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Research note: A time and motion study for two vegetation survey techniques1
Item type: Journal Article • Journal: African Journal of Range & Forage Science • Authors: M.D. Panagos --- Agricultural Research Council, Republic of South Africa P.J.K. Zacharias --- Department of Grassland Science, Republic of South AfricaPrecise costing of vegetation surveys has become a necessity for parastatal research organizations. Competitive and cost‐effective budgets have to be tabled by these parastatals to secure funding for mapping and classification projects. The mean time required to record floristic data... -
Estimating sample size for a small‐quadrat method of botanical survey for application in mixed Bushveld
Item type: Journal Article • Journal: African Journal of Range & Forage Science • Authors: W.G. Dörgeloh --- Applied Natural Sciences, Republic of South AfricaSpecies density and grass density were measured using a small‐quadrat method in eight plant communities in the Nylsvley Nature Reserve, South Africa. The presence of new species in each additional quadrat was used to calculate sample size. A sample size... -
A new line search technique
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: T.A. Adewale F.M. AderibigbeIn this paper the problem of line search, an important step in most multidimensional optimization algorithms, is considered. If conjugate gradient descent is to be used in producing a descent sequence for a given functional f on a Hilbert space... -
Quadratic Pencil of Difference Equations: Jost Solutions, Spectrum, and Principal Vectors
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Murat Adıvar --- Department of Mathematics, TurkeyIn this paper, a quadratic pencil of Schrodinger type difference operator Lλ is taken under investigation to provide a general perspective for the spectral analysis of non-selfadjoint difference equations of second order. Introducing Jost-type solutions, structure and quantitative properties of... -
A simple method for rapid estimation of Ecklonia maxima and Laminaria pallida biomass using floating surface quadrats
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: MD Rothman --- Department of Agriculture, South Africa RJ Anderson --- Department of Agriculture, South Africa JJ Bolton --- Department of Botany, South Africa CJT Boothroyd --- Department of Agriculture, South Africa FA Kemp --- Department of Agriculture, South AfricaIn South Africa two species of kelp, Ecklonia maxima and Laminaria pallida, occur in quantities sufficient for commercial use. Currently, the former species is harvested in large quantities (about 5 000 tonnes wet weight per year) as abalone feed. In... -
Oscillation Theory for a Quadratic Eigenvalue Problem
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: PatrickJ. Browne BruceA. WatsonWe study the Sturm-Liouville problem with quadratic dependence on the spectral parameter, -
Stability and enhancement analysis of a modelled self-balancing verticalized mobility aid using optimal control techniques
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Roger van Rensburg --- Department of Electrical Engineering, South-Africa Nico Steyn --- Department of Electrical Engineering, South-Africa Lambert Trénoras --- Laboratoire d’Ingénierie des Systèmes de Versailles, France Yskandar Hamam --- Department of Electrical Engineering, South-Africa Eric Monacelli --- Laboratoire d’Ingénierie des Systèmes de Versailles, FranceThis research comprises an analytical study of the Gyrolift, a new type of robotic wheelchair mobility aid adapted from the Segway self-balancing human transporter, and suggests additional contributions to its development. The Gyrolift is equipped with an agility module that... -
Development of a stand density management diagram for Santalum album plantations in Karnataka, India
Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Vindhya Prasad Tewari --- Himalayan Forest Research Institute, India Baragur N Diwakara --- Forest Biometry Division, Institute of Wood Science and Technology, IndiaStand density management diagrams are average stand-level models that graphically display the relationship between stand yield, density, height and diameter throughout the various stages of forest development in even-aged stands. These are useful tools for designing, displaying and evaluating alternative... -
The geometry of the moduli space of non-cyclic biquadratic field extensions
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mpendulo Cele --- Stellenbosch University, South Africa Sophie Marques --- Stellenbosch University, South AfricaIn this paper, we investigate the existence of an elementary abelian closure in characteristic not 2 for biquadratic extensions. We discover that it exists for any non-cyclic extension. We make use of it to obtain a classification for this class... -
Periodic solution for perturbed Hamiltonian systems
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Khaled Khachnaoui --- University of Kairouan, TunisiaIn this paper, we study the existence of infinitely many periodic solutions for second-order perturbed Hamiltonian systems. By using variational methods, we obtain new criteria to guarantee the existence of infinitely many periodic solutions using Bolle’s perturbation method. Our results... -
Near universal property of a quadratic form of Hessian discriminant 4
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jesse Ira Deutsch --- , BotswanaA quadratic form is universal if it represents all totally positive integers in a number field. In classical number theory over the rational integers there are some results where a quadratic form takes on all positive integer values except for...