1,265 research outputs found

    Design of a candidate flutter suppression control law for DAST ARW-2

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    A control law is developed to suppress symmetric flutter for a mathematical model of an aeroelastic research vehicle. An implementable control law is attained by including modified LQC (Linear Quadratic Gaussian) design techniques, controller order reduction, and gain scheduling. An alternate (complementary) design approach is illustrated for one flight condition wherein nongradient-based constrained optimization techniques are applied to maximize controller robustness

    Fitting aerodynamic forces in the Laplace domain: An application of a nonlinear nongradient technique to multilevel constrained optimization

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    A technique which employs both linear and nonlinear methods in a multilevel optimization structure to best approximate generalized unsteady aerodynamic forces for arbitrary motion is described. Optimum selection of free parameters is made in a rational function approximation of the aerodynamic forces in the Laplace domain such that a best fit is obtained, in a least squares sense, to tabular data for purely oscillatory motion. The multilevel structure and the corresponding formulation of the objective models are presented which separate the reduction of the fit error into linear and nonlinear problems, thus enabling the use of linear methods where practical. Certain equality and inequality constraints that may be imposed are identified; a brief description of the nongradient, nonlinear optimizer which is used is given; and results which illustrate application of the method are presented

    Control law design to meet constraints using SYNPAC-synthesis package for active controls

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    Major features of SYNPAC (Synthesis Package for Active Controls) are described. SYNPAC employs constrained optimization techniques which allow explicit inclusion of design criteria (constraints) in the control law design process. Interrelationships are indicated between this constrained optimization approach, classical and linear quadratic Gaussian design techniques. Results are presented that were obtained by applying SYNPAC to the design of a combined stability augmentation/gust load alleviation control law for the DAST ARW-2

    Application of optimization techniques to the design of a flutter suppression control law for the DAST ARW-2

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    The design of a candidate flutter suppression (FS) control law for the symmetric degrees of freedom for the DAST ARW-2 aircraft is discussed. The results illustrate the application of several currently employed control law design techniques. Subsequent designs, obtained as the mathematical model of the ARW-2 is updated, are expected to employ similar methods and to provide a control law whose performance will be flight tested. This study represents one of the steps necessary to provide an assessment of the validity of applying current control law synthesis and analysis techniques in the design of actively controlled aircraft. Mathematical models employed in the control law design and evaluation phases are described. The control problem is specified by presenting the flutter boundary predicted for the uncontrolled aircraft and by defining objectives and constraints that the controller should satisfy. A full-order controller is obtained by using Linear Quadratic Gaussian (LQG) techniques. The process of obtaining an implementable reduced-order controller is described. One example is also shown in which constrained optimization techniques are utilized to explicitly include robustness criteria within the design algorithm

    Tools for active control system design

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    Efficient control law analysis and design tools which properly account for the interaction of flexible structures, unsteady aerodynamics and active controls are developed. Development, application, validation and documentation of efficient multidisciplinary computer programs for analysis and design of active control laws are also discussed

    The Caenorhabditis elegans Female State: Decoupling the Transcriptomic Effects of Aging and Sperm-Status

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    Understanding genome and gene function in a whole organism requires us to fully comprehend the life cycle and the physiology of the organism in question. Caenorhabditis elegans XX animals are hermaphrodites that exhaust their sperm after 3 d of egg-laying. Even though C. elegans can live for many days after cessation of egg-laying, the molecular physiology of this state has not been as intensely studied as other parts of the life cycle, despite documented changes in behavior and metabolism. To study the effects of sperm depletion and aging of C. elegans during the first 6 d of adulthood, we measured the transcriptomes of first-day adult hermaphrodites and sixth-day sperm-depleted adults, and, at the same time points, mutant fog-2(lf) worms that have a feminized germline phenotype. We found that we could separate the effects of biological aging from sperm depletion. For a large subset of genes, young adult fog-2(lf) animals had the same gene expression changes as sperm-depleted sixth-day wild-type hermaphrodites, and these genes did not change expression when fog-2(lf) females reached the sixth day of adulthood. Taken together, this indicates that changing sperm status causes a change in the internal state of the worm, which we call the female-like state. Our data provide a high-quality picture of the changes that happen in global gene expression throughout the period of early aging in the worm

    Life History of Elsinoe panici

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    Elsinoe panici Tiffany and Mathre is widespread on native Panicum virgatum L. in Iowa. In June Sphaceloma (imperfect stage) conidia develop from acervuli on overwintered stromata of wind-dispersed leaf litter and culms. Germ cubes penetrate between epidermal cells of young leaves, and 2 wk later tiny yellowish, subepidermal stromata are visible. Secondary conidia develop from acervuli on these stromata within 2 wk and are spread to adjacent leaves. Stromata become black, raised, shiny, ovoid-elongate patches, composed of thick-walled pseudoparenchymatous cells. Chlorosis or necrosis does not develop around the stromata. Stromata are visible on all leaves throughout the season. Acervuli, appearing as white spots in black stromata, open by irregular tears in the epidermis. Ascostromata develop on lower leaves infrequently from late July into September. They are tan-bronze, raised, ovoid-elongate, softer, and more loosely structured than stromata. Asci mature at different times. Ascospores are discharged from the bitunicate asci and germinate directly by budding or by germ tubes

    Active controls: A look at analytical methods and associated tools

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    A review of analytical methods and associated tools for active controls analysis and design problems is presented. Approaches employed to develop mathematical models suitable for control system analysis and/or design are discussed. Significant efforts have been expended to develop tools to generate the models from the standpoint of control system designers' needs and develop the tools necessary to analyze and design active control systems. Representative examples of these tools are discussed. Examples where results from the methods and tools have been compared with experimental data are also presented. Finally, a perspective on future trends in analysis and design methods is presented

    Evaluation of wildlife Guards at Access Roads

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    The reconstruction of 90.6 km of U.S. Highway 93 from Evaro to Polson, MT on the Flathead Indian Reservation includes 41 fish and wildlife crossing structures and 13.4 km of road with wildlife fencing. These measures are aimed at reducing wildlife–vehicle collisions, while allowing wildlife to cross the road. In fenced road sections, gaps for side roads are mitigated by wildlife guards (similar to cattle guards). We focused on a 1-km fenced section where animals can either cross the road using five crossing structures (4 culverts, 1 bridge), or they can access the road through two guards on the east side and cross using jump-outs, i.e., earthen ramps that allow animals in fenced areas to jump down to safety, on the west side. We monitored wildlife movements with cameras at the two guards and in one large crossing structure adjacent to a guard. We investigated how effective these guards are in keeping deer (Odocoileus spp.) from accessing the road. We also compared movements across a guard to those through a crossing structure. The guards were 85 percent or more effective in keeping deer from accessing the road, and 93.5 percent of deer used the crossing structure instead of an adjacent guard when crossing the road. Though the guards were not an absolute barrier to deer, the results indicated that deer were substantially discouraged from crossing the guards, and the vast majority crossed the road using the crossing structure rather than the guard, indicating that guards are an effective means of mitigation

    Pemberdayaan Media Massa Dalam Meningkatkan Pendidikan Politik Pada Masyarakat Kelurahan Wewelen Kecamatan Tondano Barat Kabupaten Minahasa

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    Penelitian ini dilakukan untuk mengetahui pemberdayaan media massa dalam meningkatkan pendidikan politik pada masyarakat kecamatan Tondano Barat Kabupaten Minahasa dan untuk mengetahui media massa yang dominan sebagai sarana bagi masyarakat untuk mendapatkan informasi terkait politik.Penelitian ini menggunakan metode kualitatif. Responden penelitian ditentukan sebanyak 10 orang yang terdiri dari 2 orang aparatur pemerintah, 2 orang karyawan swasta dan wirausahawan, 2 orang tokoh agama, 2 orang tokoh masyarakat dan 2 orang tokoh pemuda. Pengumpulan data dilakukan dengan menggunakan teknik wawancara dan observasi. Teknik analisis data yang digunakan ialah deskriptif kualitatif.Hasil penelitian menyimpulkan bahwa media massa khususnya televisi belum sepenuhnya menjalankan fungsinya sebagai sarana pendidikan politik. Lebih banyak menampilkan aspek hiburan dan komersial. Dengan kata lain media massa kurang berdaya dalam upaya meningkatkan pendidikan politik masyarakat. Kesimpulan berikutnya adalah bahwa responden lebih menyukai siaran-siaran televisi yang ditampilkan oleh Metro TV dan TV One sebagai sumber informasi berkaitan dengan ekonomi, hukum dan politik.Mengacu dari kesimpulan tersebut maka penulis menyarankan agar pengelola media televisi meningkatkan frekwensi penayangan informasi-informasi politik khususnya politik lokal. Informasi-informasi tersebut dipilih yang memiliki bobot nilai dalam kerangka pendidikan politik masyarakat
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