Finite element analysis of blade-formation interactions in excavation

The efficiency and costs of mining operations greatly depend on the efficient design and use of excavators. The performance of these capital-intensive excavators requires thorough understanding of the physical and design factors that affect the formation-cutting tool interaction process. The current body of knowledge, based on experimental and analytical methods, provides limited understanding of these factors, which limits the accurate design and performance of excavators. The soil constitutive equations used in most of the available finite element (FE) models also fail to adequately capture the elastic and plastic behaviors of soil formations. This research initiative uses FE techniques to model the soil-tool interaction phenomenon, with appropriate focus on the behavior of soils during excavation. This is a pioneering effort in developing FE model of the soil-dozer blade interaction using the modified Cam Clay elasto-plastic law. The model is validated with results from previous experimental and analytical methods. The results provided soil forces, a progressive developed failure zone, displacement fields and stress distribution along the tool surface. The sensitivity analysis of changes in blade angle on cutting force showed that, the cutting force increases with increasing blade angle. The cutting depth of the blade had a similar effect on blade cutting force. Increasing the depth of cut increases the required cutting force. Increasing the coefficient of friction at the soil blade interface increases the blade cutting force. Reducing the coefficient of friction at the soil blade interface from 0.3 to 0.05 reduces the cutting force by 22.3%. The percentage represents the maximum potential savings in blade cutting force. This research initiative advances the frontiers of soil-tool interactions, during excavations, to expand the limited knowledge in this critical area --Abstract, page iii

Synthesis of ZnO micro-flowers assisted by plant-mediated strategy and their photocatalytic application

有机污染物中特别是染料，对人类生活和环境的不利影响，已经受到了社会的广泛关注。在半导体存在的条件下，光催化降解已成为一种除去染料污物的有效手段。许多不同的半导体已经被应用于光催化降解的过程中，其中，ZnO由于其吸附能力强、无毒性、高催化效率、带隙宽、化学稳定性、激子结合能大和廉价等特点，已经引起了研究者极大的关注。而上述性质决定了ZnO具有良好的光催化性质。氧化锌的光催化性能与其尺寸、表面积和形貌有关，因此ZnO的微/纳米结构合成和形貌控制备受关注。与传统的化学和物理方法相比，利用植物法合成高度稳定的ZnO成本效益更高。 在本文中，我们采用芳樟叶浸出物合成氧化锌微花（ZnOMFs）。结果表明...The harmful effects of organic pollutants especially dyes have received significant concerns due to their impact on human lives and the environment. Photocatalytic degradation of these dye pollutants with the assistance of semiconductors has been well established as efficient means of removing these pollutants. Different semiconductors have been applied as photocatalyst for the degradation of thes...学位：工程硕士院系专业：化学化工学院_化学工程学号：2042013115452

The impact of information and communications technology infrastructure and complementary factors on intra-African Trade

Trade is one of the cornerstones of socio-economic development for Africa. Intra-continental trade stimulates productive capacity and competitiveness in nations through exposing domestic industries to competition. The purpose of this study was to investigate how information and communications technology (ICT) infrastructure impacts on intra-African trade, taking into account other relevant factors that also influence trade such as Institutional Quality and Educational Attainment. Archival data about Telecommunications Infrastructure (a key indicator of ICT infrastructure), Institutional Quality and Educational Attainment and Trade Flows (Export and Import) from 28 African countries were used as empirical evidence. The research employed structural equation modeling with partial least squares to analyze data. The empirical analysis shows that the Telecommunications Infrastructure has a major impact on intra-African trade. Interacting factors such as Institutional Quality and Educational Attainment also play a role in influencing intra-African trade.Web of Scienc

The impact of ICT Investments on human development: a regression splines analysis

Despite the worldwide growth in investments in information and communication technology (JCT), few studies have investigated the complex interactions between components of JCT investments and different dimensions of human development. The purpose of this study is to explore the conditional impacts of JCT investments (Hardware, Software, Internal Services Spending and Telecommunication) on two dimensions of Human Development (Standard of Living and Health) within three contexts (classified as High, Medium and Low income countries). To carry out the study, archival data concerning JCT investments and human development for 51 countries with the largest JCT markets were collected for the period 1994 to 2003. The study utilized a novel approach called regression splines to analyse the data. Results suggest, among other things, that: (1) the impact of investments in the different JCT components varies with context; (2) impacts are in many cases conditional and complex; and (3) the direction of impacts of JCT investment on Standard of Living may be different from the corresponding directions of impacts on Health. It is therefore necessary for policy makers or IS executives to do in-depth tradeoff analysis between the different components of JCT investment to determine appropriate allocations.Web of Scienc

Bolstering Ontario Land-Use Planners’ Adaptive Capacity for Resilient Climate Change Adaptation through Education

For many land-use planners across the province of Ontario, the region that my research examines, the issue has been raised that the adaptive capacity required to effectively and efficiently implement the climate change adaptation strategies and policies that they have been mandated to employ is lacking. Even though the tools and resources are there in abundance, the ability to implement such strategies and policies has been recognized to depend on land-use planners’ understanding of the climate issue at hand and the number of accessible human and technological resources . This is the central argument of this paper. As such, I use this research opportunity to explore how to bolster the adaptive capacity of Ontario’s land-use planner in these ways for a better response to the challenge that climate warming poses. I begin with a brief history of the climate change regime, along with a brief explanation of the climate science behind the warming. I then proceed to discuss the role land-use planning plays in contributing to climate warming, how it can redirect its efforts to reduce our carbon footprint, the challenges land-use planners face when tasked to implement adaptation strategies and how it can be solved through the bolstering of their adaptive capacity using the resilience framework. This is followed by a discussion on the work that the province of Ontario is doing through the BRACE Project to help bolster the adaptive capacity of the land-use planner. Through this research, my objective is to highlight the gap that currently exists in our adaptation efforts where those we depend on to implement these climate change adaptation strategies are lacking in their ability to carry out the work due to their lack of climate change adaptive capacity and how to bolster this through a resilience framework that presents us with a solution – education

The Physico-chemical Characteristics of Yeast Fermentation of two Mango (Mangifera indica Linn) Varieties.

Efficient methods of post harvest handling, preservation and value addition are critical for minimizing high losses in the post harvest chain of fruits.  The goal of this study was to address this problem by employing yeast fermentation technology to produce a more stable, value added product from mangoes. The design of the study involved determination of the fermentative capabilities of a selected yeast strain on the quality characteristics of mango wine obtained from two selected mango cultivars (improved and wild) with and without peels. The response variables monitored in the must and wine included total soluble solids (TSS), pH and total acidity (TA), microbial populations (aerophilic mesophiles, yeasts and Acetic acid Bacteria), and alcohol content. Volatile compounds development was also monitored using GC-FID procedures. Descriptive and hedonic sensory evaluations were carried out on the mango wine obtained from all treatments. The effects of mango peels in must fermentation characteristics compared well with those of must fermented without peels. However, the wines made using peeled mangoes were far more preferred by consumers than wine made using mangoes with peels. Five (5) major classes of aromatic volatiles were identified in all must and wine samples. Acetaldehyde and ethyl caprylate were present in all treatments, followed by isobutyraldehyde and 2, 3 Butanedione. Some volatiles identified appeared to be mango cultivar specific (Benzaldehyde and 1-methyl-2-pyrrolidone) while other volatiles appeared to be unique to the yeast strain employed (Ethyl butyrate). Keywords: mango, peels, yeast, must, wine, volatiles, alcoho

Fermentation Capacity of Yeasts Using Mango (Mangifera indica Linn.) as Substrate

The goal of this study was to address the problem of large post harvest losses of mangoes by employing yeast fermentation technology to produce a more stable, value-added product in this case fruit wine. The design of the study involved determination of the fermentative capabilities of four commercial yeast types on musts obtained from an improved (Keitt) mango cultivar that is popularly cultivated in some parts of Ghana for export. The characteristics of the mango musts that were monitored included total soluble solids (TSS), pH and total acidity (TA), microbial populations (aerophilic mesophiles, yeasts and Acetic acid Bacteria), alcohol content and colour over the course of the fermentations. Descriptive and hedonic sensory evaluation was carried out on the ferments obtained from all treatments. Results showed that two of the yeast types namely; Red Star Pasteur and Red Star Montrachet displayed superior fermentation characteristics and produced mango wines that were acceptable by both descriptive and affective sensory panels. Keywords: mango, yeast, fermentation, alcohol, wine, must, soluble solids, acidity

Phenotypic Characterization of AmpC beta-lactamase among Cefoxitin Resistant Escherichia coli and Klebsiella pneumoniae Isolates in Accra, Ghana

AmpC ?-lactamases hydrolyze penicillins, cephalosporins and cephamycins and resist inhibition by clavulanate, sulbactam, and tazobactam. Strains with AmpC genes are inherently resistant to multiple agents, making the selection of an effective antibiotic difficult. This present work sought to investigate the occurrence of AmpC beta-lactamases-producing phenotypes in E. coli and K. pneumoniae and their antimicrobial sensitivity profile. Four hundred K. pneumoniae and E. coli non-duplicate isolates were collected and their antibiotic sensitivity testing for cefoxitin and other 16 antibiotics were determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France).  The isolates resistant to cefoxitin were confirmed as AmpC beta-lactamases-producing phenotypes with disk synergy testing (DST) using cefotaxime or ceftazidime with or without boronic acid. An increase in zone diameter of ?5mm in the presence of boronic acid indicates the presence of AmpC beta-lactamases in the test organism. The results showed that of the 50 cefoxitin resistant isolates screened from 400 bacterial isolates, 5(10%) were AmpC beta-lactamase-producers with 60%, 60%, 60%, 80% and 100% multiply antibiotic resistance in gentamicin, ciprofloxacin, norfloxacin, trimethoprim/sulfamethoxazole and tetracycline respectively. Nitrofurantoin which indicated 100% susceptibility with MIC90 of 32µg/ml may be a therapeutic option especially for non-life-threatening urinary tract infection. Imipenem was the antibiotic of choice with 100% susceptibility rates (MIC90 of ?1µg/ml). Though the insignificant (p>0.05) levels of AmpC beta-lactamase phenotypes may not require routine detection in health facilities, there is the need to implement evolutionary antibiotic administration policies and pragmatic infection control measures in the hospitals.      Keywords: AmpC beta-lactamase, Cefoxitin, ?-lactams, E. coli, K. pneumonia

The Reliability of Using Vitek 2 Compact System to Detect Extended-Spectrum Beta-lactamase-producing Isolates in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta-lactamases that are capable of hydrolysing ?-lactams except carbapenems and cephamycins. The global increased prevalence of ESBL-producing bacteria creates an urgent need for laboratory diagnostic methods that will accurately and rapidly identify the presence of ESBL phenotypes in clinical isolates. The Vitek 2 System (bioMérieux, France) is a rapid automated microbiological system used for bacteria and yeast identification, antimicrobial susceptibility testing (AST), resistance mechanism detection and epidemiologic trending and reporting using its advanced expert system. This present work sought to determine the reliability of routinely using Vitek 2 System to accurately and rapidly detect ESBL-producing E. coli and K. pneumoniae in Accra. The ESBL phenotypes for 400 E. coli and K. pneumoniae isolates were determined using the Vitek 2 system and combined disc synergy method. The results were used to determine the sensitivity, specificity, negative predictive value and positive predictive value of the Vitek 2 ESBL test through comparative analysis with the combined disk synergy method which is the reference method recommended by CLSI. The findings of this work indicated that the sensitivity, specificity, positive predictive value and negative predictive value of Vitek 2 system was 98.5%, 98.9%, 99% and 98.5% respectively. Consequently, Vitek 2 system is a reliable semi-automated microbiology system which may be used for routine, accurate and rapid detection of ESBL strains in health facilities in Accra, Ghana. Keywords: Vitek 2 Compact System, Extended spectrum beta-lactamase, bioMérieux, E. coli and K.  pneumoni

The epidemiology of lymphatic filariasis in Ghana, explained by the possible existence of two strains of Wuchereria bancrofti

Introduction Lymphatic filariasis is a debilitating disease caused by the filarial worm Wuchereria bancrofti. It is earmarked for elimination by the year 2020 through the Global Program for the Elimination of LF (GPELF). In Ghana, mass treatment has been on-going since the year 2000. Earlier studies have revealed differing epidemiology of LF in the North and South of Ghana. This study was therefore aimed at understanding the possible impacts of W. bancrofti diversity on the epidemiology and control of LF in Ghana. Methods The Mitochondrial, Cytochrome C Oxidase I gene of W. bancrofti samples was sequenced and analyzed. The test sequences were grouped into infrapopulations, and pairwise differences (Π) and mutation rates (θ) were computed. The amount of variance within and among populations was also computed using the AMOVA. The evolutionary history was inferred using the Maximum Parsimony method. Results Seven samples from the South and 15 samples from the North were sequenced, and submitted to GenBank with accession numbers GQ479497- GQ479518. The results revealed higher mutation frequencies in the southern population, compared to the northern population. Haplotype analyses revealed a total of 11 haplotypes (Hap) in all the 22 DNA sequences, with high genetic variation and polymorphisms within the southern samples. Conclusion This study showed that there is considerable genetic variability within W. bancrofti populations in Ghana, differences that might explain the observed epidemiology of LF. Further studies are however required for an in-depth understanding of LF epidemiology and control