Formation Flight of Earth Satellites on KAM Tori

Kolmogorov, Arnold and Moser (KAM) theory provides that orbits of satellites whose dynamics are representable by an integrable Hamiltonian plus a small, real perturbation lie on tori in phase space and remain on the KAM tori for all time, unless acted upon by a non-conservative force. A refined technique for constructing KAM tori for Earth-orbiting satellites is developed and implemented using numerically integrated orbital data for hypothetical satellites and involving methods of Fourier analysis and spectral decomposition. Definition of satellite formations on the KAM tori is performed and analyses conducted to investigate both constellations with large separations and clusters with small separations. Cluster formations with physical secular drift rates on the order of nanometers to micrometers per second are obtained. A brief discussion of effects of non-conservative forces (such as atmospheric drag) on KAM tori is given

Formation Flight of Earth Satellites on Low-Eccentricity KAM Tori

The problem of Earth satellite constellation and formation flight is investigated in the context of Kolmogorov-Arnold-Moser (KAM) theory. KAM tori are constructed utilizing Wiesel’s Low-Eccentricity Earth Satellite Theory, allowing numerical representation of the perturbed tori describing Earth orbits acted upon by geopotential perturbations as sets of Fourier series. A maneuvering strategy using the local linearization of the KAM tangent space is developed and applied, demonstrating the ability to maneuver onto and within desired torus surfaces. Constellation and formation design and maintenance on KAM tori are discussed, along with stability and maneuver error concerns. It is shown that placement of satellites on KAM tori results in virtually no secular relative motion in the full geopotential to within computational precision. The effects of maneuver magnitude errors are quantified in terms of a singular value decomposition of the modal system for several orbits of interest, introducing a statistical distribution in terms of torus angle drift rates due to mismatched energies. This distribution is then used to create expectations of the steady-state station-keeping costs, showing that these costs are driven by operational and spacecraft limitations, and not by limitations of the dynamics formulation. A non-optimal continuous control strategy for formations based on Control Lyapunov Functions is also outlined and demonstrated in the context of formation reconfiguration

C2Learn Learning Design for CER: C2Learn project deliverable no. D2.2.2

Deliverable 2.2.2 is the second of the two public versions of the document; the first was delivered in Month 9 and this one in Month 18 of the three-year project. Similarly to D2.2.1, and D2.1.1 Interim, this document explicates the key concepts and principles relating to C2 Learn’s Learning Design. Developed by the OU team working closely with feedback from other consortium members, it sets out the over-arching theoretical frame of the project which encompasses Creative Emotional Reasoning (Deliverable 2.1.2) and its practical application in relation to the project's learning approach. Deliverable 2.2.2 is structured in three parts. The first considers the overall goals of the C2Learn gameful design encompassing a 'playful' digital gaming and social networking environment or "Co-creativity space" (C2Space). The C2Space exemplifies students' and teachers 'playful' experiences or what they do: - free exploration of ideas, concepts, and 'shared' knowledge - opportunities to engage in creative problem-finding and problem-solving - opportunities to be assisted by the system (Creativity Assistants) The second part addresses what the C2Space looks like in practice utilising the affordances of currently available examples of game prototypes and digital tools. The third part documents what will occur next in how the consortium is progressing in designing the C2Space encompassing a digital gaming and social networking environment, with the learning goals in mind. Inevitably as the parts of C2Learn are developing in planned parallel development, the Learning Design will in reality remain a living document throughout the second half of the project, with terminology and processes being refined. This official version though sets down markers as to our expectation of the direction of such evolution

C2Learn Learning Design for CER: C2Learn project deliverable no. D2.2.2

Deliverable 2.2.2 is the second of the two public versions of the document; the first was delivered in Month 9 and this one in Month 18 of the three-year project. Similarly to D2.2.1, and D2.1.1 Interim, this document explicates the key concepts and principles relating to C2 Learn’s Learning Design. Developed by the OU team working closely with feedback from other consortium members, it sets out the over-arching theoretical frame of the project which encompasses Creative Emotional Reasoning (Deliverable 2.1.2) and its practical application in relation to the project's learning approach. Deliverable 2.2.2 is structured in three parts. The first considers the overall goals of the C2Learn gameful design encompassing a 'playful' digital gaming and social networking environment or "Co-creativity space" (C2Space). The C2Space exemplifies students' and teachers 'playful' experiences or what they do: - free exploration of ideas, concepts, and 'shared' knowledge - opportunities to engage in creative problem-finding and problem-solving - opportunities to be assisted by the system (Creativity Assistants) The second part addresses what the C2Space looks like in practice utilising the affordances of currently available examples of game prototypes and digital tools. The third part documents what will occur next in how the consortium is progressing in designing the C2Space encompassing a digital gaming and social networking environment, with the learning goals in mind. Inevitably as the parts of C2Learn are developing in planned parallel development, the Learning Design will in reality remain a living document throughout the second half of the project, with terminology and processes being refined. This official version though sets down markers as to our expectation of the direction of such evolution

LASP SmallSat Science Data Services

We are developing of a set of turn-key science data services for smallsat data management, processing, and hosting. Using cloud computing resources and existing infrastructure, we can rapidly deploy a modular data system for a mission or project. A basic system includes reliable, secure data storage, an API for fast data access worldwide, and a lightweight website with information about the mission and data API documentation. Optional add-ons include the ability to deploy science processing software using Docker containers, interactive web-based data displays, and archive deliveries to NASA or other archive facilities. The use of AWS CloudFormation templates to build new systems makes deployment and support straightforward and cost-efficient, and provides a consistent interface for both mission teams and science data users

A century-long record of plant evolution reconstructed from a coastal marsh seed bank

Evidence is mounting that climate-driven shifts in environmental conditions can elicit organismal evolution, yet there are sparingly few long-term records that document the tempo and progression of responses, particularly for plants capable of transforming ecosystems. In this study, we “resurrected” cohorts of a foundational coastal marsh sedge (Schoenoplectus americanus) from a time-stratified seed bank to reconstruct a century-long record of heritable variation in response to salinity exposure. Common-garden experiments revealed that S. americanus exhibits heritable variation in phenotypic traits and biomass-based measures of salinity tolerance. We found that responses to salinity exposure differed among the revived cohorts, with plants from the early 20th century exhibiting greater salinity tolerance than those from the mid to late 20th century. Fluctuations in salinity tolerance could reflect stochastic variation but a congruent record of genotypic variation points to the alternative possibility that the loss and gain in functionality are driven by selection, with comparisons to historical rainfall and paleosalinity records suggesting that selective pressures vary according to shifting estuarine conditions. Because salinity tolerance in S. americanus is tightly coupled to primary productivity and other vital ecosystem attributes, these findings indicate that organismal evolution merits further consideration as a factor shaping coastal marsh responses to climate change

Transforming practice: critical issues in equity, diversity and education

This Open University Reader critically examines educational issues of equity, diversity and social justice and how they are socially, culturally, economically rooted in educational practice across diverse educational settings. It highlights research, practice and pedagogies that challenge and transform educational experiences to support equity, social justice and inclusivity

Study on US wetland protection institution change

本文提出了分析湿地保护制度变迁的理论框架,使不同国家的湿地保护制度研究能在统一语境下比较。首先基于科学计量学和系统研究方法筛选出公众、科学、政府和法律为影响湿地保护制度变迁的四个关键要素,并依赖博弈论工具建立了分析美国湿地保护制度的理论架构。基于这一架构,本文对包括关键利益相关者、政策执行路径、政策工具和管理挑战等内容的美国湿地政策史进行了讨论。对美国湿地保护制度的演化进行了四阶断之划分:"西进运动"与全民开垦(1900年之前)、"水鸟保护"与公众参与(1900-1970年)、核心法律与科学研究(1971-1980年)和完善制度与新的挑战(1980年至今)。分析得出如下结论:在湿地保护制度中,公众是源头、科学是前提、有效的政府管治和将湿地保护的规则和与政策制度化是关键。通过借鉴美国湿地保护制度变迁研究,本文构建了湿地保护制度变迁的"竹节模式"经验性模型,揭示了各动因之间的作用机理。虽然美国湿地保护制度也面临着公众教育、科学定义和政府管辖权等挑战,但中国的湿地管理者与政策制定者仍可从美国湿地政策执行的历史背景中吸取经验。同时本文的理论分析结构也可为自然资源及管理策略的研究提供参考。The four key elements of public opinion,science,government and law were used to construct an empirical model built upon Game Theory. This theoretical framework,in which the wetland management policies of different countries can be compared,demonstrates the mechanism by which the four key elements interact to develop environmental policy and protect wetlands.Based on this empirical model,the history of wetland policies in the USA including key stakeholders,policy implementation approaches,policy instruments and management challenges were discussed. Evolution of the institution that protects American wetlands is broken down into four stages:Westward Movement and Reclamation(pre- 1900),Waterfowl Protection and Public Participation(1900- 1970),Core Laws and Scientific Research(1971- 1980)and Improved Institutions and New Challenges(1980- present). Wetland policies originate with public opinions and beliefs,scientific knowledge is a prerequisite for policy implementation and,lastly,effective governmental jurisdiction and institutionalization of wetland protection regulation and policy are critical. Although public education,scientific definition and governmental jurisdiction are challenging,Chinese wetland managers and policy makers can learn from the implementation of USA wetland policies. The analysis outlined in this paper is a template that other natural resource studies can follow when developing natural resource strategies.国家公派留学基金项目(2011-2013);; 康奈尔大学Jeffrey Sean Lehman基金项目(2012-2013

Evaluation of Microbiome-Host Relationships in the Zebrafish Gastrointestinal System Reveals Adaptive Immunity Is a Target of Bis(2-ethylhexyl) Phthalate (DEHP) Exposure

To improve physical characteristics of plastics such as flexibility and durability, producers enrich materials with phthalates such as di-2-(ethylhexyl) phthalate (DEHP). DEHP is a high production volume chemical associated with metabolic and immune disruption in animals and humans. To reveal mechanisms implicated in phthalate-related disruption in the gastrointestinal system, male and female zebrafish were fed DEHP (3 ppm) daily for two months. At the transcriptome level, DEHP significantly upregulated gene networks in the intestine associated with helper T cells' (Th1, Th2, and Th17) specific pathways. The activation of gene networks associated with adaptive immunity was linked to the suppression of networks for tight junction, gap junctional intercellular communication, and transmembrane transporters, all of which are precursors for impaired gut integrity and performance. On a class level, DEHP exposure increased Bacteroidia and Gammaproteobacteria and decreased Verrucomicrobiae in both the male and female gastrointestinal system. Further, in males there was a relative increase in Fusobacteriia and Betaproteobacteria and a relative decrease in Saccharibacteria. Predictive algorithms revealed that the functional shift in the microbiome community, and the metabolites they produce, act to modulate intestinal adaptive immunity. This finding suggests that the gut microbiota may contribute to the adverse effects of DEHP on the host by altering metabolites sensed by both intestinal and immune Th cells. Our results suggest that the microbiome-gut-immune axis can be modified by DEHP and emphasize the value of multiomics approaches to study microbiome-host interactions following chemical perturbations