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991.
Buffer analysis has traditionally relied heavily on the use of traffic models with short range (exponentially decaying) autocorrelation, e.g. Poisson and Markov modulated Poisson processes. Recent literature has suggested the presence of traffic with slowly (hyperbolically) decaying autocorrelation functions; these sources collectively and individually seem to be exhibiting the phenomenon of long range dependence (LRD). Furthermore, it has been claimed that this sort of traffic may exhibit behaviour, when buffered, that is advantageous in that a smaller buffer may be required than would be the case with non-LRD traffic. This phenomenon has been named the crossover effect, and the authors quantify its relevance to ATM networking, using simulation studies of a homogenous mix of chaotic sources. These show that there is a crossover effect, but the key finding is that this effect is much nearer to a buffer length of zero than was predicted by previous theoretical studies, actually occurring at a value so low that it has no practical significance 相似文献
992.
In reference to the above-titled paper by R.A. DeMillo and A.J. Offutt (see ibid., vol.17, no.9, p.900-10, Sept. 1991), the commenter rates that he and M.R. Woodward (1985) implemented a system for FORTRAN-77 programs that integrates weak mutation and data flow analysis. He reports here that experiments have been carried out by them (1986), using the system to compare the error exposing ability of weak mutation, data flow, and control flow testing strategies 相似文献
993.
The paper presents a review of results concerning the aspartic proteinase cathepsin D and its role in tumor invasion and metastasis. Special attention was paid to the clinical prognostic value of cathepsin D determination in the breast cancer cytosol. 相似文献
994.
Ivo M. Babuka Rodolfo Rodriguez 《International journal for numerical methods in engineering》1993,36(4):539-567
This paper addresses the problem of assessing the quality of an a posteriori error estimate of a finite element solution. An error estimate based on local L2-projections is analysed in the case of translation-invariant meshes. It is shown that for general meshes this technique does not lead to an asymptotically exact estimator. The problem is analysed in detail in the one-dimensional setting. It is shown that an asymptotically exact estimator is not the optimal one when the solution is not sufficiently smooth. An optimal estimator for adaptively constructed meshes is given. Finally, a general mathematical framework for the quality assessment of estimators is introduced. 相似文献
995.
L Struillou M Fiks-Sigaud JH Barrier E Blat G Magadur-Joly 《Canadian Metallurgical Quarterly》1993,60(7-8):524-526
The authors report an exceedingly rare complication of rheumatoid arthritis, i.e. acquired hemophilia due to anti-factor VIII autoantibody production. Treatment with intravenous immune globulin ensured control of hemorrhagic manifestations by inducing a transient rise in factor VIII level. 相似文献
996.
It was found, that To?pa Peat Preparation (TPP) administered to healthy volunteers in doses of 100-300 mg/day during 14 days evoked the stimulation of the phagocytic and bactericidal activity of the granulocytes. The dose of 600 mg/day causes only a transient and insignificant increase of phagocytic and bactericidal properties of the granulocytes. 相似文献
997.
998.
T Noda M Arakawa T Takaya T Nagano K Kagawa H Miwa S Hirakawa 《Canadian Metallurgical Quarterly》1993,14(7):876-884
To evaluate right atrial (RA) contractile performance in patients with myocardial infarction, we validated a cineangiographic method of RA volume measurement, and investigated RA volume change in 'normal' individuals and patients with a previous myocardial infarction. Sixteen silicone rubber RA casts made from human cadavers were filmed in the postero-anterior and left lateral projections. The cast volumes calculated following Simpson's rule were in good agreement with those measured by water replacement (r = 0.992, P < 0.01). At cardiac catheterization, biplane RA cineangiography was performed in 19 'normal' individuals (N group), in 14 patients with a previous antero-septal infarction (AMI group) and in seven patients with a previous inferior infarction (IMI group). The RA volume-time curve was constructed at 20-40 ms intervals for one cardiac cycle. RA volume at the beginning of the atrial contraction (RAVd), which was defined as the 'preload' of the RA, tended to be larger in both the AMI and IMI groups compared with 'normal' individuals. The RA ejection volume was significantly larger in both the AMI (18.4 +/- 2.1 ml.m-2, P < 0.01) and IMI groups (19.4 +/- 2.8, P < 0.01) than in the N group (14.5 +/- 1.9), even for a comparable level of RAVd (range from 26 to 36 ml.m-2) (18.6 +/- 2.1, P < 0.01, 18.2 +/- 2.0, P < 0.01, 14.7 +/- 1.9, respectively). These results suggest that RA contraction increases in patients with myocardial infarction by increasing both the 'preload' and 'contractility' of the RA. 相似文献
999.
I Frías MT Caldeira JR Pérez-Casti?eira JP Navarro-Avi?ó FA Culia?ez-Maciá O Kuppinger H Stransky M Pagés A Hager R Serrano 《Canadian Metallurgical Quarterly》1996,8(9):1533-1544
The plasma membrane (PM) H(+)-ATPase has been proposed to play important transport and regulatory roles in plant physiology, including its participation in auxin-induced acidification in coleoptile segments. This enzyme is encoded by a family of genes differing in tissue distribution, regulation, and expression level. A major expressed isoform of the maize PM H(+)-ATPase (MHA2) has been characterized. RNA gel blot analysis indicated that MHA2 is expressed in all maize organs, with highest levels being in the roots. In situ hybridization of sections from maize seedlings indicated enriched expression of MHA2 in stomatal guard cells, phloem cells, and root epidermal cells. MHA2 mRNA was induced threefold when nonvascular parts of the coleoptile segments were treated with auxin. This induction correlates with auxin-triggered proton extrusion by the same part of the segments. The PM H(+)-ATPase in the vascular bundies does not contribute significantly to auxin-induced acidification, is not regulated by auxin, and masks the auxin effect in extracts of whole coleoptile segments. We conclude that auxin-induced acidification in coleoptile segments most often occurs in the nonvascular tissue and is mediated, at least in part, by increased levels of MHA2. 相似文献
1000.
Fuzzy logic control of a switched reluctance motor drive 总被引:2,自引:0,他引:2
The paper deals with the fuzzy logic control of a switched reluctance motor (SRM) drive. The fundamentals of the fuzzy logic are first illustrated, pointing out the aspects related to the control under consideration. A fuzzy logic controller (FLC) of the motor speed is then designed and simulated. The results show that the use of an FLC in the speed loop gives the drive superior performances. In particular, the robustness of the drive has been proved 相似文献