timetable
Fat Bear Week bracket is set: meet the heavyweights, underdogs and defending champ in this year's tournament
Riley Green drops 19-track album'That's Just Me' and country music fans can't get enough Attorney reveals Lane Kiffin used ChatGPT for legal advice during LSU's failed bid to add pro players Baker Mayfield loses bet to coach Todd Bowles, has'rough couple of days' including at press conference Falcons star Kyle Pitts Sr predicts CFB players will unionize, says pro players returning to school is'crazy' New trailer for'Other Mommy' with Jessica Chastain reveals a sinister entity terrorizing a young girl'God has been so good to me': Ella Langley reacts to incredible nine CMA Awards nominations'How can you fight during a love song?' Riley Green defuses crowd fight at New Mexico show Netflix drops full trailer for Ben Affleck's'Animals' and expectations are already soaring Dan Lanning spars with reporter after Dante Moore misses media following Oregon's loss to Oklahoma State Best hikes to try around Lubbock ahead of Texas Tech's week one matchup with Abilene Christian Elon Musk's mom uses Grok 10x times a day. "Why Does The NCAA Even Exist?" Craig Carton TORCHES Its Pathetic Michigan Hail Mary Statement | The Craig Carton Show OutKick Outdoors Fat Bear Week bracket is set: meet the heavyweights, underdogs and defending champ in this year's tournament A mother bear charges a young male after he moves toward her two cubs and their prime salmon fishing spot at Alaska's Crescent Lake. The most important bracket of the year has arrived. Fat Bear Week is back, baby! The annual competition at Alaska's Katmai National Park and Preserve kicks off Tuesday with 16 brown bears vying for the title of chonkiest champ.
Timetable Nodes for Public Transport Network
Rohovyi, Andrii, Stuckey, Peter J., Walsh, Toby
Faster pathfinding in time-dependent transport networks is an important and challenging problem in navigation systems. There are two main types of transport networks: road networks for car driving and public transport route network. The solutions that work well in road networks, such as Time-dependent Contraction Hierarchies and other graph-based approaches, do not usually apply in transport networks. In transport networks, non-graph solutions such as CSA and RAPTOR show the best results compared to graph-based techniques. In our work, we propose a method that advances graph-based approaches by using different optimization techniques from computational geometry to speed up the search process in transport networks. We apply a new pre-computation step, which we call timetable nodes (TTN). Our inspiration comes from an iterative search problem in computational geometry. We implement two versions of the TTN: one uses a Combined Search Tree (TTN-CST), and the second uses Fractional Cascading (TTN-FC). Both of these approaches decrease the asymptotic complexity of reaching new nodes from $O(k\times \log|C|)$ to $O(k + \log(k) + \log(|C|))$, where $k$ is the number of outgoing edges from a node and $|C|$ is the size of the timetable information (total outgoing edges). Our solution suits any other time-dependent networks and can be integrated into other pathfinding algorithms. Our experiments indicate that this pre-computation significantly enhances the performance on high-density graphs. This study showcases how leveraging computational geometry can enhance pathfinding in transport networks, enabling faster pathfinding in scenarios involving large numbers of outgoing edges.
Reinforcement Learning for Scalable Train Timetable Rescheduling with Graph Representation
Yue, Peng, Jin, Yaochu, Dai, Xuewu, Feng, Zhenhua, Cui, Dongliang
Train timetable rescheduling (TTR) aims to promptly restore the original operation of trains after unexpected disturbances or disruptions. Currently, this work is still done manually by train dispatchers, which is challenging to maintain performance under various problem instances. To mitigate this issue, this study proposes a reinforcement learning-based approach to TTR, which makes the following contributions compared to existing work. First, we design a simple directed graph to represent the TTR problem, enabling the automatic extraction of informative states through graph neural networks. Second, we reformulate the construction process of TTR's solution, not only decoupling the decision model from the problem size but also ensuring the generated scheme's feasibility. Third, we design a learning curriculum for our model to handle the scenarios with different levels of delay. Finally, a simple local search method is proposed to assist the learned decision model, which can significantly improve solution quality with little additional computation cost, further enhancing the practical value of our method. Extensive experimental results demonstrate the effectiveness of our method. The learned decision model can achieve better performance for various problems with varying degrees of train delay and different scales when compared to handcrafted rules and state-of-the-art solvers.
Robustness Approaches for the Examination Timetabling Problem under Data Uncertainty
In the literature the examination timetabling problem (ETTP) is often considered a post-enrollment problem (PE-ETTP). In the real world, universities often schedule their exams before students register using information from previous terms. A direct consequence of this approach is the uncertainty present in the resulting models. In this work we discuss several approaches available in the robust optimization literature. We consider the implications of each approach in respect to the examination timetabling problem and present how the most favorable approaches can be applied to the ETTP. Afterwards we analyze the impact of some possible implementations of the given robustness approaches on two real world instances and several random instances generated by our instance generation framework which we introduce in this work.
A Mobile Data-Driven Hierarchical Deep Reinforcement Learning Approach for Real-time Demand-Responsive Railway Rescheduling and Station Overcrowding Mitigation
Liu, Enze, Lin, Zhiyuan, Wang, Judith Y. T., Chen, Hong
Real-time railway rescheduling is an important technique to enable operational recovery in response to unexpected and dynamic conditions in a timely and flexible manner. Current research relies mostly on OD based data and model-based methods for estimating train passenger demands. These approaches primarily focus on averaged disruption patterns, often overlooking the immediate uneven distribution of demand over time. In reality, passenger demand deviates significantly from predictions, especially during a disaster. Disastrous situations such as flood in Zhengzhou, China in 2022 has created not only unprecedented effect on Zhengzhou railway station itself, which is a major railway hub in China, but also other major hubs connected to Zhengzhou, e.g., Xi'an, the closest hub west of Zhengzhou. In this study, we define a real-time demand-responsive (RTDR) railway rescheduling problem focusing two specific aspects, namely, volatility of the demand, and management of station crowdedness. For the first time, we propose a data-driven approach using real-time mobile data (MD) to deal with this RTDR problem. A hierarchical deep reinforcement learning (HDRL) framework is designed to perform real-time rescheduling in a demand-responsive manner. The use of MD has enabled the modelling of passenger dynamics in response to train delays and station crowdedness, and a real-time optimisation for rescheduling of train services in view of the change in demand as a result of passengers' behavioural response to disruption. Results show that the agent can steadily satisfy over 62% of the demand with only 61% of the original rolling stock, ensuring continuous operations without overcrowding. Moreover, the agent exhibits adaptability when transferred to a new environment with increased demand, highlighting its effectiveness in addressing unforeseen disruptions in real-time settings.
Optimizing Energy Efficiency in Metro Systems Under Uncertainty Disturbances Using Reinforcement Learning
Xie, Haiqin, Wang, Cheng, Li, Shicheng, Zhang, Yue, Wang, Shanshan
In the realm of urban transportation, metro systems serve as crucial and sustainable means of public transit. However, their substantial energy consumption poses a challenge to the goal of sustainability. Disturbances such as delays and passenger flow changes can further exacerbate this issue by negatively affecting energy efficiency in metro systems. To tackle this problem, we propose a policy-based reinforcement learning approach that reschedules the metro timetable and optimizes energy efficiency in metro systems under disturbances by adjusting the dwell time and cruise speed of trains. Our experiments conducted in a simulation environment demonstrate the superiority of our method over baseline methods, achieving a traction energy consumption reduction of up to 10.9% and an increase in regenerative braking energy utilization of up to 47.9%. This study provides an effective solution to the energy-saving problem of urban rail transit.
Argelich
We present a random generator of partially complete round robin timetables that produces exclusively satisfiable instances, and provide experimental evidence that there is an easy-hard-easy pattern in the computational difficulty of completing partially complete timetables as the ratio of the number of removed entries to the total number of entries of the timetable is varied. Timetables in the hard region provide a suitable test-bed for evaluating and fine-tuning local search algorithms.
US sanction forces China's AI firm SenseTime to delay IPO
Chinese artificial intelligence start-up SenseTime Group has postponed its $767m Hong Kong initial public offering (IPO) after being placed on a US investment blacklist. SenseTime said it remained committed to completing the offering and would publish a supplemental prospectus and an updated listing timetable. Reuters first reported earlier on Monday the company's plan to withdraw the offering and update its prospectus to include the potential impact of the US investment ban, with the aim of relaunching the IPO process. SenseTime had planned to sell 1.5 billion shares in a price range of HK$3.85 ($0.49) to HK$3.99 ($0.51), according to its regulatory filings. That would raise up to $767m, a figure that had already been trimmed earlier this year from a $2bn target.
Solving Large Break Minimization Problems in a Mirrored Double Round-robin Tournament Using Quantum Annealing
Kuramata, Michiya, Katsuki, Ryota, Nakata, Kazuhide
Quantum annealing (QA) has gained considerable attention because it can be applied to combinatorial optimization problems, which have numerous applications in logistics, scheduling, and finance. In recent years, research on solving practical combinatorial optimization problems using them has accelerated. However, researchers struggle to find practical combinatorial optimization problems, for which quantum annealers outperform other mathematical optimization solvers. Moreover, there are only a few studies that compare the performance of quantum annealers with one of the most sophisticated mathematical optimization solvers, such as Gurobi and CPLEX. In our study, we determine that QA demonstrates better performance than the solvers in the break minimization problem in a mirrored double round-robin tournament (MDRRT). We also explain the desirable performance of QA for the sparse interaction between variables and a problem without constraints. In this process, we demonstrate that the break minimization problem in an MDRRT can be expressed as a 4-regular graph. Through computational experiments, we solve this problem using our QA approach and two-integer programming approaches, which were performed using the latest quantum annealer D-Wave Advantage, and the sophisticated mathematical optimization solver, Gurobi, respectively. Further, we compare the quality of the solutions and the computational time. QA was able to determine the exact solution in 0.05 seconds for problems with 20 teams, which is a practical size. In the case of 36 teams, it took 84.8 s for the integer programming method to reach the objective function value, which was obtained by the quantum annealer in 0.05 s. These results not only present the break minimization problem in an MDRRT as an example of applying QA to practical optimization problems, but also contribute to find problems that can be effectively solved by QA.
Optimising Rolling Stock Planning including Maintenance with Constraint Programming and Quantum Annealing
Grozea, Cristian, Hans, Ronny, Koch, Matthias, Riehn, Christina, Wolf, Armin
We developed and compared Constraint Programming (CP) and Quantum Annealing (QA) approaches for rolling stock optimisation considering necessary maintenance tasks. To deal with such problems in CP we investigated specialised pruning rules and implemented them in a global constraint. For the QA approach, we developed quadratic unconstrained binary optimisation (QUBO) models. For testing, we use data sets based on real data from Deutsche Bahn and run the QA approach on real quantum computers from D-Wave. Classical computers are used to run the CP approach as well as tabu search for the QUBO models. We find that both approaches tend at the current development stage of the physical quantum annealers to produce comparable results, with the caveat that QUBO does not always guarantee that the maintenance constraints hold, which we fix by adjusting the QUBO model in preprocessing, based on how close the trains are to a maintenance threshold distance.