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 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.     

Genetic Control of Aerogel and Nanofoam Properties,Applied to Ni–MnOx Cathode Design

Aerogels are ultralight porous materials whose matrix structure can be formed by interlinking 880 nm long M13 phage particles. In theory, changing the phage properties would alter the aerogel matrix, but attempting this using the current production system leads to heterogeneous lengths. A phagemid system that yields a narrow length distribution that can be tuned in 0.3 nm increments from 50 to 2500 nm is designed and, independently, the persistence length varies from 14 to 68 nm by mutating the coat protein. A robotic workflow that automates each step from DNA construction to aerogel synthesis is used to build 1200 aerogels. This is applied to compare Ni–MnO_x cathodes built using different matrixes, revealing a pareto-optimal relationship between performance metrics. This work demonstrates the application of genetic engineering to create “tuning knobs” to sweep through material parameter space; in this case, toward creating a physically strong and high-capacity battery.     

High-resolution underwater acoustic imaging with lens-based systems

In recent years, several sonars designed for high-resolution, short-range underwater imaging have been developed. These imaging systems use an acoustic lens to focus the incoming waves on an array of transducers. In this article we describe three prototype systems that use a line-focus or a point-focus lens and operate at a frequency of 300 kHz or 3 MHz. The line-focus lens produces two-dimensional (2D) intensity images, while the point-focus lens produces 3D intensity images. We present sample images taken from moving and stationary platforms, and discuss the techniques used for processing the acoustic backscatter data to reconstruct and visualize the scene. The images, particularly those taken with a point-focus lens, show a remarkable degree of detail. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 377–385, 1997     

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.     

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.     

Exposing water samples to ultraviolet light improves fluorometry for detecting human fecal contamination

Fluorometry identifies human fecal contamination by detecting optical brighteners in environmental waters. Because optical brighteners are sensitive to sunlight, we determined if we could improve fluorometry by exposing water samples to ultraviolet (UV) light to differentiate between optical brighteners and other fluorescing organic compounds. Optical brighteners were likely present when the relative percentage difference in fluorometric value of the water before and after UV light exposure was >30% (glass cuvettes, 30 min exposure) or >15% (polymethacrylate cuvettes, 5 min exposure). In a blind study, we correctly identified the presence or absence of optical brighteners in 178 of 180 (99%) of the samples tested with a more expensive field fluorometer and in 175 of 180 (97%) of the samples tested with a less expensive handheld fluorometer. In the field, the method correctly identified two negative and three positive locations for human fecal contamination. When combined with counts of fecal bacteria, the new fluorometric method may be a simple, quick, and easy way to identify human fecal contamination in environmental waters.     

Using the clinical linguistic and auditory milestone scale for developmental screening in high-risk preterm infants

Eighty-one preterm infants (mean gestational age 29 weeks, range 24-36 weeks) discharged from The Johns Hopkins Hospital Neonatal Intensive Care Unit were followed up sequentially from birth to 2 years of age by use of the Clinical Linguistic and Auditory Milestone Scale (CLAMS) to evaluate language development. Children were studied during three time intervals: Interval 1: 3-5 months chronologic age (CA); Interval 2: 9-14 months (CA); and Interval 3: 18-24 months (CA). Psychometric test scores were compared with CLAMS Language Quotients (LQ) by use of full, partial (75%, 50%, 25%), and no "correction" for weeks of prematurity to determine whether "correcting" for prematurity would yield a more accurate estimate of eventual cognitive outcome. CLAMS LQ at Interval 1 was highly correlated with CLAMS LQ at Interval 2 and CLAMS LQ at Interval 2 correlated well with CLAMS LQ at Interval 3 (r = 0.57 and 0.64, respectively, P = 0.0001). Correlations indicated that there was an orderly, sequential development of language in the preterm infant. CLAMS evaluations correlated significantly with psychometric test results during Interval 2 and Interval 3 (r = 0.34, P < 0.02 and r = 0.75, P = 0.0001, respectively). The CLAMS proved to be a useful instrument for monitoring preterm language development in the primary pediatric care setting.