•Traffic conflict study comparing cyclists’ relative risk for five bicycle layouts.•Watchdog video analysis software applied to reduce video data.•Video analysis software necessary to conduct larger ...conflict studies.•Recessed bicycle track seems to provide the highest safety level for cyclists.
The purpose of this study is to compare the safety of cyclists in five bicycle facility layouts in signalized intersections at various traffic volumes in order to assess if some layouts are better than others with regards to cyclist safety and to develop methods to facilitate this comparison. The five layouts included two full-length bicycle tracks with and without separate right-turning lane, two truncated bicycle tracks – one in which cyclists and right-turning vehicles merge in the right-turning lane, one continued into a narrow bicycle lane – and a recessed bicycle track. Using two different definitions of traffic conflicts the safety of cyclists in each layout is calculated as the risk of a cyclist being involved in a conflict with left- and right-turning vehicles at low, medium and high vehicle volumes, respectively. In total, around 35,500 left-turning vehicles, 38,000 right-turning vehicles and 16,000 cyclists going straight ahead were observed, resulting in 12 left-hook and 25 right-hook traffic conflicts for the reaction-based indicator and 25 left-hook and 80 right-hook traffic conflicts for the time-based indicator. The results show that regardless of which of the two conflict indicators were used, the number of conflicts was too small to make firm conclusions about which layout is safest for cyclists at various traffic volumes, although the study was based on 80h of video recordings from each of the five intersections. However, a recessed bicycle track seems to be safer than the other geometric layouts. In order to facilitate the detection of conflicts, we developed watchdog video analysis software to reduce the amount of video. This software compressed 400h of video into 64h, i.e. 16% of its original length. The use of this software is particularly important to provide enough conflicts for an analysis if even larger traffic conflict studies should be carried out.
Four donor–acceptor salicylaldimines with benzoheterocyclic substituents at nitrogen imine were prepared and characterised by means of optical spectroscopy. Their luminescent properties were compared ...with two isoelectronic carbocyclic analogues. In contrast to the typical salicylaldimines, our reported benzoheterocyclic compounds exhibit solely local emissive behaviour in all media whereas for the carbocyclic analogues we expectedly observe dominant ESIPT emission in the majority of instances. Low temperature (5 K - liquid helium) fluorescence measurements revealed the effect of the restriction of the molecular rotation which was manifested by significant increment of the fluorescence intensity. The comprehensive experimental and ab initio study reveal effect of solvent polarity, viscosity and temperature on the complex photophysics of heterocyclic and carbocyclic substituted salicylaldimines with several degrees of freedom for molecular transformations. This work adds considerable insight in emission lifetime data which greatly facilitates understanding of the fluorescence mechanism of the molecules with environmentally dependent restrictions.
The aim of this paper is to study the differential geometric properties of the intersection curve of two parametric surfaces in Euclidean n-space. For this aim, we first present the mth order ...derivative formula of a curve lying on a parametric surface. Then, we obtain curvatures and Frenet vectors of the transversal intersection curve of two parametric surfaces in Euclidean n-space. We also provide computer code produced in MATLAB to simplify determining the coefficients relative to Frenet frame of higher order derivatives of a curve.
The current conduction mechanisms (CCMs), temperature-sensitivities (S), energy-dependent interface traps (Nss), and origin of the intersection points in the forward bias (IF−VF) plots of the ...Al/Al2O3/Ge/p-Si heterostructure were investigated in wide temperature range of 90–420 K. Firstly, main electrical parameters, including reverse-saturation current (Io), ideality factor (n), zero-bias barrier-height (ΦBo), and series-resistance (Rs) values, were extracted for each temperature. The lnIF-VF curves illustrate two distinct linear regimes at low and intermediate bias voltages. Despite the observed decline in n values as temperature rises, the corresponding ΦBo values exhibit an upward trend. The conventional Richardson plots deviated from linearity at low temperatures, and the Richardson-constants (A*) value obtained from its linear part is quite lower than its theoretical value. Hence, ΦBo−q/2 kT, ΦBo−n, and n(kT)/q−(kT/q) correlations were plotted to seek indications of the Gaussian distribution (GD) of barrier heights (BHs) and tunneling mechanism. Temperate sensitivity (S = dV/dT) for 0.01, 0.10, 0.50, and 1 μA was found as 2.30, 2.33, 2.34, and 2.35 mV/K, which indicated that the fabricated Al/Al₂O₃/Ge/p-Si heterostructure is highly sensitive to temperature, rendering it suitable for use in temperature sensor applications. The observed crossing point at about 2.4V was explained by an increase in the apparent BH with temperature and the presence of Rs.
Objective: Intersection movement assist (IMA) has been recognized as one of the prominent countermeasures to reduce angle crashes at intersections, which constitute 22% of total crashes in the United ...States. Utilizing vehicle-based sensors, vehicle-to-vehicle (V2V), and vehicle-to-infrastructure (V2I) communications, IMA offers extended vision to provide early warning for an imminent crash. However, most of IMA-related research implements their methods and strategies only in simulations, test tracks, or driving simulator studies that have quite a few assumptions and limitations and hence the effectiveness evaluations reported may not be transferable or comparable.
Methods: This study seeks to develop a generalized evaluation scheme that can be used not only to assess the effectiveness of IMA on improving traffic safety at intersections but to facilitate comparisons across similar studies. The proposed evaluation scheme utilizes the concepts of traffic conflict in terms of time-to-collision (TTC) as a crash surrogate. This approach avoids the issue of having insufficient crash frequency data for system evaluation. To measure the effectiveness of IMA on reducing traffic conflicts, a relative risk is calculated for comparing the risk of with/without using the IMA. As a proof-of-concept study, this study applied the proposed evaluation scheme and reported the effectiveness of IMA on improving traffic safety in a field operation test (FOT). Seven test scenarios were conducted at 4 intersections, and a total of 40 participants were recruited to use the IMA for 6 months.
Results: It was estimated that IMA users have 26% fewer conflicts with TTC less than 5 s and have 15% fewer conflicts with TTC less than 4 s. However, the results vary across different sites and different definitions of conflicts in terms of TTC.
Conclusions: Overall, IMA is promising to effectively reduce angle crashes related to sight obstruction and has potential to reduce not only crash frequency but crash severity.
The advent of connected vehicle technology brings forth a new set of possibilities for more efficient traffic control. Indeed, the ability to consider driver-specific attributes, such as value of ...time or willingness to pay, in intersection management through advanced communication protocols allows for reducing individual delay costs. In this context, this study presents an auction-based approach for signalized intersection control under a connected vehicle setting. A second-price sealed-bid auction is employed to assign green time to conflicting movements, while driver bids and bidding distance per lane vary based on delay accumulation. The proposed auction-based control is evaluated using various demand levels and flow patterns and compared against pre-timed signal control. Results show that the proposed mechanism may be a promising alternative for several flow patterns, achieving lower average delays while maintaining fairness.
•We present an unconditionally secure quantum Private Set Intersection Cardinality protocol, which requires O(1) communication cost.•We propose a novel anonymous authentication scheme, which can not ...only achieve two basic secure goals: secure authentication and anonymity, but can also easily and dynamically update the authorized clients.
In this paper, we proposed an unconditionally secure quantum Private Set Intersection Cardinality (PSI-CA) protocol. Compared with classical PSI-CA protocols, the proposed protocol can dramatically reduce the communication complexity, because it only requires O(1) communication cost, which is fully independent of the size of the sets. Furthermore, based on the proposed quantum PSI-CA protocol, we constructed a novel anonymous authentication scheme. This scheme can not only achieve two basic secure goals: secure authentication and anonymity, but can also dynamically update the authorized clients. When revoking any authorized client or adding a new client, it only needs to simply compute several set operations without any complex cryptographic operation, and thus it is very suitable for applications in some dynamic environments, e.g., large-scale client-server networks.
•We model the dynamics of crossing pedestrian streams at four-way intersections.•Experimental data and Approximate Bayesian Computation are used for model selection.•We show that at high inflow rates ...interactions between entire streams emerge.•When four streams intersect some streams may move whilst others are jammed.•Thus, intersections may influence pedestrian flows beyond their immediate vicinity.
The interactions between individual pedestrians can lead to emergent effects, such as the formation of lanes in bidirectional flows. Here, we expose properties of an emergent effect at a macroscopic level, namely interactions between pedestrian streams that arise when pedestrians walk into and through four-way intersections from different directions. We propose non-spatial models for the number of pedestrians from different streams inside an intersection. Each model encodes a different hypothesis for how streams interact and can produce dynamics fundamentally distinct from the other models. By fitting our models to large experimental data sets and determining which model explains the data best, we determine when and how entire streams of pedestrians start to interact. We find that as arrival rates increase, streams start to interact and compete for space. Our results suggest that these interactions result in an even balance of pedestrian numbers across two orthogonally intersecting streams. Neither of the streams can dominate. In contrast, for four intersecting streams, our findings suggest that jams in some streams can coincide with higher flow rates in other streams and that the relative dominance of streams can switch stochastically. By adapting existing methodology, we thus present a coherent conceptual approach for investigating emergent effects in temporal dynamics at aggregated levels in pedestrian flows that could be applied to other scenarios. Our approach is flexible and uses easily measured quantities, making it highly suitable for observational data in different scenarios or deployment in applications.
Display omitted
Let
V
be a set of
n
vertices,
M
a set of
m
labels, and let
R
be an
m
×
n
matrix ofs independent Bernoulli random variables with probability of success
p
; columns of
R
are incidence vectors of label ...sets assigned to vertices. A random instance
G
(
V
,
E
,
R
T
R
)
of the weighted random intersection graph model is constructed by drawing an edge with weight equal to the number of common labels (namely
R
T
R
v
,
u
) between any two vertices
u
,
v
for which this weight is strictly larger than 0. In this paper we study the average case analysis of
Weighted Max Cut
, assuming the input is a weighted random intersection graph, i.e. given
G
(
V
,
E
,
R
T
R
)
we wish to find a partition of
V
into two sets so that the total weight of the edges having exactly one endpoint in each set is maximized. In particular, we initially prove that the weight of a maximum cut of
G
(
V
,
E
,
R
T
R
)
is concentrated around its expected value, and then show that, when the number of labels is much smaller than the number of vertices (in particular,
m
=
n
α
,
α
<
1
), a random partition of the vertices achieves asymptotically optimal cut weight with high probability. Furthermore, in the case
n
=
m
and constant average degree (i.e.
p
=
Θ
(
1
)
n
), we show that with high probability, a majority type randomized algorithm outputs a cut with weight that is larger than the weight of a random cut by a multiplicative constant strictly larger than 1. Then, we formally prove a connection between the computational problem of finding a (weighted) maximum cut in
G
(
V
,
E
,
R
T
R
)
and the problem of finding a 2-coloring that achieves minimum discrepancy for a set system
Σ
with incidence matrix
R
(i.e. minimum imbalance over all sets in
Σ
). We exploit this connection by proposing a (weak) bipartization algorithm for the case
m
=
n
,
p
=
Θ
(
1
)
n
that, when it terminates, its output can be used to find a 2-coloring with minimum discrepancy in a set system with incidence matrix
R
. In fact, with high probability, the latter 2-coloring corresponds to a bipartition with maximum cut-weight in
G
(
V
,
E
,
R
T
R
)
. Finally, we prove that our (weak) bipartization algorithm terminates in polynomial time, with high probability, at least when
p
=
c
n
,
c
<
1
.
Autonomous intersection management (AIM) has been widely researched, but previous studies assume that vehicles will follow assigned trajectories precisely. The purpose of this paper is to investigate ...the safety buffers needed between intersecting vehicles to avoid a collision if a vehicle malfunctions. We optimize vehicle trajectories by deciding the arrival times at each conflict point (point of possible intersection with other vehicles) along each vehicle's trajectory. Because intersecting vehicles rely on the intersection manager (IM) to detect and communicate malfunctions, the reaction time from the IM determines the minimum safety buffer needed. Although a smaller reaction time reduces the safety buffer, it increases the probability that the IM falsely detects a malfunction, instructing vehicles to stop and creating unnecessary delays. This paper develops a mathematical safety buffer for intersecting vehicles, linearizes this time separation, and constructs a combined mixed-integer linear program. A complete protocol is presented and simulated for normal circumstances, emergency circumstances, and recovery circumstances. Sensitivity analyses on various reaction times show the tradeoff between low reaction times (more false positives) and high reaction times (greater safety buffer).
PDF
