No / Sierra Leone came to world attention in the 1990s when a catastrophic civil war linked to the diamond trade was reported globally. This fleeting and particular interest, however, obscured two crucial processes in this small West African state. On the one hand, while the civil war was momentous and brutal, affecting all Sierra Leoneans, it was also just one element in the long and faltering attempt to build a nation and state, given the country’s immensely problematic pre-colonial and British colonial legacies. On the other, the aftermath of the war precipitated a huge international effort to construct a ‘liberal peace’, with mixed results, and interrupted by the devastating Ebola pandemic. This made Sierra Leone a laboratory for both post-conflict and health crisis interventions. Sierra Leone examines over 230 years of its history and sixty years of independence, placing state–society relations at the centre of an original and revealing investigation of those who have tried to rule or change Sierra Leone and its inhabitants, and the responses engendered. It interweaves the historical narrative with sketches of politicians, anecdotes, the landscape and environment and key turning-points, alongside theoretical and other comparisons with the rest of Africa. It is a new contribution to the debate for those who already know Sierra Leone and a solid point of entry for those who wish to.

Diverging diamond interchanges (DDI) have been proved to outperform other types of diamond interchanges in terms of safety, cost-effectiveness and efficiency, but few research efforts have been done to conduct the analytic calculation of delay, with which optimization of timing plans can be acquired more efficiently. This paper develops the control strategies based on the introduction of overlap and offset analysis, which provide a uniform representation of sequences for DDI signal control. Based on the developed timing plan then the delay calculation equations are put forward and results show the calculation fit simulation very well with R-Square to be 0.9949 for total delay of those two directions. Ecodriving aims to achieve the best fuel efficiency by guiding vehicles travel at planned and optimized speed trajectories. This study opens the door for safety concerns for following normal driving vehicles (FNVs) when following ecodriving vehicles (EVs). To examine the safety issues under different circumstance. Three road elements: initial signal status, ambient vehicles and speed limit along with three EV elements: SpeedTolimit, DistanceToStoplight and acceleration were chosen as potential influential elements, and time to collision (TTC) was selected as the dependent variable. Therefore, six testing scenarios and six baseline were designed and implemented using a drive safety DNS-250 simulator. 29 drivers participated in the driving simulator study. The results show the aforementioned road elements and EV elements have significant influence on TTC of FNV in different testing parts. Therefore, these finding can be used as guidance for future ecodriving algorithm design and implementation. / Master of Science

Efficient generation of 1.5 um wavelength light has applications for ranging and remote sensing while being in the "eye safe" region of the optical spectrum. Diamond Raman lasers are excellent candidates for light sources at these wavelengths due to the excellent optical and mechanical properties of diamond as a laser material. This thesis describes the design and build of a MOPA fiber laser system in the CW regime as a pump for a Diamond Raman laser along with a design for operating it in the pulsed regime as well. The CW fiber laser was tested up to 200 W average power and characterized for each stage of the MOPA architecture. The third and final amplifier stage uses an extra large mode area(XLMA) fiber for decreasing irradiance of the signal with in the fiber and thus mitigating the unwanted nonlinear effects at the output when the system will be pulsed. Engineering designs will be presented for fiberized components that reduce the amount of passive fiber in the system overall. The process of putting end caps on the fiber facets will also be described. The multimode nature of the XLMA fiber required mode mixing elements to obtain a more uniform flat top beam profile. Characterization of the mode mixing fiber will be presented along with the output profile improvement.

Thesis (MBA)--University of Stellenbosch, 2010. / Since gaining independence in 1990, Namibia has enjoyed a fairly stable economic performance, but its heavy reliance on its natural resources, especially its mineral resources, is at times worrisome. Historically, the country has depended primarily on diamond exports as a major source of foreign exchange earnings and state revenue. The contribution of diamond mining to government revenue has over the years declined from a high of N$1493 million in 2002 to the levels of N$821 million in 2007. Similarly, the contribution of diamond mining to the Gross Domestic Product has decline marginally from N$4.59 billion (16.9 percent) in 2006 to N$3.56 billion (13.1 percent) in 2007 respectively. It is evident that there has been a steady, but progressive decline in the proportional contribution of diamonds to the national income in relation to the other sectors of the economy. This decline can however not be directly attributed to a corresponding decline in the diamond production output, but perhaps due to a decline in diamond demand and lower prices. Based on the fact that diamond production and expansion thereof to offshore operations in particular will continue for years to come and still make significant contribution to the Namibia economy, this study attempts to formulate value addition strategies that could lead to the optimisation of the Namibia diamond economy potential, especially local benefication, as well as increased international competitiveness within the established world diamond markets. To this end, it evaluates the intricate supply and demand patterns in the world diamond market to understand how Namibia could position itself. The study found that there is a clear case for local diamond benefication as an economic imperative and that it is a feasible proposition. However, it must be approached cautiously and within a clearly defined and structured framework. It is recommended that Namibia should pursue the benefication of her unique gem quality diamonds in conjunction with external manufacturing experts and marketers in order to secure a bigger stake in the global diamond pipeline. To this end the government needs to formulate clear incentive strategies and packages for investors and also open the playing field for local manufacturers, without compromising existing relations and revenue streams. Furthermore, it is suggested that Namibia strive to maintain an amicable balance between rough exports and local benefication, whilst expanding the regulatory and enabling environment. Other proposals that will support local benefication and competitiveness of the Namibian diamond economy are diamond branding and marketing through already existing diamond marketing pioneers such as DTC International. Finally, Namibia needs to embark upon strategies to urgently increase its skills base and improve the productivity of its labour force in order to achieve the vision of a flourishing diamond benefication sector.

An extremely facile and novel method called spontaneous deposition, to deposit noble metal nanoparticles on a most stable form of carbon (C) i.e. diamond is presented. Nanometer sized particles of such metals as platinum (Pt), palladium (Pd), gold (Au), copper (Cu) and silver (Ag) could be deposited on boron-doped (B-doped) polycrystalline diamond films grown on silicon (Si) substrates, by simply immersing the diamond/Si sample in hydrofluoric acid (HF) solution containing ions of the corresponding metal. The electrons for the reduction of metal ions came from the Si back substrate. The diamond/Si interfacial ohmic contact was of paramount importance to the observation of the spontaneous deposition process. The metal/diamond (M/C) surfaces were investigated using Raman spectroscopy, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffractometry (XRD). The morphology (i.e. size and distribution) of metal nanoparticles deposits could be controlled by adjusting the metal ion concentration, HF concentration and deposition time. XRD data indicate the presence of textured and strained crystal lattices of Pd for different Pd/C morphologies, which seem to influence the electrocatalytic oxidation of formaldehyde (HCHO). The sensitivity of electrocatalytic reactions to surface crystal structure implies that M/C could be fabricated for specific electrocatalytic applications. The research also presents electroplating of Cu on ruthenium (Ru), which a priori is a promising barrier material for Cu interconnects in the sub 0.13 μm generation integrated circuits (ICs). Cu plates on Ru with over 90% efficiency. The electrochemical nucleation and growth studies using the potentiostatic current transient method showed a predominantly progressive nucleation of Cu on Ru. This was also supported by SEM imaging, which showed that continuous thin films of Cu (ca. 400 Å) with excellent conformity could be plated over Ru without dendrite formation. Scotch tape peel tests and SEM on Cu/Ru samples both at room temperature (RT) and after annealing at 800 oC, showed no sign of delamination of the Cu film from Ru indicating strong adhesion. XRD patterns from Cu/Ru samples at RT through 800 oC indicated Cu in its characteristic face centered cubic (fcc) form with (111) phase dominating. Most importantly no new XRD peak emerged, even after annealing to 800 oC showing Cu and Ru did not interact much. The excellent adhesion and lack of metallurgical interactions between Cu and Ru underscored the potential application of Ru as a new Cu diffusion barrier in the next generation ICs.

Chemical vapor deposition (CVD) has been the main method for synthesizing diamond thin films on hetero substrate materials since 1980s. It has been well acknowledged that both nucleation and growth of diamond on non-diamond surfaces without pre-treatment are very difficult and slow. Furthermore, the weak adhesion between the diamond thin films and substrates has been a major problem for widespread application of diamond thin films. Up to now, Si has been the most frequently used substrate for the study of diamond thin films and various methods, including bias and diamond powder scratching, have been applied to enhance diamond nucleation density. In the present study, nucleation and growth of diamond thin films on Ti3SiC2, a newly developed ceramic-metallic material, using Microwave Plasma Enhanced (MPE) and Hot-Filament (HF) CVD reactors were carried out. In addition, synchrotron-based Near Edge Extended X-Ray Absorption Fine Structure Spectroscopy (NEXAFS) was used to identify the electronic and chemical structures of various NCD films. The results from MPECVD showed that a much higher diamond nucleation density and a much higher film growth rate can be obtained on Ti3SiC2 compared with on Si. Consequently, nanocrystalline diamond (NCD) thin films were feasibly synthesized on Ti3SiC2 under the typical conditions for microcrystalline diamond film synthesis. Furthermore, the diamond films on Ti3SiC2 exhibited better adhesion than on Si. The early stage growth of diamond thin films on Ti3SiC2 by HFCVD indicated that a nanowhisker-like diamond-graphite composite layer, different from diamond nucleation on Si, initially formed on the surface of Ti3SiC2, which resulted in high diamond nucleation density. These results indicate that Ti3SiC2 has great potentials to be used both as substrates and interlayers on metals for diamond thin film deposition and application. This research may greatly expand the tribological application of both Ti3SiC2 and diamond thin films. The results demonstrated that NEXAFS is a reliable and powerful tool to identify NCD films.

Chemical vapor deposition (CVD) has been the main method for synthesizing diamond thin films on hetero substrate materials since 1980s. It has been well acknowledged that both nucleation and growth of diamond on non-diamond surfaces without pre-treatment are very difficult and slow. Furthermore, the weak adhesion between the diamond thin films and substrates has been a major problem for widespread application of diamond thin films. Up to now, Si has been the most frequently used substrate for the study of diamond thin films and various methods, including bias and diamond powder scratching, have been applied to enhance diamond nucleation density. In the present study, nucleation and growth of diamond thin films on Ti3SiC2, a newly developed ceramic-metallic material, using Microwave Plasma Enhanced (MPE) and Hot-Filament (HF) CVD reactors were carried out. In addition, synchrotron-based Near Edge Extended X-Ray Absorption Fine Structure Spectroscopy (NEXAFS) was used to identify the electronic and chemical structures of various NCD films. The results from MPECVD showed that a much higher diamond nucleation density and a much higher film growth rate can be obtained on Ti3SiC2 compared with on Si. Consequently, nanocrystalline diamond (NCD) thin films were feasibly synthesized on Ti3SiC2 under the typical conditions for microcrystalline diamond film synthesis. Furthermore, the diamond films on Ti3SiC2 exhibited better adhesion than on Si. The early stage growth of diamond thin films on Ti3SiC2 by HFCVD indicated that a nanowhisker-like diamond-graphite composite layer, different from diamond nucleation on Si, initially formed on the surface of Ti3SiC2, which resulted in high diamond nucleation density. These results indicate that Ti3SiC2 has great potentials to be used both as substrates and interlayers on metals for diamond thin film deposition and application. This research may greatly expand the tribological application of both Ti3SiC2 and diamond thin films. The results demonstrated that NEXAFS is a reliable and powerful tool to identify NCD films.

Polycarbynes ( poly(hydridocarbyne), poly(methylcarbyne) and poly(phenylcarbyne) ) are a class of network polymers which are primarily composed of tetrahedrally hybridizated carbon atoms which have hydrogen, methyl or phenyl pendant group linked via three carbon-carbon single bonds to form a three dimensional network of fixed rings. This backbone oers unusual properties on the polymer including thermal decomposition to form diamond and diamondlike carbon. In this thesis, polycarbynes were synthesized by electrolytical reduction of trihaloorganocompounds, namely chloroform, hexachloroethane, 1,1,1-trichloroethane and 1,1,1-trichlorotoluene. Poly(hydridocarbyne) was synthesized using chloroform and hexachloroethane. Poly(methylcarbyne) was synthesized from 1,1,1-trichloroethane. Poly(phenylcarbyne) was synthesized from 1,1,1-trichlorotoluene. Polycarbynes were characterized by UV/Vis spectroscopy, 1H and 13C NMR spectroscopy, FTIR and GPC. All results are found to be consistent with literature / and thus a single step cheap, safe and easy method was introduced to scientists and manufacturers in diamond science. The resulting polymers were heated upon 1000oC under nitrogen atmosphere for 24 hours yielding in the formation of diamond and diamond-like carbon. Results indicated that both diamond films and powders were successfully produced from polycarbynes. Diamonds formed from the polymers were characterized via optical microscope, SEM, X-ray and Raman spectroscopy. All results shown in thesis are completely consistent with studies previously done for polycarbynes and diamond.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 140-152).

Thesis (MPhil)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.