3,039 research outputs found

    Execution Time Analysis for Industrial Control Applications

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    Estimating the execution time of software components is often mandatory when evaluating the non-functional properties of software-intensive systems. This particularly holds for real-time embedded systems, e.g., in the context of industrial automation. In practice it is however very hard to obtain reliable execution time estimates which are accurate, but not overly pessimistic with respect to the typical behavior of the software. This article proposes two new concepts to ease the use of execution time analysis for industrial control applications: (1) a method based on recurring occurrences of code sequences for automatically creating a timing model of a given processor and (2) an interactive way to integrate execution time analysis into the development environment, thus making timing analysis results easily accessible for software developers. The proposed methods are validated by an industrial case study, which shows that a significant amount of code reuse is present in a set of representative industrial control applications.Comment: In Proceedings FESCA 2014, arXiv:1404.043

    Allopolyploids of the Genus Elymus (Triticeae, Poaceae): a Phylogenetic Perspective

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    The wheat tribe, Triticeae, includes many genomically distinct polyploid taxa. Elymus is an entirely allopolyploid genus, with all species containing the St genome of Pseudoroegneria. The St genome may be combined with one or more distinct genomes representing multiple, diverse diploid donors from throughout the tribe. This study includes a simultaneous phylogenetic analysis of new and previously published data from several distinct Elymus groups, including North American and Eurasian StStHH tetraploids, in which the H genome is derived from Hordeum, Eurasian StStYY tetraploids, in which the Y genome is derived from an unknown donor, and a putative StStStStHH hexaploid. Elymus species were analyzed with a broad sample of diploid genera from within the tribe using a combination of molecular data from the chloroplast and the nuclear genomes. The data confirm the genomic constitution of the StStHH and StStYY tetraploids, but do not provide additional information on the identity of the Y-genome donor. The genomic diversity in the hexaploid is greater than expected, inconsistent with the hypothesis of an StStStStHH genome complement

    Substituted bisphosphanylamines as ligands in gold(I) chemistry – synthesis and structures

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    Dimethyl 5-aminoisophthalate, which is a building block of amino-substituted tetralactam macrocycles, was used as ligand in gold(I) chemistry to form model complexes for macrocyclic gold compounds. Reaction of dimethyl 5-aminoisophthalate with chlorodiphenylphosphine gave the diphosphine compound dimethyl 5-[N,N-bis(diphenylphosphanyl)amino]isophthalate (dmbpaip). This compound can further be reacted with [AuCl(tht)] (tht = tetrahydrothiophene) to give the dinuclear complex [Au(2),Cl(2)(dmbpaip)]. In contrast, treatment of dinbpaip with [Au(tht)(2)]ClO(4) resulted in the ionic compound [Au(2)(dmbpaip)(2)](ClO(4))(2) in which the cation forms an eight-membered Au(2)P(4)N(2) heterocycle. In both gold(I) compounds Au center dot center dot center dot Au interactions are observed. All new compounds were characterized by single-crystal X-ray diffraction

    Circuit architecture explains functional similarity of bacterial heat shock responses

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    Heat shock response is a stress response to temperature changes and a consecutive increase in amounts of unfolded proteins. To restore homeostasis, cells upregulate chaperones facilitating protein folding by means of transcription factors (TF). We here investigate two heat shock systems: one characteristic to gram negative bacteria, mediated by transcriptional activator sigma32 in E. coli, and another characteristic to gram positive bacteria, mediated by transcriptional repressor HrcA in L. lactis. We construct simple mathematical model of the two systems focusing on the negative feedbacks, where free chaperons suppress sigma32 activation in the former, while they activate HrcA repression in the latter. We demonstrate that both systems, in spite of the difference at the TF regulation level, are capable of showing very similar heat shock dynamics. We find that differences in regulation impose distinct constrains on chaperone-TF binding affinities: the binding constant of free sigma32 to chaperon DnaK, known to be in 100 nM range, set the lower limit of amount of free chaperon that the system can sense the change at the heat shock, while the binding affinity of HrcA to chaperon GroE set the upper limit and have to be rather large extending into the micromolar range.Comment: 17 pages, 5 figure

    Absolute identification by relative judgment

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    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative relative judgment model (RJM) in which the elemental perceptual units are representations of the differences between current and previous stimuli. These differences are used, together with the previous feedback, to respond. Without using long-term representations of absolute magnitudes, the RJM accounts for (a) information transmission limits, (b) bowed serial position effects, and (c) sequential effects, where responses are biased toward immediately preceding stimuli but away from more distant stimuli (assimilation and contrast)

    UK Coal resource for new exploitation technologies. Final report

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    This focus of this report are the UK coal resources available for exploitation by the new technologies of Underground Coal Gasification, Coalbed Methane production and Carbon Dioxide Sequestration. It also briefly considers the potential for further underground and opencast mining and the extraction of methane from working and closed mines. The potential for mining was mainly considered because it has a bearing on the scope for the new exploitation technologies rather than to identify resources or potential mine development areas. The report covers the UK landward area and nearshore areas, although information on the extent of underground mining was not available for the nearshore areas. This work was carried out by the British Geological Survey, with the assistance of Wardell Armstrong and Imperial College, London. It represents a summary of the results of the Study of the UK Coal Resource for New Exploitation Technologies Project, carried out for the DTI Cleaner Coal Technology Programme (Contract No. C/01/00301/00/00) under the management of Future Energy Solutions (Agreement No. C/01/00301/00/00). Coalbed methane production can be subdivided into three categories: Methane drained from working mines, known as Coal Mine Methane (CMM), has been exploited in the UK since at least the 1950s. Currently all working mines except Daw Mill and Ellington drain methane. It is used to generate electricity at Harworth, Tower and Thoresby collieries and in boilers at Welbeck, Kellingley and Ricall/Whitemoor collieries. There is potential to increase the exploitation of CMM in the UK but this is mainly a question of economics. There is also an environmental case for further utilisation, as methane is an important greenhouse gas, 23 times more powerful than carbon dioxide on a mass basis. Methane drained from abandoned mines, known as Abandoned Mine Methane (AMM), is a methane-rich gas that is obtained from abandoned mines by applying suction to the workings. The fuel gas component consists primarily of methane desorbed from seams surrounding the mined seam(s). These unmined seams have been de-stressed and fractured by the collapse of overlying and underlying strata into the void left by the extracted seam(s). Currently AMM is being exploited at sites in North Staffordshire (Silverdale Colliery), the East Midlands (Bentinck, Shirebrook and Markham collieries) and Yorkshire (Hickleton, Monk Bretton and Wheldale collieries). The methane-rich gas is used for electricity generation or supplied to local industry for use in boilers and kilns. Over the last few years, the fledgling UK AMM industry has started to ascend a learning curve. However, it has suffered a major setback since the wholesale price of electricity fell under the New Electricity Trading Arrangements and AMM does not currently qualify as renewable energy in the UK. Coalbed methane produced via boreholes from virgin coal seams, known as Virgin Coalbed Methane (VCBM), has been the subject of significant exploration effort in Lancashire, North Wales, South Wales and Scotland. The best production of gas and water from a single well is understood to be from the project at Airth, north of Falkirk in Scotland. However, this is not economic at present. The main reason for the slow development of VCBM in the UK is perceived to be the widespread low permeability of UK coal seams, although little work has been carried out in the UK on coal permeability, or to truly identify the reasons for the lack of success. This must be overcome before the otherwise significant resource bases in the Clackmannan Syncline, Canonbie, Cumbria, South Lancashire, North Wales, North Staffordshire and South Wales coalfields can be exploited. A technological breakthrough is required to overcome the likely widespread low permeability in the UK Carboniferous coal seams. Otherwise, at best, production will probably be limited to niche opportunities in areas where high seam permeability exists. The criteria used to define and map the location of VCBM resources are as follows: • Coal seams greater than 0.4 m in thickness at depths >200 m • Seam gas content >1m3/tonne • 500 metres or more horizontal separation from underground coal workings • Vertical separation of 150m above and 40 m below a previously worked seam Vertical separation of >100 m from major unconformities of these areas is thought to be about ,900 x 109 m3 (about 29 years of UK natural gas consumption). he main criteria sed for the delineation and mapping of resource areas with potential for UCG were: eparation from underground coal workings and current omic and environmental grounds as described later in this report. he establishment of these criteria do not rule out UCG projects in shallower or thinner seams, if • Vertical separation of >100 m from major aquifers, and • Areas with a CMM resource (current underground coal mining licences) were excluded. Note that the presence of a CBM resource does not imply permeability in the coal seams or that the resource can be recovered economically now or at any time in the future. Using these criteria resource areas were defined and represented on the maps. The total VCBM resource 2 Underground coal gasification (UCG) is the process whereby the injection of oxygen and steam/water via a borehole results in the partial in-situ combustion of coal to produce a combustible gas mixture consisting of CO2, CH4, H2 and CO, the proportions depending on temperature, pressure conditions and the reactant gases injected. This product gas is then extracted via a producing well for use as an energy source. All previous trials of this technology in the UK took place in the 1950’s or before, e.g. Durham (1912), Newman Spinney (1949-1956) and Bayton (c.1955), although this country is well placed for UCG, with large reserves of indigenous coal both onshore and offshore. T u • Seams of 2 m thickness or greater • Seams at depths between 600 and 1200 m from the surface • 500 m or more horizontal and vertical scoal mining licences, and • Greater than 100 m from major aquifers While seams outside these depth and thicknesses criteria are known to support UCG, the criteria were chosen for this generic study on econ T local site specific factors support it. Mapping of the potential UCG resource has identified large areas suitable for UCG, particularly in Eastern England, Midland Valley of Scotland, North Wales, Cheshire Basin, South Lancashire, Canonbie, the Midlands and Warwickshire. Potential also exists in other coalfields but on a smaller scale; this is often limited by the extent of former underground coal mining activities. The total area where coals are suitable for gasification is approximately 2.8 x 109m2. Where the criteria for UCG are met, the minimum volume of coal available for gasification, calculated assuming only one 2 m thick seam meets the criteria across each area, is app63 roximately 5,698 x 10 m (~7 Btonnes). Using an verage of the total thickness of coals that meet the criteria across each area gives a more realistic source figure of 12,911 x 106m3 (~17 Btonnes). pass the expensive step of parating the CO2 from flue gases. If the main objective, however, is CO2 sequestration rather than ethane production then separation of the flue gases may be worthwhile. O2 on coal seams, is would render them unminable and ungasifiable (because the CO2 would be released). Any future ining of such coals would require re-capture and sequestration of the stored CO . ion, providing that other issues, such as low seam permeability, can be vercome. Large areas where coal is below 1,200 m occur in the UK, particularly in the Cheshire asin and Eastern England. In summary • and its potential application in the UK cannot be assessed. However, there are vast areas of coal at depths below 1,200 m that are possibly too deep for mining and in situ gasification
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