Experimental Investigation of Segregation of Granular Materials using the Vibrational Phenomenon

Many industrial processes including food, mining, material and pharmaceuticals involve the handling of granular materials. Thetendency of granular materials to segregate due to variation of certain parameters as well as differences in particle propertiessuch as size, density, shape negatively affect the process efficiency and product quality. In this study, the segregation phenomenaof different large particles in a granular bed were studied experimentally in a Perspex box that was vibrated vertically. In particular, the effect of frequency, bed depth, particle size and density were investigated. The result showed that the segregationat relatively constant acceleration was found to decrease within the frequency range 20 Hz-40 Hz. On the other hand, thesegregation then increases with increasing frequency. Furthermore, within the same frequency range, segregation was observedto further decrease with increasing acceleration, and then gradually starts decreasing exponentially with frequency. In addition,the segregation rate was higher at a greater bed depth for all vibratory conditions. The segregation trend was found to increasewith the size of the particles for all vibratory conditions. Nonetheless, for all vibratory conditions, the segregation rate was lowerfor intruder particles with higher densit

Fault Detection and Isolation of a Three-tank System Using Analytical Temporal Redundancy – Parity Space/Relation Based Residual Generation

This paper investigates the fault detection and isolation technique in measurement datasets from a three-tank system using analytical model-based temporal redundancy. It is based on residual generation using a parity equations/space approach. Thepaper further briefly outlines other approaches of model-based residual generation. The basic idea of parity space residual neration in temporal redundancy is a dynamic relationship between sensor outputs and actuator inputs (input-output model).These residuals were then used to detect whether or not the system is faulty and indicate the location of the fault when it is faulty.The method obtains good results by detecting and isolating faults from the considered measurement datasets generated from the system

CONTROLLER DESIGN FOR MAGNETIC LEVITATION SYSTEM USING BACTERIA FORAGING ALGORITHM TECHNIQUE

This paper presents the use of Bacteria Foraging Optimization Algorithm (BFOA) to tune Proportional, Integral and Derivative (PID) controller parameters for real time control of Feedback 33-210 Magnetic Levitation System (MLS). The system is hardwarein the loop training kit based on MATLAB which gives leverage for controller modification or adaptability. It consists of inbuiltPID and PD controllers. The inbuilt system PID gains were tuned for optimal performance of the real-time system in regulatingthe ball position and tracking a reference input. Real-time system gave the percentage error of 11.8% and 33.6% for the optimaland inbuilt PID controllers respectively. Similarly, real-time system results gave the percentage error of 81.4% and 128.7% for optimal and inbuilt PD controllers respectively. Simulation results gave the percentage error of 0.65% and 23.7% for the optimaland inbuilt PID controllers respectively. Its PD controller counterpart presents the percentage error of 18.4% and 336.6% foroptimal and inbuilt simulations scenarios respectivel

NTC Thermistor Performance and Linearization of its Temperature-Resistance Characteristics Using Electronic Circuit

This paper critically discusses the performance of an NTC thermistor sensor in the temperature range 20 oC to 85 oC and provides a technique for linearization of the temperature sensed by the thermistor. The linearization was achieved by utilizing Wheatstone bridge electronic circuitry which responds to the thermistor and produces an output which is an exponential function of the temperature sensed by the thermistor sensor. A further simple and low-cost electronic circuitry responds to such output and converts the resistance measurement to provide a signal which represents the temperature. Moreover, the Wheatstone bridge signal conditioning circuitry was designed to have 0 – 100 mV output voltage within the considered temperature range. The physical characteristics of the thermistor (constant A and b ) were found to be 4.0015 x 10-5 ± 0.2956 x 10-5 Ω and 3514.8 ± 11.6 K respectively. The result also shows that the percentage nonlinearity was as low as 1.7 and a sensitivity value of 1.5661 mV/K was found for the thermistor, but the resolution of this thermistor sensor is 2 oC. However, the percentage of nonlinearity obtained was in agreement with the theoretical percentage nonlinearity

Occurrence, abundance and distribution of benthic macroinvertebrates in the Nyando River catchment, Kenya

A baseline study was conducted of the occurrence of macroinvertebrates at 26 sites in the Nyando River catchment in 2005-2006. A total of 13 orders and 16 families of Arthropoda, Mollusca, Platyhelminthes and Annelida were collected, with the order Ephemeroptera being most abundant in the up- and mid-stream reaches, followed by Hemiptera and Plecoptera respectively. The downstream sections of the river were dominated by Hirudinea and tubificids, as the water quality deteriorated mainly due to local land use, raw sewage effluent discharge and annual floods. Insects and annelids were the main invertebrates found and the extent of pollution increased from mid-section (Site 15) downwards as the river flowed into the Winam Gulf. Stringent management measures are required to safeguard the environment and ecosystems of Lake Victoria.Funding Agencies|International Foundation for Science (IFS) [W3982-1]; Higher Education Loans Board (HELB), Kenya</p

Absence of Association between Cord Specific Antibody Levels and Severe Respiratory Syncytial Virus (RSV) Disease in Early Infants: A Case Control Study from Coastal Kenya

The target group for severe respiratory syncytial virus (RSV) disease prevention is infants under 6 months of age. Vaccine boosting of antibody titres in pregnant mothers could protect these young infants from severe respiratory syncytial virus (RSV) associated disease. Quantifying protective levels of RSV-specific maternal antibody at birth would inform vaccine development. METHODS: A case control study nested in a birth cohort (2002–07) was conducted in Kilifi, Kenya; where 30 hospitalised cases of RSV-associated severe disease were matched to 60 controls. Participants had a cord blood and 2 subsequent 3-monthly blood samples assayed for RSV-specific neutralising antibody by the plaque reduction neutralisation test (PRNT). Two sample paired t test and conditional logistic regression were used in analyses of log2PRNT titres. RESULTS: The mean RSV log2PRNT titre at birth for cases and controls were not significantly different (P = 0.4) and remained so on age-stratification. Cord blood PRNT titres showed considerable overlap between cases and controls. The odds of RSV disease decreased with increase in log2PRNT cord blood titre. There was a 30% reduction in RSV disease per unit increase in log2PRNT titre (<3months age group) but not significant (P = 0.3). CONCLUSIONS: From this study, there is no strong evidence of protection by maternal RSV specific antibodies from severe RSV disease. Cord antibody levels show wide variation with considerable overlap between cases and controls. It is likely that, there are additional factors to specific PRNT antibody levels which determine susceptibility to severe RSV disease. In addition, higher levels of neutralizing antibody beyond the normal range may be required for protection; which it is hoped can be achieved by a maternal RSV vaccine