146 research outputs found
Rethinking Educati. in Ethiopia. Tekeste Negash, Nordiska Afrikainstitutet, Uppsala, 1996, 118 pages .
No full textTekeste Negash, the author of The Crises ofEthiopia Education: some implications fornation building (t 990), has' recently comeout with a book, Rethinking Education inEthiopia. He analyses educational issues andpolices in Ethiopia from the historical andcontemporary perspectives in relation to thedevelopment of the country. He alsoforwards recommendations some. of whichare in fact controversial
Latency Bounds for Memory-Based FFTs with Applications in OFDM Communication
No full textFuture communication systems require low latency Fast Fourier transform (FFT)computation with a small cost of area. In this study, a memory-based FFT processorwith low latency is designed. To reduce latency and maintain constant outputsample rate, a scheduling method suitable for input sample rate and clock rateis used in the radix-2 butterfly processing elements. The scheduling scheme employsa combination of ASAP and ALAP scheduling strategies. A mathematicalexpression that models FFT’s latency is given. The size of FFT, the input samplerate, and the number of processing elements are the input parameters of the expression.The effect of using pipelined processing element is also studied. Lastly,the proposed low latency design is compared with other low-latency FFT designs.The result shows that, in the 4G LTE application scenario, our memory-based designcan do the FFT computations faster with a small area
Latency Bounds for Memory-Based FFTs with Applications in OFDM Communication
No full textFuture communication systems require low latency Fast Fourier transform (FFT)computation with a small cost of area. In this study, a memory-based FFT processorwith low latency is designed. To reduce latency and maintain constant outputsample rate, a scheduling method suitable for input sample rate and clock rateis used in the radix-2 butterfly processing elements. The scheduling scheme employsa combination of ASAP and ALAP scheduling strategies. A mathematicalexpression that models FFT’s latency is given. The size of FFT, the input samplerate, and the number of processing elements are the input parameters of the expression.The effect of using pipelined processing element is also studied. Lastly,the proposed low latency design is compared with other low-latency FFT designs.The result shows that, in the 4G LTE application scenario, our memory-based designcan do the FFT computations faster with a small area
Litter decomposition of six tree species on indigenous agroforestry farms in south-eastern Ethiopia in relation to litterfall carbon inputs and modelled soil respiration
No full textThe indigenous agroforestry systems practised by smallholders in south-eastern Ethiopia have high biodiversity and productivity. However, little is known about their carbon (C) inputs and outputs. We carried out a 1-year litterbag study to determine leaf litter decomposition k constants for six woody species common to these agroforestry systems. The k values were then used to calculate the decomposition C losses from measured litterfall C fluxes and the results compared to modelled soil respiration (Rs) C losses. Litterbag weight loss at the end of the year was 100% or nearly so, k values 2.582-6.108 (yr(-1)) and half-life 41-112 days. k values were significantly (p = 0.023) correlated with litter N contents, nearly so with C/N ratios (p = 0.053), but not with other nutrients (Ca, Mg and K), and negatively correlated with temperature (p = 0.080). Using species, farm elevation, temperature and litter quality as predictors, partial least squares regression explained 48% of the variation in k. Depending on species, estimated decomposition C losses from litterfall were 18 to 58% lower than annual litterfall C inputs. Using a heterotrophic respiration (Rh) to Rs ratio of 0.5, modelled Rh C losses were 89 to 238% of litterfall decomposition C losses estimated using k values. However, using an Rh/Rs ratio of 0.27, which is appropriate for tropical humid forests, Rh C losses were 11 to 138% of estimated litterfall decomposition C losses. Our decomposition and soil respiration estimates indicate that litterfall is sufficient to maintain soil organic C contents and thereby the soil fertility of these unique agroforestry systems.Peer reviewe
Perception of African Youth on Personal Computer Utilization: The Case of Ethiopia and Rwanda
No full textThe tendency to pursue innovativeness and adopt new technologies has been found more likely with younger individuals and a strong relationship between attitude and personal computer (PC) utilization has been found. However, research in these areas is mainly focused on high-income countries. Do these findings hold for low-income countries? What are the perceptions of African youth on the factors that impact PC use? There is a dearth of micro-level studies that promote understanding about the behavior of individuals in low-income countries. This study looked at demographic data including age, gender, grade level, region, and prior experience among 228 youth from Ethiopia and Rwanda. PC utilization constructs including complexity, long-term consequences, and facilitating conditions were studied. The author found access to PCs at least three times a week and providing structured computer training programs as major factor for increased PC utilization. Computer centers with more female instructors were found to have larger female enrollment. The author also found younger groups (15 year olds and younger) disagreed about PC utilization factors. Implications and directions for future research are also included
The use of Lagrange multipliers and Kuhn-Tucker's theory in optimization problems, 1987
No full textLagrange multipliers, penalty methods, and Kuhn-Tucker's theory are some important mathematical tools used in optimization problems. These tools are discussed so that one can appreciate the current areas of optimization research. Moreover, since extensive research work exists for linear optimization problems, only nonlinear applications are discussed
An analysis of an equation governing the transverse displacement of a beam, 1998
No full textIn this thesis, we study the transverse displacement of a multi-layered beam. The beam is made up of three layers. The middle layer has hysteresis while the outer layers are elastic. The equation governing the transverse motion of the beam is simplified, and a model equation that retains the essential features of the original equation is analyzed. In addition, we provide a method of approximation of the model equation using splines
A mathematical model of urban traffic flow
No full textWe study a particular traffic network where the volume of traffic is regulated by controlling the traffic signals at each intersection. We make an appropriate choice of uw where v=0,..., k, which will enable us to control the traffic signals. Our objective is to move one traffic configuration to another (ideal or appropriate) traffic configuration so we may stop configuration within our network. Numerical examples were used to specifically demonstrate the effect of uv to our model. The calculations were implemented using a mathematical tool, MathCad Plus
Optimum problem involving integral equations, 1987
No full textExtremum problem involving certain linear integral equations with linear constraints is considered. We first give a discussion of integral equation with emphasis on the resolvent. Then, we use the resolvent method to convert an extremum problem involving a state and control into one where only the control appears. In the form involving just the controls, the optimal controls are easy to characterize
Pre-slaughter, slaughter and post-slaughter defects of skins and hides at the Sheba Tannery and Leather Industry, Tigray region, northern Ethiopia
No full textSkins and hides are perishable resources that can be damaged by parasitic diseases and human error, which result in downgrading or rejection. This study was conducted to identify defect types and to determine their prevalence in pickled sheep and wet blue goat skins and wet blue hides. Each selected skin or hide was examined for defects in natural light and the defects were graded according to established quality criteria in Ethiopian standard manuals. Major defects were captured by digital photography. The major pre-slaughter defects included scratches (64.2%), cockle (ekek) (32.8%), wounds or scars (12.6%), lesions from pox or lumpy skin disease (6.1%), poor substance (5%), branding marks (2.3%) and tick bites (1.5%). The presence of grain scratches in wet blue hides (76.3%) was significantly higher than in pickled sheep (67.2%) and wet blue goat (59.1%) skins. The major slaughter defects included flay cuts or scores, holes, poor pattern and vein marks, with a higher occurrence in wet blue goat skins (28.7%; P < 0.001) than in wet blue hides (22.8%) and pickled sheep skins (11.1%). The most prevalent postslaughter defects were grain cracks (14.9%), hide beetle damage (8%), damage caused by heat or putrefaction (3.7%) and machine-induced defects (0.5%). Grain cracks (27.04%) and hide beetle damage (13.9%) in wet blue goat skins were significantly more common than in wet blue hides and pickled sheep skins. These defects cause depreciation in the value of the hides and skins. Statistically significant (P < 0.001) higher rejection rates were recorded for wet blue hides (82.9%) than for pickled sheep skins (18.3%) and wet blue goat skins (8.5%). Improved animal health service delivery, effective disease control strategies and strong collaboration between stakeholders are suggested to enhance the quality of skins and hides
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