Hidden force opposing ice compression

Coulomb repulsion between the unevenly-bound bonding and nonbonding electron pairs in the O:H-O hydrogen-bond is shown to originate the anomalies of ice under compression. Consistency between experimental observations, density functional theory and molecular dynamics calculations confirmed that the resultant force of the compression, the repulsion, and the recovery of electron-pair dislocations differentiates ice from other materials in response to pressure. The compression shortens and strengthens the longer-and-softer intermolecular O:H lone-pair virtual-bond; the repulsion pushes the bonding electron pair away from the H+/p and hence lengthens and weakens the intramolecular H-O real-bond. The virtual-bond compression and the real-bond elongation symmetrize the O:H-O as observed at ~60 GPa and result in the abnormally low compressibility of ice. The virtual-bond stretching phonons (< 400 cm-1) are thus stiffened and the real-bond stretching phonons (> 3000 cm-1) softened upon compression. The cohesive energy of the real-bond dominates and its loss lowers the critical temperature for the VIII-VII phase transition. The polarization of the lone electron pairs and the entrapment of the bonding electron pairs by compression expand the band gap consequently. Findings should form striking impact to understanding the physical anomalies of H2O.Comment: arXiv admin note: text overlap with arXiv:1110.007

HYDRODYNAMIC PERFORMANCE OF NEIL PRYDE RS: X AND MISTRAL SAILBOARD

After Olympic Games in 2004, the once used board, MISTRAL (M), in Olympic Game has been substituted with NEIL PRYDE RS&#65306;X (NP). To meet the need of the national sailing team, the research group carried out the experiments on the hydrodynamic performance of the NP and M early or later. The resistances, transverse forces and wrest moments were measured by using the balance of the trisection force, the angle of the heel and pitch was measured by using the angle sensor. The sailboard could rise and sink freely, the pitch was free, the static angle could be adjusted by utilizing the weight and the balance was at the mast. The results showed that the resistance of NP sailboard was bigger as soon as the pitch angle was bigger and this was the same as that of M sailboard, the heel did not have any influence on the resistance of NP sailboard, the resistance became small continuously when the angle of the centerboard decreased and the resistance increased as the sailboard was heavier

SPORT APPLICATIONS FOR CFD ANALYSIS

Computational Fluid Dynamics (CFD) and the sports applications of CFD were introduced. It was discussed that the level of sports games was enhanced by calculating the performance of equipment by use of CFD. The results indicated that by use of CFD, the simulative computation can be finished in the short period, the relation of the fluid dynamics and the figure of equipment was gained

HYDRODYNAMIC ANALYSIS OF ROWING HULL BASED ON THE FLOAT POSE

The rowing is one of the important events in the Olympic Games. In order to study the hydrodynamic performance of rowing, we finished the linetype mapping and the calculated the parameters of the double rowing model. Based on the resistance data of rowing at different states, we obtained the rule of resistance of rowing at different speeds. The study indicated that the enhancement of the physical force of the athletes seemed to be in proportion to the weight of the athletes and the results based on research shallow affected and optimized the design

Sn(II)-containing phosphates as optoelectronic materials

We theoretically investigate Sn(II) phosphates as optoelectronic materials using first principles calculations. We focus on known prototype materials Sn$_n$P$_2$O$_{5+n}$ (n=2, 3, 4, 5) and a previously unreported compound, SnP$_2$O$_6$ (n=1), which we find using global optimization structure prediction. The electronic structure calculations indicate that these compounds all have large band gaps above 3.2 eV, meaning their transparency to visible light. Several of these compounds show relatively low hole effective masses ($\sim$2-3 m$_0$), comparable the electron masses. This suggests potential bipolar conductivity depending on doping. The dispersive valence band-edges underlying the low hole masses, originate from the anti-bonding hybridization between the Sn 5s orbitals and the phosphate groups. Analysis of structure-property relationships for the metastable structures generated during structure search shows considerable variation in combinations of band gap and carrier effective masses, implying chemical tunability of these properties. The unusual combinations of relatively high band gap, low carrier masses and high chemical stability suggests possible optoelectronic applications of these Sn(II) phosphates, including p-type transparent conductors. Related to this, calculations for doped material indicate low visible light absorption, combined with high plasma frequencies.Comment: 10 pages, 10 figures, Supplementary informatio