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Stewart C. Kai Shen Dwarkadas S. Scott M.L. Jian Yin 《Distributed Systems Online, IEEE》2004,5(10):1-1
The growth of the Internet and of various intranets has spawned a wealth of online services, most of which are implemented on local-area clusters using remote invocation (for example, remote procedure call/remote method invocation) among manually placed application components. Component placement can be a significant challenge for large-scale services, particularly when application resource needs are workload dependent. Automatic component placement has the potential to maximize overall system throughput. The key idea is to construct (offline) a mapping between input workload and individual-component resource consumption. Such mappings, called component profiles, then support high-performance placement. Preliminary results on an online auction benchmark based on J2EE (Java 2 Platform, Enterprise Edition) suggest that profile-driven tools can identify placements that achieve near-optimal overall throughput. 相似文献
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Thomas S. Lowry John C. Bright Murray E. Close Christina A. Robb Paul A. White Stewart G. Cameron 《国际水资源开发杂志》2003,19(4):579-592
The primary objective of this project is to identify gaps, whether real or perceived, that hinder effective groundwater management in New Zealand. These gaps show as gaps in information, gaps in implementation, gaps in technological and management tools, and gaps in understanding of fundamental processes. The secondary objective is to propose a management strategy to close the identified gaps. Several methods are used to meet these objectives: surveys distributed to selected staff in each regional council; the review of various written reports; the analysis of land-use databases; and private consultation within each regional council. Results show that groundwater management in New Zealand is generally reactionary with the main gaps being in strategic planning and national guidelines. Most gaps appear to be predominantly information and implementation issues. In some cases there are gaps in the understanding of fundamental processes within an aquifer system, including the long-term effects of land-use on groundwater quality. An adaptive management approach is suggested as a means of closing these gaps. 相似文献
4.
A coupled cell system is a network of dynamical systems, or 'cells', coupled together. Such systems can be represented schematically by a directed graph whose nodes correspond to cells and whose edges represent couplings. A symmetry of a coupled cell system is a permutation of the cells and edges that preserves all internal dynamics and all couplings. It is well known that symmetry can lead to patterns of synchronized cells, rotating waves, multirhythms, and synchronized chaos. Recently, the introduction of a less stringent form of symmetry, the 'symmetry groupoid', has shown that global group-theoretic symmetry is not the only mechanism that can create such states in a coupled cell system. The symmetry groupoid consists of structure-preserving bijections between certain subsets of the cell network, the input sets. Here, we introduce a concept intermediate between the groupoid symmetries and the global group symmetries of a network: 'interior symmetry'. This concept is closely related to the groupoid structure, but imposes stronger constraints of a group-theoretic nature. We develop the local bifurcation theory of coupled cell systems possessing interior symmetries, by analogy with symmetric bifurcation theory. The main results are analogues for 'synchrony-breaking' bifurcations of the Equivariant Branching Lemma for steady-state bifurcation, and the Equivariant Hopf Theorem for bifurcation to time-periodic states. 相似文献
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Stewart L. Stokes Jr. 《Information Systems Management》1994,11(3):34-40
Mentoring has been around for ages, often masquerading as the management club or the fast track. Among successful business unit managers, mentoring is a well-understood practice, and it's a career development strategy today's IS professional would be wise to consider. 相似文献
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Guangyan Li W. Ian Hamilton Ged Morrisroe Theresa Clarke 《Cognition, Technology & Work》2006,8(1):30-40
A study was carried out using simulation to investigate driver responses to lineside signals and signs at various approach
speeds. The objectives of the study were: (1) to find out whether train speed would significantly affect signal/sign reading;
(2) to examine at which point certain types of signs or signals could be detected or recognised, and (3) to determine a speed
cut-off level above which certain types of signs or signals are no longer recognisable or detectable. Fifty-seven train drivers
from 12 Train Operating Companies in the UK participated in the trials. Twenty different types of lineside signs and ten types
of signals were tested under six different approach speeds ranging from 100 to 350 km/h (62–218 mph). Driver performance measures
were ‘time remaining to the signal/sign’ at the point of detection or recognition, and reading error rate. The results showed
a significant influence of train speed on driver responses to lineside signals/signs and demonstrated a non-linear relationship
between driver responses to signals/signs and approach speed. This has been used to estimate a maximum approach speed limit
within which a specific signal or sign can be correctly detected or recognised. The findings and implications of the study
are discussed in the paper. 相似文献
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OBJECTIVE: To describe an outbreak of hepatitis A virus (HAV) infection that occurred in Melbourne in 1991. DESIGN: (i) We reviewed Health Department Victoria surveillance data from 1989 to 1991 (primary surveillance) and identified all notified cases of HAV infection with an onset of illness between 1 January and 31 December 1991 (secondary surveillance data). (ii) We studied HAV seroprevalence in Melbourne among homosexual men attending gay venues. RESULTS: (i) In the two years 1989-1990 there were only 55 notifications of HAV infection to Health Department Victoria, with a male:female ratio of 1.2:1. Of the 495 notifications for 1991, 407 (82%) were male, of whom 210 (52%) were known to be homosexual. Many reported sexual and social contact at Melbourne's gay venues and with the Sydney gay community. (ii) Of men attending gay venues, 27% had serological evidence of past infection with HAV, compared with 45.8% in a 1981 Melbourne study. CONCLUSION: The outbreak of HAV infection in Victoria largely affected homosexual males in their sexually active years. Contact with the Sydney gay community was commonly reported. 相似文献
10.
Different forms of generativity in the writings of E. H. Erikson (1950/1963) and J. Kotre (1984) were related to agentic and communal motives in a sample of young adults (M?=?28 yrs old). For women, the power motive related to parenting, whereas the achievement motive was associated with forms of generative expression outside of the household. The opposite pattern of achievement and power motive relationships was found for men, although in a weaker form. The affiliation–intimacy motive, on the other hand, related both to women's parenting and societal concerns. Differences in expectations and opportunities for young men and women may account for these gender differences. The results for women support D. P. McAdams's (1988) suggestions that agency and communion are important for understanding generativity. In addition, the results provide evidence that people begin to grapple with generative issues as young adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献