NASA Technical Reports Server (NTRS)
Walker, K. P.
1981-01-01
Results of a 20-month research and development program for nonlinear structural modeling with advanced time-temperature constitutive relationships are reported. The program included: (1) the evaluation of a number of viscoplastic constitutive models in the published literature; (2) incorporation of three of the most appropriate constitutive models into the MARC nonlinear finite element program; (3) calibration of the three constitutive models against experimental data using Hastelloy-X material; and (4) application of the most appropriate constitutive model to a three dimensional finite element analysis of a cylindrical combustor liner louver test specimen to establish the capability of the viscoplastic model to predict component structural response.
LTSTAR- SUPERSONIC WING NON-LINEAR AERODYNAMICS PROGRAM
NASA Technical Reports Server (NTRS)
Carlson, H. W.
1994-01-01
The Supersonic Wing Nonlinear Aerodynamics computer program, LTSTAR, was developed to provide for the estimation of the nonlinear aerodynamic characteristics of a wing at supersonic speeds. This corrected linearized-theory method accounts for nonlinearities in the variation of basic pressure loadings with local surface slopes, predicts the degree of attainment of theoretical leading-edge thrust forces, and provides an estimate of detached leading-edge vortex loadings that result when the theoretical thrust forces are not fully realized. Comparisons of LTSTAR computations with experimental results show significant improvements in detailed wing pressure distributions, particularly for large angles of attack and for regions of the wing where the flow is highly three-dimensional. The program provides generally improved predictions of the wing overall force and moment coefficients. LTSTAR could be useful in design studies aimed at aerodynamic performance optimization and for providing more realistic trade-off information for selection of wing planform geometry and airfoil section parameters. Input to the LTSTAR program includes wing planform data, freestream conditions, wing camber, wing thickness, scaling options, and output options. Output includes pressure coefficients along each chord, section normal and axial force coefficients, and the spanwise distribution of section force coefficients. With the chordwise distributions and section coefficients at each angle of attack, three sets of polars are output. The first set is for linearized theory with and without full leading-edge thrust, the second set includes nonlinear corrections, and the third includes estimates of attainable leading-edge thrust and vortex increments along with the nonlinear corrections. The LTSTAR program is written in FORTRAN IV for batch execution and has been implemented on a CDC 6000 series computer with a central memory requirement of approximately 150K (octal) of 60 bit words. The LTSTAR
NASA Astrophysics Data System (ADS)
Vasant, P.; Ganesan, T.; Elamvazuthi, I.
2012-11-01
A fairly reasonable result was obtained for non-linear engineering problems using the optimization techniques such as neural network, genetic algorithms, and fuzzy logic independently in the past. Increasingly, hybrid techniques are being used to solve the non-linear problems to obtain better output. This paper discusses the use of neuro-genetic hybrid technique to optimize the geological structure mapping which is known as seismic survey. It involves the minimization of objective function subject to the requirement of geophysical and operational constraints. In this work, the optimization was initially performed using genetic programming, and followed by hybrid neuro-genetic programming approaches. Comparative studies and analysis were then carried out on the optimized results. The results indicate that the hybrid neuro-genetic hybrid technique produced better results compared to the stand-alone genetic programming method.
Genetic programming as an analytical tool for non-linear dielectric spectroscopy.
Woodward, A M; Gilbert, R J; Kell, D B
1999-05-01
By modelling the non-linear effects of membranous enzymes on an applied oscillating electromagnetic field using supervised multivariate analysis methods, Non-Linear Dielectric Spectroscopy (NLDS) has previously been shown to produce quantitative information that is indicative of the metabolic state of various organisms. The use of Genetic Programming (GP) for the multivariate analysis of NLDS data recorded from yeast fermentations is discussed, and GPs are compared with previous results using Partial Least Squares (PLS) and Artificial Neural Nets (NN). GP considerably outperforms these methods, both in terms of the precision of the predictions and their interpretability. PMID:10379559
Christophersen, A; McKinley-McKee, J S
1984-01-01
An interactive program for analysing enzyme activity-time data using non-linear regression analysis is described. Protection studies can also be dealt with. The program computes inactivation rates, dissociation constants and promotion or inhibition parameters with their standard errors. It can also be used to distinguish different inactivation models. The program is written in SIMULA and is menu-oriented for refining or correcting data at the different levels of computing. PMID:6546558
Optimal Reservoir Operation for Hydropower Generation using Non-linear Programming Model
NASA Astrophysics Data System (ADS)
Arunkumar, R.; Jothiprakash, V.
2012-05-01
Hydropower generation is one of the vital components of reservoir operation, especially for a large multi-purpose reservoir. Deriving optimal operational rules for such a large multi-purpose reservoir serving various purposes like irrigation, hydropower and flood control are complex, because of the large dimension of the problem and the complexity is more if the hydropower production is not an incidental. Thus optimizing the operations of a reservoir serving various purposes requires a systematic study. In the present study such a large multi-purpose reservoir, namely, Koyna reservoir operations are optimized for maximizing the hydropower production subject to the condition of satisfying the irrigation demands using a non-linear programming model. The hydropower production from the reservoir is analysed for three different dependable inflow conditions, representing wet, normal and dry years. For each dependable inflow conditions, various scenarios have been analyzed based on the constraints on the releases and the results are compared. The annual power production, combined monthly power production from all the powerhouses, end of month storage levels, evaporation losses and surplus are discussed. From different scenarios, it is observed that more hydropower can be generated for various dependable inflow conditions, if the restrictions on releases are slightly relaxed. The study shows that Koyna dam is having potential to generate more hydropower.
Automatic design of synthetic gene circuits through mixed integer non-linear programming.
Huynh, Linh; Kececioglu, John; Köppe, Matthias; Tagkopoulos, Ilias
2012-01-01
Automatic design of synthetic gene circuits poses a significant challenge to synthetic biology, primarily due to the complexity of biological systems, and the lack of rigorous optimization methods that can cope with the combinatorial explosion as the number of biological parts increases. Current optimization methods for synthetic gene design rely on heuristic algorithms that are usually not deterministic, deliver sub-optimal solutions, and provide no guaranties on convergence or error bounds. Here, we introduce an optimization framework for the problem of part selection in synthetic gene circuits that is based on mixed integer non-linear programming (MINLP), which is a deterministic method that finds the globally optimal solution and guarantees convergence in finite time. Given a synthetic gene circuit, a library of characterized parts, and user-defined constraints, our method can find the optimal selection of parts that satisfy the constraints and best approximates the objective function given by the user. We evaluated the proposed method in the design of three synthetic circuits (a toggle switch, a transcriptional cascade, and a band detector), with both experimentally constructed and synthetic promoter libraries. Scalability and robustness analysis shows that the proposed framework scales well with the library size and the solution space. The work described here is a step towards a unifying, realistic framework for the automated design of biological circuits. PMID:22536398
Christodoulou, Manolis A; Kontogeorgou, Chrysa
2008-10-01
In recent years there has been a great effort to convert the existing Air Traffic Control system into a novel system known as Free Flight. Free Flight is based on the concept that increasing international airspace capacity will grant more freedom to individual pilots during the enroute flight phase, thereby giving them the opportunity to alter flight paths in real time. Under the current system, pilots must request, then receive permission from air traffic controllers to alter flight paths. Understandably the new system allows pilots to gain the upper hand in air traffic. At the same time, however, this freedom increase pilot responsibility. Pilots face a new challenge in avoiding the traffic shares congested air space. In order to ensure safety, an accurate system, able to predict and prevent conflict among aircraft is essential. There are certain flight maneuvers that exist in order to prevent flight disturbances or collision and these are graded in the following categories: vertical, lateral and airspeed. This work focuses on airspeed maneuvers and tries to introduce a new idea for the control of Free Flight, in three dimensions, using neural networks trained with examples prepared through non-linear programming. PMID:18991361
Mitsos, Alexander; Melas, Ioannis N; Morris, Melody K; Saez-Rodriguez, Julio; Lauffenburger, Douglas A; Alexopoulos, Leonidas G
2012-01-01
Modeling of signal transduction pathways plays a major role in understanding cells' function and predicting cellular response. Mathematical formalisms based on a logic formalism are relatively simple but can describe how signals propagate from one protein to the next and have led to the construction of models that simulate the cells response to environmental or other perturbations. Constrained fuzzy logic was recently introduced to train models to cell specific data to result in quantitative pathway models of the specific cellular behavior. There are two major issues in this pathway optimization: i) excessive CPU time requirements and ii) loosely constrained optimization problem due to lack of data with respect to large signaling pathways. Herein, we address both issues: the former by reformulating the pathway optimization as a regular nonlinear optimization problem; and the latter by enhanced algorithms to pre/post-process the signaling network to remove parts that cannot be identified given the experimental conditions. As a case study, we tackle the construction of cell type specific pathways in normal and transformed hepatocytes using medium and large-scale functional phosphoproteomic datasets. The proposed Non Linear Programming (NLP) formulation allows for fast optimization of signaling topologies by combining the versatile nature of logic modeling with state of the art optimization algorithms. PMID:23226239
Non-Linear Editing for the Smaller College-Level Production Program, Rev. 2.0.
ERIC Educational Resources Information Center
Tetzlaff, David
This paper focuses on a specific topic and contention: Non-linear editing earns its place in a liberal arts setting because it is a superior tool to teach the concepts of how moving picture discourse is constructed through editing. The paper first points out that most students at small liberal arts colleges are not going to wind up working…
NASA Technical Reports Server (NTRS)
Fleming, P.
1985-01-01
A design technique is proposed for linear regulators in which a feedback controller of fixed structure is chosen to minimize an integral quadratic objective function subject to the satisfaction of integral quadratic constraint functions. Application of a non-linear programming algorithm to this mathematically tractable formulation results in an efficient and useful computer-aided design tool. Particular attention is paid to computational efficiency and various recommendations are made. Two design examples illustrate the flexibility of the approach and highlight the special insight afforded to the designer.
NASA Astrophysics Data System (ADS)
Jamali, A.; Khaleghi, E.; Gholaminezhad, I.; Nariman-zadeh, N.
2016-05-01
In this paper, a new multi-objective genetic programming (GP) with a diversity preserving mechanism and a real number alteration operator is presented and successfully used for Pareto optimal modelling of some complex non-linear systems using some input-output data. In this study, two different input-output data-sets of a non-linear mathematical model and of an explosive cutting process are considered separately in three-objective optimisation processes. The pertinent conflicting objective functions that have been considered for such Pareto optimisations are namely, training error (TE), prediction error (PE), and the length of tree (complexity of the network) (TL) of the GP models. Such three-objective optimisation implementations leads to some non-dominated choices of GP-type models for both cases representing the trade-offs among those objective functions. Therefore, optimal Pareto fronts of such GP models exhibit the trade-off among the corresponding conflicting objectives and, thus, provide different non-dominated optimal choices of GP-type models. Moreover, the results show that no significant optimality in TE and PE may occur when the TL of the corresponding GP model exceeds some values.
A Non-linear Temperature-Time Program for Non-isothermal Kinetic Measurements
NASA Astrophysics Data System (ADS)
Sohn, Hong Yong
2016-04-01
A new temperature-time program for non-isothermal measurements of chemical reaction rates has been developed. The major advantages of the proposed temperature-time function are twofold: Firstly, the analysis of kinetic information in the high temperature range of the measurement is improved over the conventional linear temperature program by slowing the rate of temperature increase in the high temperature range and secondly, the new temperature program greatly facilitates the data analysis by providing a closed-form solution of the temperature integral and allows a convenient way to obtain the kinetic parameters by eliminating the need for the approximate evaluation of the temperature integral. The procedures for applying the new temperature-time program to the analysis of experimental data are demonstrated in terms of the determination of the kinetic parameters based on the selection of a suitable conversion function in the rate equation as well as the direct determination of activation energy at different conversion extents without the need for a conversion function. The rate analysis based on the new temperature program is robust and does not appear to be sensitive to errors in experimental measurements.
NASA Technical Reports Server (NTRS)
Maskew, B.
1982-01-01
VSAERO is a computer program used to predict the nonlinear aerodynamic characteristics of arbitrary three-dimensional configurations in subsonic flow. Nonlinear effects of vortex separation and vortex surface interaction are treated in an iterative wake-shape calculation procedure, while the effects of viscosity are treated in an iterative loop coupling potential-flow and integral boundary-layer calculations. The program employs a surface singularity panel method using quadrilateral panels on which doublet and source singularities are distributed in a piecewise constant form. This user's manual provides a brief overview of the mathematical model, instructions for configuration modeling and a description of the input and output data. A listing of a sample case is included.
Energy Science and Technology Software Center (ESTSC)
2006-11-17
Software that simulates and inverts electromagnetic field data for subsurface electrical properties (electrical conductivity) of geological media. The software treats data produced by a time harmonic source field excitation arising from the following antenna geometery: loops and grounded bipoles, as well as point electric and magnetic dioples. The inversion process is carried out using a non-linear conjugate gradient optimization scheme, which minimizes the misfit between field data and model data using a least squares criteria.more » The software is an upgrade from the code NLCGCS_MP ver 1.0. The upgrade includes the following components: Incorporation of new 1 D field sourcing routines to more accurately simulate the 3D electromagnetic field for arbitrary geologic& media, treatment for generalized finite length transmitting antenna geometry (antennas with vertical and horizontal component directions). In addition, the software has been upgraded to treat transverse anisotropy in electrical conductivity.« less
Wang, C.Y.
1985-01-01
A three-dimensional computer program for linear/non-linear, static/dynamic analyses of reactor-piping systems under various accident loads is described. In the analysis, the hydrodynamic calculation can be performed in the implicit or semi-implicit manner. The structure response can be calculated using either a purely explicit or implicit time-integration scheme. Coupling between the fluid and structure is achieved by utilizing either the implicit-explicit or implicit-implicit link. Thus, a wide range of piping safety problems can be analyzed by the suitable choice of options available in the hydrodynamics and structural analysis. In this paper, several salient features are presented. Sample problems illustrating the versatility of the program are given. The results are discussed in detail.
NASA Astrophysics Data System (ADS)
Arrigoni, Marco; McCoy, Darryl
2016-03-01
In the last few years Multiphoton Excitation Microscopy witnessed a mutation from tool for imaging cellular structures in living animals deeper than other high-resolution techniques, into an instrument for monitoring functionality and even stimulating or inhibiting inter-cellular signalling. This paradigm shift has been enabled primarily by the development of genetically encoded probes like Ca indicators (GECI) and Opsins for optogenetics inhibition and stimulation. These developments will hopefully enable the understanding of how local network of hundreds or thousands of neurons operate in response to actual tasks or induced stimuli. Imaging, monitoring signals and activating neurons, all on a millisecond time scale, requires new laser tools providing a combination of wavelengths, higher powers and operating regimes different from the ones traditionally used for classic multiphoton imaging. The other key development in multiphoton techniques relates to potential diagnostic and clinical applications where non-linear imaging could provide all optical marker-free replacement of H and E techniques and even intra-operative guidance for procedures like cancer surgery. These developments will eventually drive the development of specialized laser sources where compact size, ease of use, beam delivery and cost are primary concerns. In this talk we will discuss recent laser product developments targeting the various applications of multiphoton imaging, as fiber lasers and other new type of lasers gradually gain popularity and their own space, side-by-side or as an alternative to conventional titanium sapphire femtosecond lasers.
Computer modeling of batteries from non-linear circuit elements
NASA Technical Reports Server (NTRS)
Waaben, S.; Federico, J.; Moskowitz, I.
1983-01-01
A simple non-linear circuit model for battery behavior is given. It is based on time-dependent features of the well-known PIN change storage diode, whose behavior is described by equations similar to those associated with electrochemical cells. The circuit simulation computer program ADVICE was used to predict non-linear response from a topological description of the battery analog built from advice components. By a reasonable choice of one set of parameters, the circuit accurately simulates a wide spectrum of measured non-linear battery responses to within a few millivolts.
Advanced studies program overview
NASA Technical Reports Server (NTRS)
Ahlf, Peter R.
1991-01-01
The topics covered are presented in view graph form and include the following: (1) Space Station Engineering; (2) level 1 engineering organization; (3) advanced studies program organization; (4) NASA Center support areas; (5) work breakdown; (6) Space Station Freedom (SSF) Program Phases; (7) distributed systems evolution; (8) Space Shuttle ET mating analogy to on-orbit tank mating; (9) reference growth concept; (10) technology assessment process; (11) SSF technology priorities; (12) accomplishments; and (13) near term direction.
NIST ADVANCED TECHNOLOGY PROGRAM
Not-yet-possible technologies are the domain of the National Institute of Standards and Technology (NIST) Advanced Technology Program. The ATP is a unique partnership between government and private industry to accelerate the development of high-risk technologies that promise sign...
Advanced composites technology program
NASA Technical Reports Server (NTRS)
Davis, John G., Jr.
1993-01-01
This paper provides a brief overview of the NASA Advanced Composites Technology (ACT) Program. Critical technology issues that must be addressed and solved to develop composite primary structures for transport aircraft are delineated. The program schedule and milestones are included. Work completed in the first 3 years of the program indicates the potential for achieving composite structures that weigh less and are cost effective relative to conventional aluminum structure. Selected technical accomplishments are noted. Readers who are seeking more in-depth technical information should study the other papers included in these proceedings.
Advanced turbine systems program
Wilkes, C.; Mukavetz, D.W.; Knickerbocker, T.K.; Ali, S.A.
1992-01-01
In accordance with the goals of the DOE program, improvements in the gas turbine are the primary focus of Allison activity during Phase I. To this end Allison conducted a survey of potentially applicable gas turbine cycles and selected the advanced combined cycle as reference system. Extensive analysis of two versions of the advanced combined cycle was performed against the requirement for a 60% thermal efficiency (LHV) utility-sized, natural gas fired system. This analysis resulted in technology requirements for this system. Additional analysis determined emissions potential for the system, established a coal-fueled derivative system and a commercialization plan. This report deals with the technical requirements for a system that meets the thermal efficiency goal. Allison initially investigated four basic thermodynamic cycles: Humid air turbine, intercalate-recuperated systems, advanced combined cycle, chemically recuperated cycle. Our survey and cycle analysis indicated that au had the potential of reaching 60% thermal efficiency. We also concluded that engine hot section technology would be a critical technology regardless of which cycle was chosen. Based on this result Allison chose to concentrate on the advanced combined cycle. This cycle is well known and understood by the utility turbine user community and is therefore likely to be acceptable to users.
Advanced turbine systems program
Wilkes, C.; Mukavetz, D.W.; Knickerbocker, T.K.; Ali, S.A.
1992-12-31
In accordance with the goals of the DOE program, improvements in the gas turbine are the primary focus of Allison activity during Phase I. To this end Allison conducted a survey of potentially applicable gas turbine cycles and selected the advanced combined cycle as reference system. Extensive analysis of two versions of the advanced combined cycle was performed against the requirement for a 60% thermal efficiency (LHV) utility-sized, natural gas fired system. This analysis resulted in technology requirements for this system. Additional analysis determined emissions potential for the system, established a coal-fueled derivative system and a commercialization plan. This report deals with the technical requirements for a system that meets the thermal efficiency goal. Allison initially investigated four basic thermodynamic cycles: Humid air turbine, intercalate-recuperated systems, advanced combined cycle, chemically recuperated cycle. Our survey and cycle analysis indicated that au had the potential of reaching 60% thermal efficiency. We also concluded that engine hot section technology would be a critical technology regardless of which cycle was chosen. Based on this result Allison chose to concentrate on the advanced combined cycle. This cycle is well known and understood by the utility turbine user community and is therefore likely to be acceptable to users.
NASA Technical Reports Server (NTRS)
Bielawa, R. L.
1976-01-01
The differential equations of motion for the lateral and torsional deformations of a nonlinearly twisted rotor blade in steady flight conditions together with those additional aeroelastic features germane to composite bearingless rotors are derived. The differential equations are formulated in terms of uncoupled (zero pitch and twist) vibratory modes with exact coupling effects due to finite, time variable blade pitch and, to second order, twist. Also presented are derivations of the fully coupled inertia and aerodynamic load distributions, automatic pitch change coupling effects, structural redundancy characteristics of the composite bearingless rotor flexbeam - torque tube system in bending and torsion, and a description of the linearized equations appropriate for eigensolution analyses. Three appendixes are included presenting material appropriate to the digital computer program implementation of the analysis, program G400.
Proceedings of the Non-Linear Aero Prediction Requirements Workshop
NASA Technical Reports Server (NTRS)
Logan, Michael J. (Editor)
1994-01-01
The purpose of the Non-Linear Aero Prediction Requirements Workshop, held at NASA Langley Research Center on 8-9 Dec. 1993, was to identify and articulate requirements for non-linear aero prediction capabilities during conceptual/preliminary design. The attendees included engineers from industry, government, and academia in a variety of aerospace disciplines, such as advanced design, aerodynamic performance analysis, aero methods development, flight controls, and experimental and theoretical aerodynamics. Presentations by industry and government organizations were followed by panel discussions. This report contains copies of the presentations and the results of the panel discussions.
Advanced Rotorcraft Transmission Program
NASA Technical Reports Server (NTRS)
Bill, Robert C.
1990-01-01
The U.S. Army/NASA Advanced Rotorcraft Transmission (ART) program is charged with developing and demonstrating a light, quiet, and durable drivetrain for next-generation rotorcraft in two classes: a 10,000-20,000 Future Attack Air Vehicle capable of both tactical ground support and air-to-air missions, and a 60,000-80,000 lb Advanced Cargo Aircraft, for heavy-lift field-support operations. Specific ART objectives encompass a 25-percent reduction in drivetrain weight, a 10-dB noise level reduction at the transmission source, and the achievement of a 5000-hr MTBF. Four candidate drivetrain systems have been carried to a conceptual design stage, together with projections of their mission performance and life-cycle costs.
Criteria for Evaluating Advancement Programs.
ERIC Educational Resources Information Center
Heemann, Warren, Ed.
Criteria for evaluating college and university advancement programs are presented, based on the efforts of professional area trustees and advisory committees of the Council for Advancement and Support of Education (CASE). The criteria can be useful in three ways: as the basis of internal audits of advancement programs or program components; as the…
ADVANCED TURBINE SYSTEMS PROGRAM
Gregory Gaul
2004-04-21
Natural gas combustion turbines are rapidly becoming the primary technology of choice for generating electricity. At least half of the new generating capacity added in the US over the next twenty years will be combustion turbine systems. The Department of Energy has cosponsored with Siemens Westinghouse, a program to maintain the technology lead in gas turbine systems. The very ambitious eight year program was designed to demonstrate a highly efficient and commercially acceptable power plant, with the ability to fire a wide range of fuels. The main goal of the Advanced Turbine Systems (ATS) Program was to develop ultra-high efficiency, environmentally superior and cost effective competitive gas turbine systems for base load application in utility, independent power producer and industrial markets. Performance targets were focused on natural gas as a fuel and included: System efficiency that exceeds 60% (lower heating value basis); Less than 10 ppmv NO{sub x} emissions without the use of post combustion controls; Busbar electricity that are less than 10% of state of the art systems; Reliability-Availability-Maintainability (RAM) equivalent to current systems; Water consumption minimized to levels consistent with cost and efficiency goals; and Commercial systems by the year 2000. In a parallel effort, the program was to focus on adapting the ATS engine to coal-derived or biomass fuels. In Phase 1 of the ATS Program, preliminary investigators on different gas turbine cycles demonstrated that net plant LHV based efficiency greater than 60% was achievable. In Phase 2 the more promising cycles were evaluated in greater detail and the closed-loop steam-cooled combined cycle was selected for development because it offered the best solution with least risk for achieving the ATS Program goals for plant efficiency, emissions, cost of electricity and RAM. Phase 2 also involved conceptual ATS engine and plant design and technology developments in aerodynamics, sealing
Advanced rotorcraft transmission program
NASA Technical Reports Server (NTRS)
Bill, Robert C.
1990-01-01
The Advanced Rotorcraft Transmission (ART) program is an Army-funded, joint Army/NASA program to develop and demonstrate lightweight, quiet, durable drivetrain systems for next generation rotorcraft. ART addresses the drivetrain requirements of two distinct next generation aircraft classes: Future Air Attack Vehicle, a 10,000 to 20,000 lb. aircraft capable of undertaking tactical support and air-to-air missions; and Advanced Cargo Aircraft, a 60,000 to 80,000 lb. aircraft capable of heavy life field support operations. Both tiltrotor and more conventional helicopter configurations are included in the ART program. Specific objectives of ART include reduction of drivetrain weight by 25 percent compared to baseline state-of-the-art drive systems configured and sized for the next generation aircraft, reduction of noise level at the transmission source by 10 dB relative to a suitably sized and configured baseline, and attainment of at least a 5000 hr mean-time-between-removal. The technical approach for achieving the ART goals includes application of the latest available component, material, and lubrication technology to advanced concept drivetrains that utilize new ideas in gear configuration, transmission layout, and airframe/drivetrain integration. To date, candidate drivetrain systems were carried to a conceptual design stage, and tradeoff studies were conducted resulting in selection of an ART transmission configuration for each of the four contractors. The final selection was based on comparative weight, noise, and reliability studies. A description of each of the selected ART designs is included. Preliminary design of each of the four selected ART transmission was completed, as have mission impact studies wherein comparisons of aircraft mission performance and life cycle costs are undertaken for the next generation aircraft with ART and with the baseline transmission.
Non-linearity in clinical practice.
Petros, Peter
2003-05-01
The whole spectrum of medicine consists of complex non-linear systems that are balanced and interact with each other. How non-linearity confers stability on a system and explains variation and uncertainty in clinical medicine is discussed. A major theme is that a small alteration in initial conditions may have a major effect on the end result. In the context of non-linearity, it is argued that 'evidence-based medicine' (EBM) as it exists today can only ever be relevant to a small fraction of the domain of medicine, that the 'art of medicine' consists of an intuitive 'tuning in' to these complex systems and as such is not so much an art as an expression of non-linear science. The main cause of iatrogenic disease is interpreted as a failure to understand the complexity of the systems being treated. Case study examples are given and analysed in non-linear terms. It is concluded that good medicine concerns individualized treatment of an individual patient whose body functions are governed by non-linear processes. EBM as it exists today paints with a broad and limited brush, but it does promise a fresh new direction. In this context, we need to expand the spectrum of scientific medicine to include non-linearity, and to look upon the 'art of medicine' as a historical (but unstated) legacy in this domain. PMID:12787180
Morabito, A; Marubini, E
1976-03-01
Given a set of measurements of s explanatory variables corresponding to each experimental unit, a computer program, whose methodological background can be found in [2] has been written in FORTRAN IV language in order to perform regression analyses when the dependent variable is: (i) dichotomous; (ii) polichotomous; (iii) censored survival. In the two former the Cox's [6] linear logistic models are used while in the third one it has been resorted to the models suggested by Feigl and Zelen [8]. The statistical estimation procedure is maximum likelihood and among the different algorithms developed to reach this goal, the one published by Van der Voort and Dorpema [3], has been utilized. Furthermore, when the dependent variable is quantitative, the program is suitable to fit any function non-linear in the parameters; the pertinent function and its first and second derivatives must be provided by the user. In the present version, implemented on a Univac 1106 machine, the program fits directly the Gompertz function. PMID:1269260
Non-linear methods in remotely sensed multispectral data classification
NASA Astrophysics Data System (ADS)
Nikolov, Hs; Petkov, Di; Jeliazkova, N.; Ruseva, S.; Boyanov, K.
The aim of this research is to examine existing geoinformation processing systems and to develop a new system, able to cope with the stochastic nature of remote sensing data. In order to achieve this objective, it is necessary to structure the methodological knowledge in the area of data mining and reveal the most suitable methods for the prediction and decision support based on large amounts of multispectral data. Non-linear methods are a vast and quickly advancing field of research, but in the case of geoinformatics they are far away from applications targeted to end-users. The idea is to establish a framework by decomposing the task into functionality objectives and to allow the end-user to experiment with a set of classification methods and select the best methods for specific applications. In this framework we consider Bayesian analysis tools, nonlinear regression models, neural networks, fuzzy reasoning systems, kernel methods, evolutionary programming, genetic algorithms and decision trees. In particular we compare our results from Bayesian classification based on estimated probability densities of the data to the results obtained from other classification methods. We demonstrate that the theoretically optimal Bayesian classification also provides optimal classification in practice.
An Advanced Chemistry Laboratory Program.
ERIC Educational Resources Information Center
Wise, John H.
The Advanced Chemistry Laboratory Program is a project designed to devise experiments to coordinate the use of instruments in the laboratory programs of physical chemistry, instrumental analysis, and inorganic chemistry at the advanced undergraduate level. It is intended that such experiments would incorporate an introduction to the instrument…
Non-linear Post Processing Image Enhancement
NASA Technical Reports Server (NTRS)
Hunt, Shawn; Lopez, Alex; Torres, Angel
1997-01-01
A non-linear filter for image post processing based on the feedforward Neural Network topology is presented. This study was undertaken to investigate the usefulness of "smart" filters in image post processing. The filter has shown to be useful in recovering high frequencies, such as those lost during the JPEG compression-decompression process. The filtered images have a higher signal to noise ratio, and a higher perceived image quality. Simulation studies comparing the proposed filter with the optimum mean square non-linear filter, showing examples of the high frequency recovery, and the statistical properties of the filter are given,
Stability of non-linear integrable accelerator
Batalov, I.; Valishev, A.; /Fermilab
2011-09-01
The stability of non-linear Integrable Optics Test Accelerator (IOTA) model developed in [1] was tested. The area of the stable region in transverse coordinates and the maximum attainable tune spread were found as a function of non-linear lens strength. Particle loss as a function of turn number was analyzed to determine whether a dynamic aperture limitation present in the system. The system was also tested with sextupoles included in the machine for chromaticity compensation. A method of evaluation of the beam size in the linear part of the accelerator was proposed.
Non-linearity in Bayesian 1-D magnetotelluric inversion
NASA Astrophysics Data System (ADS)
Guo, Rongwen; Dosso, Stan E.; Liu, Jianxin; Dettmer, Jan; Tong, Xiaozhong
2011-05-01
This paper applies a Bayesian approach to examine non-linearity for the 1-D magnetotelluric (MT) inverse problem. In a Bayesian formulation the posterior probability density (PPD), which combines data and prior information, is interpreted in terms of parameter estimates and uncertainties, which requires optimizing and integrating the PPD. Much work on 1-D MT inversion has been based on (approximate) linearized solutions, but more recently fully non-linear (numerical) approaches have been applied. This paper directly compares results of linearized and non-linear uncertainty estimation for 1-D MT inversion; to do so, advanced methods for both approaches are applied. In the non-linear formulation used here, numerical optimization is carried out using an adaptive-hybrid algorithm. Numerical integration applies Metropolis-Hastings sampling, rotated to a principal-component parameter space for efficient sampling of correlated parameters, and employing non-unity sampling temperatures to ensure global sampling. Since appropriate model parametrizations are generally not known a priori, both under- and overparametrized approaches are considered. For underparametrization, the Bayesian information criterion is applied to determine the number of layers consistent with the resolving power of the data. For overparametrization, prior information is included which favours simple structure in a manner similar to regularized inversion. The data variance and/or trade-off parameter regulating data and prior information are treated in several ways, including applying fixed optimal estimates (an empirical Bayesian approach) or including them as hyperparameters in the sampling (hierarchical Bayesian). The latter approach has the benefit of accounting for the uncertainty in the hyperparameters in estimating model parameter uncertainties. Non-linear and linearized inversion results are compared for synthetic test cases and for the measured COPROD1 MT data by considering marginal probability
Advanced Launch Development Program status
NASA Technical Reports Server (NTRS)
Colgrove, Roger
1990-01-01
The Advanced Launch System is a joint NASA - Air Force program originally directed to define the concept for a modular family of launch vehicles, to continue development programs and preliminary design activities focused primarily on low cost to orbit, and to offer maturing technologies to existing systems. The program was restructed in the spring of 1990 as a result of funding reductions and renamed the Advanced Launch Development Program. This paper addresses the program's status following that restructuring and as NASA and the Air Force commence a period of deliberation over future space launch needs and the budgetary resources available to meet those needs. The program is currently poised to protect a full-scale development decision in the mid-1990's through the appropriate application of program resources. These resources are concentrated upon maintaining the phase II system contractor teams, continuing the Space Transportation Engine development activity, and refocusing the Advanced Development Program demonstrated activities.
NASA Astrophysics Data System (ADS)
Thomson, Mark J.; McKellar, Bruce H. J.
1991-04-01
A simple, non-linear generalization of the MSW equation is presented and its analytic solution is outlined. The orbits of the polarization vector are shown to be periodic, and to lie on a sphere. Their non-trivial flow patterns fall into two topological categories, the more complex of which can become chaotic if perturbed.
Non-linear cord-rubber composites
NASA Technical Reports Server (NTRS)
Clark, S. K.; Dodge, R. N.
1989-01-01
A method is presented for calculating the stress-strain relations in a multi-layer composite made up of materials whose individual stress-strain characteristics are non-linear and possibly different. The method is applied to the case of asymmetric tubes in tension, and comparisons with experimentally measured data are given.
Advanced ramjet concepts program
NASA Technical Reports Server (NTRS)
Leingang, J. L.
1992-01-01
Uniquely advantageous features, on both the performance and weight sides of the ledger, can be achieved through synergistic design integration of airbreathing and rocket technologies in the development of advanced orbital space transport propulsion systems of the combined cycle type. In the context of well understood advanced airbreathing and liquid rocket propulsion principles and practices, this precept of synergism is advanced mainly through six rather specific examples. These range from the detailed component level to the overall vehicle system level as follows: using jet compression; achieving a high area ratio rocket nozzle; ameliorating gas generator cycle rocket system deficiencies; using the in-duct special rocket thrust chamber assembly as the principal scramjet fuel injection operation; using the unstowed, covered fan as a duct closure for effecting high area ratio rocket mode operation; and creating a unique airbreathing rocket system via the onboard, cryogenic hydrogen induced air liquefaction process.
NASA Technical Reports Server (NTRS)
Masters, A. I.; Galler, D. E.; Denman, T. F.; Shied, R. A.; Black, J. R.; Fierstein, A. R.; Clark, G. L.; Branstrom, B. R.
1993-01-01
A design and analysis study was conducted to provide advanced engine descriptions and parametric data for space transfer vehicles. The study was based on an advanced oxygen/hydrogen engine in the 7,500 to 50,000 lbf thrust range. Emphasis was placed on defining requirements for high-performance engines capable of achieving reliable and versatile operation in a space environment. Four variations on the expander cycle were compared, and the advantages and disadvantages of each were assessed. Parametric weight, envelope, and performance data were generated over a range of 7,500 to 50,000 lb thrust and a wide range of chamber pressure and nozzle expansion ratio.
Advanced release technologies program
NASA Technical Reports Server (NTRS)
Purdy, Bill
1994-01-01
The objective of the ARTS program was to develop lighter and less expensive spacecraft ordnance and release systems that answer to the requirements of a wide variety of spacecraft applications. These improvements were to be evaluated at the spacecraft system level, as it was determined that there were substantial system-level costs associated with the present ordnance and release subsystems. New, better devices were to be developed, then flight qualified, then integrated into a flight experiment in order to prove the reliability required for their subsequent use on high-reliability spacecraft. The secondary goal of the program was to quantify the system-level benefits of these new subsystems based upon the development program results. Three non-explosive release mechanisms and one laser-diode-based ordnance system were qualified under the program. The release devices being developed were required to release high preloads because it is easier to scale down a release mechanism than to scale it up. The laser initiator developed was required to be a direct replacement for NASA Standard Initiators, since these are the most common initiator in use presently. The program began in October, 1991, with completion of the flight experiment scheduled for February, 1994. This paper provides an overview of the ARTS program, discusses the benefits of using the ARTS components, introduces the new components, compares them with conventional systems and each other, and provides recommendations on how best to implement them.
Non-linear dark energy clustering
Anselmi, Stefano; Ballesteros, Guillermo; Pietroni, Massimo E-mail: ballesteros@pd.infn.it
2011-11-01
We consider a dark energy fluid with arbitrary sound speed and equation of state and discuss the effect of its clustering on the cold dark matter distribution at the non-linear level. We write the continuity, Euler and Poisson equations for the system in the Newtonian approximation. Then, using the time renormalization group method to resum perturbative corrections at all orders, we compute the total clustering power spectrum and matter power spectrum. At the linear level, a sound speed of dark energy different from that of light modifies the power spectrum on observationally interesting scales, such as those relevant for baryonic acoustic oscillations. We show that the effect of varying the sound speed of dark energy on the non-linear corrections to the matter power spectrum is below the per cent level, and therefore these corrections can be well modelled by their counterpart in cosmological scenarios with smooth dark energy. We also show that the non-linear effects on the matter growth index can be as large as 10–15 per cent for small scales.
Phototube non-linearity correction technique
NASA Astrophysics Data System (ADS)
Riboldi, S.; Blasi, N.; Brambilla, S.; Camera, F.; Giaz, A.; Million, B.
2015-06-01
Scintillation light is often detected by photo-multiplier tube (PMT) technology. PMTs are however intrinsically non linear devices, especially when operated with high light yield scintillators and high input photon flux. Many physical effects (e.g. inter-dynode field variation, photocathode resistivity, etc.) can spoil the ideal PMT behavior in terms of gain, ending up in what are addressed as the under-linearity and over-linearity effects. Established techniques implemented in the PMT base (e.g. increasing bleeding current, active voltage divider, etc.) can mitigate these effects, but given the unavoidable spread in manufacturing and materials, it turns out that, with respect to linearity at the percent level, every PMT sample is a story of its own. The residual non linearity is usually accounted for with polynomial correction of the spectrum energy scale, starting from the position of a few known energy peaks of calibration sources, but uncertainly remains in between of calibration peaks. We propose to retrieve the calibration information from the entire energy spectrum and not only the position of full energy peaks (FEP), by means of an automatic procedure that also takes into account the quality (signal/noise ratio) of the information about the non-linearity extracted from the various regions of the spectrum.
Non-linear aeroelastic prediction for aircraft applications
NASA Astrophysics Data System (ADS)
de C. Henshaw, M. J.; Badcock, K. J.; Vio, G. A.; Allen, C. B.; Chamberlain, J.; Kaynes, I.; Dimitriadis, G.; Cooper, J. E.; Woodgate, M. A.; Rampurawala, A. M.; Jones, D.; Fenwick, C.; Gaitonde, A. L.; Taylor, N. V.; Amor, D. S.; Eccles, T. A.; Denley, C. J.
2007-05-01
Current industrial practice for the prediction and analysis of flutter relies heavily on linear methods and this has led to overly conservative design and envelope restrictions for aircraft. Although the methods have served the industry well, it is clear that for a number of reasons the inclusion of non-linearity in the mathematical and computational aeroelastic prediction tools is highly desirable. The increase in available and affordable computational resources, together with major advances in algorithms, mean that non-linear aeroelastic tools are now viable within the aircraft design and qualification environment. The Partnership for Unsteady Methods in Aerodynamics (PUMA) Defence and Aerospace Research Partnership (DARP) was sponsored in 2002 to conduct research into non-linear aeroelastic prediction methods and an academic, industry, and government consortium collaborated to address the following objectives: To develop useable methodologies to model and predict non-linear aeroelastic behaviour of complete aircraft. To evaluate the methodologies on real aircraft problems. To investigate the effect of non-linearities on aeroelastic behaviour and to determine which have the greatest effect on the flutter qualification process. These aims have been very effectively met during the course of the programme and the research outputs include: New methods available to industry for use in the flutter prediction process, together with the appropriate coaching of industry engineers. Interesting results in both linear and non-linear aeroelastics, with comprehensive comparison of methods and approaches for challenging problems. Additional embryonic techniques that, with further research, will further improve aeroelastics capability. This paper describes the methods that have been developed and how they are deployable within the industrial environment. We present a thorough review of the PUMA aeroelastics programme together with a comprehensive review of the relevant research
ERIC Educational Resources Information Center
Schachter, Ron
2008-01-01
The International Baccalaureate may sound like it involves some sort of foreign exchange and a college graduation ceremony, but the IB is actually a comprehensive, demanding, and increasingly popular diploma program for high school juniors and seniors, with a strong academic focus on the world around them. While the IB was created 40 years ago by…
SP-100 Advanced Technology Program
NASA Technical Reports Server (NTRS)
Sovie, Ronald J.
1987-01-01
The goal of the triagency SP-100 Program is to develop long-lived, compact, lightweight, survivable nuclear reactor space power systems for application to the power range 50 kWe to 1 MWe. The successful development of these systems should enable or significantly enhance many of the future NASA civil and commercial missions. The NASA SP-100 Advanced Technology Program strongly augments the parallel SP-100 Ground Engineering System Development program and enhances the chances for success of the overall SP-100 program. The purpose of this paper is to discuss the key technical elements of the Advanced Technology Program and the progress made in the initial year and a half of the project.
ADVANCED TURBINE SYSTEMS PROGRAM
Sy Ali
2002-03-01
The market for power generation equipment is undergoing a tremendous transformation. The traditional electric utility industry is restructuring, promising new opportunities and challenges for all facilities to meet their demands for electric and thermal energy. Now more than ever, facilities have a host of options to choose from, including new distributed generation (DG) technologies that are entering the market as well as existing DG options that are improving in cost and performance. The market is beginning to recognize that some of these users have needs beyond traditional grid-based power. Together, these changes are motivating commercial and industrial facilities to re-evaluate their current mix of energy services. One of the emerging generating options is a new breed of advanced fuel cells. While there are a variety of fuel cell technologies being developed, the solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC) are especially promising, with their electric efficiency expected around 50-60 percent and their ability to generate either hot water or high quality steam. In addition, they both have the attractive characteristics of all fuel cells--relatively small siting footprint, rapid response to changing loads, very low emissions, quiet operation, and an inherently modular design lending itself to capacity expansion at predictable unit cost with reasonably short lead times. The objectives of this project are to:(1) Estimate the market potential for high efficiency fuel cell hybrids in the U.S.;(2) Segment market size by commercial, industrial, and other key markets;(3) Identify and evaluate potential early adopters; and(4) Develop results that will help prioritize and target future R&D investments. The study focuses on high efficiency MCFC- and SOFC-based hybrids and competing systems such as gas turbines, reciprocating engines, fuel cells and traditional grid service. Specific regions in the country have been identified where these
Spin waves cause non-linear friction
NASA Astrophysics Data System (ADS)
Magiera, M. P.; Brendel, L.; Wolf, D. E.; Nowak, U.
2011-07-01
Energy dissipation is studied for a hard magnetic tip that scans a soft magnetic substrate. The dynamics of the atomic moments are simulated by solving the Landau-Lifshitz-Gilbert (LLG) equation numerically. The local energy currents are analysed for the case of a Heisenberg spin chain taken as substrate. This leads to an explanation for the velocity dependence of the friction force: The non-linear contribution for high velocities can be attributed to a spin wave front pushed by the tip along the substrate.
Non-linear Models for Longitudinal Data
Serroyen, Jan; Molenberghs, Geert; Verbeke, Geert; Davidian, Marie
2009-01-01
While marginal models, random-effects models, and conditional models are routinely considered to be the three main modeling families for continuous and discrete repeated measures with linear and generalized linear mean structures, respectively, it is less common to consider non-linear models, let alone frame them within the above taxonomy. In the latter situation, indeed, when considered at all, the focus is often exclusively on random-effects models. In this paper, we consider all three families, exemplify their great flexibility and relative ease of use, and apply them to a simple but illustrative set of data on tree circumference growth of orange trees. PMID:20160890
Non-Linear Dynamics of Saturn's Rings
NASA Astrophysics Data System (ADS)
Esposito, L. W.
2015-10-01
Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible. Results of driven N-body systems by Stuart Robbins: Even unforced rings show large variations; Forcing triggers aggregation; Some limit cycles and phase lags seen, but not always as predicted by predator-prey model. Summary of Halo Results: A predatorprey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw'. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon
Non-Linear Dynamics of Saturn's Rings
NASA Astrophysics Data System (ADS)
Esposito, Larry W.
2015-04-01
Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible Results of driven N-body systems by Stuart Robbins: Even unforced rings show large variations; Forcing triggers aggregation; Some limit cycles and phase lags seen, but not always as predicted by predator-prey model. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw'. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon
DYNAMIC NON LINEAR IMPACT ANALYSIS OF FUEL CASK CONTAINMENT VESSELS
Leduc, D
2008-06-10
Large fuel casks present challenges when evaluating their performance in the accident sequence specified in 10CFR 71. Testing is often limited because of cost, difficulty in preparing test units and the limited availability of facilities which can carry out such tests. In the past, many casks were evaluated without testing using simplified analytical methods. This paper details the use of dynamic non-linear analysis of large fuel casks using advanced computational techniques. Results from the dynamic analysis of two casks, the T-3 Spent Fuel Cask and the Hanford Un-irradiated Fuel Package are examined in detail. These analyses are used to fully evaluate containment vessel stresses and strains resulting from complex loads experienced by cask components during impacts. Importantly, these advanced analytical analyses are capable of examining stresses in key regions of the cask including the cask closure. This paper compares these advanced analytical results with the results of simplified cask analyses like those detailed in NUREG 3966.
Non-Linear Dynamics of Saturn's Rings
NASA Astrophysics Data System (ADS)
Esposito, L. W.
2015-12-01
Non-linear processes can explain why Saturn's rings are so active and dynamic. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw', as observed ny Cassini cameras. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn's rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. This confirms the triple architecture of ring particles: a broad size distribution of particles; these aggregate into temporary rubble piles; coated by a regolith of dust. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from
Non-linear Flood Risk Assessment
NASA Astrophysics Data System (ADS)
Mazzarella, A.
The genesis of floodings is very complex depending on hydrologic, meteorological and evapo-transpirative factors that are linked among themselves in a non linear way with numerous feedback processes. The Cantor dust and the rank-ordering statistics supply a proper framework for identifying a kind of a non linear order in the time succession of the floodings and so provide a basis for their prediction. When a catalogue is analysed, it is necessary to test its completeness with respect to the size of the recorded events and results obtained from analysis of catalogues that do not take into account such a test are suspect and possibly wrong, or, at least, unreliable. Floodings have no instrumentally determined magnitude scale, like that conventionally used for earthquakes, and this is why they are generally described in qualitative terms. For this reason, a semi-quantitative index, called ASI (Alluvial Strength Index) has been here developed that combines attributes of alluvial triggering mechanisms and effects on the territorial and hydraulic system.The historical succession of alluvial events occurred at high valley of Po river (Northern Italy), mean valley of Calore river (Southern Italy) and at Sarno, near Naples, have been accurately reconstructed on the basis of old documents and classified according to their ASI. The catalogues have been verified to be complete only for events classified at least as moderate and this probably because many of the lowest energetic events, especially in the past, escaped the detection. The identification of scale-invariances in the time clustering of alluvial events, both on short and long time scales, even if indicative of the complexity of their genesis, might be very helpful for the assessment and reduction of the hazard of future disasters. For example, on the basis of the results of the rank-ordering statistics, the most probable occurrence of an alluvial event at Sarno, classified at least as strong, is predicted to occur
Support Vector Machines for Non-linear Geophysical Inversion
NASA Astrophysics Data System (ADS)
Kuzma, H. A.; Rector, J. W.
2004-12-01
Classical non-linear geophysical inversion can be simulated using computer learning via Support Vector Machines. Geophysical inverse problems are almost always ill-posed which means that many different models (i.e. descriptions of the earth) can be found to explain a given noisy or incomplete data set. Regularization and constraints encourage inversions to find physically realistic models. The set of preferred models needs to be defined a priori using as much geologic knowledge as is available. In inversion, it is assumed that data and a forward modeling process is known. The goal is to solve for a model. In the SVM paradigm, a series of models and associated data are known. The goal is to solve for a reverse modeling process. Starting with a series of initial models assembled using all available geologic information, synthetic data is created using the most realistic forward modeling program available. With the synthetic data as inputs and the known models as outputs, a Support Vector Machine is trained to approximate a local inverse to the forward modeling program. The advantages of this approach are that it is honest about the need to establish, a priori, the kinds of models that are reasonable in a particular field situation. There is no need to adjust the forward process to accommodate inversion, because SVMs can be easily modified to capture complicated, non-linear relationships. SVMs are transparent and require very little programming. If an SVM is trained using model/data pairs that are drawn from the same probability distribution that is implicit in the regularization of an inversion, then it will get very similar results to the inversion. Because SVMs can interpret as much data as desired so long as the conditions of an experiment do not change, they can be used to perform otherwise computationally expensive procedures. Support Vector Machines are trained to emulate non-linear seismic Amplitude Variation with Offset (AVO) inversions, gravity inversions
Advanced expander test bed program
NASA Technical Reports Server (NTRS)
Masters, A. I.; Mitchell, J. C.
1991-01-01
The Advanced Expander Test Bed (AETB) is a key element in NASA's Chemical Transfer Propulsion Program for development and demonstration of expander cycle oxygen/hydrogen engine technology component technology for the next space engine. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced missions focused components and new health monitoring techniques. The split-expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust.
Advanced expander test bed program
NASA Technical Reports Server (NTRS)
Riccardi, D. P.; Mitchell, J. C.
1993-01-01
The Advanced Expander Test Bed (AETB) is a key element in NASA's Space Chemical Engine Technology Program for development and demonstration of expander cycle oxygen/hydrogen engine and advanced component technologies applicable to space engines as well as launch vehicle upper stage engines. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced mission focused components and new health monitoring techniques in an engine system environment. The split expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust. Contract work began 27 Apr. 1990. During 1992, a major milestone was achieved with the review of the final design of the oxidizer turbopump in Sep. 1992.
Optimal feedback control of strongly non-linear systems excited by bounded noise
NASA Astrophysics Data System (ADS)
Zhu, W. Q.; Huang, Z. L.; Ko, J. M.; Ni, Y. Q.
2004-07-01
A strategy for non-linear stochastic optimal control of strongly non-linear systems subject to external and/or parametric excitations of bounded noise is proposed. A stochastic averaging procedure for strongly non-linear systems under external and/or parametric excitations of bounded noise is first developed. Then, the dynamical programming equation for non-linear stochastic optimal control of the system is derived from the averaged Itô equations by using the stochastic dynamical programming principle and solved to yield the optimal control law. The Fokker-Planck-Kolmogorov equation associated with the fully completed averaged Itô equations is solved to give the response of optimally controlled system. The application and effectiveness of the proposed control strategy are illustrated with the control of cable vibration in cable-stayed bridges and the feedback stabilization of the cable under parametric excitation of bounded noise.
Advanced Rotorcraft Transmission program summary
NASA Astrophysics Data System (ADS)
Bossler, Robert B., Jr.; Heath, Gregory F.
1992-07-01
The current status of the Advanced Rotorcraft Transmission (ART) program is reviewed. The discussion includes a general configuration and face gear description, weight analysis, stress analysis, reliability analysis, acoustic analysis, face gear testing, and planned torque split testing. Design descriptions include the face gear webs sized for equal stiffness, a positive engagement clutch, the lubrication system, and a high contact ratio planetary. Test results for five gear materials and three housing materials are presented.
Advanced Rotorcraft Transmission (ART) program
NASA Technical Reports Server (NTRS)
Heath, Gregory F.; Bossler, Robert B., Jr.
1993-01-01
Work performed by the McDonnell Douglas Helicopter Company and Lucas Western, Inc. within the U.S. Army/NASA Advanced Rotorcraft Transmission (ART) Program is summarized. The design of a 5000 horsepower transmission for a next generation advanced attack helicopter is described. Government goals for the program were to define technology and detail design the ART to meet, as a minimum, a weight reduction of 25 percent, an internal noise reduction of 10 dB plus a mean-time-between-removal (MTBR) of 5000 hours compared to a state-of-the-art baseline transmission. The split-torque transmission developed using face gears achieved a 40 percent weight reduction, a 9.6 dB noise reduction and a 5270 hour MTBR in meeting or exceeding the above goals. Aircraft mission performance and cost improvements resulting from installation of the ART would include a 17 to 22 percent improvement in loss-exchange ratio during combat, a 22 percent improvement in mean-time-between-failure, a transmission acquisition cost savings of 23 percent of $165K, per unit, and an average transmission direct operating cost savings of 33 percent, or $24K per flight hour. Face gear tests performed successfully at NASA Lewis are summarized. Also, program results of advanced material tooth scoring tests, single tooth bending tests, Charpy impact energy tests, compact tension fracture toughness tests and tensile strength tests are summarized.
Advanced gas turbine systems program
Zeh, C.M.
1995-06-01
The U.S. Department of Energy (DOE) is sponsoring a program to develop fuel-efficient gas turbine-based power systems with low emissions. DOE`s Office of Fossil Energy (DOE/FE) and Office of Energy Efficiency and Renewable Energy (DOE/EE) have initiated an 8-year program to develop high-efficiency, natural gas-fired advanced gas turbine power systems. The Advanced Turbine Systems (ATS) Program will support full-scale prototype demonstration of both industrial- and utility-scale systems that will provide commercial marketplace entries by the year 2000. When the program targets are met, power system emissions will be lower than from the best technology in use today. Efficiency of the utility-scale units will be greater than 60 percent on a lower heating value basis, and emissions of carbon dioxide will be reduced inversely with this increase. Industrial systems will also see an improvement of at least 15 percent in efficiency. Nitrogen oxides will be reduced by at least 10 percent, and carbon monoxide and hydrocarbon emissions will each be kept below 20 parts per million, for both utility and industrial systems.
Non-Linear Electrohydrodynamics in Microfluidic Devices
Zeng, Jun
2011-01-01
Since the inception of microfluidics, the electric force has been exploited as one of the leading mechanisms for driving and controlling the movement of the operating fluid and the charged suspensions. Electric force has an intrinsic advantage in miniaturized devices. Because the electrodes are placed over a small distance, from sub-millimeter to a few microns, a very high electric field is easy to obtain. The electric force can be highly localized as its strength rapidly decays away from the peak. This makes the electric force an ideal candidate for precise spatial control. The geometry and placement of the electrodes can be used to design electric fields of varying distributions, which can be readily realized by Micro-Electro-Mechanical Systems (MEMS) fabrication methods. In this paper, we examine several electrically driven liquid handling operations. The emphasis is given to non-linear electrohydrodynamic effects. We discuss the theoretical treatment and related numerical methods. Modeling and simulations are used to unveil the associated electrohydrodynamic phenomena. The modeling based investigation is interwoven with examples of microfluidic devices to illustrate the applications. PMID:21673912
Non-linear electrohydrodynamics in microfluidic devices.
Zeng, Jun
2011-01-01
Since the inception of microfluidics, the electric force has been exploited as one of the leading mechanisms for driving and controlling the movement of the operating fluid and the charged suspensions. Electric force has an intrinsic advantage in miniaturized devices. Because the electrodes are placed over a small distance, from sub-millimeter to a few microns, a very high electric field is easy to obtain. The electric force can be highly localized as its strength rapidly decays away from the peak. This makes the electric force an ideal candidate for precise spatial control. The geometry and placement of the electrodes can be used to design electric fields of varying distributions, which can be readily realized by Micro-Electro-Mechanical Systems (MEMS) fabrication methods. In this paper, we examine several electrically driven liquid handling operations. The emphasis is given to non-linear electrohydrodynamic effects. We discuss the theoretical treatment and related numerical methods. Modeling and simulations are used to unveil the associated electrohydrodynamic phenomena. The modeling based investigation is interwoven with examples of microfluidic devices to illustrate the applications. PMID:21673912
Image enhancement by non-linear extrapolation in frequency space
NASA Technical Reports Server (NTRS)
Anderson, Charles H. (Inventor); Greenspan, Hayit K. (Inventor)
1998-01-01
An input image is enhanced to include spatial frequency components having frequencies higher than those in an input image. To this end, an edge map is generated from the input image using a high band pass filtering technique. An enhancing map is subsequently generated from the edge map, with the enhanced map having spatial frequencies exceeding an initial maximum spatial frequency of the input image. The enhanced map is generated by applying a non-linear operator to the edge map in a manner which preserves the phase transitions of the edges of the input image. The enhanced map is added to the input image to achieve a resulting image having spatial frequencies greater than those in the input image. Simplicity of computations and ease of implementation allow for image sharpening after enlargement and for real-time applications such as videophones, advanced definition television, zooming, and restoration of old motion pictures.
ADVANCED EMISSIONS CONTROL DEVELOPMENT PROGRAM
G.A. Farthing
2001-02-06
The primary objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (HAPs, or air toxics) from coal-fired boilers. The project goal is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPs), fabric filters (baghouses), and wet flue gas desulfurization (WFGD) systems. Development work initially concentrated on the capture of trace metals, fine particulate, hydrogen chloride, and hydrogen fluoride. Recent work has focused almost exclusively on the control of mercury emissions.
Advanced Emissions Control Development Program
G. A. Farthing; G. T. Amrhein; G. A. Kudlac; D. A. Yurchison; D. K. McDonald; M. G. Milobowski
2001-03-31
The primary objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (HAPs, or air toxics) from coal-fired boilers. This objective is being met by identifying ways to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPs), fabric filters (fabric filters), and wet flue gas desulfurization (wet FGD) systems. Development work initially concentrated on the capture of trace metals, hydrogen chloride, and hydrogen fluoride. Recent work has focused almost exclusively on the control of mercury emissions.
Advanced Transport Operating Systems Program
NASA Technical Reports Server (NTRS)
White, John J.
1990-01-01
NASA-Langley's Advanced Transport Operating Systems Program employs a heavily instrumented, B 737-100 as its Transport Systems Research Vehicle (TRSV). The TRSV has been used during the demonstration trials of the Time Reference Scanning Beam Microwave Landing System (TRSB MLS), the '4D flight-management' concept, ATC data links, and airborne windshear sensors. The credibility obtainable from successful flight test experiments is often a critical factor in the granting of substantial commitments for commercial implementation by the FAA and industry. In the case of the TRSB MLS, flight test demonstrations were decisive to its selection as the standard landing system by the ICAO.
NASA Technical Reports Server (NTRS)
Manning, Robert M.
1991-01-01
The dynamic and composite nature of propagation impairments that are incurred on Earth-space communications links at frequencies in and above 30/20 GHz Ka band, i.e., rain attenuation, cloud and/or clear air scintillation, etc., combined with the need to counter such degradations after the small link margins have been exceeded, necessitate the use of dynamic statistical identification and prediction processing of the fading signal in order to optimally estimate and predict the levels of each of the deleterious attenuation components. Such requirements are being met in NASA's Advanced Communications Technology Satellite (ACTS) Project by the implementation of optimal processing schemes derived through the use of the Rain Attenuation Prediction Model and nonlinear Markov filtering theory.
Advanced Emissions Control Development Program
A.P.Evans; K.E. Redinger; M.J. Holmes
1998-04-01
The objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W).
Developing a career advancement program.
Pinette, Shirley L
2003-01-01
Have you ever asked yourself, "What will I be doing five or ten years from now?" "Will I be doing the same thing I'm doing right now?" How would you feel if the answer were "yes"? I often wonder if any of my employees think the same thing. If they do, and the answer is "yes," just how does that make them feel? A day's work for managers can run the gamut--from billing and coding, to patient issues, to staff performance reviews, to CQI, to JCAHO-just to name a few. We're NEVER bored. Can we say the same of our employees, or do they do the same thing day in and day out? If so, it's no wonder that attitudes may become negative and motivation and productivity may decline. What are we as healthcare managers and administrators doing to value and continually train our employees so that staff morale, productivity and patient satisfaction remain high? What are we doing to keep those highly motivated employees motivated and challenged so that they don't get bored and want to move across town to our neighboring hospital or healthcare center? What are we doing to stop our employees from developing the "same job, different day" attitude? A Career Ladder program holds many benefits and opportunities for the motivated employee who seeks and needs additional challenges on the job. It affords them opportunities to learn new skills, demonstrate initiative, accept additional responsibilities and possibly advance into new positions. It also affords them opportunities to grow, to be challenged and to feel like an important and valued member of the radiology team and radiology department. For the manager, a Career Ladder program affords opportunities to retain valuable employees, attract new high-quality employees and maintain a workforce of well-trained highly motivated employees, which in turn will provide high quality products and services to our customers. A Career Ladder program is a "win-win" situation for everyone. For the last twelve months, I have been working with other
Predictability of extremes in non-linear hierarchically organized systems
NASA Astrophysics Data System (ADS)
Kossobokov, V. G.; Soloviev, A.
2011-12-01
phenomena of highly complex origin, by their nature, implies using problem oriented methods, which design breaks the limits of classical statistical or econometric applications. The unambiguously designed forecast/prediction algorithms of the "yes or no" variety, analyze the observable quantitative integrals and indicators available to a given date, then provides unambiguous answer to the question whether a critical transition should be expected or not in the next time interval. Since the predictability of an originating non-linear dynamical system is limited in principle, the probabilistic component of forecast/prediction algorithms is represented by the empirical probabilities of alarms, on one side, and failures-to-predict, on the other, estimated on control sets achieved in the retro- and prospective experiments. Predicting in advance is the only decisive test of forecast/predictions and the relevant on-going experiments are conducted in the case seismic extremes, recessions, and increases of unemployment rate. The results achieved in real-time testing keep being encouraging and confirm predictability of the extremes.
Non-linear interaction of elastic waves in rocks
NASA Astrophysics Data System (ADS)
Kuvshinov, B. N.; Smit, T. J. H.; Campman, X. H.
2013-09-01
We study theoretically the interaction of elastic waves caused by non-linearities of rock elastic moduli, and assess the possibility to use this phenomenon in hydrocarbon exploration and in the analysis of rock samples. In our calculations we use the five-constant model by Gol'dberg. It is shown that the interaction of plane waves in isotropic solids is completely described by five coupling coefficients, which have the same order of magnitude. By considering scattering of compressional waves generated by controlled sources at the Earth surface from a non-linear layer at the subsurface, we conclude that non-linear signals from deep formations are unlikely to be measured with the current level of technology. Our analysis of field tests where non-linear signals were measured, suggests that these signals are generated either in the shallow subsurface or in the vicinity of sources. Non-linear wave interaction might be observable in lab tests with focused ultrasonic beams. In this case, the non-linear response is generated in the secondary parametric array formed by linear beams scattered from inclusions. Although the strength of this response is controlled by non-linearity of the surrounding medium rather than by non-linearity of inclusions, its measurement can help to obtain better images of rock samples.
Employment of CB models for non-linear dynamic analysis
NASA Technical Reports Server (NTRS)
Klein, M. R. M.; Deloo, P.; Fournier-Sicre, A.
1990-01-01
The non-linear dynamic analysis of large structures is always very time, effort and CPU consuming. Whenever possible the reduction of the size of the mathematical model involved is of main importance to speed up the computational procedures. Such reduction can be performed for the part of the structure which perform linearly. Most of the time, the classical Guyan reduction process is used. For non-linear dynamic process where the non-linearity is present at interfaces between different structures, Craig-Bampton models can provide a very rich information, and allow easy selection of the relevant modes with respect to the phenomenon driving the non-linearity. The paper presents the employment of Craig-Bampton models combined with Newmark direct integration for solving non-linear friction problems appearing at the interface between the Hubble Space Telescope and its solar arrays during in-orbit maneuvers. Theory, implementation in the FEM code ASKA, and practical results are shown.
Advanced automotive diesel assessment program
NASA Technical Reports Server (NTRS)
Sekar, R.; Tozzi, L.
1983-01-01
Cummins Engine Company completed an analytical study to identify an advanced automotive (light duty) diesel (AAD) power plant for a 3,000-pound passenger car. The study resulted in the definition of a revolutionary diesel engine with several novel features. A 3,000-pound car with this engine is predicted to give 96.3, 72.2, and 78.8 MPG in highway, city, and combined highway-city driving, respectively. This compares with current diesel powered cars yielding 41.7, 35.0, and 37.7 MPG. The time for 0-60 MPH acceleration is 13.9 sec. compared to the baseline of 15.2 sec. Four technology areas were identified as crucial in bringing this concept to fruition. They are: (1) part-load preheating, (2) positive displacement compounding, (3) spark assisted diesel combustion system, and (4) piston development for adiabatic, oilless diesel engine. Marketing and planning studies indicate that an aggressive program with significant commitment could result in a production car in 10 years from the date of commencement.
Analysis of non-linearity in differential wavefront sensing technique.
Duan, Hui-Zong; Liang, Yu-Rong; Yeh, Hsien-Chi
2016-03-01
An analytical model of a differential wavefront sensing (DWS) technique based on Gaussian Beam propagation has been derived. Compared with the result of the interference signals detected by quadrant photodiode, which is calculated by using the numerical method, the analytical model has been verified. Both the analytical model and numerical simulation show milli-radians level non-linearity effect of DWS detection. In addition, the beam clipping has strong influence on the non-linearity of DWS. The larger the beam clipping is, the smaller the non-linearity is. However, the beam walking effect hardly has influence on DWS. Thus, it can be ignored in laser interferometer. PMID:26974079
Advances by the Integral Fast Reactor Program
Lineberry, M.J.; Pedersen, D.R.; Walters, L.C.; Cahalan, J.E.
1991-01-01
The advances by the Integral Fast Reactor Program at Argonne National Laboratory are the subject of this paper. The Integral Fast Reactor (IFR) is an advanced liquid-metal-cooled reactor concept being developed at Argonne National Laboratory. The advances stressed in the paper include fuel irradiation performance, improved passive safety, and the development of a prototype fuel cycle facility. 14 refs.
Organic non-linear optics and opto-electronics
NASA Astrophysics Data System (ADS)
Maldonado, J. L.; Ramos-Ortíz, G.; Rodríguez, M.; Meneses-Nava, M. A.; Barbosa-García, O.; Santillán, R.; Farfán, N.
2010-12-01
π-conjugated organic molecules and polymers are of great importance in physics, chemistry, material science and engineering. It is expected that, in the near future, organic materials will find widespread use in many technological applications. In the case of organic opto-electronic systems, the list of devices includes light emitting diodes (OLEDs), photovoltaic cells (OPVs), field-effect transistors (OFET), photorefractive materials for light manipulation, among others. These materials are also used for photonic applications: all-optical switching, modulators, optical correlators, plastic waveguides, all polymeric integrated circuits, solid-state lasers, and for biophotonic applications as in the case of the development of organic labels for multiphoton microscopy and photodynamic therapy. The advances in the developing of organic compounds with better mechanical, electrical, and optical (linear and non-linear) characteristics are of a great importance for this field. Here, we present the research on this area carried out at the Centro de Investigaciones en Óp-tica (CIO), in collaboration with Chemistry Departments of different institutions. This work focuses on the optical characterization of materials through several techniques such as TOF, FWM, TBC, THG Maker Fringes, HRS, Z-scan, and TPEF. Additionally, some applications, such as dynamic holography by using photorefractive polymers, and OPVs cells will be discussed.
Influence of shear in the non-linear analysis of RC members
Diotallevi, Pier Paolo; Landi, Luca; Cardinetti, Filippo
2008-07-08
The purpose of this study is to develop an analytical model characterized by a beam-column finite element which is able to reproduce the non-linear flexural-shear behavior of RC structures. The paper shows a brief description of the finite element formulation, the theory used for modeling the constitutive relationship and the scheme of the algorithm, transformed in a computer program, which was developed for implementing the theoretical model. Finally it illustrates a comparison with available experimental results for the calibration and validation of the model and a study on the influence of the non-linear shear response.
Advanced turbocharger design study program
NASA Technical Reports Server (NTRS)
Culy, D. G.; Heldenbrand, R. W.; Richardson, N. R.
1984-01-01
The advanced Turbocharger Design Study consisted of: (1) the evaluation of three advanced engine designs to determine their turbocharging requirements, and of technologies applicable to advanced turbocharger designs; (2) trade-off studies to define a turbocharger conceptual design and select the engine with the most representative requirements for turbocharging; (3) the preparation of a turbocharger conceptual design for the Curtiss Wright RC2-32 engine selected in the trade-off studies; and (4) the assessment of market impact and the preparation of a technology demonstration plan for the advanced turbocharger.
Asymptotic Stability of Interconnected Passive Non-Linear Systems
NASA Technical Reports Server (NTRS)
Isidori, A.; Joshi, S. M.; Kelkar, A. G.
1999-01-01
This paper addresses the problem of stabilization of a class of internally passive non-linear time-invariant dynamic systems. A class of non-linear marginally strictly passive (MSP) systems is defined, which is less restrictive than input-strictly passive systems. It is shown that the interconnection of a non-linear passive system and a non-linear MSP system is globally asymptotically stable. The result generalizes and weakens the conditions of the passivity theorem, which requires one of the systems to be input-strictly passive. In the case of linear time-invariant systems, it is shown that the MSP property is equivalent to the marginally strictly positive real (MSPR) property, which is much simpler to check.
Dilatonic non-linear sigma models and Ricci flow extensions
NASA Astrophysics Data System (ADS)
Carfora, M.; Marzuoli, A.
2016-09-01
We review our recent work describing, in terms of the Wasserstein geometry over the space of probability measures, the embedding of the Ricci flow in the renormalization group flow for dilatonic non-linear sigma models.
Stochastic differential equations for non-linear hydrodynamics
NASA Astrophysics Data System (ADS)
Español, Pep
1998-02-01
We formulate the stochastic differential equations for non-linear hydrodynamic fluctuations. The equations incorporate the random forces through a random stres tensor and random heat flux as in the Landau and Lifshitz theory. However, the equations are non-linear and the random forces are non-Gaussian. We provide explicit expressions for these random quantities in terms of the well-defined increments of the Wienner process.
Advanced lab initiatives: building on a rich diversity of programs and experiments
NASA Astrophysics Data System (ADS)
Peterson, Richard
2009-04-01
The intermediate and advanced lab experience plays a critical role in preparing physics undergraduates for a diversity of careers and graduate school options. During the last few years AAPT, APS, and ALPhA (Advanced Laboratory Physics Association - http://www.advlab.org/) have been working together to invigorate these programs and to help network their instructors -- including a 2009 2.5-day advanced lab topical conference at the University of Michigan 7/23-7/25 (http://advlabs.aapt.org/). Project oriented labs incorporating applications in engineering, acoustics, fluids, optical metrology and diagnostics, non-linear dynamics, biophysics, and nanoscience can play a broadly motivating role for students planning on REU or graduate work in applied physics areas. Experimental examples highlighted here include studies of mechanical resonance and shock wave phenomena utilizing holographic, Schlieren, and interferometric diagnostics -- often in conjunction with MATLAB and COMSOL computational work.
NASA Astrophysics Data System (ADS)
HARRAS, B.; BENAMAR, R.; WHITE, R. G.
2002-04-01
The geometrically non-linear free vibration of thin composite laminated plates is investigated by using a theoretical model based on Hamilton's principle and spectral analysis previously applied to obtain the non-linear mode shapes and resonance frequencies of thin straight structures, such as beams, plates and shells (Benamar et al. 1991Journal of Sound and Vibration149 , 179-195; 1993, 164, 295-316; 1990 Proceedings of the Fourth International Conference on Recent Advances in Structural Dynamics, Southampton; Moussaoui et al. 2000 Journal of Sound and Vibration232, 917-943 [1-4]). The von Kármán non-linear strain-displacement relationships have been employed. In the formulation, the transverse displacement W of the plate mid-plane has been taken into account and the in-plane displacements U and V have been neglected in the non-linear strain energy expressions. This assumption, quite often made in the literature has been adopted in reference [2] and (El Kadiri et al. 1999 Journal of Sound and Vibration228, 333-358 [5]), in the isotropic case and has been mentioned here because the results obtained have been found to be in very good agreement with those based on the hierarchical finite element method (HFEM). In a previous study, it was assumed, based on the analogy with the isotropic case, that the fundamental carbon fibre reinforced plastic (CFRP) plate non-linear mode shape could be well estimated, by using nine plate functions, obtained as products of clamped-clamped beam functions in the x and y directions, symmetric in both the length U001and width directions [3]. In the present work, a convergence study has been performed and has shown that, although such an assumption may yield a good estimate for the non-linear resonance frequency, 18 plate functions should be taken into account instead of nine in the first non-linear mode shape and associated bending stress patterns calculations. This allows the anisotropy induced by the fibre orientations to be taken
Advanced Industrial Materials (AIM) fellowship program
McCleary, D.D.
1997-04-01
The Advanced Industrial Materials (AIM) Program administers a Graduate Fellowship Program focused toward helping students who are currently under represented in the nation`s pool of scientists and engineers, enter and complete advanced degree programs. The objectives of the program are to: (1) establish and maintain cooperative linkages between DOE and professors at universities with graduate programs leading toward degrees or with degree options in Materials Science, Materials Engineering, Metallurgical Engineering, and Ceramic Engineering, the disciplines most closely related to the AIM Program at Oak Ridge National Laboratory (ORNL); (2) strengthen the capabilities and increase the level of participation of currently under represented groups in master`s degree programs, and (3) offer graduate students an opportunity for practical research experience related to their thesis topic through the three-month research assignment or practicum at ORNL. The program is administered by the Oak Ridge Institute for Science and Education (ORISE).
Correcting the NICMOS count-rate dependent non-linearity
NASA Astrophysics Data System (ADS)
de Jong, Roelof S.
2006-03-01
We describe a routine to correct NICMOS imaging data for the NICMOS count-rate dependent non-linearity recently discovered by Bohlin et al. (2005) and quantified by deJong et al. (2006) and Bohlin et al. (2006). The routine has been implemented in the python scripting language and is callable from the shell command line and from iraf. The routine corrects NICMOS count-rate images assuming the non-linearity follows a powerlaw behavior. The wavelength dependence of the non-linearity is interpolated between the measured points of de Jong et al. (2006) and Bohlin et al. (2006) if necessary. The count rates in the output images are modified and hence the standard NICMOS calibration zero-points are no longer valid. New calibration zero-points have been derived from standard star images corrected with the routine. The routine was tested on the lamp-on/off data used in de Jong et al. (2006) to measure the non-linearity effect. We apply the correction to the NGC1850 stellar cluster field and the Hubble Ultra Deep Field (HUDF) to show the magnitude offsets expected due to the non-linearity on objects with a range in luminosity and surface brightness.
Finite element modelling of non-linear magnetic circuits using Cosmic NASTRAN
NASA Technical Reports Server (NTRS)
Sheerer, T. J.
1986-01-01
The general purpose Finite Element Program COSMIC NASTRAN currently has the ability to model magnetic circuits with constant permeablilities. An approach was developed which, through small modifications to the program, allows modelling of non-linear magnetic devices including soft magnetic materials, permanent magnets and coils. Use of the NASTRAN code resulted in output which can be used for subsequent mechanical analysis using a variation of the same computer model. Test problems were found to produce theoretically verifiable results.
Ghost Dark Energy with Non-Linear Interaction Term
NASA Astrophysics Data System (ADS)
Ebrahimi, E.
2016-06-01
Here we investigate ghost dark energy (GDE) in the presence of a non-linear interaction term between dark matter and dark energy. To this end we take into account a general form for the interaction term. Then we discuss about different features of three choices of the non-linear interacting GDE. In all cases we obtain equation of state parameter, w D = p/ ρ, the deceleration parameter and evolution equation of the dark energy density parameter (Ω D ). We find that in one case, w D cross the phantom line ( w D < -1). However in two other classes w D can not cross the phantom divide. The coincidence problem can be solved in these models completely and there exist good agreement between the models and observational values of w D , q. We study squared sound speed {vs2}, and find that for one case of non-linear interaction term {vs2} can achieves positive values at late time of evolution.
Theoretical studies for novel non-linear optical crystals
NASA Astrophysics Data System (ADS)
Wu, Kechen; Chen, Chuangtian
1996-09-01
To fulfil the "molecular engineering" of non-linear optical crystals, two theoretical models suitable respectively for the studies of the absorption edge and birefringence of a non-linear optical crystal have been set up. Molecular quantum chemical methods have been adopted in the systematic calculations of some typical crystals. DV-SCM-X α methods have been used to calculate the absorption edge on the UV side of BBO, LBO, KB5, KDP, Na 2SbF 5, Ba 2TiSi 2O 8, iodate and NaNO 2 crystals. Ab initio methods have been adopted to study the birefringence of NaNO 2, BBO, LiIO 3 and urea crystals. All the theoretical results agreed well with the experimental values. The relationship between structure and properties has been discussed. The results will be helpful to the search for novel non-linear optical crystals.
Non-Linear Vibration Characteristics of Clamped Laminated Shallow Shells
NASA Astrophysics Data System (ADS)
ABE, A.; KOBAYASHI, Y.; YAMADA, G.
2000-07-01
This paper examines non-linear free vibration characteristics of first and second vibration modes of laminated shallow shells with rigidly clamped edges. Non-linear equations of motion for the shells based on the first order shear deformation and classical shell theories are derived by means of Hamilton's principle. We apply Galerkin's procedure to the equations of motion in which eigenvectors for first and second modes of linear vibration obtained by the Ritz method are employed as trial functions. Then simultaneous non-linear ordinary differential equations are derived in terms of amplitudes of the first and second vibration modes. Backbone curves for the first and second vibration modes are solved numerically by the Gauss-Legendre integration method and the shooting method respectively. The effects of lamination sequences and transverse shear deformation on the behavior are discussed. It is also shown that the motion of the first vibration mode affects the response for the second vibration mode.
Non-linear dynamic analysis of anisotropic cylindrical shells
Lakis, A.A.; Selmane, A.; Toledano, A.
1996-12-01
A theory to predict the influence of geometric non-linearities on the natural frequencies of an empty anisotropic cylindrical shell is presented in this paper. It is a hybrid of finite element and classical thin shell theories. Sanders-Koiter non-linear and strain-displacement relations are used. Displacement functions are evaluated using linearized equations of motion. Modal coefficients are then obtained for these displacement functions. Expressions for the mass, linear and non-linear stiffness matrices are derived through the finite element method. The uncoupled equations are solved with the help of elliptic functions. The period and frequency variations are first determined as a function of shell amplitudes and then compared with the results in the literature.
Non-linear system identification in flow-induced vibration
Spanos, P.D.; Zeldin, B.A.; Lu, R.
1996-12-31
The paper introduces a method of identification of non-linear systems encountered in marine engineering applications. The non-linearity is accounted for by a combination of linear subsystems and known zero-memory non-linear transformations; an equivalent linear multi-input-single-output (MISO) system is developed for the identification problem. The unknown transfer functions of the MISO system are identified by assembling a system of linear equations in the frequency domain. This system is solved by performing the Cholesky decomposition of a related matrix. It is shown that the proposed identification method can be interpreted as a {open_quotes}Gram-Schmidt{close_quotes} type of orthogonal decomposition of the input-output quantities of the equivalent MISO system. A numerical example involving the identification of unknown parameters of flow (ocean wave) induced forces on offshore structures elucidates the applicability of the proposed method.
Neural network modelling of non-linear hydrological relationships
NASA Astrophysics Data System (ADS)
Abrahart, R. J.; See, L. M.
2007-09-01
Two recent studies have suggested that neural network modelling offers no worthwhile improvements in comparison to the application of weighted linear transfer functions for capturing the non-linear nature of hydrological relationships. The potential of an artificial neural network to perform simple non-linear hydrological transformations under controlled conditions is examined in this paper. Eight neural network models were developed: four full or partial emulations of a recognised non-linear hydrological rainfall-runoff model; four solutions developed on an identical set of inputs and a calculated runoff coefficient output. The use of different input combinations enabled the competencies of solutions developed on a reduced number of parameters to be assessed. The selected hydrological model had a limited number of inputs and contained no temporal component. The modelling process was based on a set of random inputs that had a uniform distribution and spanned a modest range of possibilities. The initial cloning operations permitted a direct comparison to be performed with the equation-based relationship. It also provided more general information about the power of a neural network to replicate mathematical equations and model modest non-linear relationships. The second group of experiments explored a different relationship that is of hydrological interest; the target surface contained a stronger set of non-linear properties and was more challenging. Linear modelling comparisons were performed against traditional least squares multiple linear regression solutions developed on identical datasets. The reported results demonstrate that neural networks are capable of modelling non-linear hydrological processes and are therefore appropriate tools for hydrological modelling.
BEAM-BASED NON-LINEAR OPTICS CORRECTIONS IN COLLIDERS.
PILAT, R.; LUO, Y.; MALITSKY, N.; PTITSYN, V.
2005-05-16
A method has been developed to measure and correct operationally the non-linear effects of the final focusing magnets in colliders, that gives access to the effects of multi-pole errors by applying closed orbit bumps, and analyzing the resulting tune and orbit shifts. This technique has been tested and used during 4 years of RHIC (the Relativistic Heavy Ion Collider at BNL) operations. I will discuss here the theoretical basis of the method, the experimental set-up, the correction results, the present understanding of the machine model, the potential and limitations of the method itself as compared with other non-linear correction techniques.
Non-linear effects in bunch compressor of TARLA
NASA Astrophysics Data System (ADS)
Yildiz, Hüseyin; Aksoy, Avni; Arikan, Pervin
2016-03-01
Transport of a beam through an accelerator beamline is affected by high order and non-linear effects such as space charge, coherent synchrotron radiation, wakefield, etc. These effects damage form of the beam, and they lead particle loss, emittance growth, bunch length variation, beam halo formation, etc. One of the known non-linear effects on low energy machine is space charge effect. In this study we focus on space charge effect for Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) machine which is designed to drive InfraRed Free Electron Laser covering the range of 3-250 µm. Moreover, we discuss second order effects on bunch compressor of TARLA.
Realization of non-linear coherent states by photonic lattices
Dehdashti, Shahram Li, Rujiang; Chen, Hongsheng; Liu, Jiarui Yu, Faxin
2015-06-15
In this paper, first, by introducing Holstein-Primakoff representation of α-deformed algebra, we achieve the associated non-linear coherent states, including su(2) and su(1, 1) coherent states. Second, by using waveguide lattices with specific coupling coefficients between neighbouring channels, we generate these non-linear coherent states. In the case of positive values of α, we indicate that the Hilbert size space is finite; therefore, we construct this coherent state with finite channels of waveguide lattices. Finally, we study the field distribution behaviours of these coherent states, by using Mandel Q parameter.
Arithmetic coding as a non-linear dynamical system
NASA Astrophysics Data System (ADS)
Nagaraj, Nithin; Vaidya, Prabhakar G.; Bhat, Kishor G.
2009-04-01
In order to perform source coding (data compression), we treat messages emitted by independent and identically distributed sources as imprecise measurements (symbolic sequence) of a chaotic, ergodic, Lebesgue measure preserving, non-linear dynamical system known as Generalized Luröth Series (GLS). GLS achieves Shannon's entropy bound and turns out to be a generalization of arithmetic coding, a popular source coding algorithm, used in international compression standards such as JPEG2000 and H.264. We further generalize GLS to piecewise non-linear maps (Skewed-nGLS). We motivate the use of Skewed-nGLS as a framework for joint source coding and encryption.
Non-linear optics of ultrastrongly coupled cavity polaritons
NASA Astrophysics Data System (ADS)
Crescimanno, Michael; Liu, Bin; McMaster, Michael; Singer, Kenneth
2016-05-01
Experiments at CWRU have developed organic cavity polaritons that display world-record vacuum Rabi splittings of more than an eV. This ultrastrongly coupled polaritonic matter is a new regime for exploring non-linear optical effects. We apply quantum optics theory to quantitatively determine various non-linear optical effects including types of low harmonic generation (SHG and THG) in single and double cavity polariton systems. Ultrastrongly coupled photon-matter systems such as these may be the foundation for technologies including low-power optical switching and computing.
Photocrosslinkable copolymers for non-linear optical applications
Kawatsuki, N.; Pakbaz, K.; Schmidt, H.W.
1993-12-31
New photocrosslinkable copolymers have been synthesized and applied as non-linear optical materials. The copolymers are based on methyl methacrylate, a photo-excitable benzophenone monomer, a non-linear optical active 4`-[(2-hydroxyethyl)ethylamino]-4-nitro-azobenzene (disperse red 1) side chain monomer and a crosslinkable 2-butenyl monomer. These copolymers can be crosslinked by UV light at 366 nm in the poled state and show a stable alignment of NLO chromophore by monitoring the adsorption spectra. The crosslinked and poled film did not change its alignment after storing 4 weeks at room temperature.
Non-Linear Finite Element Modeling of THUNDER Piezoelectric Actuators
NASA Technical Reports Server (NTRS)
Taleghani, Barmac K.; Campbell, Joel F.
1999-01-01
A NASTRAN non-linear finite element model has been developed for predicting the dome heights of THUNDER (THin Layer UNimorph Ferroelectric DrivER) piezoelectric actuators. To analytically validate the finite element model, a comparison was made with a non-linear plate solution using Von Karmen's approximation. A 500 volt input was used to examine the actuator deformation. The NASTRAN finite element model was also compared with experimental results. Four groups of specimens were fabricated and tested. Four different input voltages, which included 120, 160, 200, and 240 Vp-p with a 0 volts offset, were used for this comparison.
The Rock Valley College Career Advancement Program.
ERIC Educational Resources Information Center
Rock Valley Coll., Rockford, IL.
The Career Advancement Program (CAP) is a joint effort by a 2-year college and industrial firms in its district to expand educational opportunities, to match college programs to local needs, and to help industry meet its present and future technical manpower needs. CAP has worked to attract students, full- or part-time, to technical training.…
Programmed electronic advance for engines
Dogadko, P.
1987-03-03
An ignition advance control is described for an internal combustion engine including a crankshaft, a throttle control, and at least one cylinder, the ignition advance control comprising a spark ignition circuit associated with the cylinder and including trigger means operative to cause an ignition spark, means for generating a control pulse associated with the cylinder, latch means for enabling the trigger means in response to generation of the control pulse, means for generating a constant plurality of sequentially occurring electrical reference pulses during each revolution of the crankshaft, means for counting the reference pulses developed during each revolution of the crankshaft, means for firing the enabled trigger means in response to the counting means counting a predetermined number of the reference pulses to cause the ignition spark at a predetermined ignition point in each revolution of the crankshaft, means for sensing the position of the throttle control, and means responsive to the throttle sensing means for varying the predetermined number of reference pulses solely in accordance with the position of the throttle control to vary the predetermined ignition point as appropriate for the position of the throttle control.
Algorithmic advances in stochastic programming
Morton, D.P.
1993-07-01
Practical planning problems with deterministic forecasts of inherently uncertain parameters often yield unsatisfactory solutions. Stochastic programming formulations allow uncertain parameters to be modeled as random variables with known distributions, but the size of the resulting mathematical programs can be formidable. Decomposition-based algorithms take advantage of special structure and provide an attractive approach to such problems. We consider two classes of decomposition-based stochastic programming algorithms. The first type of algorithm addresses problems with a ``manageable`` number of scenarios. The second class incorporates Monte Carlo sampling within a decomposition algorithm. We develop and empirically study an enhanced Benders decomposition algorithm for solving multistage stochastic linear programs within a prespecified tolerance. The enhancements include warm start basis selection, preliminary cut generation, the multicut procedure, and decision tree traversing strategies. Computational results are presented for a collection of ``real-world`` multistage stochastic hydroelectric scheduling problems. Recently, there has been an increased focus on decomposition-based algorithms that use sampling within the optimization framework. These approaches hold much promise for solving stochastic programs with many scenarios. A critical component of such algorithms is a stopping criterion to ensure the quality of the solution. With this as motivation, we develop a stopping rule theory for algorithms in which bounds on the optimal objective function value are estimated by sampling. Rules are provided for selecting sample sizes and terminating the algorithm under which asymptotic validity of confidence interval statements for the quality of the proposed solution can be verified. Issues associated with the application of this theory to two sampling-based algorithms are considered, and preliminary empirical coverage results are presented.
Advanced composite airframe program: Today's technology
NASA Technical Reports Server (NTRS)
Good, Danny E.; Mazza, L. Thomas
1988-01-01
The Advanced Composite Airframe Program (ACAP) was undertaken to demonstrate the advantages of the application of advanced composite materials and structural design concepts to the airframe structure on helicopters designed to stringent military requirements. The primary goals of the program were the reduction of airframe production costs and airframe weight by 17 and 22 percent respectively. The ACAP effort consisted of a preliminary design phase, detail design, and design support testing, full-scale fabrication, laboratory testing, and a ground/flight test demonstration. Since the completion of the flight test demonstration programs follow-on efforts were initiated to more fully evaluate a variety of military characteristics of the composite airframe structures developed under the original ACAP advanced development contracts. An overview of the ACAP program is provided and some of the design features, design support testing, manufacturing approaches, and the results of the flight test evaluation, as well as, an overview of Militarization Test and Evaluation efforts are described.
Rare earth ion doped non linear laser crystals
NASA Astrophysics Data System (ADS)
Jaque, D.; Romero, J. J.; Ramirez, M. O.; Garcia, J. A. S.; de Las Heras, C.; Bausa, L. E.; Sole, J. G.
2003-01-01
We show how non linear crystals activated with Yb3+ or Nd3+ ions can be used to develop diode pumped solid state lasers emitting in the visible region of the electromagnetic spectrum. For this purpose we have selected relevant examples of systems investigated in our laboratory.
Non-linear protocell models: synchronization and chaos
NASA Astrophysics Data System (ADS)
Filisetti, A.; Serra, R.; Carletti, T.; Villani, M.; Poli, I.
2010-09-01
We consider generic protocells models allowing linear and non-linear kinetics for the main involved chemical reactions. We are interested in understanding if and how the protocell division and the metabolism do synchronise to give rise to sustainable evolution of the protocell.
Is 3D true non linear traveltime tomography reasonable ?
NASA Astrophysics Data System (ADS)
Herrero, A.; Virieux, J.
2003-04-01
The data sets requiring 3D analysis tools in the context of seismic exploration (both onshore and offshore experiments) or natural seismicity (micro seismicity surveys or post event measurements) are more and more numerous. Classical linearized tomographies and also earthquake localisation codes need an accurate 3D background velocity model. However, if the medium is complex and a priori information not available, a 1D analysis is not able to provide an adequate background velocity image. Moreover, the design of the acquisition layouts is often intrinsically 3D and renders difficult even 2D approaches, especially in natural seismicity cases. Thus, the solution relies on the use of a 3D true non linear approach, which allows to explore the model space and to identify an optimal velocity image. The problem becomes then practical and its feasibility depends on the available computing resources (memory and time). In this presentation, we show that facing a 3D traveltime tomography problem with an extensive non-linear approach combining fast travel time estimators based on level set methods and optimisation techniques such as multiscale strategy is feasible. Moreover, because management of inhomogeneous inversion parameters is more friendly in a non linear approach, we describe how to perform a jointly non-linear inversion for the seismic velocities and the sources locations.
Non-linear dynamic analysis of geared systems, part 2
NASA Technical Reports Server (NTRS)
Singh, Rajendra; Houser, Donald R.; Kahraman, Ahmet
1990-01-01
A good understanding of the steady state dynamic behavior of a geared system is required in order to design reliable and quiet transmissions. This study focuses on a system containing a spur gear pair with backlash and periodically time-varying mesh stiffness, and rolling element bearings with clearance type non-linearities. A dynamic finite element model of the linear time-invariant (LTI) system is developed. Effects of several system parameters, such as torsional and transverse flexibilities of the shafts and prime mover/load inertias, on free and force vibration characteristics are investigated. Several reduced order LTI models are developed and validated by comparing their eigen solution with the finite element model results. Several key system parameters such as mean load and damping ratio are identified and their effects on the non-linear frequency response are evaluated quantitatively. Other fundamental issues such as the dynamic coupling between non-linear modes, dynamic interactions between component non-linearities and time-varying mesh stiffness, and the existence of subharmonic and chaotic solutions including routes to chaos have also been examined in depth.
Evolution equation for non-linear cosmological perturbations
Brustein, Ram; Riotto, Antonio E-mail: Antonio.Riotto@cern.ch
2011-11-01
We present a novel approach, based entirely on the gravitational potential, for studying the evolution of non-linear cosmological matter perturbations. Starting from the perturbed Einstein equations, we integrate out the non-relativistic degrees of freedom of the cosmic fluid and obtain a single closed equation for the gravitational potential. We then verify the validity of the new equation by comparing its approximate solutions to known results in the theory of non-linear cosmological perturbations. First, we show explicitly that the perturbative solution of our equation matches the standard perturbative solutions. Next, using the mean field approximation to the equation, we show that its solution reproduces in a simple way the exponential suppression of the non-linear propagator on small scales due to the velocity dispersion. Our approach can therefore reproduce the main features of the renormalized perturbation theory and (time)-renormalization group approaches to the study of non-linear cosmological perturbations, with some possibly important differences. We conclude by a preliminary discussion of the nature of the full solutions of the equation and their significance.
Tunneling control using classical non-linear oscillator
Kar, Susmita; Bhattacharyya, S. P.
2014-04-24
A quantum particle is placed in symmetric double well potential which is coupled to a classical non-linear oscillator via a coupling function. With different spatial symmetry of the coupling and under various controlling fashions, the tunneling of the quantum particle can be enhanced or suppressed, or totally destroyed.
Non-linear Langmuir waves in a warm quantum plasma
Dubinov, Alexander E. Kitaev, Ilya N.
2014-10-15
A non-linear differential equation describing the Langmuir waves in a warm quantum electron-ion plasma has been derived. Its numerical solutions of the equation show that ordinary electronic oscillations, similar to the classical oscillations, occur along with small-scale quantum Langmuir oscillations induced by the Bohm quantum force.
Solar Concentrator Advanced Development Program
NASA Technical Reports Server (NTRS)
Knasel, Don; Ehresman, Derik
1989-01-01
The Solar Concentrator Advanced Development Project has successfully designed, fabricated, and tested a full scale prototypical solar dynamic concentrator for space station applications. A Truss Hexagonal Panel reflector was selected as a viable solar concentrator concept to be used for space station applications. This concentrator utilizes a modular design approach and is flexible in attainable flux profiles and assembly techniques. The detailed design of the concentrator, which included structural, thermal and optical analysis, identified the feasibility of the design and specific technologies that were required to fabricate it. The needed surface accuracy of the reflectors surface was found to be very tight, within 5 mrad RMS slope error, and results in very close tolerances for fabrication. To meet the design requirements, a modular structure composed of hexagonal panels was used. The panels, made up of graphite epoxy box beams provided the strength, stiffness and dimensional stability needed. All initial project requirements were met or exceeded by hardware demonstration. Initial testing of structural repeatability of a seven panel portion of the concentrator was followed by assembly and testing of the full nineteen panel structure. The testing, which consisted of theodolite and optical measurements over an assembly-disassembly-reassembly cycle, demonstrated that the concentrator maintained the as-built contour and optical characteristics. The facet development effort within the project, which included developing the vapor deposited reflective facet, produced a viable design with demonstrated optical characteristics that are within the project goals.
Overview of Advanced Turbine Systems Program
NASA Astrophysics Data System (ADS)
Webb, H. A.; Bajura, R. A.
The US Department of Energy initiated a program to develop advanced gas turbine systems to serve both central power and industrial power generation markets. The Advanced Turbine Systems (ATS) Program will lead to commercial offerings by the private sector by 2002. ATS will be developed to fire natural gas but will be adaptable to coal and biomass firing. The systems will be: highly efficient (15 percent improvement over today's best systems); environmentally superior (10 percent reduction in nitrogen oxides over today's best systems); and cost competitive (10 percent reduction in cost of electricity). The ATS Program has five elements. Innovative cycle development will lead to the demonstration of systems with advanced gas turbine cycles using current gas turbine technology. High temperature development will lead to the increased firing temperatures needed to achieve ATS Program efficiency goals. Ceramic component development/demonstration will expand the current DOE/CE program to demonstrate industrial-scale turbines with ceramic components. Technology base will support the overall program by conducting research and development (R&D) on generic technology issues. Coal application studies will adapt technology developed in the ATS program to coal-fired systems being developed in other DOE programs.
Feature Visibility Limits in the Non-Linear Enhancement of Turbid Images
NASA Technical Reports Server (NTRS)
Jobson, Daniel J.; Rahman, Zia-ur; Woodell, Glenn A.
2003-01-01
The advancement of non-linear processing methods for generic automatic clarification of turbid imagery has led us from extensions of entirely passive multiscale Retinex processing to a new framework of active measurement and control of the enhancement process called the Visual Servo. In the process of testing this new non-linear computational scheme, we have identified that feature visibility limits in the post-enhancement image now simplify to a single signal-to-noise figure of merit: a feature is visible if the feature-background signal difference is greater than the RMS noise level. In other words, a signal-to-noise limit of approximately unity constitutes a lower limit on feature visibility.
Advanced Emission Control Development Program.
Evans, A.P.
1997-12-31
Babcock & Wilcox (B&W) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using B&W`s new Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and the inorganic species hydrogen chloride and hydrogen fluoride.
Advanced Emissions Control Development Program
Evans, A P
1998-12-03
Babcock & Wilcox (B&W) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using B&W's new Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and the inorganic species hydrogen chloride and hydrogen fluoride.
Advanced Emissions Control Development Program
M. J. Holmes
1998-12-03
McDermott Technology, Inc. (MTI) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using the Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and hydrogen chloride and hydrogen fluoride.
Advanced Emissions Control Development Program
A. P. Evans
1998-12-03
McDermott Technology, Inc. (MTI) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using the Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and the inorganic species, hydrogen chloride and hydrogen fluoride.
Advanced Rotorcraft Transmission (ART) program summary
NASA Technical Reports Server (NTRS)
Krantz, T. L.; Kish, J. G.
1992-01-01
The Advanced Rotorcraft Transmission (ART) Program was initiated to advance the state of the art for rotorcraft transmissions. The goal of the ART Program was to develop and demonstrate the technologies needed to reduce transmission weight by 25 pct. and reduce noise by 10 dB while obtaining a 5000 hr 'mean time between failure'. The research done under the ART Program is summarized. A split path design was selected as best able to meet the program goals. Key part technologies needed for this design were identified, studied, and developed. Two of these technologies are discussed in detail: the load sharing of split path designs including the use of a compliant elastomeric torque splitter and the application of a high ratio, low pitch line velocity gear mesh. Development of an angular contact spherical roller bearing, transmission error analysis, and fretting fatigue testing are discussed. The technologies for a light weight, quiet, and reliable rotorcraft transmission were demonstrated.
New non-linear photovoltaic effect in uniform bipolar semiconductor
Volovichev, I.
2014-11-21
A linear theory of the new non-linear photovoltaic effect in the closed circuit consisting of a non-uniformly illuminated uniform bipolar semiconductor with neutral impurities is developed. The non-uniform photo-excitation of impurities results in the position-dependant current carrier mobility that breaks the semiconductor homogeneity and induces the photo-electromotive force (emf). As both the electron (or hole) mobility gradient and the current carrier generation rate depend on the light intensity, the photo-emf and the short-circuit current prove to be non-linear functions of the incident light intensity at an arbitrarily low illumination. The influence of the sample size on the photovoltaic effect magnitude is studied. Physical relations and distinctions between the considered effect and the Dember and bulk photovoltaic effects are also discussed.
On the non-linear scale of cosmological perturbation theory
Blas, Diego; Garny, Mathias; Konstandin, Thomas E-mail: mathias.garny@desy.de
2013-09-01
We discuss the convergence of cosmological perturbation theory. We prove that the polynomial enhancement of the non-linear corrections expected from the effects of soft modes is absent in equal-time correlators like the power or bispectrum. We first show this at leading order by resumming the most important corrections of soft modes to an arbitrary skeleton of hard fluctuations. We derive the same result in the eikonal approximation, which also allows us to show the absence of enhancement at any order. We complement the proof by an explicit calculation of the power spectrum at two-loop order, and by further numerical checks at higher orders. Using these insights, we argue that the modification of the power spectrum from soft modes corresponds at most to logarithmic corrections at any order in perturbation theory. Finally, we discuss the asymptotic behavior in the large and small momentum regimes and identify the expansion parameter pertinent to non-linear corrections.
A non-linear model of economic production processes
NASA Astrophysics Data System (ADS)
Ponzi, A.; Yasutomi, A.; Kaneko, K.
2003-06-01
We present a new two phase model of economic production processes which is a non-linear dynamical version of von Neumann's neoclassical model of production, including a market price-setting phase as well as a production phase. The rate of an economic production process is observed, for the first time, to depend on the minimum of its input supplies. This creates highly non-linear supply and demand dynamics. By numerical simulation, production networks are shown to become unstable when the ratio of different products to total processes increases. This provides some insight into observed stability of competitive capitalist economies in comparison to monopolistic economies. Capitalist economies are also shown to have low unemployment.
Non-linear Higgs portal to Dark Matter
NASA Astrophysics Data System (ADS)
Brivio, I.; Gavela, M. B.; Merlo, L.; Mimasu, K.; No, J. M.; del Rey, R.; Sanz, V.
2016-04-01
The Higgs portal to scalar Dark Matter is considered in the context of non-linearly realised electroweak symmetry breaking. We determine the dominant interactions of gauge bosons and the physical Higgs particle h to a scalar singlet Dark Matter candidate. Phenomenological consequences are also studied in detail, including the possibility of distinguishing this scenario from the standard Higgs portal in which the electroweak symmetry breaking is linearly realised. Two features of significant impact are: i) the connection between the electroweak scale v and the Higgs particle departs from the ( v + h) functional dependence, as the Higgs field is not necessarily an exact electroweak doublet; ii) the presence of specific couplings that arise at different order in the non-linear and in the linear expansions. These facts deeply affect the Dark Matter relic abundance, as well as the expected signals in direct and indirect searches and collider phenomenology, where Dark Matter production rates are enhanced with respect to the standard portal.
Non-linear microscopy and spectroscopy of skin tissues
NASA Astrophysics Data System (ADS)
Palero, Jonathan A.; Latouche, Gwendal; de Bruijn, Henri"tte S.; Gerritsen, Hans C.; Sterenborg, Henricus J. C. M.
2005-11-01
We combined a non-linear microscope with a sensitive prism-based spectrograph and employed it for the imaging of the auto fluorescence of skin tissues. The system has a sub-micron spatial resolution and a spectral resolution of better than 5 nm. The spectral images contain signals arising from two-photon excited fluorescence (TPEF) of endogenous fluorophores in the skin and from second harmonic generation (SHG) produced by the collagen fibers, which have non-centrosymmetric structure. Non-linear microscopy has the potential to image deep into optically thick specimens because it uses near-infrared (NIR) laser excitation. In addition, the phototoxicity of the technique is comparatively low. Here, the technique is used for the spectral imaging of unstained skin tissue sections. We were able to image weak cellular autofluorescence as well as strong collagen SHG. The images were analyzed by spectral unmixing and the results exhibit a clear spectral signature for the different skin layers.
Lincoln Advanced Science & Engineering Reinforcement (LASER) Program.
ERIC Educational Resources Information Center
Williams, Willie
The Lincoln Advanced Science and Engineering Reinforcement (LASER) Program at Lincoln University, which has recruited over 100 students for majors in technical fields, is described in this report. To date, over 70% have completed or will complete technical degrees in engineering, physics, chemistry, and computer science. Of those completing the…
NASA/industry advanced turboprop technology program
NASA Technical Reports Server (NTRS)
Ziemianski, Joseph A.; Whitlow, John B., Jr.
1988-01-01
Experimental and analytical effort shows that use of advanced turboprop (propfan) propulsion instead of conventional turbofans in the older narrow-body airline fleet could reduce fuel consumption for this type of aircraft by up to 50 percent. The NASA Advanced Turboprop (ATP) program was formulated to address the key technologies required for these thin, swept-blade propeller concepts. A NASA, industry, and university team was assembled to develop and validate applicable design codes and prove by ground and flight test the viability of these propeller concepts. Some of the history of the ATP Project, an overview of some of the issues, and a summary of the technology developed to make advanced propellers viable in the high-subsonic cruise speed application are presented. The ATP program was awarded the prestigious Robert J. Collier Trophy for the greatest achievement in aeronautics and astronautics in America in 1987.
NASA/industry advanced turboprop technology program
NASA Technical Reports Server (NTRS)
Ziemianski, Joseph A.; Whitlow, John B., Jr.
1988-01-01
Experimental and analytical effort shows that use of advanced turboprop (propfan) propulsion instead of conventional turbofans in the older narrow-body airline fleet could reduce fuel consumption for this type of aircraft by up to 50 percent. The NASA Advanced Turboprop (ATP) program was formulated to address the key technologies required for these thin, swept-blade propeller concepts. A NASA, industry, and university team was assembled to develop and validate applicable design codes and prove by ground and flight test the viability of these propeller concepts. Some of the history of the ATP project, an overview of some of the issues, and a summary of the technology developed to make advanced propellers viable in the high-subsonic cruise speed application are presented. The ATP program was awarded the prestigious Robert J. Collier Trophy for the greatest achievement in aeronautics and astronautics in America in 1987.
Non-linear power spectra in the synchronous gauge
NASA Astrophysics Data System (ADS)
Hwang, Jai-chan; Noh, Hyerim; Jeong, Donghui; Gong, Jinn-Ouk; Biern, Sang Gyu
2015-05-01
We study the non-linear corrections to the matter and velocity power spectra in the synchronous gauge (SG). For the leading correction to the non-linear power spectra, we consider the perturbations up to third order in a zero-pressure fluid in a flat cosmological background. Although the equations in the SG happen to coincide with those in the comoving gauge (CG) to linear order, they differ from second order. In particular, the second order hydrodynamic equations in the SG are apparently in the Lagrangian form, whereas those in the CG are in the Eulerian form. The non-linear power spectra naively presented in the original SG show rather pathological behavior quite different from the result of the Newtonian theory even on sub-horizon scales. We show that the pathology in the nonlinear power spectra is due to the absence of the convective terms in, thus the Lagrangian nature of, the SG. We show that there are many different ways of introducing the corrective convective terms in the SG equations. However, the convective terms (Eulerian modification) can be introduced only through gauge transformations to other gauges which should be the same as the CG to the second order. In our previous works we have shown that the density and velocity perturbation equations in the CG exactly coincide with the Newtonian equations to the second order, and the pure general relativistic correction terms starting to appear from the third order are substantially suppressed compared with the relativistic/Newtonian terms in the power spectra. As a result, we conclude that the SG per se is an inappropriate coordinate choice in handling the non-linear matter and velocity power spectra of the large-scale structure where observations meet with theories.
Liapunov functions for non-linear difference equation stability analysis.
NASA Technical Reports Server (NTRS)
Park, K. E.; Kinnen, E.
1972-01-01
Liapunov functions to determine the stability of non-linear autonomous difference equations can be developed through the use of auxiliary exact difference equations. For this purpose definitions are introduced for the gradient of an implicit function of a discrete variable, a principal sum, a definite sum and an exact difference equation, and a theorem for exactness of a difference form is proved. Examples illustrate the procedure.
Approximate solutions for non-linear iterative fractional differential equations
NASA Astrophysics Data System (ADS)
Damag, Faten H.; Kiliçman, Adem; Ibrahim, Rabha W.
2016-06-01
This paper establishes approximate solution for non-linear iterative fractional differential equations: d/γv (s ) d sγ =ℵ (s ,v ,v (v )), where γ ∈ (0, 1], s ∈ I := [0, 1]. Our method is based on some convergence tools for analytic solution in a connected region. We show that the suggested solution is unique and convergent by some well known geometric functions.
Linear Algebraic Method for Non-Linear Map Analysis
Yu,L.; Nash, B.
2009-05-04
We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a matrix analysis method from linear algebra. Choosing the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of Jordan decomposition which is widely used in conventional linear algebra.
Non-Linear Dynamics and Emergence in Laboratory Fusion Plasmas
NASA Astrophysics Data System (ADS)
Hnat, B.
2011-09-01
Turbulent behaviour of laboratory fusion plasma system is modelled using extended Hasegawa-Wakatani equations. The model is solved numerically using finite difference techniques. We discuss non-linear effects in such a system in the presence of the micro-instabilities, specifically a drift wave instability. We explore particle dynamics in different range of parameters and show that the transport changes from diffusive to non-diffusive when large directional flows are developed.
Non-linear stochastic growth rates and redshift space distortions
Jennings, Elise; Jennings, David
2015-04-09
The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ = ∇ ∙ v(x,t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean <θ|δ>, together with the fluctuations of θ around this mean. We also measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10 per cent at k < 0.2 h Mpc^{-1} to 25 per cent at k ~ 0.45 h Mpc^{-1} at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 10^{12} M_{⊙} h^{-1}, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean <θ|δ> away from the linear theory prediction -f_{LT}δ, where f_{LT }is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) fork < 0.1 h Mpc^{-1}. Furthermore, the stochasticity in the θ – δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of f_{LT} from two-point statistics in redshift space. Furthermore, given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of f_{LT} extracted using models which assume a linear, deterministic expression.
Non-linear stochastic growth rates and redshift space distortions
NASA Astrophysics Data System (ADS)
Jennings, Elise; Jennings, David
2015-06-01
The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ = nabla \\cdot v({x},t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean <θ|δ>, together with the fluctuations of θ around this mean. We measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ˜10 per cent at k < 0.2 h Mpc-1 to 25 per cent at k ˜ 0.45 h Mpc-1 at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 1012 M⊙ h-1, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean <θ|δ> away from the linear theory prediction -fLTδ, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) for k < 0.1 h Mpc-1. The stochasticity in the θ-δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of fLT from two-point statistics in redshift space. Given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.
Non-Linear Dynamics and Emergence in Laboratory Fusion Plasmas
Hnat, B.
2011-09-22
Turbulent behaviour of laboratory fusion plasma system is modelled using extended Hasegawa-Wakatani equations. The model is solved numerically using finite difference techniques. We discuss non-linear effects in such a system in the presence of the micro-instabilities, specifically a drift wave instability. We explore particle dynamics in different range of parameters and show that the transport changes from diffusive to non-diffusive when large directional flows are developed.
Non-linear stochastic growth rates and redshift space distortions
Jennings, Elise; Jennings, David
2015-04-09
The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ = ∇ ∙ v(x,t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean <θ|δ>, together with the fluctuations of θ around this mean. We also measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10 per cent at k < 0.2 h Mpc-1 to 25 per cent at kmore » ~ 0.45 h Mpc-1 at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 1012 M⊙ h-1, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean <θ|δ> away from the linear theory prediction -fLTδ, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) fork < 0.1 h Mpc-1. Furthermore, the stochasticity in the θ – δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of fLT from two-point statistics in redshift space. Furthermore, given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.« less
Non linear identities between unitary minimal Virasoro characters
NASA Astrophysics Data System (ADS)
Taormina, Anne
Non linear identities between unitary minimal Virasoro characters at low levels (m = 3, 4, 5) are presented as well as a sketch of some proofs. The first identity gives the Ising model characters (m = 3) as bilinears in tricritical Ising model characters (m = 4), while the second one gives the tricritical Ising model characters as bilinears in the Ising model characters and the six combinations of m = 5 Virasoro characters which do not appear in the spectrum of the three state Potts model.
Non-linear optics of nano-scale pentacene thin film
NASA Astrophysics Data System (ADS)
Yahia, I. S.; Alfaify, S.; Jilani, Asim; Abdel-wahab, M. Sh.; Al-Ghamdi, Attieh A.; Abutalib, M. M.; Al-Bassam, A.; El-Naggar, A. M.
2016-07-01
We have found the new ways to investigate the linear/non-linear optical properties of nanostructure pentacene thin film deposited by thermal evaporation technique. Pentacene is the key material in organic semiconductor technology. The existence of nano-structured thin film was confirmed by atomic force microscopy and X-ray diffraction. The wavelength-dependent transmittance and reflectance were calculated to observe the optical behavior of the pentacene thin film. It has been observed the anomalous dispersion at wavelength λ < 800 nm, whereas the normal dispersion was found at wavelength λ > 800. The non-linear refractive index of the deposited films was investigated. The linear optical susceptibility of pentacene thin film was calculated, and we observed the non-linear optical susceptibility of pentacene thin film at about 6 × 10-13 esu. The advantage of this work is to use of spectroscopic method to calculate the liner and non-liner optical response of pentacene thin films rather than expensive Z-scan. The calculated optical behavior of the pentacene thin films could be used in the organic thin films base advanced optoelectronic devices such as telecommunications devices.
Non-linear Compton Scattering in Short Laser Pulses
NASA Astrophysics Data System (ADS)
Krajewska, Katarzyna; Kamiński, Jerzy
2012-06-01
The generation of short X-ray laser pulses attracts a great deal of attention. One of mechanisms to achieve this goal is the non-linear Compton scattering at very high laser powers. The majority of previous works on the non-linear Compton scattering have been devoted to the case when the incident laser field is treated as a monochromatic plane wave. There is, however, recent interest in analyzing the effect of a pulsed laser field on the non-linear Compton scattering [1-4]. We study the process for different durations of the incident laser pulse and compare it with the results for both a plane wave laser field and a laser pulse train. [4pt] [1] M. Boca and V. Florescu, Phys. Rev. A 80, 053403 (2009).[0pt] [2] M. Boca and V. Florescu, Eur. Phys. J. D 61, 446 (2011).[0pt] [3] D. Seipt and B. Kämpfer, Phys. Rev. A 83, 022101 (2011).[0pt] [4] F. Mackenroth and A. Di Piazza, Phys. Rev. A 83, 032106 (2011).
Can the Non-linear Ballooning Model describe ELMs?
NASA Astrophysics Data System (ADS)
Henneberg, S. A.; Cowley, S. C.; Wilson, H. R.
2015-11-01
The explosive, filamentary plasma eruptions described by the non-linear ideal MHD ballooning model is tested quantitatively against experimental observations of ELMs in MAST. The equations describing this model were derived by Wilson and Cowley for tokamak-like geometry which includes two differential equations: the linear ballooning equation which describes the spatial distribution along the field lines and the non-linear ballooning mode envelope equation, which is a two-dimensional, non-linear differential equation which can involve fractional temporal-derivatives, but is often second-order in time and space. To employ the second differential equation for a specific geometry one has to evaluate the coefficients of the equation which is non-trivial as it involves field line averaging of slowly converging functions. We have solved this system for MAST, superimposing the solutions of both differential equations and mapping them onto a MAST plasma. Comparisons with the evolution of ELM filaments in MAST will be reported in order to test the model. The support of the EPSRC for the FCDT (Grant EP/K504178/1), of Euratom research and training programme 2014-2018 (No 633053) and of the RCUK Energy Programme [grant number EP/I501045] is gratefully acknowledged.
IPIRG programs - advances in pipe fracture technology
Wilkowski, G.; Olson, R.; Scott, P.
1997-04-01
This paper presents an overview of the advances made in fracture control technology as a result of the research performed in the International Piping Integrity Research Group (IPIRG) program. The findings from numerous experiments and supporting analyses conducted to investigate the behavior of circumferentially flawed piping and pipe systems subjected to high-rate loading typical of seismic events are summarized. Topics to be discussed include; (1) Seismic loading effects on material properties, (2) Piping system behavior under seismic loads, (3) Advances in elbow fracture evaluations, and (4) {open_quotes}Real{close_quotes} piping system response. The presentation for each topic will be illustrated with data and analytical results. In each case, the state-of-the-art in fracture mechanics prior to the first IPIRG program will be contrasted with the state-of-the-art at the completion of the IPIRG-2 program.
A Technique for Determining Non-Linear Circuit Parameters from Ring Down Data
ROMERO, LOUIS; DICKEY, FRED M.; DISON, HOLLY
2003-01-01
We present a technique for determining non-linear resistances, capacitances, and inductances from ring down data in a non-linear RLC circuit. Although the governing differential equations are non-linear, we are able to solve this problem using linear least squares without doing any sort of non-linear iteration.
Non-linearities in Holocene floodplain sediment storage
NASA Astrophysics Data System (ADS)
Notebaert, Bastiaan; Nils, Broothaerts; Jean-François, Berger; Gert, Verstraeten
2013-04-01
Floodplain sediment storage is an important part of the sediment cascade model, buffering sediment delivery between hillslopes and oceans, which is hitherto not fully quantified in contrast to other global sediment budget components. Quantification and dating of floodplain sediment storage is data and financially demanding, limiting contemporary estimates for larger spatial units to simple linear extrapolations from a number of smaller catchments. In this paper we will present non-linearities in both space and time for floodplain sediment budgets in three different catchments. Holocene floodplain sediments of the Dijle catchment in the Belgian loess region, show a clear distinction between morphological stages: early Holocene peat accumulation, followed by mineral floodplain aggradation from the start of the agricultural period on. Contrary to previous assumptions, detailed dating of this morphological change at different shows an important non-linearity in geomorphologic changes of the floodplain, both between and within cross sections. A second example comes from the Pre-Alpine French Valdaine region, where non-linearities and complex system behavior exists between (temporal) patterns of soil erosion and floodplain sediment deposition. In this region Holocene floodplain deposition is characterized by different cut-and-fill phases. The quantification of these different phases shows a complicated image of increasing and decreasing floodplain sediment storage, which hampers the image of increasing sediment accumulation over time. Although fill stages may correspond with large quantities of deposited sediment and traditionally calculated sedimentation rates for such stages are high, they do not necessary correspond with a long-term net increase in floodplain deposition. A third example is based on the floodplain sediment storage in the Amblève catchment, located in the Belgian Ardennes uplands. Detailed floodplain sediment quantification for this catchments shows
Advanced Turbine Systems Program. Topical report
1993-03-01
The Allison Gas Turbine Division (Allison) of General Motors Corporation conducted the Advanced Turbine Systems (ATS) program feasibility study (Phase I) in accordance with the Morgantown Energy Technology Center`s (METC`s) contract DE-AC21-86MC23165 A028. This feasibility study was to define and describe a natural gas-fired reference system which would meet the objective of {ge}60% overall efficiency, produce nitrogen oxides (NO{sub x}) emissions 10% less than the state-of-the-art without post combustion controls, and cost of electricity of the N{sup th} system to be approximately 10% below that of the current systems. In addition, the selected natural gas-fired reference system was expected to be adaptable to coal. The Allison proposed reference system feasibility study incorporated Allison`s long-term experience from advanced aerospace and military technology programs. This experience base is pertinent and crucial to the success of the ATS program. The existing aeroderivative technology base includes high temperature hot section design capability, single crystal technology, advanced cooling techniques, high temperature ceramics, ultrahigh turbomachinery components design, advanced cycles, and sophisticated computer codes.
Advanced space program studies. Overall executive summary
NASA Technical Reports Server (NTRS)
Wolfe, M. G.
1977-01-01
NASA and DoD requirements and planning data were used in multidiscipline advanced planning investigations of space operations and associated elements (including man), identification of potential low cost approaches, vehicle design, cost synthesis techniques, technology forecasting and opportunities for DoD technology transfer, and the development near-, mid-, and far-term space initiatives and development plans with emphasis on domestic and military commonality. An overview of objectives and results are presented for the following studies: advanced space planning and conceptual analysis, shuttle users, technology assessment and new opportunities, standardization and program practice, integrated STS operations planning, solid spinning upper stage, and integrated planning support functions.
The non-linear analysis of multi-support rotor-bearing systems
Kicinski, J.; Drozdowski, R.
1995-12-31
This paper contains selected parts of the simulation research of large rotor machines (200 MW power turbine-sets). These investigations were based on a non-linear theoretical model and the NLDW computer program, and were carried out in the Institute of Fluid-Flow Machinery of PAS. A trial has been performed of the optimization of system-dynamic properties, through the suitable selection of thermally deformed bearing-bush centers line -- the so called ``hot`` line -- (due to a rotor`s geodesic line), as well as the selection of the external fixing stiffness of bearing supports. Examples are also included of the orbits of selected system nodes for two differently powered turbine-sets. On this basis, an analysis of the stability of those turbines was achieved. A significant objective of this paper is also to point out some possibilities of applying the simulation research, based on a non-linear description of the system, to the diagnostics of rotor-machinery. Non-linear analysis facilitates the possibility of easily generating vibration spectra, as well as creating simulation waterfall graphs. These properties of nonlinear analysis create convenient conditions for gaining specific diagnostic information.
ADVANCED GAS TURBINE SYSTEMS RESEARCH PROGRAM
Lawrence P. Golan
2003-05-01
The quarterly activities of the Advanced Gas Turbine Systems Research (AGTSR) program are described in this quarterly report. As this program administers research, we have included all program activity herein within the past quarter as dated. More specific research progress reports are provided weekly at the request of the AGTSR COR and are being sent to NETL As for the administration of this program, items worthy of note are presented in extended bullet format following the appropriate heading. No new memberships, workshops, research projects, internships, faculty fellowships or special studies were initiated during this reporting period. Contract completion is set for June 30, 2003. During the report period, nine subcontractor reports were received (5 final reports and 4 semi-annual reports). The report technology distribution is as follows: 3--aero-heat transfer, 2--combustion and 4--materials. AGTSR continues to project that it will under spend DOE obligated funds by approximately $329K.
Advanced Rotorcraft Transmission (ART) program review
NASA Technical Reports Server (NTRS)
Kish, Jules
1990-01-01
This paper summarizes the work accomplished to date on the NASA/Army Advanced Rotorcraft Transmission (ART) program. A 23-percent weight reduction has been demonstrated for a high output reduction ratio split path transmission compared to an aggressive program goal of 25-percent. Greater than 10 dB noise reduction in the cabin is achieved by the use of high contact ratio spur and double helical gears. In addition, mean times between transmission removals have been increased by almost four fold. These performance gains have been achieved by application of advanced transmission technology concepts. Technology areas are being explored which offer high gain but at relatively high risk in such areas as composites, split power gear concepts, double helical gears, new gear materials, high speed spring clutches, and ceramic rolling element bearings.
NASA's Advanced Space Transportation Hypersonic Program
NASA Technical Reports Server (NTRS)
Hueter, Uwe; McClinton, Charles; Cook, Stephen (Technical Monitor)
2002-01-01
NASA's has established long term goals for access-to-space. NASA's third generation launch systems are to be fully reusable and operational in approximately 25 years. The goals for third generation launch systems are to reduce cost by a factor of 100 and improve safety by a factor of 10,000 over current conditions. The Advanced Space Transportation Program Office (ASTP) at NASA's Marshall Space Flight Center in Huntsville, AL has the agency lead to develop third generation space transportation technologies. The Hypersonics Investment Area, part of ASTP, is developing the third generation launch vehicle technologies in two main areas, propulsion and airframes. The program's major investment is in hypersonic airbreathing propulsion since it offers the greatest potential for meeting the third generation launch vehicles. The program will mature the technologies in three key propulsion areas, scramjets, rocket-based combined cycle and turbine-based combination cycle. Ground and flight propulsion tests are being planned for the propulsion technologies. Airframe technologies will be matured primarily through ground testing. This paper describes NASA's activities in hypersonics. Current programs, accomplishments, future plans and technologies that are being pursued by the Hypersonics Investment Area under the Advanced Space Transportation Program Office will be discussed.
Advanced Reactors Transition Program Resource Loaded Schedule
GANTT, D.A.
2000-01-12
The Advanced Reactors Transition (ART) Resource Loaded Schedule (RLS) provides a cost and schedule baseline for managing the project elements within the ART Program. The Fast Flux Test Facility (FETF) activities are delineated through the end of FY 2000, assuming continued standby. The Nuclear Energy (NE) Legacies and Plutonium Recycle Test Reactor (PRTR) activities are delineated through the end of the deactivation process. This revision reflects the 19 Oct 1999 baseline.
Advanced Reactors Transition Program Resource Loaded Schedule
BOWEN, W.W.
1999-11-08
The Advanced Reactors Transition (ART) Resource Loaded Schedule (RLS) provides a cost and schedule baseline for managing the project elements within the ART Program. The Fast Flux Test Facility (FFTF) activities are delineated through the end of FY 2000, assuming continued standby. The Nuclear Energy (NE) Legacies and Plutonium Recycle Test Reactor (PRTR) activities are delineated through the end of the deactivation process. This document reflects the 1 Oct 1999 baseline.
Global non-linear effect of temperature on economic production
NASA Astrophysics Data System (ADS)
Burke, Marshall; Hsiang, Solomon M.; Miguel, Edward
2015-11-01
Growing evidence demonstrates that climatic conditions can have a profound impact on the functioning of modern human societies, but effects on economic activity appear inconsistent. Fundamental productive elements of modern economies, such as workers and crops, exhibit highly non-linear responses to local temperature even in wealthy countries. In contrast, aggregate macroeconomic productivity of entire wealthy countries is reported not to respond to temperature, while poor countries respond only linearly. Resolving this conflict between micro and macro observations is critical to understanding the role of wealth in coupled human-natural systems and to anticipating the global impact of climate change. Here we unify these seemingly contradictory results by accounting for non-linearity at the macro scale. We show that overall economic productivity is non-linear in temperature for all countries, with productivity peaking at an annual average temperature of 13 °C and declining strongly at higher temperatures. The relationship is globally generalizable, unchanged since 1960, and apparent for agricultural and non-agricultural activity in both rich and poor countries. These results provide the first evidence that economic activity in all regions is coupled to the global climate and establish a new empirical foundation for modelling economic loss in response to climate change, with important implications. If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change. In contrast to prior estimates, expected global losses are approximately linear in global mean temperature, with median losses many times larger than leading models indicate.
Global non-linear effect of temperature on economic production.
Burke, Marshall; Hsiang, Solomon M; Miguel, Edward
2015-11-12
Growing evidence demonstrates that climatic conditions can have a profound impact on the functioning of modern human societies, but effects on economic activity appear inconsistent. Fundamental productive elements of modern economies, such as workers and crops, exhibit highly non-linear responses to local temperature even in wealthy countries. In contrast, aggregate macroeconomic productivity of entire wealthy countries is reported not to respond to temperature, while poor countries respond only linearly. Resolving this conflict between micro and macro observations is critical to understanding the role of wealth in coupled human-natural systems and to anticipating the global impact of climate change. Here we unify these seemingly contradictory results by accounting for non-linearity at the macro scale. We show that overall economic productivity is non-linear in temperature for all countries, with productivity peaking at an annual average temperature of 13 °C and declining strongly at higher temperatures. The relationship is globally generalizable, unchanged since 1960, and apparent for agricultural and non-agricultural activity in both rich and poor countries. These results provide the first evidence that economic activity in all regions is coupled to the global climate and establish a new empirical foundation for modelling economic loss in response to climate change, with important implications. If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change. In contrast to prior estimates, expected global losses are approximately linear in global mean temperature, with median losses many times larger than leading models indicate. PMID:26503051
Non-linear dynamics of compound sawteeth in tokamaks
NASA Astrophysics Data System (ADS)
Ahn, J.-H.; Garbet, X.; Lütjens, H.; Marx, A.; Nicolas, T.; Sabot, R.; Luciani, J.-F.; Guirlet, R.; Février, O.; Maget, P.
2016-05-01
Compound sawteeth is studied with the XTOR-2F code. Non-linear full 3D magnetohydrodynamic simulations show that the plasma hot core is radially displaced and rotates during the partial crash, but is not fully expelled out of the q = 1 surface. Partial crashes occur when the radius of the q = 1 surface exceeds a critical value, at fixed poloidal beta. This critical value depends on the plasma elongation. The partial crash time is larger than the collapse time of an ordinary sawtooth, likely due to a weaker diamagnetic stabilization. This suggests that partial crashes result from a competition between destabilizing effects such as the q = 1 radius and diamagnetic stabilization.
A non-linear UAV altitude PSO-PD control
NASA Astrophysics Data System (ADS)
Orlando, Calogero
2015-12-01
In this work, a nonlinear model based approach is presented for the altitude stabilization of a hexarotor unmanned aerial vehicle (UAV). The mathematical model and control of the hexacopter airframe is presented. To stabilize the system along the vertical direction, a Proportional Derivative (PD) control is taken into account. A particle swarm optimization (PSO) approach is used in this paper to select the optimal parameters of the control algorithm taking into account different objective functions. Simulation sets are performed to carry out the results for the non-linear system to show how the PSO tuned PD controller leads to zero the error of the position along Z earth direction.
8-PSK Signaling over non-linear satellite channels
NASA Technical Reports Server (NTRS)
Horan, Sheila B.; Caballero, Ruben B. Eng.
1996-01-01
Space agencies are under pressure to utilize better bandwidth-efficient communication methods due to the actual allocated frequency bands becoming more congested. Also budget reductions is another problem that the space agencies must deal with. This budget constraint results in simpler spacecraft carrying less communication capabilities and also the reduction in staff to capture data in the earth stations. It is then imperative that the most bandwidth efficient communication methods be utilized. This thesis presents a study of 8-ary Phase Shift Keying (8PSK) modulation with respect to bandwidth, power efficiency, spurious emissions and interference susceptibility over a non-linear satellite channel.
Response of a rotorcraft model with damping non-linearities
NASA Astrophysics Data System (ADS)
Tongue, B. H.
1985-11-01
The linearized equations of motion of a helicopter in contact with the ground have solutions which can be linearly stable or unstable, depending on the system parameters. The present study includes physical non-linearities in the helicopter model. This allows one to determine if a steady-state response exists and, if so, what the frequency and amplitude of the oscillations will be. In this way, one can determine how serious the linearly unstable operating regime is and whether destructive oscillations are possible when the system is in the linearly stable regime. The present analysis applies to helicopters having fully articulated rotors.
Non-linear wave interaction in a plasma column
NASA Technical Reports Server (NTRS)
Larsen, J.-M.; Crawford, F. W.
1979-01-01
Non-linear three-wave interaction is analysed for propagation along a cylindrical plasma column surrounded by an infinite dielectric, in the absence of a static magnetic field. An averaged-Lagrangian method is used, and the results are specialized to parametric interaction and mode conversion, assuming an undepleted pump wave. The theory for these two types of interactions is extended to include imperfect synchronism, and the effects of loss. Computations are presented indicating that parametric growth rates of the order of a fraction of a decibel per centimeter should be obtainable for plausible laboratory plasma column parameters.
Non-linear identification of a squeeze-film damper
NASA Technical Reports Server (NTRS)
Stanway, Roger; Mottershead, John; Firoozian, Riaz
1987-01-01
Described is an experimental study to identify the damping laws associated with a squeeze-film vibration damper. This is achieved by using a non-linear filtering algorithm to process displacement responses of the damper ring to synchronous excitation and thus to estimate the parameters in an nth-power velocity model. The experimental facility is described in detail and a representative selection of results is included. The identified models are validated through the prediction of damper-ring orbits and comparison with observed responses.
Non-linear isocurvature perturbations and non-Gaussianities
Langlois, David; Vernizzi, Filippo; Wands, David E-mail: filippo.vernizzi@cea.fr
2008-12-15
We study non-linear primordial adiabatic and isocurvature perturbations and their non-Gaussianity. After giving a general formulation in the context of an extended {delta}N formalism, we analyse in detail two illustrative examples. The first is a mixed curvaton-inflaton scenario in which fluctuations of both the inflaton and a curvaton (a light isocurvature field during inflation) contribute to the primordial density perturbation. The second example is that of double inflation involving two decoupled massive scalar fields during inflation. In the mixed curvaton-inflaton scenario we find that the bispectrum of primordial isocurvature perturbations may be large and comparable to the bispectrum of adiabatic curvature perturbations.
Non-linear dielectric spectroscopy of microbiological suspensions
Treo, Ernesto F; Felice, Carmelo J
2009-01-01
Background Non-linear dielectric spectroscopy (NLDS) of microorganism was characterized by the generation of harmonics in the polarization current when a microorganism suspension was exposed to a sinusoidal electric field. The biological nonlinear response initially described was not well verified by other authors and the results were susceptible to ambiguous interpretation. In this paper NLDS was performed to yeast suspension in tripolar and tetrapolar configuration with a recently developed analyzer. Methods Tripolar analysis was carried out by applying sinusoidal voltages up to 1 V at the electrode interface. Tetrapolar analysis was carried on with sinusoidal field strengths from 0.1 V cm-1 to 70 V cm-1. Both analyses were performed within a frequency range from 1 Hz through 100 Hz. The harmonic amplitudes were Fourier-analyzed and expressed in dB. The third harmonic, as reported previously, was investigated. Statistical analysis (ANOVA) was used to test the effect of inhibitor an activator of the plasma membrane enzyme in the measured response. Results No significant non-linearities were observed in tetrapolar analysis, and no observable changes occurred when inhibitor and activator were added to the suspension. Statistical analysis confirmed these results. When a pure sinus voltage was applied to an electrode-yeast suspension interface, variations higher than 25 dB for the 3rd harmonic were observed. Variation higher than 20 dB in the 3rd harmonics has also been found when adding an inhibitor or activator of the membrane-bounded enzymes. These variations did not occur when the suspension was boiled. Discussion The lack of result in tetrapolar cells suggest that there is no, if any, harmonic generation in microbiological bulk suspension. The non-linear response observed was originated in the electrode-electrolyte interface. The frequency and voltage windows observed in previous tetrapolar analysis were repeated in the tripolar measurements, but maximum were not
Non-Linear Dynamics of Saturn’s Rings
NASA Astrophysics Data System (ADS)
Esposito, Larry W.
2015-11-01
Non-linear processes can explain why Saturn’s rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states.Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit.Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like ‘straw’ that can explain the halo structure and spectroscopy: This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn’s rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from results of numerical simulations in the tidal environment surrounding Saturn. Aggregates can explain many dynamic aspects
Advanced Rotorcraft Transmission (ART) program status
NASA Technical Reports Server (NTRS)
Kish, Jules
1991-01-01
A weight reduction of 23 percent, noise reduction greater than 10 dB, and almost a fourfold increase in mean time between transmission removals has been demonstrated for a helicopter gearbox having a high output reduction ratio split path gear arrangement. These performance gains have been achieved by application of advanced transmission technology concepts in areas which offer high gain but are outside of normal design practices. New technology is being developed in such areas as split power gear concepts, composites, double helical gears, new gear materials, high speed spring clutches, and ceramic rolling element bearings. The programs, when completed, will provide demonstrated component and drive arrangement technology supported by analytical tools. The work is being accomplished under a CR&D program funded by NASA/Army termed the Advanced Rotorcraft transmission (ART) program. It is expected that the ART technology will be incorporated in future rotorcraft of the 1990s and 2000s. This paper summarizes the work accomplished to date on the program by Sikorsky Aircraft.
Non-linear plasma wake growth of electron holes
Hutchinson, I. H.; Haakonsen, C. B.; Zhou, C.
2015-03-15
An object's wake in a plasma with small Debye length that drifts across the magnetic field is subject to electrostatic electron instabilities. Such situations include, for example, the moon in the solar wind and probes in magnetized laboratory plasmas. The instability drive mechanism can equivalently be considered drift down the potential-energy gradient or drift up the density-gradient. The gradients arise because the plasma wake has a region of depressed density and electrostatic potential into which ions are attracted along the field. The non-linear consequences of the instability are analysed in this paper. At physical ratios of electron to ion mass, neither linear nor quasilinear treatment can explain the observation of large-amplitude perturbations that disrupt the ion streams well before they become ion-ion unstable. We show here, however, that electron holes, once formed, continue to grow, driven by the drift mechanism, and if they remain in the wake may reach a maximum non-linearly stable size, beyond which their uncontrolled growth disrupts the ions. The hole growth calculations provide a quantitative prediction of hole profile and size evolution. Hole growth appears to explain the observations of recent particle-in-cell simulations.
Modified non-linear Burgers' equations and cosmic ray shocks
NASA Technical Reports Server (NTRS)
Zank, G. P.; Webb, G. M.; Mckenzie, J. F.
1988-01-01
A reductive perturbation scheme is used to derive a generalized non-linear Burgers' equation, which includes the effects of dispersion, in the long wavelength regime for the two-fluid hydrodynamical model used to describe cosmic ray acceleration by the first-order Fermi process in astrophysical shocks. The generalized Burger's equation is derived for both relativistic and non-relativistic cosmic ray shocks, and describes the time evolution of weak shocks in the theory of diffusive shock acceleration. The inclusion of dispersive effects modifies the phase velocity of the shock obtained from the lower order non-linear Burger's equation through the introduction of higher order terms from the long wavelength dispersion equation. The travelling wave solution of the generalized Burgers' equation for a single shock shows that larger cosmic ray pressures result in broader shock transitions. The results for relativistic shocks show a steepening of the shock as the shock speed approaches the relativistic cosmic ray sound speed. The dependence of the shock speed on the cosmic ray pressure is also discussed.
Non-linear leak currents affect mammalian neuron physiology
Huang, Shiwei; Hong, Sungho; De Schutter, Erik
2015-01-01
In their seminal works on squid giant axons, Hodgkin, and Huxley approximated the membrane leak current as Ohmic, i.e., linear, since in their preparation, sub-threshold current rectification due to the influence of ionic concentration is negligible. Most studies on mammalian neurons have made the same, largely untested, assumption. Here we show that the membrane time constant and input resistance of mammalian neurons (when other major voltage-sensitive and ligand-gated ionic currents are discounted) varies non-linearly with membrane voltage, following the prediction of a Goldman-Hodgkin-Katz-based passive membrane model. The model predicts that under such conditions, the time constant/input resistance-voltage relationship will linearize if the concentration differences across the cell membrane are reduced. These properties were observed in patch-clamp recordings of cerebellar Purkinje neurons (in the presence of pharmacological blockers of other background ionic currents) and were more prominent in the sub-threshold region of the membrane potential. Model simulations showed that the non-linear leak affects voltage-clamp recordings and reduces temporal summation of excitatory synaptic input. Together, our results demonstrate the importance of trans-membrane ionic concentration in defining the functional properties of the passive membrane in mammalian neurons as well as other excitable cells. PMID:26594148
Non-linear plasma wake growth of electron holes
NASA Astrophysics Data System (ADS)
Hutchinson, I. H.; Haakonsen, C. B.; Zhou, C.
2015-03-01
An object's wake in a plasma with small Debye length that drifts across the magnetic field is subject to electrostatic electron instabilities. Such situations include, for example, the moon in the solar wind and probes in magnetized laboratory plasmas. The instability drive mechanism can equivalently be considered drift down the potential-energy gradient or drift up the density-gradient. The gradients arise because the plasma wake has a region of depressed density and electrostatic potential into which ions are attracted along the field. The non-linear consequences of the instability are analysed in this paper. At physical ratios of electron to ion mass, neither linear nor quasilinear treatment can explain the observation of large-amplitude perturbations that disrupt the ion streams well before they become ion-ion unstable. We show here, however, that electron holes, once formed, continue to grow, driven by the drift mechanism, and if they remain in the wake may reach a maximum non-linearly stable size, beyond which their uncontrolled growth disrupts the ions. The hole growth calculations provide a quantitative prediction of hole profile and size evolution. Hole growth appears to explain the observations of recent particle-in-cell simulations.
Effects on non-linearities on aircraft poststall motion
Rohacs, J.; Thomasson, P.; Mosehilde, E.
1994-12-31
The poststall maneuverability controlled by thrust vectoring has become one of the important aspects of new fighter development projects. In simplified case, the motion of aircraft can be described by 6DOF nonlinear system. The lecture deals with the longitudinal motion of poststall maneuverable aircraft. The investigation made about the effects of non-linearities in aerodynamic coefficients having considerable non-linearities and hysteresisis an the poststall motions. There were used some different models of aerodynamic coefficients. The results of investigation have shown that the poststall domain of vectored aircraft can be divided into five different pHs in field of thrust - pitch vector angle, and the chaotic motions of aircraft can be found at the different frequencies of thrust deflection. There were defined an unstable right domain with an unstable oscillation and a field of overpulling at poststall motion. The certain frequency chaotic attractors were got at frequencies of Oxitation between the 0.15 and 0.65 rad/sec. The pitching moment derivatives had the big influence on the chaotic motions, while the lift coefficient derivatives bad the reasonable effects, only.
Polycarbonate-Based Blends for Optical Non-linear Applications
NASA Astrophysics Data System (ADS)
Stanculescu, F.; Stanculescu, A.
2016-02-01
This paper presents some investigations on the optical and morphological properties of the polymer (matrix):monomer (inclusion) composite materials obtained from blends of bisphenol A polycarbonate and amidic monomers. For the preparation of the composite films, we have selected monomers characterised by a maleamic acid structure and synthesised them starting from maleic anhydride and aniline derivatives with -COOH, -NO2, -N(C2H5)2 functional groups attached to the benzene ring. The composite films have been deposited by spin coating using a mixture of two solutions, one containing the matrix and the other the inclusion, both components of the composite system being dissolved in the same solvent. The optical transmission and photoluminescence properties of the composite films have been investigated in correlation with the morphology of the films. The scanning electron microscopy and atomic force microscopy have revealed a non-uniform morphology characterised by the development of two distinct phases. We have also investigated the generation of some optical non-linear (ONL) phenomena in these composite systems. The composite films containing as inclusions monomers characterised by the presence of one -COOH or two -NO2 substituent groups to the aromatic nucleus have shown the most intense second-harmonic generation (SHG). The second-order optical non-linear coefficients have been evaluated for these films, and the effect of the laser power on the ONL behaviour of these materials has also been emphasised.
Polycarbonate-Based Blends for Optical Non-linear Applications.
Stanculescu, F; Stanculescu, A
2016-12-01
This paper presents some investigations on the optical and morphological properties of the polymer (matrix):monomer (inclusion) composite materials obtained from blends of bisphenol A polycarbonate and amidic monomers. For the preparation of the composite films, we have selected monomers characterised by a maleamic acid structure and synthesised them starting from maleic anhydride and aniline derivatives with -COOH, -NO2, -N(C2H5)2 functional groups attached to the benzene ring. The composite films have been deposited by spin coating using a mixture of two solutions, one containing the matrix and the other the inclusion, both components of the composite system being dissolved in the same solvent. The optical transmission and photoluminescence properties of the composite films have been investigated in correlation with the morphology of the films. The scanning electron microscopy and atomic force microscopy have revealed a non-uniform morphology characterised by the development of two distinct phases. We have also investigated the generation of some optical non-linear (ONL) phenomena in these composite systems. The composite films containing as inclusions monomers characterised by the presence of one -COOH or two -NO2 substituent groups to the aromatic nucleus have shown the most intense second-harmonic generation (SHG). The second-order optical non-linear coefficients have been evaluated for these films, and the effect of the laser power on the ONL behaviour of these materials has also been emphasised. PMID:26873262
Industrial Advanced Turbine Systems Program overview
Esbeck, D.W.
1995-10-01
The U.S. Department of Energy (DOE), in partnership with industry, has set new performance standards for industrial gas turbines through the creation of the Industrial Advanced Turbine System Program. Their leadership will lead to the development of an optimized, energy efficient, and environmentally friendly gas turbine power systems in this size class (3-to-20 MW). The DOE has already created a positive effect by encouraging gas turbine system manufacturers to reassess their product and technology plans using the new higher standards as the benchmark. Solar Turbines has been a leader in the industrial gas turbine business, and is delighted to have joined with the DOE in developing the goals and vision for this program. We welcome the opportunity to help the national goals of energy conservation and environmental enhancement. The results of this program should lead to the U.S. based gas turbine industry maintaining its international leadership and the creation of highly paid domestic jobs.
Industrial Advanced Turbine Systems Program overview
Esbeck, D.W.
1995-12-31
DOE`s ATS Program will lead to the development of an optimized, energy efficient, and environmentally friendly gas turbine power systems in the 3 to 20 MW class. Market studies were conducted for application of ATS to the dispersed/distributed electric power generation market. The technology studies have led to the design of a gas-fired, recuperated, industrial size gas turbine. The Ceramic Stationary Gas Turbine program continues. In the High Performance Steam Systems program, a 100 hour development test to prove the advanced 1500 F, 1500 psig system has been successfully completed. A market transformation will take place: the customer will be offered a choice of energy conversion technologies to meet heat and power generation needs into the next century.
Advanced launch system. Advanced development oxidizer turbopump program
NASA Technical Reports Server (NTRS)
1993-01-01
On May 19, 1989, Pratt & Whitney was awarded contract NAS8-37595 by the National Aeronautics and Space Administration, Marshall Space Flight Center, Huntsville Alabama for an Advanced Development Program (ADP) to design, develop and demonstrate a highly reliable low cost, liquid oxygen turbopump for the Advanced Launch System (ALS). The ALS had an overall goal of reducing the cost of placing payloads in orbit by an order of magnitude. This goal would require a substantial reduction in life cycle costs, with emphasis on recurring costs, compared to current launch vehicles. Engine studies supporting these efforts were made for the Space Transportation Main Engine (STME). The emphasis on low cost required design simplification of components and subsystems such that the ground maintenance and test operations was minimized. The results of the Oxygen Turbopump ADP technology effort would provide data to be used in the STME. Initially the STME baseline was a gas generator cycle engine with a vacuum thrust level of 580,000 lbf. This was later increased to 650,000 lbf and the oxygen turbopump design approach was changed to reflect the new thrust level. It was intended that this ADP program be conducted in two phases. Phase 1, a basic phase, would encompass the preliminary design effort, and Phase II, an optional contract phase to cover design, fabrication and test evaluation of an oxygen turbopump at a component test facility at the NASA John C. Stennis Space Center in Mississippi. The basic phase included preliminary design and analysis, evaluation of low cost concepts, and evaluation of fabrication techniques. The option phase included design of the pump and support hardware, analysis of the final configuration to ensure design integrity, fabrication of hardware to demonstrate low cost, DVS Testing of hardware to verify the design, assembly of the turbopump and full scale turbopump testing. In December 1990, the intent of this ADP to support the design and development was
Advanced launch system. Advanced development oxidizer turbopump program
NASA Astrophysics Data System (ADS)
1993-10-01
On May 19, 1989, Pratt & Whitney was awarded contract NAS8-37595 by the National Aeronautics and Space Administration, Marshall Space Flight Center, Huntsville Alabama for an Advanced Development Program (ADP) to design, develop and demonstrate a highly reliable low cost, liquid oxygen turbopump for the Advanced Launch System (ALS). The ALS had an overall goal of reducing the cost of placing payloads in orbit by an order of magnitude. This goal would require a substantial reduction in life cycle costs, with emphasis on recurring costs, compared to current launch vehicles. Engine studies supporting these efforts were made for the Space Transportation Main Engine (STME). The emphasis on low cost required design simplification of components and subsystems such that the ground maintenance and test operations was minimized. The results of the Oxygen Turbopump ADP technology effort would provide data to be used in the STME. Initially the STME baseline was a gas generator cycle engine with a vacuum thrust level of 580,000 lbf. This was later increased to 650,000 lbf and the oxygen turbopump design approach was changed to reflect the new thrust level. It was intended that this ADP program be conducted in two phases. Phase 1, a basic phase, would encompass the preliminary design effort, and Phase II, an optional contract phase to cover design, fabrication and test evaluation of an oxygen turbopump at a component test facility at the NASA John C. Stennis Space Center in Mississippi. The basic phase included preliminary design and analysis, evaluation of low cost concepts, and evaluation of fabrication techniques. The option phase included design of the pump and support hardware, analysis of the final configuration to ensure design integrity, fabrication of hardware to demonstrate low cost, DVS Testing of hardware to verify the design, assembly of the turbopump and full scale turbopump testing. In December 1990, the intent of this ADP to support the design and development was
ADVANCED TURBINE SYSTEM FEDERAL ASSISTANCE PROGRAM
Frank Macri
2003-10-01
Rolls-Royce Corporation has completed a cooperative agreement under Department of Energy (DOE) contract DE-FC21-96MC33066 in support of the Advanced Turbine Systems (ATS) program to stimulate industrial power generation markets. This DOE contract was performed during the period of October 1995 to December 2002. This final technical report, which is a program deliverable, describes all associated results obtained during Phases 3A and 3B of the contract. Rolls-Royce Corporation (formerly Allison Engine Company) initially focused on the design and development of a 10-megawatt (MW) high-efficiency industrial gas turbine engine/package concept (termed the 701-K) to meet the specific goals of the ATS program, which included single digit NOx emissions, increased plant efficiency, fuel flexibility, and reduced cost of power (i.e., $/kW). While a detailed design effort and associated component development were successfully accomplished for the 701-K engine, capable of achieving the stated ATS program goals, in 1999 Rolls-Royce changed its focus to developing advanced component technologies for product insertion that would modernize the current fleet of 501-K and 601-K industrial gas turbines. This effort would also help to establish commercial venues for suppliers and designers and assist in involving future advanced technologies in the field of gas turbine engine development. This strategy change was partly driven by the market requirements that suggested a low demand for a 10-MW aeroderivative industrial gas turbine, a change in corporate strategy for aeroderivative gas turbine engine development initiatives, and a consensus that a better return on investment (ROI) could be achieved under the ATS contract by focusing on product improvements and technology insertion for the existing Rolls-Royce small engine industrial gas turbine fleet.
NASA Astrophysics Data System (ADS)
Hegelich, Bjorn M.; Arefiev, Alexey; Ditmire, Todd; Donovan, Michael E.; Dyer, Gillis; Gaul, Erhard; Labun, Lance; Luedtke, Scott; Martinez, Mikael; McCarry, Edward; Stark, David; Pomerantz, Ishay; Tiwari, Ganesh; Toncian, Toma
2015-11-01
Advances in laser-based hadron generation, especially with respect to particle energy, as well as reaching the new regime of radiation dominated plasmas and non-linear QED, require laser fields of Petavolts per meter that preferably interact with very high density, overcritical plasmas. To achieve these conditions we are upgrading the Texas Petawatt Laser both respect to on-target laser intensity and laser-contrast, aiming to reach intensities of ~ 5x1022 W/cm2 and pulse contrast parameters allowing the interaction with overcritical, yet ultrathin, sub-micron targets. We will report on the planned experiments aimed at ion acceleration, neutron generation and the first experimental measurement of radiation reactions to motivate the chosen upgrade parameters. We will further report on the technical changes to the laser and present first measurements of the achieved intensity and contrast parameters. This work was supported by NNSA cooperative agreement DE-NA0002008, the Defense Advanced Research Projects Agency's PULSE program (12-63-PULSE-FP014), the Air Force Office of Scientific Research (FA9550-14-1-0045) and the National Institute of Health SBIR.
Technology Transfer Automated Retrieval System (TEKTRAN)
Axisymmetric finite element (FE) method was developed using a commercial computer program to simulate cone penetration process in layered granular soil. Soil was considered as a non-linear elastic plastic material which was modeled using variable elastic parameters of Young’s Modulus and Poisson’s r...
12 CFR 1292.5 - Community Investment Cash Advance Programs.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 12 Banks and Banking 10 2014-01-01 2014-01-01 false Community Investment Cash Advance Programs... COMMUNITY INVESTMENT CASH ADVANCE PROGRAMS § 1292.5 Community Investment Cash Advance Programs. (a) In... shall offer a CIP to provide financing for housing projects and for eligible targeted community...
ADVANCED GAS TURBINE SYSTEMS RESEARCH PROGRAM
Lawrence P. Golan
2003-05-01
The activities of the Advanced Gas Turbine Systems Research (AGTSR) program for the reporting period October 1, 2002 to December 31, 2002 are described in this quarterly report. No new membership, workshops, research projects, internships, faculty fellowships or special studies were initiated during this reporting period. Contract completion is set for June 30, 2003. During the report period, six research progress reports were received (3 final reports and 3 semi-annual reports). The University of Central Florida contract SR080 was terminated during this period, as UCF was unable to secure research facilities. AGTSR now projects that it will under spend DOE obligated funds by approximately 340-350K$.
Advanced space program studies: Overall executive summary
NASA Technical Reports Server (NTRS)
Sitney, L. R.
1974-01-01
Studies were conducted to provide NASA with advanced planning analyses which relate integrated space program goals and options to credible technical capabilities, applications potential, and funding resources. The studies concentrated on the following subjects: (1) upper stage options for the space transportation system based on payload considerations, (2) space servicing and standardization of payloads, (3) payload operations, and (4) space transportation system economic analyses related to user charges and new space applications. A systems cost/performance model was developed to synthesize automated, unmanned spacecraft configurations based on the system requirements and a list of equipments at the assembly level.
Transformation matrices between non-linear and linear differential equations
NASA Technical Reports Server (NTRS)
Sartain, R. L.
1983-01-01
In the linearization of systems of non-linear differential equations, those systems which can be exactly transformed into the second order linear differential equation Y"-AY'-BY=0 where Y, Y', and Y" are n x 1 vectors and A and B are constant n x n matrices of real numbers were considered. The 2n x 2n matrix was used to transform the above matrix equation into the first order matrix equation X' = MX. Specially the matrix M and the conditions which will diagonalize or triangularize M were studied. Transformation matrices P and P sub -1 were used to accomplish this diagonalization or triangularization to return to the solution of the second order matrix differential equation system from the first order system.
Non-linear radial spinwave modes in thin magnetic disks
Helsen, M. De Clercq, J.; Vansteenkiste, A.; Van Waeyenberge, B.; Weigand, M.
2015-01-19
We present an experimental investigation of radial spin-wave modes in magnetic nano-disks with a vortex ground state. The spin-wave amplitude was measured using a frequency-resolved magneto-optical spectrum analyzer, allowing for high-resolution resonance curves to be recorded. It was found that with increasing excitation amplitude up to about 10 mT, the lowest-order mode behaves strongly non-linearly as the mode frequency redshifts and the resonance peak strongly deforms. This behavior was quantitatively reproduced by micromagnetic simulations. Micromagnetic simulations showed that at higher excitation amplitudes, the spinwaves are transformed into a soliton by self-focusing, and collapse onto the vortex core, dispersing the energy in short-wavelength spinwaves. Additionally, this process can lead to switching of the vortex polarization through the injection of a Bloch point.
Non-linear dielectric response of ferrofluids under magnetic field
NASA Astrophysics Data System (ADS)
Licinio, Pedro; Teixeira, Alvaro V.; Figueiredo, José Marcos A.
2005-03-01
The dielectric response of a water-based magnetic fluid is investigated at room temperature and in the frequency range of 100-10 7 rad/s. The response is linear in the electric fields used. Upon application of a constant magnetic field of 40 mT, which is well below the sample saturation, the response becomes non-linear. Magnetic field effects are isolated by performing a differential analysis of the inverse dielectric permittivity with and without applied field in both perpendicular and parallel configurations. The imaginary part of the differential inverse permittivity displays two peaks. The low-frequency peak is seen to correspond to the orientation relaxation of aggregates also detected in SAXS, photon correlation and atomic force microscopy measurements. The high-frequency peak corresponds to single magnetic particle reorientation.
Memristive non-linear system and hidden attractor
NASA Astrophysics Data System (ADS)
Saha, P.; Saha, D. C.; Ray, A.; Chowdhury, A. R.
2015-07-01
Effects of memristor on non-linear dynamical systems exhibiting chaos are analysed both form the view point of theory and experiment. It is observed that the memristive system has always fewer number of fixed points than the original one. Sometimes there is no fixed point in the memristive system. But its chaotic properties are retained. As such we have a situation known as hidden attractor because if it is a stable fixed point then the attractor does not evolve from its basin of attraction(obtained from its stable fixed point) or if there is no fixed point, the question of basin of attraction from fixed point does not arise at all [1, 2]. Our analysis gives a detailed accounts of properties related to its chaotic behavior. Important observations are also obtained with the help of electronic circuits to support the numerical simulations.
Anderson Localization, Non-linearity and Stable Genetic Diversity
NASA Astrophysics Data System (ADS)
Epstein, Charles L.
2006-07-01
In many models of genotypic evolution, the vector of genotype populations satisfies a system of linear ordinary differential equations. This system of equations models a competition between differential replication rates (fitness) and mutation. Mutation operates as a generalized diffusion process on genotype space. In the large time asymptotics, the replication term tends to produce a single dominant quasi-species, unless the mutation rate is too high, in which case the asymptotic population becomes de-localized. We introduce a more macroscopic picture of genotypic evolution wherein a random fitness term in the linear model produces features analogous to Anderson localization. When coupled with density dependent non-linearities, which limit the population of any given genotype, we obtain a model whose large time asymptotics display stable genotypic diversity.
Engineering Non-Classical Light with Non-Linear Microwaveguides
NASA Astrophysics Data System (ADS)
Grimsmo, Arne; Clerk, Aashish; Blais, Alexandre
The quest for ever increasing fidelity and scalability in measurement of superconducting qubits to be used for fault-tolerant quantum computing has recently led to the development of near quantum-limited broadband phase preserving amplifiers in the microwave regime. These devices are, however, more than just amplifiers: They are sources of high-quality, broadband two-mode squeezed light. We show how bottom-up engineering of Josephson junction embedded waveguides can be used to design novel squeezing spectra. Furthermore, the entanglement in the two-mode squeezed output field can be imprinted onto quantum systems coupled to the device's output. These broadband microwave amplifiers constitute a realization of non-linear waveguide QED, a very interesting playground for non-equilibrium many-body physics.
Non-linear optical crystal vibration sensing device
Kalibjian, R.
1994-08-09
A non-linear optical crystal vibration sensing device including a photorefractive crystal and a laser is disclosed. The laser produces a coherent light beam which is split by a beam splitter into a first laser beam and a second laser beam. After passing through the crystal the first laser beam is counter-propagated back upon itself by a retro-mirror, creating a third laser beam. The laser beams are modulated, due to the mixing effect within the crystal by vibration of the crystal. In the third laser beam, modulation is stable and such modulation is converted by a photodetector into a usable electrical output, intensity modulated in accordance with vibration applied to the crystal. 3 figs.
Non-linear optical crystal vibration sensing device
Kalibjian, Ralph
1994-01-11
A non-linear optical crystal vibration sensing device (10) including a photorefractive crystal (26) and a laser (12). The laser (12 ) produces a coherent light beam (14) which is split by a beam splitter (18) into a first laser beam (20) and a second laser beam (22). After passing through the crystal (26) the first laser beam (20) is counter-propagated back upon itself by a retro-mirror (32), creating a third laser beam (30). The laser beams (20, 22, 30) are modulated, due to the mixing effect within the crystal (26) by vibration of the crystal (30). In the third laser beam (30), modulation is stable and such modulation is converted by a photodetector (34) into a usable electrical output, intensity modulated in accordance with vibration applied to the crystal (26).
Detector noise statistics in the non-linear regime
NASA Technical Reports Server (NTRS)
Shopbell, P. L.; Bland-Hawthorn, J.
1992-01-01
The statistical behavior of an idealized linear detector in the presence of threshold and saturation levels is examined. It is assumed that the noise is governed by the statistical fluctuations in the number of photons emitted by the source during an exposure. Since physical detectors cannot have infinite dynamic range, our model illustrates that all devices have non-linear regimes, particularly at high count rates. The primary effect is a decrease in the statistical variance about the mean signal due to a portion of the expected noise distribution being removed via clipping. Higher order statistical moments are also examined, in particular, skewness and kurtosis. In principle, the expected distortion in the detector noise characteristics can be calibrated using flatfield observations with count rates matched to the observations. For this purpose, some basic statistical methods that utilize Fourier analysis techniques are described.
Neural networks: What non-linearity to choose
NASA Technical Reports Server (NTRS)
Kreinovich, Vladik YA.; Quintana, Chris
1991-01-01
Neural networks are now one of the most successful learning formalisms. Neurons transform inputs (x(sub 1),...,x(sub n)) into an output f(w(sub 1)x(sub 1) + ... + w(sub n)x(sub n)), where f is a non-linear function and w, are adjustable weights. What f to choose? Usually the logistic function is chosen, but sometimes the use of different functions improves the practical efficiency of the network. The problem of choosing f as a mathematical optimization problem is formulated and solved under different optimality criteria. As a result, a list of functions f that are optimal under these criteria are determined. This list includes both the functions that were empirically proved to be the best for some problems, and some new functions that may be worth trying.
Method and system for non-linear motion estimation
NASA Technical Reports Server (NTRS)
Lu, Ligang (Inventor)
2011-01-01
A method and system for extrapolating and interpolating a visual signal including determining a first motion vector between a first pixel position in a first image to a second pixel position in a second image, determining a second motion vector between the second pixel position in the second image and a third pixel position in a third image, determining a third motion vector between one of the first pixel position in the first image and the second pixel position in the second image, and the second pixel position in the second image and the third pixel position in the third image using a non-linear model, determining a position of the fourth pixel in a fourth image based upon the third motion vector.
Spontaneous Lorentz symmetry breaking in non-linear electrodynamics
Urrutia, Luis F.
2010-07-29
A recently proposed model of non-linear electrodynamics arising from a gauge invariant spontaneous Lorentz symmetry breaking is reviewed. The potential providing the symmetry breaking is argued to arise from the integration of gauge bosons and fermions in an underlying theory. The invariant subgroups remaining after the symmetry breaking are determined, as well as the dispersion relations and polarization modes of the propagating linear sector or the model. Strong bounds upon the predicted anisotropy of the speed of light are obtained by embedding the model in the electromagnetic sector of the Standard Model Extension and taking advantage of the restrictions in the parameters derived there. Finally, a reasonable estimation of the intergalactic magnetic field is obtained by assuming that the vacuum energy of the model is described by the standard cosmological constant.
Attractor reconstruction for non-linear systems: a methodological note
Nichols, J.M.; Nichols, J.D.
2001-01-01
Attractor reconstruction is an important step in the process of making predictions for non-linear time-series and in the computation of certain invariant quantities used to characterize the dynamics of such series. The utility of computed predictions and invariant quantities is dependent on the accuracy of attractor reconstruction, which in turn is determined by the methods used in the reconstruction process. This paper suggests methods by which the delay and embedding dimension may be selected for a typical delay coordinate reconstruction. A comparison is drawn between the use of the autocorrelation function and mutual information in quantifying the delay. In addition, a false nearest neighbor (FNN) approach is used in minimizing the number of delay vectors needed. Results highlight the need for an accurate reconstruction in the computation of the Lyapunov spectrum and in prediction algorithms.
Ferrite core non-linearity in coils for magnetic neurostimulation
Lazzi, Gianluca
2014-01-01
The need to correctly predict the voltage across terminals of mm-sized coils, with ferrite core, to be employed for magnetic stimulation of the peripheral neural system is the motivation for this work. In such applications, which rely on a capacitive discharge on the coil to realise a transient voltage curve of duration and strength suitable for neural stimulation, the correct modelling of the non-linearity of the ferrite core is critical. A demonstration of how a finite-difference model of the considered coils, which include a model of the current-controlled inductance in the coil, can be used to correctly predict the time-domain voltage waveforms across the terminals of a test coil is presented. Five coils of different dimensions, loaded with ferrite cores, have been fabricated and tested: the measured magnitude and width of the induced pulse are within 10% of simulated values. PMID:26609390
Solar Concentrator Advanced Development Program, Task 1
NASA Technical Reports Server (NTRS)
1986-01-01
Solar dynamic power generation has been selected by NASA to provide power for the space station. Solar dynamic concentrator technology has been demonstrated for terrestrial applications but has not been developed for space applications. The object of the Solar Concentrator Advanced Development program is to develop the technology of solar concentrators which would be used on the space station. The first task of this program was to develop conceptual concentrator designs and perform trade-off studies and to develop a materials data base and perform material selection. Three unique concentrator concepts; Truss Hex, Spline Radial Panel and Domed Fresnel, were developed and evaluated against weighted trade criteria. The Truss Hex concept was recommended for the space station. Materials data base development demonstrated that several material systems are capable of withstanding extended periods of atomic oxygen exposure without undesirable performance degradation. Descriptions of the conceptual designs and materials test data are included.
Advanced composites wing study program, volume 2
NASA Technical Reports Server (NTRS)
Harvey, S. T.; Michaelson, G. L.
1978-01-01
The study on utilization of advanced composites in commercial aircraft wing structures was conducted as a part of the NASA Aircraft Energy Efficiency Program to establish, by the mid-1980s, the technology for the design of a subsonic commercial transport aircraft leading to a 40% fuel savings. The study objective was to develop a plan to define the effort needed to support a production commitment for the extensive use of composite materials in wings of new generation aircraft that will enter service in the 1985-1990 time period. Identification and analysis of what was needed to meet the above plan requirements resulted in a program plan consisting of three key development areas: (1) technology development; (2) production capability development; and (3) integration and validation by designing, building, and testing major development hardware.
NASA/USRA University advanced design program
NASA Technical Reports Server (NTRS)
Lembeck, Michael F.; Prussing, John
1989-01-01
The participation of the University of Illinois at Urbana-Champaign in the NASA/USRA University Advanced Design Program for the 1988 to 1989 academic year is reviewed. The University's design project was the Logistics Resupply and Emergency Crew Return System for Space Station Freedom. Sixty-one students divided into eight groups, participated in the spring 1989 semester. A presentation prepared by three students and a graduate teaching assistant for the program's summer conference summarized the project results. Teamed with the NASA Marshall Space Flight Center (MSFC), the University received support in the form of remote telecon lectures, reference material, and previously acquired applications software. In addition, a graduate teaching assistant was awarded a summer 1989 internship at MSFC.
Reducing sample variance: halo biasing, non-linearity and stochasticity
NASA Astrophysics Data System (ADS)
Gil-Marín, Héctor; Wagner, Christian; Verde, Licia; Jimenez, Raul; Heavens, Alan F.
2010-09-01
Comparing clustering of differently biased tracers of the dark matter distribution offers the opportunity to reduce the sample or cosmic variance error in the measurement of certain cosmological parameters. We develop a formalism that includes bias non-linearities and stochasticity. Our formalism is general enough that it can be used to optimize survey design and tracers selection and optimally split (or combine) tracers to minimize the error on the cosmologically interesting quantities. Our approach generalizes the one presented by McDonald & Seljak of circumventing sample variance in the measurement of f ≡ d lnD/d lna. We analyse how the bias, the noise, the non-linearity and stochasticity affect the measurements of Df and explore in which signal-to-noise regime it is significantly advantageous to split a galaxy sample in two differently biased tracers. We use N-body simulations to find realistic values for the parameters describing the bias properties of dark matter haloes of different masses and their number density. We find that, even if dark matter haloes could be used as tracers and selected in an idealized way, for realistic haloes, the sample variance limit can be reduced only by up to a factor σ2tr/σ1tr ~= 0.6. This would still correspond to the gain from a three times larger survey volume if the two tracers were not to be split. Before any practical application one should bear in mind that these findings apply to dark matter haloes as tracers, while realistic surveys would select galaxies: the galaxy-host halo relation is likely to introduce extra stochasticity, which may reduce the gain further.
Limit cycle oscillation of missile control fin with structural non-linearity
NASA Astrophysics Data System (ADS)
Bae, J. S.; Lee, I.
2004-01-01
Non-linear aeroelastic characteristics of a deployable missile control fin with structural non-linearity are investigated. A deployable missile control fin is modelled as a two-dimensional typical section model. Doublet-point method is used for the calculation of supersonic unsteady aerodynamic forces, and aerodynamic forces are approximated by using the minimum-state approximation. For non-linear flutter analysis structural non-linearity is represented by an asymmetric bilinear spring and is linearized by using the describing function method. The linear and non-linear flutter analyses indicate that the flutter characteristics are significantly dependent on the frequency ratio. From the non-linear flutter analysis, various types of limit cycle oscillations are observed in a wide range of air speeds below or above the linear divergent flutter boundary. The non-linear flutter characteristics and the non-linear aeroelastic responses are investigated.
Advanced optics in an interdisciplinary graduate program
NASA Astrophysics Data System (ADS)
Nic Chormaic, S.
2014-07-01
The Okinawa Institute of Science and Technology Graduate University, established in November 2011, provides a 5- year interdisciplinary PhD program, through English, within Japan. International and Japanese students entering the program undertake coursework and laboratory rotations across a range of topics, including neuroscience, molecular science, physics, chemistry, marine science and mathematics, regardless of previous educational background. To facilitate interdisciplinarity, the university has no departments, ensuring seamless interactions between researchers from all sectors. As part of the PhD program a course in Advanced Optics has been developed to provide PhD students with the practical and theoretical skills to enable them to use optics tools in any research environment. The theoretical aspect of the course introduces students to procedures for complex beam generation (e.g. Laguerre-Gaussian), optical trapping, beam analysis and photon optics, and is supported through a practical program covering introductory interference/diffraction experiments through to more applied fiber optics. It is hoped that, through early exposure to optics handling and measurement techniques, students will be able to develop and utilize optics tools regardless of research field. In addition to the formal course in Advanced Optics, a selection of students also undertakes 13 week laboratory rotations in the Light-Matter Interactions research laboratory, where they work side-by-side with physicists in developing optics tools for laser cooling, photonics or bio-applications. While currently in the first year, conclusive results about the success of such an interdisciplinary PhD training are speculative. However, initial observations indicate a rich cross-fertilization of ideas stemming from the diverse backgrounds of all participants.
The Federal Advanced Wind Turbine Program
Hock, S M; Thresher, R W; Goldman, P R
1991-12-01
The development of technologically advanced, higher efficiency wind turbines has been identified as a high priority activity by the US wind industry. The Department of Energy's Wind Energy Program has begun a multi-year development program aimed at assisting the wind industry with the design, development, and testing of advanced wind turbine systems that can compete with conventional electric generation for $0.05/kWh at 13 mph sites by the mid-1990s and with fossil-fuel-based generators for $0.04/kWh at 13 mph sites by the year 2000. The development plan consists of four phases: (1) Conceptual Design Studies; (2) Near-Term Product Development; (3) Next Generation Technology Integration and Design, and (4) Next- Generation Technology Development and Testing. The Conceptual Design Studies were begun in late 1990, and are scheduled for completion in the Spring of 1992. Preliminary results from these analyses are very promising and indicate that the goals stated above are technically feasible. This paper includes a brief summary of the Conceptual Design Studies and presents initial plans for the follow-on activities. 3 refs., 4 figs.
State-variable analysis of non-linear circuits with a desk computer
NASA Technical Reports Server (NTRS)
Cohen, E.
1981-01-01
State variable analysis was used to analyze the transient performance of non-linear circuits on a desk top computer. The non-linearities considered were not restricted to any circuit element. All that is required for analysis is the relationship defining each non-linearity be known in terms of points on a curve.
Discriminating Non-Linearity from Linearity: Its Cognitive Foundations in Five-Year-Olds
ERIC Educational Resources Information Center
Ebersbach, Mirjam; Van Dooren, Wim; Goudriaan, Margje N.; Verschaffel, Lieven
2010-01-01
People often have difficulties in understanding situations that involve non-linear processes. Also, the topic of non-linear functions is introduced relatively late in the curriculum. Previous research has nevertheless shown that already children aged 6 years and older are able to discriminate non-linear from linear processes. Within the present…
NASA Astrophysics Data System (ADS)
KIM, DONG-HYUN; LEE, IN
2000-07-01
A two-degree-of-freedom airfoil with a freeplay non-linearity in the pitch and plunge directions has been analyzed in the transonic and low-supersonic flow region, where aerodynamic non-linearities also exist. The primary purpose of this study is to show aeroelastic characteristics due to freeplay structural non-linearity in the transonic and low-supersonic regions. The unsteady aerodynamic forces on the airfoil were evaluated using two-dimensional unsteady Euler code, and the resulting aeroelastic equations are numerically integrated to obtain the aeroelastic time responses of the airfoil motions and to investigate the dynamic instability. The present model has been considered as a simple aeroelastic model, which is equivalent to the folding fin of an advanced generic missile. From the results of the present study, characteristics of important vibration responses and aeroelastic instabilities can be observed in the transonic and supersonic regions, especially considering the effect of structural non-linearity in the pitch and plunge directions. The regions of limit-cycle oscillation are shown at much lower velocities, especially in the supersonic flow region, than the divergent flutter velocities of the linear structure model. It is also shown that even small freeplay angles can lead to severe dynamic instabilities and dangerous fatigue conditions for the flight vehicle wings and control fins.
Steyrl, David; Scherer, Reinhold; Faller, Josef; Müller-Putz, Gernot R
2016-02-01
There is general agreement in the brain-computer interface (BCI) community that although non-linear classifiers can provide better results in some cases, linear classifiers are preferable. Particularly, as non-linear classifiers often involve a number of parameters that must be carefully chosen. However, new non-linear classifiers were developed over the last decade. One of them is the random forest (RF) classifier. Although popular in other fields of science, RFs are not common in BCI research. In this work, we address three open questions regarding RFs in sensorimotor rhythm (SMR) BCIs: parametrization, online applicability, and performance compared to regularized linear discriminant analysis (LDA). We found that the performance of RF is constant over a large range of parameter values. We demonstrate - for the first time - that RFs are applicable online in SMR-BCIs. Further, we show in an offline BCI simulation that RFs statistically significantly outperform regularized LDA by about 3%. These results confirm that RFs are practical and convenient non-linear classifiers for SMR-BCIs. Taking into account further properties of RFs, such as independence from feature distributions, maximum margin behavior, multiclass and advanced data mining capabilities, we argue that RFs should be taken into consideration for future BCIs. PMID:25830903
Non-Linear Oscillation in Ionic Current Due to Size Effect in Glass Nanopipette
NASA Astrophysics Data System (ADS)
Takami, Tomohide; Deng, Xiao Long; Son, Jong Wan; Kang, Eun Ji; Kawai, Tomoji; Park, Bae Ho
2012-11-01
We studied the size effect of the ionic current in glass pipette, and found an interesting 2.7 mHz oscillation at 50 nm. In this study, we would like to discuss the mechanism of the non-linear oscillation. Cation-rich layer with its Debye length λ exists in nanopipette, and its conductivity σd is lower than that in the central bulk layer σb in this study. The pressure difference ΔP = ΔcRT where Δc is the difference in concentrations between in and out of the pipette. Then, the ionic current I can be estimated by using Hagen-Poiseuille equation; I =π/8 η ΔcRT/l {σdr4 + (σb -σd) (λ - r) 2 (r2 + 2 rλ -λ2) } . (r : inner radius, l: pipette length, η: viscosity) The last term indicates the non-linear oscillation. Moreover, we roughly estimated λ = 2.08 ×(2r) 1 / 2. Then, the bulk layer appears appropriately when 2 r 50 nm, which causes the effective ionic current oscillation. This work was supported by KOSEF NRL Program grant funded by the Korea Government MEST (Grant No. 2010-0024525 and R0A-2008-000-20052-0), and WCU Program through the KOSEF funded by the MEST (Grant No. R31-2008-000-10057-0).
Rapid Non-Linear Uncertainty Propagation via Analytical Techniques
NASA Astrophysics Data System (ADS)
Fujimoto, K.; Scheeres, D. J.
2012-09-01
Space situational awareness (SSA) is known to be a data starved problem compared to traditional estimation problems in that observation gaps per object may span over days if not weeks. Therefore, consistent characterization of the uncertainty associated with these objects including non-linear effects is crucial in maintaining an accurate catalog of objects in Earth orbit. Simultaneously, the motion of satellites in Earth orbit is well-modeled in that it is particularly amenable to having their solution and their uncertainty described through analytic or semi-analytic techniques. Even when stronger non-gravitational perturbations such as solar radiation pressure and atmospheric drag are encountered, these perturbations generally have deterministic components that are substantially larger than their time-varying stochastic components. Analytic techniques are powerful because time propagation is only a matter of changing the time parameter, allowing for rapid computational turnaround. These two ideas are combined in this paper: a method of analytically propagating non-linear orbit uncertainties is discussed. In particular, the uncertainty is expressed as an analytic probability density function (pdf) for all time. For a deterministic system model, such pdfs may be obtained if the initial pdf and the system states for all time are also given analytically. Even when closed-form solutions are not available, approximate solutions exist in the form of Edgeworth series for pdfs and Taylor series for the states. The coefficients of the latter expansion are referred to as state transition tensors (STTs), which are a generalization of state transition matrices to arbitrary order. Analytically expressed pdfs can be incorporated in many practical tasks in SSA. One can compute the mean and covariance of the uncertainty, for example, with the moments of the initial pdf as inputs. This process does not involve any sampling and its accuracy can be determined a priori. Analytical
Advanced Technology Composite Fuselage: Program Overview
NASA Technical Reports Server (NTRS)
Ilcewicz, L. B.; Smith, P. J.; Hanson, C. T.; Walker, T. H.; Metschan, S. L.; Mabson, G. E.; Wilden, K. S.; Flynn, B. W.; Scholz, D. B.; Polland, D. R.; Fredrikson, H. G.; Olson, J. T.; Backman, B. F.
1997-01-01
The Advanced Technology Composite Aircraft Structures (ATCAS) program has studied transport fuselage structure with a large potential reduction in the total direct operating costs for wide-body commercial transports. The baseline fuselage section was divided into four 'quadrants', crown, keel, and sides, gaining the manufacturing cost advantage possible with larger panels. Key processes found to have savings potential include (1) skins laminated by automatic fiber placement, (2) braided frames using resin transfer molding, and (3) panel bond technology that minimized mechanical fastening. The cost and weight of the baseline fuselage barrel was updated to complete Phase B of the program. An assessment of the former, which included labor, material, and tooling costs, was performed with the help of design cost models. Crown, keel, and side quadrant cost distributions illustrate the importance of panel design configuration, area, and other structural details. Composite sandwich panel designs were found to have the greatest cost savings potential for most quadrants. Key technical findings are summarized as an introduction to the other contractor reports documenting Phase A and B work completed in functional areas. The current program status in resolving critical technical issues is also highlighted.
Non-linear evolution of the cosmic neutrino background
Villaescusa-Navarro, Francisco; Viel, Matteo; Peña-Garay, Carlos E-mail: spb@ias.edu E-mail: viel@oats.inaf.it
2013-03-01
We investigate the non-linear evolution of the relic cosmic neutrino background by running large box-size, high resolution N-body simulations which incorporate cold dark matter (CDM) and neutrinos as independent particle species. Our set of simulations explore the properties of neutrinos in a reference ΛCDM model with total neutrino masses between 0.05-0.60 eV in cold dark matter haloes of mass 10{sup 11}−10{sup 15} h{sup −1}M{sub s}un, over a redshift range z = 0−2. We compute the halo mass function and show that it is reasonably well fitted by the Sheth-Tormen formula, once the neutrino contribution to the total matter is removed. More importantly, we focus on the CDM and neutrino properties of the density and peculiar velocity fields in the cosmological volume, inside and in the outskirts of virialized haloes. The dynamical state of the neutrino particles depends strongly on their momentum: whereas neutrinos in the low velocity tail behave similarly to CDM particles, neutrinos in the high velocity tail are not affected by the clustering of the underlying CDM component. We find that the neutrino (linear) unperturbed momentum distribution is modified and mass and redshift dependent deviations from the expected Fermi-Dirac distribution are in place both in the cosmological volume and inside haloes. The neutrino density profiles around virialized haloes have been carefully investigated and a simple fitting formula is provided. The neutrino profile, unlike the cold dark matter one, is found to be cored with core size and central density that depend on the neutrino mass, redshift and mass of the halo, for halos of masses larger than ∼ 10{sup 13.5}h{sup −1}M{sub s}un. For lower masses the neutrino profile is best fitted by a simple power-law relation in the range probed by the simulations. The results we obtain are numerically converged in terms of neutrino profiles at the 10% level for scales above ∼ 200 h{sup −1}kpc at z = 0, and are stable with
Filtering Non-Linear Transfer Functions on Surfaces.
Heitz, Eric; Nowrouzezahrai, Derek; Poulin, Pierre; Neyret, Fabrice
2014-07-01
Applying non-linear transfer functions and look-up tables to procedural functions (such as noise), surface attributes, or even surface geometry are common strategies used to enhance visual detail. Their simplicity and ability to mimic a wide range of realistic appearances have led to their adoption in many rendering problems. As with any textured or geometric detail, proper filtering is needed to reduce aliasing when viewed across a range of distances, but accurate and efficient transfer function filtering remains an open problem for several reasons: transfer functions are complex and non-linear, especially when mapped through procedural noise and/or geometry-dependent functions, and the effects of perspective and masking further complicate the filtering over a pixel's footprint. We accurately solve this problem by computing and sampling from specialized filtering distributions on the fly, yielding very fast performance. We investigate the case where the transfer function to filter is a color map applied to (macroscale) surface textures (like noise), as well as color maps applied according to (microscale) geometric details. We introduce a novel representation of a (potentially modulated) color map's distribution over pixel footprints using Gaussian statistics and, in the more complex case of high-resolution color mapped microsurface details, our filtering is view- and light-dependent, and capable of correctly handling masking and occlusion effects. Our approach can be generalized to filter other physical-based rendering quantities. We propose an application to shading with irradiance environment maps over large terrains. Our framework is also compatible with the case of transfer functions used to warp surface geometry, as long as the transformations can be represented with Gaussian statistics, leading to proper view- and light-dependent filtering results. Our results match ground truth and our solution is well suited to real-time applications, requires only a few
76 FR 68011 - Medicare Program; Advanced Payment Model
Federal Register 2010, 2011, 2012, 2013, 2014
2011-11-02
... Medicare Program; Advanced Payment Model; Notice #0;#0;Federal Register / Vol. 76, No. 212 / Wednesday... Services Medicare Program; Advanced Payment Model AGENCY: Centers for Medicare & Medicaid Services (CMS), HHS. ACTION: Notice. SUMMARY: This notice announces the testing of the Advance Payment Model...
76 FR 24343 - Advanced Biofuel Payment Program; Correction
Federal Register 2010, 2011, 2012, 2013, 2014
2011-05-02
... Service Rural Utilities Service 7 CFR Part 4288 RIN 0570-AA75 Advanced Biofuel Payment Program; Correction... Advanced Biofuel Payment Program authorized under the Food, Conservation, and Energy Act of 2008. This... contracts with advanced biofuel producers to pay such producers for the production of eligible...
Rocketdyne's advanced coal slurry pumping program
NASA Technical Reports Server (NTRS)
Davis, D. E.; Wong, G. S.; Gilman, H. H.
1977-01-01
The Rocketdyne Division of Rockwell International Corporation is conducting a program for the engineering, fabrication, and testing of an experimental/prototype high-capacity, high-pressure centrifugal slurry feed pump for coal liquefaction purposes. The abrasion problems in a centrifugal slurry pump are primarily due to the manner in which the hard, solid particles contained in the slurry are transported through the hydraulic flow passages within the pump. The abrasive particles can create scraping, grinding, cutting, and sandblasting effects on the various exposed parts of the pump. These critical areas involving abrasion and impact erosion wear problems in a centrifugal pump are being addressed by Rocketdyne. The mechanisms of abrasion and erosion are being studied through hydrodynamic analysis, materials evaluation, and advanced design concepts.
Research for Lunar Exploration: ADVANCE Program
NASA Technical Reports Server (NTRS)
Rojdev, Kristina
2009-01-01
This viewgraph presentation reviews the work that the author has been involved with in her undergraduate and graduate education and the ADVANCE Program. One project was the Lunar Entry and Approach Platform For Research On Ground (LEAPFROG). This vehicle was to be a completely autonomous vehicle, and was developed in successive academic years with increases in the perofmamnce and capability of the simulated lander. Another research project for the PhD was on long-term lunar radiation degradation of materials to be used for construction of lunar habitats. This research has concentrated on developing and testing light-weight composite materials with high strength characteristics, and the ability of these composite materials to withstand the lunar radiation environment.
Sikorsky Aircraft Advanced Rotorcraft Transmission (ART) program
NASA Astrophysics Data System (ADS)
Kish, Jules G.
1993-03-01
The objectives of the Advanced Rotorcraft Transmission program were to achieve a 25 percent weight reduction, a 10 dB noise reduction, and a 5,000 hour mean time between removals (MTBR). A three engine Army Cargo Aircraft (ACA) of 85,000 pounds gross weight was used as the baseline. Preliminary designs were conducted of split path and split torque transmissions to evaluate weight, reliability, and noise. A split path gearbox was determined to be 23 percent lighter, greater than 10 dB quieter, and almost four times more reliable than the baseline two stage planetary design. Detail design studies were conducted of the chosen split path configuration, and drawings were produced of a 1/2 size gearbox consisting of a single engine path of the split path section. Fabrication and testing was then conducted on the 1/2 size gearbox. The 1/2 size gearbox testing proved that the concept of the split path gearbox with high reduction ratio double helical output gear was sound. The improvements were attributed to extensive use of composites, spring clutches, advanced high hot hardness gear steels, the split path configuration itself, high reduction ratio, double helical gearing on the output stage, elastomeric load sharing devices, and elimination of accessory drives.
National Advanced Drilling and Excavation Technologies Program
1993-06-15
The second meeting of Federal agency representatives interested in the National Advanced Drilling and Excavation Technologies (NADET) Program took place on June 15, 1993. The Geothermal Division of the U.S. Department of Energy (DOE) hosted the meeting at the Washington, D.C., offices of DOE. Representatives from the National Science Foundation, U.S. Geological Survey, U.S. Bureau of Mines, National Institute of Standards and Technology, National Aeronautics and Space Administration, Environmental Protection Agency, and various offices within the Department of Energy attended. For a complete list of attendees see Attachment A. The purpose of the meeting was: (1) to cover the status of efforts to gain formal approval for NADET, (2) to brief participants on events since the last meeting, especially two recent workshops that explored research needs in drilling and excavation, (3) to review some recent technological advances, and (4) to solicit statements of the importance of improving drilling and excavation technologies to the missions of the various agencies. The meeting agenda is included as Attachment B.
Sikorsky Aircraft Advanced Rotorcraft Transmission (ART) program
NASA Technical Reports Server (NTRS)
Kish, Jules G.
1993-01-01
The objectives of the Advanced Rotorcraft Transmission program were to achieve a 25 percent weight reduction, a 10 dB noise reduction, and a 5,000 hour mean time between removals (MTBR). A three engine Army Cargo Aircraft (ACA) of 85,000 pounds gross weight was used as the baseline. Preliminary designs were conducted of split path and split torque transmissions to evaluate weight, reliability, and noise. A split path gearbox was determined to be 23 percent lighter, greater than 10 dB quieter, and almost four times more reliable than the baseline two stage planetary design. Detail design studies were conducted of the chosen split path configuration, and drawings were produced of a 1/2 size gearbox consisting of a single engine path of the split path section. Fabrication and testing was then conducted on the 1/2 size gearbox. The 1/2 size gearbox testing proved that the concept of the split path gearbox with high reduction ratio double helical output gear was sound. The improvements were attributed to extensive use of composites, spring clutches, advanced high hot hardness gear steels, the split path configuration itself, high reduction ratio, double helical gearing on the output stage, elastomeric load sharing devices, and elimination of accessory drives.
Bell Helicopter Advanced Rotocraft Transmission (ART) program
NASA Astrophysics Data System (ADS)
Henry, Zachary S.
1995-06-01
Future rotorcraft transmissions require key emerging material and component technologies using advanced and innovative design practices in order to meet the requirements for a reduced weight to power ratio, a decreased noise level, and a substantially increased reliability. The specific goals for the future rotorcraft transmission when compared with a current state-of-the-art transmission (SOAT) are: (1) a 25 percent weight reduction; (2) a 10 dB reduction in the transmitted noise level; and (3) a system reliability of 5000 hours mean-time-between-removal (MTBR) for the transmission. This report summarizes the work conducted by Bell Helicopter Textron, Inc. to achieve these goals under the Advanced Rotorcraft Transmission (ART) program from 1988 to 1995. The reference aircraft selected by BHTI for the ART program was the Tactical Tiltrotor which is a 17,000 lb gross weight aircraft. A tradeoff study was conducted comparing the ART with a Selected SOAT. The results showed the ART to be 29 percent lighter and up to 13 dB quieter with a calculated MTBR in excess of 5000 hours. The results of the following high risk component and material tests are also presented: (1) sequential meshing high contact ratio planetary with cantilevered support posts; (2) thin dense chrome plated M50 NiL double row spherical roller planetary bearings; (3) reduced kinematic error and increased bending strength spiral bevel gears; (4) high temperature WE43 magnesium housing evaluation and coupon corrosion tests; (5) flexure fatigue tests of precision forged coupons simulating precision forged gear teeth; and (6) flexure fatigue tests of plasma carburized coupons simulating plasma carburized gear teeth.
Bell Helicopter Advanced Rotocraft Transmission (ART) program
NASA Technical Reports Server (NTRS)
Henry, Zachary S.
1995-01-01
Future rotorcraft transmissions require key emerging material and component technologies using advanced and innovative design practices in order to meet the requirements for a reduced weight to power ratio, a decreased noise level, and a substantially increased reliability. The specific goals for the future rotorcraft transmission when compared with a current state-of-the-art transmission (SOAT) are: (1) a 25 percent weight reduction; (2) a 10 dB reduction in the transmitted noise level; and (3) a system reliability of 5000 hours mean-time-between-removal (MTBR) for the transmission. This report summarizes the work conducted by Bell Helicopter Textron, Inc. to achieve these goals under the Advanced Rotorcraft Transmission (ART) program from 1988 to 1995. The reference aircraft selected by BHTI for the ART program was the Tactical Tiltrotor which is a 17,000 lb gross weight aircraft. A tradeoff study was conducted comparing the ART with a Selected SOAT. The results showed the ART to be 29 percent lighter and up to 13 dB quieter with a calculated MTBR in excess of 5000 hours. The results of the following high risk component and material tests are also presented: (1) sequential meshing high contact ratio planetary with cantilevered support posts; (2) thin dense chrome plated M50 NiL double row spherical roller planetary bearings; (3) reduced kinematic error and increased bending strength spiral bevel gears; (4) high temperature WE43 magnesium housing evaluation and coupon corrosion tests; (5) flexure fatigue tests of precision forged coupons simulating precision forged gear teeth; and (6) flexure fatigue tests of plasma carburized coupons simulating plasma carburized gear teeth.
Not Available
1990-07-01
The purpose of the Ceramic Technology for Advanced Heat Engines (CTAHE) Project is the development of an industrial technology base capable of providing reliable and cost-effective high temperature ceramic components for application in advanced heat engines. There is a deliberate emphasis on industrial'' in the purpose statement. The project is intended to support the US ceramic and engine industries by providing the needed ceramic materials technology. The heat engine programs have goals of component development and proof-of-concept. The CTAHE Project is aimed at developing generic basic ceramic technology and does not involve specific engine designs and components. The materials research and development efforts in the CTAHE Project are focused on the needs and general requirements of the advanced gas turbine and low heat rejection diesel engines. The CTAHE Project supports the DOE Office of Transportation Systems' heat engine programs, Advanced Turbine Technology Applications (ATTAP) and Heavy Duty Transport (HDT) by providing the basic technology required for development of reliable and cost-effective ceramic components. The heat engine programs provide the iterative component design, fabrication, and test development logic. 103 refs., 18 figs., 11 tabs.
Multigrid approaches to non-linear diffusion problems on unstructured meshes
NASA Technical Reports Server (NTRS)
Mavriplis, Dimitri J.; Bushnell, Dennis M. (Technical Monitor)
2001-01-01
The efficiency of three multigrid methods for solving highly non-linear diffusion problems on two-dimensional unstructured meshes is examined. The three multigrid methods differ mainly in the manner in which the nonlinearities of the governing equations are handled. These comprise a non-linear full approximation storage (FAS) multigrid method which is used to solve the non-linear equations directly, a linear multigrid method which is used to solve the linear system arising from a Newton linearization of the non-linear system, and a hybrid scheme which is based on a non-linear FAS multigrid scheme, but employs a linear solver on each level as a smoother. Results indicate that all methods are equally effective at converging the non-linear residual in a given number of grid sweeps, but that the linear solver is more efficient in cpu time due to the lower cost of linear versus non-linear grid sweeps.
Amplitude relations in non-linear sigma model
NASA Astrophysics Data System (ADS)
Chen, Gang; Du, Yi-Jian
2014-01-01
In this paper, we investigate tree-level scattering amplitude relations in U( N) non-linear sigma model. We use Cayley parametrization. As was shown in the recent works [23,24], both on-shell amplitudes and off-shell currents with odd points have to vanish under Cayley parametrization. We prove the off-shell U(1) identity and fundamental BCJ relation for even-point currents. By taking the on-shell limits of the off-shell relations, we show that the color-ordered tree amplitudes with even points satisfy U(1)-decoupling identity and fundamental BCJ relation, which have the same formations within Yang-Mills theory. We further state that all the on-shell general KK, BCJ relations as well as the minimal-basis expansion are also satisfied by color-ordered tree amplitudes. As a consequence of the relations among color-ordered amplitudes, the total 2 m-point tree amplitudes satisfy DDM form of color decomposition as well as KLT relation.
Experimental study of a linear/non-linear flux rope
NASA Astrophysics Data System (ADS)
DeHaas, Timothy; Gekelman, Walter; Van Compernolle, Bart
2015-08-01
Flux ropes are magnetic structures of helical field lines, accompanied by spiraling currents. Commonly observed on the solar surface extending into the solar atmosphere, flux ropes are naturally occurring and have been observed by satellites in the near earth and in laboratory environments. In this experiment, a single flux rope (r = 2.5 cm, L = 1100 cm) was formed in the cylindrical, magnetized plasma of the Large Plasma Device (LaPD, L = 2200 cm, rplasma = 30 cm, no = 1012 cm-3, Te = 4 eV, He). The flux rope was generated by a DC discharge between an electron emitting cathode and anode. This fixes the rope at its source while allowing it to freely move about the anode. At large currents (I > πr2B0c/2 L), the flux rope becomes helical in structure and oscillates about a central axis. Under varying Alfven speeds and injection current, the transition of the flux rope from stable to kink-unstable was examined. As it becomes non-linear, oscillations in the magnetic signals shift from sinusoidal to Sawtooth-like, associated with elliptical motion of the flux rope; or the signal becomes intermittent as its current density increases.
STATISTICAL BASED NON-LINEAR MODEL UPDATING USING FEATURE EXTRACTION
Schultz, J.F.; Hemez, F.M.
2000-10-01
This research presents a new method to improve analytical model fidelity for non-linear systems. The approach investigates several mechanisms to assist the analyst in updating an analytical model based on experimental data and statistical analysis of parameter effects. The first is a new approach at data reduction called feature extraction. This is an expansion of the update metrics to include specific phenomena or character of the response that is critical to model application. This is an extension of the classical linear updating paradigm of utilizing the eigen-parameters or FRFs to include such devices as peak acceleration, time of arrival or standard deviation of model error. The next expansion of the updating process is the inclusion of statistical based parameter analysis to quantify the effects of uncertain or significant effect parameters in the construction of a meta-model. This provides indicators of the statistical variation associated with parameters as well as confidence intervals on the coefficients of the resulting meta-model, Also included in this method is the investigation of linear parameter effect screening using a partial factorial variable array for simulation. This is intended to aid the analyst in eliminating from the investigation the parameters that do not have a significant variation effect on the feature metric, Finally an investigation of the model to replicate the measured response variation is examined.
Channel Capacity of Non-Linear Transmission Systems
NASA Astrophysics Data System (ADS)
Ellis, Andrew D.; Zhao, Jian
Since their introduction in the late 1970s, the capacity of optical communication links has grown exponentially, fuelled by a series of key innovations including movement between the three telecommunication windows of 850 nm, 1,310 nm and 1,550 nm, distributed feedback laser, erbium-doped fibre amplifiers (EDFAs), dispersion-shifted and dispersion-managed fibre links, external modulation, wavelength division multiplexing, optical switching, forward error correction (FEC), Raman amplification, and most recently, coherent detection, electronic signal processing and optical orthogonal frequency division multiplexing (OFDM). Throughout this evolution, one constant factor has been the use of single-mode optical fibre, whose fundamental principles dated back to the 1800s, when Irish scientist, John Tyndall demonstrated in a lecture to the Royal Society in London that light could be guided through a curved stream of water [1]. Following many developments, including the proposal for waveguides by J.J. Thompson [2], the presentation of detailed calculations for dielectric waveguides by Snitzer [3], the proposal [4] and fabrication [5] of ultra low loss fibres, single-mode fibres were first adopted for non-experimental use in Dorset, UK in 1975, and are still in use today, despite the evolving designs to control chromatic dispersion and non-linearity.
Experimental study of a linear/non-linear flux rope
DeHaas, Timothy; Gekelman, Walter; Van Compernolle, Bart
2015-08-15
Flux ropes are magnetic structures of helical field lines, accompanied by spiraling currents. Commonly observed on the solar surface extending into the solar atmosphere, flux ropes are naturally occurring and have been observed by satellites in the near earth and in laboratory environments. In this experiment, a single flux rope (r = 2.5 cm, L = 1100 cm) was formed in the cylindrical, magnetized plasma of the Large Plasma Device (LaPD, L = 2200 cm, r{sub plasma} = 30 cm, n{sub o} = 10{sup 12 }cm{sup −3}, T{sub e} = 4 eV, He). The flux rope was generated by a DC discharge between an electron emitting cathode and anode. This fixes the rope at its source while allowing it to freely move about the anode. At large currents (I > πr{sup 2}B{sub 0}c/2 L), the flux rope becomes helical in structure and oscillates about a central axis. Under varying Alfven speeds and injection current, the transition of the flux rope from stable to kink-unstable was examined. As it becomes non-linear, oscillations in the magnetic signals shift from sinusoidal to Sawtooth-like, associated with elliptical motion of the flux rope; or the signal becomes intermittent as its current density increases.
Optimum Damping in a Non-Linear Base Isolation System
NASA Astrophysics Data System (ADS)
Jangid, R. S.
1996-02-01
Optimum isolation damping for minimum acceleration of a base-isolated structure subjected to earthquake ground excitation is investigated. The stochastic model of the El-Centro1940 earthquake, which preserves the non-stationary evolution of amplitude and frequency content of ground motion, is used as an earthquake excitation. The base isolated structure consists of a linear flexible shear type multi-storey building supported on a base isolation system. The resilient-friction base isolator (R-FBI) is considered as an isolation system. The non-stationary stochastic response of the system is obtained by the time dependent equivalent linearization technique as the force-deformation of the R-FBI system is non-linear. The optimum damping of the R-FBI system is obtained under important parametric variations; i.e., the coefficient of friction of the R-FBI system, the period and damping of the superstructure; the effective period of base isolation. The criterion selected for optimality is the minimization of the top floor root mean square (r.m.s.) acceleration. It is shown that the above parameters have significant effects on optimum isolation damping.
Non-linear optical measurements using a scanned, Bessel beam
NASA Astrophysics Data System (ADS)
Collier, Bradley B.; Awasthi, Samir; Lieu, Deborah K.; Chan, James W.
2015-03-01
Oftentimes cells are removed from the body for disease diagnosis or cellular research. This typically requires fluorescent labeling followed by sorting with a flow cytometer; however, possible disruption of cellular function or even cell death due to the presence of the label can occur. This may be acceptable for ex vivo applications, but as cells are more frequently moving from the lab to the body, label-free methods of cell sorting are needed to eliminate these issues. This is especially true of the growing field of stem cell research where specialized cells are needed for treatments. Because differentiation processes are not completely efficient, cells must be sorted to eliminate any unwanted cells (i.e. un-differentiated or differentiated into an unwanted cell type). In order to perform label-free measurements, non-linear optics (NLO) have been increasingly utilized for single cell analysis because of their ability to not disrupt cellular function. An optical system was developed for the measurement of NLO in a microfluidic channel similar to a flow cytometer. In order to improve the excitation efficiency of NLO, a scanned Bessel beam was utilized to create a light-sheet across the channel. The system was tested by monitoring twophoton fluorescence from polystyrene microbeads of different sizes. Fluorescence intensity obtained from light-sheet measurements were significantly greater than measurements made using a static Gaussian beam. In addition, the increase in intensity from larger sized beads was more evident for the light-sheet system.
Non linear processes modulated by low doses of radiation exposure
NASA Astrophysics Data System (ADS)
Mariotti, Luca; Ottolenghi, Andrea; Alloni, Daniele; Babini, Gabriele; Morini, Jacopo; Baiocco, Giorgio
The perturbation induced by radiation impinging on biological targets can stimulate the activation of several different pathways, spanning from the DNA damage processing to intra/extra -cellular signalling. In the mechanistic investigation of radiobiological damage this complex “system” response (e.g. omics, signalling networks, micro-environmental modifications, etc.) has to be taken into account, shifting from a focus on the DNA molecule solely to a systemic/collective view. An additional complication comes from the finding that the individual response of each of the involved processes is often not linear as a function of the dose. In this context, a systems biology approach to investigate the effects of low dose irradiations on intra/extra-cellular signalling will be presented, where low doses of radiation act as a mild perturbation of a robustly interconnected network. Results obtained through a multi-level investigation of both DNA damage repair processes (e.g. gamma-H2AX response) and of the activation kinetics for intra/extra cellular signalling pathways (e.g. NFkB activation) show that the overall cell response is dominated by non-linear processes - such as negative feedbacks - leading to possible non equilibrium steady states and to a poor signal-to-noise ratio. Together with experimental data of radiation perturbed pathways, different modelling approaches will be also discussed.
Non-linear saturation mechanism of electron temperature gradient modes
Tokluoglu, E. K.; Sokolov, V.; Sen, A. K.
2012-10-15
The electron temperature gradient (ETG) mode is a very plausible candidate to explain the large electron particle transport and thermal conduction. Production and identification of slab ETG modes and measurement electron transport have been already reported [X. Wei, V. Sokolov, and A. K. Sen, Phys. Plasmas 17, 042108 (2010); V. Sokolov and A. K. Sen, Phys. Rev. Lett. (2011)]. Now, we develop a theoretical model of non-linear saturation mechanism of ETG mode based on the three wave coupling of an unstable high frequency ETG mode with a damped ETG radial harmonic and a damped ion acoustic (IA) mode. Bicoherence analysis of Columbia linear machine (CLM) data show coupling between ETG modes ({approx}2.4 MHz) and a low frequency mode ({approx}50 kHz). The large damping drive of the ETG radial harmonic accompanied by the smaller but finite damping of the IA mode presents an energy sink for the unstable ETG mode, thus causing saturation. This model predicts a saturation level of {approx}10% and agrees with the observed levels of ETG modes in the CLM.
Non-linear analysis and the design of Pumpkin Balloons: stress, stability and viscoelasticity
NASA Astrophysics Data System (ADS)
Rand, J. L.; Wakefield, D. S.
Tensys have a long-established background in the shape generation and load analysis of architectural stressed membrane structures Founded upon their inTENS finite element analysis suite these activities have broadened to encompass lighter than air structures such as aerostats hybrid air-vehicles and stratospheric balloons Winzen Engineering couple many years of practical balloon design and fabrication experience with both academic and practical knowledge of the characterisation of the non-linear viscoelastic response of the polymeric films typically used for high-altitude scientific balloons Both companies have provided consulting services to the NASA Ultra Long Duration Balloon ULDB Program Early implementations of pumpkin balloons have shown problems of geometric instability characterised by improper deployment and these difficulties have been reproduced numerically using inTENS The solution lies in both the shapes of the membrane lobes and also the need to generate a biaxial stress field in order to mobilise in-plane shear stiffness Balloons undergo significant temperature and pressure variations in flight The different thermal characteristics between tendons and film can lead to significant meridional stress Fabrication tolerances can lead to significant local hoop stress concentrations particularly adjacent to the base and apex end fittings The non-linear viscoelastic response of the envelope film acts positively to help dissipate stress concentrations However creep over time may produce lobe geometry variations that may
A Fully Associative, Non-Linear Kinematic, Unified Viscoplastic Model for Titanium Based Matrices
NASA Technical Reports Server (NTRS)
Arnold, S. M.; Saleeb, A. F.; Castelli, M. G.
1994-01-01
Specific forms for both the Gibb's and complementary dissipation potentials are chosen such that a complete (i.e., fully associative) potential based multiaxial unified viscoplastic model is obtained. This model possesses one tensorial internal state variable that is associated with dislocation substructure, with an evolutionary law that has nonlinear kinematic hardening and both thermal and strain induced recovery mechanisms. A unique aspect of the present model is the inclusion of non-linear hardening through the use of a compliance operator, derived from the Gibb's potential, in the evolution law for the back stress. This non-linear tensorial operator is significant in that it allows both the flow and evolutionary laws to be fully associative (and therefore easily integrated) and greatly influences the multiaxial response under non-proportional loading paths. In addition to this nonlinear compliance operator, a new consistent, potential preserving, internal strain unloading criterion has been introduced to prevent abnormalities in the predicted stress-strain curves, which are present with nonlinear hardening formulations, during unloading and reversed loading of the external variables. Specification of an experimental program for the complete determination of the material functions and parameters for characterizing a metallic matrix, e.g., TIMETAL 21S, is given. The experiments utilized are tensile, creep, and step creep tests. Finally, a comparison of this model and a commonly used Bodner-Partom model is made on the basis of predictive accuracy and numerical efficiency.
NASA Astrophysics Data System (ADS)
Adcock, T. A. A.; Taylor, P. H.
2016-01-01
The non-linear Schrödinger equation and its higher order extensions are routinely used for analysis of extreme ocean waves. This paper compares the evolution of individual wave-packets modelled using non-linear Schrödinger type equations with packets modelled using fully non-linear potential flow models. The modified non-linear Schrödinger Equation accurately models the relatively large scale non-linear changes to the shape of wave-groups, with a dramatic contraction of the group along the mean propagation direction and a corresponding extension of the width of the wave-crests. In addition, as extreme wave form, there is a local non-linear contraction of the wave-group around the crest which leads to a localised broadening of the wave spectrum which the bandwidth limited non-linear Schrödinger Equations struggle to capture. This limitation occurs for waves of moderate steepness and a narrow underlying spectrum.
Phenomenon of life: between equilibrium and non-linearity.
Galimov, E M
2004-12-01
A model of ordering applicable to biological evolution is presented. It is shown that a steady state (more precisely approaching to a steady state) system of irreversible processes, under conditions of disproportionation of entropy, produces a lower-entropy product, that is, ordering. The ordering is defined as restricting of degrees of freedom: freedom of motion, interactions etc. The model differs from previous ones in that it relates the ordering to processes running not far from equilibrium, described in the linear field of non-equilibrium thermodynamics. It is shown that a system, which includes adenosine triphosphate (ATP) to adenosine diphosphate (ADP) conversion meets the demands of the physical model: it provides energy maintaining steady state conditions, and hydrolysis of ATP proceeding with consumption of water can be tightly conjugated with the most important reactions of synthesis of organic polymers (peptides, nucleotide chains etc.), which proceed with release of water. For these and other reasons ATP seems to be a key molecule of prebiotic evolution. It is argued that the elementary chemical reaction proceeding under control of an enzyme is not necessarily far from equilibrium. The experimental evidence supporting this idea, is presented. It is based on isotope data. Carbon isotope distribution in biochemical systems reveals regularity, which is inherent to steady state systems of chemical reactions, proceeding not far from equilibrium. In living organisms this feature appears at the statistical level, as many completely irreversible and non-linear processes occur in organisms. However not-far-from-equilibrium reactions are inherent to biochemical systems as a matter of principle. They are reconcilable with biochemical behavior. Extant organisms are highly evolved entities which, however, show in their basis the same features, as the simplest chemical systems must have had been involved in the origin of life. Some consequences following from the
Non-linear pattern formation in bone growth and architecture.
Salmon, Phil
2014-01-01
The three-dimensional morphology of bone arises through adaptation to its required engineering performance. Genetically and adaptively bone travels along a complex spatiotemporal trajectory to acquire optimal architecture. On a cellular, micro-anatomical scale, what mechanisms coordinate the activity of osteoblasts and osteoclasts to produce complex and efficient bone architectures? One mechanism is examined here - chaotic non-linear pattern formation (NPF) - which underlies in a unifying way natural structures as disparate as trabecular bone, swarms of birds flying, island formation, fluid turbulence, and others. At the heart of NPF is the fact that simple rules operating between interacting elements, and Turing-like interaction between global and local signals, lead to complex and structured patterns. The study of "group intelligence" exhibited by swarming birds or shoaling fish has led to an embodiment of NPF called "particle swarm optimization" (PSO). This theoretical model could be applicable to the behavior of osteoblasts, osteoclasts, and osteocytes, seeing them operating "socially" in response simultaneously to both global and local signals (endocrine, cytokine, mechanical), resulting in their clustered activity at formation and resorption sites. This represents problem-solving by social intelligence, and could potentially add further realism to in silico computer simulation of bone modeling. What insights has NPF provided to bone biology? One example concerns the genetic disorder juvenile Pagets disease or idiopathic hyperphosphatasia, where the anomalous parallel trabecular architecture characteristic of this pathology is consistent with an NPF paradigm by analogy with known experimental NPF systems. Here, coupling or "feedback" between osteoblasts and osteoclasts is the critical element. This NPF paradigm implies a profound link between bone regulation and its architecture: in bone the architecture is the regulation. The former is the emergent
Non-Linear Pattern Formation in Bone Growth and Architecture
Salmon, Phil
2014-01-01
The three-dimensional morphology of bone arises through adaptation to its required engineering performance. Genetically and adaptively bone travels along a complex spatiotemporal trajectory to acquire optimal architecture. On a cellular, micro-anatomical scale, what mechanisms coordinate the activity of osteoblasts and osteoclasts to produce complex and efficient bone architectures? One mechanism is examined here – chaotic non-linear pattern formation (NPF) – which underlies in a unifying way natural structures as disparate as trabecular bone, swarms of birds flying, island formation, fluid turbulence, and others. At the heart of NPF is the fact that simple rules operating between interacting elements, and Turing-like interaction between global and local signals, lead to complex and structured patterns. The study of “group intelligence” exhibited by swarming birds or shoaling fish has led to an embodiment of NPF called “particle swarm optimization” (PSO). This theoretical model could be applicable to the behavior of osteoblasts, osteoclasts, and osteocytes, seeing them operating “socially” in response simultaneously to both global and local signals (endocrine, cytokine, mechanical), resulting in their clustered activity at formation and resorption sites. This represents problem-solving by social intelligence, and could potentially add further realism to in silico computer simulation of bone modeling. What insights has NPF provided to bone biology? One example concerns the genetic disorder juvenile Pagets disease or idiopathic hyperphosphatasia, where the anomalous parallel trabecular architecture characteristic of this pathology is consistent with an NPF paradigm by analogy with known experimental NPF systems. Here, coupling or “feedback” between osteoblasts and osteoclasts is the critical element. This NPF paradigm implies a profound link between bone regulation and its architecture: in bone the architecture is the regulation. The former is the
Non-linear scission/recombination kinetics of living polymerization
NASA Astrophysics Data System (ADS)
Nyrkova, I. A.; Semenov, A. N.
2007-10-01
Living polymers are formed by reversible association of primary units (unimers). Generally the chain statistical weight involves a factor σ < 1 suppressing short chains in comparison with free unimers. Living polymerization is a sharp thermodynamic transition for σ ≪ 1 which is typically the case. We show that this sharpness has an important effect on the kinetics of living polymerization (one-dimensional association). The kinetic model involves i) the unimer activation step (a transition to an assembly-competent state); ii) the scission/recombination processes providing growth of polymer chains and relaxation of their length distribution. Analyzing the polymerization with no chains but unimers at t = 0 , with initial concentration of unimers M ≳ M* (M* is the critical polymerization concentration), we determine the time evolution of the chain length distribution and find that: 1) for M* ≪ M ≪ M*/σ the kinetics is characterized by 5 distinct time stages demarcated by 4 characteristic times t1, t2, t3 and t*; 2) there are transient regimes (t1 ≲ t ≲ t3) when the molecular-weight distribution is strongly non-exponential; 3) the chain scissions are negligible at times shorter than t2. The chain growth is auto-accelerated for t1 ≲ t ≲ t2 : the cut-off chain length (= polymerization degree
The non-linear initiation of diapirs and plume heads
NASA Astrophysics Data System (ADS)
Bercovici, David; Kelly, Amanda
1997-04-01
A simple theory is devised to describe the non-linear feedback mechanisms involved in the initial growth of a single diapir or plume head from a low viscosity channel overlain by a much more viscous layer. Such feedbacks arise primarily from the relation between the growth of a proto-diapir (i.e. an undulation on the upper boundary of the low viscosity channel) and the draining of the low viscosity channel. In the period of time between its initial exponential growth (characterized by linear stability analysis) and its separation from the low viscosity channel as a fully formed diapir, the proto-diapir can undergo a significant cessation in its development due to deflation of the low viscosity channel; i.e. the proto-diapir's growth can essentially stall for a long period of time before it separates and begins its ascent through the overlying medium. The theory is used to determine a criterion for separation of the diapir from the low viscosity channel that is in terms of the geometrical and mechanical properties of the channel, instead of the ad hoc volume flux widely used in many models of mantle plumes and plume heads (e.g. Whitehead and Luther, 1975; Richards et al., 1989; Olson, 1990; Sleep, 1990; Bercovici and Mahoney, 1994). From this separation criterion, self-consistent scaling laws can be formulated to relate the size of the fully developed diapir and its trailing conduit to the properties of the initial channel, instead of to the ad hoc volume flux. Basic laboratory experiments involving highly viscous fluids are presented and demonstrate that the so-called 'stalling' period between initial growth and separation does indeed occur. These results suggest that nascent mantle plume heads may stall for extended periods at the base of the mantle and thereby contribute to variations in thickness of the D″ layer.
Simulation of non-linear coregionalization models by FFTMA
NASA Astrophysics Data System (ADS)
Liang, Min; Marcotte, Denis; Shamsipour, Pejman
2016-04-01
A fast and efficient method to simulate multivariate fields with non-linear models of coregionalization (N-LMC) is described. The method generalizes FFTMA to the multivariate simulation of the N-LMC with symmetric cross-covariances, hence the name GFFTMA. It allows us for example to use an exponential model as the direct covariance for the main variable, a Cauchy model for the secondary variable and a K-Bessel model for the cross-covariance. Each covariance and cross-covariance are Fast Fourier Transformed (FFT) to get the discrete spectral densities. Then the spectral matrix is eigen-decomposed at each frequency separately to provide the square root matrix and to enforce positive-definiteness in cases where small negative eigenvalues are found. Finally the simulated spectrum is obtained as multiplication of the root matrix and the white noise coefficients. The method is particularly fast for covariances having derivatives at the origin and/or for covariances with long range. Hence, two-variables' 2D fields of 100 million pixels with all-Gaussian or all-cubic covariances and cross-covariance are both simulated in less than 200 s. The CPU-time increases only as N log(N) (N, the number of points to simulate). Additional realizations are obtained at a low marginal cost as the eigen-decomposition step needs to be done only once for the first realization. The main limitation of the approach is its rather stringent memory requirement. Synthetic examples illustrate the simulations of N-LMC with two and three variables for different combinations of the seven available models. It shows that the theoretical models are all well reproduced. An illustrative case-study on overburden thickness simulation is provided where the secondary information consists of a latent Gaussian variable identifying the geological domain.
The NASA-JPL advanced propulsion program
NASA Technical Reports Server (NTRS)
Frisbee, Robert H.
1994-01-01
The NASA Advanced Propulsion Concepts (APC) program at the Jet Propulsion Laboratory (JPL) consists of two main areas: The first involves cooperative modeling and research activities between JPL and various universities and industry; the second involves research at universities and industry that is directly supported by JPL. The cooperative research program consists of mission studies, research and development of ion engine technology using C-60 (Buckminsterfullerene) propellant, and research and development of lithium-propellant Lorentz-force accelerator (LFA) engine technology. The university/industry- supported research includes research (modeling and proof-of-concept experiments) in advanced, long-life electric propulsion, and in fusion propulsion. These propulsion concepts were selected primarily to cover a range of applications from near-term to far-term missions. For example, the long-lived pulsed-xenon thruster research that JPL is supporting at Princeton University addresses the near-term need for efficient, long-life attitude control and station-keeping propulsion for Earth-orbiting spacecraft. The C-60-propellant ion engine has the potential for good efficiency in a relatively low specific impulse (Isp) range (10,000 - 30,000 m/s) that is optimum for relatively fast (less than 100 day) cis-lunar (LEO/GEO/Lunar) missions employing near-term, high-specific mass electric propulsion vehicles. Research and modeling on the C-60-ion engine are currently being performed by JPL (engine demonstration), Caltech (C-60 properties), MIT (plume modeling), and USC (diagnostics). The Li-propellant LFA engine also has good efficiency in the modest Isp range (40,000 - 50,000 m/s) that is optimum for near-to-mid-term megawatt-class solar- and nuclear-electric propulsion vehicles used for Mars missions transporting cargo (in support of a piloted mission). Research and modeling on the Li-LFA engine are currently being performed by JPL (cathode development), Moscow Aviation
The Advanced Controls Program at Oak Ridge National Laboratory
Knee, H.E.; White, J.D.
1990-01-01
The Oak Ridge National Laboratory (ORNL), under sponsorship of the US Department of Energy (DOE), is conducting research that will lead to advanced, automated control of new liquid-metal-reactor (LMR) nuclear power plants. Although this program of research (entitled the Advanced Controls Program'') is focused on LMR technology, it will be capable of providing control design, test, and qualification capability for other advanced reactor designs (e.g., the advanced light water reactor (ALWR) and high temperature gas-cooled reactor (HTGR) designs), while also benefiting existing nuclear plants. The Program will also have applicability to complex, non-nuclear process control environments (e.g., petrochemical, aerospace, etc.). The Advanced Controls Program will support capabilities throughout the entire plant design life cycle, i.e., from the initial interactive first-principle dynamic model development for the process, systems, components, and instruments through advanced control room qualification. The current program involves five principal areas of research activities: (1) demonstrations of advanced control system designs, (2) development of an advanced controls design environment, (3) development of advanced control strategies, (4) research and development (R D) in human-system integration for advanced control system designs, and (5) testing and validation of advanced control system designs. Discussion of the research in these five areas forms the basis of this paper. Also included is a description of the research directions of the program. 8 refs.
Grossi, E
2006-01-01
Summary The relationship between the different symptoms of gastro-oesophageal reflux disease remain markedly obscure due to the high underlying non-linearity and the lack of studies focusing on the problem. Aim of this study was to evaluate the hidden relationships between the triad of symptoms related to gastro-oesophageal reflux disease using advanced mathematical techniques, borrowed from the artificial intelligence field, in a cohort of patients with oesophagitis. A total of 388 patients (from 60 centres) with endoscopic evidence of oesophagitis were recruited. The severity of oesophagitis was scored by means of the Savary-Miller classification. PST algorithm was employed. This study shows that laryngo-pharyngeal symptoms related to gastro-oesophageal reflux disease are correlated even if in a non-linear way. PMID:17345935
Grossi, E
2006-10-01
The relationship between the different symptoms of gastro-oesophageal reflux disease remain markedly obscure due to the high underlying non-linearity and the lack of studies focusing on the problem. Aim of this study was to evaluate the hidden relationships between the triad of symptoms related to gastro-oesophageal reflux disease using advanced mathematical techniques, borrowed from the artificial intelligence field, in a cohort of patients with oesophagitis. A total of 388 patients (from 60 centres) with endoscopic evidence of oesophagitis were recruited. The severity of oesophagitis was scored by means of the Savary-Miller classification. PST algorithm was employed. This study shows that laryngo-pharyngeal symptoms related to gastro-oesophageal reflux disease are correlated even if in a non-linear way. PMID:17345935
Federal Register 2010, 2011, 2012, 2013, 2014
2013-11-01
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Advanced imaging systems programs at DARPA MTO
NASA Astrophysics Data System (ADS)
Dhar, Nibir K.; Elizondo, Lee A.; Dat, Ravi; Elizondo, Shelly L.
2013-09-01
In this paper, we review a few selected imaging technology development programs at the Defense Advanced Research Projects Agency (DARPA) in the reflective visible to the emissive/thermal long wave infrared (LWIR) spectral bands. For the reflective visible band, results are shown for two different imagers: a gigapixel monocentric multi-scale camera design that solves the scaling issues for a high pixel count, and a wide field of view and a single photon detection camera with a large dynamic range. Also, a camera with broadband capability covering both reflective and thermal bands (0.5 μm to 5.0 μm) with >80% quantum efficiency is discussed. In the emissive/thermal band, data is presented for both uncooled and cryogenically cooled LWIR detectors with pixel pitches approaching the fundamental detection limits. By developing wafer scale manufacturing processes and reducing the pixel size of uncooled thermal imagers, it is shown that an affordable camera on a chip, capable of seeing through obscurants in day or night, is feasible. Also, the fabrication and initial performance of the world's first 5 μm pixel pitch LWIR camera is discussed. Lastly, we use an initial model to evaluate the signal to noise ratio and noise equivalent differential temperature as a function of well capacity to predict the performance for this thermal imager.
ALS liquid hydrogen turbopump: Advanced Development Program
NASA Technical Reports Server (NTRS)
Shimp, Nancy R.; Claffy, George J.
1989-01-01
The point of departure (POD) turbopump concept was reviewed and finalized. The basis for the POD was the configuration presented in the Aerojet proposal. After reviewing this proposal concept, several modifications were made. These modifications include the following: (1) the dual pump discharge arrangement was changed to a single discharge; (2) commonality of the turbine inlet manifold with the advanced launch system (ALS) liquid oxygen (LOX) TPA was dropped for this program; (3) the turbine housing flange arrangement was improved by relocating it away from the first stage nozzles; (4) a ten percent margin (five percent diameter increase) was built into the impeller design to ensure meeting the required discharge pressure without the need for increasing speed; (5) a ten percent turbine power margin was imposed which is to be obtained by increasing turbine inlet pressure if required; and (6) the backup concept, as an alternative to the use of cast impellers, now incorporates forged/machined shrouded impellers, rather than the unshrouded type originally planned.
Linear and non-linear wall friction of wet foams.
Le Merrer, Marie; Lespiat, Rémi; Höhler, Reinhard; Cohen-Addad, Sylvie
2015-01-14
We study the wall slip of aqueous foams with a high liquid content. We use a set-up where, driven by buoyancy, a foam creeps along an inclined smooth solid wall which is immersed in the foaming solution. This configuration allows the force driving the bubble motion and the bubble confinement in the vicinity of the wall to be tuned independently. First, we consider bubble monolayers with small Bond number Bo < 1 and measure the relation between the friction force F and the bubble velocity V. For bubbles which are so small that they are almost spherical, the friction law F ∝ V is Stokes-like. The analysis shows that the minimal thickness of the lubricating contact between the bubble and the wall is governed by DLVO long-range forces. Our results are the first evidence of this predicted linear friction regime for creeping bubbles. Due to buoyancy, large bubbles flatten against the wall. In this case, dissipation arises because of viscous flow in the dynamic meniscus between the contact film and the spherical part of the bubble. It leads to a non-linear Bretherton-like friction law F ∝ V(2/3), as expected for slipping bubbles with mobile liquid-gas interfaces. The Stokes-like friction dominates for capillary numbers Ca larger than the crossover value Ca* ∼ Bo(3/2). The overall friction force can be expressed as the sum of these two contributions. On this basis, we then study 3D foams close to the jamming transition with osmotic pressures Π small compared to the capillary pressure Pc. We measure the wall shear stress τ as a function of the capillary number, and we evidence two friction regimes that are consistent with those found for the monolayer. Similarly to this latter case, the total shear stress can be expressed as the sum of the Stokes-like friction term τ ∝ Ca and the Bretherton-like one τ ∝ Ca(2/3). However, for a 3D foam, the crossover at a capillary number Ca** between both regimes is governed by the ratio of the osmotic pressure to the
Entropy, non-linearity and hierarchy in ecosystems
NASA Astrophysics Data System (ADS)
Addiscott, T.
2009-04-01
Soil-plant systems are open systems thermodynamically because they exchange both energy and matter with their surroundings. Thus they are properly described by the second and third of the three stages of thermodynamics defined by Prigogine and Stengers (1984). The second stage describes a system in which the flow is linearly related to the force. Such a system tends towards a steady state in which entropy production is minimized, but it depends on the capacity of the system for self-organization. In a third stage system, flow is non-linearly related to force, and the system can move far from equilibrium. This system maximizes entropy production but in so doing facilitates self-organization. The second stage system was suggested earlier to provide a useful analogue of the behaviour of natural and agricultural ecosystems subjected to perturbations, but it needs the capacity for self-organization. Considering an ecosystem as a hierarchy suggests this capacity is provided by the soil population, which releases from dead plant matter nutrients such as nitrate, phosphate and captions needed for growth of new plants and the renewal of the whole ecosystem. This release of small molecules from macromolecules increases entropy, and the soil population maximizes entropy production by releasing nutrients and carbon dioxide as vigorously as conditions allow. In so doing it behaves as a third stage thermodynamic system. Other authors (Schneider and Kay, 1994, 1995) consider that it is in the plants in an ecosystem that maximize entropy, mainly through transpiration, but studies on transpiration efficiency suggest that this is questionable. Prigogine, I. & Stengers, I. 1984. Order out of chaos. Bantam Books, Toronto. Schneider, E.D. & Kay, J.J. 1994. Life as a manifestation of the Second Law of Thermodynamics. Mathematical & Computer Modelling, 19, 25-48. Schneider, E.D. & Kay, J.J. 1995. Order from disorder: The Thermodynamics of Complexity in Biology. In: What is Life: the Next
Surface and Atmospheric Parameter Retrieval From AVIRIS Data: The Importance of Non-Linear Effects
NASA Technical Reports Server (NTRS)
Green Robert O.; Moreno, Jose F.
1996-01-01
AVIRIS data represent a new and important approach for the retrieval of atmospheric and surface parameters from optical remote sensing data. Not only as a test for future space systems, but also as an operational airborne remote sensing system, the development of algorithms to retrieve information from AVIRIS data is an important step to these new approaches and capabilities. Many things have been learned since AVIRIS became operational, and the successive technical improvements in the hardware and the more sophisticated calibration techniques employed have increased the quality of the data to the point of almost meeting optimum user requirements. However, the potential capabilities of imaging spectrometry over the standard multispectral techniques have still not been fully demonstrated. Reasons for this are the technical difficulties in handling the data, the critical aspect of calibration for advanced retrieval methods, and the lack of proper models with which to invert the measured AVIRIS radiances in all the spectral channels. To achieve the potential of imaging spectrometry, these issues must be addressed. In this paper, an algorithm to retrieve information about both atmospheric and surface parameters from AVIRIS data, by using model inversion techniques, is described. Emphasis is put on the derivation of the model itself as well as proper inversion techniques, robust to noise in the data and an inadequate ability of the model to describe natural variability in the data. The problem of non-linear effects is addressed, as it has been demonstrated to be a major source of error in the numerical values retrieved by more simple, linear-based approaches. Non-linear effects are especially critical for the retrieval of surface parameters where both scattering and absorption effects are coupled, as well as in the cases of significant multiple-scattering contributions. However, sophisticated modeling approaches can handle such non-linear effects, which are especially