CORRELATED FACILITY DISRUPTION
- Designed an overarching model framework for facility location design under correlated facility disruptions
- Introduced the idea of supporting station structure to decompose any type of facility correlations
- Proposed a mixed-integer model and Lagrangian relaxation based algorithms to solve the RFL problem
RELIABLE SENSOR DEPLOYMENT
- Optimized sensor deployment locations to maximize system-wide positioning/surveillance benefits
- Incorporated the risk of site-dependent probabilistic sensor disruptions into the optimization framework
- Developed a compact mixed-integer programming model and designed several customized algorithms
RELIABLE NETWORK DISTRICTING
- Designed mixed-integer models for reliable network districting problems with multiple practical criteria
- Developed both customized heuristic algorithms and column-generation based algorithms
- Used by CSX Transportation Inc to solve their large-scale districting applications (e.g., call center design)
LOCOMOTIVE INFRASTRUCTURE
- Developed large-scale mixed-integer mathematical models and decomposition-based solution algorithms
- Numerous field studies demonstrated significant superiority of the model solutions over the current practice
- Used proactively by CSX Transportation Inc and have realized annual savings of more than $10 millions
NETWORK TRAVERSAL SCHEDULING
- Designed mathematical programs and heuristic algorithms to schedule periodic traversal of network vertices
- Developed graph packages with implementations of multiple data structures and graph algorithms (e,g., BFS/DFS, Dijkstra’s, Floyd-Warshall, Ford-Fulkerson)
- Used by CSX Transportation Inc to solve their grinder scheduling problems
FAILURE PREDICTION
- Applied machine learning techniques (e.g., SVM, kernel) to learn an traffic/railroad incident prediction model
- Used customized simulation-based over-sampling technique to handle the issue of data unbalance
- Implemented the cross-validation approach in Matlab to evaluate the model in terms of precision and recall
PHASE SWAP STRATEGY
- Proposed an operational paradigm for the phase swap sorting strategy to increase capacity of intersections
- Built a mixed-integer model to formulate the paradigm with both geometric and signal timings decisions
- Implemented the paradigm into simulation programs to visualize and validate the proposed model solutions
UNCONVENTIONAL INTERSECTION DESIGN
- Proposed a new unconventional intersection design to increase the capacity of isolated intersections
- Built a mixed-integer model to formulate the paradigm with both geometric and signal timings decisions
- Conducted numerical experiments to quantify the benefit of the proposed design against the conventional design