On the production testing of analog and digital circuits

This thesis focuses on the production testing of Analog and Digital circuits. First, it addresses the issue of finding a high coverage minimum test set for the second generation current conveyor as this was not tackled before. The circuit under test is used in active capacitance multipliers, V-I scalar circuits, Biquadratic filters and many other applications. This circuit is often used to implement voltage followers, current followers and voltage to current converters. Five faults are assumed per transistor. It is shown that, to obtain 100% fault coverage, the CCII has to be operated in voltage to current converter mode. Only two test values are required to obtain this fault coverage. Additionally, the thesis focuses on the production testing of Memristor Ratioed Logic (MRL) gates because this was not studied before. MRL is a family that uses memristors along with CMOS inverters to design logic gates. Two-input NAND and NOR gates are investigated using the stuck at fault model for the memristors and the five-fault model for the transistors. It is shown that in order to obtain full coverage for the MRL NAND and NOR gates, two solutions are proposed. The first is the usage of scaled input voltages to prevent the output from falling in the undefined region. The second proposed solution is changing the switching threshold VM of the CMOS inverter. In addition, it is shown that test speed and order should be taken into consideration. It is proven that three ordered test vectors are needed for full coverage in MRL NAND and NOR gates, which is different from the 100% coverage test set in the conventional NAND and NOR CMOS designs

Examining the terminology of race issues in assessments for international exchange students

This study examined assignments by students from a university in Scotland and a university in the USA, and explored the terminology used by student when referring to race issues in assignments linked to practice. The findings suggest the terminology of race issues in assessments may be inappropriate for students because they allow racism to be marginalized from practice or presented in a way that conveys little analysis

Copper (II) Adsorption by Calcium-alginate Shea Butter Cake

This study investigated the utilization of modified shea butter cake for the removal of Cu(II) ions from aqueous solution. Instrumental analysis such as Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), X-ray Diffractometer (XRD) was used for the characterisation of the solid sorbent. Batch equilibrium study was carried out to evaluate the adsorption capacity, and process parameters such as initial metal ion concentration, time, pH, and adsorbent dosage. An optimum pH of 5, equilibrium time of 30mins and adsorbent dosage of 40 beads was obtained. The Langmuir and Freundlich isotherms were used to fit the experimental data and values fits the Langmuir more adequately with correlation coefficient unity (1.000) at 10mg/l of initial metal ion concentration. The Kinetic study using the Pseudo-first-order and pseudo-second were used to determine the rate constants and experiments data best fits the pseudo-second –order with calculated amount adsorbed approximately equal to the experimental values. The results indicate that modified shea butter cake could be employed as an adsorbent for the removal of copper (II) ions in an aqueous solution. Keywords: Shea butter cake, process parameters, kinetics, Copper (II)

Synthesis of Gamma-Alumina from Kankara Kaolin as Potential Zeolite Active Matrix

Commercial fluid catalytic cracking catalysts are manufactured using zeolites dispersed on an amorphous matrix, which is mostly alumina. Alumina is widely used as catalyst support in many heterogeneous catalytic processes owing to its high surface area, superior chemical activity and low cost. In compounded zeolite catalyst it serves as the active matrix which aids the conversion of the bulkiest molecules in the feed owing to its larger pore size than zeolite. Large specific surface area gamma-alumina (γ-Al2O3) was synthesized by hydrothermal method using Kankara kaolin as starting material. Thermal treatment of ammonium alum prepared from the filtrate of the dealuminated metakaolin was employed to obtain the alumina. Crystalline aluminum sulfate with 39 wt% Al2O3 was obtained at calcination temperature of 800°C with 3 h soaking. Gamma-alumina was produced at 850°C with 3 h soaking time, having specific surface area of 166 m2/g. The weight percent of Al2O3 content in the synthesized and commercial gamma-alumina were 85% and 89% respectively as obtained from the XRF analysis. Good comparison was also observed in the diffractogram of the synthesized and commercial gamma-alumina from the XRD analysis. The Scanning Electron Microscopy (SEM) image showed the platy hexagonal shape of the gamma-alumina.Keywords: Gamma-alumina, zeolite, kaoli

Genetic diversity of Hajar1 and Hajar2 local Saudi chicken lines using mitochondrial DNA D-loop markers

This study was conducted to assess genetic diversity of Hajar1 and Hajar2 local Saudi chicken lines using mitochondrial DNA (mtDNA) D-loop partial sequences. One hundred blood samples were obtained equally from Hajar1 and Hajar2 Saudi chicken lines as 50 samples from each line. The D-loop region was partially amplified from genomic DNA with a conserved primer set, and the fragments were sequenced. Eight published reference mtDNA sequence data from the GenBank were used for comparisons, and multiple alignments were performed. The most common haplotype was assigned as a basic sequence for comparing within each line. Entropy plot and conserved region analysis were performed. Genetic distances and neighbour-joining (NJ) phylogenetic trees were estimated. The results indicated haplotype variations within and between local Saudi chicken lines, which could explain the phenotypic variation reported earlier. A close genetic relationship was shown between the Saudi local chicken lines. Unique conserved regions and nucleotide substitutions were observed between the two lines. Both lines have a close relationship with the reference Asian local chicken population, especially local Chinese and Indian chicken breeds. The current results are considered the first report of mtDNA sequence diversity for Hajar1 and Hajar2 lines. Further detailed molecular genetic studies of both lines are indispensable to genetic conservation and development.Keywords: chicken population, diversity, D-loop, Hajar1, Hajar2, mtDN

Demonstration of On-Board Maneuver Planning using Autonomous S/W Architectures

The need for higher level of SIC autonomy is gaining increased importance in future space missions planning. These autonomous capabilities are needed not only to reduce the overall mission life-cycle cost but also to enable a new class of planetary missions (comets, asteroids, moons, etc.) requiring rendezvous and/or sample return. Some of the key candidate technologies identified for such missions include, autonomous approach/rendezvous/descent navigation, autonomous maneuver planning and implementation, and target based pointing and tracking. This paper presents the results of implementation and simulation of on-board maneuver planning, where a high level command is implemented while satisfying mission flight rules and spacecraft constraints. As part of this effort, a candidate spacecraft simulation is developed within a S/W architecture that provides a set of constructs suited for implementation of high level task decomposition and planning as well as on-line constraints checking and exception handling functions. The software architecture allows for future incremental refinements or addition of new autonomous capabilities as mission needs evolve

Objective Method for Determination of Potato Cooking

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a Technical article from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 2 (2000): Jioi Blahovec, Ahmed A.S.Esmir, Josef Vacek. Objective Method for Determination of Potato Cooking

Reduction of Sulphur Content of Urals Crude Oil Prior to Processing Using Oxidative Desulphurization

The presence of sulphur in crude oil poses enormous challenges as regards its negative environmental and economic impacts. As such, the safety of the personnel and the equipment is at high risk during the processing of Urals crude oil in Kaduna Refining and Petrochemical Company (KRPC) because of its sour nature. This study was aimed at reducing the sulphur content of the Urals crude oil prior to processing by subjecting it to oxidative desulphurization where peracetic acid was used as the oxidant in the actual mass-to-stoichiometric mass ratio ranging from 1 to 5. The oxidized sulphur compounds were thereafter extracted using acetic acid as the extraction solvent. Furthermore, atmospheric distillation was carried out on both the raw and the desulphurized crude oil samples. Finally, the sulphur contents of the various crude oil samples and their fractions were analyzed. The results showed drastic reductions in the sulphur contents up to actual mass-to-stoichiometric mass ratio of 2 but the reductions became progressively insignificant afterwards. Meanwhile, the highest reduction in the sulphur content of the crude oil was 61.6 % while those of the gasoline, kerosene, diesel and residue were 32.0, 45.1, 68.9 and 75.0 % respectively. Therefore, peracetic acid is an effective oxidant for oxidative desulphurization of the crude oil.Keywords: Sulphur content, Crude oil, Oxidative desulphurization, Thiophenic compound

Formulation of critical micellar concentration of non- phosphate detergents by surface tension measurement

Non-phosphate builders which are environmentally friendly are required for use in detergent formulation to replace the sodium tri-poly phosphate (STPP). Phosphates are excellent fertilizer for algae, bacteria, and other flora and fauna in rivers, lakes and  oceans, making them bloom at very rapid rates. This exhausts the oxygen supply both in the surface and in the bottom layers of water bodies, and leading the death of fishes. Sodium metasilicate a non-phosphate builder from Lokoja Quartzite was used to  formulate a non-phosphate biodegradable synthetic detergent using 25%, 50% and 75% sodium hydroxide concentrations. The critical micellar concentration (CMC) of a non-phosphate  detergent was determined via measurement of surface tension. This method is rapid, reliable and cheap compared to the  fluorescence polarization method which required a sophiscated materials such as 1,6-diphenyl-1,3,5-hexatriene as fluorescence probe. The detergents formulated with 75% and 50% sodium hydroxide concentrations have CMC values of 8.6685 mM and 6.9348 mM respectively. From this study, a non phosphate builder synthesized from Lokoja Quartzite has potential of protecting aquatic animals when compared with the conventional STPP currently used in our detergent formulation. Also, the simple and economical approach for determination of detergent’s CMC has demonstrated it’s potentials. These values agree well with the literature value ranges between 7 to 10 mM.Keywords: Detergent; CMC; Surfactants; Non-phosphate;  1,6-diphenyl-1,3,5-hexatrien

Effect of groundnut shell powder on the viscoelastic properties of recycled high density polyethylene composites

In the quest to clean up the environment and produce economically viable materials from plastic wastes and readily available natural fibres, groundnut shell powder reinforced recycled high density polyethylene composite was prepared via two roll melt mixing and compression moulding technique. The dynamic mechanical properties of the composites such as storage modulus (E'), loss modulus (E''), and damping parameter (Tan ∂) were investigated using 242E dynamic mechanical analyzer in a temperature range from 30oC 100oC at a frequency of 1 Hz. It was found that the storage modulus of all the composites decrease with increase in temperature with composite containing 25%wt fibre having maximum E' value of 1158.47MPa compared to 1033.58MPa of the unreinforced recycled high density polyethylene. These results indicated that the thermal stability and load bearing capacity of the recycled high density polyethylene have been improved with the incorporation of groundnut shell powder. Scanning Electron micrographs showed better interfacial adhesion between treated groundnut shell powder in the polymer matrix; this explained the observed improvement in the viscoelastic properties of the composites.Keywords: Mechanical Properties, Groundnut Shell Powder, Recycled polyethylene, Viscolastic, Composites