| 1. |
- Joffrin, E., et al.
(författare)
-
Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
-
Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
|
|
| 2. |
- Fenstermacher, M.E., et al.
(författare)
-
DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
- 2022
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4
-
Tidskriftsartikel (refereegranskat)abstract
- DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L-H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.
|
|
| 3. |
- Muncke, J., et al.
(författare)
-
Scientific Challenges in the Risk Assessment of Food Contact Materials
- 2017
-
Ingår i: Environmental health perspectives. - 1552-9924. ; 125:9
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Food contact articles (FCAs) are manufactured from food contact materials (FCMs) that include plastics, paper, metal, glass, and printing inks. Chemicals can migrate from FCAs into food during storage, processing, and transportation. Food contact materials' safety is evaluated using chemical risk assessment (RA). Several challenges to the RA of FCAs exist. OBJECTIVES: We review regulatory requirements for RA of FCMs in the United States and Europe, identify gaps in RA, and highlight opportunities for improving the protection of public health. We intend to initiate a discussion in the wider scientific community to enhance the safety of food contact articles. DISCUSSION: Based on our evaluation of the evidence, we conclude that current regulations are insufficient for addressing chemical exposures from FCAs. RA currently focuses on monomers and additives used in the manufacture of products, but it does not cover all substances formed in the production processes. Several factors hamper effective RA for many FCMs, including a lack of information on chemical identity, inadequate assessment of hazardous properties, and missing exposure data. Companies make decisions about the safety of some food contact chemicals (FCCs) without review by public authorities. Some chemical migration limits cannot be enforced because analytical standards are unavailable. CONCLUSION: We think that exposures to hazardous substances migrating from FCAs require more attention. We recommend a) limiting the number and types of chemicals authorized for manufacture and b) developing novel approaches for assessing the safety of chemicals in FCAs, including unidentified chemicals that form during or after production. https://doi.org/10.1289/EHP644.
|
|
| 4. |
|
|
| 5. |
- Harrison, M. E., et al.
(författare)
-
Comparison between CFD simulations and experiments for predicting the far wake of horizontal axis tidal turbines
- 2010
-
Ingår i: IET Renewable Power Generation. - : Institution of Engineering and Technology. - 1752-1416 .- 1752-1424. ; 4:6, s. 613-627
-
Tidskriftsartikel (refereegranskat)abstract
- The actuator disc is a useful method for parameterising a tidal stream turbine in a solution of the Reynolds-averaged Navier–Stokes equations. An actuator disc is a region where similar forces are applied to a flow as would be imposed by a turbine. It is useful where large-scale flow characteristics are of interest, such as the far wake, free surface effects, or installation of multi-turbine arrays. This study compares the characteristics of the wake of an actuator disc, modelled using a steady solution to the Reynolds-averaged Navier–Stokes (RANS) simulated equations, with the k–ω shear stress transport (SST) turbulence model, to experimental data measured behind discs of various porosities. The results show that the wake of the experimental and modelled discs has similar characteristics; in both model and experiment, velocity in the near wake decreased as thrust coefficient increased. However, the near wake region in the experiment was shorter than simulated in the model because of near wake turbulence. This, combined with lower ambient turbulence levels in the model, meant that the far wake recovered further downstream, while showing similar overall trends in velocity and turbulence intensity.
|
|
| 6. |
- James, P. A. B., et al.
(författare)
-
Implications of the UK field trial of building mounted horizontal axis micro-wind turbines
- 2010
-
Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215 .- 1873-6777. ; 38:10, s. 6130-6144
-
Tidskriftsartikel (refereegranskat)abstract
- Building mounted micro-wind turbines and photovoltaics have the potential to provide widely applicable carbon free electricity generation at the building level. Photovoltaic systems are well understood and it is easy to predict performance using software tools or widely accepted yield estimates. Micro-wind, however, is far more complex and in comparison poorly understood. This paper presents the key findings of the building mounted (<2 kWp) turbine component of the UK micro-wind trial undertaken by the Energy Saving Trust in 2008/09. The monitored performance of 39 horizontal axis turbines in urban, suburban and rural locations is discussed alongside the accuracy of predictive wind speed tools for the sites. The performance of urban and suburban micro-wind sites in the trial was poor with annual generation of less than 75 kWh/m2 swept area, the majority of which were less than 25 kWh/m2. Good rural sites had an annual generation of between 100 and 280 kWh/m2, far less than the nominal 360 kWh/m2 (10% load factor for a typical turbine) that is often assumed. In the light of these findings, the potential impact of the UK’s latest policy instrument, the 2010 micro-generation tariffs, is considered for both micro-wind and photovoltaics.
|
|
| 7. |
- Sissons, M. F., et al.
(författare)
-
Pole-mounted horizontal axis micro-wind turbines : UK field trial findings and market size assessment
- 2011
-
Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215 .- 1873-6777. ; 39:6, s. 3822-3831
-
Tidskriftsartikel (refereegranskat)abstract
- This paper discusses the key findings of the pole-mounted turbine (2.5–6 kWp) component of the UK micro-wind trial. The real world performance of horizontal axis turbines is compared with yield estimates based on site wind speed prediction. The distribution of UK agricultural farms is overlaid with wind resource mapping to estimate the number of potential agricultural farm sites for micro-wind. The yield performance of turbines during the monitoring period was observed to be very close to that predicted by NOABL–MCS wind speed estimates. Based on an installation criterion of a maximum 12 year payback time, with a 6% discount rate and micro-generation feed in tariffs available, there are ∼87,000 farm sites for micro-wind in the UK. If 10% of these farms were to install micro-wind turbines (to a capacity of 48 kWp per farm) this would correspond to a capacity of 418 MWp, with an annual generation yield of 1025 GWh, comparable to that of a large, on shore wind farm in the UK. It should be noted that the feed in tariff considered in this paper is that available in the UK in 2011, which, at 26.7 p/kWh (∼30 Euro cents/kWh) represents a significant subsidy.
|
|
| 8. |
- Burvall, Anna, et al.
(författare)
-
Singular-value decomposition of a tomosynthesis system
- 2010
-
Ingår i: Optics Express. - 1094-4087. ; 18:20, s. 20699-20711
-
Tidskriftsartikel (refereegranskat)abstract
- Tomosynthesis is an emerging technique with potential to replace mammography, since it gives 3D information at a relatively small increase in dose and cost. We present an analytical singular-value decomposition of a tomosynthesis system, which provides the measurement component of any given object. The method is demonstrated on an example object. The measurement component can be used as a reconstruction of the object, and can also be utilized in future observer studies of tomosynthesis image quality.
|
|
| 9. |
- Kurtz, Sherry L., et al.
(författare)
-
Whole genome profiling refines a panel of correlates to predict vaccine efficacy against Mycobacterium tuberculosis
- 2020
-
Ingår i: Tuberculosis. - : Elsevier. - 1472-9792 .- 1873-281X. ; 120
-
Tidskriftsartikel (refereegranskat)abstract
- New vaccines are needed to combat the public health threat posed by M. tuberculosis (M. tb), but no correlates have been defined to aid vaccine development. Using mouse models, we previously developed an in vitro system that measures the ability of M. tb-immune lymphocytes to control bacterial replication during co-culture with M. tb-infected macrophages. We demonstrated that the degree of in vitro growth control by lymphocytes from mice given vaccines of varying efficacy reflected the relative degree of in vivo protection against lethal challenge. Further, using targeted analyses of gene expression in lymphocytes recovered from co-cultures, we found mediators whose relative expression also correlated with in vitro and in vivo outcomes. Here we advanced those findings by employing genome-wide expression analyses. We first screened splenocytes recovered from co-cultures by microarray, revealing additional genes whose expression correlated with protection. After applying pathway analyses to down-select gene candidates, we used both splenocytes and peripheral blood lymphocytes to validate microarray findings by qRT-PCR. We then subjected data from top candidates to rigorous statistical analyses. Resulting correlate candidates, including CXCL9, IFN-γ, and CCL5, significantly predicted protection with high specificity. These findings therefore refine and extend a panel of relevant immune correlates to advance vaccine development.
|
|
