Platooning Strategy for Connected and Autonomous Vehicles: Transition from Light Traffic

2017 ◽  
Vol 2623 (1) ◽  
pp. 73-81 ◽  
Author(s):  
Soohyuk Bang ◽  
Soyoung Ahn
Keyword(s):  
Autonomous Vehicles ◽  
Spring Constant ◽  
Low Flow ◽  
Control Parameters ◽  
Mass Damper ◽  
Acceleration And Deceleration ◽  
Formation And Evolution ◽  
The Given ◽  
Insight Into ◽  
Flow States

This study presents a strategy for platoon formation and evolution of connected and autonomous vehicles (CAVs) in free-flow traffic. The proposed strategy is based on swarm intelligence, which describes bird flocking, fish schooling, and so on, in natural and artificial systems. In this concept, CAVs behave according to some rules to move together as a platoon without collisions. The rules are expressed by a spring–mass–damper system: CAV platoon formation and evolution are controlled by the spring constant and damping coefficient. Valid domains of these control parameters were derived on the basis of physical vehicle properties (e.g., bounded acceleration and deceleration) for realistic control. Furthermore, various relationships—maximum (in which the spring constant was set at its maximum for the given flow), quadratic, and cubic—between the control parameters and traffic flow were examined with simulations to obtain insight into desirable control parameter settings. The results suggest that the most efficient platooning can be achieved by the maximum relationship between the spring constant and flow with critical damping. However, the cubic relationship coupled with overdamping is more desirable in low-flow states to allow more freedom for vehicles to change lanes.

Analysis and Control of Heterogeneous Connected and Autonomous Vehicles using a Spring-Mass-Damper System

2020 ◽  
Vol 2674 (8) ◽  
pp. 309-318
Author(s):  
Sookyuk Bang ◽  
Soyoung Ahn
Keyword(s):  
Equilibrium State ◽  
Autonomous Vehicles ◽  
Control Parameters ◽  
Heavy Vehicles ◽  
Heavy Duty ◽  
Passenger Cars ◽  
Lower Performance ◽  
Mass Damper ◽  
And Control ◽  
Heavy Duty Vehicles

This study analyzes the behavior of heterogeneous connected and autonomous vehicles (CAVs) and proposes the best vehicle sequence for optimal platoon throughput and platoon formation. A spring-mass-damper (SMD) system is adopted for control of CAVs, and the control parameters are formulated in relation to the physical capabilities of vehicles. To gain insight, we consider three types of vehicle: passenger cars, mini-vans, and heavy-duty vehicles. For each type, we investigate the maximum platoon throughput and the clustering time, defined as the time to reach the target equilibrium state. We further investigate different sequences of vehicle types in a platoon to identify the optimal vehicle order that maximizes the throughput and minimizes clustering time. Findings suggest that the highest performance vehicle (in relation to acceleration capability) should be placed as the leader of a platoon and that the number of passenger cars behind heavy vehicles (e.g., semi-trailers) should be minimized in the platoon. In addition, we examine how the proportions of lower performance vehicles affect throughput and clustering times. The result suggests that the higher the proportions, the lower the throughput and the longer the clustering time. The lowest performance vehicle had the greatest effect.

Mixed Traffic of Connected and Autonomous Vehicles and Human-Driven Vehicles: Traffic Evolution and Control using Spring-Mass-Damper System

2019 ◽  
Vol 2673 (7) ◽  
pp. 504-515 ◽  
Author(s):  
Soohyuk Bang ◽  
Soyoung Ahn
Keyword(s):  
Autonomous Vehicles ◽  
Control Method ◽  
Feasible Region ◽  
Control Parameters ◽  
Mixed Traffic ◽  
Traffic Dynamics ◽  
Acceleration Rate ◽  
Mass Damper ◽  
Spring Coefficient ◽  
And Control

This paper sheds light on mixed-traffic dynamics considering the differences in driving characteristics, namely acceleration/deceleration rate, desired speed, and response time, between connected and autonomous vehicles (CAVs) and human-driven vehicles (HDVs). In light traffic, these differences were found to induce platoon formations, headed by vehicles with a lower acceleration rate and propensity not to exceed the desired speed (HDV in this study). Platoon formations lead to large inter-platoon spacing that can be utilized to accommodate cut-in vehicles. In a near-capacity condition, however, the differences in driving characteristics can induce voids and undermine traffic throughput when traffic is disturbed by merging vehicles. Based on these findings, a simple CAV control method is proposed based on the spring-mass-damper (SMD) system approach that directly considers the HDV behavior to mitigate disturbance propagation and throughput reduction. The main principle is to adjust the control parameters (lower spring coefficient and higher damping coefficient in the SMD control model) with an aim to control CAVs to absorb the cut-in impact (i.e., spacing shortage) before it reaches the first upstream HDV. A simulation experiment suggests the feasible region of the control parameters, subject to the recovery time, the number of controllable CAVs, and the cut-in impact.

Control of Connected and Autonomous Vehicles with Cut-in Movement using Spring Mass Damper System

2018 ◽  
Vol 2672 (20) ◽  
pp. 133-143 ◽  
Author(s):  
Soohyuk Bang ◽  
Soyoung Ahn
Keyword(s):  
Autonomous Vehicles ◽  
Recovery Time ◽  
Control Method ◽  
Control Model ◽  
Lane Change ◽  
Control Parameters ◽  
Traffic Conditions ◽  
Disturbance Propagation ◽  
Simulation Based ◽  
Mass Damper

This paper proposes a theoretical framework to control a platoon of connected and autonomous vehicles (CAVs) in the presence of cut-in movements. The control method is developed based on the spring–mass–damper (SMD) system concept and aims to improve the platoon efficiency and stability after a cut-in movement (e.g., lane change and merging from on-ramp). The method seeks to resolve a disturbance created by a cut-in vehicle by systematically setting two control parameters, spring constant and damping coefficient, of the SMD-based control model based on the prevailing traffic conditions. The control method is evaluated through a simulation based on the changes in speed and spacing, recovery time to reach the desired speed, disturbance propagation, and platoon flow. The simulation result shows that the control method can effectively reduce the disturbance caused by a cut-in movement and improve platoon flow.

Mobile-Friendly Dashboards to Display Associations Between Cited-by and Similar Journals on Mobile Health Research: A Bibliometric Study (Preprint)

2018 ◽  
Author(s):  
Tsair-Wei Chien ◽  
Hsien-Yi Wang ◽  
Yang Shao ◽  
Willy Chou
Keyword(s):  
Social Network ◽  
Mobile Health ◽  
Health Research ◽  
Similarity Criteria ◽  
Network Density ◽  
Deep Insight ◽  
Density Indices ◽  
The Subject ◽  
The Given ◽  
Insight Into

BACKGROUND Researchers often spend a great deal of time and effort retrieving related journals for their studies and submissions. Authors often designate one article and then retrieve other articles that are related to the given one using PubMed’s service for finding cited-by or similar articles. However, to date, none present the association between cited-by and similar journals related to a given journal. Authors need one effective and efficient way to find related journals on the topic of mobile health research. OBJECTIVE This study aims (1) to show the related journals for a given journal by both cited-by and similarity criteria; (2) to present the association between cited-by and similarity journals related to a given journal; (3) to inspect the patterns of network density indices among clusters classified by social network analysis (SNA); (4) to investigate the feature of Kendall's coefficient(W) of concordance. METHODS We obtained 676 abstracts since 2013 from Medline based on the keywords of ("JMIR mHealth and uHealth"[Journal]) on June 30, 2018, and plotted the clusters of related journals on Google Maps by using MS Excel modules. The features of network density indices were examined. The Kendall coefficient (W) was used to assess the concordance of clusters across indices. RESULTS This study found that (1) the journals related to JMIR mHealth and uHealth are easily presented on dashboards; (2) a mild association(=0.14) exists between cited-by and similar journals related to JMIR mHealth and uHealth; (3) the median Impact Factor were 3.37 and 2.183 based on the representatives of top ten clusters grouped by the cited-by and similar journals, respectively; (4) all Kendall’s coefficients(i.e., 0.82, 0.89, 0.92, and 0.75) for the four sets of density centrality have a statistically significant concordance (p < 0.05). CONCLUSIONS SNA provides deep insight into the relationships of related journals to a given journal. The results of this research can provide readers with a knowledge and concept diagram to use with future submissions to a given journal in the subject category of Mobile Health Research. CLINICALTRIAL Not available

scholarly journals R Coronae Borealis Stars: Long-Term Photometric & Spectroscopic Studies

1998 ◽  
Vol 11 (1) ◽  
pp. 379-379
Author(s):  
P.L. Cottrell ◽  
L. Skuljan ◽  
P.M. Kilmartin ◽  
C. Gilmore ◽  
W.A. Lawson
Keyword(s):  
Radial Velocity ◽  
Spectroscopic Studies ◽  
Photometric Data ◽  
Decline Phase ◽  
Dust Clouds ◽  
Medium Resolution ◽  
Formation And Evolution ◽  
R Coronae Borealis Stars ◽  
Insight Into

For more than a decade we have been able to acquire and analyse a significant amount of photometric data of the highly variable R Coronae Borealis (RCB) stars. This has made been possible by a photometric service observing programme instigated at the Observatory. These photometric data have been combined with less extensive spectroscopic coverage, particularly of the decline phase of these stars. These have been supplemented by observations obtained at Mount Stromlo and Siding Spring Observatories for a radial velocity study. Significantly more spectroscopic observations are now being acquired with the development of a new medium resolution spectrograph at Mount John University Observatory. In this poster we will present recent photometric and spectroscopic results for a number of the RCB stars in our sample. This observational and analysis work can be used to provide further insight into the nature of these stars, their likely progeny and progenitors and the processes that are involved in the formation and evolution of the obscuring dust clouds which cause the decline phase.

scholarly journals Traffic Flow Management of Autonomous Vehicles Using Platooning and Collision Avoidance Strategies

Electronics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1221
Author(s):  
Anum Mushtaq ◽  
Irfan ul Haq ◽  
Wajih un Nabi ◽  
Asifullah Khan ◽  
Omair Shafiq
Keyword(s):  
Traffic Flow ◽  
Collision Avoidance ◽  
Autonomous Vehicles ◽  
Flow Management ◽  
V2v Communication ◽  
Cooperative Strategies ◽  
Vehicle To Vehicle ◽  
Traffic Flow Management ◽  
Vehicle To Infrastructure ◽  
Formation And Evolution

Connected Autonomous Vehicles (AVs) promise innovative solutions for traffic flow management, especially for congestion mitigation. Vehicle-to-Vehicle (V2V) communication depends on wireless technology where vehicles can communicate with each other about obstacles and make cooperative strategies to avoid these obstacles. Vehicle-to-Infrastructure (V2I) also helps vehicles to make use of infrastructural components to navigate through different paths. This paper proposes an approach based on swarm intelligence for the formation and evolution of platoons to maintain traffic flow during congestion and collision avoidance practices using V2V and V2I communications. In this paper, we present a two level approach to improve traffic flow of AVs. At the first level, we reduce the congestion by forming platoons and study how platooning helps vehicles deal with congestion or obstacles in uncertain situations. We performed experiments based on different challenging scenarios during the platoon’s formation and evolution. At the second level, we incorporate a collision avoidance mechanism using V2V and V2I infrastructures. We used SUMO, Omnet++ with veins for simulations. The results show significant improvement in performance in maintaining traffic flow.

scholarly journals Quantitative Shape-Classification of Misfitting Precipitates during Cubic to Tetragonal Transformations: Phase-Field Simulations and Experiments

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1373
Author(s):  
Yueh-Yu Lin ◽  
Felix Schleifer ◽  
Markus Holzinger ◽  
Na Ta ◽  
Birgit Skrotzki ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Phase Field ◽  
Phase Field Model ◽  
Invariant Moments ◽  
Plane Normal ◽  
Plane Shape ◽  
Formation And Evolution ◽  
The Given ◽  
Good Agreement

The effectiveness of the mechanism of precipitation strengthening in metallic alloys depends on the shapes of the precipitates. Two different material systems are considered: tetragonal γ′′ precipitates in Ni-based alloys and tetragonal θ′ precipitates in Al-Cu-alloys. The shape formation and evolution of the tetragonally misfitting precipitates was investigated by means of experiments and phase-field simulations. We employed the method of invariant moments for the consistent shape quantification of precipitates obtained from the simulation as well as those obtained from the experiment. Two well-defined shape-quantities are proposed: (i) a generalized measure for the particles aspect ratio and (ii) the normalized λ2, as a measure for shape deviations from an ideal ellipse of the given aspect ratio. Considering the size dependence of the aspect ratio of γ′′ precipitates, we find good agreement between the simulation results and the experiment. Further, the precipitates’ in-plane shape is defined as the central 2D cut through the 3D particle in a plane normal to the tetragonal c-axes of the precipitate. The experimentally observed in-plane shapes of γ′′-precipitates can be quantitatively reproduced by the phase-field model.

Metabolism of the fat cell in low-flow states

1966 ◽  
Vol 6 (6) ◽  
pp. 254-258 ◽  
Author(s):  
William Schumer
Keyword(s):  
Low Flow ◽  
Fat Cell ◽  
Flow States

scholarly journals Constitutional Dilemma of Pakistan: 1947 -1956

2018 ◽  
Vol III (I) ◽  
pp. 1-9
Author(s):  
Muhammad Rizwan ◽  
Manzoor Ahmad ◽  
Syed Asif Anwar Bukhari
Keyword(s):  
Human Rights ◽  
Political Leadership ◽  
Deep Insight ◽  
Constitutional Development ◽  
The World ◽  
Refugee Problem ◽  
The Right ◽  
The Given ◽  
The Relationship ◽  
Insight Into

Soon after its creation, Pakistan confronted many issues including refugee problem, scarcity of able political leadership, absence of mutual consensus between both wings of the country and confusing nature of the relationship between Islam and state etc. took almost nine years to frame the permanent constitution for Pakistan. Constitution, the basic document of a state, determines the shape of its laws, structure of governance and system of rights and duties. The effectiveness of a constitution is judged by its practicability in the given area where it is enforced by the state machinery. Although, all civilized states of the world do possess a constitution, yet a good constitution is one which must protect the basic human rights by ensuring the independence of judiciary. Due to countless hurdles at the beginning of its journey, Pakistan’s constitutional development in the right direction could not take place. The main objective of the present study is to provide deep insight into the events and factors causing a delay in the constitution-making for the newly created state of Pakistan. The various events which took place from 1947 to 1956 have been analyzed in a subtle way.

scholarly journals Scientific methods of public administration in migration research

2020 ◽  
Vol 68 (2) ◽  
pp. 109-122
Author(s):  
András László Szabó
Keyword(s):  
Public Administration ◽  
Research Methods ◽  
Methodological Approach ◽  
Point Of View ◽  
Scientific Methods ◽  
Migration Research ◽  
Independent Field ◽  
The Subject ◽  
The Given ◽  
Insight Into

In my study, I list the directions of migration research, all from the point of view of public administration science. The emergence of migration research as an independent field is necessitated by the growth of migration. Researchers are researching the phenomenon of migration from their own field. Public administration uses a multidisciplinary, i.e. methodological approach of several disciplines, all of which is determined by the knowledge and nature of the subject of the given research. In the following, I review and evaluate the methodological directions of the research, which can provide an answer to a segment of the phenomenon of migration. The study gives an insight into research methods for migration research. It is not intended to present specific examples and procedures. At the end of the study, in possible directions, beyond the science of public administration, I list the organizations and faculties that are able to use the methodology of migration research.

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