237 research outputs found

    The optimisation of a strategic business process

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    The optimisation of a Tendering Process for Warship Refit Contracts is presented. The Pre Contract Award process (PCA) involves all the activities needed to successfully win a Refit Contract, e.g. estimating, planning, tendering and negotiation. Process activities and information flows have been modelled using Integrated computer aided manufacturing DEFinition methodology (IDEF0) and a Design Structure Matrix (DSM) with optimisation performed via a Genetic Algorithm (DSM-GA) search technique [1]. The aim of the DSM-GA is to provide the user with an enhanced sequence of performing process activities. A new process was extracted from the optimised solution, showing an improved sequence with reduced iteration and planned activity concurrency based on carefully considered information requirements. This is of practical benefit to enhance understanding and to provide a guide to implementation. The approach suggests an enhanced sequence of process activities, based on information requirements, and can lead to improved business practice. This Paper discusses the potential benefits and limitations of this approach in a practical setting

    The optimisation of the estimating and tendering process in warship refit - a case study

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    The optimisation of a tendering process for warship refit contracts is presented. The tendering process, also known as the pre-contract award process (PCA), involves all the activities needed to be successfully awarded a refit contract. Process activities and information flows have been modelled using Integrated Definition Language IDEF0 and a Dependency Structure Matrix (DSM) with optimisation performed via a Genetic Algorithm (DSM-GA) search technique. By utilising this approach the process activities were re-sequenced in such an order that the number and size of rework cycles were reduced. The result being a 57% reduction in a criterion indicating 're-work' cycles

    Climate Change in the High Andes:implications and adaptation strategies for small-scale farmers

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    Abstract: Global climate change represents a major threat to sustainable farming in the Andes. Farmers have used local ecological knowledge and intricate production systems to cope, adapt and reorganize to meet climate uncertainty and risk, which have always been a fact of life. Those traditional systems are generally highly resilient, but the predicted effects, rates and variability of climate change may push them beyond their range of adaptability. This article examines the extent of actual and potential impacts of climate variability and change on small-scale farmers in the highland Andes of Bolivia, Ecuador and Peru. It describes how climate change impacts agriculture through deglaciation, changes in hydrology, soil and pest and disease populations. The article highlights some promising adaptive strategies currently in use by or possible for producers, rural communities and local institutions to mitigate climate change effects while preserving the livelihoods and environmental and social sustainability of the regio

    Genetic structure of the population of Phytophthora infestans attacking Solanum ochranthum in the highlands of Ecuador

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    Thirty-nine isolates of Phytophthora infestans were collected from the wild host Solanum ochranthum in the highland tropics of Ecuador and characterized with a set of phenotypic and molecular markers (mating type, metalaxyl sensitivity, the allozyme loci Gpi, and Pep, mitochondrial DNA haplotype, RFLP, and SSR), as well as for pathogenicity on various hosts. Three groups of isolates (A, B, and C) were identified based on their multilocus genotypes and variable abilities to cause disease on different hosts. Group A had a combination of alleles for the Gpi (86/100), Pep (96/100) and mtDNA (Ia) loci, as well as an RFLP fingerprint, that have not been reported for P. infestans in Ecuador, or elsewhere. Group B shares many marker characteristics with the US-1 lineage described in Ecuador on tomato, pear melon (S. muricatum), and S. caripense, but has SSR alleles not present in typical US-1 isolates. Group C for all markers tested is identical to the EC-1 lineage described on cultivated and wild potatoes in Ecuador. All isolates from S. ochranthum were able to re-infect their host of origin in the detached leaf assay; however, we did not draw clear conclusions as to the relative aggressiveness of the three groups on this host. Isolates of group A were the most specialized and were generally non-pathogenic or weakly pathogenic on all hosts other than S. ochranthum. Groups B and C infected tuber-bearing hosts, including the cultivated potato but were generally non-pathogenic on other non-tuber bearing hosts. Solanum ochranthum was infected by isolates coming from tuber-bearing Solanum hosts (i.e., the EC-1 lineage of P. infestans) and some US-1 isolates from non-tuber bearing hosts. Thus, in nature this species might be a potential reservoir of inoculum of different pathogen populations able to infect the cultivated hosts potato, tomato and pear melon (S.¿muricatum). Unlike potato and tomato in Ecuador, each of which is primarily attacked by a highly specialized pathogen population, S. ochranthum appears to harbour at least three pathogen groups of¿different genetic make-up. The unresolved issue of potential host specificity in isolates found on S.¿ochranthum could complicate efforts to use this species in tomato improvemen

    Seed degeneration in potato : the need for an integrated seed health strategy to mitigate the problem in developing countries

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    Seed potato degeneration, the reduction in yield or quality caused by an accumulation of pathogens and pests in planting material due to successive cycles of vegetative propagation, has been a long-standing production challenge for potato growers around the world. In developed countries this problem has been overcome by general access to and frequent use of seed, produced by specialized growers, that has been certified to have pathogen and pest incidence below established thresholds, often referred to as certified seed. The success of certified seed in developed countries has concentrated the research and development agenda on the establishment of similar systems in developing countries. Despite these efforts, certified seed has had little penetration into the informal seed systems currently in place in most developing countries. Small-scale farmers in these countries continue to plant seed tubers acquired through the informal seed system, i.e. produced on-farm or acquired from neighbours or local markets. Informal seed tubers frequently have poor health status, leading to significant reductions in yield and/or market value. This review emphasizes the need to refocus management efforts in developing countries on improving the health status of seed tubers in the informal system by integrating disease resistance and on-farm management tools with strategic seed replacement. This 'integrated seed health strategy' can also prolong the good health status of plants derived from certified seed, which would otherwise be diminished due to potential rapid infection from neighbouring fields. Knowledge gaps, development challenges and impacts of this integrated seed health strategy are discussed.PostprintPeer reviewe

    Multiwavelength Study of M8.9/3B Solar Flare from AR NOAA 10960

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    We present a multi-wavelength analysis of a long duration white-light solar flare (M8.9/3B) event that occurred on 4 June 2007 from NOAA AR 10960. The flare was observed by several spaceborne instruments, namely SOHO/MDI, Hinode/SOT, TRACE and STEREO/SECCHI. The flare was initiated near a small, positive-polarity, satellite sunspot at the centre of the AR, surrounded by opposite-polarity field regions. MDI images of the AR show considerable amount of changes in a small positive-polarity sunspot of delta configuration during the flare event. SOT/G-band (4305 A) images of the sunspot also suggest the rapid evolution of the positive-polarity sunspot with highly twisted penumbral filaments before the flare event, which were oriented in the counterclockwise direction. It shows the change in orientation and also remarkable disappearance of twisted penumbral filaments (~35-40%) and enhancement in umbral area (~45-50%) during the decay phase of the flare. TRACE and SECCHI observations reveal the successive activations of two helical twisted structures associated with this sunspot, and the corresponding brightening in the chromosphere as observed by the time-sequence images of SOT/Ca II H line (3968 A). The secondary-helical twisted structure is found to be associated with the M8.9 flare event. The brightening starts 6-7 min prior to the flare maximum with the appearance of secondary helical-twisted structure. The flare intensity maximizes as this structure moves away from the AR. This twisted flux-tube associated with the flare triggering, is found to be failed in eruption. The location of the flare is found to coincide with the activation site of the helical twisted structures. We conclude that the activations of successive helical twists in the magnetic flux tubes/ropes plays a crucial role in the energy build-up process and triggering of M-class solar flare without a CME.Comment: 22 pages, 12 figures, Accepted for Publication in Solar Physic

    The effective force NL3 revisited

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    Covariant density functional theory based on the relativistic mean field (RMF) Lagrangian with the parameter set NL3 has been used in the last ten years with great success. Now we propose a modification of this parameter set, which improves the description of the ground state properties of many nuclei and simultaneously provides an excellent description of excited states with collective character in spherical as well as in deformed nuclei.Comment: 8 pages, 5 figure

    3D evolution of a filament disappearance event observed by STEREO

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    A filament disappearance event was observed on 22 May 2008 during our recent campaign JOP 178. The filament, situated in the southern hemisphere, showed sinistral chirality consistent with the hemispheric rule. The event was well observed by several observatories in particular by THEMIS. One day before the disappearance, Hα\alpha observations showed up and down flows in adjacent locations along the filament, which suggest plasma motions along twisted flux rope. THEMIS and GONG observations show shearing photospheric motions leading to magnetic flux canceling around barbs. STEREO A, B spacecraft with separation angle 52.4 degrees, showed quite different views of this untwisting flux rope in He II 304 \AA\ images. Here, we reconstruct the 3D geometry of the filament during its eruption phase using STEREO EUV He II 304 \AA\ images and find that the filament was highly inclined to the solar normal. The He II 304 \AA\ movies show individual threads, which oscillate and rise to an altitude of about 120 Mm with apparent velocities of about 100 km s1^{-1}, during the rapid evolution phase. Finally, as the flux rope expands into the corona, the filament disappears by becoming optically thin to undetectable levels. No CME was detected by STEREO, only a faint CME was recorded by LASCO at the beginning of the disappearance phase at 02:00 UT, which could be due to partial filament eruption. Further, STEREO Fe XII 195 \AA\ images showed bright loops beneath the filament prior to the disappearance phase, suggesting magnetic reconnection below the flux rope

    Eruptions of Magnetic Ropes in Two Homologous Solar Events on 2002 June 1 and 2: a Key to Understanding of an Enigmatic Flare

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    The goal of this paper is to understand the drivers, configurations, and scenarios of two similar eruptive events, which occurred in the same solar active region 9973 on 2002 June 1 and 2. The June 2 event was previously studied by Sui, Holman, and Dennis (2006, 2008), who concluded that it was challenging for popular flare models. Using multi-spectral data, we analyze a combination of the two events. Each of the events exhibited an evolving cusp-like feature. We have revealed that these apparent ``cusps'' were most likely mimicked by twisted magnetic flux ropes, but unlikely to be related to the inverted Y-like magnetic configuration in the standard flare model. The ropes originated inside a funnel-like magnetic domain whose base was bounded by an EUV ring structure, and the top was associated with a coronal null point. The ropes appear to be the major drivers for the events, but their rise was not triggered by reconnection in the coronal null point. We propose a scenario and a three-dimensional scheme for these events in which the filament eruptions and flares were caused by interaction of the ropes.Comment: 22 pages, 11 figure
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