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991.
A systematic theoretical study is carried out for the electron and positron impact excitation of the 31,3 P and 31,3 D states of helium from the ground 11 S state. The results are reported for the differential cross sections, Stokes parameters and alignment and orientation parameters. To calculate the scattering amplitude which relate these parameters, a distorted wave approximation theory with different choices of distortion potential has been used. The results are compared with available theoretical and experimental data in the energy range of 40–100eV.  相似文献   
992.
In this note, we summarize and compare various model predictions forpp total cross-section σ tot pp , giving an estimate of the range of predictions for the total cross-section, σ tot pp expected at the LHC. We concentrate on the results for σ tot pp obtained in a particular QCD based model of the energy dependence of the total cross-section, including the effect of soft gluon radiation. We obtain the range of predictions in this model by exploring the allowed range of model parameters. We further give a handy parametrisation of these results which incidentally spans the range of various other available predictions at the LHC as well  相似文献   
993.
Scheduling independent tasks on unrelated machines is a relatively difficult and challenging problem. In this paper, we develop a tabu search based heuristic for minimising makespan for the above problem that can provide good quality solutions for practical size problems within a reasonable amount of computational time. Our adaptation of this tabu search uses hashing to control the tabu restrictions of the search process and requires fewer critical parameters than many of the common tabu search approaches employed for combinatorial optimisation. Hashing is simple to implement and very effective in providing a near-optimal solution. Computational results are presented to demonstrate the effectiveness of the proposed heuristic.  相似文献   
994.
The densities and speeds of sound of binary solutions of nitrobenzene, 1-butanol, and anisole with tetra-n-butylammonium picrate have been measured over the full composition range from 298.15 to 371.1 K, in order to study the volumetric behavior of continuously miscible systems, made from an organic fused salt and a molecular organic liquid, at just above the melting point of the salt. The calculated apparent molar volumes and compressibilities are analyzed by using the equations of Petrenko and Pitzer. The thermal expansion coefficients of the above systems are also reported.  相似文献   
995.
996.
Some generalizations of the well-known Cauchy–Schwarz inequality and the analogous Cauchy–Bunyakovsky inequality involving four free parameters are given for both discrete and continuous cases. Several particular cases of interest are also analyzed. Some of the applications of our main results include (for example) the Wagner inequality.  相似文献   
997.
The angular distribution of the five-fold differential cross section for the electron impact double ionization of He (21 S) and He (23 S) has been studied. The kinematical conditions for maxima/minima in the angular distribution for the two cases have been compared. The two-step process for the double ionization is found to contribute very little in the triplet case.  相似文献   
998.
Using first principles calculations based on a gradient corrected density functional formalism we show that Fe2O3 nano-particles with (1 0 0) and (0 0 0 1) surface orientations can oxidize CO to form CO2 with or without the presence of O2. However, depending on the surface orientation, the oxidation occurs through differing sequences. On the (1 0 0) surface, in the absence of O2, two CO molecules are required for one CO oxidation in a concerted reaction while on a oxygen terminated (0 0 0 1) surface, a single CO molecule itself, without the aid of a second CO, can react with the lattice oxygen atoms to form CO2. In the presence of O2, the O vacancies created by an initial oxidation through lattice oxygen act as the favored sites for O2 adsorption which can subsequently oxidize the incoming CO. Detailed reaction paths and the corresponding energetics for the proposed mechanisms are also studied.  相似文献   
999.
S.K. Srivastava  S.P. Ojha   《Optik》2007,118(1):19-24
In this present communication, we introduce a new type of annular optical waveguide whose outer cladding is made of sheath helix. The sheath helix is made up of the dielectric material of lower refractive index than the core materials. Using vector approach, the general characteristic equation for the proposed waveguide has been derived. The modal dispersion characteristics for the lowest-order modes for different pitch angles are determined and analyzed. We observe that there is no effect of pitch angles on dispersion curve nearly up to 89° but drastic change is observed at 90° and above pitch angle. On comparison of helically inner cladded annular circular waveguide, we have found that there is not the existence of the negative dispersion curve and photonic band gap in the helically outer cladded annular circular waveguide. It means only the inner cladding is responsible for the negative dispersion as well as photonic band gap. There is no effect of the outer cladding.  相似文献   
1000.
A code for 2D space-charge dominated beam dynamics study in beam transport lines is developed. The code is used for particle-in-cell (PIC) simulation of z-uniform beam in a channel containing solenoids and drift space. It can also simulate a transport line where quadrupoles are used for focusing the beam. Numerical techniques as well as the results of beam dynamics studies are presented in the paper.   相似文献   
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