Degradation of a Multilayer Insulation Due to a Seam and a Penetration

The degradation of the thermal performance of a multilayer insulation due to the presence of a seam and a penetration was studied. The multilayer insulation had 30 aluminized Mylar radiation shields with silk net spacers. The seam, an offset butt joint, caused a heat input of 0.169 watt per meter in addition to the basic insulation thermal performance of 0.388 watt per square meter obtained before the installation of the butt joint. The penetration, a fiberglass tank support strut, provided a heat input (including the degradation of the insulation) of 0.543 watt in addition to the basic insulation thermal performance of 0.452 watt per square meter obtained before the penetration

Development of ultrahigh strength, low density, aluminum plate composites progress report no. 16, oct. 1 - nov. 1, 1964

High strength reinforced aluminum alloy and composite aluminum sandwich plate for space and launch vehicle

Transient thermal performance of multilayer insulation systems during simulated ascent pressure decay

Transient thermal performance of multilayer insulation systems with liquid hydrogen tank during simulated Saturn 5 ascent pressure deca

Comparison of reusable insulation systems for cryogenically-tanked earth-based space vehicles

Three reusable insulation systems concepts were developed for use with cryogenic tanks of earth-based space vehicles. Two concepts utilized double-goldized Kapton (DGK) or double-aluminized Mylar (DAM) multilayer insulation (MLI), while the third utilized a hollow-glass-microsphere, loadbearing insulation (LBI). Thermal performance measurements were made under space-hold (vacuum) conditions for insulating warm boundary temperatures of approximately 291 K. The resulting effective thermal conductivity was approximately 0.00008 W/m-K (W = weight,Kg; m = measured; K = temperature) for the MLI systems (liquid hydrogen test results) and 0.00054 W/m-K for the LBI system (liquid nitrogen test results corrected to liquid hydrogen temperature)

Development of improved-durability plasma sprayed ceramic coatings for gas turbine engines

As part of a NASA program to reduce fuel consumption of current commercial aircraft engines, methods were investigated for improving the durability of plasma sprayed ceramic coatings for use on vane platforms in the JT9D turbofan engine. Increased durability concepts under evaluation include use of improved strain tolerant microstructures and control of the substrate temperature during coating application. Initial burner rig tests conducted at temperatures of 1010 C (1850 F) indicate that improvements in cyclic life greater than 20:1 over previous ceramic coating systems were achieved. Three plasma sprayed coating systems applied to first stage vane platforms in the high pressure turbine were subjected to a 100-cycle JT9D engine endurance test with only minor damage occurring to the coatings

EXPERIMENTAL INVESTIGATION OF THE SLOSH-DAMPING EFFECTIVENESS OF POSITIVE-EXPULSION BAGS AND DIAPHRAGMS IN SPHERICAL TANKS

Slosh damping effectiveness of positive expulsion bags and diaphragms in spherical tank

Children with Dyslexia: Spelling as a Constraint on Writing Development

Background. Developmental dyslexia is characterised as a specific learning difficulty with written language: namely, reading and spelling. To date, little research has been conducted to examine the role of spelling when writing and, in particular, in the writing of young children with dyslexia. This is surprising when considering that spelling is an active process used when transcribing written text. Thus, this thesis aimed to investigate the impact of spelling ability in four areas: the quality of the written compositions produced, spelling error analyses, vocabulary choice when writing, and handwriting execution. Method. Thirty-one children with dyslexia (15 boys, 16 girls; 9 years) were compared to two typically developing groups: the first matched by age and the second by spelling-ability. Participants completed tasks that assessed cognitive ability, spelling, reading, working memory, narrative writing, vocabulary level, motor skill, and handwriting performance. A digital writing tablet was used to record and identify the temporal characteristics of handwriting. Results. Children with dyslexia scored significantly below their peers for written text quality, wrote less overall, and demonstrated a higher number of phonetically and orthographically inaccurate spelling errors. Limited vocabulary choices and a more disfluent handwriting profile were characteristics of the writing by children with dyslexia. These children with dyslexia did not have motor difficulties and demonstrated that handwriting execution speed was in fact similar to their peers. Rather, children with dyslexia paused more frequently before misspellings and within-words, a similar pattern to the younger spelling-ability matches. Spelling ability was found to predict a large proportion of variance in handwriting speed, written vocabulary choice, and the quality of the written text produced by children with dyslexia. Conclusions. A new model of the interacting writing processes was proposed, emphasising the importance of acquiring strong foundations in proficient spelling for writing to progress. The proposed model relates to atypical and typical development. The findings are related to theories of dyslexia and avenues for future research are discussed in relation to expanding the new writing model

How much does style matter? Investigating legibility and speed of writing in Year 2 children

Efficient transcription skills underpin the writing process and have been shown to explain variance in both quality and quantity of written composition. Although there is broad consensus that the development of legible handwriting produced at sufficient speed is a priority in the early years of school, there is much debate about how this is best achieved. The present study compared the performance of two groups of Year 2 pupils, with contrasting instructional regimes and experience, across a range of tasks assessing writing speed and legibility, and spelling. Participants from School M (n=74) had initially been taught to form individual (manuscript) letters and had only been introduced to joining at the end of Year 1; while participants from School CC (n=39) had been taught to form letters with entry strokes from the baseline since school-entry and a continuous cursive style had been promoted throughout. Results showed that participants from School CC were more productive than those from School M; however, participants at School M produced text that was more legible. The evidence regarding the merits of particular regimes and styles is not conclusive, nor is a secure relationship between handwriting style and spelling established. However, for both settings, findings provide useful implications for practice