Large spacecraft pointing and shape control

The overall objective of this program was the development of control algorithms that allow the concurrent operation of slewing, pointing, vibration, and shape control subsystems. This objective is important for near-term space surveillance missions that require the rapid retargeting and precise pointing of large flexible satellites. The success of these missions requires the design and concurrent operation of the various interacting control subsystems. There were two phases conducted: phase 1 was mathematical model development, and phase 2 was control development. The program is detailed and major conclusions given

A Rayleigh-Ritz approach to the synthesis of large structures with rotating flexible components

The equations of motion for large structures with rotating flexible components are derived by regarding the structure as an assemblage of substructures. Based on a stationarity principle for rotating structures, it is shown that each continuous or discrete substructure can be simulated by a suitable set of admissible functions or admissible vectors. This substructure synthesis approach provides a rational basis for truncating the number of degrees of freedom both of each substructure and of the assembled structure

Dynamic analysis of the long-term zonal earth energy budget experiment (LZEEBE) spacecraft

The motions of the flexible LZEEBE spacecraft after injection into a circular orbit were analyzed. The spacecraft consists of three spherical balloons connected to a central hub by three long flexible booms which lie in a plane such that the angle between any pair of booms is 120 degrees. The major torques acting on the spacecraft are gravity-gradient torques and torques due to solar radiation pressure acting on the balloons which have different reflective properties. A development of the equations of motion is presented. Computer simulations indicate that the spacecraft will have random motion, provided the injection into orbit does not create conditions favorable to gravity-gradient capture

Structural Dynamics, Stability, and Control of Helicopters

The dynamic synthesis of gyroscopic structures consisting of point-connected substructures is investigated. The objective is to develop a mathematical model capable of an adequate simulation of the modal characteristics of a helicopter using a minimum number of degrees of freedom. The basic approach is to regard the helicopter structure as an assemblage of flexible substructures. The variational equations for the perturbed motion about certain equilibrium solutions are derived. The discretized variational equations can be conveniently exhibited in matrix form, and a great deal of information about the system modal characteristics can be extracted from the coefficient matrices. The derivation of the variational equations requires a monumental amount of algebraic operations. To automate this task a symbolic manipulation program on a digital computer is developed

High-temperature Adhesive Development and Evaluation

High-temperature adhesive systems are evaluated for short and long-term stability at temperatures ranging from 232C to 427C. The resins selected for characterization include: NASA Langley developed polyphenylquinoxaline (PPQ), and commercially available polyimides (PI). The primary method of bond testing is single lap shear. The PPQ candidates are evaluated on 6A1-4V titanium adherends with chromic acid anodize and phosphate fluoride etch surface preparations. The remaining adhesives are evaluated on 15-5 PH stainless steel with a sulfuric acid anodize surface preparation. Preliminary data indicate that the PPQ adhesives tested have stability to 3000 hours at 450F with chromic acid anodize surface preparation. Additional studies are continuing to attempt to improve the PPQ's high-performance by formulating adhesive films with a boron filler and utilizing the phosphate fluoride surface preparation on titanium. Evaluation of the polyimide candidates on stainless-steel adherends indicates that the FM-35 (American Cyanamid), PMR-15 (U.S. Polymeric/Ferro), TRW partially fluorinated polyimide and NR 150B2S6X (DuPont) adhesives show sufficient promise to justify additional testing

A Vavilovian approach to discovering crop-associated microbes with potential to enhance plant immunity

Through active associations with a diverse community of largely non-pathogenic microbes, a plant may be thought of as possessing an “extended genotype,” an interactive cross-organismal genome with potential, exploitable implications for plant immunity. The successful enrichment of plant microbiomes with beneficial species has led to numerous commercial applications, and the hunt for new biocontrol organisms continues. Increasingly flexible and affordable sequencing technologies, supported by increasingly comprehensive taxonomic databases, make the characterization of non-model crop-associated microbiomes a widely accessible research method toward this end; and such studies are becoming more frequent. A summary of this emerging literature reveals, however, the need for a more systematic research lens in the face of what is already a metagenomics data deluge. Considering the processes and consequences of crop evolution and domestication, we assert that the judicious integration of in situ crop wild relatives into phytobiome research efforts presents a singularly powerful tool for separating signal from noise, thereby facilitating a more efficient means of identifying candidate plant-associated microbes with the potential for enhancing the immunity and fitness of crop species

Measurements of an ionizable constituent of low ionosphere using a Lyman-alpha source and blunt probe

Ionizable constituent density measurement of D region using Lyman-alpha source and blunt prob

The bearable lightness of being

How are philosophical questions about what kinds of things there are to be understood and how are they to be answered? This paper defends broadly Fregean answers to these questions. Ontological categories-such as object, property, and relation-are explained in terms of a prior logical categorization of expressions, as singular terms, predicates of varying degree and level, etc. Questions about what kinds of object, property, etc., there are are, on this approach, reduce to questions about truth and logical form: for example, the question whether there are numbers is the question whether there are true atomic statements in which expressions function as singular terms which, if they have reference at all, stand for numbers, and the question whether there are properties of a given type is a question about whether there are meaningful predicates of an appropriate degree and level. This approach is defended against the objection that it must be wrong because makes what there depend on us or our language. Some problems confronting the Fregean approach-including Frege's notorious paradox of the concept horse-are addressed. It is argued that the approach results in a modest and sober deflationary understanding of ontological commitments

Perceptions of physiotherapists towards research: a mixed methods study

OBJECTIVES: To explore the perceptions of physiotherapists towards the use of and participation in research. DESIGN: Concurrent mixed methods research, combining in-depth interviews with three questionnaires (demographics, Edmonton Research Orientation Survey, visual analogue scales for confidence and motivation to participate in research). SETTING: One physiotherapy department in a rehabilitation hospital, consisting of seven specialised areas. PARTICIPANTS: Twenty-five subjects {four men and 21 women, mean age 38 [standard deviation (SD) 11] years} who had been registered as a physiotherapist for a mean period of 15 (SD 10) years participated in this study. They were registered with the New Zealand Board of Physiotherapy, held a current practising certificate, and were working as a physiotherapist or physiotherapy/allied health manager at the hospital. MAIN OUTCOME MEASURE: The primary outcome measure was in-depth interviews and the secondary outcome measures were the three questionnaires. RESULTS: Physiotherapists were generally positive towards research, but struggled with the concept of research, the available literature and the time to commit to research. Individual confidence and orientation towards research seemed to influence how these barriers were perceived. CONCLUSION: This study showed that physiotherapists struggle to implement research in their daily practice and become involved in research. Changing physiotherapists' conceptions of research, making it more accessible and providing dedicated research time could facilitate increased involvement in the physiotherapy profession

GBS-SNP-CROP: a reference-optional pipeline for SNP discovery and plant germplasm characterization using variable length, paired-end genotyping-by-sequencing data

Background: With its simple library preparation and robust approach to genome reduction, genotyping-by-sequencing (GBS) is a flexible and cost-effective strategy for SNP discovery and genotyping, provided an appropriate reference genome is available. For resource-limited curation, research, and breeding programs of underutilized plant genetic resources, however, even low-depth references may not be within reach, despite declining sequencing costs. Such programs would find value in an open-source bioinformatics pipeline that can maximize GBS data usage and perform high-density SNP genotyping in the absence of a reference. Results: The GBS SNP-Calling Reference Optional Pipeline (GBS-SNP-CROP) developed and presented here adopts a clustering strategy to build a population-tailored “Mock Reference” from the same GBS data used for downstream SNP calling and genotyping. Designed for libraries of paired-end (PE) reads, GBS-SNP-CROP maximizes data usage by eliminating unnecessary data culling due to imposed read-length uniformity requirements. Using 150 bp PE reads from a GBS library of 48 accessions of tetraploid kiwiberry (Actinidia arguta), GBS-SNP-CROP yielded on average three times as many SNPs as TASSEL-GBS analyses (32 and 64 bp tag lengths) and over 18 times as many as TASSEL-UNEAK, with fewer genotyping errors in all cases, as evidenced by comparing the genotypic characterizations of biological replicates. Using the published reference genome of a related diploid species (A. chinensis), the reference-based version of GBS-SNP-CROP behaved similarly to TASSEL-GBS in terms of the number of SNPs called but had an improved read depth distribution and fewer genotyping errors. Our results also indicate that the sets of SNPs detected by the different pipelines above are largely orthogonal to one another; thus GBS-SNP-CROP may be used to augment the results of alternative analyses, whether or not a reference is available. Conclusions: By achieving high-density SNP genotyping in populations for which no reference genome is available, GBS-SNP-CROP is worth consideration by curators, researchers, and breeders of under-researched plant genetic resources. In cases where a reference is available, especially if from a related species or when the target population is particularly diverse, GBS-SNP-CROP may complement other reference-based pipelines by extracting more information per sequencing dollar spent. The current version of GBS-SNP-CROP is available at https://github.com/halelab/GBS-SNP-CROP.gi