Continuous Obstructed Detour Queries

In this paper, we introduce Continuous Obstructed Detour (COD) Queries, a novel query type in spatial databases. COD queries continuously return the nearest point of interests (POIs) such as a restaurant, an ATM machine and a pharmacy with respect to the current location and the fixed destination of a moving pedestrian in presence of obstacles like a fence, a lake or a private building. The path towards a destination is typically not predetermined and the nearest POIs can change over time with the change of a pedestrian\u27s current location towards a fixed destination. The distance to a POI is measured as the summation of the obstructed distance from the pedestrian\u27s current location to the POI and the obstructed distance from the POI to the pedestrian\u27s destination. Evaluating the query for every change of a pedestrian\u27s location would incur extremely high processing overhead. We develop an efficient solution for COD queries and verify the effectiveness and efficiency of our solution in experiments

Updating the Bridge Construction Cost Database

Adopting a comprehensive suite of methods to track, analyze, and maintain data on bridge construction costs can help state transportation agencies identify and implement strategies to mitigate the influence of factors which escalate project costs. This report discusses how the Kentucky Transportation Cabinet (KYTC) should approach updating, maintaining, and analyzing its bridge construction cost data. Based on a review of practices introduced at other agencies and interviews with public and private industry stakeholders, the report catalogues practical strategies for improving estimating procedures and tracking cost data as well as the most important cost drivers of bridge construction. Analysis of KYTC data on average unit bid prices for eight key bid items on bridge projects found that prices went up for every item between 2015 and 2021. Steel reinforcement and epoxy coated steel reinforcement displayed the most consistent linear upward trend, while greater variability was noticeable in prices for Class A and AA concrete and foundation preparation. This analysis substantiated observations by interviewees that contractors submit higher bid prices when they perceive greater risk associated with a work item. Recommendations for process improvements at the Cabinet focus on agencywide rollout of AASHTOWare Estimation, conducting post-construction reviews, establishing contract durations that reasonably accommodate the completion of all work, and performing more in-depth geotechnical investigations

Construction Project Administration and Management for Mitigating Work Zone Crashes and Fatalities: An Integrated Risk Management Model

The goal of this research is to mitigate the risk of highway accidents (crashes) and fatalities in work zones. The approach of this research has been to address the mitigation of work zone crashes through the creation of a formal risk management model to be utilized during the construction management and administration of highway projects for all stages of the project life-cycle. The result of these efforts is realized through the design of an integrated risk management model. A standard risk management model has three components: risk identification, risk analysis, and risk response. The risks are identified by the factors that contribute to work zone crashes. The risk analysis involves understanding the tendency of a hazard to influence the frequency or severity of a loss, and the risk response relates to the appropriate countermeasures to the factors that contribute to work zone crashes. The number of hazards and mitigation strategies corresponding to work zone crashes can be substantial. The intent of this research is to develop a formalized risk management plan to identify potential hazards on plans, designs, or jobsites and to cue a risk response to the hazards. Mitigation strategies may take the form of a mitigation “method” (alert motorist, assist worker/motorist, control motorist, inform motorist, and protect worker/motorist). The results of this research will be a formal step-by-step methodology to be utilized by managers and decision makers. Each stage of the project life-cycle (or Project Development Process) will provide a checklist of hazards and mitigation strategies. This research will also provide a qualitative method to assess the likelihood and severity of a hazard or multiple hazards on a roadway work zone. This research is intended to provide a holistic approach to risk management that is to be integrated into the existing corporate structure and not to be considered a standalone program. This integrated approach will allow a formalized procedure to be utilized by any member of an organization during all phases of the construction project life-cycle

Design for Manufacturability in Advanced Lithography Technologies

As the technology nodes keep shrinking following Moore\u27s law, lithography becomes increasingly critical to the fabrication of integrated circuits. The 193nm ArF immersion lithography (193i) has been a common technique for manufacturing integrated circuits. However, the 193i with single exposure has finally reached its printability limit at the 28nm technology node. To keep the pace of Moore\u27s law, design for manufacturability (DFM) is demonstrated to be effective and cost-efficient. The concept of DFM is to modify the design of integrated circuits in order to make them more manufacturable. Tremendous efforts have been made for DFM in advanced lithography technologies. In general, the progress can be summarized in four directions. (1) Advanced lithography process by novel patterning techniques and next-generation lithography; (2) High performance lithography simulation approach in mask synthesis; (3) Physical design (PD) methodology with lithography manufacturability awareness; (4) Robust design flow integrating emerging PD challenges. Accordingly, we propose our research topics in those directions. (1) Throughput optimization for self-aligned double patterning (SADP) and e-beam lithography based manufacturing of 1D layout; (2) Design of efficient rasterization algorithm for mask patterns in inverse lithography technology (ILT); (3) SADP-aware detailed routing; (4) SADP-aware detailed routing with consideration of double via insertion and via manufacturability; (5) Pin accessibility driven detailed placement refinement. In our first research work, we investigate throughput optimization of 1D layout manufacturing. SADP is a mature lithography technique to print 1D gridded layout for advanced technologies. However, in 16nm technology node, trim mask pattern in SADP lithography process may not be printable using 193i along within a single exposure. A viable solution is to complement SADP with e-beam lithography. To order to increase the throughput of 1D layout manufacturing, we consider the problem of e-beam shot minimization subject to bounded line-end extension constraints. Two different approaches of utilizing the trim mask and e-beam to print a 1D layout are considered. The first approach is trimming by end cutting, in which trim mask and e-beam are used to chop up parallel lines at required locations by small fixed rectangles. The second approach is trimming by gap removal, in which trim mask and e-beam are used to rid of all unnecessary portions. We propose elegant integer linear program formulations for both approaches. Experimental results show that both integer linear program formulations can be solved efficiently and have a major speedup compared with previous related work. Furthermore, the pros and cons of the two approaches for manufacturing 1D layout are discussed. In our second research work, we focus on a critical problem of lithography simulation in the design of ILT mask. To reduce the complexity of modern lithography simulation, a widely used approach is to first rasterize the ILT mask before it is inputted to the simulation tool. Accordingly, we propose a high performance rasterization algorithm. The algorithm is based on a pre-computed look-up table. Every pixel in the rasterized image is firstly identified its category: exception or non-exception. Then convolution for every pixel can be performed by a single or multiple look-up table queries depending on its category. In addition, the proposed algorithm has shift invariant property and can be applied for all-angle mask patterns in ILT. Experimental results demonstrate that our approach can speedup conventional rasterization process by almost 500x while maintaining small variations in critical dimension. In our third research work, we concentrate on SADP-aware detailed routing. SADP is a promising manufacturing option for sub-22nm technology nodes due to its good overlay control. To ensure layout is manufacturable by SADP, it is necessary to consider it during layout configuration, e.g., detailed routing stage. However, SADP process is not intuitive in terms of mask design, and considering it during detailed routing stage is even more challenging. We investigate both of two popular types of SADP: spacer-is-dielectric and spacer-is-metal. Different from previous works, we apply the color pre-assignment idea and propose an elegant graph model which captures both routing and SADP manufacturing cost. They greatly simplify the problem to maintain SADP design rules during detailed routing. A negotiated congestion based rip-up and reroute scheme is applied to achieve good routability while maintaining SADP design rules. Our approach can be extended to consider other multiple patterning lithography during detailed routing, e.g., self-aligned quadruple patterning targeted at sub-10nm technology nodes. Compared with state-of-the-art academic SADP-aware detailed routers, we offer routing solution with better quality of result. In our fourth research work, we extend our SADP-aware detailed routing to consider other manufacturing issues. Both SADP and triple patterning lithography (TPL) are potential layout manufacturing techniques in 10nm technology node. While metal layers can be printed by SADP, via layer manufacturing requires TPL. Previous works on SADP-aware detailed routing do not automatically guarantee via layer are manufacturable by TPL. We extend our SADP-aware detailed routing to consider TPL manufacturability of via layer. Double via insertion is an effective method to improve yield and reliability in integrated circuits manufacturing. We also consider it in our SADP-aware detailed routing to further improve insertion rate. A problem of TPL-aware double via insertion in the post routing stage is proposed. It is solved by both integer linear programming and high-performance heuristic. Experimental results demonstrate that our SADP-aware detailed routing can ensure via layer are TPL manufacturable and improve double via insertion rate. In our last research work, we target at the enhancement of pin access. The significant increased number of routing design rules in advanced technologies has made pin access an emerging difficultly in detailed routing. Resolving pin access in detailed routing may be too late due to the fix pin locations. Thus, we consider pin access in earlier design stage, i.e., detailed placement stage, when perturbation of cell placement is allowed. A cost function is proposed to model pin access for each pin-to-pin connection in detailed routing. A two-phase detailed placement refinement is performed to improve pin access, and refinement techniques are limited to cell flipping, same-row adjacent cell swap and cell shifting. The problem is solved by dynamic programming and linear programming. Experimental results demonstrate that the proposed detailed placement refinement improve pin access and reduce the number of unroutable nets in detailed routing significantly

Construction project administration and management for mitigating work zone crashes and fatalities: An integrated risk management model

Each year in the United States hundreds of people die in automobile crashes in highway work zones and tens of thousands of motorists suffer injury or property damage due to crashes in highway work zones. The traveling public, designers, department of transportation agencies, and contractors will all benefit from research aimed at the reduction of crashes in highway work zones. Although much past research has delved into the various causes of work zone crashes and the various strategies to mitigate work zone crashes, little effort has been given to the overall management of the risks associated with work zone crashes. The goal of this research is to develop a new, integrated approach to the management of these risks. This goal is achieved through the development of a formal integrated risk management model to be utilized during the construction management and administration of highway projects for all stages of the project lifecycle. Within this integrated risk management program, validation and application of the model is accomplished by focusing on the three components of the standard risk management model: risk identification, risk analysis, and risk response. This project requires a multi-faceted research approach employing several methodologies. With the exception of the risk assessment portion of this research, the methodology for this project is primarily qualitative, using focus groups, surveys, personal interviews, and content analysis to identify work zone risks, mitigating strategies and the proper stakeholders and project phases in which to implement mitigating strategies. The model validation phase of this research involves qualitative assessments along with an analytic assessment of work zone hazards through database queries into a statewide crash database to produce a risk matrix tool. The risk matrix tool is a two dimensional representation of the frequency and severity of crashes with specific characteristics (hazards) that are associated with the crash and can be used by a risk management team to prioritize their responses to work zone risk

Heuristic Path Finding Method for Online Game Environment.

Pathfinding is one of the main problems for computer gaming. It has long been a bottleneck for system performance in the online game industry. Due to the vast amount of pathfinding requests and attributes of game maps, many pathfinding methods that work well for the console game environment have failed the challenges of online games. In order to obtain a satisfactory performance, the background processing system has to sacrifice either efficiency or accuracy otherwise it would require a hardware improvement. Therefore, after investigating possible solutions to resolve these common issues of pathfinding, we have designed a Heuristic Path Finding Method. Under this method, designers analyze the game map structure and build area information first. The online game system will then generate path templates for in-game usage based on the map information. As the templates are being generated, the system's pathfinding Artificial Intelligence (AI) will pick a path from the templates and adjust it accordingly to produce a real path. This method improves pathfinding tasks with higher accuracy, is less time consuming and requires fewer resources from the game system. We have also created a testing system as a tool for testing and evaluating pathfinding related work. We carried out a series of experiments with the testing system on the online game service, and showed us that our method is a better solution than a few known algorithms.--P. i.The original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b173777

Shortest path queries in rectilinear worlds

Abstract In this paper, a data structure is given for two and higher dimensional shortest path queries. For a set of n axis-parallel rectangles in the plane, or boxes in d-space, and a fixed target, it is possible with this structure to find a shortest rectilinear path avoiding all rectangles or boxes from any point to this target. Alternatively, it is possible to find the length of the path. The metric considered is a generalization of the Ll-metric and the link metric, where the length of a path is its L1-Iength plus some (fixed) constant times the number of turns on the path. The data structure has size 0« n log n )d-l), and a query takes O(logd-l n) time (plus the output size if the path must be reported). As a byproduct, a relatively simple solution to the single shot problem is obtained; the shortest path between two given points can be computed in time O(ndlogn) for d ~ 3, and in time 0(n 2 ) in the plane

Next Generation Traffic Signal Performance Measures: Leveraging Connected Vehicle Data

High-resolution connected vehicle (CV) trajectory and event data has recently become commercially available. With over 500 billion vehicle position records generated each month in the United States, these data sets provide unique opportunities to build on and expand previous advances on traffic signal performance measures and safety evaluation. This report is a synthesis of research focused on the development of CV-based performance measures. A discussion is provided on data requirements, such as acquisition, storage, and access. Subsequently, techniques to reference vehicle trajectories to relevant roadways and movements are presented. This allows for performance analyses that can range from the movement- to the system-level. A comprehensive suite of methodologies to evaluate signal performance using vehicle trajectories is then provided. Finally, uses of CV hard-braking and hard-acceleration event data to assess safety and driver behavior are discussed. To evaluate scalability and test the proposed techniques, performance measures for over 4,700 traffic signals were estimated using more than 910 million vehicle trajectories and 14 billion GPS points in all 50 states and Washington, D.C. The contents of this report will help the industry transition towards a hybrid blend of detector- and CV-based signal performance measures with rigorously defined performance measures that have been peer-reviewed by both academics and industry leaders