Relative performance of 8.5-GHz and 32-GHz telemetry links on the basis of total data return per pass

The performance of X-band (8.5-GHz) and 32-GHz telemetry links is compared on the basis of the total data return per DSN station pass. Differences in spacecraft transmitter efficiency, transmit circuit loss, and transmitting antenna area efficiency and pointing loss are not considered in these calculations. Thus, the performance differentials calculated in this memo are those produced by a DSN 70-m station antenna gain and clear weather receiving system noise temperature and by weather. These calculations show that, assuming mechanical compensation of the DSN 70-m antenna for 32-GHz operation, a performance advantage for 32 GHz over X-band of 8.2 dB can be achieved for at least one DSN station location. Even if only Canberra and Madrid are used, a performance advantage of 7.7 dB can be obtained for at least one DSN station location. A system using a multiple beam feed (electronic compensation) should achieve similar results

Effect of interference on a binary communication channel using known signals

Sinusoidal and Gaussian interference effects on binary communication channel using known signals in white random nois

Use of acrylic sheet molds for elastomeric products

Molds constructed of acrylic sheet are more easily machined than metal, are transparent to ensure complete filling during injection, and have smooth surfaces free of contamination. Technique eliminates flashing on molded parts and mold release agents

THE IMPACT OF RECESS ON CHILDREN’S SOCIAL/EMOTIONAL DEVELOPMENT, CLASSROOM BEHAVIORS, AND TEACHER PEDAGOGY: AN EXPLORATORY CASE STUDY OF ELEMENTARY SCHOOL STUDENTS AT PLAY

Recent reports have stated that schools across the United States have been reducing recess so that more time can be spent in the classroom. There has been little research to prove that more time in the classroom and less recess equals better academic outcomes for children. The purpose of this study was to discover the impact recess on elementary school students’ social competencies, emotional development, classroom behaviors, and teachers’ pedagogy and instructional practices. The elementary school is in a suburban district in United States. It has a population of 457 students. The population is culturally diverse with 10% of the students receiving English as a Second Language. The percentage of students with disabilities is 16%, and 43% of students are socioeconomically disadvantaged. Twelve teachers participated in interviews. Students were observed during various recess breaks over five sessions. The researcher took notes regarding social interactions, communications, and play behaviors. The sample size for assessing classroom behaviors prior to and following recess consisted of 30 first-grade students. The results of this study validate the value of recess and play experiences for children. The study of classroom behaviors exposed the reality that students were more focused and less fidgety following a recess break. Teachers’ responses revealed that recess was valuable for students’ social, emotional, academic, and physical development. It also revealed that teachers feel better about their pedagogy as a result of being permitted to implement recess breaks in between sustained instruction. The literature review provided evidence that block time and more time in the classroom with minimal breaks for students is poor practice and a detriment to proper child development. Research has indicated that recess is essential for children’s social, emotional, creative, and cognitive well-being (American Academy of Pediatrics, 2013; Barros, Silver, & Stein, 2009). Children’s experience, however, varies widely from school to school. Future research should focus on the differences in recess mandates from state to state and the social, emotional, and academic outcomes of children

Lessons learnt from CCAFS - 10 years scaling climate-smart agriculture: Insights from the review of CCAFS scaling activities, 2019

This Info Note is based on the insights of the CCAFS core team, lessons shared by project leaders via the MARLO, and interviewees from the following CGIAR centers and partners: Bioversity, CIAT, CIMMYT, CIP, ICARDA, ICRAF, ICRISAT, IFPRI, IITA, ILRI, IRRI, IWMI, WorldFish, and WUR. After ten years’ implementation, lessons learnt of practitioners validate two concepts that CCAFS has used and developed for scaling CSA: the Three-Thirds Principle for effective science-policy engagement (Dinesh et al. 2018) applies widely for scaling CSA, when adding the element of iterative learning; and the LearningWheel with 11 cornerstones for effective research and development to improve livelihoods and the environment (Campbell et al. 2006) is a useful framework for managing not only R4D, but also scaling processes

The Scaling Mindset – Shifting from Problems to Solutions. Insights from the Review of CCAFS Scaling Activities, 2019

In the frame of the review of CCAFS scaling activities in 2019, 21 project leaders and –implementers were interviewed about their scaling processes, touching a series of aspects that had been identified as crucial and/or critical by earlier research. Results were analysed with a systemic approach, to draw organisational learnings. The findings were validated with CCAFS core team during their Scaling Workshop in Madrid, May 2019, in which the Core Team also prioritized its programmatic areas of response. This working paper captures the main insights and learnings from both the interviews on project level, followed by the results’ analysis. It then summarized the Core Team workshop’s main discussion points and shortly outlines the programmatic areas of response that CCAFS identified. The learnings and insights on the realities of scaling agricultural innovations presented in this working paper can provide a rich basis for further synthesis and/or deeper research on the different aspects of innovation development and scaling

Glaciers and Global Warming

Ice core and mass balance studies from glaciers, ice caps and ice sheets constitute an ideal medium for monitoring and studying present and past environmental change and, as such, make a valuable contribution to the present debate over anthropogenic forcing of climate. Data derived from 32 years of measurements in the Canadian Arctic show no significant trends in glacier mass balance, ice melt, or snow accumulation, although the mass balance continues to be slightly negative. Models suggest that industrial aerosol loading of the atmosphere should add to the warming effect of greenhouse gases. However, we have found a sharp increase in the concentration of industrial pollutants in snow deposited since the early 1950's which makes the trendless nature of our various time series surprising. Spatial differences in the nature of climatic change may account for the lack of trend in the Queen Elizabeth Islands but encourages similar investigations to this study elsewhere in the circumpolar region. A global warming trend over the past 150 years has been demonstrated from instrumental data and is evident in our ice cores. However, the ice core data and glacier geometry changes in the Canadian Arctic suggest the Arctic warming is more pronounced in summer than winter. The same warming trend is not unique when viewed in the context of changes over the past 10,000 or 100,000 years. This suggests the 150-year trend is part of the natural climate variability.L'analyse des carottes de glace et les mesures du bilan de masse des glaciers, des calottes glaciaires et des indlandsis permettent de déceler des changements environnementaux survenus dans le passé tout en permettant de surveiller les changements actuels. Ces études peuvent contribuer au débat portant sur les conséquences physiques de l'activité humaine sur le climat. Trente-deux ans de données accumulées sur les bilans de masse, la fonte et l'accumulation de neige sur les glaciers de l'Arctique canadien ne montrent aucune tendance significative, bien que les bilans de masse soient quelque peu négatifs. Les modèles prévoient pourtant un réchauffement provoqué par l'apport accru d'aérosols d'origine industrielle. Nous observons une forte augmentation des concentrations de polluants industriels dans la neige déposée depuis les années cinquante, ce qui rend l'absence d'une tendance dans nos observations encore plus surprenante. L'absence d'indices sur un réchauffement dans l'archipel de la Reine-Élisabeth est peut-être simplement attribuable aux variations régionales du changement climatique, un phénomène qui devrait être étudié dans d'autres régions circumpolaires. Depuis 150 ans, une tendance vers un réchauffement à l'échelle planétaire a été observée à partir des données recueillies par les instruments ainsi que dans les carottes de glace. Les données obtenues à partir des carottes de glace et de la géométrie des glaciers semblent indiquer que ce réchauffement est plus marqué l'été que l'hiver. La tendance au réchauffement n'est cependant pas exceptionnelle dans le contexte des 10 000 ou 100 000 dernières années; elle pourrait rendre compte de la variabilité naturelle du climat.Die Analyse von Eisbohrkernen und das Studium der Bilanz der Masse von Gletschem, Eiskappen und Eisdecken sind ein ausgezeichnetes Mittel, um gegenwàrtige und vergangene Umweltverânderungen zu kontrollieren und zu studieren. So kann ein wertvoller Beitrag zur gegenwàrtigen Débatte ùber den Einfluft der menschlichen Aktivitàt auf das Klima geleistet werden. Die Daten, die man durch Messungen ùber 32 Jahre in der kanadischen Arktis gewann, zeigen keine erhebliche Tendenz in der Bilanz der Gletschermasse, Eisschmelze oder Schneeakkumulation, auch wenn die Bilanz der Masse weiter leicht negativ ist. Die Modelle lassen vermuten, da8 die Ladung der Atmosphère mit Industrieaerosolen zum Treibhauseffekt beitrâgt. Jedoch haben wir einen starken Anstieg in der Konzentration industrieller Schadstoffe in dem seit den frùhen fùnfziger Jahren angesammelten Schnee, was das Fehlen einer Tendenz in unseren verschiedenen Zeitabschnitten ùberraschend macht. Ôrtliche Unterschiede in der Natur der Klimawechsel mogen fur das Fehlen einer Tendenz auf den Queen Elizabeth lnseln verantwortlich sein, doch dieser Untersuchung vergleichbare Studien sollten andernorts in der Region um den PoI durchgefùhrt werden. Eine globale Erwàrmungstendenz ùber die vergangenen 150 Jahre konnte mittels instrumenteller Messungen festgestellt werden und ist in unseren Eisbohrkernen sichtbar. Indessen lassen die Eisbohrkerndaten und Verànderungen in der Géométrie der Gletscher in der kanadischen Arktis annehmen, daft die Erwàrmung der Arktis im Sommer deutlicher ist als im Winter. Dièse Erwàrmungstendenz ist nicht auftergewôhnlich, wenn man sie im Kontext der Verânderungen in den letzten 10,000 oder 100,000 Jahren sieht. Die 150 Jahre-Tendenz ist wohl Teil der natùrlichen Klimavariabilitàt

Discrete element models of soil-geogrid interaction

Geogrids are the geosynthetics of choice for soil reinforcement applications. To evaluate the efficiency of geogrid reinforcement, several methods are used including field tests, laboratory tests and numerical modeling. Field studies consume long period of time and conducting these investigations may become highly expensive because of the need for real-size structures. Laboratory studies present also significant difficulties: large-size testing machines are required to accommodate realistic geogrid designs. The discrete element method (DEM) may be used as a complementary tool to extend physical testing databases at lower cost. Discrete element models do not require complex constitutive formulations and may be fed with particle scale data (size, strength, shape) thus reducing the number offree calibration parameters. Discrete element models also are well suited to problems in which large displacements are present, such as geogrid pullout. This paper reviews the different approaches followed to model soil-geogrid interaction in DEM and presents preliminary results from pull-out conditions.Peer ReviewedPostprint (author's final draft