Multilevel decision making for supply chain management

University of Technology Sydney. Faculty of Engineering and Information Technology.Multilevel decision-making techniques aim to handle decentralized decision problems that feature multiple decision entities distributed throughout a hierarchical organization. Decision entities at the upper level and the lower level are respectively termed the leader and the follower. Three challenges have appeared in the current developments in multilevel decision-making: (1) large-scale - multilevel decision problems become large-scale owing to high-dimensional decision variables; (2) uncertainty - uncertain information makes related decision parameters and conditions imprecisely or ambiguously known to decision entities; (3) diversification – multiple decision entities that have a variety of relationships with one another may exist at each decision level. However, existing decision models or solution approaches cannot completely and effectively handle these large-scale, uncertain and diversified multilevel decision problems. To overcome these three challenges, this thesis addresses theoretical techniques for handling three categories of unsolved multilevel decision problems and applies the proposed techniques to deal with real-world problems in supply chain management (SCM). First, the thesis presents a heuristics-based particle swarm optimization (PSO) algorithm for solving large-scale nonlinear bi-level decision problems and then extends the bi-level PSO algorithm to solve tri-level decision problems. Second, based on a commonly used fuzzy number ranking method, the thesis develops a compromise-based PSO algorithm for solving fuzzy nonlinear bi-level decision problems. Third, to handle tri-level decision problems with multiple followers at the middle and bottom levels, the thesis provides different tri-level multi-follower (TLMF) decision models to describe various relationships between multiple followers and develops a TLMF Kth-Best algorithm; moreover, an evaluation method based on fuzzy programming is proposed to assess the satisfaction of decision entities towards the obtained solution. Lastly, these proposed multilevel decision-making techniques are applied to handle decentralized production and inventory operational problems in SCM

An Iterative Scheme for Leverage-based Approximate Aggregation

The current data explosion poses great challenges to the approximate aggregation with an efficiency and accuracy. To address this problem, we propose a novel approach to calculate the aggregation answers with a high accuracy using only a small portion of the data. We introduce leverages to reflect individual differences in the samples from a statistical perspective. Two kinds of estimators, the leverage-based estimator, and the sketch estimator (a "rough picture" of the aggregation answer), are in constraint relations and iteratively improved according to the actual conditions until their difference is below a threshold. Due to the iteration mechanism and the leverages, our approach achieves a high accuracy. Moreover, some features, such as not requiring recording the sampled data and easy to extend to various execution modes (e.g., the online mode), make our approach well suited to deal with big data. Experiments show that our approach has an extraordinary performance, and when compared with the uniform sampling, our approach can achieve high-quality answers with only 1/3 of the same sample size.Comment: 17 pages, 9 figure

Non-governmental organizations’ influence on tackling black carbon in the shipping industry

This paper reviews the achievements of some typical non-governmental organizations (NGOs) in reducing black carbon emissions from shipping which enjoy the consultative status offered by the International Maritime Organization. It discusses the roles of the specific NGOs in dealing with black carbon in the Arctic region from the perspective of global governance to gain insights to guide our involvements in the Arctic affairs and shipping in the region by taking the advantages of NGOs’ influence on the proceedings of international negotiations, our national policy development, the improvement of industrial practices and public perceptions

Gap States Assisted MoO3 Nanobelt Photodetector with Wide Spectrum Response

10.1038/srep04891Scientific Reports

Research on governance of HFO use and carriage on ships in accordance with the Polar Code

In this paper, we discuss the environmental damages caused by the use and carriage of Heavy Fuel Oil (HFO) by ships in Arctic waters. We also review efforts made by major international and regional organizations in governing the use and carriage of HFO by ships in Arctic waters after implementation of the Polar Code, and analyze the obstacles and difficulties that lie ahead. By illustrating the features of the Arctic Council and the International Maritime Organization (IMO), which govern Arctic waters, we examine measures taken by these two organizations in tackling HFO issues. These include: assessing indigenous and local community’s reliance on HFO transportation in the Arctic, developing risk prevention measures for ships operating in Arctic waters, seeking economic alternatives to HFO that contribute to a greener economy, developing a package of HFO governance measures, strengthening cooperation between relevant international and regional organizations that govern HFO to provide suggestions for follow-up discussions on HFOs, and optimize governance by relevant organizations and determine a better global solution to governing the use and carriage of HFO by ships. In addition, we discuss the feasibility of an IMO-imposed HFO ban from the perspective of the Arctic governance to clearly grasp the path of its future development

Accurate Time-segmented Loss Model for SiC MOSFETs in Electro-thermal Multi-Rate Simulation

Compared with silicon (Si) power devices, Silicon carbide (SiC) devices have the advantages of fast switching speed and low on-resistance. However, the effects of non-ideal characteristics of SiC MOSFETs and stray parameters (especially parasitic inductance) on switching losses need to be further evaluated. In this paper, a transient loss model based on SiC MOSFET and SiC Schottky barrier diode (SBD) switching pairs is proposed. The transient process analysis is simplified by time segmentation of the transient process of power switching devices. The electro-thermal simulation calculates the junction temperature and updates the temperature-related parameters with the proposed loss model and the thermal network model. A multi-rate data exchange strategy is proposed to solve the problem of disparity in timescales between circuit simulation and thermal network simulation. The CREE CMF20120D SiC MOSFET device is used for the experimental verification. The experimental results verify the accuracy of the model which provides guidance for the circuit design of SiC MOSFETs. All the parameters of the loss model can be extracted from the datasheet, which is practical in power electronics design

アクティブ制御システムを有する船の運動応答と波エネルギー吸収特性に関する研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学准教授 北澤 大輔, 東京大学教授 鈴木 克幸, 東京大学講師 柴田 和也, 東京大学教授 高木 健, 東京大学教授 古関 隆章University of Tokyo(東京大学

Manipulating Electromagnetic Waves with Zero Index Materials

Zero-index material is a typical metamaterial with an effective zero refractive index, possessing a variety of exotic electromagnetic properties and particular functionalities. We have considered two kinds of zero-index materials with the first one a nearly matched zero index made of magnetic metamaterial and the second one a radially anisotropic zero index. The magnetic metamaterial-based systems are shown to be significant in wavefront engineering and flexibly tunable by an external magnetic field and a temperature field. The radially anisotropic zero-index-based systems can remarkably enhance the omnidirectional isotropic radiation by enclosing a line source and a dielectric particle within a shell configuration. The physical origin lies in that the dielectric particle effectively rescatters the trapped anisotropic higher order modes and converts them into the isotropic 0th order mode radiated outside the system. The case for the system with the loss is then examined and the energy compensation with a gain particle is also demonstrated