Accelerating Manufacturing Decisions using Bayesian Optimization: An Optimization and Prediction Perspective

Manufacturing is a promising technique for producing complex and custom-made parts with a high degree of precision. It can also provide us with desired materials and products with specified properties. To achieve that, it is crucial to find out the optimum point of process parameters that have a significant impact on the properties and quality of the final product. Unfortunately, optimizing these parameters can be challenging due to the complex and nonlinear nature of the underlying process, which becomes more complicated when there are conflicting objectives, sometimes with multiple goals. Furthermore, experiments are usually costly, time-consuming, and require expensive materials, man, and machine hours. So, each experiment is valuable and it\u27s critical to determine the optimal experiment location to gain the most comprehensive understanding of the process. Sequential learning is a promising approach to actively learn from the ongoing experiments, iteratively update the underlying optimization routine, and adapt the data collection process on the go. This thesis presents a multi-objective Bayesian optimization framework to find out the optimum processing conditions for a manufacturing setup. It uses an acquisition function to collect data points sequentially and iteratively update its understanding of the underlying design space utilizing a Gaussian Process-based surrogate model. In manufacturing processes, the focus is often on obtaining a rough understanding of the design space using minimal experimentation, rather than finding the optimal parameters. This falls under the category of approximating the underlying function rather than design optimization. This approach can provide material scientists or manufacturing engineers with a comprehensive view of the entire design space, increasing the likelihood of making discoveries or making robust decisions. However, a precise and reliable prediction model is necessary for a good approximation. To meet this requirement, this thesis proposes an epsilon-greedy sequential prediction framework that is distinct from the optimization framework. The data acquisition strategy has been refined to balance exploration and exploitation, and a threshold has been established to determine when to switch between the two. The performance of this proposed optimization and prediction framework is evaluated using real-life datasets against the traditional design of experiments. The proposed frameworks have generated effective optimization and prediction results using fewer experiments

Functional changes of the vasculature in HIV/AIDS patients on Haart and Haart Naïve HIV participants

The present study sought to explore the functional changes that occur in the vasculature of HIV positive participants of African origin in Mthatha district of South africa which might lead to increased risk in their cardiovascular system. Available literature shows that arterial stiffness plays an important role in cardiovascular events such as stroke, vasculitis and myocardial infarction. Measurement of (aortic pulse wave velocity; PWV) provides some of the strongest evidence concerning the prognostic significance of large artery stiffening. This study was aimed at investigating the relationship between anthropometry, age, E-Selectin level, cytokine levels, haemodynamic variables, blood counts and blood lipid profile with pulse wave velocity. Some traditional cardiovascular risk factors such as alcohol, and smoking were also taken into account. This was a cross-sectional study comprising of 169 participants (62 males and 107 females). 63 were HIV negative (group A), 54 HIV positive on treatment (group B), and 52 were HIV positive not on treatment (group C). Pulse wave velocity (PWV) was assessed using the Sphygmocor Vx. Statistically, ANOVA was used for variables with normal distribution and non parametric tests were used for variables with skewed distribution. Notable significant differences were seen in the means of the following variables across all the 3 groups. Conclusion: This study showed that HIV infected patients with or without antiretroviral therapy have increase arterial stiffness which is associated with an increased cardiovascular risk. The sphygmocor is an accurate, non invassive and useful tool in the evaluation of arterial stiffness and its use in clinical practice should be encouraged. PWV and the augmentation index (AIx) are the two major non- iv invasive methods of assessing arterial stiffness. Life style modification should be incorporated into the management of HIV patients so as the continuous monitoring of their haematological and lipid profile

Variation in the susceptibility of Anopheles gambiae to botanicals across a metropolitan region of Nigeria

Pesticide resistance is normally associated with genetic changes, resulting in varied responses to insecticides between different populations. There is little evidence of resistance to plant allelochemicals; it is likely that their efficacy varies between genetically diverse populations, which may lead to the development of resistance in the future. This study evaluated the response of Anopheles gambiae (larvae and adults) from spatially different populations to acetone extracts of two botanicals, Piper guineense and Eugenia aromatica. Mosquito samples from 10 locations within Akure metropolis in Southwest Nigeria were tested for variation in susceptibility to the toxic effect of botanical extracts. The spatial distribution of the tolerance magnitude (T.M.) of the mosquito populations to the botanicals was also mapped. The populations of An. gambiae manifested significant differences in their level of tolerance to the botanicals. The centre of the metropolis was the hot spot of tolerance to the botanicals. There was a significant positive correlation between the adulticidal activities of both botanicals and initial knockdown. Hence, knockdown by these botanicals could be a predictor of their subsequent mortality. In revealing variation in response to botanical pesticides, our work has demonstrated that any future use of botanicals as alternative environmentally friendly vector control chemicals needs to be closely monitored to ensure that resistance does not develop

Study of atmospheric pollution levels by trace elements analysis of tree bark and leaves

The concentrations of Pb, Cu, Zn, Ni, Fe, and Mn in leaf and bark samples of 7 tree species at 22 sampling locations with different pollution levels, in Ogbomoso, Nigeria, were investigated. The metal concentrations (mean ± RSD in mg g-1) in leaf and bark samples, respectively, were: Pb, 203±70, 282±120; Cu, 19.5±4.2, 12.7±2.6; Zn, 42.7±12.9, 42.8±13.1; Ni, 30.0±11.1, 20.0±9.9; Fe, 869±348, 504±118; and Mn, 108±18, 73.7±13.8. The high-pollution automobile parking lots showed higher levels of these elements (p < 0.05). The correlation coefficient between element pairs of high and low-pollution automobile parking lots was carried out to determine the extent of relationship between the elements investigated. KEY WORDS: Atmospheric pollution, Trace elements analysis, Tree bark, Tree leaves  Bull. Chem. Soc. Ethiop. 2003, 17(1), 11-17

Colletotrichum circinans and Colletotrichum coccodes can be distinguished by DGGE analysis of PCR-amplified 18S rDNA fragments

The rDNA 18S region of Colletotrichum circinans and C. coccodes was amplified by PCR to evaluate this DNA region as a tool for species delineation. PCR amplification of the 18S of both species produced 1.65 Kb long fragments that covered most of the entire 18S rDNA molecule. DGGE analysis of the amplified fragments distinguished C. circinans from C. coccodes isolates. This result provides molecular evidence that supports the current treatment of C. circinans as a species distinct from C. coccodes, in spite of the failure of previous attempts at genetic differentiation of the two species based on RFLP analysis of the rDNA ITS region. Key Words: DGGE; Colletotrichum circinans; Colletotrichum coccodes; molecular differentiation; species delineation. African Jnl Biotechnology Vol.3(3) 2004: 195-19

Removal of Basic Dye From Aqueous Solution By Adsorption On Melon Husk In Binary And Ternary Systems

The adsorption behaviour of a cationic dye (methylene blue)   in binary and ternary solutions on the husk of melon (Citrullus lanatus) seed was investigated in order to elucidate the effects of competitive adsorption on the kinetics and thermodynamics of the sorption process.  The experimental findings showed that adsorption equilibrium was reached within 120 min either in single, binary or ternary mixtures; and the   adsorption processes in all the systems studied were described by the pseudo-second order kinetics with the initial rate constant increasing as the  concentrations of the competing dyes were increased.  Five different equilibrium isotherm models ( Freundlich, Temkin, Langmuir, Harkin-Jura and Dubinin-Radushkevich) were applied and  Langmuir was the best-fitting one for the adsorption of methylene blue dye in single system (R2 &gt; 0.99), while the binary and ternary systems were best described by Freundlich model (R2 &gt; 0.99). The sorption processes were thermodynamically feasible as ?G values were negative. Adsorption in both single and binary systems was exothermic while that of ternary system was endothermic. Keywords: melon husk, binary dye system, ternary dye system, methylene blue,                       Competitive adsorption, isotherms, thermodynamics, basic dy

Aliphatic and polycyclic aromatic hydrocarbons profiles of photomodified natural bitumen of Agbabu, Southwestern Nigeria

The impact of sunlight on aliphatic and polycyclic aromatic hydrocarbons profiles of Agbabu natural bitumen in Nigeria was investigated. The raw flow type of the bitumen was purified and exposed to sunlight for six consecutive months. Different portions of the bitumen were withdrawn at an interval of one month and were separated into aliphatic and polycyclic aromatic hydrocarbon fractions by column chromatography, followed by the GC analyses of various fractions. The total aliphatic hydrocarbon content was found to be 485, 424, 416 and 392 g/kg for control, one, three and six months solar-irradiated bitumen samples, respectively; while the total polycyclic aromatic hydrocarbons content found in the control, one, three and six months solar-irradiated bitumen samples were 708, 733, 609 and 638 µg/g, respectively. The effects of sunlight on the compositional patterns of bitumen were discussed. KEY WORDS: Agbabu, Bitumen, Sunlight, GC, Aliphatic hydrocarbon, Polycyclic aromatic hydrocarbon  Bull. Chem. Soc. Ethiop. 2010, 24(3), 461-466

Synthesis and fungicidal activity of acetyl substituted benzyl disulfides

The synthesis and fungicidal activity of acetyl substituted benzyl disulfides 1(a – g) are reported. The compounds were characterized by elemental analysis, nuclear magnetic resonance (1H NMR and 13C NMR) and mass spectrometric techniques. The results of the biological screening showed that the synthesized compound possess very high fungicidal activity. KEY WORDS: Acetyl substituted benzyl disulfides, Fungicidal activity  Bull. Chem. Soc. Ethiop. 2003, 17(1), 53-60

Spectral Transmission of Porcine Crystalline Lens at Post-Mortem Interval

Purpose: Determining the total spectral transmission of the porcine crystalline lens at various post mortem intervals. Method: An experimental study conducted in the Department of chemical Pharmacology, Faculty of pharmacy, University of Benin. Twenty pairs of porcine eyes were obtained from an abattoir in Benin City. The crystalline lenses were carefully extracted from the enucleated porcine eyes at various post- mortem intervals (0, 12, 24, 36 and 48hours) and their spectral transmissions were measured using a T80 UV-VIS Spectrophotometer. Measurement at 0 hour was used as a control being the baseline. Result: The result showed a strong negative correlation between increased post mortem intervals and transmission of the crystalline lens for both eyes, as the post-mortem time interval increases, the transmission of long wavelengths (r = -0.992, P = 0.001), mid wavelengths (r = -0.994, P = 0.000)&nbsp; and short wavelengths(r = -0.991, P = 0.001) decreases significantly. It was also observed there was no significant difference (P&gt; 0.05) existed&nbsp; between both eyes in the different wavelength regions with increased post mortem interval. Conclusion: The study shows that time after death has effect on the spectral transmission of crystalline lens which can serve as important information in forensic evaluation. Key words: Post mortem interval, crystalline lens, spectral transmission, spectrophotometer and porcine