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The Behaviour of Vertical Bell Laboratories Layered Space-Time Algorithm Combined with Multiuser Detection Schemes in Wireless Communication System
Get PDFThis paper provides the performance analysis of multiuser Vertical Bell Laboratories Layered Space-Time (V-BLAST) system receiver structures for Multiple-input Multiple-Output (MIMO) channel at a base station with assumption of perfect channel estimation and perfect timing delay estimation. In MIMO channels the receivers such as decorrelator, Minimum Mean Square Error (MMSE) and Multistage Parallel Interference Cancellation (MPIC) receiver outperform the conventional receiver. Withal, since the multiple antenna interference led to a strong impact on the performance degradation of a multistage interference cancellation receiver, the performance of MPIC receiver was highly degraded based on system loading
Cross-sectional study of antioxidant status in normotensive and hypertensive pregnancy
Get PDFObjectives: The study measured the concentrations of antioxidants in women during pregnancy and the Post
Partum Period (PPP) with a view to investigating their role in the aetiology of pregnancy induced hypertension
(PIH). Study Design: Informed consent was obtained from 105 women who were divided into three groups: 15 age and parity matched normotensive non-pregnant (control group), 45 normotensive and 45 hypertensive pregnant women. The two groups of pregnant women were divided into three groups of 15 each and studied in the second and third trimesters and PPP respectively. Venous blood was obtained from all the participants for measurements of some antioxidants (uric acid, albumin, catalase and vitamin C). Data were analyzed using descriptive and inferential statistical methods.
Results: The results show that the mean concentrations of catalase, albumin, vitamin C and uric acid for the
control were 3.1 ± 0.18 µ/l, 46.6 ± 6.6 g/l, 0.38 ± 0.01 mg/dl and 0.16 ± 0.03 mmol/l respectively. The mean
concentration of all antioxidants except uric acid were significantly lower during pregnancy when compared with
controls (t= 2.06; p<0.01). In the normotensive group of pregnant women, vitamin C was the only antioxidant that showed significant higher concentration when the second trimester concentration and third trimester
concentration were compared (t=2.06; p<0.05). Uric acid levels were significantly higher (t=2.06; p<0.05) and
nd rd catalase and vitamin C levels were significantly lower in the hypertensive group during the 2 and 3 trimesters (t=2.06; p<0.05). There was a tendency for all antioxidant concentrations to return to normal values during the PPPin the normotensive group; however in the hypertensive group, uric acid levels remained significantly higher
(t=2.06; p<0.05).
Conclusion: In conclusion this study showed that pregnancy generally reduced the concentration of antioxidants
but vitamin C levels were higher in late pregnancy of normotensive women. Therefore higher levels of vitamin C
may protect against PIH
Automatic diagnosis of diabetic retinopathy from fundus images using digital signal and image processing techniques
Get PDFAutomatic diagnosis and display of diabetic retinopathy from images of retina using the techniques of digital signal and image processing is presented in this paper. The acquired images undergo pre-processing to equalize uneven illumination associated with the acquired fundus images. This stage also removes noise present in the image. Segmentation stage clusters the image into two distinct classes while the abnormalities detection stage was used to distinguish between candidate lesions and other information. Methods of diagnosis of red spots, bleeding and detection of vein-artery crossover points have also been developed in this work using the color information, shape, size, object length to breadth ration as contained in the acquired digital fundus image. The algorithm was tested with a separate set of 25 fundus images. From this, the result obtained for Microaneurysms and Haemorrhages diagnosis shows the appropriateness of the method
Effects of artemether on the plasma and urine concentrations of some electrolytes in rats
Get PDFThis study was carried out to determine the changes in the urine levels of sodium (Na+), potassium (K+), and calcium (Ca 2+) of rats during a week of intramuscular administration of artemether (12.5 to 50.0 mg/kg/day), another one week thereafter and their concentrations in the plasma at the end of the study. At 12.5 and 25.0 mg/kg of artemether, urine Na+ concentration was significantly increased throughout the study (p< 0.05), except on Day 7 (at 12.5 mg/kg) and Day 11 (at 25.0 mg/kg), when it was not significantly different from the control. At 12.5 mg/kg of the drug, urine K+ concentration was significantly increased throughout the study (p< 0.05). Artemether caused no significant changes in urine Ca 2+ concentration in the control rats as well as those that received 12.5 and 25.0 mg/kg of artemether. Progressive and significant reductions in the urine concentrations of all the electrolytes at 50.0 mg/kg of artemether were observed. Their concentrations in the plasma were also significantly reduced at this dose of the drug. A dose-dependent degeneration of the renal tissue of all the experimental rats was also observed. We concluded that high doses of artemether caused progressive degeneration of the renal tissue of rats, inability of the damaged kidneys to concentrate urine, which manifested as excessive water loss and electrolyte depletion
Degradation of aviation fuel by microorganisms isolated from tropical polluted soils
No full textThe degradation of aviation fuel was observed in soil samples from a polluted site at the aviation fuel
depot, Lagos Airport, Nigeria. The percentage of occurrence of bacterial aviation fuel–utilizers were less than
1.0% of the heterotrophic populations, while the fungal-degraders were between 2.547-16.053%. There were
no significant statistical differences for both the bacteria and fungi estimations among the soil samples.
Enrichment of soil samples with aviation fuel resulted in the isolation of five bacteria (Pseudomonas
aeruginosa, Micrococcus luteus, Corynebacterium sp., Flavobacterium rigense, Bacillus subtilis), three yeasts
(Rhodotorula sp., Candida tropicalis, Saccharomyces sp.) and two molds (Aspergillus niger, Penicillium sp.).
Utilization of the substrate by bacteria and yeast isolates resulted in an increase in population density and
subsequent decrease in pH value and residual aviation fuel concentration. Over 90% of the n-alkane fraction of
the aviation fuel supplied at 0.5% v v-1 concentration was degraded in 14 days by Pseudomonas aeruginosa,
Micrococcus luteus and Corynebacterium sp. There were differential growth responses by the strains to
dodecane, benzene, toluene and naphthalene, while growth was not supported by hexane and cyclohexane.
Thus, enrichment with of soil contaminated with aviation fuel led to the isolation of competent hydrocarbon
degraders
The demographic bonus: how prepared is Africa for the gains?
Get PDFThis paper examines the prospects of Africa’s changing age structure in favor of a temporary surge in the proportion of the working age population and the possibility of benefitting from the implied human endowment via appropriate development strategies a la South-East Asia.
An attempt to gauge the preparedness of sub-Saharan African countries in order to take advantage of the incipient demographic bonus, using South-East Asia as the platform of best practices, shows that sub-Saharan Africa must, on the average, grow the GDP to a higher level, reduce both public and private consumption expenditure in order to save and deepen more her investments in education at all levels and also enhance private spending on health. Besides, intra-African comparisons on the development efforts towards the attainment of the MDGs shows that a lot of sub-Saharan African countries are too slow to adapt to the changing age structure with appropriate social and human capital development policies and programs.
Other important variables required, from the South-East Asian experience, are more investments in physical infrastructures, services and industrial production which are essential for employment generation in the economy
ANCAEE: A Novel Clustering Algorithm for Energy Efficiency in Wireless Sensor Networks
Get PDFOne of the major constraints of wireless sensor networks is limited energy available to sensor nodes because
of the small size of the batteries they use as source of power. Clustering is one of the routing techniques that
have been using to minimize sensor nodes’ energy consumption during operation. In this paper, A Novel
Clustering Algorithm for Energy Efficiency in Wireless Sensor Networks (ANCAEE) has been proposed.
The algorithm achieves good performance in terms of minimizing energy consumption during data transmission and energy consumptions are distributed uniformly among all nodes. ANCAEE uses a new method of
clusters formation and election of cluster heads. The algorithm ensures that a node transmits its data to the
cluster head with a single hop transmission and cluster heads forward their data to the base station with
multi-hop transmissions. Simulation results show that our approach consumes less energy and effectively
extends network utilization
Artificial intelligent based friction modelling and compensation in motion control system
Get PDFThe interest in the study of friction in control engineering has been driven by the need for 10 precise motion control in most of industrial applications such as machine tools, robot 11 systems, semiconductor manufacturing systems and Mechatronics systems. Friction has 12 been experimentally shown to be a major factor in performance degradation in various 13 control tasks. Among the prominent effects of friction in motion control are: steady state 14 error to a reference command, slow response, periodic process of sticking and sliding (stick-15 slip) motion, as well as periodic oscillations about a reference point known as hunting when 16 an integral control is employed in the control scheme. Table 1 shows the effects and type of 17 friction as highlighted by Armstrong et. al.(1994). It is observed that, each of task is 18 dominated by at least one friction effect ranging from stiction, or/and kinetic to negative 19 friction (Stribeck). Hence, the need for accurate compensation of friction has become 20 important in high precision motion control. Several techniques to alleviate the effects of 21 friction have been reported in the literature (Dupont and Armstrong, 1993; Wahyudi, 2003; 22 Tjahjowidodo, 2004; Canudas, et. al., 1986). 23 One of the successful methods is the well-known model-based friction compensation 24 (Armstrong et al., 1994; Canudas de Wit et al., 1995 and Wen-Fang, 2007). In this method, 25 the effect of the friction is cancelled by applying additional control signal which generates a 26 torque/force. The generated torque/force has the same value (or approximately the same) 27 with the friction torque/force but in opposite direction
Deformation and Dehulling of Sponge Gourd (Luffa aegyptiaca) Seeds
Get PDFThis work presents the compressive strength properties of sponge gourd (Luffa aegyptica)
seeds to facilitate the design or adaptation of an appropriate dehuller. The sizes and shape
indices of the seed and kernel, and the clearance of the kernel from the seed coat were
determined. The seed samples were subjected to uni-axial quasi-static compression tests at
1.0 mm min−1 along the minor and the major axes. The fracture resistance, stiffness modulus, modulus of elasticity, toughness, and maximum elastic deformation of the seed were
obtained from the force-deformation curve. The geometric mean diameters varied from 4.0
to 4.5 mm for the seed and 1.6 to 3.9 mm for the embedded kernel; while their corresponding sphericities were 0.64 and 0.62, respectively. The compressive strength of the seed varied
with loading orientation. The seed exhibited larger deformation but lower stiffness along the
major axis than the minor axis. The force required for rupturing the hull were 95 N along
the major axis and 81 N along the minor axis; while the corresponding energy required were
95 and 40 m
UDCA: Energy Optimization III Wireless Sensor Networks Using Uniform Distributed Clustering Algorithms
Get PDFTransceivers are the major energy consumption in a Wireless Sensor Network which is made of low-power, small in size, low cost and multi-functional nodes. These sensor nodes are operated by batteries which put significant constraint to the energy available to them. Each sensor node collects sensed data and forwards it to a single processing centre called the base station which uses all reported data to detect an event or determine the changes in an environment. In present study, we propose energy optimization in Wireless Sensor Networks (WSNs) using uniform distributed clustering algorithms. One ofthe algorithms distributes cluster heads uniformly in each cluster and each non -cluster head transmit its data to the cluster heads with short distance which reduces the communication distance of each node. Thus, minimizes the energy consumption of sensor nodes. The second algorithm generates cluster heads in hierarchical form in order to transmit the aggregate data to the base station. It was observed that there is increase in energy savings as we move from bottom up in the hierarchy. Both UDCA protocol and Low Energy Adaptive Cluster Hierarchy protocol (LEACH) were simulated. The simulation results show significant reduction in energy consumption of sensor nodes and cluster heads are more uniformly distributed among all nodes in UDCA compare with LEACH and extend the wireless sensor networks lifetime