Network recovery from large-scale failures considering the recovery resources and the upper limit of traffic demand

2011 ◽  
Author(s):  
Chunxia Yang ◽  
Hongfang Yu ◽  
Gang Sun
Keyword(s):  
Large Scale ◽  
Traffic Demand ◽  
Network Recovery ◽  
Upper Limit ◽  
Recovery Resources

scholarly journals Constrained Urban Airspace Design for Large-Scale Drone-Based Delivery Traffic

Aerospace ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 38
Author(s):  
Malik Doole ◽  
Joost Ellerbroek ◽  
Victor L. Knoop ◽  
Jacco M. Hoekstra
Keyword(s):  
Traffic Congestion ◽  
Urban Areas ◽  
Large Scale ◽  
Cost Savings ◽  
Future Research ◽  
Fast Time ◽  
Potential Cost ◽  
Horizontal Structure ◽  
Traffic Demand ◽  
Demand Patterns

Large-scale adoption of drone-based delivery in urban areas promise societal benefits with respect to emissions and on-ground traffic congestion, as well as potential cost savings for drone-based logistic companies. However, for this to materialise, the ability of accommodating high volumes of drone traffic in an urban airspace is one of the biggest challenges. For unconstrained airspace, it has been shown that traffic alignment and segmentation can be used to mitigate conflict probability. The current study investigates the application of these principles to a highly constrained airspace. We propose two urban airspace concepts, applying road-based analogies of two-way and one-way streets by imposing horizontal structure. Both of the airspace concepts employ heading-altitude rules to vertically segment cruising traffic according to their travel direction. These airspace configurations also feature transition altitudes to accommodate turning flights that need to decrease the flight speed in order to make safe turns at intersections. While using fast-time simulation experiments, the performance of these airspace concepts is compared and evaluated for multiple traffic demand densities in terms of safety, stability, and efficiency. The results reveal that an effective way to structure drone traffic in a constrained urban area is to have vertically segmented altitude layers with respect to travel direction as well as horizontal constraints imposed to the flow of traffic. The study also makes recommendations for areas of future research, which are aimed at supporting dynamic traffic demand patterns.

Link importance-based network recovery for large-scale failures in smart grids

2020 ◽  
Author(s):  
Huibin Jia ◽  
Yonghe Gai ◽  
Dongfang Xu ◽  
Yincheng Qi ◽  
Hongda Zheng
Keyword(s):  
Smart Grids ◽  
Large Scale ◽  
Network Recovery

scholarly journals The Feasibility of Opening Communities -- Based on the Wiedemann Car-Following Model

2018 ◽  
Vol 11 (3) ◽  
pp. 57
Author(s):  
Xiao-Yan Cao ◽  
Bing-Qian Liu ◽  
Bao-Ru Pan ◽  
Yuan-Biao Zhang
Keyword(s):  
Traffic Congestion ◽  
Large Scale ◽  
Gated Communities ◽  
Urban Traffic ◽  
Average Delay ◽  
Traffic Demand ◽  
Car Following ◽  
Car Following Model ◽  
Urbanization In China ◽  
The Impact

With the accelerating development of urbanization in China, the increasing traffic demand and large scale gated communities have aggravated urban traffic congestion. This paper studies the impact of communities opening on road network structure and the surrounding road capacity. Firstly, we select four indicators, namely average speed, vehicle flow, average delay time, and queue length, to measure traffic capacity. Secondly, we establish the Wiedemann car-following model, then use VISSIM software to simulate the traffic conditions of surrounding roads of communities. Finally, we take Shenzhen as an example to simulate and compare the four kinds of gated communities, axis, centripetal and intensive layout, and we also analyze the feasibility of opening communities.

scholarly journals Prevalence of Subclinical Hypothyroidism among Patients with Acute Myocardial Infarction

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Okuyan Ertugrul ◽  
Uslu Ahmet ◽  
Enhos Asim ◽  
Hepgul E. Gulcin ◽  
Ayca Burak ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Subclinical Hypothyroidism ◽  
Large Scale ◽  
Thyroid Stimulating Hormone ◽  
Free T4 ◽  
Upper Limit ◽  
St Elevation ◽  
Elevation Acute Myocardial Infarction ◽  
Tsh Levels

Introduction. Subclinical hypothyroidism (SCH) is defined as a serum thyroid-stimulating hormone (TSH) level above the upper limit of normal despite normal levels of serum free thyroxine. There is growing evidence that SCH is associated with increased cardiovascular risk. We tried to investigate prevalence of SCH in acute myocardial infarction patients. Methods and Results. We evaluate free T3, free T4, and TSH levels of 604 patients (age 58.4) retrospectively, who have been admitted to the coronary intensive care unit between years 2004–2009 with the diagnosis of ST elevation (STEMI) or non-ST elevation acute myocardial infarction (NSTEMI). Mild subclinical hypothyroidism (TSH 4.5 to 9.9 mU/l) was present in 54 (8.94%) participants and severe subclinical hypothyroidism (TSH 10.0 to 19.9 mU/l) in 11 (1.82%). So 65 patients (10.76%) had TSH levels between 4.5 and 20. Conclusions. In conclusion, 65 patients (10.76%) had TSH levels between 4.5 and 20 in our study, and it is a considerable amount. Large-scale studies are needed to clarify the effects of SCH on myocardial infarction both on etiologic and prognostic grounds.

scholarly journals Some Observations on the Behavior of the Liquid and Gas Phases in Temperate Glacier Ice

1975 ◽  
Vol 14 (71) ◽  
pp. 213-233 ◽  
Author(s):  
C. F. Raymond ◽  
W. D. Harrison
Keyword(s):  
Large Scale ◽  
Water Flux ◽  
Coarse Grained ◽  
Glacier Surface ◽  
Cross Sectional ◽  
Gas Phases ◽  
Upper Limit ◽  
Melt Water ◽  
Glacier Ice ◽  
Typical Summer

Microscopic and textural observations were made on ice samples cored from Blue Glacier slightly below the equilibrium line to depths of 60 m. Observations were started within a few minutes after collection Water was found in veins along three-grain intersections, in lenses on grain boundaries and in irregular shapes. Gas was found in bubbles in the interior of crystals, in bubbles touching veins and locally in veins Vein sizes showed some spread; average cross-sectional area was about 74 × 10−4mm2with no discernible, trend with texture or depth except within 7 m of the surface. Before the samples were examined they could have experienced a complex relaxation which could have changed them significantly As a result it is not possible to determine thein situsize of veins, but an upper limit can be determined. Also it is not possible to predict intergranular water flux per unit area, but 1 × 10−1m a−1represents an upper limit. In coarse-grained ice the water flux density is likely to be even smaller, because of a low density of veins and blocking by bubbles. This indicates that only a very small fraction of the melt-water production on a typical summer day can penetrate into the glacier on an intergranular scale except possibly near the surface. The existence of conduit-like features in several cores suggests that much melt water ran nevertheless penetrate the ice locally without large-scale lateral movements along the glacier surface. The observed profile of ice temperature indicates that the intergranular water flux may be much smaller than the upper limit determined from the core samples.

scholarly journals A logistic model for age-specific COVID-19 case-fatality rates

JAMIA Open ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 151-153
Author(s):  
Xiang Gao ◽  
Qunfeng Dong
Keyword(s):  
Mathematical Model ◽  
General Population ◽  
Logistic Model ◽  
Large Scale ◽  
Case Fatality ◽  
Rate Of Growth ◽  
Upper Limit

Abstract To develop a mathematical model to characterize age-specific case-fatality rates (CFR) of COVID-19. Based on 2 large-scale Chinese and Italian CFR data, a logistic model was derived to provide quantitative insight on the dynamics between CFR and age. We inferred that CFR increased faster in Italy than in China, as well as in females over males. In addition, while CFR increased with age, the rate of growth eventually slowed down, with a predicted theoretical upper limit for males (32%), females (21%), and the general population (23%). Our logistic model provided quantitative insight on the dynamics of CFR.

scholarly journals Some Observations on the Behavior of the Liquid and Gas Phases in Temperate Glacier Ice

1975 ◽  
Vol 14 (71) ◽  
pp. 213-233 ◽  
Author(s):  
C. F. Raymond ◽  
W. D. Harrison
Keyword(s):  
Large Scale ◽  
Water Flux ◽  
Coarse Grained ◽  
Glacier Surface ◽  
Cross Sectional ◽  
Gas Phases ◽  
Upper Limit ◽  
Melt Water ◽  
Glacier Ice ◽  
Typical Summer

Microscopic and textural observations were made on ice samples cored from Blue Glacier slightly below the equilibrium line to depths of 60 m. Observations were started within a few minutes after collection. Water was found in veins along three-grain intersections, in lenses on grain boundaries and in irregular shapes. Gas was found in bubbles in the interior of crystals, in bubbles touching veins, and locally in veins. Vein sizes showed some spread; average cross-sectional area was about 7 × 10−4 mm2 with no discernible, trend with texture or depth except within 7 m of the surface. Before the samples were examined they could have experienced a complex relaxation which could have changed them significantly. As a result it is not possible to determine the in situ size of veins, but an upper limit can be determined. Also it is not possible to predict intergranular water flux per unit area, but 1 × 10−1 m a−1 represents an upper limit. In coarse-grained ice the water flux density is likely to be even smaller, because of a low density of veins, and blocking by bubbles. This indicates that only a very small fraction of the melt-water production on a typical summer day can penetrate into the glacier on an intergranular scale except possibly near the surface. The existence of conduit-like features in several cores suggests that much melt water can nevertheless penetrate the ice locally without large-scale lateral movements along the glacier surface. The observed profile of ice temperature indicates that the intergranular water flux may be much smaller than the upper limit determined from the core samples.

scholarly journals Road Network Vulnerability Analysis Based on Improved Ant Colony Algorithm

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Yunpeng Wang ◽  
Yuqin Feng ◽  
Wenxiang Li ◽  
William Case Fulcher ◽  
Li Zhang
Keyword(s):  
Road Network ◽  
Large Scale ◽  
Ant Colony Algorithm ◽  
Ant Colony ◽  
Critical Infrastructures ◽  
Traffic Demand ◽  
The Road ◽  
Utility Index ◽  
Decision Supporting ◽  
Improved Ant Colony Algorithm

We present an improved ant colony algorithm-based approach to assess the vulnerability of a road network and identify the critical infrastructures. This approach improves computational efficiency and allows for its applications in large-scale road networks. This research involves defining the vulnerability conception, modeling the traffic utility index and the vulnerability of the road network, and identifying the critical infrastructures of the road network. We apply the approach to a simple test road network and a real road network to verify the methodology. The results show that vulnerability is directly related to traffic demand and increases significantly when the demand approaches capacity. The proposed approach reduces the computational burden and may be applied in large-scale road network analysis. It can be used as a decision-supporting tool for identifying critical infrastructures in transportation planning and management.

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