Application of smoothed particle hydrodynamics in analysis of shaped-charge jet penetration caused by underwater explosion

© 2017 Elsevier Ltd A process of target pen etration by a shaped-charge jet includes three main stages: charge detonation, formation of a metallic jet and its penetration of the target. With continuously increasing computational power, a numerical approach gradually becomes more prominent (combined with experimental and theoretical methods) in investigations of performance of a shaped-charge jet and its target penetration. This paper presents a meshfree methodology - Smoothed Particle Hydrodynamics (SPH) - for a shaped charge penetrating underwater structures. First, a SPH model of a sphere impacting a plate is developed; its numerical results agree well with the experimental data, verifying the validity of the mentioned developed method. Then, results obtained for different cases - for various materials of explosives and liners - are discussed and compared, and as a result, more suitable parameters of the shaped charge in order to increase the penetration depth are obtained - HMX and copper were chosen respectively as the explosive and the liner material. It follows by validation of a model of a free-field underwater explosion, developed to verify the effectiveness of the modified SPH method in solving problems of underwater explosion; its numerical results are compared with an empirical formula. Finally, the SPH method is applied to simulate the entire process ranging from the detonation of the shaped charge to the target penetration employing the optimal parameters. A fluid around the shaped charge is included into analysis, and damage characteristics of the plate exposed to air and water on its back side are compared

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Dioscorea sativa

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Molecular Distances Determined with Resonant Vibrational Energy Transfers

In general, intermolecular distances in condensed phases at the angstrom scale are difficult to measure. We were able to do so by using the vibrational energy transfer method, an ultrafast vibrational analogue of Förster resonance energy transfer. The distances among SCN^– anions in KSCN crystals and ion clusters of KSCN aqueous solutions were determined with the method. In the crystalline samples, the closest anion distance was determined to be 3.9 ± 0.3 Å, consistent with the XRD result. In the 1.8 and 1 M KSCN aqueous solutions, the anion distances in the ion clusters were determined to be 4.4 ± 0.4 Å. The clustered anion distances in aqueous solutions are very similar to the closest anion distance in the KSCN crystal but significantly shorter than the average anion distance (0.94–1.17 nm) in the aqueous solutions if ion clustering did not occur. The result suggests that ions in the strong electrolyte aqueous solutions can form clusters inside of which they have direct contact with each other

Nonresonant and Resonant Mode-Specific Intermolecular Vibrational Energy Transfers in Electrolyte Aqueous Solutions

The donor/acceptor energy mismatch and vibrational coupling strength dependences of interionic vibrational energy transfer kinetics in electrolyte aqueous solutions were investigated with ultrafast multiple-dimensional vibrational spectroscopy. An analytical equation derived from the Fermi’s Golden rule that correlates molecular structural parameters and vibrational energy transfer kinetics was found to be able to describe the intermolecular mode specific vibrational energy transfer. Under the assumption of the dipole–dipole approximation, the distance between anions in the aqueous solutions was obtained from the vibrational energy transfer measurements, confirmed with measurements on the corresponding crystalline samples. The result demonstrates that the mode-specific vibrational energy transfer method holds promise as an angstrom molecular ruler

Probing Ion/Molecule Interactions in Aqueous Solutions with Vibrational Energy Transfer

Interactions between model molecules representing building blocks of proteins and the thiocyanate anion, a strong protein denaturant agent, were investigated in aqueous solutions with intermolecular vibrational energy exchange methods. It was found that thiocyanate anions are able to bind to the charged ammonium groups of amino acids in aqueous solutions. The interactions between thiocyanate anions and the amide groups were also observed. The binding affinity between the thiocyanate anion and the charged amino acid residues is about 20 times larger than that between water molecules and the amino acids and about 5–10 times larger than that between the thiocyanate anion and the neutral backbone amide groups. The series of experiments also demonstrates that the chemical nature, rather than the macroscopic dielectric constant, of the ions and molecules plays a critical role in ion/molecule interactions in aqueous solutions