80 research outputs found

    Calibration Challenges for Future Radio Telescopes

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    Instruments for radio astronomical observations have come a long way. While the first telescopes were based on very large dishes and 2-antenna interferometers, current instruments consist of dozens of steerable dishes, whereas future instruments will be even larger distributed sensor arrays with a hierarchy of phased array elements. For such arrays to provide meaningful output (images), accurate calibration is of critical importance. Calibration must solve for the unknown antenna gains and phases, as well as the unknown atmospheric and ionospheric disturbances. Future telescopes will have a large number of elements and a large field of view. In this case the parameters are strongly direction dependent, resulting in a large number of unknown parameters even if appropriately constrained physical or phenomenological descriptions are used. This makes calibration a daunting parameter estimation task, that is reviewed from a signal processing perspective in this article.Comment: 12 pages, 7 figures, 20 subfigures The title quoted in the meta-data is the title after release / final editing

    The cheeseboard in Dutch fine dining restaurants, I: Practices and opinions of restaurant professionals

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    The difficulties in serving a cheeseboard are explored in this paper. From literature 1940–2010, for accompanying cheeses, a shift was found from red to white wines and from dry to sweeter wines. There is also a tendency to more and sweeter garnishes with the cheese. Interviews with professionals from nine Dutch restaurants largely confirmed these tendencies. In most restaurants, a varied cheeseboard was offered with sweet breads and garnishes. Many customers only finished the wine from the main dish with the cheeseboard. When a new wine was ordered, it was most of the time a sweet wine that did not match with all the cheeses of the cheeseboard. Recommendations for improving this situation are given.Keywords: fine dining restaurants, wine-food combinations, flavour profiles, flavour styl

    Effect of long-term Sodium Hypochlorite Cleaning on Silicon Carbide Ultrafiltration Membranes Prepared by Low-Pressure Chemical Vapor Deposition

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    Sodium hypochlorite (NaClO) is widely used for the chemical cleaning of fouled ultrafiltration (UF) membranes. Various studies performed on polymeric membranes demonstrate that long-term (&gt;100 h) exposure to NaClO deteriorates the physicochemical properties of the membranes, leading to reduced performance and service life. However, the effect of NaClO cleaning on ceramic membranes, particularly the number of cleaning cycles they can undergo to alleviate irreversible fouling, remains poorly understood. Silicon carbide (SiC) membranes have garnered widespread attention for water and wastewater treatment, but their chemical stability in NaClO has not been studied. Low-pressure chemical vapor deposition (LP-CVD) provides a simple and economical route to prepare/modify ceramic membranes. As such, LP-CVD facilitates the preparation of SiC membranes: (a) in a single step; and (b) at much lower temperatures (700–900 °C) in comparison with sol-gel methods (ca. 2000 °C). In this work, SiC ultrafiltration (UF) membranes were prepared via LP-CVD at two different deposition temperatures and pressures. Subsequently, their chemical stability in NaClO was investigated over 200 h of aging. Afterward, the properties and performance of as-prepared SiC UF membranes were evaluated before and after aging to determine the optimal deposition conditions. Our results indicate that the SiC UF membrane prepared via LP-CVD at 860 °C and 100 mTorr exhibited excellent resistance to NaClO aging, while the membrane prepared at 750 °C and 600 mTorr significantly deteriorated. These findings not only highlight a novel preparation route for SiC membranes in a single step via LP-CVD, but also provide new insights about the careful selection of LP-CVD conditions for SiC membranes to ensure their long-term performance and robustness under harsh chemical cleaning conditions.</div

    Problems and Promises of Health Technologies: The Role of Early Health Economic Modeling

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    Background: To assess whether early health economic modeling helps to distinguish those healthcare innovations that are potentially cost-effective from those that are not potentially cost-effective. We will also study what information is retrieved from the health economic models to inform further development, research and implementation decisions.Methods: We performed secondary analyses on an existing database of 32 health economic modeling assessments of 30 innovations, performed by our group. First, we explored whether the assessments could distinguish innovations with potential cost-effectiveness from innovations without potential cost-effectiveness. Second, we explored which recommendations were made regarding development, implementation and further research of the innovation. Results: Of the 30 innovations, 1 (3%) was an idea that was not yet being developed and 14 (47%) were under development. Eight (27%) innovations had finished development, and another 7 (23%) innovations were on the market. Although all assessments showed that the innovation had the potential to become cost-effective, due to improved patient outcomes, cost savings or both, differences were found in the magnitude of the potential benefits, and the likelihood of reaching this potential. The assessments informed how the innovation could be further developed or positioned to maximize its cost-effectiveness, and informed further research.Conclusion: The early health economic assessments provided insight in the potential cost-effectiveness of an innovation in its intended context, and the associated uncertainty. None of the assessments resulted in a firm ‘no-go’ recommendation, but recommendations could be provided on further research and development in order to maximize value for money

    Voorspellen van recidive. Een onderzoek naar de voorspelbaarheid van herhaling van krimineel gedrag bij ernstige gevallen van kriminaliteit

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    In this book we have dealt with the predictability of recidivism in cases of serious criminality. In Chapter 1 we have presented an introduction to criminological prediction. Besides mentioning a number of objections against the prediction of criminal behaviour we have pointed to specific advantages a prognostic instrument produces. ... Zie: Summary

    Probation Supervision through GPS

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