有限元方法计算J积分

本文讨论了有限元方法计算Ｊ积分，并依据能量区域积分方法编制了计算机程序，通 过对ＣＣＴ试块的计算表明程序可靠准确。     

Responses of Human Cells to PAH-Induced DNA Damage

Benzo[ a ]pyrene (B[ a ]P) and dibenzo[ a,l ]pyrene (DB[ a,l ]P) induce cytochrome P450 (CYP) CYP1A1 and CYP1B1, which metabolize these polycyclic aromatic hydrocarbons (PAHs) into DNA-binding species. In order to detail roles of CYP1A1 and CYP1B1 in activation of DB[ a,l ]P to the diol epoxide, we here report the inhibition of CYP1A1 in human MCF-7 cells with phosphorodiamidate morpholino antisense oligomers (morpholinos). PAH-DNA adduct formation was also determined after treatment with morpholinos and B[ a ]P or DB[ a,l ]P. p53 is involved in DNA repair, cell cycle arrest, and apoptosis. Cells with normal p53 protein arrest in the G1 phase of the cell cycle on exposure to DNA-damaging agents (presumably allowing the cell sufficient time to repair damaged DNA prior to replication). Previous studies in human MCF-7 cells indicate that cells with PAH-DNA adducts escape cell cycle arrest and accumulate in the S phase. In the present study the effect of PAH-DNA adducts on the cell cycle were observed in human diploid fibroblasts (HDF). We found that treatment of HDF with the diol epoxide of DB[ a,l ]P causes cell cycle arrest in G 1 . An increase in DNA adduct formation with increase in concentration of dibenzo[ a,l ]pyrene diol epoxide {( m )- anti -DB[ a,l ]PDE} was also observed.     

Ambient media for peripheral information display

In our everyday lives, we use surrounding living and working environments to arrange physical information artefacts such as books, pictures and calendars. However, when it comes to consumption of computer-based information, this is almost entirely based on attending to screens that separate us from our surroundings. In this paper, we explore the augmentative use of non-computer artefacts in our surroundings for peripheral display of digital information. We discuss system integration of such ambient media, the mapping of information to ambient media, and issues of flexibility and user control. Ambient media have been in everyday use in our work environment, and we report observations from which we conclude their utility as extensions to our digital information spaces.     

Premixed and nonpremixed generated manifolds in large-eddy simulation of Sandia flame D and F

Premixed and nonpremixed flamelet-generated manifolds have been constructed and applied to large-eddy simulation of the piloted partially premixed turbulent flames Sandia Flame D and F. In both manifolds the chemistry is parameterized as a function of the mixture fraction and a progress variable. Compared to standard nonpremixed flamelets, premixed flamelets cover a much larger part of the reaction domain. Comparison of the results for the two manifolds with experimental data of flame D show that both manifolds yield predictions of comparable accuracy for the mean temperature, mixture fraction, and a number of chemical species, such as CO₂. However, the nonpremixed manifold outperforms the premixed manifold for other chemical species, the most notable being CO and H₂. If the mixture is rich, CO and H₂ in a premixed flamelet are larger than in a nonpremixed flamelet, for a given value of the progress variable. Simulations have been performed for two different grids to address the effect of the large-eddy filter width. The inclusion of modeled subgrid variances of mixture fraction and progress variable as additional entries to the manifold have only small effects on the simulation of either flame. An exception is the prediction of NO, which (through an extra transport equation) was found to be much closer to experimental results when modeled subgrid variances were included. The results obtained for flame D are satisfactory, but despite the unsteadiness of the LES, the extinction measured in flame F is not properly captured. The latter finding suggests that the extinction in flame F mainly occurs on scales smaller than those resolved by the simulation. With the presumed β-pdf approach, significant extinction does not occur, unless the scalar subgrid variances are overestimated. A thickened flame model, which maps unresolved small-scale dynamics upon resolved scales, is able to predict the experimentally observed extinction to some extent.     

Analysis of poly(chlorophenyl methacrylates) by ultraviolet spectroscopy

Summary A number of copolymers of methyl methacrylate and chlorophenyl methacrylates of different structure was prepared and analyzed by ultraviolet spectroscopy. It was found that the copolymer composition can be determined using a calibration curve based on mixtures of the appropriate homopolymers. The U. V. spectroscopical results are in good agreement with the chlorine analysis.     

Path controllability of linear input-output systems

The varied definitions used in four studies of path controllability of linear input-output systems are given, their similarities and differences examined, and some of their corresponding results compared and discussed.     

Flexural Response of Steel Beams Strengthened with Partial-Length CFRP Plates

This paper presents the flexural behavior of rolled steel beams that were strengthened with partial-length, adhesive-bonded carbon fiber-reinforced polymer (CFRP) plates. The hybrid beams had two types of failure mode, depending on the length of the plate: (1) plate debonding in beams with short plates;?and (2) plate rupture at midspan in beams with long plates. The flexural behavior that was investigated includes the development of tensile stresses in the plate, the moment-curvature of the strengthened section, and the load-deflection of the strengthened beam. The analytical methods used include shear lag analysis, section analysis, and application of the virtual work principle. Agreement between the experimental results and the analytical predictions is discussed.