Detecting disturbances in supply chains: the case of capacity constraints

Purpose – The ability to detect disturbances quickly as they arise in a supply chain helps to manage them efficiently and effectively. This paper is aimed at demonstrating the feasibility of automatically, and therefore quickly detecting a specific disturbance, which is constrained capacity at a supply chain echelon. Design/Methodology/approach – Different supply chain echelons of a simulated four echelon supply chain were individually capacity constrained to assess their impacts on the profiles of system variables, and to develop a signature that related the profiles to the echelon location of the capacity constraint. A review of disturbance detection techniques across various domains formed the basis for considering the signature based technique. Findings – The signature for detecting a capacity constrained echelon was found to be based on cluster profiles of shipping and net inventory variables for that echelon as well as other echelons in a supply chain, where the variables are represented as spectra. Originality/value– Detection of disturbances in a supply chain including that of constrained capacity at an echelon has seen limited research where this study makes a contribution

Managing Supply Chain Events to Build Sense-and-Respond Capability

As supply chains become more dynamic, there is a need for a sense-and-respond capability to react to events in a real-time manner. In this paper, we propose Petri nets extended with time and color (for case data) as a formalism for doing so. Hence, we describe seven basic patterns that are used to capture modeling concepts that arise commonly in supply chains. These basic patterns may be used by themselves and also be combined to create new patterns. Next, we show how to use the patterns as building blocks to model a complete supply chain and analyze it using dependency graphs and simulation. Dependency graphs can be used to analyze the various events and their causes. Simulation was, in addition, used to analyze various performance indicators (e.g. fill rates, replenishment times, and lead times) under different supply chain strategies. We performed sensitivity analysis to study the effect of changing parameter values on the performance indicators. In the experiments, by cutting resolution time for production delays in half (strategy 1), we were able to increase order fill rate from 89% to 95%. Similarly, upon raising the probability of successful alternative sourcing (strategy 2) from 0.5 to 0.7 the order fill rate again increased from 89% to 95%. We show that by modeling timing and causality issues accurately, it is possible to improve supply chain performance

Multi Agent Systems in Logistics: A Literature and State-of-the-art Review

Based on a literature survey, we aim to answer our main question: “How should we plan and execute logistics in supply chains that aim to meet today’s requirements, and how can we support such planning and execution using IT?†Today’s requirements in supply chains include inter-organizational collaboration and more responsive and tailored supply to meet specific demand. Enterprise systems fall short in meeting these requirements The focus of planning and execution systems should move towards an inter-enterprise and event-driven mode. Inter-organizational systems may support planning going from supporting information exchange and henceforth enable synchronized planning within the organizations towards the capability to do network planning based on available information throughout the network. We provide a framework for planning systems, constituting a rich landscape of possible configurations, where the centralized and fully decentralized approaches are two extremes. We define and discuss agent based systems and in particular multi agent systems (MAS). We emphasize the issue of the role of MAS coordination architectures, and then explain that transportation is, next to production, an important domain in which MAS can and actually are applied. However, implementation is not widespread and some implementation issues are explored. In this manner, we conclude that planning problems in transportation have characteristics that comply with the specific capabilities of agent systems. In particular, these systems are capable to deal with inter-organizational and event-driven planning settings, hence meeting today’s requirements in supply chain planning and execution.supply chain;MAS;multi agent systems

Multi Agent Systems in Logistics: A Literature and State-of-the-art Review

Based on a literature survey, we aim to answer our main question: “How should we plan and execute logistics in supply chains that aim to meet today’s requirements, and how can we support such planning and execution using IT?” Today’s requirements in supply chains include inter-organizational collaboration and more responsive and tailored supply to meet specific demand. Enterprise systems fall short in meeting these requirements The focus of planning and execution systems should move towards an inter-enterprise and event-driven mode. Inter-organizational systems may support planning going from supporting information exchange and henceforth enable synchronized planning within the organizations towards the capability to do network planning based on available information throughout the network. We provide a framework for planning systems, constituting a rich landscape of possible configurations, where the centralized and fully decentralized approaches are two extremes. We define and discuss agent based systems and in particular multi agent systems (MAS). We emphasize the issue of the role of MAS coordination architectures, and then explain that transportation is, next to production, an important domain in which MAS can and actually are applied. However, implementation is not widespread and some implementation issues are explored. In this manner, we conclude that planning problems in transportation have characteristics that comply with the specific capabilities of agent systems. In particular, these systems are capable to deal with inter-organizational and event-driven planning settings, hence meeting today’s requirements in supply chain planning and execution

Synthesis of Optimization and Simulation for Multi-Period Supply Chain Planning with Consideration of Risks

Solutions to deterministic optimizing models for supply chains can be very sensitive to the formulation of the objective function and the choice of planning horizon. We illustrate how multi-period optimizing models may be counterproductive if traditional accounting of revenue and costs is performed and planning occurs with too short a planning horizon. We propose a “value added” complement to traditional financial accounting that allows planning to occur with shorter horizons than previously thought necessary. This dissertation presents a simulation model with an embedded optimizer that can help organizations develop strategies that minimize expected costs or maximize expected contributions to profit while maintaining a designated level of service. Plans are developed with a deterministic optimizing model and each of the decisions for the first period in the planning horizon are implemented within the simulator. Random deviations in demands and in upstream and downstream shipping times are imposed and the state of the system is updated at the end of each simulated period of activity. This process continues iteratively for a chosen number of periods (90 days for this research). Multiple replications are performed using unique random number seeds for each replication. The simulation model generates detailed event logs for each period of simulated activity that are used to analyze supply-chain performance and supply-chain risk. Supply-chain performance is measured with eleven key performance indicators that reveal system behavior at the overall supply-chain level, as well as performance related to individual plants, warehouses, and products. There are three key findings from this research. First, a value-added complement in an optimization model’s objective function can allow planning to occur effectively with a significantly shorter horizon than required when traditional accounting of costs and revenues is employed. Second, solutions with the value-added complement are robust for situations where supply-chain disruptions cause unexpected depletions in inventories at production facilities and warehouses. Third, ceteris paribus, the hybrid multi-period planning approach generates solutions with higher service levels for products with greater revenue per average production-minute, shorter average upstream lead times, and lower coefficients of variation for daily demand

Diseño de una cadena de suministro de ciclo cerrado para la cooperativa Mercar de la ciudad de Manizales

El presente trabajo de grado tiene como objetivo identificar las falencias generadas en el comercio minorista enfocado en los tenderos de la ciudad de Manizales de Frutas y verduras, permitiendo así identificar los aspectos principales que afectan la competitividad de estas tiendas en la ciudad de Manizales, teniendo en cuenta la existencia de una cooperativa en la ciudad de Manizales que puede fortalecer el sector mediante el suministro de productos y vinculación a la asociación que potencie el negocio mediante la integración de una cadena de suministro, partiendo de la premisa que una de las principales falencias que poseen los tenderos minoristas de frutas y/o verduras es su escaso poder de negociación frente a los proveedores debido a su sistema de compra al detal, por lo que este proyecto de grado además de recopilar la información de diferentes estudios de ciudad y país referente a los tenderos y su estructura comercial, busca brindar una alternativa de solución a los tenderos con el planteamiento de una cadena de suministro por parte de la cooperativa Mercar.The present degree work aims to identify failures generated in the retailer commerce focused in the shopkeerper’s fruits and vegetables of Manizales city, allowing to identify the main aspects that affect the competitiveness of these stores Manizales city, taking into account the existence of a cooperative in the city that can strengthen the sector by providing products and linking to the association that promote the business by the integration of a supply chain, starting of the premise that one of the main failures that have the retailers shopkeeper’s fruits and / or vegetables are their scarce power of negotiation against the suppliers due to their retail system, so that this degree project in addition to compile the information from different studies about city and country referring to the shopkeepers and their commercial structure, to provide them an alternative solution with the raising of a supply chain by the Mercar cooperative

Analysing supply chain operation dynamics through logic-based modelling and simulation

Supply Chain Management (SCM) is becoming increasingly important in the modern business world. In order to effectively manage and integrate a supply chain (SC), a deep understanding of overall SC operation dynamics is needed. This involves understanding how the decisions, actions and interactions between SC members affect each other, and how these relate to SC performance and SC disruptions. Achieving such an understanding is not an easy task, given the complex and dynamic nature of supply chains. Existing simulation approaches do not provide an explanation of simulation results, while related work on SC disruption analysis studies SC disruptions separately from SC operation and performance. This thesis presents a logic-based approach for modelling, simulating and explaining SC operation that fills these gaps. SC members are modelled as logicbased intelligent agents consisting of a reasoning layer, represented through business rules, a process layer, represented through business processes and a communication layer, represented through communicative actions. The SC operation model is declaratively formalised, and a rule-based specification is provided for the execution semantics of the formal model, thus driving the simulation of SC operation. The choice of a logic-based approach enables the automated generation of explanations about simulated behaviours. SC disruptions are included in the SC operation model, and a causal model is defined, capturing relationships between different types of SC disruptions and low SC performance. This way, explanations can be generated on causal relationships between occurred SC disruptions and low SC performance. This approach was analytically and empirically evaluated with the participation of SCM and business experts. The results indicate the following: Firstly, the approach is useful, as it allows for higher efficiency, correctness and certainty about explanations of SC operation compared to the case of no automated explanation support. Secondly, it improves the understanding of the domain for non-SCM experts with respect to their correctness and efficiency; the correctness improvement is significantly higher compared to the case of no prior explanation system use, without loss of efficiency. Thirdly, the logic-based approach allows for maintainability and reusability with respect to the specification of SC operation input models, the developed simulation system and the developed explanation system

An information systems framework for event management in supply chain operations

As competition has shifted from the company to the Supply Chain level, gaining a competitive edge becomes an issue of efficient collaboration amongst SC partners. Within the e-business era the level of competitiveness is determined by the ability of an SC to react and adjust rapidly to market and industrial changes and to overcome burdens originating both from inside and outside the SC borders. These features create the framework for defining agility within supply chains. Managing turbulence in SCs, while maintaining customer satisfaction at a low operational cost requires proactive dynamics towards risk factors. An agile Supply Chain addresses direct and indirect sources of risk, which expand outside the SC boundaries. Supply risk is related to the potential occurrence of an incident such as inbound supplies failure that results in customer dissatisfaction. Sources of risk in the SC have various origins which due to their dynamic nature cannot always be predicted, such as turbulence in oil or currency prices, physical or manmade disasters, production failures, product recalls and so on. Organizations need to respond to events as certain unexpected events can cause chaos in the SC and form patterns with negative impact, such as the bullwhip effect, backlogs etc. Chaos in the SC originates from managerial and computer control decisions and actions but apart from the internal sources, chaotic spikes in the SC demand can also originate from external changes. This thesis proposes that Internet based Information Systems support is required for responsive Supply Chains, in order to address risk origins under a holistic perspective. An event driven architectural framework is proposed in the context of SC operations, which enables flexibility and agility in an e-business setting. The concept of events is explored within the Supply Chain domain and the information regarding patterns of occurring events is identified and disseminated. Initially the theoretical ground for event identification is set and unexpected events in a SC context are classified. Building on the events classification, a notation (EPN) to model event patterns is described. Finally an architecture (SCEDRA) which captures unexpected events and forms and disseminates event patterns is proposed