Wuhan University

About: Wuhan University is a education organization based out in Wuhan, China. It is known for research contribution in the topics: Population & Feature extraction. The organization has 92849 authors who have published 92882 publications receiving 1691049 citations. The organization is also known as: WHU & Wuhan College.

Synthesis and electrochemical behaviors of layered Na0.67[Mn0.65Co0.2Ni0.15]O2 microflakes as a stable cathode material for sodium-ion batteries

Abstract: Stable Na+ ion storage cathodes with adequate reversible capacity are now greatly needed for enabling Na-ion battery technology for large scale and low cost electric storage applications. In light of the superior Li+ ion storage performance of layered oxides, pure P2-phase Na0.67[Mn0.65Ni0.15Co0.2]O2 microflakes are synthesized by a simple sol–gel method and tested as a Na+ ion storage cathode. These layered microflakes exhibit a considerably high reversible capacity of 141 mA h g−1 and a slow capacity decay to 125 mA h g−1 after 50 cycles, showing much better cyclability than previous NaMnO2 compounds. To further enhance the structural and cycling stability, we partially substituted Co3+ by Al3+ ions in the transition-metal layer to synthesize Na0.67[Mn0.65Ni0.15Co0.15Al0.05]O2. As expected, the Al-substituted material demonstrates a greatly improved cycling stability with a 95.4% capacity retention over 50 cycles, possibly serving as a high capacity and stable cathode for Na-ion battery applications.

Ultrasound tunneling through 3D phononic crystals.

Abstract: We report the study of ultrasound tunneling in 3D phononic crystals, consisting of fcc arrays of close-packed tungsten carbide beads in water. The transmission coefficient, phase velocity, and group velocity were measured along the [111] direction, allowing us to systematically investigate the tunneling of ultrasound at frequencies in the lowest band gap. Our experimental data are interpreted using multiple scattering theory, which provides a good explanation of our results. The effect of absorption and the difference between the tunneling of classical waves and quantum waves are discussed.

Mapping wetland changes in China between 1978 and 2008

Abstract: Four wetland maps for all China have been produced, based on Landsat and CBERS-02B remote sensing data between 1978 and 2008 (1978, 1990, 2000 and 2008). These maps were mainly developed by manual interpretation and validated by substantial field investigation in 2009. Based on these maps, we analyzed the 2008 wetland distribution in China and discussed wetland changes and their drivers over the past 30 years. (i) There were about 324097 km(2) of wetlands in 2008, for which inland marshes or swamps were the most common wetland type (35%), with lakes (26%) second. Most of the wetlands were in Heilongjiang, Inner Mongolia, Qinghai and Tibet, occupying about 55% of the national wetland area. (ii) From 1978 to 2008, China's wetland area continually and significantly decreased, by about 33% based on changes in the wetland map. This was in sharp contrast to the increase in artificial wetlands, which increased by about 122%. Inland marshes accounted for the main loss of total wetlands from 1978 to 2000. From 2000 through 2008, riverine and lacustrine wetlands constituted the main wetland loss. Fortunately however, the rate of wetland loss decreased from 5523 to 831 km(2)/a. (iii) The change ratio of lost natural wetlands (including inland and coastal wetlands) to non-wetlands has decreased slightly over the past 30 years. From 1978 to 1990, nearly all natural wetlands (98%) lost were transformed into non-wetlands. However, the ratio declined to 86% from 1990 to 2000, and to 77% from 2000 to 2008. (iv) All Chinese provinces were divided into three groups according to patterns of wetland changes, which could relate to the driving forces of such changes. Tibet was completely different from other provinces, as it was one representative example in which there was a net wetland increase, because of global warming and decreased human activity since 1990. Increased economic development caused considerable wetland loss in most eastern provinces, and artificial wetlands increased.

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays.

Abstract: We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.