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Model Predictions (model + prediction)
Kinds of Model Predictions Selected AbstractsMODEL PREDICTION FOR SENSORY ATTRIBUTES OF NONGLUTEN PASTAJOURNAL OF FOOD QUALITY, Issue 6 2001JEN-CHIEH HUANG ABSTRACT Response surface methodology was used to predict sensory attributes of a nongluten pasta and develop response surface plots to help visualize the optimum region. Optimum regions of xanthan gum, modified starch, and locust bean gum were selected by overlapping the contour plots of sensory properties of nongluten pasta as compared with the control pasta. The formula of nongluten pasta that possessed the most desirable properties was xanthan gum at 40 g, modified starch at 35 g, locust bean gum at 40 g, tapioca starch at 113 g, potato starch at 57 g, corn flour at 250 g, and rice flour at 50 g. The quality of nongluten pasta could be improved by using different levels of nongluten starches and flours, and nonstarch polysaccharides. [source] Remote Monitoring Integrated State Variables for AR Model Prediction of Daily Total Building Air-Conditioning Power ConsumptionIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 5 2010Chuzo Ninagawa Member Abstract It is extremely difficult to predict daily accumulated power consumption of the entire building air-conditioning facilities because of a huge number of variables. We propose new integrated state variables, i.e. the daily operation amount and the daily operation-capacity-weighted average set temperature. Taking advantage of a remote monitoring technology, time series data of the integrated state variables were collected and an autoregressive (AR) model prediction for the daily total power consumption has been tried. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Computational Network Model Prediction of Hemodynamic Alterations Due to Arteriolar Remodeling in Interval Sprint Trained Skeletal MuscleMICROCIRCULATION, Issue 3 2007Kyle W. Binder ABSTRACT Objectives: Exercise training is known to enhance skeletal muscle blood flow capacity, with high-intensity interval sprint training (IST) primarily affecting muscles with a high proportion of fast twitch glycolytic fibers. The objective of this study was to determine the relative contributions of new arteriole formation and lumenal arteriolar remodeling to enhanced flow capacity and the impact of these adaptations on local microvascular hemodynamics deep within the muscle. Methods: The authors studied arteriolar adaptation in the white/mixed-fiber portion of gastrocnemius muscles of IST (6 bouts of running/day; 2.5 min/bout; 60 m/min speed; 15% grade; 4.5 min rest between bouts; 5 training days/wk; 10 wks total) and sedentary (SED) control rats using whole-muscle Microfil casts. Dimensional and topological data were then used to construct a series of computational hemodynamic network models that incorporated physiological red blood cell distributions and hematocrit and diameter dependent apparent viscosities. Results: In comparison to SED controls, IST elicited a significant increase in arterioles/order in the 3A through 6A generations. Predicted IST and SED flows through the 2A generation agreed closely with in vivo measurements made in a previous study, illustrating the accuracy of the model. IST shifted the bulk of the pressure drop across the network from the 3As to the 4As and 5As, and flow capacity increased from 0.7 mL/min in SED to 1.5 mL/min in IST when a driving pressure of 80 mmHg was applied. Conclusions: The primary adaptation to IST is an increase in arterioles in the 3A through 6A generations, which, in turn, creates an approximate doubling of flow capacity and a deeper penetration of high pressure into the arteriolar network. [source] Thermal Degradation Kinetics of Nylon 66: Experimental Study and Comparison with Model PredictionsMACROMOLECULAR REACTION ENGINEERING, Issue 5 2007Mark A. Schaffer Abstract An experimental investigation of nonoxidative thermal degradation kinetics of nylon 66 melt under high temperature (280,300,°C) and low water content (0.02,0.14 wt.-%) conditions is presented. Experimental data for the time evolution of polymer end-group concentrations and degradation-product generation rates were compared with the predictions of the only published kinetic model. The omitted influence of water content is a plausible partial explanation for the considerable discrepancy between model predictions and some data. Several previously unreported or unquantified degradation products were identified and measured. Potential additional reactions to account for these results in future kinetic models are proposed. [source] Analyzing the real advantages of bifunctional initiator over monofunctional initiator in free radical polymerizationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Paula F. de M. P. B. Machado Abstract Monofunctional initiators are extensively used in free radical polymerization. To enhance productivity, a higher temperature is usually used; however, this leads to lower molecular weights. Bifunctional initiators can increase the polymerization rate without decreasing the average molecular weight and this can be desirable. A bifunctional initiator is an important issue to be investigated, and it is of great interest to industries. The objective of this work is to study polymerization reactions with mono- and bi-functional initiators through comprehensive mathematical models. Polystyrene is considered as case study. This work collects and presents some experimental data available in literature for polymerization using two different types of bifunctional initiators. Model prediction showed good agreement with experimental data. It was observed that the initial initiator concentration has a huge impact on the efficiency of initiators with functionality bigger than one and high concentrations of bifunctional initiator make the system behave as if it were a system operating with monofunctional initiator. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Towards an integrated GIS-based coastal forecast workflowCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 14 2008Gabrielle Allen Abstract The SURA Coastal Ocean Observing and Prediction (SCOOP) program is using geographical information system (GIS) technologies to visualize and integrate distributed data sources from across the United States and Canada. Hydrodynamic models are run at different sites on a developing multi-institutional computational Grid. Some of these predictive simulations of storm surge and wind waves are triggered by tropical and subtropical cyclones in the Atlantic and the Gulf of Mexico. Model predictions and observational data need to be merged and visualized in a geospatial context for a variety of analyses and applications. A data archive at LSU aggregates the model outputs from multiple sources, and a data-driven workflow triggers remotely performed conversion of a subset of model predictions to georeferenced data sets, which are then delivered to a Web Map Service located at Texas A&M University. Other nodes in the distributed system aggregate the observational data. This paper describes the use of GIS within the SCOOP program for the 2005 hurricane season, along with details of the data-driven distributed dataflow and workflow, which results in geospatial products. We also focus on future plans related to the complimentary use of GIS and Grid technologies in the SCOOP program, through which we hope to provide a wider range of tools that can enhance the tools and capabilities of earth science research and hazard planning. Copyright © 2008 John Wiley & Sons, Ltd. [source] Range-wide patterns of greater sage-grouse persistenceDIVERSITY AND DISTRIBUTIONS, Issue 6 2008Cameron L. Aldridge ABSTRACT Aim, Greater sage-grouse (Centrocercus urophasianus), a shrub-steppe obligate species of western North America, currently occupies only half its historical range. Here we examine how broad-scale, long-term trends in landscape condition have affected range contraction. Location, Sagebrush biome of the western USA. Methods, Logistic regression was used to assess persistence and extirpation of greater sage-grouse range based on landscape conditions measured by human population (density and population change), vegetation (percentage of sagebrush habitat), roads (density of and distance to roads), agriculture (cropland, farmland and cattle density), climate (number of severe and extreme droughts) and range periphery. Model predictions were used to identify areas where future extirpations can be expected, while also explaining possible causes of past extirpations. Results, Greater sage-grouse persistence and extirpation were significantly related to sagebrush habitat, cultivated cropland, human population density in 1950, prevalence of severe droughts and historical range periphery. Extirpation of sage-grouse was most likely in areas having at least four persons per square kilometre in 1950, 25% cultivated cropland in 2002 or the presence of three or more severe droughts per decade. In contrast, persistence of sage-grouse was expected when at least 30 km from historical range edge and in habitats containing at least 25% sagebrush cover within 30 km. Extirpation was most often explained (35%) by the combined effects of peripherality (within 30 km of range edge) and lack of sagebrush cover (less than 25% within 30 km). Based on patterns of prior extirpation and model predictions, we predict that 29% of remaining range may be at risk. Main Conclusions, Spatial patterns in greater sage-grouse range contraction can be explained by widely available landscape variables that describe patterns of remaining sagebrush habitat and loss due to cultivation, climatic trends, human population growth and peripherality of populations. However, future range loss may relate less to historical mechanisms and more to recent changes in land use and habitat condition, including energy developments and invasions by non-native species such as cheatgrass (Bromus tectorum) and West Nile virus. In conjunction with local measures of population performance, landscape-scale predictions of future range loss may be useful for prioritizing management and protection. Our results suggest that initial conservation efforts should focus on maintaining large expanses of sagebrush habitat, enhancing quality of existing habitats, and increasing habitat connectivity. [source] Evaluation of a wind erosion model in a desert area of northern Asia by eddy covarianceEARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2009Gerardo Fratini Abstract For the first time, vertical fluxes of mineral dust measured by Eddy Covariance in two desert sites of Northern Asia have been used to test the performances of a wind erosion model in the field. Soil parameters required by the model were obtained through field and laboratory determinations. Model predictions and direct measurements have been compared. The main finding was that the direction of the horizontal wind relative to the orientation of nebkhas played a crucial role in determining the emission of particles in one of the investigated sites. Being unable to simulate such interaction, the model generally overestimated the actual emission. It provided, instead, reliable predictions (r2 = 0·87) when the wind direction was suitable in detaching loose erodible elements placed on nebkhas thanks to their normal orientation. Copyright © 2009 John Wiley & Sons, Ltd. [source] A model of equilibrium bed topography for meander bends with erodible banksEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2002Stephen E. Darby Abstract Channel curvature produces secondary currents and a transverse sloping channel bed, along which the depth increases towards the outer bank. As a result deep pools tend to form adjacent to the outer bank, promoting bank collapse. The interaction of sediment grains with the primary and secondary flow and the transverse sloping bed also causes meanders to move different grain sizes in different proportions and directions, resulting in a consistent sorting pattern. Several models have been developed to describe this process, but they all have the potential to over-predict pool depth because they cannot account for the influence of erodible banks. In reality, bank collapse might lead to the development of a wider, shallower cross-section and any resulting flow depth discrepancy can bias associated predictions of flow, sediment transport, and grain-size sorting. While bed topography, sediment transport and grain sorting in bends will partly be controlled by the sedimentary characteristics of the bank materials, the magnitude of this effect has not previously been explored. This paper reports the development of a model of flow, sediment transport, grain-size sorting, and bed topography for river bends with erodible banks. The model is tested via intercomparison of predicted and observed bed topography in one low-energy (5·3 W m,2 specific stream power) and one high-energy (43·4 W m,2) study reach, namely the River South Esk in Scotland and Goodwin Creek in Mississippi, respectively. Model predictions of bed topography are found to be satisfactory, at least close to the apices of bends. Finally, the model is used in sensitivity analyses that provide insight into the influence of bank erodibility on equilibrium meander morphology and associated patterns of grain-size sorting. The sensitivity of meander response to bank cohesion is found to increase as a function of the available stream power within the two study bends. Copyright © 2002 John Wiley & Sons, Ltd. [source] Responses of global plant diversity capacity to changes in carbon dioxide concentration and climateECOLOGY LETTERS, Issue 11 2008F. I. Woodward Abstract We model plant species diversity globally by country to show that future plant diversity capacity has a strong dependence on changing climate and carbon dioxide concentration. CO2 increase, through its impact on net primary production and warming is predicted to increase regional diversity capacity, while warming with constant CO2 leads to decreases in diversity capacity. Increased CO2 concentrations are unlikely to counter projected extinctions of endemic species, shown in earlier studies to be more strongly dependent on changing land use patterns than climate per se. Model predictions were tested against (1) contemporary observations of tree species diversity in different biomes, (2) an independent global map of contemporary species diversity and (3) time sequences of plant naturalisation for different locations. Good agreements between model, observations and naturalisation patterns support the suggestion that future diversity capacity increases are likely to be filled from a ,cosmopolitan weed pool' for which migration appears to be an insignificant barrier. [source] A Comparison of Conventional Local Approach and the Short Crack Approach to Fatigue Crack Initiation at a Notch,ADVANCED ENGINEERING MATERIALS, Issue 9 2009Narayanaswami Ranganathan Methods to estimate fatigue crack initiation life at a notch tip are compared. The methods used determine the strain amplitudes at the notch tip using Neuber's or Glinka's approximation. In conventional approaches, equivalent-damage levels are determined, using appropriate strain-life relationships coupled with damage-summation models. In the short-crack approach, a crack-like defect is assumed to exist at the notch tip. It is shown that the short-crack concept can be successfully applied to predict crack-initiation behavior at a notch. Model predictions are compared with carefully designed experiments. It is shown that model predictions are very close to experimentally measured lives under an aircraft-wing loading spectrum. [source] Evaluation of creep damage accumulation models: Considerations of stepped testing and highly stressed volumeFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 8 2007W. A. GRELL ABSTRACT Many components experience combined temperature and stress loading and are designed to withstand creep. In this study, experimental creep testing was performed under both static and stepped loading conditions with constant temperature for two specimen geometries (tensile and three-point bend). The objective of this study was to evaluate whether existing damage accumulation models accurately predict creep performance when considering step loading and stress gradients. Model predictions, based on static tensile creep data and using a highly stressed volume correction for the three-point bend specimens and the experimental average damage sum, agreed well with experimental data; differences were on average within 38% (static) and 2.2 h (stepped). Comparisons showed more accurate predictions using an exponential Larson,Miller parameter curve and the Pavlou damage accumulation model. Findings of the current study have applicability to component design, where complex geometries often contain stress gradients and it is desirable to predict creep performance from static tensile creep data. [source] A model for predicting the emergence of dragonflies in a changing climateFRESHWATER BIOLOGY, Issue 9 2008OTTO RICHTER Summary 1. Precise models for the phenology of different species are essential for predicting the potential effects of any temporal mismatch of life cycles with environmental parameters under different climate change scenarios. Here we investigated the effects of ambient water temperature on the onset and synchrony of emergence for a widespread European riverine dragonfly, Gomphus vulgatissimus. 2. Long-term field data on the annual emergence from two rivers in northern Germany, and additional data from a laboratory experiment with different temperature regimes, were used to develop a model that predicted the onset of emergence by using mainly the temperature sum (degree days) as a parameter. 3. Model predictions of the onset of emergence fitted the observations well and could be transferred between localities. This was particularly so when weighting early winter temperature data by using a day length and a temperature-response function, implying potential additional control mechanisms for the onset of emergence. 4. We simulated effects of different winter temperature regimes on the emergence curves in order to predict the effects of climate change. These indicated an acceleration of emergence by 6,7 days per 1 °C temperature increase, which is corroborated by the laboratory data and is in the upper range of data published for other dragonflies. [source] Validation of a prediction rule to maximize curative (R0) resection of early-stage pancreatic adenocarcinomaHPB, Issue 7 2009Philip Bao Abstract Background:, The surgeon's contribution to patients with localized pancreatic adenocarcinoma (PAC) is a margin negative (R0) resection. We hypothesized that a prediction rule based on pre-operative imaging would maximize the R0 resection rate while reducing non-therapeutic intervention. Methods:, The prediction rule was developed using computed tomography (CT) and endoscopic ultrasound (EUS) data from 65 patients with biopsy-proven PAC who underwent attempted resection. The rule classified patients as low or high risk for non-R0 outcome and was validated in 78 subsequent patients. Results:, Model variables were: any evidence of vascular involvement on CT; EUS stage and EUS size dichotomized at 2.6 cm. In the validation cohort, 77% underwent resection and 58% achieved R0 status. If only patients in the low-risk group underwent surgery, the prediction rule would have increased the resection rate to 92% and the R0 rate to 73%. The R0 rate was 40% higher in low-risk compared with high-risk patients (P < 0.001). High risk was associated with a 67% rate of non-curative surgery (unresectable disease and metastases). Conclusion:, The prediction rule identified patients most likely to benefit from resection for PAC using pre-operative CT and EUS findings. Model predictions would have increased the R0 rate and reduced non-therapeutic interventions. [source] Micromechanical analysis of failure propagation in frictional granular materialsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2009Antoinette Tordesillas Abstract The extent to which the evolution of instabilities and failure across multiple length scales can be reproduced with the aid of a bifurcation analysis is examined. We adopt an elastoplastic micropolar constitutive model, recently developed for dense cohesionless granular materials within the framework of thermomicromechanics. The internal variables and their evolution laws are conceived from a direct consideration of the dissipative mechanism of force chain buckling. The resulting constitutive law is cast entirely in terms of the particle scale properties. It thus presents a unique opportunity to test the potential of micromechanical continuum formulations to reproduce key stages in the deformation history: the development of material instabilities and failure following an initially homogeneous deformation. Progression of failure, initiating from frictional sliding and rolling at contacts, followed by the buckling of force chains, through to macroscopic strain softening and shear banding, is reproduced. Bifurcation point, marking the onset of shear banding, occurred shortly after the peak stress ratio. A wide range of material parameters was examined to show the effect of particle scale properties on the progression of failure. Model predictions on the thickness and angle of inclination of the shear band and the structural evolution inside the band, namely the latitudinal distribution of particle rotations and the angular distributions of contacts and the normal contact forces, are consistent with observations from numerical simulations and experiments. Copyright © 2009 John Wiley & Sons, Ltd. [source] A density-dependent elastoplastic hydro-mechanical model for unsaturated compacted soilsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 11 2007D. A. Sun Abstract This paper presents a three-dimensional elastoplastic constitutive model for predicting the hydraulic and mechanical behaviour of unsaturated soils. It is based on experimental results obtained from a series of controlled-suction triaxial tests on unsaturated compacted clay with different initial densities. Hydraulic hysteresis in the water-retention behaviour is modelled as an elastoplastic process, with the elastic part modelled by a series of scanning curves and the elastoplastic part modelled by the main drying and wetting curves. The effect of void ratio on the water-retention behaviour is studied using data obtained from controlled-suction wetting,drying cyclic tests on unsaturated compacted clay with different initial densities. The effect of the degree of saturation on the stress,strain-strength behaviour and the effect of void ratio on the water-retention behaviour are considered in the model, as is the effect of suction on the hydraulic and mechanical behaviour. The initial density dependency of the compacted soil behaviour is modelled by experimental relationships between the initial density and the corresponding yield stress and, thereby, between the initial density and the normal compression line. The model is generalized to three-dimensional stress states by assuming that the shapes of the failure and yield surfaces in the deviatoric stress plane are given by the Matsuoka,Nakai criterion. Model predictions of the stress,strain and water-retention behaviour are compared with those obtained from triaxial tests with different initial densities under isotropic compression, triaxial compression and triaxial extension, with or without variation in suction. The comparisons indicate that the model accurately predicts the hydraulic and mechanical behaviour of unsaturated compacted soils with different initial densities using the same material constant. Copyright © 2006 John Wiley & Sons, Ltd. [source] Experimental measurements and kinetic modeling of CH4/O2 and CH4/C2H6/O2 conversion at high pressure,INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 12 2008Christian Lund Rasmussen A detailed chemical kinetic model for homogeneous combustion of the light hydrocarbon fuels CH4 and C2H6 in the intermediate temperature range roughly 500,1100 K, and pressures up to 100 bar has been developed and validated experimentally. Rate constants have been obtained from critical evaluation of data for individual elementary reactions reported in the literature with particular emphasis on the conditions relevant to the present work. The experiments, involving CH4/O2 and CH4/C2H6/O2 mixtures diluted in N2, have been carried out in a high-pressure flow reactor at 600,900 K, 50,100 bar, and reaction stoichiometries ranging from very lean to fuel-rich conditions. Model predictions are generally satisfactory. The governing reaction mechanisms are outlined based on calculations with the kinetic model. Finally, the mechanism was extended with a number of reactions important at high temperature and tested against data from shock tubes, laminar flames, and flow reactors. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 778,807, 2008 [source] Variability of southeastern Queensland rainfall and climate indicesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2004Bradley F. Murphy Abstract The variability of climate indices and rainfall in southeastern (SE) Queensland (Qld) is studied. Using high-resolution gridded rainfall data for all of Australia and global sea-surface temperatures (SSTs), the relationship between Australia-wide rainfall (and in SE Qld in particular) and SST indices and the southern oscillation index (SOI) have been investigated. It is found that SE Qld is more subject to the breakdown of correlations between the SOI and rainfall than any other part of Australia. Model predictions suggest that this is probable in the future. Considering only time scales longer than interannual, it was found that SSTs in the central tropical Pacific Ocean (TPO; represented by the Niño-4 index) correlated best with SE Qld rainfall. Eastern TPO (Niño-3) SSTs and the SOI produced successively weaker correlations. The time series of the second modes of variability of SSTs over the Pacific and Indian Oceans were shown to have limited impact on SE Qld rainfall variability. The data were split into periods before and after 1946, when Australian mean rainfall changed. Whereas the SOI correlations with rainfall in SE Australia were similar in both periods, in SE Qld the correlations were very weak in the earlier period (0.06) but very strong in the later period (0.72). The Niño-4 index correlated better than the Niño-3 index in both periods, but both indexes showed smaller changes from the earlier to the later periods than the SOI. Copyright © 2004 Royal Meteorological Society. [source] Modelling climate change in West African Sahel rainfall (1931,90) as an artifact of changing station locationsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2004Adrian Chappell Abstract Since the major droughts in the West African Sahel during the 1970s, it has been widely asserted that mean annual summer rainfall has declined since the late 1960s. Explanation of this persistent regional drying trend was important for famine early-warning and global climate models. However, the network of rainfall stations changed considerably during that recent period of desiccation. Furthermore, it was difficult to reconcile the calculation of a simple mean value for a region known to have a complex spatial and temporal rainfall pattern. A simple model separated the Sahel into ,wet' and ,dry' regions. This model was inverted against mean annual summer rainfall for the Sahel between 1931 and 1990. Model predictions were found to be insensitive to initial starting conditions. The optimized parameters explained 87% of the variation in observed mean annual summer rainfall. The model predicted the mean annual rainfall in the wet ,coastal' and dry ,continental' regions of the Sahel to be 973 mm and 142 mm respectively. Consequently, the predicted long-term mean annual summer rainfall was 558 mm, 15% greater than that of the observed long-term mean (417 mm). The mean annual summer rainfall for the region was corrected by removing the influence of changing station locations over the study period. No persistent decline was found in mean annual summer rainfall, which suggested that the perceived drying trend was an artifact of the crude statistical aggregation of the data and historical changes in the climate station networks. The absence of a decline in rainfall questioned the validity of the hypotheses and speculations for the causes of the drying trend in the region and its effects on global climate change. It also increased the likelihood that changes over time in other regional and global climate station networks have influenced the performance and interpretation of global climate models. Copyright © 2004 Royal Meteorological Society [source] Regional climate modulates the canopy mosaic of favourable and risky microclimates for insectsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2007SYLVAIN PINCEBOURDE Summary 1,One major gap in our ability to predict the impacts of climate change is a quantitative analysis of temperatures experienced by organisms under natural conditions. We developed a framework to describe and quantify the impacts of local climate on the mosaic of microclimates and physiological states of insects within tree canopies. This approach was applied to a leaf mining moth feeding on apple leaf tissues. 2,Canopy geometry was explicitly considered by mapping the 3D position and orientation of more than 26 000 leaves in an apple tree. Four published models for canopy radiation interception, energy budget of leaves and mines, body temperature and developmental rate of the leaf miner were integrated. Model predictions were compared with actual microclimate temperatures. The biophysical model accurately predicted temperature within mines at different positions within the tree crown. 3,Field temperature measurements indicated that leaf and mine temperature patterns differ according to the regional climatic conditions (cloudy or sunny) and depending on their location within the canopy. Mines in the sun can be warmer than those in the shade by several degrees and the heterogeneity of mine temperature was incremented by 120%, compared with that of leaf temperature. 4.,The integrated model was used to explore the impact of both warm and exceptionally hot climatic conditions recorded during a heat wave on the microclimate heterogeneity at canopy scale. During warm conditions, larvae in sunlight-exposed mines experienced nearly optimal growth conditions compared with those within shaded mines. The developmental rate was increased by almost 50% in the sunny microhabitat compared with the shaded location. Larvae, however, experienced optimal temperatures for their development inside shaded mines during extreme climatic conditions, whereas larvae in exposed mines were overheating, leading to major risks of mortality. 5,Tree canopies act as both magnifiers and reducers of the climatic regime experienced in open air outside canopies. Favourable and risky spots within the canopy do change as a function of the climatic conditions at the regional scale. The shifting nature of the mosaic of suitable and risky habitats may explain the observed uniform distribution of leaf miners within tree canopies. [source] A model of human hunting impacts in multi-prey communitiesJOURNAL OF APPLIED ECOLOGY, Issue 5 2003J. Marcus Rowcliffe Summary 1The hunting of wild animals for consumption by people currently threatens many species with extinction. In the tropics, where the threat is most acute, hunting frequently targets many prey species simultaneously, yet our understanding of the dynamics of hunting in such multi-prey systems is limited. This study addressed this issue by modelling the effects of human hunters on prey population dynamics in a multi-species prey community. Both pursuit hunting (in which offtake depends partly on hunters' prey preferences) and trap hunting (in which the offtake is determined solely by random processes) were considered as submodels. 2The pursuit hunting submodel was validated against studies of subsistence hunting in tropical forests, while the trap hunting submodel was validated against data from five studies of offtake rates by snare hunters in subSaharan Africa. In all cases, observed prey removal rates were predicted well by the model. 3Simulations demonstrated the emergence of distinctive prey profiles at different intensities of hunting, related to sequences of overexploitation dependent on species' vulnerabilities to exploitation. 4Synthesis and applications. A model is developed to explore the impacts of harvesting on multi-species prey communities. Model predictions can be used to aid the interpretation of incomplete monitoring data, such as snapshots of the species taken by hunters. This will improve our ability to assess the sustainability of multi-species hunting systems using the limited information typically available in these cases. [source] Development of a mechanistic model for biological nutrient removal activated sludge systems and application to a full-scale WWTPAICHE JOURNAL, Issue 6 2010Bing-Jie Ni Abstract In wastewater treatment plants (WWTPs) the production of nitrite as an intermediate in the biological nutrient removal (BNR) process has been widely observed, but not been taken into account by most of the conventional activated sludge models yet. This work aims to develop a mechanistic mathematical model to evaluate the BNR process after resolving such a problem. A mathematical model is developed based on the Activated Sludge Model No.3 (ASM3) and the EAWAG Bio-P model with an incorporation of the two-step nitrification,denitrification, the anoxic P uptake, and the associated two-step denitrification by phosphorus accumulating organisms. The database used for simulations originates from a full-scale BNR municipal wastewater treatment plant. The influent wastewater composition is characterized using batch tests. Model predictions are compared with the measured concentrations of chemical oxygen demand (COD), NH -N, NO -N, NO -N, PO -P, and mixed liquid volatile suspended solids. Simulation results indicate that the calibrated model is capable of predicting the microbial growth, COD removal, nitrification and denitrification, as well as aerobic and anoxic P removal. Thus, this model can be used to evaluate and simulate full-scale BNR activated sludge WWTPs. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Modeling and simulation of the sequencing batch reactor at a full-scale municipal wastewater treatment plantAICHE JOURNAL, Issue 8 2009Bing-Jie Ni Abstract In this work, we attempted to modify the Activated Sludge Model No.3 and to simulate the performance of a full-scale sequencing batch reactor (SBR) plant for municipal wastewater treatment. The long-term dynamic data from the continuous operation of this SBR plant were simulated. The influent wastewater composition was characterized using batch measurements. After incorporating all the relevant processes, the sensitivity of the stoichiometric and kinetic coefficients for the model was thoroughly analyzed prior to the model calibration. The modified model was calibrated and validated with the data from both batch- and full-scale experiments. Model predictions were compared with routine data in terms of chemical oxygen demand, NH4+ -N and mixed liquid volatile suspended solids in the SBR, combined with batch experimental data under different conditions. The model predictions match the experimental results well, demonstrating that the model is appropriate to simulate the performance of a full-scale wastewater treatment plant even operated under perturbation conditions. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Physiologically based predictions of the impact of inhibition of intestinal and hepatic metabolism on human pharmacokinetics of CYP3A substratesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2010Frederique Fenneteau Abstract The first objective of the present study was to predict the pharmacokinetics of selected CYP3A substrates administered at a single oral dose to human. The second objective was to predict pharmacokinetics of the selected drugs in presence of inhibitors of the intestinal and/or hepatic CYP3A activity. We developed a whole-body physiologically based pharmacokinetics (WB-PBPK) model accounting for presystemic elimination of midazolam (MDZ), alprazolam (APZ), triazolam (TRZ), and simvastatin (SMV). The model also accounted for concomitant administration of the above-mentioned drugs with CYP3A inhibitors, namely ketoconazole (KTZ), itraconazole (ITZ), diltiazem (DTZ), saquinavir (SQV), and a furanocoumarin contained in grape-fruit juice (GFJ), namely 6,,7,-dihydroxybergamottin (DHB). Model predictions were compared to published clinical data. An uncertainty analysis was performed to account for the variability and uncertainty of model parameters when predicting the model outcomes. We also briefly report on the results of our efforts to develop a global sensitivity analysis and its application to the current WB-PBPK model. Considering the current criterion for a successful prediction, judged satisfied once the clinical data are captured within the 5th and 95th percentiles of the predicted concentration,time profiles, a successful prediction has been obtained for a single oral administration of MDZ and SMV. For APZ and TRZ, however, a slight deviation toward the 95th percentile was observed especially for Cmax but, overall, the in vivo profiles were well captured by the PBPK model. Moreover, the impact of DHB-mediated inhibition on the extent of intestinal pre-systemic elimination of MDZ and SMV has been accurately predicted by the proposed PBPK model. For concomitant administrations of MDZ and ITZ, APZ and KTZ, as well as SMV and DTZ, the in vivo concentration,time profiles were accurately captured by the model. A slight deviation was observed for SMV when coadministered with ITZ, whereas more important deviations have been obtained between the model predictions and in vivo concentration,time profiles of MDZ coadministered with SQV. The same observation was made for TRZ when administered with KTZ. Most of the pharmacokinetic parameters predicted by the PBPK model were successfully predicted within a two-fold error range either in the absence or presence of metabolism-based inhibition. Overall, the present study demonstrated the ability of the PBPK model to predict DDI of CYP3A substrates with promising accuracy. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:486,514, 2010 [source] Mathematical Modeling of Atom-Transfer Radical CopolymerizationMACROMOLECULAR REACTION ENGINEERING, Issue 4 2007Mamdouh Al-Harthi Abstract A comprehensive mathematical model for atom transfer radical copolymerization in a batch reactor is presented using the concept of pseudo-kinetic rate constants and the method of moments. The model describes molecular weight, monomer conversion, polydispersity index, and copolymer composition as a function of polymerization time. Model predictions were compared with experimental data for styrene and butyl acrylate copolymerization and excellent agreement was obtained. We have also tested the model with styrene-acrylonitrile copolymerization data obtained in our laboratory. Finally, we used the model to study the effect of comonomer reactivity ratio, feed composition, activation and deactivation rate constants on the copolymer composition. [source] Modelling the role of social behavior in the persistence of the alpine marmot Marmota marmotaOIKOS, Issue 1 2003Volker Grimm A general rule of thumb for biological conservation obtained from simple models of hypothetical species is that for populations with strong environmental noise moderate increases in habitat size or quality do not substantially reduce extinction risk. However, whether this rule also holds for real species with complex behavior, such as social species with breeding units and reproductive suppression, is uncertain. Here we present a population viability analysis of the alpine marmot Marmota marmota, which displays marked social behavior, i.e. it lives in social groups of up to twenty individuals. Our analysis is based on a long-term field study carried out in the Bavarian Alps since 1982. During the first fifteen years of this study, 687 marmots were individually marked and the movements and fate of 98 dispersing marmots were recorded with radio-telemetry. Thus, in contrast to most other viability analyses of spatially structured populations, good data about dispersal exist. A model was constructed which is individual-based, spatially explicit at the scale of clusters of neighbouring territories, and spatially implicit at larger scales. The decisive aspect of marmot life history, winter mortality, is described by logistic regression where mortality is increased by age and the severity of winter, and decreased by the number of subdominant individuals present in a group. Model predictions of group size distribution are in good agreement with the results of the field study. The model shows that the effect of sociality on winter mortality is very effective in buffering environmental harshness and fluctuations. This underpins theoretical results stating that the appropriate measure of the strength of environmental noise is the ratio between the variance of population growth rate and the intrinsic rate of increase. The lessons from our study for biological conservation are that simple, unstructured models may not be sufficient to assess the viability of species with complex behavioral traits, and that even moderate increases in habitat capacity may substantially reduce extinction risk even if environmental fluctuations seem high. [source] A nonlinear theoretical model for prediction of mechanical behavior of particulate composites and experimental verification of the model predictionsPOLYMER COMPOSITES, Issue 7 2010A. Ramazani S.A. A model for prediction the stress-strain behavior of particulate composite over wide ranges of filler concentration and composite deformation has been developed through combination of Anderson's and Yilmizer's model. The constitutive equations are extracted from first law of thermodynamic and nonlinear dilatational effects which are produced by filler-matrix debonding process. In addition to nonlinear behavior that has been resulted by filler-matrix debonding and was presented by Yilmizer, the formation and growing of void or cavitations has been also introduced in this model, whereas Anderson's model, most important reason for deviation of linear behavior is filler-matrix debonding and has been indicated by change of modulus. Model predictions for effects of the filler concentration and its particle size and particle size distribution for some matrix-filler systems are compared with related experimental data from literature and some investigated systems in this work. An excellent agreement even better than prediction of Anderson's model between experimental data and model predictions can be observed in most cases especially for some concentrated systems. POLYM. COMPOS., 31:1150,1155, 2010. © 2009 Society of Plastics Engineers [source] Lateral compaction effects in braided structuresPOLYMER COMPOSITES, Issue 2 2003Robert A. Dasilva This paper addresses the phenomenology of strand interaction in biaxial non-embedded braided textile structures under uniaxial tension. The specific interest in the development of new braided textile structures is a result of the shortcomings of current rope, belt, and cable performance under large strain controlled conditions. However, this work also holds particular significance in the area of textile composite preforms. In composites forming, the lateral strand compaction mechanism, which drives braid behavior under tension, may be applied to woven fabrics for predicting wrinkling during forming processes. Additionally, manufacturing models produced in this study may be used to predict shape and size limitations of braided composite preforms. In this paper, a generalized model is developed for these structures with the intent of characterizing and predicting mechanical behavior. The methodology consists of a modular framework, which includes the prediction of manufacturing parameters. Lateral strand compaction tests were performed to generate constitutive material curves for use in analytical geometric models. Model predictions correlate well with data generated from braid uniaxial tension tests. Results suggest that lateral strand strain drives braid tensile behavior. [source] Modelling sources and sinks of CO2, H2O and heat within a Siberian pine forest using three inverse methodsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 590 2003M. Siqueira Abstract Source/sink distributions of heat, CO2 and water vapour in a Siberian Scots pine forest were estimated from measured concentration and temperature profiles using three inverse analysis methods. These methods include: a Eulerian second-order closure model (EUL); a localized near-field Lagrangian dispersion model (LNF); and a hybrid model (HEL) which uses the Eulerian second-order turbulence model to calculate the flow statistics combined with the regression analysis used with the Lagrangian model. Model predictions were compared to heat flux profiles measured at five levels in the canopy, and to CO2 and water-vapour fluxes measured close to the ground and above the forest. Predictions of sensible-heat flux profiles by the LNF and HEL schemes were systematically better than results from the EUL analysis. This improvement was attributed to the redundancy in the measured profile (scalar concentration and temperature) data for LNF and HEL and to the imposed smoothness condition used in the regression analyses, whereas the EUL approach calculates a source for each level without any redundancy. The LNF and HEL schemes were also better than EUL in predicting source distributions for CO2 and water vapour, although errors were larger than for sensible heat. The main novelty in our study is the use of EUL to decompose the vertical variability in scalar (or heat) sources into variability produced by the inhomogeneity in flow statistics and variability inferred from the measured mean scalar concentration (or temperature) profile. Hence, it is possible with this analysis to assess how much ,new information' about the source variability is attributed to vertical variation in the measured mean scalar concentration (or temperature) profiles. The analysis shows that measured water vapour concentration profiles provide little information on the inferred source distribution, whereas the CO2 profiles contain more information. Monte Carlo simulations show that computed sources from all three inverse methods have similar sensitivities to errors in measured temperatures. Errors are reduced when the reference temperature above the canopy is held fixed, implying that errors in this temperature propagate throughout the entire domain. When information content and error estimations are combined, a valuable tool to assess the quality of source prediction by inverse methods can be generated. Copyright © 2003 Royal Meteorological Society [source] A mechanistic model of the enzymatic hydrolysis of celluloseBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010Seth E. Levine Abstract A detailed mechanistic model of enzymatic cellulose hydrolysis has been developed. The behavior of individual cellulase enzymes and parameters describing the cellulose surface properties are included. Results obtained for individual enzymes (T. reesei endoglucanase 2 and cellobiohydrolase I) and systems with both enzymes present are compared with experimental literature data. The model was sensitive to cellulase-accessible surface area; the EG2,CBHI synergy observed experimentally was only predicted at a sufficiently high cellulose surface area. Enzyme crowding, which is more apparent at low surface areas, resulted in differences between predicted and experimental rates of hydrolysis. Model predictions also indicated that the observed decrease in hydrolysis rates following the initial rate of rapid hydrolysis is not solely caused by product inhibition and/or thermal deactivation. Surface heterogeneities, which are not accounted for in this work, may play a role in decreasing the hydrolysis rate. The importance of separating the enzyme adsorption and complexation steps is illustrated by the model's sensitivity to the rate of formation of enzyme,substrate complexes on the cellulose surface. Biotechnol. Bioeng. 2010;107: 37,51. © 2010 Wiley Periodicals, Inc. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||