Browsing by Subject "Supply chain"

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Influence of fruit logistics on fresh-cut pineapple (Ananas comosus [L.] Merr.) volatiles assessed by HS-SPME–GC–MS analysis
(2021) Steingass, Christof B.; Dickreuter, Jennifer; Kuebler, Sabine; Schweiggert, Ralf M.; Carle, Reinhold
Green-ripe pineapples are shipped overseas by sea freight, while those picked at full maturity need to be transported by airfreight over the same large distance. In this study, fresh-cut pineapple cubes were assessed two, five, and eight days after processing from green-ripe pineapples after mimicked sea freigh (SF) and fully ripe air-freighted (AF) pineapples. The sea-freighted samples displayed elevated titratable acidity (TA), thus resulting in smaller ratios of total soluble solids and TA compared to the AF pineapples. Differences in the carotenoid levels of the two fresh-cut categories were found to be insignificant. By contrast, hierarchical cluster analysis (HCA) and principal component analysis (PCA) calculated on the basis of the volatiles analysed by headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) permitted to distinguish all six individual sample types and to segregate them into two major clusters (SF and AF). The effect of storage on the volatiles was further evaluated by partial least squares (PLS) regression. Substantial chemical markers to differentiate the individual samples and to describe the effect of storage were deduced from the PCA and PLS regression, respectively. In general, fresh-cut products obtained from fully ripe AF fruit displayed higher concentrations of volatiles, in particular, increased concentrations of diverse methyl esters. With progressing storage duration, the concentrations of ethanol and diverse ethyl esters increased. Moreover, products from AF pineapples displayed lower microbial counts compared to those from SF fruit.
Interdependenzen zwischen Planungsproblemen
ein multiagentenbasierter Koordinationsansatz
(2016) Schüle, Michael; Kirn, Stefan
In this thesis, interdependencies of planning problems in a supply chain in the context of a civil engineering logistic scenario are analysed. In this construction site scenario there are - within the scheduling of activities - the resource-constrained project scheduling problem (RCPSP) and - within the spatial distribution of activities - the asymmetric traveling salesman problem (ATSP) in an interdependence. The required coordination in order to resolve the impact caused by interdependencies of several planning is address as the core problem in this work. Since the individual planning processes do not consider the optimality of the planning of the respective other planning problem, there arise potentially in terms of the overall system and its objective function from the optimum material deviated solutions, although the isolated solutions of partial problems are optimally possibly. The coordination problem is exacerbated by the asymmetric distribution of information through the supply chain. From the perspective of the supply chain, this has the consequence that the service providers must be closely integrated as autonomous actors throughout all levels of the supply chain. In this context of the contractual relationship between the service providers with potentially different interests the coordination problem is extended to the coordination effort between the potentially autonomous providers. This decentralized decision situation must therefore be considered in the coordination of planning. Thereby software agents provide a suitable approach to represent autonomous, distributed, decentralized logistics systems. Especially the field of agent-based decentralized coordination for decentralized planning of decentralized plans offers this work a perspective to develop an approach for the coordination problem. Specifically, the agent-based coordination approach of the generalized partial global planning (GPGP) is used for the planning and coordination tasks, in which both the process of planning as well as the result of planning is distributed. Based on this method, a coordination approach along the interaction protocol engineering process model is developed. The result represents a coordination protocol. The evaluation is performed using the method of simulation as part of a multi-agent simulation. The simulation model is a reduced version of the construction site scenario. The aim of the simulation is to show that the presented multi-agent system and developed coordination protocol (1) are suitable for the optimization of the interdependent planning problems and (2) showing a sound system behaviour.