A note on scheduling to meet two min-sum objectives

We consider a single machine scheduling problem with two min-sum objective functions: the sum of completion times and the sum of weighted completion times. We propose a simple polynomial time (1+(1/γ),1+γ)-approximation algorithm, and show that for γ>1, there is no (x,y)-approximation with 1<x<1+(1/γ) and 1<y<1+(γ-1)/(2+γ).     

Distinctive features of time-resolved photoluminescence of porous silicon coated with a layer of diamondlike carbon

Time-resolved photoluminescence from porous silicon coated with a diamondlike carbon film is investigated. The intensity of the photoluminescence from the carbon film is obserd to increase after deposition, and there is an accompanying change in the intensity and a shortwavelength shift of the photoluminescence band of porous silicon that depends on the porosity of its original layers. These changes are explained by the formation of carbon nanoclusters on the surface of the silicon filaments. Zh. Tekh. Fiz. 68, 83–87 (April 1998)     

Infrared absorption and electron paramagnetic resonance studies of vinyl radical in noble-gas matrices

Vinyl radicals produced by annealing-induced reaction of mobilized hydrogen atoms with acetylene molecules in solid noble-gas matrices (Ar, Kr, and Xe) were characterized by Fourier transform infrared and electron paramagnetic resonance (EPR) spectroscopies. The hydrogen atoms were generated from acetylene by UV photolysis or fast electron irradiation. Two vibrational modes of the vinyl radical (nu7 and nu5) were assigned in IR absorption studies. The assignment is based on data for various isotopic substitutions (D and 13C) and confirmed by comparison with the EPR measurements and density-functional theory calculations. The data on the nu7 mode is in agreement with previous experimental and theoretical results whereas the nu5 frequency agrees well with the computational data but conflicts with the gas-phase IR emission results.     

Numerical modeling of the influence of heat exchange of reservoir beds with enclosing rocks on gas production from a single well

In the computational experiment, the influence of heat exchange through the top and bottom of the gas-bearing reservoir on the dynamics of temperature and pressure fields in the process of real gas production from a single well is investigated. The experiment is carried out with a modified mathematical model of nonisothermal gas filtration, obtained from the energy and mass conservation laws and the Darcy law. The physical and caloric equations of state together with the Newton-Richman law of heat exchange of a gas reservoir with surrounding enclosing rocks are used as closing relations. It is shown that the influence of the heat exchange with environment on the temperature field of a gas-bearing reservoir is localized in a narrow zone near its top and bottom, although the size of this zone increases with time.     

Solvent-free deposition of hybrid halide perovskites onto thin films of copper iodide p-type conductor

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