Stability Improvement of Motion of a Rotor With an Active Control Method

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The so-called phase-locked delayed feedback control method is applied to a Jeffcott rotor supported by rolling-element bearings but with negative damping and then to the same rotor supported hy journal bear ings, to improve the stability of motion of the rotor. The control parameters arc determined in terms of the characteristic equation of the controlled rotor. The results of numerical simulations show that the stability of motion of the rotor is greatly improved with the help of the phase-locked delayed feedback control method

Heatshield for Extreme Entry Environment Technology (HEEET) for Missions to Saturn and Beyond

This poster provides an overview of the requirements, design, development and testing of the 3D Woven TPS being developed under NASAs Heatshield for Extreme Entry Environment Technology (HEEET) project. Under this current program, NASA is working to develop a Thermal Protection System (TPS) capable of surviving entry into Saturn. A primary goal of the project is to build and test an Engineering Test Unit (ETU) to establish a Technical Readiness Level (TRL) of 6 for this technology by 2017

Conformal Ablative Thermal Protection System for Planetary and Human Exploration Missions: Overview of the Technology Maturation Efforts Funded by NASA's Game Changing Development Program

The Office of Chief Technologist (OCT), NASA has identified the need for research and technology development in part from NASA's Strategic Goal 3.3 of the NASA Strategic Plan to develop and demonstrate the critical technologies that will make NASA's exploration, science, and discovery missions more affordable and more capable. Furthermore, the Game Changing Development Program (GCDP) is a primary avenue to achieve the Agency's 2011 strategic goal to "Create the innovative new space technologies for our exploration, science, and economic future." In addition, recently released "NASA space Technology Roadmaps and Priorities," by the National Research Council (NRC) of the National Academy of Sciences stresses the need for NASA to invest in the very near term in specific EDL technologies. The report points out the following challenges (Page 2-38 of the pre-publication copy released on February 1, 2012): Mass to Surface: Develop the ability to deliver more payload to the destination. NASA's future missions will require ever-greater mass delivery capability in order to place scientifically significant instrument packages on distant bodies of interest, to facilitate sample returns from bodies of interest, and to enable human exploration of planets such as Mars. As the maximum mass that can be delivered to an entry interface is fixed for a given launch system and trajectory design, the mass delivered to the surface will require reduction in spacecraft structural mass; more efficient, lighter thermal protection systems; more efficient lighter propulsion systems; and lighter, more efficient deceleration systems. Surface Access: Increase the ability to land at a variety of planetary locales and at a variety of times. Access to specific sites can be achieved via landing at a specific location (s) or transit from a single designated landing location, but it is currently infeasible to transit long distances and through extremely rugged terrain, requiring landing close to the site of interest. The entry environment is not always guaranteed with a direct entry, and improving the entry system's robustness to a variety of environmental conditions could aid in reaching more varied landing sites.

Classes of fast and specific search mechanisms for proteins on DNA

Problems of search and recognition appear over different scales in biological systems. In this review we focus on the challenges posed by interactions between proteins, in particular transcription factors, and DNA and possible mechanisms which allow for a fast and selective target location. Initially we argue that DNA-binding proteins can be classified, broadly, into three distinct classes which we illustrate using experimental data. Each class calls for a different search process and we discuss the possible application of different search mechanisms proposed over the years to each class. The main thrust of this review is a new mechanism which is based on barrier discrimination. We introduce the model and analyze in detail its consequences. It is shown that this mechanism applies to all classes of transcription factors and can lead to a fast and specific search. Moreover, it is shown that the mechanism has interesting transient features which allow for stability at the target despite rapid binding and unbinding of the transcription factor from the target.Comment: 65 pages, 23 figure

Adaptable, Deployable Entry and Placement Technology (ADEPT) Overview of FY15 Accomplishments

ADEPT is an atmospheric entry architecture for missions to most planetary bodies with atmospheres: Current Technology development project funded under STMD Game Changing Development Program (FY12 start); stowed inside the launch vehicle shroud and deployed in space prior to entry; low ballistic coefficient (less than 50 kilograms per square meter) provides a benign deceleration and thermal environment to the payload; High-temperature ribs support three dimensional woven carbon fabric to generate drag and withstand high heating

Aplicación del método de la madurez para la estimación del plazo de descimbrado de forjados construidos con sistemas industrializados

El presente artículo propone una metodología para la estimación del plazo de descimbrado de forjados construidos con sistemas industrializados. Para esto, se realiza un estudio de madurez de hormigones usados en este tipo de construcción. Con el fin de construir la curva de madurez en laboratorio se implementa la metodología descrita en la ASTM C1074, calculando la energía de activación por los tres métodos propuestos y midiendo el historial térmico de las mezclas a una temperatura controlada. Por último, se realiza la instrumentación en obra de una placa donde se estima la edad de descimbrado. Se ha observado que el tiempo de fraguado final no es un parámetro recomendable para descimbrar las placas, como lo recomiendan las productoras de hormigón en Colombia. La edad de descimbrado obtenida es mayor a la del tiempo de fraguado final, habiendo una diferencia de hasta 11 horas en el caso más crítico.Castro-Garrido, M.; López-Garzón, M.; Alvarado Vargas, YA.; Castaño Tabares, JO.; Gasch, I. (2016). Aplicación del método de la madurez para la estimación del plazo de descimbrado de forjados construidos con sistemas industrializados. Informes de la Construcción. 68(541). doi:10.3989/ic.14.105Se1316854

Heatshield for Extreme Entry Environment Technology (HEEET) - Enabling Missions Beyond Heritage Carbon Phenolic

This poster provides an overview of the requirements, design, development and testing of the 3D Woven TPS being developed under NASA's Heatshield for Extreme Entry Environment Technology (HEEET) project. Under this current program, NASA is working to develop a Thermal Protection System (TPS) capable of surviving entry into Venus or Saturn. A primary goal of the project is to build and test an Engineering Test Unit (ETU) to establish a Technical Readiness Level (TRL) of 6 for this technology by 2017

Identification of RNA recognition elements in the Saccharomyces cerevisiae transcriptome

Post-transcriptional regulation of gene expression, including mRNA localization, translation and decay, is ubiquitous yet still largely unexplored. How is the post-transcriptional regulatory program of each mRNA encoded in its sequence? Hundreds of specific RNA-binding proteins (RBPs) appear to play roles in mediating the post-transcriptional regulatory program, akin to the roles of specific DNA-binding proteins in transcription. As a step toward decoding the regulatory programs encoded in each mRNA, we focused on specific mRNA–protein interactions. We computationally analyzed the sequences of Saccharomyces cerevisiae mRNAs bound in vivo by 29 specific RBPs, identifying eight novel candidate motifs and confirming or extending six earlier reported recognition elements. Biochemical selections for RNA sequences selectively recognized by 12 yeast RBPs yielded novel motifs bound by Pin4, Nsr1, Hrb1, Gbp2, Sgn1 and Mrn1, and recovered the known recognition elements for Puf3, She2, Vts1 and Whi3. Most of the RNA elements we uncovered were associated with coherent mRNA expression changes and were significantly conserved in related yeasts, supporting their functional importance and suggesting that the corresponding RNA–protein interactions are evolutionarily conserved

Heatshield for Extreme Entry Environment Technology (HEEET) Enabling Missions Beyond Heritage Carbon Phenolic

Future NASA robotic missions utilizing an entry system into Venus and the outer planets, results in extremely high entry conditions that exceed the capabilities of state of the art low to mid density ablators such as PICA or AVCOAT. Previously, mission planners had to assume the use of fully dense carbon phenolic heatshields similar to what was flown on Pioneer Venus or Galileo. Carbon phenolic is a robust TPS material, however, its high density and relatively high thermal conductivity constrain mission planners to steep entries, with high heat fluxes and pressures and short entry durations. The high entry conditions pose challenges for certification in existing ground based test facilities and the longer-term sustainability of CP will continue to pose challenges. NASA has decided to invest in new technology development rather than invest in reviving carbon phenolic. The HEEET project, funded by STMD is maturing a game changing Woven Thermal Protection System technology. HEEET is a capability development project and is not tied to a single mission or destination, therefore, it is challenging to complete ground testing needed to demonstrate a capability that is much broader than any single mission or destination would require. This presentation will status HEEET progress. Near term infusion target for HEEET is the upcoming New Frontiers (NF-4) class of competitively selected Science Mission Directorate (SMD) missions for which it is incentivized