3,410 research outputs found
The vibration reduction design of single-cylinder engine based on the balance shaft
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?
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 Jy, 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
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 by the joint
constraint. For the agegraphic models, they can be recovered to the standard
cosmological model when the constant which presents the fraction of dark
energy approaches to infinity. Absence of upper limit of 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
, 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 with 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 and
constant .Comment: 8 pages, 4 figures, accepted for publication in PR
Mass Transport Induced by Heat Current in Carbon Nanotubes
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
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
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
- …