Launch ascent guidance by discrete multi-model predictive control
NASA Astrophysics Data System (ADS)
Vachon, Alexandre; Desbiens, André; Gagnon, Eric; Bérard, Caroline
2014-02-01
This paper studies the application of discrete multi-model predictive control as a trajectory tracking guidance law for a space launcher. Two different algorithms are developed, each one based on a different representation of launcher translation dynamics. These representations are based on an interpolation of the linear approximation of nonlinear pseudo-five degrees of freedom equations of translation around an elliptical Earth. The interpolation gives a linear-time-varying representation and a linear-fractional representation. They are used as the predictive model of multi-model predictive controllers. The controlled variables are the orbital parameters, and constraints on a terminal region for the minimal accepted precision are also included. Use of orbital parameters as the controlled variables allows for a partial definition of the trajectory. Constraints can also be included in multi-model predictive control to reduce the number of unknowns of the problem by defining input shaping constraints. The guidance algorithms are tested in nominal conditions and off-nominal conditions with uncertainties on the thrust. The results are compared to those of a similar formulation with a nonlinear model predictive controller and to a guidance method based on the resolution of a simplified version of the two-point boundary value problem. In nominal conditions, the model predictive controllers are more precise and produce a more optimal trajectory but are longer to compute than the two-point boundary solution. Moreover, in presence of uncertainties, developed algorithms exhibit poor robustness properties. The multi-model predictive control algorithms do not reach the desired orbit while the nonlinear model predictive control algorithm still converges but produces larger maneuvers than the other method.
Adaptive discrete cosine transform based image coding
NASA Astrophysics Data System (ADS)
Hu, Neng-Chung; Luoh, Shyan-Wen
1996-04-01
In this discrete cosine transform (DCT) based image coding, the DCT kernel matrix is decomposed into a product of two matrices. The first matrix is called the discrete cosine preprocessing transform (DCPT), whose kernels are plus or minus 1 or plus or minus one- half. The second matrix is the postprocessing stage treated as a correction stage that converts the DCPT to the DCT. On applying the DCPT to image coding, image blocks are processed by the DCPT, then a decision is made to determine whether the processed image blocks are inactive or active in the DCPT domain. If the processed image blocks are inactive, then the compactness of the processed image blocks is the same as that of the image blocks processed by the DCT. However, if the processed image blocks are active, a correction process is required; this is achieved by multiplying the processed image block by the postprocessing stage. As a result, this adaptive image coding achieves the same performance as the DCT image coding, and both the overall computation and the round-off error are reduced, because both the DCPT and the postprocessing stage can be implemented by distributed arithmetic or fast computation algorithms.
An averaging analysis of discrete-time indirect adaptive control
NASA Technical Reports Server (NTRS)
Phillips, Stephen M.; Kosut, Robert L.; Franklin, Gene F.
1988-01-01
An averaging analysis of indirect, discrete-time, adaptive control systems is presented. The analysis results in a signal-dependent stability condition and accounts for unmodeled plant dynamics as well as exogenous disturbances. This analysis is applied to two discrete-time adaptive algorithms: an unnormalized gradient algorithm and a recursive least-squares (RLS) algorithm with resetting. Since linearization and averaging are used for the gradient analysis, a local stability result valid for small adaptation gains is found. For RLS with resetting, the assumption is that there is a long time between resets. The results for the two algorithms are virtually identical, emphasizing their similarities in adaptive control.
Guidance and Actuation Systems for an Adaptive-Suspension Vehicle
1984-03-14
FORM 1. REPORT NUMBER 2. GOVT ACCESSION NO. 3 . RECIPIENT’S CATALOG NUMBER G8186-685-84 ’D Ji 4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED...Adaptive-Suspension Vehicle ..... ........ 2 2.2.2 The Terrain-Sensing System ...... .......... 3 2.3 Guidance System Algorithms... 3 2.3.1 Overview ............. ................... 3 2.3.2 Elevation Map Algorithms ...... ........... 3 2.3.3 Vehicle Guidance Algorithms
Adaptive guidance for an aero-assisted boost vehicle
NASA Technical Reports Server (NTRS)
Pamadi, Bandu N.; Taylor, Lawrence W., Jr.; Price, Douglas B.
1988-01-01
An adaptive guidance system incorporating dynamic pressure constraint is studied for a single stage to low earth orbit (LEO) aero-assist booster with thrust gimbal angle as the control variable. To derive an adaptive guidance law, cubic spline functions are used to represent the ascent profile. The booster flight to LEO is divided into initial and terminal phases. In the initial phase, the ascent profile is continuously updated to maximize the performance of the boost vehicle enroute. A linear feedback control is used in the terminal phase to guide the aero-assisted booster onto the desired LEO. The computer simulation of the vehicle dynamics considers a rotating spherical earth, inverse square (Newtonian) gravity field and an exponential model for the earth's atmospheric density. This adaptive guidance algorithm is capable of handling large deviations in both atmospheric conditions and modeling uncertainties, while ensuring maximum booster performance.
Discrete-time adaptive control of robot manipulators
NASA Technical Reports Server (NTRS)
Tarokh, M.
1989-01-01
A discrete-time model reference adaptive control scheme is developed for trajectory tracking of robot manipulators. Hyperstability theory is utilized to derive the adaptation laws for the controller gain matrices. It is shown that asymptotic trajectory tracking is achieved despite gross robot parameter variation and uncertainties. The method offers considerable design flexibility and enables the designer to improve the performance of the control system by adjusting free design parameters. The discrete-time adaptation algorithm is extremely simple and is therefore suitable for real-time implementation.
Adaptive pattern for autonomous UAV guidance
NASA Astrophysics Data System (ADS)
Sung, Chen-Ko; Segor, Florian
2013-09-01
The research done at the Fraunhofer IOSB in Karlsruhe within the AMFIS project is focusing on a mobile system to support rescue forces in accidents or disasters. The system consists of a ground control station which has the capability to communicate with a large number of heterogeneous sensors and sensor carriers and provides several open interfaces to allow easy integration of additional sensors into the system. Within this research we focus mainly on UAV such as VTOL (Vertical takeoff and Landing) systems because of their ease of use and their high maneuverability. To increase the positioning capability of the UAV, different onboard processing chains of image exploitation for real time detection of patterns on the ground and the interfacing technology for controlling the UAV from the payload during flight were examined. The earlier proposed static ground pattern was extended by an adaptive component which admits an additional visual communication channel to the aircraft. For this purpose different components were conceived to transfer additive information using changeable patterns on the ground. The adaptive ground pattern and their application suitability had to be tested under external influence. Beside the adaptive ground pattern, the onboard process chains and the adaptations to the demands of changing patterns are introduced in this paper. The tracking of the guiding points, the UAV navigation and the conversion of the guiding point positions from the images to real world co-ordinates in video sequences, as well as use limits and the possibilities of an adaptable pattern are examined.
NASA Technical Reports Server (NTRS)
Kantor, A. V.; Timonin, V. G.; Azarova, Y. S.
1974-01-01
The method of adaptive discretization is the most promising for elimination of redundancy from telemetry messages characterized by signal shape. Adaptive discretization with associative sorting was considered as a way to avoid the shortcomings of adaptive discretization with buffer smoothing and adaptive discretization with logical switching in on-board information compression devices (OICD) in spacecraft. Mathematical investigations of OICD are presented.
Discrete adaptive zone light elements (DAZLE): a new approach to adaptive imaging
NASA Astrophysics Data System (ADS)
Kellogg, Robert L.; Escuti, Michael J.
2007-09-01
New advances in Liquid Crystal Spatial Light Modulators (LCSLM) offer opportunities for large adaptive optics in the midwave infrared spectrum. A light focusing adaptive imaging system, using the zero-order diffraction state of a polarizer-free liquid crystal polarization grating modulator to create millions of high transmittance apertures, is envisioned in a system called DAZLE (Discrete Adaptive Zone Light Elements). DAZLE adaptively selects large sets of LCSLM apertures using the principles of coded masks, embodied in a hybrid Discrete Fresnel Zone Plate (DFZP) design. Issues of system architecture, including factors of LCSLM aperture pattern and adaptive control, image resolution and focal plane array (FPA) matching, and trade-offs between filter bandwidths, background photon noise, and chromatic aberration are discussed.
Discrete model reference adaptive control with an augmented error signal
NASA Technical Reports Server (NTRS)
Ionescu, T.; Monopoli, R.
1975-01-01
A method for designing discrete model reference adaptive control systems when one has access to only the plant's input and output signals is given. Controllers for single-input, single-output, nonlinear, nonautonomous plants are developed via Liapunov's second method. Anticipative values of the plant output are not required, but are replaced by signals easily obtained from a low-pass filter operating on the plant's output. The augmented error signal method is employed, ensuring finally that the normally used error signal also approaches zero asymptotically.
ADART: an adaptive algebraic reconstruction algorithm for discrete tomography.
Maestre-Deusto, F Javier; Scavello, Giovanni; Pizarro, Joaquín; Galindo, Pedro L
2011-08-01
In this paper we suggest an algorithm based on the Discrete Algebraic Reconstruction Technique (DART) which is capable of computing high quality reconstructions from substantially fewer projections than required for conventional continuous tomography. Adaptive DART (ADART) goes a step further than DART on the reduction of the number of unknowns of the associated linear system achieving a significant reduction in the pixel error rate of reconstructed objects. The proposed methodology automatically adapts the border definition criterion at each iteration, resulting in a reduction of the number of pixels belonging to the border, and consequently of the number of unknowns in the general algebraic reconstruction linear system to be solved, being this reduction specially important at the final stage of the iterative process. Experimental results show that reconstruction errors are considerably reduced using ADART when compared to original DART, both in clean and noisy environments.
ADGS-2100 Adaptive Display and Guidance System Window Manager Analysis
NASA Technical Reports Server (NTRS)
Whalen, Mike W.; Innis, John D.; Miller, Steven P.; Wagner, Lucas G.
2006-01-01
Recent advances in modeling languages have made it feasible to formally specify and analyze the behavior of large system components. Synchronous data flow languages, such as Lustre, SCR, and RSML-e are particularly well suited to this task, and commercial versions of these tools such as SCADE and Simulink are growing in popularity among designers of safety critical systems, largely due to their ability to automatically generate code from the models. At the same time, advances in formal analysis tools have made it practical to formally verify important properties of these models to ensure that design defects are identified and corrected early in the lifecycle. This report describes how these tools have been applied to the ADGS-2100 Adaptive Display and Guidance Window Manager being developed by Rockwell Collins Inc. This work demonstrates how formal methods can be easily and cost-efficiently used to remove defects early in the design cycle.
Mathematics of adaptive wavelet transforms: relating continuous with discrete transforms
NASA Astrophysics Data System (ADS)
Szu, Harold H.; Telfer, Brian A.
1994-07-01
We prove several theorems and construct explicitly the bridge between the continuous and discrete adaptive wavelet transform (AWT). The computational efficiency of the AWT is a result of its compact support closely matching linearly the signal's time-frequency characteristics, and is also a result of a larger redundancy factor of the superposition-mother s(x) (super-mother), created adaptively by a linear superposition of other admissible mother wavelets. The super-mother always forms a complete basis, but is usually associated with a higher redundancy number than its constituent complete orthonormal bases. The robustness of super-mother suffers less noise contamination (since noise is everywhere, and a redundant sampling by bandpassings can suppress the noise and enhance the signal). Since the continuous super-mother has been created off-line by AWT (using least-mean- squares neural nets), we wish to accomplish fast AWT on line. Thus, we formulate AWT in discrete high-pass (H) and low-pass (L) filter bank coefficients via the quadrature mirror filter, (QMF), a digital subband lossless coding. A linear combination of two special cases of complete biorthogonal normalized (Cbi-ON) QMF [L(z), H(z), L+(z), H+(z)], called (alpha) -bank and (Beta) -bank, becomes a hybrid a(alpha) + b(Beta) -bank (for any real positive constants a and b) that is still admissible, meaning Cbi-ON and lossless. Finally, the power of AWT is the implementation by means of wavelet chips and neurochips, in which each node is a daughter wavelet similar to a radial basis function using dyadic affine scaling.
Assessment of Adaptive Guidance for Responsive Launch Vehicles and Spacecraft
2009-04-29
Coordinate Systems 6 3.1 Earth Centered Inertial Coordinate System XIYIZI . . . . . . . . . . . . . . 6 3.2 Launch Guidance (Plumbline) System XPYPZP...Figures 1 Earth centered inertial and launch plumbline coordinate systems . . . . . . . 7 2 Geodetic and geocentric latitude...8 3 Vehicle body coordinate system showing Euler angles . . . . . . . . . . . . . 9 4 Launch vehicle body frame with
NASA Astrophysics Data System (ADS)
Abedini, Mohammad; Nojoumian, Mohammad Ali; Salarieh, Hassan; Meghdari, Ali
2015-08-01
In this paper, model reference control of a fractional order system has been discussed. In order to control the fractional order plant, discrete-time approximation methods have been applied. Plant and reference model are discretized by Grünwald-Letnikov definition of the fractional order derivative using "Short Memory Principle". Unknown parameters of the fractional order system are appeared in the discrete time approximate model as combinations of parameters of the main system. The discrete time MRAC via RLS identification is modified to estimate the parameters and control the fractional order plant. Numerical results show the effectiveness of the proposed method of model reference adaptive control.
Adaptive guidance and control for future remote sensing systems
NASA Technical Reports Server (NTRS)
Lowrie, J. W.; Myers, J. E.
1980-01-01
A unique approach to onboard processing was developed that is capable of acquiring high quality image data for users in near real time. The approach is divided into two steps: the development of an onboard cloud detection system; and the development of a landmark tracker. The results of these two developments are outlined and the requirements of an operational guidance and control system capable of providing continuous estimation of the sensor boresight position are summarized.
Experimental and simulation study results of an Adaptive Video Guidance System /AVGS/
NASA Technical Reports Server (NTRS)
Schappell, R. T.; Knickerbocker, R. L.
1975-01-01
Studies relating to stellar-body exploration programs have pointed out the need for an adaptive guidance scheme capable of providing automatic real-time guidance and site selection capability. For the case of a planetary lander, without such guidance, targeting is limited to what are believed to be generally benign areas in order to ensure a reasonable landing-success probability. Typically, the Mars Viking Lander will be jeopardized by obstacles exceeding 22 centimers in diameter. The benefits of on-board navigation and real-time selection of a landing site and obstacle avoidance have been demonstrated by the Apollo lunar landings, in which man performed the surface sensing and steering functions. Therefore, an Adaptive Video Guidance System (AVGS) has been developed, bread-boarded, and flown on a six-degree-of-freedom simulator.
An adaptive guidance law for single stage to low earth orbit
NASA Technical Reports Server (NTRS)
Pamadi, Bandu N.
1989-01-01
An adaptive guidance algorithm based on a cubic spline representation of the ascent profile and imposition of a dynamic pressure constraint is studied for a single stage to low earth orbit. The flight path is divided into initial and terminal phases. In the initial phase, fully adaptive, and in the terminal phase, semi-adaptive, guidance schemes are used. The cubic spline paqrameters are determined by gradient optimization for maximum payload to orbit. In the terminal phase, a linear quadratic regulator is used to derive the optimal feedback gains to keep the vehicle close to the nominal path. The computational aspects of the guidance algorithm are examined and criteria are developed to ensure stability and convergence.
ERIC Educational Resources Information Center
Kanar, Adam M.; Bell, Bradford S.
2013-01-01
Adaptive guidance is an instructional intervention that helps learners to make use of the control inherent in technology-based instruction. The present research investigated the interactive effects of guidance design (i.e., framing of guidance information) and individual differences (i.e., pretraining motivation and ability) on learning basic and…
Yu, Jinpeng; Shi, Peng; Yu, Haisheng; Chen, Bing; Lin, Chong
2015-07-01
This paper considers the problem of discrete-time adaptive position tracking control for a interior permanent magnet synchronous motor (IPMSM) based on fuzzy-approximation. Fuzzy logic systems are used to approximate the nonlinearities of the discrete-time IPMSM drive system which is derived by direct discretization using Euler method, and a discrete-time fuzzy position tracking controller is designed via backstepping approach. In contrast to existing results, the advantage of the scheme is that the number of the adjustable parameters is reduced to two only and the problem of coupling nonlinearity can be overcome. It is shown that the proposed discrete-time fuzzy controller can guarantee the tracking error converges to a small neighborhood of the origin and all the signals are bounded. Simulation results illustrate the effectiveness and the potentials of the theoretic results obtained.
NASA Astrophysics Data System (ADS)
Li, Shuang; Peng, Yuming
2012-01-01
In order to accurately deliver an entry vehicle through the Martian atmosphere to the prescribed parachute deployment point, active Mars entry guidance is essential. This paper addresses the issue of Mars atmospheric entry guidance using the command generator tracker (CGT) based direct model reference adaptive control to reduce the adverse effect of the bounded uncertainties on atmospheric density and aerodynamic coefficients. Firstly, the nominal drag acceleration profile meeting a variety of constraints is planned off-line in the longitudinal plane as the reference model to track. Then, the CGT based direct model reference adaptive controller and the feed-forward compensator are designed to robustly track the aforementioned reference drag acceleration profile and to effectively reduce the downrange error. Afterwards, the heading alignment logic is adopted in the lateral plane to reduce the crossrange error. Finally, the validity of the guidance algorithm proposed in this paper is confirmed by Monte Carlo simulation analysis.
NASA Technical Reports Server (NTRS)
Grantham, Katie
2003-01-01
Reusable Launch Vehicles (RLVs) have different mission requirements than the Space Shuttle, which is used for benchmark guidance design. Therefore, alternative Terminal Area Energy Management (TAEM) and Approach and Landing (A/L) Guidance schemes can be examined in the interest of cost reduction. A neural network based solution for a finite horizon trajectory optimization problem is presented in this paper. In this approach the optimal trajectory of the vehicle is produced by adaptive critic based neural networks, which were trained off-line to maintain a gradual glideslope.
Discrete-time adaptive backstepping nonlinear control via high-order neural networks.
Alanis, Alma Y; Sanchez, Edgar N; Loukianov, Alexander G
2007-07-01
This paper deals with adaptive tracking for discrete-time multiple-input-multiple-output (MIMO) nonlinear systems in presence of bounded disturbances. In this paper, a high-order neural network (HONN) structure is used to approximate a control law designed by the backstepping technique, applied to a block strict feedback form (BSFF). This paper also includes the respective stability analysis, on the basis of the Lyapunov approach, for the whole controlled system, including the extended Kalman filter (EKF)-based NN learning algorithm. Applicability of the scheme is illustrated via simulation for a discrete-time nonlinear model of an electric induction motor.
Guidance and adaptive-robust attitude & orbit control of a small information satellite
NASA Astrophysics Data System (ADS)
Somov, Ye.; Butyrin, S.; Somov, S.; Somova, T.; Testoyedov, N.; Rayevsky, V.; Titov, G.; Yakimov, Ye.; Ovchinnikov, A.; Mathylenko, M.
2017-01-01
We consider a small information satellite which may be placed on an orbit with altitude from 600 up to 1000 km. The satellite attitude and orbit control system contains a strap-down inertial navigation system, cluster of four reaction wheels, magnetic driver and a correcting engine unit with eight electro-reaction engines. We study problems on design of algorithms for spatial guidance, in-flight identification and adaptive-robust control of the satellite motion on sun-synchronous orbit.
Ren, Shenghan; Hu, Haihong; Li, Gen; Cao, Xu; Zhu, Shouping; Chen, Xueli; Liang, Jimin
2016-01-01
Bioluminescence tomography (BLT) has been a valuable optical molecular imaging technique to non-invasively depict the cellular and molecular processes in living animals with high sensitivity and specificity. Due to the inherent ill-posedness of BLT, a priori information of anatomical structure is usually incorporated into the reconstruction. The structural information is usually provided by computed tomography (CT) or magnetic resonance imaging (MRI). In order to obtain better quantitative results, BLT reconstruction with heterogeneous tissues needs to segment the internal organs and discretize them into meshes with the finite element method (FEM). It is time-consuming and difficult to handle the segmentation and discretization problems. In this paper, we present a fast reconstruction method for BLT based on multi-atlas registration and adaptive voxel discretization to relieve the complicated data processing procedure involved in the hybrid BLT/CT system. A multi-atlas registration method is first adopted to estimate the internal organ distribution of the imaged animal. Then, the animal volume is adaptively discretized into hexahedral voxels, which are fed into FEM for the following BLT reconstruction. The proposed method is validated in both numerical simulation and an in vivo study. The results demonstrate that the proposed method can reconstruct the bioluminescence source efficiently with satisfactory accuracy. PMID:27446674
Chen, Ying-ping; Chen, Chao-Hong
2010-01-01
An adaptive discretization method, called split-on-demand (SoD), enables estimation of distribution algorithms (EDAs) for discrete variables to solve continuous optimization problems. SoD randomly splits a continuous interval if the number of search points within the interval exceeds a threshold, which is decreased at every iteration. After the split operation, the nonempty intervals are assigned integer codes, and the search points are discretized accordingly. As an example of using SoD with EDAs, the integration of SoD and the extended compact genetic algorithm (ECGA) is presented and numerically examined. In this integration, we adopt a local search mechanism as an optional component of our back end optimization engine. As a result, the proposed framework can be considered as a memetic algorithm, and SoD can potentially be applied to other memetic algorithms. The numerical experiments consist of two parts: (1) a set of benchmark functions on which ECGA with SoD and ECGA with two well-known discretization methods: the fixed-height histogram (FHH) and the fixed-width histogram (FWH) are compared; (2) a real-world application, the economic dispatch problem, on which ECGA with SoD is compared to other methods. The experimental results indicate that SoD is a better discretization method to work with ECGA. Moreover, ECGA with SoD works quite well on the economic dispatch problem and delivers solutions better than the best known results obtained by other methods in existence.
Ray, Jaideep; Lefantzi, Sophia; Najm, Habib N.; Kennedy, Christopher A.
2006-01-01
Block-structured adaptively refined meshes (SAMR) strive for efficient resolution of partial differential equations (PDEs) solved on large computational domains by clustering mesh points only where required by large gradients. Previous work has indicated that fourth-order convergence can be achieved on such meshes by using a suitable combination of high-order discretizations, interpolations, and filters and can deliver significant computational savings over conventional second-order methods at engineering error tolerances. In this paper, we explore the interactions between the errors introduced by discretizations, interpolations and filters. We develop general expressions for high-order discretizations, interpolations, and filters, in multiple dimensions, using a Fourier approach, facilitating the high-order SAMR implementation. We derive a formulation for the necessary interpolation order for given discretization and derivative orders. We also illustrate this order relationship empirically using one and two-dimensional model problems on refined meshes. We study the observed increase in accuracy with increasing interpolation order. We also examine the empirically observed order of convergence, as the effective resolution of the mesh is increased by successively adding levels of refinement, with different orders of discretization, interpolation, or filtering.
Charging Guidance of Electric Taxis Based on Adaptive Particle Swarm Optimization.
Niu, Liyong; Zhang, Di
2015-01-01
Electric taxis are playing an important role in the application of electric vehicles. The actual operational data of electric taxis in Shenzhen, China, is analyzed, and, in allusion to the unbalanced time availability of the charging station equipment, the electric taxis charging guidance system is proposed basing on the charging station information and vehicle information. An electric taxis charging guidance model is established and guides the charging based on the positions of taxis and charging stations with adaptive mutation particle swarm optimization. The simulation is based on the actual data of Shenzhen charging stations, and the results show that electric taxis can be evenly distributed to the appropriate charging stations according to the charging pile numbers in charging stations after the charging guidance. The even distribution among the charging stations in the area will be achieved and the utilization of charging equipment will be improved, so the proposed charging guidance method is verified to be feasible. The improved utilization of charging equipment can save public charging infrastructure resources greatly.
Nonlinear Adaptive Control and Guidance for Unstart Recovery for a Generic Hypersonic Vehicle
NASA Astrophysics Data System (ADS)
Gunbatar, Yakup
This work presents the development of an integrated flight controller for a generic model of a hypersonic air-breathing vehicle. The flight control architecture comprises a guidance and trajectory planning module and a nonlinear inner-loop adaptive controller. The emphasis of the controller design is on achieving stable tracking of suitable reference trajectories in the presence of a specific engine fault (inlet unstart), in which sudden and drastic changes in the vehicle aerodynamics and engine performance occur. First, the equations of motion of the vehicle for a rigid body model, taking the rotation of the Earth into account, is provided. Aerodynamic forces and moments and engine data are provided in lookup-table format. This comprehensive model is used for simulations and verification of the control strategies. Then, a simplified control-oriented model is developed for the purpose of control design and stability analysis. The design of the guidance and nonlinear adaptive control algorithms is first carried out on a longitudinal version of the vehicle dynamics. The design is verified in a simulation study aiming at testing the robustness of the inner-loop controller under significant model uncertainty and engine failures. At the same time, the guidance system provides reference trajectories to maximize the vehicle's endurance, which is cast as an optimal control problem. The design is then extended to tackle the significantly more challenging case of the 6-degree-of-freedom (6-DOF) vehicle dynamics. For the full 6-DOF case, the adaptive nonlinear flight controller is tested on more challenging maneuvers, where values of the flight path and bank angles exceed the nominal range defined for the vehicle. Simulation studies show stable operation of the closed-loop system in nominal operating conditions, unstart conditions, and during transition from sustained scramjet propulsion to engine failure mode.
Savage, L.S.; Capito, B.P.
1995-12-31
The Administrative Record (AR) is a CERCLA-mandated collection of material that documents the selection of a remedial response at National Priority List (NPL) sites. It is a massive file that is established to serve legal as well as community relations functions. The US Environmental Protection Agency (USEPA) has promulgated guidance for those who are required to establish and maintain ARs; however, this guidance was developed for single-site, USEPA cleanups (i.e., industrial NPL sites). Department of Defense (DoD) facilities are tested on the NPL by installation; a single installation usually encompasses multiple sites, sometimes 25 or more. The USEPA Administrative Record guidance must be adapted before being applied to DoD installations. This paper will present the AR approach developed by the US Navy, Atlantic Division, Naval Facilities Engineering Command (LANTDIV) through its contractor Baker Environmental (Baker). The AR project was conducted as part of the Comprehensive Long-term Environmental Action Navy (CLEAN) contract. The CLEAN program is designed to address environmental problems resulting from past, formerly accepted waste management practices.
ERIC Educational Resources Information Center
Rolleri, Lori A.; Fuller, Taleria R.; Firpo-Triplett, Regina; Lesesne, Catherine A.; Moore, Claire; Leeks, Kimberly D.
2014-01-01
Evidence-based interventions (EBIs) are effective in preventing adolescent pregnancy and sexually transmitted infections; however, prevention practitioners are challenged when selecting and adapting the most appropriate programs. While there are existing adaptation frameworks, there is little practical guidance in applying research in the field.…
Optical image compression based on adaptive directional prediction discrete wavelet transform
NASA Astrophysics Data System (ADS)
Zhang, Libao; Qiu, Bingchang
2013-11-01
The traditional lifting wavelet transform cannot effectively reconstruct the nonhorizontal and nonvertical high-frequency information of an image. In this paper, we present a new image compression method based on adaptive directional prediction discrete wavelet transform (ADP-DWT). We first design a directional prediction model to obtain the optimal transform direction of the lifting wavelet. Then, we execute the directional lifting transform along the optimal transform direction. The edge and texture energy can be reduced in the nonhorizontal and nonvertical directions of the high-frequency sub-bands. Finally, the wavelet coefficients are coded with the set partitioning in hierarchical trees (SPIHT) algorithm. The new method holds the advantages of both adaptive directional lifting (ADL) and direction-adaptive discrete wavelet transform (DA-DWT), and the computational complexity is far lower than that in these methods. For the images containing regular and fine textures or edges, the coding preformance of ADP-DWT is better than that of ADL and DA-DWT.
Discrete-time entropy formulation of optimal and adaptive control problems
NASA Technical Reports Server (NTRS)
Tsai, Yweting A.; Casiello, Francisco A.; Loparo, Kenneth A.
1992-01-01
The discrete-time version of the entropy formulation of optimal control of problems developed by G. N. Saridis (1988) is discussed. Given a dynamical system, the uncertainty in the selection of the control is characterized by the probability distribution (density) function which maximizes the total entropy. The equivalence between the optimal control problem and the optimal entropy problem is established, and the total entropy is decomposed into a term associated with the certainty equivalent control law, the entropy of estimation, and the so-called equivocation of the active transmission of information from the controller to the estimator. This provides a useful framework for studying the certainty equivalent and adaptive control laws.
NASA Technical Reports Server (NTRS)
Spratlin, Kenneth Milton
1987-01-01
An adaptive numeric predictor-corrector guidance is developed for atmospheric entry vehicles which utilize lift to achieve maximum footprint capability. Applicability of the guidance design to vehicles with a wide range of performance capabilities is desired so as to reduce the need for algorithm redesign with each new vehicle. Adaptability is desired to minimize mission-specific analysis and planning. The guidance algorithm motivation and design are presented. Performance is assessed for application of the algorithm to the NASA Entry Research Vehicle (ERV). The dispersions the guidance must be designed to handle are presented. The achievable operational footprint for expected worst-case dispersions is presented. The algorithm performs excellently for the expected dispersions and captures most of the achievable footprint.
Discrete event simulation as a tool in optimization of a professional complex adaptive system.
Nielsen, Anders Lassen; Hilwig, Helmer; Kissoon, Niranjan; Teelucksingh, Surujpal
2008-01-01
Similar urgent needs for improvement of health care systems exist in the developed and developing world. The culture and the organization of an emergency department in developing countries can best be described as a professional complex adaptive system, where each agent (employee) are ignorant of the behavior of the system as a whole; no one understands the entire system. Each agent's action is based on the state of the system at the moment (i.e. lack of medicine, unavailable laboratory investigation, lack of beds and lack of staff in certain functions). An important question is how one can improve the emergency service within the given constraints. The use of simulation signals is one new approach in studying issues amenable to improvement. Discrete event simulation was used to simulate part of the patient flow in an emergency department. A simple model was built using a prototyping approach. The simulation showed that a minor rotation among the nurses could reduce the mean number of visitors that had to be refereed to alternative flows within the hospital from 87 to 37 on a daily basis with a mean utilization of the staff between 95.8% (the nurses) and 87.4% (the doctors). We conclude that even faced with resource constraints and lack of accessible data discrete event simulation is a tool that can be used successfully to study the consequences of changes in very complex and self organizing professional complex adaptive systems.
Adaptive Guidance and Control Algorithms applied to the X-38 Reentry Mission
NASA Astrophysics Data System (ADS)
Graesslin, M.; Wallner, E.; Burkhardt, J.; Schoettle, U.; Well, K. H.
International Space Station's Crew Return/Rescue Vehicle (CRV) is planned to autonomously return the complete crew of 7 astronauts back to earth in case of an emergency. As prototype of such a vehicle, the X-38, is being developed and built by NASA with European participation. The X-38 is a lifting body with a hyper- sonic lift to drag ratio of about 0.9. In comparison to the Space Shuttle Orbiter, the X-38 has less aerodynamic manoeuvring capability and less actuators. Within the German technology programme TETRA (TEchnologies for future space TRAnsportation systems) contributing to the X-38 program, guidance and control algorithms have been developed and applied to the X-38 reentry mission. The adaptive guidance concept conceived combines an on-board closed-loop predictive guidance algorithm with flight load control that temporarily overrides the attitude commands of the predictive component if the corre- sponding load constraints are violated. The predictive guidance scheme combines an optimization step and a sequence of constraint restoration cycles. In order to satisfy on-board computation limitations the complete scheme is performed only during the exo-atmospheric flight coast phase. During the controlled atmospheric flight segment the task is reduced to a repeatedly solved targeting problem based on the initial optimal solution, thus omitting in-flight constraints. To keep the flight loads - especially the heat flux, which is in fact a major concern of the X-38 reentry flight - below their maximum admissible values, a flight path controller based on quadratic minimization techniques may override the predictive guidance command for a flight along the con- straint boundary. The attitude control algorithms developed are based on dynamic inversion. This methodology enables the designer to straightforwardly devise a controller structure from the system dynamics. The main ad- vantage of this approach with regard to reentry control design lies in the fact that
NASA Astrophysics Data System (ADS)
Palaniswamy, Sumithra; Duraisamy, Prakash; Alam, Mohammad Showkat; Yuan, Xiaohui
2012-04-01
Automatic speech processing systems are widely used in everyday life such as mobile communication, speech and speaker recognition, and for assisting the hearing impaired. In speech communication systems, the quality and intelligibility of speech is of utmost importance for ease and accuracy of information exchange. To obtain an intelligible speech signal and one that is more pleasant to listen, noise reduction is essential. In this paper a new Time Adaptive Discrete Bionic Wavelet Thresholding (TADBWT) scheme is proposed. The proposed technique uses Daubechies mother wavelet to achieve better enhancement of speech from additive non- stationary noises which occur in real life such as street noise and factory noise. Due to the integration of human auditory system model into the wavelet transform, bionic wavelet transform (BWT) has great potential for speech enhancement which may lead to a new path in speech processing. In the proposed technique, at first, discrete BWT is applied to noisy speech to derive TADBWT coefficients. Then the adaptive nature of the BWT is captured by introducing a time varying linear factor which updates the coefficients at each scale over time. This approach has shown better performance than the existing algorithms at lower input SNR due to modified soft level dependent thresholding on time adaptive coefficients. The objective and subjective test results confirmed the competency of the TADBWT technique. The effectiveness of the proposed technique is also evaluated for speaker recognition task under noisy environment. The recognition results show that the TADWT technique yields better performance when compared to alternate methods specifically at lower input SNR.
Policy iteration adaptive dynamic programming algorithm for discrete-time nonlinear systems.
Liu, Derong; Wei, Qinglai
2014-03-01
This paper is concerned with a new discrete-time policy iteration adaptive dynamic programming (ADP) method for solving the infinite horizon optimal control problem of nonlinear systems. The idea is to use an iterative ADP technique to obtain the iterative control law, which optimizes the iterative performance index function. The main contribution of this paper is to analyze the convergence and stability properties of policy iteration method for discrete-time nonlinear systems for the first time. It shows that the iterative performance index function is nonincreasingly convergent to the optimal solution of the Hamilton-Jacobi-Bellman equation. It is also proven that any of the iterative control laws can stabilize the nonlinear systems. Neural networks are used to approximate the performance index function and compute the optimal control law, respectively, for facilitating the implementation of the iterative ADP algorithm, where the convergence of the weight matrices is analyzed. Finally, the numerical results and analysis are presented to illustrate the performance of the developed method.
NASA Astrophysics Data System (ADS)
Owens, A. R.; Kópházi, J.; Welch, J. A.; Eaton, M. D.
2017-04-01
In this paper a hanging-node, discontinuous Galerkin, isogeometric discretisation of the multigroup, discrete ordinates (SN) equations is presented in which each energy group has its own mesh. The equations are discretised using Non-Uniform Rational B-Splines (NURBS), which allows the coarsest mesh to exactly represent the geometry for a wide range of engineering problems of interest; this would not be the case using straight-sided finite elements. Information is transferred between meshes via the construction of a supermesh. This is a non-trivial task for two arbitrary meshes, but is significantly simplified here by deriving every mesh from a common coarsest initial mesh. In order to take full advantage of this flexible discretisation, goal-based error estimators are derived for the multigroup, discrete ordinates equations with both fixed (extraneous) and fission sources, and these estimators are used to drive an adaptive mesh refinement (AMR) procedure. The method is applied to a variety of test cases for both fixed and fission source problems. The error estimators are found to be extremely accurate for linear NURBS discretisations, with degraded performance for quadratic discretisations owing to a reduction in relative accuracy of the ;exact; adjoint solution required to calculate the estimators. Nevertheless, the method seems to produce optimal meshes in the AMR process for both linear and quadratic discretisations, and is ≈×100 more accurate than uniform refinement for the same amount of computational effort for a 67 group deep penetration shielding problem.
NASA Technical Reports Server (NTRS)
Malin, Jane T.; Basham, Bryan D.
1989-01-01
CONFIG is a modeling and simulation tool prototype for analyzing the normal and faulty qualitative behaviors of engineered systems. Qualitative modeling and discrete-event simulation have been adapted and integrated, to support early development, during system design, of software and procedures for management of failures, especially in diagnostic expert systems. Qualitative component models are defined in terms of normal and faulty modes and processes, which are defined by invocation statements and effect statements with time delays. System models are constructed graphically by using instances of components and relations from object-oriented hierarchical model libraries. Extension and reuse of CONFIG models and analysis capabilities in hybrid rule- and model-based expert fault-management support systems are discussed.
Shape-adaptive discrete wavelet transform for coding arbitrarily shaped texture
NASA Astrophysics Data System (ADS)
Li, Shipeng; Li, Weiping
1997-01-01
This paper presents a shape adaptive discrete wavelet transform (SA-DWT) scheme for coding arbitrarily shaped texture. The proposed SA-DWT can be used for object-oriented image coding. The number of coefficients after SA-DWT is identical to the number of pels contained in the arbitrarily shaped image objects. The locality property of wavelet transform and self-similarity among subbands are well preserved throughout this process.For a rectangular region, the SA-DWT is identical to a standard wavelet transform. With SA-DWT, conventional wavelet based coding schemes can be readily extended to the coding of arbitrarily shaped objects. The proposed shape adaptive wavelet transform is not unitary but the small energy increase is restricted at the boundary of objects in subbands. Two approaches of using the SA-DWT algorithm for object-oriented image and video coding are presented. One is to combine scalar SA-DWT with embedded zerotree wavelet (EZW) coding technique, the other is an extension of the normal vector wavelet coding (VWC) technique to arbitrarily shaped objects. Results of applying SA-VWC to real arbitrarily shaped texture coding are also given at the end of this paper.
varying airframe dynamics. Guidance techniques for tactical missiles are also reviewed and a number of steering laws, derived from optimal control ... theory , are evaluated. Quantitative comparisons are made between different guidance laws on the basis of intercept accuracy and control effort expended.
NASA Technical Reports Server (NTRS)
Blissit, J. A.
1986-01-01
Using analysis results from the post trajectory optimization program, an adaptive guidance algorithm is developed to compensate for density, aerodynamic and thrust perturbations during an atmospheric orbital plane change maneuver. The maneuver offers increased mission flexibility along with potential fuel savings for future reentry vehicles. Although designed to guide a proposed NASA Entry Research Vehicle, the algorithm is sufficiently generic for a range of future entry vehicles. The plane change analysis provides insight suggesting a straight-forward algorithm based on an optimized nominal command profile. Bank angle, angle of attack, and engine thrust level, ignition and cutoff times are modulated to adjust the vehicle's trajectory to achieve the desired end-conditions. A performance evaluation of the scheme demonstrates a capability to guide to within 0.05 degrees of the desired plane change and five nautical miles of the desired apogee altitude while maintaining heating constraints. The algorithm is tested under off-nominal conditions of + or -30% density biases, two density profile models, + or -15% aerodynamic uncertainty, and a 33% thrust loss and for various combinations of these conditions.
Value Iteration Adaptive Dynamic Programming for Optimal Control of Discrete-Time Nonlinear Systems.
Wei, Qinglai; Liu, Derong; Lin, Hanquan
2016-03-01
In this paper, a value iteration adaptive dynamic programming (ADP) algorithm is developed to solve infinite horizon undiscounted optimal control problems for discrete-time nonlinear systems. The present value iteration ADP algorithm permits an arbitrary positive semi-definite function to initialize the algorithm. A novel convergence analysis is developed to guarantee that the iterative value function converges to the optimal performance index function. Initialized by different initial functions, it is proven that the iterative value function will be monotonically nonincreasing, monotonically nondecreasing, or nonmonotonic and will converge to the optimum. In this paper, for the first time, the admissibility properties of the iterative control laws are developed for value iteration algorithms. It is emphasized that new termination criteria are established to guarantee the effectiveness of the iterative control laws. Neural networks are used to approximate the iterative value function and compute the iterative control law, respectively, for facilitating the implementation of the iterative ADP algorithm. Finally, two simulation examples are given to illustrate the performance of the present method.
Camley, Brian A.; Zimmermann, Juliane; Levine, Herbert; Rappel, Wouter-Jan
2016-01-01
Single eukaryotic cells commonly sense and follow chemical gradients, performing chemotaxis. Recent experiments and theories, however, show that even when single cells do not chemotax, clusters of cells may, if their interactions are regulated by the chemoattractant. We study this general mechanism of “collective guidance” computationally with models that integrate stochastic dynamics for individual cells with biochemical reactions within the cells, and diffusion of chemical signals between the cells. We show that if clusters of cells use the well-known local excitation, global inhibition (LEGI) mechanism to sense chemoattractant gradients, the speed of the cell cluster becomes non-monotonic in the cluster’s size—clusters either larger or smaller than an optimal size will have lower speed. We argue that the cell cluster speed is a crucial readout of how the cluster processes chemotactic signals; both amplification and adaptation will alter the behavior of cluster speed as a function of size. We also show that, contrary to the assumptions of earlier theories, collective guidance does not require persistent cell-cell contacts and strong short range adhesion. If cell-cell adhesion is absent, and the cluster cohesion is instead provided by a co-attraction mechanism, e.g. chemotaxis toward a secreted molecule, collective guidance may still function. However, new behaviors, such as cluster rotation, may also appear in this case. Co-attraction and adaptation allow for collective guidance that is robust to varying chemoattractant concentrations while not requiring strong cell-cell adhesion. PMID:27367541
NASA Astrophysics Data System (ADS)
Gehb, Christopher M.; Platz, Roland; Melz, Tobias
2015-04-01
In many applications, kinematic structures are used to enable and disable degrees of freedom. The relative movement between a wheel and the body of a car or a landing gear and an aircraft fuselage are examples for a defined movement. In most cases, a spring-damper system determines the kinetic properties of the movement. However, unexpected high load peaks may lead to maximum displacements and maybe to locking. Thus, a hard clash between two rigid components may occur, causing acceleration peaks. This may have harmful effects for the whole system. For example a hard landing of an aircraft can result in locking the landing gear and thus damage the entire aircraft. In this paper, the potential of adaptive auxiliary kinematic guidance elements in a spring-damper system to prevent locking is investigated numerically. The aim is to provide additional forces in the auxiliary kinematic guidance elements in case of overloading the spring-damper system and thus to absorb some of the impact energy. To estimate the potential of the load redistribution in the spring-damper system, a numerical model of a two-mass oscillator is used, similar to a quarter-car-model. In numerical calculations, the reduction of the acceleration peaks of the masses with the adaptive approach is compared to the Acceleration peaks without the approach, or, respectively, when locking is not prevented. In addition, the required force of the adaptive auxiliary kinematic guidance elements is calculated as a function of the masses of the system and the drop height, or, respectively, the impact energy.
Füssel, Hans-Martin
2008-02-01
Climate change adaptation assessments aim at assisting policy-makers in reducing the health risks associated with climate change and variability. This paper identifies key characteristics of the climate-health relationship and of the adaptation decision problem that require consideration in climate change adaptation assessments. It then analyzes whether these characteristics are appropriately considered in existing guidelines for climate impact and adaptation assessment and in pertinent conceptual models from environmental epidemiology. The review finds three assessment guidelines based on a generalized risk management framework to be most useful for guiding adaptation assessments of human health. Since none of them adequately addresses all key challenges of the adaptation decision problem, actual adaptation assessments need to combine elements from different guidelines. Established conceptual models from environmental epidemiology are found to be of limited relevance for assessing and planning adaptation to climate change since the prevailing toxicological model of environmental health is not applicable to many climate-sensitive health risks.
NASA Astrophysics Data System (ADS)
Lang, Jun; Hao, Zhengchao
2014-01-01
In this paper, we first propose the discrete multi-parameter fractional random transform (DMPFRNT), which can make the spectrum distributed randomly and uniformly. Then we introduce this new spectrum transform into the image fusion field and present a new approach for the remote sensing image fusion, which utilizes both adaptive pulse coupled neural network (PCNN) and the discrete multi-parameter fractional random transform in order to meet the requirements of both high spatial resolution and low spectral distortion. In the proposed scheme, the multi-spectral (MS) and panchromatic (Pan) images are converted into the discrete multi-parameter fractional random transform domains, respectively. In DMPFRNT spectrum domain, high amplitude spectrum (HAS) and low amplitude spectrum (LAS) components carry different informations of original images. We take full advantage of the synchronization pulse issuance characteristics of PCNN to extract the HAS and LAS components properly, and give us the PCNN ignition mapping images which can be used to determine the fusion parameters. In the fusion process, local standard deviation of the amplitude spectrum is chosen as the link strength of pulse coupled neural network. Numerical simulations are performed to demonstrate that the proposed method is more reliable and superior than several existing methods based on Hue Saturation Intensity representation, Principal Component Analysis, the discrete fractional random transform etc.
Adaptive critic designs for discrete-time zero-sum games with application to H(infinity) control.
Al-Tamimi, Asma; Abu-Khalaf, Murad; Lewis, Frank L
2007-02-01
In this correspondence, adaptive critic approximate dynamic programming designs are derived to solve the discrete-time zero-sum game in which the state and action spaces are continuous. This results in a forward-in-time reinforcement learning algorithm that converges to the Nash equilibrium of the corresponding zero-sum game. The results in this correspondence can be thought of as a way to solve the Riccati equation of the well-known discrete-time H(infinity) optimal control problem forward in time. Two schemes are presented, namely: 1) a heuristic dynamic programming and 2) a dual-heuristic dynamic programming, to solve for the value function and the costate of the game, respectively. An H(infinity) autopilot design for an F-16 aircraft is presented to illustrate the results.
NASA Astrophysics Data System (ADS)
Sun, Zhiyong; Hao, Lina; Chen, Wenlin; Li, Zhi; Liu, Liqun
2013-09-01
Ionic polymer-metal composite (IPMC), also called artificial muscle, is an EAP material which can generate a relatively large deformation with a low driving voltage (generally less than 5 V). Like other EAP materials, IPMC possesses strong nonlinear properties, which can be described as a hybrid of back-relaxation (BR) and hysteresis characteristics, which also vary with water content, environmental temperature and even the usage consumption. Nowadays, many control approaches have been developed to tune the IPMC actuators, among which adaptive methods show a particular striking performance. To deal with IPMCs’ nonlinear problem, this paper represents a robust discrete adaptive inverse (AI) control approach, which employs an on-line identification technique based on the BR operator and Prandtl-Ishlinskii (PI) hysteresis operator hybrid model estimation method. Here the newly formed control approach is called discrete adaptive sliding-mode-like control (DASMLC) due to the similarity of its design method to that of a sliding mode controller. The weighted least mean squares (WLMS) identification method was employed to estimate the hybrid IPMC model because of its advantage of insensitivity to environmental noise. Experiments with the DASMLC approach and a conventional PID controller were carried out to compare and demonstrate the proposed controller’s better performance.
Biological Inspired Direct Adaptive Guidance and Control for Autonomous Flight Systems
2007-11-02
and ultimately to map the location of the target on the eye during the pursuit. The results provided a means to compare the guidance strategy of the...two project areas. 1) We have made optical measurements of the compound eye to determine the distribution of visual acuity across the sensor array. 2...enable more precise angular measurements of the position of the head, which bears the immobile eyes , relative to the thorax (Fig. B. 1). Fi. We
Numerous strategies but limited implementation guidance in US local adaptation plans
NASA Astrophysics Data System (ADS)
Woodruff, Sierra C.; Stults, Missy
2016-08-01
Adaptation planning offers a promising approach for identifying and devising solutions to address local climate change impacts. Yet there is little empirical understanding of the content and quality of these plans. We use content analysis to evaluate 44 local adaptation plans in the United States and multivariate regression to examine how plan quality varies across communities. We find that plans draw on multiple data sources to analyse future climate impacts and include a breadth of strategies. Most plans, however, fail to prioritize impacts and strategies or provide detailed implementation processes, raising concerns about whether adaptation plans will translate into on-the-ground reductions in vulnerability. Our analysis also finds that plans authored by the planning department and those that engaged elected officials in the planning process were of higher quality. The results provide important insights for practitioners, policymakers and scientists wanting to improve local climate adaptation planning and action.
NASA Astrophysics Data System (ADS)
Yoshimura, Toshio
2016-02-01
This paper presents the design of an adaptive fuzzy sliding mode control (AFSMC) for uncertain discrete-time nonlinear dynamic systems. The dynamic systems are described by a discrete-time state equation with nonlinear uncertainties, and the uncertainties include the modelling errors and the external disturbances to be unknown but nonlinear with the bounded properties. The states are measured by the restriction of measurement sensors and the contamination with independent measurement noises. The nonlinear uncertainties are approximated by using the fuzzy IF-THEN rules based on the universal approximation theorem, and the approximation error is compensated by adding an adaptive complementary term to the proposed AFSMC. The fuzzy inference approach based on the extended single input rule modules is proposed to reduce the number of the fuzzy IF-THEN rules. The estimates for the un-measurable states and the adjustable parameters are obtained by using the weighted least squares estimator and its simplified one. It is proved that under some conditions the estimation errors will remain in the vicinity of zero as time increases, and the states are ultimately bounded subject to the proposed AFSMC. The effectiveness of the proposed method is indicated through the simulation experiment of a simple numerical system.
Adaptive stabilization of discrete-time systems using linear periodically time varying controllers
NASA Technical Reports Server (NTRS)
Ortega, Romeo; Albertos, Pedro; Lozano, Rogelio
1988-01-01
A direct adaptive scheme based on the use of linear time-varying periodic controllers is proposed which estimates online the periodic coefficients of the controller. It is shown that adaptive stabilization is attained for all possibly nonstably invertible plants of known order but unknown delay. Although no appeal is made to persistency of excitation arguments, a provision is needed to avoid the singularity of an estimated matrix, this property being required only for the analysis and not the control calculations.
Qin, An; Sun, Ying; Liang, Jian; Yan, Di
2015-04-01
Purpose: To evaluate online/offline image-guided/adaptive treatment techniques for prostate cancer radiation therapy with daily cone-beam CT (CBCT) imaging. Methods and Materials: Three treatment techniques were evaluated retrospectively using daily pre- and posttreatment CBCT images on 22 prostate cancer patients. Prostate, seminal vesicles (SV), rectal wall, and bladder were delineated on all CBCT images. For each patient, a pretreatment intensity modulated radiation therapy plan with clinical target volume (CTV) = prostate + SV and planning target volume (PTV) = CTV + 3 mm was created. The 3 treatment techniques were as follows: (1) Daily Correction: The pretreatment intensity modulated radiation therapy plan was delivered after online CBCT imaging, and position correction; (2) Online Planning: Daily online inverse plans with 3-mm CTV-to-PTV margin were created using online CBCT images, and delivered; and (3) Hybrid Adaption: Daily Correction plus an offline adaptive inverse planning performed after the first week of treatment. The adaptive plan was delivered for all remaining 15 fractions. Treatment dose for each technique was constructed using the daily posttreatment CBCT images via deformable image registration. Evaluation was performed using treatment dose distribution in target and critical organs. Results: Treatment equivalent uniform dose (EUD) for the CTV was within [85.6%, 100.8%] of the pretreatment planned target EUD for Daily Correction; [98.7%, 103.0%] for Online Planning; and [99.2%, 103.4%] for Hybrid Adaptation. Eighteen percent of the 22 patients in Daily Correction had a target dose deficiency >5%. For rectal wall, the mean ± SD of the normalized EUD was 102.6% ± 2.7% for Daily Correction, 99.9% ± 2.5% for Online Planning, and 100.6% ± 2.1% for Hybrid Adaptation. The mean ± SD of the normalized bladder EUD was 108.7% ± 8.2% for Daily Correction, 92.7% ± 8.6% for Online Planning, and 89.4% ± 10.8% for Hybrid
Controlling Discrete Time T-S Fuzzy Chaotic Systems via Adaptive Adjustment
NASA Astrophysics Data System (ADS)
Nian, Yibei; Zheng, Yongai
In order to overcome typical drawbacks of the OGY control, i.e. the long waiting time for control to be applied and the accessible turning system parameter in advance, this paper presents a new chaos control method based on Takagi- Sugeno (T-S) fuzzy model and adaptive adjustment. This method represents a chaotic system by linear models in different state space regions based on T-S fuzzy model and then stabilize the linear models in different state space regions by the adaptive adjustment mechanism. An example for the Henon map is given to demonstrate the effectiveness of the proposed method.
Balter, Max L; Chen, Alvin I; Maguire, Timothy J; Yarmush, Martin L
2017-02-01
Robotic systems have slowly entered the realm of modern medicine; however, outside the operating room, medical robotics has yet to be translated to more routine interventions such as blood sampling or intravenous fluid delivery. In this paper, we present a medical robot that safely and rapidly cannulates peripheral blood vessels-a procedure commonly known as venipuncture. The device uses near-infrared and ultrasound imaging to scan and select suitable injection sites, and a 9-DOF robot to insert the needle into the center of the vessel based on image and force guidance. We first present the system design and visual servoing scheme of the latest generation robot, and then evaluate the performance of the device through workspace simulations and free-space positioning tests. Finally, we perform a series of motion tracking experiments using stereo vision, ultrasound, and force sensing to guide the position and orientation of the needle tip. Positioning experiments indicate sub-millimeter accuracy and repeatability over the operating workspace of the system, while tracking studies demonstrate real-time needle servoing in response to moving targets. Lastly, robotic phantom cannulations demonstrate the use of multiple system states to confirm that the needle has reached the center of the vessel.
Goal-based h-adaptivity of the 1-D diamond difference discrete ordinate method
NASA Astrophysics Data System (ADS)
Jeffers, R. S.; Kópházi, J.; Eaton, M. D.; Févotte, F.; Hülsemann, F.; Ragusa, J.
2017-04-01
The quantity of interest (QoI) associated with a solution of a partial differential equation (PDE) is not, in general, the solution itself, but a functional of the solution. Dual weighted residual (DWR) error estimators are one way of providing an estimate of the error in the QoI resulting from the discretisation of the PDE. This paper aims to provide an estimate of the error in the QoI due to the spatial discretisation, where the discretisation scheme being used is the diamond difference (DD) method in space and discrete ordinate (SN) method in angle. The QoI are reaction rates in detectors and the value of the eigenvalue (Keff) for 1-D fixed source and eigenvalue (Keff criticality) neutron transport problems respectively. Local values of the DWR over individual cells are used as error indicators for goal-based mesh refinement, which aims to give an optimal mesh for a given QoI.
Zhang, Huaguang; Jiang, He; Luo, Chaomin; Xiao, Geyang
2016-10-03
In this paper, we investigate the nonzero-sum games for a class of discrete-time (DT) nonlinear systems by using a novel policy iteration (PI) adaptive dynamic programming (ADP) method. The main idea of our proposed PI scheme is to utilize the iterative ADP algorithm to obtain the iterative control policies, which not only ensure the system to achieve stability but also minimize the performance index function for each player. This paper integrates game theory, optimal control theory, and reinforcement learning technique to formulate and handle the DT nonzero-sum games for multiplayer. First, we design three actor-critic algorithms, an offline one and two online ones, for the PI scheme. Subsequently, neural networks are employed to implement these algorithms and the corresponding stability analysis is also provided via the Lyapunov theory. Finally, a numerical simulation example is presented to demonstrate the effectiveness of our proposed approach.
ERIC Educational Resources Information Center
Belanger, Charles H., Ed.
Changes in higher education that affect teaching and research are addressed in the proceedings of the 1982 forum of the European Association for Institutional Research. In addition to six invited papers on adaptation or guidance of universities, papers on faculty, resources and cost indicators, research facilities and equipment, and institutional…
ERIC Educational Resources Information Center
Lieberman, Lauren; Lucas, Mark; Jones, Jeffery; Humphreys, Dan; Cody, Ann; Vaughn, Bev; Storms, Tommie
2013-01-01
"Helping General Physical Educators and Adapted Physical Educators Address the Office of Civil Rights Dear Colleague Guidance Letter: Part IV--Sport Groups" provides the the following articles: (1) "Sport Programming Offered by Camp Abilities and the United States Association for Blind Athletes" (Lauren Lieberman and Mark…
Rezaee, Kh.; Haddadnia, J.
2013-01-01
Background: Breast cancer is currently one of the leading causes of death among women worldwide. The diagnosis and separation of cancerous tumors in mammographic images require accuracy, experience and time, and it has always posed itself as a major challenge to the radiologists and physicians. Objective: This paper proposes a new algorithm which draws on discrete wavelet transform and adaptive K-means techniques to transmute the medical images implement the tumor estimation and detect breast cancer tumors in mammograms in early stages. It also allows the rapid processing of the input data. Method: In the first step, after designing a filter, the discrete wavelet transform is applied to the input images and the approximate coefficients of scaling components are constructed. Then, the different parts of image are classified in continuous spectrum. In the next step, by using adaptive K-means algorithm for initializing and smart choice of clusters’ number, the appropriate threshold is selected. Finally, the suspicious cancerous mass is separated by implementing the image processing techniques. Results: We Received 120 mammographic images in LJPEG format, which had been scanned in Gray-Scale with 50 microns size, 3% noise and 20% INU from clinical data taken from two medical databases (mini-MIAS and DDSM). The proposed algorithm detected tumors at an acceptable level with an average accuracy of 92.32% and sensitivity of 90.24%. Also, the Kappa coefficient was approximately 0.85, which proved the suitable reliability of the system performance. Conclusion: The exact positioning of the cancerous tumors allows the radiologist to determine the stage of disease progression and suggest an appropriate treatment in accordance with the tumor growth. The low PPV and high NPV of the system is a warranty of the system and both clinical specialists and patients can trust its output. PMID:25505753
NASA Technical Reports Server (NTRS)
Tolmadzheva, T. A.; Kantor, A. V.; Rozhkovskiy, L. V.
1974-01-01
Digital computer modeling of the process of adaptive discretization with associative sorting of actual multichannel telemetry information is discussed. The main task in modeling is production of initial data for determination of dependences describing the operation of the on-board information compression device. Conclusions are presented including the shortcomings of telemetric information used in modeling.
Ge, Shuzhi Sam; Yang, Chenguang; Lee, Tong Heng
2008-09-01
In this paper, adaptive neural network (NN) control is investigated for a class of nonlinear pure-feedback discrete-time systems. By using prediction functions of future states, the pure-feedback system is transformed into an n-step-ahead predictor, based on which state feedback NN control is synthesized. Next, by investigating the relationship between outputs and states, the system is transformed into an input-output predictor model, and then, output feedback control is constructed. To overcome the difficulty of nonaffine appearance of the control input, implicit function theorem is exploited in the control design and NN is employed to approximate the unknown function in the control. In both state feedback and output feedback control, only a single NN is used and the controller singularity is completely avoided. The closed-loop system achieves semiglobal uniform ultimate boundedness (SGUUB) stability and the output tracking error is made within a neighborhood around zero. Simulation results are presented to show the effectiveness of the proposed control approach.
Shih, Cheng-Ting; Lin, Hsin-Hon; Chuang, Keh-Shih; Wu, Jay; Chang, Shu-Jun
2014-08-15
Purpose: Several positron emission tomography (PET) scanners with special detector block arrangements have been developed in recent years to improve the resolution of PET images. However, the discontinuous detector blocks cause gaps in the sinogram. This study proposes an adaptive discrete cosine transform-based (aDCT) filter for gap-inpainting. Methods: The gap-corrupted sinogram was morphologically closed and subsequently converted to the DCT domain. A certain number of the largest coefficients in the DCT spectrum were identified to determine the low-frequency preservation region. The weighting factors for the remaining coefficients were determined by an exponential weighting function. The aDCT filter was constructed and applied to two digital phantoms and a simulated phantom introduced with various levels of noise. Results: For the Shepp-Logan head phantom, the aDCT filter filled the gaps effectively. For the Jaszczak phantom, no secondary artifacts were induced after aDCT filtering. The percent mean square error and mean structure similarity of the aDCT filter were superior to those of the DCT2 filter at all noise levels. For the simulated striatal dopamine innervation study, the aDCT filter recovered the shape of the striatum and restored the striatum to reference activity ratios to the ideal value. Conclusions: The proposed aDCT filter can recover the missing gap data in the sinogram and improve the image quality and quantitative accuracy of PET images.
Liu, Yan-Jun; Tong, Shaocheng
2016-11-01
In this paper, we propose an optimal control scheme-based adaptive neural network design for a class of unknown nonlinear discrete-time systems. The controlled systems are in a block-triangular multi-input-multi-output pure-feedback structure, i.e., there are both state and input couplings and nonaffine functions to be included in every equation of each subsystem. The design objective is to provide a control scheme, which not only guarantees the stability of the systems, but also achieves optimal control performance. The main contribution of this paper is that it is for the first time to achieve the optimal performance for such a class of systems. Owing to the interactions among subsystems, making an optimal control signal is a difficult task. The design ideas are that: 1) the systems are transformed into an output predictor form; 2) for the output predictor, the ideal control signal and the strategic utility function can be approximated by using an action network and a critic network, respectively; and 3) an optimal control signal is constructed with the weight update rules to be designed based on a gradient descent method. The stability of the systems can be proved based on the difference Lyapunov method. Finally, a numerical simulation is given to illustrate the performance of the proposed scheme.
Avci, Derya; Leblebicioglu, Mehmet Kemal; Poyraz, Mustafa; Dogantekin, Esin
2014-02-01
So far, analysis and classification of urine cells number has become an important topic for medical diagnosis of some diseases. Therefore, in this study, we suggest a new technique based on Adaptive Discrete Wavelet Entropy Energy and Neural Network Classifier (ADWEENN) for Recognition of Urine Cells from Microscopic Images Independent of Rotation and Scaling. Some digital image processing methods such as noise reduction, contrast enhancement, segmentation, and morphological process are used for feature extraction stage of this ADWEENN in this study. Nowadays, the image processing and pattern recognition topics have come into prominence. The image processing concludes operation and design of systems that recognize patterns in data sets. In the past years, very difficulty in classification of microscopic images was the deficiency of enough methods to characterize. Lately, it is seen that, multi-resolution image analysis methods such as Gabor filters, discrete wavelet decompositions are superior to other classic methods for analysis of these microscopic images. In this study, the structure of the ADWEENN method composes of four stages. These are preprocessing stage, feature extraction stage, classification stage and testing stage. The Discrete Wavelet Transform (DWT) and adaptive wavelet entropy and energy is used for adaptive feature extraction in feature extraction stage to strengthen the premium features of the Artificial Neural Network (ANN) classifier in this study. Efficiency of the developed ADWEENN method was tested showing that an avarage of 97.58% recognition succes was obtained.
Kertzscher, Gustavo Andersen, Claus E.; Tanderup, Kari
2014-05-15
Purpose: This study presents an adaptive error detection algorithm (AEDA) for real-timein vivo point dosimetry during high dose rate (HDR) or pulsed dose rate (PDR) brachytherapy (BT) where the error identification, in contrast to existing approaches, does not depend on an a priori reconstruction of the dosimeter position. Instead, the treatment is judged based on dose rate comparisons between measurements and calculations of the most viable dosimeter position provided by the AEDA in a data driven approach. As a result, the AEDA compensates for false error cases related to systematic effects of the dosimeter position reconstruction. Given its nearly exclusive dependence on stable dosimeter positioning, the AEDA allows for a substantially simplified and time efficient real-time in vivo BT dosimetry implementation. Methods: In the event of a measured potential treatment error, the AEDA proposes the most viable dosimeter position out of alternatives to the original reconstruction by means of a data driven matching procedure between dose rate distributions. If measured dose rates do not differ significantly from the most viable alternative, the initial error indication may be attributed to a mispositioned or misreconstructed dosimeter (false error). However, if the error declaration persists, no viable dosimeter position can be found to explain the error, hence the discrepancy is more likely to originate from a misplaced or misreconstructed source applicator or from erroneously connected source guide tubes (true error). Results: The AEDA applied on twoin vivo dosimetry implementations for pulsed dose rate BT demonstrated that the AEDA correctly described effects responsible for initial error indications. The AEDA was able to correctly identify the major part of all permutations of simulated guide tube swap errors and simulated shifts of individual needles from the original reconstruction. Unidentified errors corresponded to scenarios where the dosimeter position was
NASA Astrophysics Data System (ADS)
Mohsen Hosseini-Ardali, Seyed; Ghaderi, Adel
2015-11-01
This paper considers the output feedback adaptive controller design problem for a class of discrete-time nonlinear systems in output feedback form with unknown control directions and preceded by unknown hysteresis. The problem of lacking in a-priori knowledge on the control directions and unknown hysteresis are solved by using the discrete Nussbaum gain and Prandtl-Ishlinskii model, respectively. The system is transformed into the form of a nonlinear auto regressive moving average (NARMA) model to construct an output feedback control. To overcome the noncausal problem in the control design, future output prediction laws and parameter update laws with the dead-zone technique are constructed on the basis of the NARMA model. The proposed control algorithm guarantees that all the signals in the controlled system are bound and the output tracking error is made to be neighbourhood around zero, ultimately. Finally, simulations are performed on a nonlinear system to show the effectiveness of the proposed method
Chen, Weisheng
2009-07-01
This paper focuses on the problem of adaptive neural network tracking control for a class of discrete-time pure-feedback systems with unknown control direction under amplitude and rate actuator constraints. Two novel state-feedback and output-feedback dynamic control laws are established where the function tanh(.) is employed to solve the saturation constraint problem. Implicit function theorem and mean value theorem are exploited to deal with non-affine variables that are used as actual control. Radial basis function neural networks are used to approximate the desired input function. Discrete Nussbaum gain is used to estimate the unknown sign of control gain. The uniform boundedness of all closed-loop signals is guaranteed. The tracking error is proved to converge to a small residual set around the origin. A simulation example is provided to illustrate the effectiveness of control schemes proposed in this paper.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-02-26
..., statistical, and regulatory aspects of a wide range of adaptive design clinical studies that can be proposed... design clinical trials (i.e., clinical, statistical, regulatory) call for special consideration, when to interact with FDA while planning and conducting adaptive design studies, what information to include in...
Gilbert, K J; Whitlock, M C
2017-03-01
Range expansions are complex evolutionary and ecological processes. From an evolutionary standpoint, a populations' adaptive capacity can determine the success or failure of expansion. Using individual-based simulations, we model range expansion over a two-dimensional, approximately continuous landscape. We investigate the ability of populations to adapt across patchy environmental gradients and examine how the effect sizes of mutations influence the ability to adapt to novel environments during range expansion. We find that genetic architecture and landscape patchiness both have the ability to change the outcome of adaptation and expansion over the landscape. Adaptation to new environments succeeds via many mutations of small effect or few of large effect, but not via the intermediate between these cases. Higher genetic variance contributes to increased ability to adapt, but an alternative route of successful adaptation can proceed from low genetic variance scenarios with alleles of sufficiently large effect. Steeper environmental gradients can prevent adaptation and range expansion on both linear and patchy landscapes. When the landscape is partitioned into local patches with sharp changes in phenotypic optimum, the local magnitude of change between subsequent patches in the environment determines the success of adaptation to new patches during expansion.
NASA Astrophysics Data System (ADS)
Zhang, Lijun; Zhao, Jiemei; Qi, Xue; Jia, Heming
2013-06-01
The problem of tracking control for a class of uncertain non-affine discrete-time nonlinear systems with internal dynamics is addressed. The fixed point theorem is first employed to ensure the control problem in question is solvable and well-defined. Based on it, an adaptive output feedback control scheme based on neural network (NN) is presented. The proposed control algorithm consists of two parts: a dynamic compensator is introduced to stabilise the linear portion of the tracking error system; a single-hidden-layer neural network (SHL NN) approximation mechanism is introduced to cancel the uncertainties resulting from the non-affine function, where the recursive weight update rules of NN estimation are derived from the discrete-time version of Lyapunov control theory. Ultimate boundedness of the error signals is shown through Lyapunov's direct method and the discrete-time version of input-to-state stability (ISS) theory. Finally, a model of automatical underwater vehicle (AUV) is considered to show the effectiveness of the proposed control scheme.
ERIC Educational Resources Information Center
Redondo, Miguel A.; Bravo, Crescencio; Ortega, Manuel; Verdejo, M. Felisa
2007-01-01
Experimental learning environments based on simulation usually require monitoring and adaptation to the actions the users carry out. Some systems provide this functionality, but they do so in a way which is static or cannot be applied to problem solving tasks. In response to this problem, we propose a method based on the use of intermediate…
Sahoo, Avimanyu; Xu, Hao; Jagannathan, Sarangapani
2016-01-01
This paper presents a novel adaptive neural network (NN) control of single-input and single-output uncertain nonlinear discrete-time systems under event sampled NN inputs. In this control scheme, the feedback signals are transmitted, and the NN weights are tuned in an aperiodic manner at the event sampled instants. After reviewing the NN approximation property with event sampled inputs, an adaptive state estimator (SE), consisting of linearly parameterized NNs, is utilized to approximate the unknown system dynamics in an event sampled context. The SE is viewed as a model and its approximated dynamics and the state vector, during any two events, are utilized for the event-triggered controller design. An adaptive event-trigger condition is derived by using both the estimated NN weights and a dead-zone operator to determine the event sampling instants. This condition both facilitates the NN approximation and reduces the transmission of feedback signals. The ultimate boundedness of both the NN weight estimation error and the system state vector is demonstrated through the Lyapunov approach. As expected, during an initial online learning phase, events are observed more frequently. Over time with the convergence of the NN weights, the inter-event times increase, thereby lowering the number of triggered events. These claims are illustrated through the simulation results.
NASA Astrophysics Data System (ADS)
Lausch, Anthony; Chen, Jeff; Ward, Aaron D.; Gaede, Stewart; Lee, Ting-Yim; Wong, Eugene
2014-11-01
Parametric response map (PRM) analysis is a voxel-wise technique for predicting overall treatment outcome, which shows promise as a tool for guiding personalized locally adaptive radiotherapy (RT). However, image registration error (IRE) introduces uncertainty into this analysis which may limit its use for guiding RT. Here we extend the PRM method to include an IRE-related PRM analysis confidence interval and also incorporate multiple graded classification thresholds to facilitate visualization. A Gaussian IRE model was used to compute an expected value and confidence interval for PRM analysis. The augmented PRM (A-PRM) was evaluated using CT-perfusion functional image data from patients treated with RT for glioma and hepatocellular carcinoma. Known rigid IREs were simulated by applying one thousand different rigid transformations to each image set. PRM and A-PRM analyses of the transformed images were then compared to analyses of the original images (ground truth) in order to investigate the two methods in the presence of controlled IRE. The A-PRM was shown to help visualize and quantify IRE-related analysis uncertainty. The use of multiple graded classification thresholds also provided additional contextual information which could be useful for visually identifying adaptive RT targets (e.g. sub-volume boosts). The A-PRM should facilitate reliable PRM guided adaptive RT by allowing the user to identify if a patient’s unique IRE-related PRM analysis uncertainty has the potential to influence target delineation.
NASA Technical Reports Server (NTRS)
Swenson, Harry N.; Zelenka, Richard E.; Hardy, Gordon H.; Dearing, Munro G.
1992-01-01
A computer aiding concept for low-altitude helicopter flight was developed and evaluated in a real-time piloted simulation. The concept included an optimal control trajectory-generation algorithm based upon dynamic programming and a helmet-mounted display (HMD) presentation of a pathway-in-the-sky, a phantom aircraft, and flight-path vector/predictor guidance symbology. The trajectory-generation algorithm uses knowledge of the global mission requirements, a digital terrain map, aircraft performance capabilities, and advanced navigation information to determine a trajectory between mission way points that seeks valleys to minimize threat exposure. The pilot evaluation was conducted at NASA ARC moving base Vertical Motion Simulator (VMS) by pilots representing NASA, the U.S. Army, the Air Force, and the helicopter industry. The pilots manually tracked the trajectory generated by the algorithm utilizing the HMD symbology. The pilots were able to satisfactorily perform the tracking tasks while maintaining a high degree of awareness of the outside world.
Liu, Han; Wu, Qiuwen
2011-08-07
For prostate cancer patients, online image-guided (IG) radiotherapy has been widely used in clinic to correct the translational inter-fractional motion at each treatment fraction. For uncertainties that cannot be corrected online, such as rotation and deformation of the target volume, margins are still required to be added to the clinical target volume (CTV) for the treatment planning. Offline adaptive radiotherapy has been implemented to optimize the treatment for each individual patient based on the measurements at early stages of treatment process. It has been shown that offline adaptive radiotherapy can effectively reduce the required margin. Recently a hybrid strategy of offline adaptive replanning and online IG was proposed and the geometric evaluation was performed. It was found that the planning margins can further be reduced by 1-2 mm compared to online IG only strategy. The purpose of this study was to investigate the dosimetric benefits of such a hybrid strategy on the target and organs at risk. A total of 420 repeated helical computed tomography scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles, SV) were included in the simulation. Two registration methods, based on center-of-mass shift of prostate only and prostate plus SV, were performed for IRP. The intensity-modulated radiotherapy was used in the simulation. Criteria on both cumulative and fractional doses were evaluated. Furthermore, the geometric evaluation was extended to investigate the optimal number of fractions necessary to construct the internal target volume (ITV) for the hybrid strategy. The dosimetric margin improvement was smaller than its geometric counterpart and was in the range of 0-1 mm. The optimal number of fractions necessary for the ITV construction is 2 for LRPs and 3-4 for IRPs in a hypofractionation protocol. A new cumulative index of target volume was proposed
NASA Astrophysics Data System (ADS)
Liu, Han; Wu, Qiuwen
2011-08-01
For prostate cancer patients, online image-guided (IG) radiotherapy has been widely used in clinic to correct the translational inter-fractional motion at each treatment fraction. For uncertainties that cannot be corrected online, such as rotation and deformation of the target volume, margins are still required to be added to the clinical target volume (CTV) for the treatment planning. Offline adaptive radiotherapy has been implemented to optimize the treatment for each individual patient based on the measurements at early stages of treatment process. It has been shown that offline adaptive radiotherapy can effectively reduce the required margin. Recently a hybrid strategy of offline adaptive replanning and online IG was proposed and the geometric evaluation was performed. It was found that the planning margins can further be reduced by 1-2 mm compared to online IG only strategy. The purpose of this study was to investigate the dosimetric benefits of such a hybrid strategy on the target and organs at risk. A total of 420 repeated helical computed tomography scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles, SV) were included in the simulation. Two registration methods, based on center-of-mass shift of prostate only and prostate plus SV, were performed for IRP. The intensity-modulated radiotherapy was used in the simulation. Criteria on both cumulative and fractional doses were evaluated. Furthermore, the geometric evaluation was extended to investigate the optimal number of fractions necessary to construct the internal target volume (ITV) for the hybrid strategy. The dosimetric margin improvement was smaller than its geometric counterpart and was in the range of 0-1 mm. The optimal number of fractions necessary for the ITV construction is 2 for LRPs and 3-4 for IRPs in a hypofractionation protocol. A new cumulative index of target volume was proposed
NASA Astrophysics Data System (ADS)
Viré, Axelle; Xiang, Jiansheng; Milthaler, Frank; Farrell, Patrick Emmet; Piggott, Matthew David; Latham, John-Paul; Pavlidis, Dimitrios; Pain, Christopher Charles
2012-12-01
Fluid-structure interactions are modelled by coupling the finite element fluid/ocean model `Fluidity-ICOM' with a combined finite-discrete element solid model `Y3D'. Because separate meshes are used for the fluids and solids, the present method is flexible in terms of discretisation schemes used for each material. Also, it can tackle multiple solids impacting on one another, without having ill-posed problems in the resolution of the fluid's equations. Importantly, the proposed approach ensures that Newton's third law is satisfied at the discrete level. This is done by first computing the action-reaction force on a supermesh, i.e. a function superspace of the fluid and solid meshes, and then projecting it to both meshes to use it as a source term in the fluid and solid equations. This paper demonstrates the properties of spatial conservation and accuracy of the method for a sphere immersed in a fluid, with prescribed fluid and solid velocities. While spatial conservation is shown to be independent of the mesh resolutions, accuracy requires fine resolutions in both fluid and solid meshes. It is further highlighted that unstructured meshes adapted to the solid concentration field reduce the numerical errors, in comparison with uniformly structured meshes with the same number of elements. The method is verified on flow past a falling sphere. Its potential for ocean applications is further shown through the simulation of vortex-induced vibrations of two cylinders and the flow past two flexible fibres.
GUIDANCE AWARENESS IN ELEMENTARY EDUCATION.
ERIC Educational Resources Information Center
MOREAU, GEORGE H., ED.
THE PURPOSE OF THE WORKSHOP IN ELEMENTARY SCHOOL GUIDANCE WAS TWOFOLD--(1) TO SHOW HOW GUIDANCE PROCEDURES AND TECHNIQUES CENTER ABOUT AND INVOLVE THE CHILD AS HE ADAPTS TO A NEW TYPE OF SCHOOL SETTING AND LEARNING PROCESS, AND (2) TO CREATE AN AWARENESS OF THE NEED FOR ALL AREAS OF COUNSELING AT THE ELEMENTARY SCHOOL LEVEL. OF THE ELEVEN PAPERS…
Guidance: Interim Municipal Settlement Policy
Interim guidance and fact sheets regarding settlements involving municipalities or municipal waste under Section 122 CERCLA as amended by SARA. Interim policy sets forth the criteria by which EPA generally determines whether to exercise enforcement discretion to pursue MSW generators and transporters as PRPs.
Guidance that explains the process for getting images approved in One EPA Web microsites and resource directories. includes an appendix that shows examples of what makes some images better than others, how some images convey meaning more than others
Designing Automated Guidance for Concept Diagrams in Inquiry Instruction
ERIC Educational Resources Information Center
Ryoo, Kihyun; Linn, Marcia C.
2016-01-01
Advances in automated scoring technologies have the potential to support student learning during inquiry instruction by providing timely and adaptive guidance on individual students' responses. To identify which forms of automated guidance can be beneficial for inquiry learning, we compared reflective guidance to directive guidance for…
Broom, Donald M
2006-01-01
The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and
ERIC Educational Resources Information Center
Rosenstein, Joseph G., Ed.; Franzblau, Deborah S., Ed.; Roberts, Fred S., Ed.
This book is a collection of articles by experienced educators and explains why and how discrete mathematics should be taught in K-12 classrooms. It includes evidence for "why" and practical guidance for "how" and also discusses how discrete mathematics can be used as a vehicle for achieving the broader goals of the major…
ERIC Educational Resources Information Center
Poulin, David; Martinez, David; Aenchbacher, Amy; Aiello, Rocco; Doyle, Mike; Hilgenbrinck, Linda; Busse, Sean; Cappuccio, Jim
2013-01-01
In Part III of the feature, physical educators and adapted physical educators offer current best practices as models of implementation for readers. Contributions included are: (1) Answer to the Dear Colleague Letter from the Anchorage School District's Adapted Sport Program (David Poulin); (2) Georgia's Adapted Physical Educators Response to the…
NASA Astrophysics Data System (ADS)
Bargatze, L. F.
2015-12-01
Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted
Hypervelocity Orbital Intercept Guidance
1988-04-14
Professor Charles E. Fosha, Jr. Terminal guidance of a hypervelocity exo-atmospheric orbital interceptor with free end-time is examined. The pursuer is...stochastic nonlinear systems with free end-time was developed by Tse and 29 Bar-Shalom [5]. This method differs from the optimal control formulation...Vol. AC-18, No. 2, April 1973, pp. 98-108. 5. Tse, E., and Y. Bar-Shalom, "Adaptive Dual Control For Stochastic Nonlinear Systems with Free End- Time
Interim Guidance: Municipal Solid Waste Exemption under Superfund
Interim guidance discusses the statutory provisions of CERCLA § 107(p) and identifies some factors to be considered by EPA and DOJ staff in exercising their enforcement discretion of MSW at an NPL site.
Collective cell migration: guidance principles and hierarchies.
Haeger, Anna; Wolf, Katarina; Zegers, Mirjam M; Friedl, Peter
2015-09-01
Collective cell migration results from the establishment and maintenance of collective polarization, mechanocoupling, and cytoskeletal kinetics. The guidance of collective cell migration depends on a reciprocal process between cell-intrinsic multicellular organization with leader-follower cell behavior and results in mechanosensory integration of extracellular guidance cues. Important guidance mechanisms include chemotaxis, haptotaxis, durotaxis, and strain-induced mechanosensing to move cell groups along interfaces and paths of least resistance. Additional guidance mechanisms steering cell groups during specialized conditions comprise electrotaxis and passive drift. To form higher-order cell and tissue structures during morphogenesis and cancer invasion, these guidance principles act in parallel and are integrated for collective adaptation to and shaping of varying tissue environments. We review mechanochemical and electrical inputs and multiparameter signal integration underlying collective guidance, decision making, and outcome.
Space shuttle guidance, navigation, and control design equations. Volume 3: Guidance
NASA Technical Reports Server (NTRS)
1973-01-01
Space shuttle guidance, navigation, and control design equations are presented. The space-shuttle mission includes three relatively distinct guidance phases which are discussed; atmospheric boost, which is characterized by an adaptive guidance law; extra-atmospheric activities; and re-entry activities, where aerodynamic surfaces are the principal effectors. Guidance tasks include pre-maneuver targeting and powered flight guidance, where powered flight is defined to include the application of aerodynamic forces as well as thruster forces. A flow chart which follows guidance activities throughout the mission from the pre-launch phase through touchdown is presented. The main guidance programs and subroutines used in each phase of a typical rendezvous mission are listed. Detailed software requirements are also presented.
Autonomous Guidance, Navigation and Control
NASA Technical Reports Server (NTRS)
Bordano, A. J.; Mcswain, G. G.; Fernandes, S. T.
1991-01-01
The NASA Autonomous Guidance, Navigation and Control (GN&C) Bridging program is reviewed to demonstrate the program plan and GN&C systems for the Space Shuttle. The ascent CN&C system is described in terms of elements such as the general-purpose digital computers, sensors for the navigation subsystem, the guidance-system software, and the flight-control subsystem. Balloon-based and lidar wind soundings are used for operations assessment on the day of launch, and the guidance software is based on dedicated units for atmospheric powered flight, vacuum powered flight, and abort-specific situations. Optimization of the flight trajectories is discussed, and flight-control responses are illustrated for wavelengths of 500-6000 m. Alternate sensors are used for load relief, and adaptive GN&C systems based on alternate gain synthesis are used for systems failures.
Norquist, Josephine M; Khawaja, Shazia S; Kurian, Cizely; Mast, T Christopher; Liaw, Kai-Li; Robertson, Michael N; Evans, Barbara; Gutsch, David; Saddier, Patricia
2012-09-01
The Adult/Adolescent Vaccination Report Card (VRC) was developed and validated by Merck in 1998 for use in vaccine clinical trials to collect information from trial subjects on complaints for both local and systemic events after vaccination. This short report describes the revision to the original validated VRC in order to align with the guidelines outlined in the 2007 FDA Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in Preventive Vaccine Clinical Trials. Since the VRC elicits trial subjects' self-reports of any adverse experiences (AE) occurring post vaccination, it was important that subsequent modifications of the VRC retained the original user-friendly characteristics while gathering the appropriate information to align with the FDA Guidance. A convenience sample of 15 participants (71% females, 87% white and mean (SD) age 45 (13) years was recruited to obtain feedback in order to revise the Adult/Adolescent VRC. Based on the feedback received, the following were slightly revised: ruler for the measurements of local systemic reactions, severity ratings, and general instructions. The revised VRC is currently being used in Merck vaccine clinical trials.
Dorda, Antonius Schürrer, Ferdinand
2015-03-01
We present a novel numerical scheme for the deterministic solution of the Wigner transport equation, especially suited to deal with situations in which strong quantum effects are present. The unique feature of the algorithm is the expansion of the Wigner function in local basis functions, similar to finite element or finite volume methods. This procedure yields a discretization of the pseudo-differential operator that conserves the particle density on arbitrarily chosen grids. The high flexibility in refining the grid spacing together with the weighted essentially non-oscillatory (WENO) scheme for the advection term allows for an accurate and well-resolved simulation of the phase space dynamics. A resonant tunneling diode is considered as test case and a detailed convergence study is given by comparing the results to a non-equilibrium Green's functions calculation. The impact of the considered domain size and of the grid spacing is analyzed. The obtained convergence of the results towards a quasi-exact agreement of the steady state Wigner and Green's functions computations demonstrates the accuracy of the scheme, as well as the high flexibility to adjust to different physical situations.
Dorda, Antonius; Schürrer, Ferdinand
2015-03-01
We present a novel numerical scheme for the deterministic solution of the Wigner transport equation, especially suited to deal with situations in which strong quantum effects are present. The unique feature of the algorithm is the expansion of the Wigner function in local basis functions, similar to finite element or finite volume methods. This procedure yields a discretization of the pseudo-differential operator that conserves the particle density on arbitrarily chosen grids. The high flexibility in refining the grid spacing together with the weighted essentially non-oscillatory (WENO) scheme for the advection term allows for an accurate and well-resolved simulation of the phase space dynamics. A resonant tunneling diode is considered as test case and a detailed convergence study is given by comparing the results to a non-equilibrium Green's functions calculation. The impact of the considered domain size and of the grid spacing is analyzed. The obtained convergence of the results towards a quasi-exact agreement of the steady state Wigner and Green's functions computations demonstrates the accuracy of the scheme, as well as the high flexibility to adjust to different physical situations.
Dorda, Antonius; Schürrer, Ferdinand
2015-01-01
We present a novel numerical scheme for the deterministic solution of the Wigner transport equation, especially suited to deal with situations in which strong quantum effects are present. The unique feature of the algorithm is the expansion of the Wigner function in local basis functions, similar to finite element or finite volume methods. This procedure yields a discretization of the pseudo-differential operator that conserves the particle density on arbitrarily chosen grids. The high flexibility in refining the grid spacing together with the weighted essentially non-oscillatory (WENO) scheme for the advection term allows for an accurate and well-resolved simulation of the phase space dynamics. A resonant tunneling diode is considered as test case and a detailed convergence study is given by comparing the results to a non-equilibrium Green's functions calculation. The impact of the considered domain size and of the grid spacing is analyzed. The obtained convergence of the results towards a quasi-exact agreement of the steady state Wigner and Green's functions computations demonstrates the accuracy of the scheme, as well as the high flexibility to adjust to different physical situations. PMID:25892748
On the design of fuzzified trajectory shaping guidance law.
Lin, Chun-Liang; Lin, Yu-Ping; Chen, Kai-Ming
2009-04-01
Midcourse guidance is commonly designed to save as much energy as possible so that the missile's final speed can be maximized while entering the homing stage. For this purpose, a competitive guidance design should be able to generate an admissible flight trajectory as to bring the interceptor to a superior altitude for a favorable target engagement. In this paper, a new adaptive trajectory shaping guidance scheme based on the adaptive fuzzy inference system, which is capable of generating a variety of trajectories for efficient target interception, is presented. The guidance law is developed with the aim of saving the interceptor's energy conservation while improving performance robustness. Applications of the presented approach have included a variety of mission oriented guidance, such as cruise missile guidance, anti-ballistic missile guidance, etc.
Synchronization Of Parallel Discrete Event Simulations
NASA Technical Reports Server (NTRS)
Steinman, Jeffrey S.
1992-01-01
Adaptive, parallel, discrete-event-simulation-synchronization algorithm, Breathing Time Buckets, developed in Synchronous Parallel Environment for Emulation and Discrete Event Simulation (SPEEDES) operating system. Algorithm allows parallel simulations to process events optimistically in fluctuating time cycles that naturally adapt while simulation in progress. Combines best of optimistic and conservative synchronization strategies while avoiding major disadvantages. Algorithm processes events optimistically in time cycles adapting while simulation in progress. Well suited for modeling communication networks, for large-scale war games, for simulated flights of aircraft, for simulations of computer equipment, for mathematical modeling, for interactive engineering simulations, and for depictions of flows of information.
DOE Waste Treatability Group Guidance
Kirkpatrick, T.D.
1995-01-01
This guidance presents a method and definitions for aggregating U.S. Department of Energy (DOE) waste into streams and treatability groups based on characteristic parameters that influence waste management technology needs. Adaptable to all DOE waste types (i.e., radioactive waste, hazardous waste, mixed waste, sanitary waste), the guidance establishes categories and definitions that reflect variations within the radiological, matrix (e.g., bulk physical/chemical form), and regulated contaminant characteristics of DOE waste. Beginning at the waste container level, the guidance presents a logical approach to implementing the characteristic parameter categories as part of the basis for defining waste streams and as the sole basis for assigning streams to treatability groups. Implementation of this guidance at each DOE site will facilitate the development of technically defined, site-specific waste stream data sets to support waste management planning and reporting activities. Consistent implementation at all of the sites will enable aggregation of the site-specific waste stream data sets into comparable national data sets to support these activities at a DOE complex-wide level.
Unified powered flight guidance
NASA Technical Reports Server (NTRS)
Brand, T. J.; Brown, D. W.; Higgins, J. P.
1973-01-01
A complete revision of the orbiter powered flight guidance scheme is presented. A unified approach to powered flight guidance was taken to accommodate all phases of exo-atmospheric orbiter powered flight, from ascent through deorbit. The guidance scheme was changed from the previous modified version of the Lambert Aim Point Maneuver Mode used in Apollo to one that employs linear tangent guidance concepts. This document replaces the previous ascent phase equation document.
Hu, Y.
2015-06-15
MRI-guided treatment is a growing area of medicine, particularly in radiotherapy and surgery. The exquisite soft tissue anatomic contrast offered by MRI, along with functional imaging, makes the use of MRI during therapeutic procedures very attractive. Challenging the utility of MRI in the therapy room are many issues including the physics of MRI and the impact on the environment and therapeutic instruments, the impact of the room and instruments on the MRI; safety, space, design and cost. In this session, the applications and challenges of MRI-guided treatment will be described. The session format is: Past, present and future: MRI-guided radiotherapy from 2005 to 2025: Jan Lagendijk Battling Maxwell’s equations: Physics challenges and solutions for hybrid MRI systems: Paul Keall I want it now!: Advances in MRI acquisition, reconstruction and the use of priors to enable fast anatomic and physiologic imaging to inform guidance and adaptation decisions: Yanle Hu MR in the OR: The growth and applications of MRI for interventional radiology and surgery: Rebecca Fahrig Learning Objectives: To understand the history and trajectory of MRI-guided radiotherapy To understand the challenges of integrating MR imaging systems with linear accelerators To understand the latest in fast MRI methods to enable the visualisation of anatomy and physiology on radiotherapy treatment timescales To understand the growing role and challenges of MRI for image-guided surgical procedures My disclosures are publicly available and updated at: http://sydney.edu.au/medicine/radiation-physics/about-us/disclosures.php.
Discrete Analog Processing for Tracking and Guidance Control
1980-11-01
the idea of the system is to compare successive frames of com- puter vision data to compute relative motion and displacements in three dimen- sions...ability, etc. All these auxiliary operations can be obtained at a rela- tively slow rate if the tracking algoritnm can keep the system functioning...values. However, if the formula is solved for displacement of the target from the reference point, then texture measurements from successive frames
NASA Technical Reports Server (NTRS)
Holley, M. D.; Swingle, W. L.; Bachman, S. L.; Leblanc, C. J.; Howard, H. T.; Biggs, H. M.
1976-01-01
The primary guidance, navigation, and control systems for both the lunar module and the command module are described. Development of the Apollo primary guidance systems is traced from adaptation of the Polaris Mark II system through evolution from Block I to Block II configurations; the discussion includes design concepts used, test and qualification programs performed, and major problems encountered. The major subsystems (inertial, computer, and optical) are covered. Separate sections on the inertial components (gyroscopes and accelerometers) are presented because these components represent a major contribution to the success of the primary guidance, navigation, and control system.
No-Reference Image Blur Assessment Based on Discrete Orthogonal Moments.
Li, Leida; Lin, Weisi; Wang, Xuesong; Yang, Gaobo; Bahrami, Khosro; Kot, Alex C
2016-01-01
Blur is a key determinant in the perception of image quality. Generally, blur causes spread of edges, which leads to shape changes in images. Discrete orthogonal moments have been widely studied as effective shape descriptors. Intuitively, blur can be represented using discrete moments since noticeable blur affects the magnitudes of moments of an image. With this consideration, this paper presents a blind image blur evaluation algorithm based on discrete Tchebichef moments. The gradient of a blurred image is first computed to account for the shape, which is more effective for blur representation. Then the gradient image is divided into equal-size blocks and the Tchebichef moments are calculated to characterize image shape. The energy of a block is computed as the sum of squared non-DC moment values. Finally, the proposed image blur score is defined as the variance-normalized moment energy, which is computed with the guidance of a visual saliency model to adapt to the characteristic of human visual system. The performance of the proposed method is evaluated on four public image quality databases. The experimental results demonstrate that our method can produce blur scores highly consistent with subjective evaluations. It also outperforms the state-of-the-art image blur metrics and several general-purpose no-reference quality metrics.
Principles of Discrete Time Mechanics
NASA Astrophysics Data System (ADS)
Jaroszkiewicz, George
2014-04-01
1. Introduction; 2. The physics of discreteness; 3. The road to calculus; 4. Temporal discretization; 5. Discrete time dynamics architecture; 6. Some models; 7. Classical cellular automata; 8. The action sum; 9. Worked examples; 10. Lee's approach to discrete time mechanics; 11. Elliptic billiards; 12. The construction of system functions; 13. The classical discrete time oscillator; 14. Type 2 temporal discretization; 15. Intermission; 16. Discrete time quantum mechanics; 17. The quantized discrete time oscillator; 18. Path integrals; 19. Quantum encoding; 20. Discrete time classical field equations; 21. The discrete time Schrodinger equation; 22. The discrete time Klein-Gordon equation; 23. The discrete time Dirac equation; 24. Discrete time Maxwell's equations; 25. The discrete time Skyrme model; 26. Discrete time quantum field theory; 27. Interacting discrete time scalar fields; 28. Space, time and gravitation; 29. Causality and observation; 30. Concluding remarks; Appendix A. Coherent states; Appendix B. The time-dependent oscillator; Appendix C. Quaternions; Appendix D. Quantum registers; References; Index.
NASA Technical Reports Server (NTRS)
Hanson, John M.; Shrader, M. Wade; Cruzen, Craig A.
1995-01-01
This paper contains results from ascent guidance studies conducted at the NASA Marshall Space Flight Center. The studies include investigation of different guidance schemes for a variety of potential launch vehicles. Criteria of a successful ascent guidance scheme are low operations cost, satisfaction of load indicator constraints, and maximization of performance. Results show that open-loop designs as a function of altitude or velocity are preferable to designs that are functions of time. Optimized open-loop trajectories can increase performance while maintaining load indicators within limits. Closed-loop atmospheric schemes that involve linear tangent steering or feedback of velocity terms for trajectory modification did not yield any improvement. Early release of vacuum closed-loop guidance, including use during solid rocket booster operation, yields some improvements. Evaluation of a closed-loop optimization scheme for flying through the atmosphere shows no advantages over open-loop optimization. Dispersion study results for several potential guidance schemes and launch vehicles are included in the paper and are not a discriminator between guidance schemes. The primary cost driver is mission operations philosophy, not choice of guidance scheme. More autonomous guidance schemes can help in movement towards a philosophy that would reduce operations costs.
Aiding Vertical Guidance Understanding
NASA Technical Reports Server (NTRS)
Feary, Michael; McCrobie, Daniel; Alkin, Martin; Sherry, Lance; Polson, Peter; Palmer, Everett; McQuinn, Noreen
1998-01-01
A two-part study was conducted to evaluate modern flight deck automation and interfaces. In the first part, a survey was performed to validate the existence of automation surprises with current pilots. Results indicated that pilots were often surprised by the behavior of the automation. There were several surprises that were reported more frequently than others. An experimental study was then performed to evaluate (1) the reduction of automation surprises through training specifically for the vertical guidance logic, and (2) a new display that describes the flight guidance in terms of aircraft behaviors instead of control modes. The study was performed in a simulator that was used to run a complete flight with actual airline pilots. Three groups were used to evaluate the guidance display and training. In the training, condition, participants went through a training program for vertical guidance before flying the simulation. In the display condition, participants ran through the same training program and then flew the experimental scenario with the new Guidance-Flight Mode Annunciator (G-FMA). Results showed improved pilot performance when given training specifically for the vertical guidance logic and greater improvements when given the training and the new G-FMA. Using actual behavior of the avionics to design pilot training and FMA is feasible, and when the automated vertical guidance mode of the Flight Management System is engaged, the display of the guidance mode and targets yields improved pilot performance.
NASA Technical Reports Server (NTRS)
Harpold, J. C.; Graves, C. A., Jr.
1978-01-01
This paper describes the design of the entry guidance for the Space Shuttle Orbiter. This guidance provides the steering commands for trajectory control from initial penetration of the earth's atmosphere until the terminal area guidance is activated at an earth-relative speed of 2500 fps. At this point, the Orbiter is at a distance of about 50 nmi from the runway threshold, and at an altitude of about 80,000 ft. The entry guidance design is based on an analytic solution of the equations of motion defining the drag acceleration profile that meets the terminal criteria of the entry flight while maintaining the flight within systems and operational constraints. Guidance commands, which are based on a control law that ensures damping of oscillatory type trajectory motion, are computed to steer the Orbiter to this drag acceleration profile.
Shuttle entry guidance revisited
NASA Astrophysics Data System (ADS)
Mease, Kenneth D.; Kremer, Jean-Paul
1992-08-01
The Shuttle entry guidance concept is reviewed which is aimed at tracking a reference drag trajectory that leads to the specified range and velocity for the initiation of the terminal energy management phase. An approximate method of constructing the domain of attraction is proposed, and its validity is ascertained by simulation. An alternative guidance law yielding global exponential tracking in the absence of control saturation is derived using a feedback linearization method. It is noted that the alternative guidance law does not improve on the stability and performance of the current guidance law, for the operating domain and control capability of the Shuttle. It is suggested that the new guidance law with a larger operating domain and increased lift-to-drag capability would be superior.
Shuttle entry guidance revisited
NASA Technical Reports Server (NTRS)
Mease, Kenneth D.; Kremer, Jean-Paul
1992-01-01
The Shuttle entry guidance concept is reviewed which is aimed at tracking a reference drag trajectory that leads to the specified range and velocity for the initiation of the terminal energy management phase. An approximate method of constructing the domain of attraction is proposed, and its validity is ascertained by simulation. An alternative guidance law yielding global exponential tracking in the absence of control saturation is derived using a feedback linearization method. It is noted that the alternative guidance law does not improve on the stability and performance of the current guidance law, for the operating domain and control capability of the Shuttle. It is suggested that the new guidance law with a larger operating domain and increased lift-to-drag capability would be superior.
Influence of haptic guidance in learning a novel visuomotor task.
van Asseldonk, Edwin H F; Wessels, Martijn; Stienen, Arno H A; van der Helm, Frans C T; van der Kooij, Herman
2009-01-01
In (re)learning of movements, haptic guidance can be used to direct the needed adaptations in motor control. Haptic guidance influences the main driving factors of motor adaptation, execution error, and control effort in different ways. Human-control effort is dissipated in the interactions that occur during haptic guidance. Minimizing the control effort would reduce the interaction forces and result in adaptation. However, guidance also decreases the magnitude of the execution errors, which could inhibit motor adaptation. The aim of this study was to assess how different types of haptic guidance affect kinematic adaptation in a novel visuomotor task. Five groups of subjects adapted to a reaching task in which the visual representation of the hand was rotated 30 degrees. Each group was guided by a different force field. The force fields differed in magnitude and direction in order to discern the adaptation based on execution errors and control effort. The results demonstrated that the execution error did indeed play a key role in adaptation. The more the guiding forces restricted the occurrence of execution errors, the smaller the amount and rate of adaptation. However, the force field that enlarged the execution errors did not result in an increased rate of adaptation. The presence of a small amount of adaptation in the groups who did not experience execution errors during training suggested that adaptation could be driven on a much slower rate and on the basis of minimization of control effort as was evidenced by a gradual decrease of the interaction forces during training. Remarkably, also in the group in which the subjects were passive and completely guided, a small but significant adaptation occurred. The conclusion is that both minimization of execution errors and control effort drives kinematic adaptation in a novel visuomotor task, but the latter at a much slower rate.
Federal Guidance for Radiation Protection
EPA produces federal guidance technical reports, which standardize dose and risk assessment and issues radiation protection guidance to federal agencies. This page provides links to federal guidance policy recommendations and technical reports.
Pollinator Risk Assessment Guidance
This Guidance is part of a long-term strategy to advance the science of assessing the risks posed by pesticides to honey bees, giving risk managers the means to further improve pollinator protection in our regulatory decisions.
The policy establishes the principles for accessible Electronic and Information Technology (EIT) and complying with Section 508 requirements. The guidance defines EIT and the technical and functional performance criteria necessary for compliance.
Morris, J; Johnson, S
2007-12-03
The Distinct Element Method (also frequently referred to as the Discrete Element Method) (DEM) is a Lagrangian numerical technique where the computational domain consists of discrete solid elements which interact via compliant contacts. This can be contrasted with Finite Element Methods where the computational domain is assumed to represent a continuum (although many modern implementations of the FEM can accommodate some Distinct Element capabilities). Often the terms Discrete Element Method and Distinct Element Method are used interchangeably in the literature, although Cundall and Hart (1992) suggested that Discrete Element Methods should be a more inclusive term covering Distinct Element Methods, Displacement Discontinuity Analysis and Modal Methods. In this work, DEM specifically refers to the Distinct Element Method, where the discrete elements interact via compliant contacts, in contrast with Displacement Discontinuity Analysis where the contacts are rigid and all compliance is taken up by the adjacent intact material.
Synchronous Discrete Harmonic Oscillator
Antippa, Adel F.; Dubois, Daniel M.
2008-10-17
We introduce the synchronous discrete harmonic oscillator, and present an analytical, numerical and graphical study of its characteristics. The oscillator is synchronous when the time T for one revolution covering an angle of 2{pi} in phase space, is an integral multiple N of the discrete time step {delta}t. It is fully synchronous when N is even. It is pseudo-synchronous when T/{delta}t is rational. In the energy conserving hyperincursive representation, the phase space trajectories are perfectly stable at all time scales, and in both synchronous and pseudo-synchronous modes they cycle through a finite number of phase space points. Consequently, both the synchronous and the pseudo-synchronous hyperincursive modes of time-discretization provide a physically realistic and mathematically coherent, procedure for dynamic, background independent, discretization of spacetime. The procedure is applicable to any stable periodic dynamical system, and provokes an intrinsic correlation between space and time, whereby space-discretization is a direct consequence of background-independent time-discretization. Hence, synchronous discretization moves the formalism of classical mechanics towards that of special relativity. The frequency of the hyperincursive discrete harmonic oscillator is ''blue shifted'' relative to its continuum counterpart. The frequency shift has the precise value needed to make the speed of the system point in phase space independent of the discretizing time interval {delta}t. That is the speed of the system point is the same on the polygonal (in the discrete case) and the circular (in the continuum case) phase space trajectories.
Synchronous Discrete Harmonic Oscillator
NASA Astrophysics Data System (ADS)
Antippa, Adel F.; Dubois, Daniel M.
2008-10-01
We introduce the synchronous discrete harmonic oscillator, and present an analytical, numerical and graphical study of its characteristics. The oscillator is synchronous when the time T for one revolution covering an angle of 2π in phase space, is an integral multiple N of the discrete time step Δt. It is fully synchronous when N is even. It is pseudo-synchronous when T/Δt is rational. In the energy conserving hyperincursive representation, the phase space trajectories are perfectly stable at all time scales, and in both synchronous and pseudo-synchronous modes they cycle through a finite number of phase space points. Consequently, both the synchronous and the pseudo-synchronous hyperincursive modes of time-discretization provide a physically realistic and mathematically coherent, procedure for dynamic, background independent, discretization of spacetime. The procedure is applicable to any stable periodic dynamical system, and provokes an intrinsic correlation between space and time, whereby space-discretization is a direct consequence of background-independent time-discretization. Hence, synchronous discretization moves the formalism of classical mechanics towards that of special relativity. The frequency of the hyperincursive discrete harmonic oscillator is "blue shifted" relative to its continuum counterpart. The frequency shift has the precise value needed to make the speed of the system point in phase space independent of the discretizing time interval Δt. That is the speed of the system point is the same on the polygonal (in the discrete case) and the circular (in the continuum case) phase space trajectories.
Comprehensive Guidance Programs That Work.
ERIC Educational Resources Information Center
Gysbers, Norman C.; And Others
This monograph describes how the comprehensive guidance model is transforming elementary-secondary school guidance and counseling programs in schools across the country. It incorporates the ideas and experiences of 12 guidance program developers in the actual use of the comprehensive guidance model in diverse school and cultural settings. The book…
Aerocapture Guidance Algorithm Comparison Campaign
NASA Technical Reports Server (NTRS)
Rousseau, Stephane; Perot, Etienne; Graves, Claude; Masciarelli, James P.; Queen, Eric
2002-01-01
The aerocapture is a promising technique for the future human interplanetary missions. The Mars Sample Return was initially based on an insertion by aerocapture. A CNES orbiter Mars Premier was developed to demonstrate this concept. Mainly due to budget constraints, the aerocapture was cancelled for the French orbiter. A lot of studies were achieved during the three last years to develop and test different guidance algorithms (APC, EC, TPC, NPC). This work was shared between CNES and NASA, with a fruitful joint working group. To finish this study an evaluation campaign has been performed to test the different algorithms. The objective was to assess the robustness, accuracy, capability to limit the load, and the complexity of each algorithm. A simulation campaign has been specified and performed by CNES, with a similar activity on the NASA side to confirm the CNES results. This evaluation has demonstrated that the numerical guidance principal is not competitive compared to the analytical concepts. All the other algorithms are well adapted to guaranty the success of the aerocapture. The TPC appears to be the more robust, the APC the more accurate, and the EC appears to be a good compromise.
Correcting for Visuo-Haptic Biases in 3D Haptic Guidance.
van Beek, Femke E; Kuling, Irene A; Brenner, Eli; Bergmann Tiest, Wouter M; Kappers, Astrid M L
2016-01-01
Visuo-haptic biases are observed when bringing your unseen hand to a visual target. The biases are different between, but consistent within participants. We investigated the usefulness of adjusting haptic guidance to these user-specific biases in aligning haptic and visual perception. By adjusting haptic guidance according to the biases, we aimed to reduce the conflict between the modalities. We first measured the biases using an adaptive procedure. Next, we measured performance in a pointing task using three conditions: 1) visual images that were adjusted to user-specific biases, without haptic guidance, 2) veridical visual images combined with haptic guidance, and 3) shifted visual images combined with haptic guidance. Adding haptic guidance increased precision. Combining haptic guidance with user-specific visual information yielded the highest accuracy and the lowest level of conflict with the guidance at the end point. These results show the potential of correcting for user-specific perceptual biases when designing haptic guidance.
Correcting for Visuo-Haptic Biases in 3D Haptic Guidance
Kuling, Irene A.; Brenner, Eli; Bergmann Tiest, Wouter M.; Kappers, Astrid M. L.
2016-01-01
Visuo-haptic biases are observed when bringing your unseen hand to a visual target. The biases are different between, but consistent within participants. We investigated the usefulness of adjusting haptic guidance to these user-specific biases in aligning haptic and visual perception. By adjusting haptic guidance according to the biases, we aimed to reduce the conflict between the modalities. We first measured the biases using an adaptive procedure. Next, we measured performance in a pointing task using three conditions: 1) visual images that were adjusted to user-specific biases, without haptic guidance, 2) veridical visual images combined with haptic guidance, and 3) shifted visual images combined with haptic guidance. Adding haptic guidance increased precision. Combining haptic guidance with user-specific visual information yielded the highest accuracy and the lowest level of conflict with the guidance at the end point. These results show the potential of correcting for user-specific perceptual biases when designing haptic guidance. PMID:27438009
Discrete dislocations in graphene
NASA Astrophysics Data System (ADS)
Ariza, M. P.; Ortiz, M.
2010-05-01
In this work, we present an application of the theory of discrete dislocations of Ariza and Ortiz (2005) to the analysis of dislocations in graphene. Specifically, we discuss the specialization of the theory to graphene and its further specialization to the force-constant model of Aizawa et al. (1990). The ability of the discrete-dislocation theory to predict dislocation core structures and energies is critically assessed for periodic arrangements of dislocation dipoles and quadrupoles. We show that, with the aid of the discrete Fourier transform, those problems are amenable to exact solution within the discrete-dislocation theory, which confers the theory a distinct advantage over conventional atomistic models. The discrete dislocations exhibit 5-7 ring core structures that are consistent with observation and result in dislocation energies that fall within the range of prediction of other models. The asymptotic behavior of dilute distributions of dislocations is characterized analytically in terms of a discrete prelogarithmic energy tensor. Explicit expressions for this discrete prelogarithmic energy tensor are provided up to quadratures.
Video guidance, landing, and imaging systems
NASA Technical Reports Server (NTRS)
Schappell, R. T.; Knickerbocker, R. L.; Tietz, J. C.; Grant, C.; Rice, R. B.; Moog, R. D.
1975-01-01
The adaptive potential of video guidance technology for earth orbital and interplanetary missions was explored. The application of video acquisition, pointing, tracking, and navigation technology was considered to three primary missions: planetary landing, earth resources satellite, and spacecraft rendezvous and docking. It was found that an imaging system can be mechanized to provide a spacecraft or satellite with a considerable amount of adaptability with respect to its environment. It also provides a level of autonomy essential to many future missions and enhances their data gathering ability. The feasibility of an autonomous video guidance system capable of observing a planetary surface during terminal descent and selecting the most acceptable landing site was successfully demonstrated in the laboratory. The techniques developed for acquisition, pointing, and tracking show promise for recognizing and tracking coastlines, rivers, and other constituents of interest. Routines were written and checked for rendezvous, docking, and station-keeping functions.
Feedback nonlinear discrete-time systems
NASA Astrophysics Data System (ADS)
Yu, Miao; Wang, Jiasen; Qi, Donglian
2014-11-01
In this paper, we design an adaptive iterative learning control method for a class of high-order nonlinear output feedback discrete-time systems with random initial conditions and iteration-varying desired trajectories. An n-step ahead predictor approach is employed to estimate future outputs. The discrete Nussbaum gain method is incorporated into the control design to deal with unknown control directions. The proposed control algorithm ensures that the tracking error converges to zero asymptotically along the iterative learning axis except for the beginning outputs affected by random initial conditions. A numerical simulation is carried out to demonstrate the efficacy of the presented control laws.
NASA Astrophysics Data System (ADS)
Aydin, Alhun; Sisman, Altug
2016-03-01
By considering the quantum-mechanically minimum allowable energy interval, we exactly count number of states (NOS) and introduce discrete density of states (DOS) concept for a particle in a box for various dimensions. Expressions for bounded and unbounded continua are analytically recovered from discrete ones. Even though substantial fluctuations prevail in discrete DOS, they're almost completely flattened out after summation or integration operation. It's seen that relative errors of analytical expressions of bounded/unbounded continua rapidly decrease for high NOS values (weak confinement or high energy conditions), while the proposed analytical expressions based on Weyl's conjecture always preserve their lower error characteristic.
Anticipatory guidance through DVD.
Franz, Sandra; McMahon, Pamela M; Calongne, Laurinda; Steele-Moses, Susan K
2014-03-01
The major purpose of the study was to determine if a 5-minute DVD is an effective method for communicating anticipatory guidance to parents at their child's 4-month well-child visit. A total of 84 caregivers were randomly assigned to receive anticipatory guidance through standard care (written anticipatory guidance handout and free talk) or DVD (DVD format + standard care). Participants completed a brief questionnaire immediately before and after their visit. As anticipated, knowledge scores improved significantly from pre-test to post-test. There was also a significant interaction between format used for anticipatory guidance and time. Specifically, there was greater improvement in knowledge over time for parents in the DVD group as compared with the standard care group. Additionally, the mean knowledge level of those in the DVD group as compared with those in the standard care group trended toward significance. Finally, visit length was shortened by nearly 3 minutes in the DVD group, and close to 100% of all respondents, regardless of anticipatory guidance format, indicated that they were very satisfied with their visit and amount of information learned.
ERIC Educational Resources Information Center
Peters, James V.
2004-01-01
Using the methods of finite difference equations the discrete analogue of the parabolic and catenary cable are analysed. The fibonacci numbers and the golden ratio arise in the treatment of the catenary.
ERIC Educational Resources Information Center
Crisler, Nancy; Froelich, Gary
1990-01-01
Discussed are summary recommendations concerning the integration of some aspects of discrete mathematics into existing secondary mathematics courses. Outlines of course activities are grouped into the three levels of prealgebra, algebra, and geometry. Some sample problems are included. (JJK)
Annual Compliance Certification Guidance
This document may be of assistance in applying the Title V air operating permit regulations. This document is part of the Title V Policy and Guidance Database available at www2.epa.gov/title-v-operating-permits/title-v-operating-permit-policy-and-guidance-document-index. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.
Guidance publication proves timely.
Baillie, Jonathan
2011-05-01
The importance of properly identifying, assessing, and managing risk in all areas of engineering practice, the fact that genuine innovation is almost impossible without a certain element of risk-taking, and the need to acknowledge and respond to public concerns, however much some may be ill-founded, over the risks inherent in technological and engineering advances, are highlighted in a new risk guidance document, Guidance on Risk for the Engineering Profession, published by the Engineering Council in London last month. HEJ editor Jonathan Baillie reports.
On-orbit guidance for the Delta 180 mission
NASA Astrophysics Data System (ADS)
Rebholz, Jeffery J.
The development of the guidance modes used by both the Delta second stage and the new third stage, the Payload Adapter System, is discussed. The Delta 180 mission objectives included observations of a spacecraft against a variety of ranges, tracking a launch vehicle within its plume, and the interception of an accelerating target by an active radar seeker. Of particular interest are the guidance modes prior to the intercept.
Guidance on lobbying restrictions
The purpose of this guidance is to remind nonprofit organizations, universities, and other non-government recipients of EPA grants that, with very limited exceptions, you may not use Federal grant funds or cost-sharing funds to conduct lobbying activities.
Guidelines for Guidance Services.
ERIC Educational Resources Information Center
Manitoba Dept. of Education and Training, Winnipeg.
The purpose of this booklet is to provide direction and assistance to school divisions as they develop responsive, effective, and accountable guidance services and programs at the school level. The guidelines presented provide a broad conceptual framework of definitions and goals and outline expectations for service standards. Models and…
Foundations of Career Guidance.
ERIC Educational Resources Information Center
Ruff, Eldon E.
The paper traces the evolution of career guidance from 1909 to the present. The predominant views before 1950 were almost entirely nondevelopmental, but in response to questions raised at a series of major national conferences in the 1960's and the national impact of the career education concept, the 1970's have seen a flurry of writings and…
The Counseling & Guidance Curriculum.
ERIC Educational Resources Information Center
Ediger, Marlow
Counseling and guidance services are vital in any school curriculum. Counselors may themselves be dealing with students of diverse abilities and handicaps. Counselors may have to work with students affected by drug addiction, fetal alcohol syndrome, homelessness, poverty, Acquired Immune Deficiency Syndrome (AIDS) and divorce. Students may present…
PIV Logon Configuration Guidance
Lee, Glen Alan
2016-03-04
This document details the configurations and enhancements implemented to support the usage of federal Personal Identity Verification (PIV) Card for logon on unclassified networks. The guidance is a reference implementation of the configurations and enhancements deployed at the Los Alamos National Laboratory (LANL) by Network and Infrastructure Engineering – Core Services (NIE-CS).
ERIC Educational Resources Information Center
Plant, Peter
This paper examines quality issues in career guidance, counseling, and information services in Europe and elsewhere from a range of different perspectives related to economic, ethical, and/or effectiveness criteria. Selected examples from the European Union member states, Canada, and the United States are used to illustrate how quality is…
1994-05-01
The Office of Civilian Radioactive Waste Management (OCRWM) Program Management System Manual requires preparation of the OCRWM Regulatory Guidance Document (RGD) that addresses licensing, environmental compliance, and safety and health compliance. The document provides: regulatory compliance policy; guidance to OCRWM organizational elements to ensure a consistent approach when complying with regulatory requirements; strategies to achieve policy objectives; organizational responsibilities for regulatory compliance; guidance with regard to Program compliance oversight; and guidance on the contents of a project-level Regulatory Compliance Plan. The scope of the RGD includes site suitability evaluation, licensing, environmental compliance, and safety and health compliance, in accordance with the direction provided by Section 4.6.3 of the PMS Manual. Site suitability evaluation and regulatory compliance during site characterization are significant activities, particularly with regard to the YW MSA. OCRWM`s evaluation of whether the Yucca Mountain site is suitable for repository development must precede its submittal of a license application to the Nuclear Regulatory Commission (NRC). Accordingly, site suitability evaluation is discussed in Chapter 4, and the general statements of policy regarding site suitability evaluation are discussed in Section 2.1. Although much of the data and analyses may initially be similar, the licensing process is discussed separately in Chapter 5. Environmental compliance is discussed in Chapter 6. Safety and Health compliance is discussed in Chapter 7.
Vocational Development and Guidance.
ERIC Educational Resources Information Center
Tennyson, W. Wesley; And Others
The vocational education volume considers questions of career development, the role of guidance in the school, vocational training, the relation of self-concept to vocational choice, and occupational information. Twenty-six papers deal with theories of vocational behavior, the success of vocational education programs, and testing information.…
Discrete sequence prediction and its applications
NASA Technical Reports Server (NTRS)
Laird, Philip
1992-01-01
Learning from experience to predict sequences of discrete symbols is a fundamental problem in machine learning with many applications. We apply sequence prediction using a simple and practical sequence-prediction algorithm, called TDAG. The TDAG algorithm is first tested by comparing its performance with some common data compression algorithms. Then it is adapted to the detailed requirements of dynamic program optimization, with excellent results.
NASA Astrophysics Data System (ADS)
Klette, Reinhard; Jiang, Ruyi; Morales, Sandino; Vaudrey, Tobi
Applying computer technology, such as computer vision in driver assistance, implies that processes and data are modeled as being discretized rather than being continuous. The area of stereo vision provides various examples how concepts known in discrete mathematics (e.g., pixel adjacency graphs, belief propagation, dynamic programming, max-flow/min-cut, or digital straight lines) are applied when aiming for efficient and accurate pixel correspondence solutions. The paper reviews such developments for a reader in discrete mathematics who is interested in applied research (in particular, in vision-based driver assistance). As a second subject, the paper also discusses lane detection and tracking, which is a particular task in driver assistance; recently the Euclidean distance transform proved to be a very appropriate tool for obtaining a fairly robust solution.
Discrete breathers in crystals
NASA Astrophysics Data System (ADS)
Dmitriev, S. V.; Korznikova, E. A.; Baimova, Yu A.; Velarde, M. G.
2016-05-01
It is well known that periodic discrete defect-containing systems, in addition to traveling waves, support vibrational defect-localized modes. It turned out that if a periodic discrete system is nonlinear, it can support spatially localized vibrational modes as exact solutions even in the absence of defects. Since the nodes of the system are all on equal footing, it is only through the special choice of initial conditions that a group of nodes can be found on which such a mode, called a discrete breather (DB), will be excited. The DB frequency must be outside the frequency range of the small-amplitude traveling waves. Not resonating with and expending no energy on the excitation of traveling waves, a DB can theoretically conserve its vibrational energy forever provided no thermal vibrations or other perturbations are present. Crystals are nonlinear discrete systems, and the discovery in them of DBs was only a matter of time. It is well known that periodic discrete defect-containing systems support both traveling waves and vibrational defect-localized modes. It turns out that if a periodic discrete system is nonlinear, it can support spatially localized vibrational modes as exact solutions even in the absence of defects. Because the nodes of the system are all on equal footing, only a special choice of the initial conditions allows selecting a group of nodes on which such a mode, called a discrete breather (DB), can be excited. The DB frequency must be outside the frequency range of small-amplitude traveling waves. Not resonating with and expending no energy on the excitation of traveling waves, a DB can theoretically preserve its vibrational energy forever if no thermal vibrations or other perturbations are present. Crystals are nonlinear discrete systems, and the discovery of DBs in them was only a matter of time. Experimental studies of DBs encounter major technical difficulties, leaving atomistic computer simulations as the primary investigation tool. Despite
Vocational Guidance and Human Development.
ERIC Educational Resources Information Center
Herr, Edwin L., Ed.
New knowledge and practices in the area of vocational guidance and human growth and development that have occurred since 1964 as well as future directions for guidance, both nationally and internationally, are covered in this second volume of a decennial volume series sponsored by the National Vocational Guidance Association to up-date the…
When Instructional Guidance is Needed
ERIC Educational Resources Information Center
Chen, Ouhao; Kalyuga, Slava; Sweller, John
2016-01-01
Studying worked examples providing problem solutions to learners usually leads to better test performance than solving the equivalent problems without guidance, demonstrating the worked-example effect. The generation effect occurs when learners who generate answers without guidance learn better than those who read answers that provide guidance.…
Environmental guidance regulatory bulletin
1997-01-31
This document describes the background on expanding public participation in the Resource Conservation and Recovery Act and DOE`s response. The bulletin also describes the changes made by the final rule to existing regulations, guidance provided by EPA in the preamble and in the revised RCRA Public Participation Manual, the relationship between public participation and environmental justice, and DOE`s recent public participation and environmental justice initiatives.
Federal Register 2010, 2011, 2012, 2013, 2014
2013-09-13
... COMMISSION Interim Staff Guidance Specific Environmental Guidance for Integral Pressurized Water Reactors Reviews AGENCY: Nuclear Regulatory Commission. ACTION: Draft Interim Staff Guidance; request for comment... comment on, draft Interim Staff Guidance (ISG) ESP/COL-ISG-027, ``Interim Staff Guidance...
Shuttle ascent guidance and control.
NASA Technical Reports Server (NTRS)
Lovingood, J. A.; Blair, J. C.; Geissler, E. O.
1972-01-01
The requirements of a unified optimal guidance scheme are discussed, giving attention to a general formulation, aspects of self-targeting, problems of optimum guidance within the atmosphere, and a unified concept for all flight phases. Since no previous guidance scheme meets these requirements, the shuttle demands a fundamentally new approach. A new unified optimal guidance scheme, called Mascot, was developed. The capabilities of Mascot include the real-time solution of general trajectory-optimization problems and the unification of guidance for all flight phases.
Makris, Konstantinos G; Suntsov, Sergiy; Christodoulides, Demetrios N; Stegeman, George I; Hache, Alain
2005-09-15
It is theoretically shown that discrete nonlinear surface waves are possible in waveguide lattices. These self-trapped states are located at the edge of the array and can exist only above a certain power threshold. The excitation characteristics and stability properties of these surface waves are systematically investigated.
The effect of haptic guidance and visual feedback on learning a complex tennis task.
Marchal-Crespo, Laura; van Raai, Mark; Rauter, Georg; Wolf, Peter; Riener, Robert
2013-11-01
While haptic guidance can improve ongoing performance of a motor task, several studies have found that it ultimately impairs motor learning. However, some recent studies suggest that the haptic demonstration of optimal timing, rather than movement magnitude, enhances learning in subjects trained with haptic guidance. Timing of an action plays a crucial role in the proper accomplishment of many motor skills, such as hitting a moving object (discrete timing task) or learning a velocity profile (time-critical tracking task). The aim of the present study is to evaluate which feedback conditions-visual or haptic guidance-optimize learning of the discrete and continuous elements of a timing task. The experiment consisted in performing a fast tennis forehand stroke in a virtual environment. A tendon-based parallel robot connected to the end of a racket was used to apply haptic guidance during training. In two different experiments, we evaluated which feedback condition was more adequate for learning: (1) a time-dependent discrete task-learning to start a tennis stroke and (2) a tracking task-learning to follow a velocity profile. The effect that the task difficulty and subject's initial skill level have on the selection of the optimal training condition was further evaluated. Results showed that the training condition that maximizes learning of the discrete time-dependent motor task depends on the subjects' initial skill level. Haptic guidance was especially suitable for less-skilled subjects and in especially difficult discrete tasks, while visual feedback seems to benefit more skilled subjects. Additionally, haptic guidance seemed to promote learning in a time-critical tracking task, while visual feedback tended to deteriorate the performance independently of the task difficulty and subjects' initial skill level. Haptic guidance outperformed visual feedback, although additional studies are needed to further analyze the effect of other types of feedback visualization on
Mission-based guidance system design for autonomous UAVs
NASA Astrophysics Data System (ADS)
Moon, Jongki
The advantages of UAVs in the aviation arena have led to extensive research activities on autonomous technology of UAVs to achieve specific mission objectives. This thesis mainly focuses on the development of a mission-based guidance system. Among various missions expected for future needs, autonomous formation flight (AFF) and obstacle avoidance within safe operation limits are investigated. In the design of an adaptive guidance system for AFF, the leader information except position is assumed to be unknown to a follower. Thus, the only measured information related to the leader is the line-of-sight (LOS) range and angle. Adding an adaptive element with neural networks into the guidance system provides a capability to effectively handle leader's velocity changes. Therefore, this method can be applied to the AFF control systems that use a passive sensing method. In this thesis, an adaptive velocity command guidance system and an adaptive acceleration command guidance system are developed and presented. Since relative degrees of the LOS range and angle are different depending on the outputs from the guidance system, the architecture of the guidance system changes accordingly. Simulations and flight tests are performed using the Georgia Tech UAV helicopter, the GTMax, to evaluate the proposed guidance systems. The simulation results show that the neural network (NN) based adaptive element can improve the tracking performance by effectively compensating for the effect of unknown dynamics. It has also been shown that the combination of an adaptive velocity command guidance system and the existing GTMax autopilot controller performs better than the combination of an adaptive acceleration command guidance system and the GTMax autopilot controller. The successful flight evaluation using an adaptive velocity command guidance system clearly shows that the adaptive guidance control system is a promising solution for autonomous formation flight of UAVs. In addition, an
This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.
PSD Increment Consumption Guidance
This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.
NSR Program Transitional Guidance
This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.
Discrete Variational Optimal Control
NASA Astrophysics Data System (ADS)
Jiménez, Fernando; Kobilarov, Marin; Martín de Diego, David
2013-06-01
This paper develops numerical methods for optimal control of mechanical systems in the Lagrangian setting. It extends the theory of discrete mechanics to enable the solutions of optimal control problems through the discretization of variational principles. The key point is to solve the optimal control problem as a variational integrator of a specially constructed higher dimensional system. The developed framework applies to systems on tangent bundles, Lie groups, and underactuated and nonholonomic systems with symmetries, and can approximate either smooth or discontinuous control inputs. The resulting methods inherit the preservation properties of variational integrators and result in numerically robust and easily implementable algorithms. Several theoretical examples and a practical one, the control of an underwater vehicle, illustrate the application of the proposed approach.
NASA Technical Reports Server (NTRS)
Swei, Sean
2014-01-01
We propose to develop a robust guidance and control system for the ADEPT (Adaptable Deployable Entry and Placement Technology) entry vehicle. A control-centric model of ADEPT will be developed to quantify the performance of candidate guidance and control architectures for both aerocapture and precision landing missions. The evaluation will be based on recent breakthroughs in constrained controllability/reachability analysis of control systems and constrained-based energy-minimum trajectory optimization for guidance development operating in complex environments.
Steerable Discrete Fourier Transform
NASA Astrophysics Data System (ADS)
Fracastoro, Giulia; Magli, Enrico
2017-03-01
Directional transforms have recently raised a lot of interest thanks to their numerous applications in signal compression and analysis. In this letter, we introduce a generalization of the discrete Fourier transform, called steerable DFT (SDFT). Since the DFT is used in numerous fields, it may be of interest in a wide range of applications. Moreover, we also show that the SDFT is highly related to other well-known transforms, such as the Fourier sine and cosine transforms and the Hilbert transforms.
The Discrete Wavelet Transform
1991-06-01
Split- Band Coding," Proc. ICASSP, May 1977, pp 191-195. 12. Vetterli, M. "A Theory of Multirate Filter Banks ," IEEE Trans. ASSP, 35, March 1987, pp 356...both special cases of a single filter bank structure, the discrete wavelet transform, the behavior of which is governed by one’s choice of filters . In...B-1 ,.iii FIGURES 1.1 A wavelet filter bank structure ..................................... 2 2.1 Diagram illustrating the dialation and
Discrete minimal flavor violation
Zwicky, Roman; Fischbacher, Thomas
2009-10-01
We investigate the consequences of replacing the global flavor symmetry of minimal flavor violation (MFV) SU(3){sub Q}xSU(3){sub U}xSU(3){sub D}x{center_dot}{center_dot}{center_dot} by a discrete D{sub Q}xD{sub U}xD{sub D}x{center_dot}{center_dot}{center_dot} symmetry. Goldstone bosons resulting from the breaking of the flavor symmetry generically lead to bounds on new flavor structure many orders of magnitude above the TeV scale. The absence of Goldstone bosons for discrete symmetries constitute the primary motivation of our work. Less symmetry implies further invariants and renders the mass-flavor basis transformation observable in principle and calls for a hierarchy in the Yukawa matrix expansion. We show, through the dimension of the representations, that the (discrete) symmetry in principle does allow for additional {delta}F=2 operators. If though the {delta}F=2 transitions are generated by two subsequent {delta}F=1 processes, as, for example, in the standard model, then the four crystal-like groups {sigma}(168){approx_equal}PSL(2,F{sub 7}), {sigma}(72{phi}), {sigma}(216{phi}) and especially {sigma}(360{phi}) do provide enough protection for a TeV-scale discrete MFV scenario. Models where this is not the case have to be investigated case by case. Interestingly {sigma}(216{phi}) has a (nonfaithful) representation corresponding to an A{sub 4} symmetry. Moreover we argue that the, apparently often omitted, (D) groups are subgroups of an appropriate {delta}(6g{sup 2}). We would like to stress that we do not provide an actual model that realizes the MFV scenario nor any other theory of flavor.
Guidance Provided by Teacher and Simulation for Inquiry-Based Learning: a Case Study
NASA Astrophysics Data System (ADS)
Lehtinen, Antti; Viiri, Jouni
2016-12-01
Current research indicates that inquiry-based learning should be guided in order to achieve optimal learning outcomes. The need for guidance is even greater when simulations are used because of their high information content and the difficulty of extracting information from them. Previous research on guidance for learning with simulations has concentrated on guidance provided by the simulation. Little research has been done on the role of the teacher in guiding learners with inquiry-based activities using simulations. This descriptive study focuses on guidance provided during small group investigations; pre-service teachers (n = 8) guided third and fifth graders using a particular simulation. Data was collected using screen capture videos. The data was analyzed using a combination of theory- and data-driven analysis. Forms of guidance provided by the simulation and by the teachers were divided into the same categories. The distribution of the guidance between the teacher and the simulation was also analyzed. The categories for forms of guidance provided by simulations proved to be applicable to guidance provided by the teachers as well. Teachers offered more various forms of guidance than the simulation. The teachers adapted their guidance and used different patterns to complement the guidance provided by the simulation. The results of the study show that guidance provided by teachers and simulations have different affordances, and both should be present in the classroom for optimal support of learning. This has implications for both teaching with simulations and development of new simulations.
Guidance Provided by Teacher and Simulation for Inquiry-Based Learning: a Case Study
NASA Astrophysics Data System (ADS)
Lehtinen, Antti; Viiri, Jouni
2017-04-01
Current research indicates that inquiry-based learning should be guided in order to achieve optimal learning outcomes. The need for guidance is even greater when simulations are used because of their high information content and the difficulty of extracting information from them. Previous research on guidance for learning with simulations has concentrated on guidance provided by the simulation. Little research has been done on the role of the teacher in guiding learners with inquiry-based activities using simulations. This descriptive study focuses on guidance provided during small group investigations; pre-service teachers ( n = 8) guided third and fifth graders using a particular simulation. Data was collected using screen capture videos. The data was analyzed using a combination of theory- and data-driven analysis. Forms of guidance provided by the simulation and by the teachers were divided into the same categories. The distribution of the guidance between the teacher and the simulation was also analyzed. The categories for forms of guidance provided by simulations proved to be applicable to guidance provided by the teachers as well. Teachers offered more various forms of guidance than the simulation. The teachers adapted their guidance and used different patterns to complement the guidance provided by the simulation. The results of the study show that guidance provided by teachers and simulations have different affordances, and both should be present in the classroom for optimal support of learning. This has implications for both teaching with simulations and development of new simulations.
A paradigm for discrete physics
Noyes, H.P.; McGoveran, D.; Etter, T.; Manthey, M.J.; Gefwert, C.
1987-01-01
An example is outlined for constructing a discrete physics using as a starting point the insight from quantum physics that events are discrete, indivisible and non-local. Initial postulates are finiteness, discreteness, finite computability, absolute nonuniqueness (i.e., homogeneity in the absence of specific cause) and additivity.
Discretization of the Schwarzian derivative
NASA Astrophysics Data System (ADS)
Itoh, Toshiaki
2016-10-01
Numerical treatment of the Schwarzian derivatives from the exact discretization point is useful for many applications. Since we found the discrete counterpart of Schwarzian derivative is the Cross-ratio, we can regard the Cross-ratio to the discrete conformal mapping function instead of the Schwarzian derivative. By this approach we found some integrable system of special functions are derived by the classical treatment of 2nd order ODE and difference equations. Such discrete integrable system is composed of simultameous equation of the two Möbius transformations or discrete Riccati's eqautions.
Multiple Autonomous Discrete Event Controllers for Constellations
NASA Technical Reports Server (NTRS)
Esposito, Timothy C.
2003-01-01
The Multiple Autonomous Discrete Event Controllers for Constellations (MADECC) project is an effort within the National Aeronautics and Space Administration Goddard Space Flight Center's (NASA/GSFC) Information Systems Division to develop autonomous positioning and attitude control for constellation satellites. It will be accomplished using traditional control theory and advanced coordination algorithms developed by the Johns Hopkins University Applied Physics Laboratory (JHU/APL). This capability will be demonstrated in the discrete event control test-bed located at JHU/APL. This project will be modeled for the Leonardo constellation mission, but is intended to be adaptable to any constellation mission. To develop a common software architecture. the controllers will only model very high-level responses. For instance, after determining that a maneuver must be made. the MADECC system will output B (Delta)V (velocity change) value. Lower level systems must then decide which thrusters to fire and for how long to achieve that (Delta)V.
Semi-Discrete Ingham-Type Inequalities
Komornik, Vilmos Loreti, Paola
2007-03-15
One of the general methods in linear control theory is based on harmonic and non-harmonic Fourier series. The key of this approach is the establishment of various suitable adaptations and generalizations of the classical Parseval equality. A new and systematic approach was begun in our papers in collaboration with Baiocchi. Many recent results of this kind, obtained through various Ingham-type theorems, were exposed recently. Although this work concentrated on continuous models, in connection with numerical simulations a natural question is whether these results also admit useful discrete versions. The purpose of this paper is to establish discrete versions of various Ingham-type theorems by using our approach. They imply the earlier continuous results by a simple limit process.
Comprehensive Career Guidance. Career Guidance Curriculum. Staff Development K-6.
ERIC Educational Resources Information Center
Straub, Vicki W.; Moore, Earl J.
One of six staff development training manuals for career guidance infusion in the elementary school curriculum (K-6), this manual focuses on the curriculum design of a comprehensive career guidance program. It is divided into the following five major sections: (1) a list of the major goals and activities covered in the manual; (2) an overview…
Endangerment assessment guidance
Not Available
1985-11-22
The directive clarifies the requirement that an endangerment assessment be developed to support all administrative and judicial enforcement actions under Section 106 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Section 7003 of the Resource Conservation and Recovery Act (RCRA). Before taking enforcement action under these provisions to abate the hazards or potential hazards at a site, the Environmental Protection Agency (EPA) must be able to properly document and justify its assertion that an imminent and substantial endangerment to public health or welfare or the environment may exist. The endangerment assessment provides this documentation and justification. The endangerment assessment is not necessary to support Section 104 actions. It also provides guidance on the content, timing, level of detail, format, and resources required for the preparation of endangerment assessments.
Discrete range clustering using Monte Carlo methods
NASA Technical Reports Server (NTRS)
Chatterji, G. B.; Sridhar, B.
1993-01-01
For automatic obstacle avoidance guidance during rotorcraft low altitude flight, a reliable model of the nearby environment is needed. Such a model may be constructed by applying surface fitting techniques to the dense range map obtained by active sensing using radars. However, for covertness, passive sensing techniques using electro-optic sensors are desirable. As opposed to the dense range map obtained via active sensing, passive sensing algorithms produce reliable range at sparse locations, and therefore, surface fitting techniques to fill the gaps in the range measurement are not directly applicable. Both for automatic guidance and as a display for aiding the pilot, these discrete ranges need to be grouped into sets which correspond to objects in the nearby environment. The focus of this paper is on using Monte Carlo methods for clustering range points into meaningful groups. One of the aims of the paper is to explore whether simulated annealing methods offer significant advantage over the basic Monte Carlo method for this class of problems. We compare three different approaches and present application results of these algorithms to a laboratory image sequence and a helicopter flight sequence.
MULTISCALE DISCRETIZATION OF SHAPE CONTOURS
Prasad, L.; Rao, R.
2000-09-01
We present an efficient multi-scale scheme to adaptively approximate the continuous (or densely sampled) contour of a planar shape at varying resolutions. The notion of shape is intimately related to the notion of contour, and the efficient representation of the contour of a shape is vital to a computational understanding of the shape. Any polygonal approximation of a planar smooth curve is equivalent to a piecewise constant approximation of the parameterized X and Y coordinate functions of a discrete point set obtained by densely sampling the curve. Using the Haar wavelet transform for the piecewise approximation yields a hierarchical scheme in which the size of the approximating point set is traded off against the morphological accuracy of the approximation. Our algorithm compresses the representation of the initial shape contour to a sparse sequence of points in the plane defining the vertices of the shape's polygonal approximation. Furthermore, it is possible to control the overall resolution of the approximation by a single, scale-independent parameter.
Guidance for the New Millenium?
ERIC Educational Resources Information Center
McLaren, David J.
1996-01-01
Reviews the "Guidance Arrangements" consultation document issued with "Higher Still" (proposed new Scottish upper secondary curricula). Argues that the paper ignores the full implications for educational change in Higher Still and misses the opportunity for timely modernization of school guidance. Advocates a cross-curricular…
Guidance in the Secondary School
ERIC Educational Resources Information Center
Kumar, V. Jurist Lional
2010-01-01
Secondary School Students face a lot of problems in their body as well as in mind due to puberty that tends to adolescence stage. Adolescence has peculiar characters of their own. They need proper Guidance and Counselling to tackle their own problems. Guidance is described as a counselling service to assist the individual in achieving self…
Restructuring Guidance and Counseling Programs.
ERIC Educational Resources Information Center
Snyder, Beverly A.; Daly, Timothy P.
1993-01-01
Briefly reviews counseling profession's call for revitalization and transformation in school counseling and guidance programs. Summarizes one school system's efforts during late 1980s and early 1990s to transform its program from services and crisis orientation into a comprehensive developmental model based on Myrick's developmental guidance and…
Guidance Services in Spanish Universities
ERIC Educational Resources Information Center
Vidal, Javier; Diez, Gloria; Vieira, Maria J.
2003-01-01
Since the 80s, higher education in Spain has undergone important modifications such as greater autonomy, expansion in the number of students and the introduction of more flexible programmes. In this context, guidance services have proliferated in an unstructured way. This paper presents a description of guidance services in Spanish universities…
Final OSWER Vapor Intrusion Guidance
EPA is preparing to finalize its guidance on assessing and addressing vapor intrusion, which is defined as migration of volatile constituents from contaminated media in the subsurface (soil or groundwater) into the indoor environment. In November 2002, EPA issued draft guidance o...
Marxist Guidance: A Dialectic Lesson
ERIC Educational Resources Information Center
Drapela, Victor J.
1971-01-01
Based on primary sources published in the Soviet Bloc, this article compares the stated goals of Marxist guidance with actual outcomes, and identifies the foundations of guidance in the Soviet Bloc in terms of Marxist philosophy and social doctrine. Current symptoms of ideological unrest in socialist society as exemplified by the suppressed reform…
Automated Guidance for Student Inquiry
ERIC Educational Resources Information Center
Gerard, Libby F.; Ryoo, Kihyun; McElhaney, Kevin W.; Liu, Ou Lydia; Rafferty, Anna N.; Linn, Marcia C.
2016-01-01
In 4 classroom experiments we investigated uses for technologies that automatically score student generated essays, concept diagrams, and drawings in inquiry curricula. We used the automatic scores to assign typical and research-based guidance and studied the impact of the guidance on student progress. Seven teachers and their 897 students…
Discussing Diverse Perspectives on Guidance
ERIC Educational Resources Information Center
Gonzalez-Mena, Janet; Shareef, Intisar
2005-01-01
Ideas about discipline and guidance get extremely complex when they intersect with culture and oppression. Some groups of people who are targets of racism have to protect their children from the oppressive practices of racist individuals and institutions. Their methods of guidance and discipline may be different from those of groups for whom…
Ascent Guidance for a Winged Boost Vehicle. M.S. Thesis
NASA Technical Reports Server (NTRS)
Corvin, Michael Alexander
1988-01-01
The objective of the advanced ascent guidance study was to investigate guidance concepts which could contribute to increased autonomy during ascent operations in a winged boost vehicle such as the proposed Shuttle II. The guidance scheme was required to yield near a full-optimal ascent in the presence of vehicle system and environmental dispersions. The study included consideration of trajectory shaping issues, trajectory design, closed loop and predictive adaptive guidance techniques and control of dynamic pressure by throttling. An extensive ascent vehicle simulation capability was developed for use in the study.
Washington TRU Solutions LLC
2008-01-12
The purpose of this program guidance document is to provide the technical requirements for use, operation, inspection, and maintenance of the RH-TRU 72-B Waste Shipping Package (also known as the "RH-TRU 72-B cask") and directly related components. This document complies with the requirements as specified in the RH-TRU 72-B Safety Analysis Report for Packaging (SARP), and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9212. If there is a conflict between this document and the SARP and/or C of C, the C of C shall govern. The C of C states: "...each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, Operating Procedures, of the application." It further states: "...each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, Acceptance Tests and Maintenance Program of the Application." Chapter 9.0 of the SARP tasks the Waste Isolation Pilot Plant (WIPP) Management and Operating (M&O) Contractor with assuring the packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC-approved, users need to be familiar with Title 10 Code of Federal Regulations (CFR) §71.8, "Deliberate Misconduct." Any time a user suspects or has indications that the conditions of approval in the C of C were not met, the U.S. Department of Energy (DOE) Carlsbad Field Office (CBFO) shall be notified immediately. The CBFO will evaluate the issue and notify the NRC if required.In accordance with 10 CFR Part 71, "Packaging and Transportation of Radioactive Material," certificate holders, packaging users, and contractors or subcontractors who use, design, fabricate, test, maintain, or modify the packaging shall post copies of (1) 10 CFR Part 21, "Reporting of Defects and Noncompliance," regulations, (2) Section 206 of the Energy Reorganization Act of 1974, and (3) NRC Form 3, Notice to Employees. These documents must be posted in a
Fast and Accurate Learning When Making Discrete Numerical Estimates
Sanborn, Adam N.; Beierholm, Ulrik R.
2016-01-01
Many everyday estimation tasks have an inherently discrete nature, whether the task is counting objects (e.g., a number of paint buckets) or estimating discretized continuous variables (e.g., the number of paint buckets needed to paint a room). While Bayesian inference is often used for modeling estimates made along continuous scales, discrete numerical estimates have not received as much attention, despite their common everyday occurrence. Using two tasks, a numerosity task and an area estimation task, we invoke Bayesian decision theory to characterize how people learn discrete numerical distributions and make numerical estimates. Across three experiments with novel stimulus distributions we found that participants fell between two common decision functions for converting their uncertain representation into a response: drawing a sample from their posterior distribution and taking the maximum of their posterior distribution. While this was consistent with the decision function found in previous work using continuous estimation tasks, surprisingly the prior distributions learned by participants in our experiments were much more adaptive: When making continuous estimates, participants have required thousands of trials to learn bimodal priors, but in our tasks participants learned discrete bimodal and even discrete quadrimodal priors within a few hundred trials. This makes discrete numerical estimation tasks good testbeds for investigating how people learn and make estimates. PMID:27070155
Manpower Analysis Using Discrete Simulation
2015-12-01
building using Discrete Event Simulation (DES) and experimentation using Design of Experiments (DOE). We derived five metamodels to identify the most...objectives were met. 14. SUBJECT TERMS manpower policy analysis, discrete event simulation, Simkit 15. NUMBER OF PAGES 85 16. PRICE CODE 17. SECURITY...using Discrete Event Simulation (DES) and experimentation using Design of Experiments (DOE). We derived five metamodels to identify the most
Integrable discrete PT symmetric model.
Ablowitz, Mark J; Musslimani, Ziad H
2014-09-01
An exactly solvable discrete PT invariant nonlinear Schrödinger-like model is introduced. It is an integrable Hamiltonian system that exhibits a nontrivial nonlinear PT symmetry. A discrete one-soliton solution is constructed using a left-right Riemann-Hilbert formulation. It is shown that this pure soliton exhibits unique features such as power oscillations and singularity formation. The proposed model can be viewed as a discretization of a recently obtained integrable nonlocal nonlinear Schrödinger equation.
Autonomous landing guidance program
NASA Astrophysics Data System (ADS)
Brown, John A.
1996-05-01
The Autonomous Landing Guidance program is partly funded by the US Government under the Technology Reinvestment Project. The program consortium consists of avionics and other equipment vendors, airlines and the USAF. A Sextant Avionique HUD is used to present flight symbology in cursive form as well as millimeter wave radar imagery from Lear Astronics equipment and FLIR Systems dual-channel, forward-looking, infrared imagery. All sensor imagery is presented in raster form. A future aim is to fuse all imagery data into a single presentation. Sensor testing has been accomplished in a Cessna 402 operated by the Maryland Advanced Development Laboratory. Development testing is under way in a Northwest Airlines simulator equipped with HUD and image simulation. Testing is also being carried out using United Airlines Boeing 727 and USAF C-135C (Boeing 707) test aircraft. The paper addresses the technology utilized in sensory and display systems as well as modifications made to accommodate the elements in the aircraft. Additions to the system test aircraft include global positioning systems, inertial navigation systems and extensive data collection equipment. Operational philosophy and benefits for both civil and military users are apparent. Approach procedures have been developed allowing use of Category 1 ground installations in Category 3 conditions.
Exploring Discretization Error in Simulation-Based Aerodynamic Databases
NASA Technical Reports Server (NTRS)
Aftosmis, Michael J.; Nemec, Marian
2010-01-01
This work examines the level of discretization error in simulation-based aerodynamic databases and introduces strategies for error control. Simulations are performed using a parallel, multi-level Euler solver on embedded-boundary Cartesian meshes. Discretization errors in user-selected outputs are estimated using the method of adjoint-weighted residuals and we use adaptive mesh refinement to reduce these errors to specified tolerances. Using this framework, we examine the behavior of discretization error throughout a token database computed for a NACA 0012 airfoil consisting of 120 cases. We compare the cost and accuracy of two approaches for aerodynamic database generation. In the first approach, mesh adaptation is used to compute all cases in the database to a prescribed level of accuracy. The second approach conducts all simulations using the same computational mesh without adaptation. We quantitatively assess the error landscape and computational costs in both databases. This investigation highlights sensitivities of the database under a variety of conditions. The presence of transonic shocks or the stiffness in the governing equations near the incompressible limit are shown to dramatically increase discretization error requiring additional mesh resolution to control. Results show that such pathologies lead to error levels that vary by over factor of 40 when using a fixed mesh throughout the database. Alternatively, controlling this sensitivity through mesh adaptation leads to mesh sizes which span two orders of magnitude. We propose strategies to minimize simulation cost in sensitive regions and discuss the role of error-estimation in database quality.
Enzymic determination of plasma cholesterol on discrete automatic analysers.
Nobbs, B T; Smith, J M; Walker, A W
1977-09-01
Enzymic procedures for the determination of plasma cholesterol, using cholesterol esterase and cholesterol oxidase, have been adapted to the Vickers D-300, Vickers M,-300, and Vitatron AKES discrete analysers. The results obtained by these methods have been compared to those obtained by manual and continuous flow Liebermann-Burchard methods. The enzymic methods were found to be accurate, precise and of adequate sensitivity.
Thermodynamics of discrete quantum processes
NASA Astrophysics Data System (ADS)
Anders, Janet; Giovannetti, Vittorio
2013-03-01
We define thermodynamic configurations and identify two primitives of discrete quantum processes between configurations for which heat and work can be defined in a natural way. This allows us to uncover a general second law for any discrete trajectory that consists of a sequence of these primitives, linking both equilibrium and non-equilibrium configurations. Moreover, in the limit of a discrete trajectory that passes through an infinite number of configurations, i.e. in the reversible limit, we recover the saturation of the second law. Finally, we show that for a discrete Carnot cycle operating between four configurations one recovers Carnot's thermal efficiency.
Discrete Pearson distributions
Bowman, K.O.; Shenton, L.R.; Kastenbaum, M.A.
1991-11-01
These distributions are generated by a first order recursive scheme which equates the ratio of successive probabilities to the ratio of two corresponding quadratics. The use of a linearized form of this model will produce equations in the unknowns matched by an appropriate set of moments (assumed to exist). Given the moments we may find valid solutions. These are two cases; (1) distributions defined on the non-negative integers (finite or infinite) and (2) distributions defined on negative integers as well. For (1), given the first four moments, it is possible to set this up as equations of finite or infinite degree in the probability of a zero occurrence, the sth component being a product of s ratios of linear forms in this probability in general. For (2) the equation for the zero probability is purely linear but may involve slowly converging series; here a particular case is the discrete normal. Regions of validity are being studied. 11 refs.
Discrete bisoliton fiber laser
Liu, X. M.; Han, X. X.; Yao, X. K.
2016-01-01
Dissipative solitons, which result from the intricate balance between dispersion and nonlinearity as well as gain and loss, are of the fundamental scientific interest and numerous important applications. Here, we report a fiber laser that generates bisoliton – two consecutive dissipative solitons that preserve a fixed separation between them. Deviations from this separation result in its restoration. It is also found that these bisolitons have multiple discrete equilibrium distances with the quantized separations, as is confirmed by the theoretical analysis and the experimental observations. The main feature of our laser is the anomalous dispersion that is increased by an order of magnitude in comparison to previous studies. Then the spectral filtering effect plays a significant role in pulse-shaping. The proposed laser has the potential applications in optical communications and high-resolution optics for coding and transmission of information in higher-level modulation formats. PMID:27767075
Discrete Reliability Projection
2014-12-01
Defense, Handbook MIL - HDBK -189C, 2011 Hall, J. B., Methodology for Evaluating Reliability Growth Programs of Discrete Systems, Ph.D. thesis, University...pk,i ] · [ 1− (1− θ̆k) · ( N k · T )]k−m , (2.13) 5 2 Hall’s Model where m is the number of observed failure modes and d∗i estimates di (either based...Mode Failures FEF Ni d ∗ i 1 1 0.95 2 1 0.70 3 1 0.90 4 1 0.90 5 4 0.95 6 2 0.70 7 1 0.80 Using equations 2.1 and 2.2 we can calculate the failure
Noyes, H.P. ); Starson, S. )
1991-03-01
Discrete physics, because it replaces time evolution generated by the energy operator with a global bit-string generator (program universe) and replaces fields'' with the relativistic Wheeler-Feynman action at a distance,'' allows the consistent formulation of the concept of signed gravitational charge for massive particles. The resulting prediction made by this version of the theory is that free anti-particles near the surface of the earth will fall'' up with the same acceleration that the corresponding particles fall down. So far as we can see, no current experimental information is in conflict with this prediction of our theory. The experiment crusis will be one of the anti-proton or anti-hydrogen experiments at CERN. Our prediction should be much easier to test than the small effects which those experiments are currently designed to detect or bound. 23 refs.
NASA Astrophysics Data System (ADS)
Noyes, H. Pierre; Starson, Scott
1991-03-01
Discrete physics, because it replaces time evolution generated by the energy operator with a global bit-string generator (program universe) and replaces fields with the relativistic Wheeler-Feynman action at a distance, allows the consistent formulation of the concept of signed gravitational charge for massive particles. The resulting prediction made by this version of the theory is that free anti-particles near the surface of the earth will fall up with the same acceleration that the corresponding particles fall down. So far as we can see, no current experimental information is in conflict with this prediction of our theory. The experiment crusis will be one of the anti-proton or anti-hydrogen experiments at CERN. Our prediction should be much easier to test than the small effects which those experiments are currently designed to detect or bound.
Discrete bisoliton fiber laser
NASA Astrophysics Data System (ADS)
Liu, X. M.; Han, X. X.; Yao, X. K.
2016-10-01
Dissipative solitons, which result from the intricate balance between dispersion and nonlinearity as well as gain and loss, are of the fundamental scientific interest and numerous important applications. Here, we report a fiber laser that generates bisoliton – two consecutive dissipative solitons that preserve a fixed separation between them. Deviations from this separation result in its restoration. It is also found that these bisolitons have multiple discrete equilibrium distances with the quantized separations, as is confirmed by the theoretical analysis and the experimental observations. The main feature of our laser is the anomalous dispersion that is increased by an order of magnitude in comparison to previous studies. Then the spectral filtering effect plays a significant role in pulse-shaping. The proposed laser has the potential applications in optical communications and high-resolution optics for coding and transmission of information in higher-level modulation formats.
Immigration and Prosecutorial Discretion.
Apollonio, Dorie; Lochner, Todd; Heddens, Myriah
Immigration has become an increasingly salient national issue in the US, and the Department of Justice recently increased federal efforts to prosecute immigration offenses. This shift, however, relies on the cooperation of US attorneys and their assistants. Traditionally federal prosecutors have enjoyed enormous discretion and have been responsive to local concerns. To consider how the centralized goal of immigration enforcement may have influenced federal prosecutors in regional offices, we review their prosecution of immigration offenses in California using over a decade's worth of data. Our findings suggest that although centralizing forces influence immigration prosecutions, individual US attorneys' offices retain distinct characteristics. Local factors influence federal prosecutors' behavior in different ways depending on the office. Contrary to expectations, unemployment rates did not affect prosecutors' willingness to pursue immigration offenses, nor did local popular opinion about illegal immigration.
Steerable Discrete Cosine Transform
NASA Astrophysics Data System (ADS)
Fracastoro, Giulia; Fosson, Sophie M.; Magli, Enrico
2017-01-01
In image compression, classical block-based separable transforms tend to be inefficient when image blocks contain arbitrarily shaped discontinuities. For this reason, transforms incorporating directional information are an appealing alternative. In this paper, we propose a new approach to this problem, namely a discrete cosine transform (DCT) that can be steered in any chosen direction. Such transform, called steerable DCT (SDCT), allows to rotate in a flexible way pairs of basis vectors, and enables precise matching of directionality in each image block, achieving improved coding efficiency. The optimal rotation angles for SDCT can be represented as solution of a suitable rate-distortion (RD) problem. We propose iterative methods to search such solution, and we develop a fully fledged image encoder to practically compare our techniques with other competing transforms. Analytical and numerical results prove that SDCT outperforms both DCT and state-of-the-art directional transforms.
Steerable Discrete Cosine Transform.
Fracastoro, Giulia; Fosson, Sophie M; Magli, Enrico
2017-01-01
In image compression, classical block-based separable transforms tend to be inefficient when image blocks contain arbitrarily shaped discontinuities. For this reason, transforms incorporating directional information are an appealing alternative. In this paper, we propose a new approach to this problem, namely, a discrete cosine transform (DCT) that can be steered in any chosen direction. Such transform, called steerable DCT (SDCT), allows to rotate in a flexible way pairs of basis vectors, and enables precise matching of directionality in each image block, achieving improved coding efficiency. The optimal rotation angles for SDCT can be represented as solution of a suitable rate-distortion (RD) problem. We propose iterative methods to search such solution, and we develop a fully fledged image encoder to practically compare our techniques with other competing transforms. Analytical and numerical results prove that SDCT outperforms both DCT and state-of-the-art directional transforms.
Nonintegrable Schrodinger discrete breathers.
Gómez-Gardeñes, J; Floría, L M; Peyrard, M; Bishop, A R
2004-12-01
In an extensive numerical investigation of nonintegrable translational motion of discrete breathers in nonlinear Schrödinger lattices, we have used a regularized Newton algorithm to continue these solutions from the limit of the integrable Ablowitz-Ladik lattice. These solutions are shown to be a superposition of a localized moving core and an excited extended state (background) to which the localized moving pulse is spatially asymptotic. The background is a linear combination of small amplitude nonlinear resonant plane waves and it plays an essential role in the energy balance governing the translational motion of the localized core. Perturbative collective variable theory predictions are critically analyzed in the light of the numerical results.
Immigration and Prosecutorial Discretion
Apollonio, Dorie; Lochner, Todd; Heddens, Myriah
2015-01-01
Immigration has become an increasingly salient national issue in the US, and the Department of Justice recently increased federal efforts to prosecute immigration offenses. This shift, however, relies on the cooperation of US attorneys and their assistants. Traditionally federal prosecutors have enjoyed enormous discretion and have been responsive to local concerns. To consider how the centralized goal of immigration enforcement may have influenced federal prosecutors in regional offices, we review their prosecution of immigration offenses in California using over a decade's worth of data. Our findings suggest that although centralizing forces influence immigration prosecutions, individual US attorneys' offices retain distinct characteristics. Local factors influence federal prosecutors' behavior in different ways depending on the office. Contrary to expectations, unemployment rates did not affect prosecutors' willingness to pursue immigration offenses, nor did local popular opinion about illegal immigration. PMID:26146530
Discrete Minimal Surface Algebras
NASA Astrophysics Data System (ADS)
Arnlind, Joakim; Hoppe, Jens
2010-05-01
We consider discrete minimal surface algebras (DMSA) as generalized noncommutative analogues of minimal surfaces in higher dimensional spheres. These algebras appear naturally in membrane theory, where sequences of their representations are used as a regularization. After showing that the defining relations of the algebra are consistent, and that one can compute a basis of the enveloping algebra, we give several explicit examples of DMSAs in terms of subsets of sln (any semi-simple Lie algebra providing a trivial example by itself). A special class of DMSAs are Yang-Mills algebras. The representation graph is introduced to study representations of DMSAs of dimension d ≤ 4, and properties of representations are related to properties of graphs. The representation graph of a tensor product is (generically) the Cartesian product of the corresponding graphs. We provide explicit examples of irreducible representations and, for coinciding eigenvalues, classify all the unitary representations of the corresponding algebras.
Pandemic influenza guidance for corporations.
2011-06-01
The purpose of this guidance document is to assist members of the American College of Occupational and Environmental Medicine (ACOEM), and the organizations for which they work, in managing the impact of a pandemic of influenza or other contagious respiratory disease on patients, employees, and business. This guidance document outlines actions to take before and during an influenza pandemic on the basis of two main strategies: (1) reducing the spread of the virus within facilities; and (2) providing medical care and medical surveillance to client/patient populations. Facilities in which ACOEM members serve include government agencies and the military, universities, and corporations, which generally have multiple locations/sites and their own medical staff, with members responsible for medical care and disease control. This guidance is for organizations with outpatient occupational medicine services, to be used as appropriate. Medical centers should also use guidance that addresses additional employee and external patient care needs.1–3 The ACOEM fully supports implementation of occupational influenza programs that conform with guidance from the Centers for Disease Control and Prevention (CDC), with other guidance from the US Department of Health and Human Services (DHHS), and Occupational Safety and Health Administration (OSHA) regulations and guidance.
General RMP Guidance - Appendix D: OSHA Guidance on PSM
OSHA's Process Safety Management (PSM) Guidance on providing complete and accurate written information concerning process chemicals, process technology, and process equipment; including process hazard analysis and material safety data sheets.
In Respect to the Cognitive Load Theory: Adjusting Instructional Guidance with Student Expertise.
Schilling, Jim
2017-01-01
The amount of guidance supplied by educators to students in allied health programs is a factor in student learning. According to the cognitive load theory of learning, without adequate instructional support, novice learners will be overwhelmed and unable to store information, while unnecessary guidance supplied to advanced students will cause extraneous cognitive load on the working memory system. Adjusting instructional guidance for students according to their level of expertise to minimize extraneous cognitive load and optimize working memory storage capacity will enhance learning effectiveness. Novice students presented with complex subject matter require significant guidance during the initial stages, using strategies such as worked examples. As students comprehend information, instructional guidance needs to gradually fade to avoid elevated extraneous cognitive load from the expertise reversal effect. An instructional strategy that utilizes a systemic (fixed) or adjustable (adaptive) tapering of guidance to students in allied health programs depending on their expertise will optimize learning capability.
Uprated fine guidance sensor study
NASA Technical Reports Server (NTRS)
1984-01-01
Future orbital observatories will require star trackers of extremely high precision. These sensors must maintain high pointing accuracy and pointing stability simultaneously with a low light level signal from a guide star. To establish the fine guidance sensing requirements and to evaluate candidate fine guidance sensing concepts, the Space Telescope Optical Telescope Assembly was used as the reference optical system. The requirements review was separated into three areas: Optical Telescope Assembly (OTA), Fine Guidance Sensing and astrometry. The results show that the detectors should be installed directly onto the focal surface presented by the optics. This would maximize throughput and minimize point stability error by not incoporating any additional optical elements.
Adaptive control of linearizable systems
NASA Technical Reports Server (NTRS)
Sastry, S. Shankar; Isidori, Alberto
1989-01-01
Initial results are reported regarding the adaptive control of minimum-phase nonlinear systems which are exactly input-output linearizable by state feedback. Parameter adaptation is used as a technique to make robust the exact cancellation of nonlinear terms, which is called for in the linearization technique. The application of the adaptive technique to control of robot manipulators is discussed. Only the continuous-time case is considered; extensions to the discrete-time and sampled-data cases are not obvious.
Washington TRU Solutions, LLC
2003-08-25
The purpose of this program guidance document is to provide technical requirements for use, operation, inspection, and maintenance of the RH-TRU 72-B Waste Shipping Package and directly related components. This document complies with the requirements as specified in the RH-TRU 72-B Safety Analysis Report for Packaging (SARP), and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9212. If there is a conflict between this document and the SARP and/or C of C, the SARP and/or C of C shall govern. The C of C states: ''...each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, ''Operating Procedures,'' of the application.'' It further states: ''...each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, ''Acceptance Tests and Maintenance Program of the Application.'' Chapter 9.0 of the SARP tasks the Waste Isolation Pilot Plant (WIPP) Management and Operating (M&O) contractor with assuring the packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC approved, users need to be familiar with 10 CFR {section} 71.11, ''Deliberate Misconduct.'' Any time a user suspects or has indications that the conditions of approval in the C of C were not met, the Carlsbad Field Office (CBFO) shall be notified immediately. CBFO will evaluate the issue and notify the NRC if required. This document details the instructions to be followed to operate, maintain, and test the RH-TRU 72-B packaging. This Program Guidance standardizes instructions for all users. Users shall follow these instructions. Following these instructions assures that operations are safe and meet the requirements of the SARP. This document is available on the Internet at: ttp://www.ws/library/t2omi/t2omi.htm. Users are responsible for ensuring they are using the current revision and change notices. Sites may prepare their own document using the word
SPLC Sustainable Purchasing Guidance Profile
To help you find the resource that is right for your organization, EPA conducted a scan of the landscape and developed summary profiles of some of the leading sources of sustainable purchasing guidance around the globe.
Guidance Documents for Marine Fuel
The following guidance documents apply to marine fuel used in ocean-going vessels. All vessels that operate in the North American Emission Control Area (ECA) must generally use fuel with 1,000 ppm sulfur or less.
Chesapeake Bay Program Grant Guidance
Grant Guidance and appendices for the Chesapeake Bay Program that describes how the U.S. Environmental Protection Agency’s (EPA) Region 3’s Chesapeake Bay Program Office (CBPO) administers grant and cooperative agreement funds.
Inert Ingredients Overview and Guidance
This Web page provides information on inert ingredients approved for use in pesticide products and the guidance documents that are available to assist in obtaining approval for a new inert ingredient.
Enforcement Response Policies and Guidance
EPA's Enforcement Response Policies relating to violations or noncompliance with the environmental statutes and regulations. The listing is not inclusive of all policy and guidance that may be relied upon in developing enforcement actions.
BASINS User Information and Guidance
This page provides links to guidance on how to use BASINS, including the User’s Manual, tutorials and training, technical notes, case studies, and publications that highlight the use of BASINS in various watershed analyses.
Guidance for identifying, reporting and tracking nuclear safety noncompliances
1995-12-01
This document provides Department of Energy (DOE) contractors, subcontractors and suppliers with guidance in the effective use of DOE`s Price-Anderson nuclear safety Noncompliance Tracking System (NTS). Prompt contractor identification, reporting to DOE, and correction of nuclear safety noncompliances provides DOE with a basis to exercise enforcement discretion to mitigate civil penalties, and suspend the issuance of Notices of Violation for certain violations. Use of this reporting methodology is elective by contractors; however, this methodology is intended to reflect DOE`s philosophy on effective identification and reporting of nuclear safety noncompliances. To the extent that these expectations are met for particular noncompliances, DOE intends to appropriately exercise its enforcement discretion in considering whether, and to what extent, to undertake enforcement action.
Discrete Mathematics and Its Applications
ERIC Educational Resources Information Center
Oxley, Alan
2010-01-01
The article gives ideas that lecturers of undergraduate Discrete Mathematics courses can use in order to make the subject more interesting for students and encourage them to undertake further studies in the subject. It is possible to teach Discrete Mathematics with little or no reference to computing. However, students are more likely to be…
NASA Technical Reports Server (NTRS)
1986-01-01
This false-color Voyager picture of Uranus shows a discrete cloud seen as a bright streak near the planet's limb. The picture is a highly processed composite of three images obtained Jan. 14, 1986, when the spacecraft was 12.9 million kilometers (8.0 million miles) from the planet. The cloud visible here is the most prominent feature seen in a series of Voyager images designed to track atmospheric motions. (The occasional donut-shaped features, including one at the bottom, are shadows cast by dust in the camera optics; the processing necessary to bring out the faint features on the planet also brings out these camera blemishes.) Three separate images were shuttered through violet, blue and orange filters. Each color image showed the cloud to a different degree; because they were not exposed at exactly the same time, the images were processed to provide a correction for a good spatial match. In a true-color image, the cloud would be barely discernible; the false color helps bring out additional details. The different colors imply variations in vertical structure, but as yet is not possible to be specific about such differences. One possibility is that the Uranian atmosphere contains smog-like constituents, in which case some color differences may represent differences in how these molecules are distributed. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.
Discreteness inducing coexistence
NASA Astrophysics Data System (ADS)
dos Santos, Renato Vieira
2013-12-01
Consider two species that diffuse through space. Consider further that they differ only in initial densities and, possibly, in diffusion constants. Otherwise they are identical. What happens if they compete with each other in the same environment? What is the influence of the discrete nature of the interactions on the final destination? And what are the influence of diffusion and additive fluctuations corresponding to random migration and immigration of individuals? This paper aims to answer these questions for a particular competition model that incorporates intra and interspecific competition between the species. Based on mean field theory, the model has a stationary state dependent on the initial density conditions. We investigate how this initial density dependence is affected by the presence of demographic multiplicative noise and additive noise in space and time. There are three main conclusions: (1) Additive noise favors denser populations at the expense of the less dense, ratifying the competitive exclusion principle. (2) Demographic noise, on the other hand, favors less dense populations at the expense of the denser ones, inducing equal densities at the quasi-stationary state, violating the aforementioned principle. (3) The slower species always suffers the more deleterious effects of statistical fluctuations in a homogeneous medium.
Not Available
1988-05-01
These case studies constitute Part II of the ACL Guidance Document. They are intended to assist Regional and State personnel in exercising the discretion conferred by regulation in evaluating applications for alternate concentration limits (ACLs) submitted pursuant to 40 CFR 264.94. The document is not a regulation and should not be used as such. Regional and State personnel must exercise their discretion in using this guidance document as well as other relevant information in determining whether an ACL demonstration meets the regulatory standard.
Adaptive optics ophthalmoscopy.
Roorda, Austin; Duncan, Jacque L
2015-11-01
This review starts with a brief history and description of adaptive optics (AO) technology, followed by a showcase of the latest capabilities of AO systems for imaging the human retina and an extensive review of the literature on where AO is being used clinically. The review concludes with a discussion on future directions and guidance on usage and interpretation of images from AO systems for the eye.
Resources for Guidance Program Improvement. Volume 2.
ERIC Educational Resources Information Center
Frenza, Mary C., Comp.; and Others
This guide, for guidance personnel and teachers, is designed to provide ready access to current, practical programs, activities, and references for improving guidance programs. The resources are organized in four sections representing areas of basic concern for guidance personnel. Section 1 presents selected portions of guidance programs from…
Resources for Guidance Program Improvement. Volume I.
ERIC Educational Resources Information Center
Walz, Garry R., Comp.; And Others
Designed for use by counselors, guidance directors, school administrators, school board members, and anyone interested in the improvement of school guidance programs, this resource book provides a collection of over 100 guidance program models and individual guidance practices. The format consists of references (bibliographic information with…
On the properties of discrete spatial filters for CFD
NASA Astrophysics Data System (ADS)
Báez Vidal, A.; Lehmkuhl, O.; Trias, F. X.; Pérez-Segarra, C. D.
2016-12-01
The spatial filtering of variables in the context of Computational Fluid Dynamics (CFD) is a common practice. Most of the discrete filters used in CFD simulations are locally accurate models of continuous operators. However, when filters are adaptative, i.e. the filter width is not constant, or meshes are irregular, discrete filters sometimes break relevant global properties of the continuous models they are based on. For example, the principle of maxima and minima reduction or conservation are eventually infringed. In this paper, we analyze the properties of analytic continuous convolution filters and extract those we consider to define filtering. Then, we impose the accomplishment of these properties on explicit discrete filters by means of constraints. Three filters satisfying the derived conditions are deduced and compared to common differential discrete CFD filters on synthetic fields. Tests on the developed discrete filters show the fulfillment of the imposed properties. In particular, the problem of maxima and minima generation is resolved for physically relevant cases. The tests are conducted on the basis of the eigenvectors of graph Laplacian matrices of meshes. Thus, insight into the relations between filtering and oscillation growth on general meshes is provided. Further tests on singularity fields and on isentropic vortices have also been conducted to evaluate the performance of filters on basic CFD fields. Results confirm that imposing the proposed conditions makes discrete filters properties consistent with those of the continuous ones.
How navigational guidance systems are combined in a desert ant.
Collett, Matthew
2012-05-22
Animals use information from multiple sources in order to navigate between goals. Ants such as Cataglyphis fortis use an odometer and a sun-based compass to provide input for path integration (PI). They also use configurations of visual features to learn both goal locations and habitual routes to the goals. Information is not combined into a unified representation but appears to be exploited by separate expert guidance systems. Visual and PI goal memories are acquired rapidly and provide the consistency for route memories to be formed. Do established route memories then suppress the guidance from PI? A series of manipulations putting PI and route memories into varying levels of conflict found that ants follow compromise trajectories. The guidance systems are therefore active together and share the control of behavior. Route memories do not suppress the other guidance systems. A simple model shows that observed patterns of control could arise from a superposition of the output commands from the guidance systems, potentially approximating Bayesian inference. These results help show how an insect's relatively simple decision-making can produce navigation that is reliable and efficient and that also adapts to changing demands.
Bound States of One-Dimensional Helium Atom by Discretization of Space and Time
NASA Astrophysics Data System (ADS)
Weatherford, Charles
2001-05-01
The computational theory for calculation of the solution of the time-dependent Schrödinger equation for two electrons [C.A. Weatherford, Computational Chemistry: Reviews of Current Trends, Vol. 5, ed. J. Leszczynski, World Scientific 2000] is reviewed and adapted to the case of the one-dimensional helium atom. This results in a new computational time-dependent exchange/correlation theory. A solution algorithm which discretizes space using a spectral discrete variable basis of synthetic cartesian polynomials, and discretizes time using a spectral element discrete variable basis of Chebyshev polynomials, is presented. Supported by NSF CREST grant HRD-9707076, and by NASA grant NAG5-10148.
GENERAL: Symplectic-energy-first integrators of discrete mechanico-electrical dynamical systems
NASA Astrophysics Data System (ADS)
Fu, Jing-Li; Chen, Ben-Yong; Tang, Yi-Fa; Fu, Hao
2008-11-01
A discrete total variation calculus with variable time steps is presented for mechanico-electrical systems where there exist non-potential and dissipative forces. By using this discrete variation calculus, the symplectic-energy-first integrators for mechanico-electrical systems are derived. To do this, the time step adaptation is employed. The discrete variational principle and the Euler-Lagrange equation are derived for the systems. By using this discrete algorithm it is shown that mechanico-electrical systems are not symplectic and their energies are not conserved unless they are Lagrange mechanico-electrical systems. A practical example is presented to illustrate these results.
Optimal guidance for future space applications
NASA Astrophysics Data System (ADS)
Bradt, J. E.; Jessick, M. V.; Hardtla, J. W.
Use of a powerful flight performance analysis technique is explored for application as a guidance algorithm for future space applications. The technique uses Hermite interpolation and collocation to implicitly integrate the equations of motion. This technique readily accepts flight path constraints such as structural loading or heating. It is an optimal, adaptive algorithm that adjusts to changing flight conditions and also has the necessary structure for performing on-board mission targeting. The capability of the algorithm is demonstrated for three potential applications: (1) a hypersonic gliding reentry to achieve maximum cross range while constraining the vehicle maximum temperature; (2) a low L/D reentry vehicle targeted to earth relative coordinates; and (3) an aerocapture of a Mars space probe targeting a minimum Delta V insertion into an elliptic orbit about the planet.
Optical Kalman filtering for missile guidance
NASA Technical Reports Server (NTRS)
Casasent, D.; Neuman, C. P.; Lycas, J.
1984-01-01
Optical systolic array processors constitute a powerful and general-purpose set of optical architectures with high computational rates. In this paper, Kalman filtering, a novel application for these architectures, is investigated. All required operations are detailed; their realization by optical and special-purpose analog electronics are specified; and the processing time of the system is quantified. The specific Kalman filter application chosen is for an air-to-air missile guidance controller. The architecture realized in this paper meets the design goal of a fully adaptive Kalman filter which processes a measurement every 1 msec. The vital issue of flow and pipelining of data and operations in a systolic array processor is addressed. The approach is sufficiently general and can be realized on an optical or digital systolic array processor.
T Cell Migration in Three-dimensional Extracellular Matrix: Guidance by Polarity and Sensations
Bröker, Eva-Bettina
2000-01-01
The locomotion of T lymphocytes within 3-D extracellular matrix (ECM) is a highly dynamic and flexible process following the principles of ameboid movement. Ameboid motility is characterized by a polarized yet simple cell shape allowing high speed, rapid directional oscillations, and low affinity interactions to the substrate that are coupled to a low degree of cytoskeletal organization lacking discrete focal contacts. At the onset of T cell migration, a default program, here described as migration-associated polarization, is initiated, resulting in the polar redistribution of cell surface receptors and cytoskeletal elements. Polarization involves protein cycling either to the leading edge (i.e. LFA-1, CD45RO, chemokine receptors, focal adhesion kinase), to a central polarizing compartment (MTOC, PKC, MARCKS), or into the uropod (CD44, CD43, ICAM- and –3, β1 integrins). The function of such compartment formation may be important in chemotactic response, scanning of encountered cells, and a flexible and adaptive interaction with the ECM itself. Due to the simple shape and a diffusely organized cytoskeleton, the interactions to the surrounding extracellular matrix are rapid and reversible and appear to allow a broad spectrum of molecular migration strategies. These range from (1) adhesive and haptokinetic following i.e. chemokine-induced motility across 2-D surfaces to (2) largely integrin-independent migration predominantly guided by shape change and morphological flexibility, as seen in 3-D type I collagen matrices. Their prominent capacity to rapidly adapt to a given structural environment coupled to contact guidance mechanisms set T cell locomotion apart from slow, focal contact-dependent and more adhesive migration strategies established by fibroblast-like cells and cell clusters. It is therefore likely that, within the tissues, besides chemotactic or haptotactic gradients, the preformed matrix structure has an important impact on T cell trafficking and
Small Body GN&C Research Report: A G-Guidance Enhancement to Increase Mission Functionality
NASA Technical Reports Server (NTRS)
Carson, John M., III; Ackmese, Behcet
2006-01-01
G-Guidance is a robust G&C (guidance and control) algorithm developed under the small-body GN&C task. The G-Guidance scheme utilizes a model predictive control approach, along with a convexification of the governing dynamics, control constraints, and trajectory/state constraints. This report details an enhancement to the FY2005 G-Guidance algorithm; the addition of a fire-second approach helps to nullify velocity errors and hit desired final velocities much more precisely than the original Fire-first scheme developed in FY2005. The enhancement preserves the primary benefit of the algorithm, which is to ensure required thruster silent times during trajectory maneuvers. The fire-second scheme increases the versatility of the algorithm for missions employing G-Guidance. For instance, a landing sequence could employ the fire-second scheme to ensure a null final velocity at landing, whereas an ascent sequence could utilize a fire-first scheme to ensure there is no drift of the spacecraft toward the ground at the beginning of the maneuver. Examples are provided within to demonstrate a fire-first versus fire-second guidance scheme. As in the existing G-Guidance algorithm, the examples and schemes incorporate gravity models and thruster firing times into discrete dynamics that are solved as a optimal control problem to minimize fuel consumption or thruster energy expenditure.
Chaos in Periodic Discrete Systems
NASA Astrophysics Data System (ADS)
Shi, Yuming; Zhang, Lijuan; Yu, Panpan; Huang, Qiuling
This paper focuses on chaos in periodic discrete systems, whose state space may vary with time. Some close relationships between some chaotic dynamical behaviors of a periodic discrete system and its autonomous induced system are given. Based on these relationships, several criteria of chaos are established and some sufficient conditions for no chaos are given for periodic discrete systems. Further, it is shown that a finite-dimensional linear periodic discrete system is not chaotic in the sense of Li-Yorke or Wiggins. In particular, an interesting problem of whether nonchaotic rules may generate a chaotic system is studied, with some examples provided, one of which surprisingly shows that a composition of globally asymptotically stable maps can be chaotic. In addition, some properties of sign pattern matrices of non-negative square matrices are given for convenience of the study.
Microscopic derivation of discrete hydrodynamics.
Español, Pep; Anero, Jesús G; Zúñiga, Ignacio
2009-12-28
By using the standard theory of coarse graining based on Zwanzig's projection operator, we derive the dynamic equations for discrete hydrodynamic variables. These hydrodynamic variables are defined in terms of the Delaunay triangulation. The resulting microscopically derived equations can be understood, a posteriori, as a discretization on an arbitrary irregular grid of the Navier-Stokes equations. The microscopic derivation provides a set of discrete equations that exactly conserves mass, momentum, and energy and the dissipative part of the dynamics produces strict entropy increase. In addition, the microscopic derivation provides a practical implementation of thermal fluctuations in a way that the fluctuation-dissipation theorem is satisfied exactly. This paper points toward a close connection between coarse-graining procedures from microscopic dynamics and discretization schemes for partial differential equations.
Ultrasound guidance for vascular access.
Abboud, Paul-André C; Kendall, John L
2004-08-01
The evidence that supports the general application of US guidance for venous access in the ED has reached a critical mass. The increasing familiarity of emergency physicians with US and the recent focus on patient safety and clinical outcomes has intensified attention on the capacity for US to improve patient care in the ED. US guidance can increase the safety and efficiency of venous access procedures and offers improved outcomes. The potential for these improvements is compelling, especially among certain types of ED patients such as those with difficult or complicated access. Varying levels of evidence support the use of US guidance over the traditional landmark approach for venous access in adult and pediatric populations and for central and peripheral veins. Many different techniques may be applied, depending on the clinical situation and equipment available.
Information architecture. Volume 3: Guidance
1997-04-01
The purpose of this document, as presented in Volume 1, The Foundations, is to assist the Department of Energy (DOE) in developing and promulgating information architecture guidance. This guidance is aimed at increasing the development of information architecture as a Departmentwide management best practice. This document describes departmental information architecture principles and minimum design characteristics for systems and infrastructures within the DOE Information Architecture Conceptual Model, and establishes a Departmentwide standards-based architecture program. The publication of this document fulfills the commitment to address guiding principles, promote standard architectural practices, and provide technical guidance. This document guides the transition from the baseline or defacto Departmental architecture through approved information management program plans and budgets to the future vision architecture. This document also represents another major step toward establishing a well-organized, logical foundation for the DOE information architecture.
Discrete solitons in graphene metamaterials
NASA Astrophysics Data System (ADS)
Bludov, Yu. V.; Smirnova, D. A.; Kivshar, Yu. S.; Peres, N. M. R.; Vasilevskiy, M. I.
2015-01-01
We study nonlinear properties of multilayer metamaterials created by graphene sheets separated by dielectric layers. We demonstrate that such structures can support localized nonlinear modes described by the discrete nonlinear Schrödinger equation and that its solutions are associated with stable discrete plasmon solitons. We also analyze the nonlinear surface modes in truncated graphene metamaterials being a nonlinear analog of surface Tamm states.
Concurrency and discrete event control
NASA Technical Reports Server (NTRS)
Heymann, Michael
1990-01-01
Much of discrete event control theory has been developed within the framework of automata and formal languages. An alternative approach inspired by the theories of process-algebra as developed in the computer science literature is presented. The framework, which rests on a new formalism of concurrency, can adequately handle nondeterminism and can be used for analysis of a wide range of discrete event phenomena.
Guidance for state attainment plans
Strait, R.
1994-06-01
Title I of the Clean Air act Amendments of 1990 significantly changed requirements for regulatory agencies to prepare state implementation plans that demonstrate attainment of the ozone National Ambient Air Quality Standards. State agencies now are required to submit plans that show how they will meet the standards by their attainment date. EPA has published a series of guidance documents to assist states in preparing their plans. In addition, the agency is developing software to assist states in projecting emissions and tracking reductions. This article summarizes the guidance documents and software program.
Reading Guidance: Death and Grief.
ERIC Educational Resources Information Center
Smith, Alice Gullen
1989-01-01
Gives guidelines for the librarian using reading guidance (similar to bibliotherapy). Provides a nine-item annotated bibliography of novels for children and adolescents on the subject of death and grief. Appends an embryo list of categories suitable for content analysis of any file librarians might wish to keep on books suitable for use in this…
THE STRESSOR IDENTIFICATION GUIDANCE DOCUMENT
THE STRESSOR IDENTIFICATION GUIDANCE DOCUMENT
Susan M. Cormier, ORD/NRMRL, Susan B. Norton, ORD/NCEA, Glenn W. Suter, II ORD/NCEA, William Swietlik, OW lOST
Science Question(s):
MYP Science Question: How can multiple and possibly related causes of biological ...
Atmospheric guidance techniques and performance
NASA Technical Reports Server (NTRS)
Harpold, J. C.; Gavert, D. E.
1982-01-01
The Orbiter entry guidance system controls the Space Shuttle Orbiter from the initial atmospheric penetration point to the point at which an earth relative velocity of 2500 feet/second is reached. At the latter point, control of the Orbiter is transferred to the terminal area energy management system. The entry guidance system is based on the concept that the range to be flown during entry is a unique function of the drag deceleration profile flown throughout the entry. The range prediction during entry is based on analytic equations which are simple drag deceleration functions of earth relative velocity above Mach 10.5 and energy with respect to the earth below Mach 10.5. Flight through the entry corridor is accomplished by linking these simple drag deceleration functions together in series in order to define a drag deceleration reference profile. The results of the first three Space Shuttle missions have not only verified the entry guidance concept but have also demonstrated the stability of the guidance system.
Theater As A Guidance Technique
ERIC Educational Resources Information Center
Wolpert, William
1973-01-01
Guidance-drama activity provides (a) crisp definitions of selected issues; (b) potent modeling from the characters in the play, the students actively engaged in the play, and the students involved in the discussions that follow the play; and (c) a technique for peer-led discussions on sensitive issues. This article gives precise definition to the…
Abortion Information: A Guidance Viewpoint
ERIC Educational Resources Information Center
Wolleat, Patricia L.
1975-01-01
A number of questions relating to providing abortion information to teenagers can be raised from legal, ethical and philosophical standpoints. The purpose of this article is to examine abortion information-giving from the perspective of counseling and guidance theory and practice. (Author)
Imaging Futuristic Career Guidance Goals.
ERIC Educational Resources Information Center
Miller, Juliet V.; and Others
This module is directed toward guidance personnel in school (k-adult) and agency settings such as counselors, teachers, students and administrators. It is also designed for students in pre-service education programs who are familiar with career development theories and information. The Module assumes that the participant is not familiar with the…
Imaging Futuristic Career Guidance Programs.
ERIC Educational Resources Information Center
Miller, Juliet V; And Others
This Module is directed toward guidance personnel in school (K-adult) and agency settings such as counselors, teachers, students and administrators. It is also designed for students in pre-service education programs who have had previous exposure to career development theories and to sources of educational-occupational information. The Module…
Developing Local Lifelong Guidance Strategies.
ERIC Educational Resources Information Center
Watts, A. G.; Hawthorn, Ruth; Hoffbrand, Jill; Jackson, Heather; Spurling, Andrea
1997-01-01
Outlines the background, rationale, methodology, and outcomes of developing local lifelong guidance strategies in four geographic areas. Analyzes the main components of the strategies developed and addresses a number of issues relating to the process of strategy development. Explores implications for parallel work in other localities. (RJM)
Research Bulletin: Bayesian Guidance Technology.
ERIC Educational Resources Information Center
Novick, Melvin R.; Jackson, Paul H.
This paper presents a discussion of the use of educational tests in guidance services as seen in the light of modern developments in statistical theory and computer technology, and of the increasing demands for such services. A focus and vocabulary for this discussion is found in Turnbull's recent article on "Relevance in Testing." Following an…
Elementary Guidance Program. Navajo Area.
ERIC Educational Resources Information Center
Bureau of Indian Affairs (Dept. of Interior), Window Rock, AZ.
A program designed to assist guidance staff in working with Navajo elementary school students, particularly boarding school students, is presented in this booklet with emphasis directed toward meeting both individual and group needs in the areas of home living, student activities, and counseling. The first section gives 14 separate functions of…
Consensus standard requirements and guidance
Putman, V.L.
1995-12-01
This report presents information from the ANS Criticality Alarm System Workshop relating to the consensus standard requirements and guidance. Topics presented include: definition; nomenclature; requirements and recommendations; purpose of criticality alarms; design criteria; signal characteristics; reliability, dependability and durability; tests; and emergency preparedness and planning.
Child Development, Care, and Guidance.
ERIC Educational Resources Information Center
Texas Education Agency, Austin. Dept. of Occupational Education and Technology.
This teacher's guide on child development, care, and guidance is one of seven subject area guides developed for use in consumer and homemaking education in secondary schools in Texas. The guide is correlated with the "Conceptual Framework for Consumer and Homemaking Education in Texas." Content is based on the competencies needed by…
Guidance for Supporting School Counselors
ERIC Educational Resources Information Center
Light, Carolyn
2005-01-01
School counselors need the assistance of principals and other administrators to improve guidance and school counseling services in schools. Principals and other administrators are the leaders in education, and it is important that they know how to create the best school counseling programs possible. This article provides 12 suggestions that can…
Educational Guidance and Curriculum Change.
ERIC Educational Resources Information Center
Oakeshott, Martin
A project conducted by Britain's Further Education Unit: (1) identified and evaluated strategies used by Educational Guidance Services for Adults (EGSAs) to feed back to providers of learning opportunities the unmet needs of adult clients with particular reference to the unemployed and unwaged; (2) identified and evaluated mechanisms used by…
Guidance strategies for microburst escape
NASA Astrophysics Data System (ADS)
Dogan, Atilla
This study compares three escape guidance laws for microburst encounters during final landing approach: Altitude-Guidance, Dive-Guidance, and Pitch-Guidance from the point of view of safety. It also introduces Modified Altitude- and Dive-Guidance laws. In this study, we use a full, 6-DOF, nonlinear, rigid-body aircraft model, including the effects of windshear and wind vorticity, and a model of microburst with turbulence. We also model the effect of stall prevention on the escape path. We first construct a new safety metric that quantifies the aircraft upward force capability in a microburst encounter. In the absence of turbulence, the safety factor is analytically proven to be a decreasing function of altitude. This suggests that descending to a low altitude may improve safety in the sense that the aircraft will have more upward force capability to maintain its altitude. In the presence of stochastic turbulence, the safety factor is treated as a random variable and its probability distribution function is analytically approximated as a function of altitude. This approximation reveals that the probability of safety factor being less than a given value has a minimum, i.e. safety increases as the altitude decreases up to a certain altitude, then starts decreasing. In the dissertation, two different approaches are used for comparison. (1) In a sample analysis approach, typical samples of the time histories of various variables are analyzed. Additionally, an animation of an aircraft escaping a microburst is produced and the behavior of the aircraft along with its inertial velocity and airspeed vectors are studied. (2) In a statistical approach, the probability distribution of the minimum altitude is estimated by the Monte Carlo Method when the statistical properties of the microburst parameters are known. Both approaches suggest that, within the modeling assumptions of this dissertation, and in the absence of human factors, altitude and dive guidance with low commanded
Anomaly Detection for Discrete Sequences: A Survey
Chandola, Varun; Banerjee, Arindam; Kumar, Vipin
2012-01-01
This survey attempts to provide a comprehensive and structured overview of the existing research for the problem of detecting anomalies in discrete/symbolic sequences. The objective is to provide a global understanding of the sequence anomaly detection problem and how existing techniques relate to each other. The key contribution of this survey is the classification of the existing research into three distinct categories, based on the problem formulation that they are trying to solve. These problem formulations are: 1) identifying anomalous sequences with respect to a database of normal sequences; 2) identifying an anomalous subsequence within a long sequence; and 3) identifying a pattern in a sequence whose frequency of occurrence is anomalous. We show how each of these problem formulations is characteristically distinct from each other and discuss their relevance in various application domains. We review techniques from many disparate and disconnected application domains that address each of these formulations. Within each problem formulation, we group techniques into categories based on the nature of the underlying algorithm. For each category, we provide a basic anomaly detection technique, and show how the existing techniques are variants of the basic technique. This approach shows how different techniques within a category are related or different from each other. Our categorization reveals new variants and combinations that have not been investigated before for anomaly detection. We also provide a discussion of relative strengths and weaknesses of different techniques. We show how techniques developed for one problem formulation can be adapted to solve a different formulation, thereby providing several novel adaptations to solve the different problem formulations. We also highlight the applicability of the techniques that handle discrete sequences to other related areas such as online anomaly detection and time series anomaly detection.
Robust and Adaptive Guidance and Control Laws for Missile Systems
1994-06-26
Englewood Cliffs, NJ: Prentice-Hall, 1988. positive real lemma are developed in Sections II and HI using optimal [111 R. S. Varga . Matrix Iterative...testing certain Math, 1987. square matrices for positive definiteness related to the generalized [14] F. Alvarado , "Parallel solution of transient
Discrete solitons in electromechanical resonators.
Syafwan, M; Susanto, H; Cox, S M
2010-02-01
We consider a particular type of parametrically driven discrete Klein-Gordon system describing microdevices and nanodevices, with integrated electrical and mechanical functionality. Using a multiscale expansion method we reduce the system to a discrete nonlinear Schrödinger equation. Analytical and numerical calculations are performed to determine the existence and stability of fundamental bright and dark discrete solitons admitted by the Klein-Gordon system through the discrete Schrödinger equation. We show that a parametric driving can not only destabilize onsite bright solitons, but also stabilize intersite bright discrete solitons and onsite and intersite dark solitons. Most importantly, we show that there is a range of values of the driving coefficient for which dark solitons are stable, for any value of the coupling constant, i.e., oscillatory instabilities are totally suppressed. Stability windows of all the fundamental solitons are presented and approximations to the onset of instability are derived using perturbation theory, with accompanying numerical results. Numerical integrations of the Klein-Gordon equation are performed, confirming the relevance of our analysis.
Distributed Relaxation for Conservative Discretizations
NASA Technical Reports Server (NTRS)
Diskin, Boris; Thomas, James L.
2001-01-01
A multigrid method is defined as having textbook multigrid efficiency (TME) if the solutions to the governing system of equations are attained in a computational work that is a small (less than 10) multiple of the operation count in one target-grid residual evaluation. The way to achieve this efficiency is the distributed relaxation approach. TME solvers employing distributed relaxation have already been demonstrated for nonconservative formulations of high-Reynolds-number viscous incompressible and subsonic compressible flow regimes. The purpose of this paper is to provide foundations for applications of distributed relaxation to conservative discretizations. A direct correspondence between the primitive variable interpolations for calculating fluxes in conservative finite-volume discretizations and stencils of the discretized derivatives in the nonconservative formulation has been established. Based on this correspondence, one can arrive at a conservative discretization which is very efficiently solved with a nonconservative relaxation scheme and this is demonstrated for conservative discretization of the quasi one-dimensional Euler equations. Formulations for both staggered and collocated grid arrangements are considered and extensions of the general procedure to multiple dimensions are discussed.
On the Importance of the Dynamics of Discretizations
NASA Technical Reports Server (NTRS)
Sweby, Peter K.; Yee, H. C.; Rai, ManMohan (Technical Monitor)
1995-01-01
It has been realized recently that the discrete maps resulting from numerical discretizations of differential equations can possess asymptotic dynamical behavior quite different from that of the original systems. This is the case not only for systems of Ordinary Differential Equations (ODEs) but in a more complicated manner for Partial Differential Equations (PDEs) used to model complex physics. The impact of the modified dynamics may be mild and even not observed for some numerical methods. For other classes of discretizations the impact may be pronounced, but not always obvious depending on the nonlinear model equations, the time steps, the grid spacings and the initial conditions. Non-convergence or convergence to periodic solutions might be easily recognizable but convergence to incorrect but plausible solutions may not be so obvious - even for discretized parameters within the linearized stability constraint. Based on our past four years of research, we will illustrate some of the pathology of the dynamics of discretizations, its possible impact and the usage of these schemes for model nonlinear ODEs, convection-diffusion equations and grid adaptations.
Pinning synchronization of discrete dynamical networks with delay coupling
NASA Astrophysics Data System (ADS)
Cheng, Ranran; Peng, Mingshu; Zuo, Jun
2016-05-01
The purpose of this paper is to investigate the pinning synchronization analysis for nonlinear coupled delayed discrete dynamical networks with the identical or nonidentical topological structure. Based on the Lyapunov stability theory, pinning control method and linear matrix inequalities, several adaptive synchronization criteria via two kinds of pinning control method are obtained. Two examples based on Rulkov chaotic system are included to illustrate the effectiveness and verification of theoretical analysis.
Guidance: CERCLA Section 106 Judicial Actions
This guidance provides criteria for consideration in selecting and initiating Section 106 judicial actions. The guidance also identifies and discusses issues that should be considered in preparation of a Section 106 referral.
Integrable structure in discrete shell membrane theory
Schief, W. K.
2014-01-01
We present natural discrete analogues of two integrable classes of shell membranes. By construction, these discrete shell membranes are in equilibrium with respect to suitably chosen internal stresses and external forces. The integrability of the underlying equilibrium equations is proved by relating the geometry of the discrete shell membranes to discrete O surface theory. We establish connections with generalized barycentric coordinates and nine-point centres and identify a discrete version of the classical Gauss equation of surface theory. PMID:24808755
Discretization errors in particle tracking
NASA Astrophysics Data System (ADS)
Carmon, G.; Mamman, N.; Feingold, M.
2007-03-01
High precision video tracking of microscopic particles is limited by systematic and random errors. Systematic errors are partly due to the discretization process both in position and in intensity. We study the behavior of such errors in a simple tracking algorithm designed for the case of symmetric particles. This symmetry algorithm uses interpolation to estimate the value of the intensity at arbitrary points in the image plane. We show that the discretization error is composed of two parts: (1) the error due to the discretization of the intensity, bD and (2) that due to interpolation, bI. While bD behaves asymptotically like N-1 where N is the number of intensity gray levels, bI is small when using cubic spline interpolation.
Dispersion reducing methods for edge discretizations of the electric vector wave equation
NASA Astrophysics Data System (ADS)
Bokil, V. A.; Gibson, N. L.; Gyrya, V.; McGregor, D. A.
2015-04-01
We present a novel strategy for minimizing the numerical dispersion error in edge discretizations of the time-domain electric vector wave equation on square meshes based on the mimetic finite difference (MFD) method. We compare this strategy, called M-adaptation, to two other discretizations, also based on square meshes. One is the lowest order Nédélec edge element discretization. The other is a modified quadrature approach (GY-adaptation) proposed by Guddati and Yue for the acoustic wave equation in two dimensions. All three discrete methods use the same edge-based degrees of freedom, while the temporal discretization is performed using the standard explicit Leapfrog scheme. To obtain efficient and explicit time stepping methods, the three schemes are further mass lumped. We perform a dispersion and stability analysis for the presented schemes and compare all three methods in terms of their stability regions and phase error. Our results indicate that the method produced by GY-adaptation and the Nédélec method are both second order accurate for numerical dispersion, but differ in the order of their numerical anisotropy (fourth order, versus second order, respectively). The result of M-adaptation is a discretization that is fourth order accurate for numerical dispersion as well as numerical anisotropy. Numerical simulations are provided that illustrate the theoretical results.
Melman, T; de Winter, J C F; Abbink, D A
2017-01-01
An important issue in road traffic safety is that drivers show adverse behavioral adaptation (BA) to driver assistance systems. Haptic steering guidance is an upcoming assistance system which facilitates lane-keeping performance while keeping drivers in the loop, and which may be particularly prone to BA. Thus far, experiments on haptic steering guidance have measured driver performance while the vehicle speed was kept constant. The aim of the present driving simulator study was to examine whether haptic steering guidance causes BA in the form of speeding, and to evaluate two types of haptic steering guidance designed not to suffer from BA. Twenty-four participants drove a 1.8m wide car for 13.9km on a curved road, with cones demarcating a single 2.2m narrow lane. Participants completed four conditions in a counterbalanced design: no guidance (Manual), continuous haptic guidance (Cont), continuous guidance that linearly reduced feedback gains from full guidance at 125km/h towards manual control at 130km/h and above (ContRF), and haptic guidance provided only when the predicted lateral position was outside a lateral bandwidth (Band). Participants were familiarized with each condition prior to the experimental runs and were instructed to drive as they normally would while minimizing the number of cone hits. Compared to Manual, the Cont condition yielded a significantly higher driving speed (on average by 7km/h), whereas ContRF and Band did not. All three guidance conditions yielded better lane-keeping performance than Manual, whereas Cont and ContRF yielded lower self-reported workload than Manual. In conclusion, continuous steering guidance entices drivers to increase their speed, thereby diminishing its potential safety benefits. It is possible to prevent BA while retaining safety benefits by making a design adjustment either in lateral (Band) or in longitudinal (ContRF) direction.
A guidance concept for hypersonic aerospacecrafts
NASA Astrophysics Data System (ADS)
Ishimoto, Shinji
In this paper a guidance concept for hypersonic re-entry flights is presented. The method uses a closed-form guidance technique based on a drag acceleration reference profile. A guidance law for range control is developed. It employs a physical relation between vehicle energy and range instead of a prediction-correction technique used for Shuttle entry guidance. Simulation results show that the algorithm provides good performance.
Distributed Adaptive Control: Beyond Single-Instant, Discrete Variables
NASA Technical Reports Server (NTRS)
Wolpert, David H.; Bieniawski, Stefan
2005-01-01
In extensive form noncooperative game theory, at each instant t, each agent i sets its state x, independently of the other agents, by sampling an associated distribution, q(sub i)(x(sub i)). The coupling between the agents arises in the joint evolution of those distributions. Distributed control problems can be cast the same way. In those problems the system designer sets aspects of the joint evolution of the distributions to try to optimize the goal for the overall system. Now information theory tells us what the separate q(sub i) of the agents are most likely to be if the system were to have a particular expected value of the objective function G(x(sub 1),x(sub 2), ...). So one can view the job of the system designer as speeding an iterative process. Each step of that process starts with a specified value of E(G), and the convergence of the q(sub i) to the most likely set of distributions consistent with that value. After this the target value for E(sub q)(G) is lowered, and then the process repeats. Previous work has elaborated many schemes for implementing this process when the underlying variables x(sub i) all have a finite number of possible values and G does not extend to multiple instants in time. That work also is based on a fixed mapping from agents to control devices, so that the the statistical independence of the agents' moves means independence of the device states. This paper also extends that work to relax all of these restrictions. This extends the applicability of that work to include continuous spaces and Reinforcement Learning. This paper also elaborates how some of that earlier work can be viewed as a first-principles justification of evolution-based search algorithms.
Discrete cloud structure on Neptune
NASA Technical Reports Server (NTRS)
Hammel, H. B.
1989-01-01
Recent CCD imaging data for the discrete cloud structure of Neptune shows that while cloud features at CH4-band wavelengths are manifest in the southern hemisphere, they have not been encountered in the northern hemisphere since 1986. A literature search has shown the reflected CH4-band light from the planet to have come from a single discrete feature at least twice in the last 10 years. Disk-integrated photometry derived from the imaging has demonstrated that a bright cloud feature was responsible for the observed 8900 A diurnal variation in 1986 and 1987.
Quality Assurance in University Guidance Services
ERIC Educational Resources Information Center
Simon, Alexandra
2014-01-01
In Europe there is no common quality assurance framework for the delivery of guidance in higher education. Using a case study approach in four university career guidance services in England, France and Spain, this article aims to study how quality is implemented in university career guidance services in terms of strategy, standards and models,…
Space Shuttle ascent guidance, navigation, and control
NASA Technical Reports Server (NTRS)
Mchenry, R. L.; Long, A. D.; Cockrell, B. F.; Thibodeau, J. R., III; Brand, T. J.
1979-01-01
The factors leading to the particular design of the Shuttle guidance, navigation and control software are discussed. The derivation of explicit guidance equations satisfying a wide range of different maneuver constraints and steering equations that create attitude steering errors from the guidance solutions is presented, as are navigation equations, and equations for identifying faulty instruments from sets of redundant instrument measurements.
Providing Career Guidance for Young Women.
ERIC Educational Resources Information Center
Colby, Pamela G.
This module is directed at personnel working or planning to work in the areas of guidance, counseling, placement and follow-through in junior and senior high school settings, grades 7-12. The module topic is career guidance for young women of junior and senior high school age, aand the focus will be on providing nonbiased career guidance which…
75 FR 76079 - Sound Incentive Compensation Guidance
Federal Register 2010, 2011, 2012, 2013, 2014
2010-12-07
... Office of Thrift Supervision Sound Incentive Compensation Guidance AGENCY: Office of Thrift Supervision... collection. Title of Proposal: Sound Incentive Compensation Guidance. OMB Number: 1550-0129. Form Number: N/A... principles and the guidance are consistent with the Principles for Sound Compensation Practices adopted...
75 FR 22679 - Sound Incentive Compensation Guidance
Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-29
... Office of Thrift Supervision Sound Incentive Compensation Guidance AGENCY: Office of Thrift Supervision... collection. Title of Proposal: Sound Incentive Compensation Guidance. OMB Number: 1550-0NEW. Form Number: N/A... principles and the guidance are consistent with the Principles for Sound Compensation Practices adopted...
75 FR 53023 - Sound Incentive Compensation Guidance
Federal Register 2010, 2011, 2012, 2013, 2014
2010-08-30
... Office of Thrift Supervision Sound Incentive Compensation Guidance AGENCY: Office of Thrift Supervision... collection. Title of Proposal: Sound Incentive Compensation Guidance. OMB Number: 1550-0129. Form Number: N/A... principles and the guidance are consistent with the Principles for Sound Compensation Practices adopted...
Reentry guidance for Space Shuttle
NASA Technical Reports Server (NTRS)
Causey, W.; Sohoni, V.
1973-01-01
An explicit guidance scheme is outlined which provides the appropriate energy management in order for the shuttle orbiter to reach any location within the required footprint. Considering the orbiter as entering the earth's atmosphere, expressions for the downrange, crossrange, and the time of the termination of the entry phase as functions of the control variables are developed. Performing an order-of-magnitude analysis of the terms in these expressions, only dominant terms are retained. Analytical expressions for the elements of the sensitivity matrix which represents the partial derivatives of the desired range with respect to control variables are formulated. Using the Gauss-Jordan inversion technique, the required change in guidance commands as a function of the deviations in the downrange and crossrange are explicitly computed.
Teleautonomous guidance for mobile robots
NASA Technical Reports Server (NTRS)
Borenstein, J.; Koren, Y.
1990-01-01
Teleautonomous guidance (TG), a technique for the remote guidance of fast mobile robots, has been developed and implemented. With TG, the mobile robot follows the general direction prescribed by an operator. However, if the robot encounters an obstacle, it autonomously avoids collision with that obstacle while trying to match the prescribed direction as closely as possible. This type of shared control is completely transparent and transfers control between teleoperation and autonomous obstacle avoidance gradually. TG allows the operator to steer vehicles and robots at high speeds and in cluttered environments, even without visual contact. TG is based on the virtual force field (VFF) method, which was developed earlier for autonomous obstacle avoidance. The VFF method is especially suited to the accommodation of inaccurate sensor data (such as that produced by ultrasonic sensors) and sensor fusion, and allows the mobile robot to travel quickly without stopping for obstacles.
Optical guidance vidicon test program
NASA Technical Reports Server (NTRS)
Eiseman, A. R.; Stanton, R. H.; Voge, C. C.
1976-01-01
A laboratory and field test program was conducted to quantify the optical navigation parameters of the Mariner vidicons. A scene simulator and a camera were designed and built for vidicon tests under a wide variety of conditions. Laboratory tests characterized error sources important to the optical navigation process and field tests verified star sensitivity and characterized comet optical guidance parameters. The equipment, tests and data reduction techniques used are described. Key test results are listed. A substantial increase in the understanding of the use of selenium vidicons as detectors for spacecraft optical guidance was achieved, indicating a reduction in residual offset errors by a factor of two to four to the single pixel level.
2011 Army Strategic Planning Guidance
2011-03-25
TESI ) of 22,000 Soldiers, the Army’s total force by the end of the mid-term period is programmed to be 520K (AC). We will achieve a more...dwell ratios, extending TESI authority to adequately man deploying units and sustain the All-Volunteer Force, right-sizing the generating force, and... TESI Temporary End-Strength Increase WMD Weapons of Mass Destruction 2011 ARMY STRATEGIC PLANNING GUIDANCE Page 19 2011
Mars Science Laboratory Entry Guidance
NASA Technical Reports Server (NTRS)
Mendeck, Gavin F.
2011-01-01
The Mars Science Laboratory will be the first Mars mission to attempt a guided entry with the objective of safely delivering the entry vehicle to a survivable parachute deploy state within 12.5 km of the pre-designated parachute deploy coordinates. The Entry Terminal Point Controller guidance algorithm is derived from the final phase Apollo Command Module guidance and, like Apollo, modulates the bank angle to control range based on deviations in range, altitude rate, and drag acceleration from a reference trajectory. For application to Mars landers which must make use of the tenuous Martian atmosphere, it is critical to balance the lift of the vehicle to minimize the range while still ensuring a safe deploy altitude. An overview of the process to generate optimized guidance settings is presented, discussing improvements made over the last nine years. Performance tradeoffs between ellipse size and deploy altitude will be presented, along with imposed constraints of entry acceleration and heating. Performance sensitivities to the bank reversal deadbands, heading alignment, attitude initialization error, and entry delivery errors are presented.
BENCHMARK DOSE TECHNICAL GUIDANCE DOCUMENT ...
The U.S. EPA conducts risk assessments for an array of health effects that may result from exposure to environmental agents, and that require an analysis of the relationship between exposure and health-related outcomes. The dose-response assessment is essentially a two-step process, the first being the definition of a point of departure (POD), and the second extrapolation from the POD to low environmentally-relevant exposure levels. The benchmark dose (BMD) approach provides a more quantitative alternative to the first step in the dose-response assessment than the current NOAEL/LOAEL process for noncancer health effects, and is similar to that for determining the POD proposed for cancer endpoints. As the Agency moves toward harmonization of approaches for human health risk assessment, the dichotomy between cancer and noncancer health effects is being replaced by consideration of mode of action and whether the effects of concern are likely to be linear or nonlinear at low doses. Thus, the purpose of this project is to provide guidance for the Agency and the outside community on the application of the BMD approach in determining the POD for all types of health effects data, whether a linear or nonlinear low dose extrapolation is used. A guidance document is being developed under the auspices of EPA's Risk Assessment Forum. The purpose of this project is to provide guidance for the Agency and the outside community on the application of the benchmark dose (BMD) appr
Reduced discretization error in HZETRN
Slaba, Tony C.; Blattnig, Steve R.; Tweed, John
2013-02-01
The deterministic particle transport code HZETRN is an efficient analysis tool for studying the effects of space radiation on humans, electronics, and shielding materials. In a previous work, numerical methods in the code were reviewed, and new methods were developed that further improved efficiency and reduced overall discretization error. It was also shown that the remaining discretization error could be attributed to low energy light ions (A < 4) with residual ranges smaller than the physical step-size taken by the code. Accurately resolving the spectrum of low energy light particles is important in assessing risk associated with astronaut radiation exposure. In this work, modifications to the light particle transport formalism are presented that accurately resolve the spectrum of low energy light ion target fragments. The modified formalism is shown to significantly reduce overall discretization error and allows a physical approximation to be removed. For typical step-sizes and energy grids used in HZETRN, discretization errors for the revised light particle transport algorithms are shown to be less than 4% for aluminum and water shielding thicknesses as large as 100 g/cm{sup 2} exposed to both solar particle event and galactic cosmic ray environments.
Discrete tomography in neutron radiography
NASA Astrophysics Data System (ADS)
Kuba, Attila; Rodek, Lajos; Kiss, Zoltán; Ruskó, László; Nagy, Antal; Balaskó, Márton
2005-04-01
Discrete tomography (DT) is an imaging technique for reconstructing discrete images from their projections using the knowledge that the object to be reconstructed contains only a few homogeneous materials characterized by known discrete absorption values. One of the main reasons for applying DT is that we will hopefully require relatively few projections. Using discreteness and some a priori information (such as an approximate shape of the object) we can apply two DT methods in neutron imaging by reducing the problem to an optimization task. The first method is a special one because it is only suitable if the object is composed of cylinders and sphere shapes. The second method is a general one in the sense that it can be used for reconstructing objects of any shape. Software was developed and physical experiments performed in order to investigate the effects of several reconstruction parameters: the number of projections, noise levels, and complexity of the object to be reconstructed. We give a summary of the experimental results and make a comparison of the results obtained using a classical reconstruction technique (FBP). The programs we developed are available in our DT reconstruction program package DIRECT.
Police Discretion: A Selected Bibliography.
ERIC Educational Resources Information Center
Brenner, Robert N.; Kravitz, Marjorie
This bibliography was compiled with two goals. The first goal is to provide police administrators and officers with an overview of the issues involved in developing guidelines for police discretion and a discussion of the options available. The second goal is to demonstrate the need for continuing dialogue and interaction between lawmakers, law…
High order discontinuous Galerkin discretizations with discontinuity resolution within the cell
NASA Astrophysics Data System (ADS)
Ekaterinaris, John; Panourgias, Konstantinos
2016-11-01
The nonlinear filter of Yee et al. and used for low dissipative well-balanced high order accurate finite-difference schemes is adapted to the finite element context of discontinuous Galerkin (DG) discretizations. The performance of the proposed nonlinear filter for DG discretizations is demonstrated for different orders of expansions for one- and multi-dimensional problems with exact solutions. It is shown that for higher order discretizations discontinuity resolution within the cell is achieved and the design order of accuracy is preserved. The filter is applied for inviscid and viscous flow test problems including strong shocks interactions to demonstrate that the proposed dissipative mechanism for DG discretizations yields superior results compared to the results obtained with the TVB limiter and high-order hierarchical limiting. The proposed approach is suitable for p-adaptivity in order to locally enhance resolution of three-dimensional flow simulations.
Where does axon guidance lead us?
Stoeckli, Esther
2017-01-01
During neural circuit formation, axons need to navigate to their target cells in a complex, constantly changing environment. Although we most likely have identified most axon guidance cues and their receptors, we still cannot explain the molecular background of pathfinding for any subpopulation of axons. We lack mechanistic insight into the regulation of interactions between guidance receptors and their ligands. Recent developments in the field of axon guidance suggest that the regulation of surface expression of guidance receptors comprises transcriptional, translational, and post-translational mechanisms, such as trafficking of vesicles with specific cargos, protein-protein interactions, and specific proteolysis of guidance receptors. Not only axon guidance molecules but also the regulatory mechanisms that control their spatial and temporal expression are involved in synaptogenesis and synaptic plasticity. Therefore, it is not surprising that genes associated with axon guidance are frequently found in genetic and genomic studies of neurodevelopmental disorders. PMID:28163913
David A. Boothman
1999-08-11
Due to several interesting findings on both adaptive survival responses (ASRs) and DNA mismatch repair (MMR), this grant was separated into two discrete Specific Aim sets (each with their own discrete hypotheses). The described experiments were simultaneously performed.
Impact of large sidelobe discretes in SAR image formation
NASA Astrophysics Data System (ADS)
Maher, John E.; Lynch, E. Douglas; Schneible, Richard; Wicks, Michael C.; Zhang, Yuhong
2001-12-01
In this paper, the U.S. Air Force's Research Laboratory Space-Time Adaptive Processing (RLSTAP) tool is used to demonstrate the impact of large sidelobe discretes on modern Synthetic Aperture Radar (SAR) signal and image processing. Sidelobe discretes ay mask or even completely obscure weak target returns of interest in the immediate vicinity of these strong returns. Adaptive processing offers the potential to mitigate the effects of strong sidelobe discretes on image formation. In this paper, we characterize the severity of the problems caused by these discretes. RLSTAP can simulate high-fidelity airborne, spaceborne, or ground based multi-channel radar data in jamming and clutter environments, develop and evaluate new signal and image processing algorithms, and assess the performance of advanced radar systems. RLSTAP is a time domain simulation, updating object positions for every radar pulse and allowing modeling of realistic effects such as returns 'walking' across range bins and Doppler filters. The site-specific clutter model uses terrain elevation and cover data to derive the line-of-site visibility, grazing angle, and clutter type for each range-angle cell. Spatial and temporal clutter statistics are applied to each cell and the signal strength at the receiver is calculated as a function of the backscatter coefficient, range, atmospheric attenuation, antenna gain, and system gains/losses. The scene generation capability in RLSTAP is unique in that it exploits Defense Terrain Elevation Data (DTED) and Land Use Land Cover Data (LULC) to create realistic clutter scenes (data cubes) for any given geographic location. As such, the application of adaptive multi-channel/multi-pulse processing to radar data that is characteristic of the area being imaged is now possible. Furthermore, the selection of waveform parameters, signal and image processing techniques, and associated radar parameters may be improved upon.
Brown, D.; Freitag, L.; Glimm, J.
2002-03-28
We present an overview of the technical objectives of the Terascale Simulation Tools and Technologies center. The primary goal of this multi-institution collaboration is to develop technologies that enable application scientists to easily use multiple mesh and discretization strategies within a single simulation on terascale computers. The discussion focuses on our efforts to create interoperable mesh generation tools, high-order discretization techniques, and adaptive meshing strategies.
Climate Change Adaptation Plan
2014-06-01
currently valid OMB control number. 1. REPORT DATE JUN 2014 2 . REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Climate...PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 2 I...policy and guidance. 3 I N T R O D U C T I O NC O N T E N T S EXECUTIVE SUMMARY 2 CONTENTS 3 INTRODUCTION 4 What’s new in the 2014 Adaptation Plan 4
Spatial data discretization methods for geocomputation
NASA Astrophysics Data System (ADS)
Cao, Feng; Ge, Yong; Wang, Jinfeng
2014-02-01
Geocomputation provides solutions to complex geographic problems. Continuous and discrete spatial data are involved in the geocomputational process; however, geocomputational methods for discrete spatial data cannot be directly applied to continuous or mixed spatial data. Therefore, discretization methods for continuous or mixed spatial data are involved in the process. Since spatial data has spatial features, such as association, heterogeneity and spatial structure, these features cannot be handled by traditional discretization methods. Therefore, this work develops feature-based spatial data discretization methods that achieve optimal discretization results for spatial data using spatial information implicit in those features. Two discretization methods considering the features of spatial data are presented. One is an unsupervised method considering autocorrelation of spatial data and the other is a supervised method considering spatial heterogeneity. Discretization processes of the two methods are exemplified using neural tube defects (NTD) for Heshun County in Shanxi Province, China. Effectiveness is also assessed.
Modular strapdown guidance unit with embedded microprocessors
NASA Astrophysics Data System (ADS)
Gilmore, J. P.
1980-02-01
The Low-Cost Inertial Guidance System (LCIGS) is a modular strapdown implementation of attitude (gyro) and velocity (accelerometer) axes which permits the interchangeable use of different manufacturer's instruments without affecting the system's electronic or mechanical interfaces or processing software. This design flexibility is made possible by the use of microprocessors for processing and control. The microprocessors are embedded in each module and five are used: one per accelerometer triad, one each per gyro module, and one in the service module. The processors effect on-line digital torquing control of the gyros, active instrument error model compensation, including modeling for temperature sensitivity effects, temperature control, self-testing, etc. Adaptation of processing and calibration algorithms to accommodate for instrument changes or sensed environmental variations is achieved through the use of an alterable read-only data base that may be updated by the LCIGS support equipment as required at calibrations or upon an instrument replacement. This data base is accessed by the microprocessors and used to compute coefficient corrections for the processing algorithms. The system architecture is presented and the microprocessor software partitioning and functions are described.
Precision optical navigation guidance system
NASA Astrophysics Data System (ADS)
Starodubov, D.; McCormick, K.; Nolan, P.; Johnson, D.; Dellosa, M.; Volfson, L.; Fallahpour, A.; Willner, A.
2016-05-01
We present the new precision optical navigation guidance system approach that provides continuous, high quality range and bearing data to fixed wing aircraft during landing approach to an aircraft carrier. The system uses infrared optical communications to measure range between ship and aircraft with accuracy and precision better than 1 meter at ranges more than 7.5 km. The innovative receiver design measures bearing from aircraft to ship with accuracy and precision better than 0.5 mRad. The system provides real-time range and bearing updates to multiple aircraft at rates up to several kHz, and duplex data transmission between ship and aircraft.
Orthobiologic Interventions Using Ultrasound Guidance.
Malanga, Gerard; Abdelshahed, Dena; Jayaram, Prathap
2016-08-01
The application of regenerative therapies for the treatment of musculoskeletal conditions has emerged over the last decade with recent acceleration. These include prolotherapy, platelet-rich plasma, and mesenchymal stem cell therapy. These strategies augment the body's innate physiology to heal pathologic processes. This article presents an overview of platelet-rich plasma and mesenchymal stem cell therapy for the treatment of musculoskeletal injuries. A brief literature review is included, as are techniques for the use of ultrasound guidance to assist with these procedures.
Systoles in discrete dynamical systems
NASA Astrophysics Data System (ADS)
Fernandes, Sara; Grácio, Clara; Ramos, Carlos Correia
2013-01-01
The fruitful relationship between Geometry and Graph Theory has been explored by several authors benefiting also the Theory of discrete dynamical systems seen as Markov chains in graphs. In this work we will further explore the relation between these areas, giving a geometrical interpretation of notions from dynamical systems. In particular, we relate the topological entropy with the systole, here defined in the context of discrete dynamical systems. We show that for continuous interval maps the systole is trivial; however, for the class of interval maps with one discontinuity point the systole acquires relevance from the point of view of the dynamical behavior. Moreover, we define the geodesic length spectrum associated to a Markov interval map and we compute the referred spectrum in several examples.
Dark Energy from Discrete Spacetime
Trout, Aaron D.
2013-01-01
Dark energy accounts for most of the matter-energy content of our universe, yet current theories of its origin rely on radical physical assumptions such as the holographic principle or controversial anthropic arguments. We give a better motivated explanation for dark energy, claiming that it arises from a small negative scalar-curvature present even in empty spacetime. The vacuum has this curvature because spacetime is fundamentally discrete and there are more ways for a discrete geometry to have negative curvature than positive. We explicitly compute this effect using a variant of the well known dynamical-triangulations (DT) model for quantum gravity. Our model predicts a time-varying non-zero cosmological constant with a current value, in natural units, in agreement with observation. This calculation is made possible by a novel characterization of the possible DT action values combined with numerical evidence concerning their degeneracies. PMID:24312502
Dark energy from discrete spacetime.
Trout, Aaron D
2013-01-01
Dark energy accounts for most of the matter-energy content of our universe, yet current theories of its origin rely on radical physical assumptions such as the holographic principle or controversial anthropic arguments. We give a better motivated explanation for dark energy, claiming that it arises from a small negative scalar-curvature present even in empty spacetime. The vacuum has this curvature because spacetime is fundamentally discrete and there are more ways for a discrete geometry to have negative curvature than positive. We explicitly compute this effect using a variant of the well known dynamical-triangulations (DT) model for quantum gravity. Our model predicts a time-varying non-zero cosmological constant with a current value, [Formula: see text] in natural units, in agreement with observation. This calculation is made possible by a novel characterization of the possible DT action values combined with numerical evidence concerning their degeneracies.
Observability of discretized partial differential equations
NASA Technical Reports Server (NTRS)
Cohn, Stephen E.; Dee, Dick P.
1988-01-01
It is shown that complete observability of the discrete model used to assimilate data from a linear partial differential equation (PDE) system is necessary and sufficient for asymptotic stability of the data assimilation process. The observability theory for discrete systems is reviewed and applied to obtain simple observability tests for discretized constant-coefficient PDEs. Examples are used to show how numerical dispersion can result in discrete dynamics with multiple eigenvalues, thereby detracting from observability.
SEA screening of voluntary climate change plans: A story of non-compliant discretion
Kørnøv, Lone Wejs, Anja
2013-07-15
Screening within Strategic Environmental Assessment (SEA) is the first critical stage involving considerations on whether an assessment is carried out or not. Although legislation and guidance offer practitioners a legal and logical approach to the screening process, it is inevitable that discretionary judgement takes place and will impact on the screening decision. This article examines the results of discretion involved in screening of climate change plans (CCPs) in a Danish context. These years voluntary CCPs are developed as a response to the global and local emergence of both mitigation and adaptation, and the voluntary commitment by the local authorities is an indication of an emerging norm of climate change as an important issue. This article takes its point of departure in the observation that SEA is not undertaken for these voluntary CCPs. The critical analysis of this phenomenon rests upon a documentary study of Danish CCPs, interviews with a lawyer and ministerial key person and informal discussions between researchers, practitioners and lawyers on whether climate change plans are covered by SEA legislation and underlying reasons for the present practice. Based on a critical analysis of mandatory SEA and/or obligation to screen CCPs according to significance criteria, the authors find that 18 out of the 48 CCPs are mandatory to SEA and 9 would require a screening of significance and thereby potentially be followed by a SEA. In practice only one plan was screened and one was environmentally assessed. The legal, democratic and environmental consequences of this SEA practice are critically discussed. Hereunder is the missed opportunity to use the broad environmental scope of SEA to avoid a narrow focus on energy and CO{sub 2} in CCPs, and the question whether this practice in Denmark complies with the EU Directive. -- Highlights: ► It is inevitable that discretionary judgement takes place and will impact on the screening decision. ► The article hereby
Umbral Deformations on Discrete SPACE TIME
NASA Astrophysics Data System (ADS)
Zachos, Cosmas K.
Given a minimum measurable length underlying spacetime, the latter may be effectively regarded as discrete, at scales of order the Planck length. A systematic discretization of continuum physics may be effected most efficiently through the umbral deformation. General functionals yielding such deformations at the level of solutions are furnished and illustrated, and broad features of discrete oscillations and wave propagation are outlined.
Autonomous and cooperative multi-UAV guidance in adversarial environment
NASA Astrophysics Data System (ADS)
Zengin, Ugur
The research presented in this dissertation is aimed at developing rule-based autonomous and cooperative guidance strategies for UAVs to perform missions such as path planning, target tracking and rendezvous while reducing their risk/threat exposure level, and avoiding threats and/or obstacles by utilizing measurement information provided by sensors. First, a mathematical formulation is developed to represent the area of operation that contains various types of threats, obstacles, and restricted areas, in a single framework. Once constructed, there will be no need to distinguish between threats, obstacles and restricted areas as the framework already contains the information on what needs to be avoided and the level of penalty for a given position in the area. This framework provides the mathematical foundation for the guidance strategies to make intelligent decisions during the execution of the mission and also provides scalar metrics to assess the performance of a guidance strategy in a given mission. The autonomous guidance strategies are developed by using a rule-based expert system approach with the requirements of completing assigned mission or task, avoiding obstacle/restricted-areas, minimizing threat exposure level, considering the dynamic and communication constraints of the UAVs and avoiding collision. All these requirements and objectives are quantified and prioritized to facilitate the development of guidance algorithms that can be executed in real-time. The strategies consist of a set of "decision states", which contain rules to determine how the host UAV should move by generating heading and speed signals. Cooperation of multiple UAVs is modeled by minimizing a cost function, which is constructed based on the level of threat exposure for each UAV and distance of each UAV relative to the target. This improves the performance of the system in the terms of increasing the total area of coverage of the sensors onboard the UAVs, increasing the flexibility
Chance-Constrained Guidance With Non-Convex Constraints
NASA Technical Reports Server (NTRS)
Ono, Masahiro
2011-01-01
Missions to small bodies, such as comets or asteroids, require autonomous guidance for descent to these small bodies. Such guidance is made challenging by uncertainty in the position and velocity of the spacecraft, as well as the uncertainty in the gravitational field around the small body. In addition, the requirement to avoid collision with the asteroid represents a non-convex constraint that means finding the optimal guidance trajectory, in general, is intractable. In this innovation, a new approach is proposed for chance-constrained optimal guidance with non-convex constraints. Chance-constrained guidance takes into account uncertainty so that the probability of collision is below a specified threshold. In this approach, a new bounding method has been developed to obtain a set of decomposed chance constraints that is a sufficient condition of the original chance constraint. The decomposition of the chance constraint enables its efficient evaluation, as well as the application of the branch and bound method. Branch and bound enables non-convex problems to be solved efficiently to global optimality. Considering the problem of finite-horizon robust optimal control of dynamic systems under Gaussian-distributed stochastic uncertainty, with state and control constraints, a discrete-time, continuous-state linear dynamics model is assumed. Gaussian-distributed stochastic uncertainty is a more natural model for exogenous disturbances such as wind gusts and turbulence than the previously studied set-bounded models. However, with stochastic uncertainty, it is often impossible to guarantee that state constraints are satisfied, because there is typically a non-zero probability of having a disturbance that is large enough to push the state out of the feasible region. An effective framework to address robustness with stochastic uncertainty is optimization with chance constraints. These require that the probability of violating the state constraints (i.e., the probability of
ACS Algorithm in Discrete Ordinates for Pressure Vessel Dosimetry
NASA Astrophysics Data System (ADS)
Walters, William; Haghighat, Alireza
2016-02-01
The Adaptive Collision Source (ACS) method can solve the Linear Boltzmann Equation (LBE) more efficiently by adaptation of the angular quadrature order. This is similar to, and essentially an extension of, the first collision source method. Previously, the ACS methodology has been implemented into the TITAN discrete ordinates code, and has shown speedups of 2-4 on a simple test problem, with very little loss of accuracy (within a provided adaptive tolerance). This work examines the use of the ACS method for a more realistic problem: pressure vessel dosimetry with the VENUS-2 MOX-fuelled reactor dosimetry benchmark. The ACS method proved to be able to obtain accurate results while being approximately twice as efficient as using a constant quadrature in a standard source iteration scheme.
Semaphorin7A: branching beyond axonal guidance and into immunity.
Garcia-Areas, Ramon; Libreros, Stephania; Iragavarapu-Charyulu, Vijaya
2013-12-01
Semaphorins are a family of proteins that were originally described for their role in axonal guidance. Studies now show that semaphorins encompass many physiological functions outside of the nervous system, including immune responses. Semaphorin7A (SEMA7A) belongs to the "immune" semaphorin group and has been shown to play a crucial role in regulating immune responses. In this review, we discuss the structure and function of SEMA7A as well as its role in innate and adaptive immunity [corrected].We further describe SEMA7A's involvement in inflammatory disease and its emergent role in cancer.
Semaphorin7A: branching beyond axonal guidance and into immunity
Garcia-Areas, Ramon; Libreros, Stephania
2014-01-01
Semaphorins are a family of proteins that were originally described for their role in axonal guidance. Studies now show that semaphorins encompass many physiological functions outside of the nervous system, including immune responses. Semaphorin7A (SEMA7A) belongs to the “immune” semaphorin group and has been shown to play a crucial role in regulating immune responses. In this review, we discuss the structure and function of SEMA7A as well as its role of SEMA7A in innate and adaptive immunity. We further describe SEMA7A’s involvement in inflammatory disease and its emergent role in cancer. PMID:24222277
Micro guidance and control synthesis: New components, architectures, and capabilities
NASA Technical Reports Server (NTRS)
Mettler, Edward; Hadaegh, Fred Y.
1993-01-01
New GN&C (guidance, navigation and control) system capabilities are shown to arise from component innovations that involve the synergistic use of microminiature sensors and actuators, microelectronics, and fiber optics. Micro-GN&C system and component concepts are defined that include micro-actuated adaptive optics, micromachined inertial sensors, fiber-optic data nets and light-power transmission, and VLSI microcomputers. The thesis is advanced that these micro-miniaturization products are capable of having a revolutionary impact on space missions and systems, and that GN&C is the pathfinder micro-technology application that can bring that about.
Adaptation and risk management
Preston, Benjamin L
2011-01-01
Adaptation assessment methods are compatible with the international risk management standard ISO:31000. Risk management approaches are increasingly being recommended for adaptation assessments at both national and local levels. Two orientations to assessments can commonly be identified: top-down and bottom-up, and prescriptive and diagnostic. Combinations of these orientations favor different types of assessments. The choice of orientation can be related to uncertainties in prediction and taking action, in the type of adaptation and in the degree of system stress. Adopting multiple viewpoints is to be encouraged, especially in complex situations. The bulk of current guidance material is consistent with top-down and predictive approaches, thus is most suitable for risk scoping and identification. Abroad range ofmaterial fromwithin and beyond the climate change literature can be used to select methods to be used in assessing and implementing adaptation. The framing of risk, correct formulation of the questions being investigated and assessment methodology are critical aspects of the scoping phase. Only when these issues have been addressed should be issue of specific methods and tools be addressed. The reorientation of adaptation from an assessment focused solely on anthropogenic climate change to broader issues of vulnerability/resilience, sustainable development and disaster risk, especially through a risk management framework, can draw from existing policy and management understanding in communities, professions and agencies, incorporating existing agendas, knowledge, risks, and issues they already face.
Flight Guidance System Requirements Specification
NASA Technical Reports Server (NTRS)
Miller, Steven P.; Tribble, Alan C.; Carlson, Timothy M.; Danielson, Eric J.
2003-01-01
This report describes a requirements specification written in the RSML-e language for the mode logic of a Flight Guidance System of a typical regional jet aircraft. This model was created as one of the first steps in a five-year project sponsored by the NASA Langley Research Center, Rockwell Collins Inc., and the Critical Systems Research Group of the University of Minnesota to develop new methods and tools to improve the safety of avionics designs. This model will be used to demonstrate the application of a variety of methods and techniques, including safety analysis of system and subsystem requirements, verification of key properties using theorem provers and model checkers, identification of potential sources mode confusion in system designs, partitioning of applications based on the criticality of system hazards, and autogeneration of avionics quality code. While this model is representative of the mode logic of a typical regional jet aircraft, it does not describe an actual or planned product. Several aspects of a full Flight Guidance System, such as recovery from failed sensors, have been omitted, and no claims are made regarding the accuracy or completeness of this specification.
Energy angular momentum closed-loop guidance
NASA Astrophysics Data System (ADS)
Patera, Russell P.
2015-03-01
A novel guidance algorithm for launch vehicle ascent to the desired mission orbit is proposed. The algorithm uses total specific energy and orbital angular momentum as new state vector parameters. These parameters are ideally suited for the ascent guidance task, since the guidance algorithm steers the launch vehicle along a pre-flight optimal trajectory in energy angular momentum space. The guidance algorithm targets apogee, perigee, inclination and right ascension of ascending node. Computational complexities are avoided by eliminating time in the guidance computation and replacing it with angular momentum magnitude. As a result, vehicle acceleration, mass, thrust, length of motor burns, and staging times are also eliminated from the pitch plane guidance calculations. The algorithm does not involve launch vehicle or target state propagation, which results in minimal computational effort. Proof of concept of the new algorithm is presented using several numerical examples that illustrate performance results.
Simulation of low thrust guidance problems
NASA Technical Reports Server (NTRS)
Dawkins, G. S.; Long, D.
1974-01-01
The determination of optimal rocket control profiles and the guidance procedures used to approximate these profiles have received much attention. Simple guidance procedures have sufficed for the Apollo flights. A modified version of the linear tangent guidance law is developed which can be used for a low-thrust orbital maneuvering system such as the space shuttle. The modification allows the estimation of gravity over long thrusting arcs which is necessary for low thrust systems.
Long-Term Stewardship Baseline Report and Transition Guidance
Kristofferson, Keith
2001-11-01
Long-term stewardship consists of those actions necessary to maintain and demonstrate continued protection of human health and the environment after facility cleanup is complete. As the Department of Energy’s (DOE) lead laboratory for environmental management programs, the Idaho National Engineering and Environmental Laboratory (INEEL) administers DOE’s long-term stewardship science and technology efforts. The INEEL provides DOE with technical, and scientific expertise needed to oversee its long-term environmental management obligations complexwide. Long-term stewardship is administered and overseen by the Environmental Management Office of Science and Technology. The INEEL Long-Term Stewardship Program is currently developing the management structures and plans to complete INEEL-specific, long-term stewardship obligations. This guidance document (1) assists in ensuring that the program leads transition planning for the INEEL with respect to facility and site areas and (2) describes the classes and types of criteria and data required to initiate transition for areas and sites where the facility mission has ended and cleanup is complete. Additionally, this document summarizes current information on INEEL facilities, structures, and release sites likely to enter long-term stewardship at the completion of DOE’s cleanup mission. This document is not intended to function as a discrete checklist or local procedure to determine readiness to transition. It is an overarching document meant as guidance in implementing specific transition procedures. Several documents formed the foundation upon which this guidance was developed. Principal among these documents was the Long-Term Stewardship Draft Technical Baseline; A Report to Congress on Long-Term Stewardship, Volumes I and II; Infrastructure Long-Range Plan; Comprehensive Facility Land Use Plan; INEEL End-State Plan; and INEEL Institutional Plan.
Multipulses in discrete Hamiltonian nonlinear systems.
Kevrekidis, P G
2001-08-01
In this work, the behavior of multipulses in discrete Hamiltonian nonlinear systems is investigated. The discrete nonlinear Schrödinger equation is used as the benchmark system for this study. A singular perturbation methodology as well as a variational approach are implemented in order to identify the dominant factors in the discrete problem. The results of the two methodologies are shown to coincide in assessing the interplay of discreteness and exponential tail-tail pulse interaction. They also allow one to understand why, contrary to what is believed for their continuum siblings, discrete systems can sustain (static) multipulse configurations, a conclusion that is subsequently verified by numerical experiment.
On equivalence of discrete-discrete and continuum-discrete design sensitivity analysis
NASA Technical Reports Server (NTRS)
Choi, Kyung K.; Twu, Sung-Ling
1989-01-01
Developments in design sensitivity analysis (DSA) method have been made using two fundamentally different approaches as shown. In the first approach, a discretized structural finite element model is used to carry out DSA. There are three different methods in the discrete DSA approach: finite difference, semi-analytical, and analytical methods. The finite difference method is a popular one due to its simplicity, but a serious shortcoming of the method is the uncertainty in the choice of a perturbation step size of design variables. In the semi-analytical method, the derivatives of stiffness matrix is computed by finite differences, whereas in the analytical method, the derivatives are obtained analytically. For the shape design variable, computation of analytical derivative of stiffness matrix is quite costly. Because of this, the semi-analytical method is a popular choice in discrete shape DSA approach. However, recently, Barthelemy and Haftka presented that the semi-analytical method can have serious accuracy problems for shape design variables in structures modeled by beam, plate, truss, frame, and solid elements. They found that accuracy problems occur even for a simple cantilever beam. In the second approach, a continuum model of the structure is used to carry out DSA.
Input-output identification of controlled discrete manufacturing systems
NASA Astrophysics Data System (ADS)
Estrada-Vargas, Ana Paula; López-Mellado, Ernesto; Lesage, Jean-Jacques
2014-03-01
The automated construction of discrete event models from observations of external system's behaviour is addressed. This problem, often referred to as system identification, allows obtaining models of ill-known (or even unknown) systems. In this article, an identification method for discrete event systems (DESs) controlled by a programmable logic controller is presented. The method allows processing a large quantity of observed long sequences of input/output signals generated by the controller and yields an interpreted Petri net model describing the closed-loop behaviour of the automated DESs. The proposed technique allows the identification of actual complex systems because it is sufficiently efficient and well adapted to cope with both the technological characteristics of industrial controllers and data collection requirements. Based on polynomial-time algorithms, the method is implemented as an efficient software tool which constructs and draws the model automatically; an overview of this tool is given through a case study dealing with an automated manufacturing system.
Nonconforming mortar element methods: Application to spectral discretizations
NASA Technical Reports Server (NTRS)
Maday, Yvon; Mavriplis, Cathy; Patera, Anthony
1988-01-01
Spectral element methods are p-type weighted residual techniques for partial differential equations that combine the generality of finite element methods with the accuracy of spectral methods. Presented here is a new nonconforming discretization which greatly improves the flexibility of the spectral element approach as regards automatic mesh generation and non-propagating local mesh refinement. The method is based on the introduction of an auxiliary mortar trace space, and constitutes a new approach to discretization-driven domain decomposition characterized by a clean decoupling of the local, structure-preserving residual evaluations and the transmission of boundary and continuity conditions. The flexibility of the mortar method is illustrated by several nonconforming adaptive Navier-Stokes calculations in complex geometry.
NASP guidance design for vehicle autonomy
NASA Astrophysics Data System (ADS)
Wagner, E. A.; Li, I.; Nguyen, D. D.; Nguyen, P. L.
1990-10-01
Vehicle guidance for General Dynamics' NASP vehicle is planned to be self-contained onboard the vehicle, and independent of any ground support during the mission. It will include real-time onboard abort and ascent trajectory optimization capability. Although these features should be considered a natural outgrowth of research in guidance and trajectory optimization and advances in computation, facilitating full vehicle autonomy for NASP represents a significant advance relative to any flight-demonstrated guidance. Algorithms and processing requirements for autonomous NASP vehicle guidance are considered.
Virtual Ultrasound Guidance for Inexperienced Operators
NASA Technical Reports Server (NTRS)
Caine, Timothy; Martin, Davis
2012-01-01
Medical ultrasound or echocardiographic studies are highly operator-dependent and generally require lengthy training and internship to perfect. To obtain quality echocardiographic images in remote environments, such as on-orbit, remote guidance of studies has been employed. This technique involves minimal training for the user, coupled with remote guidance from an expert. When real-time communication or expert guidance is not available, a more autonomous system of guiding an inexperienced operator through an ultrasound study is needed. One example would be missions beyond low Earth orbit, in which the time delay inherent with communication will make remote guidance impractical.
A semi-analytical guidance algorithm for autonomous landing
NASA Astrophysics Data System (ADS)
Lunghi, Paolo; Lavagna, Michèle; Armellin, Roberto
2015-06-01
One of the main challenges posed by the next space systems generation is the high level of autonomy they will require. Hazard Detection and Avoidance is a key technology in this context. An adaptive guidance algorithm for landing that updates the trajectory to the surface by means of an optimal control problem solving is here presented. A semi-analytical approach is proposed. The trajectory is expressed in a polynomial form of minimum order to satisfy a set of boundary constraints derived from initial and final states and attitude requirements. By imposing boundary conditions, a fully determined guidance profile is obtained, function of a restricted set of parameters. The guidance computation is reduced to the determination of these parameters in order to satisfy path constraints and other additional constraints not implicitly satisfied by the polynomial formulation. The algorithm is applied to two different scenarios, a lunar landing and an asteroidal landing, to highlight its general validity. An extensive Monte Carlo test campaign is conducted to verify the versatility of the algorithm in realistic cases, by the introduction of attitude control systems, thrust modulation, and navigation errors. The proposed approach proved to be flexible and accurate, granting a precision of a few meters at touchdown.
Federal Guidance Report No. 8: Guidance for the Control of Radiation Hazards in Uranium Mining
This report contains background material used in the development of guidance concerning radiation protection in the mining of uranium ore, and seeks to provide guidance for long-term radiation protection in uranium mining.
Evaluation of an optimal aerocapture guidance algorithm for human Mars missions
NASA Astrophysics Data System (ADS)
Webb, Kyle
Aeroassist guidance is concerned with providing steering commands to a vehicle flying through a planetary atmosphere in the form of an aerodynamic roll angle, or bank angle, which results in appropriate direction of the aerodynamic lift force so that the vehicle will safely and accurately reach its designated final condition. Aerocapture guidance is a particular subcategory of aeroassist guidance that involves atmospheric entry from an interplanetary transfer orbit, a guided flight through the atmosphere, and a final condition consisting of a post-atmospheric exit target orbit around the planet. Using aerocapture guidance to establish this target orbit can provide significant propellant mass savings when compared to traditional propulsive maneuvers. No current aerocapture guidance algorithms can ensure truly optimal performance in minimizing post-exit orbit insertion ?V requirements. This thesis investigates the development of a two-phase optimal aerocapture guidance algorithm. This closed-loop guidance algorithm uses a mathematically optimal bang-bang bank angle profile structure, in which a vehicle first flies with the lift vector pointed straight up, and then flies full lift-down until atmospheric exit. The optimal trajectory is found by determining the switching time between full lift-up and full lift-down flight. Results from testing the algorithm in a high-fidelity NASA simulation environment are presented and compared with results from existing state-of-the-art aerocapture guidance algorithms. These results show that the developed algorithm provides the robustness and adaptability of a numerical predictor-corrector guidance algorithm while demonstrating a significant reduction in ?V requirements compared to other existing algorithms.
Adaptation as process: the future of Darwinism and the legacy of Theodosius Dobzhansky.
Depew, David J
2011-03-01
Conceptions of adaptation have varied in the history of genetic Darwinism depending on whether what is taken to be focal is the process of adaptation, adapted states of populations, or discrete adaptations in individual organisms. I argue that Theodosius Dobzhansky's view of adaptation as a dynamical process contrasts with so-called "adaptationist" views of natural selection figured as "design-without-a-designer" of relatively discrete, enumerable adaptations. Correlated with these respectively process and product oriented approaches to adaptive natural selection are divergent pictures of organisms themselves as developmental wholes or as "bundles" of adaptations. While even process versions of genetical Darwinism are insufficiently sensitive to the fact much of the variation on which adaptive selection works consists of changes in the timing, rate, or location of ontogenetic events, I argue that articulations of the Modern Synthesis influenced by Dobzhansky are more easily reconciled with the recent shift to evolutionary developmentalism than are versions that make discrete adaptations central.
ERIC Educational Resources Information Center
Goldberg, Michael R.; Dill, Charles A.; Shin, Jin Y.; Nhan, Nguyen Viet
2009-01-01
This study was conducted to examine an adaptation of the Vineland Adaptive Behavior Scale (VABS) [Sparrow, S. S., Balla, D. A., & Cicchetti, D. V. (1984). "The Vineland Adaptive Behavior Scales." Circle Pines, MN: America Guidance Service; Sparrow, S. S., Balla, D. A., & Cicchetti, D. V. (2005). "Vineland Adaptive Behavior…
Longwall Guidance and Control Development
NASA Technical Reports Server (NTRS)
1982-01-01
The longwall guidance and control (G&C) system was evaluated to determine which systems and subsystems lent themselves to automatic control in the mining of coal. The upper coal/shale interface was identified as the reference for a vertical G&C system, with two sensors (the natural backgound and the sensitized pick) being used to locate and track this boundary. In order to insure a relatively smooth recession surface (roof and floor of the excavated seam), a last and present cut measuring instrument (acoustic sensor) was used. Potentiometers were used to measure elevations of the shearer arms. The intergration of these components comprised the vertical control system (pitch control). Yaw and roll control were incorporated into a face alignment system which was designed to keep the coal face normal to its external boundaries. Numerous tests, in the laboratory and in the field, have confirmed the feasibility of automatic horizon control, as well as determining the face alignment.
Orion Cislunar Guidance and Navigation
NASA Technical Reports Server (NTRS)
D'Souza, Christopher; Crain, Timothy; Clark, Fred C.
2007-01-01
The Orion vehicle is being designed to provide nominal crew transport to the lunar transportation stack in low Earth orbit, crew abort prior during transit to the moon, and crew return to Earth once lunar orbit is achieved. Design of guidance and navigation algorithms to perform maneuvers in support of these functions is dependent on the support provided by navigation infrastructure, the performance of the onboard GN&C system, and the choice of trajectory maneuver methodology for outbound and return mission phases. This paper documents the preliminary integrated analyses performed by members of the Orion Orbit GN&C System team investigating the navigation update accuracy of a modern equivalent to the Apollo era ground tracking network and the expected onboard dispersion and navigation errors during a lunar mission using a linear covariance error analysis technique.
Aerocapture - Guidance, navigation, and control
NASA Astrophysics Data System (ADS)
Mease, K. D.; Weidner, R. J.; Kechichian, J. A.; Wood, L. J.; Cruz, M. I.
1982-08-01
Aerocapture is a concept for inserting a spacecraft into orbit about a target planet. The energy required for orbit insertion is obtained from natural resources present at or near the target body, thereby reducing the amount of propellant which must be carried onboard. Specifically, the transfer from a hyperbolic flyby trajectory to a desired bound orbit is effected by aerodynamic lift and drag forces acting on the spacecraft during controlled flight through the atmosphere of either the target planet or a nearby satellite. A survey is provided of the trajectory guidance, navigation, and control aspects of aerocapture, and a summary is given of the results of a number of preliminary studies concerning certain of these aspects. The investigation has additional significance in connection with the current interest in aeroassisted orbital transfer vehicles, which may be used in conjunction with the Space Shuttle.
Aerocapture - Guidance, navigation, and control
NASA Technical Reports Server (NTRS)
Mease, K. D.; Weidner, R. J.; Kechichian, J. A.; Wood, L. J.; Cruz, M. I.
1982-01-01
Aerocapture is a concept for inserting a spacecraft into orbit about a target planet. The energy required for orbit insertion is obtained from natural resources present at or near the target body, thereby reducing the amount of propellant which must be carried onboard. Specifically, the transfer from a hyperbolic flyby trajectory to a desired bound orbit is effected by aerodynamic lift and drag forces acting on the spacecraft during controlled flight through the atmosphere of either the target planet or a nearby satellite. A survey is provided of the trajectory guidance, navigation, and control aspects of aerocapture, and a summary is given of the results of a number of preliminary studies concerning certain of these aspects. The investigation has additional significance in connection with the current interest in aeroassisted orbital transfer vehicles, which may be used in conjunction with the Space Shuttle.
Endangerment assessment guidance. Final report
Not Available
1985-10-21
The directive clarifies the requirement that an endangerment assessment be developed to support all administrative and judicial enforcement actions under Section 106 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Section 7003 of the Resource Conservation and Recovery Act (RCRA). Before taking enforcement action under these provisions to abate the hazards or potential hazards at a site, the Environmental Protection Agency (EPA) must be able to properly document and justify its assertion that an imminent and substantial endangerment to public health or welfare or the environment may exist. The endangerment assessment provides the documentation and justification. The endangerment assessment is not necessary to support Section 104 actions. It also provides guidance on the content, timing, level of detail, format, and resources required for the preparation of endangerment assessments.
Invariants of broken discrete symmetries.
Kalozoumis, P A; Morfonios, C; Diakonos, F K; Schmelcher, P
2014-08-01
The parity and Bloch theorems are generalized to the case of broken global symmetry. Local inversion or translation symmetries in one dimension are shown to yield invariant currents that characterize wave propagation. These currents map the wave function from an arbitrary spatial domain to any symmetry-related domain. Our approach addresses any combination of local symmetries, thus applying, in particular, to acoustic, optical, and matter waves. Nonvanishing values of the invariant currents provide a systematic pathway to the breaking of discrete global symmetries.
Invariants of Broken Discrete Symmetries
NASA Astrophysics Data System (ADS)
Kalozoumis, P. A.; Morfonios, C.; Diakonos, F. K.; Schmelcher, P.
2014-08-01
The parity and Bloch theorems are generalized to the case of broken global symmetry. Local inversion or translation symmetries in one dimension are shown to yield invariant currents that characterize wave propagation. These currents map the wave function from an arbitrary spatial domain to any symmetry-related domain. Our approach addresses any combination of local symmetries, thus applying, in particular, to acoustic, optical, and matter waves. Nonvanishing values of the invariant currents provide a systematic pathway to the breaking of discrete global symmetries.
Guidance, Navigation, and Control Program
NASA Technical Reports Server (NTRS)
Hinkel, Heather; Tamblyn, Scott; Jackson, William L.; Foster, Chris; Brazzel, Jack; Manning, Thomas R.; Clark, Fred; Spehar, Pete; Barrett, Jim D.; Milenkovic, Zoran
2011-01-01
The Rendezvous and Proximity Operations Program (RPOP) is real-time guidance, navigation, and control (GN&C) domain piloting-aid software that provides 3D Orbiter graphics and runs on the Space Shuttle's Criticality-3 Payload and General Support Computer (PGSC) in the crew cockpit. This software provides the crew with Situational Awareness during the rendezvous and proximity operations phases of flight. RPOP can be configured from flight to flight, accounting for mission-specific flight scenarios and target vehicles, via initialization load (I-load) data files. The software provides real-time, automated, closed-loop guidance recommendations and the capability to integrate the crew s manual backup techniques. The software can bring all relative navigation sensor data, including the Orbiter's GPC (general purpose computer) data, into one central application to provide comprehensive situational awareness of the rendezvous and proximity operations trajectory. RPOP also can separately maintain trajectory estimates (past, current, and predicted) based on certain data types and co-plot them, in order to show how the various navigation solutions compare. RPOP s best estimate of the relative trajectory is determined by a relative Kalman filter processing data provided by the sensor suite s most accurate sensor, the trajectory control sensor (TCS). Integrated with the Kalman filter is an algorithm that identifies the reflector that the TCS is tracking. Because RPOP runs on PC laptop computers, the development and certification lifecycles are more agile, flexible, and cheaper than those that govern the Orbiter FSW (flight software) that runs in the GPC. New releases of RPOP can be turned around on a 3- to 6-month template, from new Change Request (CR) to certification, depending on the complexity of the changes.
Federal Register 2010, 2011, 2012, 2013, 2014
2013-08-07
... to the pharmaceutical industry. In most cases, FDA has developed other guidances and resources to... guidances: 1. ``Manufacturing, Processing, or Holding Active Pharmaceutical Ingredients''--issued April 1998... guidances (number 19 through 22), contact the Office of Pharmaceutical Science in CDER. 23. ``Qualifying...
Adaptive Algebraic Multigrid Methods
Brezina, M; Falgout, R; MacLachlan, S; Manteuffel, T; McCormick, S; Ruge, J
2004-04-09
Our ability to simulate physical processes numerically is constrained by our ability to solve the resulting linear systems, prompting substantial research into the development of multiscale iterative methods capable of solving these linear systems with an optimal amount of effort. Overcoming the limitations of geometric multigrid methods to simple geometries and differential equations, algebraic multigrid methods construct the multigrid hierarchy based only on the given matrix. While this allows for efficient black-box solution of the linear systems associated with discretizations of many elliptic differential equations, it also results in a lack of robustness due to assumptions made on the near-null spaces of these matrices. This paper introduces an extension to algebraic multigrid methods that removes the need to make such assumptions by utilizing an adaptive process. The principles which guide the adaptivity are highlighted, as well as their application to algebraic multigrid solution of certain symmetric positive-definite linear systems.
Getting Closer: Workplace Guidance for Lifelong Learning
ERIC Educational Resources Information Center
Plant, Peter; Turner, Bob
2005-01-01
The purposes of this article are twofold. First, it considers the policy links between guidance and lifelong learning, highlighting in particular the implications of findings from a recent study by the Organisation for Economic Co-operation and Development (OECD). Secondly, it critically compares two approaches to workplace guidance about…
Social Benefits of Career Guidance. NICEC Briefing.
ERIC Educational Resources Information Center
Killeen, John; Watts, Tony; Kidd, Jenny
Social benefits can be thought of as aggregates of individual benefits, though with possible "snowball" effects. Potential social benefits of career guidance fall into the following two main categories: reducing social exclusion and enhancing social development. Guidance is a way of making the structure of society work, by linking…
Elementary School Guidance Work Conference. Conference Report.
ERIC Educational Resources Information Center
Herr, Edwin L.; Hershberger, James K.
In October, 1967, 100 invited participants representing all aspects of guidance, education, school administration, counselor education, psychology, and interested government agencies in Pennsylvania met for three days to listen, think, discuss, and hopefully develop some recommendations for those who want a better program of elementary guidance.…
Foundations for Policy in Guidance and Counseling.
ERIC Educational Resources Information Center
Herr, Edwin L., Ed.; Pinson, Nancy M., Ed.
This book provides educators, counselors, policy makers, and community members with information about the state of the art of federal and state policy in guidance and counseling. The two chapters in part 1, Overview, are: "Foundations for Policy in Guidance and Counseling: An Introduction", by Edwin L. Herr and Nancy M. Pinson; and "A Counselor…
Career Guidance and Public Mental Health
ERIC Educational Resources Information Center
Robertson, Peter J.
2013-01-01
Career guidance may have the potential to promote public health by contributing positively to both the prevention of mental health conditions and to population level well-being. The policy implications of this possibility have received little attention. Career guidance agencies are well placed to reach key target groups. Producing persuasive…
Guidance trajectories for aeroassisted orbital transfer
NASA Technical Reports Server (NTRS)
Miele, A.
1990-01-01
Research on aerobraking guidance schemes is presented. The intent is to produce aerobraking guidance trajectories exhibiting many of the desirable characteristics of optimal aerobraking trajectories. Both one-control schemes and two-control schemes are studied. The research is in the interest of aeroassisted flight experiment vehicles (AFE) and aeroassisted orbital transfer (AOT) vehicles.
Guidance in Adult and Continuing Education.
ERIC Educational Resources Information Center
McNamara, Gerry
The provision of guidance in adult and continuing education in Ireland was examined. First, policy in Ireland regarding guidance for adults in education is discussed in the context of the proposals adopted by the European Union (EU) Commission and EU Member States pursuant to the EU Year of Lifelong Learning in 1996. Recent literature on career…
48 CFR 427.104 - General guidance.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false General guidance. 427.104 Section 427.104 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS General 427.104 General guidance. As used in FAR part 27, the...
48 CFR 27.102 - General guidance.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false General guidance. 27.102 Section 27.102 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS General 27.102 General guidance. (a) The Government encourages...
48 CFR 27.102 - General guidance.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false General guidance. 27.102 Section 27.102 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS General 27.102 General guidance. (a) The Government encourages...
48 CFR 27.102 - General guidance.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false General guidance. 27.102 Section 27.102 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION GENERAL CONTRACTING REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS General 27.102 General guidance. (a) The Government encourages...
21 CFR 312.145 - Guidance documents.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Guidance documents. 312.145 Section 312.145 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DRUGS FOR HUMAN USE INVESTIGATIONAL NEW DRUG APPLICATION Miscellaneous § 312.145 Guidance documents. (a) FDA...
Guidance for performing preliminary assessments under CERCLA
1991-09-01
EPA headquarters and a national site assessment workgroup produced this guidance for Regional, State, and contractor staff who manage or perform preliminary assessments (PAs). EPA has focused this guidance on the types of sites and site conditions most commonly encountered. The PA approach described in this guidance is generally applicable to a wide variety of sites. However, because of the variability among sites, the amount of information available, and the level of investigative effort required, it is not possible to provide guidance that is equally applicable to all sites. PA investigators should recognize this and be aware that variation from this guidance may be necessary for some sites, particularly for PAs performed at Federal facilities, PAs conducted under EPA`s Environmental Priorities Initiative (EPI), and PAs at sites that have previously been extensively investigated by EPA or others. The purpose of this guidance is to provide instructions for conducting a PA and reporting results. This guidance discusses the information required to evaluate a site and how to obtain it, how to score a site, and reporting requirements. This document also provides guidelines and instruction on PA evaluation, scoring, and the use of standard PA scoresheets. The overall goal of this guidance is to assist PA investigators in conducting high-quality assessments that result in correct site screening or further action recommendations on a nationally consistent basis.
77 FR 48591 - State Rail Plan Guidance
Federal Register 2010, 2011, 2012, 2013, 2014
2012-08-14
... Federal Railroad Administration State Rail Plan Guidance AGENCY: Federal Railroad Administration (FRA), Department of Transportation (DOT). ACTION: Request for Public Comment on Proposed State Rail Plan Guidance..., submission, and acceptance of State rail plans. State rail plans are documents that are required...
Gifted Child Development and Guidance Study.
ERIC Educational Resources Information Center
Virginia Beach City Public Schools, VA.
The Gifted Child Development and Guidance Program of Virginia Beach City (Virginia) Public Schools was developed to interest gifted college-bound students in a vocational class in child development and guidance that might lead to further career interest in child-related professions. This report briefly describes program promotion; student…
Supervised Discrete Hashing With Relaxation.
Gui, Jie; Liu, Tongliang; Sun, Zhenan; Tao, Dacheng; Tan, Tieniu
2016-12-29
Data-dependent hashing has recently attracted attention due to being able to support efficient retrieval and storage of high-dimensional data, such as documents, images, and videos. In this paper, we propose a novel learning-based hashing method called ''supervised discrete hashing with relaxation'' (SDHR) based on ''supervised discrete hashing'' (SDH). SDH uses ordinary least squares regression and traditional zero-one matrix encoding of class label information as the regression target (code words), thus fixing the regression target. In SDHR, the regression target is instead optimized. The optimized regression target matrix satisfies a large margin constraint for correct classification of each example. Compared with SDH, which uses the traditional zero-one matrix, SDHR utilizes the learned regression target matrix and, therefore, more accurately measures the classification error of the regression model and is more flexible. As expected, SDHR generally outperforms SDH. Experimental results on two large-scale image data sets (CIFAR-10 and MNIST) and a large-scale and challenging face data set (FRGC) demonstrate the effectiveness and efficiency of SDHR.
Entwinement in discretely gauged theories
NASA Astrophysics Data System (ADS)
Balasubramanian, V.; Bernamonti, A.; Craps, B.; De Jonckheere, T.; Galli, F.
2016-12-01
We develop the notion of "entwinement" to characterize the amount of quantum entanglement between internal, discretely gauged degrees of freedom in a quantum field theory. This concept originated in the program of reconstructing spacetime from entanglement in holographic duality. We define entwinement formally in terms of a novel replica method which uses twist operators charged in a representation of the discrete gauge group. In terms of these twist operators we define a non-local, gauge-invariant object whose expectation value computes entwinement in a standard replica limit. We apply our method to the computation of entwinement in symmetric orbifold conformal field theories in 1+1 dimensions, which have an S N gauging. Such a theory appears in the weak coupling limit of the D1-D5 string theory which is dual to AdS3 at strong coupling. In this context, we show how certain kinds of entwinement measure the lengths, in units of the AdS scale, of non-minimal geodesics present in certain excited states of the system which are gravitationally described as conical defects and the M = 0 BTZ black hole. The possible types of entwinement that can be computed define a very large new class of quantities characterizing the fine structure of quantum wavefunctions.
Discreteness effects in population dynamics
NASA Astrophysics Data System (ADS)
Guevara Hidalgo, Esteban; Lecomte, Vivien
2016-05-01
We analyse numerically the effects of small population size in the initial transient regime of a simple example population dynamics. These effects play an important role for the numerical determination of large deviation functions of additive observables for stochastic processes. A method commonly used in order to determine such functions is the so-called cloning algorithm which in its non-constant population version essentially reduces to the determination of the growth rate of a population, averaged over many realizations of the dynamics. However, the averaging of populations is highly dependent not only on the number of realizations of the population dynamics, and on the initial population size but also on the cut-off time (or population) considered to stop their numerical evolution. This may result in an over-influence of discreteness effects at initial times, caused by small population size. We overcome these effects by introducing a (realization-dependent) time delay in the evolution of populations, additional to the discarding of the initial transient regime of the population growth where these discreteness effects are strong. We show that the improvement in the estimation of the large deviation function comes precisely from these two main contributions.
Advances in Orion's On-Orbit Guidance and Targeting System Architecture
NASA Technical Reports Server (NTRS)
Scarritt, Sara K.; Fill, Thomas; Robinson, Shane
2015-01-01
NASA's manned spaceflight programs have a rich history of advancing onboard guidance and targeting technology. In order to support future missions, the guidance and targeting architecture for the Orion Multi-Purpose Crew Vehicle must be able to operate in complete autonomy, without any support from the ground. Orion's guidance and targeting system must be sufficiently flexible to easily adapt to a wide array of undecided future missions, yet also not cause an undue computational burden on the flight computer. This presents a unique design challenge from the perspective of both algorithm development and system architecture construction. The present work shows how Orion's guidance and targeting system addresses these challenges. On the algorithm side, the system advances the state-of-the-art by: (1) steering burns with a simple closed-loop guidance strategy based on Shuttle heritage, and (2) planning maneuvers with a cutting-edge two-level targeting routine. These algorithms are then placed into an architecture designed to leverage the advantages of each and ensure that they function in concert with one another. The resulting system is characterized by modularity and simplicity. As such, it is adaptable to the on-orbit phases of any future mission that Orion may attempt.
78 FR 67442 - Congestion Mitigation and Air Quality Improvement Program Interim Guidance
Federal Register 2010, 2011, 2012, 2013, 2014
2013-11-12
... Federal Highway Administration Congestion Mitigation and Air Quality Improvement Program Interim Guidance... Mitigation and Air Quality Improvement (CMAQ) Program (Interim Guidance). The Interim Guidance revises CMAQ....gov/environment/air_quality/cmaq/policy_and_guidance/2008_guidance/ guidance/. DATES: This...
Adaptivity in space and time for shallow water equations
NASA Astrophysics Data System (ADS)
Morandi Cecchi, M.; Marcuzzi, F.
1999-09-01
In this paper, adaptive algorithms for time and space discretizations are added to an existing solution method previously applied to the Venice Lagoon Tidal Circulation problem. An analysis of the interactions between space and time discretizations adaptation algorithms is presented. In particular, it turns out that both error estimations in space and time must be present for maintaining the adaptation efficiency. Several advantages, for adaptivity and for time decoupling of the equations, offered by the operator-splitting adopted for shallow water equations solution are presented. Copyright
Pollen tube guidance by attractant molecules: LUREs.
Okuda, Satohiro; Higashiyama, Tetsuya
2010-01-01
Sexual reproduction in flowering plants requires pollen-tube guidance, which is thought to be mediated by chemoattractants derived from target ovules. To date, however, no convincing evidence has been reported of a particular molecule being the true attractant. Emerging data indicate that two synergid cells, which are on either side of the egg cell, emit a diffusible, species-specific signal to attract the pollen tube at the last step of pollen-tube guidance. Recently, it was demonstrated that LUREs (LURE1 and LURE2), cysteine-rich polypeptides secreted from the synergid cell, are the key molecules in pollen-tube guidance. In this review, we summarize the mechanism of pollen-tube guidance, with special focus on gametophytic guidance and the attractants.
Approach guidance for outer planet pioneer missions
NASA Technical Reports Server (NTRS)
Bejczy, A. K.
1975-01-01
Onboard optical approach guidance measurements for spin-stabilized Pioneer-type spacecraft are discussed. Approach guidance measurement accuracy requirements are outlined. The application concept and operation principle of the V-slit star tracker are discussed within the context of approach guidance measurements and measurables. It is shown that the accuracy of onboard optical approach guidance measurements is inherently coupled to the stability characteristics of the spacecraft spin axis. Geometrical and physical measurement parameters are presented for Pioneer entry probe missions to Uranus via Jupiter or Saturn flyby. The impact of these parameters on both sensor instrumentation and measurement system design is discussed. The need for sensing extended objects is shown. The feasibility of implementing an onboard approach guidance measurement system for Pioneer-type spacecraft is indicated. Two Pioneer 10 onboard measurement experiments performed in May-June 1974 are described.
Webster, Michael A.
2015-01-01
Sensory systems continuously mold themselves to the widely varying contexts in which they must operate. Studies of these adaptations have played a long and central role in vision science. In part this is because the specific adaptations remain a powerful tool for dissecting vision, by exposing the mechanisms that are adapting. That is, “if it adapts, it's there.” Many insights about vision have come from using adaptation in this way, as a method. A second important trend has been the realization that the processes of adaptation are themselves essential to how vision works, and thus are likely to operate at all levels. That is, “if it's there, it adapts.” This has focused interest on the mechanisms of adaptation as the target rather than the probe. Together both approaches have led to an emerging insight of adaptation as a fundamental and ubiquitous coding strategy impacting all aspects of how we see. PMID:26858985
Entry Guidance for the Reusable Launch Vehicle
NASA Technical Reports Server (NTRS)
Lu, Ping
1999-01-01
The X-33 Advanced Technology Demonstrator is a half-scale prototype developed to test the key technologies needed for a full-scale single-stage reusable launch vehicle (RLV). The X-33 is a suborbital vehicle that will be launched vertically, and land horizontally. The goals of this research were to develop an alternate entry guidance scheme for the X-33 in parallel to the actual X-33 entry guidance algorithms, provide comparative and complementary study, and identify potential new ways to improve entry guidance performance. Toward these goals, the nominal entry trajectory is defined by a piecewise linear drag-acceleration-versus-energy profile, which is in turn obtained by the solution of a semi-analytical parameter optimization problem. The closed-loop guidance is accomplished by tracking the nominal drag profile with primarily bank-angle modulation on-board. The bank-angle is commanded by a single full-envelope nonlinear trajectory control law. Near the end of the entry flight, the guidance logic is switched to heading control in order to meet strict conditions at the terminal area energy management interface. Two methods, one on ground-track control and the other on heading control, were proposed and examined for this phase of entry guidance where lateral control is emphasized. Trajectory dispersion studies were performed to evaluate the effectiveness of the entry guidance algorithms against a number of uncertainties including those in propulsion system, atmospheric properties, winds, aerodynamics, and propellant loading. Finally, a new trajectory-regulation method is introduced at the end as a promising precision entry guidance method. The guidance principle is very different and preliminary application in X-33 entry guidance simulation showed high precision that is difficult to achieve by existing methods.
Acquiring case adaptation knowledge: A hybrid approach
Leake, D.B.; Kinley, A.; Wilson, D.
1996-12-31
The ability of case-based reasoning (CBR) systems to apply cases to novel situations depends on their case adaptation knowledge. However, endowing CBR systems with adequate adaptation knowledge has proven to be a very difficult task. This paper describes a hybrid method for performing case adaptation, using a combination of rule-based and case-based reasoning. It shows how this approach provides a framework for acquiring flexible adaptation knowledge from experiences with autonomous adaptation and suggests its potential as a basis for acquisition of adaptation knowledge from interactive user guidance. It also presents initial experimental results examining the benefits of the approach and comparing the relative contributions of case learning and adaptation learning to reasoning performance.
A homogenization-based quasi-discrete method for the fracture of heterogeneous materials
NASA Astrophysics Data System (ADS)
Berke, P. Z.; Peerlings, R. H. J.; Massart, T. J.; Geers, M. G. D.
2014-05-01
The understanding and the prediction of the failure behaviour of materials with pronounced microstructural effects is of crucial importance. This paper presents a novel computational methodology for the handling of fracture on the basis of the microscale behaviour. The basic principles presented here allow the incorporation of an adaptive discretization scheme of the structure as a function of the evolution of strain localization in the underlying microstructure. The proposed quasi-discrete methodology bridges two scales: the scale of the material microstructure, modelled with a continuum type description; and the structural scale, where a discrete description of the material is adopted. The damaging material at the structural scale is divided into unit volumes, called cells, which are represented as a discrete network of points. The scale transition is inspired by computational homogenization techniques; however it does not rely on classical averaging theorems. The structural discrete equilibrium problem is formulated in terms of the underlying fine scale computations. Particular boundary conditions are developed on the scale of the material microstructure to address damage localization problems. The performance of this quasi-discrete method with the enhanced boundary conditions is assessed using different computational test cases. The predictions of the quasi-discrete scheme agree well with reference solutions obtained through direct numerical simulations, both in terms of crack patterns and load versus displacement responses.
Ideal shrinking and expansion of discrete sequences
NASA Technical Reports Server (NTRS)
Watson, Andrew B.
1986-01-01
Ideal methods are described for shrinking or expanding a discrete sequence, image, or image sequence. The methods are ideal in the sense that they preserve the frequency spectrum of the input up to the Nyquist limit of the input or output, whichever is smaller. Fast implementations that make use of the discrete Fourier transform or the discrete Hartley transform are described. The techniques lead to a new multiresolution image pyramid.
Preston, Benjamin L; Westaway, Richard M.; Yuen, Emma J.
2011-04-01
Formal planning for climate change adaptation is emerging rapidly at a range of geo-political scales. This first generation of adaptation plans provides useful information regarding how institutions are framing the issue of adaptation and the range of processes that are recognized as being part of an adaptation response. To better understand adaptation planning among developed nations, a set of 57 adaptation plans from Australia, the United Kingdom and the United States was evaluated against a suite of 19 planning processes identified from existing guidance instruments for adaptation planning. Total scores among evaluated plans ranged from 16% of the maximum possible score to 61%, with an average of 37%. These results suggest adaptation plans are largely under-developed. Critical weaknesses in adaptation planning are related to limited consideration for non-climatic factors as well as neglect for issues of adaptive capacity including entitlements to various forms of capital needed for effective adaptation. Such gaps in planning suggest there are opportunities for institutions to make better use of existing guidance for adaptation planning and the need to consider the broader governance context in which adaptation will occur. In addition, the adaptation options prescribed by adaptation plans reflect a preferential bias toward low-risk capacity-building (72% of identified options) over the delivery of specific actions to reduce vulnerability. To the extent these findings are representative of the state of developed nation adaptation planning, there appear to be significant deficiencies in climate change preparedness, even among those nations often assumed to have the greatest adaptive capacity.
A Comparison of Error-Correction Procedures on Skill Acquisition during Discrete-Trial Instruction
ERIC Educational Resources Information Center
Carroll, Regina A.; Joachim, Brad T.; St. Peter, Claire C.; Robinson, Nicole
2015-01-01
Previous research supports the use of a variety of error-correction procedures to facilitate skill acquisition during discrete-trial instruction. We used an adapted alternating treatments design to compare the effects of 4 commonly used error-correction procedures on skill acquisition for 2 children with attention deficit hyperactivity disorder…
A discrete event method for wave simulation
Nutaro, James J
2006-01-01
This article describes a discrete event interpretation of the finite difference time domain (FDTD) and digital wave guide network (DWN) wave simulation schemes. The discrete event method is formalized using the discrete event system specification (DEVS). The scheme is shown to have errors that are proportional to the resolution of the spatial grid. A numerical example demonstrates the relative efficiency of the scheme with respect to FDTD and DWN schemes. The potential for the discrete event scheme to reduce numerical dispersion and attenuation errors is discussed.
Discrete gauge symmetry in continuum theories
Krauss, L.M.; Wilczek, F.
1989-03-13
We point out that local symmetries can masquerade as discrete global symmetries to an observer equipped with only low-energy probes. The existence of the underlying local gauge invariance can, however, result in observable Aharonov-Bohm-type effects. Black holes can therefore carry discrete gauge charges: a form of nonclassical ''hair.'' Neither black-hole evaporation, wormholes, nor anything else can violate discrete gauge symmetries. In supersymmetric unified theories such discrete symmetries can forbid proton-decay amplitudes that might otherwise be catastrophic.
Scalar discrete nonlinear multipoint boundary value problems
NASA Astrophysics Data System (ADS)
Rodriguez, Jesus; Taylor, Padraic
2007-06-01
In this paper we provide sufficient conditions for the existence of solutions to scalar discrete nonlinear multipoint boundary value problems. By allowing more general boundary conditions and by imposing less restrictions on the nonlinearities, we obtain results that extend previous work in the area of discrete boundary value problems [Debra L. Etheridge, Jesus Rodriguez, Periodic solutions of nonlinear discrete-time systems, Appl. Anal. 62 (1996) 119-137; Debra L. Etheridge, Jesus Rodriguez, Scalar discrete nonlinear two-point boundary value problems, J. Difference Equ. Appl. 4 (1998) 127-144].
Discrete wave mechanics: An introduction
Wall, Frederick T.
1986-01-01
Discrete wave mechanics is formulated for particles in one-dimensional systems by use of a simple finite difference equation. The solutions involve wave vectors (instead of wave functions) as well as a newly defined “wave vector energy.” In the limit, as c → ∞, the treatment reduces to that of Schrödinger's wave mechanics. Specific calculations are made for completely free particles as well as for particles confined to a one-dimensional box. The results exhibit a striking compatibility with relativistic considerations. The wave vectors show properties that can be identified with particles and anti-particles—each possess identical probability distributions with energies that add up to zero. PMID:16593732
Discrete wave mechanics: Multidimensional systems
Wall, Frederick T.
1987-01-01
Discrete wave mechanics is pursued further by extending the one-dimensional treatment to two (or more) dimensions in the light of explicit momentum considerations. Cognizance is taken of the effect of particle motion on mass and hence on the interactions between components of motion in different directions. The overall energy parameter turns out to be a product instead of a sum of parameters identified with each of several orthogonal axes. Accordingly, the separation of variables is most directly accomplished by factoring the principal energy parameter in conjunction with factoring the wave vector expression itself. Wave vector energies, on the other hand, remain additive. Finally, group velocity components are discussed for higher-dimensional systems. PMID:16593833
Discrete modelling of drapery systems
NASA Astrophysics Data System (ADS)
Thoeni, Klaus; Giacomini, Anna
2016-04-01
Drapery systems are an efficient and cost-effective measure in preventing and controlling rockfall hazards on rock slopes. The simplest form consists of a row of ground anchors along the top of the slope connected to a horizontal support cable from which a wire mesh is suspended down the face of the slope. Such systems are generally referred to as simple or unsecured draperies (Badger and Duffy 2012). Variations such as secured draperies, where a pattern of ground anchors is incorporated within the field of the mesh, and hybrid systems, where the upper part of an unsecured drapery is elevated to intercept rockfalls originating upslope of the installation, are becoming more and more popular. This work presents a discrete element framework for simulation of unsecured drapery systems and its variations. The numerical model is based on the classical discrete element method (DEM) and implemented into the open-source framework YADE (Šmilauer et al., 2010). The model takes all relevant interactions between block, drapery and slope into account (Thoeni et al., 2014) and was calibrated and validated based on full-scale experiments (Giacomini et al., 2012).The block is modelled as a rigid clump made of spherical particles which allows any shape to be approximated. The drapery is represented by a set of spherical particle with remote interactions. The behaviour of the remote interactions is governed by the constitutive behaviour of the wire and generally corresponds to a piecewise linear stress-strain relation (Thoeni et al., 2013). The same concept is used to model wire ropes. The rock slope is represented by rigid triangular elements where material properties (e.g., normal coefficient of restitution, friction angle) are assigned to each triangle. The capabilities of the developed model to simulate drapery systems and estimate the residual hazard involved with such systems is shown. References Badger, T.C., Duffy, J.D. (2012) Drapery systems. In: Turner, A.K., Schuster R
Structure of random discrete spacetime
NASA Technical Reports Server (NTRS)
Brightwell, Graham; Gregory, Ruth
1991-01-01
The usual picture of spacetime consists of a continuous manifold, together with a metric of Lorentzian signature which imposes a causal structure on the spacetime. A model, first suggested by Bombelli et al., is considered in which spacetime consists of a discrete set of points taken at random from a manifold, with only the causal structure on this set remaining. This structure constitutes a partially ordered set (or poset). Working from the poset alone, it is shown how to construct a metric on the space which closely approximates the metric on the original spacetime manifold, how to define the effective dimension of the spacetime, and how such quantities may depend on the scale of measurement. Possible desirable features of the model are discussed.
78 FR 54949 - Major Project Financial Plan Guidance
Federal Register 2010, 2011, 2012, 2013, 2014
2013-09-06
... TRANSPORTATION Federal Highway Administration Major Project Financial Plan Guidance AGENCY: Federal Highway... Major Project Financial Plan Guidance outlining the procedures the FHWA will follow when reviewing and approving Financial Plans. The proposed Major Project Financial Plan Guidance incorporates changes...
The Development of Vocational Guidance in the USSR.
ERIC Educational Resources Information Center
Kostin, L. A.
1986-01-01
The author defines the scope and importance of vocational guidance in the Soviet Union. He states that such guidance is primarily for youth. He discusses the institutional framework of vocational guidance programs and new developments in the Soviet Union. (CH)
76 FR 411 - Regulatory Guidance Concerning Electronic Signatures and Documents
Federal Register 2010, 2011, 2012, 2013, 2014
2011-01-04
... Federal Motor Carrier Safety Administration Regulatory Guidance Concerning Electronic Signatures and... guidance. SUMMARY: FMCSA issues regulatory guidance concerning the use of electronic signatures and... information regarding FMCSA's acceptance of electronic signature on documents required by the Federal...
Guidance and control of swarms of spacecraft
NASA Astrophysics Data System (ADS)
Morgan, Daniel James
There has been considerable interest in formation flying spacecraft due to their potential to perform certain tasks at a cheaper cost than monolithic spacecraft. Formation flying enables the use of smaller, cheaper spacecraft that distribute the risk of the mission. Recently, the ideas of formation flying have been extended to spacecraft swarms made up of hundreds to thousands of 100-gram-class spacecraft known as femtosatellites. The large number of spacecraft and limited capabilities of each individual spacecraft present a significant challenge in guidance, navigation, and control. This dissertation deals with the guidance and control algorithms required to enable the flight of spacecraft swarms. The algorithms developed in this dissertation are focused on achieving two main goals: swarm keeping and swarm reconfiguration. The objectives of swarm keeping are to maintain bounded relative distances between spacecraft, prevent collisions between spacecraft, and minimize the propellant used by each spacecraft. Swarm reconfiguration requires the transfer of the swarm to a specific shape. Like with swarm keeping, minimizing the propellant used and preventing collisions are the main objectives. Additionally, the algorithms required for swarm keeping and swarm reconfiguration should be decentralized with respect to communication and computation so that they can be implemented on femtosats, which have limited hardware capabilities. The algorithms developed in this dissertation are concerned with swarms located in low Earth orbit. In these orbits, Earth oblateness and atmospheric drag have a significant effect on the relative motion of the swarm. The complicated dynamic environment of low Earth orbits further complicates the swarm-keeping and swarm-reconfiguration problems. To better develop and test these algorithms, a nonlinear, relative dynamic model with J2 and drag perturbations is developed. This model is used throughout this dissertation to validate the algorithms
NASA Technical Reports Server (NTRS)
Tigges, Michael; Crull, Timothy; Rea, Jeremy; Johnson, Wyatt
2006-01-01
This paper assesses a preliminary guidance and targeting strategy for accomplishing Skip-Entry (SE) flight during a lunar return-capsule entry flight. One of the primary benefits of flying a SE trajectory is to provide the crew with continuous Continental United States (CONUS) landing site access throughout the lunar month. Without a SE capability, the capsule must land either in water or at one of several distributed land sites in the Southern Hemisphere for a significant portion of a lunar month using a landing and recovery scenario similar to that employed during the Apollo program. With a SE trajectory, the capsule can land either in water at a site in proximity to CONUS or at one of several distributed landing sites within CONUS, thereby simplifying the operational requirements for crew retrieval and vehicle recovery, and possibly enabling a high degree of vehicle reusability. Note that a SE capability does not require that the vehicle land on land. A SE capability enables a longer-range flight than a direct-entry flight, which permits the vehicle to land at a much greater distance from the Entry Interface (EI) point. This does not exclude using this approach to push the landing point to a water location in proximity of CONUS and utilizing water or airborne recovery forces.
Optofluidic control of axonal guidance
NASA Astrophysics Data System (ADS)
Gu, Ling; Ordonez, Simon; Black, Bryan; Mohanty, Samarendra K.
2013-03-01
Significant efforts are being made for control on axonal guidance due to its importance in nerve regeneration and in the formation of functional neuronal circuitry in-vitro. These include several physical (topographic modification, optical force, and electric field), chemical (surface functionalization cues) and hybrid (electro-chemical, photochemical etc) methods. Here, we report comparison of the effect of linear flow versus microfluidic flow produced by an opticallydriven micromotor in guiding retinal ganglion axons. A circularly polarized laser tweezers was used to hold, position and spin birefringent calcite particle near growth cone, which in turn resulted in microfluidic flow. The flow rate and resulting shear-force on axons could be controlled by a varying the power of the laser tweezers beam. The calcite particles were placed separately in one chamber and single particle was transported through microfluidic channel to another chamber containing the retina explant. In presence of flow, the turning of axons was found to strongly correlate with the direction of flow. Turning angle as high as 90° was achieved. Optofluidic-manipulation can be applied to other types of mammalian neurons and also can be extended to stimulate mechano-sensing neurons.
Evaluation of low-dose limits in 3D-2D rigid registration for surgical guidance
NASA Astrophysics Data System (ADS)
Uneri, A.; Wang, A. S.; Otake, Y.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Gallia, G. L.; Gokaslan, Z. L.; Siewerdsen, J. H.
2014-09-01
An algorithm for intensity-based 3D-2D registration of CT and C-arm fluoroscopy is evaluated for use in surgical guidance, specifically considering the low-dose limits of the fluoroscopic x-ray projections. The registration method is based on a framework using the covariance matrix adaptation evolution strategy (CMA-ES) to identify the 3D patient pose that maximizes the gradient information similarity metric. Registration performance was evaluated in an anthropomorphic head phantom emulating intracranial neurosurgery, using target registration error (TRE) to characterize accuracy and robustness in terms of 95% confidence upper bound in comparison to that of an infrared surgical tracking system. Three clinical scenarios were considered: (1) single-view image + guidance, wherein a single x-ray projection is used for visualization and 3D-2D guidance; (2) dual-view image + guidance, wherein one projection is acquired for visualization, combined with a second (lower-dose) projection acquired at a different C-arm angle for 3D-2D guidance; and (3) dual-view guidance, wherein both projections are acquired at low dose for the purpose of 3D-2D guidance alone (not visualization). In each case, registration accuracy was evaluated as a function of the entrance surface dose associated with the projection view(s). Results indicate that images acquired at a dose as low as 4 μGy (approximately one-tenth the dose of a typical fluoroscopic frame) were sufficient to provide TRE comparable or superior to that of conventional surgical tracking, allowing 3D-2D guidance at a level of dose that is at most 10% greater than conventional fluoroscopy (scenario #2) and potentially reducing the dose to approximately 20% of the level in a conventional fluoroscopically guided procedure (scenario #3).
Evaluation of low-dose limits in 3D-2D rigid registration for surgical guidance.
Uneri, A; Wang, A S; Otake, Y; Kleinszig, G; Vogt, S; Khanna, A J; Gallia, G L; Gokaslan, Z L; Siewerdsen, J H
2014-09-21
An algorithm for intensity-based 3D-2D registration of CT and C-arm fluoroscopy is evaluated for use in surgical guidance, specifically considering the low-dose limits of the fluoroscopic x-ray projections. The registration method is based on a framework using the covariance matrix adaptation evolution strategy (CMA-ES) to identify the 3D patient pose that maximizes the gradient information similarity metric. Registration performance was evaluated in an anthropomorphic head phantom emulating intracranial neurosurgery, using target registration error (TRE) to characterize accuracy and robustness in terms of 95% confidence upper bound in comparison to that of an infrared surgical tracking system. Three clinical scenarios were considered: (1) single-view image+guidance, wherein a single x-ray projection is used for visualization and 3D-2D guidance; (2) dual-view image+guidance, wherein one projection is acquired for visualization, combined with a second (lower-dose) projection acquired at a different C-arm angle for 3D-2D guidance; and (3) dual-view guidance, wherein both projections are acquired at low dose for the purpose of 3D-2D guidance alone (not visualization). In each case, registration accuracy was evaluated as a function of the entrance surface dose associated with the projection view(s). Results indicate that images acquired at a dose as low as 4 μGy (approximately one-tenth the dose of a typical fluoroscopic frame) were sufficient to provide TRE comparable or superior to that of conventional surgical tracking, allowing 3D-2D guidance at a level of dose that is at most 10% greater than conventional fluoroscopy (scenario #2) and potentially reducing the dose to approximately 20% of the level in a conventional fluoroscopically guided procedure (scenario #3).
Adaptive management is an approach to natural resource management that emphasizes learning through management where knowledge is incomplete, and when, despite inherent uncertainty, managers and policymakers must act. Unlike a traditional trial and error approach, adaptive managem...
Optimal guidance law in quantum mechanics
Yang, Ciann-Dong Cheng, Lieh-Lieh
2013-11-15
Following de Broglie’s idea of a pilot wave, this paper treats quantum mechanics as a problem of stochastic optimal guidance law design. The guidance scenario considered in the quantum world is that an electron is the flight vehicle to be guided and its accompanying pilot wave is the guidance law to be designed so as to guide the electron to a random target driven by the Wiener process, while minimizing a cost-to-go function. After solving the stochastic optimal guidance problem by differential dynamic programming, we point out that the optimal pilot wave guiding the particle’s motion is just the wavefunction Ψ(t,x), a solution to the Schrödinger equation; meanwhile, the closed-loop guidance system forms a complex state–space dynamics for Ψ(t,x), from which quantum operators emerge naturally. Quantum trajectories under the action of the optimal guidance law are solved and their statistical distribution is shown to coincide with the prediction of the probability density function Ψ{sup ∗}Ψ. -- Highlights: •Treating quantum mechanics as a pursuit-evasion game. •Reveal an interesting analogy between guided flight motion and guided quantum motion. •Solve optimal quantum guidance problem by dynamic programming. •Gives a formal proof of de Broglie–Bohm’s idea of a pilot wave. •The optimal pilot wave is shown to be a wavefunction solved from Schrödinger equation.
Molecular mechanisms of optic axon guidance
NASA Astrophysics Data System (ADS)
Inatani, Masaru
2005-12-01
Axon guidance is one of the critical processes during vertebrate central nervous system (CNS) development. The optic nerve, which contains the axons of retinal ganglion cells, has been used as a powerful model to elucidate some of the mechanisms underlying axon guidance because it is easily manipulated experimentally, and its function is well understood. Recent molecular biology studies have revealed that numerous guidance molecules control the development of the visual pathway. This review introduces the molecular mechanisms involved in each critical step during optic axon guidance. Axonal projections to the optic disc are thought to depend on adhesion molecules and inhibitory extracellular matrices such as chondroitin sulfate. The formation of the head of the optic nerve and the optic chiasm require ligand-receptor interactions between netrin-1 and the deleted in colorectal cancer receptor, and Slit proteins and Robo receptors, respectively. The gradient distributions of ephrin ligands and Eph receptors are essential for correct ipsilateral projections at the optic chiasm and the topographic mapping of axons in the superior colliculus/optic tectum. The precise gradient is regulated by transcription factors determining the retinal dorso-ventral and nasal-temporal polarities. Moreover, the axon guidance activities by Slit and semaphorin 5A require the existence of heparan sulfate, which binds to numerous guidance molecules. Recent discoveries about the molecular mechanisms underlying optic nerve guidance will facilitate progress in CNS developmental biology and axon-regeneration therapy.
2007-09-01
basic’, ‘ business ’, ‘industrial’ and ‘military’. Table 4: Number of references grouped by level of experimentation, peer review and domain...or business target domains; and, green = military target domain. Reference. Full reference of article. Overview. Summary of the main conceptual...Organizational Model (organizational or business processes); • Task Model (high-level tasks and goals of agents in the system); • Agent Model (who
Federal Register 2010, 2011, 2012, 2013, 2014
2011-07-21
... Administration (FDA) is announcing the availability of the guidance entitled ``Class II Special Controls Guidance Document: Electrocardiograph Electrodes.'' The special controls identify the following risks to health... Drug Administration Staff; Class II Special Controls Guidance Document: Electrocardiograph...
Federal Register 2010, 2011, 2012, 2013, 2014
2011-05-20
...; Class II Special Controls; Guidance Document: Topical Oxygen Chamber for Extremities; Availability... Drug Administration Staff; Class II Special Controls Guidance Documents: Topical Oxygen Chamber for... Guidance Document: Topical Oxygen Chamber for Extremities'' to the Division of Small...
Powell, R.D.; McCutchen, G.D.
1998-12-31
In October 1997, the Air and Waste Management Association (A and WMA) made available a notebook consisting of documents pertaining to implementation of the operating permits program required by title V of the Clean Air Act and the Environmental Protection Agency`s (EPA) part 70 operating permits regulations. The documents include guidance memos/letters, questions/answers, several specialty documents, and related Federal Register notices that have been produced by EPA since inception of the program with the Clean Air Act amendments of 1990. The notebook contents were made available by EPA and the project was carried out under an EPA contract to A and WMA. The work was performed by RTP Environmental Associates Inc. of Raleigh, North Carolina. The notebook contains more than 75 documents; all the materials EPA believes relevant to implementation of the part 70 program by States, local agencies, territories, and Indian tribes. The documents that comprise the notebook are organized by subject matter and each is given a reference number for purposes of referring to the document. The part 70 operating permits regulations are annotated with document reference numbers to indicate where a document relates to a specific section of the regulations. In addition, documents are indexed four ways; by date, by author, alphabetically by title, and by reference number. Abstracts of each document are included in the notebook to allow the user to determine if the document is of interest. The notebook user, therefore, should be able to readily locate documents and be aware of all materials that affect any area of interest the user may have. The notebook will periodically be updated to add any new materials generated since the last update. The notebook should also be of interest to sources who must obtain a part 70 operating permit and to the general public interested in following implementation of the program. Notebooks may be purchased from A and WMA.
Spurious haloes and discreteness-driven relaxation in cosmological simulations
NASA Astrophysics Data System (ADS)
Power, C.; Robotham, A. S. G.; Obreschkow, D.; Hobbs, A.; Lewis, G. F.
2016-10-01
There is strong evidence that cosmological N-body simulations dominated by warm dark matter (WDM) contain spurious or unphysical haloes, most readily apparent as regularly spaced low-mass haloes strung along filaments. We show that spurious haloes are a feature of traditional N-body simulations of cosmological structure formation models, including WDM and cold dark matter models, in which gravitational collapse proceeds in an initially anisotropic fashion, and arises naturally as a consequence of discreteness-driven relaxation. We demonstrate this using controlled N-body simulations of plane-symmetric collapse and show that spurious haloes are seeded at shell crossing by localized velocity perturbations induced by the discrete nature of the density field, and that their characteristic separation should be approximately the mean inter-particle separation of the N-body simulation, which is fixed by the mass resolution within the volume. Using cosmological N-body simulations in which particles are split into two collisionless components of fixed mass ratio, we find that the spatial distribution of the two components show signatures of discreteness-driven relaxation on both large and small scales. Adopting a spline kernel gravitational softening that is of order the comoving mean inter-particle separation helps to suppress the effect of discreteness-driven relaxation, but cannot eliminate it completely. These results provide further motivation for recent developments of new algorithms, which include, for example, revisions of the traditional N-body approach by means of spatially adaptive anistropric gravitational softenings or explicit solution of the evolution of dark matter in phase space.
Current Density and Continuity in Discretized Models
ERIC Educational Resources Information Center
Boykin, Timothy B.; Luisier, Mathieu; Klimeck, Gerhard
2010-01-01
Discrete approaches have long been used in numerical modelling of physical systems in both research and teaching. Discrete versions of the Schrodinger equation employing either one or several basis functions per mesh point are often used by senior undergraduates and beginning graduate students in computational physics projects. In studying…
Discretization vs. Rounding Error in Euler's Method
ERIC Educational Resources Information Center
Borges, Carlos F.
2011-01-01
Euler's method for solving initial value problems is an excellent vehicle for observing the relationship between discretization error and rounding error in numerical computation. Reductions in stepsize, in order to decrease discretization error, necessarily increase the number of steps and so introduce additional rounding error. The problem is…
Responsible Purchasing Network - Sustainable Purchasing Guidance Profile
To help you find the resource that is right for your organization, EPA conducted a scan of the landscape and developed summary profiles of some of the leading sources of sustainable purchasing guidance around the globe.
European Union Sustainable Purchasing Guidance Profile
To help you find the resource that is right for your organization, EPA conducted a scan of the landscape and developed summary profiles of some of the leading sources of sustainable purchasing guidance around the globe.
Surface Water Treatment Rules State Implementation Guidance
These documents provide guidance to states, tribes and U.S. EPA Regions exercising primary enforcement responsibility under the Safe Drinking Water Act. The documents contain EPA’s recommendations for implementation of the Surface Water Treatment Rules.
Safe abortion: WHO technical and policy guidance.
Cook, R J; Dickens, B M; Horga, M
2004-07-01
In 2003, the World Health Organization published its well referenced handbook Safe Abortion: Technical and Policy Guidance for Health Systems to address the estimated almost 20 million induced abortions each year that are unsafe, imposing a burden of approximately 67 thousand deaths annually. It is a global injustice that 95% of unsafe abortions occur in developing countries. The focus of guidance is on abortion procedures that are lawful within the countries in which they occur, noting that in almost all countries, the law permits abortion to save a woman's life. The guidance treats unsafe abortion as a public health challenge, and responds to the problem through strategies concerning improved clinical care for women undergoing procedures, and the appropriate placement of necessary services. Legal and policy considerations are explored, and annexes present guidance to further reading, international consensus documents on safe abortion, and on manual vacuum aspiration and post-abortion contraception.
Optimal guidance for the space shuttle transition.
NASA Technical Reports Server (NTRS)
Stengel, R. F.
1972-01-01
A guidance method for the space shuttle's transition from hypersonic entry to subsonic cruising flight is presented. The method evolves from a numerical trajectory optimization technique in which kinetic energy and total energy (per unit weight) replace velocity and time in the dynamic equations. This allows the open end-time problem to be transformed to one of fixed terminal energy. In its ultimate form, 'E-Guidance' obtains energy balance (including dynamic-pressure-rate damping) and path length control by angle-of-attack modulation and cross-range control by roll angle modulation. The guidance functions also form the basis for a pilot display of instantaneous maneuver limits and destination. Numerical results illustrate the E-Guidance concept and the optimal trajectories on which it is based.
Optimal guidance for the space shuttle transition
NASA Technical Reports Server (NTRS)
Stengel, R. F.
1974-01-01
A guidance method for the space shuttle's transition from hypersonic entry to subsonic cruising flight is presented. The method evolves from a numerical trajectory optimization technique in which kinetic energy and total energy (per unit weight) replace velocity and time in the dynamic equations. This allows the open end-time problem to be transformed to one of fixed terminal energy. In its ultimate form, E-Guidance obtains energy balance (including dynamic-pressure-rate damping) and path length control by angle-of-attack modulation and cross-range control by roll angle modulation. The guidance functions also form the basis for a pilot display of instantaneous maneuver limits and destination. Numerical results illustrate the E-Guidance concept and the optimal trajectories on which it is based.
Optimal guidance for the space shuttle transition
NASA Technical Reports Server (NTRS)
Stengel, R. F.
1972-01-01
A guidance method for the space shuttle's transition from hypersonic entry to subsonic cruising flight is presented. The method evolves from a numerical trajectory optimization technique in which kinetic energy and total energy (per unit weight) replace velocity and time in the dynamic equations. This allows the open end-time problem to be transformed to one of fixed terminal energy. In its ultimate form, E-Guidance obtains energy balance (including dynamic-pressure-rate damping) and path length control by angle-of-attack modulation and cross-range control by roll angle modulation. The guidance functions also form the basis for a pilot display of instantaneous maneuver limits and destination. Numerical results illustrate the E-Guidance concept and the optimal trajectories on which it is based.
General RMP Guidance - Table of Contents
The Risk Management Programs for Chemical Accident Prevention (40 CFR Part 68) guidance is in chapters; each covering topics such as applicability of the rule, and requirements for reporting five-year accident history and offsite consequence analysis.
Delta launch vehicle inertial guidance system (DIGS)
NASA Technical Reports Server (NTRS)
Duck, K. I.
1973-01-01
The Delta inertial guidance system, part of the Delta launch vehicle improvement effort, has been flown on three launches and was found to perform as expected for a variety of mission profiles and vehicle configurations.
RMP Guidance for Warehouses - Table of Contents
This Risk Management Program (40 CFR Part 68) Guidance is organized into chapters, each covering a topic such as applicability of the rule, requirements for the five-year accident history and offsite consequence analysis, and emergency response.
Beam envelope matching for beam guidance systems
Brown, K.L.
1980-08-01
Ray optics and phase ellipse optics are developed as tools for designing charged particle beam guidance systems. Specific examples of basic optical systems and of phase ellipse matching are presented as illustrations of these mathematical techniques.
Practice Greenhealth Sustainable Purchasing Guidance Profile
To help you find the resource that is right for your organization, EPA conducted a scan of the landscape and developed summary profiles of some of the leading sources of sustainable purchasing guidance around the globe.
Guidance for Developing TMDLs in California
This document provides guidance to the State of California concerning its responsibility under section 303(d) of the Clean Water Act concerning the development of TMDLs for water quality-limited segments listed under section 303(d).
Beyond Black: An Alternative to Ethnocentric Guidance
ERIC Educational Resources Information Center
Goldman, Robert C.
1977-01-01
This article is a clarification of the author's personal philosophy in the guidance and counseling of youth and adults, and clarification of commonalities that form the raison d'etre of all student personnel services. (Author)
The Industrial User Permitting Guidance Manual
Provides guidance for control authorities to effectively develop and issue control mechanisms to IUs discharging to the POTW and covers developing and implementing control mechanisms for both SIUs and non-SIUs.
Guidance: Treatment of Insurers Under Superfund
Guidance provides EPA Regional offices with the appropriate procedures to follow in issuing notice letters, developing referrals, and tracking CERCLA enforcement cases that may include insurers as third party defendants.
POTW Sludge Sampling and Analysis Guidance Document
In view of the variability of municipal sludge quality,appropriate procedures must be followed to collect and analyze samples that accurately represent each POTW's sludge quality.This manual was developed to provide that guidance to POTW operators, engin
Extreme events in discrete nonlinear lattices.
Maluckov, A; Hadzievski, Lj; Lazarides, N; Tsironis, G P
2009-02-01
We perform statistical analysis on discrete nonlinear waves generated through modulational instability in the context of the Salerno model that interpolates between the integrable Ablowitz-Ladik (AL) equation and the nonintegrable discrete nonlinear Schrödinger equation. We focus on extreme events in the form of discrete rogue or freak waves that may arise as a result of rapid coalescence of discrete breathers or other nonlinear interaction processes. We find power law dependence in the wave amplitude distribution accompanied by an enhanced probability for freak events close to the integrable limit of the equation. A characteristic peak in the extreme event probability appears that is attributed to the onset of interaction of the discrete solitons of the AL equation and the accompanied transition from the local to the global stochasticity monitored through the positive Lyapunov exponent of a nonlinear map.
Discrete multiscale wavelet shrinkage and integrodifferential equations
NASA Astrophysics Data System (ADS)
Didas, S.; Steidl, G.; Weickert, J.
2008-04-01
We investigate the relation between discrete wavelet shrinkage and integrodifferential equations in the context of simplification and denoising of one-dimensional signals. In the continuous setting, strong connections between these two approaches were discovered in 6 (see references). The key observation is that the wavelet transform can be understood as derivative operator after the convolution with a smoothing kernel. In this paper, we extend these ideas to the practically relevant discrete setting with both orthogonal and biorthogonal wavelets. In the discrete case, the behaviour of the smoothing kernels for different scales requires additional investigation. The results of discrete multiscale wavelet shrinkage and related discrete versions of integrodifferential equations are compared with respect to their denoising quality by numerical experiments.
Generalized exponential function and discrete growth models
NASA Astrophysics Data System (ADS)
Souto Martinez, Alexandre; Silva González, Rodrigo; Lauri Espíndola, Aquino
2009-07-01
Here we show that a particular one-parameter generalization of the exponential function is suitable to unify most of the popular one-species discrete population dynamic models into a simple formula. A physical interpretation is given to this new introduced parameter in the context of the continuous Richards model, which remains valid for the discrete case. From the discretization of the continuous Richards’ model (generalization of the Gompertz and Verhulst models), one obtains a generalized logistic map and we briefly study its properties. Notice, however that the physical interpretation for the introduced parameter persists valid for the discrete case. Next, we generalize the (scramble competition) θ-Ricker discrete model and analytically calculate the fixed points as well as their stabilities. In contrast to previous generalizations, from the generalized θ-Ricker model one is able to retrieve either scramble or contest models.
Active control of turbomachine discrete tones
NASA Astrophysics Data System (ADS)
Fleeter, Sanford
This paper was directed at active control of discrete frequency noise generated by subsonic blade rows through cancellation of the blade row interaction generated propagating acoustic waves. First discrete frequency noise generated by a rotor and stator in a duct was analyzed to determine the propagating acoustic pressure waves. Then a mathematical model was developed to analyze and predict the active control of discrete frequency noise generated by subsonic blade rows through cancellation of the propagating acoustic waves, accomplished by utilizing oscillating airfoil surfaces to generate additional control propagating pressure waves. These control waves interact with the propagating acoustic waves, thereby, in principle, canceling the acoustic waves and thus, the far field discrete frequency tones. This model was then applied to a fan exit guide vane to investigate active airfoil surface techniques for control of the propagating acoustic waves, and thus the far field discrete frequency tones, generated by blade row interactions.
Seleson, Pablo; Du, Qiang; Parks, Michael L.
2016-08-16
The peridynamic theory of solid mechanics is a nonlocal reformulation of the classical continuum mechanics theory. At the continuum level, it has been demonstrated that classical (local) elasticity is a special case of peridynamics. Such a connection between these theories has not been extensively explored at the discrete level. This paper investigates the consistency between nearest-neighbor discretizations of linear elastic peridynamic models and finite difference discretizations of the Navier–Cauchy equation of classical elasticity. While nearest-neighbor discretizations in peridynamics have been numerically observed to present grid-dependent crack paths or spurious microcracks, this paper focuses on a different, analytical aspect of such discretizations. We demonstrate that, even in the absence of cracks, such discretizations may be problematic unless a proper selection of weights is used. Specifically, we demonstrate that using the standard meshfree approach in peridynamics, nearest-neighbor discretizations do not reduce, in general, to discretizations of corresponding classical models. We study nodal-based quadratures for the discretization of peridynamic models, and we derive quadrature weights that result in consistency between nearest-neighbor discretizations of peridynamic models and discretized classical models. The quadrature weights that lead to such consistency are, however, model-/discretization-dependent. We motivate the choice of those quadrature weights through a quadratic approximation of displacement fields. The stability of nearest-neighbor peridynamic schemes is demonstrated through a Fourier mode analysis. Finally, an approach based on a normalization of peridynamic constitutive constants at the discrete level is explored. This approach results in the desired consistency for one-dimensional models, but does not work in higher dimensions. The results of the work presented in this paper suggest that even though nearest
Soil screening guidance: User`s guide
1996-04-01
The Soil Screening Guidance is a tool that the U.S. Environmental Protection Agency (EPA) developed to help standardize and accelerate the evaluation and cleanup of contaminated soils at sites on the National Priorities List (NPL) with future residential land use. This guidance provides a methodology for environmental science/engineering professionals to calculate risk-based, site-specific, soil screening levels (SSLs) for contaminants in soil that may be used to identify areas needing further investigation at NPL sites.
Reach on laser imaging technology to terminal guidance
NASA Astrophysics Data System (ADS)
Tan, Xue-chun; Jin, Guang-yong; Wu, Zhi-chao; Ling, Ming; Liang, Zhu
2009-07-01
The development of range-imaging devices is motivated by various ground and space applications. Tasks in space missions include docking, rendezvous, manipulating robotic arms, landing and autonomous rover applications, sample identification and surface mapping. The ground applications include the guidance of vehicles, robotic and manipulator arms, and other autonomous or teleoperated machines, as well as surface or construction model generation. Without the scanner devices, scannerless imaging lidars have the characteristic of high frame rate, wide field of view and high reliability,which can be successful used in terminal guidance. Diode pumped laser radar with high repetition rate is studied in this paper. A bistatic system is set up and a high speed signal processor for the system is researched. In a conceptual sense, the imaging lidar has two parts, a transmitter and a receiver. Their field of views overlap throughout the measuring range.The imaging lidar operates as follows. Based on principle of pulsed time-of-flight (TOF) laser range finding, the solid-state laser diode-pumped laser produces short laser pulses, which though the expanded lens, then reach the target. The back reflected light is collected with a receiver lens and fed through optical fibres to discrete avalanche photo diodes (APDs). When a received pulse is detected by the comparator a time to digital converter (TDC) stops counting and a time interval, corresponding to the range, is produced. The precision of a single measurement is about +/-4.0cm, but better precision is achieved by averaging. Information about the reflectivity of the target is gathered by recording the amplitude of the received pulse. Range images with the lidar prototype were taken indoors, the measuring distance was about 14m.
Adaptive control based on retrospective cost optimization
NASA Astrophysics Data System (ADS)
Santillo, Mario A.
This dissertation studies adaptive control of multi-input, multi-output, linear, time-invariant, discrete-time systems that are possibly unstable and nonminimum phase. We consider both gradient-based adaptive control as well as retrospective-cost-based adaptive control. Retrospective cost optimization is a measure of performance at the current time based on a past window of data and without assumptions about the command or disturbance signals. In particular, retrospective cost optimization acts as an inner loop to the adaptive control algorithm by modifying the performance variables based on the difference between the actual past control inputs and the recomputed past control inputs based on the current control law. We develop adaptive control algorithms that are effective for systems that are nonminimum phase. We consider discrete-time adaptive control since these control laws can be implemented directly in embedded code without requiring an intermediate discretization step. Furthermore, the adaptive controllers in this dissertation are developed under minimal modeling assumptions. In particular, the adaptive controllers require knowledge of the sign of the high-frequency gain and a sufficient number of Markov parameters to approximate the nonminimum-phase zeros (if any). No additional modeling information is necessary. The adaptive controllers presented in this dissertation are developed for full-state-feedback stabilization, static-output-feedback stabilization, as well as dynamic compensation for stabilization, command following, disturbance rejection, and model reference adaptive control. Lyapunov-based stability and convergence proofs are provided for special cases. We present numerical examples to illustrate the algorithms' effectiveness in handling systems that are unstable and/or nonminimum phase and to provide insight into the modeling information required for controller implementation.
Discrete vortices on anisotropic lattices
NASA Astrophysics Data System (ADS)
Chen, Gui-Hua; Wang, Hong-Cheng; Chen, Zi-Fa
2015-08-01
We consider the effects of anisotropy on two types of localized states with topological charges equal to 1 in two-dimensional nonlinear lattices, using the discrete nonlinear Schrödinger equation as a paradigm model. We find that on-site-centered vortices with different propagation constants are not globally stable, and that upper and lower boundaries of the propagation constant exist. The region between these two boundaries is the domain outside of which the on-site-centered vortices are unstable. This region decreases in size as the anisotropy parameter is gradually increased. We also consider off-site-centered vortices on anisotropic lattices, which are unstable on this lattice type and either transform into stable quadrupoles or collapse. We find that the transformation of off-sitecentered vortices into quadrupoles, which occurs on anisotropic lattices, cannot occur on isotropic lattices. In the quadrupole case, a propagation-constant region also exists, outside of which the localized states cannot stably exist. The influence of anisotropy on this region is almost identical to its effects on the on-site-centered vortex case.
Additional information for food processors, food distributors, refrigerated warehouses, and any other facility with ammonia refrigeration system. Includes guidance on exemptions, threshold quantity, offsite consequence analysis.
Adaptive Control Techniques for Large Space Structures.
1986-09-15
Adaptive Systems: A Ji . Fixed-Point Analysis", submitted, IEEE Trans. on Circuits and Systems; Special Issue on Adaptive Systems, Sept. 1987. I.M.Y...Shaped Cost Functionals: Extensions of LQG Methods," *.. AIAA J. of Guidance and Control, pp. 529-535, Nov-Dec. 1980. [81 C.A. Desoer , R.W. Liu, J. Murray...for Parameter Conver- gence in Adaptive Control," Memo No. UCB/ERL M84/25, Univ. of California, Berke- ley, 1984. [19] C.A. Desoer and M. Vidyasagar
Compatible Spatial Discretizations for Partial Differential Equations
Arnold, Douglas, N, ed.
2004-11-25
From May 11--15, 2004, the Institute for Mathematics and its Applications held a hot topics workshop on Compatible Spatial Discretizations for Partial Differential Equations. The numerical solution of partial differential equations (PDE) is a fundamental task in science and engineering. The goal of the workshop was to bring together a spectrum of scientists at the forefront of the research in the numerical solution of PDEs to discuss compatible spatial discretizations. We define compatible spatial discretizations as those that inherit or mimic fundamental properties of the PDE such as topology, conservation, symmetries, and positivity structures and maximum principles. A wide variety of discretization methods applied across a wide range of scientific and engineering applications have been designed to or found to inherit or mimic intrinsic spatial structure and reproduce fundamental properties of the solution of the continuous PDE model at the finite dimensional level. A profusion of such methods and concepts relevant to understanding them have been developed and explored: mixed finite element methods, mimetic finite differences, support operator methods, control volume methods, discrete differential forms, Whitney forms, conservative differencing, discrete Hodge operators, discrete Helmholtz decomposition, finite integration techniques, staggered grid and dual grid methods, etc. This workshop seeks to foster communication among the diverse groups of researchers designing, applying, and studying such methods as well as researchers involved in practical solution of large scale problems that may benefit from advancements in such discretizations; to help elucidate the relations between the different methods and concepts; and to generally advance our understanding in the area of compatible spatial discretization methods for PDE. Particular points of emphasis included: + Identification of intrinsic properties of PDE models that are critical for the fidelity of numerical
An extension of the OpenModelica compiler for using Modelica models in a discrete event simulation
Nutaro, James
2014-11-03
In this article, a new back-end and run-time system is described for the OpenModelica compiler. This new back-end transforms a Modelica model into a module for the adevs discrete event simulation package, thereby extending adevs to encompass complex, hybrid dynamical systems. The new run-time system that has been built within the adevs simulation package supports models with state-events and time-events and that comprise differential-algebraic systems with high index. Finally, although the procedure for effecting this transformation is based on adevs and the Discrete Event System Specification, it can be adapted to any discrete event simulation package.
NASA Astrophysics Data System (ADS)
Ulrich, Steve; de Lafontaine, Jean
2007-12-01
Upcoming landing missions to Mars will require on-board guidance and control systems in order to meet the scientific requirement of landing safely within hundreds of meters to the target of interest. More specifically, in the longitudinal plane, the first objective of the entry guidance and control system is to bring the vehicle to its specified velocity at the specified altitude (as required for safe parachute deployment), while the second objective is to reach the target position in the longitudinal plane. This paper proposes an improvement to the robustness of the constant flight path angle guidance law for achieving the first objective. The improvement consists of combining this guidance law with a novel adaptive control scheme, derived from the so-called Simple Adaptive Control (SAC) technique. Monte-Carlo simulation results are shown to demonstrate the accuracy and the robustness of the proposed guidance and adaptive control system.
Adaptive Dynamic Bayesian Networks
Ng, B M
2007-10-26
A discrete-time Markov process can be compactly modeled as a dynamic Bayesian network (DBN)--a graphical model with nodes representing random variables and directed edges indicating causality between variables. Each node has a probability distribution, conditional on the variables represented by the parent nodes. A DBN's graphical structure encodes fixed conditional dependencies between variables. But in real-world systems, conditional dependencies between variables may be unknown a priori or may vary over time. Model errors can result if the DBN fails to capture all possible interactions between variables. Thus, we explore the representational framework of adaptive DBNs, whose structure and parameters can change from one time step to the next: a distribution's parameters and its set of conditional variables are dynamic. This work builds on recent work in nonparametric Bayesian modeling, such as hierarchical Dirichlet processes, infinite-state hidden Markov networks and structured priors for Bayes net learning. In this paper, we will explain the motivation for our interest in adaptive DBNs, show how popular nonparametric methods are combined to formulate the foundations for adaptive DBNs, and present preliminary results.
Barrett, Harrison H.; Furenlid, Lars R.; Freed, Melanie; Hesterman, Jacob Y.; Kupinski, Matthew A.; Clarkson, Eric; Whitaker, Meredith K.
2008-01-01
Adaptive imaging systems alter their data-acquisition configuration or protocol in response to the image information received. An adaptive pinhole single-photon emission computed tomography (SPECT) system might acquire an initial scout image to obtain preliminary information about the radiotracer distribution and then adjust the configuration or sizes of the pinholes, the magnifications, or the projection angles in order to improve performance. This paper briefly describes two small-animal SPECT systems that allow this flexibility and then presents a framework for evaluating adaptive systems in general, and adaptive SPECT systems in particular. The evaluation is in terms of the performance of linear observers on detection or estimation tasks. Expressions are derived for the ideal linear (Hotelling) observer and the ideal linear (Wiener) estimator with adaptive imaging. Detailed expressions for the performance figures of merit are given, and possible adaptation rules are discussed. PMID:18541485
Hybridization, agency discretion, and implementation of the U.S. Endangered Species Act.
Lind-Riehl, Jennifer F; Mayer, Audrey L; Wellstead, Adam M; Gailing, Oliver
2016-12-01
The U.S. Endangered Species Act (ESA) requires that the "best available scientific and commercial data" be used to protect imperiled species from extinction and preserve biodiversity. However, it does not provide specific guidance on how to apply this mandate. Scientific data can be uncertain and controversial, particularly regarding species delineation and hybridization issues. The U.S. Fish and Wildlife Service (FWS) had an evolving hybrid policy to guide protection decisions for individuals of hybrid origin. Currently, this policy is in limbo because it resulted in several controversial conservation decisions in the past. Biologists from FWS must interpret and apply the best available science to their recommendations and likely use considerable discretion in making recommendations for what species to list, how to define those species, and how to recover them. We used semistructured interviews to collect data on FWS biologists' use of discretion to make recommendations for listed species with hybridization issues. These biologists had a large amount of discretion to determine the best available science and how to interpret it but generally deferred to the scientific consensus on the taxonomic status of an organism. Respondents viewed hybridization primarily as a problem in the context of the ESA, although biologists who had experience with hybridization issues were more likely to describe it in more nuanced terms. Many interviewees expressed a desire to continue the current case-by-case approach for handling hybridization issues, but some wanted more guidance on procedures (i.e., a "flexible" hybrid policy). Field-level information can provide critical insight into which policies are working (or not working) and why. The FWS biologists' we interviewed had a high level of discretion, which greatly influenced ESA implementation, particularly in the context of hybridization.
On the definition of discrete hydrodynamic variables.
Español, Pep; Zúñiga, Ignacio
2009-10-28
The Green-Kubo formula for discrete hydrodynamic variables involves information about not only the fluid transport coefficients but also about discrete versions of the differential operators that govern the evolution of the discrete variables. This gives an intimate connection between discretization procedures in fluid dynamics and coarse-graining procedures used to obtain hydrodynamic behavior of molecular fluids. We observed that a natural definition of discrete hydrodynamic variables in terms of Voronoi cells leads to a Green-Kubo formula which is divergent, rendering the full coarse-graining strategy useless. In order to understand this subtle issue, in the present paper we consider the coarse graining of noninteracting Brownian particles. The discrete hydrodynamic variable for this problem is the number of particles within Voronoi cells. Thanks to the simplicity of the model we spot the origin of the singular behavior of the correlation functions. We offer an alternative definition, based on the concept of a Delaunay cell that behaves properly, suggesting the use of the Delaunay construction for the coarse graining of molecular fluids at the discrete hydrodynamic level.
Constituent Aspects of Workplace Guidance in Secondary VET
ERIC Educational Resources Information Center
Swager, Robert; Klarus, Ruud; van Merriënboer, Jeroen J. G.; Nieuwenhuis, Loek F. M.
2015-01-01
Purpose: This paper aims to present an integrated model of workplace guidance to enhance awareness of what constitutes good guidance, to improve workplace guidance practices in vocational education and training. Design/methodology/approach: To identify constituent aspects of workplace guidance, a systematic search of Web of Science was conducted,…
The Development of a Lifelong Guidance System in Hungary
ERIC Educational Resources Information Center
Watts, A. G.; Borbely-Pecze, Bors Tibor
2011-01-01
The development of a lifelong guidance system in Hungary Systematic work is currently being undertaken in Hungary to develop a lifelong guidance system, in line with principles outlined by leading international organisations. The origins of career guidance in Hungary, and the nature of the current career guidance system, are outlined. The main…
Guidance for Human-system Interfaces to Automatic Systems
O'Hara, J.M.; Higgins, J.; Stephen Fleger; Valerie Barnes
2010-09-27
Automation is ubiquitous in modern complex systems, and commercial nuclear- power plants are no exception. Automation is applied to a wide range of functions, including monitoring and detection, situation assessment, response planning, and response implementation. Automation has become a 'team player' supporting personnel in nearly all aspects of system operation. In light of its increasing use and importance in new- and future-plants, guidance is needed to conduct safety reviews of the operator's interface with automation. The objective of this research was to develop such guidance. We first characterized the important HFE aspects of automation, including six dimensions: Levels, functions, processes, modes, flexibility, and reliability. Next, we reviewed literature on the effects of all of these aspects of automation on human performance, and on the design of human-system interfaces (HSIs). Then, we used this technical basis established from the literature to identify general principles for human-automation interaction and to develop review guidelines. The guidelines consist of the following seven topics: Automation displays, interaction and control, automation modes, automation levels, adaptive automation, error tolerance and failure management, and HSI integration.
Integration of existing systematic reviews into new reviews: identification of guidance needs
2014-01-01
Background An exponential increase in the number of systematic reviews published, and constrained resources for new reviews, means that there is an urgent need for guidance on explicitly and transparently integrating existing reviews into new systematic reviews. The objectives of this paper are: 1) to identify areas where existing guidance may be adopted or adapted, and 2) to suggest areas for future guidance development. Methods We searched documents and websites from healthcare focused systematic review organizations to identify and, where available, to summarize relevant guidance on the use of existing systematic reviews. We conducted informational interviews with members of Evidence-based Practice Centers (EPCs) to gather experiences in integrating existing systematic reviews, including common issues and challenges, as well as potential solutions. Results There was consensus among systematic review organizations and the EPCs about some aspects of incorporating existing systematic reviews into new reviews. Current guidance may be used in assessing the relevance of prior reviews and in scanning references of prior reviews to identify studies for a new review. However, areas of challenge remain. Areas in need of guidance include how to synthesize, grade the strength of, and present bodies of evidence composed of primary studies and existing systematic reviews. For instance, empiric evidence is needed regarding how to quality check data abstraction and when and how to use study-level risk of bias assessments from prior reviews. Conclusions There remain areas of uncertainty for how to integrate existing systematic reviews into new reviews. Methods research and consensus processes among systematic review organizations are needed to develop guidance to address these challenges. PMID:24956937
Wolf, R Cameron; Adams, Darrin; Dayton, Robyn; Verster, Annette; Wong, Joe; Romero, Marcela; Mazin, Rafael; Settle, Edmund; Sladden, Tim; Keatley, JoAnne
2016-01-01
Transgender (trans) activists and global health partners have collaborated to develop new tools and guidance for assessing and addressing HIV and other health needs within trans populations. Trans women experience a heavy burden of HIV and other sexually transmitted infections (STIs), high incidence of violence and difficulties accessing gender-affirming services. At the same time, little has been published on trans men's health, HIV issues, needs and experiences. Young trans people are especially marginalized and vulnerable, with few programmes and services specifically tailored to their needs. Trans-specific data and guidance are needed to adapt the global response to HIV to meet the needs of the trans population. While the needs of this group have only recently received attention, global, regional and other technical guidance documents are being developed to address these gaps. Regional blueprints for comprehensive care for trans people in Latin America, the Caribbean, and Asia and the Pacific are now available. These tools - supported by the Pan American Health Organization, World Health Organization, US President's Emergency Plan for AIDS Relief and the United Nations Development Programme, in collaboration with regional trans groups - provide a contextual map, indicating opportunities for interventions in health, HIV, violence, stigma and discrimination, social protection and human rights. Global guidance includes the World Health Organization's Policy Brief: Transgender People and HIV, and the interagency publication, Implementing Comprehensive HIV and STI Programmes with Transgender People. Community empowerment and capacity building are the focus of the new tools for global and regional transgender guidance. The goal is to strengthen and ensure community-led responses to the HIV challenge in trans populations. This article describes the new tools and guidance and considers the steps needed to use them to appropriately support and engage transgender
Putting the t in tools: a roadmap for implementation of new global and regional transgender guidance
Wolf, R Cameron; Adams, Darrin; Dayton, Robyn; Verster, Annette; Wong, Joe; Romero, Marcela; Mazin, Rafael; Settle, Edmund; Sladden, Tim; Keatley, JoAnne
2016-01-01
Transgender (trans) activists and global health partners have collaborated to develop new tools and guidance for assessing and addressing HIV and other health needs within trans populations. Trans women experience a heavy burden of HIV and other sexually transmitted infections (STIs), high incidence of violence and difficulties accessing gender-affirming services. At the same time, little has been published on trans men's health, HIV issues, needs and experiences. Young trans people are especially marginalized and vulnerable, with few programmes and services specifically tailored to their needs. Trans-specific data and guidance are needed to adapt the global response to HIV to meet the needs of the trans population. While the needs of this group have only recently received attention, global, regional and other technical guidance documents are being developed to address these gaps. Regional blueprints for comprehensive care for trans people in Latin America, the Caribbean, and Asia and the Pacific are now available. These tools – supported by the Pan American Health Organization, World Health Organization, US President's Emergency Plan for AIDS Relief and the United Nations Development Programme, in collaboration with regional trans groups – provide a contextual map, indicating opportunities for interventions in health, HIV, violence, stigma and discrimination, social protection and human rights. Global guidance includes the World Health Organization's Policy Brief: Transgender People and HIV, and the interagency publication, Implementing Comprehensive HIV and STI Programmes with Transgender People. Community empowerment and capacity building are the focus of the new tools for global and regional transgender guidance. The goal is to strengthen and ensure community-led responses to the HIV challenge in trans populations. This article describes the new tools and guidance and considers the steps needed to use them to appropriately support and engage transgender
Williamson, Jeffrey F
2008-01-01
In the past decade, brachytherapy has shifted from the traditional surgical paradigm to more modern three-dimensional image-based planning and delivery approaches. The role of intraoperative and multimodality image-based planning is growing. Published American Association of Physicists in Medicine, American College of Radiology, European Society for Therapeutic Radiology and Oncology, and International Atomic Energy Agency quality assurance (QA) guidelines largely emphasize the QA of planning and delivery devices rather than processes. These protocols have been designed to verify compliance with major performance specifications and are not risk based. With some exceptions, complete and clinically practical guidance exists for sources, QA instrumentation, non-image-based planning systems, applicators, remote afterloading systems, dosimetry, and calibration. Updated guidance is needed for intraoperative imaging systems and image-based planning systems. For non-image-based brachytherapy, the American Association of Physicists in Medicine Task Group reports 56 and 59 provide reasonable guidance on procedure-specific process flow and QA. However, improved guidance is needed even for established procedures such as ultrasound-guided prostate implants. Adaptive replanning in brachytherapy faces unsolved problems similar to that of image-guided adaptive external beam radiotherapy.
Stochastic Discrete Equation Method (sDEM) for two-phase flows
Abgrall, R.; Congedo, P.M.; Geraci, G.; Rodio, M.G.
2015-10-15
A new scheme for the numerical approximation of a five-equation model taking into account Uncertainty Quantification (UQ) is presented. In particular, the Discrete Equation Method (DEM) for the discretization of the five-equation model is modified for including a formulation based on the adaptive Semi-Intrusive (aSI) scheme, thus yielding a new intrusive scheme (sDEM) for simulating stochastic two-phase flows. Some reference test-cases are performed in order to demonstrate the convergence properties and the efficiency of the overall scheme. The propagation of initial conditions uncertainties is evaluated in terms of mean and variance of several thermodynamic properties of the two phases.
NASA Astrophysics Data System (ADS)
Lü, Ling; Chen, Liansong; Bai, Suyuan; Li, Gang
2016-10-01
We propose a novel scheme to achieve synchronization tracking of uncertain discrete network with spatiotemporal chaos behaviors. In this work, the traditional method of sliding mode control is firstly modified for researching conveniently the synchronization tracking of uncertain discrete network. Further, the network sliding mode surface and control input are designed, and their effectiveness are analyzed. At the same time, we also design the adaptive law to identify availably the uncertain configuration coefficient of the network sliding mode surface. Finally, an example about the small-world network is considered to illustrate the application and effectiveness of the proposed scheme.
Discrete symmetries and de Sitter spacetime
Cotăescu, Ion I. Pascu, Gabriel
2014-11-24
Aspects of the ambiguity in defining quantum modes on de Sitter spacetime using a commuting system composed only of differential operators are discussed. Discrete symmetries and their actions on the wavefunction in commonly used coordinate charts are reviewed. It is argued that the system of commuting operators can be supplemented by requiring the invariance of the wavefunction to combined discrete symmetries- a criterion which selects a single state out of the α-vacuum family. Two such members of this family are singled out by particular combined discrete symmetries- states between which exists a well-known thermality relation.
Discrete flavour symmetries from the Heisenberg group
NASA Astrophysics Data System (ADS)
Floratos, E. G.; Leontaris, G. K.
2016-04-01
Non-abelian discrete symmetries are of particular importance in model building. They are mainly invoked to explain the various fermion mass hierarchies and forbid dangerous superpotential terms. In string models they are usually associated to the geometry of the compactification manifold and more particularly to the magnetised branes in toroidal compactifications. Motivated by these facts, in this note we propose a unified framework to construct representations of finite discrete family groups based on the automorphisms of the discrete and finite Heisenberg group. We focus in particular, on the PSL2 (p) groups which contain the phenomenologically interesting cases.
Using discrete choice experiments to understand preferences in health care.
Pfarr, Christian; Schmid, Andreas; Schneider, Udo
2014-01-01
Whenever processes are reconfigured or new products are designed the needs and preferences of patients and consumers have to be considered. Although at times neglected, this becomes more and more relevant in health care settings: Which modes of health care delivery will be accepted? What are the patients' priorities and what is the willingness to pay? To which degree are patients mobile and for which kind of services are they willing to travel? Preferences, however, are difficult to measure, as they are latent constructs. This becomes even more difficult, when no past choices can be analyzed either as the service or the product is yet to be developed or as in the past there has not been free choice for patients. In such cases, preferences cannot be surveyed directly. Asking individuals openly for their attitudes towards certain services and products, the results are likely biased as individuals are not confronted with budget constraints and trade-offs. For this reason, discrete choice experiments (DCEs) are frequently used to elicit patient preferences. This approach confronts patients with hypothetical scenarios of which only one can be chosen. Over the past few years, this tool to reveal patients' preferences for health care has become very popular in health economics. This contribution aims at introducing the principles of DCEs, highlighting the underlying theory and giving practical guidance for conducting a discrete choice experiment in health economics. Thereby we focus on three major fields of patient demand: designing health insurance, assessing patient utility of new pharmaceuticals and analyzing provider choice. By having a closer look at selected international studies, we discuss the application of this technique for the analysis of the supply and the demand of health care as well as the implications for assessing patient mobility across different health care systems.
Launch flexibility using NLP guidance and remote wind sensing
NASA Technical Reports Server (NTRS)
Cramer, Evin J.; Bradt, Jerre E.; Hardtla, John W.
1990-01-01
This paper examines the use of lidar wind measurements in the implementation of a guidance strategy for a nonlinear programming (NLP) launch guidance algorithm. The NLP algorithm uses B-spline command function representation for flexibility in the design of the guidance steering commands. Using this algorithm, the guidance system solves a two-point boundary value problem at each guidance update. The specification of different boundary value problems at each guidance update provides flexibility that can be used in the design of the guidance strategy. The algorithm can use lidar wind measurements for on pad guidance retargeting and for load limiting guidance steering commands. Examples presented in the paper use simulated wind updates to correct wind induced final orbit errors and to adjust the guidance steering commands to limit the product of the dynamic pressure and angle-of-attack for launch vehicle load alleviation.
Variationally consistent discretization schemes and numerical algorithms for contact problems
NASA Astrophysics Data System (ADS)
Wohlmuth, Barbara
We consider variationally consistent discretization schemes for mechanical contact problems. Most of the results can also be applied to other variational inequalities, such as those for phase transition problems in porous media, for plasticity or for option pricing applications from finance. The starting point is to weakly incorporate the constraint into the setting and to reformulate the inequality in the displacement in terms of a saddle-point problem. Here, the Lagrange multiplier represents the surface forces, and the constraints are restricted to the boundary of the simulation domain. Having a uniform inf-sup bound, one can then establish optimal low-order a priori convergence rates for the discretization error in the primal and dual variables. In addition to the abstract framework of linear saddle-point theory, complementarity terms have to be taken into account. The resulting inequality system is solved by rewriting it equivalently by means of the non-linear complementarity function as a system of equations. Although it is not differentiable in the classical sense, semi-smooth Newton methods, yielding super-linear convergence rates, can be applied and easily implemented in terms of a primal-dual active set strategy. Quite often the solution of contact problems has a low regularity, and the efficiency of the approach can be improved by using adaptive refinement techniques. Different standard types, such as residual- and equilibrated-based a posteriori error estimators, can be designed based on the interpretation of the dual variable as Neumann boundary condition. For the fully dynamic setting it is of interest to apply energy-preserving time-integration schemes. However, the differential algebraic character of the system can result in high oscillations if standard methods are applied. A possible remedy is to modify the fully discretized system by a local redistribution of the mass. Numerical results in two and three dimensions illustrate the wide range of
Guidance and Control Concepts for the X-33 Technology Demonstrator
NASA Technical Reports Server (NTRS)
Dukeman, Gregory A.; Gallaher, Michael W.
1998-01-01
The X-33 technology demonstrator is a suborbital precursor to the Reusable Launch Vehicle (RLV) with first flight planned for summer of 1999. The flight test program will include about 15 flights originating from Edwards Air Force Base, California, each with widely varying flight profiles in order to test new thermal protection system (TPS) materials, structures, and linear aerospike engines. The first flights will be relatively short range flights with about a 300 nmi range, maximum Mach number of 7, maximum altitude of 190,000 feet, whereas the latter flights will cover about 800 nmi range, with max altitude of about 260,000 feet and max Mach of about 15. The guidance algorithms must be flexible enough to accommodate these various profiles and to adapt to severe off-nominal dispersions, such as early engine failure (partial or total) where possibly more than half the thrust is lost. An onboard real-time performance monitor will be used to assess the viability of the nominal landing site as well as alternate landing sites that would potentially be used in extreme off-nominal conditions. During ascent, a single entry guidance-related parameter, which is easy to calculate, is used to assess the viability of the nominal landing site as well as alternate landing sites. Real-time adjustment of the stored ascent attitude profile will be performed, as required, to maximize the probability of making it to the nominal landing site. Numerical results are given for various engine-out cases to illustrate the adaptability of the performance monitor.
Raising the Profile of Career Guidance: Educational and Vocational Guidance Practitioner
ERIC Educational Resources Information Center
Hiebert, Bryan
2009-01-01
In 2007 the International Association for Educational and Vocational Guidance (IAEVG) launched the Educational and Vocational Guidance Practitioner credential (EVGP) as one means of formally acknowledging the knowledge, skills, and personal attributes that practitioners need in order to provide quality career development services to clients. This…
Federal Register 2010, 2011, 2012, 2013, 2014
2013-06-20
... HUMAN SERVICES Food and Drug Administration Guidance for Industry; Guidance on Abbreviated New Drug Applications: Stability Testing of Drug Substances and Products; Availability AGENCY: Food and Drug Administration, HHS. ACTION: Notice. SUMMARY: The Food and Drug Administration (FDA or Agency) is announcing...
Federal Guidance Report No. 14 provides federal facilities that use diagnostic and interventional x-ray equipment with updated recommendations for keeping doses as low as reasonably achievable without compromising the quality of patient care, This guidance is an update of Federal...
NASA Technical Reports Server (NTRS)
Culp, Robert D. (Editor); Bickley, George (Editor)
1993-01-01
Papers from the sixteenth annual American Astronautical Society Rocky Mountain Guidance and Control Conference are presented. The topics covered include the following: advances in guidance, navigation, and control; control system videos; guidance, navigation and control embedded flight control systems; recent experiences; guidance and control storyboard displays; and applications of modern control, featuring the Hubble Space Telescope (HST) performance enhancement study.
ERIC Educational Resources Information Center
Jacobs, Karen; Struyf, Elke
2013-01-01
Socioemotional guidance of students has recently become an integral part of education, however no instrument exists to measure integrated socioemotional guidance. This study therefore examines the factor structure and reliability of the Socioemotional Guidance Questionnaire. Psychometric properties of the Socioemotional Guidance Questionnaire and…
VMT forecasting and tracking guidance, Section 187
Not Available
1992-01-01
The guidance is required by Section 187 (a) of the Clean Air Act Amendments of 1990. It offers the Environmental Protection Agency's (EPA's) recommendations on how to forecast and track vehicle miles traveled (VMT) in Moderate and Serious carbon monoxide (CO) non-attainment areas with design values greater than 12.7 ppm at the time of classification. The purpose of the guidance is to help states prepare State Implementation Plan (SIP) revisions that EPA can readily propose to approve as meeting the requirements of the Clean Air Act Amendments. If a state adheres to the guidance, EPA will propose approval of its SIP. A state intending to depart from the guidance, however, should show that the alternative approach it proposes is technically sound and adequate to meet the requirements of the Clean Air Act Amendments. EPA will review SIP submittals from such states on a case-by-case basis to determine whether they do in fact comply with the Clean Air Act Amendment requirements. States are encouraged to obtain EPA approval before using methods other than those specified in the guidance, in order to avoid later problems.
Safety of magnetic fusion facilities: Guidance
1996-05-01
This document provides guidance for the implementation of the requirements identified in DOE-STD-6002-96, Safety of Magnetic Fusion Facilities: Requirements. This guidance is intended for the managers, designers, operators, and other personnel with safety responsibilities for facilities designated as magnetic fusion facilities. While the requirements in DOE-STD-6002-96 are generally applicable to a wide range of fusion facilities, this Standard, DOE-STD-6003-96, is concerned mainly with the implementation of those requirements in large facilities such as the International Thermonuclear Experimental Reactor (ITER). Using a risk-based prioritization, the concepts presented here may also be applied to other magnetic fusion facilities. This Standard is oriented toward regulation in the Department of Energy (DOE) environment as opposed to regulation by other regulatory agencies. As the need for guidance involving other types of fusion facilities or other regulatory environments emerges, additional guidance volumes should be prepared. The concepts, processes, and recommendations set forth here are for guidance only. They will contribute to safety at magnetic fusion facilities.
Fine Guidance Sensing for Coronagraphic Observatories
NASA Technical Reports Server (NTRS)
Brugarolas, Paul; Alexander, James W.; Trauger, John T.; Moody, Dwight C.
2011-01-01
Three options have been developed for Fine Guidance Sensing (FGS) for coronagraphic observatories using a Fine Guidance Camera within a coronagraphic instrument. Coronagraphic observatories require very fine precision pointing in order to image faint objects at very small distances from a target star. The Fine Guidance Camera measures the direction to the target star. The first option, referred to as Spot, was to collect all of the light reflected from a coronagraph occulter onto a focal plane, producing an Airy-type point spread function (PSF). This would allow almost all of the starlight from the central star to be used for centroiding. The second approach, referred to as Punctured Disk, collects the light that bypasses a central obscuration, producing a PSF with a punctured central disk. The final approach, referred to as Lyot, collects light after passing through the occulter at the Lyot stop. The study includes generation of representative images for each option by the science team, followed by an engineering evaluation of a centroiding or a photometric algorithm for each option. After the alignment of the coronagraph to the fine guidance system, a "nulling" point on the FGS focal point is determined by calibration. This alignment is implemented by a fine alignment mechanism that is part of the fine guidance camera selection mirror. If the star images meet the modeling assumptions, and the star "centroid" can be driven to that nulling point, the contrast for the coronagraph will be maximized.
Guidance Trade-off for Aerocapture Missions
NASA Astrophysics Data System (ADS)
Vernis, P.; Gelly, G.; Ferreira, E.; da Costa, R.; Ortega, G.
In the very late 90's, EADS-ST began home funded studies on aerocapture problems. The objectives of these studies were at that time to prepare a possible cooperation within the NASA/Cnes MSR-Orbiter program by investigating this new orbital insertion technique studying different algorithmic solutions from a guidance point of view. According to these preliminary studies, EADS-ST was retained in 2002 by ESA to study insertion techniques such as aerocapture, aero-gravity assist or aerobraking techniques within the frame of Technological Research Program able to bring solutions to Aurora program. In the frame of the ATPE (Aeroassist Technologies for Planetary Exploration) TRP program, EADS-ST, led by Astrium-Gmbh (now part of EADS-ST), developed and implemented an efficient and simple guidance scheme able to cope with mission requirements for aerocapture on Mars, Venus or the Earth: the Feedback Trajectory Control, or FTC. The development of this guidance scheme was made according to a preliminary trade-off analysis using different guidance schemes. Among those ones was an original predictor-corrector guidance scheme, already analyzed within the frame of the MSR-O mission. But, the FTC algoritm was prefered because of its good results and high simplicity. This paper presents an upgrade of the original Apoapsis Predictor, or AP, with the improvement of its robustness woth respect to off-nomonal flight conditions and its process simplification. A new trade-off analysis is then detailed on a Mars Sample return mission.
NASA Astrophysics Data System (ADS)
Kinzig, Ann P.
2015-03-01
This paper is intended as a brief introduction to climate adaptation in a conference devoted otherwise to the physics of sustainable energy. Whereas mitigation involves measures to reduce the probability of a potential event, such as climate change, adaptation refers to actions that lessen the impact of climate change. Mitigation and adaptation differ in other ways as well. Adaptation does not necessarily have to be implemented immediately to be effective; it only needs to be in place before the threat arrives. Also, adaptation does not necessarily require global, coordinated action; many effective adaptation actions can be local. Some urban communities, because of land-use change and the urban heat-island effect, currently face changes similar to some expected under climate change, such as changes in water availability, heat-related morbidity, or changes in disease patterns. Concern over those impacts might motivate the implementation of measures that would also help in climate adaptation, despite skepticism among some policy makers about anthropogenic global warming. Studies of ancient civilizations in the southwestern US lends some insight into factors that may or may not be important to successful adaptation.
Application of Grazing-Inspired Guidance Laws to Autonomous Information Gathering
2014-09-01
Application of Grazing -Inspired Guidance Laws to Autonomous Information Gathering Thomas Apker Shih-Yuan Liu Donald Sofge J. Karl Hedrick Abstract...Domestic grazing animals follow simple, scalable rules to assign themselves trajectories to cover a pasture. We explain how to adapt these rules for an...scalability and robustness to failure are required. I. INTRODUCTION Biological systems such as domestic grazing animals ex- hibit efficient and
Software Safety Analysis of a Flight Guidance System
NASA Technical Reports Server (NTRS)
Butler, Ricky W. (Technical Monitor); Tribble, Alan C.; Miller, Steven P.; Lempia, David L.
2004-01-01
This document summarizes the safety analysis performed on a Flight Guidance System (FGS) requirements model. In particular, the safety properties desired of the FGS model are identified and the presence of the safety properties in the model is formally verified. Chapter 1 provides an introduction to the entire project, while Chapter 2 gives a brief overview of the problem domain, the nature of accidents, model based development, and the four-variable model. Chapter 3 outlines the approach. Chapter 4 presents the results of the traditional safety analysis techniques and illustrates how the hazardous conditions associated with the system trace into specific safety properties. Chapter 5 presents the results of the formal methods analysis technique model checking that was used to verify the presence of the safety properties in the requirements model. Finally, Chapter 6 summarizes the main conclusions of the study, first and foremost that model checking is a very effective verification technique to use on discrete models with reasonable state spaces. Additional supporting details are provided in the appendices.
Turbulent Output-Based Anisotropic Adaptation
NASA Technical Reports Server (NTRS)
Park, Michael A.; Carlson, Jan-Renee
2010-01-01
Controlling discretization error is a remaining challenge for computational fluid dynamics simulation. Grid adaptation is applied to reduce estimated discretization error in drag or pressure integral output functions. To enable application to high O(10(exp 7)) Reynolds number turbulent flows, a hybrid approach is utilized that freezes the near-wall boundary layer grids and adapts the grid away from the no slip boundaries. The hybrid approach is not applicable to problems with under resolved initial boundary layer grids, but is a powerful technique for problems with important off-body anisotropic features. Supersonic nozzle plume, turbulent flat plate, and shock-boundary layer interaction examples are presented with comparisons to experimental measurements of pressure and velocity. Adapted grids are produced that resolve off-body features in locations that are not known a priori.
Comparing the Discrete and Continuous Logistic Models
ERIC Educational Resources Information Center
Gordon, Sheldon P.
2008-01-01
The solutions of the discrete logistic growth model based on a difference equation and the continuous logistic growth model based on a differential equation are compared and contrasted. The investigation is conducted using a dynamic interactive spreadsheet. (Contains 5 figures.)
Dynamic discretization method for solving Kepler's equation
NASA Astrophysics Data System (ADS)
Feinstein, Scott A.; McLaughlin, Craig A.
2006-09-01
Kepler’s equation needs to be solved many times for a variety of problems in Celestial Mechanics. Therefore, computing the solution to Kepler’s equation in an efficient manner is of great importance to that community. There are some historical and many modern methods that address this problem. Of the methods known to the authors, Fukushima’s discretization technique performs the best. By taking more of a system approach and combining the use of discretization with the standard computer science technique known as dynamic programming, we were able to achieve even better performance than Fukushima. We begin by defining Kepler’s equation for the elliptical case and describe existing solution methods. We then present our dynamic discretization method and show the results of a comparative analysis. This analysis will demonstrate that, for the conditions of our tests, dynamic discretization performs the best.
Commutation Relations and Discrete Garnier Systems
NASA Astrophysics Data System (ADS)
Ormerod, Christopher M.; Rains, Eric M.
2016-11-01
We present four classes of nonlinear systems which may be considered discrete analogues of the Garnier system. These systems arise as discrete isomonodromic deformations of systems of linear difference equations in which the associated Lax matrices are presented in a factored form. A system of discrete isomonodromic deformations is completely determined by commutation relations between the factors. We also reparameterize these systems in terms of the image and kernel vectors at singular points to obtain a separate birational form. A distinguishing feature of this study is the presence of a symmetry condition on the associated linear problems that only appears as a necessary feature of the Lax pairs for the least degenerate discrete Painlevé equations.
Running Parallel Discrete Event Simulators on Sierra
Barnes, P. D.; Jefferson, D. R.
2015-12-03
In this proposal we consider porting the ROSS/Charm++ simulator and the discrete event models that run under its control so that they run on the Sierra architecture and make efficient use of the Volta GPUs.
A Few Continuous and Discrete Dynamical Systems
NASA Astrophysics Data System (ADS)
Zhang, Yufeng; Rui, Wenjuan
2016-08-01
Starting from a 2-unimodular group, we construct its new Lie algebras for which the positive-order Lax pairs and the negative-order Lax pairs are introduced, respectively. With the help of the resulting structure equation of the group we generate some partial differential equations including the well-known MKdV equation, the sine-Gordon equation, the hyperbolic sine-Gordon equation and other new nonlinear evolution equations. With the aid of the Tu scheme combined with the given Lax pairs, we obtain the isospectral and nonisospectral hierarchies of evolution equations, from which we generate two sets of symmetries of a generalized nonlinear Schrödinger (gNLS) equation. Finally, we discretize the Lax pairs to obtain a set of coupled semi-discrete equations. As their reduction, we produce the semi-discrete MKdV equation and semi-discrete NLS equation.
Motion of Discrete Interfaces Through Mushy Layers
NASA Astrophysics Data System (ADS)
Braides, Andrea; Solci, Margherita
2016-08-01
We study the geometric motion of sets in the plane derived from the homogenization of discrete ferromagnetic energies with weak inclusions. We show that the discrete sets are composed by a `bulky' part and an external `mushy region' composed only of weak inclusions. The relevant motion is that of the bulky part, which asymptotically obeys to a motion by crystalline mean curvature with a forcing term, due to the energetic contribution of the mushy layers, and pinning effects, due to discreteness. From an analytical standpoint, it is interesting to note that the presence of the mushy layers implies only a weak and not strong convergence of the discrete motions, so that the convergence of the energies does not commute with the evolution. From a mechanical standpoint it is interesting to note the geometrical similarity of some phenomena in the cooling of binary melts.
Vortex chains travelling with discrete velocities
NASA Astrophysics Data System (ADS)
Malishevskii, A. S.; Silin, V. P.; Uryupin, S. A.; Uspenskii, S. G.
2008-05-01
It has been shown that Swihart waves slowing down caused by Josephson junction spatial dispersion leads to the new field periodic nonlinear vortex states moving with discrete velocities. Swihart waves trapping by periodic vortex structures is discovered.
Discrete breathers in nonlinear magnetic metamaterials.
Lazarides, N; Eleftheriou, M; Tsironis, G P
2006-10-13
Magnetic metamaterials composed of split-ring resonators or U-type elements may exhibit discreteness effects in THz and optical frequencies due to weak coupling. We consider a model one-dimensional metamaterial formed by a discrete array of nonlinear split-ring resonators where each ring interacts with its nearest neighbors. On-site nonlinearity and weak coupling among the individual array elements result in the appearance of discrete breather excitations or intrinsic localized modes, both in the energy-conserved and the dissipative system. We analyze discrete single and multibreather excitations, as well as a special breather configuration forming a magnetization domain wall and investigate their mobility and the magnetic properties their presence induces in the system.
The discrete-time compensated Kalman filter
NASA Technical Reports Server (NTRS)
Lee, W. H.; Athans, M.
1978-01-01
A suboptimal dynamic compensator to be used in conjunction with the ordinary discrete time Kalman filter was derived. The resultant compensated Kalman Filter has the property that steady state bias estimation errors, resulting from modelling errors, were eliminated.
Radix Representation of Triangular Discrete Grid System
NASA Astrophysics Data System (ADS)
Ben, J.; Li, Y. L.; Wang, R.
2016-11-01
Discrete Global Grid Systems (DGGSs) are spatial references that use a hierarchical tessellation of cells to partition and address the entire globe. It provides an organizational structure that permits fast integration between multiple sources of large and variable geospatial data. Although many endeavors have been done to describe certain discrete grid systems, there still lack of a uniform mathematical framework for them. This paper simplifies the planar class I aperture 4 triangular discrete grid system into a hierarchical lattice model which is proved to be a radix system in the complex number plane. Mathematical properties of the radix system reveal the discrete grid system is equivalent to the set of complex numbers with special form. The conclusion provides a potential way to build a uniform mathematical framework of DGGS and can be used to design efficient encoding and spatial operation scheme for DGGS.
Discrete mechanics, "time machines" and hybrid systems
NASA Astrophysics Data System (ADS)
Elze, Hans-Thomas
2013-09-01
Modifying the discrete mechanics proposed by T.D. Lee, we construct a class of discrete classical Hamiltonian systems, in which time is one of the dynamical variables. This includes a toy model of "time machines" which can travel forward and backward in time and which differ from models based on closed timelike curves (CTCs). In the continuum limit, we explore the interaction between such time reversing machines and quantum mechanical objects, employing a recent description of quantum-classical hybrids.
Discrete Surface Modelling Using Partial Differential Equations.
Xu, Guoliang; Pan, Qing; Bajaj, Chandrajit L
2006-02-01
We use various nonlinear partial differential equations to efficiently solve several surface modelling problems, including surface blending, N-sided hole filling and free-form surface fitting. The nonlinear equations used include two second order flows, two fourth order flows and two sixth order flows. These nonlinear equations are discretized based on discrete differential geometry operators. The proposed approach is simple, efficient and gives very desirable results, for a range of surface models, possibly having sharp creases and corners.
Terminal Dynamics Approach to Discrete Event Systems
NASA Technical Reports Server (NTRS)
Zak, Michail; Meyers, Ronald
1995-01-01
This paper presents and discusses a mathematical formalism for simulation of discrete event dynamic (DED)-a special type of 'man-made' systems to serve specific purposes of information processing. The main objective of this work is to demonstrate that the mathematical formalism for DED can be based upon a terminal model of Newtonian dynamics which allows one to relax Lipschitz conditions at some discrete points.!.
HUMAN FACTORS GUIDANCE FOR CONTROL ROOM EVALUATION
OHARA,J.; BROWN,W.; STUBLER,W.; HIGGINS,J.; WACHTEL,J.; PERSENSKY,J.J.
2000-07-30
The Human-System Interface Design Review Guideline (NUREG-0700, Revision 1) was developed by the US Nuclear Regulatory Commission (NRC) to provide human factors guidance as a basis for the review of advanced human-system interface technologies. The guidance consists of three components: design review procedures, human factors engineering guidelines, and a software application to provide design review support called the ``Design Review Guideline.'' Since it was published in June 1996, Rev. 1 to NUREG-0700 has been used successfully by NRC staff, contractors and nuclear industry organizations, as well as by interested organizations outside the nuclear industry. The NRC has committed to the periodic update and improvement of the guidance to ensure that it remains a state-of-the-art design evaluation tool in the face of emerging and rapidly changing technology. This paper addresses the current research to update of NUREG-0700 based on the substantial work that has taken place since the publication of Revision 1.
The handling of causality in SEA guidance
Perdicoulis, A. . E-mail: tasso@utad.pt; Hanusch, M. . E-mail: marie.hanusch@ufz.de; Kasperidus, H.D. . E-mail: hans.kasperidus@ufz.de; Weiland, U. . E-mail: ulrike.weiland@ufz.de
2007-03-15
Causality, or the relation of cause and effect, is a fundamental notion in science, planning, and management. It is also a fundamental notion in impact assessment, as it relates action proposals with environmental impacts. Building on recent research about causality in impact assessment, this article turns to Strategic Environmental Assessment (SEA) and examines eleven guidance documents to see whether and how they handle causality. The findings of this research, in line with results from similar research in EIA, indicate a weak handling of causality with regards to instruction, obligation, and theoretical support. The recommendations are to investigate the reasons for the observed trend, as there is no evidence in the guidance documents themselves, and to have the fundamental premise of causality in impact assessment safeguarded in future SEA guidance.
VTOL shipboard letdown guidance system analysis
NASA Technical Reports Server (NTRS)
Phatak, A. V.; Karmali, M. S.
1983-01-01
Alternative letdown guidance strategies are examined for landing of a VTOL aircraft onboard a small aviation ship under adverse environmental conditions. Off line computer simulation of shipboard landing task is utilized for assessing the relative merits of the proposed guidance schemes. The touchdown performance of a nominal constant rate of descent (CROD) letdown strategy serves as a benchmark for ranking the performance of the alternative letdown schemes. Analysis of ship motion time histories indicates the existence of an alternating sequence of quiescent and rough motions called lulls and swells. A real time algorithms lull/swell classification based upon ship motion pattern features is developed. The classification algorithm is used to command a go/no go signal to indicate the initiation and termination of an acceptable landing window. Simulation results show that such a go/no go pattern based letdown guidance strategy improves touchdown performance.
Human Genetic Disorders of Axon Guidance
Engle, Elizabeth C.
2010-01-01
This article reviews symptoms and signs of aberrant axon connectivity in humans, and summarizes major human genetic disorders that result, or have been proposed to result, from defective axon guidance. These include corpus callosum agenesis, L1 syndrome, Joubert syndrome and related disorders, horizontal gaze palsy with progressive scoliosis, Kallmann syndrome, albinism, congenital fibrosis of the extraocular muscles type 1, Duane retraction syndrome, and pontine tegmental cap dysplasia. Genes mutated in these disorders can encode axon growth cone ligands and receptors, downstream signaling molecules, and axon transport motors, as well as proteins without currently recognized roles in axon guidance. Advances in neuroimaging and genetic techniques have the potential to rapidly expand this field, and it is feasible that axon guidance disorders will soon be recognized as a new and significant category of human neurodevelopmental disorders. PMID:20300212
Discretization of continuous features in clinical datasets
Maslove, David M; Podchiyska, Tanya; Lowe, Henry J
2013-01-01
Background The increasing availability of clinical data from electronic medical records (EMRs) has created opportunities for secondary uses of health information. When used in machine learning classification, many data features must first be transformed by discretization. Objective To evaluate six discretization strategies, both supervised and unsupervised, using EMR data. Materials and methods We classified laboratory data (arterial blood gas (ABG) measurements) and physiologic data (cardiac output (CO) measurements) derived from adult patients in the intensive care unit using decision trees and naïve Bayes classifiers. Continuous features were partitioned using two supervised, and four unsupervised discretization strategies. The resulting classification accuracy was compared with that obtained with the original, continuous data. Results Supervised methods were more accurate and consistent than unsupervised, but tended to produce larger decision trees. Among the unsupervised methods, equal frequency and k-means performed well overall, while equal width was significantly less accurate. Discussion This is, we believe, the first dedicated evaluation of discretization strategies using EMR data. It is unlikely that any one discretization method applies universally to EMR data. Performance was influenced by the choice of class labels and, in the case of unsupervised methods, the number of intervals. In selecting the number of intervals there is generally a trade-off between greater accuracy and greater consistency. Conclusions In general, supervised methods yield higher accuracy, but are constrained to a single specific application. Unsupervised methods do not require class labels and can produce discretized data that can be used for multiple purposes. PMID:23059731
Discrete mappings with an explicit discrete Lyapunov function related to integrable mappings
NASA Astrophysics Data System (ADS)
Inoue, Hironori; Takahashi, Daisuke; Matsukidaira, Junta
2006-05-01
We propose discrete mappings of second order that have a discrete analogue of Lyapunov function. The mappings are extensions of the integrable Quispel-Roberts-Thompson (QRT) mapping, and a discrete Lyapunov function of the mappings is identical to an explicit conserved quantity of the QRT mapping. Moreover we can obtain a differential and an ultradiscrete limit of the mappings preserving the existence of Lyapunov function. We also give applications of a mapping with an adjusted parameter, a probabilistic mapping and coupled mappings.
Development of mining guidance and control systems
NASA Technical Reports Server (NTRS)
1979-01-01
New fundamental interface sensor concepts were identified and investigated including tabulation of the physical and performance characteristics of two new interface detector concepts: - natural background radiation and magnetic spin resonance. Studies of guidance and control techniques for the longwall miner identified three basic systems for use in automated/remote controlled longwall mining. The following projects were initiated: system study which will more completely define the longwall guidance and control system design concepts; integration of the various control functions (vertical, yaw, and roll); and hardware technical requirements.
Ascent guidance algorithm using lidar wind measurements
NASA Technical Reports Server (NTRS)
Cramer, Evin J.; Bradt, Jerre E.; Hardtla, John W.
1990-01-01
The formulation of a general nonlinear programming guidance algorithm that incorporates wind measurements in the computation of ascent guidance steering commands is discussed. A nonlinear programming (NLP) algorithm that is designed to solve a very general problem has the potential to address the diversity demanded by future launch systems. Using B-splines for the command functional form allows the NLP algorithm to adjust the shape of the command profile to achieve optimal performance. The algorithm flexibility is demonstrated by simulation of ascent with dynamic loading constraints through a set of random wind profiles with and without wind sensing capability.
CNES Approaching Guidance Experiment within FFIORD
NASA Technical Reports Server (NTRS)
Berges, Jean-Claude; Cayeux, Philippe; Gaudel-Vacaresse, Angelique; Meyssignac, Benoit
2007-01-01
This article outlines the relative orbit control (guidance algorithm and its preliminary performance tests evaluation) that will be tested by the CNES Team on FFIORD (Formation Flying In Orbit Ranging Demonstration) onboard PRISMA mission. After a brief summary of the PRISMA mission context, the paper provides a full description of the rendezvous function involved in the approaching guidance experiment. This FFIORD onboard function is detailed in terms of on-board algorithmic method (basic algorithm and enhanced alternative), sensibility analysis used to construct maneuver plans and preliminary tests results.
Overcoming Consumer Inertia to Dietary Guidance12
Webb, Densie; Byrd-Bredbenner, Carol
2015-01-01
Despite 35 y of dietary guidance, there has been no substantial shift in consumer compliance. Consumers report that they seek information on nutrition and healthy eating, but most are not paying attention to dietary recommendations. For guidance to be effective, it must be realistic. Even with increasingly detailed nutrition information and evidence that diet affects health outcomes, convenience and taste remain the strongest determinants of food choices. It is up to health educators to clear up confusion and give consumers control with nutrition messages that are realistic, positive, easy to understand, and actionable without an expectation that consumers will surrender foods they love. PMID:26178023
Aeroassist flight experiment guidance, navigation and control
NASA Technical Reports Server (NTRS)
Brand, Timothy J.; Engel, Albert G.
1986-01-01
The Aeroassist Flight Experiment scheduled for the early 1990's will demonstrate the use of a low L/D lifting brake using aerodynamic drag to return a spacecraft from a high energy to a low earth orbit. The experimental vehicle will be deployed and retrieved by the Shuttle Orbiter. This paper reviews some of the challenges, problems, and solutions encountered to date during guidance system development, with emphasis on technology advances which will benefit an operational Orbit Transfer Vehicle (OTV). Key factors to be discussed include guidance alternatives, aerodynamic modeling, navigation requirements, the impact of atmospheric uncertainties, and flight profile alternatives considered during initial planning.
Overcoming consumer inertia to dietary guidance.
Webb, Densie; Byrd-Bredbenner, Carol
2015-07-01
Despite 35 y of dietary guidance, there has been no substantial shift in consumer compliance. Consumers report that they seek information on nutrition and healthy eating, but most are not paying attention to dietary recommendations. For guidance to be effective, it must be realistic. Even with increasingly detailed nutrition information and evidence that diet affects health outcomes, convenience and taste remain the strongest determinants of food choices. It is up to health educators to clear up confusion and give consumers control with nutrition messages that are realistic, positive, easy to understand, and actionable without an expectation that consumers will surrender foods they love.
Finite-time intercept-angle guidance
NASA Astrophysics Data System (ADS)
Lu, Kunfeng; Xia, Yuanqing; Yu, Chunmei; Chen, Rongfang
2015-02-01
In this paper, new nonsingular terminal sliding mode control guidance laws (NTSMCGLs) to unknown maneuvering target intercept are proposed and their finite-time convergences are proved. A novel nonsingular terminal sliding mode surface based on a predefined angle is designed to improve intercept performance and avoid singularity problem. The presented guidance law requires no information on maneuvering target that is estimated and compensated by extended state observer (ESO), and it can be used in practical systems where the target can evade freely. Also, undesired chattering is restrained effectively by real-time estimation and compensation of ESO. Simulation results show that the NTSMCGLs can achieve exact interception.
Aerospace plane guidance using geometric control theory
NASA Technical Reports Server (NTRS)
Van Buren, Mark A.; Mease, Kenneth D.
1990-01-01
A reduced-order method employing decomposition, based on time-scale separation, of the 4-D state space in a 2-D slow manifold and a family of 2-D fast manifolds is shown to provide an excellent approximation to the full-order minimum-fuel ascent trajectory. Near-optimal guidance is obtained by tracking the reduced-order trajectory. The tracking problem is solved as regulation problems on the family of fast manifolds, using the exact linearization methodology from nonlinear geometric control theory. The validity of the overall guidance approach is indicated by simulation.
Virtual Ultrasound Guidance for Inexperienced Operators
NASA Technical Reports Server (NTRS)
Caine, Timothy; Martin, David
2012-01-01
Medical ultrasound or echocardiographic studies are highly operator-dependent and generally require lengthy training and internship to perfect. To obtain quality echocardiographic images in remote environments, such as on-orbit, remote guidance of studies has been employed. This technique involves minimal training for the user, coupled with remote guidance from an expert. When real-time communication or expert guidance is not available, a more autonomous system of guiding an inexperienced operator through an ultrasound study is needed. One example would be missions beyond low Earth orbit in which the time delay inherent with communication will make remote guidance impractical. The Virtual Ultrasound Guidance system is a combination of hardware and software. The hardware portion includes, but is not limited to, video glasses that allow hands-free, full-screen viewing. The glasses also allow the operator a substantial field of view below the glasses to view and operate the ultrasound system. The software is a comprehensive video program designed to guide an inexperienced operator through a detailed ultrasound or echocardiographic study without extensive training or guidance from the ground. The program contains a detailed description using video and audio to demonstrate equipment controls, ergonomics of scanning, study protocol, and scanning guidance, including recovery from sub-optimal images. The components used in the initial validation of the system include an Apple iPod Classic third-generation as the video source, and Myvue video glasses. Initially, the program prompts the operator to power-up the ultrasound and position the patient. The operator would put on the video glasses and attach them to the video source. After turning on both devices and the ultrasound system, the audio-video guidance would then instruct on patient positioning and scanning techniques. A detailed scanning protocol follows with descriptions and reference video of each view along with
Guidance accuracy considerations for realtime GPS interferometry
NASA Technical Reports Server (NTRS)
Braasch, Michael S.; Van Graas, Frank
1991-01-01
During April and May of 1991, the Avionics Engineering Center at Ohio University completed the first set of realtime flight tests of a GPS interferometric attitude and heading determination system. This technique has myriad applications for aircraft and spacecraft guidance and control. However, before these applications can be further developed, a number of guidance accuracy issues must be considered. Among these are: signal derogation due to multipath and shadowing, effects of structural flexures, and system robustness during loss of phase lock. This paper addresses these issues with special emphasis on the information content of the GPS signal, and characterization and mitigation of multipath encountered while in flight.
A Bell-Curved Based Algorithm for Mixed Continuous and Discrete Structural Optimization
NASA Technical Reports Server (NTRS)
Kincaid, Rex K.; Weber, Michael; Sobieszczanski-Sobieski, Jaroslaw
2001-01-01
An evolutionary based strategy utilizing two normal distributions to generate children is developed to solve mixed integer nonlinear programming problems. This Bell-Curve Based (BCB) evolutionary algorithm is similar in spirit to (mu + mu) evolutionary strategies and evolutionary programs but with fewer parameters to adjust and no mechanism for self adaptation. First, a new version of BCB to solve purely discrete optimization problems is described and its performance tested against a tabu search code for an actuator placement problem. Next, the performance of a combined version of discrete and continuous BCB is tested on 2-dimensional shape problems and on a minimum weight hub design problem. In the latter case the discrete portion is the choice of the underlying beam shape (I, triangular, circular, rectangular, or U).
On the Dynamics of Some Discretizations of Convection-Diffusion Equations
NASA Technical Reports Server (NTRS)
Sweby, Peter K.; Yee, H. C.; Rai, Man Mohan (Technical Monitor)
1995-01-01
Numerical discretizations of differential equations which model physical processes can possess dynamics quite different from that of the equations themselves. Recently the emphasis has been on the the dynamics of numerical discretizations for Ordinary Differential Equations (ODEs). For Partial Differential Equations (PDEs) using a method of lines approach the situation is more complex. First, the spatial discretisation may introduce dynamics not present in the original equations; second, the solution of the resulting system of ODEs is open to the modified dynamics of the ODE solver used. These two effects may interact in a complex manner. In this talk we present some results of our recent work on the dynamics of discretizations of convection-diffusion equations, including those produced using Total Variation Diminishing (TVD) schemes and adaptive grid techniques. A more general overview of the area may be found on our accompanying poster presentation.
Wang, Renxin; Wang, Wei; Li, Zhihong
2016-01-01
Silicon microneedle arrays (MNAs) have been widely studied due to their potential in various transdermal applications. However, discrete MNAs, as a preferred choice to fabricate flexible penetrating devices that could adapt curved and elastic tissue, are rarely reported. Furthermore, the reported discrete MNAs have disadvantages lying in uniformity and height-pitch ratio. Therefore, an improved technique is developed to manufacture discrete MNA with tunable height-pitch ratio, which involves KOH-dicing-KOH process. The detailed process is sketched and simulated to illustrate the formation of microneedles. Furthermore, the undercutting of convex mask in two KOH etching steps are mathematically analyzed, in order to reveal the relationship between etching depth and mask dimension. Subsequently, fabrication results demonstrate KOH-dicing-KOH process. {321} facet is figured out as the surface of octagonal pyramid microneedle. MNAs with diverse height and pitch are also presented to identify the versatility of this approach. At last, the metallization is realized via successive electroplating. PMID:27735837
Wang, Renxin; Wang, Wei; Li, Zhihong
2016-10-09
Silicon microneedle arrays (MNAs) have been widely studied due to their potential in various transdermal applications. However, discrete MNAs, as a preferred choice to fabricate flexible penetrating devices that could adapt curved and elastic tissue, are rarely reported. Furthermore, the reported discrete MNAs have disadvantages lying in uniformity and height-pitch ratio. Therefore, an improved technique is developed to manufacture discrete MNA with tunable height-pitch ratio, which involves KOH-dicing-KOH process. The detailed process is sketched and simulated to illustrate the formation of microneedles. Furthermore, the undercutting of convex mask in two KOH etching steps are mathematically analyzed, in order to reveal the relationship between etching depth and mask dimension. Subsequently, fabrication results demonstrate KOH-dicing-KOH process. {321} facet is figured out as the surface of octagonal pyramid microneedle. MNAs with diverse height and pitch are also presented to identify the versatility of this approach. At last, the metallization is realized via successive electroplating.
A comparison of error-correction procedures on skill acquisition during discrete-trial instruction.
Carroll, Regina A; Joachim, Brad T; St Peter, Claire C; Robinson, Nicole
2015-01-01
Previous research supports the use of a variety of error-correction procedures to facilitate skill acquisition during discrete-trial instruction. We used an adapted alternating treatments design to compare the effects of 4 commonly used error-correction procedures on skill acquisition for 2 children with attention deficit hyperactivity disorder and 3 children with autism spectrum disorder. For all participants, multiple error-correction procedures were effective; however, 1 or 2 specific error-correction procedures led to more efficient skill acquisition for each individual. These results highlight the importance of evaluating the effectiveness and efficiency of error-correction procedures for individual learners during discrete-trial instruction. We discuss the use of discrete-trial instruction with different populations, implications for using multiple measures of procedural efficiency, and several areas for future research.
Unstructured Adaptive Meshes: Bad for Your Memory?
NASA Technical Reports Server (NTRS)
Biswas, Rupak; Feng, Hui-Yu; VanderWijngaart, Rob
2003-01-01
This viewgraph presentation explores the need for a NASA Advanced Supercomputing (NAS) parallel benchmark for problems with irregular dynamical memory access. This benchmark is important and necessary because: 1) Problems with localized error source benefit from adaptive nonuniform meshes; 2) Certain machines perform poorly on such problems; 3) Parallel implementation may provide further performance improvement but is difficult. Some examples of problems which use irregular dynamical memory access include: 1) Heat transfer problem; 2) Heat source term; 3) Spectral element method; 4) Base functions; 5) Elemental discrete equations; 6) Global discrete equations. Nonconforming Mesh and Mortar Element Method are covered in greater detail in this presentation.
Adaptive broadening to improve spectral resolution in the numerical renormalization group
NASA Astrophysics Data System (ADS)
Lee, Seung-Sup B.; Weichselbaum, Andreas
2016-12-01
We propose an adaptive scheme of broadening the discrete spectral data from numerical renormalization group (NRG) calculations to improve the resolution of dynamical properties at finite energies. While the conventional scheme overbroadens narrow features at large frequency by broadening discrete weights with constant width in log-frequency, our scheme broadens each discrete contribution individually based on its sensitivity to a z -shift in the logarithmic discretization intervals. We demonstrate that the adaptive broadening better resolves various features in noninteracting and interacting models at comparable computational cost. The resolution enhancement is more significant for coarser discretization as typically required in multiband calculations. At low frequency below the energy scale of temperature, the discrete NRG data necessarily needs to be broadened on a linear scale. Here we provide a method that minimizes transition artifacts in between these broadening kernels.
Light Adaptation in the Ventral Photoreceptor of Limulus
Srebro, Richard; Behbehani, Michael
1974-01-01
Light adaptation in both the ventral photoreceptor and the lateral eye photoreceptor is a complex process consisting of at least two phases. One phase, which we call the rapid phase of adaptation, occurs whenever there is temporal overlap of the discrete waves that compose a light response. The recovery from the rapid phase of adaptation follows an exponential time-course with a time constant of approximately 75 ms at 21°C. The rapid phase of adaptation occurs at light intensities barely above discrete wave threshold as well as at substantially higher light intensities with the same recovery time-course at all intensities. It occurs in voltage-clamped and unclamped photoreceptors. The kinetics of the rapid phase of adaptation is closely correlated to the photocurrent which appears to initiate it after a short delay. The rapid phase of adaptation is probably identical to what is called the "adapting bump" process. At light intensities greater than about 10 times discrete wave threshold another phase of light adaptation occurs. It develops slowly over a period of ½ s or so, and decays even more slowly over a period of several seconds. It is graded with light intensity and occurs in both voltage-clamped and unclamped photoreceptors. We call this the slow phase of light adaptation. PMID:4846765
Discrete emotion-congruent false memories in the DRM paradigm.
Bland, Cassandra E; Howe, Mark L; Knott, Lauren
2016-08-01
Research has shown that false-memory production is enhanced for material that is emotionally congruent with the mood of the participant at the time of encoding. So far this research has only been conducted to examine the influence of generic negative affective mood states and generic negative stimuli on false-memory production. In addition, much of the research is limited as it focuses on valence and arousal dimensions, and fails to take into account the more comprehensive nature of emotions. The current study demonstrates that this effect goes beyond general negative or positive moods and acts at a more discrete emotional level. Participants underwent a standard emotion-induction procedure before listening to negative emotional or neutral associative word lists. The emotions induced, negative word lists, and associated nonpresented critical lures, were related to either fear or anger, 2 negative valence emotions that are also both high in arousal. Results showed that when valence and arousal are controlled for, false memories are more likely to be produced for discrete emotionally congruent compared with incongruent materials. These results support spreading activation theories of false remembering and add to our understanding of the adaptive nature of false-memory production. (PsycINFO Database Record
ERIC Educational Resources Information Center
Exceptional Parent, 1987
1987-01-01
Suggestions are presented for helping disabled individuals learn to use or adapt toothbrushes for proper dental care. A directory lists dental health instructional materials available from various organizations. (CB)
Dynamics of movement patterning in learning a discrete multiarticular action.
Chow, Jia Yi; Davids, Keith; Button, Chris; Rein, Robert
2008-07-01
From a nonlinear dynamics perspective, presence of movement variability before a change in preferred movement patterns is hypothesized to afford the necessary adaptability and flexibility for seeking novel functional behaviors. In this study, four novice participants practiced a discrete multiarticular movement for 12 sessions over 4 weeks. Cluster analysis procedures revealed how changes between preferred movement patterns were affected with and without the presence of variability in movement clusters before a defined change. Performance improved in all participants as a function of practice. Participants typically showed evidence of change between preferred movement clusters and higher variability in the use of movement clusters within a session. However, increasing variability in movement clusters was not always accompanied by transition from one preferred movement cluster to another. In summary, it was observed that intentional and informational constraints play an important role in influencing the specific pathway of change for individual learners as they search for new preferred movement patterns.
Discrete extremal lengths of graph approximations of Sierpinski carpets
NASA Astrophysics Data System (ADS)
Malo, Robert Jason
The study of mathematical objects that are not smooth or regular has grown in importance since Benoit Mandelbrot's foundational work in the in the late 1960s. The geometry of fractals has many of its roots in that work. An important measurement of the size and structure of fractals is their dimension. We discuss various ways to describe a fractal in its canonical form. We are most interested in a concept of dimension introduced by Pierre Pansu in 1989, that of the conformal dimension. We focus on an open question: what is the conformal dimension of the Sierpinski carpet? In this work we adapt an algorithm by Oded Schramm to calculate the discrete extremal length in graph approximations of the Sierpinski carpet. We apply a result by Matias Piaggio to relate the extremal length to the Ahlfors-regular conformal dimension. We find strong numeric evidence suggesting both a lower and upper bound for this dimension.
Seleson, Pablo; Du, Qiang; Parks, Michael L.
2016-08-16
The peridynamic theory of solid mechanics is a nonlocal reformulation of the classical continuum mechanics theory. At the continuum level, it has been demonstrated that classical (local) elasticity is a special case of peridynamics. Such a connection between these theories has not been extensively explored at the discrete level. This paper investigates the consistency between nearest-neighbor discretizations of linear elastic peridynamic models and finite difference discretizations of the Navier–Cauchy equation of classical elasticity. While nearest-neighbor discretizations in peridynamics have been numerically observed to present grid-dependent crack paths or spurious microcracks, this paper focuses on a different, analytical aspect of suchmore » discretizations. We demonstrate that, even in the absence of cracks, such discretizations may be problematic unless a proper selection of weights is used. Specifically, we demonstrate that using the standard meshfree approach in peridynamics, nearest-neighbor discretizations do not reduce, in general, to discretizations of corresponding classical models. We study nodal-based quadratures for the discretization of peridynamic models, and we derive quadrature weights that result in consistency between nearest-neighbor discretizations of peridynamic models and discretized classical models. The quadrature weights that lead to such consistency are, however, model-/discretization-dependent. We motivate the choice of those quadrature weights through a quadratic approximation of displacement fields. The stability of nearest-neighbor peridynamic schemes is demonstrated through a Fourier mode analysis. Finally, an approach based on a normalization of peridynamic constitutive constants at the discrete level is explored. This approach results in the desired consistency for one-dimensional models, but does not work in higher dimensions. The results of the work presented in this paper suggest that even though nearest
PREFACE: 4th Symposium on Prospects in the Physics of Discrete Symmetries (DISCRETE2014)
NASA Astrophysics Data System (ADS)
Di Domenico, Antonio; Mavromatos, Nick E.; Mitsou, Vasiliki A.; Skliros, Dimitri P.
2015-07-01
The DISCRETE 2014: Fourth Symposium in the Physics of Discrete Symmetries took place at King's College London, Strand Campus, London WC2R 2LS, from Tuesday, December 2 2014 till Saturday, December 6 2014. This is the fourth Edition of the DISCRETE conference series, which is a biannual event, having been held previously in Valencia (Discrete'08), Rome (Discrete2010) and Lisbon (Discrete2012). The topics covered at the DISCRETE series of conferences are: T, C, P, CP symmetries; accidental symmetries (B, L conservation); CPT symmetry, decoherence and entangled states, Lorentz symmetry breaking (phenomenology and current bounds); neutrino mass and mixing; implications for cosmology and astroparticle physics, dark matter searches; experimental prospects at LHC, new facilities. In DISCRETE 2014 we have also introduced two new topics: cosmological aspects of non-commutative space-times as well as PT symmetric Hamiltonians (non-Hermitian but with real eigenvalues), a topic that has wide applications in particle physics and beyond. The conference was opened by the King's College London Vice Principal on Research and Innovation, Mr Chris Mottershead, followed by a welcome address by the Chair of DISCRETE 2014 (Professor Nick E. Mavromatos). After these introductory talks, the scientific programme of the DISCRETE 2014 symposium started. Following the tradition of DISCRETE series of conferences, the talks (138 in total) were divided into plenary-review talks (25), invited research talks (50) and shorter presentations (63) — selected by the conveners of each session in consultation with the organisers — from the submitted abstracts. We have been fortunate to have very high-quality, thought stimulating and interesting talks at all levels, which, together with the discussions among the participants, made the conference quite enjoyable. There were 152 registered participants for the event.
Enhancements on the Convex Programming Based Powered Descent Guidance Algorithm for Mars Landing
NASA Technical Reports Server (NTRS)
Acikmese, Behcet; Blackmore, Lars; Scharf, Daniel P.; Wolf, Aron
2008-01-01
In this paper, we present enhancements on the powered descent guidance algorithm developed for Mars pinpoint landing. The guidance algorithm solves the powered descent minimum fuel trajectory optimization problem via a direct numerical method. Our main contribution is to formulate the trajectory optimization problem, which has nonconvex control constraints, as a finite dimensional convex optimization problem, specifically as a finite dimensional second order cone programming (SOCP) problem. SOCP is a subclass of convex programming, and there are efficient SOCP solvers with deterministic convergence properties. Hence, the resulting guidance algorithm can potentially be implemented onboard a spacecraft for real-time applications. Particularly, this paper discusses the algorithmic improvements obtained by: (i) Using an efficient approach to choose the optimal time-of-flight; (ii) Using a computationally inexpensive way to detect the feasibility/ infeasibility of the problem due to the thrust-to-weight constraint; (iii) Incorporating the rotation rate of the planet into the problem formulation; (iv) Developing additional constraints on the position and velocity to guarantee no-subsurface flight between the time samples of the temporal discretization; (v) Developing a fuel-limited targeting algorithm; (vi) Initial result on developing an onboard table lookup method to obtain almost fuel optimal solutions in real-time.
Carstensen, C.; Feischl, M.; Page, M.; Praetorius, D.
2014-01-01
This paper aims first at a simultaneous axiomatic presentation of the proof of optimal convergence rates for adaptive finite element methods and second at some refinements of particular questions like the avoidance of (discrete) lower bounds, inexact solvers, inhomogeneous boundary data, or the use of equivalent error estimators. Solely four axioms guarantee the optimality in terms of the error estimators. Compared to the state of the art in the temporary literature, the improvements of this article can be summarized as follows: First, a general framework is presented which covers the existing literature on optimality of adaptive schemes. The abstract analysis covers linear as well as nonlinear problems and is independent of the underlying finite element or boundary element method. Second, efficiency of the error estimator is neither needed to prove convergence nor quasi-optimal convergence behavior of the error estimator. In this paper, efficiency exclusively characterizes the approximation classes involved in terms of the best-approximation error and data resolution and so the upper bound on the optimal marking parameters does not depend on the efficiency constant. Third, some general quasi-Galerkin orthogonality is not only sufficient, but also necessary for the R-linear convergence of the error estimator, which is a fundamental ingredient in the current quasi-optimality analysis due to Stevenson 2007. Finally, the general analysis allows for equivalent error estimators and inexact solvers as well as different non-homogeneous and mixed boundary conditions. PMID:25983390
Guidance Program Evaluation: What's Out There?
ERIC Educational Resources Information Center
Miller, Juliet V.; Grisdale, George A.
1975-01-01
This article reviews a number of guidance evaluation materials and programs presently in use in terms of Stufflebeam's CIPP model. Some materials were simple evaluation instruments; others were as comprehensive as process guides for the planning, development, and application of a complete systems approach evaluation. (Author)
Computer-Based Vocational Guidance Systems.
ERIC Educational Resources Information Center
Gallagher, James J., Ed.
Job and educational opportunities are increasing dramatically. School guidance counselors can no longer cope adequately with the available information, nor can they help all students to see the complex range of alternative life styles. Computers are now programed to give students information. They can also provide for students' decision-making…
Computer Applications in Guidance and Counseling.
ERIC Educational Resources Information Center
Havens, Robert I.
The purpose of this discussion is to acquaint pupil personnel workers with some of the applications of computer based information processing systems for pupil services and also to consider some of the legal and ethical concerns relative to data processing in counseling and guidance. Some of the uses discussed are: (1) scheduling; (2) student…
Decisions & Values. Intermediate Level. Career Guidance.
ERIC Educational Resources Information Center
Cooper, Irene
Materials contained in this career guidance unit are designed to aid ten- and eleven-year-old students in becoming effective problem solvers, and to bring to attention the relationship between an individual's values and decisions. Skill in using a simplified problem solving technique introduced in the primary grades (Decision Making, Levels…
Guidance for an aeroassisted orbital transfer vehicle
NASA Technical Reports Server (NTRS)
Hall, Kenneth R.
1988-01-01
The use of atmospheric drag for slowing satellite in high energy, high apogee orbits to a lower energy, lower apogee orbit about the Earth is investigated. The high energy orbit is assumed to intercept the Earth's atmosphere. Guidance for the atmospheric phase of the trajectory may be done using the aerodynamic forces generated by the passage through the atmosphere. This research was concerned with the investigation of several methods of guidance during the atmospheric phase to cause a significant reduction in the final velocity as the vehicle leaves the atmosphere. In addition, the velocity direction was controlled to exit to a desired target orbit. Lastly excess aerodynamic lift was used to effect a plane change between the entry orbit plane and the exit orbit plane to achieve a desired orbit plane. The guidance methods were applied to a 3 degree-of-freedom simulation which included an oblate Earth gravity model and a rotating atmosphere. Simulation results were compared on the basis of speed of computation of the guidance parameters and amount of added velocity necessary to achieve the desired orbit.
21 CFR 314.445 - Guidance documents.
Code of Federal Regulations, 2010 CFR
2010-04-01
... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DRUGS FOR HUMAN USE APPLICATIONS FOR FDA APPROVAL TO MARKET A NEW DRUG Miscellaneous Provisions § 314.445 Guidance... directed to the Office of Training and Communications, Division of Drug Information, Center for...
Epilepsy in the Classroom: Guidance for Educators.
ERIC Educational Resources Information Center
Lassner, Lee M.
This paper for educators, school psychologists, and counselors attempts to provide guidance for meeting the needs of students with epilepsy. Stressed throughout the paper are ways to provide for the child's special needs while fostering his/her self esteem and full participation in classroom activities. The paper addresses the following topics:…
Assessing Enterprise Capability: Guidance for Schools
ERIC Educational Resources Information Center
National Foundation for Educational Research, 2007
2007-01-01
This document offers guidance to schools on how assessment can support enterprise education. It presents the interim findings from research carried out by the National Foundation for Educational Research (NFER) for the Department for Education and Skills (DfES) in secondary schools in England. Enterprise capability is the key outcome of enterprise…
Online guidance updates using neural networks
NASA Astrophysics Data System (ADS)
Filici, Cristian; Sánchez Peña, Ricardo S.
2010-02-01
The aim of this article is to present a method for the online guidance update for a launcher ascent trajectory that is based on the utilization of a neural network approximator. Generation of training patterns and selection of the input and output spaces of the neural network are presented, and implementation issues are discussed. The method is illustrated by a 2-dimensional launcher simulation.
Money, Money, Money: A Developmental Guidance Approach.
ERIC Educational Resources Information Center
Allan, John; Klassen, Garry
1992-01-01
Describes developmental guidance unit on topic of money for grades six and seven. Describes class discussion format used to conduct two sessions helping students explore, understand, and develop coping skills regarding money issues. Notes that students worried about money, understood why people overspend, and developed ways of earning and saving…
Career Guidance Policy: An International Review
ERIC Educational Resources Information Center
Watts, A. G.
2005-01-01
The Organization for Economic Co-operation and Development, the World Bank, and the European Commission have conducted reviews of the career guidance policies and practices in 37 countries. The 37 country studies, together with the 3 synthesis reports and a number of other commissioned papers, constitute the largest database on career guidance…
A Workable Program of Career Guidance
ERIC Educational Resources Information Center
Hunt, Myrtle E.
1974-01-01
Seven observations made by a career education team (a counselor, an occupational specialist, and classroom teachers) provided the basis for establishing career guidance goals. The goals were devoloped around the accepted elements of career education and implemented in a teacher-counselor shared accountability effort in Florida's Pinellas County.…