Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Removal of heavy metal ions from wastewaters: A review

인공고관절의 세라믹 볼 헤드의 기계적 안정성 평가를 위한 3 차원 유한요소 해석

 Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles Therefore, it is necessary to understand the distribution between the phases According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references It is also available at http://wwwhenrys-laworg 

/pdf/compilation-of-henry-s-law-constants-version-4-0-for-water-58il9q0ogv.pdf

Compilation of Henry's law constants (version 4.0) for water as solvent

Über die Adsorption in Lösungen

Removal of Cu2+ and Ni2+ from wastewater with a chelating agent and reverse osmosis processes

Solubility of carbon dioxide in poly(vinyl acetate) (PVAc), poly(2,6-dimethyl-1,4-phenylene ether) (PPO), polypropylene (PP), and high-density polyethylene (HDPE), poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA) and polystyrene (PS) are modeled by adaptive neuro-fuzzy inference system (ANFIS) in wide range of pressure and temperature. The results obtained in this work indicate that ANFIS is effective method for prediction of solubility of carbon dioxide in polymers and have better accuracy and simplicity compared with the classical methods.

Application of adaptive neuro-fuzzy inference system for solubility prediction of carbon dioxide in polymers

Activities of water are reported for aqueous solutions of poly(ethylene glycol) (PEG) with number average molecular weights of 300, 400, 4000, and 6000 are measured at 35, 45, 55, and 65 °C and at various concentrations from 0 to 40 wt % of PEG using vapor-pressure osmometery. A cubic equation in terms of PEG concentrations is sufficient for correlation of activities. Using measured activities, the Flory−Huggins interaction parameters have been calculated. The effect of temperature, molecular weight of PEG and its concentration, and volume change upon mixing on interaction parameter have been considered. Ignoring the volume change of mixing can lead to an average error of 2.5% with a maximum error of 5.3%.

Measurement of Activity of Water in Aqueous Poly(ethylene glycol) Solutions (Effect of Excess Volume on the Flory−Huggins χ-Parameter)

Molecular simulation study of penetrant gas transport properties into the pure and nanosized silica particles filled polysulfone membranes

Densities of aqueous solutions of poly(ethylene glycol) (PEG) have been measured at (300.15, 310.15, 313.15, 318.15, 323.15, and 328.15) K. The number-average molecular weights for PEG were 400, 4000, and 6000. The density data were fitted by a third-order polynomial with respect to mass fracton of the polymer at each temperature. Using the fitted polynomial expression and the Gibbs−Duhem equation, partial molar volumes of PEG and water for various mixtures were computed and reported.

Hamid Modarress

Papers

Removal of Cu2+ and Ni2+ from wastewater with a chelating agent and reverse osmosis processes

Application of adaptive neuro-fuzzy inference system for solubility prediction of carbon dioxide in polymers

Measurement of Activity of Water in Aqueous Poly(ethylene glycol) Solutions (Effect of Excess Volume on the Flory−Huggins χ-Parameter)

Molecular simulation study of penetrant gas transport properties into the pure and nanosized silica particles filled polysulfone membranes

Densities of Poly(ethylene glycol) + Water Mixtures in the 298.15-328.15 K Temperature Range