1,720,989 research outputs found
Supply chain risk at simultaneous robust perturbations
No full textThe focus of this paper is the risk management of total supply chains by identifying the risk drivers that could appear simultaneously, and the determination of their common denominator to mitigate supply chain risk using the Net Present Value (NPV) approach in Extended Material Requirements Planning (Extended MRP) models. Any risk driver that is likely to disrupt the procurement, production, transportation, warehousing, delivery or financing of a good or service constitutes a realisation of supply chain risk. Risk drivers often appear simultaneously. It is imperative, therefore, that an a priori assessment of the risk drivers that pose risk to the global supply chain is undertaken and that contingency plans are developed at every level to monitor and mitigate these risks, even when they appear simultaneously. To avoid the ruin of a supply chain we must ensure the availability of adequate funds in conjunction with safety stock. Therefore, the risk-mitigation approach pursued in our paper follows from our conviction that money is the stock of purchasing power of any activity cell in a global supply chain that could influence the perturbation of material flows—on many stages simultaneously. In the paper, we provide a method appropriate for preventing the long-term disruption of a supply chain with probability determined in advance. How to assure resilience of a global supply chain is the question which has occupied the World Economic Forum since 2009. The Industry Agendas in Davos expressed the need to develop a risk assessment framework for the end-to-end supply chain which has not been developed yet. The article presents how company owners, regulators, and board members of supply chains can build the risk assessment framework on a similar requirement as that accepted in the insurance industry, capturing knowledge from the Solvency II framework, and embed the constraints in the extended MRP model. Such a quantitative tool can be used to exercise the “stress tests” of the total chain according to assumptions and plans. In the presented methodology, as a novelty first developed here, we show how the perturbation of intensity in production and logistics, simultaneous perturbations in the timing of financial flows, information flows, flows of items and market perturbations can be better evaluated simultaneously through Laplace transforms and the NPV expression which allow for a control of physical and financial flows simultaneously. Our paper follows the Davos 2013 conclusions analysed by Forbes that “To maintain effectiveness, supply chain managers can arrange to share strategic stocks, or to enter into joint supply agreements. They can also pre-arrange ways to access critical stocks”. Therefore risks should be evaluated on the level of the end-to-end supply chain, and not only on the level of the companies involved. The paper suggests that resilience of a chain is measured by the probability that the NPV of the chain will not fall under the critical value determined in advance, and the yearly mathematical reservations are derived
Formulation and evaluation of vinylpyrrolidone/vinylacetate copolymer microspheres with griseofulvin
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Dynamic Multi-Scenario Approach to Robust and Profitable Online Optimization & Optimal Control of Batch Processes
No full textWe propose a novel integrated methodology for taking into account model uncertainty, in the form of uncertain parameters, within a previously published real time dynamic optimization and optimal control strategy. The combined approach, designed for batch processes, is scenario-based and consists of two interacting layers: one, which computes the optimal operating conditions and takes control actions in response to disturbances, and the other, which executes the dynamic scenario updating strategy. The approach is applied to a fed-batch reactor to demonstrate its effectiveness and flexibility
Interactions between flows of human resources in functional regions and flows of inventories in dynamic processes of global supply chains
No full textAccording to the Ageing Report 2015 (EC, 2015), the number of workers in Europe will decline for 20 million by 2060. The question thus arises how this shrinking pool of workers unequally dispersed in the European regions will influence the competitiveness and profitability of global supply chains and location of the production and distribution nodes. Within the human resource market, commuting costs are compensated, thus influencing wage rates and/or land rent, capitalised in the value of residential properties. These aspects influence the total costs of human resources in the activity cells of supply chains and the stream of profit achieved in a chain. The corporation, whose activity cells are located in the local area which is a net importer of human resources, has to pay higher average wages than the corporation, whose facilities are located in the district from which the labour is exported. If higher wages do not cover these differences, they create incentives to commute into other functional regions. The edges of the functional regions are the lines from which human resources are indifferent regarding commuting to a given central place where the activity cell is located or in the competing central place. These indifference curves move as relative wages change. Therefore, those planning the location and intensity of activities in the nodes of a supply chain should consider the influence of the required level of wages, which depends on the spatial dispersion of dwellings of workers. So, the intensity of the flow of items (inventories in the process) and intensity of the inflow of human resources interact in the area in which the activity cell is located and influence the profit of corporations. Therefore, our aim is to present an innovative approach to the integration of the gravity model of spatially dispersed human resources with the supply systems described by extended MRP Theory. Here the dynamics of delineation of functional regions is assumed to respond immediately to the changes in the differences between wages and commuting costs, which is also a novelty of this compound model. In our study, these two analytical models interact and merge in the compact form for studying the profitability of activities under the volatile intensity of the production flows; this represents a new approach to the evaluation of the present value of chain. Our method enables us to evaluate an expected long-term stream of profit. This is an important tool for managers and owners, who might have different options regarding where to place and invest in an activity cell. They can forecast the influences of the localities and wages on the profit stream before deciding to open or to close and to intensify or not their activities in the particular central place of a functional region
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Optimising biomass-based energy supply chains for sustainable mobility
No full textThe identification of alternative and sustainable energy sources has been one of the fundamental research goals of the last two decades and electric cars or biofuel fed vehicles may contribute to tackle this formidable issue. According to this perspective, a multi-echelon supply chain is here investigated considering biomass cultivation, transport, conversion into bioethanol or bioelectricity, distribution and final usage in alternative bifuel (ethanol and petrol) and electric vehicles. Multiperiod and spatially explicit features are introduced in a Mixed Integer Linear Programming modelling framework where economic and environmental objectives are simultaneously taken into account assessing multiple technologies. Results will show the efficacy of the methodology at providing stakeholders with a quantitative tool to optimise the economic and environmental performance of different supply chain configuration
Enabling Sulfur-rich Coal Sources for Gasification without Emissions
No full textNowadays H2S and CO2 are strongly undesired coal gasification by-products. Nonetheless, despite his bad reputation, H2S is quite an interesting chemical since it contains a highly noble species, the hydrogen. Basing on recent advances, it is possible to convert H2S and CO2 into valuable products and specifically into syngas according to the oxi-reduction reaction: 2H2S + CO2 → H2 + CO + S2 + H2O, whenever it takes place into a regenerative thermal reactor and at specific operating conditions. Such a technology allows to enable some energy sources currently still unexploited due to their relevant content in sulfur, such as some crude oils, natural gases, and coal sources. For example, the Sulcis coal in Italy has the 5 to 9%w/w, the Hungarian coal has the 3 to 5%w/w, and the Inner Mongolia-Chinese coal has up to 18% of sulfur content. In the coal gasification process, the sulfur is converted into H2S and COS according to the operating conditions. Looking forward to the use of these sulfur-rich sources of energy, it is of key importance to consider the possible formation of organosulfur compounds such as COS and CS2: H2S + CO2 → COS + H2O, H2S + COS → CS2 + H2O, as they could reduce the effectiveness of the technology and could cause environmental problems. The paper is aimed at studying the coal gasification process including the oxi-reduction reaction and the hydrolysis system in a catalytic reactor of the organosulfur compounds. The target is to demonstrate that higher content in sulfur means lower emissions of CO2 without any additional environmental impact due to organosulfur species. Detailed kinetic and reactor models for coal gasification will be integrated in process simulation packages. Prior studies on the hydrolysis of organosulfur compounds will be also integrated in the simulation
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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