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Gabriele Broll - One of the best experts on this subject based on the ideXlab platform.

  • Layering in the Rocky Mountain treeline ecotone: clonal conifer groups’ Distribution, Structure, and functional role
    Trees, 2017
    Co-Authors: Friedrich-karl Holtmeier, Gabriele Broll
    Abstract:

    Key message Layering plays a major role in treeline stability. Growth ring pattern of clonal groups reflects both an individualistic and an only temporally common response to the harsh treeline environment . Abstract Clonal groups are common to alpine and polar treelines. Distribution, shape, architecture, and development of clonal Picea engelmannii and Abies lasiocarpa in an extremely windy Rocky Mountain treeline ecotone are considered. Clonal groups prevail (>70% of all tree groups). Most of them consist of A. lasiocarpa (65%). Number, growth form, and damage were documented along transects and field routes. Age Structure and development of the clonal groups were assessed using increment cores and stem disks. The groups usually consisted of different clonal series with several clonal members in each. On wind-swept terrain, clonal groups exhibit wedge-like, hedge-like, or mat-like habit. One clonal A. lasiocarpa group was studied in detail and it serves as an example showing formation, architecture, and internal growth pattern of clonal series. The clone members in the clone series exhibited an individualistic growth pattern. Wind-control of growth occasionally overruled the often ‘chaotic’ internal group growth pattern. The effect of prevailing winds, however, temporally overlapped with a ‘force’ directed from the center of the group margin (e.g., competition for light, high stem density), as reflected in recurrent change of eccentricity within the clonal trunks. Clonal groups may be of major importance in treeline dynamics.

  • Layering in the Rocky Mountain treeline ecotone: clonal conifer groups’ Distribution, Structure, and functional role
    Trees-structure and Function, 2017
    Co-Authors: Friedrich-karl Holtmeier, Gabriele Broll
    Abstract:

    Key message Layering plays a major role in treeline stability. Growth ring pattern of clonal groups reflects both an individualistic and an only temporally common response to the harsh treeline environment.

Dick Van Damme - One of the best experts on this subject based on the ideXlab platform.

  • A sectoral perspective on Distribution Structure design
    International Journal of Logistics Research and Applications, 2020
    Co-Authors: Alexander T. C. Onstein, Lóránt Tavasszy, Jafar Rezaei, Dick Van Damme, Adeline Heitz
    Abstract:

    This paper studies the factors that drive Distribution Structure design (DSD), which includes the spatial layout of Distribution channels and location choice of logistics facilities. We build on a ...

  • Importance of factors driving firms’ decisions on spatial Distribution Structures
    International Journal of Logistics Research and Applications, 2019
    Co-Authors: A.t.c. Onstein, Lóránt Tavasszy, Jafar Rezaei, Mehrnaz Ektesaby, Dick Van Damme
    Abstract:

    The design of a spatial Distribution Structure is of strategic importance for companies, to meet required customer service levels and to keep logistics costs as low as possible. Spatial distributio...

  • Factors determining Distribution Structure decisions in logistics: a literature review and research agenda
    Transport Reviews, 2018
    Co-Authors: A.t.c. Onstein, Lóránt Tavasszy, Dick Van Damme
    Abstract:

    Distribution Structures, as studied in this paper, involve the spatial layout of the freight transport and storage system used to move goods between production and consumption locations. Decisions on this layout are important to companies as they allow them to balance customer service levels and logistics costs. Until now there has been very little descriptive research into the factors that drive decisions about these Structures. Moreover, the literature on the topic is scattered across various research streams. In this paper we review and consolidate this literature, with the aim to arrive at a comprehensive list of factors. Three relevant research streams were identified: Supply Chain Management (SCM), Transportation and Geography. The SCM and Transportation literature mostly focus on Distribution Structure including Distribution centre (DC) location selection from a viewpoint of service level and logistics costs factors. The Geography literature focuses on spatial DC location decisions and resulting patterns mostly explained by location factors such as labour and land availability. Our review indicates that the main factors that drive decision-making are “demand level”, “service level”, “product characteristics”, “logistics costs”, “labour and land”, “accessibility” and “contextual factors”. The main trade-off influencing Distribution Structure selection is “service level” versus “logistics costs”. Together, the research streams provide a rich picture of the factors that drive Distribution Structure including DC location selection. We conclude with a framework that shows the relative position of these factors. Future work can focus on completing the framework by detailing out the sub factors and empirically testing the direction and strength of relationships. Cooperation between the three research streams will be useful to further extend and operationalize the framework.

Raf Jans - One of the best experts on this subject based on the ideXlab platform.

  • Benders decomposition for a stochastic three-level lot sizing and replenishment problem with a Distribution Structure
    European Journal of Operational Research, 2020
    Co-Authors: Matthieu Gruson, Jean-françois Cordeau, Raf Jans
    Abstract:

    Abstract We address a stochastic three-level lot sizing and replenishment problem with a Distribution Structure in a two-stage decision process. We consider one production plant that produces one type of item over a discrete and finite planning horizon. The items produced are transported to warehouses and then to retailers using direct shipments. Each retailer is linked to a unique warehouse and there are no transfers between warehouses nor between retailers. The stochasticity comes from the uncertainty in the demand at the retailer level and is modelled through scenarios. The setup decisions are made in the first stage and the production, transportation and inventory decisions are made in the second stage, once the demands are revealed. The objective is to minimize the sum of the fixed production and replenishment costs, and of the expected variable inventory holding costs among all scenarios. We also study an extension where we allow for lost sales at the retailer level. We use a Benders decomposition approach and develop a Benders-based branch-and-cut algorithm to efficiently solve the problem. We take advantage of the subStructures identified in the decomposition and design efficient procedures to solve the subproblems obtained. We also propose computational enhancements to speed up the solution process. Finally, we perform extensive computational experiments to assess the performance of our decomposition approach and analyze the impact of the enhancements. The Benders-based branch-and-cut algorithm we propose clearly outperforms CPLEX.

  • A comparison of formulations for a three-level lot sizing and replenishment problem with a Distribution Structure
    Computers & Operations Research, 2019
    Co-Authors: Matthieu Gruson, Jean-françois Cordeau, Majid Bazrafshan, Raf Jans
    Abstract:

    Abstract We address a three-level lot sizing and replenishment problem with a Distribution Structure (3LSPD), which is an extension of the one-warehouse multi-retailer problem (OWMR). We consider one production plant that produces one type of item over a discrete and finite planning horizon. The items produced are used to replenish warehouses and then retailers using direct shipments. Each retailer is linked to a unique warehouse and there are no transfers between warehouses nor between retailers. We also assume that transportation is uncapacitated. However, we consider the possibility of imposing production capacity constraints at the production plant level. The objective is to minimize the sum of the fixed production and replenishment costs and of the variable inventory holding costs at all three levels. We compare 13 different MIP formulations to solve the problem. All of these formulations are adapted from existing MIP formulations found in the one-warehouse multi-retailer literature, but most formulations are new in the context of the 3LSPD. We run experiments on both balanced and unbalanced networks. Our results indicate that the multi-commodity formulation is well suited for uncapacititated instances and that the echelon stock reformulations are better for capacitated instances. They also show that the richer formulations are not necessarily the best ones and that the unbalanced instances are harder to solve.

Friedrich-karl Holtmeier - One of the best experts on this subject based on the ideXlab platform.

  • Layering in the Rocky Mountain treeline ecotone: clonal conifer groups’ Distribution, Structure, and functional role
    Trees, 2017
    Co-Authors: Friedrich-karl Holtmeier, Gabriele Broll
    Abstract:

    Key message Layering plays a major role in treeline stability. Growth ring pattern of clonal groups reflects both an individualistic and an only temporally common response to the harsh treeline environment . Abstract Clonal groups are common to alpine and polar treelines. Distribution, shape, architecture, and development of clonal Picea engelmannii and Abies lasiocarpa in an extremely windy Rocky Mountain treeline ecotone are considered. Clonal groups prevail (>70% of all tree groups). Most of them consist of A. lasiocarpa (65%). Number, growth form, and damage were documented along transects and field routes. Age Structure and development of the clonal groups were assessed using increment cores and stem disks. The groups usually consisted of different clonal series with several clonal members in each. On wind-swept terrain, clonal groups exhibit wedge-like, hedge-like, or mat-like habit. One clonal A. lasiocarpa group was studied in detail and it serves as an example showing formation, architecture, and internal growth pattern of clonal series. The clone members in the clone series exhibited an individualistic growth pattern. Wind-control of growth occasionally overruled the often ‘chaotic’ internal group growth pattern. The effect of prevailing winds, however, temporally overlapped with a ‘force’ directed from the center of the group margin (e.g., competition for light, high stem density), as reflected in recurrent change of eccentricity within the clonal trunks. Clonal groups may be of major importance in treeline dynamics.

  • Layering in the Rocky Mountain treeline ecotone: clonal conifer groups’ Distribution, Structure, and functional role
    Trees-structure and Function, 2017
    Co-Authors: Friedrich-karl Holtmeier, Gabriele Broll
    Abstract:

    Key message Layering plays a major role in treeline stability. Growth ring pattern of clonal groups reflects both an individualistic and an only temporally common response to the harsh treeline environment.

A.t.c. Onstein - One of the best experts on this subject based on the ideXlab platform.

  • Importance of factors driving firms’ decisions on spatial Distribution Structures
    International Journal of Logistics Research and Applications, 2019
    Co-Authors: A.t.c. Onstein, Lóránt Tavasszy, Jafar Rezaei, Mehrnaz Ektesaby, Dick Van Damme
    Abstract:

    The design of a spatial Distribution Structure is of strategic importance for companies, to meet required customer service levels and to keep logistics costs as low as possible. Spatial distributio...

  • Factors determining Distribution Structure decisions in logistics: a literature review and research agenda
    Transport Reviews, 2018
    Co-Authors: A.t.c. Onstein, Lóránt Tavasszy, Dick Van Damme
    Abstract:

    Distribution Structures, as studied in this paper, involve the spatial layout of the freight transport and storage system used to move goods between production and consumption locations. Decisions on this layout are important to companies as they allow them to balance customer service levels and logistics costs. Until now there has been very little descriptive research into the factors that drive decisions about these Structures. Moreover, the literature on the topic is scattered across various research streams. In this paper we review and consolidate this literature, with the aim to arrive at a comprehensive list of factors. Three relevant research streams were identified: Supply Chain Management (SCM), Transportation and Geography. The SCM and Transportation literature mostly focus on Distribution Structure including Distribution centre (DC) location selection from a viewpoint of service level and logistics costs factors. The Geography literature focuses on spatial DC location decisions and resulting patterns mostly explained by location factors such as labour and land availability. Our review indicates that the main factors that drive decision-making are “demand level”, “service level”, “product characteristics”, “logistics costs”, “labour and land”, “accessibility” and “contextual factors”. The main trade-off influencing Distribution Structure selection is “service level” versus “logistics costs”. Together, the research streams provide a rich picture of the factors that drive Distribution Structure including DC location selection. We conclude with a framework that shows the relative position of these factors. Future work can focus on completing the framework by detailing out the sub factors and empirically testing the direction and strength of relationships. Cooperation between the three research streams will be useful to further extend and operationalize the framework.

  • Distribution Structure and Distribution centre location decision-making – A review
    2015
    Co-Authors: A.t.c. Onstein, D.a. Van Damme, Lóránt Tavasszy
    Abstract:

    Distribution Structures and Distribution centre (DC) locations are essential for logistics companies to optimise logistics costs and service levels. This paper reviews Supply Chain Management (SCM), Geography and Economic Geographic literature on Distribution Structure and DC locations decision-making. Two central decision-making elements are discussed: process steps and decision-making factors. Added value of our paper is 1) A literature review 2) Conclusions on the state of current scientific knowledge in three research streams 3) A research agenda. Reviewing literature shows decision-making factors are renowned, however, importance of factors in each process step is unknown. Results also show literature diverges on which process steps logistics companies take (descriptive) or should optimally take (prescriptive) in Distribution Structure and DC location decision-making. Thus, more research is needed. Developing a descriptive conceptual model and testing on several industry sectors will be valuable to understand differences on Distribution Structure and DC location decision-making.