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691.
Described the main environmental hazards occurring in Polish underground mines and their continuous growth in recent years
as well as equipment and systems which were used for monitoring mine air parameters and geodynamic phenomena. The latest versions
of environmental hazard monitoring systems, having a form of a comprehensive set of underground and surface equipment, are
presented and their functions characterized. 相似文献
692.
The purpose of this study was to investigate the structural, water holding capacity (WHC) and water compartmentalization changes in meat samples sonicated at 24 h after slaughter. Analyses were carried out at the following fixed intervals post mortem: 24, 48, 72 and 96 h on the beef muscle (m. semimembranosus) taken from carcasses chilled at 2 °C. Muscle was divided into eight parts. Four of them were subjected to ultrasound treatment within 2 min with frequency of 45 kHz (sample S). The other four were regarded as control samples. Water compartmentalization was assessed by NMR relaxation time measurements. Water holding capacity as well as acidity of meat was measured. More advanced post mortem changes in sonicated sample than in the control sample support the hypothesis that application of ultrasound treatment can cause acceleration of the ageing process. 相似文献
693.
Retrenchment is a flexible model evolution formalism that arose as a reaction to the limitations imposed by refinement, and for which the proof obligations feature additional predicates for accommodating design data. Composition mechanisms for retrenchment are studied. Vertical, horizontal, dataflow, parallel and fusion compositions are described. Of particular note are the means by which the additional predicates compose. It is argued that all of the compositions introduced are associative, and that they are mutually coherent. Composition of retrenchment with refinement, so important for the smooth interworking of the two techniques, is discussed. Decomposition, allowing finer grained retrenchments to be extracted from a single large grained retrenchment, is also investigated. 相似文献
694.
Cobalt(II) sites in ferrierites are already well-known from their catalytic activity, their speciation and properties, however, the knowledge are far from completeness. The following paper presents the first in literature combined QM/MM study to elucidate the structure of these sites. With this end force-field parameters describing Co interactions with ionic shells in zeolite have been tested and the cell size for various Al distributions and Co positioning has been determined. Oxide-type Buckingham parameters are shown to perform better than the carbonate ones. Moreover, Co(II) ions stability in α and β sites with various Al distribution indicates at T1T1 Al substitution in β-site as that the preferred Co(II) siting. DFT results show that the quartet spin state of Co(II) is more stable than the doublet one. 相似文献
695.
696.
The Judd–Ofelt (J–O) theory has had a remarkable success in the characterization of radiative transitions in lanthanide doped solids. The purpose of this paper is to review the applications of the J–O theory to the Pr3+ and Sm3+ ions and to use this system as an occasion to appraise its validity and to clarify its limits. In this paper we dwell at length on the absorption and luminescence measurements of two glass samples doped with Pr3+ and Sm3+, because they are basic for the J–O treatment. The results obtained for the J–O theory application to phosphate glasses doped with Pr3+ and Sm3+ present two undesirable outcomes: (1) a positive value of parameter Ω2 and (2) large uncertainties with which the three Judd–Ofelt parameters were obtained. The validity of the J–O theory for intensity analysis was also tested for Sm3+ doped in phosphate glass. The resulting Ω2 was much lower than Ω4. The first set parameters were obtained using all the levels for which fexp. was available. The second set parameter values were evaluated without the 6F1/2 and 6H15/2 levels. The Ω2,4,6 values given in these two sets clearly suggest that particular care should be taken while evaluating the Judd–Ofelt parameters as well as when these parameters are compared to other systems due to their strong dependence on the nature of levels. 相似文献
697.
The paper addresses the issue of decision-making support for small and medium-size enterprises operating within a virtual
project-driven enterprise environment. The problem considered here can be defined in terms of finding a feasible schedule
that satisfies the constraints imposed by the work-order duration, the price, and the time-constrained resource availability.
The problem belongs to the class of multi-mode case problems of project scheduling, where finding a feasible solution is NP-hard.
A heuristic method for process planning and scheduling is proposed. The method is based on a critical path approach and the
branch and bound search scheme. It has been implemented in a web-enabled interactive software package, and is illustrated
using the example of a virtual construction enterprise.
Received: February 2005 / Accepted: January 2006 相似文献
698.
Magnetic contactless detection of stress distribution and assembly defects in constructional steel element 总被引:3,自引:0,他引:3
Zbigniew H. urek 《NDT & E International》2005,38(7):589-595
The paper describes contactless stress measurement in a fit joint. The stress was investigated on the basis of changes in material's magnetisation. The level of magnetic leakage field changes due to mechanical stress is low. The stress measurements are determined by material's magnetoelastic sensitivity. This sensitivity must be ascertained. The magnetising field intensity is selected with high accuracy in the range where material's magnetoelastic sensitivity is greatest.The fit joint was executed with tolerance kept within planned limits. The elastic deformation of the ring's material at the lateral surface was measured with a strain gauge. At the last stage, the analytic and numerical calculations of the fit joint were compared to the magnetic field measurement results. The experiment has proven that it is possible to carry out contactless magnetic tests in constructional steel characterised by low magnetoelastic sensitivity. 相似文献
699.
Thickness effects of water overlayer on its explosive evaporation at heated metal surfaces 总被引:1,自引:0,他引:1
Yusheng Dou Leonid V. Zhigilei Zbigniew Postawa Nicholas Winograd Barbara J. Garrison 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2001,180(1-4):105-111
Molecular dynamics (MD) simulations have been employed to investigate the effect of the thickness of a water overlayer on the character of its ejection from a heated Au surface. The simulations are performed for five systems differing in the thickness of the water overlayer which was adsorbed on a metal substrate heated to 1000 K. For each system, an explosive evaporation occurs in the part of the water film adjacent to the metal surface and the upper part of the film is pushed off by the generated force. The average maximum temperature of the water film decreases as the film thickness increases. In contrast, the temperature achieved by the fast cooling due to the explosive evaporation shows an inverse trend. The significance of these model calculations to matrix-assisted laser desorption and ionization (MALDI) mass spectrometry is discussed. 相似文献
700.