1,720,971 research outputs found
Proposed interventions for the technical industrial and vocational enterprise training (TIVET) sector in Kenya
No full textThe mechanical properties of sisal and loofah fibres and their composites resulting from the reinforcement of epoxy resins
No full textSisal and Loofah are two amongst a number of
natural fibres that are found in Kenya. While Sisal is
cultivated commercially in large scale plantations,
Loofah grows in the wild. The traditional uses for Sisal
fibre include the making of rope, sacks, carpets, bags
and cushioning upholstery. Loofah fibre is normally used
as washing sponges, pillowing material, filter material
for oil presses and for scouring and cleaning machinery.
Extensive research has been carried out on the
effects of Longitudinally Aligned continuous and Randomly
Aligned Discontinuous Sisal fibres on base materials such
as Mortar, Cement and Epoxy resin. This research has been
conducted within the Departments of technical
Engineering and Civil Engineering of the University of
Nairobi. Mutuli (1979) carried out research on the
mechanical properties of sisal fibre reinforced
composites. While his results on the tensile properties
conformed with the general theory on fibre reinforced
composites, they lacked certain features that would
normally arise at low and high fibre volume fractions.
otieno and Ogango (1991) carrred out some work on the
effects of Loofah fibre on the tensile stress and the
tensile strain of Epoxy reSln. Their results however were
not conclusive.
One of the aims of this research is to determine
the effect of fibre volume fraction on the tensile
strength, tensile strain, and Elastic Modulus of Sisal
reinforced and Loofah reinforced Epoxy resin composites.
Comparison of the results from both the existing theory
and the present work will be done. The volume fraction at
which the composite properties are a minimum or are
critical will be identified. The relationship between the
Multiple Matrix Fracture (M.M.F.) phenomena and the fibre
volume fraction will be determined. The interfacial bond
strength and the fibre critical length will also be
evaluated. In addition the effects of the varying cross -
sectional area of sisal fibre and the differing Poissons
ratios of sisal fibre and Epoxy resin matrix will be
examined.
The present results show that sisal fibre when
used to reinforce Epoxy resin does lead to definate
improvements in the tensile properties of the matrix. The
results also show that designs must be based on specific
fibre volume fractions. Within the M.M.F. range,
containers for liquids will be regarded as having failed
whereas pure structural components may still find use.
In contrast, Loofah fibre reinforcement of Epoxy
resin results into a reduction of the tensile properties
of the matrix
PROPOSED INTERVENTIONS FOR THE TECHNICAL INDUSTRIAL AND VOCATIONAL ENTERPRISE TRAINING (TIVET) SECTOR IN KENYA
Get PDFThis paper presents a brief overview of TIVET in Kenya (history and present), the laws governing TIVET, and its structure and challenges today. A robust review of various relevant concepts that are in use in TVET is presented and solutions to identified shortcomings of the Kenyan TIVET system proposed. The Develop a Curriculum, (DACUM) and the Systematic Curriculum and Instructional Development (SCID) methods of developing demand led and competency based occupational profiles and arising curricula are recommended for adoption in the country’s TIVET system. It is further recommended that On-Job-Training is introduced in addition to the creation of strong linkages with industry in order to increase relevance to and absorption of TIVET graduates in industry. The paper touches on the issues of specification and sourcing of equipment and identifies possible source markets. More study is recommended in order to obtain a complete and comprehensive assessment of TIVET in the country
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
IMPROVEMENT OF TECHNICAL EDUCATION IN PUBLIC TECHNICAL SECONDARY SCHOOLS (ECOLE TECHNIQUE OFFICIEL - ETOS) IN RWANDA
Get PDFThis paper presents a brief review of the state of technical education in Rwanda based on a study conducted in 2007, with pertinent recommendations. The background of technical education in the country is appreciated first, and then followed up with a situational analysis. Thereafter, a 5-year implementation project plan proposal, to address the identified shortcomings, needs, and expectations of government is advanced. The need to raise access to post tronc commun (post O-Level) technical training is addressed within this proposal with a specific interest to increase the capacity and range of programmes running in the existing ETOs, and the introduction of new ETOs where deemed necessary. The establishment and sustenance of a good quality technical education system is also given consideration in this proposal for effective and efficient rehabilitation of existing physical facilities and the purchase of new and appropriate training equipment. Simultaneously, considerations for increasing the number of technical teachers in the system to a determined optimum level while setting minimum acceptable qualifications for technical teachers are advanced. Implementation of this proposal is expected to contribute greatly to the continuous development of a labour pool with skills that are relevant to and adequate for the needs of the economy
Detection and monitoring of fatigue damage in SMCR26 specimens using spate, for a constant mean stress – a qualitative approach
No full textThe primary aim of the work presented here was to establish the use of thermoelastic measurements in detecting the presence of damage and its subsequent accumulation in sheet moulding compound (SMCR26). To this end, several dog bone shaped specimens of SMCR26 were cycled at a constant mean stress of 38.87 MPa and at varying stress amplitudes, the latter in order to investigate any dependencies on stress amplitude. Surface scans were taken from each specimen at various stages in their load history using the Stress Pattern Analysis by Thermal Emission (SPATE) measurement equipment. The first scan obtained from each specimen was used to determine its initial state of damage, while subsequent scans were used to monitor the accumulation of damage. The thermoelastic signal in the initial and subsequent scans exhibited different magnitudes and distribution for the different specimens, which denoted heterogeneity of the SMCR26 specimens and of the occurrence and accumulation of damage. This was in sharp contrast to the uniform thermoelastic signal that is emitted from the surfaces of cycled, undamaged homogeneous materials. The absence of any apparent relationship between the stress amplitude and the accumulation of damage in the tested specimens was thought to be a result of the in-homogeneity inherent in SMCR26, and of the heterogeneous nature of the accumulation of damage, rather than a limitation of the thermoelastic equipment used. The results obtained in this work demonstrated SPATE to be a fast and useful means of detecting the presence of damage and of monitoring its accumulateKeywords: Sheet Moulding Compound (SMC), fatigue, damage Journal of Agriculture, Science and Technology Vol. 7(1) 2005: 91-12
Dimensioning of dog bone specimens and numerical analysis of the effects of different fillet radii, clamp area and pinhole loading on the stresses in such specimens
No full textThe effects of different fillet radii, clamp area dimensions, and pinhole loading through a hole located in the clamp area of a dog bone specimen were investigated using the Finite Element Analysis (FEA) software Abaqus. Changes in the fillet radius were shown to have little effect on the distribution and magnitude of the von Mises stresses. Different dimensions of the clamp section gave different von Mises stress distributions within the clamp section, with the maximum values remaining within the gauge section, thus implying that limitations of available cutters and material could be accommodated by varying the dimensions of test specimens. Introduction of pinhole loading in order to minimise torsion, led to a shift of the maximum von Mises stress from the gauge section to the edge of the pinhole, an indication that the benefits of minimising torsion required to be weighed carefully. The observed shift was only significant however, for failure load levels and for cyclic loading. A set percentage change rather than the absolute convergence of the von Mises stresses was shown to be a more economical way of arriving at an optimal mesh density, a characteristic that was seen to vary from one location to another. African Journal of Science and Technology Vol. 5(2) 2004: 60-7
Mixing And Reuse Of Polymer Laser Sintering Powders To Ensure Homogeneity - A Review
Get PDFArticleSelective laser sintering is one of the most common additive manufacturing technologies for polymeric materials. However, the technique is limited due to the high cost of the few available feedstock materials. Besides, laser sintering is a high-temperature process, which subjects polymeric materials to thermal stresses, resulting in the degeneration of powder. Besides, only a small portion of the powder fed into the built chamber is used in the printing of components. Hence, the need to recycle the used polymeric powder. This is achieved by mixing used and virgin powder in the ratios stipulated by the manufacturers of the powders. This review investigates the types of powder, types of mixing mechanism, parameters that affect efficient mixing, the homogeneity of mixed powder, mechanisms of segregation, and selection of the most appropriate mixers in the context of selective laser sintering of polymeric materials
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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