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31.
Annette C. Feng Apu C. Kapadia Wu-Chun Feng Geneva G. Belford 《The Journal of supercomputing》2002,23(1):51-66
Streaming multimedia with UDP has become increasingly popular over distributed systems like the Internet. Scientific applications that stream multimedia include remote computational steering of visualization data and video-on-demand teleconferencing over the Access Grid. However, UDP does not possess a self-regulating, congestion-control mechanism; and most best-effort traffic is served by congestion-controlled TCP. Consequently, UDP steals bandwidth from TCP such that TCP flows starve for network resources. With the volume of Internet traffic continuing to increase, the perpetuation of UDP-based streaming will cause the Internet to collapse as it did in the mid-1980's due to the use of non-congestion-controlled TCP. To address this problem, we introduce the counter-intuitive notion of inter-packet spacing with control feedback to enable UDP-based applications to perform well in the next-generation Internet and computational grids. When compared with traditional UDP-based streaming, we illustrate that our approach can reduce packet loss over 50% without adversely affecting delivered throughput. 相似文献
32.
Knight CH Alamer MA Sorensen A Nevison lM Flint DJ Vernon RG 《The Journal of dairy research》2004,71(2):141-153
Three galactopoietic stimuli, frequent milking (4X), bovine somatotrophin (bST) and thyroxine (T4) were used in an additive stair-step design to achieve maximum output (metabolic capacity) in six peak-lactation cows of high genetic merit (HT) and six of low genetic merit (LT). A further six of each merit were untreated controls (HC, LC). Milk yield was increased significantly by 4X, increased further by the combination of 4X and bST and increased further still and significantly by the full combination of 4X, bST and T4. The magnitude of the yield response to the sequence of treatments did not differ significantly between HT and LT. The yield response to 4X and bST was sustainable without significant loss of body weight or body condition score for the 6 weeks during which these stimuli were administered. The response to the full combination, which included T4, was accompanied by significantly elevated heart rate and significant loss of body weight and condition compared with the combination of 4X and bST. As a result, treatments were discontinued, on an individual cow basis, before completion of this 6-week phase. Time on experiment did not differ between HT and LT. The results do not support the commonly held belief that selective breeding of dairy cows for high milk production has rendered them markedly more susceptible to metabolic disturbances. 相似文献
33.
34.
Indirect measuring of crack growth by means of a key-curve-method in pre-cracked Charpy specimens made of nodular cast iron 总被引:1,自引:0,他引:1
Andreas Emrich Uwe Michael Mühlich Meinhard Kuna Annette Ludwig Peter Trubitz 《International Journal of Fracture》2007,145(1):47-61
The determination of dynamic crack resistance curves from single specimen fracture tests requires information about the crack
advance during the experiment. Here, attention is focused on crack resistance curves for nodular cast iron based on experimental
data from instrumented Charpy tests. In order to estimate the actual crack length a key curve method (KCM) is employed. On
the other hand, the Charpy impact tests were realized numerically using finite element calculations in conjunction with a
continuum damage model (CDM) to simulate ductile crack growth. The parameters of the CDM model were determined from the experimental
data of single specimen fracture tests. Equivalence between the experimental and the numerical realization of a fracture test
was ensured by validating the predictions of the numerical simulations by means of low blow fracture tests. Comparison between
the crack advance predicted by the numerical simulations and the results obtained using the proposed KCM shows a sufficiently
well agreement with the actual crack length. Furthermore, crack resistance curves obtained from single specimen tests using
either standard estimation schemes in conjunction with the KCM or numerical simulations are compared with the predictions
based on low blow fracture tests. 相似文献
35.
In this paper we propose a new model for estimating the effective properties of regular hexagonal honeycombs. This model yields some new simple formulae which, in contrast to previous attempts, match the general invariant relations found by Vigdergauz in 1999. By comparing with numerical results, we also find some improved (but still simple) formulae which enable us to estimate the effective properties with an accuracy better than 1%, even for high density honeycombs. 相似文献
36.
Mahoney Annette; Pargament Kenneth I.; Jewell Tracey; Swank Aaron B.; Scott Eric; Emery Erin; Rye Mark 《Canadian Metallurgical Quarterly》1999,13(3):321
Ninety-seven couples completed questionnaires about their involvement in joint religious activities and their perceptions regarding the sanctification of marriage, including perceived sacred qualities of marriage and beliefs about the manifestation of God in marriage. In contrast to individual religiousness and religious homogamy (distal religious constructs), these proximal religious variables directly reflect an integration of religion and marriage, and they were associated with greater global marital adjustment, more perceived benefits from marriage, less marital conflict, more verbal collaboration, and less use of verbal aggression and stalemate to discuss disagreements for both wives and husbands. The proximal measures also added substantial unique variance (adjusted R2 change ranged from .06 to .48) to specific aspects of marital functioning after controlling demographic factors and distal religious variables in hierarchical regression analyses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
Stanton Annette L.; Kirk Sarah B.; Cameron Christine L.; Danoff-Burg Sharon 《Canadian Metallurgical Quarterly》2000,78(6):1150
Four studies demonstrate the psychometric adequacy and validity of scales designed to assess coping through emotional approach. In separate undergraduate samples, exploratory and confirmatory factor analyses of dispositional (Study 1) and situational (Study 3) coping item sets yielded 2 distinct emotional approach coping factors: emotional processing (i.e., active attempts to acknowledge and understand emotions) and emotional expression. The 2 scales yielded high internal consistency and test-retest reliability, as well as convergent and discriminant validity. A study (Study 2) of young adults and their parents established the scales' interjudge reliabilities. Longitudinal (Study 3) and experimental (Study 4) research supported the predictive validity of the emotional approach coping scales with regard to adjustment to stressful encounters. Findings highlight the utility of functionalist theories of emotion as applied to coping theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
38.
Stanton Annette L.; Lobel Marci; Sears Sharon; DeLuca Robyn Stein 《Canadian Metallurgical Quarterly》2002,70(3):751
Emphasizing research published in the past decade, this article presents a summary and evaluation of psychosocial investigations of women's reproductive health, with a focus on selected aspects of menstruation, pregnancy and birth, infertility, and menopause. In some areas, studies have focused on negative physical and psychological concomitants of these health issues. However, research reveals substantial individual variability, with most women adapting well to reproductive health changes. Although methodological and conceptual shortcomings have limited firm conclusions, research has advanced our understanding of the multivariate biological, psychological, and social influences on women's reproductive health and associated outcomes. Understanding and promoting women's reproductive health across the lifespan requires biopsychosocial approaches to research. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
39.
A variety of different experimental results show substantial evidence that the order parameter in high-temperature superconducting copper oxides is not of pure d-wave symmetry, but that an s-wave component exists, which especially shows up in experiments that test the c-axis properties. These findings are modeled theoretically within a two-band model with interband interactions, where the superconducting order parameters in the two bands are allowed to differ in symmetry. It is found that the coupling of order parameters with different symmetries (s+d) leads to substantial enhancements of the superconducting transition temperature T
c as compared to order parameters with only s-wave symmetry. An additional enhancement factor of T
c is obtained from the coupling of the bands to the lattice where moderate couplings favor superconductivity while too strong couplings lead to electron (hole) localization and consequently suppress superconductivity. 相似文献
40.
Windschitl Paul D.; Martin René; Flugstad Annette R. 《Canadian Metallurgical Quarterly》2002,82(5):742
Four experiments investigated how people's perceptions about a group's (e.g., women's) vulnerability to a disease are influenced by information about the prevalence of the disease in a comparable group (e.g., men). Participants read symptom and prevalence information about fictitious diseases before answering questions regarding target group vulnerability. Participants used the prevalence rate for a nontarget group as an immediate comparison standard for intuitively interpreting the degree of vulnerability of a target group, resulting in robust contrast effects. Experiments 3 and 4 illustrated that these contrast effects can cause a person's intuitive perceptions about a group's vulnerability to selected diseases to conflict with his or her knowledge of the prevalence rates for the diseases. The results support a distinction between 2 components of psychological uncertainty--beliefs in objective probability and more intuitive perceptions of certainty. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献