An Integrated Inventory-Transportation System with Periodic Pick-Ups and Leveled Replenishment

In this paper we develop a combined inventory-transportation system. The general idea is to integrate a simple replenishment policy with a routing component to derive operationally consistent standard routes as a basis for milk run design. The most interesting feature of the approach is that we combine stochastic vehicle routing with a replenishment policy which makes use of inventory to level the variability propagated into transportation operations. To evaluate the approach, we compare its performance with stochastic vehicle routing as well as sequential vehicle routing and replenishment planning. With respect to these approaches, substantial gains are achieved

Midlatitude Oceanic Fronts Strengthen the Hydrological Cycle Between Cyclones and Anticyclones

The Kuroshio-Oyashio Extension and Gulf Stream oceanic frontal zones are characterized by enhanced activity of synoptic-scale cyclones and anticyclones and vigorous air-sea heat and moisture exchange in the cold season. However, the time-mean air-sea exchange attributed separately to cyclones and anticyclones has not been assessed. Here we quantify cyclonic and anticyclonic contributions around the frontal zones to surface turbulent heat fluxes, precipitation, and the associated hydrological cycle using atmospheric general circulation model experiments with observed and artificially smoothed sea-surface temperature gradients. The evaluation reveals that precipitation exceeds evaporation climatologically within cyclonic domains while evaporation dominates within anticyclonic domains. These features as well as the net moisture transport from anticyclonic to cyclonic domains are all enhanced by the sharpness of the frontal zones. Oceanic frontal zones thus climatologically act to strengthen the hydrological cycle. These findings aid our understanding of the relationship between midlatitude air-sea interactions on synoptic- and longer-time scales.publishedVersio

The continuum hypothesis : independence and truth-value

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Philosophy, 1974.MIT Humanities Library copy: issued in two vols.Leaf number 84 used twice. Also issued as a two-volume set.Includes bibliographical references (leaves 217-258).by Thomas S. Weston.Ph.D

A System Dynamics Model of the Air Transport System

In this report, we give a complete algebraic description of a system dynamics model of the air transport system, developed to assess the impact of different policies on the adoption rate of fully electric aircraft until the year 2050. Our model consists of the interaction between three major segments, namely air travel demand, airline industry and aircraft manufacturers. This model was used in the paper “How much can electric aircraft contribute to reaching the Flightpath 2050 CO2 emissions goal? A system dynamics approach for European short haul flights” for the computational results therein

Информационные технологии в управлении интеллектуальным капиталом организации

The report examines how organization can use information technologies for management of intellectual capital

Sustainability Assessment and Engineering of Emerging Aircraft Technologies: Challenges, Methods and Tools

Driven by concerns regarding the sustainability of aviation and the continued growth of air traffic, increasing interest is given to emerging aircraft technologies. Although new technologies, such as battery-electric propulsion systems, have the potential to minimise in-flight emissions and noise, environmental burdens are possibly shifted to other stages of the aircraft’s life cycle, and new socio-economic challenges may arise. Therefore, a life-cycle-oriented sustainability assessment is required to identify these hotspots and problem shifts and to derive recommendations for action for aircraft development at an early stage. This paper proposes a framework for the modelling and assessment of future aircraft technologies and provides an overview of the challenges and available methods and tools in this field. A structured search and screening process is used to determine which aspects of the proposed framework are already addressed in the scientific literature and in which areas research is still needed. For this purpose, a total of 66 related articles are identified and systematically analysed. Firstly, an overview of statistics of papers dealing with life-cycle-oriented analysis of conventional and emerging aircraft propulsion systems is given, classifying them according to the technologies considered, the sustainability dimensions and indicators investigated, and the assessment methods applied. Secondly, a detailed analysis of the articles is conducted to derive answers to the defined research questions. It illustrates that the assessment of environmental aspects of alternative fuels is a dominating research theme, while novel approaches that integrate socio-economic aspects and broaden the scope to battery-powered, fuel-cell-based, or hybrid-electric aircraft are emerging. It also provides insights by what extent future aviation technologies can contribute to more sustainable and energy-efficient aviation. The findings underline the need to harmonise existing methods into an integrated modelling and assessment approach that considers the specifics of upcoming technological developments in aviation

Iterative optimization-based simulation in practice – simulation of the surface finishing at Salzgitter Flachstahl GmbH

The Salzgitter Flachstahl GmbH plans a shift in their production program, which might require adaptions in the logistics. A discrete event simulation model is used to evaluate the impact of the new production program on logistics and the effects of various adaptations. In practice, however, optimization algorithms are applied in this system to facilitate resource planning, e.g., for loading train wagons or crane scheduling. To develop a valid production system model, it was necessary to implement optimization algorithms directly within the simulation and execute them iteratively during the simulation run. Using this approach, different adaptions of the logistic system could be evaluated. The approach to implementing iterative optimization-based simulation in practice and the lessons learned are reported

Green batteries for clean skies: Sustainability assessment of lithium‐sulfur all‐solid‐state batteries for electric aircraft

The use of novel battery technologies in short-haul electric aircraft can support the aviation sector in achieving its goals for a sustainable development. However, the production of the batteries is often associated with adverse environmental and socio-economic impacts, potentially leading to burden shifting. Therefore, this paper investigates alternative technologies for lithium–sulfur all-solid-state batteries (LiS-ASSBs) in terms of their contribution to the sustainable development goals (SDGs). We propose a new approach that builds on life cycle sustainability assessment and links the relevant impact categories to the related SDGs. The approach is applied to analyze four LiS-ASSB configurations with different solid electrolytes, designed for maximum specific energy using an electrochemical model. They are compared to a lithium–sulfur battery with a liquid electrolyte as a benchmark. The results of our cradle-to-gate analysis reveal that the new LiS-ASSB technologies generally have a positive contribution to SDG achievement. However, the battery configuration with the best technical characteristics is not the most promising in terms of SDG achievement. Especially variations from the technically optimal cathode thickness can improve the SDG contribution. A sensitivity analysis shows that the results are rather robust against the weighting factors within the SDG quantification method