Icing and De-Icing of a Propeller with Internal Electric Blade Heaters

An investigation has been made in the NACA Cleveland icing research tunnel to determine the de-icing effectiveness of an experimental configuration of an Internal electric propeller-blade heater. Two atmospheric Icing conditions and two propeller operating conditions were Investigated, In experiments with unheated blades and with heat applied to the blades both continuously and cyclically. Data are presented to show the effect of propeller speed., ambient air temperature and liquid-water concentration, and the duration of the heat-on and cycle times on the power requirements and de-Icing performance of the blade heaters. The extent of ice-covered area on the blades for various icing ax4 operating conditions has been determined. The largest iced area was obtained at the higher ambient-air temperatures and at low propeller speed. The ohord.wise extent of Icing In practically every case was greater than that covered by blade heaters. Adequate de-icing in the heated area with continuous application of heat was obtained with the power available but a maximum power, input of 1250 watts per blade was insufficient for cyclic de-Icing for the range of conditions investigated. Blade-surface temperature rates of rise of 0.2 to 0.7 F per second were obtained and the minimum cooling period for cyclic de-icing was found to be approximately 2-1/2 times the heating period

Proceedings of the Spacecraft Charging Technology Conference: Executive Summary

Aerospace environments are reviewed in reference to spacecraft charging. Modelling, a theoretical scheme which can be used to describe the structure of the sheath around the spacecraft and to calculate the charging currents within, is discussed. Materials characterization is considered for experimental determination of the behavior of typical spacecraft materials when exposed to simulated geomagnetic substorm conditions. Materials development is also examined for controlling and minimizing spacecraft charging or at least for distributing the charge in an equipotential manner, using electrical conductive surfaces for materials exposed to space environment

Mapping urban infrastructure interdependencies and fuzzy risks

This is the final version of the article. Available from Elsevier via the DOI in this record.In this study, we considered the relationships between different types of CI and services to simulate possible cascading effects during extreme hazard conditions brought on by climate change and how to analyse impacts with limited data resources. An area in central Bristol, UK, was used as the case study to investigate the interdependencies among select assets and services. A wide range of plausible scenarios caused by pipe bursts in the area were simulated using the CADDIES 2D modelling framework, to identify the hotspots with high risk. The impact on CI, including water supply, electricity, wastewater, solid waste, transportation, telecommunication, and emergency services were assessed by the HAZUR tool. The analysis demonstrated that with limited data resources the dynamics of the interdependencies between CI networks can be highlighted and a basis of risk quantification can be established. The same procedure can be repeated to evaluate the impact of other types of hazards, or the compound hazard scenarios to provide a holistic assessment. Therefore, urban planners and managers can further explore options of interventions for setting up strategies to strengthen city resilience.This study is supported by the RESCCUE (RESilience to cope with Climate Change in Urban arEas) project, funded by the European Union Horizon 2020 research and innovation programme (Grant Agreement No. 700174)

First results of material charging in the space environment

A satellite experiment, designed to measure potential charging of typical thermal control materials at near geosynchronous altitude, was flown as part of the SCATHA program. Direct observations of charging of typical satellite materials in a natural charging event ( 5 keV) are presented. The results show some features which differ significantly from previous laboratory simulations of the environment

Inhomogeneous magnetization in dipolar ferromagnetic liquids

At high densities fluids of strongly dipolar spherical particles exhibit spontaneous long-ranged orientational order. Typically, due to demagnetization effects induced by the long range of the dipolar interactions, the magnetization structure is spatially inhomogeneous and depends on the shape of the sample. We determine this structure for a cubic sample by the free minimization of an appropriate microscopic density functional using simulated annealing. We find a vortex structure resembling four domains separated by four domain walls whose thickness increases proportional to the system size L. There are indications that for large L the whole configuration scales with the system size. Near the axis of the mainly planar vortex structure the direction of the magnetization escapes into the third dimension or, at higher temperatures, the absolute value of the magnetization is strongly reduced. Thus the orientational order is characterized by two point defects at the top and the bottom of the sample, respectively. The equilibrium structure in an external field and the transition to a homogeneous magnetization for strong fields are analyzed, too.Comment: 17 postscript figures included, submitted to Phys. Rev.

Carbon and nitrogen isotopic ratios of urine and faeces as novel nutritional biomarkers of meat and fish intake

Purpose Meat and fish consumption are associated with changes in the risk of chronic diseases. Intake is mainly assessed using self-reporting, as no true quantitative nutritional biomarker is available. The measurement of plasma fatty acids, often used as an alternative, is expensive and time-consuming. As meat and fish differ in their stable isotope ratios, δ13C and δ15N have been proposed as biomarkers. However, they have never been investigated in controlled human dietary intervention studies. Objective In a short-term feeding study, we investigated the suitability of δ13C and δ15N in blood, urine and faeces as biomarkers of meat and fish intake. Methods The dietary intervention study (n = 14) followed a randomised cross-over design with three eight-day dietary periods (meat, fish and half-meat–half-fish). In addition, 4 participants completed a vegetarian control period. At the end of each period, 24-h urine, fasting venous blood and faeces were collected and their δ13C and δ15N analysed. Results There was a significant difference between diets in isotope ratios in faeces and urine samples, but not in blood samples (Kruskal–Wallis test, p < 0.0001). In pairwise comparisons, δ13C and δ15N were significantly higher in urine and faecal samples following a fish diet when compared with all other diets, and significantly lower following a vegetarian diet. There was no significant difference in isotope ratio between meat and half-meat–half-fish diets for blood, urine or faecal samples. Conclusions The results of this study show that urinary and faecal δ13C and δ15N are suitable candidate biomarkers for short-term meat and fish intake

Asymptotics and local constancy of characters of p-adic groups

In this paper we study quantitative aspects of trace characters $\Theta_\pi$ of reductive $p$-adic groups when the representation $\pi$ varies. Our approach is based on the local constancy of characters and we survey some other related results. We formulate a conjecture on the behavior of $\Theta_\pi$ relative to the formal degree of $\pi$, which we are able to prove in the case where $\pi$ is a tame supercuspidal. The proof builds on J.-K.~Yu's construction and the structure of Moy-Prasad subgroups.Comment: Proceedings of Simons symposium on the trace formul

NRLMSIS 2.1: An Empirical Model of Nitric Oxide Incorporated Into MSIS

We have developed an empirical model of nitric oxide (NO) number density at altitudes from ∼73 km to the exobase, as a function of altitude, latitude, day of year, solar zenith angle, solar activity, and geomagnetic activity. The model is part of the NRLMSIS® 2.1 empirical model of atmospheric temperature and species densities; this upgrade to NRLMSIS 2.0 consists solely of the addition of NO. MSIS 2.1 assimilates observations from six space-based instruments: UARS/HALOE, SNOE, Envisat/MIPAS, ACE/FTS, Odin/SMR, and AIM/SOFIE. We additionally evaluated the new model against independent extant NO data sets. In this paper, we describe the formulation and fitting of the model, examine biases between the data sets and model and among the data sets, compare with another empirical NO model (NOEM), and discuss scientific aspects of our analysis

Cultural adaptation and psychometric evaluation of the Swedish version of the Reproductive Concerns After Cancer (RCAC) scale

BACKGROUND: Reproductive concerns are common among young cancer survivors and include worries related to different aspects of fertility and parenthood. The Reproductive Concerns After Cancer (RCAC) scale is an 18-item scale with six dimensions, developed to capture a variety of such concerns. The aim of the present study was to describe the cultural adaptation of the RCAC scale into Swedish and evaluate its psychometric properties among young women who have undergone treatment for cancer. METHODS: The RCAC was forward translated from English into Swedish and assessed for cultural adaptation based on a two-panel approach followed by cognitive interviews with the target group. For the psychometric evaluation, a Swedish cohort of 181 female young adult breast cancer survivors completed a survey including the RCAC scale approximately 1.5 years post-diagnosis. Psychometric properties were examined by analyses of construct validity (confirmatory factor analysis and convergent validity), data quality (score distribution, floor and ceiling effects), reliability and known-groups validity. RESULTS: The confirmatory factor analysis yielded an acceptable fit (RMSEA 0.08, SRMR 0.09, CFI 0.92). Convergent validity was demonstrated by a negative correlation of moderate size (- 0.36) between the RCAC total score and the emotional function scale of the EORTC QLQ-C30. Reliability measured with Revelle Ω total was satisfactory (0.73-0.92) for five of the dimensions, and poor for the dimension Becoming pregnant (Revelle Ω total = 0.60); Cronbach's alpha showed a similar pattern. Known-groups validity was indicated by significant RCAC mean score differences (MD), reflecting more concerns among women with a certain (MD 4.56 [95% CI 3.13 to 5.99]) or uncertain (MD 3.41 [95% CI 1.68 to 5.14]) child wish compared to those with no wish for (additional) children. CONCLUSION: The translation and cultural adaptation of the Swedish RCAC has resulted in a scale demonstrating construct and known-groups validity, and satisfactory reliability for five of six dimensions. The dimension Becoming pregnant showed non-optimal internal consistency and should undergo further evaluation. The Swedish RCAC is recommended to be used in research settings for measurement of concerns related to fertility and parenthood in young women with cancer