The Design of OpenMP Tasks Ayguade, E.; Copty, N.; Duran, A. ...
IEEE transactions on parallel and distributed systems,
03/2009, Letnik:
20, Številka:
3
Journal Article, Publication
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OpenMP has been very successful in exploiting structured parallelism in applications. With increasing application complexity, there is a growing need for addressing irregular parallelism in the ...presence of complicated control structures. This is evident in various efforts by the industry and research communities to provide a solution to this challenging problem. One of the primary goals of OpenMP 3.0 is to define a standard dialect to express and efficiently exploit unstructured parallelism. This paper presents the design of the OpenMP tasking model by members of the OpenMP 3.0 tasking sub-committee which was formed for this purpose. The paper summarizes the efforts of the sub-committee (spanning over two years) in designing, evaluating and seamlessly integrating the tasking model into the OpenMP specification. In this paper, we present the design goals and key features of the tasking model, including a rich set of examples and an in-depth discussion of the rationale behind various design choices. We compare a prototype implementation of the tasking model with existing models, and evaluate it on a wide range of applications. The comparison shows that the OpenMP tasking model provides expressiveness, flexibility, and huge potential for performance and scalability.
•Leaching potential of 3 different types of nano-ZnO in real fresh MSW was investigated.•Batch tests were conducted at different pH, ionic strength and ZnO concentrations.•Most of the added nano-ZnO ...mass was retained within the solid waste matrix.•The pH and IS conditions did not significantly influence the leaching behavior of ZnO.•A kinetic particle deposition/detachment model was developed to analyze ZnO behavior.
Despite widespread use of engineered nanomaterials (ENMs) in commercial products and their potential disposal in landfills, the fate of ENMs in solid waste environments are still not well understood. In this study, the leaching behavior of nano ZnO -one of the most used ENMs- in fresh municipal solid waste (MSW) was investigated. Batch reactors containing municipal solid waste samples were spiked with three different types of nano ZnO having different surface stabilization. The leaching of ZnO was examined under acidic, basic and elevated ionic strength (IS) conditions. The results of the 3-day batch tests showed that the percent of the added nano-ZnO mass retained within the solid waste matrix ranged between 80% and 93% on average for the three types of nano-ZnO tested. The pH and IS conditions did not significantly influence the leaching behavior of ZnO. To further analyze the behavior of ZnO in the MSW matrix, a kinetic particle deposition/detachment model was developed. The model was able to reproduce the main trends of the batch experiments. Reaction rate constants for the batch tests ranged from 0.01 to 0.4 1/hr, reflecting the rapid deposition of nano-ZnO within the MSW matrix.
With the rapid development in nanotechnology in recent years, the number of commercially available products containing engineered nanomaterials (ENMs) has increased significantly. It is expected that ...large fractions of these ENMs will end up in landfills for final disposal. Despite the wide use of ENMs, little data is available on their fate within landfills. This study examined the leaching behavior of nanoscale titanium dioxide (nano-TiO2), one of the mostly used ENMs, in fresh municipal solid wastes (MSWs). Batch reactors containing municipal waste samples were spiked with a range of nano-TiO2 concentrations at different pH and ionic strength conditions. The Ti concentrations in leachate decreased rapidly and reached steady state after about 12–24 h. Results suggest that, for the environmental conditions considered, approximately 3–19% of the added nano-TiO2remained in leachate. Batch tests conducted with individual synthetically-prepared solid waste components also showed low leaching potential (5.2% for organic waste, 3.3% for glass, 1.7% for both textile and paper and 0.6% for metal), indicating that all components of MSW contributed to the retention of the nano-TiO2 mass within the solid matrix.
•Leaching potential of nano-TiO2 in real fresh MSW was investigated.•Batch tests were conducted at different pH, ionic strength and Ti concentrations.•For all experimental conditions, most of the added Ti was retained in the waste.•All MSW components contributed to the retention of the nano-TiO2.
The Physics of the B Factories Bevan, Adrian; Golob, Bostjan; Mannel, Thomas ...
European physical journal. C, Particles and fields,
March 2015, Letnik:
74, Številka:
11
eBook, Journal Article
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This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related ...issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C.
Accurate estimation of level change in lakes and reservoirs in response to climatic variations is an important step for the development of sustainable water usage policies, particularly for complex ...hydrological systems such as Lake Beysehir, Turkey. In this study, level changes of Lake Beysehir were estimated using adaptive neuro-fuzzy inference system (ANFIS), artificial neural networks (ANN) and a seasonal autoregressive integrated moving average (SARIMA). The ANN and ANFIS models were first trained based on observed data between 1966 and 1984, and then used to predict water level changes over the test period extending from 1985 to 1990. The performances of the different models were evaluated by comparing the corresponding values of mean squared errors (MSE) and decisive coefficients (
R
2). While all models produced acceptable results, the minimum MSE value (0.0057) and the maximum
R
2 value (0.7930) were obtained with ANFIS model, followed by the three-layered artificial neural network model (ANN1). The lowest performance was observed with the SARIMA model.
The deleterious effects of sodium-induced secondary alkalinization on soil structure and hydraulic properties of calcareous soils can vary widely. This study aims to evaluate the impact of sodicity ...and leaching velocity on the physical and hydraulic properties of a calcareous clay-rich soil. Two application rates of tap water (TW) and sodic water (SW) are considered: fast leaching, equal to the saturated hydraulic conductivity, Ks, and slow leaching conditions, equal to have 1/2 Ks. For the TW and SW experiments, up to 14 and 26 leaching cycles were performed in duplicates, respectively. After the leaching applications, the PVC columns were cut horizontally, and undisturbed samples were removed from the different depths. It was observed that neither water quality nor water flow rate significantly affected water stable aggregate percentages. TW did not affect soil total porosity and bulk density except at the bottom of the column. On the other hand, there were remarkable reductions in soil porosity and bulk density in the SW leaching experiments ranging from 8.8 to 12.5% and 7.4–13.8%, respectively. High Na concentrations in leaching water caused aggregate swelling and dispersion, leading to reduced Na+ and enhanced Ca2+ transport to the lower portions of the soil column. In the lower layers, the severity of sodium-induced dispersion was restricted by calcium, which was exchanged by the excess amount of Na from the upper layers, maintaining soil particles flocculated. Ca2+, which tightens the soil particles and aggregates together, limited Na-induced disruption of the soil aggregation. Nonetheless, particles that broke away from aggregate did influence the hydraulic properties of the soils. Overall, the experiments revealed that although the physical and hydraulic properties of the soil are affected by the sodic waters and the flow rates, this effect is reduced in calcareous soils due to their strong bonding feature.
•Deleterious effect of Na on aggregation is less evident in calcareous clay-rich soil.•Sodium-induced degradation is more pronounced in the upper layers of calcareous soil.•Aggregates of well-structured calcareous soils resist compaction caused by Na.•Increased flow rates of sodic water accelerate soil degradation.•The higher the limestone and clay content, the more stable the soil structure.
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