The ability of asphalt binders (bitumen) in road surfaces to self-heal after cracking is important to developing a robust transportation system that can tolerate heavy traffic and varying weather conditions. In order to develop improved binders, there is a need for noninvasive, in-situ, interface-specific methods of monitoring the kinetics, physics and chemistry of self-healing bitumen interfaces. Here the feasibility of using optical second-harmonic generation (SHG) by focused femtosecond laser pulses to monitor bitumen surfaces is demonstrated. SHG signals are observed in transmission through a sample composed of bitumen spin-coated onto a borosilicate microscope coverslip. The SHG signals are absent from uncoated coverslips, demonstrating that they originate from the bitumen layer. Further tests demonstrate that the bitumen-air surface makes the dominant contribution to the SHG signal. The SHG signal is observed to decay on a time scale comparable to typical self-healing times because of sample heating by the incident laser irradiation. Methods to control this effect by translating the sample during data acquisition are developed. Although the present results were obtained with a single incident wavelength (800 nm), they demonstrate the feasibility of probing bitumen interfaces spectroscopically with tunable light sources in order to monitor bond-specific chemical kinetics. / text

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

The role of farmers in technology generation and diffusion has long been identified as a key dimension in publicly funded international agricultural research. This thesis uses a case study approach to document actual research and diffusion practices andlheir outcomes, and from these it draws conclusions for research policy. The thesis compares the effects of new technology, the research processes that generated it, and the diffusion processes that promoted and disseminated it, in three countries. Particular attention is given to farmer participation and related issues deemed critical to effective research and diffusion. The technology in question is True Potato Seed, a radical alternative means for potato propagation to tuber seed, researched and promoted by the International Potato Centre in collaboration with national research institutes since 1978. The case study countries are India, Egypt, and Indonesia. Extensive quantitative and qualitative farmer surveys provide the first detailed assessment of TPS benefits, their distribntion, and likely TPS adoption. Secondary data, documentation, and in-depth interviews with key actors permit an analysis of the significant activities, decisions, and players that shaped TPS research and diffusion processes. The farmer survey evidence indicates that TPS outcomes are problematic in each country. It also reveals cases of inadequately justified TPS research and promotion largely due to a poor awareness by scientists and research managers of farmers' conditions. This thesis demonstrates that a powerful countervailing force to the pursuit of unproductive research lies in the early and effective involvement of farmers in the research process. This allows for critical weaknesses to come to light after experimentation by farmers under their own conditions of production. The inevitable geographical and institutional decentralisation that this entails, fosters a greater level of research responsiveness and an environment in which alternatives to formal extension, including farmer dissemination networks, may be stimulated and encouraged where appropriate. However, regardless of the rhetoric regarding farmer participatory approaches at an organisational level, the extent to which these are borne out in practice depends largely upon the philosophies of the key individuals who shape and direct research and promotion processes.

No description available.

Människan spenderar en stor del av sin tid på arbetet. Vad arbetet och arbetsplatsen innebär för människan har förändrats över tiden och varierar beroende på den individuella utgångspunkten. Vi ser en sammankoppling mellan identitet, sociala relationer, status och prestationskrav till arbetet. Arbetet är därmed ett viktigt element i den moderna människans livsbygge. Herzberg menar att det finns inre och yttre faktorer som ger arbetsmotivation och arbetstillfredsställelse, Maslow talar om liknande faktorer men uttrycker dem som mänskliga behov. Maslow menar att människans slutgiltiga behov att tillfredställa är ett självförverkligande. Om de övriga behoven/faktorerna går att tillgodose genom arbetet och arbetsplatsen – varför skulle då inte människan däri kunna söka även ett självförverkligande?Arbetet bär på värden utöver det värde som ligger i lönekuvertet. Det är just dessa värden vi i vår uppsats söker definiera. Vi menar att det är av stor vikt att företag uppmärksammar det som individer söker i arbetet, detta för att kunna vara en attraktiv arbetsgivare och konkurrera om den bästa arbetskraften. Till detta kommer det faktum att vi står i ett generationsskifte, 80-talisterna – Generation Y står att ta över efter 40-talisterna. Generation Y menas vara en individualistisk generation och de har en ny syn på sig själva, livet och samhället med andra krav på sin omgivning. Frågan är vad denna förändring innebär för arbetslivets olika parter.Syftet med denna uppsats är att analysera och skapa en bild av hur svenska företag går till väga för att bemöta de olika värden arbetstagare söker i arbetet och på arbetsplatsen. Vidare är syftet att beskriva hur företag bemöter Generation Y. För att besvara vårt syfte har vi genomfört en flerfallstudie i tre svenska aktiebolag med säte i Stockolm. På respektive företag har vi intervjuat ansvariga för personalarbete, även kallat human resources.

Surface properties of polymers and competition adsorption of toluene and heptane on silica were studied using IR-visible sum frequency generation (SFG) vibrational spectroscopy. SFG is intrinsically surface sensitive because the second-order optical process is forbidden in media with inversion symmetry, such as bulk polymers and liquids. This nonlinear optical technique provides surface vibrational spectra under ambient conditions without the need of an ultra-high vacuum environment. Polymer surface properties, including surface relaxation temperature of poly(methyl methacrylate) (PMMA) and surface electronic states of poly[2-methoxy, 5-ethyl (2’-hexyloxy) para phenylenevinylene] (MEH-PPV), were investigated. It was found that there are significant differences between the surface and bulk properties for these polymers. For PMMA, a new surface structure relaxation was identified at 67°C, which does not match any known structure relaxation temperatures for bulk PMMA and is 40°C below the bulk glass transition temperature. For MEH-PPV, SFG electronic spectra, which were obtained by scanning the frequencies of incident visible and JR beams, indicated that the electronic states at the polymer/solid and air/polymer interfaces are red-shifted with respect to that of the bulk. Finally, SFG was employed to study the competition adsorption of toluene and heptane on silica surfaces. Experimental data showed that heptane adsorbed favorably compared to toluene. Using a Langmuir adsorption isotherm, the changes of Gibbs free energy for the adsorption processes were calculated to be —12.1 ± 1.8 (kJ/mol) for toluene and —16.5 ± 2.3 (kJ/mol) for heptane.

Environmentally friendly renewable energy technologies such as wind and solar energy systems are among the fleet of new generating technologies driving the demand for distributed generation of electricity. Power Electronics has initiated the next tech¬nological revolution and enables the connection of distributed generation (DG) systems to the grid. The challenge is to achieve system functionality without extensive custom engineering, yet still have high system reliability and generation placement flexibility. Nowadays, it is a general trend to increase the electricity production using DG systems. If these systems are not properly controlled, their connection to the utility network can generate problems on the grid side. Therefore, considerations about power generation, safe running and grid synchronization must be done before connecting these systems to the utility network. This thesis introduces a new grid-synchronization, or more visibly a new “power signal processor” adaptive notch filtering (ANF) tool that can potentially stimulate much interest in the field and provide improvement solutions for grid-connected operation of DG systems. The processor is simple and offers high degree of immunity and insensitivity to power system disturbances, harmonics and other types of pollutions that exist in the grid signal. The processor is capable of decomposing three-phase quantities into symmetrical components, extracting harmonics, tracking the frequency variations, and providing means for voltage regulation and reactive power control. In addition, this simple and powerful synchronization tool will simplify the control issues currently challenging the integration of distributed energy technologies onto the electricity grid. All converter-interfaced equipments like FACTS (flexible ac transmission systems) and Custom Power Controllers will benefit from this technique. The theoretical analysis is presented, and simulation and experimental results confirm the validity of the analytical work. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2009-01-27 11:37:07.279

No description available.

No description available.

Loopless algorithms are an interesting challenge in the field of combinatorial generation. These algorithms must generate each combinatorial object from its predecessor in no more than a constant number of instructions, thus achieving theoretically minimal time complexity. This constraint rules out powerful programming techniques such as iteration and recursion, which makes loopless algorithms harder to develop and less intuitive than other algorithms. This thesis discusses a divide-and-conquer approach by which loopless algorithms can be developed more easily and intuitively: fusing loopless algorithms. If a combinatorial generation problem can be divided into subproblems, it may be possible to conquer it looplessly by fusing loopless algorithms for its subproblems. A key advantage of this approach is that is allows existing loopless algorithms to be reused. This approach is not novel, but it has not been generalised before. This thesis presents a general framework for fusing loopless algorithms, and discusses its implications. It then applies this approach to two combinatorial generation problems and presents two new loopless algorithms. The first new algorithm, MIXPAR, looplessly generates well-formed parenthesis strings comprising two types of parentheses. It is the first loopless algorithm for generating these objects. The second new algorithm, MULTPERM, generates multiset permutations in linear space using only arrays, a benchmark recently set by Korsh and LaFollette (2004). Algorithm MULTPERM is evaluated against Korsh and LaFollette's algorithm, and shown to be simpler and more efficient in both space and time.