3,410 research outputs found

    The vibration reduction design of single-cylinder engine based on the balance shaft

    Get PDF
    A 3d model of crank connecting rod of a single cylinder internal combustion engine (ICE) is established, whose force analysis was carried out in ADAMS/VIEW using virtual prototyping method. It was found that the results between the analysis and the theoretical calculation results were basically consistent, indicating that the established model is correct and reliable. In order to reduce the inertia force and torque of this ICE, the uniaxial balance method was used to carry out the vibration reduction design based on the balance shaft. The results of virtual experiments showed that the single cylinder internal combustion engine with a balance shaft can greatly reduce the inertia excitation force as well as improve the vibration

    Is the late near-infrared bump in short-hard GRB 130603B due to the Li-Paczynski kilonova?

    Full text link
    Short-hard gamma-ray bursts (GRBs) are widely believed to be produced by the merger of two binary compact objects, specifically by two neutron stars or by a neutron star orbiting a black hole. According to the Li-Paczynski kilonova model, the merger would launch sub-relativistic ejecta and a near-infrared/optical transient would then occur, lasting up to days, which is powered by the radioactive decay of heavy elements synthesized in the ejecta. The detection of a late bump using the {\em Hubble Space Telescope} ({\em HST}) in the near-infrared afterglow light curve of the short-hard GRB 130603B is indeed consistent with such a model. However, as shown in this Letter, the limited {\em HST} near-infrared lightcurve behavior can also be interpreted as the synchrotron radiation of the external shock driven by a wide mildly relativistic outflow. In such a scenario, the radio emission is expected to peak with a flux of ∼100μ\sim 100 \muJy, which is detectable for current radio arrays. Hence, the radio afterglow data can provide complementary evidence on the nature of the bump in GRB 130603B. It is worth noting that good spectroscopy during the bump phase in short-hard bursts can test validity of either model above, analogous to spectroscopy of broad-lined Type Ic supernova in long-soft GRBs.Comment: 4 pages, 2 figures, published in ApJ Lette

    Cosmological constraints on holographic dark energy models under the energy conditions

    Full text link
    We study the holographic and agegraphic dark energy models without interaction using the latest observational Hubble parameter data (OHD), the Union2.1 compilation of type Ia supernovae (SNIa), and the energy conditions. Scenarios of dark energy are distinguished by the cut-off of cosmic age, conformal time, and event horizon. The best-fit value of matter density for the three scenarios almost steadily located at Ωm0=0.26\Omega_{m0}=0.26 by the joint constraint. For the agegraphic models, they can be recovered to the standard cosmological model when the constant cc which presents the fraction of dark energy approaches to infinity. Absence of upper limit of cc by the joint constraint demonstrates the recovery possibility. Using the fitted result, we also reconstruct the current equation of state of dark energy at different scenarios, respectively. Employing the model criteria χmin2/dof\chi^2_{\textrm{min}}/dof, we find that conformal time model is the worst, but they can not be distinguished clearly. Comparing with the observational constraints, we find that SEC is fulfilled at redshift 0.2≲z≲0.30.2 \lesssim z \lesssim 0.3 with 1σ1\sigma confidence level. We also find that NEC gives a meaningful constraint for the event horizon cut-off model, especially compared with OHD only. We note that the energy condition maybe could play an important role in the interacting models because of different degeneracy between Ωm\Omega_m and constant cc.Comment: 8 pages, 4 figures, accepted for publication in PR

    Mass Transport Induced by Heat Current in Carbon Nanotubes

    Get PDF
    Transport of helium atoms in the carbon nanotubes is investigated in the presence of temperature gradients. The heat current flowing along the carbon nanotubes can induce a stable directed transport of helium; it is demonstrated that the heat current density rather than the temperature gradient performs as a fundamental physical factor to the mass transport. We provide an alternative route to control the mass transport by using heat. Our results reported here are also relevant for understanding the transition from thermal energy to mechanical energy

    COSTS DUE TO UTILITY FOULING IN CHINA

    Get PDF
    This paper puts forward a method for evaluating the fouling costs of boilers and turbines in power plants. Furthermore, the Huaneng Dalian Power Plant and Changshan Power Plant are taken as examples for analyzing the costs of fouling. Based on data of on-site measurements in the above Power Plants, the costs due to fouling such as excess surface area, product loss, operating maintenance and increase of product costs are calculated. Results show that the total economical loss due to boiler and turbine fouling in China reaches 4.68 billion dollars, which covers is about 0.169% GDP of China in 2006

    Ariadne's Thread:Using Text Prompts to Improve Segmentation of Infected Areas from Chest X-ray images

    Full text link
    Segmentation of the infected areas of the lung is essential for quantifying the severity of lung disease like pulmonary infections. Existing medical image segmentation methods are almost uni-modal methods based on image. However, these image-only methods tend to produce inaccurate results unless trained with large amounts of annotated data. To overcome this challenge, we propose a language-driven segmentation method that uses text prompt to improve to the segmentation result. Experiments on the QaTa-COV19 dataset indicate that our method improves the Dice score by 6.09% at least compared to the uni-modal methods. Besides, our extended study reveals the flexibility of multi-modal methods in terms of the information granularity of text and demonstrates that multi-modal methods have a significant advantage over image-only methods in terms of the size of training data required.Comment: Provisional Acceptance by MICCAI 202
    • …
    corecore