Voltage stability analysis using a modified continuation load flow and optimal capacitor bank placement

This paper addresses the rising problem of identifying the voltage stability limits of load buses in a power system and how to optimally place capacitor banks for voltage stability improvement. This paper uses the concept of the continuation power flow analysis used in voltage stability analysis. It uses the modified continuation load flow to plot the PV curves of a load bus with an aggregate induction motor load. Neuro-fuzzy techniques have been used to model the induction motor load which represents an industrial load. In the subsequent predictor]corrector stages, the induction motors are increased to depict increment in loading. Different motor ratings are used in the investigations. The process starts at some base values of the system and leading to the critical point. Further the reduced Jacobian is used to strategically locate the capacitor banks in the power system so as to effect maximum voltage improvement. In case study, illustrative  examples with the IEEE 30 bus system are shown. The results indicatethat the modified continuation load flow captures the active and reactive power consumption of the induction motors revealing cases which could lead to voltage instability. In general, the larger rated aggregated  induction motors posed a greater voltage instability risk by demanding more reactive power at lower voltages compared the equivalent lower rated aggregated induction motors. In all, manipulation of the reduced Jacobian identified the optimal placement of capacitor banks for voltage stability improvement.Key words: Continuation load flow, induction motors, voltage stability, neuro-fuzz

Ethnobotany of the Samburu of Mt. Nyiru, South Turkana, Kenya

Traditional plant use is of extremely high importance in many societies, and prevalent in African communities. This knowledge is however dwindling rapidly due to changes towards a more Western lifestyle. The influence of modern tourism cannot be neglected in this context. This paper examines the plant use of the Samburu of the Mt. Nyiru area in Northern Kenya. The Samburu pastoralists of Kenya are still amongst the most traditional communities of the country and have retained most of their knowledge about the use of a large part of the plants in their environment for a wide variety of purposes. The results indicate that the local population has a very high knowledge of the plants in their surroundings, and attributes a purpose to a large percentage of the plants found. 448 plant species were collected, identified and their Samburu names and traditional uses recorded. 199 species were reported as of "no use". The high proportion of 249 plant species however had some traditional use: The highest number (180 species) was used as fodder, followed by 80 species that had medicinal use. Firewood (59 species), construction (42 species), tools (31 species), food (29 species) and ceremonial use (19 species) ranked far behind. Traditionally the Samburu attribute most illnesses to the effect of pollutants that block or inhibit digestion. This can include "polluted" food, contagion through sick people as well as witchcraft. In most cases the treatment of illness involves herbal purgatives to cleanse the patient. There are however frequent indications of plant use for common problems like wounds, parasites, body aches and burns. The change from a nomadic to a more sedentary lifestyle, often observed in other areas of the country, has affected the Samburu of remote Mt. Nyiru to a much lesser extent and did so far not lead to a major loss of traditional plant knowledge. However, overgrazing and over-exploitation of plant resources have already led to a decline of the plant material available

Knowledge and care seeking practices for ear infections among parents of under five children in Kigali, Rwanda : a cross-sectional study

Background: Infections affecting the middle ear are a common childhood occurrence. Some cases may present with ear discharge through a tympanic membrane perforation which may heal spontaneously. However, up to 5% or more cases of those affected have persistent ear discharge. A number of barriers contribute towards delayed presentation at health facilities for treatment of ear infections. We conducted a study to evaluate parents’ and caregivers’ knowledge and care seeking practices for ear infections in children under five in Gasabo district in Kigali, Rwanda. Methods: Parents/guardians (n = 810) were interviewed using a structured questionnaire to elicit their knowledge of ear infections in children under five and their attitude to seeking care for their children. Results: The mean age of the respondents was 31.27 years (SD = 7.88, range 17–83). Considering an average of knowledge parameters which included causes, symptoms, prevention, treatment and consequences of ear infections, we found that 76.6% (622) of respondents were knowledgeable about ear infections. We defined a positive practice as seeking medical treatment (community health workers or health facility) and this was found in 89.1% (722) respondents. Correlating knowledge with choice of seeking treatment, respondents were 33% less likely to practice medical pluralism (OR = 0.33, CI 0.11–0.97, P = 0.043) if they were familiar with infections. Moreover, urban dweller were 1.7 times more likely to know ear infections compared to rural dwellers (OR = 1.70, CI 1.22–2.38, P = 0.002). Conclusion: The majority of respondents had good knowledge and positive attitudes and practices about ear infection. However, medical pluralism was common. There is need to improve the community’s awareness and access to primary health care facilities for the care of ear infections especially in rural areas of Rwanda

Indigenous use and bio-efficacy of medicinal plants in the Rasuwa District, Central Nepal

<p>Abstract</p> <p>Background</p> <p>By revealing historical and present plant use, ethnobotany contributes to drug discovery and socioeconomic development. Nepal is a natural storehouse of medicinal plants. Although several ethnobotanical studies were conducted in the country, many areas remain unexplored. Furthermore, few studies have compared indigenous plant use with reported phytochemical and pharmacological properties.</p> <p>Methods</p> <p>Ethnopharmacological data was collected in the Rasuwa district of Central Nepal by conducting interviews and focus group discussions with local people. The informant consensus factor (F_IC) was calculated in order to estimate use variability of medicinal plants. Bio-efficacy was assessed by comparing indigenous plant use with phytochemical and pharmacological properties determined from a review of the available literature. Criteria were used to identify high priority medicinal plant species.</p> <p>Results</p> <p>A total of 60 medicinal formulations from 56 plant species were documented. Medicinal plants were used to treat various diseases and disorders, with the highest number of species being used for gastro-intestinal problems, followed by fever and headache. Herbs were the primary source of medicinal plants (57% of the species), followed by trees (23%). The average F_IC value for all ailment categories was 0.82, indicating a high level of informant agreement compared to similar studies conducted elsewhere. High F_ICvalues were obtained for ophthalmological problems, tooth ache, kidney problems, and menstrual disorders, indicating that the species traditionally used to treat these ailments are worth searching for bioactive compounds: <it>Astilbe rivularis</it>, <it>Berberis asiatica</it>, <it>Hippophae salicifolia, Juniperus recurva</it>, and <it>Swertia multicaulis</it>. A 90% correspondence was found between local plant use and reported plant chemical composition and pharmacological properties for the 30 species for which information was available. Sixteen medicinal plants were ranked as priority species, 13 of which having also been prioritized in a country-wide governmental classification.</p> <p>Conclusions</p> <p>The <it>Tamang </it>people possess rich ethnopharmacological knowledge. This study allowed to identify many high value and high priority medicinal plant species, indicating high potential for economic development through sustainable collection and trade.</p

Ethnobotany in the Nepal Himalaya

<p>Abstract</p> <p>Background</p> <p>Indigenous knowledge has become recognized worldwide not only because of its intrinsic value but also because it has a potential instrumental value to science and conservation. In Nepal, the indigenous knowledge of useful and medicinal plants has roots in the remote past.</p> <p>Methods</p> <p>The present study reviews the indigenous knowledge and use of plant resources of the Nepal Himalayas along the altitudinal and longitudinal gradient. A total of 264 studies focusing on ethnobotany, ethnomedicine and diversity of medicinal and aromatic plants, carried out between 1979 and 2006 were consulted for the present analysis. In order to cross check and verify the data, seven districts of west Nepal were visited in four field campaigns.</p> <p>Results</p> <p>In contrast to an average of 21–28% ethnobotanically/ethnomedicinally important plants reported for Nepal, the present study found that up to about 55% of the flora of the study region had medicinal value. This indicates a vast amount of undocumented knowledge about important plant species that needs to be explored and documented. The richness of medicinal plants decreased with increasing altitude but the percentage of plants used as medicine steadily increased with increasing altitude. This was due to preferences given to herbal remedies in high altitude areas and a combination of having no alternative choices, poverty and trust in the effectiveness of folklore herbal remedies.</p> <p>Conclusion</p> <p>Indigenous knowledge systems are culturally valued and scientifically important. Strengthening the wise use and conservation of indigenous knowledge of useful plants may benefit and improve the living standard of poor people.</p