Mobile phone data in transportation research: methods for benchmarking against other data sources

The ubiquity of personal cellular phones in society has led to a surging interest in using Big Data generated by mobile phones in transport research. Studies have suggested that the vast amount of data could be used to estimate origin–destination (OD) matrices, thereby potentially replacing traditional data sources such as travel surveys. However, constructing OD matrices from mobile phone data (MPD) entails multiple challenges, and the lack of ground truth hampers the evaluation and validation of the estimated matrices. Furthermore, national laws may prohibit the distribution of MPD for research purposes, compelling researchers to work with pre-compiled OD matrices with no insight into the methods used. In this paper, we analyse a set of such pre-compiled OD matrices from the greater Oslo area and perform validation procedures against several sources to assess the quality and robustness of the OD matrices as well as their usefulness in transportation planning applications. We find that while the OD matrices correlate well with other sources at a low resolution, the reliability decreases when a finer level of detail is chosen, particularly when comparing shorter trips between neighbouring areas. Our results suggest that coarseness of data and privacy concerns restrict the usefulness of MPD in transport research in the case where OD matrices are pre-compiled by the operator.

     

大直径盾构隧道穿越建筑物群变形分析与控制措施北大核心CSCD

大直径盾构隧道掘进施工对土体造成扰动,导致地表产生沉降或隆起,继而严重威胁上部建筑物群的结构安全。文章依托某大直径盾构隧道穿越老旧小区密集建筑物群工程,首先利用二维有限元软件计算关键断面房屋的沉降变形,再对比三维有限元软件的计算结果,分析两种计算方法的适用范围;然后基于三维模型探究了不同初期荷载释放率对盾构穿越引起的地表和房屋变形的影响,最后利用Peck公式计算的理论地表沉降数据,梳理初期荷载释放率、地表沉降、地层损失率三者的内部联系并提出了控制变形的相关措施。研究结果表明,初期荷载释放率越小,地表及房屋沉降也越小,对应的地层损失也越小;对于控制地表变形,减小荷载释放率等同于减小地层损失率;初期荷载释放率、地表沉降、地层损失率这三者减小的量值呈线性关系。     

Simulating the household plug-in hybrid electric vehicle distribution and its electric distribution network impacts

This paper presents a multi agent-based simulation framework for modeling spatial distribution of plug-in hybrid electric vehicle ownership at local residential level, discovering “plug-in hybrid electric vehicle hot zones” where ownership may quickly increase in the near future, and estimating the impacts of the increasing plug-in hybrid electric vehicle ownership on the local electric distribution network with different charging strategies. We use Knox County, Tennessee as a case study to highlight the simulation results of the agent-based simulation framework.     

Making public policy through citizen committees: Case histories from the Islands

Abstract

Citizen committees properly designed can strongly influence public policy. Examples are taken from the results of reports on marine affairs that citizen committees wrote in Hawaii, the U.S. Virgin Islands and Puerto Rico. Community acceptance and use of each report came about because (1) many members of the committees were in positions to act on the recommendations, (2) the recommendations were specific and called for actions other than studies, and (3) the governor of each area had asked that a report be drawn. To ensure attention to the reports, each governor had agreed that they would be uncensored, widely publicized, and released concurrently to the public and the government.     

A complex network perspective for characterizing urban travel demand patterns: graph theoretical analysis of large-scale origin–destination demand networks

Urban travel demand, consisting of thousands or millions of origin–destination trips, can be viewed as a large-scale weighted directed graph. The paper applies a complex network-motivated approach to understand and characterize urban travel demand patterns through analysis of statistical properties of origin–destination demand networks. We compare selected network characteristics of travel demand patterns in two cities, presenting a comparative network-theoretic analysis of Chicago and Melbourne. The proposed approach develops an interdisciplinary and quantitative framework to understand mobility characteristics in urban areas. The paper explores statistical properties of the complex weighted network of urban trips of the selected cities. We show that travel demand networks exhibit similar properties despite their differences in topography and urban structure. Results provide a quantitative characterization of the network structure of origin–destination demand in cities, suggesting that the underlying dynamical processes in travel demand networks are similar and evolved by the distribution of activities and interaction between places in cities.     

Application of fuel-saving strategies onboard high-speed passenger ships

Strategies of fuel consumption onboard ships are of one of the crucial issues in marine shipping industry. Many of the relevant authorities maritime domain gave great interesting to that issue, either through research that discussed the impact of marine fuel consumption on the environment and economy of ships or through practical experiments’ that are made by marine engine manufacturers. Over the years, many solutions have been put forward to overcome this problem while maintaining the amount of goods transported globally at the same transfer rate and ship speed. The present paper sheds light on many of the methods used currently to reach this purpose. It is explained that applying a certain fuel-saving strategy will rely on some of the factors, especially the type of ship. Mainly two methods including: shore-side power and cold out of heat strategies have been investigated regarding adaption, economic, and environmental issues in case of applying onboard high-speed passenger ships.     

Design of ferrite magnet CFSM to improve speed response of EPS system

This paper deals with the speed response characteristic of the concentrated flux synchronous motor (CFSM) using ferrite magnets for the electric power steering (EPS) system. To analyze the response characteristic of the CFSM, an analytical method using the electromechanical undamped natural frequency and damping ratio based on the transfer function is proposed. By using the method, the speed response according to the variations of the shape of the permanent magnets (PMs) and rotor core is analyzed. It was analyzed under the conditions of the constant volume of the PMs as well as the constant diameter of the rotor. By using the proposed analysis method, the improved model is desgined based on the initial model fulfilling the required specifications. Finally, the torque and speed response characteristics of two motors are simulated through the finite element analysis (FEA) and MATLAB Simulink.     

The Decline of the Artisanal Fisheries in Mediterranean Coastal Areas: The Case of Cap de Creus (Cape Creus)

This article examines the sociocultural, economic, and environmental causes of the decline of the artisanal fisheries in the rocky coast of Cape Creus (NW Mediterranean) over the past decades. The changes that have occurred over time have favored trawlers, purse-seiners, shellfish fisheries, and tourism activities, to the detriment of artisanal fisheries. This article shows that the establishment of a marine reserve in 1998 could not reverse the observed decline in the artisanal fisheries. This raises the necessity of implementing a fishery management plan integrated into a coastal management plan, which should accompany the habitat protection. These plans could assist in the maintenance and the sustainable development of the artisanal fishing sector in Cape Creus as well as in other Mediterranean coastal areas where artisanal fisheries are also declining.     

Democratization of Coastal Zone Decision Making for Indigenous Australians: Insights from Stakeholder Analysis

Community participation has become something of an orthodoxy within natural resource management. In the absence of an explicit strategy for democratization and capacity-building the notion of community participation is potentially meaningless and its application likely to mask decisions made in the interests of elite groups. This article examines the shortcomings of participatory processes in coastal resource management and seeks to identify and overcome constraints to democratization and capacity-building for Indigenous Australians. Using two coastal catchments in Central Queensland as a case study, we explore relations of power among stakeholders using Stakeholder Analysis to provide a platform for more effective deliberative participation by this group of stakeholders. Discussion of the specific barriers to participation identified by Aboriginal stakeholders will demonstrate the need to adopt notions of capacity-building that focus not only on the attributes of the individual stakeholder that might facilitate their participation, but on the characteristics also of the decision-making environment.     

On-board aging estimation using half-cell voltage curves for LiFePO<Subscript>4</Subscript> cathode-based lithium-ion batteries for EV applications

The aim of this work is the design of an algorithm for on-board determination of the actual capacity of a lithium iron phosphate (LFP) cathode-based lithium-ion battery for electric vehicle applications. The presented approach is based on the detection of the predominant aging mechanisms (in terms of loss of lithium and loss of active material in both electrodes) by determining the single electrode voltage curves. The information related to the characteristic length and position of the voltage plateaus, which can be gathered during battery operation, can be used to obtain the actual aging state of the cells. The length of the plateaus depends on the respective position that the voltage curves of the single electrodes have in relation to each other. Relating the change of the plateau characteristics to the possible aging mechanisms allows the determination of the actual battery aging state in terms of total cell capacity. The work presents a possible implementation of an algorithm for capacity determination based on the described methodology. The algorithm is validated with various differently aged LFP cells. Furthermore, the work discusses the ability of the method to detect the actual battery capacity if the characteristics of only part of the quasi-OCV (open circuit voltage) curve are detected. Achieved accuracy and existing limitations are described and discussed in detail.