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

Voltage Collapse and the Nigerian National Grid

A modern electric power system network (PSN) is typically a large and complex engineering system whose healthy existence is crucial to industrial and socio-economic development of Nations. Voltage instability and collapse contribute to large extent to system collapse or blackouts and it is one of the major concerns for today’s electric power system operations. The Nigerian National grid (NNG) experiences on an average of thirty-five (35) system collapse every year over the past ten (10) years. This paper presents an overview and classification of system collapse on the NNG. Keywords — Voltage collapse, Voltage instability, and Nigerian National Grid (NNG

Cryptococcal Meningitis Diagnostics and Screening in the Era of Point-of-Care Laboratory Testing.

Over the past ten years, standard diagnostics for cryptococcal meningitis in HIV-infected persons have evolved from culture to India ink to detection of cryptococcal antigen (CrAg), with the recent development and distribution of a point-of-care lateral flow assay. This assay is highly sensitive and specific in cerebrospinal fluid (CSF), but is also sensitive in the blood to detect CrAg prior to meningitis symptoms. CrAg screening of HIV-infected persons in the blood prior to development of fulminant meningitis and preemptive treatment for CrAg-positive persons are recommended by the World Health Organization and many national HIV guidelines. Thus, CrAg testing is occurring more widely, especially in resource-limited laboratory settings. CrAg titer predicts meningitis and death and could be used in the future to customize therapy according to burden of infection

The diversity of aquatic flora and their importance in the Victoria and Kyoga lake basins

A great part of Uganda is endowed with water bodies in the forms of rivers and open water lakes. These bodies are never alone. They are either flanked or associated with plants, which are adapted to the wet conditions. They are so characteristic that they are part and parcel of the aquatic ecosystems. They occupy various positions depending on the amount of water in the relevant habitats

Fault Tree-Based Reliability Assessment of a 132-kV Transmission Line Protection Scheme

The reliability of a power system network depends greatly on the performance of the protection system. Improving the reliability of the protection scheme of the transmission lines will enhance the overall reliability of the power system network. The focus of this paper is the improvement of the reliability of a power system transmission line using fault tree analysis (FTA). The paper considers the development of fault tree diagrams for the protection scheme of the 150km-long 132-kV transmission line in Northern Nigeria. The existing protection scheme is analyzed and compared with a proposed scheme equipped with a redundancy arrangement. And the result shows that the new scheme offers significant improvement (about 51%) in the availability of the line

Review of System Collapse Incidences on the 330-kV Nigerian National Grid

A modern electric power system network (PSN) is typically a large and complex engineering system whose healthy existence is crucial to industrial and socio-economic development of Nations. Voltage instability contributes to large extent to the system collapses or blackouts. It is a major concern for today’s electric power system operators. The Nigerian National grid (NNG) experiences on an average of thirty-five (35) system collapses every year over the past ten (10) years. This paper presents a review and classification of system collapses experienced on the Nigerian National Grid (NNG). It also reveals that on the average, the fault induced system collapse is about 88%. This implies that the NNG is highly venerable to voltage instability than other form of disturbances

KEPUTUSAN PEMBELIAN PRODUK COCA COLA (Studi Kasus Pada Wilayah Bluru, Sidoarjo)

Di dalam penelitian ini merek produk yang diangkat adalah produk minuman bersoda Coca-Cola seperti yang diketahui banyak orang merupakan merek minuman terpopuler dan laris dipasaran, namun pada saat ini kompetisi begitu ketat di pasar, merek yang kuat merupakansatu-satunya hal yang dimiliki oleh perusahaan yang membedakan dirinya, namun akhir-akhir ini kinerja produk Coca-Cola menurun masih kalah dengan Fanta, sehingga penulis mengangkat permasalahan tersebut Populasi dalam penelitian ini adalah agen di Bluru,Sidoarjo yang membeli produk minuman bersoda Coca-Cola. Sampel yang diambil adalah sebesar 60 responden. Data yang dipergunakan adalah data primer yaitu data yang berdasarkan kuisioner hasil jawaban responden. Sedangkan analisis data yang dipergunakan adalah Partial Least Square . Berdasarkan dari hasil penelitian yang telah dilakukan telah didapatkan bahwa : 1).Faktor Ekuitas merek berpengaruh terhadap Keputusan Pembelian signifikan (positif). 2). Faktor Promosi terhadap Keputusan Pembelian non signifikan (positif). Keyword : Ekuitas Merek,Promosi,Keputusan Pembelia

Synchronous Generator Excitation Chatter-Free Sliding Mode Controller

A chatter-free sliding mode controller (SMC) for synchronous generator excitation is presented in this paper. A linearized model of a single machine connected to an infinite bus is employed to design a variable-structure controller which not only stabilizes the system, but also ensures that this is maintained in the face of system parameter variations. Validating the robustness feature of an SMC, simulation results that show the dynamic performance of the system under both constant excitation and SMC-controlled excitation are presented

An Electronic Protection Unit for Diesel Engine Standby Generators

Today diesel engine-driven standby generators for backup power supply have been adopted for residential, commercial, and industrial use--especially in some developing countries where power from the utility company is highly erratic. Although many of these generators function well in operation, certain engine conditions, such as low oil pressure, high oil and water temperature, abnormally high speed, etc., could lead to malfunction, failure, or complete breakdown of the engine. Therefore, the focus of this work is to present the implementation of a simple, but effective electronic protection unit (EPU) capable of mitigating the adverse effect which may arise as a result of these conditions. It is composed of two major sub-circuits-the main protective sub-circuit and the timing sub-circuit-realized using a combination of passive and active components. Unlike the common electrical relay-based protection system, this unit has an additional advantage of being able to keep the faultindicating system of the generator working even after engine shutdown, thereby facilitating fault tracking. The unit has been tested on a diesel engine-driven generator and found to function satisfactorily. The test results are shown