A Petri Nets-based Scheduling Methodology forMultipurpose Batch Plants.

This article presents an optimization methodology of batch production processes assembled by shared resources which rely on a mapping of state-events into time-events allowing in this way the straightforward use of a well consolidated scheduling policies developed for manufacturing systems. A technique to generate the timed Petri net representation from a continuous dynamic representation (Differential-Algebraic Equations systems (DAEs)) of the production system is presented together with the main characteristics of a Petri nets-based tool implemented for optimization purposes. This paper describes also how the implemented tool generates the coverability tree and how it can be pruned by a general purpose heuristic. An example of a distillation process with two shared batch resources is used to illustrate the optimization methodology proposed

Literature review on thin-walled and cellular structure designs for energy absorption

Bio-inspired structure is a topic of immense interest to researchers worldwide. In order to maximize energy absorption through biomimetic structures, this article presents bio-inspired structure particularly, thin walled and cellular structures thorough analysis of the interactions between experimental research and Finite Element Analysis (FEA) simulations. The study compiles the prior research on experimental investigations of thin-walled and cellular biomimetic structures in order to understand the significance of biomimetic structural energy absorption. These inventive works of nature serve as inspiration for these designs, which provide engineering solutions that excel in impact resistance and energy dissipation abilities. The study further highlights the mutual advantages of combining experimental research with FEA models, which enable a deeper understanding of the impact response and energy absorption mechanisms inherent in biomimetic structures, by exploring into recent developments in material science and design methodologies. The article emphasizes how important validations are in bringing experimental results in line with FEA predictions. Furthermore, the practical applications demonstrated in fields like aircraft engineering, automotive safety, and protections can serve as excellent examples of the paradigm-shifting potential of this method for boosting impact protection. This review proposes novel research avenues aimed at fully harnessing the potential of biomimetic architectures to enhance energy absorption, all while acknowledging and addressing the associated challenges.publishedVersio

Vertical integration and firm boundaries : the evidence

Since Ronald H. Coase's (1937) seminal paper, a rich set of theories has been developed that deal with firm boundaries in vertical or input–output structures. In the last twenty-five years, empirical evidence that can shed light on those theories also has been accumulating. We review the findings of empirical studies that have addressed two main interrelated questions: First, what types of transactions are best brought within the firm and, second, what are the consequences of vertical integration decisions for economic outcomes such as prices, quantities, investment, and profits. Throughout, we highlight areas of potential cross-fertilization and promising areas for future work

Education and Training in a Model of Endogenous Growth with Creative Destruction

By formulating an endogenous growth model that combines elements from Romer (1990), Aghion and Howitt (1992), and van Zon and Yetkiner (2003), the present paper studies the contribution of education and training on economic growth through their impact on the rate of innovation. The article addresses two main issues. The first is the optimum provision of on-the-job training necessary to be able to adopt, and adapt to new technologies. The second is the impact of both formal education and on-the-job training on the innovative capacity of an economic system that is the ultimate cause of output growth. In our set-up, education enhances R&D activities and lowers adjustment costs to new technologies, thus facilitating their adoption, while on the other hand on-the-job training ensures the possibility to implement the new coming technologies and reap all the related future profits. We assume that the adoption of a new technology consists of two periods, i.e. the training phase during which newly hired workers acquire the right amount of know how in order to become familiar with the specific new technology, and the implementation or production phase in which profit flows arise for firms and in which the cost savings that can be realized arise from productivity increases in the previous phase. By extending the training phase, entrepreneurs run a greater risk of shortening the production phase for a given arrival rate of new technologies that progressively erode the profit flows obtained from existing technologies. The paper shows first that it is possible to find a profit-maximizing, endogenously determined, amount of training that depends on the workers’ educational attainment. Thus, a situation in which better educated workers may be disproportionately selected for training issues is possible, especially in times of rapid technological change. However, the paper also shows that a non-linear relationship between education and technological change (and growth) exists, so that an increase in the formal level of education can even result in a reduction in the rate of growth. The reason for this is the increase in creative destruction that raises ‘technology adoption costs’ in terms of output foregone during re-training spells that arrive at a faster rate. The results offer some insights that are interesting from an education policy perspective.labour economics ;

Economic and environmental impacts of the energy source for the utility production system in the HDA process

The well-known benchmark process for hydrodealkylation of toluene (HDA) to produce benzene is revisited in a multi-objective approach for identifying environmentally friendly and cost-effective operation solutions. The paper begins with the presentation of the numerical tools used in this work, i.e., a multi-objective genetic algorithm and a Multiple Choice Decision Making procedure. Then, two studies related to the energy source involved in the utility production system (UPS), either fuel oil or natural gas, of the HDA process are carried out. In each case, a multi-objective optimization problem based on the minimization of the total annual cost of the process and of five environmental burdens, that are Global Warming Potential, Acidification Potential, Photochemical Ozone Creation Potential, Human Toxicity Potential and Eutrophication Potential, is solved and the best solution is identified by use of Multiple Choice Decision Making procedures. An assessment of the respective contribution of the HDA process and the UPS towards environmental impacts on the one hand, and of the environmental impacts generated by the main equipment items of the HDA process on the other hand is then performed to compare both solutions. This ‘‘gate-to-gate’’ environmental study is then enlarged by implementing a ‘‘cradle-togate’’ Life Cycle Assessment (LCA), for accounting of emission inventory and extraction. The use of a natural gas turbine, less economically efficient, turns out to be a more attractive alternative to meet the societal expectations concerning environment preservation and sustainable development

Societal Effects and the Transfer of Business Practices to Britain and France

This paper seeks to reconcile the notion of a 'societal effect' in business organisation with the considerable evidence that competitive pressures continuously lead national producers to emulate the business practices of other nations, which are perceived as providing a basis for superior economic performance. The paper identifies three sources of national specificity in the process of emulation giving rise to 'hybrid' models. First, the fact that a nation's manufacturers have a distinctive knowledge base means that adopting another nation's methods will depend on local learning involving trial and error. The more 'distant' the emulated technology is from the local one, the less likely it is that this learning process will result in an exact replica of the parent model. Second, when there are strong interdependencies between a nation's production methods and its systems of vocational training, there will be strong pressure to adopt new methods in ways that are compatible with existing career structures. Third, the fact each nation has a particular industrial relations legacy involving varying levels of trust between labour and management, means that new practices will be introduced through a distinctive process of negotiation and compromise giving rise to national specific effects.knowledge, learning processes, national specificity

Factors influencing employee perceptions in lean transformations

The purpose of the study was to investigate employee perceptions during a lean transformation1. The combination of case study and survey methodologies was used to define elements influencing the perceived lean success of shop floor employees. According to our findings, belief, commitment, work method and communication all have a considerable direct impact on workers’ perceptions of lean success. However, their effects are very different based on the scope and focus of changes that is influenced by process characteristics. Perceptions regarding successful lean transformation during a moderate reorganisation of the company’s welding plant, where mainly males work, are affected only by commitment and work method, whereas the deep reorganisation of the sewing plant (populated by female employees) is only influenced by belief and communication

Productivity and the Services of Capital and Labor

macroeconomics, productivity, labor

Tricks and trucks: Ten years of organizational renewal at DAF?

Organizational Change;Lean Production;DAF;production