Root Locus-Based Magnetic Levitation System Stabilization: An Undergraduate Control System Design Approach

The subject of control system design has evolved considerably over the years. Although several design techniques and strategies have been adopted to realize control systems that meet a predetermined set of performance criteria, the fundamental problem remains that of developing controllers to adjust the performance characteristics of a dynamic system in order to obtain a desired output behavior. The dynamic behavior of a magnetic levitation system (MLS) of a ferromagnetic ball is compensated in this paper. Consolidating the exposure of undergraduate students to the rudiments of control system design, the paper employs the classical root locus technique to stabilize the system. A combination of analytical and software-based methods is used to design proportional-derivative and phase-lead compensators based on the linearized model of the system. Complete details of the design approach, from modeling and analysis of the plant to computing the values of the controller parameters, are shown. MATLAB scripts for plotting root loci and simulating the system are provided

Assessment of wind energy potential of two sites in North-East, Nigeria

The study is used to assess the wind energy potential of Maiduguri and Potiskum, two sites in North-East, Nigeria. 21 years (1987e2007) monthly mean wind data at 10 m height were assessed from the Nigeria Meteorological department and subjected to 2-parameter Weibull and other statistical analyzes. The result showed that average monthly mean wind speed variation for Potiskum ranged from 3.90 to 5.85 m/s, while for Maiduguri, it ranged from 4.35 to 6.33 m/s. Seasonally, data variation between the dry and wet seasons revealed that, the mean wind speed variation for Potiskum ranged from 4.46 (for dry) to 5.16 m/s (for wet), while for Maiduguri it ranged from 5.10 (dry) to 5.59 m/s (wet). The wind power density variation based on the Weibull analysis ranged from 102.54 to 300.15 W/m2 for Potiskum and it ranged from 114.77 to 360.04 W/m2 for Maiduguri respectively. Moreover, Maiduguri was found to be the better of the sites in terms of monthly and seasonal variation of mean wind speed, but they both can be suitable for stand alone and medium scale wind power generation

Differences in the epidemiology of theileriosis on smallholder dairy farms in contrasting agro-ecological and grazing strata of highland Kenya

A prospective cohort study was conducted in five purposively-sampled agro-ecological zone (AEZ)-grazing system strata in Murang’a District, Kenya, between March 1995 and June 1996. The study strata were selected based on a preliminary characterization study to represent the widest range of risks to East Coast fever (ECF) in the District and included zero-grazing and open-grazing farms. In total, 225 calves from 188 smallholder farms were examined from birth to 6 months of age and visited within the first 2 weeks of life and thereafter at bi-weekly intervals for up to 14 visits. The purpose of the study was to characterize the differences in epidemiology (risks of infection, morbidity and mortality) and potential control of ECF between the selected strata. Evidence of Theileria parva infection was assessed by increased antibody levels as measured in an indirect ELISA assay by the percent positivity (PP) of serum samples relative to a strong positive reference serum. Sero-conversion risks of T. parva were highest in the open-grazing strata. Antibody prevalence in adult cattle and ECF morbidity and mortality risks were also highest in open-grazing strata. While different, all five AEZ-grazing strata were considered to be endemically unstable for ECF. East Coast fever challenge was low in all zero-grazing strata and this challenge is likely to remain low due to continuing intensification of smallholder farming in the central highlands. In the open-grazing strata, there was higher challenge and a greater impact of ECF. ILRI publication no.: 99017

ENGINEERING MATHEMATICS EDUCATION WITH COMPUTER ALGEBRA: THE MATLAB ALTERNATIVE

Computer algebra systems have become an important tool for many engineering and technical professionals. There is a growing need to incorporate such tools into the education of such professionals. This paper discusses these systems and their role within engineering mathematics in higher education. Some advantages and problems associated with computer algebra are highlighted and illustrated using MATLAB