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Search Results: 1 - 10 of 53827 matches for " Jun Song "
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Research on Characteristics of Atmospheric Pollution and Meteorological Condition in South of Northern China  [PDF]
Jun Zhang, Xiaohui Song
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.51005
Abstract: Taking Handan City (the south of Northern China) as an example, and making use of the environmentally friendly materials of Handan Environmental Monitor Station in 2013-2014, the surface observational data of Handan Meteorological Station and the sounding data of Xingtai station, combined with the integrated analysis of numerical prediction and simulation, this paper shows that, in 2014, the air quality improved; the emission-reduction effect was significant; the days of heavy pollution decreased; and the days up to the standard increased; the annual average concentration of pollutants PM2.5 and PM10 in the whole city showed a decreasing tendency compared to the same period of last year. In 2014, there were a total of 9 weather processes of heavy pollution lasting more than 3 days and the duration was significantly shorter than that in 2013, which indicated that effective emission-reduction measures significantly shortened the duration of weather processes of heavy pollution. The comprehensive analysis of meteorological conditions, such as the days of light wind, wind speed, wind frequency, PM2.5 concentration at different wind directions, the thickness and intensity of the inversion layer, and the height of the mixed layer, showed that, compared with the same period in 2013, the general meteorological conditions of air pollutant dispersion were basically flat and slightly disadvantageous in 2014. Handan municipal government increased the intensity of the prevention and control of air pollution in 2014, promulgated and adopted a series of air pollution control policies and emission-reduction control measures, and achieved some results, especially the emission-reduction measures during the APEC meeting which were obviously effective.
Empirical Research on the Relationship between Scientific Innovation and Economic Growth in Beijing  [PDF]
Lei Zhang, Wei Song, Jun He
Technology and Investment (TI) , 2012, DOI: 10.4236/ti.2012.33023
Abstract: This paper will build up a model about the dynamic relationship between scientific innovation and economic growth in Beijing, with VAR model (Vector Autoregressive Model), and choose the quantity of patent applications, sum of business transactions in the market of technologies and the foreign direct investment as its indicators of science and technology output, GDP as its indicator of economic growth, which finally uses variance decomposition analysis. The research shows that there is a long-term equilibrium relationship between scientific innovation and economic growth, and both have interactivity which means that scientific innovation promotes economic growth and economic growth boosts the scientific innovation.
Research progress in the development of direct acting antiviral agents for hepatitis C and the anti-viral resistance
Song YANG,Jun CHENG
Medical Journal of Chinese People's Liberation Army , 2011,
Abstract: Recently,directly acting antiviral agents against hepatitic C virus with different mechanisms have been developed and put into clinical trials.Especially,results of phase Ⅲ clinical trials of Boceprevir and Telaprevir have been published,and these two agents are to be approved for marketing in recent years.Also much attention has been paid on anti-viral resistance against direct acting antiviral agents.Great progresses have been made in field of direct acting antiviral agents against hepatitic C virus.Domestic studies in this area should take characteristics of virus and host of Chinese chronic hepatitis C into consideration.
Rate-Based Active Queue Management for TCP Flows over Wired and Wireless Networks
Wang Jun,Song Min
EURASIP Journal on Wireless Communications and Networking , 2007,
Abstract: Current active queue management (AQM) and TCP protocol are designed and tuned to work well on wired networks where packet loss is mainly due to network congestion. In wireless networks, however, communication links suffer from significant transmission bit errors and handoff failures. As a result, the performance of TCP flows is significantly degraded. To mitigate this problem, we analyze existing AQM schemes and propose a rate-based exponential AQM (REAQM) scheme. The proposed REAQM scheme uses the input rate as a primary metric and queue length as the secondary metric. The objectives of REAQM are to stabilize networks with low packet loss, low packet delay, and high link utilization regardless the dynamic of network conditions. We prove the global asymptotic stability of the equilibrium based on Lyapunov theory. Simulation results suggest that REAQM is capable of performing well for TCP flows over both wired and wireless networks, and has comparable implementation complexity as other AQM schemes.
Rate-Based Active Queue Management for TCP Flows over Wired and Wireless Networks
Jun Wang,Min Song
EURASIP Journal on Wireless Communications and Networking , 2007, DOI: 10.1155/2007/54038
Abstract: Current active queue management (AQM) and TCP protocol are designed and tuned to work well on wired networks where packet loss is mainly due to network congestion. In wireless networks, however, communication links suffer from significant transmission bit errors and handoff failures. As a result, the performance of TCP flows is significantly degraded. To mitigate this problem, we analyze existing AQM schemes and propose a rate-based exponential AQM (REAQM) scheme. The proposed REAQM scheme uses the input rate as a primary metric and queue length as the secondary metric. The objectives of REAQM are to stabilize networks with low packet loss, low packet delay, and high link utilization regardless the dynamic of network conditions. We prove the global asymptotic stability of the equilibrium based on Lyapunov theory. Simulation results suggest that REAQM is capable of performing well for TCP flows over both wired and wireless networks, and has comparable implementation complexity as other AQM schemes.
Collisions between Whales and Fast Ferries around Korean Waters
Kyung-Jun Song
Journal of Marine Biology , 2013, DOI: 10.1155/2013/309751
Abstract: Although there is heavy maritime traffic around Korean waters, collisions between whales and fast ferries around Korean waters are nearly unknown. A ship strike that was associated with a minke whale occurred near the southeastern part of Tsushima Island along the sailing route of the fast ferry between Korea and Japan on December 16, 2004. It was associated with a fast ferry that runs at a speed of approximately 46.1?kn (83?km/h) between Korea and Japan. This individual was certainly seriously injured or killed by this ship strike because large amounts of skin of this individual were attached to the surface of the fast ferry, and also large amounts of blood of this individual spread out in that area. However, fortunately, serious damage did not occur to the mariners and passengers of the ferry, although many passengers were knocked down to the floor of the fast ferry when the fast ferry collided with the minke whale. In addition, a total of 4 records of possible collisions between whales and fast ferries have occurred on the fast ferry route between Korea and Japan between 2004 and 2007. This study is the first formal report on collisions between whales and fast ferries around Korean waters. Although the effect of ship strikes on the survival of cetaceans distributed around Korean waters is not very high at present compared with that of other threats, such as entanglement in fishing gear, ship strikes can pose a significant potential threat to endangered cetaceans such as western gray whales. Therefore, it is necessary to prepare prevention measures for ship strikes for the conservation of cetaceans around Korean waters in the future. 1. Introduction Collisions between cetaceans and ships, known as ship strikes, have been continuously reported all around the world [1, 2]. Furthermore, the frequency of ship strikes has tended to increase in recent years because of the increase in maritime traffic and in the speed of various vessels. A comprehensive review of ship strikes with large whales throughout the world has been made for the first time [1]. According to this investigation, a total of 11 species collided with vessels throughout the world. Among these 11 species, several species such as fin whales, right whales, humpback whales, sperm whales, and gray whales frequently collided with vessels. They also noted that ship strikes have occurred with all types of vessels based on the historical records and a computerized stranding database. On the other hand, according to some studies, a total of 292 large whale individuals collided with vessels between
Structural Parameters for Globular Clusters in the Outer Halo of M31
Song Wang,Jun Ma
Physics , 2012, DOI: 10.1088/0004-6256/143/6/132
Abstract: In this paper, we present internal surface brightness profiles, using images in the F606W and F814W filter bands observed with the Advanced Camera for Surveys on the {\it Hubble Space Telescope}, for ten globular clusters (GCs) in the outer halo of M31. Standard King models are fitted to the profiles to derive their structural and dynamical parameters. The results show that, in general, the properties of clusters in M31 and the Milky Way fall in the same regions of parameter spaces. The outer halo GCs of M31 have larger ellipticities than most of GCs in M31 and the Milky Way. Their large ellipticities may be due to galaxy tides coming from satellite dwarf galaxies of M31 or may be related to the apparently more vigorous accretion or merger history that M31 has experienced. The tight correlation of cluster binding energy $E_b$ with mass $M_{\rm mod}$ indicates that, the "fundamental plane" does exist for clusters, regardless of their host environments, which is consistent with previous studies.
Strain engineering of magnetic states of vacancy-decorated hexagonal boron nitride
Bin Ouyang,Jun Song
Physics , 2013, DOI: 10.1063/1.4819266
Abstract: Novel materials with tunable magnetic states play a significant role in the development of next-generation spintronic devices. In this paper, we examine the role of biaxial strain on the electronic properties of vacancy-decorated hexagonal boron nitride (h-BN) monolayers using density functional theory calculations. We found that the strain can lead to switching of the magnetic state for h-BN monolayers with boron vacancy or divacancy. Our findings promise a new route for the operation of low-dimensional spintronic devices.
Structural parameters for globular clusters in M31
Song Wang,Jun Ma
Physics , 2013, DOI: 10.1088/0004-6256/146/2/20
Abstract: In this paper, we present surface brightness profiles for 79 globular clusters in M31, using images observed with {\it Hubble Space Telescope}, some of which are from new observations. The structural and dynamical parameters are derived from fitting the profiles to several different models for the first time. The results show that in the majority of cases, King models fit the M31 clusters as well as Wilson models, and better than S\'{e}rsic models. However, there are 11 clusters best fitted by S\'{e}rsic models with the S\'{e}rsic index $n>2$, meaning that they have cuspy central density profiles. These clusters may be the well-known core-collapsed candidates. There is a bimodality in the size distribution of M31 clusters at large radii, which is different from their Galactic counterparts. In general, the properties of clusters in M31 and the Milky Way fall in the same regions of parameter spaces. The tight correlations of cluster properties indicate a "fundamental plane" for clusters, which reflects some universal physical conditions and processes operating at the epoch of cluster formation.
Covalent pathways in engineering h-BN supported graphene
Bin Ouyang,Jun Song
Physics , 2015,
Abstract: Cross-planar di-vacancies (CPDVs) within stacked graphene hexagonal boron nitride (h-BN) heterostructures provide stabilized covalent links to bridge adjacent graphene and h-BN sheets. It was shown that the CPDVs serve as focal points for cross-planar atom transport between graphene and h-BN, and the chemical nature of interlayer links along with associated cross-planar migration pathways at these defects can be predictively manipulated through modulation of the chemical environment and charge engineering, to achieve consistent B or N doping and simultaneous healing of graphene. The present study proposed a viable approach integrating irradiation, chemical and charge engineering, to produce high-quality graphene with tunable electronic and electrochemical properties, using the h-BN substrate.
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