Modelling and detection of faults in axial-flux permanent magnet machines

The development of various topologies and configurations of axial-flux permanent magnet machine has spurred its use for electromechanical energy conversion in several applications. As it becomes increasingly deployed, effective condition monitoring built on reliable and accurate fault detection techniques is needed to ensure its engineering integrity. Unlike induction machine which has been rigorously investigated for faults, axial-flux permanent magnet machine has not. Thus in this thesis, axial-flux permanent magnet machine is investigated under faulty conditions. Common faults associated with it namely; static eccentricity and interturn short circuit are modelled, and detection techniques are established. The modelling forms a basis for; developing a platform for precise fault replication on a developed experimental test-rig, predicting and analysing fault signatures using both finite element analysis and experimental analysis. In the detection, the motor current signature analysis, vibration analysis and electrical impedance spectroscopy are applied. Attention is paid to fault-feature extraction and fault discrimination. Using both frequency and time-frequency techniques, features are tracked in the line current under steady-state and transient conditions respectively. Results obtained provide rich information on the pattern of fault harmonics. Parametric spectral estimation is also explored as an alternative to the Fourier transform in the steady-state analysis of faulty conditions. It is found to be as effective as the Fourier transform and more amenable to short signal-measurement duration. Vibration analysis is applied in the detection of eccentricities; its efficacy in fault detection is hinged on proper determination of vibratory frequencies and quantification of corresponding tones. This is achieved using analytical formulations and signal processing techniques. Furthermore, the developed fault model is used to assess the influence of cogging torque minimization techniques and rotor topologies in axial-flux permanent magnet machine on current signal in the presence of static eccentricity. The double-sided topology is found to be tolerant to the presence of static eccentricity unlike the single-sided topology due to the opposing effect of the resulting asymmetrical properties of the airgap. The cogging torque minimization techniques do not impair on the established fault detection technique in the single-sided topology. By applying electrical broadband impedance spectroscopy, interturn faults are diagnosed; a high frequency winding model is developed to analyse the impedance-frequency response obtained

Pedagogical repertoire of a model language Teacher

This paper examines the expected traits of a language teacher especially in a multilingual society. The peculiar linguistic attributes are scrupulously considered as each letter of the word TEACHER is used to bring out the required linguistic pedagogical culture. The common occurrence of students’ mass failure in English language as witnessed in the various competitive examinations and the rapid decline in the quality of teachers in charge of the subject in schools bring to the fore the concern for its pedagogical appraisal especially in the area of teachers’ preparation for the sensitive job. The work is expository as some common factors were brought out and used to treat the expected teachers’ behavior in language teaching activities. The writer’s exposure and experience in the job supply the root for all the issues raised in the work. Based on the considered factors, it is recommended that the personnel that handle the training of teachers in the higher institution must be exposed to the real practical aspect of the work. Through this, well trained, brilliant, interested and committed individuals will be discovered on the field to take care of students who opt for teaching career in the colleges of education and in the faculty of education in the universities. When the stream is progressive and hard work is rewarded, teachers will be dedicated to work and be related to stand up as models to the students

Acute flaccid paralysis: a five–year review of cases managed by physiotherapy at the University College Hospital, Ibadan

A 5-year (1999-2004) review of acute flaccid paralysis (AFP) cases managed at the physiotherapy clinic of the University College Hospital, Ibadan Nigeria was carried out. Collection of data involved retrieving the records of all patients seen at the physiotherapy clinic during the study period, from which the paediatric cases were sorted out. The treatment records cards of patients with acute flaccid paralysis were identified and reviewed. Information on age, gender, immunization history, and specific physician diagnosis and discharge practice were collated. A total of 757 paediatric cases reviewed out of which 132 (17.4%) were AFP case, with mean age of 44.31± 33.03 months and a 1.2:1.0 male: female ratio. Sciatic nerve palsy accounted for majority (72.0%) of the AFP; only 43.2% of the patients had completed immunization before the onset; majority of the cases (78.8%) were referred to physiotherapy within 6 months of onset and the discharge pattern revealed that only 9.8% of the patients were formally discharged. With injection palsy accounting for majority of the AFP cases, the need for caution. In administration of intramuscular injections at the buttocks of children with febrile illnesses is suggested. Importance of adequate documentation of clinical information by clinicians is also emphasised. African Journal of Health Sciences Vol. 13 (1-2) 2008: pp. 28-3

Effects of Out-door Activities on Students’ Attitude towards Physics in Secondary Schools

The study investigated the effects of out-door activities on students’ attitude towards learning of Physics in Senior Secondary School Physics in Ekiti State, Nigeria. The research design adopted in the study was Pretest-Posttest Quasi-experimental. The sample for the study was 150 Senior Secondary One (SSI) Physics students (this sample was divided into the experimental and control groups in ratio 1: 1 i.e. 75 in each group), selected through the multistage sampling technique from a total population of 7,852 SS I students offering Physics in all the 184 public Senior Secondary Schools in Ekiti State. The instrument used to collect relevant data from the subjects was Physics Attitudinal Scale (PAS). The reliability of the instrument was determined through the split-half method with the reliability coefficient of 0.83. Two null hypotheses were tested at 0.05 level of significance. The data collected were analysed using inferential statistics of t-test and Analysis of Covariance (ANCOVA). The results of the analyses showed that there was significant difference in the attitude of students to Physics in the experimental and control groups in favour of experimental group. Based on the findings of the study, it was recommended that non-conventional teaching approaches such as using out-door activities, should be introduced into the teaching of Physics in the nation’s secondary schools to reinforce the hitherto adopted conventional teaching method and Physics teachers should be encouraged to make use of these new teaching approaches

Zur indigenen afrikanischen Epistemologie: mythografische Darstellungen des Phänomens der Hexerei in Texten Ifás

U umovima onih što snažno podržavaju hegemoniju znanosti ponad praksi usmenih tradicija, vještičarstvo pripada dimenziji makabrističkih fantazija, djelomice i zato što je vještičarenje uvršteno u područje okultnog i teško je empirijski provjerljivo. Pozitivistički pristup i zapadnjačko omalovažavanje fenomena vještičarstva stvara utisak da su prakse poput magije i vještičarstva, usađene u usmene tradicije, teorijske pretpostavke te iracionalne. Za ovaj rad važno je pogrešno shvaćanje Geoffreyja Parrindera da se Afrikanci nisu naslanjali na zapise, nego na mnemoničke genije kada su u pitanju bile njihove povijesti, filozofije, kozmologije itd. Uzimaju¬ći vještičarenje kao pozadinu, Parrinder tvrdi da ne postoje pouzdani zapisi koji potvrđuju postojanje vještičarenja u Africi. Pod »pouzdani zapisi« očito je da Parrinder podrazumijeva pisanje ponad usmenog prenošenja i, samim time, nepoznato mu je da, za narod Yorùbá, Ifá može producirati zapise vezane za njihove mitske/religijske koncepcije, svjetonazore i živuće ritualne obrede. Ovaj rad pokazuje, u jednu ruku, da je naše pogrešno korištenje termina »pisanje« i »pismenost« razmješteno mnogim dvosmislenostima koje nas sprječavaju u prihvaćanju, primjerice, inskriptivne prirode Ifá sustava u našu povijest zapisa. U drugu ruku, rad predstavlja Ifáu kao korpus pouzdanih zapisa i povlači argumente iz sistematiziranog grafičkog prevođenja dvaju strofa Ìrosùn-Ọ̀sẹ́ i Ọ̀sá-Méjì, kojima se odgovara na pitanja o prihvaćanju postojanja vještica, zatim može li se čarobnjaštvo i vještičarstvo koristiti izmjenično, o djelovanju vještica prema članovima svoje porodice, o položaju vještica u hijerarhiji bića itd.In the minds of those who strongly support the hegemony of science over practices in oral cultures, witchcraft belongs to the realm of macabre fantasies, in part because witchcraft practices fall within the domain of the occult and become extremely difficult to explain empirically. This positivistic attitude and Western condescension towards the phenomenon of witchcraft convey the impression that such practices as magic and witchcraft, ingrained in oral cultures, are theoretical presuppositions and irrational. Of interest to this paper, therefore, is Geoffrey Parrinder’s perceived misconception that Africans relied not on “written records” but only on mnemonic genius in terms of their history, their philosophy, their cosmology, and so on. With witchcraft at the back of his mind, Parrinder claims that there are no reliable records to back the existence of witches in Africa. By “reliable records”, it is clear that Parrinder valorizes writing at the expense of orality and is, therefore, oblivious of the fact that, for the Yorùbá, Ifá could produce scribal discourses in respect of their mythical/religious conceptions, worldviews and lived ritual practices. This paper shows, on the one hand, that our misuse of the term “writing” or “literacy” is mostly clustered with many ambiguities which often debar us from admitting, for example, the inscriptive nature of the Ifá system into our writing history. On the other hand, the paper presents Ifá as a corpus of reliable records and draws from the systematized graphic translations of two Ifá verses, namely Ìrosùn-Ọ̀sẹ́ and Ọ̀sá-Méjì, to answer salient questions bordering on the admission of the existence of witches, whether witchcraft and sorcery can be used interchangeably, the activities of witches towards kinsmen or members of their family and the position of witches in the hierarchy of beings, and so on.Dans la pensée de ceux qui soutiennent fermement l’hégémonie d’une science qui serait audessus de la pratique traditionnelle orale, la sorcellerie relève d’une dimension fantaisiste macabre, partiellement en raison du fait qu’elle s’inscrit dans le domaine de l’occulte et qu’elle est difficilement vérifiable de manière empirique. L’approche positiviste et la dépréciation du phé¬nomène de la sorcellerie de la part de l’Occident donnent l’impression que les pratiques telles la magie et la sorcellerie, enracinées dans la tradition orale, sont des hypothèses qui relèvent de la théorie et sont ainsi irrationnelles. Ce travail prend en considération la conception erronée de Geoffrey Parrinder selon laquelle les Africains ne se seraient pas basés sur des écrits, mais sur des génies de la mnémonique lorsqu’il est question de leur histoire, leur philosophie, leur cosmologie, etc. En se servant du contexte de la sorcellerie, Parrinder affirme qu’il n’existe pas d’écrits fiables qui confirment l’existence de la sorcellerie en Afrique. Il est clair que sous l’appellation de « écrits fiables » Parrinder suppose que la transmission écrite est au¬dessus de la transmission orale, et ainsi, il lui est inconnu que le sytème de divination Ifá peut produire pour le peuple Yorùbá des écrits liés à leur conception religieuse/mythique, leur vision du monde, leurs rituels vivants. D’un côté, ce travail montre que notre compréhension des termes de « écriture » et « éducation » se déploie par le biais de nombreuses ambiguïtés qui nous empêchent d’accepter, par exemple, le caractère inscriptible du système Ifá dans notre histoire de l’écriture ; d’un autre côté, ce travail présente le système Ifá en tant que corpus d’inscriptions fiables et tire ses arguments d’une traduction graphique systématisée de deux strophes, Ìrosùn-Ọ̀sẹ́ et Ọ̀sá-Méjì, à travers desquelles les réponses aux questions concernant l’existence des sorcières et de leurs actions envers les membres de leur famille sont données, mais pose également la question de savoir s’il est possible d’utiliser les termes de magie noire et de sorcellerie de manière interchangeable et interroge le rôle des sorcière dans la hiérarchie de l’être, etc.Im Geist derjenigen, die die Hegemonie der Wissenschaft über die Praxis mündlicher Traditionen stark unterstützen, gehört die Hexerei zur Dimension makabristischer Fantasien, zum Teil auch weil die Hexerei in den Bereich des Okkulten eingeordnet wird und empirisch kaum nachprüfbar ist. Der positivistische Ansatz und die westliche Herabwürdigung des Phänomens der Hexerei erzeugen den Eindruck, dass Praktiken wie Magie und Hexerei, die in mündliche Traditionen eingebettet sind, theoretische Annahmen und Irrationalitäten sind. Für diese Arbeit ist die falsche Auffassung Geoffrey Parrinders belangvoll, dass sich die Afrikaner nicht auf die Aufzeichnungen stützten, sondern auf die mnemonischen Genies, wenn deren Geschichte, Philosophien, Kosmologien usw. in Betracht gezogen wurden. Vor dem Hintergrund der Hexerei behauptet Parrinder, es bestünden keine zuverlässigen Aufzeichnungen, die die Existenz von Hexerei in Afrika beweisen. Unter den „zuverlässigen Aufzeichnungen“ gewährt Parrinder offensichtlich den Vorrang der schriftlichen im Vergleich zur mündlichen Überlieferung, und es ist ihm dadurch unbekannt, dass Ifá für das Volk der Yorùbá Aufzeichnungen produzieren kann, die sich auf ihre mythischen / religiösen Konzeptionen, Weltanschauungen und lebende Ritualzeremonien beziehen. Diese Arbeit zeigt einerseits, dass unsere falsche Verwendung der Termini „Schreiben“ und „Alphabetisierung“ durch zahlreiche Zweideutigkeiten zersplittert worden ist, die uns daran hindern, beispielsweise die inskriptive Natur des Ifá Systems in unsere Aufzeichnungsgeschichte einzuführen. Auf der anderen Seite stellt die Arbeit Ifá als Korpus verlässlicher Aufzeichnungen dar und leitet Argumente aus der systematisierten grafischen Übersetzung zweier Strophen, Ìrosùn-Ọ̀sẹ́ und Ọ̀sá-Méjì, ab, die Fragen zur Akzeptanz der Existenz von Hexen beantworten. Darüber hinaus beantworten sie die Frage, ob Zauberei und Hexerei wechselweise verwendet werden können, außerdem die Frage zur Tätigkeit der Hexen gegen¬ über den Mitgliedern ihrer Familien und schließlich die Frage zur Position der Hexen in der Hierarchie der Wesen usw

Major urogenital malformations in Nigerian children

Background:There is scanty data on the pattern of childhoodurogenital malformations in many resource-poorcountries, including Nigeria.Objective:To describe the pattern of occurrence of majorurogenital malformations in children presenting in atertiary health care centre in sub Saharan Africa.Design:Retrospective case review.Patients:All children with major urogenital malformationspresented at the Department of Paediatrics of theUniversity College Hospital, Ibadan, a large tertiaryhealth care institution in South West Nigeria. In theperiod from July 1985 to December 1995.Main results:A total number of 125 cases of major urogenitalmalformations were seen during the study period.The commonest of these malformations were posterior urethral valves (40.0%), hypospedias(18.4%), ambiguous external genitalia (12.8%) andectopia vesicae (11.2%).Prenatal diagnosis was rare and most patientspresented late. Mortality during first admission was14.4% (18/125), mostly accounted for by cases ofposterior urethral valves.Conclusion: Posterior urethral valves accounted for the majority of major urogenital malformations seen in the setting studied. The high mortality probably reflected the severity of the lesions and late presentation of patients (which was related to the rarity of prenatal diagnosis). Increased awareness of these lesions among physicians practising in developing countries and greater use of ultrasonography in the third trimester of pregnancy may improve the prognosis by early detection and management

The Contributions Of Nigeria Women Towards National Development

This paper examine the contributions of Nigeria Women towards National Development. It gives the detrimental effects which the colonialism have had on the status of Nigerian women. The challenges of women contributions to the development of the Nigerian nation are highlighted. And ameliorating these challenges recommendations are made which among others include the proper education of women, formation of more women, business cooperatives, enlightment campaigns in secondary and tertiary institutions as well as granting women their constitutional rights to effective participation in the affairs of the country

Students’ Attitude and Interest as Correlates of Students’ Academic Performance in Biology in Senior Secondary School

The study examined the relationship in the students’ attitude to Biology and students’ interest and academic performance of student in Biology in Ekiti State, Nigeria. Students for the study were two hundred (200) SS II Biology students randomly drawn from five secondary schools in Ado Local Government Area of Ekiti State. The research design adopted was a descriptive survey research which was questionnaire based and past terminal continuous assessment results of the students involved in the study. The instruments used to collect relevant data from the students were Biology Attitudinal Scale (BAS), Biology Interest Scale (BIS) and terminal continuous assessment results. The instruments were subjected to validity and reliability mechanism. Pearson Product Moment correlation(r) statistical analysis was used to analysed the two null hypotheses formulated for the study. The findings showed that there is significant relationship in the students’ attitude to Biology and students’ academic performance in Biology, and the findings also revealed that there is significant relationship in the students’ interest in Biology and students’ academic performance in Biology. Conclusion and recommendations were also made in this paper

In-vitro antioxidant activities of the stem bark extract fractions of Bridelia ferruginea

Bridelia ferruginea stem bark generally used in Indigenous folk medicine for diverse uses was evaluated scientifically to elucidate the antioxidant activity of various fractions in-vitro to validate its folkloric usage. In vitro antioxidant properties of the extract fractions were evaluated using the free radical scavenging activities by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) with ascorbic acid as control. The total antioxidant activity results indicated that, the inhibition percent of aqueous extract was significantly higher than the inhibition percent of ethanol and ethyl acetate in the DPPH methods. A higher IC50 (0.85 mg/ml compared to 1.34 mg/ml ethanolic extract and 1.41mg/ml of Ethyl acetate) value was observed. The aqueous extract was better in Fe2+chelating activity and higher in the content of total phenol as compared to ethanolic and ethyl acetate extracts. However, the ethyl acetate extract had signi?cantly higher (P < 0.05) hydroxyl radical scavenging activity with the concentration for 50% inhibition (IC) value of 0.86 mg/mL, 1.24 mg/mL for ethanolic extract and 2.16 mg/mL for aqueous extract. The results indicated that all the extracts showed excellent Nitric oxide scavenging activities with a close range of IC50 values of 0.83, 0.99 and 1.83 mg/mL for aqueous, ethanolic and ethyl acetate extract. The results suggest that Bridelia ferruginea stem bark possesses varied degrees of antioxidant activity in vitro and has the potential to be developed into dietary supplements and synergically modified with synthetic antioxidants. Keywords: Ethanolic extract, Aqueous extract, Ethyl acetate extract, Bridelia ferruginea, and Antioxidant activity

Nurse-led training programme on knowledge about sexual violence among adolescent females in selected secondary schools, Abeokuta South local government area, Ogun state

Sexual violence is any unwanted sexual act that is perpetrated against someone’s willingness by a person known or unknown to the victim. Adolescent girls are at high risk of sexual violence due to their inadequate knowledge about sexual violence. This study aimed to determine the effect of nurse-led training programme on knowledge about sexual violence among adolescent females in secondary schools in Abeokuta South Local Government Area, Ogun State. This study adopted quasi-experimental design with two treatment groups forming the control and intervention groups using 109 adolescent female students from four selected secondary schools using a self-administered questionnaire. A draft of the instrument along with the objectives of the study, research questions were submitted for face and content validation. Cronbach's Alpha Coefficient was used to test for reliability, values of 0.70 and above were accepted and items that scored less were reframed. Descriptive and inferential statistics such as z-test were used to explore relationships between the nurse-led training and knowledge. The study results revealed a statistically significant difference (p>000) between knowledge of adolescent female students, after the intervention. There is therefore need for periodic intervention programmes and awareness/enlightenment campaigns about sexual violence targeted at secondary school students. Keywords: Adolescent, Knowledge, Nurse-led Intervention, Prevention, Sexual violenc