scholarly journals Exploring App-Based Taxi Movement Patterns from Large-Scale Geolocation Data

2021 ◽  
Vol 10 (11) ◽  
pp. 751
Author(s):  
Wenbo Zhang ◽  
Chang Xu
Keyword(s):  
Large Scale ◽  
Movement Patterns ◽  
Cumulative Distribution ◽  
Gyration Radius ◽  
Traffic Flows ◽  
Large Cities ◽  
Movement Characteristics ◽  
Pagerank Centrality ◽  
Visualization Techniques ◽  
Vehicle Movement

This study is designed to leverage ubiquitous mobile computing techniques on exploring app-based taxi movement patterns in large cities. To study patterns at different scales, we comprehensively explore both occupied and unoccupied vehicle movement characteristics through not only individual trips but also their aggregations. Moran’s I and its variations are applied to explore spatial autocorrelations among different rides. PageRank centrality is applied for a functional network representing traffic flows to discover places of interest. Gyration radius measures the scope of passenger mobility and driver passenger searching. Moreover, cumulative distribution and data visualization techniques are adopted for trip level characteristics and features analysis. The results indicate that the app-based taxi services are serving more neighborhoods other than downtown areas by taking large proportion of relatively shorter trips and contributing to net increase in total taxi ridership although net decrease in downtown areas. The spatial autocorrelations are significant not only within each service but also among services. With the smartphone-based applications, app-based taxi services are able to search passengers in a larger area and move more efficiently during both occupied and unoccupied periods. Mining from huge empty trip trajectory by app-based taxis, we also identify the existence of stationary/stops state and circulations.

scholarly journals Fencing affects African wild dog movement patterns and population dynamics

Oryx ◽  
2021 ◽  
pp. 1-9
Author(s):  
Helen M. K. O'Neill ◽  
Sarah M. Durant ◽  
Stefanie Strebel ◽  
Rosie Woodroffe
Keyword(s):  
Population Dynamics ◽  
Large Scale ◽  
Animal Movement ◽  
Landscape Connectivity ◽  
Ecological Impact ◽  
Movement Patterns ◽  
Wrong Side ◽  
African Wild Dog ◽  
Wild Dog ◽  
Wild Dogs

Abstract Wildlife fences are often considered an important tool in conservation. Fences are used in attempts to prevent human–wildlife conflict and reduce poaching, despite known negative impacts on landscape connectivity and animal movement patterns. Such impacts are likely to be particularly important for wide-ranging species, such as the African wild dog Lycaon pictus, which requires large areas of continuous habitat to fulfil its resource requirements. Laikipia County in northern Kenya is an important area for wild dogs but new wildlife fences are increasingly being built in this ecosystem. Using a long-term dataset from the area's free-ranging wild dog population, we evaluated the effect of wildlife fence structure on the ability of wild dogs to cross them. The extent to which fences impeded wild dog movement differed between fence designs, although individuals crossed fences of all types. Purpose-built fence gaps increased passage through relatively impermeable fences. Nevertheless, low fence permeability can lead to packs, or parts of packs, becoming trapped on the wrong side of a fence, with consequences for population dynamics. Careful evaluation should be given to the necessity of erecting fences; ecological impact assessments should incorporate evaluation of impacts on animal movement patterns and should be undertaken for all large-scale fencing interventions. Where fencing is unavoidable, projects should use the most permeable fencing structures possible, both in the design of the fence and including as many purpose-built gaps as possible, to minimize impacts on wide-ranging wildlife.

scholarly journals Joint optimization of network selection and task offloading for vehicular edge computing

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Lujie Tang ◽  
Bing Tang ◽  
Li Zhang ◽  
Feiyan Guo ◽  
Haiwu He
Keyword(s):  
Large Scale ◽  
Vehicular Networks ◽  
Access Point ◽  
Edge Computing ◽  
Network Selection ◽  
Network Access ◽  
Task Execution ◽  
Point Selection ◽  
Vehicle Movement ◽  
Task Offloading

AbstractTaking the mobile edge computing paradigm as an effective supplement to the vehicular networks can enable vehicles to obtain network resources and computing capability nearby, and meet the current large-scale increase in vehicular service requirements. However, the congestion of wireless networks and insufficient computing resources of edge servers caused by the strong mobility of vehicles and the offloading of a large number of tasks make it difficult to provide users with good quality of service. In existing work, the influence of network access point selection on task execution latency was often not considered. In this paper, a pre-allocation algorithm for vehicle tasks is proposed to solve the problem of service interruption caused by vehicle movement and the limited edge coverage. Then, a system model is utilized to comprehensively consider the vehicle movement characteristics, access point resource utilization, and edge server workloads, so as to characterize the overall latency of vehicle task offloading execution. Furthermore, an adaptive task offloading strategy for automatic and efficient network selection, task offloading decisions in vehicular edge computing is implemented. Experimental results show that the proposed method significantly improves the overall task execution performance and reduces the time overhead of task offloading.

scholarly journals Ensemble model for estimating continental-scale patterns of human movement: a case study of Australia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Karen McCulloch ◽  
Nick Golding ◽  
Jodie McVernon ◽  
Sarah Goodwin ◽  
Martin Tomko
Keyword(s):  
Spatial Scales ◽  
Predictive Ability ◽  
Movement Patterns ◽  
Human Movement ◽  
Continental Scale ◽  
Movement Characteristics ◽  
Human Movements ◽  
Movement Models ◽  
Epidemiology Data

AbstractUnderstanding human movement patterns at local, national and international scales is critical in a range of fields, including transportation, logistics and epidemiology. Data on human movement is increasingly available, and when combined with statistical models, enables predictions of movement patterns across broad regions. Movement characteristics, however, strongly depend on the scale and type of movement captured for a given study. The models that have so far been proposed for human movement are best suited to specific spatial scales and types of movement. Selecting both the scale of data collection, and the appropriate model for the data remains a key challenge in predicting human movements. We used two different data sources on human movement in Australia, at different spatial scales, to train a range of statistical movement models and evaluate their ability to predict movement patterns for each data type and scale. Whilst the five commonly-used movement models we evaluated varied markedly between datasets in their predictive ability, we show that an ensemble modelling approach that combines the predictions of these models consistently outperformed all individual models against hold-out data.

scholarly journals Probabilistic downscaling of precipitation data in a subtropical mountain area: a two-step approach

2011 ◽  
Vol 18 (2) ◽  
pp. 223-234 ◽  
Author(s):  
R. Haas ◽  
K. Born
Keyword(s):  
Complex Terrain ◽  
Large Scale ◽  
Distribution Functions ◽  
Data Availability ◽  
Cumulative Distribution ◽  
Second Step ◽  
Mountain Area ◽  
Investigation Area ◽  
Distribution Parameters ◽  
Mountain Environment

Abstract. In this study, a two-step probabilistic downscaling approach is introduced and evaluated. The method is exemplarily applied on precipitation observations in the subtropical mountain environment of the High Atlas in Morocco. The challenge is to deal with a complex terrain, heavily skewed precipitation distributions and a sparse amount of data, both spatial and temporal. In the first step of the approach, a transfer function between distributions of large-scale predictors and of local observations is derived. The aim is to forecast cumulative distribution functions with parameters from known data. In order to interpolate between sites, the second step applies multiple linear regression on distribution parameters of observed data using local topographic information. By combining both steps, a prediction at every point of the investigation area is achieved. Both steps and their combination are assessed by cross-validation and by splitting the available dataset into a trainings- and a validation-subset. Due to the estimated quantiles and probabilities of zero daily precipitation, this approach is found to be adequate for application even in areas with difficult topographic circumstances and low data availability.

Techno-Economic Assessment of Utilizing Wind Energy for Hydrogen Production Through Electrolysis

2017 ◽  
Author(s):  
Reza Ziazi ◽  
Kasra Mohammadi ◽  
Navid Goudarzi
Keyword(s):  
Hydrogen Production ◽  
Wind Energy ◽  
Wind Turbines ◽  
Alternative Energy ◽  
Large Scale ◽  
Fossil Fuels ◽  
Combustion Engine ◽  
Economic Assessment ◽  
Large Cities ◽  
North East

Hydrogen as a clean alternative energy carrier for the future is required to be produced through environmentally friendly approaches. Use of renewables such as wind energy for hydrogen production is an appealing way to securely sustain the worldwide trade energy systems. In this approach, wind turbines provide the electricity required for the electrolysis process to split the water into hydrogen and oxygen. The generated hydrogen can then be stored and utilized later for electricity generation via either a fuel cell or an internal combustion engine that turn a generator. In this study, techno-economic evaluation of hydrogen production by electrolysis using wind power investigated in a windy location, named Binaloud, located in north-east of Iran. Development of different large scale wind turbines with different rated capacity is evaluated in all selected locations. Moreover, different capacities of electrolytic for large scale hydrogen production is evaluated. Hydrogen production through wind energy can reduce the usage of unsustainable, financially unstable, and polluting fossil fuels that are becoming a major issue in large cities of Iran.

Vehicle movement patterns and vegetative impacts during military training exercises

2003 ◽  
Vol 40 (2) ◽  
pp. 83-95 ◽  
Author(s):  
Liv B. Haugen ◽  
Paul D. Ayers ◽  
Alan B. Anderson
Keyword(s):  
Military Training ◽  
Movement Patterns ◽  
Training Exercises ◽  
Vehicle Movement

scholarly journals Study of Vortex Systems as a Method to Weakening the Urban Heat Islands within the Financial District in Large Cities

2021 ◽  
Vol 13 (23) ◽  
pp. 13206
Author(s):  
Luis Rodriguez-Lucas ◽  
Chen Ning ◽  
Marcelo Fajardo-Pruna ◽  
Yugui Yang
Keyword(s):  
Rural Areas ◽  
Large Scale ◽  
Flow Characteristics ◽  
Maximum Velocity ◽  
Vortex Generator ◽  
Urban Heat Islands ◽  
Navier Stokes ◽  
Specific Work ◽  
Heat Islands ◽  
Large Cities

This paper presents a new concept called the urban vortex system (UVS). The UVS couples a vortex generator (V.G.) that produces updraft by artificial vortex and a vortex stability zone (VSZ) consisting of an assembly of four buildings acting as a chimney. Through this system, a stable, upward vortex flow can be generated. The Reynolds Averaged Navier–Stokes (RANS) simulation was carried out to investigate the flow field in the UVS. The Renormalized Group (RNG) k–ε turbulent model was selected to solve the complex turbulent flow. Validation of the numerical results was achieved by making a comparison with the large-size experimental model. The results reported that a steady-state vortex could be formed when a vapor-air mixture at 2 m/s and 450 K enters the vortex generator. This vortex presented a maximum negative central pressure of −6.81 Pa and a maximum velocity of 5.47 (m/s). Finally, the similarity method found four dimensionless parameters, which allowed all the flow characteristics to be transported on a large scale. The proposed large-scale UVS application is predicted to be capable, with have a maximum power of 2 M.W., a specific work of 3 kJ/kg, buildings 200-m high, and the ability to generate winds of 6.1 m/s (20 km/h) at 200 m up to winds of 1.5 m/s (5 km/h) at 400 m. These winds would cause the rupture of the gas capsule of the heat island phenomenon. Therefore, the city would balance its temperature with that of the surrounding rural areas.

scholarly journals Movement Patterns of Wintering Grassland Sparrows in Arizona

The Auk ◽  
2000 ◽  
Vol 117 (3) ◽  
pp. 748-759 ◽  
Author(s):  
Caleb E. Gordon
Keyword(s):  
Large Scale ◽  
Radio Telemetry ◽  
Movement Patterns ◽  
Movement Pattern ◽  
Summer Rainfall ◽  
Movement Behavior ◽  
Home Ranges ◽  
Mark Recapture ◽  
Mobile Species ◽  
Study Sites

Abstract I used mark-recapture analysis and radio telemetry to characterize winter movement patterns of six grassland sparrows in southeastern Arizona. Mark-recapture data were generated by banding birds captured during repeated flush-netting sessions conducted on a series of 7-ha plots over three consecutive winters. This resulted in 2,641 captures of 2,006 individual sparrows of the six species. Radio telemetry was conducted concurrently on 20 individuals of four of these species. Recapture data and radio telemetry indicated that Cassin's Sparrow (Aimophila cassinii) and Grasshopper Sparrow (Ammodramus savannarum) were the most sedentary, followed by Baird's Sparrow (Ammodramus bairdii), Vesper Sparrow (Pooecetes gramineus), Savannah Sparrow (Passerculus sandwichensis), and Brewer's Sparrow (Spizella breweri). Grasshopper, Baird's, Savannah, and Vesper sparrows tended to remain within fixed home ranges during winter. With the exception of Savannah Sparrows, whose movement behavior varied among study sites, movement patterns remained constant within species across years and study sites despite radical fluctuations in the absolute and relative abundances of all species. Interspecific differences in movement pattern suggest that species in this system partition niche space according to the regional-coexistence mechanism. Abundances of the most sedentary species, Cassin's, Grasshopper, and Baird's sparrows, were poorly or negatively correlated with summer rainfall at the between-year landscape scale, whereas abundances of the more mobile Savannah, Vesper, and Brewer's sparrows were strongly positively correlated. This is consistent with the theoretical prediction that movement constrains large-scale habitat selection, favoring mobile species in fragmented environments.

scholarly journals The role of spatial dependence for large-scale flood risk estimation

2020 ◽  
Vol 20 (4) ◽  
pp. 967-979 ◽  
Author(s):  
Ayse Duha Metin ◽  
Nguyen Viet Dung ◽  
Kai Schröter ◽  
Sergiy Vorogushyn ◽  
Björn Guse ◽  
...  
Keyword(s):  
Flood Risk ◽  
Spatial Dependence ◽  
Large Scale ◽  
Temporal Dynamics ◽  
Cumulative Distribution ◽  
Risk Assessments ◽  
Return Periods ◽  
Risk Estimates ◽  
Flood Peaks ◽  
Complete Dependence

Abstract. Flood risk assessments are typically based on scenarios which assume homogeneous return periods of flood peaks throughout the catchment. This assumption is unrealistic for real flood events and may bias risk estimates for specific return periods. We investigate how three assumptions about the spatial dependence affect risk estimates: (i) spatially homogeneous scenarios (complete dependence), (ii) spatially heterogeneous scenarios (modelled dependence) and (iii) spatially heterogeneous but uncorrelated scenarios (complete independence). To this end, the model chain RFM (regional flood model) is applied to the Elbe catchment in Germany, accounting for the spatio-temporal dynamics of all flood generation processes, from the rainfall through catchment and river system processes to damage mechanisms. Different assumptions about the spatial dependence do not influence the expected annual damage (EAD); however, they bias the risk curve, i.e. the cumulative distribution function of damage. The widespread assumption of complete dependence strongly overestimates flood damage of the order of 100 % for return periods larger than approximately 200 years. On the other hand, for small and medium floods with return periods smaller than approximately 50 years, damage is underestimated. The overestimation aggravates when risk is estimated for larger areas. This study demonstrates the importance of representing the spatial dependence of flood peaks and damage for risk assessments.

scholarly journals Physical Modelling of Roll and Pitch Motions of Travelling or Stationary Ship in Large-Scale Landslide-Generated Waves

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Pei-yin Yuan ◽  
Ping-yi Wang ◽  
Yu Zhao
Keyword(s):  
Large Scale ◽  
Physical Modelling ◽  
River Channel ◽  
Mountain River ◽  
Propagation Characteristics ◽  
Field Investigations ◽  
Movement Characteristics ◽  
Depth Study ◽  
Sailing Ship ◽  
River Type

Large-scale landslides often occur in river-type reservoirs, and landslide-generated waves affect navigation channels and the navigation of ships. Thus, such waves cause widespread regional disasters. This study establishes a mechanical model of landslide-generated waves via field investigations and data collection, reveals the mechanism and process of landslide-generated waves, and investigates the propagation characteristics of landslide-generated waves along a sloping wave. The feasibility of the model is verified via (i) regularity analysis, (ii) comparative analysis of the effect of landslide-generated waves of mountain river channel reservoirs on the movement characteristics of navigation vessels and stationary vessels, (iii) deviation from the equilibrium position, and (iv) an in-depth study of the influence of large-scale landslide-generated waves on ships in different navigation positions in a river channel. Countermeasures are proposed for a sailing ship to tackle a sudden landslide-generated wave; these measures can provide a theoretical basis for ships to sail safely through large-scale landslide-generated waves.

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