Junjie Zhang

Mr. Junjie Zhang


Research Focus & Metrics

Academic Career Length

14Years (2013-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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21 July 2016 in Physical Review E
Verified
Journal Article
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SCShuchao Cao
Shuchao Cao
JZJunjie Zhang
Junjie Zhang
DSDaniel Salden
Daniel Salden
JMJian Ma
Jian Ma
CSChang'AN Shi
Chang'AN Shi
RZRuifang Zhang
Ruifang Zhang
An aging population is bringing new challenges to the management of escape routes and facility design in many countries. This paper investigates pedestrian movement properties of crowd with different age compositions. Three pedestrian groups are considered: young student group, old people group, and mixed group. It is found that traffic jams occur more frequently in mixed group due to the great differences of mobilities and self-adaptive abilities among pedestrians. The jams propagate backward with a velocity 0.4m/s for global density ρg≈1.75m−1 and 0.3m/s for ρg>2.3m−1. The fundamental diagrams of the three groups are obviously different from each other and cannot be unified into one diagram by direct nondimensionalization. Unlike previous studies, three linear regimes in mixed group but only two regimes in young student group are observed in the headway-velocity relation, which is also verified in the fundamental diagram. Different ages and mobilities of pedestrians in a crowd cause the heterogeneity of system and influence the properties of pedestrian dynamics significantly. It indicates that the density is not the only factor leading to jams in pedestrian traffic. The composition of crowd has to be considered in understanding pedestrian dynamics and facility design.

2 September 2013
Verified
Book Chapter
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JZJunjie Zhang
Junjie Zhang
WKW. Klingsch
W. Klingsch
ASAndreas Schadschneider
Andreas Schadschneider
ASArmin Seyfired
Armin Seyfired

12 June 2025 in IEEE Transactions on Power Systems
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Journal Article
Open access
CHCarsten Hartmann
Carsten Hartmann
JZJunjie Zhang
Junjie Zhang
CCCarlos D. Gonzalez Calaza
Carlos D. Gonzalez Calaza
TPThiemo Pesch
Thiemo Pesch
KMKristel Michielsen
Kristel Michielsen
ABAndrea Benigni
Andrea Benigni
Graph partitioning has many applications in power systems, from decentralized state estimation to parallel simulation. Focusing on parallel simulation, optimal grid partitioning minimizes the idle time caused by different simulation times for the sub-networks and their components and reduces the overhead required to simulate the cuts. Partitioning a graph into two parts such that, for example, the cut is minimal and the sub-graphs have equal size is an NP-hard problem. In this paper, we show how optimal partitioning of a graph can be obtained using quantum annealing (QA). We show how to map the requirements for optimal splitting to a quadratic unconstrained binary optimization (QUBO) formulation and test the proposed formulation using a current D-Wave QPU. We show that the necessity to find an embedding of the QUBO on current D-Wave QPUs limits the problem size to under 200 buses and notably affects the time-to-solution. We finally discuss the implications of quantum hardware non-ideality on near term implementation in the simulation loop.

1 June 2021 in Electronics
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Journal Article
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JZJunjie Zhang
Junjie Zhang
LRLukas Razik
Lukas Razik
SJSigurd Hofsmo Jakobsen
Sigurd Hofsmo Jakobsen
SDSalvatore D'arco
Salvatore D'arco
ABAndrea Benigni
Andrea Benigni
In this paper we introduce an approach to accelerate many-scenario (i.e., hundreds to thousands) power system simulations which is based on a highly scalable and flexible open-source software environment. In this approach, the parallel execution of simulations follows the single program, multiple data (SPMD) paradigm, where the dynamic simulation program is executed in parallel and takes different inputs to generate different scenarios. The power system is modeled using an existing Modelica library and compiled to a simulation executable using the OpenModelica Compiler. Furthermore, the parallel simulation is performed with the aid of a message-passing interface (MPI) and the approach includes dynamic workload balancing. Finally, benchmarks with the simulation environment are performed on high-performance computing (HPC) clusters with four test cases. The results show high scalability and a considerable parallel speedup of the proposed approach in the simulation of all scenarios.

8 May 2024 in International Journal of Electrical Power & Energy Systems
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Journal Article
Open access
JZJunjie Zhang
Junjie Zhang
MMMarcel Mittenbühler
Marcel Mittenbühler
ABAndrea Benigni
Andrea Benigni

28 June 2024 in Electric Power Systems Research
Verified
Journal Article
Open access
MMMarcel Mittenbühler
Marcel Mittenbühler
JZJunjie Zhang
Junjie Zhang
ABAndrea Benigni
Andrea Benigni