Adaptive Coding and Modulation for Mobile Wireless Access Via High Altitude Platforms

In this paper we are concerned with broadband wireless access via high altitude platform system, providing the Internet access and broadband multimedia services to passengers equipped with WLAN terminals connecting through a collective terminal mounted on the train. The main challenge in such scenario is the development of efficient and reliable radio interface for the broadband communication link in the mobile wireless access segment. We are focusing on performance analysis of the adaptive coding and modulation scheme in the communication link between a high altitude platform and a collective terminal on-board moving train. In order to increase the reliability of the communication system in a fading environment we also exploit space and platform diversity. The proposed approach significantly increases the throughput of the wireless access system, while bit error rate remains below the target value regardless of the considered propagation environment.Tomaz Javornik received his B.Sc., M.Sc. and Ph.D. degrees in electrical engineering from the University of Ljubljana, Slovenia, in 1987, 1990 and 1993, respectively. He joined the Jozef Stefan Institute in 1987, where he currently works as a researcher in the Department of Digital Communications and Networks. He is involved in the study of digital radio-relay systems, modulation techniques, coding, adaptive signal processing and digital mobile communication systems.Mihael Mohorcic received B.Sc., M.Sc. and Ph.D. degrees in Electrical Engineering from the University of Ljubljana, Slovenia, in 1994, 1998 and 2002, respectively, and M.Phil. degree in Electrical Engineering from University of Bradford, UK, in 1998. He is a research fellow in the Department of Digital Communications and Networks at the Jozef Stefan Institute. In 1996/1997 he spent 12 months as a Visiting Scientist at University of Bradford, Bradford, UK. His research interests include development and performance evaluation of network protocols and architectures for mobile and wireless communication systems, and resource management in satellite and high altitude platforms networks with the emphasis on routing algorithms and traffic engineering. He is a member of IEEE.Ales Svigelj received his B.Sc., M.Sc. and Ph.D. degrees in Electrical Engineering from the University of Ljubljana, Ljubljana, Slovenia, in 1997, 2000 and 2003 respectively. He is a research associate in the Department of Digital Communications and Networks at the Jozef Stefan Institute. In 2000/2001 he spent one year as a visiting researcher at Leeds Metropolitan University in Leeds, UK. He has participated in several national and international projects. His research interests concern the development of telecommunications systems, network protocols and architectures for satellite, high altitude platforms and terrestrial mobile communication systems. In 2004 he was awarded with The Jozef Stefan Golden Emblem Prize for outstanding contributions made to science in Doctoral theses in the field of natural sciences in Slovenia.Igor Ozimek received his B.Sc., M.Sc. and Ph.D. degrees in electrical engineering from the University of Ljubljana, Slovenia in 1980, 1988 and 1993, respectively. Since 1980 he has been with the Jozef Stefan Institute, Ljubljana, where he works as a researcher. His current interests include digital communications,DSP processing and computer networks.Gorazd Kandus received B.Sc., M.Sc. and Ph.D. degrees in Electrical Engineering from the University of Ljubljana, Ljubljana, Slovenia, in 1971, 1974 and 1991, respectively. He is currently the head of the Department of Digital Communications and Networks at the Jozef Stefan Institute and a Professor at the Faculty of Electrical Engineering, Computer Science and Information Technology, University of Maribor. He spent one year at Worchester Polytechnic Institute, Worchester, MA, as a Fulbright Fellow and 5 months as a Visiting Scientist at the University of Karlsruhe, Germany. His main research interests include design and simulation of mobile and wireless communication systems and development of new telecommunication services. He is a member of IEEE and Upsilon Pi Epsilon.     

Stylopsal: The First Identified Female-produced Sex Pheromone of Strepsiptera

A female-produced sex pheromone of Stylops muelleri was identified as an unusually branched saturated aldehyde (9R)-3,5-syn-3,5,9-trimethyldodecanal. We named it stylopsal. Its structure was established by using mass spectrometry, infrared spectroscopy, and organic synthesis of candidate compounds. The synthetic standard of (9R)-3,5-syn-3,5,9-trimethyldodecanal gave identical chromatographic and mass spectrometric data as the natural pheromone and also was active in electroantennographic and behavioral assays. The female fat body lipids contained the corresponding fatty acid, indicating a possible link between lipid metabolism and the pheromone biosynthesis.     

Providing with vitamins of different population groups in Sverdlovsk]

The investigation on providing with vitamins of varying population groups: preschool children, schoolchildren, students of trade schools and higher schools, workers and employees was conducted in Sverdlovsk. Low levels of vitamin C were detected in the blood of 40-92%, folic acid--in 10-76%, vitamin A--in 4-28%, carotene--in 8-60%, tocopherol--in 4-50% of the examinees. Vitamin B1 deficiency was noted in 36-68%, vitamin B2--in 17-71%. The highest deficiency of ascorbic acid was recorded in workers and students of trade schools and higher schools, of folic acid--in workers and adolescents of 15-18 years, of vitamins B1, E, A and carotene--in children and adolescents, vitamin B1--in employees. The mass character of vitamin deficiencies and their negative effects on the health of the population have necessitated broad-scale prophylactic measures: production of vitamin-enriched foods, regular use of multivitamins.     

Grain boundary plane reorientation: model experiments on bi- and tricrystals

Experiments on growth and annealing of bi- and tricrystals of an Fe–6at.%Si model alloy are described in this study that investigates the behavior of (a) a free grain boundary in a bicrystal and (b) constrained grain boundaries at the triple junction of a tricrystal. The results clearly show the tendency of the grain boundaries to incline to special orientations dominated mainly by the {011} and {112} planes, thus supporting the idea that the grain boundaries may reorient their planes during annealing and change their character from general to special.     

Characterization of the carbides and the martensite phase in powder-metallurgy high-speed steel

A microstructural characterization of the powder-metallurgy high-speed-steel S390 Microclean was performed based on an elemental distribution of the carbide phase as well as crystallographic analyses. The results showed that there were two types of carbides present: vanadium-rich carbides, which were not chemically homogeneous and exhibited a tungsten-enriched or tungsten-depleted central area; and chemically homogeneous tungsten-rich M₆C-type carbides. Despite the possibility of chemical inhomogenities, the crystallographic orientation of each of the carbides was shown to be uniform. Using electron backscatter diffraction the vanadium-rich carbides were determined to be either cubic VC or hexagonal V₆C₅, while the tungsten-rich carbides were M₆C. The electron backscatter diffraction results were also verified using X-ray diffraction. Several electron backscatter diffraction pattern maps were acquired in order to define the fraction of each carbide phase as well as the amount of martensite phase. The fraction of martensite was estimated using band-contrast images, while the fraction of carbides was calculated using the crystallographic data.     

Kinetic Study of Nickel Oxide Reduction by Methane

The reduction of the nickel oxide, NiO, by methane was investigated in this work. The thermogravimetric technique was used for the determination of kinetic parameters for the reaction. The reaction was carried out in the temperature range of 600–725 °C, at atmospheric pressure with porous pellets prepared from nickel oxide powder with a mean particle size of 0.026 μm. The conversion‐time data have been interpreted by using the grain model. Complete conversion can be achieved in 11 min at 725 °C, which is shorter than the time required by carbon, i.e., ca. 120 min at 1000 °C. This faster reduction in comparison with carbonthermal reduction is attributed to the high carbon activity in methane. For the first order reaction with respect to methane concentration, the activation energy is found to be 63.9 kcal/g mol.     

Modeling accidents for prioritizing prevention

The Workgroup Occupational Risk Model (WORM) project in the Netherlands is developing a comprehensive set of scenarios to cover the full range of occupational accidents. The objective is to support companies in their risk analysis and prioritization of prevention. This paper describes how the modeling has developed through projects in the chemical industry, to this one in general industry and how this is planned to develop further in the future to model risk prevention in air transport. The core modeling technique is based on the bowtie, with addition of more explicit modeling of the barriers needed for risk control, the tasks needed to ensure provision, use, monitoring and maintenance of the barriers, and the management resources and tasks required to ensure that these barrier life cycle tasks are carried out effectively. The modeling is moving from a static notion of barriers which can fail, to seeing risk control dynamically as (fallible) means for staying within a safe envelope. The paper shows how concepts develop slowly over a series of projects as a core team works continuously together. It concludes with some results of the WORM project and some indications of how the modeling is raising fundamental questions about the conceptualization of system safety, which need future resolution.     

Introduction of hydrogen vehicles in Kathmandu Valley: A clean and sustainable way of transportation

Air quality of Kathmandu Valley, the capital of Nepal, was one of the worse among the big cites in the world. The air quality situation was becoming more critical due to the substantial increase in the conventional fueled vehicles in the valley each year. The bowl-like topography and generally low speeds of wind during the dry seasons create poor dispersion conditions, augmenting the air pollution problem further. The pollution is expected to quadruple by 2020 from the 2005 level in as business as usual scenario.The main source of the pollution in the valley is motor vehicle emissions. The paper highlights the different level of air pollution and emission reductions by introducing hydrogen fuel vehicles in Kathmandu Valley. The entire fleet of vehicles in the valley can be fueled by hydrogen produced from the national hydroelectricity of Nepal using only less than 50% of its surplus energy. This will reduce about 700,000 tonnes of carbon emission in the valley in 2020. In addition, production of hydrogen using the surplus hydroelectricity of Nepal will improve load factor of the grid, and save a substantial amount of hard currency used to import the petroleum fuel in the country. As Nepal is one of the most hydropower potential countries in the world, with a 80,000 MW potential capacity, hydrogen production is renewable, sustainable and pollution free.     

New composite films based on MoO<Subscript>3−<Emphasis Type="Italic">x</Emphasis></Subscript> nanowires aligned in a liquid single crystal elastomer matrix

Abstract  

In this study, we report the preparation, structure characterization, and application of new MoO_3−x nanowires, promising candidates for lithium intercalation, hydrogen sensing, and smart windows due to their photochromic property. These nanowires are a mixture of MoO₃ and conductive Mo₅O₁₄ phase and have been used to prepare composite films based on liquid single crystal elastomers (LSCE). The structure, morphology, and thermomechanic behavior of these films are discussed. In particular, we show that the particular combination of molybdenum-based nanowires and LSCEs allows for doping of liquid single crystal elastomers, preserving the pristine mechanical and optical properties of the host matrix.     

Underestimation of language issues in frequently used accident investigation methods: a new taxonomy problem found in Dutch accident data

A wide variety of methods exist in the field of accident investigation. The challenge to find the cause for each and every accident has perpetuated a complicated and fundamental debate. In spite of the different paradigms, the many branch specific investigation methods, decades of accumulated and documented accident investigation experience, the diversity in taxonomy of causal factors, and an increasing depth of general systematic analysis tools, there are still causal factors missing out. A recent study identifies language issues as an underestimated danger. Dutch Labour Inspectorate records identify procedures and communication as an important causal factor area for major accidents. Accident investigation method taxonomies that are frequently used in The Netherlands, were investigated on the content related to language issues. Language issues are found to be either present less than proportional with observed accident rates or not present at all in frequently applied accident investigation classification systems. Hence a new taxonomy problem was found in Dutch accident data. Language issues need more attention in accident investigation methods.