1,209 research outputs found

    Fractional Denoising for 3D Molecular Pre-training

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    Coordinate denoising is a promising 3D molecular pre-training method, which has achieved remarkable performance in various downstream drug discovery tasks. Theoretically, the objective is equivalent to learning the force field, which is revealed helpful for downstream tasks. Nevertheless, there are two challenges for coordinate denoising to learn an effective force field, i.e. low coverage samples and isotropic force field. The underlying reason is that molecular distributions assumed by existing denoising methods fail to capture the anisotropic characteristic of molecules. To tackle these challenges, we propose a novel hybrid noise strategy, including noises on both dihedral angel and coordinate. However, denoising such hybrid noise in a traditional way is no more equivalent to learning the force field. Through theoretical deductions, we find that the problem is caused by the dependency of the input conformation for covariance. To this end, we propose to decouple the two types of noise and design a novel fractional denoising method (Frad), which only denoises the latter coordinate part. In this way, Frad enjoys both the merits of sampling more low-energy structures and the force field equivalence. Extensive experiments show the effectiveness of Frad in molecular representation, with a new state-of-the-art on 9 out of 12 tasks of QM9 and on 7 out of 8 targets of MD17

    Based on Two and Three Dimensional Technology to quickly build a Virtual Battlefield

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    AbstractVirtual battlefield environment is the use of computer technology, graphics technology and virtual reality technology to the real battle space in the computer. As technology advances and development, virtual battlefield environment system has been applied more and more combat troops and combat command being. Virtual Battlefield Environment Simulation System is a system for the commander to provide a realistic battlefield environment to facilitate their understanding of the terrain, the battlefield awareness information. In this paper, two-dimensional battlefield maps based on MapObject structures and the construction of three-dimensional virtual battlefield environment problem, a second, three-dimensional virtual battlefield environment with the rapid construction techniques. Operational commanders can quickly build a virtual battlefield, not only from the macro real-time battlefield information and to grasp the battlefield situation, but also learned from the battlefield of detailed microscopic details

    Onsite data processing and monitoring for the Daya Bay Experiment

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    The Daya Bay Reactor Neutrino Experiment started running on September 23, 2011. The offline computing environment, consisting of 11 servers at Daya Bay, was built to process onsite data. With current computing ability, onsite data processing is running smoothly. The Performance Quality Monitoring system (PQM) has been developed to monitor the detector performance and data quality. Its main feature is the ability to efficiently process multi-data-stream from three experimental halls. The PQM processes raw data files from the Daya Bay data acquisition system, generates and publishes histograms via a graphical web interface by executing the user-defined algorithm modules, and saves the histograms for permanent storage. The fact that the whole process takes only around 40 minutes makes it valuable for the shift crew to monitor the running status of all the sub-detectors and the data quality

    Predictions of Light Hadronic Decays of Heavy Quarkonium 1D_2 States in NRQCD

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    The inclusive light hadronic decays of 1D_2 heavy quarkonia are studied within the framework of NRQCD at the leading order in vv and up to the order of αs3\alpha_s^3. With one-loop QCD corrections, the infrared divergences and Coulomb singularities in the decay amplitudes are proved to be absorbed by the renormalization of the matrix elements of corresponding NRQCD operators, and the infrared finite short-distance coefficients are obtained through the matching calculations. By taking the factorization scale to be 2m_Q, the light hadronic decay widths are estimated to be about 274, 4.7, and 8.8 KeV for the ηc2,ηb2\eta_{c2}, \eta_{b2}, and ηb2′\eta_{b2}' respectively. Based on the above estimates, and using the E1 transition width and dipion transition width for the ηc2\eta_{c2} estimated elsewhere, we get the total width of ηc2\eta_{c2} to be about 660-810 KeV, and the branching ratio of the E1 transition ηc2→γhc\eta_{c2}\to\gamma h_c to be about (44-54)%, which will be useful in searching for this missing charmonium state through, e.g., the process ηc2→γhc\eta_{c2}\to\gamma h_c followed by hc→γηch_c\to\gamma\eta_c.Comment: 27 pages, 10 figure

    N-(2,6-Diisopropyl­phen­yl)-N-{3-[(2,6-diisopropyl­phen­yl)imino]­butan-2-yl}aza­nide trichloridostannate(II)

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    In the title compound, (C28H43N2)[SnCl3], two pairs of molecular species are present in the asymmetric unit. The employed α-diimine opens up, forming a highly asymmetric ammonium that has its protons at one of the N atoms [N—C= 1.264 (4) and 1.516 (4) Å]. One of the C=N double bonds was oxidized to C—N, which is consistent with the bond length of 1.516 (4) Å. Meanwhile SnIV was reduced to SnII. The (SnCl)3 − anion is trigonal–pyramidal. In the crystal, mol­ecules are linked by C—H⋯Cl, N—H⋯Cl, N—H⋯N and C—H⋯N bonds. The crystal studied was twinned by pseudo-merohedry
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