摘要 :
Motivated by a variety of applications in information and communication systems, we consider queueing networks in which the service rate at each of the individual nodes depends on the state of the entire system. The asymptotic beh...
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Motivated by a variety of applications in information and communication systems, we consider queueing networks in which the service rate at each of the individual nodes depends on the state of the entire system. The asymptotic behaviour of this type of networks is fundamentally different from classical queueing networks, where the service rate at each node is usually assumed to be independent of the state of the other nodes. We study the per-node rate stability and output rates for a general class of feed-forward queueing networks with a general capacity allocation function. More specifically, we derive necessary conditions of per-node rate stability, and give bounds for the per-node output rate and asymptotic growth rates, under mild assumptions on the allocation function. For a set of parallel nodes, we further prove the convergence of the output rates and give a sharp characterization of the per-node rate stability. The results provide new intuition and fundamental insight in the stability and throughput behavior of queueing networks with shared resources.
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This report presents revised birth and fertility rates for 2000 and 2001, based on populations consistent with the April 1, 2000, census. Rates are presented by age, race, and Hispanic origin of mother; by age, race, and Hispanic ...
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This report presents revised birth and fertility rates for 2000 and 2001, based on populations consistent with the April 1, 2000, census. Rates are presented by age, race, and Hispanic origin of mother; by age, race, and Hispanic origin of mother for unmarried women; and by age and race of father. To put the rates for 2000 and 2001 into context, rates are also shown for 1990.
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We analyze the effects of money injections on interest rates and exchange rateswhen agents must pay a Baumol-Tobin style fixed cost to exchange bonds and money. Asset markets are endogenously segmented because this fixed cost lead...
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We analyze the effects of money injections on interest rates and exchange rateswhen agents must pay a Baumol-Tobin style fixed cost to exchange bonds and money. Asset markets are endogenously segmented because this fixed cost leads agents to trade bonds and money infrequently. When the government injects money through an open market operation, only those agents that are currently trading absorb these injections. Through their impact on these agents consumption, these money injections affect real interest rates and real exchange rates. The model generates the observed negative relation between expected inflation and real interest rates as well as persistent liquidity effects in interest rates and volatile and persistent exchange rates.
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Eight hundred eighty-two airmen were divided into more accurate and less accurate rating groups on the basis of their ability to estimate scores of their peers on a vocabulary test. To test whether the method actually did separate...
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Eight hundred eighty-two airmen were divided into more accurate and less accurate rating groups on the basis of their ability to estimate scores of their peers on a vocabulary test. To test whether the method actually did separate more accurate from less accurate raters, correlations were calculated within the more and less accurate groups between ratings of carefulness and scores on carefulness tests and between ratings of decisiveness and scores on decisiveness tests. The analysis consisted of counting the number of times the correlations between test scores and ratings in the more accurate group were larger than the analogous correlations in the less accurate group and computing the probability that this number of differences in the predicted direction might be expected by chance. It appears that this method of identifying accurate raters does work reasonably well. Several auxiliary questions concerning the best qualities to test in the estimating part of the study and the generalizability of rater accuracy to different personality characteristics were asked and answered. (Author)
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Managers choose credit rating targets by trading off the benefits associated with a high rating against the higher cost of capital associated with the additional equity required to maintain the high rating. We find that small and ...
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Managers choose credit rating targets by trading off the benefits associated with a high rating against the higher cost of capital associated with the additional equity required to maintain the high rating. We find that small and risky firms tend to target lower ratings, whereas firms with high growth opportunities tend to target higher ratings. In addition, firms with small boards and large blockholders tend to target lower ratings. We also find that deviations from rating targets influence subsequent capital structure choices. When observed ratings are below (above) the target, managers tend to make security issuance and repurchase decisions that reduce (increase) leverage. In addition, firms are more likely to increase dividend payouts when they have above target ratings and are less likely to make acquisitions when they have below target ratings.
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This report describes the High Power Modulator (HPM) which was constructed for the Naval Research Laboratory (NRL) by Pulse Sciences Incorporated of San Leandro, California (PSI) in accordance with the specifications set forth in ...
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This report describes the High Power Modulator (HPM) which was constructed for the Naval Research Laboratory (NRL) by Pulse Sciences Incorporated of San Leandro, California (PSI) in accordance with the specifications set forth in contract N00014-86-C-2020. The nominal electrical specifications for the HPM were to produce a 1 microsec. flattop (x or- 3%) pluse with a minimum amplitude of 200 kV into a 400 ohm resistive load but with a design goal of 250 kV. The HPM meets or exceeds the design goals. The HPM has three modes of operation; 1) single shot, 2) continuous repetitive at rates up to 1 Hz, and 3) burst for up to 50 pulses at rates up to 100 Hz. The operating modes as well as their associated parameters are switch selectable through a sophisticated control system.
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It is shown that the monotone multivariate hazard and failure rates of Harris and of Brindley and Thompson have no natural analog involving the multivariate failure rate function of Basu for absolutely continuous distributions. Qu...
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It is shown that the monotone multivariate hazard and failure rates of Harris and of Brindley and Thompson have no natural analog involving the multivariate failure rate function of Basu for absolutely continuous distributions. Quantities related to the multivariate failure rate function are used to define monotone hazard and failure rates. It is shown that these are equivalent to the monotone hazard and failure rates of Harris and of Brindley and Thompson. Based on these quantities, the loss of memory property of Marshall and Olkin is characterized. (Author)
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The Surface Transportation Board (STB or Board) monitors freight railroad rates in the United States. Periodically, the STBs Section of Economics distills its data and analysis of freight rail rates into formal reports that are sh...
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The Surface Transportation Board (STB or Board) monitors freight railroad rates in the United States. Periodically, the STBs Section of Economics distills its data and analysis of freight rail rates into formal reports that are shared with the Board and the public. This updated report summarizes our latest findings on trends in freight railroad rates and brings our measurement of the rail rate index up through 2007. The data used to prepare this report come from the STBs Carload Waybill Sample (Waybill Sample). Certain limitations exist with this information that will be discussed in detail later; however, we find that the data present a useful way to monitor rates. In addition, we have significantly improved our rate index so it does a better job accounting for changes in service type and car ownership.
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