3,406 research outputs found

    Investigation of rank 2 and higher output feedback for pole placement

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    A common feature of several pole placement techniques is discussed and the use of a dyadic feedback matrix is presented. The limitation of this design is examined and a design involving output feedback matrices of Rank greater than one is developed as a logical extension of the dyadic feedback design. An example is presented to illustrate the design procedure

    An efficient algorithm for calculation of the Luenberger canonical form

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    An algorithm is suggested to obtain the Luenberger canonical form for multivariable systems. The method computes the canonical form directly without having to compute the transformation matrix. In addition, there is a large reduction in the number of calculations. The reduced computations along with Gaussian techniques lend to greater inherent accuracy and the ability to refine the solution with additional computations

    Non-perturbative unification in the light of LEP results

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    We consider an alternative to conventional GUTs originally proposed by Maiani, Parisi and Petronzio, where owing to the existence of extra fermion generations at some intermediate scale, the gauge couplings become large at high energies. We first comment on how the non- supersymmetric version of this scenario is ruled out; we then consider the two-loop evolution of the couplings in the supersymmetric extension of this scenario, and check whether such a scenario is feasible in the light of the precies values of couplings now available from LEP.Comment: Latex file 7 pages+1 fig. (ps file appended after the latex file), CERN-TH.6913/9

    R-Parity Violating Supersymmetry Explanation for Large t tbar Forward-Backward Asymmetry

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    We propose a supersymmetric explanation for the anomalously high forward backward asymmetry in top pair production measured by CDF and D0. We suppose that it is due to the t-channel exchange of a right-handed sbottom which couples to d_R and t_R, as is present in the R-parity violating minimal supersymmetric standard model. We show that all Tevatron and LHC experiments' t tbar constraints may be respected for a sbottom mass between 300 and 1200 GeV, and a large Yukawa coupling >2.2, yielding A_{FB} up to 0.18. The non Standard Model contribution to the LHC charge asymmetry parameter is Delta A_C^y=0.017-0.045, small enough to be consistent with current measurements but non-zero and positive, allowing for LHC confirmation in the future within 20 fb^-1. A small additional contribution to the LHC t tbar production cross-section is also predicted, allowing a further test. We estimate that 10 fb^-1 of LHC luminosity would be sufficient to rule out the proposal to 95% confidence level, if the measurements of the t tbar cross-section turn out to be centred on the Standard Model prediction.Comment: 5 pages, 2 figures, v2 has added comments and references and increased statistics, leading to more accurate numerical predictions. v3 has typos in Fig 1 fixed: arrow directions and t and tbar labels. v4 has added discussion and corrections to Eq 4. v5 has luminosity predictions, additional checks and small numerical change

    Investigating the Supersymmetric Explanation of Anomalous CDF lepton(s) photon(s) Missing-E_T Events

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    The recent excess over the Standard Model prediction in the \mu \gamma missing-E_T channel reported by CDF can be well-explained by resonant smuon production with a single dominant R-parity violating coupling \lambda'_{211}, in the context of models where the gravitino is the lightest supersymmetric particle. The slepton decays to the lightest neutralino and a muon followed by neutralino decaying to a gravitino and photon. The kinematical distributions are fitted well by our hypothesis and we use them to constrain the available parameter space. The model also provides an explanation for the ee\gamma\gamma missing-E_T event observed in Run I of the Tevatron by the CDF experiment. Our model predicts an excess of between 5 and 35 events in a \gamma missing-E_T channel at Run I. We provide predictions for signatures expected by the model at Run II.Comment: 23 pages, Latex file + 10 figures and 4 Tables (included) Includes JHEP3.cls and axodraw.st

    AN INVESTIGATION OF DIFFERENT VIDEO WATERMARKING TECHNIQUES

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    Watermarking is an advanced technology that identifies to solve the problem of illegal manipulation and distribution of digital data. It is the art of hiding the copyright information into host such that the embedded data is imperceptible. The covers in the forms of digital multimedia object, namely image, audio and video. The extensive literature collected related to the performance improvement of video watermarking techniques is critically reviewed and presented in this paper. Also, comprehensive review of the literature on the evolution of various video watermarking techniques to achieve robustness and to maintain the quality of watermarked video sequences

    Configuration management and automatic control of an augmentor wing aircraft with vectored thrust

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    An advanced structure for automatic flight control logic for powered-lift aircraft operating in terminal areas is under investigation at Ames Research Center. This structure is based on acceleration control; acceleration commands are constructed as the sum of acceleration on the reference trajectory and a corrective feedback acceleration to regulate path tracking errors. The central element of the structure, termed a Trimmap, uses a model of the aircraft aerodynamic and engine forces to calculate the control settings required to generate the acceleration commands. This report describes the design criteria for the Trimmap and derives a Trimmap for Ames experimental augmentor wing jet STOL research aircraft

    Oxygen production on Mars and the Moon

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    Significant progress was made in the area of in-situ oxygen production in the last year. In order to reduce sealing problems due to thermal expansion mismatch in the disk configuration, several all-Zirconia cells were constructed and are being tested. Two of these cells were run successfully for extended periods of time. One was run for over 200 hours and the other for over 800 hours. These extended runs, along with gas sample analysis, showed that the oxygen being produced is definitely from CO2 and not from air leaks or from the disk material. A new tube system is being constructed that is more rugged, portable, durable, and energy efficient. The important operating parameters of this system will be better controlled compared to previous systems. An electrochemical compressor will also be constructed with a similar configuration. The electrochemical compressor will use less energy since the feed stock is already heated in the separation unit. In addition, it does not have moving parts

    The Enrollment Effects of Merit-Based Financial Aid: Evidence from Georgia's HOPE Scholarship

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    This paper examines the effects of Georgia's merit-based HOPE Scholarship on college enrollment. Introduced in 1993, the HOPE Scholarship covers tuition, fees, and book expenses for students attending Georgia public colleges, and provides a subsidy of comparable value to students attending in-state private colleges, without any income restrictions. Treating HOPE as a natural experiment, we contrast college enrollment in Georgia with those in the other member states of the Southern Regional Educational Board using IPEDS data for the period 1988-97. We estimate that the HOPE increased total freshmen enrollment by 5.9 percent, with the gains concentrated in 4-year schools. For freshmen recently graduated from high school attending 4-year colleges, two-thirds of the program effect is explained by a decrease in students leaving the state. Both white and black enrollments increased because of HOPE, with the state's historically-black institutions playing an important role. Finally, the total HOPE-induced enrollment increase represents only 15 percent freshmen scholarship recipients.Higher Education, Enrollment, HOPE, Merit-based Aid
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