2,733 research outputs found

    Children, internet cultures and online social networks

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    Comparison of Pruning Regimes for Stone Pine (Pinus pinea L.) Using a Functional- Structural Plant Model

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    Functional-Structural Plant Models (FSPM) are becoming important tools for modeling the structure and growth of plants, including complex organisms like trees. These models combine the advantages of empirical, mechanistic, and structural models to simulate the growth of individual plant structures (branches, buds, leaves, etc.). This approach enables realistic evaluation of the plant‚Äôs response‚Äď including changes in structure and growth to different environmental conditions. We demonstrate the potential use of these models to evaluate individual tree growth under different management regimes (pruning). The data used in this study was obtained from 3-D measurements taken with a FASTRAK Polhemus digitizer, with specific attention given to bud creation and branching. Each branch segment was analyzed to estimate its age, enabling us to document annual structural changes. We use the XL programming language and a GroIMP environment to simulate and compare different pruning scenarios

    Optimal Regeneration Regime under Continuous Crown Cover Requirements in Cork Oak Woodlands

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    In the present work the cork oak tree spatial growth simulator CORKFITS is used to create candidate scenarios for generating a large set of regeneration regimes combining both time and intensity factors with the individual tree spatial information. An optimal regeneration regime under continuous crown cover requirements is sought by applying a dynamic programming algorithm. It is shown that the crown cover constraint influences the total cork production potential in a negative way. The target cover constraint of 50% decreases the cork production by 66% from the potential in 40 years in our mature plot, and approximately 43% in our young plot. Higher crown cover constraint of 70% decreases the potential cork production approximately by 54% in the mature plot and does not have any influence on the younger plot. The observed losses in cork production in relation with the potential with the crown cover constrains need to be compensated economically by the higher availability of growing space for the grazing and livestock part of the montado/dehesa production system

    Comparative mapping of disease resistance genes in Lathyrus spp. using model legume genetic information

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    Lathyrus cicera L. (chickling pea) and L. sativus L. (grass pea) have great potential among grain legumes due to their adaptability to inauspicious environments, high protein content and resistance to serious diseases. Lathyrus spp. are considered potential sources of high quality and cheap protein. Nevertheless, due to its past underuse, further activities are required to exploit this potential and to capitalise on the present molecular biology advances on Lathyrus spp. breeding programmes.(...

    Large scale railway renewal planning with a multiobjective modeling approach

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    Confer√™ncia realizada na Fil√Ęndia, Helsinquia, de 20-24 de agosto de 2018A multiobjective modeling approach for managing large scale railway infrastructure asset renewal is presented. An optimized intervention project schedule is obtained considering operational constraints in a three objectives model: evenly spreading investment throughout multiple years, minimizing total cost, minimizing work start postponements on higher priority railway sections. The MILP model was based on a real world case study; the objectives and constraints specified by an infrastructure management company. Results show that investment spreading greatly influences the other objectives and that total cost fluctuations depend on the overall condition of the railway infrastructure. The model can produce exact efficient solutions in reasonable time, even for very large-sized instances (a test network of similar size to the USA railway network, the largest in the world). The modeling approach is therefore a very useful, practical methodology, for generating optimized solutions and analyzing trade-offs among objectives, easing the task of ultimately selecting a solution and produce the works schedule for field implementation.info:eu-repo/semantics/publishedVersio

    Bi-objective modeling approach for repairing multiple feature infrastructure systems

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    A bi-objective decision aid model for planning long-term maintenance of infrastructure systems is presented, oriented to interventions on their constituent elements, with two upgrade levels possible for each element (partial/full repairs). The model aims at maximizing benefits and minimizing costs, and its novelty is taking into consideration, and combining, the system/element structure, volume discounts, and socioeconomic factors. The model is tested with field data from 229 sidewalks (systems) and compared to two simpler repair policies, of allowing only partial or full repairs. Results show that the efficiency gains are greater in the lower mid-range budget region. The proposed modeling approach is an innovative tool to optimize cost/benefits for the various repair options and analyze the respective trade-offs.info:eu-repo/semantics/publishedVersio

    Multi-objective model for optimizing railway infrastructure asset renewal

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    Trabalho inspirado num problema real da empresa Infraestruturas de Portugal, EP.A multi-objective model for managing railway infrastructure asset renewal is presented. The model aims to optimize three objectives, while respecting operational constraints: levelling investment throughout multiple years, minimizing total cost and minimizing work start postponements. Its output is an optimized intervention schedule. The model is based on a case study from a Portuguese infrastructure management company, which specified the objectives and constraints, and reflects management practice on railway infrastructure. The results show that investment levelling greatly influences the other objectives and that total cost fluctuations may range from insignificant to important, depending on the condition of the infrastructure. The results structure is argued to be general and suggests a practical methodology for analysing trade-offs and selecting a solution for implementation.info:eu-repo/semantics/publishedVersio

    Gest√£o sustentada dos montados de sobro. Solu√ß√Ķes de engenharia florestal para a gest√£o adaptativa

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    O montado de sobro e os sobreirais s√£o sistemas de produ√ß√£o florestal complexos que resultam da integra√ß√£o de actividades agro pastoris ou pastoris em povoamentos florestais sendo a estrutura e densidade e a din√Ęmica definida de acordo com a qualidade da esta√ß√£o e objectivos de gest√£o. No contexto actual √© fundamental implementar t√©cnicas de gest√£o adaptativa associada com modelos de crescimento e sistemas de apoio √† decis√£o, constru√≠dos com base em s√≥lidos sistemas de monitoriza√ß√£o cont√≠nua, para a elabora√ß√£o de planos de gest√£o com grande precis√£o assentes em objectivos de gest√£o de longo prazo. A implementa√ß√£o dos planos de gest√£o deve de estar alicer√ßada em pol√≠ticas de transfer√™ncia de conhecimento ligando as universidades e os centros de investiga√ß√£o aos produtores/gestores atrav√©s da engenharia florestal. O montado de sobro e os sobreirais s√£o particularmente relevantes j√° que dominam a paisagem a sudoeste da Pen√≠nsula Ib√©rica, ocupando cerca de 0.574 milh√Ķes de hectares em Espanha e 0.737 milh√Ķes de hectares em Portugal Continental, representando cerca de 61 % da √°rea mundial de sobreiro e 80% da produ√ß√£o mundial de corti√ßa
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