365 research outputs found
Validation of simulated real world TCP stacks
No full textThe TCP models in ns-2 have been validated and are widely used in network research. They are however not aimed at producing results consistent with a TCP implementation, they are rather designed to be a general model for TCP congestion control. The Network Simulation Cradle makes real world TCP implementations available to ns-2: Linux, FreeBSD and OpenBSD can all be simulated as easily as using the original simplified models. These simulated TCP implementations can be validated by directly comparing packet traces from simulations to traces measured from a real network. We describe the Network Simulation Cradle, present packet trace comparison results showing the high degree of accuracy possible when simulating with real TCP implementations and briefly show how this is reflected in a simulation study of TCP throughput
Recent Advancements in Continuous Wheel Slip Control
No full textThe paper presents an overview of continuous wheel slip control (WSC) methods as the part of anti-lock braking system (ABS) for the several vehicles configurations with friction brakes and electric motors. Performance of proposed WSC design variants using several control techniques has been experimentally evaluated for three different test vehicles: Sport Utility Vehicle (SUV) with decoupled electro-hydraulic brake (DEHB) system, SUV with four individual on-board electric motors (OBM), and compact vehicle with four individual in-wheel motors (IWM). Obtained results demonstrated that proposed continuous WSC variants provide a simultaneous effect on braking efficiency and ride quality as well as robust operation in various road conditions. Presented summary provides outlook on future perspectives of the continuous WSC and compares its status with conventional rule-based ABS systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Vehicle
Complex systems modeling for supply and demand in health and social care
No full textThis paper introduces a major new cross-disciplinary research project that looks at the UK health and social care system, as part of an ambitious, broader initiative to apply methods from complexity science to a range of key global challenges. This particular project aims to develop new, integrated models for the supply and demand of both health and social care, in the context of the societal change brought about by migration, mobility and the ageing population. We discuss the background to the work, and the broad way in which we intend to leverage complexity science. This is made more specific with a brief discussion on existing demographic models, and some examples of model-building in progress. We conclude with a glimpse into the subtly difficult problems of fostering such innovative interdisciplinarity
Seasonal to interannual variability in density around the Canary Islands and their influence on the Atlantic meridional overturning circulation at 26°N
No full textThe meridional interior flow obtained from the RAPID array is determined by horizontal density fluctuations at the eastern and western boundary of 26°N. The physical causes of these density variations are responsible for fluctuations in the Atlantic Meridional Overturning Circulation (AMOC) and through it, the meridional heat transport of the Atlantic. In this modelling study, a high resolution ocean model is used to investigate the source and origin of the AMOC variability associated with the density fluctuations at the eastern boundary. The AMOC in the model is in good agreement with the RAPID observations and appears to adequately represent the smaller scale features of variability around the Canary Islands. In this paper, we identify a robust relationship between the density structure south of the Canary Islands, the local wind stress curl (WSC) around these islands and the AMOC using an empirical orthogonal functions analysis, wavelet transform and wavelet coherence. We find that the deep density fluctuations at the eastern boundary of 26°N arise from the pumping effect of the spatial pattern of WSC south of the islands. These deep density fluctuations drive the AMOC both on seasonal and interannual timescales, through their influence on the basinwide tilt of the thermocline. At seasonal timescales, the density fluctuations south of the islands are driven by the WSC and directly influence the AMOC. At interannual timescales, a significant coherence is found between the density fluctuation and the southward UMO transport although the origin of these density fluctuations is not explained by the the direct pumping caused by the WSC
Genetic variation in water-soluble carbohydrate concentration in diverse cultivars of Dactylis glomerata L. during vegetative growth
No full textThe water-soluble carbohydrate (WSC) content of Dactylis glomerata L. (cocksfoot) during vegetative growth is lower than that of other temperate grasses. Variation in the WSC content of vegetative growth among cultivars was assessed in order to assess the potential to improve forage quality. There were significant differences among cultivars for WSC content (P<0.01) in all maturity groups. Average WSC content of the late (L) maturity group was higher than that of the early (E) and medium (M) maturity groups. Variation in the WSC content was largest among group L cultivars and smallest in group M. The WSC content of cultivars in groups M and L was consistent across 2 years (interactions between cultivars and years were not significant). Brown stripe infection was shown to reduce WSC content in susceptible cultivars. As a result of multiple regression analysis with WSC content as the dependent variable, dry matter content, heading date, thickness of stems and resistance to brown stripe were selected as independent variables that were correlated with WSC. Therefore, variation for these traits must also be monitored in any program to increase WSC content in orchardgrass
Inheritance of concentration of water-soluble carbohydrates in cocksfoot
No full textThe concentration of water-soluble carbohydrates (WSC) of cocksfoot is lower than that of other temperate grasses. Increasing in the WSC concentration in cocksfoot is important in increasing its digestibility and preference by ruminants. The genetic variation in mono- and disaccharides, fructans and total WSC concentrations and their interrelationships with crude protein (CP) and fibre concentrations of cocksfoot (Dactylis glomerata L.) at the vegetative growth stage in half-sib cross populations were assessed in two experiments conducted under spaced-planting and sward conditions. There was a wide range in the means for concentrations of fructan, WSC and neutral-detergent fibre (NDF) in parents and progeny whereas there was a narrow range of the means for concentrations of mono- and disaccharides, CP and acid-detergent fibre (ADF). Mean concentrations of mono- and disaccharides showed the smallest range. Mean squares of entries in parents and progenies were significant for mono- and disaccharides, fructan and total WSC concentrations in all populations. The entry × year interactions for fructan and total WSC concentrations were significant in parents and half-sib progeny. However, the entry × year interactions for mono- and disaccharide concentrations in progeny were not significant. Concentration of WSC was under genetic control since mean squares of the concentration values were significant and variance components for all traits were significantly larger than zero. There were negative genetic correlations between WSC and ADF and NDF concentrations. Narrow sense heritabilities (hn) estimated from variance components of progeny for total WSC concentrations were 0.59 and 0.53 in sward and space-planting conditions, respectively. The hn of fructan and WSC concentrations were similar in both sward and spaced-planting conditions, whereas that of mono- and disaccharide concentrations varied from 0.20 to 0.69. It was found that the genetic variation of total WSC concentration in cocksfoot depended mainly on genetic variation in fructan concentration. These results suggested that the forage quality of cocksfoot at the vegetative growth stage was influenced by an additive gene effect and could be improved genetically by recurrent selection
Planning of bed capacities in specialized and integrated care units: Incorporating bed blockers in a simulation of surgical throughput
No full textThe ethics of computer modeling and simulation
No full textThis paper describes a framework for ethical analysis of the practice of computer Modeling & Simulation (M&S). Each of the authors presents a computational model as a case study and offers an ethical analysis by applying the philosophical, scientific, and practical components of the framework. Each author also provides a constructive response to the other case studies. The paper concludes with a summary of guidelines for using this ethical framework when preparing, executing, and analyzing M&S activities. Our hope is that this collaborative engagement will encourage others to join a rich and ongoing conversation about the ethics of M&S.Information and Communication Technolog
Ecotypic variation of water-soluble carbohydrate concentration and winter hardiness in cocksfoot (Dactylis glomerata L.)
No full textThe variation of the water-soluble carbohydrate (WSC) concentration in foliage and stubble and winter hardiness among cocksfoot (Dactylis glomerata L.) ecotypes originated from diverse countries were studied in the field in order to find a breeding material for the improvement of WSC. The total WSC concentration of foliage was found to be highest in Japanese cultivars and lowest in ecotypes from northern Europe in summer and autumn. The variation of fructan concentration in stubble among ecotypes was larger than the variation of mono and disaccharide concentrations in stubble and that of total WSC concentration in foliage in both winters over which this study was conducted. The total WSC and fructan concentrations in the stubble of ecotypes from Spain and southern Europe, derived from the Mediterranean region, were highest in summer. Ecotypes from Japan showed the highest concentration of total WSC in stubble, and were especially high in fructan concentration in autumn. Ecotypes from France, central Europe and central Asia, like Japanese cultivars, also showed a high fructan concentration. The latitude of origin was negatively correlated with WSC concentration and plant vigor in autumn. The altitude of origin was negatively correlated with plant vigor in autumn and positively correlated with fructan concentration in stubble, winter hardiness and snow endurance. Typhula snow blight resistance was related with the amount of the increase in fructan in the plants and with their growth habits in autumn. The fructan concentration of foliage and stubble in autumn was found to be closely related with winter hardiness in cocksfoot ecotypes. A breeding material which has a high WSC concentration in the foliage could not be found among the ecotypes in this study. However, some ecotypes that showed disease resistance, good winter hardiness and plant vigor would be useful as breeding materials for Hokkaido
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