This paper proposes and solves the Time-Interval All Fastest Path (allFP) query. Given a user-defined leaving or arrival time interval I, a source node s and an end node e, allFP asks for a set of all fastest paths from s to e, one for each sub-interval of I. Note that the query algorithm should find a partitioning of I into sub-intervals. Existing methods can only be used to solve a very special case of the problem, when the leaving time is a single time instant. A straightforward solution to the allFP query is to run existing methods many times, once for every time instant in I. This paper proposes a solution based on novel extensions to the A* algorithm. Instead of expanding the network many times, we expand once. The travel time on a path is kept as a function of leaving time. Methods to combine travel-time functions are provided to expand a path. A novel lower-bound estimator for travel time is proposed. Performance results reveal that our method is more efficient and more accurate than the discrete-time approach.
With the assistance of PVP, a novel magnetically recyclable Ag-based catalyst has been synthesized in one pot, and it is found that this catalyst is highly efficient in selectively catalyzing styrene conversion to styrene oxide.
Self-assembly can be a powerful, but simple, synthetic method for the fabrication and surface modification of nanometer- to micrometer-sized hollow spheres. Here we report a facile route for preparation of submicrometer ferrite hollow spheres which are amphiphilic and superparamagnetic. This unique approach involves the formation of ferrite nanocrystals and the simultaneous self-assembly of nanocrystals and block copolymer PEO-PPO-PEO into hollow spheres. Furthermore, this approach is general for the preparation of a series of ferrite hollow spheres, including Fe3O4, Co1-xFe2+xO4, and Mn1-xFe2+xO4. Unlike conventional hollow spheres, which are either hydrophobic or hydrophilic, the products we obtained exhibit excellent dispersibility in both polar and nonpolar solvents.
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