Design of a network of reusable logistic containers

In this paper, we consider the management of the return flows of empty logistic containers that accumulate at the customer’s sites. These containers must be brought back to the factories in order to sustain future expeditions. We consider a network composed of several factories and several customers in which the return flows are independent of the delivery flows. The models and their solutions aim at finding to which factory the contain- ers have to be brought back and at which frequency. These frequencies directly define the volume of logistic containers to hold in the network. We consider fixed transportation costs depending on the locations of the customers and of the factories and linear holding costs for the inventory of logistic containers. The analysis also provides insight on the benefit of pooling the containers among different customers and/or factories.supply chain management, returnable items, reverse logistic, economic order quantity, network design

A tight bound on the throughput of queueing networks with blocking

In this paper, we present a bounding methodology that allows to compute a tight lower bound on the cycle time of fork--join queueing networks with blocking and with general service time distributions. The methodology relies on two ideas. First, probability masses fitting (PMF) discretizes the service time distributions so that the evolution of the modified network can be modelled by a Markov chain. The PMF discretization is simple: the probability masses on regular intervals are computed and aggregated on a single value in the orresponding interval. Second, we take advantage of the concept of critical path, i.e. the sequence of jobs that covers a sample run. We show that the critical path can be computed with the discretized distributions and that the same sequence of jobs offers a lower bound on the original cycle time. The tightness of the bound is shown on computational experiments. Finally, we discuss the extension to split--and--merge networks and approximate estimations of the cycle time.queueing networks, blocking, throughput, bound, probability masses fitting, critical path.

Probability masses fitting in the analysis of manufacturing flow lines

A new alternative in the analysis of manufacturing systems with finite buffers is presented. We propose and study a new approach in order to build tractable phase-type distributions, which are required by state-of-the-art analytical models. Called "probability masses fitting" (PMF), the approach is quite simple: the probability masses on regular intervals are computed and aggregated on a single value in the corresponding interval, leading to a discrete distribution. PMF shows some interesting properties: it is bounding, monotonic and it conserves the shape of the distribution. After PMF, from the discrete phase-type distributions, state-of-the-art analytical models can be applied. Here, we choose the exactly model the evolution of the system by a Markov chain, and we focus on flow lines. The properties of the global modelling method can be discovered by extending the PMF properties, mainly leading to bounds on the throughput. Finally, the method is shown, by numerical experiments, to compute accurate estimations of the throughput and of various performance measures, reaching accuracy levels of a few tenths of percent.stochastic modelling, flow lines, probability masses fitting, discretization, bounds, performance measures, distributions.

KNOWLEDGE SHARING BEHAVIOR GURU DITINJAU DARI TRANSFORMATIONAL LEADERSHIP DAN SELF-EFFICACY [TEACHERS’ KNOWLEDGE SHARING BEHAVIOR FROM TRANSFORMATIONAL LEADERSHIP AND SELF-EFFICACY’S PERSPECTIVE]

The changing context of the age and the characteristics of today's generation demand that the role of the teacher be more creative and innovative. A way to answer this need is to cultivate a knowledge sharing behavior in the school environment. There are many factors that can support the establishment of this knowledge sharing behavior, including transformational leadership and self-efficacy. This study aims to determine the effect of transformational leadership and self-efficacy on the knowledge sharing behavior of teachers. The research subjects were 112 teachers who teach in two locations of XYZ Private High School in West Jakarta which have the potential to develop knowledge sharing behavior. The design used in this study was correlational, using surveys to collect the data and then analyze using the PLS-SEM method. The results of this study showed that transformational leadership and self-efficacy affected knowledge sharing behavior positively.BAHASA INDONESIA ABSTRAK: Perubahan konteks zaman dan karakteristik generasi zaman sekarang menuntut peran guru yang semakin kreatif dan inovatif. Salah satu upaya untuk menjawab hal ini adalah dengan membudayakan perilaku knowledge sharing behavior di lingkungan sekolah. Ada banyak faktor yang dapat mendukung terbangunnya perilaku knowledge sharing behavior ini, di antaranya transformational leadership dan self-efficacy. Penelitian ini bertujuan untuk mengetahui pengaruh transformational leadership dan self-efficacy terhadap knowledge sharing behavior guru. Subjek penelitian adalah 112 guru yang mengajar di dua lokasi Sekolah Menengah Atas Swasta XYZ di Jakarta Barat yang memiliki potensi untuk membangun perilaku knowledge sharing behavior. Desain penelitian bersifat korelational, data diambil berdasarkan survey yang dianalisi dengan metode PLS-SEM. Hasil penelitian yang diperoleh memperlihatkan bahwa transformational leadership dan self-efficacy mempengaruhi knowledge sharing behavior secara positif

Bertrand Méheust, 2009, La Politique de l’oxymore. Comment ceux qui nous gouvernent nous masquent la réalité du monde, La Découverte, 161 p.

Avec La Politique de l’oxymore, le philosophe Bertrand Méheust a signé un excellent essai, qui aurait tout aussi bien pu s’intituler La Saturation du monde. Moins accrocheur, moins communicatif, ce titre aurait cependant davantage souligné ce qui fait la stimulante originalité de la démarche choisie et de la thèse défendue. L’idée selon laquelle la gravité de la crise écologique globale – pour ne pas dire de l’effondrement écologique global – est sans cesse euphémisée par des oxymores n’est p..