Greening Supply Chains: Impact on Cost and Design

The consideration of environmental issues has emerged as a topic of critical importance for today’s globalized supply chains. The purpose of this paper is to develop a strategic-tactical decision-support methodology to assist managers in evaluating the impact of environmental issues, related to transportation emissions, on the transport geography of a region. Specifically we provide a tool that addresses: (i) supply chain network design, including port of entry and transportation mode, and (ii) decisions on leasing vs. outsourcing of transportation and distribution centers. The applicability of the proposed methodology is examined through the development of a sustainable supply chain network in the South-Eastern Europe region. The results indicate that in most cases outsourcing distribution centers to Third Party Logistics operators improves both the cost and the environmental performance of a company. In all cases outsourcing of transportation operations minimizes the amount of CO2 and PM emissions generated, while leasing minimizes costs.carbon footprint;supply chain design;supply chain sustainability

Inventory control of spare parts using a Bayesian approach: a case study

This paper presents a case study of applying a Bayesian approach to forecast demand and subsequently determine the appropriate parameter S of an (S-1,S) inventory system for controlling spare parts of electronic equipment. First, the problem and the current policy are described. Then, the basic elements of the Bayesian approach are introduced and the procedure for calculating the appropriate parameter S is illustrated. Finally, we present the results of applying the Bayesian approach in an innovative way to determine the stock levels of three types of circuit packs at several locations. According to the proposed method, a lower base stock than the one currently used is sufficient to achieve the desired service level.inventory control;spare parts;case study;Bayesian analysis

Self-organization of hydrophobic soil and granular surfaces

Soil can become extremely water repellent following forest fires or oil spillages, thus preventing penetration of water and increasing runoff and soil erosion. Here the authors show that evaporation of a droplet from the surface of a hydrophobic granular material can be an active process, lifting, self-coating, and selectively concentrating small solid grains. Droplet evaporation leads to the formation of temporary liquid marbles and, as droplet volume reduces, particles of different wettabilities compete for water-air interfacial surface area. This can result in a sorting effect with self-organization of a mixed hydrophobic-hydrophilic aggregate into a hydrophobic shell surrounding a hydrophilic core

Investigation of ultrafast laser photonic material interactions: challenges for directly written glass photonics

Currently, direct-write waveguide fabrication is probably the most widely studied application of femtosecond laser micromachining in transparent dielectrics. Devices such as buried waveguides, power splitters, couplers, gratings and optical amplifiers have all been demonstrated. Waveguide properties depend critically on the sample material properties and writing laser characteristics. In this paper we discuss the challenges facing researchers using the femtosecond laser direct-write technique with specific emphasis being placed on the suitability of fused silica and phosphate glass as device hosts for different applications.Comment: 11 pages, 87 references, 11 figures. Article in revie

Tactical/Operational Decision Making for Designing Green Logistics Networks

Cap and trade regulations along with an increasing consumer and company demand for green products and services constitute two major drivers for motivating corporations to adopt green practices. However, the adoption of such practices usually increases their operational costs. Therefore, the trade-off between “green” and cost-optimal policies is a common challenge for most organizations, at least in developed countries. The purpose of this paper is to assess alternative logistic network design options (applicable in most supply chains) taking into account both their cost and CO2 emissions performance. The applicability of the proposed methodology is illustrated through the design of a major white good retailer’s logistics network in the region of Greece. The results indicate that a company optimizes its cost performance by serving all its retail stores directly by truck through one central distribution center. On the other hand, a CO2 emissions optimal performance includes additional distribution centers and the employment of rail instead of truck transportation. Moreover, longer review periods, despite the higher holding and backorder costs, result in lower transportation costs and CO2 emissions

Greening Supply Chains: Impact on Cost and Design

The consideration of environmental issues has emerged as a topic of critical importance for today’s globalized supply chains. The purpose of this paper is to develop a strategic-tactical decision-support methodology to assist managers in evaluating the impact of environmental issues, related to transportation emissions, on the transport geography of a region. Specifically we provide a tool that addresses: (i) supply chain network design, including port of entry and transportation mode, and (ii) decisions on leasing vs. outsourcing of transportation and distribution centers. The applicability of the proposed methodology is examined through the development of a sustainable supply chain network in the South-Eastern Europe region. The results indicate that in most cases outsourcing distribution centers to Third Party Logistics operators improves both the cost and the environmental performance of a company. In all cases outsourcing of transportation operations minimizes the amount of CO2 and PM emissions generated, while leasing minimizes costs

Operations Research for Green Logistics – An Overview of Aspects, Issues, Contributions and Challenges

The worldwide economic growth of the last century has given rise to a vast consumption of goods while globalization has led to large streams of goods all over the world. The production, transportation, storage and consumption of all these goods, however, have created large environmental problems. Today, global warming, created by large scale emissions of greenhouse gasses, is a top environmental concern. Governments, action groups and companies are asking for measures to counter this threat. Operations research has a long tradition in improving operations and especially in reducing costs. In this paper, we present a review that highlights the contribution of operations research to green logistics, which involves the integration of environmental aspects in logistics. We give a sketch of the present and possible developments, focussing on design, planning and control in a supply chain for transportation, inventory of products and facility decisions. While doing this, we also indicate several areas where environmental aspects could be included in OR models for logistics

Spectroscopy of Young Planetary Mass Candidates with Disks

It is now well established that many young brown dwarfs exhibit characteristics similar to classical T Tauri stars, including infrared excess from disks and emission lines related to accretion. Whether the same holds true for even lower mass objects, namely those near and below the Deuterium-burning limit, is an important question. Here we present optical spectra of six isolated planetary mass candidates in Chamaeleon II, Lupus I and Ophiuchus star-forming regions, recently identified by Allers and collaborators to harbor substantial mid-infrared excesses. Our spectra, from ESO's Very Large Telescope and New Technology Telescope, show that four of the targets have spectral types in the ~M9-L1 range, and three of those also exhibit H_alpha. Their luminosities are consistent with masses of ~5-15 M_{Jupiter} according to models of Chabrier, Baraffe and co-workers, thus placing these four objects among the lowest mass brown dwarfs known to be surrounded by circum-sub-stellar disks. Our findings bolster the idea that free-floating planetary mass objects could have infancies remarkably similar to those of Sun-like stars and suggest the intriguing possibility of planet formation around primaries whose masses are comparable to those of extra-solar giant planets. Another target appears to be a brown dwarf (~M8) with prominent H_alpha emission, possibly arising from accretion. The sixth candidate is likely a background source, underlining the need for spectroscopic confirmation.Comment: to appear in The Astrophysical Journal Letter