| 2. |
- Folkesson, Anders, et al.
(författare)
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Real life testing of a hybrid PEM fuel cell bus
- 2003
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Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 118:1-2, s. 349-357
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Tidskriftsartikel (refereegranskat)abstract
- Fuel cells produce low quantities of local emissions, if any, and are therefore one of the most promising alternatives to internal combustion engines as the main power source in future vehicles. It is likely that urban buses will be among the first commercial applications for fuel cells in vehicles. This is due to the fact that urban buses are highly visible for the public, they contribute significantly to air pollution in urban areas, they have small limitations in weight and volume and fuelling is handled via a centralised infrastructure. Results and experiences from real life measurements of energy flows in a Scania Hybrid PEM Fuel Cell Concept Bus are presented in this paper. The tests consist of measurements during several standard duty cycles. The efficiency of the fuel cell system and of the complete vehicle are presented and discussed. The net efficiency of the fuel cell system was approximately 40% and the fuel consumption of the concept bus is between 42 and 48% lower compared to a standard Scania bus. Energy recovery by regenerative braking saves up 28% energy. Bus subsystems such as the pneumatic system for door opening, suspension and brakes, the hydraulic power steering, the 24 V grid, the water pump and the cooling fans consume approximately 7% of the energy in the fuel input or 17% of the net power output from the fuel cell system. The bus was built by a number of companies in a project partly financed by the European Commission's Joule programme. The comprehensive testing is partly financed by the Swedish programme "Den Grona Bilen" (The Green Car). A 50 kW(el) fuel cell system is the power source and a high voltage battery pack works as an energy buffer and power booster. The fuel, compressed hydrogen, is stored in two high-pressure stainless steel vessels mounted on the roof of the bus. The bus has a series hybrid electric driveline with wheel hub motors with a maximum power of 100 kW. Hybrid Fuel Cell Buses have a big potential, but there are still many issues to consider prior to full-scale commercialisation of the technology. These are related to durability, lifetime, costs, vehicle and system optimisation and subsystem design. A very important factor is to implement an automotive design policy in the design and construction of all components, both in the propulsion system as well as in the subsystems.
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| 3. |
- Folkesson, Anders
(författare)
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On extrinsic and intrinsic organizational themes in gram negative bacteria and their role in evolution and virulence of the bacterial genus Salmonella spp
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gram-negative bacteria are composed of intrinsic organizational themes such as outer and inner membrane, cell wall, and replicons. Themes that not only determine the body-plan and physical properties but also set the boundaries for choice of life style and evolution of the organisms. Bacteria also harbor extrinsic organizational themes that are represented by horizontally transferred genetic information such as plasmids, bacteriophages and pathogenicity island that augments the unique properties that define the separate organizational units of the individual bacteria. Our studies have focused on two organizational themes and studied how they influence pathogenicity, virulence and evolution of species specificity of the Gram-negative rod Salmonella enterica serovar Typhimurium. We have determined the genetic structure and organization of the Salmonella enterica centisome 7 genomic island (SCI) located at the aspV loci in S.enterica subspecies I strains. The island encodes 37 putative proteins, including the saf fimbrial opreron and the sinR transcriptional regulator. Other open reading frames (designated sciA to Z) in the island encode putative proteins with homologies to virulence-associated proteins in a number of Gram-negative bacteria that have the ability to interact and manipulate eukaryotic cells. Deletion of the entire SCI region affects the ability of the organisms to enter eukaryotic cells. We have investigated the immunogenicity in mice of Saf fimbrial components, and studied the protection induced by oral challenge with live Salmonella enterica. These studies show that a systemic and mucosal immune response is induced in immunized mice. Subcutaneously immunized mice showed significantly fewer bacteria in spleens after challenge than non-immunized. During bacterial growth the cell wall is constantly remodelled and the integrity of the murein is dependent on a balance between synthesizing and degrading activities and the turnover is coupled to a highly efficient recycling pathway. The recycling pathway is coupled to induction of antibiotic resistance in many Gram-negative bacteria. Interference with the pathway does not affect cell growth in vitro and mutants in the membrane transport protein AmpG and the cytoplasmic muropeptide specific amidase AmpD are as viable as wild type cells. We constructed mutations in Salmonella enterica serovar Typhimurium that interferes with the recycling pathway in this bacterium. A Salmonella ampD knock out mutant has lower in vivo fitness in a competition experiment in Balb/c mice than the wild type. The ampD mutant is also less able to enter mouse macrophages. Furthermore, these studies show that the ampD mutant induces nitric oxide to a higher degree than the wild-type. In conclusion, we have investigated, by using similar methodologies, how different Gram-negative organizational themes affect the pathogenicity and evolution in the important human pathogen Salmonella.
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