Using a group of robots in place of a single complex robot to accomplish a task has many benefits, including simplified system repair, less down time, and lower cost. Combining heterogeneous groups of these multi-robot systems allows addressing multiple subtasks in parallel, reducing the time it takes to address many problems, such as search and rescue, reconnaissance, and mine detection. These missions demand different roles for robots, necessitating a strategy for coordinated autonomy while respecting any constraints the environment may impose. Synthesis of control policies for heterogeneous multirobot systems is particularly challenging because of inter-robot constraints such as communication maintenance and collision avoidance, the need to coordinate robots within groups, and the dynamics of individual robots. I will present approaches to synthesizing feedback policies for navigating groups of robots in constrained environments. These approaches automatically and concurrently solve both the path planning and control synthesis problems, and are specified at a high level, for example, using an iPad interface to navigate a complex environment with a team of UAVs. I will also present some preliminary work on novel approaches to developing controllers for many types of multirobot tasks, by using crowdsourced multi-player game data.
Apatite nanoparticles are the main inorganic component of human hard tissues, and have been used in repair of bone defects or scaffolds for bone tissue engineering. It has a stable hexagonal crystal structure, which could be employed as a host matrix for lanthanides doping to prepare both downconversion and upconversion fluorescent nanoparticles. In the thesis, lanthanide doped apatite nanoparticles have been prepared by hydrothermal synthesis, and their structure, luminescence properties, cell proliferation, and their fluorescent tracking in vitro and in vivo have been investigated. The novel apatite fluorescence probe is expected to overcome the shortcomings such as instability and photobleaching of organic fluorophores, and the potential toxicity from quantum dots. The terbium (Tb) doped fluorapatite (FA:Tb) and hydroxyapatite (HA:Tb) nanocrystals with a uniform slender morphology exhibit bright green fluorescence, good cytocompatibility and excellent cell imaging capacity, providing feasibility for imaging and tracking of cells with multilineage differentiation. The Yb3+/Ho3+ co-doped apatite nanoparticles are firstly prepared with both green and red upconversion emissions under 980 nm near-infrared excitation. The 543 and 654 nm upconversion emission signals could be assigned, respectively, to 5F4 (5S2) - 5I8 and 5F5 - 5I8 transitions of holmium after energy transfer from ytterbium under 980 nm excitation. The FA:Yb3+/Ho3+ results in a superior green luminescence, while HA:Yb3+/Ho3+ dominates in red emission. The difference in green and red emission behavior between FA:Yb3+/Ho3+ and HA:Yb3+/Ho3+ is dependent on their lattice structure and composition. Several reasonable lanthanide embedding lattice models along the fluorine channel or hydroxyl channel of FA or HA crystal cell are proposed, and reveal a necessity for coexistent substitution mechanism. The upconversion apatite nanoparticles are used for the first time to clearly distinguish the implanted material from bone tissue, and to track their respective distribution in vivo. The superposition of fluorescent images including the upconversion apatite and the Masson’s stained bone tissue indicates that new bone tissue could grow into the interval space between the apatite particles and fully integrate with these particles. The upconversion material and fluorescence superposition method provide a novel strategy for long-term discriminable fluorescence tracking of implanted materials and scaffolds. These fluorescent apatite nanoparticles can not only form bonding with bone tissue, but also provide stable and clear fluorescence, which can be utilized for long-term bioimaging, distinguishing scaffold from newly formed bone tissue or identifying the interface between implanted material and bone tissue, and tracking the distribution of degraded scaffold fragments in vivo. Both the lanthanide doped apatite nanoparticles and the method presented in this research will have a promising prospect for future biomedical applications.
Interview portion of Lost in the Stacks, episode 397, originally broadcast Sept 28, 2018. Features interview with Dr David Beer, Professor of Sociology at the University of York, U.K.. Dr Beer discusses how academic writing and scholarly communication compare to the formats of popular music.
Gas drilling firms such as Shell, Halliburton or Schlumberger may be interested in this alternative green technology to chemical-based hydraulic fracturing, or "fracking," for shale gas drilling” which is called Cavitation Hydrovibration-- in light of the proposed ban on fracking (NYC urges ban on shale gas drilling)
Eliminating the fracking fluid is great but how effective is this new technology at controlling secondary fractures that allow the gas itself to escape into wells, water tables and surface water like creeks where it can disrupt ecosystems and come out through someone's faucet? The gas itself is poisonous as well.
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