show how anefficient implementation of regularization of order n can be made byrecursive filtering using 2n multiplications and additions peroutput element without introducing any approximation.     

Development of an Experimental Device to Study High Temperature Oxidation

An experimental device was designed and constructed to study the oxidation behaviour of steel. The device consists in a special chamber mounted within the frame of a servo-hydraulic testing machine holding the sample being studied. The atmosphere within the chamber can be controlled to be either inert or oxidation by flowing either nitrogen or dry air: a flow of 14 Nl/min was used for replacing either atmosphere in less than 0.1 s. The sample of steel was heated up to the testing temperature by induction. The testing procedure was designed to be flexible enough for heating up and cooling down the sample without oxidation. The device allowed for scales that ranged from a few micrometers to close to 300 μm. The growth kinetics recorded in this work was found to agree with previous published data. It can be concluded that the present device allows for studying the behaviour of thin crusts of steel oxide, which are classified as tertiary and can damage the surface of the steel during rolling.     

Cobalt removal from waste‐water by means of supported liquid membranes

BACKGROUND: Supported liquid membranes (SLM) are an alternative technique to remove and recover metals from diluted process solutions and waste‐water. In the present work, the removal of Co(II) from a synthetic CoSO₄ solution containing initial amounts of cobalt(II) in the range 100–200 ppm (0.1–0.2 g dm^?3) has been studied on a pilot scale. By performing batch equilibrium experiments, the optimal settings, i.e. the composition of the organic phase, the pH of the feed, the type and concentration of the stripping agent were determined. RESULTS: It is shown that the equilibrium characteristics of a synergistic extractant mixture containing di‐2‐ethyl‐hexylphosphoric acid (D2EHPA) and 5‐dodecylsalicylaldoxime (LIX 860‐I) are superior to D2EHPA. Both hydrochloric acid and sulfuric acid have been evaluated as stripping solutions in liquid–liquid extraction tests and as the receiving phase in a SLM configuration. Although equilibrium tests showed no difference in stripping characteristics between both chemicals, it was observed that in a SLM configuration the stability of the system when hydrochloric acid is used is poor. With a commercially available SLM module (Liqui‐Cel Extra‐Flow 4 × 28) having a surface area of 19 m², a steady Co(II) flux of 0.140 gm^?2h^?1 has been obtained at influent concentrations of cobalt between 100 and 200 ppm with 3 mol dm^?3 sulfuric acid as stripping phase. CONCLUSIONS: The results obtained show that a supported liquid membrane containing a synergistic mixture of LIX 860‐I and D2EHPA gives the possibility of recovering cobalt from dilute solutions. Copyright © 2008 Society of Chemical Industry     

The development of an environmental friendly catalytic system for the conversion of olefins

An elegant method is described for the synthesis of ZSM-22. By controlled addition of seeds and applying stirring during the crystallization, the phase purity and the crystal size can be controlled. The H-ZSM-22 is tested in the dense phase oligomerization of propene at 180–250°C and 70 bar. It is found that adding small amounts of water significantly increases the activity and decreases the deactivation of the catalyst. Secondly, it is shown that catalyst activity is higher after calcination at 400°C versus 550°C and that smaller crystal sizes positively affect the catalyst activity. Both observations are ascribed to the presence of active sites located near the zeolite outer surface accounting for a major part of the catalytic activity.     

Simplified seismic analysis methods in Belgium

Seismic design and analysis of nuclear plant systems, structures and components have requested huge effort and tremendous costs in the past two decades. The extended use of sophisticated, linear response type methods (modal analysis, spectral response) and the associated conservatism are responsible for the significant stiffening of the piping systems and the multiplication of supports and snubbers. The remedy used against the seismic risk seems worse than the pain itself, and safety might be impaired rather than improved. Indeed, system stiffening increases the average load level in normal operation (stresses, fatigue, nozzle loads, etc.); supports do not behave ideally as assumed (friction, rust, etc.) and snubbers are remarkably unreliable. On the other hand, experience with actual earthquakes shows that industrial facilities designed using very simplistic seismic techniques, or even no seismic requirement at all, suffer essentially no damage, even in the case of a large earthquake. This paradox challenges the traditional seismic design techniques, and appeals for revised seismic qualification methods of piping systems. When the assumption of the occurrence of an earthquake event is made in a plant in operation, which has not been designed against seismic criteria, the use of the standard seismic qualification techniques is still more questionable; simplified (quasi-static) techniques offer in this case a valuable and economically justified alternative. The paper describes the application of the quasi-static “modified load coefficient method” to the seismic assessment of the piping in a nuclear plant in operation, designed during the pre-seismic era.     

Is there "feedback" during visual imagery? Evidence from a specificity of practice paradigm.

The specificity of practice hypothesis predicts the development of a sensorimotor representation specific to the afferent feedback available during skill acquisition (Proteau, 1992; Proteau, Marteniuk, Girouard, & Dugas, 1987). In the present investigation, we used the specificity of practice hypothesis to test whether skill acquisition through visual imagery would lead to the development of a sensory-specific movement representation similar to one resulting from actual practice. To accomplish this objective, participants practiced walking a 12-m linear path in one of three practice conditions, full-vision (FV), no-vision (NV), or visual imagery (VI), for either 10 or 100 trials. Knowledge of spatial and/or temporal results (KR) was provided to participants following each trial during this phase. Following acquisition, participants completed 10 NV trials without KR. An analysis of root-mean-squared-error (RMSE) indicated NV participants were more accurate than both FV and VI participants in the transfer condition. We believe the equivalence in transfer RMSE between FV and VI suggests that there are similarities between the movement representations attained by FV and VI practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dam,Environment and Regional Development: Case Study of the Logone Floodplain in Northern Cameroon

The purpose of this paper is a study of environmental change in the Logone floodplain in northern Cameroon following the construction in the 1970s of a dam for a rice irrigation project. This unique ecosystem, designated as a biosphere reserve for supporting an impressive wildlife population, depends on the annual overflowing of the lowland. Several communities living in the plain rely upon water and natural resources of the floodplain to support recession agriculture, the fisheries, wetland rice and livestock. But both persistently poor rainfalls in the Sahel and the adverse impacts of the dam have devastated the area, forcing a large number of people to leave. This paper gives the scope of this situation based on geospatial information and field investigation, and also early results of the floodplain rehabilitation programme conducted since 1994 under the supervision of the World Wildlife Fund. In addition to demonstrating the potential of geomatics technology in environmental hazard assessment, this case study highlights the complexity of water-related issues in areas of conflicting interests. Despite significant improvements achieved by the rehabilitation programme, there is still much work to complete for the area to recover its former biodiversity.     

Design, modelisation and optimisation of high efficiency miniature E-field probes performed on 3D ceramic prisms for SAR evaluation

A comprehensive design methodology is proposed in this paper in order to optimise E-field probes used for evaluating the specific absorption ratio within liquid equivalent tissues exposed to radiofrequency signals. Hybrid analysis approaches are investigated, combining both electromagnetic (three dimensional) and circuit simulators. This design environment can therefore be considered for enhancing E-field detectors’ performances in terms of sensitivity, isotropy, dimensions and shape. Comparisons between simulations and measurements are presented and discussed.     

Integrated instrumental chain for magnetic pulse measurement in strong static field environment

This paper describes an integrated analogue instrumental chain dedicated to measuring magnetic pulses with an amplitude of a few tens or hundreds of microteslas, superimposed to a strong static magnetic field, i.e. 1.5 T. The system features a silicon Hall sensor with nested-chopping-like biasing circuitry, DC Hall voltage compensation, amplifying and multistage filtering. Low-noise performances are achieved by applying 100 kHz spinning current to the Hall device and chopping at 200 kHz to the signal conditioning blocs downstream. The microsystem achieves 20 μT resolution over a 1.6 kHz bandwidth extending from 5 Hz to 1.6 kHz under 1.5 T static field.