Search
Search results for
We found
37 results for you
-
Root Systems of Some Southern Cape Indigenous Forest Trees
Item type: Journal Article • Journal: South African Forestry Journal • Authors: H. Kotze --- Division of Forest Science and Technology Saasveld Forestry Research Centre, South Africa C.J. Geldenhuys --- Division of Forest Science and Technology Saasveld Forestry Research Centre, South AfricaRoot system form of forest trees were investigated and classified in the southern Cape indigenous forests. Windfalls of some of the dominant canopy species were inspected. Root systems were opened up by mechanical excavations. Tree species displayed the following general... -
Impact of Site Preparation on Wind Resistance of Young Pinus radiata
Item type: Journal Article • Journal: South African Forestry Journal • Authors: J.B. Zwolinski --- , D. G.M. Donald --- Forestry Faculty, W.H. Groenewald --- Division of Forest Science and Technology,Young trees were damaged by winds blowing at 39 m/s speed in the southern Cape Province. The frequency and the extent of wind damage was investigated in an establishment experiment comprising four methods of soil cultivation, two levels of weed... -
Reaction of potatoes to calcium and phosphate levels as affected by wind
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: R. Barnard --- Department of Agronomy, Republic of South Africa N. J.J. Combrink --- Department of Agronomy, Republic of South AfricaIn an attempt to increase the number of mini tubers produced per potato plant, the effect of calcium and phosphorus nutrition was investigated. It is believed that high phosphorus (P) and low calcium (Ca) levels stimulate tuberization. Three nutrient solution... -
A CONCEPTUAL MODEL OF A SILTATION SYSTEM IN SHALLOW LAKES WITH LITTORAL VEGETATION
Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa • Authors: P.J. Weisser --- Facultad de Ciencias,In shallow lakes a siltation system develops when wind driven water turbulence erodes the lake floor, silt is resuspended and transported by means of waterdrift into the littoral vegetation. Here, due to the resistance of the vegetation, the turbulence is... -
THE DIURNAL MIXED LAYER IN LAKES AND OCEANS
Item type: Journal Article • Journal: Southern African Journal of Aquatic Sciences • Authors: JohnL. Largier --- Division of Earth, Marine and Atmospheric Science and Technology, South AfricaIn this review the current ideas on diurnal mixed layers are discussed with reference to several observations. Essentially, solar heating sets up a shallow thermocline which traps and concentrates further influx of heat and momentum in the top few metres... -
Oceanic variability in the western sector of Algoa Bay, South Africa
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: EH Schumann JRS Churchill HJ ZaaymanThe city of Port Elizabeth lies in the western sector of Algoa Bay, and a number of projects have investigated the oceanic temperature, salinity and current structures in the vicinity. This paper analyses past results, and then incorporates measurements of... -
Towards the development of an environmental rule-based model for predicting recruitment in Brazilian sardine Sardinella brasiliensis
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: S Jablonski LFL LegeyA rule-based model was built in order to analyse the effects of environmental variables (wind stress, Ekman transport, turbulence, and sea surface temperature [SST]) on the recruitment of the Brazilian sardine Sardinella brasiliensis. The purpose of modelling was (1) to... -
Prey capture success and chick diet of Damara terns Sterna balaenarum in Namibia
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: J Braby --- Animal Demography Unit, Department of Zoology, South Africa LG Underhill --- Animal Demography Unit, Department of Zoology, South Africa RE Simmons --- Percy FitzPatrick Institute of African Ornithology, Department of Zoology, South AfricaFeeding terns are affected by a variety of environmental conditions. We studied prey capture success of Damara terns Sterna balaenarum in relation to six variables at two breeding colonies in southern Namibia: tidal phase, wind speed, water clarity, cloud cover,... -
The effect of wind direction on flying fish counts
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: PG Ryan --- Percy FitzPatrick Institute, DST/NRF Centre of Excellence, South AfricaFlying fish and squid flushed by a ship's passage are easy to count, but the value of such data is compromised by uncertainty regarding the proportion of individuals flushed. Wind direction relative to the ship's course plays an important role... -
Use of environmental parameters to explain the variability in spawnerrecruitment relationships of Namibian sardine Sardinops sagax
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: CH Kirchner --- National Marine Information and Research Centre, Namibia CH Bartholomae --- National Marine Information and Research Centre, Namibia A Kreiner --- National Marine Information and Research Centre, NamibiaThis study attempts to explain the variability in recruitment of sardine in the northern Benguela and to develop potential models by including environmental information to predict recruitment. Two different recruitment and spawner number datasets were available: a VPA-developed dataset, for... -
Wind farms threaten southern Africa's cliff-nesting vultures
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Ian Rushworth --- Scientific Services, South Africa Sonja Krüger --- Scientific Services, South AfricaWind farms have been shown to cause bird mortality in many studies. Proposals for the development of wind farms in Lesotho, which is core habitat for small and declining populations of the regionally Endangered Bearded Vulture Gypaetus barbatus meridionalis and... -
Discriminating between Thryonomys swinderianus and Thryonomys gregorianus
Item type: Journal Article • Journal: African Zoology • Authors: M. van der Merwe --- Department of Zoology and Entomology, South AfricaOwing to the great similarity in external features between the two cane rat species, Thryonomys swinderianus and T. gregorianus, it is sometimes difficult to distinguish between them, especially when dealing with juveniles and subadults. It becomes even more difficult when... -
A sero-survey to identify the window of vulnerability to measles in infants in north-eastern Nigeria
Item type: Journal Article • Journal: Southern African Journal of Epidemiology and Infection • Authors: Baba Usman Ahmadu --- Department of Paediatrics, Federal Medical Centre, Nigeria Garba Ashir --- Department of Paediatrics, Nigeria Modu Mustapha --- Head of Department, Paediatrics, (UMTH), Nigeria Yakubu Mava --- Head of Department, Paediatrics, Nigeria Isa Saidu --- Department of Paediatrics, Nigeria Jose Ambe --- Department of Paediatrics, NigeriaAs infants lose maternal measles antibodies (MMAs), they experience periods when their antibody levels are insuffcient to protect them against measles. A prospective study was carried out at the University of Maiduguri Teaching Hospital. Sera collected from neonates at birth,... -
Breeding season and breeding potential of the greater cane rat (Thryonomys swinderianus) in captivity in South Africa
Item type: Journal Article • Journal: South African Journal of Zoology • Authors: M. van der Merwe --- Mammal Research Institute, Department of Zoology and Entomology, South AfricaThe cane rat, Thryonomys swinderianus, is an aseasonal breeder. It has a very low fecundity rate with an average litter size of 2.9 (range 1-5), producing a maximum of two litters per annum. The low annual fecundity is the direct... -
Modelling the Zambezi River plume
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: FPJ Nehama --- Department of Oceanography, South Africa CJC Reason --- Department of Oceanography, South AfricaA model for the Zambezi River plume, the largest on the Indian Ocean coast of Africa, is presented and the results of experiments with different discharges and wind forcings are analysed. Although the river plays an important role in the... -
A proportional integral synthesis for a variable speed wind energy conversion system using a permanent magnet synchronous generator
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Francis-Daniel Menga --- Department of Renewable Energy, Cameroon Noël Djongyang --- Department of Renewable Energy, Cameroon Danwé Raïdandi --- Department of Renewable Energy, Cameroon Réné Tchinda --- LISIE, CameroonA wind energy conversion system applied to battery charge is proposed in this paper. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. In order to extract the maximum power, the generator... -
Observations and mechanisms of upwelling in the northern KwaZulu-Natal Bight, South Africa
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: MJ Roberts --- Ocean Sciences and Marine Food Security, South Africa C Nieuwenhuys --- Bayworld Centre for Research and Education, South AfricaNew in situ time-series data were acquired by two ADCP moorings placed on the shelf off Richards Bay on the east coast of South Africa at depths of 25 m and 582 m between October 2009 and August 2010. The... -
Wind energy potential and economic evaluation of WPS using WECSs in three selected locations of Northern Ethiopia
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Shiva Prashanth Kumar Kodicherla --- Department of Civil Engineering, College of Engineering & Technology, Ethiopia Satyanarayana Gaddada --- Department of Electrical and Computer Engineering, College of Engineering & Technology, Ethiopia Nagaraju Shaik --- Department of Construction Management, College of Engineering & Technology, EthiopiaThis paper analyzes wind energy potential and economic evaluation of water pumping system (WPS) employed by various wind energy conversion systems (WECSs). The wind speed data gathered from three different locations of Northern Ethiopia are analyzed using the Weibull probability... -
Genetic structure of wild and domesticated grasscutters (Thryonomys swinderianus) from south-western Nigeria
Item type: Journal Article • Journal: African Zoology • Authors: Oluwakayode M Coker --- Department of Wildlife and Ecotourism Management, Nigeria Abosede O Omonona --- Department of Wildlife and Ecotourism Management, Nigeria Olusegun A Fagbohun --- Department of Veterinary Microbiology and Parasitology, Nigeria Cortney Pylant --- Department of Wildlife Ecology and Conservation, USA James D Austin --- Department of Wildlife Ecology and Conservation, USAGrasscutter (Thryonomys swinderianus) is a large rodent distributed across sub-Saharan Africa that is highly valued as a source of protein. There has been little effort to evaluate the genetic structure of grasscutters despite long-term harvesting pressure and over 40 years... -
Feasibility of electricity generation using WECS in the selected locations of Tigray region (Ethiopia)
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Shiva Prashanth Kumar Kodicherla --- Department of Civil Engineering, College of Engineering & Technology, Ethiopia Satyanarayana Gaddada --- Department of Electrical and Computer Engineering, College of Engineering & Technology, EthiopiaThis paper presents the feasibility of electricity generation using WECS in the selected locations of Tigray region in Ethiopia. Weibull parameters were obtained using the energy pattern factor method (EPFM). A linear agreement was observed between mean wind speed and... -
Socio-economic and environmental analysis of wind power projects as viable renewable energy resources in Kenya
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Victor Ongoma --- Key Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), People’s Republic of ChinaThe demand for power in Kenya is on the increase with the ongoing growth of the country’s economy. There is a need for the country to balance energy efficiency, sustainability and low-carbon technologies. This entails drafting and implementing policies and... -
Applications of small-scale, stand-alone wind energy conversion systems in rural Cross River State, Nigeria
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Fidelis I. Abam --- Energy, Exergy and Environment Research Group (EEERG), Mechanical Engineering Department, Nigeria Olayinka S. Ohunakin --- The Energy and Environment Research Group (TEERG), Department of Mechanical Engineering, NigeriaThe study presents the wind energy potential (WEP) for six locations in Cross River State, Nigeria. The objective of the study was to assess the WEP of the selected sites for electricity generation, using small size wind energy conversion systems... -
The effect of pre-harvest wind damage on post-harvest quality of ‘Triumph’ persimmon fruit
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Pesanai Zanamwe --- Department of Botany and Biotechnology, South AfricaThe post-harvest quality of ‘Triumph’ persimmon fruits grown in the Western Cape, South Africa varies with seasons. Poor post-harvest fruit quality is assumed to be associated with seasons that are characterized by violent wind occurrences. This study was carried out... -
Conservation buffer sizes derived from movement data of adult Cape vultures (Gyps coprotheres) in South Africa
Item type: Journal Article • Journal: African Zoology • Authors: Jan A Venter --- School of Natural Resource Management, South Africa Francis R Martens --- School of Natural Resource Management, South Africa Kerri Wolter --- VulPro, South AfricaThe endangered Cape vulture (Gyps coprotheres) is facing a new emerging threat, e.g. wind energy development. Given their vulnerability to wind energy infrastructure, there is a necessity to establish proactive measures that could potentially mitigate future collisions, such as conservation... -
Using radar technology to assess visual monitoring accuracy of Cape Vulture movements
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Frowin K Becker --- Department of Conservation Ecology and Entomology, South Africa Rhonda L Millikin --- EchoTrack Inc., Canada Alison J Leslie --- Department of Conservation Ecology and Entomology, South AfricaSouth Africa’s expanding wind energy industry is providing much needed alleviation from an ongoing energy crisis. Its development, however, does bear environmental repercussions, which most notably include its impact on birds. Collision risks, habitat loss, and barrier effects are amongst... -
Wave setup at Tristan da Cunha
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: PL Woodworth --- , United KingdomWave setup was investigated using data from tide gauges in a small harbour at the island of Tristan da Cunha in the South Atlantic Ocean. Frequent examples of wave setup were found during the period 1986–1992, but were much less... -
On a collision course? The large diversity of birds killed by wind turbines in South Africa
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: V Perold --- , South Africa S Ralston-Paton --- , South Africa P Ryan --- , South AfricaWind energy is a clean, renewable alternative to fossil fuel-derived energy sources, but many birds are at risk from collisions with wind turbines. We summarise the diversity of birds killed by turbine collisions at 20 wind energy facilities (WEFs) across... -
Characterising the seasonal cycle of wind forcing, surface circulation and temperature around the sub-Antarctic Prince Edward Islands
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: T Toolsee --- , South Africa T Lamont --- , South Africa M Rouault --- , South Africa I Ansorge --- , South AfricaLocated between the sub-Antarctic Front and the Antarctic Polar Front, the Prince Edward Islands (PEIs) provide an essential breeding ground for top predators and are an ideal location to investigate disturbances linked to climate change. This study provides the first... -
Three-dimensional modelling of the circulation in False Bay, South Africa
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: F Coleman --- , South Africa GPJ Diedericks --- , South Africa AK Theron --- , South Africa J Lencart e Silva --- , United KingdomFalse Bay is the largest coastal embayment along South Africa’s coastline. Despite notable contributions of various historical observational studies on the circulation within False Bay and the associated physical processes driving these flows, there remains significant uncertainty largely because the... -
Wind and solar power deployment in India: Economic aspects and policy implications
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Alok Das --- , India Hardik K. Jani --- , India Garlapati Nagababu --- , India Surendra Singh Kachhwaha --- , IndiaEconomic assets play a key role in the growth of renewable power projects and depend on financial scenarios and policy structures offered by government policies. The focus of the study is to assess the impact of the existing economic scenarios... -
Salt marsh erosion in a microtidal estuary
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: T Riddin --- , South Africa JB Adams --- , South AfricaSalt marshes protect estuary banks from erosion by acting as buffers between marine and terrestrial environments. Residents living near the Breede River estuary, Western Cape Province, South Africa, raised concerns about ongoing erosion evident at Groenpunt, the main salt marsh... -
The innovation system for diffusion of small wind in Kenya: Strong, weak or absent? A technological innovation system analysis
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Faith Hamala Wandera --- , KenyaKenya is currently seeking to promote rural electrification through a decentralized approach for deploying renewable energy. This article asks whether an innovation system is in place to support the diffusion of small wind which could complement rural electrification using solar... -
The ecology of coastal wetland ponds created by diamond mining in southern Namibia. 2. Saltmarsh vegetation
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: L Maritz --- , South Africa D Pillay --- , South Africa GM Branch --- , South AfricaDiamond mining on the southern Namibian coastline has created multiple large coastal ponds of up to 380 000 m2 adjacent to the coastline, as the sea overtops erected seawalls or seeps into excavated areas. These ponds span ages of 1–38... -
Analysis of offshore wind energy potential for power generation in three selected locations in Nigeria
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Mamman Rabiu Onoruoiza --- , Nigeria Oyewole Adedipe --- , Nigeria Sunday Albert Lawal --- , Nigeria Oluwafemi Ayodeji Olugboji --- , Nigeria Victor Chiagozie Nwachukwu --- , NigeriaThe rise in the global carbon footprint arising from fossil fuel sources has necessitated the need to explore sustainable and eco-friendly sources of energy. Wind as a source of renewable energy has been underutilized in Nigeria and this study is... -
Wind- and eddy-driven upwelling over submarine canyons inshore of the northern Agulhas Current
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: G Rautenbach --- Nelson Mandela University, South Africa J Hermes --- , South Africa I Halo --- , South Africa T Morris --- , South Africa J Veitch --- , South AfricaThe iSimangaliso Wetland Park, located along the coastline of northern KwaZulu-Natal, hosts South Africa’s only subtropical coral reef system. Episodic upwelling events are observed inshore and at the heads of Diepgat, Leadsman and Leven canyons within the iSimangaliso Wetland Park... -
Lack of evasive behaviour by a Martial Eagle Polemaetus bellicosus on impact with a turbine blade at a South African wind farm: causes and mitigations
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Robert E Simmons --- University of Cape Town, South Africa Marlei Martins --- , South AfricaWe describe a collision of Africa’s largest raptor, the Martial Eagle Polemaetus bellicosus with a spinning blade at a South African wind farm in the Eastern Cape in July 2016, and the abandonment of the territory following a second fatal... -
Techno-economic and environmental assessment of battery integrated wind farm siting across offshore Nigeria
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Gbubemi Kevin Akporhonor --- Energy and Environment Cranfield University, United KingdomThis study investigates the economic, technical, and environmental impacts of integrating a battery energy storage system (BESS) with an offshore wind farm near Koko Sea Port, Nigeria. As renewable energy curtailment increases and Nigeria’s energy demand grows, energy storage systems...