Academic literature on the topic 'Diffuse inputs'

The River Liffey is the main source of diffuse nutrients to Dublin Bay and accounts for some 85% of all riverine inputs. The total load from the various rivers has been calculated at some 6601 kg N d1 and 748 kg P d1, of which around 82% and 52% are in the form of DIN and phosphate respectively. Sewage discharge adds almost the same again to the load, with minor contributions from the sediments (which may simply be remineralising the particulates) and from nitrogen fixation. However, these inputs are very much less than those exchanged twice-daily by tidal action. These contributions are due to change very shortly with the advent of the new STW in Dublin, but the major change may be more in the speciation of the nutrients, and in particular the dissolved/particulate balance.

Mogan Lake is an important recreational area for Metropolitan Ankara-Turkey. It is a shallow eutrophic lake with a dense growth of macrophytes. The main contributors of nutrients and other pollutants to the lake are the creeks carrying the runoff water from the watershed and upland farming land, in addition to the domestic and industrial wastewater discharges from a nearby town and industries. Hydrodynamic and water quality modeling techniques were used to determine the optimum management schemes for the lake restoration and diffuse pollution control. Management scenarios were devised and tested to control allochthonous and autochthonous nutrient inputs to the lake. Phosphorus and nitrogen load reductions were the main test elements for the control of allochthonous nutrient inputs. The scenario analysis revealed that reduction of phosphorus and nitrogen loads from diffused sources will have a marginal effect on controlling eutrophication if macrophyte growth is left uncontrolled. Scenarios employing macrophyte harvesting and sediment dredging have been evaluated for autochthonous nutrient input control. Sediment dredging alone has been shown to yield the most favorable conditions for water quality improvement in Mogan Lake. Further, control of diffuse pollution was an essential final step to achieve an acceptable long-term sustainable water quality improvement in the lake.

A model (MEPhos) for the calculation of the total phosphorus output from diffuse sources by drainage, wash-off, groundwater outflow, soil erosion and rainwater sewers as well as from point sources is presented. The model is based on a pathway- and area-differentiated emissions approach and calculates mean long-term P-inputs to surface waters. Phosphotopes are used for spatial discretization and modelling of diffuse P-inputs. Based on the modelling results “hot spots” for high P-loads can be localized and a management option for the input reduction to surface waters can be proposed which are adapted to site properties. The applicability of the model is demonstrated for two macroscale river basins in Germany (∼13,000 km2 each) with contrasting natural conditions and land use patterns.

The thalamic reticular nucleus is a layer of GABAergic neurons that occupy a strategic position between the thalamus and cortex. Here we used laser scanning photostimulation to compare in young mice (9–12 days old) the organization of the reticular inputs to first- and higher-order somatosensory relays, namely, the ventral posterior lateral nucleus and posterior nucleus, respectively. The reticulothalamic input footprints to the ventral posterior lateral nucleus neurons consisted of small, single, topographically organized elliptical regions in a tier away from the reticulothalamic border. In contrast, those to the posterior nucleus were complicated and varied considerably among neurons: although almost all contained a single elliptical region near the reticulothalamic border, in most cases, they consisted of additional discontinuous regions or relatively diffuse regions throughout the thickness of the thalamic reticular nucleus. Our results suggest two sources of reticular inputs to the posterior nucleus neurons: one that is relatively topographic from regions near the reticulothalamic border and one that is relatively diffuse and convergent from most or all of the thickness of the thalamic reticular nucleus. We propose that the more topographic reticular input is the basis of local inhibition seen in posterior nucleus neurons and that the more diffuse and convergent input may represent circuitry through which the ventral posterior lateral and posterior nuclei interact.

• Acute (normal) pain transmission is part of a survival response to prevent tissue damage and attend to and protect damaged tissue. • A cycle of afferent transmission, response to stimuli, followed by temporary hypersensitivity, then attenuation and resolution occurs. • Primary afferent, spinal cord ascending and descending pathways are fixed; however the response elicited is highly dynamic and not a linear relationship with input intensity. • Somatic inputs are topographically accurate, in contrast to diffuse visceral inputs. • Primary afferents code differentially for stimuli (heat, acid, pressure etc) and intensity. • The dorsal horn allows extensive modulation of initial inputs, either excitation or inhibition. • Higher CNS areas allow extensive modulation of inputs, account for the conscious recognition of pain: the intensity, location, emotional and memory aspects. • Descending pathways arising from midbrain regions can be inhibitory or excitatory.

A GIS-based model estimates the losses from diffuse sources in surface waters in Germany for 42 active ingredients applied to 11 field crops, vineyards and orchards. For the following pathways of entry: tile drainage, runoff and spray drift, the calculated mean pesticide input amounts to 1490 kg/year, 9060 kg/year and 3350 kg/year, respectively, in 1994. The model results are highly sensitive to the model parameters, primarily the chemical properties of the active ingredients. The modeled water inputs were compared with measured pesticide loads in smaller catchments and large river basins to validate model results. Both datasets agree as to the order of magnitude, nevertheless due to the scale of the study the results should be addressed mainly to comparative interpretations with the focus on the proportions between different active ingredients, soil regions, climates and application periods.

The uncertainty of water quality predictions caused by uncertainty in the inputs related to emissions of diffuse pollution is analysed. An uncertainty analysis of the effects of diffuse pollution is essential to compare the cost and benefits of measures to lower those emissions. We focus on diffuse nitrate pollution due to fertiliser use. Using an efficient Monte Carlo method and Latin Hypercube sampling, the contribution to the overall uncertainty by each of the inputs is calculated. The modelling environment is ESWAT, an extension of SWAT, which allows for integral modelling of the water quantity and quality processes in river basins. The diffuse pollution sources are assessed by considering crop and soil processes. The crop simulations include growth, uptake of water and nutrients and several land management practices. The in-stream water quality model is based on QUAL2E. The spatial variability of the terrain strongly affects the non-point source pollution processes. The methodology is applied to the Dender basin in Belgium. Eight inputs have significant influence on the time that the nitrate content in the river is higher than 3 mg/l. The uncertainty analysis indicated wide uncertainty bounds (95% percentile bounds differ up to ±50% from the average NO3 predictions).

In a recent estimation of the quantitative importance of diffuse and point sources on the nitrogen and phosphorus pollution of surface waters in both parts of Germany just before the reunification, the share of the diffuse sources on the total input was found very similar in the case of N (56 and 57%), but different in the case of P (42% in the old FRG and 33% in the former GDR). The diffuse N and P inputs are dominated by the joint pathways ground water/drain water and soil erosion/surface run off, respectively. The reduction of the diffuse pollution potential until 1995 (compared to 1987/89) is estimated with about 18% for N and 30% for P. This is far below the governmental target of a 50% reduction in the period 1985 to 1995. The reasons, why the up-to-now success of the different countermeasures against diffuse water pollution with N and P from agriculture is still unsatisfactory are discussed. Demands for an accelerated implementation of efficient countermeasures have to be addressed by both farmers and politicians.

The aim of this study was to apply a variety of investigative methods to identify the causes of elevated concentrations of nitrate reported in an unconfined aquifer around the township of Coonawarra in the South East region of South Australia. For nearly 30 years elevated nitrate concentrations have been of concern to Government Departments, however the source of these elevated nitrate concentrations remained unknown. Examination of an extensive historical water quality dataset for the study area identified that while nitrate concentrations were elevated during the late 1970s – early 1980s, they have declined since this time. The study demonstrates a variety of inherent biases that can exist within nitrate groundwater datasets, and presents methods that can be used for determining temporal trends in concentration that minimise the impacts of these characteristics. The quantification and spatial variability of diffuse recharge was investigated using groundwater tritium concentrations measured in the aquifer during the late 1970s. The modelling produced estimated recharge rates that were generally below those now adopted for the study area, and the methodology may not be appropriate in areas where high irrigation rates are occurring. The assessment of the variability of recharge illustrates that the high recharge areas corresponded to the previously identified areas of higher nitrate concentrations in groundwater. This correlation was further investigated statistically, and used a dual isotopic technique that applied the natural variability of nitrogen and oxygen isotopes (of nitrate) to source determination. The statistical approach was only able to explain 39% of the variability observed in groundwater nitrate concentrations using field observations. This approach indicated that there was a significant spatial relationship between bores located in close proximity to septic tanks and elevated nitrate concentrations in groundwater. The applications of the dual nitrate isotopic method further demonstrated that nitrate in the groundwater is from multiple sources, with septic tanks being a probable source of nitrate. This isotopic method is shown to be effective in source determination, with the results comparing well to literature and field observations. Modelling of diffuse inputs from the main landuse types supports the conclusion that the elevated nitrate levels are most likely due to localised sources. It is concluded that while high nitrate concentrations have existed within the Coonawarra area, the data interpretation methods previously used to report the ‘plume’ of nitrate contamination have over-estimated the extent of nitrate in groundwater. The elevated nitrate concentrations in the groundwater are primarily the result of anthropogenic sources (e.g. septic tanks) and natural sources (e.g. the mineralisation of soil organic nitrogen).

Modelle werden eingesetzt, um Menge und Herkunft der Stoffeinträge auf Flussgebietsebene zu analysieren. Aus den Ergebnissen der Modellierung lassen sich Handlungsempfehlungen zur Verbesserung der Gewässergüte ableiten. Für die Interpretation der Modellergebnisse sind Kenntnisse über die Genauigkeit und Aussagekraft der Ergebnisse notwendig. Das Modell MONERIS als konzeptionelles Modell für die Anwendung auf Flussgebietsebene wurde innerhalb der vorliegenden Arbeit in 5 europäischen Flusseinzugsgebieten angewandt. Sowohl mit verschiedenen Ansätzen aufbereitete Abflusswerte als auch unterschiedlich hoch aufgelöste Eingangsdaten führten bei der Modellierung zu Änderungen der berechneten Einträge und Frachten. Gezeigt wird, dass mit MONERIS sowohl mittlere Eintrags- und Frachtwerte für eine Periode von mehreren Jahren, als auch Werte für Einzeljahre berechnet werden können. Der Vergleich mit aus Konzentrations- und Abflussmessungen im Gewässer abgeleiteten Frachten wies Abweichungen von <30% auf. Bei der Modellierung von Einzeljahren konnten insbesondere die Jahre mit mittleren Niederschlagsbedingungen gut abgebildet werden. In Jahren mit hohen oder geringen Niederschlägen oder einer außergewöhnlichen Niederschlagsverteilung traten dagegen, bedingt durch die Kalibrierung der meisten Modellkoeffizienten für mittlere Abflussbedingungen von Perioden, Unter- oder Überschätzungen der gemessenen Frachten auf. Monatliche Einträge und Frachten wurden ebenfalls modelliert. Der Vergleich mit Messwerten zeigte hohe Abweichungen, sodass MONERIS für eine monatliche Berechnung noch weiterentwickelt werden muss. Dies betrifft vor allem die Genauigkeit der als Eingangsdaten verwendeten Abflüsse und der Abflusskomponenten sowie den in den Modellversionen vor 2008 verwendeten Retentionsansatz. Auch die räumliche Modellauflösung wurde untersucht und festgestellt, dass eine Modellierung mit MONERIS bis zu einer Auflösung von 1km² problemlos möglich ist. Die Schnittpunkte von Stoffeintragsmodellen mit Modellen aus der Siedlungswasserwirtschaft wurden durch einen Vergleich von MONERIS mit dem Modell STORM in einem stark urban geprägten Einzugsgebiet ermittelt. Obwohl die Unterschiede in den Modellansätzen deutlich wurden, konnte gezeigt werden, dass eine Ergänzung der beiden Modelltypen wünschenswert wäre. Abschließend wird ein neuer Ansatz für die Frachtberechnung aus Abfluss- und Konzentrationsmessungen vorgestellt, durch den die Genauigkeit der berechneten Jahresfrachten bei geringer Anzahl von Messwerten gegenüber etablierten Ansätzen erhöht werden kann. Da die aus Messwerten berechneten Frachten für die Modellkalibrierung und Validierung benötigt werden, kann so auch die Stoffeintragsmodellierung positiv beeinflusst werden
Different models were used to analyse and calculate the amount and origin of the nutrient inputs into riverbasins. Recommended follow-up action can be derived from the model results to improve the river water quality. The interpretation of the modelling results requires the knowledge of the accurateness and the significance of the results. For the investigations, the MONERIS model as a conceptual model was applied in five European river catchments. Different approaches for data preparation as well as a different input data were resulting in a large variation of the calculated nutrient inputs and loads. It was shown, that the MONERIS model is applicable to calculate inputs and loads for periods of several years as well as for one year. In comparison with measured loads mean deviations less than 30% were found. Looking at a yearly timestep, the nutrient inputs and loads in years with mean precipitation conditions were well reproduced. Years with high or low precipitation tends to result in overor underestimation of the nutrient inputs and loads, caused by the calibration of the model coefficients for mean runoff conditions. Monthly inputs and loads were calculated with MONERIS for the first time. The comparison with measured loads shows high deviations. Model improvements have to bee made regarding runoff input values (and runoff components) and retention approach (in the model version before 2008). Furthermore the spatial model resolution was investigated. It could be shown, that the MONERIS model is applicable until a resolution of 1sq.km. In a further application, MONERIS was compared with the urban stormwater management model STORM. Even though there were differences in model approaches, it could be shown a relation between the models for a comprehensive consideration of the calculation of nutrient contamination. Subsequent, a new runoff reduced approach for load calculation based on measurements of runoff and concentrations is presented. This approach allows the calculation of yearly loads with higher precision compared with well-established approaches, if only a low number of concentration measurement is available. The loads calculated from runoff and concentration measurements were important for calibration and validation of nutrient input models and can help to improve there results

Modelle werden eingesetzt, um Menge und Herkunft der Stoffeinträge auf Flussgebietsebene zu analysieren. Aus den Ergebnissen der Modellierung lassen sich Handlungsempfehlungen zur Verbesserung der Gewässergüte ableiten. Für die Interpretation der Modellergebnisse sind Kenntnisse über die Genauigkeit und Aussagekraft der Ergebnisse notwendig. Das Modell MONERIS als konzeptionelles Modell für die Anwendung auf Flussgebietsebene wurde innerhalb der vorliegenden Arbeit in 5 europäischen Flusseinzugsgebieten angewandt. Sowohl mit verschiedenen Ansätzen aufbereitete Abflusswerte als auch unterschiedlich hoch aufgelöste Eingangsdaten führten bei der Modellierung zu Änderungen der berechneten Einträge und Frachten. Gezeigt wird, dass mit MONERIS sowohl mittlere Eintrags- und Frachtwerte für eine Periode von mehreren Jahren, als auch Werte für Einzeljahre berechnet werden können. Der Vergleich mit aus Konzentrations- und Abflussmessungen im Gewässer abgeleiteten Frachten wies Abweichungen von <30% auf. Bei der Modellierung von Einzeljahren konnten insbesondere die Jahre mit mittleren Niederschlagsbedingungen gut abgebildet werden. In Jahren mit hohen oder geringen Niederschlägen oder einer außergewöhnlichen Niederschlagsverteilung traten dagegen, bedingt durch die Kalibrierung der meisten Modellkoeffizienten für mittlere Abflussbedingungen von Perioden, Unter- oder Überschätzungen der gemessenen Frachten auf. Monatliche Einträge und Frachten wurden ebenfalls modelliert. Der Vergleich mit Messwerten zeigte hohe Abweichungen, sodass MONERIS für eine monatliche Berechnung noch weiterentwickelt werden muss. Dies betrifft vor allem die Genauigkeit der als Eingangsdaten verwendeten Abflüsse und der Abflusskomponenten sowie den in den Modellversionen vor 2008 verwendeten Retentionsansatz. Auch die räumliche Modellauflösung wurde untersucht und festgestellt, dass eine Modellierung mit MONERIS bis zu einer Auflösung von 1km² problemlos möglich ist. Die Schnittpunkte von Stoffeintragsmodellen mit Modellen aus der Siedlungswasserwirtschaft wurden durch einen Vergleich von MONERIS mit dem Modell STORM in einem stark urban geprägten Einzugsgebiet ermittelt. Obwohl die Unterschiede in den Modellansätzen deutlich wurden, konnte gezeigt werden, dass eine Ergänzung der beiden Modelltypen wünschenswert wäre. Abschließend wird ein neuer Ansatz für die Frachtberechnung aus Abfluss- und Konzentrationsmessungen vorgestellt, durch den die Genauigkeit der berechneten Jahresfrachten bei geringer Anzahl von Messwerten gegenüber etablierten Ansätzen erhöht werden kann. Da die aus Messwerten berechneten Frachten für die Modellkalibrierung und Validierung benötigt werden, kann so auch die Stoffeintragsmodellierung positiv beeinflusst werden.
Different models were used to analyse and calculate the amount and origin of the nutrient inputs into riverbasins. Recommended follow-up action can be derived from the model results to improve the river water quality. The interpretation of the modelling results requires the knowledge of the accurateness and the significance of the results. For the investigations, the MONERIS model as a conceptual model was applied in five European river catchments. Different approaches for data preparation as well as a different input data were resulting in a large variation of the calculated nutrient inputs and loads. It was shown, that the MONERIS model is applicable to calculate inputs and loads for periods of several years as well as for one year. In comparison with measured loads mean deviations less than 30% were found. Looking at a yearly timestep, the nutrient inputs and loads in years with mean precipitation conditions were well reproduced. Years with high or low precipitation tends to result in overor underestimation of the nutrient inputs and loads, caused by the calibration of the model coefficients for mean runoff conditions. Monthly inputs and loads were calculated with MONERIS for the first time. The comparison with measured loads shows high deviations. Model improvements have to bee made regarding runoff input values (and runoff components) and retention approach (in the model version before 2008). Furthermore the spatial model resolution was investigated. It could be shown, that the MONERIS model is applicable until a resolution of 1sq.km. In a further application, MONERIS was compared with the urban stormwater management model STORM. Even though there were differences in model approaches, it could be shown a relation between the models for a comprehensive consideration of the calculation of nutrient contamination. Subsequent, a new runoff reduced approach for load calculation based on measurements of runoff and concentrations is presented. This approach allows the calculation of yearly loads with higher precision compared with well-established approaches, if only a low number of concentration measurement is available. The loads calculated from runoff and concentration measurements were important for calibration and validation of nutrient input models and can help to improve there results.

Water is a prerequisite for life on our planet. Due to climate change and pollution, water availability for agricultural production, industry and households is increasingly put at risk. With agriculture being the largest water user as well as polluter worldwide, we estimate anthropogenic nitrogen and phosphorus emissions to fresh water related to global crop production at a spatial resolution level of 5 by 5 arc min and calculate the grey water footprints (GWF) related to EU-27's crop production. A multiregional input-output model is used to trace the the GWF embodied in the final consumption of crop products by the EU-27. The total GWF related to crop production in the EU-27 in 2007 was 1 × 1012 m3/year. Spain contributed about 40% to this total. Production of cereals (wheat, rice and other cereals) take the largest share, accounting for 30% of the GWF, followed by fruits (17%), vegetables (14%), and oil crops (13%). The total agricultural GWF of the EU-27 related to crop consumption was 1830 billion m3/year, which is 3700 m3/year per capita on average. Overall, the EU-27 was able to externalize about 41% of the GWF to the rest of the world through imports of crop products.

L'optimisation structurelle dans l'industrie est souvent une tâche bien plus redoutable que ce qui était prévu par les équipes de recherche et développement. Les calculs de haute fidélité peuvent augmenter le temps CPU, ce qui nous ramène vers l'utilisation de grilles de calcul, et alors la recherche sur l'adaptation de solveurs numériques et des algorithmes d'optimisation sur les grilles de calculs. Le problème de temps CPU pour un résultat assez réaliste a aussi donné lieu à la recherche sur des stratégies de réduction de modèle pour obtenir une évaluation approximative dans une fraction de temps CPU nécessaire pour un résultat exact. A ce jour, la communauté d'optimisation multi-disciplinaire dispose d'un réseau impressionnant des méta-modèles basés sur la physique, une série d'algorithmes d'optimisation au choix et surtout des clusters/grilles de calculs puissants pour effectuer leurs simulations. Toutefois, nous rencontrons encore des problèmes dans l'optimisation industrielle. Alors que la littérature montre que la recherche existe spécifique à certains genres de problèmes dans le but d'accélérer le calcul, trois questions principales doivent être ciblés afin de pouvoir développer une véritable approche holistique et fiable de méta-modélisation pour l'optimisation structurelle industrielle. Le premier est le problème de la défaillance des serveurs de calcul, souvent en pannes ou des retards en raison d'un grand nombre d'utilisateurs concurrents. Une grille dédiée de calcul n'est jamais réaliste, et on a observé que l'absence ou de retard dans les évaluations de la fonction peuvent facilement faire dérailler un processus d'optimisation évolutionnaire. Nous présentons d'abord un protocole élégant qui va combiner notre paradigme asynchrone « Ask and future tell » avec une méta-modèle de haute qualité progressivement raffinée de manière adaptative afin de poursuivre l'optimisation en l'absence de solutions exactes. Le deuxième aspect de notre travail est une question qui a, jusqu'à présent, jamais été abordée dans le cadre de l'optimisation structurelle : celle de la dimensionnalité associé avec la domaine de conception. Nous avons observé que c'est lié au phénomène des échecs CAO à cause de la génération de géométries non admissibles. Haute dimensionnalité est un obstacle à l'optimisation efficace, car elle affecte considérablement l'efficacité des optimiseurs dans l'absence des gradients analytiques. En plus, les méthodes de paramétrage géométriques utilisées dans la CAO traditionnelle ont un taux d'échec élevé de génération de formes admissibles, comme nous l'avons observé avec les trois cas test industriels présentés par Renault. À cette fin, nous introduisons une nouvelle réduction de l'espace méta-modèle qui mappe un problème d'optimisation dans l'espace de forme, à l'aide d'une représentation unique de la forme structurelle (la fonction indicatrice) et identifie alors la variété des formes admissibles pour le problème donné et, enfin, effectue une interpolation de forme entre les géométries admissibles pour réduire la taille du problème d'optimisation tout en garantissant la faisabilité des formes générées. Le troisième aspect de notre travail concerne une incursion dans les habituelles POD basées sur des techniques pour développer un modèle d'ordre réduit pour l'amélioration de la physique d'un système. De la manière habituelle, nous attaquons le problème de la précision d'un méta-modèle sans augmenter le temps d'évaluation. Nous construisons sur le concept précédemment introduit de POD contrainte et nous introduisons une projecteur contrainte qui garantit la conservation des quantités linéaires de par leur conception, puis ajustons les coefficients de projection afin de satisfaire des contraintes quadratiques. En résumé, cette thèse combine nos recherches sur les trois sujets énumérés ci-dessus, asynchrone de substitution assistée par optimisation sur un cluster occupé / en charge, l'interpolation de forme contrainte pour l'entrée de l'espace de réduction et une énergie à la préservation de contraintes POD comme projecteur pour les contraintes quadratiques. J'ai dévéloppé de nouvelles approches pour l'optimisation de formes structurales, adaptés au calcul distribué (asynchrone). En bref, ma thèse propose: une technique de représentation des formes structurales en vue de l'optimisation (l'interpolation des formes sur la variété de formes admissibles), une technique de réduction des champs physiques (ePOD: POD sous des contraintes quadratiques), un paradigme d'optimisation asynchrone adapté à la défaillance des grilles de calcul (" Ask & Future Tell "). J'ai ensuite fait des applications de ces méthodes sur différents cas tests académiques et industriels fournis par Renault
Industrial-size structural optimization frequently ends up a far more formidable task than was originally envisioned by the research and development teams involved. It is, by now, common knowledge that high-fidelity function evaluations can prohibitively increase the CPU time, and this led to the wide-spread use of computing clusters, research on increasing the scalability of numerical solvers, parallel optimization algorithms, etc. The problem of CPU time for a sufficiently realistic result also gave birth to tomes of research on model reduction strategies to get an approximate function evaluation in a fraction of the CPU time needed for a high­ fidelity result. The multi-disciplinary optimization community now boasts of an array of impressive physics-based meta-models to choose from, a series of optimization algorithms to consider and everything from workstations to computing clusters/grids to perform the simulations. However, as far as development in high performance computing for optimization assisted by surrogate meta-modeling, we have seen but the tip of the iceberg. While literature shows that research exists specific to certain genres of problems in order to speed up computation, three main issues need to be targeted before we can develop a truly holistic and reliable meta-modeling protocol for industrial structural optimization. The first is the problem of cluster/server failures, outages or delays due to a large number of competing users. Given that a dedicated cluster to run simulations for several hours is hardly realistic, it has been observed that the absence of or delays in function evaluations due to server issues can casily derail an evolutionary optimization procedure. We first present a novel and elegant protocol that combines our asynchronous "ask and future tell" paradigm with a high-quality surrogate meta-mode! that is adaptively refined in the neighborhood of the optimal solutions to continue the optimization in the absence of exact solutions. The second aspect of our work is an issue that has, thus far, never been broached in the context of structural optimization in the literature surveyed : that of design domain dimensionality, which we observed is linked with the phenomenon of CAO failures due to the generation of inadmissible geometries. High dimensionality is by itself, quite understandably, an impediment to efficient optimization, since it greatly affects the efficiency of gradient-based optimizers unless the gradients arc available analytically. More importantly, geometric parameterization methods used in traditional CAO are seen to have a high failure rate of generating admissible shapes, as we have observed with the three industrial test-cases presented by Renault. To this end, we introduce a novel space-reduction meta-model that maps an optimization problem into "shape space" using a unique representation of structural shape (the indicator function) and then identifies the manifold of admissible shapes for the given problem and finally performs constrained shape interpolation between admissible geometries to reduce the size of the optimization problem while guaranteeing feasibility of the shapes generated. The third aspect of our work concerns a foray into the usual POO-based techniques to develop an improved reduced order model for the physics of a system. In the usual manner, we attack the ever-present problem of improving the precision of a surrogate meta model without compromising the evaluation time. We build up on the previously-introduced concept of constrained proper orthogonal decomposition to conserve linear functions of the field variables. We introduce a constrained projector that works on the coefficients obtained by projecting the snapshots on to a basis that guarantees the conservation of linear quantities by design, and then adjust these coefficients to satisfy quadratic constraints, in order to further augment the precision. Three industrial performance optimization test-cases were provided by Renault for use in the OM02 project : a 20 air-conditioning duct and 30 air-conditioning duct with 2 performance objectives each : the flow permeability and exit flow uniformity and a 30 engine intake with a single performance objective : the mass flow rate. One or more of these test-cases were used to develop, refine and finally demonstrate each of these protocols : the ask and future tell paradigm, the modified POO protocol and the diffuse­ morphing methodology. In addition, a variety of academic test-cases have been used to illustrate the methodology as and when required. Some development has also been initiated to use the diffuse-morphing space-reduction approach for the optimization of a distributed parameter : hood thickness optimization for vehicle-pedestrian head impact. Summing up, this thesis combines our research on the three subjects listed above, asynchronous surrogate-assisted optimization on a busy/loaded cluster, constrained shape interpolation for input-space reduction and an energy-preserving constrained POO-Iike projector for quadratic constraints. We believe that this thesis introduces concepts that work towards developing a robust meta­ modeling protocol for surrogate-assisted optimization. While we do focus mostly on shape optimization problems in the bulk of the narrative, we include a full extension of the space-reduction protocol for optimization of a distributed parameter (density, thickness, etc) with application to a simplified industrial problem

Uwe Wesel, professor of law at the Free University of Berlin, expressed in several of his writings an interesting thought: more than the law of obligations (Schuldrecht) the law of contracts (Vertragsrecht) is a better metadiscourse to reread and interpret the spectrum of The legal, which could even give an accurate account of the history of Western law. From the origins of the Greek civilization and to the Lisbon agreement, the contract was the institute that most connected the legal with the reasonableness, fairness, proportionality, justice and the conservative and protective sense of the community; of course also with the market economy and globalization. For this reason, this diffuse approximation of the contract and the legal business within western juridicity provides interesting inputs, such as inadvertent responses to how certain constitutional principles emerged? Or why do freedom and equality rights always entail obligations? under many others perspectives.

This chapter confronts the two principal arguments levelled against the child-as-innovator approach to language change: (1) child innovations cannot underlie historical innovations because child innovations resolve before adulthood, when they could diffuse (e.g. Traugott and Dasher 2005; Diessel 2011), and (2) parallels must hold between child innovations and historical innovations, but parallels do not hold in the domain of morphosyntax (e.g. Diessel 2012). I argue that both parallel and oppositional alignments are predicted by the two possible innovation-types children make when solving the Mapping Problem (Clark 1977, 1993, i.a.); in short, different L1A processes underlie different types of change. I further argue that input-divergent analyses at most need to persist into the teenage years, when they can be diffused via the sociolinguistic change powerhouse of teenage peer groups (e.g. Labov 2012), and may also be reinforced and prolonged in childhood via peer-to-peer acquisition and bilingualism contexts.

This article describes the conceptual framework that provides a unified description for all kinds of nanoelectronic devices covering different transport regimes from the diffusive to the ballistic limit, including molecular conductors, carbon nanotubes, and silicon transistors. More specifically, it presents a unified bottom-up viewpoint to the subject of electrical conduction of particular relevance to nanoelectronic devices and highlights the important role played by contacts. It also discusses the basic inputs that define the NEGF–Landauer model, along with its relevant equations, including those that provide a general approach to the problem of quantum transport. A few examples are given to illustrate how these equations are applied.

This chapter proposes a multiple image encryption method based on multi-dimensional chaotic equations. Four-dimensional differential chaotic equations of Lorenz attractor have been used to generate the initial security key, and alternate logistic maps have been used for encryption. Initially, three input images are used in a matrix form, where size of each image is M×N, and a composite image is derived by combining the one dimensional matrix of the input images, where size of the composite image matrix is 3×(M×N). Secondly, Lorenz attractor (LA) generates the security key using the composite matrix, and then alternate logistic map is applied with one-dimensional and two-dimensional logistic maps to confuse the matrix. In every iteration of logistic maps, XOR operation is used to encrypt the composite image, and at last, transformation is applied to diffuse the matrix. Finally, the encrypted composite image is obtained in the form of a confused matrix. The proposed algorithm reduces the correlation, increases entropy, and enhances performance of encryption.

Electronic commerce requires the redefinition of the firm’s relationships with partners, suppliers, and customers. The goal of effective customer relationship management (CRM) practice is to increase the firm’s customer equity, which is defined by the quality, quantity, and duration of customer relationships (Fjermestad & Romano, 2003). The explosive development of the online market and the rapid evolution of customer management applications have determined the companies to implement electronic customer relationship management (eCRM) systems, which are using advanced technology to enhance customer relationship management practices. The successful implementation of an eCRM system requires a specific combination of IT applications that support the classic domains of the CRM concept: marketing, sales, and service (Kennedy, 2006). Electronic marketing aims for acquiring new customers and moving existing customers to further purchases. Electronic sales try to simplify the buying process and to provide superior customer support. Electronic service has the task to provide electronic information and services for arising questions and problems or to convey customers to the right contact person in the organization. The eCRM system comprises a number of business processes, interlinked in a logical succession: • Market segmentation: The collection of historical data, complemented with information provided by third parties (such as marketing research agencies), is segmented on the basis of customer life-time value (CLV) criteria, using data mining applications. • Capturing the customer: The potential customer is attracted to the Web site of the firm through targeted promotional messages, diffused through various communication channels. • Customer information retrieval: The information retrieval process can be either implicit or explicit. When implicit, the information retrieval process registers the Web behaviour of customers, using specialized software applications, such as “cookies.” On the other hand, explicit information can be gathered through direct input of demographic data by the customer (using online registration forms or questionnaires). Often, these two categories of information are connected at database level. • Customer profile definition: The customer information collected is analyzed in relation with the target market segments identified through data mining, and a particular customer profile is defined. The profile can be enriched with additional data (e.g., external information from marketing information providers). This combination creates a holistic view of the customer, his needs, wants, interests and behaviour (Pan & Lee, 2003). • Personalization of firm-customer interaction: the customer profile is used to identify the best customer management campaign (CMC), which is applied to personalize the company-customer online interaction. • Resource management: The company-customer transaction require complex resource management operations, which are partially managed automatically, through specialized IT-applications, such as Enterprise Resource Planning (ERP) or Supply Chain Management (SCM), and partly through the direct involvement and coordination of operational managers.

An examination of the condition of the flow leaving the impeller exit kinetic energy often accounts for 30–50% of the shaft work input to the compressor stage, and for energy efficiency it is important to recover as much of this as possible. This is the function of the diffuser which follows the impeller. Effective pressure recovery downstream of an impeller is very important to realize a centrifugal compressor with high efficiency and high pressure ratio, and an appropriate selection of a diffuser for a specific impeller is a critical step to develop the compressor accordingly. The purpose of this study is to investigate the sensitivity of how compressor performances changes as vaned diffuser geometry is varied. Three kinds of vaned diffusers were studied and its results were compared. First vaned diffuser type is based on modified NACA airfoil and second is channel diffuser and third is conformal transformation of NACA 65 airfoil. A mean-line prediction method was applied to investigate the performance and stability for three kinds of diffusers. And CFD analyses have been done for comparison and detailed interior flow pattern study. In this study, the off-design behavior of three different types of diffusers, given by mean-line prediction, was investigated using CFD results and selected the NACA 65 diffuser geometry which satisfy wider operating range and higher pressure recovery than the others. The numerical results were compared with experimental data for validation.

The centrifugal compressor of marine engine turbocharger is composed of impeller, 1st vaneless diffuser, vaned diffuser, 2nd vaneless diffuser and volute casing. An examination of the condition of the flow leaving the impeller exit kinetic energy often accounts for 30–50% of the shaft work input to the compressor stage, and for energy efficiency it is important to recover as much of this as possible. This is the function of the diffuser which follows the impeller. Effective pressure recovery downstream of an impeller is very important to realize a centrifugal compressor with high efficiency and high pressure ratio, and an appropriate selection of a diffuser for a specific impeller is a critical step to develop the compressor accordingly. The purpose of this study is to investigate the sensitivity of how compressor performances changes as vaned diffuser geometry is varied. Three kinds of vaned diffusers were studied and its results were compared. First vaned diffuser type is based on NACA airfoil and second is channel diffuser and third is conformal transformation of NACA 65 airfoil. Mean-line prediction method was applied to investigate the performance and stability for three kinds of diffusers. And CFD analyses have been done for comparison and detailed interior flow pattern study. In this study, the off design behavior of three different type of diffuser, given by mean-line prediction, was investigated using CFD results and selected best diffuser geometry which satisfy wider operating range and higher pressure recovery than the others. The numerical results were compared with experimental data for validation.

If the pressure ratio of a typical single-stage centrifugal compressor is larger than four, the velocity relative to the impeller and to the diffuser exceeds the velocity of sound. The flow range of transonic centrifugal compressors with a vaned diffuser is usually very narrow. Low-solidity cascade diffusers with solidity 0.69 have been successfully applied as a part of the diffuser system of a transonic centrifugal compressor. On the basis of this type of diffuser, a series of experiments to broaden the operating range are discussed focusing on the control of the geometry of impeller and/or diffuser; one was to reduce the inducer blade turning upstream of the throat, and the other was to reduce the inlet passage width of diffuser. The milder inducer blade camber realized the improvement in flow range by 1.5 times to the original one. Regarding the diffuser inlet passage width contraction, the flow range was not broadened so much owing to the change in impeller characteristics, but the input power was reduced and then the high speed efficiency was much improved.

This paper describes the computational results on the performance of a centrifugal compressor stage with twisted vaned diffuser by varying the speed of the impeller and direction of twist for the diffuser vane. The centrifugal compressor stage configuration consists of a 2-D impeller (no twist is provided for the impeller vanes) with various configurations of diffusers. Diffuser configurations considered are Vaneless Diffuser (VLD), Low Solidity Vaned Diffuser (LSVD) and Twisted Vaned Diffuser (TVD). The analysis was carried at four different rotational speeds with corresponding mass flow rates of the impeller. 9° twist is given to the diffuser vane from hub to shroud by providing rotation at the leading edge, keeping the profile at hub as reference in the direction of rotation of the impeller and opposite to the direction of rotation of the impeller. The off-design cases considered includes operation at 80%, 90%, 110% and 120% of the design mass flow rate. CFD results are validated with experimental results for stages with VLD and LSVD for certain chosen performance parameters such as head coefficient, stage input power and exit flow angle. The computational results indicate that variations in impeller speed will cause changes in all significant performance parameters like the total pressure rise, power coefficient and efficiency of the stage and static pressure recovery coefficient of the diffuser. Contour plots were generated from CFD results and analyzed for better understanding of effect of rotational speed of the impeller on the performance of the centrifugal compressor. As a result of this study, it can be concluded that twisted vaned diffuser improves the performance in comparison to low solidity vaned diffuser for all the chosen impeller rotational speeds. The performance of the compressor stage is superior when diffuser vane twist is provided in the direction opposite to the rotation of impeller.

In most turbocharger compressors, diffusers a re designed with contractions along the passage mainly for delaying surge. The width ratio parameter, B, which defines the diffuser inlet width to diameter ratio significantly affects the losses in the diffuser. Changes to tip clearance, for example, due to the impeller rubbing the shroud casing changes the fluid flow angle at the impeller exit. The sensitivity of the absolute flow angle to the width ratio parameter has a significant influence on diffuser effectiveness and stage performance. This paper reports an investigation of tip clearance sensitivity to vaneless diffuser and stage performance of a turbocharger compressor. To assess the correlation between performance parameters and the tip clearance, Design of Experiments (DoE) was used to sample 40 design cases by changing the clearance at the leading (LE) and trailing edges (TE) of the impeller. Parameters correlation was subsequently used to determine their relationship. The key findings were that stage efficiency and pressure ratio increased linearly with decreasing LE and TE clearances having a maximum sensitivity value R = 0.7. Diffuser Cp showed a strong positive correlation for TE and a weak negative correlation for LE. Similarly, work input and diffuser loss coefficient showed an inverse relation to diffuser Cp with a maximum R value of 0.9. It was concluded that increasing the tip clearance at TE improves the diffuser effectiveness. The main source of low diffuser Cp for small tip clearances was due to higher diffusion losses as a result of flow non-uniformity when the width ratio and absolute flow angle were large. As the width ratio decreases along the passage appreciable frictional losses occur in larger tip clearance further increasing the losses. The absolute flow angle and width ratio were observed to be key to diffuser and stage performance.

Active stabilization of surge was implemented on an Allied Signal LTS-101 axi-centrifugal gas producer, reducing the surging mass flow by 1%, for an operating range increase of 11%. Control was achieved using high response sensors in the inlet and diffuser throat, coupled to actuators that injected air near the diffuser throat. System identification and modeling indicate that a classical surge-type eigenmode and an eigenmode associated with engine duct acoustics dominate the engine’s input-output properties. The surge eigenmode’s stability determines the open-loop surge mass flow. A robust linear controller with three inputs and one output stabilized this eigenmode without destabilizing the acoustic mode. The controller facilitated a 1% reduction in surging mass flow at 95% N1 corrected; this increases the engine’s choke to surge stable operating range by 11%. This paper elucidates the measured unsteady pre-surge behavior of the engine, and outlines a systematic procedure for surge control law development.

Subjected to an oscillating flow rate a compressor may feed additional (excitational) energy into the attached piping system. The relation between this additional energy input and the instantaneous behavior of a centrifugal compressor stage is dealt in a first part. Modeling the stage behavior by taking into account either inertia of the enclosed fluid mass or a first-order transient element or transient stall in any component leads to a different energy input. The energy input at a flow rate oscillation of given frequency and amplitude was calculated as a function of the slope of the characteristic and the reduced frequency applying a previously published model to describe the instantaneous behavior of the stage. In this model transient stall in the diffuser is taken into account. At reduced frequencies above unity the energy input of the diffuser was reduced by a considerable amount due to the specified instantaneous behavior of the diffuser. This indicates a potential to reduce the additional energy input of the diffuser either by increasing the time constant of the stall process or by increasing the mild surge frequency. For the investigated diffuser size the required reduced frequencies imply mild surge frequencies in a range being too high for industrial application (> 200 Hz). Still, this method turned out to give useful insight into the link between the instantaneous behavior of the compressor and its energy input. In a second part for the same centrifugal compressor the energy contribution of several stage segments during mild surge oscillations was determined from detailed instantaneous measurements. As a result the contribution of each stage segment to the conservation of the mild surge pulsation emerges. Although at the investigated mild surge frequencies the stage segments no longer behave strictly quasi-steadily their contribution to the additional energy input is found to be mainly determined by the slope of their quasi-steady characteristic.

Abstract The design of a turbocharger compressor must meet aerodynamic performance requirements, operate within specified stress and vibration limits, and respond quickly to changes in operating conditions. Design optimization must therefore include static, thermal and modal analysis (including weight and polar moment of inertia calculations) along with aerodynamic analysis (CFD). In some cases, a design optimized for aerodynamic performance only can be optimized separately to meet structural goals, using impeller backface geometry, bore radius and fillet radius inputs, which generally do not impact aerodynamic performance. If, however, impeller geometry inputs such as R1t-R1h, R2, B2 influence both aerodynamic and structural analysis, a coupled optimization is required, and each design must have both CFD and FEA analyses. In this study, a radial compressor with a vaneless diffuser at a single operating point is considered. The aerodynamic parameters for the impeller (BETA1H, BETA1S, BETA2S, main blade count, B2, R2, R1t) and diffuser (Pinch, R3/R2, Rex/R2) comprise in total 10 independent aerodynamic inputs. The aerodynamic objectives are to meet the operating point pressure ratio target and to maximize efficiency. The structural parameters for the backface (shoulder position, shoulder radius, web thickness at outer diameter (OD), OD angle, shoulder angle), bore radius and fillet radius comprise in total 7 independent structural inputs. The main structural objectives are to minimize the polar moment of inertia, and satisfy constraints on allowable maximum stress, deflection and the frequencies of blade vibration (flapping) modes. Successful multi-disciplinary optimization requires both CFD and FEA analysis to complete successfully for each trial design. Initial test runs of the optimization resulted in many geometries for which a valid CFD grid or FEA grid could not be generated. The high percentage of failed runs in the initial DOE impeded the construction of a viable surrogate model. A comprehensive investigation of all failure modes led to prescreening of both CFD and FEA geometry generation, using input constraints. The failure rate was greatly reduced as a result, leading to an improved search. Prior to the geometry screening, the optimizer found a large Pareto frontier between the efficiency and polar moment of inertia objectives. Following the screening, the efficiency and IP objectives became more cooperative. The optimization was carried out using Concepts NREC tools AxCent® and TurboOPT II™, NUMECA Fine/Turbo, and ESTECO modeFRONTIER®.