scholarly journals A Courier Service with Electric Bicycles in an Urban Area: The Case in Seoul

2019 ◽  
Vol 11 (5) ◽  
pp. 1255 ◽  
Author(s):  
Keyju Lee ◽  
Junjae Chae ◽  
Jinwoo Kim
Keyword(s):  
Urban Area ◽  
Carbon Emissions ◽  
Operating Costs ◽  
Fossil Fuel Combustion ◽  
Routing Problem ◽  
The Past ◽  
Courier Service ◽  
Mode Of Transportation ◽  
Electric Bicycles ◽  
Actual Size

Various factors must be considered when running a courier service in an urban area, because the infrastructure of a city differs from those in suburban or countryside areas. Of note, population density is higher, and vehicles encounter greater restrictions. Moreover, air pollution from fossil fuel combustion is more severe. As tailpipe emissions are becoming costly to both corporations and the environment, researchers are increasingly exploring more appealing transportation options. Electric bicycles have become an important mode of transportation in some countries in the past decade. Electric bicycles and automobiles have their respective merits and demerits when used to provide courier services. E-bikes in particular can ply their trade in densely packed areas that are off-limits to cars and trucks. This paper focuses on (1) developing a truck–bike mixture model to reduce operating costs for an existing truck-only service by replacing some of the trucks with bicycles, and (2) exploring the resulting effects in terms of reducing overall carbon emissions. Data from one of the major courier companies in South Korea were utilized. The problem was tackled as a heterogeneous fleet vehicle routing problem using simulated annealing because the actual size of the problem cannot be solved directly with a mathematical approach. The most effective fleet mix was found for the company’s case. Effects on operating costs and reduced emissions were analyzed for 15 different scenarios with varying demands and off-limits areas. Computational results revealed that the new model is viable from economic and sustainability standpoints. They indicated that costs decrease to varying degrees in all scenarios, and that carbon emissions also decrease by around 10% regardless of the selected scenario.

scholarly journals A review on the electric vehicle routing problems: Variants and algorithms

2021 ◽  
Author(s):  
Hu Qin ◽  
Xinxin Su ◽  
Teng Ren ◽  
Zhixing Luo
Keyword(s):  
Vehicle Routing ◽  
Vehicle Routing Problems ◽  
Location Routing Problem ◽  
Routing Problems ◽  
Routing Problem ◽  
Delivery Problem ◽  
Pickup And Delivery Problem ◽  
The Past ◽  
Location Routing ◽  
Comprehensive Survey

AbstractOver the past decade, electric vehicles (EVs) have been considered in a growing number of models and methods for vehicle routing problems (VRPs). This study presents a comprehensive survey of EV routing problems and their many variants. We only consider the problems in which each vehicle may visit multiple vertices and be recharged during the trip. The related literature can be roughly divided into nine classes: Electric traveling salesman problem, green VRP, electric VRP, mixed electric VRP, electric location routing problem, hybrid electric VRP, electric dial-a-ride problem, electric two-echelon VRP, and electric pickup and delivery problem. For each of these nine classes, we focus on reviewing the settings of problem variants and the algorithms used to obtain their solutions.

The Spatiotemporal Evolution of Urban Impervious Surface for Chengdu, China

2021 ◽  
Vol 87 (7) ◽  
pp. 491-502
Author(s):  
Mujie Li ◽  
Zezhong Zheng ◽  
Mingcang Zhu ◽  
Yue He ◽  
Jun Xia ◽  
...  
Keyword(s):  
Neural Networks ◽  
Growth Rate ◽  
Urban Area ◽  
Landsat Imagery ◽  
Impervious Surface ◽  
Kappa Coefficient ◽  
Spatiotemporal Evolution ◽  
Urban Impervious Surface ◽  
The Past ◽  
Secondary Industry

The spatiotemporal evolution of an impervious surface (IS) is significant for urban planning. In this paper, the IS was extracted and its spatiotemporal evolution for the Chengdu urban area was analyzed based on Landsat imagery. Our experimental results indicated that convolutional neural networks achieved the better performance with an overall accuracy of 98.32%, Kappa coefficient of 0.98, and Macro F1 of 98.28%, and the farmland was replaced by IS from 2001 to 2017, and the IS area (ISA) increased by 51.24 km2; that is, the growth rate was up to 13.8% in sixteen years. According to the landscape metrics, the IS expanded and agglomerated into large patches from small fragmented ones. In addition, the gross domestic product change of the secondary industry was similar to the change of ISA between 2001 and 2017. Thus, the spatiotemporal evolution of IS was associated with the economic development of the Chengdu urban area in the past sixteen years.

A Review of Desiccant Cooling Systems

1993 ◽  
Vol 115 (1) ◽  
pp. 1-8 ◽  
Author(s):  
D. G. Waugaman ◽  
A. Kini ◽  
C. F. Kettleborough
Keyword(s):  
Operating Costs ◽  
Coefficient Of Performance ◽  
Low Grade ◽  
Cooling Systems ◽  
The Past ◽  
Cooling Coils ◽  
Conventional Cooling ◽  
Commercial Applications ◽  
Conventional Systems ◽  
Made In

This paper describes recent published design advances that have been made in desiccant cooling systems. In desiccant cooling cycles, the desiccant reduces the humidity of the air by removing moisture from the air. Then the temperature is reduced by other components such as heat exchangers, evaporative coolers, or conventional cooling coils. The main advantage that desiccant cooling systems offer is the capability of using low-grade thermal energy. Desiccant cooling systems for residential and commercial applications are now being used to reduce energy-operating costs. However, the initial costs are comparatively high. The focus of research for the past decade has been to develop desiccant systems with a high coefficient of performance. Recent studies have emphasized computer modeling and hybrid systems that combine desiccant dehumidifiers with conventional systems.

scholarly journals Understanding Urban Growth in Beijing-Tianjin-Hebei Region over the Past 100 Years Using Old Maps and Landsat Data

2021 ◽  
Vol 13 (16) ◽  
pp. 3264 ◽  
Author(s):  
Shuang Li ◽  
Zhongqiu Sun ◽  
Yafei Wang ◽  
Yuxia Wang
Keyword(s):  
Remote Sensing ◽  
Urban Area ◽  
Spatial Data ◽  
Urban Expansion ◽  
Remote Sensing Images ◽  
The Past ◽  
Old Maps ◽  
The World ◽  
The City

Studying urban expansion from a longer-term perspective is of great significance to obtain an in-depth understanding of the process of urbanization. Remote sensing data are mostly selected to investigate the long-term expansion of cities. In this study, we selected the world-class urban agglomeration of Beijing-Tianjin-Hebei (BTH) as the study area, and then discussed how to make full use of multi-source, multi-category, and multi-temporal spatial data (old maps and remote sensing images) to study long-term urbanization. Through this study, we addressed three questions: (1) How much has the urban area in BTH expanded in the past 100 years? (2) How did the urban area expand in the past century? (3) What factors or important historical events have changed the development of cities with different functions? By comprehensively using urban spatial data, such as old maps and remote sensing images, geo-referencing them, and extracting built-up area information, a long-term series of urban built-up areas in the BTH region can be obtained. Results show the following: (1) There was clear evidence of dramatic urban expansion in this area, and the total built-up area had increased by 55.585 times, from 126.181 km2 to 7013.832 km2. (2) Continuous outward expansion has always been the main trend, while the compactness of the built-up land within the city is constantly decreasing and the complexity of the city boundary is increasing. (3) Cities in BTH were mostly formed through the construction of city walls during the Ming and Qing dynasties, and the expansion process was mostly highly related to important political events, traffic development, and other factors. In summary, the BTH area, similarly to China and most regions of the world, has experienced rapid urbanization and the history of such ancient cities should be further preserved with the combined use of old maps.

scholarly journals Archiving Metaxourgio

2021 ◽  
pp. 167-184
Author(s):  
Thomais Kordonouri
Keyword(s):  
Urban Area ◽  
21St Century ◽  
Ground Level ◽  
The Past ◽  
The Future ◽  
Relationship Of ◽  
The Relationship ◽  
Selection Of ◽  
The Way

‘Archive’ is a totality of records, layers and memories that are collected. A city is the archive that consists of the conscious selection of these layers and traces of the past and the present, looking towards the future. Metaxourgio is an area in the wider historic urban area of Keramikos in Athens that includes traces of various eras, beginning in the Antiquity and continuing all the way into the 21st century. Its archaeological space ‘Demosion Sema’ is mostly concealed under the ground level, waiting to be revealed. In this proposal, Metaxourgio is redesigned in light of archiving. Significant traces of the Antiquity, other ruins and buildings are studied, selected and incorporated in the new interventions. The area becomes the ‘open archive’ that leads towards its lost identity. The proposal aims not only to intensify the relationship of architecture with archaeology, but also to imbue the area’s identity with meanings that refer to the past, present and future.

scholarly journals Landslides and slope stability evaluation in the historical town of Kruja, Albania

2013 ◽  
Vol 1 (4) ◽  
pp. 3263-3304
Author(s):  
Y. Muceku ◽  
O. Korini
Keyword(s):  
Slope Stability ◽  
Debris Flow ◽  
Urban Area ◽  
Urban Areas ◽  
Geological Mapping ◽  
Stability Evaluation ◽  
Engineering Geological Mapping ◽  
The Past ◽  
Field Works ◽  
Cultural Monuments

Abstract. This paper describes the landslides and slope stability evaluation in the urban area of Kruja town, Albania. Kruja is a~historical and heritage center, due to the existence of many important cultural monuments including Skanderbeg castle and Bazaar square etc. The urban area of Kruja town has been affected from the Landslides effects, in the past and also present. From this phenomenon many engineering objects such as buildings, roads etc. are damaged and demolished. From the engineering geological mapping at scale 1 : 5000 it is observed that many active landslides have dramatically increased in activity after 1980s. The landslide types found in the studied area are earth slides, debris flow, as well as rock fall and rock rolling. Also, from field works and laboratory analysis, the slope stability of whole urban areas has been determined; for this purpose the studied zone is divided into the stable and unstable areas, which helps to better understand the mass movement's activity as one of the most harmful hazards of the geodynamics' phenomena.

Thrust Nozzles for Supersonic Transport Aircraft

1964 ◽  
Vol 86 (2) ◽  
pp. 97-104 ◽  
Author(s):  
David Migdal ◽  
John J. Horgan
Keyword(s):  
External Flow ◽  
Operating Costs ◽  
Jet Engine ◽  
Transport Aircraft ◽  
Supersonic Transport ◽  
The Past ◽  
Engine Thrust ◽  
Performance Trends ◽  
Flow Effects ◽  
Plug Nozzles

Supersonic transports will require jet-engine thrust nozzles that are highly efficient from take-off to supersonic cruise in order to minimize the direct operating costs. Variable-area ejectors, plug nozzles, and modifications of these basic types have been tested extensively during the past several years. Performance trends for these nozzles are presented with the emphasis on external flow effects. A new ejector which utilizes aerodynamically actuated doors to admit external air into the ejector shroud is discussed.

scholarly journals Attitudes of graduating Canadian urology residents on the job market: Is it getting better or are we just spinning our wheels?

2017 ◽  
Vol 12 (4) ◽  
pp. 104-9 ◽  
Author(s):  
Gregory W. Hosier ◽  
Naji J. Touma
Keyword(s):  
Urban Area ◽  
Response Rate ◽  
Large Urban Area ◽  
Job Market ◽  
Employment Opportunities ◽  
The Past ◽  
Agreement Score ◽  
Strongly Agree ◽  
Ideal Practice ◽  
The Ideal

Introduction: There has been increasing awareness of employment difficulties for physicians, especially surgeons, in Canada over the past few years. Our objective was to elucidate the attitudes and experiences of graduating Canadian urology residents in obtaining employment.Methods: We surveyed four separate cohorts of graduating urology residents in 2010, 2011, 2016, and 2017. Responses from the 2010 and 2011 cohorts were combined and compared to the combined results of the 2016 and 2017 cohorts. Mean Likert responses were compared using unpaired t-tests. An agreement score was created for those responding with “strongly agree” and “agree” on the Likert scale.Results: A total of 126 surveys were administered with a 100% response rate. The job market was rated as poor or very poor by 64.9% and 58.4% of graduates in 2010/2011 and 2016/2017, respectively (p=0.67). Lack of resources was identified as the biggest barrier to improved employment in both cohorts. Networking at meetings and staff urologists at their institution were the most important factors aiding employment identified by both cohorts. The ideal practice was academic or academically associated community practices in a large urban area, with 5‒10 partners for both cohorts.Conclusions: The majority of graduating urology residents viewed the job market as poor or very poor and this did not change over a six-year period. It is unclear how much personal preference for location and practice type drove the somewhat negative outlook of employment opportunities, as the majority of residents were seeking large urban, academic, or academically associated community practices in competitive locations.

Carbon emissions induced by farmland expansion in China during the past 300 years

2018 ◽  
Vol 62 (2) ◽  
pp. 423-437 ◽  
Author(s):  
Xuhong Yang ◽  
Xiaobin Jin ◽  
Xiaomin Xiang ◽  
Yeting Fan ◽  
Jing Liu ◽  
...  
Keyword(s):  
Carbon Emissions ◽  
The Past ◽  
Past 300 Years

scholarly journals Electric Vehicle Routing Problem with Battery Swapping Considering Energy Consumption and Carbon Emissions

2020 ◽  
Vol 12 (24) ◽  
pp. 10537
Author(s):  
Jin Li ◽  
Feng Wang ◽  
Yu He
Keyword(s):  
Energy Consumption ◽  
Vehicle Routing ◽  
Electric Vehicle ◽  
Carbon Emissions ◽  
Vehicle Routing Problem ◽  
Hill Climbing ◽  
Neighborhood Search ◽  
Battery Life ◽  
Routing Problem ◽  
Crossover And Mutation

In this paper, we study an electric vehicle routing problem while considering the constraints on battery life and battery swapping stations. We first introduce a comprehensive model consisting of speed, load and distance to measure the energy consumption and carbon emissions of electric vehicles. Second, we propose a mixed integer programming model to minimize the total costs related to electric vehicle energy consumption and travel time. To solve this model efficiently, we develop an adaptive genetic algorithm based on hill climbing optimization and neighborhood search. The crossover and mutation probabilities are designed to adaptively adjust with the change of population fitness. The hill climbing search is used to enhance the local search ability of the algorithm. In order to satisfy the constraints of battery life and battery swapping stations, the neighborhood search strategy is applied to obtain the final optimal feasible solution. Finally, we conduct numerical experiments to test the performance of the algorithm. Computational results illustrate that a routing arrangement that accounts for power consumption and travel time can reduce carbon emissions and total logistics delivery costs. Moreover, we demonstrate the effect of adaptive crossover and mutation probabilities on the optimal solution.

Sign in / Sign up

Export Citation Format

Share Document