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1. Kraft, Aaron R. Abstraction Hierarchies for Multi-Agent Pathfinding.

Degree: MS, Computer Science, 2017, U of Denver

Multi-Agent Pathfinding is an NP-Complete search problem with a branching factor that is exponential in the number of agents. Because of this exponential feature, it can be difficult to solve optimally using traditional search techniques, even for relatively small problems. Many recent optimal solvers have attempted to reduce the complexity of the problem by resolving the conflicts between agent paths separately. Very little of this research has focused on creating quality heuristics to help solve the problem. In this thesis, we create heuristics using sub-problems created by removing agents from a complete problem instance. We combine this with the Independence Detection technique for solving the problem by separating agents into independent (non-conflicting) groups. The results showed moderate improvements in state expansions and computation time in problems with a large number of conflicting agents. Advisors/Committee Members: Nathan Sturtevant, Ph.D..

Subjects/Keywords: Heuristic; Heuristic Search; MAPF; Multi-Agent Pathfinding; Pathfinding; Path Planning; Computer Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Kraft, A. R. (2017). Abstraction Hierarchies for Multi-Agent Pathfinding. (Thesis). U of Denver. Retrieved from https://digitalcommons.du.edu/etd/1247

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Kraft, Aaron R. “Abstraction Hierarchies for Multi-Agent Pathfinding.” 2017. Thesis, U of Denver. Accessed November 12, 2019. https://digitalcommons.du.edu/etd/1247.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Kraft, Aaron R. “Abstraction Hierarchies for Multi-Agent Pathfinding.” 2017. Web. 12 Nov 2019.

Vancouver:

Kraft AR. Abstraction Hierarchies for Multi-Agent Pathfinding. [Internet] [Thesis]. U of Denver; 2017. [cited 2019 Nov 12]. Available from: https://digitalcommons.du.edu/etd/1247.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kraft AR. Abstraction Hierarchies for Multi-Agent Pathfinding. [Thesis]. U of Denver; 2017. Available from: https://digitalcommons.du.edu/etd/1247

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


New Jersey Institute of Technology

2. James, Gregory. Experimental and numerical study of flow characteristics and segregation in flow enhanced systems.

Degree: PhD, Mechanical Engineering, 2001, New Jersey Institute of Technology

In the study of granular materials, two major topics of importance are powder flow enhancement mechanisms and the flow characterization. This dissertation is involved with both of these topics. With respect to the powder flow enhancement, this study involves investigation of two types of flow enhancement methods. The first flow enhancement method examined is a novel method called the Magnetically Assisted Powder Flow (MAPF) method. In the MAPF, small magnetic particles and powders are placed in a test hopper. A mesh is placed at the bottom of the hopper to hold the magnetic particles while the powder is discharged through the mesh. It is shown that this method may be used for controlled discharge of cohesive powders and hence may be used also for cohesive powder flow characterization. Therefore this technique is utilized for the angle of repose (AOR) measurements, which is the most convenient and popular method used in industry for powder characterization. It is found that many factors affect the results obtained for AOR, including the technique of measurement. The AOR measurement through MAPF method is developed and the effects of various variables including the dropping height, mass of the powder used in the hopper, magnetic field strength, hopper position in the magnetic field, mass of magnetic particles hopper outlet area and mesh size are evaluated. This novel AOR measurement method is found to be more reliable and easier to use. The second flow enhancement method examined is the use of vibration, which is currently a commonly applied industrial method to enhance powder flow. However, it is well known that vibration causes segregation due to the difference in particle size or density and thus causes certain adverse effects on products. In order to understand the mechanisms of segregation in vibrating systems, a systematic study of vibrated hoppers with mono-disperse as well as binary system of particles is carried out. This includes physical experiments as well a computer model using the Discrete Element Method (DEM) to simulate the model system. The first part of the study involves hoppers with the outlet closed, and includes experiments and simulations. The effects of various system parameters are investigated and several important regimes of behavior are identified based on the state diagram of dimensionless amplitude and frequency of applied vibrations. A plausible explanation through the experimental and simulation results is given for one of the most interesting regimes, where the hopper surface is inclined (i.e. forms a heap). It is shown that this occurs due to the existence of lateral (i.e. horizontal) vibration mode. For the binary system, mixtures of equal-density glass at different size ratios are vibrated and behavior is characterized as a function of the vibration amplitude. Experiments are also conducted on funnel and mass flow hoppers with outlet open, and the segregation upon discharge is measured for various operating conditions as well as hopper geometries. It is found that… Advisors/Committee Members: Rajesh N. Dave, Ian Sanford Fischer, Jay N. Meegoda.

Subjects/Keywords: Segregation; Flow enancement; Magnetically assisted particle flow (MAPF); Mechanical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

James, G. (2001). Experimental and numerical study of flow characteristics and segregation in flow enhanced systems. (Doctoral Dissertation). New Jersey Institute of Technology. Retrieved from https://digitalcommons.njit.edu/dissertations/516

Chicago Manual of Style (16th Edition):

James, Gregory. “Experimental and numerical study of flow characteristics and segregation in flow enhanced systems.” 2001. Doctoral Dissertation, New Jersey Institute of Technology. Accessed November 12, 2019. https://digitalcommons.njit.edu/dissertations/516.

MLA Handbook (7th Edition):

James, Gregory. “Experimental and numerical study of flow characteristics and segregation in flow enhanced systems.” 2001. Web. 12 Nov 2019.

Vancouver:

James G. Experimental and numerical study of flow characteristics and segregation in flow enhanced systems. [Internet] [Doctoral dissertation]. New Jersey Institute of Technology; 2001. [cited 2019 Nov 12]. Available from: https://digitalcommons.njit.edu/dissertations/516.

Council of Science Editors:

James G. Experimental and numerical study of flow characteristics and segregation in flow enhanced systems. [Doctoral Dissertation]. New Jersey Institute of Technology; 2001. Available from: https://digitalcommons.njit.edu/dissertations/516

.