Developments in remote metrology at JET

The need to maximise the operational availability of fusion devices has driven the enhancements in accuracy, flexibility and speed associated with the inspection techniques used at JET. To this end, the remote installation of the ITER-Like Wall (ILW) tiles, conduits and embedded diagnostics has necessitated the adoption of technologies from other industries for their use in conjunction with the JET Remote Handling (RH) system. The novel adaptation of targetless stereophotogrammetry, targeted single-camera photogrammetry and gap measurement techniques for remote applications has prompted a range of challenges and lessons learnt both from the design process and operational experience.Interfacing Commercial Off-The-Shelf (COTS) components with the existing RH equipment has highlighted several issues of relevance to the developing ITER RH system. This paper reports results from the stereophotogrammetry and the single-camera photogrammetry surveys, allowing analysis of the effectiveness of the RH system as a platform for in-vessel measurement. This includes scrutiny of the accuracy achieved with each technique as well as the impact on the in-vessel Configuration Management Model (CMM). The paper concludes with a summary of key recommendations for the ITER RH system based on the experience of remote metrology at JET.     

Outer Scaling for Open Channel Flow over a Gravel Bed

Similarity analysis is performed for hydraulically rough open channel flow over a gravel bed to provide mixed outer scaling of the mean-velocity profile. The analysis is based on equilibrium turbulent boundary-layer theory derived using the asymptotic invariance principle. Outer scaling based on the similarity theory is validated with velocity measurements from the laboratory and field, having a Reynolds number range that includes 1×104, 1×105, and 1×106 and a Froude number range from 0.26 to 0.83. The results show that the free-stream velocity is an appropriate outer scale for gravel-bed river flows at moderate and bankfull stage. The results agree well with the velocity measurements and collapse laboratory and field data, which allow an important connection between open channel research in the laboratory and the applications for which the research is performed in the field. The results show that the R/aD84 roughness parameter is consistent with the mixed scale used in boundary-layer velocity scaling. This is in agreement with the consistent turbulent structure of the flow for both flat plate boundary-layer and open channel flow scenarios. While R/D84 has been used empirically with depth-averaged velocity and roughness laws for many years, this roughness parameter is shown in a theoretical context due to its influence on the turbulent structure of the flow. The results are applicable to modeling the velocity distribution under fundamental gravel-bed flow cases that span to the bankfull flow regime, which provides a contribution to stream engineering.     

A constant transition array switching method for improving SFDR and resolution in a segmented digital to analogue converter

Conventional methods for correcting linearity errors in a digital to analogue converter (DAC) rely on characterising the DAC first. This paper describes a technique that can increase linearity without characterising the DAC. It is in principle, able to remove completely deterministic errors in a segmented DAC and therefore increase SFDR. As no calibration is needed, the improvement can track dynamically changing errors due for example to thermal effects. Results with an 8-bit DAC show an increase in SFDR of at least 25 dB.     

Theoretical limits on SAR imposed by the ionosphere

The ultimate theoretical limitations on space-based synthetic aperture radar (SAR) image formation that are imposed by the ionosphere are examined. The effects on the SAR image are derived from first principles, and it is shown that the ionosphere will cause defocusing in both the range and along track directions. The performance of an autofocus procedure is then examined, and it is shown that the range defocusing can always be removed, but the range time delay can only be determined for high percentage bandwidths and high signal-to-noise plus clutter ratios. It is also shown that the performance limits of autofocus are not determined by the absolute total electron content, but are given by the amount of ionospheric turbulence, which limits the along track resolution. The relationship between the requirement for a focussed SAR image and the S4 index and the integrated strength of turbulence C/sub k/L is derived.     

A study of the factors influencing the performance of ternary MEH-PPV:porphyrin:PCBM heterojunction devices: A steric approach to controlling charge recombination

A series of three porphyrins varying only in the steric bulk of their peripheral groups have been synthesised and integrated into the active layer of bulk heterojunction solar cells. The porphyrins broaden the spectral response of the device and contribute to the total photocurrent generated. More importantly, the device characteristics change systematically with increasing steric bulk on the peripheral meso phenyl groups of the tetra-phenyl porphyrin. Optical, scanning probe and scanning transmission X-ray microscopy are used to demonstrate that the observed changes do not arise from morphological differences in film structure. Cyclic voltammetry, UV-vis spectroscopy and DFT calculations are used to establish that the porphyrin LUMO, HOMO and bandgap are independent of side group. We conclude that the variations in open-circuit voltage with side group are the result of the porphyrin acting as a bimolecular recombination centre, with an efficiency that is dependent on the side group type. The possibility of designing optimised macromolecules for OPV devices based on an understanding the effect of porphyrin steric bulk upon device performance is discussed.     

A randomized trial of a brief HIV risk reduction counseling intervention for women.

There is an urgent need for the development and implementation of effective and feasible behavioral HIV and STD interventions. The purpose of the present randomized controlled trial was to evaluate the effectiveness of a single-session, skill-based sexual risk reduction intervention for women. Participants were assessed at baseline and at 1 month and 3 months following the intervention on measures of AIDS knowledge, behavioral intentions, self-efficacy, and sexual risk behavior. Compared with women in an AIDS-education-only condition, women receiving the skill-based intervention reported significantly higher rates of condom use at 3-month follow-up. Results suggest that brief sexual risk reduction programs are feasible and effective within a community setting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of morbidity interviews with a health examination survey in rural Africa

This paper describes a study of the Danfa Comprehensive Rural Health and Family Planning Project, Ghana. The report compares information obtained from morbidity interviews with information obtained during subsequent health examinations. One to 4 days prior to examination by a team of physicians, 3,653 rural Ghanaians were interviewed by a team of auxiliary workers. Information obtained from the interview survey was noticeably different from examination diagnoses. Significant health problems such as malaria, intestinal parasites and diarrhea, as well as minor and chronic conditions were seriously under-reported. Interview findings were more accurate for children, women in the reproductive age group, and in cases in which the disease caused considerable discomfort or diability. Although individual examination was eight times as costly as an interview, small scale rural health examination surveys of a representative sample of the population are recommended to provide accurate morbidity information for health planners.     

Keratinizing dermatoses. Combined data from four centers on short-term topical treatment with tretinoin

In four medical centers, 40 patients with keratinizing dermatoses were treated with topical tretinoin (vitamin A acid) 0.1% cream and salicylic acid 2% cream in a short-term, double-blind study. Tretinoin was the more effective treatment for several of the keratinizing dermatoses with the exception of palmar-plantar hyperkeratosis, for which it was not effective in the concentration and method of application used. The most striking clinical responses occurred in patients with lamellar ichthyosis and ichthyosis vulgaris. Local adverse reactions-chiefly pruritus, erythema, burning, excoriation, and irritation-were not severe and could be controlled by modification of the treatment regimen.     

Two studies with the Psychiatric Rehabiliation Attitude Survey.

Evaluated the Psychiatric Rehabilitation Attitude Survey (PRAS) by the 1st author and A. Sklare-Lancaster (1981) in 2 experiments. In Exp I, reliability and validity data of the PRAS were assessed, using 37 vocational rehabilitation practitioners. Results indicate that test–retest reliability was high and that convergent and divergent validity were adequate compared with the Attitudes Toward Disabled Persons Scale and the Marlowe-Crowne Social Desirability Scale. Exp II assessed the effect of a 4-wk field placement on the attitudes of 48 undergraduate rehabilitation psychology majors. There was a significant positive change in Ss' attitudes toward psychiatric rehabilitation, and their scores after field placement were significantly more positive than norms obtained from general-caseload rehabilitation practitioners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)