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Search Results: 1 - 10 of 572968 matches for " A.F. Van der Merwe "
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S. Matope,A.F. Van der Merwe,Y.I. Rabinovich
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: Van der Waals forces and other adhesive forces impose great challenges on micro-material handling. Mechanical grippers fail to release micro-parts reliably because of them. This paper explores how the problematic Van der Waals forces may be used for micro-material handling purposes using surface roughnesses generated by e-beam coatings of copper and silver on silicon. An atomic force microscope, model Asylum MFP 3 D-Bio with version 6.22A software, was used to measure the forces exerted by the surfaces. A silver coating of 1.41 nm rms surface roughness value is found to exert the highest Van der Waals force, followed by a copper coating of 2.72 nm rms; a copper coating of 217 nm rms exerts the least force. This implies that, in a reliable micro-material handling system, these coatings are suitable for the interactive surfaces of the placement position, micro-gripper, and the pick-up position respectively. AFRIKAANSE OPSOMMING: Van der Waalskragte en ander bindingskragte hou steeds groot uitdagings in vir mikromateriaalhantering. As gevolg van hierdie bindingskragte stel meganiese gryptoerusting nie die mikro-partikels vry nie. Hierdie artikel ondersoek hoe die Van der Waalskragte gebruik kan word vir die mikro-materiaalhanteringsproses deur die gebruik van oppervlakgrofheid gegenereer deur ’n e-straal-laagbedekking van koper en silwer op silikon. ’n Atoomkrag mikroskoop, model Asylum MFP 3 D-Bio met weergawe 6.22A programmatuur, is gebruik om die kragte deur die oppervlakke uitgeoefen te meet. Daar is gevind dat ’n silwer laagbedekking met ’n oppervlakgrofheid van 1.41nm wortel-gemiddelde-kwadraat (wgk) die hoogste Van der Waalskrag uitoefen, gevolg deur ’n koper laagbedekking met ’n oppervlakgrofheid van 2.72nm wgk; ’n koper laagbedekking met ’n grofheid van 217nm wgk het die kleinste krag uitgeoefen. Dit impliseer dat, vir ’n betroubare mikro-materiaalhanteringsisteem, hierdie laagbedekkings geskik is vir die interaktiewe oppervlakke van die plasingsposisie, die mikro-gryper en die optelposisie.
S. Matope,A.F. van der Merwe,R. Nemutudi,M. Nkosi
South African Journal of Industrial Engineering , 2012,
Abstract: ENGLISH ABSTRACT: This paper focuses on the employment of copper and aluminium in a micro-material handling system actuated by Van der Waals forces. Electron beam (e-beam) evaporator deposited both materials on a silicon substrate at a rate of 0.6-1.2 Angstroms/second, vacuum pressure between 2x10-6 and 3x10-6mbar, and at a current less than 10mA. A Veeco NanoMan V Atomic Force Microscope with Nanoscope version 7.3 software was used to analyse the root mean square (rms) surface roughnesses of the generated topographies. Rumpf-Rabinovich’s rms formula was used to determine the Van der Waals forces exerted by the surfaces. It was synthesised that an e-beam deposition of 7 minutes’ duration on both materials produced an optimum micro-material handling solution, with copper suitable for the pick-up position and aluminium for the placement position. AFRIKAANSE OPSOMMING: Die fokus van die artikel is op die gebruik van koper en aluminium in ‘n mikromateriaalhanteringstelsel, aangedryf deur Van der Waalskragte. ‘n Elektronstraal-verdamper plaas albei materiale op ‘n silikonbasis teen ‘n tempo van 0.6-1.2 Angstrom/sekonde, vakuumdruk tussen 2x10-6 en 3x10-6mbar, en teen ‘n stroom van minder as 10mA. ‘n Veeco NanoMan V Atomic Force mikroskoop, met Nanoscope 7.3 program-matuur is gebruik om die wortel-gemiddelde-kwadraat (wgk) oppervlak ruheid van die gegenereerde topografie te analiseer. Rumpf-Rabinovich se wgk-formule is gebruik om die Van der Waalskrage wat deur die oppervlaktes uitgeoefen word te bepaal. Dit is vasgestel dat ‘n elektronstraalafsetting van 7 minute op albei materiale die optimale materiaalhanteringoplossing bied, met koper geskik vir die optelposisie en aluminium vir die plasingsposisie.
Book Reviews
D. van der Horst,Albert Herrmann,A.F.P. Hulsewé,F.S. Drake
Bijdragen tot de Taal-, Land- en Volkenkunde , 1969,
Abstract: - D. van der Horst, Albert Herrmann, An historical atlas of China. New edition by Norton Ginsburg. Djambatan N.V., Amsterdam 1966. 88 pp. - A.F.P. Hulsewé, F.S. Drake, Symposium of historical, archaeological and linguistic studies on Southern China, South-East Asia and the Hongkong region. Proceedings of a meeting held in September 1961 as part of the Golden Jubilee Congress of the University of Hongkong. Hongkong, Hongkong University Press, 1967. X + 370 pp. - D.R. Jonker, Liu Shih-Shun, One hundred and one Chinese poems. With English translations and preface. UNESCO Collection of Representative Works, Chinese Series; Hong Kong University Press, 1967. XXXIX + 173 pp. - M.A.P. Meilink-Roelofsz, A. Das Gupta, Malabar in Asian trade 1740-1800. Cambridge South Asian Studies. Cambridge U.P. 1967. XII, 204 blz. Met krt. - C.R. Hooijer, Per Sorensen, Ban-Kao, Neolithic settlements with cemeteries in the Kanchanaburi Province. 140 pp., 140 plates, 4 maps, figs. The Thai-Danish Prehistoric Expedition 1960-62, Archaeological Excavations in Thailand, Vol. II. Munksgaard, Copenhagen, 1967. - C.R. Hooijer, H.R. van Heekeren, Sai-Yok, Stone-age settlements in the Kanchanaburi Province. 129 pp., 33 plates, 47 figs. The Thai-Danish Prehistoric Expedition 1960-1962, Archaeological Excavations in Thailand, Vol. I. Munksgaard, Copenhagen, 1967., Eigil Knuth (eds.) - Th. G. Th. Pigeaud, C. Hooykaas, Bagus Umbara, Prince of Koripan. The story of a prince of Bali and a princess of Java, illustrated on palm leaves by a Balines artist. With Balinese text and English translation by Dr C. Hooykaas, Reader in Old Javanese, University of London. Published by the Trustees of the British Museum, London, 1968. 55 pp., 9 illustrations, 31 x 25 cm. - H.J. de Graaf, Soemarsaid Moertono, State and statecraft in old Java: A study of the late Mataram period 16th to 19th century. Monograph series Modern Indonesia Project. Southeast Asia Program Department of Asian Studies. Cornell University Ithaca New York 1968. - M.A.P. Meilink-Roelofsz, John Bastin, Sir Thomas Stamford Raffles. With an account of the Raffles-Minto manuscript collection presented to the India Office Library on 17 July 1969 by the Malaysia-Singapore Commercial Association. The Ocean Steamship Company Limited, Liverpool 1969. 33 pp. - C. Fasseur, W.F. Wertheim, Ketters en kwezels. Regenten en rebellen. Laverman N.V., Drachten, 1968. 212 blz., A.H. Wertheim-Gijse Weenink (eds.) - S. Kooijman, Tropical Man. Continuation of International Archives of Ethnography. Yearbook of the Anthropology Department of the Royal Tropical In
The Properties of Terrestrial Laser System Intensity for Measuring Leaf Geometries: A Case Study with Conference Pear Trees (Pyrus Communis)
Mathilde A.F. Balduzzi,Dimitry Van der Zande,Jan Stuckens,Willem W. Verstraeten,Pol Coppin
Sensors , 2011, DOI: 10.3390/s110201657
Abstract: Light Detection and Ranging (LiDAR) technology can be a valuable tool for describing and quantifying vegetation structure. However, because of their size, extraction of leaf geometries remains complicated. In this study, the intensity data produced by the Terrestrial Laser System (TLS) FARO LS880 is corrected for the distance effect and its relationship with the angle of incidence between the laser beam and the surface of the leaf of a Conference Pear tree (Pyrus Commmunis) is established. The results demonstrate that with only intensity, this relationship has a potential for determining the angle of incidence with the leaves surface with a precision of ±5° for an angle of incidence smaller than 60°, whereas it is more variable for an angle of incidence larger than 60°. It appears that TLS beam footprint, leaf curvatures and leaf wrinkles have an impact on the relationship between intensity and angle of incidence, though, this analysis shows that the intensity of scanned leaves has a potential to eliminate ghost points and to improve their meshing.
Haemonchus spp. in sheep farmed under resource-poor conditions in South Africa - effect on haematocrit, conjunctival mucous membrane colour and body condition
A.F. Vatta,R.C. Krecek,M.J. Van der Linde,P.W. Motswatswe
Journal of the South African Veterinary Association , 2012, DOI: 10.4102/jsava.v73i3.572
Abstract: A longitudinal study was conducted on the differential faecal egg counts, haematocrits and body condition scores of sheep belonging to resource-poor farmers at Rust de Winter, Gauteng province, and Kraaipan, North West Province, South Africa. The animals were scored for level of anaemia using the FAMACHA(c) method, an assay for the clinical evaluation of anaemia caused by Haemonchus spp. Periods of higher Haemonchus egg counts occurred from October to March for sheep at Rust de Winter and from September/October to February or April for sheep at Kraaipan. Lower haematocrit values were registered during these periods as was a higher incidence of anaemic conjunctival mucous membrane colour scores compared to the period April to September. No clear relationship between the faecal egg counts and the body condition scores was evident. Although wider application of the FAMACHA(c) system in sheep raised by resource-poor farmers should be investigated, the present study indicates that this method may certainly prove to be a valuable worm control strategy for such livestock owners.
Retroperitoneal less donor nephrectomy
Van Der Merwe, A.;Bachmann, A.;Heyns, C. F.;
International braz j urol , 2010, DOI: 10.1590/S1677-55382010000500010
Abstract: donor nephrectomy with laparo-endoscopic single site (less) surgery has been reported via the transperitoneal approach. we describe a novel technique of retroperitoneal donor nephrectomy using a single surgical incision in the groin, below the abdominal skin crease or "bikini line". the less groin incision offers superior cosmesis, while the retroperitoneal approach has distinct advantages, such as the ability to identify the renal vessels early. the new procedure has been performed in two obese patients (body mass index 32 and 33 kg/m2, respectively). the operative times were 4 and 5 hours, warm ischemic times 135 and 315 seconds, blood loss 100 and 250 ml, and hospitalization 3 and 2 days, respectively. retroperitoneal less donor nephrectomy through a single, inconspicuous groin incision is feasible and safe. further evaluation of the technique in a larger patient cohort is indicated.
S. Faber, Strafrechtspleging en criminaliteit in Amsterdam 1680-1811. De nieuwe menslievendheid
A.F. van den Hoeven
BMGN : Low Countries Historical Review , 1985,
Subjective Well-being of Primary Health Care Patients in the Western Cape, South Africa
MC le Roux, A Kagee, M Van der Merwe, F Parker
South African Family Practice , 2008,
Abstract: Background: Patients living with a chronic illness face many challenges in their lives such as an altered body image, physical pain or discomfort, the need for frequent medical visits and the negative side effects of treatment. To this extent their sense of personal or subjective well-being may be compromised by the severity and chronicity of their illness. The aim of the present study was to explore the level of subjective well-being and its relationship with coping, quality of life and support from family and friends among a sample of Black South Africans attending semi-rural public clinics for treatment for hypertension and diabetes. This study was part of a larger project on treatment adherence to medication among patients living with these conditions. Methods: A convenience sample of 117 patients aged between 22 and 82 years (M=52.36, SD=13.24), receiving treatment for hypertension (n=79) or diabetes (n=24) at three primary health care clinics in the Boland area of the Western Cape were asked to participate in this study. Of the total sample, 14 (12%) were diagnosed with both conditions. Participants were asked to complete a questionnaire battery consisting of the Satisfaction with Life Scale, the Coping Strategy Indicator, the Functioning Assessment of Non-Life Threatening Conditions and the Perceived Social Support Scale. Results: The mean score of the Satisfaction with Life Scale was 28.70, which was significantly higher than those of other studies using this mea-sure. In order to address the problem of experiment-wise error, commonly associated with the use of multiple statistical comparisons, we used the Bonferronni correction in arriving at probability levels in determining statistical significance. On average the sample as a whole appeared to be largely satisfied. The mean scores on the two of the subscales of the Coping Strategy Indicator were significantly different from those obtained from other South African samples. On the Functioning Assessment of Non-Life Threatening Conditions, the mean scores on the subscales but not the total score was significantly higher than other South African samples. Conclusions: In general, participants scored significantly higher on all of the measuring instruments compared with other South African samples, indicating high levels of life satisfaction, coping, and support from others. We found no relationship between life satisfaction and gender. Age however correlated positively with satisfaction with Life, Support from family, social and emotional well being and Quality of Life, which concurs with the findings of previous studies. Contrary to other studies we found a significant negative correlation between education and SWLS but no relationship between employment and SWLS. Our sample also reported higher levels of support from friends and family that were significantly higher than those of other South African samples. The mean scores on all the subscales of the Coping Strategy Indicator were higher
Die begrip “rentmeesterskap” in die gemeentebouproses
J.F. van der Merwe,C.J.A. Vos
HTS Theological Studies/Teologiese Studies , 2009, DOI: 10.4102/hts.v58i1.536
Abstract: The concept of stewardship in the process of extending the local church This study looks at the biblical principal of stewardship in the context of building up the local church. The study starts with the methodological principles of Practical Theology and various models of the process of building up the local church. Traditionally stewardship was regarded as the principle that encouraged Christians to give monetary contributions towards extending the local church. The study makes it clear that a much broader and biblical understanding of stewardship is necessary. It looks at the different dimensions of stewardship and the effect the stewardship principle has on the Christian’s use of resources, time, spiritual gifts, possessions, as well as on creation, life and the Gospel of Jesus Christ.
Emergencies in Urology
A van der Merwe
African Journal of Urology , 2008,
Abstract: Emergencies in Urology Authors: M. Hohenfellner and RA Santucci Publisher Springer
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