1,698 research outputs found
Additives That Prevent Or Reverse Cathode Aging In Drift Chambers With Helium-Isobutane Gas
Noise and Malter breakdown have been studied at high rates in a test chamber
having the same cell structure and gas as in the BaBar drift chamber. The
chamber was first damaged by exposing it to a high source level at an elevated
high voltage, until its operating current at normal voltages was below
0.5nA/cm. Additives such as water or alcohol allowed the damaged chamber to
operate at 25 nA/cm, but when the additive was removed the operating point
reverted to the original low value. However with 0.02% to 0.05% oxygen or 5%
carbon dioxide the chamber could operate at more than 25 nA/cm, and continued
to operate at this level even after the additive was removed. This shows for
the first time that running with an O2 or CO2 additive at high ionisation
levels can cure a damaged chamber from breakdown problems.Comment: There were typos: 0.2%-0.5% oxygen should be 0.02%-0.05% oxygen.
Values in the Table were O
Probability-guaranteed H∞ finite-horizon filtering for a class of nonlinear time-varying systems with sensor saturations
This is the Post-Print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 ElsevierIn this paper, the probability-guaranteed H∞ finite-horizon filtering problem is investigated for a class of nonlinear time-varying systems with uncertain parameters and sensor saturations. The system matrices are functions of mutually independent stochastic variables that obey uniform distributions over known finite ranges. Attention is focused on the construction of a time-varying filter such that the prescribed H∞ performance requirement can be guaranteed with probability constraint. By using the difference linear matrix inequalities (DLMIs) approach, sufficient conditions are established to guarantee the desired performance of the designed finite-horizon filter. The time-varying filter gains can be obtained in terms of the feasible solutions of a set of DLMIs that can be recursively solved by using the semi-definite programming method. A computational algorithm is specifically developed for the addressed probability-guaranteed H∞ finite-horizon filtering problem. Finally, a simulation example is given to illustrate the effectiveness of the proposed filtering scheme.This work was supported in part by the National Natural Science Foundation of China under Grants 61028008, 60825303 and
60834003, National 973 Project under Grant 2009CB320600, the Fok Ying Tung Education Fund under Grant 111064, the Special Fund for the Author of National Excellent Doctoral Dissertation of China under Grant 2007B4, the Key Laboratory of Integrated
Automation for the Process Industry (Northeastern University) from the Ministry of Education of China, the Engineering and
Physical Sciences Research Council (EPSRC) of the U.K. under Grant GR/S27658/01, the Royal Society of the U.K., and the
Alexander von Humboldt Foundation of Germany
Realistic sterile neutrino dark matter with KeV mass does not contradict cosmological bounds
International audiencePrevious fits of sterile neutrino dark matter models to cosmological dataassumed a peculiar production mechanism, which is not representative of thebest-motivated particle physics models given current data on neutrinooscillations. These analyses ruled out sterile neutrino masses smaller than8-10 keV. Here we focus on sterile neutrinos produced resonantly. We show thattheir cosmological signature can be approximated by that of mixed Cold plusWarm Dark Matter (CWDM). We use recent results on LambdaCWDM models to showthat for each mass greater than or equal to 2 keV, there exists at least onemodel of sterile neutrino accounting for the totality of dark matter, andconsistent with Lyman-alpha and other cosmological data. Resonant productionoccurs in the framework of the nuMSM (the extension of the Standard Model withthree right-handed neutrinos). The models we checked to be allowed correspondto parameter values consistent with neutrino oscillation data, baryogenesis andall other dark matter bounds
Efficient Deformable Shape Correspondence via Kernel Matching
We present a method to match three dimensional shapes under non-isometric
deformations, topology changes and partiality. We formulate the problem as
matching between a set of pair-wise and point-wise descriptors, imposing a
continuity prior on the mapping, and propose a projected descent optimization
procedure inspired by difference of convex functions (DC) programming.
Surprisingly, in spite of the highly non-convex nature of the resulting
quadratic assignment problem, our method converges to a semantically meaningful
and continuous mapping in most of our experiments, and scales well. We provide
preliminary theoretical analysis and several interpretations of the method.Comment: Accepted for oral presentation at 3DV 2017, including supplementary
materia
Improving Continuous-time Conflict Based Search
Conflict-Based Search (CBS) is a powerful algorithmic framework for optimally
solving classical multi-agent path finding (MAPF) problems, where time is
discretized into the time steps. Continuous-time CBS (CCBS) is a recently
proposed version of CBS that guarantees optimal solutions without the need to
discretize time. However, the scalability of CCBS is limited because it does
not include any known improvements of CBS. In this paper, we begin to close
this gap and explore how to adapt successful CBS improvements, namely,
prioritizing conflicts (PC), disjoint splitting (DS), and high-level
heuristics, to the continuous time setting of CCBS. These adaptions are not
trivial, and require careful handling of different types of constraints,
applying a generalized version of the Safe interval path planning (SIPP)
algorithm, and extending the notion of cardinal conflicts. We evaluate the
effect of the suggested enhancements by running experiments both on general
graphs and -neighborhood grids. CCBS with these improvements significantly
outperforms vanilla CCBS, solving problems with almost twice as many agents in
some cases and pushing the limits of multiagent path finding in continuous-time
domains.Comment: This is a pre-print of the paper accepted to AAAI 202
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