Fault-Tolerant Control of a Flux-switching Permanent Magnet Synchronous Machine

Je jasné, že nejúspěšnější konstrukce zahrnuje postup vícefázového řízení, ve kterém každá fáze může být považována za samostatný modul. Provoz kterékoliv z jednotek musí mít minimální vliv na ostatní, a to tak, že v případě selhání jedné jednotky ostatní mohou být v provozu neovlivněny. Modulární řešení vyžaduje minimální elektrické, magnetické a tepelné ovlivnění mezi fázemi řízení (měniče). Synchronní stroje s pulzním tokem a permanentními magnety se jeví jako atraktivní typ stroje, jejíž přednostmi jsou vysoký kroutící moment, jednoduchá a robustní konstrukce rotoru a skutečnost, že permanentní magnety i cívky jsou umístěny společně na statoru. FS-PMSM jsou poměrně nové typy střídavého stroje stator-permanentní magnet, které představují významné přednosti na rozdíl od konvenčních rotorů - velký kroutící moment, vysoký točivý moment, v podstatě sinusové zpětné EMF křivky, zároveň kompaktní a robustní konstrukce díky umístění magnetů a vinutí kotvy na statoru. Srovnání výsledků mezi FS-PMSM a klasickými motory na povrchu upevněnými PM (SPM) se stejnými parametry ukazuje, že FS-PMSM vykazuje větší vzduchové mezery hustoty toku, vyšší točivý moment na ztráty v mědi, ale také vyšší pulzaci díky reluktančnímu momentu. Pro stroje buzené permanentními magnety se jedná o tradiční rozpor mezi požadavkem na vysoký kroutící moment pod základní rychlostí (oblast konstantního momentu) a provozem nad základní rychlostí (oblast konstantního výkonu), zejména pro aplikace v hybridních vozidlech. Je předložena nová topologie synchronního stroje s permanentními magnety a spínaným tokem odolného proti poruchám, která je schopná provozu během vinutí naprázdno a zkratovaného vinutí i poruchách měniče. Schéma je založeno na dvojitě vinutém motoru napájeném ze dvou oddělených vektorově řízených napěťových zdrojů. Vinutí jsou uspořádána takovým způsobem, aby tvořila dvě nezávislé a oddělené sady. Simulace a experimentální výzkum zpřesní výkon během obou scénářů jak za normálního provozu, tak za poruch včetně zkratových závad a ukáží robustnost pohonu za těchto podmínek. Tato práce byla publikována v deseti konferenčních příspěvcích, dvou časopisech a knižní kapitole, kde byly představeny jak topologie pohonu a aplikovaná řídící schémata, tak analýzy jeho schopnosti odolávat poruchám.It has become clear that the most successful design approach involves a multiple phase drive in which each phase may be regarded as a single-module. The operation of any one module must have minimal impact upon the others, so that in the event of that module failing the others can continue to operate unaffected. The modular approach requires that there should be minimal electrical, magnetic and thermal interaction between phases of the drive. Flux-Switching permanent magnet synchronous machines (FS-PMSM) have recently emerged as an attractive machine type virtue of their high torque densities, simple and robust rotor structure and the fact that permanent magnets and coils are both located on the stator. Flux-switching permanent magnet (FS-PMSM) synchronous machines are a relatively new topology of stator PM brushless machine. They exhibit attractive merits including the large torque capability and high torque (power) density, essentially sinusoidal back-EMF waveforms, as well as having a compact and robust structure due to both the location of magnets and armature windings in the stator instead of the rotor as those in the conventional rotor-PM machines. The comparative results between a FS-PMSM and a traditional surface-mounted PM (SPM) motor having the same specifications reveal that FS-PMSM exhibits larger air-gap flux density, higher torque per copper loss, but also a higher torque ripple due to cogging -torque. However, for solely permanent magnets excited machines, it is a traditional contradiction between the requests of high torque capability under the base-speed (constant torque region) and wide speed operation above the base speed (constant power region) especially for hybrid vehicle applications. A novel fault-tolerant FS-PMSM drive topology is presented, which is able to operate during open- and short-circuit winding and converter faults. The scheme is based on a dual winding motor supplied from two separate vector-controlled voltage-sourced inverter drives. The windings are arranged in a way so as to form two independent and isolated sets. Simulation and experimental work will detail the driver’s performance during both healthy- and faulty- scenarios including short-circuit faults and will show the drive robustness to operate in these conditions. The work has been published in ten conference papers, two journal papers and a book chapter, presenting both the topology of the drive and the applied control schemes, as well as analysing the fault-tolerant capabilities of the drive.

Effects of oral health in relation to fluoridation and socioeconomic status in developed and developing countries

The rate of tooth decay has declined since the start of fluoridation in the United States. Fluoridation was initiated when evidence of fluoride’s ability to make teeth stronger and more resistant to acid was reported. Despite the benefits of fluoride, many researchers using inbred mice have shown that excessive amounts of this trace element leads to fluorosis and eventually skeletal fluorosis, which can lead to osteoporosis. Interestingly, the downward trend in the rate of decline in tooth decay is also observed in various countries that do not participate in fluoridation programs, including both developed and developing countries. This decline is likely due to the high fluoride concentration within their natural waters in combination with improved oral hygiene care. Since excessive amounts of fluoride have been known to cause discoloring of teeth, decalcification of enamel, lower intelligence quotient, arthritis, osteoporosis, etc., it is also surprising that the United States consumes more fluoride than the rest of the world combined. Although fluoridation of water remains the most cost effective treatment for tooth decay in the United States its use has decreased, suggesting it may no longer be needed. To test the need of fluoridation a comparison of developed countries, which participate in fluoridation, including the United States and the United Kingdom was made with developing counties that do not participate in fluoridation programs, such as Sudan, China, and India. Observations made from several studies and discussed here demonstrate that tooth decay is positively influenced by fluoridation but can also contribute negatively to fluorosis. Even though medical treatment is more advanced in developed countries than in developing countries, tooth decay still is a major health concern in both. Factors such as socioeconomic status and lifestyle behaviors are influential and need to be considered when determining the best approach to decrease tooth decay in communities

PRODUCTIONAL PERFORMANCE OF CROSSBRED (SAANEN & NUBIAN) GOATS IN THE SECOND KIDDING UNDER SUDAN CONDITIONS

Praise, in the first place is to almighty Allah, the lord of the world for giving me health and aptitude to complete this work. I wish to express my sincere thanks and gratitude to Dr. Ibtisam Elyas Mohamed Elzubeir for her helpful supervision, suggestions and continued support throughout this work. My appreciations are due to the Adminstration of Goat Improvement Project of the Ministry of Agriculture and Animal Resources Khartoum State for allowing me to use their animals for the present experiment. Finally I wish to express my thanks to the technician and labours of Dairy chemistry laboratory, Faculty of Animal Production, and all the colleagues for friendly atmosphere that helped me in achieving this work. My thanks are due to all friends who helped me in one way or another and whose names could not be mentioned individuall

Organizational Commitment and Employees Turnover Intention in Saudi Public Sector: The Mediating Role of Job Satisfaction and Work Environemnt

Purpose:  Organisational commitment is critical to an organization's success and growth. It leads to increased job satisfaction, lower turnover, improved performance, a more positive organisational culture, and increased customer satisfaction. This research tries to highlight the relationship between organizational commitment and turnover intention taking into account the mediation role of job satisfaction and work environment.   Theoretical framework:  Organizational commitment is very crucial in today working environment. Employees are more likely to be inspired and dedicated to their work when they feel committed to their organisation.(Freudenberger, 1974) .This results in increased productivity and performance. Furthermore, organizational commitment is important in employee retention. Employees that are committed to their company are less inclined to depart for other chances(Mathieu, Fabi, Lacoursiere, & Raymond, 2016). This lowers turnover rates and the costs associated with hiring and training new personnel.   Methodology: This is a quantitative study that employed a structured questionnaire design. This study's sample consists of 193 public officers from the Saudi public sector in the western region who were chosen at randomly. Raw data gathered via mail questionnaires. The data collected was analyzed by SmartPLS 3 to test the study's hypotheses.   Findings:  Finding of this study indicates that organizational commitment has a substantial and statistically significant influence on Job Satisfaction (β = 0.601, t = 8.580, p = .001), and turnover intention (β = -0.363, t = 4.737, p = .001). In addition, the work environment and job satisfaction show mediation role in the relationship between organizational commitment and turnover intention.   Research, Practical & Social implications:  Managers at the public organizations need to apply different strategies to enhance the overall job satisfaction like giving employees a voice and involving them in problem-solving. This make them feel valued and motivated. Such practice can lead to create a conducive working environment where few people decide to quit. Employees that are committed to their organisation are more inclined to put in extra effort and go the extra mile. It is highly recommended to adopt high-performance working environment. This requires an updated human resource management techniques and practices.   Originality/Value:  The findings of this study indicates that ORC has a substantial and statistically significant influence on Job Satisfaction, working environment, and turnover intention. This study also finds the work environment and job satisfaction are significantly mediated the relationship between organizational commitment and turnover intention. This contributes to the current literature especially in the public organizations studies

Study of Performance Enhancement of a Building in Tropical Climate

The application of Trombe wall in hot climate is problematic due to undesired heat gains and overheating resulting from the solar radiation incident on the building. Heating and cooling in commercial and residential buildings consume a lot of energy generated mostly from fossil fuels and steam plants. Studies and researches are made to come up with better solutions to save the cost of energy, and the new types of energy are called renewable energies like solar energy, wind energy and biomass energy. They are introduced to compensate the degradation of fossil fuels and reduce the electricity bills. Using the solar energy principles, Trombe wall- a passive solar system- is becoming widely used to establish heat energy transfer from the solar radiation to moderate the ambient temperature of a building. In this project the concept of Trombe wall will be studied and applied to suite the Malaysian climatic conditions. At the end of the project the effect of double glazing filled with argon was justified and found to reduce the temperature inside the building

Pentalogy of cantrell

[No abstract available]Scopu

Application of loop-mediated isothermal amplification (LAMP) of the random insertion mobile element (RIME - LAMP) to diagnose camel Trypanosomiasis in Sudan

Control of Trypanosomiasis is dependent on accurate diagnosis and treatment of infected patients or animals. Highly sensitive tests are available for serological screening but the sensitivity of parasitological confirmatory tests remains insufficient and needs to be improved. Ongoing research is opening perspectives for a new generation of field diagnostics. This study aimed to apply and investigate new diagnostic technique loop-mediated isothermal amplification (LAMP) of the random insertion mobile element (RIME - LAMP) to diagnose camel Trypanosomiasis in Sudan. Extracted DNA from camels was used to detect Trypanosoma evansi infection in camels using RIME-LAMP technique. A total of 368 DNA samples positive reactor with card agglutination test for Trypanosomiasis (CATT T. evansi) was tested using RIME-LAMP. A total of 208 samples reacted positive (56.52%) using RIME – LAMP whereas only 17 samples were positive (6.34%) using parasitological methods. RIME-LAMP helps increase the probability of detecting the positive cases of camel Trypanosomiasis and it was found to be one useful and alternative molecular diagnostic tool for the detection of T. evansi infections.Key words: Sudan, loop-mediated isothermal amplification (LAMP) - random insertion mobile element (RIME - LAMP), camel, Trypanosoma evansi

Study of Performance Enhancement of a Building in Tropical Climate

The application of Trombe wall in hot climate is problematic due to undesired heat gains and overheating resulting from the solar radiation incident on the building. Heating and cooling in commercial and residential buildings consume a lot of energy generated mostly from fossil fuels and steam plants. Studies and researches are made to come up with better solutions to save the cost of energy, and the new types of energy are called renewable energies like solar energy, wind energy and biomass energy. They are introduced to compensate the degradation of fossil fuels and reduce the electricity bills. Using the solar energy principles, Trombe wall- a passive solar system- is becoming widely used to establish heat energy transfer from the solar radiation to moderate the ambient temperature of a building. In this project the concept of Trombe wall will be studied and applied to suite the Malaysian climatic conditions. At the end of the project the effect of double glazing filled with argon was justified and found to reduce the temperature inside the building

Tsetse Fly Infection Dynamics and its Implications with Control of Trypanosomiasis in Kajo-Keji County, South Sudan

A two-year study was conducted in Kajo-keji County South Sudan to evaluate tsetse fly infection dynamics which implicate the control of trypanosomiasis in the study area.Infection dynamics ofthe flieswas assessed and monitored using biconical traps.Captured flies were identified, segregated into sexes and age examined using wing fray and ovarian techniques for males and females, respectively. RIME-LAMP test was used to detectTrypanosome species in the midguts of wild tsetse flies.The non-parametric Wilcoxon Signed Rank Test was used to assess the difference in the number of the infected flies between the dry and the wet season counts.The mean infected G.f. fuscipes were: male 6 ±1.4, female 3 ± 1.0 and male 10 ± 2.0, female 3 ± 0.7 in the dry and wet seasons of the year 2011; male,6 ± 1.4,female 6 ±1.4 and male,10 ± 2, female3 ± 0.8 in the dry and wet seasons of 2012.Infection showed significant differences (Z=-2.03,  P = 0.04) with both seasons in 2011 and no significant differences (Z=-1.41, P = 0.16) in 2012. Number of infected male and female flies was positively correlated with the fly age in the dry (Male, R2=0.94; female, R2=0.86) and wet (Male, R2=0.97; female, R2=1) seasons in 2011 and (Male, R2=0.90; female, R2=0.94) in the dry and wet (Male, R2= 0.97 female, R2=1) seasons in 2012.These results showed thatG. f.fuscipeswere  infected with T.brucei gambiense and  they were proved  to be potential vectors for HAT in the study area. Hence, the implications of Tsetse fly infection dynamics in the control of trypanosomiasis need development of further control strategies for sustainable development of livestock and human resources in Kajo-keji County.

Influence of self-efficacy management on adherence to self-care activities and treatment outcome among diabetes mellitus type 2 Sudanese patients

Background: High level of self-efficacy and adherence to self-care activities have a positive impact on the achievement of glycemic goal among diabetic patients. In Sudan, there is a gap in knowledge related to self-efficacy management and its influence on adherence to self-care activities and overall disease control. Objective: To identify the influence of management self-efficacy on adherence to self-care activities and treatment outcome among Sudanese patients with type 2 diabetes mellitus. Methods: A cross-sectional study was conducted at two health care facilities in Sudan from April to May 2016. Patients with type 2 diabetes mellitus were included. Convenience sampling method was adopted. Diabetes Management Self-Efficacy Scale and the Revised Summary of Diabetes Self-care Activities were used to collect data through a face-to-face interview. Logistic regression analysis was performed. A p value <0.05 was considered to be significant. Data were processed using the software SPPS v 21.0. Results: A total of 392 patients were included. Respondents classified with high level of self- efficacy across all domains were 191 (48.7%). Moreover, high level of education [adjusted OR 0.5 (0.3-0.7), (p=0.001)] and formal health education on diabetes [adjusted OR 2.4 (1.6-3.7), (p<0.001)], were found to be significantly associated with high level of diabetes management self-efficacy. Patients who had high level of self-efficacy to manage nutrition, physical exercise activity and medication were found more adherent to general diet, exercise activity, and medication taking, respectively. Patients with controlled disease were 87(22.2%). The only predictor of diabetes control was diabetes management self-efficacy [OR 2.1(1.3- 3.5), (p=0.002)]. Conclusions: Diabetes management self-efficacy was associated with high level of education and receiving health education. Self-efficacy was significantly associated with adherence to self-care activities and glycemic control. Substantial efforts are still needed to empower the patients with self-efficacy and improving adherence to self-care activities through appropriate interventions