Volume 25, No. 1 (2019)

EFFECT OF GEOPHYSICAL PARAMETERS ON ATTENUATION OF CONTAMINANT IN FRESHWATER COASTAL AQUIFERS

ADEGOKE JAMES ADEYEMO(1), OLATUNDE I. POPOOLA(1), OLUDOTUN OMONIYI FALUYI(*1,2)

Freshwater coastal aquifers can be contaminated by influx of seawater. The study investigated the effect of geophysical parameter such as seepage velocity (v) determined empirically on the mass flux (J) of contaminant through the coastal aquifers. Porosities of the grains were determined and tagged samples A to E. v was obtained in the experimental setup. Results showed that hydraulic gradient ranged between 3.233 to 0.317 while the corresponding values of contaminant J ranged between 0.302 to 5.381 Kgm-2s-1 within 60 to 360 seconds. Therefore, the attenuation coefficients of J decreased with increased in flow rate of fluid through the samples.

ARTIFICIAL NEURAL NETWORK IN THE MODELLING OF THE EFFECT OF CHROMIUM DOPANTS ON THE MECHANICAL PROPERTIES OF AL-4%CU ALLOY

EYERE EMAGBETERE (*1), OGHENEKOWHO PETER ARUOTURE(1), FESTUS IFEANYI ASHIEDU(1)

Artificial Neural Network (ANN) was used to model the effect of Chromium dopants on the mechanical properties duralumin (Al-4 %Cu). The results showed that the hardness, yield strength, and ultimate tensile strength increased, while the energy absorbed and percentage elongation decreased, with increasing %wt of Chromium dopants. Simulation results of ANN show strong agreement with experimental values, having satisfactory R-values of Mean Square Error. ANN can suitably be used to predict the mechanical properties of Al-4%Cu doped with Chromium.

NEW PYRIDINE-3-SULFONATO TIN (IV), ANTIMONY (III) AND (V) HALO ADDUCTS AND COMPLEXES: SYNTHESIS AND INFRARED STUDY

AÏSSATOU GUEYE(1), MOUHAMADOU BIRAME DIOP(1) , LIBASSE DIOP(1)

Six new tin (IV), antimony (III) and antimony (V) adducts and complexes have been synthesized. Discrete structures were suggested on the basis of infrared data. Within the structures, the anion behaves as a bidentate, monochelating and monodentate, monodentate and tri O-chelating ligand. The environments around metallic centres are octahedral. Considering preamble of extra hydrogen bonds in compounds containing water molecules and/or OH groups, supramolecular architectures may be given rise.

EVALUATION OF THE MODEL PREDICTION TOXICITY (LD50) FOR SERIES OF 42 ORGANOPHOSPHORUS PESTICIDES

HANANE FIKRI(*1), TAOUFIQ FECHTALI(1), MOHAMED MAMOUMI(1)

Structure-Toxicity Relationships have been studied for a set of 42 organophosphorous pesticides (OPs) through multiple linear regression (MLR) and artificial neural networks (ANN). A model with three descriptors, including: total lipophilicity [log (P)], widths radicals R1 [(LR1)] and R2 [(LR2)] has achieved good results in phase Training and phase prediction of toxicity [log LD50 (lethal dose 50, Oral rat)]. The linear model (MLR: n=40, r²=0.86, s=40 and q2 = 0.66) and non-linear model with a configuration [3-6-1] (ANN: r²=0.95, s=0.73 and q2 = 0.17) have proved very successful and complementary. The selected descriptors indicate the importance of lipophilicity and widths radicals R1 and R2 in the contribution of the toxicity of pesticides derived from OPs used in this study. This information is relevant for the design of a new model of non-toxic pesticides OPs.

CHEMICAL REAGENTS FOR SELECTIVITY IN IMPROVEMENT OF RHEOLOGICAL PROPERTIES OF CRUDE OIL

VALI HANAQA NURULLAYEV(*1), BEYBALA TACI USUBALIYEV(2), FIKRET SULEYMAN GEHREMANOV(1), ULKER FIKRET GEHREMANOVA(2)

Today oil industry – one of the most developing and priority industries of Azerbaijan which plays a huge role in national economy. The need for this mineral constantly increases therefore for improvement of quality and decrease in cost of the product mining companies need to modernize constantly not only the oil-field equipment, but also to improve production processes. Now the increasing number of high-sulphurous and high-paraffinic oil fields is brought into development. As a result, the corrosion rate of the oil-field equipment increases, the output of wells decreases and expenses of mining companies in general raise.

PULSE WIDTH MODULATION TECHNIQUE FOR THE SPEED CONTROL OF M-PHASE AC MOTORS

EGWAILE JOEL OSARUMWENSE*, ORIAHI MATTHEW

Thyristors are now widely used in many power electronics and motor driven applications and all the known methods of control are nothing but variations of either the phase angle firing control (PFC) or the pulse width modulation control (PWM). Each of these methods has its own benefits and disadvantages, but the pulse width modulation control method is, perhaps, by far, the most effective and costly method. Since PWM differs from phase firing control (PFC) in that the control action of PWM takes place only during the time of the firing pulse, this research seeks to develop a combination firing package that maximizes the benefits of the two methods. At first a thyristor is configured as a PNP-type power transistor latch with two ordinary NPN bipolar switching transistors. The power transistor is switched on by zero crossover firing and then switched off by phase angle delay firing. The performance of the model was evaluated and the dynamic characteristics of the motor, such as speed, current, voltage and the total harmonic distortion were carried via simulation. The results shows that by using the Modified PWM firing technique the speed of an m-phase induction motor can be controlled more effectively and reliably. The circuit is easy to implement and cost effective and may be patented and made available for commercial use.