Experimental methodologies to support aircraft icing analysis

The experimental methodologies are illustrated by graphs, charts and line drawings. Typical ultrasonic echo signals for dry and wet ice growth, ice accretion rates for various tunnel configurations, the experimental configuration for flight tests of the ultrasonic measuring system and heat balance models used to predict ice growth are among the topics that are illustrated and briefly discussed

Experimental measurements of heat transfer from an iced surface during artificial and natural cloud icing conditions

The heat transfer behavior of accreting ice surfaces in natural (flight test) and simulated (wind tunnel) cloud icing conditions were studied. Observations of wet and dry ice growth regimes as measured by ultrasonic pulse echo techniques were made. Observed wet and dry ice growth regimes at the stagnation point of a cylinder were compared with those predicted using a quasi steady state heat balance model. A series of heat transfer coefficients were employed by the model to infer the local heat transfer behavior of the actual ice surfaces. The heat transfer in the stagnation region was generally inferred to be higher in wind tunnel icing tests than in natural flight icing conditions

Ultrasonic techniques for aircraft ice accretion measurement

Results of tests to measure ice growth in natural (flight) and artificial (icing wind tunnel) icing conditions are presented. Ice thickness is measured using an ultrasonic pulse-echo technique. Two icing regimes, wet and dry ice growth, are identified and the unique ultrasonic signal characteristics associated with these different types of ice growth are described. Ultrasonic measurements of ice growth on cylinders and airfoils exposed to artificial and natural icing conditions are presented. An accuracy of plus or minus 0.5 mm is achieved for ice thickness measurement using the pulse-echo technique. The performance of two-probe type ice detectors is compared to the surface mounted ultrasonic system. The ultrasonically measured ice accretion rates and ice surface condition (wet or dry) are used to compare the heat transfer characteristics for flight and icing wind tunnel environments. In general the heat transfer coefficient is inferred to be higher in the wind tunnel environment, not likely due to higher freestream turbulence levels. Finally, preliminary results of tests to measure ice growth on airfoil using an array of ultrasonic transducers are described. Ice profiles obtained during flight in natural icing conditions are shown and compared with mechanical and stereo image measurements

Family Literacy Environment and Early Literacy Development

A battery of reading-related and reading measures was used to select samples of good (N = 30) and poor readers (N = 19) in Grade 1. Parents of these children completed a questionnaire about current and preschool home literacy practices and socio-economic status (SES). The 2 groups were compared with t tests and in a discriminant analysis. The t tests indicated that the homes of the good and poor readers differed in many characteristics, including several aspects of home literacy, numbers of books in the home, and mothers’ education. The 2 best unique discriminators of the groups were parents’ teaching of letters and mothers’ education. The limitations of the study and the implications are discussed

Theory-Based Prediction of Early Reading

This article presents a theory of the cognitive processes involved in learning to read and examines the degree to which measures derived from this theory are able to predict success in reading. Measures were selected to address five phonological processing constructs (naming speed, memory, rhyming, phonological synthesis, and phonological analysis), letter knowledge, and the ability to pronounce words by analyzing them into smaller parts (decoding). Measures of these constructs and several measures of reading achievement were administered to an initial sample of 161 kindergarten children and then readministered to as many of the same children as possible in grades 1 and 2; in grade 3 the reading achievement tests were administered. Principal components analyses were used to derive factor scores for the phonological constructs in kindergarten and grades 1 and 2. In grade 2 five factors were found, but in kindergarten and grade 1 the phonological synthesis and analysis measures formed one phonological awareness factor. The factor scores, letter knowledge, decoding, and the reading achievement scores for each grade were used as predictors of reading achievement in subsequent grades in a series of hierarchical regression analyses. Results supported the proposed theory, with phonological awareness (or analysis), naming speed, and letter recognition being the most frequent significant predictors and R2s ranging from .69 to .89. The constructs identified in the theory are argued to be important targets for both assessment and instruction. The value of theoretical models of achievement is discussed.Cet article présente une théorie sur les processus cognitifs impliqués dans l'apprentissage de la lecture et étudie à quel point les mesures qui en découlent peuvent prédire le succès dans la lecture. Les mesures ont été sélectionnées pour refléter cinq éléments de traitement phonologique (vitesse de dénomination, mémoire, rime, synthèse phonologique et analyse phonologique), la connaissance des graphèmes et la capacité de prononcer les mots en les découpant en plus petites unités (décodage). On a mesuré ces cinq éléments et, à plusieurs reprises, le rendement en lecture d'un échantillon initial de 161 enfants à la maternelle. Plus tard, on a refait l'analyse avec autant de ces enfants que possible alors qu'ils étaient en première et deuxième années. Quand ils sont arrivés en troisième année, on a administré des tests de rendement en lecture. Des analyses de composantes principales ont servi dans la dérivation des scores factoriels pour les éléments phonologiques à la maternelle et dans les deux premières années. Chez les enfants en deuxième année, on a retrouvé cinq facteurs, mais chez ceux â la maternelle et en première année, les mesures de synthèse et d'analyse phonologiques constituaient un facteur de reconnaissance phonologique. Les scores factoriels, la connaissance des graphèmes, le décodage et les résultats des tests de rendement en lecture pour chaque niveau scolaire ont servi de valeurs prédictives du rendement en lecture dans les années scolaires subséquentes pour une série d'analyses de régression hiérarchicales. Les résultats appuient la théorie proposée, les valeurs prédictives les plus significatives étant la reconnaissance (ou l'analyse) phonologique et la connaissance des graphèmes. Les R2 va-riaient entre 0,69 et 0,89. Il est proposé que les éléments identifiés par la théorie représentent des cibles importants tant pour l'évaluation que pour l'enseignement. On discute de la valeur des modèles théoriques de rendement

Which lipid measurement should we monitor? An analysis of the LIPID study

OBJECTIVES: To evaluate the optimal lipid to measure in monitoring patients, we assessed three factors that influence the choice of monitoring tests: (1) clinical validity; (2) responsiveness to therapy changes and (3) the size of the long-term ‘signal-to-noise’ ratio. DESIGN: Longitudinal analyses of repeated lipid measurement over 5 years. SETTING: Subsidiary analysis of a Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) study—a clinical trial in Australia, New Zealand and Finland. PARTICIPANTS: 9014 patients aged 31–75 years with previous acute coronary syndromes. INTERVENTIONS: Patients were randomly assigned to 40 mg daily pravastatin or placebo. PRIMARY AND SECONDARY OUTCOME MEASURES: We used data on serial lipid measurements—at randomisation, 6 months and 12 months, and then annually to 5 years—of total cholesterol; low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol and their ratios; triglycerides; and apolipoproteins A and B and their ratio and their ability to predict coronary events. RESULTS: All the lipid measures were statistically significantly associated with future coronary events, but the associations between each of the three ratio measures (total or LDL cholesterol to HDL cholesterol, and apolipoprotein B to apolipoprotein A1) and the time to a coronary event were better than those for any of the single lipid measures. The two cholesterol ratios also ranked highly for the long-term signal-to-noise ratios. However, LDL cholesterol and non-HDL cholesterol showed the most responsiveness to treatment change. CONCLUSIONS: Lipid monitoring is increasingly common, but current guidelines vary. No single measure was best on all three criteria. Total cholesterol did not rank highly on any single criterion. However, measurements based on cholesterol subfractions—non-HDL cholesterol (total cholesterol minus HDL cholesterol) and the two ratios—appeared superior to total cholesterol or any of the apolipoprotein options. Guidelines should consider using non-HDL cholesterol or a ratio measure for initial treatment decisions and subsequent monitoring

Phonological Awareness and Listening Comprehension Among Chinese English-Immersion Students

This study investigates the relationship between English listening comprehension and English and Chinese phonological awareness (PA), and the cross-linguistic transfer of PA in 48 Grade 2 and 47 Grade 4 Chinese English-immersion students. The results of the study indicate a correlation between English PA and English listening comprehension. English listening comprehension had a significant effect on English PA in both grades; this effect is evident after considering Chinese PA, but only in Grade 4. A similar pattern is found for the effect of English PA on English listening comprehension. Only weak evidence exists pertaining to a connection between cross-linguistic transfer from Chinese PA (L1) to English listening comprehension (L2)

In-flight measurement of ice growth on an airfoil using an array of ultrasonic transducers

Results of preliminary tests to measure ice growth on an airfoil during flight icing conditions are presented. Ultrasonic pulse echo measurements of ice thickness are obtained from an array of eight ultrasonic transducers mounted flush with the leading edge of the airfoil. These thickness measurements are used to document the evolution of the ice shape during the encounter in the form of successive ice profiles. Results from 3 research flights are presented and discussed. The accuracy of the ultrasonic measurements is found to be within 0.5 mm of mechanical and stereo photograph measurements of the ice accretion

Measurement of ice accretion using ultrasonic pulse echo techniques

Many figures are given to illustrate the measurement of ice deposition using ultrasonic pulse echo techniques. The basic concept is to measure the thickness of the ice by relating the pulse echo time to the speed of sound. The measurements are made in an icing research tunnel (IRT), where echo patterns are videotaped during icing exposures under a variety of conditions. Typical echo patterns for different types of ice are illustrated. A table summarizing the icing rates measured in the IRT, along with the presence or absence of surface water is also given