HAMMERAND,DANIEL C.; KAPANIA,RAKESH K.
2000-05-01
A triangular flat shell element for large deformation analysis of linear viscoelastic laminated composites is presented. Hygrothermorheologically simple materials are considered for which a change in the hygrothermal environment results in a horizontal shifting of the relaxation moduli curves on a log time scale, in addition to the usual hygrothermal loads. Recurrence relations are developed and implemented for the evaluation of the viscoelastic memory loads. The nonlinear deformation process is computed using an incremental/iterative approach with the Newton-Raphson Method used to find the incremental displacements in each step. The presented numerical examples consider the large deformation and stability of linear viscoelastic structures under deformation-independent mechanical loads, deformation-dependent pressure loads, and thermal loads. Unlike elastic structures that have a single critical load value associated with a given snapping of buckling instability phenomenon, viscoelastic structures will usually exhibit a particular instability for a range of applied loads over a range of critical times. Both creep buckling and snap-through examples are presented here. In some cases, viscoelastic results are also obtained using the quasielastic method in which load-history effects are ignored, and time-varying viscoelastic properties are simply used in a series of elastic problems. The presented numerical examples demonstrate the capability and accuracy of the formulation.
Practical Session: Simple Linear Regression
NASA Astrophysics Data System (ADS)
Clausel, M.; Grégoire, G.
2014-12-01
Two exercises are proposed to illustrate the simple linear regression. The first one is based on the famous Galton's data set on heredity. We use the lm R command and get coefficients estimates, standard error of the error, R2, residuals …In the second example, devoted to data related to the vapor tension of mercury, we fit a simple linear regression, predict values, and anticipate on multiple linear regression. This pratical session is an excerpt from practical exercises proposed by A. Dalalyan at EPNC (see Exercises 1 and 2 of http://certis.enpc.fr/~dalalyan/Download/TP_ENPC_4.pdf).
Linear Deterministic Accumulator Models of Simple Choice
Heathcote, Andrew; Love, Jonathon
2012-01-01
We examine theories of simple choice as a race among evidence accumulation processes. We focus on the class of deterministic race models, which assume that the effects of fluctuations in the parameters of the accumulation processes between-choice trials (between-choice noise) dominate the effects of fluctuations occurring while making a choice (within-choice noise) in behavioral data (i.e., response times and choices). The latter deterministic approximation, when combined with the assumption that accumulation is linear, leads to a class of models that can be readily applied to simple-choice behavior because they are computationally tractable. We develop a new and mathematically simple exemplar within the class of linear deterministic models, the Lognormal race (LNR). We then examine how the LNR, and another widely applied linear deterministic model, Brown and Heathcote’s (2008) LBA, account for a range of benchmark simple-choice effects in lexical-decision task data reported by Wagenmakers et al. (2008). Our results indicate that the LNR provides an accurate description of this data. Although the LBA model provides a slightly better account, both models support similar psychological conclusions. PMID:22936920
Simple analytic potentials for linear ion traps
NASA Technical Reports Server (NTRS)
Janik, G. R.; Prestage, J. D.; Maleki, L.
1990-01-01
A simple analytical model was developed for the electric and ponderomotive (trapping) potentials in linear ion traps. This model was used to calculate the required voltage drive to a mercury trap, and the result compares well with experiments. The model gives a detailed picture of the geometric shape of the trapping potential and allows an accurate calculation of the well depth. The simplicity of the model allowed an investigation of related, more exotic trap designs which may have advantages in light-collection efficiency.
Simple analytic potentials for linear ion traps
NASA Technical Reports Server (NTRS)
Janik, G. R.; Prestage, J. D.; Maleki, L.
1989-01-01
A simple analytical model was developed for the electric and ponderomotive (trapping) potentials in linear ion traps. This model was used to calculate the required voltage drive to a mercury trap, and the result compares well with experiments. The model gives a detailed picture of the geometric shape of the trapping potenital and allows an accurate calculation of the well depth. The simplicity of the model allowed an investigation of related, more exotic trap designs which may have advantages in light-collection efficiency.
Linear Programming Applied to a Simple Circuit.
ERIC Educational Resources Information Center
Boyd, J. N.; Raychowdhury, P. N.
1980-01-01
Discusses what is meant by a linear program and states and illustrates two of the theorems upon which the methods of linear programing rest. This description is intended as an introduction to linear programing of physics students. (HM)
Mental chronometry with simple linear regression.
Chen, J Y
1997-10-01
Typically, mental chronometry is performed by means of introducing an independent variable postulated to affect selectively some stage of a presumed multistage process. However, the effect could be a global one that spreads proportionally over all stages of the process. Currently, there is no method to test this possibility although simple linear regression might serve the purpose. In the present study, the regression approach was tested with tasks (memory scanning and mental rotation) that involved a selective effect and with a task (word superiority effect) that involved a global effect, by the dominant theories. The results indicate (1) the manipulation of the size of a memory set or of angular disparity affects the intercept of the regression function that relates the times for memory scanning with different set sizes or for mental rotation with different angular disparities and (2) the manipulation of context affects the slope of the regression function that relates the times for detecting a target character under word and nonword conditions. These ratify the regression approach as a useful method for doing mental chronometry. PMID:9347535
A VBA-based Simulation for Teaching Simple Linear Regression
ERIC Educational Resources Information Center
Jones, Gregory Todd; Hagtvedt, Reidar; Jones, Kari
2004-01-01
In spite of the name, simple linear regression presents a number of conceptual difficulties, particularly for introductory students. This article describes a simulation tool that provides a hands-on method for illuminating the relationship between parameters and sample statistics.
Energy and linear and angular momenta in simple electromagnetic systems
NASA Astrophysics Data System (ADS)
Mansuripur, Masud
2015-08-01
We present examples of simple electromagnetic systems in which energy, linear momentum, and angular momentum exhibit interesting behavior. The systems are sufficiently simple to allow exact solutions of Maxwell's equations in conjunction with the electrodynamic laws of force, torque, energy, and momentum. In all the cases examined, conservation of energy and momentum is confirmed.
Central Forehead Reconstruction with a Simple Primary Vertical Linear Closure
Tajirian, Ani; Tsui, Michelle
2016-01-01
Objective: Following Mohs surgery, medium-to-large defects on the central forehead can often be complicated to surgically reconstruct. In this paper, the authors discuss possible central forehead reconstructions and report their successful experience employing a simple primary vertical linear closure with a special technique to demarcate forehead rhytides rather than performing an overly complicated flap or graft. Case report: The patient was a 57-year-old man who presented with a broad superficial basal cell carcinoma that required treatment with Mohs surgery. For the resulting defect, the authors elected to perform a complex linear repair taking advantage of substantial side-to-side laxity in the supraperiosteal plane and carefully labeling and matching each forehead rhytide across the defect as the wound was sutured. Conclusion: The findings of this case demonstrate that medium-to-large wounds of the central forehead can be aesthetically repaired with a simple primary vertical linear closure. Carefully mapping and labeling horizontal forehead rhytides with a sterile surgical marking pen prior to anesthesia ensures accurate approximation during wound closure. PMID:27672419
Identifying approximate linear models for simple nonlinear systems
NASA Technical Reports Server (NTRS)
Horta, L. G.; Juang, J.-N.
1985-01-01
This paper addresses the identification (realization) of approximate linear models from response data for certain nonlinear dynamic systems. Response characteristics for several typical nonlinear joints are analyzed mathematically and represented by series expansions. The parameters of the series expansion are then compared with the modal parameters of a linear model identified by the Eigensystem Realization Algorithm. The agreement of the identified model and the analytically derived representation is excellent for the cases studied. Also laboratory data from a model which exhibited stiffening behavior was analyzed using the Eigensystem Realization algorithm and Fast Fourier Transform. The laboratory experiment demonstrated the ability of the technique to recover the model characteristics using real data.
ERIC Educational Resources Information Center
Nelson, Dean
2009-01-01
Following the Guidelines for Assessment and Instruction in Statistics Education (GAISE) recommendation to use real data, an example is presented in which simple linear regression is used to evaluate the effect of the Montreal Protocol on atmospheric concentration of chlorofluorocarbons. This simple set of data, obtained from a public archive, can…
Micheloyannis, Sifis; Papanikolaou, Elias; Bizas, Emmanuel; Stam, Cornelis J; Simos, Panagiotis G
2002-06-01
This study examined patterns of variation in the ongoing electroencephalogram during performance of three visual tasks. One task required exact arithmetic calculations on Arabic numerals. A second task involved pseudoword processing as a control for the verbal (phonological) component that is, by definition, part of arithmetic tasks. A third task primarily required visual/graphemic processing, which is also involved in the other two tasks. Spectral power in the alpha range was lowest during the pseudoword task, followed by power during the arithmetic task, and finally by power in the visual task, indicating more prominent desynchronization during engagement in the analysis of word-like printed material. Finally, linear (power in the gamma range) and non-linear measures (correlation dimension) provided evidence of predominant right hemisphere engagement during the arithmetic task.
A Simple Reduction Process for the Normal Vibrational Modes Occurring in Linear Molecules
ERIC Educational Resources Information Center
McInerny, William
2005-01-01
The students in molecular spectroscopy courses are often required to determine the permitted normal vibrations for linear molecules that belong to particular groups. The reducible group representations generated by the use of Cartesian coordinates can be reduced by the use of a simple algebraic process applied to the group representations. The…
NASA Astrophysics Data System (ADS)
Chakraborty, Debadi; Sader, John E.
2015-05-01
Simple bulk liquids such as water are commonly assumed to be Newtonian. While this assumption holds widely, the fluid-structure interaction of mechanical devices at nanometer scales can probe the intrinsic molecular relaxation processes in a surrounding liquid. This was recently demonstrated through measurement of the high frequency (20 GHz) linear mechanical vibrations of bipyramidal nanoparticles in simple liquids [Pelton et al., "Viscoelastic flows in simple liquids generated by vibrating nanostructures," Phys. Rev. Lett. 111, 244502 (2013)]. In this article, we review and critically assess the available constitutive equations for compressible viscoelastic flows in their linear limits—such models are required for analysis of the above-mentioned measurements. We show that previous models, with the exception of a very recent proposal, do not reproduce the required response at high frequency. We explain the physical origin of this recent model and show that it recovers all required features of a linear viscoelastic flow. This constitutive equation thus provides a rigorous foundation for the analysis of vibrating nanostructures in simple liquids. The utility of this model is demonstrated by solving the fluid-structure interaction of two common problems: (1) a sphere executing radial oscillations in liquid, which depends strongly on the liquid compressibility and (2) the extensional mode vibration of bipyramidal nanoparticles in liquid, where the effects of liquid compressibility are negligible. This highlights the importance of shear and compressional relaxation processes, as a function of flow geometry, and the impact of the shear and bulk viscosities on nanometer scale flows.
SERF: A Simple, Effective, Robust, and Fast Image Super-Resolver From Cascaded Linear Regression.
Hu, Yanting; Wang, Nannan; Tao, Dacheng; Gao, Xinbo; Li, Xuelong
2016-09-01
Example learning-based image super-resolution techniques estimate a high-resolution image from a low-resolution input image by relying on high- and low-resolution image pairs. An important issue for these techniques is how to model the relationship between high- and low-resolution image patches: most existing complex models either generalize hard to diverse natural images or require a lot of time for model training, while simple models have limited representation capability. In this paper, we propose a simple, effective, robust, and fast (SERF) image super-resolver for image super-resolution. The proposed super-resolver is based on a series of linear least squares functions, namely, cascaded linear regression. It has few parameters to control the model and is thus able to robustly adapt to different image data sets and experimental settings. The linear least square functions lead to closed form solutions and therefore achieve computationally efficient implementations. To effectively decrease these gaps, we group image patches into clusters via k-means algorithm and learn a linear regressor for each cluster at each iteration. The cascaded learning process gradually decreases the gap of high-frequency detail between the estimated high-resolution image patch and the ground truth image patch and simultaneously obtains the linear regression parameters. Experimental results show that the proposed method achieves superior performance with lower time consumption than the state-of-the-art methods.
On Development of a Problem Based Learning System for Linear Algebra with Simple Input Method
NASA Astrophysics Data System (ADS)
Yokota, Hisashi
2011-08-01
Learning how to express a matrix using a keyboard inputs requires a lot of time for most of college students. Therefore, for a problem based learning system for linear algebra to be accessible for college students, it is inevitable to develop a simple method for expressing matrices. Studying the two most widely used input methods for expressing matrices, a simpler input method for expressing matrices is obtained. Furthermore, using this input method and educator's knowledge structure as a concept map, a problem based learning system for linear algebra which is capable of assessing students' knowledge structure and skill is developed.
Mining Distance Based Outliers in Near Linear Time with Randomization and a Simple Pruning Rule
NASA Technical Reports Server (NTRS)
Bay, Stephen D.; Schwabacher, Mark
2003-01-01
Defining outliers by their distance to neighboring examples is a popular approach to finding unusual examples in a data set. Recently, much work has been conducted with the goal of finding fast algorithms for this task. We show that a simple nested loop algorithm that in the worst case is quadratic can give near linear time performance when the data is in random order and a simple pruning rule is used. We test our algorithm on real high-dimensional data sets with millions of examples and show that the near linear scaling holds over several orders of magnitude. Our average case analysis suggests that much of the efficiency is because the time to process non-outliers, which are the majority of examples, does not depend on the size of the data set.
Dubrovsky, V. G.; Topovsky, A. V.
2013-03-15
New exact solutions, nonstationary and stationary, of Veselov-Novikov (VN) equation in the forms of simple nonlinear and linear superpositions of arbitrary number N of exact special solutions u{sup (n)}, n= 1, Horizontal-Ellipsis , N are constructed via Zakharov and Manakov {partial_derivative}-dressing method. Simple nonlinear superpositions are represented up to a constant by the sums of solutions u{sup (n)} and calculated by {partial_derivative}-dressing on nonzero energy level of the first auxiliary linear problem, i.e., 2D stationary Schroedinger equation. It is remarkable that in the zero energy limit simple nonlinear superpositions convert to linear ones in the form of the sums of special solutions u{sup (n)}. It is shown that the sums u=u{sup (k{sub 1})}+...+u{sup (k{sub m})}, 1 Less-Than-Or-Slanted-Equal-To k{sub 1} < k{sub 2} < Horizontal-Ellipsis < k{sub m} Less-Than-Or-Slanted-Equal-To N of arbitrary subsets of these solutions are also exact solutions of VN equation. The presented exact solutions include as superpositions of special line solitons and also superpositions of plane wave type singular periodic solutions. By construction these exact solutions represent also new exact transparent potentials of 2D stationary Schroedinger equation and can serve as model potentials for electrons in planar structures of modern electronics.
Simple Limits on Achieving A Quasi-Linear Magnetic Compression for an FEL Driver
Sun, Yipeng; /SLAC
2012-02-16
Free electron lasers (FEL) need a very bright electron beam in three dimensions and a high peak charge density. In order to compress an initially longer electron bunch generated from the photoinjector, magnetic bunch compression systems are widely employed. In this paper, first harmonic RF linearization and its associated requirements are reviewed. Meanwhile it is also briefly discussed what is the relation between a proper initial bunch length and main RF frequency, when a harmonic RF linearization is included. Then given a reasonable bunch compression ratio, a proper initial bunch length as a function of the main RF frequency and RF phase is estimated analytically by several approaches, assuming that no harmonic RF section is needed to linearize the energy modulation introduced during main RF acceleration, and at the same time still linearly compress the bunch length. Next the upper limit of the bunch compression ratio in a single stage is evaluated analytically. The analytical relations derived on choosing a proper initial bunch length as a function of main RF frequency are confirmed by numerical simulation. These simple limit provide rough estimations and may be beneficial for choosing bunch compression ratios in different stages of an FEL driver, especially in a first stage bunch compression where there is usually a harmonic RF linearization applied. It may also be useful in evaluating the possibility of low charge operation mode without any harmonic RF linearization, where a shorter initial bunch length can be achieved from the photoinjector.
Chan, Roger W; Rodriguez, Maritza L
2008-08-01
Previous studies reporting the linear viscoelastic shear properties of the human vocal fold cover or mucosa have been based on torsional rheometry, with measurements limited to low audio frequencies, up to around 80 Hz. This paper describes the design and validation of a custom-built, controlled-strain, linear, simple-shear rheometer system capable of direct empirical measurements of viscoelastic shear properties at phonatory frequencies. A tissue specimen was subjected to simple shear between two parallel, rigid acrylic plates, with a linear motor creating a translational sinusoidal displacement of the specimen via the upper plate, and the lower plate transmitting the harmonic shear force resulting from the viscoelastic response of the specimen. The displacement of the specimen was measured by a linear variable differential transformer whereas the shear force was detected by a piezoelectric transducer. The frequency response characteristics of these system components were assessed by vibration experiments with accelerometers. Measurements of the viscoelastic shear moduli (G' and G") of a standard ANSI S2.21 polyurethane material and those of human vocal fold cover specimens were made, along with estimation of the system signal and noise levels. Preliminary results showed that the rheometer can provide valid and reliable rheometric data of vocal fold lamina propria specimens at frequencies of up to around 250 Hz, well into the phonatory range. PMID:18681608
Chan, Roger W.; Rodriguez, Maritza L.
2008-01-01
Previous studies reporting the linear viscoelastic shear properties of the human vocal fold cover or mucosa have been based on torsional rheometry, with measurements limited to low audio frequencies, up to around 80 Hz. This paper describes the design and validation of a custom-built, controlled-strain, linear, simple-shear rheometer system capable of direct empirical measurements of viscoelastic shear properties at phonatory frequencies. A tissue specimen was subjected to simple shear between two parallel, rigid acrylic plates, with a linear motor creating a translational sinusoidal displacement of the specimen via the upper plate, and the lower plate transmitting the harmonic shear force resulting from the viscoelastic response of the specimen. The displacement of the specimen was measured by a linear variable differential transformer whereas the shear force was detected by a piezoelectric transducer. The frequency response characteristics of these system components were assessed by vibration experiments with accelerometers. Measurements of the viscoelastic shear moduli (G′ and G″) of a standard ANSI S2.21 polyurethane material and those of human vocal fold cover specimens were made, along with estimation of the system signal and noise levels. Preliminary results showed that the rheometer can provide valid and reliable rheometric data of vocal fold lamina propria specimens at frequencies of up to around 250 Hz, well into the phonatory range. PMID:18681608
A simple frequency sweep linearization method for FM density profile reflectometry
NASA Astrophysics Data System (ADS)
Liu, Adi; Hu, Jianqiang; Doyle, Edward; Zhang, Jin; Li, Hong; Zhou, Chu; Zhang, Xiaohui; Wang, Mingyuan; Lan, Tao; Xie, Jinglin; Liu, Wandong; Yu, Changxuan
2015-11-01
Frequency modulated, continuous wave (FMCW) reflectometry is widely used to measure the electron density profile on fusion devices. To ensure the output intermediate frequency signal is proportional to the propagation delay time, the frequency sweep should be linearized, especially for reflectometry with sweeping periods of only a few microseconds. We introduce a simple dynamic calibration technique to linearize the frequency sweep based on digital complex demodulation methods, without using a Fourier transform, which would induce a trade-off between frequency and time resolution. The technique is convenient as it can be done in the same conditions as for plasma measurements. The method is in use on the EAST profile reflectometer, and results will be presented. Work was supported by the Natural Science Foundation of China (NSFC) under 11475173, National Magnetic Confinement Fusion Energy Development Program of China under 2013GB106002 and 2014GB109002, and US DOE Grants DE- SC0010424 and DE-SC0010469.
A simple explanation of the linear rms-mean flux relation in accreting objects
NASA Astrophysics Data System (ADS)
Koen, C.
2016-09-01
Aims: We provide an alternative to existing theories for the origin of linear rms-mean flux relations observed in a variety of accreting systems, from AGN to white dwarfs. Methods: Standard statistical theory and simulations are used to explore the possibility that the relations are due to simple scaling effects. Results: The proposed theory can reproduce the unit slope of the rms-mean flux relation observed in the most extensive study published to date. The close similarity of the fractional variability in different objects deserves further study.
Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides
Schaub, S. C.; Shapiro, M. A.; Temkin, R. J.
2016-01-01
Simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a1 < a2, the optimal length of the taper is 3.198a1a2/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE11 mode in an optimized taper is 0.0293(a2−a1)4∕a12a22. These formulae are accurate when a2 ≲ 2a1. Slightly more complex formulae, accurate for a2 ≤ 4a1, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a2 ≤ 2.12a1 and less than 0.1 % when a2 ≤ 1.53a1. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Parabolic tapers may provide lower loss, but linear tapers with moderate values of a2/a1 may be attractive because of their simplicity of fabrication. PMID:27053963
A simple method for wind tunnel balance calibration including non-linear interaction terms
NASA Astrophysics Data System (ADS)
Ramaswamy, M. A.; Srinivas, T.; Holla, V. S.
The conventional method for calibrating wind tunnel balances to obtain the coupled linear and nonlinear interaction terms requires the application of combinations of pure components of the loads on the calibration body compensating the deflection of the balance. For a six-component balance, this calls for a complex loading system and an arrangement to translate and tilt the balance support about all three axes. A simple method called the least-square method is illustrated for a three-component balance. The simplicity arises from the fact that application of the pure components of the loads or reorientation of the balance is not required. A single load is applied that has various components whose magnitudes can be easily found knowing the orientation of the calibration body under load and the point of application of the load. The coefficients are obtained by using the least-square-fit approach to match the outputs obtained for various combinations of load.
Chicken barn climate and hazardous volatile compounds control using simple linear regression and PID
NASA Astrophysics Data System (ADS)
Abdullah, A. H.; Bakar, M. A. A.; Shukor, S. A. A.; Saad, F. S. A.; Kamis, M. S.; Mustafa, M. H.; Khalid, N. S.
2016-07-01
The hazardous volatile compounds from chicken manure in chicken barn are potentially to be a health threat to the farm animals and workers. Ammonia (NH3) and hydrogen sulphide (H2S) produced in chicken barn are influenced by climate changes. The Electronic Nose (e-nose) is used for the barn's air, temperature and humidity data sampling. Simple Linear Regression is used to identify the correlation between temperature-humidity, humidity-ammonia and ammonia-hydrogen sulphide. MATLAB Simulink software was used for the sample data analysis using PID controller. Results shows that the performance of PID controller using the Ziegler-Nichols technique can improve the system controller to control climate in chicken barn.
Auger-Méthé, Marie; Field, Chris; Albertsen, Christoffer M; Derocher, Andrew E; Lewis, Mark A; Jonsen, Ian D; Mills Flemming, Joanna
2016-01-01
State-space models (SSMs) are increasingly used in ecology to model time-series such as animal movement paths and population dynamics. This type of hierarchical model is often structured to account for two levels of variability: biological stochasticity and measurement error. SSMs are flexible. They can model linear and nonlinear processes using a variety of statistical distributions. Recent ecological SSMs are often complex, with a large number of parameters to estimate. Through a simulation study, we show that even simple linear Gaussian SSMs can suffer from parameter- and state-estimation problems. We demonstrate that these problems occur primarily when measurement error is larger than biological stochasticity, the condition that often drives ecologists to use SSMs. Using an animal movement example, we show how these estimation problems can affect ecological inference. Biased parameter estimates of a SSM describing the movement of polar bears (Ursus maritimus) result in overestimating their energy expenditure. We suggest potential solutions, but show that it often remains difficult to estimate parameters. While SSMs are powerful tools, they can give misleading results and we urge ecologists to assess whether the parameters can be estimated accurately before drawing ecological conclusions from their results. PMID:27220686
Auger-Méthé, Marie; Field, Chris; Albertsen, Christoffer M; Derocher, Andrew E; Lewis, Mark A; Jonsen, Ian D; Mills Flemming, Joanna
2016-05-25
State-space models (SSMs) are increasingly used in ecology to model time-series such as animal movement paths and population dynamics. This type of hierarchical model is often structured to account for two levels of variability: biological stochasticity and measurement error. SSMs are flexible. They can model linear and nonlinear processes using a variety of statistical distributions. Recent ecological SSMs are often complex, with a large number of parameters to estimate. Through a simulation study, we show that even simple linear Gaussian SSMs can suffer from parameter- and state-estimation problems. We demonstrate that these problems occur primarily when measurement error is larger than biological stochasticity, the condition that often drives ecologists to use SSMs. Using an animal movement example, we show how these estimation problems can affect ecological inference. Biased parameter estimates of a SSM describing the movement of polar bears (Ursus maritimus) result in overestimating their energy expenditure. We suggest potential solutions, but show that it often remains difficult to estimate parameters. While SSMs are powerful tools, they can give misleading results and we urge ecologists to assess whether the parameters can be estimated accurately before drawing ecological conclusions from their results.
Auger-Méthé, Marie; Field, Chris; Albertsen, Christoffer M.; Derocher, Andrew E.; Lewis, Mark A.; Jonsen, Ian D.; Mills Flemming, Joanna
2016-01-01
State-space models (SSMs) are increasingly used in ecology to model time-series such as animal movement paths and population dynamics. This type of hierarchical model is often structured to account for two levels of variability: biological stochasticity and measurement error. SSMs are flexible. They can model linear and nonlinear processes using a variety of statistical distributions. Recent ecological SSMs are often complex, with a large number of parameters to estimate. Through a simulation study, we show that even simple linear Gaussian SSMs can suffer from parameter- and state-estimation problems. We demonstrate that these problems occur primarily when measurement error is larger than biological stochasticity, the condition that often drives ecologists to use SSMs. Using an animal movement example, we show how these estimation problems can affect ecological inference. Biased parameter estimates of a SSM describing the movement of polar bears (Ursus maritimus) result in overestimating their energy expenditure. We suggest potential solutions, but show that it often remains difficult to estimate parameters. While SSMs are powerful tools, they can give misleading results and we urge ecologists to assess whether the parameters can be estimated accurately before drawing ecological conclusions from their results. PMID:27220686
A simple advection-dispersion model for the salt distribution in linearly tapered estuaries
NASA Astrophysics Data System (ADS)
Gay, Peter S.; O'Donnell, James
2007-07-01
We present a simple advection-dispersion model for the subtidal salt distribution in estuaries with linearly varying cross-sectional area and a nonzero net salt flux. A novel analytic solution allows investigation of the dependence of the curvature and gradient of the longitudinal salinity distribution on runoff, dispersion coefficient, and channel contraction or expansion. The model predicts that in estuarine segments that contract toward the fresher boundary, the salinity gradient is stronger than in a prismatic channel. When the dispersion coefficient is large compared to the salinity intrusion lengthscale, ? (the product of segment length and net volume flux divided by cross-sectional area at the ocean boundary), the curvature of the salt concentration may be negative, a characteristic not possible in uniform channel models. The main effect of up-estuary salt flux is to strengthen the salinity gradient. The model can be extended to multiple segments in order to simulate geometrically complicated estuaries. The model is employed to estimate an effective dispersion coefficient and to describe the salinity variation in the western 53 km of Long Island Sound where the cross section of the basin varies linearly. Using 8 years of monthly observations at seven stations we find that, since the curvature of the vertically averaged salinity is negative, the model and data are consistent only if the net volume flux and salt flux are toward the fresher boundary, the East River. Combining prior estimates of the magnitudes of the fluxes and their uncertainties with the model and salinity observations using a least squares approach, we estimate the dispersion coefficient for the Western Sound as 580 m2/s.
Non-linearities in cortical simple cells and the possible detection of zero crossings.
Richter, J; Ullman, S
1986-01-01
A theory of early visual information processing proposed by Marr and co-workers suggests that simple cortical cells may be involved in the detection of zero crossing in the retinal output. We have tested this theory by using pairs of adjacent edges (staircases stimuli) and recording from edge-specific simple cells in cat striate cortex. The zero crossing hypothesis gives rise for such stimuli to non-obvious predictions that were generally confirmed by the experiment.
A Simple and Convenient Method of Multiple Linear Regression to Calculate Iodine Molecular Constants
ERIC Educational Resources Information Center
Cooper, Paul D.
2010-01-01
A new procedure using a student-friendly least-squares multiple linear-regression technique utilizing a function within Microsoft Excel is described that enables students to calculate molecular constants from the vibronic spectrum of iodine. This method is advantageous pedagogically as it calculates molecular constants for ground and excited…
ERIC Educational Resources Information Center
Miskel, Cecil
The hypothesis guiding the study was that work motivation attitudes, behavior, and perceptions of others--as leader style concepts--and school climate--as a situational construct--are linearly and curvilinearly related to subordinate, superordinate, self, and organizational effectiveness criteria. A total of 179 principals, 996 teachers, and 41…
Erickson, S.A. Jr.
1988-01-02
A new formulation for the amplitude and pulse shape from reflections from a linear segment for a bistatic planar geometry is presented. The formulation is useful in calculating reverberation from high intensity signals in an deep ocean basin where long range propagation can occur. This reverberation is important in calculating the acoustic interference to sonar arising from the detonation of nuclear or large chemical explosives, and for modeling long range active sonar. The reflections computed with the new formulation are significantly different from those of earlier versions of the reverberation model, with pulses generally shorter and more intense, leading to predictions of louder but more sporadic reverberation than previously estimated. 9 refs
Hassan, A. K.
2015-01-01
In this work, O/W emulsion sets were prepared by using different concentrations of two nonionic surfactants. The two surfactants, tween 80(HLB=15.0) and span 80(HLB=4.3) were used in a fixed proportions equal to 0.55:0.45 respectively. HLB value of the surfactants blends were fixed at 10.185. The surfactants blend concentration is starting from 3% up to 19%. For each O/W emulsion set the conductivity was measured at room temperature (25±2°), 40, 50, 60, 70 and 80°. Applying the simple linear regression least squares method statistical analysis to the temperature-conductivity obtained data determines the effective surfactants blend concentration required for preparing the most stable O/W emulsion. These results were confirmed by applying the physical stability centrifugation testing and the phase inversion temperature range measurements. The results indicated that, the relation which represents the most stable O/W emulsion has the strongest direct linear relationship between temperature and conductivity. This relationship is linear up to 80°. This work proves that, the most stable O/W emulsion is determined via the determination of the maximum R² value by applying of the simple linear regression least squares method to the temperature–conductivity obtained data up to 80°, in addition to, the true maximum slope is represented by the equation which has the maximum R² value. Because the conditions would be changed in a more complex formulation, the method of the determination of the effective surfactants blend concentration was verified by applying it for more complex formulations of 2% O/W miconazole nitrate cream and the results indicate its reproducibility. PMID:26664063
Hassan, A K
2015-01-01
In this work, O/W emulsion sets were prepared by using different concentrations of two nonionic surfactants. The two surfactants, tween 80(HLB=15.0) and span 80(HLB=4.3) were used in a fixed proportions equal to 0.55:0.45 respectively. HLB value of the surfactants blends were fixed at 10.185. The surfactants blend concentration is starting from 3% up to 19%. For each O/W emulsion set the conductivity was measured at room temperature (25±2°), 40, 50, 60, 70 and 80°. Applying the simple linear regression least squares method statistical analysis to the temperature-conductivity obtained data determines the effective surfactants blend concentration required for preparing the most stable O/W emulsion. These results were confirmed by applying the physical stability centrifugation testing and the phase inversion temperature range measurements. The results indicated that, the relation which represents the most stable O/W emulsion has the strongest direct linear relationship between temperature and conductivity. This relationship is linear up to 80°. This work proves that, the most stable O/W emulsion is determined via the determination of the maximum R² value by applying of the simple linear regression least squares method to the temperature-conductivity obtained data up to 80°, in addition to, the true maximum slope is represented by the equation which has the maximum R² value. Because the conditions would be changed in a more complex formulation, the method of the determination of the effective surfactants blend concentration was verified by applying it for more complex formulations of 2% O/W miconazole nitrate cream and the results indicate its reproducibility. PMID:26664063
Qibo, Feng; Bin, Zhang; Cunxing, Cui; Cuifang, Kuang; Yusheng, Zhai; Fenglin, You
2013-11-01
A simple method for simultaneously measuring the 6DOF geometric motion errors of the linear guide was proposed. The mechanisms for measuring straightness and angular errors and for enhancing their resolution are described in detail. A common-path method for measuring the laser beam drift was proposed and it was used to compensate the errors produced by the laser beam drift in the 6DOF geometric error measurements. A compact 6DOF system was built. Calibration experiments with certain standard measurement meters showed that our system has a standard deviation of 0.5 µm in a range of ± 100 µm for the straightness measurements, and standard deviations of 0.5", 0.5", and 1.0" in the range of ± 100" for pitch, yaw, and roll measurements, respectively.
Clancy, R.L.; Thompson, C.J.; Robar, J.L.; Bergman, A.M.
1996-12-31
Crossed anode wire position sensitive photomultiplier tubes (PS-PMTs) detect the location of a light source and provide the X and Y axis coordinates of the event. These coordinates are typically generated using Anger logic, where a resistor chain divides the current flow into two signals for each coordinate (X{sup +}, X{sup -} & Y{sup +}, Y{sup -}). In the standard readout, identical resistor values are used across the entire resistor chain. While this arrangement provides a linear readout in the central portion of the photomultiplier face, the readout is non-linear and sometimes even double valued near the edges of the PS-PMT due to the truncation of the charge beyond the last anode wire. To counter this effect, we have increased the value of the resistance near the ends of each resistor chain in order to compensate for the charge lost beyond the anode wires. Measurements were made using a Hamamatsu R-3941 PS-PMT coupled to a pixellated BGO matrix of cut crystals with a 2mm pitch in each direction. After changing the end resistors, the usable field-of-view increased by 39%. This simple modification should enhance the operation of PS-PMTs in applications such as positron emission mammography, and small animal PET imaging.
Hack, Christopher A.; Benner, W. Henry
2001-10-31
A simple mathematical technique for improving mass calibration accuracy of linear delayed extraction matrix assisted laser desorption ionization time-of-flight mass spectrometry (DE MALDI-TOF MS) spectra is presented. The method involves fitting a parabola to a plot of Dm vs. mass data where Dm is the difference between the theoretical mass of calibrants and the mass obtained from a linear relationship between the square root of m/z and ion time of flight. The quadratic equation that describes the parabola is then used to correct the mass of unknowns by subtracting the deviation predicted by the quadratic equation from measured data. By subtracting the value of the parabola at each mass from the calibrated data, the accuracy of mass data points can be improved by factors of 10 or more. This method produces highly similar results whether or not initial ion velocity is accounted for in the calibration equation; consequently, there is no need to depend on that uncertain parameter when using the quadratic correction. This method can be used to correct the internally calibrated masses of protein digest peaks. The effect of nitrocellulose as a matrix additive is also briefly discussed, and it is shown that using nitrocellulose as an additive to a CHCA matrix does not significantly change initial ion velocity but does change the average position of ions relative to the sample electrode at the instant the extraction voltage is applied.
NASA Astrophysics Data System (ADS)
Asfahani, J.; Tlas, M.
2015-10-01
An easy and practical method for interpreting residual gravity anomalies due to simple geometrically shaped models such as cylinders and spheres has been proposed in this paper. This proposed method is based on both the deconvolution technique and the simplex algorithm for linear optimization to most effectively estimate the model parameters, e.g., the depth from the surface to the center of a buried structure (sphere or horizontal cylinder) or the depth from the surface to the top of a buried object (vertical cylinder), and the amplitude coefficient from the residual gravity anomaly profile. The method was tested on synthetic data sets corrupted by different white Gaussian random noise levels to demonstrate the capability and reliability of the method. The results acquired show that the estimated parameter values derived by this proposed method are close to the assumed true parameter values. The validity of this method is also demonstrated using real field residual gravity anomalies from Cuba and Sweden. Comparable and acceptable agreement is shown between the results derived by this method and those derived from real field data.
ERIC Educational Resources Information Center
Unsal, Yasin
2011-01-01
One of the subjects that is confusing and difficult for students to fully comprehend is the concept of angular velocity and linear velocity. It is the relationship between linear and angular velocity that students find difficult; most students understand linear motion in isolation. In this article, we detail the design, construction and…
Vidal, Sébastien; Luce, Jacques; Hocquet, Steve; Gouédard, Claude; Calvet, Pierre; Penninckx, Denis
2012-08-20
It is known that a linear filter may be easily compensated with its inverse transfer function. However, it was shown that this approach could also be valid even for such a complex nonlinear system as frequency conversion. As a matter of fact, it is possible to at least partly precompensate for distortions occurring within, or even downstream from, frequency conversion crystals with a simple linear optical filter set upstream. In this paper, we give the theoretical background and derive the optimum precompensation filter from simple analytical formulas even in the case of saturation. We first show the relevance of our approach for Gaussian pulses: the pulse may be short or not and chirped or not, and the same linear precompensation filter may be used as long as saturation is not reached. We then study the case of phase-modulated pulses, as can be found on high power lasers such as lasers for fusion. We show that previous experimental results are in perfect agreement with these calculations. Finally, justified by our simple analytical formulas, we present a rigorous parametrical study giving the distortion reduction for any second and third harmonic generation system in the case of phase-modulated pulses. PMID:22907009
NASA Technical Reports Server (NTRS)
Ng, C. F.
1988-01-01
Static postbuckling and nonlinear dynamic analysis of plates are usually accomplished by multimode analyses, although the methods are complicated and do not give straightforward understanding of the nonlinear behavior. Assuming single-mode transverse displacement, a simple formula is derived for the transverse load displacement relationship of a plate under in-plane compression. The formula is used to derive a simple analytical expression for the static postbuckling displacement and nonlinear dynamic responses of postbuckled plates under sinusoidal or random excitation. Regions with softening and hardening spring behavior are identified. Also, the highly nonlinear motion of snap-through and its effects on the overall dynamic response can be easily interpreted using the single-mode formula. Theoretical results are compared with experimental results obtained using a buckled aluminum panel, using discrete frequency and broadband point excitation. Some important effects of the snap-through motion on the dynamic response of the postbuckled plates are found.
Ramshaw, J D
2000-10-01
A simple model was recently described for predicting the time evolution of the width of the mixing layer at an unstable fluid interface [J. D. Ramshaw, Phys. Rev. E 58, 5834 (1998); ibid. 61, 5339 (2000)]. The ordinary differential equations of this model have been heuristically generalized into partial differential equations suitable for implementation in multicomponent hydrodynamics codes. The central ingredient in this generalization is a nun-diffusional expression for the species mass fluxes. These fluxes describe the relative motion of the species, and thereby determine the local mixing rate and spatial distribution of mixed fluid as a function of time. The generalized model has been implemented in a two-dimensional hydrodynamics code. The model equations and implementation procedure are summarized, and comparisons with experimental mixing data are presented.
NASA Technical Reports Server (NTRS)
Carlson, Harry W.
1985-01-01
The purpose here is to show how two linearized theory computer programs in combination may be used for the design of low speed wing flap systems capable of high levels of aerodynamic efficiency. A fundamental premise of the study is that high levels of aerodynamic performance for flap systems can be achieved only if the flow about the wing remains predominantly attached. Based on this premise, a wing design program is used to provide idealized attached flow camber surfaces from which candidate flap systems may be derived, and, in a following step, a wing evaluation program is used to provide estimates of the aerodynamic performance of the candidate systems. Design strategies and techniques that may be employed are illustrated through a series of examples. Applicability of the numerical methods to the analysis of a representative flap system (although not a system designed by the process described here) is demonstrated in a comparison with experimental data.
NASA Astrophysics Data System (ADS)
Pesheva, N. C.; Brankov, J. G.
2013-06-01
We report here results on the study of the totally asymmetric simple exclusion process, defined on an open network, consisting of head and tail simple-chain segments with a double-chain section inserted in between. Results of numerical simulations for relatively short chains reveal an interesting feature of the network. When the current through the system takes its maximum value, a simple translation of the double-chain section forward or backward along the network leads to a sharp change in the shape of the density profiles in the parallel chains, thus affecting the total number of particles in that part of the network. In the symmetric case of equal injection and ejection rates α=β>1/2 and equal lengths of the head and tail sections, the density profiles in the two parallel chains are almost linear, characteristic of the coexistence line (shock phase). Upon moving the section forward (backward), their shape changes to the one typical for the high- (low-) density phases of a simple chain. The total bulk density of particles in a section with a large number of parallel chains is evaluated too. The observed effect might have interesting implications for the traffic flow control as well as for biological transport processes in living cells. An explanation of this phenomenon is offered in terms of a finite-size dependence of the effective injection and ejection rates at the ends of the double-chain section.
Moore, Shaun; Stanley, Fintan K T; Goodarzi, Aaron A
2014-05-01
High linear energy transfer (LET) ionising radiation (IR) such as radon-derived alpha particles and high mass, high energy (HZE) particles of cosmic radiation are the predominant forms of IR to which humanity is exposed throughout life. High-LET forms of IR are established carcinogens relevant to human cancer, and their potent mutagenicity is believed, in part, to be due to a greater incidence of clustered DNA double strand breaks (DSBs) and associated lesions, as ionization events occur within a more confined genomic space. The repair of such DNA damage is now well-documented to occur with slower kinetics relative to that induced by low-LET IR, and to be more reliant upon homology-directed repair pathways. Underlying these phenomena is the relative inability of non-homologous end-joining (NHEJ) to adequately resolve high-LET IR-induced DSBs. Current findings suggest that the functionality of the DNA-dependent protein kinase (DNA-PK), comprised of the Ku70-Ku80 heterodimer and the DNA-PK catalytic subunit (DNA-PKcs), is particularly perturbed by high-LET IR-induced clustered DSBs, rendering DNA-PK dependent NHEJ less relevant to resolving these lesions. By contrast, the NHEJ-associated DNA processing endonuclease Artemis shows a greater relevance to high-LET IR-induced DSB repair. Here, we will review the cellular response to high-LET irradiation, the implications of the chronic, low-dose modality of this exposure and molecular pathways that respond to high-LET irradiation induced DSBs, with particular emphasis on NHEJ factors. PMID:24565812
NASA Astrophysics Data System (ADS)
Aubeneau, A. F.; Thompson, S. E.; Hassan, M. A.; Packman, A. I.
2009-12-01
Erosion and sediment transport are influenced by hydrological regime (rainfall-runoff), catchment properties (vegetation, topography, soil properties), management practices (land use), and their interactions. Here, we use a simple linear catchment response model to describe sediment transport in the Goodwin Creek catchment. The model includes two linear stores, one for the hillslope and one for the fluvial network. The hillslope store is supplied with sediments from upland erosion, with event-driven mobilization occurring over the effective duration of each storm. Some of the mobilized sediments are redeposited on the hillslope and the remainder is transferred to the river network. Additional sediment supply to the network occurs from the channel via bank erosion. Suspended sediment transport and deposition are considered along river channels in order to determine the timing and magnitude of sediment efflux from the catchment. In environments dominated by hillslope erosion, sediment delivery ratio (the ratio between upland erosion and sediment yield at the outlet) is expected to be closely related to catchment hydrological response. However, fluvial storage obscures this relationship by modulating the morphodynamic response to primary hydrological and geomorphological drivers. We used the model to distinguish the relative influence of climate forcing, hydrological response and land use practices on sediment transport and delivery in the Goodwin Creek catchment, where sediment and channel dynamics have been monitored in fourteen sub-catchments for over twenty years. These sub-catchments include a range of channel sizes and a diversity of management practices over the length of the data record. Our results suggest that hillslope processes dominate the delivery ratio in smaller catchments but that channel processes become more important at larger spatial scales. Furthermore, although climate variability could explain a large proportion of the variability in sediment
Hack, Christopher A; Benner, W Henry
2002-01-01
A simple mathematical technique for improving mass calibration accuracy of linear delayed extraction matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (DE MALDI-TOFMS) spectra is presented. The method involves fitting a parabola to a plot of Delta(m) vs. mass data where Delta(m) is the difference between the theoretical mass of calibrants and the mass obtained from a linear relationship between the square root of m/z and ion time of flight. The quadratic equation that describes the parabola is then used to correct the mass of unknowns by subtracting the deviation predicted by the quadratic equation from measured data. By subtracting the value of the parabola at each mass from the calibrated data, the accuracy of mass data points can be improved by factors of 10 or more. This method produces highly similar results whether or not initial ion velocity is accounted for in the calibration equation; consequently, there is no need to depend on that uncertain parameter when using the quadratic correction. This method can be used to correct the internally calibrated masses of protein digest peaks. The effect of nitrocellulose as a matrix additive is also briefly discussed, and it is shown that using nitrocellulose as an additive to the alpha-cyano-4-hydroxycinnamic acid (alphaCHCA) matrix does not significantly change initial ion velocity but does change the average position of ions relative to the sample electrode at the instant the extraction voltage is applied.
Yang, Aifu; Su, Qiao; An, Lijia
2009-03-01
The presence of selectable marker genes and vector backbone sequences has affected the safe assessment of transgenic plants. In this study, the ovary-drip method for directly generating vector- and selectable marker-free transgenic plants was described, by which maize was transformed with a linear GFP cassette (Ubi-GFP-nos). The key features of this method center on the complete removal of the styles and the subsequent application of a DNA solution directly to the ovaries. The movement of the exogenous DNA was monitored using fluorescein isothiocyanate-labeled DNA, which showed that the time taken by the exogenous DNA to enter the ovaries was shortened compared to that of the pollen-tube pathway. This led to an improved transformation frequency of 3.38% compared to 0.86% for the pollen-tube pathway as determined by PCR analysis. The use of 0.05% surfactant Silwet L-77 + 5% sucrose as a transformation solution further increased the transformation frequency to 6.47%. Southern blot analysis showed that the transgenic plants had low transgene copy number and simple integration pattern. Green fluorescence was observed in roots and immature embryos of transgenic plants by fluorescence microscopy. Progeny analysis showed that GFP insertions were inherited in T(1) generation. The ovary-drip method would become a favorable choice for directly generating vector- and marker-free transgenic maize expressing functional genes of agronomic interest.
Self-mode-locked 2 μm Tm(3+)-doped double-clad fiber laser with a simple linear cavity.
Liu, Chun; Luo, Zhengqian; Huang, Yizhong; Qu, Biao; Cheng, Huihui; Wang, Ying; Wu, Duanduan; Xu, Huiying; Cai, Zhiping
2014-02-10
We demonstrate the self-mode-locking operation of a thulium (Tm)-doped fiber laser (TDFL) with a simple linear cavity. Since the laser cavity does not include any specific mode-locker, we experimentally investigate and analyze the self-mode-locking mechanism. The mode-locking operation is attributed to the combination of the self-phase modulation effect and the weak saturable absorption of the high-concentration Tm-doped fiber. The mode-locked TDFL operates at a central wavelength of 1985.5 nm with the 3 dB spectral linewidth of 0.18 nm. The self-mode-locking generates a large pulse energy of 32.7 nJ with a pulsed repetition rate of 2.05 MHz and is stable with a radio-frequency signal-to-noise ratio of more than 54 dB. To the best of our knowledge, it is the first demonstration of a 2 μm Tm-doped fiber laser mode-locked by such technique.
Gurdal, R.J.; Maxham, W.D.
1996-12-01
Typically, structures with significant non-linear supports are analyzed using either time-history algorithms or response spectrum enveloping techniques, with multiple stiffness values to represent the non-linear supports. However, there are problems associated with these methods: (1) time-history analyses require considerable computer time, and, more importantly, the generated response files can become too large; (2) linear response spectrum analyses, when used to envelop the non-linear solution, are excessively conservative. This paper presents an equivalent linear response spectrum methodology to analyze structural systems with a uni-directional support. The structure is free to move in one direction, and restricted with a support stiffness in the diametrically opposed direction. The mathematical formulas for this application are developed and presented. The results using this methodology are compared with actual results from corresponding time-history non-linear structural analyses. These comparisons, performed for the one-mass structural system, show that the equivalent linear response spectrum method closely approximates the time-history results.
ERIC Educational Resources Information Center
St. Andre, Ralph E.
Simple machines have become a lost point of study in elementary schools as teachers continue to have more material to cover. This manual provides hands-on, cooperative learning activities for grades three through eight concerning the six simple machines: wheel and axle, inclined plane, screw, pulley, wedge, and lever. Most activities can be…
Prostatectomy - simple; Suprapubic prostatectomy; Retropubic simple prostatectomy; Open prostatectomy; Millen procedure ... prostate and what caused your prostate to grow. Open simple prostatectomy is often used when the prostate ...
Sidorin, Anatoly
2010-01-05
In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.
Resistors Improve Ramp Linearity
NASA Technical Reports Server (NTRS)
Kleinberg, L. L.
1982-01-01
Simple modification to bootstrap ramp generator gives more linear output over longer sweep times. New circuit adds just two resistors, one of which is adjustable. Modification cancels nonlinearities due to variations in load on charging capacitor and due to changes in charging current as the voltage across capacitor increases.
NASA Astrophysics Data System (ADS)
Yamamoto, Akira; Yokoya, Kaoru
2015-02-01
An overview of linear collider programs is given. The history and technical challenges are described and the pioneering electron-positron linear collider, the SLC, is first introduced. For future energy frontier linear collider projects, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC) are introduced and their technical features are discussed. The ILC is based on superconducting RF technology and the CLIC is based on two-beam acceleration technology. The ILC collaboration completed the Technical Design Report in 2013, and has come to the stage of "Design to Reality." The CLIC collaboration published the Conceptual Design Report in 2012, and the key technology demonstration is in progress. The prospects for further advanced acceleration technology are briefly discussed for possible long-term future linear colliders.
NASA Astrophysics Data System (ADS)
Yamamoto, Akira; Yokoya, Kaoru
An overview of linear collider programs is given. The history and technical challenges are described and the pioneering electron-positron linear collider, the SLC, is first introduced. For future energy frontier linear collider projects, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC) are introduced and their technical features are discussed. The ILC is based on superconducting RF technology and the CLIC is based on two-beam acceleration technology. The ILC collaboration completed the Technical Design Report in 2013, and has come to the stage of "Design to Reality." The CLIC collaboration published the Conceptual Design Report in 2012, and the key technology demonstration is in progress. The prospects for further advanced acceleration technology are briefly discussed for possible long-term future linear colliders.
ERIC Educational Resources Information Center
Walkiewicz, T. A.; Newby, N. D., Jr.
1972-01-01
A discussion of linear collisions between two or three objects is related to a junior-level course in analytical mechanics. The theoretical discussion uses a geometrical approach that treats elastic and inelastic collisions from a unified point of view. Experiments with a linear air track are described. (Author/TS)
Pinski, Peter; Riplinger, Christoph; Neese, Frank E-mail: frank.neese@cec.mpg.de; Valeev, Edward F. E-mail: frank.neese@cec.mpg.de
2015-07-21
In this work, a systematic infrastructure is described that formalizes concepts implicit in previous work and greatly simplifies computer implementation of reduced-scaling electronic structure methods. The key concept is sparse representation of tensors using chains of sparse maps between two index sets. Sparse map representation can be viewed as a generalization of compressed sparse row, a common representation of a sparse matrix, to tensor data. By combining few elementary operations on sparse maps (inversion, chaining, intersection, etc.), complex algorithms can be developed, illustrated here by a linear-scaling transformation of three-center Coulomb integrals based on our compact code library that implements sparse maps and operations on them. The sparsity of the three-center integrals arises from spatial locality of the basis functions and domain density fitting approximation. A novel feature of our approach is the use of differential overlap integrals computed in linear-scaling fashion for screening products of basis functions. Finally, a robust linear scaling domain based local pair natural orbital second-order Möller-Plesset (DLPNO-MP2) method is described based on the sparse map infrastructure that only depends on a minimal number of cutoff parameters that can be systematically tightened to approach 100% of the canonical MP2 correlation energy. With default truncation thresholds, DLPNO-MP2 recovers more than 99.9% of the canonical resolution of the identity MP2 (RI-MP2) energy while still showing a very early crossover with respect to the computational effort. Based on extensive benchmark calculations, relative energies are reproduced with an error of typically <0.2 kcal/mol. The efficiency of the local MP2 (LMP2) method can be drastically improved by carrying out the LMP2 iterations in a basis of pair natural orbitals. While the present work focuses on local electron correlation, it is of much broader applicability to computation with sparse tensors in
Christofilos, N.C.; Polk, I.J.
1959-02-17
Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.
Designing linear systolic arrays
Kumar, V.K.P.; Tsai, Y.C. . Dept. of Electrical Engineering)
1989-12-01
The authors develop a simple mapping technique to design linear systolic arrays. The basic idea of the technique is to map the computations of a certain class of two-dimensional systolic arrays onto one-dimensional arrays. Using this technique, systolic algorithms are derived for problems such as matrix multiplication and transitive closure on linearly connected arrays of PEs with constant I/O bandwidth. Compared to known designs in the literature, the technique leads to modular systolic arrays with constant hardware in each PE, few control lines, lexicographic data input/output, and improved delay time. The unidirectional flow of control and data in this design assures implementation of the linear array in the known fault models of wafer scale integration.
Generalized Gradient Approximation Made Simple
Perdew, J.P.; Burke, K.; Ernzerhof, M.
1996-10-01
Generalized gradient approximations (GGA{close_quote}s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. {copyright} {ital 1996 The American Physical Society.}
Colgate, S.A.
1958-05-27
An improvement is presented in linear accelerators for charged particles with respect to the stable focusing of the particle beam. The improvement consists of providing a radial electric field transverse to the accelerating electric fields and angularly introducing the beam of particles in the field. The results of the foregoing is to achieve a beam which spirals about the axis of the acceleration path. The combination of the electric fields and angular motion of the particles cooperate to provide a stable and focused particle beam.
NASA Technical Reports Server (NTRS)
2006-01-01
[figure removed for brevity, see original site] Context image for PIA03667 Linear Clouds
These clouds are located near the edge of the south polar region. The cloud tops are the puffy white features in the bottom half of the image.
Image information: VIS instrument. Latitude -80.1N, Longitude 52.1E. 17 meter/pixel resolution.
Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.
NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.
NASA Astrophysics Data System (ADS)
Rousseau, Bruno; Ashcroft, Neil W.
2008-03-01
In electronic and structural terms, the light alkalis have long been regarded as `simple systems', at least under ordinary conditions. However, when compressed they exhibit unforeseen complexity; the melting curve of sodium, for example, has a striking maximum, falling to near room temperature melting where a complex structure (CI16) is found, this being in the cubic class but with 16 atoms per unit cell [1,2]. The light alkalis have been extensively studied using ab initio methods with standard assumptions of transferability made for the key pseudopotential input information, largely atomic based. Lacking still, however, is a somewhat more intuitive and physical understanding of the developments in electronic structure with progressive increase in density. In the present work, the problem is treated with non-linear response theory and non-overlapping pseudopotentials, and the structural complexity traced to effective ion-ion interactions with features that both at short range and long display competing state dependence. [1] Gregoryanz et al., Phys. Rev. Lett. 94, 185502 (2005) [2] McMahon et al., Chem. Soc. Rev. 35, 943 (2006)
Characterizations of linear sufficient statistics
NASA Technical Reports Server (NTRS)
Peters, B. C., Jr.; Redner, R.; Decell, H. P., Jr.
1976-01-01
A necessary and sufficient condition is developed such that there exists a continous linear sufficient statistic T for a dominated collection of totally finite measures defined on the Borel field generated by the open sets of a Banach space X. In particular, corollary necessary and sufficient conditions are given so that there exists a rank K linear sufficient statistic T for any finite collection of probability measures having n-variate normal densities. In this case a simple calculation, involving only the population means and covariances, determines the smallest integer K for which there exists a rank K linear sufficient statistic T (as well as an associated statistic T itself).
Super-linear Precision in Simple Neural Population Codes
NASA Astrophysics Data System (ADS)
Schwab, David; Fiete, Ila
2015-03-01
A widely used tool for quantifying the precision with which a population of noisy sensory neurons encodes the value of an external stimulus is the Fisher Information (FI). Maximizing the FI is also a commonly used objective for constructing optimal neural codes. The primary utility and importance of the FI arises because it gives, through the Cramer-Rao bound, the smallest mean-squared error achievable by any unbiased stimulus estimator. However, it is well-known that when neural firing is sparse, optimizing the FI can result in codes that perform very poorly when considering the resulting mean-squared error, a measure with direct biological relevance. Here we construct optimal population codes by minimizing mean-squared error directly and study the scaling properties of the resulting network, focusing on the optimal tuning curve width. We then extend our results to continuous attractor networks that maintain short-term memory of external stimuli in their dynamics. Here we find similar scaling properties in the structure of the interactions that minimize diffusive information loss.
ERIC Educational Resources Information Center
Endres, Frank L.
Symbolic Interactive Matrix Processing Language (SIMPLE) is a conversational matrix-oriented source language suited to a batch or a time-sharing environment. The two modes of operation of SIMPLE are conversational mode and programing mode. This program uses a TAURUS time-sharing system and cathode ray terminals or teletypes. SIMPLE performs all…
Pulmonary infiltrates with eosinophilia; Loffler syndrome; Eosinophilic pneumonia; Pneumonia - eosinophilic ... simple pulmonary eosinophilia is a severe type of pneumonia called acute idiopathic eosinophilic pneumonia.
Simple aging in molecular glasses
NASA Astrophysics Data System (ADS)
Niss, Kristine
2015-03-01
The glass transition takes place when the structural (alpha) relaxation freezes in and the liquid enters a non-equilibrium solid state. This usually happens when the relaxation time, τ, reaches a timescale of 1000 seconds, and τ = 1000 s is pragmatically used as a definition of the glass transition temperature Tg. However, if the glass is studied on a long enough time scale then relaxation is still seen as physical aging. Aging is a non-linear signature of the alpha relaxation in which the relaxation dynamics changes as a function of how far the system has relaxed. If the system is studied well below Tg then equilibrium will not be achieved, but just below or around Tg it is possible to systematically monitor the non-linear relaxation all the way to equilibrium. We have developed a micro crystat which is optimized for making fast changes in temperature and keeping temperature stable over days and even weeks. Combining this micro cryostat with a small dielectric cell it is possible to monitor non-linear relaxation in a dynamical range of more than 4 decades from 10 seconds to a 105 seconds. The aging is monitored after a fast temperature jump. This means that the aging itself is isotherm, and the data therefore directly shows, how the relaxation-rate changes as volume and structure change on the isotherm. We have studied several molecular liquids and find that the data to a very large extend can be understood in terms of a TNM formalism. This implies time-aging-time superposition and suggests a simple picture where the out of equlibrium ``states'' correspond to equilibrium states - at an other temperature. If the alpha relaxation is dynamically heterogeneous as it is commonly believed, then the aging results show that fast and slow ``modes'' of the relaxation are governed in the same way by structure and volume. We hypothesize that aging according to TNM formalism is an intrinsic property of Roskilde Simple liquids.
Amplitude Frequency Response Measurement: A Simple Technique
ERIC Educational Resources Information Center
Satish, L.; Vora, S. C.
2010-01-01
A simple method is described to combine a modern function generator and a digital oscilloscope to configure a setup that can directly measure the amplitude frequency response of a system. This is achieved by synchronously triggering both instruments, with the function generator operated in the "Linear-Sweep" frequency mode, while the oscilloscope…
ERIC Educational Resources Information Center
Herald, Christine
2010-01-01
During the month of May, the author's eighth-grade physical science students study the six simple machines through hands-on activities, reading assignments, videos, and notes. At the end of the month, they can easily identify the six types of simple machine: inclined plane, wheel and axle, pulley, screw, wedge, and lever. To conclude this unit,…
Simple, Internally Adjustable Valve
NASA Technical Reports Server (NTRS)
Burley, Richard K.
1990-01-01
Valve containing simple in-line, adjustable, flow-control orifice made from ordinary plumbing fitting and two allen setscrews. Construction of valve requires only simple drilling, tapping, and grinding. Orifice installed in existing fitting, avoiding changes in rest of plumbing.
ERIC Educational Resources Information Center
Straulino, S.; Bonechi, L.
2010-01-01
Two lenses make it possible to create a simple telescope with quite large magnification. The set-up is very simple and can be reproduced in schools, provided the laboratory has a range of lenses with different focal lengths. In this article, the authors adopt the Keplerian configuration, which is composed of two converging lenses. This instrument,…
Gary S. Groenewold
2005-08-01
Simple bond cleavage is a class of fragmentation reactions in which a single bond is broken, without formation of new bonds between previously unconnected atoms. Because no bond making is involved, simple bond cleavages are endothermic, and activation energies are generally higher than for rearrangement eliminations. The rate of simple bond cleavage reactions is a strong function of the internal energy of the molecular ion, which reflects a loose transition state that resembles reaction products, and has a high density of accessible states. For this reason, simple bond cleavages tend to dominate fragmentation reactions for highly energized molecular ions. Simple bond cleavages have negligible reverse activation energy, and hence they are used as valuable probes of ion thermochemistry, since the energy dependence of the reactions can be related to the bond energy. In organic mass spectrometry, simple bond cleavages of odd electron ions can be either homolytic or heterolytic, depending on whether the fragmentation is driven by the radical site or the charge site. Simple bond cleavages of even electron ions tend to be heterolytic, producing even electron product ions and neutrals.
ERIC Educational Resources Information Center
Blond, J. P.; Boggett, D. M.
1980-01-01
Discusses some basic physical ideas about light scattering and describes a simple Raman spectrometer, a single prism monochromator and a multiplier detector. This discussion is intended for British undergraduate physics students. (HM)
Early Childhood: Simple Science.
ERIC Educational Resources Information Center
Jones, Clare B.; Shafer, Kathryn E.
1987-01-01
Encourages teachers to take advantage of the natural curiosity of young children in enhancing their interest in science. Describes four simple activities involving water, living and non-living things, air pollution, and food. (TW)
ERIC Educational Resources Information Center
Kirkwood, James J.
1994-01-01
Students explore the workings of the lever, wheel and axle, and the inclined plane as they build simple toys--a bulldozer and a road grader. The project takes four weeks. Diagrams and procedures are included. (PR)
ERIC Educational Resources Information Center
White, A. S.
1976-01-01
Describes a simple water channel, for use with an overhead projector. It is run from a water tap and may be used for flow visualization experiments, including the effect of streamlining and elementary building aerodynamics. (MLH)
Sorokine, Alexandre
2011-10-01
Simple Ontology Format (SOFT) library and file format specification provides a set of simple tools for developing and maintaining ontologies. The library, implemented as a perl module, supports parsing and verification of the files in SOFt format, operations with ontologies (adding, removing, or filtering of entities), and converting of ontologies into other formats. SOFT allows users to quickly create ontologies using only a basic text editor, verify it, and portray it in a graph layout system using customized styles.
Simple soluble molecular ionization model
Dunne, Gerald V.; Gauthier, Christopher S.
2004-05-01
We present a simple exact analytical solution, using the Weyl-Titchmarsh-Kodaira spectral theorem, for the spectral function of the one-dimensional diatomic molecule model consisting of two attractive {delta}-function wells in the presence of a static external electric field. For sufficiently deep and far apart wells, this molecule supports both an even and an odd state, and the introduction of a static electric field turns these bound states into quasibound states which are Stark-shifted and broadened. The continuum spectrum also inherits an intricate pattern of resonances which reflect the competition between resonant scattering between the two atomic wells and between the linear potential and one or both atomic well(s). All results are analytic and can be easily plotted. The relation between the large orders of the divergent perturbative Stark-shift series and the nonperturbative widths of quasibound levels is studied.
Simple soluble molecular ionization model
NASA Astrophysics Data System (ADS)
Dunne, Gerald V.; Gauthier, Christopher S.
2004-05-01
We present a simple exact analytical solution, using the Weyl-Titchmarsh-Kodaira spectral theorem, for the spectral function of the one-dimensional diatomic molecule model consisting of two attractive δ -function wells in the presence of a static external electric field. For sufficiently deep and far apart wells, this molecule supports both an even and an odd state, and the introduction of a static electric field turns these bound states into quasibound states which are Stark-shifted and broadened. The continuum spectrum also inherits an intricate pattern of resonances which reflect the competition between resonant scattering between the two atomic wells and between the linear potential and one or both atomic well(s). All results are analytic and can be easily plotted. The relation between the large orders of the divergent perturbative Stark-shift series and the nonperturbative widths of quasibound levels is studied.
The Training Wheel. A Simple Model for Instructional Design.
ERIC Educational Resources Information Center
Rogoff, Rosalind L.
1984-01-01
The author developed an instructional-design model consisting of four simple steps. The model is in a circular format, rather than the usual linear series form, so it is named the training wheel. (SSH)
Simple circuit functions as frequency discriminator for PFM signals
NASA Technical Reports Server (NTRS)
Billingsley, J.
1965-01-01
Simple circuit monitors the frequency of PFM /Pulse Frequency Modulated/ telemetry signals. This discriminator can be used as a constant current integrator in such circuits as linear sweep and time delay.
Eisenhardt, K M; Sull, D N
2001-01-01
The success of Yahoo!, eBay, Enron, and other companies that have become adept at morphing to meet the demands of changing markets can't be explained using traditional thinking about competitive strategy. These companies have succeeded by pursuing constantly evolving strategies in market spaces that were considered unattractive according to traditional measures. In this article--the third in an HBR series by Kathleen Eisenhardt and Donald Sull on strategy in the new economy--the authors ask, what are the sources of competitive advantage in high-velocity markets? The secret, they say, is strategy as simple rules. The companies know that the greatest opportunities for competitive advantage lie in market confusion, but they recognize the need for a few crucial strategic processes and a few simple rules. In traditional strategy, advantage comes from exploiting resources or stable market positions. In strategy as simple rules, advantage comes from successfully seizing fleeting opportunities. Key strategic processes, such as product innovation, partnering, or spinout creation, place the company where the flow of opportunities is greatest. Simple rules then provide the guidelines within which managers can pursue such opportunities. Simple rules, which grow out of experience, fall into five broad categories: how- to rules, boundary conditions, priority rules, timing rules, and exit rules. Companies with simple-rules strategies must follow the rules religiously and avoid the temptation to change them too frequently. A consistent strategy helps managers sort through opportunities and gain short-term advantage by exploiting the attractive ones. In stable markets, managers rely on complicated strategies built on detailed predictions of the future. But when business is complicated, strategy should be simple. PMID:11189455
2011-10-01
Simple Ontology Format (SOFT) library and file format specification provides a set of simple tools for developing and maintaining ontologies. The library, implemented as a perl module, supports parsing and verification of the files in SOFt format, operations with ontologies (adding, removing, or filtering of entities), and converting of ontologies into other formats. SOFT allows users to quickly create ontologies using only a basic text editor, verify it, and portray it in a graph layoutmore » system using customized styles.« less
Detection and recognition of simple spatial forms
NASA Technical Reports Server (NTRS)
Watson, A. B.
1983-01-01
A model of human visual sensitivity to spatial patterns is constructed. The model predicts the visibility and discriminability of arbitrary two-dimensional monochrome images. The image is analyzed by a large array of linear feature sensors, which differ in spatial frequency, phase, orientation, and position in the visual field. All sensors have one octave frequency bandwidths, and increase in size linearly with eccentricity. Sensor responses are processed by an ideal Bayesian classifier, subject to uncertainty. The performance of the model is compared to that of the human observer in detecting and discriminating some simple images.
ERIC Educational Resources Information Center
Cole, K.C.
1982-01-01
Discusses San Francisco's Exploratorium, a science teaching center with 500 exhibits focusing on human perception, but extending to everything from the mechanics of voice to the art of illusion, from holograms to harmonics. The Exploratorium emphasizes "simple science" (refractions/resonances, sounds/shadows) to tune in the senses and turn on the…
Entropy Is Simple, Qualitatively.
ERIC Educational Resources Information Center
Lambert, Frank L.
2002-01-01
Suggests that qualitatively, entropy is simple. Entropy increase from a macro viewpoint is a measure of the dispersal of energy from localized to spread out at a temperature T. Fundamentally based on statistical and quantum mechanics, this approach is superior to the non-fundamental "disorder" as a descriptor of entropy change. (MM)
Simple epibulbar cartilaginous choristoma.
Alyahya, Ahmed; Alkhalidi, Hisham; Alsuhaibani, Adel H
2011-02-01
A 15-year-old boy was referred for management of a medial, pedunculated, subconjunctival epibulbar mass of 5 months' duration in the left eye. The lesion was removed with complication, and histopathology confirmed a cartilaginous choristoma. To our knowledge this is the first reported case of a simple epibulbar cartilaginous choristoma.
2013-05-01
Simple Lookup Service (sLS) is a REST/JSON based lookup service that allows users to publish information in the form of key-value pairs and search for the published information. The lookup service supports both pull and push model. This software can be used to create a distributed architecture/cloud.
ERIC Educational Resources Information Center
Eggen, Per-Odd
2009-01-01
This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…
ERIC Educational Resources Information Center
Norbury, John W.
2006-01-01
A set of examples is provided that illustrate the use of work as applied to simple machines. The ramp, pulley, lever and hydraulic press are common experiences in the life of a student, and their theoretical analysis therefore makes the abstract concept of work more real. The mechanical advantage of each of these systems is also discussed so that…
ERIC Educational Resources Information Center
Urban, Wayne
2004-01-01
In this article, the author provides his analyses on Richard Kluger's "Simple Justice," a book that portrays the major players involved in the landmark "Brown" decision. He comments generally on Kluger and highlights a few interesting aspects of his analysis, including his interpretation of the actions of then clerk and later justice and still…
ERIC Educational Resources Information Center
Temiz, Burak Kagan; Yavuz, Ahmet
2015-01-01
This study was done to develop a simple and inexpensive wave driver that can be used in experiments on string waves. The wave driver was made using a battery-operated toy car, and the apparatus can be used to produce string waves at a fixed frequency. The working principle of the apparatus is as follows: shortly after the car is turned on, the…
ERIC Educational Resources Information Center
Hoffman, Herbert H.
A simple and cheap manual double entry continuous transaction posting system with running balances is developed for bookkeeping by small libraries. A very small library may operate without any system of fiscal control but when a library's budget approaches three figures, some kind of bookkeeping must be introduced. To maintain control over his…
ERIC Educational Resources Information Center
Shallcross, Dudley E.; Harrison, Tim G.
2007-01-01
The newly revised specifications for GCSE science involve greater consideration of climate change. This topic appears in either the chemistry or biology section, depending on the examination board, and is a good example of "How Science Works." It is therefore timely that students are given an opportunity to conduct some simple climate modelling.…
Linear thermal circulator based on Coriolis forces.
Li, Huanan; Kottos, Tsampikos
2015-02-01
We show that the presence of a Coriolis force in a rotating linear lattice imposes a nonreciprocal propagation of the phononic heat carriers. Using this effect we propose the concept of Coriolis linear thermal circulator which can control the circulation of a heat current. A simple model of three coupled harmonic masses on a rotating platform permits us to demonstrate giant circulating rectification effects for moderate values of the angular velocities of the platform.
Simple Waveforms, Simply Described
NASA Technical Reports Server (NTRS)
Baker, John G.
2008-01-01
Since the first Lazarus Project calculations, it has been frequently noted that binary black hole merger waveforms are 'simple.' In this talk we examine some of the simple features of coalescence and merger waveforms from a variety of binary configurations. We suggest an interpretation of the waveforms in terms of an implicit rotating source. This allows a coherent description, of both the inspiral waveforms, derivable from post-Newtonian(PN) calculations, and the numerically determined merger-ringdown. We focus particularly on similarities in the features of various Multipolar waveform components Generated by various systems. The late-time phase evolution of most L these waveform components are accurately described with a sinple analytic fit. We also discuss apparent relationships among phase and amplitude evolution. Taken together with PN information, the features we describe can provide an approximate analytic description full coalescence wavefoRms. complementary to other analytic waveforns approaches.
NASA Astrophysics Data System (ADS)
Ramsden, D.; Zhang, S. N.
1988-06-01
Normal phoswich detector systems use a combination of NaI(Tl) and CsI(Na) scintillators and require the application of careful pulse-shape discriminator techniques to resolve the two components in the scintillation light output which have decay constants of 250 and 630 ns respectively. These techniques provide a good anticoincidence veto efficiency for a relatively narrow range in the ratio of energy deposits in the two crytals and for a detector system whose temperature is carefully controlled. This paper describes the performance of a simple phoswich which makes use of the fast UV signal from a BaF 2 crystal to provide a prompt veto signal. The performance to be expected from various combinations of a BaF 2 anticoincidence crystal with other primary detectors is presented. These simulations have been verified by simple experimental tests.
Probabilistic simple splicing systems
NASA Astrophysics Data System (ADS)
Selvarajoo, Mathuri; Heng, Fong Wan; Sarmin, Nor Haniza; Turaev, Sherzod
2014-06-01
A splicing system, one of the early theoretical models for DNA computing was introduced by Head in 1987. Splicing systems are based on the splicing operation which, informally, cuts two strings of DNA molecules at the specific recognition sites and attaches the prefix of the first string to the suffix of the second string, and the prefix of the second string to the suffix of the first string, thus yielding the new strings. For a specific type of splicing systems, namely the simple splicing systems, the recognition sites are the same for both strings of DNA molecules. It is known that splicing systems with finite sets of axioms and splicing rules only generate regular languages. Hence, different types of restrictions have been considered for splicing systems in order to increase their computational power. Recently, probabilistic splicing systems have been introduced where the probabilities are initially associated with the axioms, and the probabilities of the generated strings are computed from the probabilities of the initial strings. In this paper, some properties of probabilistic simple splicing systems are investigated. We prove that probabilistic simple splicing systems can also increase the computational power of the splicing languages generated.
Electrothermal linear actuator
NASA Technical Reports Server (NTRS)
Derr, L. J.; Tobias, R. A.
1969-01-01
Converting electric power into powerful linear thrust without generation of magnetic fields is accomplished with an electrothermal linear actuator. When treated by an energized filament, a stack of bimetallic washers expands and drives the end of the shaft upward.
NASA Technical Reports Server (NTRS)
Tuey, R. C.
1972-01-01
Computer solutions of linear programming problems are outlined. Information covers vector spaces, convex sets, and matrix algebra elements for solving simultaneous linear equations. Dual problems, reduced cost analysis, ranges, and error analysis are illustrated.
Dimensional analysis made simple
NASA Astrophysics Data System (ADS)
Lira, Ignacio
2013-11-01
An inductive strategy is proposed for teaching dimensional analysis to second- or third-year students of physics, chemistry, or engineering. In this strategy, Buckingham's theorem is seen as a consequence and not as the starting point. In order to concentrate on the basics, the mathematics is kept as elementary as possible. Simple examples are suggested for classroom demonstrations of the power of the technique and others are put forward for homework or experimentation, but instructors are encouraged to produce examples of their own.
NASA Technical Reports Server (NTRS)
Lawson, C. L.; Krogh, F. T.; Gold, S. S.; Kincaid, D. R.; Sullivan, J.; Williams, E.; Hanson, R. J.; Haskell, K.; Dongarra, J.; Moler, C. B.
1982-01-01
The Basic Linear Algebra Subprograms (BLAS) library is a collection of 38 FORTRAN-callable routines for performing basic operations of numerical linear algebra. BLAS library is portable and efficient source of basic operations for designers of programs involving linear algebriac computations. BLAS library is supplied in portable FORTRAN and Assembler code versions for IBM 370, UNIVAC 1100 and CDC 6000 series computers.
A Vernacular for Linear Latent Growth Models
ERIC Educational Resources Information Center
Hancock, Gregory R.; Choi, Jaehwa
2006-01-01
In its most basic form, latent growth modeling (latent curve analysis) allows an assessment of individuals' change in a measured variable X over time. For simple linear models, as with other growth models, parameter estimates associated with the a construct (amount of X at a chosen temporal reference point) and b construct (growth in X per unit…
Sauer's non-linear voltage division.
Schwan, H P; McAdams, E T; Jossinet, J
2002-09-01
The non-linearity of the electrode-tissue interface impedance gives rise to harmonics and thus degrades the accuracy of impedance measurements. Also, electrodes are often driven into the non-linear range of their polarisation impedance. This is particularly true in clinical applications. Techniques to correct for electrode effects are usually based on linear electrode impedance data. However, these data can be very different from the non-linear values needed. Non-linear electrode data suggested a model based on simple assumptions. It is useful in predicting the frequency dependence of non-linear effects from linear properties. Sauer's treatment is a first attempt to provide a more general and rigorous basis for modelling the non-linear state. The paper reports Sauer's treatment of the non-linear case and points out its limitations. The paper considers Sauer's treatment of a series arrangement of two impedances. The tissue impedance is represented by a linear voltage-current characteristic. The interface impedance is represented by a Volterra expansion. The response of this network to periodic signals is calculated up to the second-order term of the series expansion. The resultant, time-dependent current is found to contain a DC term (rectification), as well as frequency-dependent terms. Sauer's treatment assumes a voltage clamp across the impedances and neglects higher-order terms in the series expansion. As a consequence, it fails adequately to represent some experimentally observed phenomena. It is therefore suggested that Sauer's expressions for the voltage divider should be combined with the non-linear treatments previously published by the co-authors. Although Sauer's work on the non-linear voltage divider was originally applied to the study of the non-linear behaviour of the electrode-electrolyte interface and biological tissues, it is stressed, however, that the work is applicable to a wide range of research areas.
Graham, Peter W.; Horn, Bart; Kachru, Shamit; Rajendran, Surjeet; Torroba, Gonzalo; /Stanford U., ITP /SLAC
2011-12-14
We explore simple but novel bouncing solutions of general relativity that avoid singularities. These solutions require curvature k = +1, and are supported by a negative cosmological term and matter with -1 < w < -1 = 3. In the case of moderate bounces (where the ratio of the maximal scale factor a{sub +} to the minimal scale factor a{sub -} is {Omicron}(1)), the solutions are shown to be classically stable and cycle through an infinite set of bounces. For more extreme cases with large a{sub +} = a{sub -}, the solutions can still oscillate many times before classical instabilities take them out of the regime of validity of our approximations. In this regime, quantum particle production also leads eventually to a departure from the realm of validity of semiclassical general relativity, likely yielding a singular crunch. We briefly discuss possible applications of these models to realistic cosmology.
Two Simple Models for Fracking
NASA Astrophysics Data System (ADS)
Norris, Jaren Quinn
Recent developments in fracking have enable the recovery of oil and gas from tight shale reservoirs. These developments have also made fracking one of the most controversial environmental issues in the United States. Despite the growing controversy surrounding fracking, there is relatively little publicly available research. This dissertation introduces two simple models for fracking that were developed using techniques from non-linear and statistical physics. The first model assumes that the volume of induced fractures must be equal to the volume of injected fluid. For simplicity, these fractures are assumed to form a spherically symmetric damage region around the borehole. The predicted volumes of water necessary to create a damage region with a given radius are in good agreement with reported values. The second model is a modification of invasion percolation which was previously introduced to model water flooding. The reservoir rock is represented by a regular lattice of local traps that contain oil and/or gas separated by rock barriers. The barriers are assumed to be highly heterogeneous and are assigned random strengths. Fluid is injected from a central site and the weakest rock barrier breaks allowing fluid to flow into the adjacent site. The process repeats with the weakest barrier breaking and fluid flowing to an adjacent site each time step. Extensive numerical simulations were carried out to obtain statistical properties of the growing fracture network. The network was found to be fractal with fractal dimensions differing slightly from the accepted values for traditional percolation. Additionally, the network follows Horton-Strahler and Tokunaga branching statistics which have been used to characterize river networks. As with other percolation models, the growth of the network occurs in bursts. These bursts follow a power-law size distribution similar to observed microseismic events. Reservoir stress anisotropy is incorporated into the model by assigning
Wiedemann, H.
1981-11-01
Since no linear colliders have been built yet it is difficult to know at what energy the linear cost scaling of linear colliders drops below the quadratic scaling of storage rings. There is, however, no doubt that a linear collider facility for a center of mass energy above say 500 GeV is significantly cheaper than an equivalent storage ring. In order to make the linear collider principle feasible at very high energies a number of problems have to be solved. There are two kinds of problems: one which is related to the feasibility of the principle and the other kind of problems is associated with minimizing the cost of constructing and operating such a facility. This lecture series describes the problems and possible solutions. Since the real test of a principle requires the construction of a prototype I will in the last chapter describe the SLC project at the Stanford Linear Accelerator Center.
NASA Technical Reports Server (NTRS)
Holloway, Sidney E., III (Inventor); Crossley, Edward A., Jr. (Inventor); Jones, Irby W. (Inventor); Miller, James B. (Inventor); Davis, C. Calvin (Inventor); Behun, Vaughn D. (Inventor); Goodrich, Lewis R., Sr. (Inventor)
1992-01-01
A linear mass actuator includes an upper housing and a lower housing connectable to each other and having a central passageway passing axially through a mass that is linearly movable in the central passageway. Rollers mounted in the upper and lower housings in frictional engagement with the mass translate the mass linearly in the central passageway and drive motors operatively coupled to the roller means, for rotating the rollers and driving the mass axially in the central passageway.
Linear phase compressive filter
McEwan, Thomas E.
1995-01-01
A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line.
Linear phase compressive filter
McEwan, T.E.
1995-06-06
A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line. 2 figs.
Fault tolerant linear actuator
Tesar, Delbert
2004-09-14
In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.
Feynman's simple quantum mechanics
NASA Astrophysics Data System (ADS)
Taylor, Edwin F.
1997-03-01
This sample class presents an alternative to the conventional introduction to quantum mechanics and describes its current use in a credit course. This alternative introduction rests on theory presented in professional and popular writings by Richard Feynman. Feynman showed that Nature gives a simple command to the electron: "Explore all paths." All of nonrelativistic quantum mechanics, among other fundamental results, comes from this command. With a desktop computer the student points and clicks to tell a modeled electron which paths to follow. The computer then shows the results, which embody the elemental strangeness and paradoxical behaviors of the world of the very small. Feynman's approach requires few equations and provides a largely non-mathematical introduction to the wave function of conventional quantum mechanics. Draft software and materials already used for two semesters in an e-mail computer conference credit university course show that Feynman's approach works well with a variety of students. The sample class explores computer and written material and describes the next steps in its development.
Endoscopic simple prostatectomy
Borkowski, Tomasz; Chłosta, Piotr; Dobruch, Jakub; Fiutowski, Marek; Jaskulski, Jarosław; Słojewski, Marcin; Szydełko, Tomasz; Szymański, Michał; Demkow, Tomasz
2014-01-01
Introduction Many options exist for the surgical treatment of lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH), including transurethral resection of the prostate (TURP), laser surgery, and open adenomectomy. Recently, endoscopic techniques have been used in the treatment of BPH. Material and methods We reviewed clinical studies in PubMed describing minimally invasive endoscopic procedures for the treatment of BPH. Results Laparoscopic adenomectomy (LA) and robotic–assisted simple prostatectomy (RASP) were introduced in the early 2000s. These operative techniques have been standardized and reproducible, with some individual modifications. Studies analyzing the outcomes of LA and RASP have reported significant improvements in urinary flow and decreases in patient International Prostate Symptom Score (IPSS). These minimally invasive approaches have resulted in a lower rate of complications, shorter hospital stays, smaller scars, faster recoveries, and an earlier return to work. Conclusions Minimally invasive techniques such as LA and RASP for the treatment BPH are safe, efficacious, and allow faster recovery. These procedures have a short learning curve and offer new options for the surgeon treating BPH. PMID:25667758
Bull, J J; Meyers, Lauren Ancel; Lachmann, Michael
2005-11-01
Quasispecies are clouds of genotypes that appear in a population at mutation-selection balance. This concept has recently attracted the attention of virologists, because many RNA viruses appear to generate high levels of genetic variation that may enhance the evolution of drug resistance and immune escape. The literature on these important evolutionary processes is, however, quite challenging. Here we use simple models to link mutation-selection balance theory to the most novel property of quasispecies: the error threshold-a mutation rate below which populations equilibrate in a traditional mutation-selection balance and above which the population experiences an error catastrophe, that is, the loss of the favored genotype through frequent deleterious mutations. These models show that a single fitness landscape may contain multiple, hierarchically organized error thresholds and that an error threshold is affected by the extent of back mutation and redundancy in the genotype-to-phenotype map. Importantly, an error threshold is distinct from an extinction threshold, which is the complete loss of the population through lethal mutations. Based on this framework, we argue that the lethal mutagenesis of a viral infection by mutation-inducing drugs is not a true error catastophe, but is an extinction catastrophe.
Strnad, Pavel; Guldiken, Nurdan; Helenius, Terhi O; Misiorek, Julia O; Nyström, Joel H; Lähdeniemi, Iris A K; Silvander, Jonas S G; Kuscuoglu, Deniz; Toivola, Diana M
2016-01-01
Simple epithelial keratins (SEKs) are the cytoplasmic intermediate filament proteins of single-layered and glandular epithelial cells as found in the liver, pancreas, intestine, and lung. SEKs have broad cytoprotective functions, which are facilitated by dynamic posttranslational modifications and interaction with associated proteins. SEK filaments are composed of obligate heteropolymers of type II (K7, K8) and type I (K18-K20, K23) keratins. The multifaceted roles of SEKs are increasingly appreciated due to findings obtained from transgenic mouse models and human studies that identified SEK variants in several digestive diseases. Reorganization of the SEK network into aggregates called Mallory-Denk bodies (MDBs) is characteristic for specific liver disorders such as alcoholic and nonalcoholic steatohepatitis. To spur further research on SEKs, we here review the methods and potential caveats of their isolation as well as possibilities to study them in cell culture. The existing transgenic SEK mouse models, their advantages and potential drawbacks are discussed. The tools to induce MDBs, ways of their visualization and quantification, as well as the possibilities to detect SEK variants in humans are summarized.
A Simple Accelerometer Calibrator
NASA Astrophysics Data System (ADS)
Salam, R. A.; Islamy, M. R. F.; Munir, M. M.; Latief, H.; Irsyam, M.; Khairurrijal
2016-08-01
High possibility of earthquake could lead to the high number of victims caused by it. It also can cause other hazards such as tsunami, landslide, etc. In that case it requires a system that can examine the earthquake occurrence. Some possible system to detect earthquake is by creating a vibration sensor system using accelerometer. However, the output of the system is usually put in the form of acceleration data. Therefore, a calibrator system for accelerometer to sense the vibration is needed. In this study, a simple accelerometer calibrator has been developed using 12 V DC motor, optocoupler, Liquid Crystal Display (LCD) and AVR 328 microcontroller as controller system. The system uses the Pulse Wave Modulation (PWM) form microcontroller to control the motor rotational speed as response to vibration frequency. The frequency of vibration was read by optocoupler and then those data was used as feedback to the system. The results show that the systems could control the rotational speed and the vibration frequencies in accordance with the defined PWM.
Craig, Benjamin M.; Busschbach, Jan J.V.; Salomon, Joshua A.
2009-01-01
Objectives To examine the relationship between ordinal and cardinal valuation of health states. Study Design and Setting We analyzed rank, visual analog scale (VAS), and time trade-off (TTO) responses for 52 health states defined using the EQ-5D classification system developed by the EuroQol Group. We analyzed 179,431 responses from 11,483 subjects in eight countries: Slovenia, Argentina, Denmark, Japan, Netherlands, Spain, United Kingdom, and United States. We first compared responses across methods by frequency of ties and values below dead. Ordinal associations between methods were evaluated using Spearman’s correlation and Kendall’s tau. Next, we estimated numerical values from rank responses using country-specific conditional logit models. After anchoring predicted values on a common scale, we further investigated the cardinal relationships between rank, VAS, and TTO-based values using Pearson’s rho and quadratic regression. Results For each country, rank responses are less likely than TTO responses to be tied and to indicate that states are worse than dead. In all countries, rank responses show a strong linear correlation with both TTO (Pearson’s rho = 0.88-0.99) and VAS (rho = 0.91-0.98) responses. However, rank-based values imply greater decrements in health for mild states than cardinal values. Conclusions Illiteracy and innumeracy can hinder implementation of complex preference elicitation techniques in diverse settings and populations. These results indicate that ranking exercises may provide an attractive alternative for health-state valuation. PMID:18945585
Magnetoelectric effect in simple collinear antiferromagnetic spinels
NASA Astrophysics Data System (ADS)
Saha, Rana; Ghara, Somnath; Suard, Emmanuelle; Jang, Dong Hyun; Kim, Kee Hoon; Ter-Oganessian, N. V.; Sundaresan, A.
2016-07-01
We report the discovery of the linear magnetoelectric effect in a family of spinel oxides, C o3O4 and Mn B2O4 (B =Al ,Ga) with simple collinear antiferromagnetic spin structure. An external magnetic field induces a dielectric anomaly at TN, accompanied by the generation of electric polarization that varies linearly with magnetic field. Magnetization and magnetoelectric measurements on a single crystal of MnG a2O4 together with a phenomenological theory suggest that the easy axis direction is [111] with the corresponding magnetic symmetry R 3¯'m' . The proposed theoretical model of single-ion contribution of magnetic ions located in a noncentrosymmetric crystal environment stands for a generic mechanism for observing magnetoelectric effects in these and other similar materials.
Simple effective interaction for dimensional crossover
NASA Astrophysics Data System (ADS)
Constantin, Lucian A.
2016-03-01
We show that the effective electron-electron interaction veff[n ] (r ,r') =erf [|r - r'|b (n ) ]/|r -r'| , with n being the electronic density and b (n ) fixed from the compressibility sum rule, is remarkably accurate in both three and two dimensions, competing with the actual state-of-the-art exchange-correlation static kernels. Using this result, we propose a simple isotropic approximation for the quasi-two-dimensional regime, which gives a realistic wave vector analysis of the correlation energy, in the context of the linear response time-dependent density functional theory.
Rheology and aging: A simple approach
NASA Astrophysics Data System (ADS)
Derec, C.; Ajdari, A.; Lequeux, F.
2001-03-01
We introduce a rheological model to describe the low-frequency mechanical properties of systems near a fluid/paste transition. We propose a Landau-like expansion for the vicinity of this transition, treating the stress relaxation rate as an order parameter. This leads to a formally simple model that allows us to describe the interplay between aging and non-linearities in the mechanical response of the system. We focus here on systems prepared by fluidification under a strong shear, on which mechanical measurments are performed (oscillatory rheology, stress relaxation, response to a steady shear rate), after a waiting time during which the system evolves on its own.
Simple inflationary quintessential model
NASA Astrophysics Data System (ADS)
de Haro, Jaume; Amorós, Jaume; Pan, Supriya
2016-04-01
In the framework of a flat Friedmann-Lemaître-Robertson-Walker geometry, we present a non-geodesically past complete model of our Universe without the big bang singularity at finite cosmic time, describing its evolution starting from its early inflationary era up to the present accelerating phase. We found that a hydrodynamical fluid with nonlinear equation of state could result in such scenario, which after the end of this inflationary stage, suffers a sudden phase transition and enters into the stiff matter dominated era, and the Universe becomes reheated due to a huge amount of particle production. Finally, it asymptotically enters into the de Sitter phase concluding the present accelerated expansion. Using the reconstruction technique, we also show that this background provides an extremely simple inflationary quintessential potential whose inflationary part is given by the well-known 1-dimensional Higgs potential, i.e., a double well inflationary potential, and the quintessential one by an exponential potential that leads to a deflationary regime after this inflation, and it can depict the current cosmic acceleration at late times. Moreover the Higgs potential leads to a power spectrum of the cosmological perturbations which fit well with the latest Planck estimations. Further, we compared our viable potential with some known inflationary quintessential potential, which shows that our quintessential model, that is, the Higgs potential combined with the exponential one, is an improved version of them because it contains an analytic solution that allows us to perform all analytic calculations. Finally, we have shown that the introduction of a nonzero cosmological constant simplifies the potential considerably with an analytic behavior of the background which again permits us to evaluate all the quantities analytically.
Linearly polarized fiber amplifier
Kliner, Dahv A.; Koplow, Jeffery P.
2004-11-30
Optically pumped rare-earth-doped polarizing fibers exhibit significantly higher gain for one linear polarization state than for the orthogonal state. Such a fiber can be used to construct a single-polarization fiber laser, amplifier, or amplified-spontaneous-emission (ASE) source without the need for additional optical components to obtain stable, linearly polarized operation.
Richter, B.
1985-12-01
A report is given on the goals and progress of the SLAC Linear Collider. The status of the machine and the detectors are discussed and an overview is given of the physics which can be done at this new facility. Some ideas on how (and why) large linear colliders of the future should be built are given.
NASA Technical Reports Server (NTRS)
Clancy, John P.
1988-01-01
The object of the invention is to provide a mechanical force actuator which is lightweight and manipulatable and utilizes linear motion for push or pull forces while maintaining a constant overall length. The mechanical force producing mechanism comprises a linear actuator mechanism and a linear motion shaft mounted parallel to one another. The linear motion shaft is connected to a stationary or fixed housing and to a movable housing where the movable housing is mechanically actuated through actuator mechanism by either manual means or motor means. The housings are adapted to releasably receive a variety of jaw or pulling elements adapted for clamping or prying action. The stationary housing is adapted to be pivotally mounted to permit an angular position of the housing to allow the tool to adapt to skewed interfaces. The actuator mechanisms is operated by a gear train to obtain linear motion of the actuator mechanism.
Linear models: permutation methods
Cade, B.S.; Everitt, B.S.; Howell, D.C.
2005-01-01
Permutation tests (see Permutation Based Inference) for the linear model have applications in behavioral studies when traditional parametric assumptions about the error term in a linear model are not tenable. Improved validity of Type I error rates can be achieved with properly constructed permutation tests. Perhaps more importantly, increased statistical power, improved robustness to effects of outliers, and detection of alternative distributional differences can be achieved by coupling permutation inference with alternative linear model estimators. For example, it is well-known that estimates of the mean in linear model are extremely sensitive to even a single outlying value of the dependent variable compared to estimates of the median [7, 19]. Traditionally, linear modeling focused on estimating changes in the center of distributions (means or medians). However, quantile regression allows distributional changes to be estimated in all or any selected part of a distribution or responses, providing a more complete statistical picture that has relevance to many biological questions [6]...
Analysis of linear trade models and relation to scale economies.
Gomory, R E; Baumol, W J
1997-09-01
We discuss linear Ricardo models with a range of parameters. We show that the exact boundary of the region of equilibria of these models is obtained by solving a simple integer programming problem. We show that there is also an exact correspondence between many of the equilibria resulting from families of linear models and the multiple equilibria of economies of scale models.
Practical Session: Multiple Linear Regression
NASA Astrophysics Data System (ADS)
Clausel, M.; Grégoire, G.
2014-12-01
Three exercises are proposed to illustrate the simple linear regression. In the first one investigates the influence of several factors on atmospheric pollution. It has been proposed by D. Chessel and A.B. Dufour in Lyon 1 (see Sect. 6 of http://pbil.univ-lyon1.fr/R/pdf/tdr33.pdf) and is based on data coming from 20 cities of U.S. Exercise 2 is an introduction to model selection whereas Exercise 3 provides a first example of analysis of variance. Exercises 2 and 3 have been proposed by A. Dalalyan at ENPC (see Exercises 2 and 3 of http://certis.enpc.fr/~dalalyan/Download/TP_ENPC_5.pdf).
Phase space evolution in linear instabilities
Pantellini, F.G.E.; Burgess, D.; Schwartz, S.J. )
1994-12-01
A simple and powerful way to investigate the linear evolution of particle distribution functions in kinetic instabilities in a homogeneous collisionless plasma is presented. The method can be applied to any kind of instability, provided the characteristics (growth rate, frequency, wave vector, and polarization) of the mode are known and can also be used to estimate the amplitude of the waves at the end of the linear phase of growth. Two didactic examples are used to illustrate the versatility of the technique: the Alfven Ion Cyclotron (AIC) instability, which is electromagnetic, and the Electron Ion Cyclotron (EIC) instability, which is electrostatic.
Portfolio optimization using fuzzy linear programming
NASA Astrophysics Data System (ADS)
Pandit, Purnima K.
2013-09-01
Portfolio Optimization (PO) is a problem in Finance, in which investor tries to maximize return and minimize risk by carefully choosing different assets. Expected return and risk are the most important parameters with regard to optimal portfolios. In the simple form PO can be modeled as quadratic programming problem which can be put into equivalent linear form. PO problems with the fuzzy parameters can be solved as multi-objective fuzzy linear programming problem. In this paper we give the solution to such problems with an illustrative example.
Linear control of the flywheel inverted pendulum.
Olivares, Manuel; Albertos, Pedro
2014-09-01
The flywheel inverted pendulum is an underactuated mechanical system with a nonlinear model but admitting a linear approximation around the unstable equilibrium point in the upper position. Although underactuated systems usually require nonlinear controllers, the easy tuning and understanding of linear controllers make them more attractive for designers and final users. In a recent paper, a simple PID controller was proposed by the authors, leading to an internally unstable controlled plant. To achieve global stability, two options are developed here: first by introducing an internal stabilizing controller and second by replacing the PID controller by an observer-based state feedback control. Simulation and experimental results show the effectiveness of the design.
NASA Technical Reports Server (NTRS)
Studer, P. A. (Inventor)
1983-01-01
A linear magnetic bearing system having electromagnetic vernier flux paths in shunt relation with permanent magnets, so that the vernier flux does not traverse the permanent magnet, is described. Novelty is believed to reside in providing a linear magnetic bearing having electromagnetic flux paths that bypass high reluctance permanent magnets. Particular novelty is believed to reside in providing a linear magnetic bearing with a pair of axially spaced elements having electromagnets for establishing vernier x and y axis control. The magnetic bearing system has possible use in connection with a long life reciprocating cryogenic refrigerator that may be used on the space shuttle.
... is the device most commonly used for external beam radiation treatments for patients with cancer. The linear ... shape of the patient's tumor and the customized beam is directed to the patient's tumor. The beam ...
Isolated linear blaschkoid psoriasis.
Nasimi, M; Abedini, R; Azizpour, A; Nikoo, A
2016-10-01
Linear psoriasis (LPs) is considered a rare clinical presentation of psoriasis, which is characterized by linear erythematous and scaly lesions along the lines of Blaschko. We report the case of a 20-year-old man who presented with asymptomatic linear and S-shaped erythematous, scaly plaques on right side of his trunk. The plaques were arranged along the lines of Blaschko with a sharp demarcation at the midline. Histological examination of a skin biopsy confirmed the diagnosis of psoriasis. Topical calcipotriol and betamethasone dipropionate ointments were prescribed for 2 months. A good clinical improvement was achieved, with reduction in lesion thickness and scaling. In patients with linear erythematous and scaly plaques along the lines of Blaschko, the diagnosis of LPs should be kept in mind, especially in patients with asymptomatic lesions of late onset. PMID:27663156
NASA Technical Reports Server (NTRS)
Laughlin, Darren
1995-01-01
Inertial linear actuators developed to suppress residual accelerations of nominally stationary or steadily moving platforms. Function like long-stroke version of voice coil in conventional loudspeaker, with superimposed linear variable-differential transformer. Basic concept also applicable to suppression of vibrations of terrestrial platforms. For example, laboratory table equipped with such actuators plus suitable vibration sensors and control circuits made to vibrate much less in presence of seismic, vehicular, and other environmental vibrational disturbances.
Shetty, Shricharith; Rao, Raghavendra; Kudva, R Ranjini; Subramanian, Kumudhini
2016-01-01
Alopecia areata (AA) over scalp is known to present in various shapes and extents of hair loss. Typically it presents as circumscribed patches of alopecia with underlying skin remaining normal. We describe a rare variant of AA presenting in linear band-like form. Only four cases of linear alopecia have been reported in medical literature till today, all four being diagnosed as lupus erythematosus profundus. PMID:27625568
Shetty, Shricharith; Rao, Raghavendra; Kudva, R Ranjini; Subramanian, Kumudhini
2016-01-01
Alopecia areata (AA) over scalp is known to present in various shapes and extents of hair loss. Typically it presents as circumscribed patches of alopecia with underlying skin remaining normal. We describe a rare variant of AA presenting in linear band-like form. Only four cases of linear alopecia have been reported in medical literature till today, all four being diagnosed as lupus erythematosus profundus.
Shetty, Shricharith; Rao, Raghavendra; Kudva, R Ranjini; Subramanian, Kumudhini
2016-01-01
Alopecia areata (AA) over scalp is known to present in various shapes and extents of hair loss. Typically it presents as circumscribed patches of alopecia with underlying skin remaining normal. We describe a rare variant of AA presenting in linear band-like form. Only four cases of linear alopecia have been reported in medical literature till today, all four being diagnosed as lupus erythematosus profundus. PMID:27625568
Inpainting with sparse linear combinations of exemplars
Wohlberg, Brendt
2008-01-01
We introduce a new exemplar-based inpainting algorithm based on representing the region to be inpainted as a sparse linear combination of blocks extracted from similar parts of the image being inpainted. This method is conceptually simple, being computed by functional minimization, and avoids the complexity of correctly ordering the filling in of missing regions of other exemplar-based methods. Initial performance comparisons on small inpainting regions indicate that this method provides similar or better performance than other recent methods.
Transformation of time dependence to linear algebra
NASA Astrophysics Data System (ADS)
Menšík, Miroslav
2005-10-01
Reduced density matrix and memory function in the Nakajima-Zwanzig equation are expanded in properly chosen basis of special functions. This trick completely transforms time dependence to linear algebra. Then, the master equation for memory function is constructed and expanded in the same basis functions. For the model of a simple harmonic oscillator it is shown that this trick introduces infinite partial summation of the memory function in the system-bath interaction.
A Simple Iterative Solution of Nonlinear Algebraic Systems
NASA Astrophysics Data System (ADS)
Gousidou, Maria; Koutitas, Christopher
2009-09-01
A simple, robust, easily programmable and efficient method for the iterative solution of nonlinear algebraic systems, commonly appearing in nonlinear mechanics, based on Newton-Raphson method (without repeatedly solving linear algebraic systems), is proposed, synoptically described and experimentally investigated. Fast convergence and easy programming are its main qualifications.
Study Guide: Seven Simple Secrets
ERIC Educational Resources Information Center
Satterfield, Nancy; Breaux, Annette; Whitaker, Todd
2007-01-01
This study guide has been developed to accompany the "Seven Simple Secrets" book written by Dr. Todd Whitaker and Annette Breaux. "Seven Simple Secrets" focuses on those attributes that have been found to help teachers be their absolute best in their daily challenges of teaching and improving student learning. The study guide is divided into the…
Superconducting linear actuator
NASA Technical Reports Server (NTRS)
Johnson, Bruce; Hockney, Richard
1993-01-01
Special actuators are needed to control the orientation of large structures in space-based precision pointing systems. Electromagnetic actuators that presently exist are too large in size and their bandwidth is too low. Hydraulic fluid actuation also presents problems for many space-based applications. Hydraulic oil can escape in space and contaminate the environment around the spacecraft. A research study was performed that selected an electrically-powered linear actuator that can be used to control the orientation of a large pointed structure. This research surveyed available products, analyzed the capabilities of conventional linear actuators, and designed a first-cut candidate superconducting linear actuator. The study first examined theoretical capabilities of electrical actuators and determined their problems with respect to the application and then determined if any presently available actuators or any modifications to available actuator designs would meet the required performance. The best actuator was then selected based on available design, modified design, or new design for this application. The last task was to proceed with a conceptual design. No commercially-available linear actuator or modification capable of meeting the specifications was found. A conventional moving-coil dc linear actuator would meet the specification, but the back-iron for this actuator would weigh approximately 12,000 lbs. A superconducting field coil, however, eliminates the need for back iron, resulting in an actuator weight of approximately 1000 lbs.
NASA Technical Reports Server (NTRS)
Leviton, Douglas B. (Inventor)
1993-01-01
A Linear Motion Encoding device for measuring the linear motion of a moving object is disclosed in which a light source is mounted on the moving object and a position sensitive detector such as an array photodetector is mounted on a nearby stationary object. The light source emits a light beam directed towards the array photodetector such that a light spot is created on the array. An analog-to-digital converter, connected to the array photodetector is used for reading the position of the spot on the array photodetector. A microprocessor and memory is connected to the analog-to-digital converter to hold and manipulate data provided by the analog-to-digital converter on the position of the spot and to compute the linear displacement of the moving object based upon the data from the analog-to-digital converter.
Linearly Adjustable International Portfolios
NASA Astrophysics Data System (ADS)
Fonseca, R. J.; Kuhn, D.; Rustem, B.
2010-09-01
We present an approach to multi-stage international portfolio optimization based on the imposition of a linear structure on the recourse decisions. Multiperiod decision problems are traditionally formulated as stochastic programs. Scenario tree based solutions however can become intractable as the number of stages increases. By restricting the space of decision policies to linear rules, we obtain a conservative tractable approximation to the original problem. Local asset prices and foreign exchange rates are modelled separately, which allows for a direct measure of their impact on the final portfolio value.
Simple ocean carbon cycle models
Caldeira, K.; Hoffert, M.I.; Siegenthaler, U.
1994-02-01
Simple ocean carbon cycle models can be used to calculate the rate at which the oceans are likely to absorb CO{sub 2} from the atmosphere. For problems involving steady-state ocean circulation, well calibrated ocean models produce results that are very similar to results obtained using general circulation models. Hence, simple ocean carbon cycle models may be appropriate for use in studies in which the time or expense of running large scale general circulation models would be prohibitive. Simple ocean models have the advantage of being based on a small number of explicit assumptions. The simplicity of these ocean models facilitates the understanding of model results.
Reciprocating Linear Electric Motor
NASA Technical Reports Server (NTRS)
Goldowsky, M. P.
1984-01-01
Features include structural simplicity and good force/displacement characteristics. Reciprocating motor has simple, rugged construction, relatively low reciprocating weight, improved power delivery, and improved force control. Wear reduced by use of magnetic bearings. Intended to provide drivers for long-lived Stirling-cycle cryogenic refrigerators, concept has less exotic applications, such as fuel pumps.
Improved Electrohydraulic Linear Actuators
NASA Technical Reports Server (NTRS)
Hamtil, James
2004-01-01
A product line of improved electrohydraulic linear actuators has been developed. These actuators are designed especially for use in actuating valves in rocket-engine test facilities. They are also adaptable to many industrial uses, such as steam turbines, process control valves, dampers, motion control, etc. The advantageous features of the improved electrohydraulic linear actuators are best described with respect to shortcomings of prior electrohydraulic linear actuators that the improved ones are intended to supplant. The flow of hydraulic fluid to the two ports of the actuator cylinder is controlled by a servo valve that is controlled by a signal from a servo amplifier that, in turn, receives an analog position-command signal (a current having a value between 4 and 20 mA) from a supervisory control system of the facility. As the position command changes, the servo valve shifts, causing a greater flow of hydraulic fluid to one side of the cylinder and thereby causing the actuator piston to move to extend or retract a piston rod from the actuator body. A linear variable differential transformer (LVDT) directly linked to the piston provides a position-feedback signal, which is compared with the position-command signal in the servo amplifier. When the position-feedback and position-command signals match, the servo valve moves to its null position, in which it holds the actuator piston at a steady position.
Duck, F
2010-01-01
The propagation of acoustic waves is a fundamentally non-linear process, and only waves with infinitesimally small amplitudes may be described by linear expressions. In practice, all ultrasound propagation is associated with a progressive distortion in the acoustic waveform and the generation of frequency harmonics. At the frequencies and amplitudes used for medical diagnostic scanning, the waveform distortion can result in the formation of acoustic shocks, excess deposition of energy, and acoustic saturation. These effects occur most strongly when ultrasound propagates within liquids with comparatively low acoustic attenuation, such as water, amniotic fluid, or urine. Attenuation by soft tissues limits but does not extinguish these non-linear effects. Harmonics may be used to create tissue harmonic images. These offer improvements over conventional B-mode images in spatial resolution and, more significantly, in the suppression of acoustic clutter and side-lobe artefacts. The quantity B/A has promise as a parameter for tissue characterization, but methods for imaging B/A have shown only limited success. Standard methods for the prediction of tissue in-situ exposure from acoustic measurements in water, whether for regulatory purposes, for safety assessment, or for planning therapeutic regimes, may be in error because of unaccounted non-linear losses. Biological effects mechanisms are altered by finite-amplitude effects. PMID:20349813
NASA Technical Reports Server (NTRS)
Chandler, J. A. (Inventor)
1985-01-01
The linear motion valve is described. The valve spool employs magnetically permeable rings, spaced apart axially, which engage a sealing assembly having magnetically permeable pole pieces in magnetic relationship with a magnet. The gap between the ring and the pole pieces is sealed with a ferrofluid. Depletion of the ferrofluid is minimized.
ERIC Educational Resources Information Center
Dobbs, David E.
2013-01-01
A direct method is given for solving first-order linear recurrences with constant coefficients. The limiting value of that solution is studied as "n to infinity." This classroom note could serve as enrichment material for the typical introductory course on discrete mathematics that follows a calculus course.
Simple formulation of magnetoplasmadynamic acceleration
Sasoh, A. )
1994-03-01
A simple formulation of magnetoplasmadynamic acceleration has been made based on energy conservation relations and a generalized Ohm's law. An exhaust velocity is expressed using three characteristic parameters: (1) a dimensionless characteristic velocity [ital [tilde U
Simple Interval Timers for Microcomputers.
ERIC Educational Resources Information Center
McInerney, M.; Burgess, G.
1985-01-01
Discusses simple interval timers for microcomputers, including (1) the Jiffy clock; (2) CPU count timers; (3) screen count timers; (4) light pen timers; and (5) chip timers. Also examines some of the general characteristics of all types of timers. (JN)
Student Conceptions of Simple Circuits.
ERIC Educational Resources Information Center
Fredette, Norman; Lochhead, John
1980-01-01
Investigates some conceptual difficulties which college students have with regard to simple direct current circuits. The clinical interview technique was used with 57 students in a freshman level engineering course. (HM)
Simple device measures solar radiation
NASA Technical Reports Server (NTRS)
Humphries, W. R.
1977-01-01
Simple inexpensive thermometer, insolated from surroundings by transparent glass or plastic encasement, measures intensities of solar radiation, or radiation from other sources such as furnaces or ovens. Unit can be further modified to accomplish readings from remote locations.
Simple motor gestures for birdsongs.
Gardner, T; Cecchi, G; Magnasco, M; Laje, R; Mindlin, G B
2001-11-12
We present a model of sound production in a songbird's vocal organ and find that much of the complexity of the song of the canary (Serinus canaria) can be produced from simple time variations in forcing functions. The starts, stops, and pauses between syllables, as well as variation in pitch and timbre are inherent in the mechanics and can often be expressed through smooth and simple variations in the frequency and relative phase of two driving parameters
Simple motor gestures for birdsongs.
Gardner, T; Cecchi, G; Magnasco, M; Laje, R; Mindlin, G B
2001-11-12
We present a model of sound production in a songbird's vocal organ and find that much of the complexity of the song of the canary (Serinus canaria) can be produced from simple time variations in forcing functions. The starts, stops, and pauses between syllables, as well as variation in pitch and timbre are inherent in the mechanics and can often be expressed through smooth and simple variations in the frequency and relative phase of two driving parameters PMID:11690514
Simple Motor Gestures for Birdsongs
NASA Astrophysics Data System (ADS)
Gardner, Tim; Cecchi, G.; Magnasco, M.; Laje, R.; Mindlin, Gabriel B.
2001-11-01
We present a model of sound production in a songbird's vocal organ and find that much of the complexity of the song of the canary (Serinus canaria) can be produced from simple time variations in forcing functions. The starts, stops, and pauses between syllables, as well as variation in pitch and timbre are inherent in the mechanics and can often be expressed through smooth and simple variations in the frequency and relative phase of two driving parameters
Transmembrane helix: simple or complex.
Wong, Wing-Cheong; Maurer-Stroh, Sebastian; Schneider, Georg; Eisenhaber, Frank
2012-07-01
Transmembrane helical segments (TMs) can be classified into two groups of so-called 'simple' and 'complex' TMs. Whereas the first group represents mere hydrophobic anchors with an overrepresentation of aliphatic hydrophobic residues that are likely attributed to convergent evolution in many cases, the complex ones embody ancestral information and tend to have structural and functional roles beyond just membrane immersion. Hence, the sequence homology concept is not applicable on simple TMs. In practice, these simple TMs can attract statistically significant but evolutionarily unrelated hits during similarity searches (whether through BLAST- or HMM-based approaches). This is especially problematic for membrane proteins that contain both globular segments and TMs. As such, we have developed the transmembrane helix: simple or complex (TMSOC) webserver for the identification of simple and complex TMs. By masking simple TM segments in seed sequences prior to sequence similarity searches, the false-discovery rate decreases without sacrificing sensitivity. Therefore, TMSOC is a novel and necessary sequence analytic tool for both the experimentalists and the computational biology community working on membrane proteins. It is freely accessible at http://tmsoc.bii.a-star.edu.sg or available for download.
Genealogies in simple models of evolution
NASA Astrophysics Data System (ADS)
Brunet, Éric; Derrida, Bernard
2013-01-01
We review the statistical properties of the genealogies of a few models of evolution. In the asexual case, selection leads to coalescence times which grow logarithmically with the size of the population, in contrast with the linear growth of the neutral case. Moreover for a whole class of models, the statistics of the genealogies are those of the Bolthausen-Sznitman coalescent rather than the Kingman coalescent in the neutral case. For sexual reproduction in the neutral case, the time to reach the first common ancestors for the whole population and the time for all individuals to have all their ancestors in common are also logarithmic in the population size, as predicted by Chang in 1999. We discuss how these times are modified by introducing selection in a simple way.
Linear Time Vertex Partitioning on Massive Graphs
Mell, Peter; Harang, Richard; Gueye, Assane
2016-01-01
The problem of optimally removing a set of vertices from a graph to minimize the size of the largest resultant component is known to be NP-complete. Prior work has provided near optimal heuristics with a high time complexity that function on up to hundreds of nodes and less optimal but faster techniques that function on up to thousands of nodes. In this work, we analyze how to perform vertex partitioning on massive graphs of tens of millions of nodes. We use a previously known and very simple heuristic technique: iteratively removing the node of largest degree and all of its edges. This approach has an apparent quadratic complexity since, upon removal of a node and adjoining set of edges, the node degree calculations must be updated prior to choosing the next node. However, we describe a linear time complexity solution using an array whose indices map to node degree and whose values are hash tables indicating the presence or absence of a node at that degree value. This approach also has a linear growth with respect to memory usage which is surprising since we lowered the time complexity from quadratic to linear. We empirically demonstrate linear scalability and linear memory usage on random graphs of up to 15000 nodes. We then demonstrate tractability on massive graphs through execution on a graph with 34 million nodes representing Internet wide router connectivity. PMID:27336059
A feedback linearization approach to orbital maneuvers
NASA Astrophysics Data System (ADS)
Lee, Sanguk
New methods for obtaining optimal orbital maneuvers of a space vehicle in total velocity change are described and applied. The elegance of Lambert's Theorem is combined with feedback linearization and linear optimal control to obtain solutions to nonlinear orbital maneuver problems. In particular, geocentric orbital maneuvers with finite-thrust acceleration are studied. The full nonlinear equations of motion are transformed exactly into a controllable linear set in Brunovsky canonical form by using feedback linearization and choosing the position vector as the fully observable output vector. These equations are used to pose a linear optimal tracking problem with a solution to the Lambert's impulsive-thrust two-point boundary-value problem as the reference orbit. The same procedure is used to force the space vehicle to follow a linear analytical solution to the continuous low-thrust orbital maneuver problem between neighboring orbits. Limits on thrust magnitudes are enforced by adjusting the weights on the states in the performance index, which is chosen to be the sum of integrals of the square sum of new control variables and the square sum of state variable errors from the reference trajectory. For comparison purpose, the feedback linearized equations are used to obtain a simple closed-form solution to an orbital maneuver problem without the use of a reference trajectory. In this case, the performance index was chosen as the integral of the square sum of new control variables only. Three different examples, coplanar rendezvous between neighboring orbits, large coplanar orbit transfer, and non-coplanar orbit transfer, are used to show the advantages of using the new methods introduced in this dissertation. The minimum-eccentricity orbit, Hohmann transfer orbit, and minimum energy orbit were used in turn as the reference trajectories. The principal problems encountered in using the new methods are the choices of the proper reference trajectory, a suitable time
NASA Technical Reports Server (NTRS)
Goldowsky, Michael P. (Inventor)
1987-01-01
A reciprocating linear motor is formed with a pair of ring-shaped permanent magnets having opposite radial polarizations, held axially apart by a nonmagnetic yoke, which serves as an axially displaceable armature assembly. A pair of annularly wound coils having axial lengths which differ from the axial lengths of the permanent magnets are serially coupled together in mutual opposition and positioned with an outer cylindrical core in axial symmetry about the armature assembly. One embodiment includes a second pair of annularly wound coils serially coupled together in mutual opposition and an inner cylindrical core positioned in axial symmetry inside the armature radially opposite to the first pair of coils. Application of a potential difference across a serial connection of the two pairs of coils creates a current flow perpendicular to the magnetic field created by the armature magnets, thereby causing limited linear displacement of the magnets relative to the coils.
General linear chirplet transform
NASA Astrophysics Data System (ADS)
Yu, Gang; Zhou, Yiqi
2016-03-01
Time-frequency (TF) analysis (TFA) method is an effective tool to characterize the time-varying feature of a signal, which has drawn many attentions in a fairly long period. With the development of TFA, many advanced methods are proposed, which can provide more precise TF results. However, some restrictions are introduced inevitably. In this paper, we introduce a novel TFA method, termed as general linear chirplet transform (GLCT), which can overcome some limitations existed in current TFA methods. In numerical and experimental validations, by comparing with current TFA methods, some advantages of GLCT are demonstrated, which consist of well-characterizing the signal of multi-component with distinct non-linear features, being independent to the mathematical model and initial TFA method, allowing for the reconstruction of the interested component, and being non-sensitivity to noise.
Dense simple plasmas as high-temperature liquid simple metals
NASA Technical Reports Server (NTRS)
Perrot, F.
1990-01-01
The thermodynamic properties of dense plasmas considered as high-temperature liquid metals are studied. An attempt is made to show that the neutral pseudoatom picture of liquid simple metals may be extended for describing plasmas in ranges of densities and temperatures where their electronic structure remains 'simple'. The primary features of the model when applied to plasmas include the temperature-dependent self-consistent calculation of the electron charge density and the determination of a density and temperature-dependent ionization state.
NASA Technical Reports Server (NTRS)
Collins, Earl R., Jr.; Curry, Kenneth C.
1990-01-01
Electrically charged helices attract or repel each other. Proposed electrostatic linear actuator made with intertwined dual helices, which holds charge-bearing surfaces. Dual-helix configuration provides relatively large unbroken facing charged surfaces (relatively large electrostatic force) within small volume. Inner helix slides axially in outer helix in response to voltages applied to conductors. Spiral form also makes components more rigid. Actuator conceived to have few moving parts and to be operable after long intervals of inactivity.
Buttram, M.T.; Ginn, J.W.
1988-06-21
A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities. 4 figs.
Relativistic Linear Restoring Force
ERIC Educational Resources Information Center
Clark, D.; Franklin, J.; Mann, N.
2012-01-01
We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…
Combustion powered linear actuator
Fischer, Gary J.
2007-09-04
The present invention provides robotic vehicles having wheeled and hopping mobilities that are capable of traversing (e.g. by hopping over) obstacles that are large in size relative to the robot and, are capable of operation in unpredictable terrain over long range. The present invention further provides combustion powered linear actuators, which can include latching mechanisms to facilitate pressurized fueling of the actuators, as can be used to provide wheeled vehicles with a hopping mobility.
Representation of linear orders.
Taylor, D A; Kim, J O; Sudevan, P
1984-01-01
Two binary classification tasks were used to explore the associative structure of linear orders. In Experiment 1, college students classified English letters as targets or nontargets, the targets being consecutive letters of the alphabet. The time to reject nontargets was a decreasing function of the distance from the target set, suggesting response interference mediated by automatic associations from the target to the nontarget letters. The way in which this interference effect depended on the placement of the boundaries between the target and nontarget sets revealed the relative strengths of individual interletter associations. In Experiment 2, students were assigned novel linear orders composed of letterlike symbols and asked to classify pairs of symbols as being adjacent or nonadjacent in the assigned sequence. Reaction time was found to be a joint function of the distance between any pair of symbols and the relative positions of those symbols within the sequence. The effects of both distance and position decreased systematically over 6 days of practice with a particular order, beginning at a level typical of unfamiliar orders and converging on a level characteristic of familiar orders such as letters and digits. These results provide an empirical unification of two previously disparate sets of findings in the literature on linear orders, those concerning familiar and unfamiliar orders, and the systematic transition between the two patterns of results suggests the gradual integration of a new associative structure.
NASA Astrophysics Data System (ADS)
Uhlmann, Armin
2016-03-01
This is an introduction to antilinear operators. In following Wigner the terminus antilinear is used as it is standard in Physics. Mathematicians prefer to say conjugate linear. By restricting to finite-dimensional complex-linear spaces, the exposition becomes elementary in the functional analytic sense. Nevertheless it shows the amazing differences to the linear case. Basics of antilinearity is explained in sects. 2, 3, 4, 7 and in sect. 1.2: Spectrum, canonical Hermitian form, antilinear rank one and two operators, the Hermitian adjoint, classification of antilinear normal operators, (skew) conjugations, involutions, and acq-lines, the antilinear counterparts of 1-parameter operator groups. Applications include the representation of the Lagrangian Grassmannian by conjugations, its covering by acq-lines. As well as results on equivalence relations. After remembering elementary Tomita-Takesaki theory, antilinear maps, associated to a vector of a two-partite quantum system, are defined. By allowing to write modular objects as twisted products of pairs of them, they open some new ways to express EPR and teleportation tasks. The appendix presents a look onto the rich structure of antilinear operator spaces.
Linearized Kernel Dictionary Learning
NASA Astrophysics Data System (ADS)
Golts, Alona; Elad, Michael
2016-06-01
In this paper we present a new approach of incorporating kernels into dictionary learning. The kernel K-SVD algorithm (KKSVD), which has been introduced recently, shows an improvement in classification performance, with relation to its linear counterpart K-SVD. However, this algorithm requires the storage and handling of a very large kernel matrix, which leads to high computational cost, while also limiting its use to setups with small number of training examples. We address these problems by combining two ideas: first we approximate the kernel matrix using a cleverly sampled subset of its columns using the Nystr\\"{o}m method; secondly, as we wish to avoid using this matrix altogether, we decompose it by SVD to form new "virtual samples," on which any linear dictionary learning can be employed. Our method, termed "Linearized Kernel Dictionary Learning" (LKDL) can be seamlessly applied as a pre-processing stage on top of any efficient off-the-shelf dictionary learning scheme, effectively "kernelizing" it. We demonstrate the effectiveness of our method on several tasks of both supervised and unsupervised classification and show the efficiency of the proposed scheme, its easy integration and performance boosting properties.
Rees, J.R.
1989-10-01
April, 1989, the first Z zero particle was observed at the Stanford Linear Collider (SLC). The SLC collides high-energy beams of electrons and positrons into each other. In break with tradition the SLC aims two linear beams at each other. Strong motives impelled the Stanford team to choose the route of innovation. One reason being that linear colliders promise to be less expensive to build and operate than storage ring colliders. An equally powerful motive was the desire to build an Z zero factory, a facility at which the Z zero particle can be studied in detail. More than 200 Z zero particles have been detected at the SLC and more continue to be churned out regularly. It is in measuring the properties of the Z zero that the SLC has a seminal contribution to make. One of the primary goals of the SLC experimental program is to determine the mass of the Z zero as precisely as possible.In the end, the SLC's greatest significance will be in having proved a new accelerator technology. 7 figs.
Some simple properties of stellar pulsation modes
NASA Technical Reports Server (NTRS)
Wolff, C. L.
1979-01-01
Except for the lowest harmonics, small-amplitude stellar pulsation modes possess many simple properties whose evaluation does not require numerical integration of the fourth-order equations of motion. All antinodes tend to have the same total kinetic energy except for those lying near physical or geometric boundaries. However, when kinetic energy per unit volume is considered, order-of-magnitude enhancements are seen in antinodes lying near the center of the star, and factor-of-2 enhancements occur near the polar axis. The nodes are distributed very regularly along the radius. They follow an exponential law in g-regions, and their separation is proportional to the sound travel time in p-regions. A simple graphical procedure is described for surveying the oscillation frequencies of a new stellar model. A precise condition is derived giving the division of energy between radial and angular motion. Another condition gives the fractional contribution to the velocity field of its two sources, the divergence and the curl. Certain simplifying results of weak coupling among the linear modes are briefly described.
Applied Electronics: Construction of a Simple Spectrophotometer
NASA Astrophysics Data System (ADS)
Thal, Melissa A.; Samide, Michael J.
2001-11-01
In this paper we describe the construction of a simple spectrophotometer intended for use as a capstone circuit for an electronics laboratory exercise. Students in the undergraduate laboratory have learned basic circuitry and are now able to read a schematic and construct an instrument that has practical applications in chemical analysis. A simple LED is used as the source and is easily changed to correspond to different species being studied. Detection is accomplished through the use of one of three signal transducers (a photoresistor, a photodiode, or a photodarlington) and a current-to-voltage converter. A box lined with black felt is used to shield the spectrophotometer from ambient light. This spectrophotometer shows excellent Beer-Lambert law linearity over a large concentration range and has been used in the laboratory to determine the concentration of a metal cation in solution on the basis of a calibration curve. Of the transducers used, the photoresistor showed the best response at multiple wavelengths with error in concentration determination not greater than 6%. Through the building and testing of this circuit, the students can visualize applications of electronic circuitry.
Simple models for reading neuronal population codes.
Seung, H S; Sompolinsky, H
1993-01-01
In many neural systems, sensory information is distributed throughout a population of neurons. We study simple neural network models for extracting this information. The inputs to the networks are the stochastic responses of a population of sensory neurons tuned to directional stimuli. The performance of each network model in psychophysical tasks is compared with that of the optimal maximum likelihood procedure. As a model of direction estimation in two dimensions, we consider a linear network that computes a population vector. Its performance depends on the width of the population tuning curves and is maximal for width, which increases with the level of background activity. Although for narrowly tuned neurons the performance of the population vector is significantly inferior to that of maximum likelihood estimation, the difference between the two is small when the tuning is broad. For direction discrimination, we consider two models: a perceptron with fully adaptive weights and a network made by adding an adaptive second layer to the population vector network. We calculate the error rates of these networks after exhaustive training to a particular direction. By testing on the full range of possible directions, the extent of transfer of training to novel stimuli can be calculated. It is found that for threshold linear networks the transfer of perceptual learning is nonmonotonic. Although performance deteriorates away from the training stimulus, it peaks again at an intermediate angle. This nonmonotonicity provides an important psychophysical test of these models. PMID:8248166
A SIMPLE MODEL FOR QUASAR DEMOGRAPHICS
Conroy, Charlie; White, Martin
2013-01-10
We present a simple model for the relationship between quasars, galaxies, and dark matter halos from 0.5 < z < 6. In the model, black hole (BH) mass is linearly related to galaxy mass, and galaxies are connected to dark matter halos via empirically constrained relations. A simple 'scattered' light bulb model for quasars is adopted, wherein BHs shine at a fixed fraction of the Eddington luminosity during accretion episodes, and Eddington ratios are drawn from a lognormal distribution that is redshift independent. This model has two free, physically meaningful parameters at each redshift: the normalization of the M {sub BH}-M {sub gal} relation and the quasar duty cycle; these parameters are fit to the observed quasar luminosity function (LF) over the interval 0.5 < z < 6. This simple model provides an excellent fit to the LF at all epochs and also successfully predicts the observed projected two-point correlation of quasars from 0.5 < z < 2.5. It is significant that a single quasar duty cycle at each redshift is capable of reproducing the extant observations. The data are therefore consistent with a scenario wherein quasars are equally likely to exist in galaxies, and therefore dark matter halos, over a wide range in masses. The knee in the quasar LF is a reflection of the knee in the stellar-mass-halo-mass relation. Future constraints on the quasar LF and quasar clustering at high redshift will provide strong constraints on the model. In the model, the autocorrelation function of quasars becomes a strong function of luminosity only at the very highest luminosities and will be difficult to observe because such quasars are so rare. Cross-correlation techniques may provide useful constraints on the bias of such rare objects. The simplicity of the model allows for rapid generation of quasar mock catalogs from N-body simulations that match the observed LF and clustering to high redshift.
Is the Simple View of Reading Too Simple?
ERIC Educational Resources Information Center
Hoien-Tengesdal, Ingjerd
2010-01-01
According to the Simple View of Reading (SVR), reading comprehension is the product of word decoding ability and linguistic comprehension (R = D x C). However, there is also evidence showing that an additive model (R = D + C) explains just as much or even more of the variance in reading comprehension than the product model. To further evaluate…
Futur "simple" et futur "proche" ("Simple" Future and "Immediate" Future).
ERIC Educational Resources Information Center
Franckel, Jean-Jacques
1984-01-01
An analysis of the use of simple and immediate future tenses in French shows that the expression of time is controlled more by context and modals than by specifically temporal cues. The role of negation in this situation is discussed. (MSE)
How Simple is the Simple View of Reading?
ERIC Educational Resources Information Center
Gustafson, Stefan; Samuelsson, Christina; Johansson, Ellinor; Wallmann, Julia
2013-01-01
According to the Simple View of Reading, reading ability can be divided into decoding and language comprehension. In the present study, decoding and comprehension's contribution to reading ability was studied both in children with reading difficulties and in children with typical reading ability. Decoding and comprehension was further divided…
Complex Autocatalysis in Simple Chemistries.
Virgo, Nathaniel; Ikegami, Takashi; McGregor, Simon
2016-01-01
Life on Earth must originally have arisen from abiotic chemistry. Since the details of this chemistry are unknown, we wish to understand, in general, which types of chemistry can lead to complex, lifelike behavior. Here we show that even very simple chemistries in the thermodynamically reversible regime can self-organize to form complex autocatalytic cycles, with the catalytic effects emerging from the network structure. We demonstrate this with a very simple but thermodynamically reasonable artificial chemistry model. By suppressing the direct reaction from reactants to products, we obtain the simplest kind of autocatalytic cycle, resulting in exponential growth. When these simple first-order cycles are prevented from forming, the system achieves superexponential growth through more complex, higher-order autocatalytic cycles. This leads to nonlinear phenomena such as oscillations and bistability, the latter of which is of particular interest regarding the origins of life.
A simple hindlimb suspension apparatus
NASA Technical Reports Server (NTRS)
Park, E.; Schultz, E.
1993-01-01
This paper describes the assembly of a simple, inexpensive apparatus for application of the hindlimb suspension model to studies of the effects of unloading on mammalian physiology. Construction of a cage and suspension assembly is described using materials that can be obtained from most hardware stores. The design is kept simple for easy assembly and disassembly to facilitate cleaning and storage. The suspension assembly allows the animals full access to all portions of the floor area and provides an effective environment to study the effects of unloading.
A Simple and Fast Spline Filtering Algorithm for Surface Metrology
Zhang, Hao; Ott, Daniel; Song, John; Tong, Mingsi; Chu, Wei
2015-01-01
Spline filters and their corresponding robust filters are commonly used filters recommended in ISO (the International Organization for Standardization) standards for surface evaluation. Generally, these linear and non-linear spline filters, composed of symmetric, positive-definite matrices, are solved in an iterative fashion based on a Cholesky decomposition. They have been demonstrated to be relatively efficient, but complicated and inconvenient to implement. A new spline-filter algorithm is proposed by means of the discrete cosine transform or the discrete Fourier transform. The algorithm is conceptually simple and very convenient to implement. PMID:26958443
Sparse linear programming subprogram
Hanson, R.J.; Hiebert, K.L.
1981-12-01
This report describes a subprogram, SPLP(), for solving linear programming problems. The package of subprogram units comprising SPLP() is written in Fortran 77. The subprogram SPLP() is intended for problems involving at most a few thousand constraints and variables. The subprograms are written to take advantage of sparsity in the constraint matrix. A very general problem statement is accepted by SPLP(). It allows upper, lower, or no bounds on the variables. Both the primal and dual solutions are returned as output parameters. The package has many optional features. Among them is the ability to save partial results and then use them to continue the computation at a later time.
Ultrasonic linear measurement system
NASA Technical Reports Server (NTRS)
Marshall, Scot H. (Inventor)
1991-01-01
An ultrasonic linear measurement system uses the travel time of surface waves along the perimeter of a three-dimensional curvilinear body to determine the perimeter of the curvilinear body. The system can also be used piece-wise to measure distances along plane surfaces. The system can be used to measure perimeters where use of laser light, optical means or steel tape would be extremely difficult, time consuming or impossible. It can also be used to determine discontinuities in surfaces of known perimeter or dimension.
[Congenital linear nevus sebaceus].
Linnemann, Anders; Bygum, Anette; Fenger-Grøn, Jesper
2011-09-01
An unusual case of nevus sebaceous is described. Nevus sebaceous is a congenital epidermal hamartoma of the skin and the predilection site is the head or neck. In this case the nevus followed the lines of Blaschko along the back of the left lower extremity. The linear lesion seemed papulovesicular which caused suspicion of incontinentia pigmenti or infection, and the boy received antimicrobial treatment until a biopsy revealed the correct diagnosis. We wish to emphasize this clinical picture to spare the patient and relatives from unnecessary tests, treatment and concern. PMID:21893006
NASA Technical Reports Server (NTRS)
Perkins, Gerald S. (Inventor)
1980-01-01
A linear actuator which can apply high forces is described, which includes a reciprocating rod having a threaded portion engaged by a nut that is directly coupled to the rotor of an electric motor. The nut is connected to the rotor in a manner that minimizes loading on the rotor, by the use of a coupling that transmits torque to the nut but permits it to shift axially and radially with respect to the rotor. The nut has a threaded hydrostatic bearing for engaging the threaded rod portion, with an oilcarrying groove in the nut being interrupted.
A Simple Demonstration of Atomic and Molecular Orbitals Using Circular Magnets
ERIC Educational Resources Information Center
Chakraborty, Maharudra; Mukhopadhyay, Subrata; Das, Ranendu Sekhar
2014-01-01
A quite simple and inexpensive technique is described here to represent the approximate shapes of atomic orbitals and the molecular orbitals formed by them following the principles of the linear combination of atomic orbitals (LCAO) method. Molecular orbitals of a few simple molecules can also be pictorially represented. Instructors can employ the…
Nonlinear Modeling by Assembling Piecewise Linear Models
NASA Technical Reports Server (NTRS)
Yao, Weigang; Liou, Meng-Sing
2013-01-01
To preserve nonlinearity of a full order system over a parameters range of interest, we propose a simple modeling approach by assembling a set of piecewise local solutions, including the first-order Taylor series terms expanded about some sampling states. The work by Rewienski and White inspired our use of piecewise linear local solutions. The assembly of these local approximations is accomplished by assigning nonlinear weights, through radial basis functions in this study. The efficacy of the proposed procedure is validated for a two-dimensional airfoil moving at different Mach numbers and pitching motions, under which the flow exhibits prominent nonlinear behaviors. All results confirm that our nonlinear model is accurate and stable for predicting not only aerodynamic forces but also detailed flowfields. Moreover, the model is robustness-accurate for inputs considerably different from the base trajectory in form and magnitude. This modeling preserves nonlinearity of the problems considered in a rather simple and accurate manner.
Construction of a Simple Respirometer.
ERIC Educational Resources Information Center
Taboga, Leandro
1979-01-01
Instructions for making a simple respirometer, to measure rates of oxygen consumption of organisms, are presented. The instrument incorporates most of the basic elements of commercial respirometers but can be made inexpensively by high school students. Operating instructions and applications are given. (Author/SA)
Simple models of turbulent flowsa)
NASA Astrophysics Data System (ADS)
Pope, Stephen B.
2011-01-01
Stochastic Lagrangian models provide a simple and direct way to model turbulent flows and the processes that occur within them. This paper provides an introduction to this approach, aimed at the nonspecialist, and providing some historical perspective. Basic models for the Lagrangian velocity (i.e., the Langevin equation) and composition are described and applied to the simple but revealing case of dispersion from a line source in grid turbulence. With simple extensions, these models are applied to inhomogeneous turbulent reactive flows, where they form the core of probability density function (PDF) methods. The use of PDF methods is illustrated for the case of a lifted turbulent jet flame. Lagrangian time series are now accessible both from experiments and from direct numerical simulations, and this information is used to scrutinize and improve stochastic Lagrangian models. In particular, we describe refinements to account for the observed strong Reynolds-number effects including intermittency. It is emphasized that all models of turbulence are necessarily approximate and incomplete, and that simple models are valuable in many applications in spite of their limitations.
Simple Machines in the Community
ERIC Educational Resources Information Center
Bryan, Robert; Laroder, Aris; Tippins, Deborah; Emaz, Meliza; Fox, Ryan
2008-01-01
The community can be a powerful context and mini-laboratory for cultivating students' common understandings of science and mathematics. On the island of Panay in the Philippines, the community was the starting place for a group of fifth- and sixth-grade students to explore simple machines in their daily lives. What students learned in the process…
A Simple Plant Growth Analysis.
ERIC Educational Resources Information Center
Oxlade, E.
1985-01-01
Describes the analysis of dandelion peduncle growth based on peduncle length, epidermal cell dimensions, and fresh/dry mass. Methods are simple and require no special apparatus or materials. Suggests that limited practical work in this area may contribute to students' lack of knowledge on plant growth. (Author/DH)
A Simple Relativistic Bohr Atom
ERIC Educational Resources Information Center
Terzis, Andreas F.
2008-01-01
A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…
Simple Games . . . or Are They?
ERIC Educational Resources Information Center
Arn, Susan Kyle
2006-01-01
Students today begin using computers and playing video games as early as two years old. The technology behind these games is more complicated than most people can imagine. In this article, the author presents some simple number games which seem easy at the beginning, but as the games are repeated, mathematical content becomes more of the focus…
Correcting Slightly Less Simple Movements
ERIC Educational Resources Information Center
Aivar, M. P.; Brenner, E.; Smeets, J. B. J.
2005-01-01
Many studies have analysed how goal directed movements are corrected in response to changes in the properties of the target. However, only simple movements to single targets have been used in those studies, so little is known about movement corrections under more complex situations. Evidence from studies that ask for movements to several targets…
A Simple Audio Conductivity Device.
ERIC Educational Resources Information Center
Berenato, Gregory; Maynard, David F.
1997-01-01
Describes a simple audio conductivity device built to address the problem of the lack of sensitivity needed to measure small differences in conductivity in crude conductivity devices. Uses a 9-V battery as a power supply and allows the relative resistance differences between substances to be detected by the frequency of its audible tones. Presents…
Simple Machines Curriculum. [Teachers' Manual.
ERIC Educational Resources Information Center
Anoka-Hennepin Independent School District No. 11, Coon Rapids, MN.
This manual provides suggestions for investigating simple machines and the teaching of certain basic concepts which pertain to them. Many of the lessons are designed to be used with the commercially available LEGO kits, in an effort to teach concepts in a way in which students must translate pictures shown in two dimension into three-dimensional…
Solving Simple Kinetics without Integrals
ERIC Educational Resources Information Center
de la Pen~a, Lisandro Herna´ndez
2016-01-01
The solution of simple kinetic equations is analyzed without referencing any topic from differential equations or integral calculus. Guided by the physical meaning of the rate equation, a systematic procedure is used to generate an approximate solution that converges uniformly to the exact solution in the case of zero, first, and second order…
Simple stringy dynamical supersymmetry breaking
Aharony, Ofer; Kachru, Shamit; Silverstein, Eva
2007-12-15
We present simple string models which dynamically break supersymmetry without non-Abelian gauge dynamics. The Fayet model, the Polonyi model, and the O'Raifeartaigh model each arise from D-branes at a specific type of singularity. D-brane instanton effects generate the requisite exponentially small scale of supersymmetry breaking.
Simple Stringy Dynamical SUSY Breaking
Aharony, Ofer; Kachru, Shamit; Silverstein, Eva; /Stanford U., Phys. Dept. /SLAC
2007-08-08
We present simple string models which dynamically break supersymmetry without non-Abelian gauge dynamics. The Fayet model, the Polonyi model, and the O'Raifeartaigh model each arise from D-branes at a specific type of singularity. D-brane instanton effects generate the requisite exponentially small scale of supersymmetry breaking.
Determining Salinity by Simple Means.
ERIC Educational Resources Information Center
Schlenker, Richard M.
This paper describes the construction and use of a simple salinometer. The salinometer is composed, mainly, of a milliammeter and a battery and uses the measurement of current flow to determine the salinity of water. A complete list of materials is given, as are details of construction and operation of the equipment. The use of the salinometer in…
The Stark effect in linear potentials
NASA Astrophysics Data System (ADS)
Robinett, R. W.
2010-01-01
We examine the Stark effect (the second-order shifts in the energy spectrum due to an external constant force) for two one-dimensional model quantum mechanical systems described by linear potentials, the so-called quantum bouncer (defined by V(z) = Fz for z > 0 and V(z) = ∞ for z < 0) and the symmetric linear potential (given by V(z) = F|z|). We show how straightforward use of the most obvious properties of the Airy function solutions and simple Taylor expansions gives closed form results for the Stark shifts in both systems. These exact results are then compared to other approximation techniques, such as perturbation theory and WKB methods. These expressions add to the small number of closed-form descriptions available for the Stark effect in model quantum mechanical systems.
Mutual inductance between piecewise-linear loops
NASA Astrophysics Data System (ADS)
Cristina Barroso, Ana; Silva, J. P.
2013-11-01
We consider a current-carrying wire loop made out of linear segments of arbitrary sizes and directions in three-dimensional space. We develop expressions to calculate its vector potential and magnetic field at all points in space. We then calculate the mutual inductance between two such (non-intersecting) piecewise-linear loops. As simple applications, we consider in detail the mutual inductance between two square wires of equal length that either lie in the same plane or lie in parallel horizontal planes with their centers on the same vertical axis. Our expressions can also be used to obtain approximations to the mutual inductance between wires of arbitrary three-dimensional shapes.
Linear control of the flywheel inverted pendulum.
Olivares, Manuel; Albertos, Pedro
2014-09-01
The flywheel inverted pendulum is an underactuated mechanical system with a nonlinear model but admitting a linear approximation around the unstable equilibrium point in the upper position. Although underactuated systems usually require nonlinear controllers, the easy tuning and understanding of linear controllers make them more attractive for designers and final users. In a recent paper, a simple PID controller was proposed by the authors, leading to an internally unstable controlled plant. To achieve global stability, two options are developed here: first by introducing an internal stabilizing controller and second by replacing the PID controller by an observer-based state feedback control. Simulation and experimental results show the effectiveness of the design. PMID:24480638
Directionality switchable gain stabilized linear repeater
NASA Astrophysics Data System (ADS)
Ota, Takayuki; Ohmachi, Tadashi; Aida, Kazuo
2004-10-01
We propose a new approach to realize a bidirectional linear repeater suitable for future optical internet networks and fault location in repeater chain with OTDR. The proposed approach is the linear repeater of simple configuration whose directionality is rearranged dynamically by electrical control signal. The repeater is composed of a magneto-optical switch, a circulator, a dynamically gain stabilized unidirectional EDFA, and control circuits. The repeater directionality is rearranged as fast as 0.1ms by an electrical control pulse. It is experimentally confirmed that OTDR with the directionality switchable repeater is feasible for repeater chain. The detailed design and performance of the repeater are also discussed, including the multi-pass interference (MPI) which may arise in the proposed repeater, the effect of the MPI on SNR degradation of the repeater chain and the feed-forward EDFA gain control circuit.
Next linear collider test accelerator injector upgrade
Yeremian, A.D.; Miller, R.H.
1995-12-31
The Next Linear Collider Test Accelerator (NLCTA) is being constructed at SLAC to demonstrate multibunch beam loading compensation, suppression of higher order deflecting modes and measure transverse components of the accelerating fields in X-band accelerating structures. Currently a simple injector which provides the average current necessary for the beam loading compensations studies is under construction. An injector upgrade is planned to produce bunch trains similar to that of the NLC with microbunch intensity, separation and energy spread, identical to that of NLC. We discuss the design of the NLCTA injector upgrade.
Experimental quantum private queries with linear optics
De Martini, Francesco; Giovannetti, Vittorio; Lloyd, Seth; Maccone, Lorenzo; Nagali, Eleonora; Sansoni, Linda; Sciarrino, Fabio
2009-07-15
The quantum private query is a quantum cryptographic protocol to recover information from a database, preserving both user and data privacy: the user can test whether someone has retained information on which query was asked and the database provider can test the amount of information released. Here we discuss a variant of the quantum private query algorithm that admits a simple linear optical implementation: it employs the photon's momentum (or time slot) as address qubits and its polarization as bus qubit. A proof-of-principle experimental realization is implemented.
Linear and nonlinear oscilations in Classical Mechanics
NASA Astrophysics Data System (ADS)
Cruz, Enrique; Martinez, Juan L.; Camacho, Edgar
1997-04-01
The theory of small oscilations is very important in many areas of physics and others sciences due to the simple form of the equations and the easy interpretetion of the results. In this work we show three examples of mechanical systems and using the Lagrangian formulation, we study the linear regime making approaches to the Lagrange's equations, and for the analysis of the nonlinear behavior of the systems we use the Hamiltonian formulation, we use the program MATHEMATICA for the whole analysis. MATHEMATICA is useful because many students can approach to the analysis and simulations using modern tools like the simbolic and numerical computacional packages.
NASA Astrophysics Data System (ADS)
Birx, Daniel
1992-03-01
Among the family of particle accelerators, the Induction Linear Accelerator is the best suited for the acceleration of high current electron beams. Because the electromagnetic radiation used to accelerate the electron beam is not stored in the cavities but is supplied by transmission lines during the beam pulse it is possible to utilize very low Q (typically<10) structures and very large beam pipes. This combination increases the beam breakup limited maximum currents to of order kiloamperes. The micropulse lengths of these machines are measured in 10's of nanoseconds and duty factors as high as 10-4 have been achieved. Until recently the major problem with these machines has been associated with the pulse power drive. Beam currents of kiloamperes and accelerating potentials of megavolts require peak power drives of gigawatts since no energy is stored in the structure. The marriage of liner accelerator technology and nonlinear magnetic compressors has produced some unique capabilities. It now appears possible to produce electron beams with average currents measured in amperes, peak currents in kiloamperes and gradients exceeding 1 MeV/meter, with power efficiencies approaching 50%. The nonlinear magnetic compression technology has replaced the spark gap drivers used on earlier accelerators with state-of-the-art all-solid-state SCR commutated compression chains. The reliability of these machines is now approaching 1010 shot MTBF. In the following paper we will briefly review the historical development of induction linear accelerators and then discuss the design considerations.
Pseudo Linear Gyro Calibration
NASA Technical Reports Server (NTRS)
Harman, Richard; Bar-Itzhack, Itzhack Y.
2003-01-01
Previous high fidelity onboard attitude algorithms estimated only the spacecraft attitude and gyro bias. The desire to promote spacecraft and ground autonomy and improvements in onboard computing power has spurred development of more sophisticated calibration algorithms. Namely, there is a desire to provide for sensor calibration through calibration parameter estimation onboard the spacecraft as well as autonomous estimation on the ground. Gyro calibration is a particularly challenging area of research. There are a variety of gyro devices available for any prospective mission ranging from inexpensive low fidelity gyros with potentially unstable scale factors to much more expensive extremely stable high fidelity units. Much research has been devoted to designing dedicated estimators such as particular Extended Kalman Filter (EKF) algorithms or Square Root Information Filters. This paper builds upon previous attitude, rate, and specialized gyro parameter estimation work performed with Pseudo Linear Kalman Filter (PSELIKA). The PSELIKA advantage is the use of the standard linear Kalman Filter algorithm. A PSELIKA algorithm for an orthogonal gyro set which includes estimates of attitude, rate, gyro misalignments, gyro scale factors, and gyro bias is developed and tested using simulated and flight data. The measurements PSELIKA uses include gyro and quaternion tracker data.
Simple Indolizidine and Quinolizidine Alkaloids.
Michael, Joseph P
2016-01-01
This review of simple indolizidine and quinolizidine alkaloids (i.e., those in which the parent bicyclic systems are in general not embedded in polycyclic arrays) is an update of the previous coverage in Volume 55 of this series (2001). The present survey covers the literature from mid-1999 to the end of 2013; and in addition to aspects of the isolation, characterization, and biological activity of the alkaloids, much emphasis is placed on their total synthesis. A brief introduction to the topic is followed by an overview of relevant alkaloids from fungal and microbial sources, among them slaframine, cyclizidine, Steptomyces metabolites, and the pantocins. The important iminosugar alkaloids lentiginosine, steviamine, swainsonine, castanospermine, and related hydroxyindolizidines are dealt with in the subsequent section. The fourth and fifth sections cover metabolites from terrestrial plants. Pertinent plant alkaloids bearing alkyl, functionalized alkyl or alkenyl substituents include dendroprimine, anibamine, simple alkaloids belonging to the genera Prosopis, Elaeocarpus, Lycopodium, and Poranthera, and bicyclic alkaloids of the lupin family. Plant alkaloids bearing aryl or heteroaryl substituents include ipalbidine and analogs, secophenanthroindolizidine and secophenanthroquinolizidine alkaloids (among them septicine, julandine, and analogs), ficuseptine, lasubines, and other simple quinolizidines of the Lythraceae, the simple furyl-substituted Nuphar alkaloids, and a mixed quinolizidine-quinazoline alkaloid. The penultimate section of the review deals with the sizable group of simple indolizidine and quinolizidine alkaloids isolated from, or detected in, ants, mites, and terrestrial amphibians, and includes an overview of the "dietary hypothesis" for the origin of the amphibian metabolites. The final section surveys relevant alkaloids from marine sources, and includes clathryimines and analogs, stellettamides, the clavepictines and pictamine, and bis
Simple Indolizidine and Quinolizidine Alkaloids.
Michael, Joseph P
2016-01-01
This review of simple indolizidine and quinolizidine alkaloids (i.e., those in which the parent bicyclic systems are in general not embedded in polycyclic arrays) is an update of the previous coverage in Volume 55 of this series (2001). The present survey covers the literature from mid-1999 to the end of 2013; and in addition to aspects of the isolation, characterization, and biological activity of the alkaloids, much emphasis is placed on their total synthesis. A brief introduction to the topic is followed by an overview of relevant alkaloids from fungal and microbial sources, among them slaframine, cyclizidine, Steptomyces metabolites, and the pantocins. The important iminosugar alkaloids lentiginosine, steviamine, swainsonine, castanospermine, and related hydroxyindolizidines are dealt with in the subsequent section. The fourth and fifth sections cover metabolites from terrestrial plants. Pertinent plant alkaloids bearing alkyl, functionalized alkyl or alkenyl substituents include dendroprimine, anibamine, simple alkaloids belonging to the genera Prosopis, Elaeocarpus, Lycopodium, and Poranthera, and bicyclic alkaloids of the lupin family. Plant alkaloids bearing aryl or heteroaryl substituents include ipalbidine and analogs, secophenanthroindolizidine and secophenanthroquinolizidine alkaloids (among them septicine, julandine, and analogs), ficuseptine, lasubines, and other simple quinolizidines of the Lythraceae, the simple furyl-substituted Nuphar alkaloids, and a mixed quinolizidine-quinazoline alkaloid. The penultimate section of the review deals with the sizable group of simple indolizidine and quinolizidine alkaloids isolated from, or detected in, ants, mites, and terrestrial amphibians, and includes an overview of the "dietary hypothesis" for the origin of the amphibian metabolites. The final section surveys relevant alkaloids from marine sources, and includes clathryimines and analogs, stellettamides, the clavepictines and pictamine, and bis
Linear dependencies between composite fermion states
NASA Astrophysics Data System (ADS)
Meyer, M. L.; Liabøtrø, O.; Viefers, S.
2016-09-01
The formalism of composite fermions (CFs) has been one of the most prominent and successful approaches to describing the fractional quantum Hall effect, in terms of trial many-body wave functions. Testing the accuracy of the latter typically involves rather heavy numerical comparison to exact diagonalization results. Thus, optimizing computational efficiency has been an important technical issue in this field. One generic (and not yet fully understood) property of the CF approach is that it tends to overcount the number of linearly independent candidate states for fixed sets of quantum numbers. Technically speaking, CF Slater determinants that are orthogonal before projection to the lowest Landau level, may lead to wave functions that are identical, or possess linear dependencies, after projection. This leads to unnecessary computations, and has been pointed out in the literature both for fermionic and bosonic systems. We here present a systematic approach that enables us to reveal all linear dependencies between bosonic compact states in the lowest CF ‘cyclotron energy’ sub-band, and almost all dependencies in higher sub-bands, at the level of the CF Slater determinants, i.e. before projection, which implies a major computational simplification. Our approach is introduced for so-called simple states of two-species rotating bosons, and then generalized to generic compact bosonic states, both one- and two-species. Some perspectives also apply to fermionic systems. The identities and linear dependencies we find, are analytically exact for ‘brute force’ projection in the disk geometry.
Modelling a Simple Mechanical System.
ERIC Educational Resources Information Center
Morland, Tim
1999-01-01
Provides an example of the modeling power of Mathematics, demonstrated in a piece of A-Level student coursework which was undertaken as part of the MEI Structured Mathematics scheme. A system of two masses and two springs oscillating in one dimension is found to be accurately modeled by a system of linear differential equations. (Author/ASK)
NASA Astrophysics Data System (ADS)
2001-05-01
Third Nucleus Observed with the VLT Summary New images from the VLT show that one of the two nuclei of Comet LINEAR (C/2001 A2), now about 100 million km from the Earth, has just split into at least two pieces . The three fragments are now moving through space in nearly parallel orbits while they slowly drift apart. This comet will pass through its perihelion (nearest point to the Sun) on May 25, 2001, at a distance of about 116 million kilometres. It has brightened considerably due to the splitting of its "dirty snowball" nucleus and can now be seen with the unaided eye by observers in the southern hemisphere as a faint object in the southern constellation of Lepus (The Hare). PR Photo 18a/01 : Three nuclei of Comet LINEAR . PR Photo 18b/01 : The break-up of Comet LINEAR (false-colour). Comet LINEAR splits and brightens ESO PR Photo 18a/01 ESO PR Photo 18a/01 [Preview - JPEG: 400 x 438 pix - 55k] [Normal - JPEG: 800 x 875 pix - 136k] ESO PR Photo 18b/01 ESO PR Photo 18b/01 [Preview - JPEG: 367 x 400 pix - 112k] [Normal - JPEG: 734 x 800 pix - 272k] Caption : ESO PR Photo 18a/01 shows the three nuclei of Comet LINEAR (C/2001 A2). It is a reproduction of a 1-min exposure in red light, obtained in the early evening of May 16, 2001, with the 8.2-m VLT YEPUN (UT4) telescope at Paranal. ESO PR Photo 18b/01 shows the same image, but in a false-colour rendering for more clarity. The cometary fragment "B" (right) has split into "B1" and "B2" (separation about 1 arcsec, or 500 km) while fragment "A" (upper left) is considerably fainter. Technical information about these photos is available below. Comet LINEAR was discovered on January 3, 2001, and designated by the International Astronomical Union (IAU) as C/2001 A2 (see IAU Circular 7564 [1]). Six weeks ago, it was suddenly observed to brighten (IAUC 7605 [1]). Amateurs all over the world saw the comparatively faint comet reaching naked-eye magnitude and soon thereafter, observations with professional telescopes indicated
On the linear programming bound for linear Lee codes.
Astola, Helena; Tabus, Ioan
2016-01-01
Based on an invariance-type property of the Lee-compositions of a linear Lee code, additional equality constraints can be introduced to the linear programming problem of linear Lee codes. In this paper, we formulate this property in terms of an action of the multiplicative group of the field [Formula: see text] on the set of Lee-compositions. We show some useful properties of certain sums of Lee-numbers, which are the eigenvalues of the Lee association scheme, appearing in the linear programming problem of linear Lee codes. Using the additional equality constraints, we formulate the linear programming problem of linear Lee codes in a very compact form, leading to a fast execution, which allows to efficiently compute the bounds for large parameter values of the linear codes.
An analogue of the Berry phase for simple harmonic oscillators
NASA Astrophysics Data System (ADS)
Suslov, S. K.
2013-03-01
We evaluate a variant of Berry's phase for a ‘missing’ family of the square integrable wavefunctions for the linear harmonic oscillator, which cannot be derived by the separation of variables (in a natural way). Instead, it is obtained by the action of the maximal kinematical invariance group on the standard solutions. A simple closed formula for the phase (in terms of elementary functions) is found here by integration with the help of a computer algebra system.
Simple Numerical Schemes for the Korteweg-deVries Equation
C. J. McKinstrie; M. V. Kozlov
2000-12-01
Two numerical schemes, which simulate the propagation of dispersive non-linear waves, are described. The first is a split-step Fourier scheme for the Korteweg-de Vries (KdV) equation. The second is a finite-difference scheme for the modified KdV equation. The stability and accuracy of both schemes are discussed. These simple schemes can be used to study a wide variety of physical processes that involve dispersive nonlinear waves.
Computer modeling of batteries from non-linear circuit elements
NASA Technical Reports Server (NTRS)
Waaben, S.; Federico, J.; Moskowitz, I.
1983-01-01
A simple non-linear circuit model for battery behavior is given. It is based on time-dependent features of the well-known PIN change storage diode, whose behavior is described by equations similar to those associated with electrochemical cells. The circuit simulation computer program ADVICE was used to predict non-linear response from a topological description of the battery analog built from advice components. By a reasonable choice of one set of parameters, the circuit accurately simulates a wide spectrum of measured non-linear battery responses to within a few millivolts.
Positrons for linear colliders
Ecklund, S.
1987-11-01
The requirements of a positron source for a linear collider are briefly reviewed, followed by methods of positron production and production of photons by electromagnetic cascade showers. Cross sections for the electromagnetic cascade shower processes of positron-electron pair production and Compton scattering are compared. A program used for Monte Carlo analysis of electromagnetic cascades is briefly discussed, and positron distributions obtained from several runs of the program are discussed. Photons from synchrotron radiation and from channeling are also mentioned briefly, as well as positron collection, transverse focusing techniques, and longitudinal capture. Computer ray tracing is then briefly discussed, followed by space-charge effects and thermal heating and stress due to showers. (LEW)
2006-11-17
Software that simulates and inverts electromagnetic field data for subsurface electrical properties (electrical conductivity) of geological media. The software treats data produced by a time harmonic source field excitation arising from the following antenna geometery: loops and grounded bipoles, as well as point electric and magnetic dioples. The inversion process is carried out using a non-linear conjugate gradient optimization scheme, which minimizes the misfit between field data and model data using a least squares criteria.more » The software is an upgrade from the code NLCGCS_MP ver 1.0. The upgrade includes the following components: Incorporation of new 1 D field sourcing routines to more accurately simulate the 3D electromagnetic field for arbitrary geologic& media, treatment for generalized finite length transmitting antenna geometry (antennas with vertical and horizontal component directions). In addition, the software has been upgraded to treat transverse anisotropy in electrical conductivity.« less
Linear response at criticality
NASA Astrophysics Data System (ADS)
Svenkeson, Adam; Bologna, Mauro; Grigolini, Paolo
2012-10-01
We study a set of cooperatively interacting units at criticality, and we prove with analytical and numerical arguments that they generate the same renewal non-Poisson intermittency as that produced by blinking quantum dots, thereby giving a stronger support to the results of earlier investigation. By analyzing how this out-of-equilibrium system responds to harmonic perturbations, we find that the response can be described only using a new form of linear response theory that accounts for aging and the nonergodic behavior of the underlying process. We connect the undamped response of the system at criticality to the decaying response predicted by the recently established nonergodic fluctuation-dissipation theorem for dichotomous processes using information about the second moment of the fluctuations. We demonstrate that over a wide range of perturbation frequencies the response of the cooperative system is greatest when at criticality.
Van Atta, C.M.; Beringer, R.; Smith, L.
1959-01-01
A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.
NASA Technical Reports Server (NTRS)
Holloway, Sidney E., III
1994-01-01
This paper describes the mechanical design, analysis, fabrication, testing, and lessons learned by developing a uniquely designed spaceflight-like actuator. The linear proof mass actuator (LPMA) was designed to attach to both a large space structure and a ground test model without modification. Previous designs lacked the power to perform in a terrestrial environment while other designs failed to produce the desired accelerations or frequency range for spaceflight applications. Thus, the design for a unique actuator was conceived and developed at NASA Langley Research Center. The basic design consists of four large mechanical parts (mass, upper housing, lower housing, and center support) and numerous smaller supporting components including an accelerometer, encoder, and four drive motors. Fabrication personnel were included early in the design phase of the LPMA as part of an integrated manufacturing process to alleviate potential difficulties in machining an already challenging design. Operating testing of the LPMA demonstrated that the actuator is capable of various types of load functions.
NASA Technical Reports Server (NTRS)
Holloway, S. E., III
1995-01-01
This paper describes the mechanical design, analysis, fabrication, testing, and lessons learned by developing a uniquely designed spaceflight-like actuator. The Linear Proof Mass Actuator (LPMA) was designed to attach to both a large space structure and a ground test model without modification. Previous designs lacked the power to perform in a terrestrial environment while other designs failed to produce the desired accelerations or frequency range for spaceflight applications. Thus, the design for a unique actuator was conceived and developed at NASA Langley Research Center. The basic design consists of four large mechanical parts (Mass, Upper Housing, Lower Housing, and Center Support) and numerous smaller supporting components including an accelerometer, encoder, and four drive motors. Fabrication personnel were included early in the design phase of the LPMA as part of an integrated manufacturing process to alleviate potential difficulties in machining an already challenging design. Operational testing of the LPMA demonstrated that the actuator is capable of various types of load functions.
Four simple ocean carbon models
NASA Technical Reports Server (NTRS)
Moore, Berrien, III
1992-01-01
This paper briefly reviews the key processes that determine oceanic CO2 uptake and sets this description within the context of four simple ocean carbon models. These models capture, in varying degrees, these key processes and establish a clear foundation for more realistic models that incorporate more directly the underlying physics and biology of the ocean rather than relying on simple parametric schemes. The purpose of this paper is more pedagogical than purely scientific. The problems encountered by current attempts to understand the global carbon cycle not only require our efforts but set a demand for a new generation of scientist, and it is hoped that this paper and the text in which it appears will help in this development.
Simple model of hydrophobic hydration.
Lukšič, Miha; Urbic, Tomaz; Hribar-Lee, Barbara; Dill, Ken A
2012-05-31
Water is an unusual liquid in its solvation properties. Here, we model the process of transferring a nonpolar solute into water. Our goal was to capture the physical balance between water's hydrogen bonding and van der Waals interactions in a model that is simple enough to be nearly analytical and not heavily computational. We develop a 2-dimensional Mercedes-Benz-like model of water with which we compute the free energy, enthalpy, entropy, and the heat capacity of transfer as a function of temperature, pressure, and solute size. As validation, we find that this model gives the same trends as Monte Carlo simulations of the underlying 2D model and gives qualitative agreement with experiments. The advantages of this model are that it gives simple insights and that computational time is negligible. It may provide a useful starting point for developing more efficient and more realistic 3D models of aqueous solvation.
Simple Fixed Functional Space Maintainer
Sarawgi, Aditi; Marwah, Nikhil; Gumber, Parvind; Dutta, Samir
2014-01-01
ABSTRACT% Premature loss of a primary tooth is one of the most common etiology for malocclusion. Space maintainers are employed to prevent this complication. In anterior region, esthetics is an important concern along with function and space management. Fiber-reinforced composite (FRC) retained space maintainer solves all these purposes ef ficiently and ef fectively. In addition, the technique is simple and the appliance is very comfortable inside the oral cavity. Here is a case of premature loss of anterior primary tooth which was replaced by FRC retained esthetic functional space maintainer. The appliance was found to be functioning satisfactorily inside the oral cavity till the last visit (1 Year). How to cite this article: Goenka P, Sarawgi A, Marwah N, Gumber P, Dutta S. Simple Fixed Functional Space Maintainer. Int J Clin Pediatr Dent 2014;7(3):225-228. PMID:25709309
Webcam classification using simple features
NASA Astrophysics Data System (ADS)
Pramoun, Thitiporn; Choe, Jeehyun; Li, He; Chen, Qingshuang; Amornraksa, Thumrongrat; Lu, Yung-Hsiang; Delp, Edward J.
2015-03-01
Thousands of sensors are connected to the Internet and many of these sensors are cameras. The "Internet of Things" will contain many "things" that are image sensors. This vast network of distributed cameras (i.e. web cams) will continue to exponentially grow. In this paper we examine simple methods to classify an image from a web cam as "indoor/outdoor" and having "people/no people" based on simple features. We use four types of image features to classify an image as indoor/outdoor: color, edge, line, and text. To classify an image as having people/no people we use HOG and texture features. The features are weighted based on their significance and combined. A support vector machine is used for classification. Our system with feature weighting and feature combination yields 95.5% accuracy.
NASA Astrophysics Data System (ADS)
Tennekes, Henk
1997-05-01
From the smallest gnat to the largest aircraft, all things that fly obey the same aerodynamic principles. The Simple Science of Flight offers a leisurely introduction to the mechanics of flight and, beyond that, to the scientific attitude that finds wonder in simple calculations, forging connections between, say, the energy efficiency of a peanut butter sandwich and that of the kerosene that fuels a jumbo jet. It is the product of a lifetime of watching and investigating the way flight happens. The hero of the book is the Boeing 747, which Tennekes sees as the current pinnacle of human ingenuity in mastering the science of flight. Also covered are paper airplanes, kites, gliders, and human-powered flying machines as well as birds and insects. Tennekes explains concepts like lift, drag, wing loading, and cruising speed through many fascinating comparisons, anecdotes, and examples.
Simple fixed functional space maintainer.
Goenka, Puneet; Sarawgi, Aditi; Marwah, Nikhil; Gumber, Parvind; Dutta, Samir
2014-01-01
Premature loss of a primary tooth is one of the most common etiology for malocclusion. Space maintainers are employed to prevent this complication. In anterior region, esthetics is an important concern along with function and space management. Fiber-reinforced composite (FRC) retained space maintainer solves all these purposes ef ficiently and ef fectively. In addition, the technique is simple and the appliance is very comfortable inside the oral cavity. Here is a case of premature loss of anterior primary tooth which was replaced by FRC retained esthetic functional space maintainer. The appliance was found to be functioning satisfactorily inside the oral cavity till the last visit (1 Year). How to cite this article: Goenka P, Sarawgi A, Marwah N, Gumber P, Dutta S. Simple Fixed Functional Space Maintainer. Int J Clin Pediatr Dent 2014;7(3):225-228.
Simple model of hydrophobic hydration.
Lukšič, Miha; Urbic, Tomaz; Hribar-Lee, Barbara; Dill, Ken A
2012-05-31
Water is an unusual liquid in its solvation properties. Here, we model the process of transferring a nonpolar solute into water. Our goal was to capture the physical balance between water's hydrogen bonding and van der Waals interactions in a model that is simple enough to be nearly analytical and not heavily computational. We develop a 2-dimensional Mercedes-Benz-like model of water with which we compute the free energy, enthalpy, entropy, and the heat capacity of transfer as a function of temperature, pressure, and solute size. As validation, we find that this model gives the same trends as Monte Carlo simulations of the underlying 2D model and gives qualitative agreement with experiments. The advantages of this model are that it gives simple insights and that computational time is negligible. It may provide a useful starting point for developing more efficient and more realistic 3D models of aqueous solvation. PMID:22564051
Computer Program For Linear Algebra
NASA Technical Reports Server (NTRS)
Krogh, F. T.; Hanson, R. J.
1987-01-01
Collection of routines provided for basic vector operations. Basic Linear Algebra Subprogram (BLAS) library is collection from FORTRAN-callable routines for employing standard techniques to perform basic operations of numerical linear algebra.
A simple scanning mirror mechanism for a Fourier transform spectrometer
NASA Astrophysics Data System (ADS)
Brasunas, John C.; Cushman, G. Mark
1998-04-01
We present a simple scanning mirror mechanism for a Fourier transform spectrometer, consisting of a voice coil actuator, a ball-bearing slide, and a single cube corner mirror or retroreflector. The use of a single cube corner reduces significantly the sensitivity of the Fourier transform spectrometer to the tilt of its moving mirror, enabling the simple mechanism. With simple velocity feedback using a linear velocity transducer, we achieve a scan speed stability of 2%-5% (root-mean-square) for scan speeds from 40 to 440 μm/s for a travel of 2.2 cm, corresponding to a spectral resolution of 0.06 cm-1. Fringe amplitude stability is about 5%. This scan mechanism was operated at standard temperature and pressure, but the relatively minute amount of lubricant in the ball-bearing slide may indicate possible operation under vacuum and/or cryogenic conditions.
Linearity Study of a Spectral Emissivity Measurement Facility
NASA Astrophysics Data System (ADS)
Yuan, Z.; Zhang, J.; Zhao, J.; Liang, Y.; Duan, Y.
2009-02-01
Linearity is one of the important characteristics of a spectral radiation measurement facility. Basically, it depends on the linearity of the spectral responsivity of the detector and amplifier at different wavelengths. As spectral emissivity is measured over wide wavelength and temperature ranges and the detection system has significant drift and noise, it is not easy to measure the linearity of this facility accurately using only one standard radiator. A simple double-blackbody method has been adopted to simulate reference emissivity samples and test the linearity of the spectral emissivity measurement facility developed at the National Institute of Metrology. Good linearity results were obtained from 3 μm to 15 μm. This method minimizes the influence of drift on the emissivity measurement over a wide ratio of measurement signals and wide spectral range.
A simple theory of motor protein kinetics and energetics. II.
Qian, H
2000-01-10
A three-state stochastic model of motor protein [Qian, Biophys. Chem. 67 (1997) pp. 263-267] is further developed to illustrate the relationship between the external load on an individual motor protein in aqueous solution with various ATP concentrations and its steady-state velocity. A wide variety of dynamic motor behavior are obtained from this simple model. For the particular case of free-load translocation being the most unfavorable step within the hydrolysis cycle, the load-velocity curve is quasi-linear, V/Vmax = (cF/Fmax-c)/(1-c), in contrast to the hyperbolic relationship proposed by A.V. Hill for macroscopic muscle. Significant deviation from the linearity is expected when the velocity is less than 10% of its maximal (free-load) value--a situation under which the processivity of motor diminishes and experimental observations are less certain. We then investigate the dependence of load-velocity curve on ATP (ADP) concentration. It is shown that the free load Vmax exhibits a Michaelis-Menten like behavior, and the isometric Fmax increases linearly with ln([ATP]/[ADP]). However, the quasi-linear region is independent of the ATP concentration, yielding an apparently ATP-independent maximal force below the true isometric force. Finally, the heat production as a function of ATP concentration and external load are calculated. In simple terms and solved with elementary algebra, the present model provides an integrated picture of biochemical kinetics and mechanical energetics of motor proteins. PMID:10631478
Inverse Modelling Problems in Linear Algebra Undergraduate Courses
ERIC Educational Resources Information Center
Martinez-Luaces, Victor E.
2013-01-01
This paper will offer an analysis from a theoretical point of view of mathematical modelling, applications and inverse problems of both causation and specification types. Inverse modelling problems give the opportunity to establish connections between theory and practice and to show this fact, a simple linear algebra example in two different…
Continuous Quantitative Measurements on a Linear Air Track
ERIC Educational Resources Information Center
Vogel, Eric
1973-01-01
Describes the construction and operational procedures of a spark-timing apparatus which is designed to record the back and forth motion of one or two carts on linear air tracks. Applications to measurements of velocity, acceleration, simple harmonic motion, and collision problems are illustrated. (CC)
The Pendulum: A Paradigm for the Linear Oscillator
ERIC Educational Resources Information Center
Newburgh, Ronald
2004-01-01
The simple pendulum is a model for the linear oscillator. The usual mathematical treatment of the problem begins with a differential equation that one solves with the techniques of the differential calculus, a formal process that tends to obscure the physics. In this paper we begin with a kinematic description of the motion obtained by experiment…
Simulation of a medical linear accelerator for teaching purposes.
Anderson, Rhys; Lamey, Michael; MacPherson, Miller; Carlone, Marco
2015-01-01
Simulation software for medical linear accelerators that can be used in a teaching environment was developed. The components of linear accelerators were modeled to first order accuracy using analytical expressions taken from the literature. The expressions used constants that were empirically set such that realistic response could be expected. These expressions were programmed in a MATLAB environment with a graphical user interface in order to produce an environment similar to that of linear accelerator service mode. The program was evaluated in a systematic fashion, where parameters affecting the clinical properties of medical linear accelerator beams were adjusted independently, and the effects on beam energy and dose rate recorded. These results confirmed that beam tuning adjustments could be simulated in a simple environment. Further, adjustment of service parameters over a large range was possible, and this allows the demonstration of linear accelerator physics in an environment accessible to both medical physicists and linear accelerator service engineers. In conclusion, a software tool, named SIMAC, was developed to improve the teaching of linear accelerator physics in a simulated environment. SIMAC performed in a similar manner to medical linear accelerators. The authors hope that this tool will be valuable as a teaching tool for medical physicists and linear accelerator service engineers.
Acute otitis media: a simple diagnosis, a simple treatment.
Chhetri, S S
2014-09-01
To assess the symptoms and signs of acute otitis media and efficiency of simple antibiotics like amoxicillin in its treatment in the primary health care setup. This is a prospective longitudinal study including 204 patients from different institutions. Patients were diagnosed as suffering from acute otitis media when presented with earache, fever, fullness and or otorrhea. Patients were divided into two equal groups on basis of the treatment they received, Group A received only symptomatic treatment while Group B were given Amoxicillin (40 mg/kg/day) for 7 days. Acute otitis media was common in children under 15 years (64.7%). Patients presented with earache (100%), aural fullness (90.68%), fever (76.47%) associated with recent onset of upper respiratory tract infections (88.23%). In group A, improvement was noticed in 28.43% in 3 days while 35.29% in 7 days. In group B, improvement was noticed in 48.03% in day 3 while 86.27% in day 7. In countries where medical care is scarce, patients lost to follow up, it is wise to treat with simple antibiotics like amoxicillin in adequate dose than to treat only symptomatically. It prevents chronicity, early hearing impairments and reduces antibiotic resistance.
LINEAR - DERIVATION AND DEFINITION OF A LINEAR AIRCRAFT MODEL
NASA Technical Reports Server (NTRS)
Duke, E. L.
1994-01-01
The Derivation and Definition of a Linear Model program, LINEAR, provides the user with a powerful and flexible tool for the linearization of aircraft aerodynamic models. LINEAR was developed to provide a standard, documented, and verified tool to derive linear models for aircraft stability analysis and control law design. Linear system models define the aircraft system in the neighborhood of an analysis point and are determined by the linearization of the nonlinear equations defining vehicle dynamics and sensors. LINEAR numerically determines a linear system model using nonlinear equations of motion and a user supplied linear or nonlinear aerodynamic model. The nonlinear equations of motion used are six-degree-of-freedom equations with stationary atmosphere and flat, nonrotating earth assumptions. LINEAR is capable of extracting both linearized engine effects, such as net thrust, torque, and gyroscopic effects and including these effects in the linear system model. The point at which this linear model is defined is determined either by completely specifying the state and control variables, or by specifying an analysis point on a trajectory and directing the program to determine the control variables and the remaining state variables. The system model determined by LINEAR consists of matrices for both the state and observation equations. The program has been designed to provide easy selection of state, control, and observation variables to be used in a particular model. Thus, the order of the system model is completely under user control. Further, the program provides the flexibility of allowing alternate formulations of both the state and observation equations. Data describing the aircraft and the test case is input to the program through a terminal or formatted data files. All data can be modified interactively from case to case. The aerodynamic model can be defined in two ways: a set of nondimensional stability and control derivatives for the flight point of
Generalized Linear Covariance Analysis
NASA Astrophysics Data System (ADS)
Markley, F. Landis; Carpenter, J. Russell
2009-01-01
This paper presents a comprehensive approach to filter modeling for generalized covariance analysis of both batch least-squares and sequential estimators. We review and extend in two directions the results of prior work that allowed for partitioning of the state space into "solve-for" and "consider" parameters, accounted for differences between the formal values and the true values of the measurement noise, process noise, and a priori solve-for and consider covariances, and explicitly partitioned the errors into subspaces containing only the influence of the measurement noise, process noise, and a priori solve-for and consider covariances. In this work, we explicitly add sensitivity analysis to this prior work, and relax an implicit assumption that the batch estimator's epoch time occurs prior to the definitive span. We also apply the method to an integrated orbit and attitude problem, in which gyro and accelerometer errors, though not estimated, influence the orbit determination performance. We illustrate our results using two graphical presentations, which we call the "variance sandpile" and the "sensitivity mosaic," and we compare the linear covariance results to confidence intervals associated with ensemble statistics from a Monte Carlo analysis.
Generalized Linear Covariance Analysis
NASA Technical Reports Server (NTRS)
Carpenter, James R.; Markley, F. Landis
2014-01-01
This talk presents a comprehensive approach to filter modeling for generalized covariance analysis of both batch least-squares and sequential estimators. We review and extend in two directions the results of prior work that allowed for partitioning of the state space into solve-for'' and consider'' parameters, accounted for differences between the formal values and the true values of the measurement noise, process noise, and textita priori solve-for and consider covariances, and explicitly partitioned the errors into subspaces containing only the influence of the measurement noise, process noise, and solve-for and consider covariances. In this work, we explicitly add sensitivity analysis to this prior work, and relax an implicit assumption that the batch estimator's epoch time occurs prior to the definitive span. We also apply the method to an integrated orbit and attitude problem, in which gyro and accelerometer errors, though not estimated, influence the orbit determination performance. We illustrate our results using two graphical presentations, which we call the variance sandpile'' and the sensitivity mosaic,'' and we compare the linear covariance results to confidence intervals associated with ensemble statistics from a Monte Carlo analysis.
Kliman, Gerald B.; Brynsvold, Glen V.; Jahns, Thomas M.
1989-01-01
A winding and method of winding for a submersible linear pump for pumping liquid sodium is disclosed. The pump includes a stator having a central cylindrical duct preferably vertically aligned. The central vertical duct is surrounded by a system of coils in slots. These slots are interleaved with magnetic flux conducting elements, these magnetic flux conducting elements forming a continuous magnetic field conduction path along the stator. The central duct has placed therein a cylindrical magnetic conducting core, this core having a cylindrical diameter less than the diameter of the cylindrical duct. The core once placed to the duct defines a cylindrical interstitial pumping volume of the pump. This cylindrical interstitial pumping volume preferably defines an inlet at the bottom of the pump, and an outlet at the top of the pump. Pump operation occurs by static windings in the outer stator sequentially conveying toroidal fields from the pump inlet at the bottom of the pump to the pump outlet at the top of the pump. The winding apparatus and method of winding disclosed uses multiple slots per pole per phase with parallel winding legs on each phase equal to or less than the number of slots per pole per phase. The slot sequence per pole per phase is chosen to equalize the variations in flux density of the pump sodium as it passes into the pump at the pump inlet with little or no flux and acquires magnetic flux in passage through the pump to the pump outlet.
Kliman, G.B.; Brynsvold, G.V.; Jahns, T.M.
1989-08-22
A winding and method of winding for a submersible linear pump for pumping liquid sodium are disclosed. The pump includes a stator having a central cylindrical duct preferably vertically aligned. The central vertical duct is surrounded by a system of coils in slots. These slots are interleaved with magnetic flux conducting elements, these magnetic flux conducting elements forming a continuous magnetic field conduction path along the stator. The central duct has placed therein a cylindrical magnetic conducting core, this core having a cylindrical diameter less than the diameter of the cylindrical duct. The core once placed to the duct defines a cylindrical interstitial pumping volume of the pump. This cylindrical interstitial pumping volume preferably defines an inlet at the bottom of the pump, and an outlet at the top of the pump. Pump operation occurs by static windings in the outer stator sequentially conveying toroidal fields from the pump inlet at the bottom of the pump to the pump outlet at the top of the pump. The winding apparatus and method of winding disclosed uses multiple slots per pole per phase with parallel winding legs on each phase equal to or less than the number of slots per pole per phase. The slot sequence per pole per phase is chosen to equalize the variations in flux density of the pump sodium as it passes into the pump at the pump inlet with little or no flux and acquires magnetic flux in passage through the pump to the pump outlet. 4 figs.
Meisner, John W.; Moore, Robert M.; Bienvenue, Louis L.
1985-03-19
Electromagnetic linear induction pump for liquid metal which includes a unitary pump duct. The duct comprises two substantially flat parallel spaced-apart wall members, one being located above the other and two parallel opposing side members interconnecting the wall members. Located within the duct are a plurality of web members interconnecting the wall members and extending parallel to the side members whereby the wall members, side members and web members define a plurality of fluid passageways, each of the fluid passageways having substantially the same cross-sectional flow area. Attached to an outer surface of each side member is an electrically conductive end bar for the passage of an induced current therethrough. A multi-phase, electrical stator is located adjacent each of the wall members. The duct, stators, and end bars are enclosed in a housing which is provided with an inlet and outlet in fluid communication with opposite ends of the fluid passageways in the pump duct. In accordance with a preferred embodiment, the inlet and outlet includes a transition means which provides for a transition from a round cross-sectional flow path to a substantially rectangular cross-sectional flow path defined by the pump duct.
Generalized Linear Covariance Analysis
NASA Technical Reports Server (NTRS)
Carpenter, J. Russell; Markley, F. Landis
2008-01-01
We review and extend in two directions the results of prior work on generalized covariance analysis methods. This prior work allowed for partitioning of the state space into "solve-for" and "consider" parameters, allowed for differences between the formal values and the true values of the measurement noise, process noise, and a priori solve-for and consider covariances, and explicitly partitioned the errors into subspaces containing only the influence of the measurement noise, process noise, and a priori solve-for and consider covariances. In this work, we explicitly add sensitivity analysis to this prior work, and relax an implicit assumption that the batch estimator s anchor time occurs prior to the definitive span. We also apply the method to an integrated orbit and attitude problem, in which gyro and accelerometer errors, though not estimated, influence the orbit determination performance. We illustrate our results using two graphical presentations, which we call the "variance sandpile" and the "sensitivity mosaic," and we compare the linear covariance results to confidence intervals associated with ensemble statistics from a Monte Carlo analysis.
NASA Astrophysics Data System (ADS)
Theofilis, Vassilios
2011-01-01
This article reviews linear instability analysis of flows over or through complex two-dimensional (2D) and 3D geometries. In the three decades since it first appeared in the literature, global instability analysis, based on the solution of the multidimensional eigenvalue and/or initial value problem, is continuously broadening both in scope and in depth. To date it has dealt successfully with a wide range of applications arising in aerospace engineering, physiological flows, food processing, and nuclear-reactor safety. In recent years, nonmodal analysis has complemented the more traditional modal approach and increased knowledge of flow instability physics. Recent highlights delivered by the application of either modal or nonmodal global analysis are briefly discussed. A conscious effort is made to demystify both the tools currently utilized and the jargon employed to describe them, demonstrating the simplicity of the analysis. Hopefully this will provide new impulses for the creation of next-generation algorithms capable of coping with the main open research areas in which step-change progress can be expected by the application of the theory: instability analysis of fully inhomogeneous, 3D flows and control thereof.
Berkeley Proton Linear Accelerator
DOE R&D Accomplishments Database
Alvarez, L. W.; Bradner, H.; Franck, J.; Gordon, H.; Gow, J. D.; Marshall, L. C.; Oppenheimer, F. F.; Panofsky, W. K. H.; Richman, C.; Woodyard, J. R.
1953-10-13
A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup 6} watts peak at 202.5 mc. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type.
On the Characteristics of Coaxial-Type Microwave Excited Linear Plasma: a Simple Numerical Analysis
NASA Astrophysics Data System (ADS)
Chen, Longwei; Meng, Yuedong; Zuo, Xiao; Ren, Zhaoxing; Wu, Kenan; Wang, Shuai
2015-05-01
To unveil the characteristics and available propagation mechanism of coaxial-type microwave excited line-shape plasma, the effects of parameters including microwave power, working pressure, dielectric constant, and external magnetic field on the plasma distribution were numerically investigated by solving a coupled system of Maxwell's equations and continuity equations. Numerical results indicate that high microwave power, relatively high working pressure, low dielectric constant, and shaped magnetic field profiles will help produce a high-density and uniform plasma source. Exciting both ends by microwave contributed to the high-density and uniform plasma source as well. Possible mechanisms were analyzed by using the polarization model of low temperature plasma. The generation and propagation processes of the line-shape plasma mainly depend on the interaction of three aspects, i.e. the transmitted part, penetration part and absorptive part of the electromagnetic field. The numerical results were qualitatively consistent with available experimental results from literature. More elaborate descriptions of the three aspects and corresponding interactions among them need to be investigated further to improve the properties of the line-shape plasma. supported by National Natural Science Foundation of China (Nos. 11205201 and 61205139), and the Scientific Foundation of Ministry of Education of China (No. N130405008)
Neutrinos in non-linear structure formation — a simple SPH approach
Hannestad, Steen; Schultz, Christian; Haugbolle, Troels E-mail: haugboel@nbi.dk
2012-02-01
We present a novel method for implementing massive neutrinos in N-body simulations. Instead of sampling the neutrino velocity distribution by individual point particles we take neutrino free-streaming into account by treating it as an effective redshift dependent sound speed in a perfect isothermal fluid, and assume a relation between the sound speed and velocity dispersion of the neutrinos. Although the method fails to accurately model the true neutrino power spectrum, it is able to calculate the total matter power spectrum to the same accuracy as more complex hybrid neutrino methods, except on very small scales. We also present an easy way to update the publicly available GADGET-2 version with this neutrino approximation.
NASA Technical Reports Server (NTRS)
Parker, Peter A.; Geoffrey, Vining G.; Wilson, Sara R.; Szarka, John L., III; Johnson, Nels G.
2010-01-01
The calibration of measurement systems is a fundamental but under-studied problem within industrial statistics. The origins of this problem go back to basic chemical analysis based on NIST standards. In today's world these issues extend to mechanical, electrical, and materials engineering. Often, these new scenarios do not provide "gold standards" such as the standard weights provided by NIST. This paper considers the classic "forward regression followed by inverse regression" approach. In this approach the initial experiment treats the "standards" as the regressor and the observed values as the response to calibrate the instrument. The analyst then must invert the resulting regression model in order to use the instrument to make actual measurements in practice. This paper compares this classical approach to "reverse regression," which treats the standards as the response and the observed measurements as the regressor in the calibration experiment. Such an approach is intuitively appealing because it avoids the need for the inverse regression. However, it also violates some of the basic regression assumptions.
Wang, Dan Ohtan; Matsuno, Hitomi; Ikeda, Shuji; Nakamura, Akiko; Yanagisawa, Hiroyuki; Hayashi, Yasunori; Okamoto, Akimitsu
2012-01-01
Fluorescence in situ hybridization (FISH) is a powerful tool used in karyotyping, cytogenotyping, cancer diagnosis, species specification, and gene-expression analysis. Although widely used, conventional FISH protocols are cumbersome and time consuming. We have now developed a FISH method using exciton-controlled hybridization-sensitive fluorescent oligodeoxynucleotide (ECHO) probes. ECHO-FISH uses a 25-min protocol from fixation to mounting that includes no stringency washing steps. We use ECHO-FISH to detect both specific DNA and RNA sequences with multicolor probes. ECHO-FISH is highly reproducible, stringent, and compatible with other fluorescent cellular labeling techniques. The resolution allows detection of intranuclear speckles of poly(A) RNA in HeLa cells and dissociated hippocampal primary cultures, and mRNAs in the distal dendrites of hippocampal neurons. We also demonstrate detection of telomeric and centromeric DNA on metaphase mouse chromosomes. The simplicity of the ECHO-FISH method will likely accelerate cytogenetic and gene-expression analysis with high resolution.
NASA Technical Reports Server (NTRS)
Balas, Mark; Frost, Susan
2012-01-01
Flexible structures containing a large number of modes can benefit from adaptive control techniques which are well suited to applications that have unknown modeling parameters and poorly known operating conditions. In this paper, we focus on a direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend our adaptive control theory to accommodate troublesome modal subsystems of a plant that might inhibit the adaptive controller. In some cases the plant does not satisfy the requirements of Almost Strict Positive Realness. Instead, there maybe be a modal subsystem that inhibits this property. This section will present new results for our adaptive control theory. We will modify the adaptive controller with a Residual Mode Filter (RMF) to compensate for the troublesome modal subsystem, or the Q modes. Here we present the theory for adaptive controllers modified by RMFs, with attention to the issue of disturbances propagating through the Q modes. We apply the theoretical results to a flexible structure example to illustrate the behavior with and without the residual mode filter.
Inside of the Linear Relation between Dependent and Independent Variables
Jäntschi, Lorentz; Pruteanu, Lavinia L.; Cozma, Alina C.; Bolboacă, Sorana D.
2015-01-01
Simple and multiple linear regression analyses are statistical methods used to investigate the link between activity/property of active compounds and the structural chemical features. One assumption of the linear regression is that the errors follow a normal distribution. This paper introduced a new approach to solving the simple linear regression in which no assumptions about the distribution of the errors are made. The proposed approach maximizes the probability of observing the event according to the random error. The use of the proposed approach is illustrated in ten classes of compounds with different activities or properties. The proposed method proved reliable and was showed to fit properly the observed data compared to the convenient approach of normal distribution of the errors. PMID:26101543
Inside of the Linear Relation between Dependent and Independent Variables.
Jäntschi, Lorentz; Pruteanu, Lavinia L; Cozma, Alina C; Bolboacă, Sorana D
2015-01-01
Simple and multiple linear regression analyses are statistical methods used to investigate the link between activity/property of active compounds and the structural chemical features. One assumption of the linear regression is that the errors follow a normal distribution. This paper introduced a new approach to solving the simple linear regression in which no assumptions about the distribution of the errors are made. The proposed approach maximizes the probability of observing the event according to the random error. The use of the proposed approach is illustrated in ten classes of compounds with different activities or properties. The proposed method proved reliable and was showed to fit properly the observed data compared to the convenient approach of normal distribution of the errors.
NASA Astrophysics Data System (ADS)
Ingebrigtsen, Trond S.; Schrøder, Thomas B.; Dyre, Jeppe C.
2012-01-01
This paper is an attempt to identify the real essence of simplicity of liquids in John Locke’s understanding of the term. Simple liquids are traditionally defined as many-body systems of classical particles interacting via radially symmetric pair potentials. We suggest that a simple liquid should be defined instead by the property of having strong correlations between virial and potential-energy equilibrium fluctuations in the NVT ensemble. There is considerable overlap between the two definitions, but also some notable differences. For instance, in the new definition simplicity is not a direct property of the intermolecular potential because a liquid is usually only strongly correlating in part of its phase diagram. Moreover, not all simple liquids are atomic (i.e., with radially symmetric pair potentials) and not all atomic liquids are simple. The main part of the paper motivates the new definition of liquid simplicity by presenting evidence that a liquid is strongly correlating if and only if its intermolecular interactions may be ignored beyond the first coordination shell (FCS). This is demonstrated by NVT simulations of the structure and dynamics of several atomic and three molecular model liquids with a shifted-forces cutoff placed at the first minimum of the radial distribution function. The liquids studied are inverse power-law systems (r-n pair potentials with n=18,6,4), Lennard-Jones (LJ) models (the standard LJ model, two generalized Kob-Andersen binary LJ mixtures, and the Wahnstrom binary LJ mixture), the Buckingham model, the Dzugutov model, the LJ Gaussian model, the Gaussian core model, the Hansen-McDonald molten salt model, the Lewis-Wahnstrom ortho-terphenyl model, the asymmetric dumbbell model, and the single-point charge water model. The final part of the paper summarizes properties of strongly correlating liquids, emphasizing that these are simpler than liquids in general. Simple liquids, as defined here, may be characterized in three quite
Non-Linear Approach in Kinesiology Should Be Preferred to the Linear--A Case of Basketball.
Trninić, Marko; Jeličić, Mario; Papić, Vladan
2015-07-01
In kinesiology, medicine, biology and psychology, in which research focus is on dynamical self-organized systems, complex connections exist between variables. Non-linear nature of complex systems has been discussed and explained by the example of non-linear anthropometric predictors of performance in basketball. Previous studies interpreted relations between anthropometric features and measures of effectiveness in basketball by (a) using linear correlation models, and by (b) including all basketball athletes in the same sample of participants regardless of their playing position. In this paper the significance and character of linear and non-linear relations between simple anthropometric predictors (AP) and performance criteria consisting of situation-related measures of effectiveness (SE) in basketball were determined and evaluated. The sample of participants consisted of top-level junior basketball players divided in three groups according to their playing time (8 minutes and more per game) and playing position: guards (N = 42), forwards (N = 26) and centers (N = 40). Linear (general model) and non-linear (general model) regression models were calculated simultaneously and separately for each group. The conclusion is viable: non-linear regressions are frequently superior to linear correlations when interpreting actual association logic among research variables.
Multidirectional direct simple shear apparatus
DeGroot, D.J.; Germaine, J.T.; Ladd, C.C.
1993-09-01
The paper describes a new simple shear testing device, the multidirectional direct simple shear (MDSS) apparatus, for testing soil specimens under conditions that simulate, at the element level, the state of stress acting within the foundation soil of an offshore Arctic gravity structure. The MDSS uses a circular specimen that is consolidated under both a vertical effective stress ({sigma}{sub vc}{prime}) and a horizontal shear stress ({tau}{sub 1}). The specimen is subsequently sheared undrained by applying a second independent horizontal shear stress ({tau}{sub 2}) at an angle {theta} relative to the horizontal consolidation shear stress {tau}{sub 1}. Evaluation of the MDSS first compares conventional K{sub D}-consolidated undrained direct simple shear (CK{sub 0}UDSS) test data ({tau}{sub 1} = 0) on normally consolidated Boston blue clay (BBC) with results obtained in the Geonor DSS device. The MDSS gives lower secant Young`s modulus values and on average 8% lower strengths, but produces remarkably less scatter in the test results than the Geonor DSS. Kinematic proof tests with an elastic material (rubber) confirm that the setup procedure, application of forces, and strain measurement systems in the MDSS work properly and produce repeatable results. Results from a MDSS test program on BBC wherein specimens were first normally consolidated with {sigma}{sub vc}{prime} and {tau}{sub 1} = 0.2{sigma}{sub vc}{prime} and then sheared undrained at {theta} varing in 30{degree} increments from zero (shear in same direction) to 150{degree} show dramatic differences in the response of the soil as a function of {theta}. The peak undrained strength varies almost twofold from 0 = 0 to 120{degree}, while the deformation behavior varies from very brittle at low {theta} angles to becoming ductile at higher angles. 11 refs., 15 figs.
A simple theory of condensation
Rabinovich, S.
2011-04-15
A simple assumption of the emergence in gas of small atomic clusters consisting of c particles each leads to a phase separation (first-order transition). It reveals itself by the emergence of a 'forbidden' density range starting at a certain temperature. Defining this latter value as the critical temperature predicts the existence of an interval with the anomalous heat capacity behavior c{sub p} {proportional_to} {Delta}T{sup -1/c}. The value c = 13 suggested in the literature yields the heat capacity exponent {alpha} = 0.077.
Simple sensor for potentiometric titrations
Selig, W.
1982-01-01
A sensor for potentiometric titrations was prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) and dioctylphthalate in tetrahydrofuran. The reference was an Ag/AgCl single-junction electrode. The sensor was used in the following potentiometric titrations: (1) precipitation titrations, (2) acid-base titrations, (3) compleximetric titrations, and (4) redox titrations. A survey of its use in such titrations is presented. Preparation of the coated-graphite sensor is simple and rapid. Moreover, it is quite inexpensive. A limitation is its applicability in aqueous media only, because organic solvents will dissolve the membrane. 5 figures, 4 tables.
Gedeon, Tomas; Murphy, Patrick
2015-10-01
We consider a simple food web with commensal relationship, where organisms utilize both external resources and resources produced by other organisms. We show that in such a community with no competition, there is at most one possible equilibrium for each fixed set of surviving species, and develop a natural condition that determines which species survive based on available resource. Our main result shows that among all possible communities described by equilibria, the one which is stable has the largest number of surviving species and largest combined biomass and hence maximizes utilization of available resources.
A simple Cavendish experimental apparatus
NASA Astrophysics Data System (ADS)
Kossler, W. J.; Klein, Susann; Morrow, Dominick; Juliao, Andre
2016-03-01
A simple Cavendish apparatus is described that allows measurement of the gravitational constant G and makes observable the gravitational attraction between commonplace objects. The apparatus consists of a torsion balance constructed from readily available materials, including lead bricks and fishing weights ("sinkers"). A computer program is used to determine the gravitational field at the location of the small mass due to a nearby lead brick, which allows students to gain experience with numerical methods. Experimental results obtained are compatible with the accepted value of G.
Controlling chaos with simple limiters
Corron; Pethel; Hopper
2000-04-24
New experimental results demonstrate that chaos control can be accomplished using controllers that are very simple relative to the system being controlled. Chaotic dynamics in a driven pendulum and a double scroll circuit are controlled using an adjustable, passive limiter-a weight for the pendulum and a diode for the circuit. For both experiments, multiple unstable periodic orbits are selectively controlled using minimal perturbations. These physical examples suggest that chaos control can be practically applied to a much wider array of important problems than initially thought possible. PMID:11019218
Simple Simulations of DNA Condensation
STEVENS,MARK J.
2000-07-12
Molecular dynamics simulations of a simple, bead-spring model of semiflexible polyelectrolytes such as DNA are performed. All charges are explicitly treated. Starting from extended, noncondensed conformations, condensed structures form in the simulations with tetravalent or trivalent counterions. No condensates form or are stable for divalent counterions. The mechanism by which condensates form is described. Briefly, condensation occurs because electrostatic interactions dominate entropy, and the favored Coulombic structure is a charge ordered state. Condensation is a generic phenomena and occurs for a variety of polyelectrolyte parameters. Toroids and rods are the condensate structures. Toroids form preferentially when the molecular stiffness is sufficiently strong.
A Simple Boyle's Law Experiment
NASA Astrophysics Data System (ADS)
Lewis, Don L.
1997-02-01
Student-conducted experiments over a range of pressures from about 14 psi to about 120 psi can safely and accurately be made utilizing a 60 ml syringe and an ordinary bathroom scale. No pressure gauge is required and no value for initial pressure in the syringe (near atmospheric pressure) need be assumed. Volume is measured in ml and pressures are recorded in pound/square inch. While data analysis does not require computer assistance, it is convenient to utilize spreadsheet programs which can perform linear regression calculations. The constant, c, in PV = c typically exhibits an uncertainty of about 5% (standard deviation/average).
Non-Linear Dynamics of Saturn's Rings
NASA Astrophysics Data System (ADS)
Esposito, Larry W.
2015-04-01
Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible Results of driven N-body systems by Stuart Robbins: Even unforced rings show large variations; Forcing triggers aggregation; Some limit cycles and phase lags seen, but not always as predicted by predator-prey model. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw'. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon
Non-Linear Dynamics of Saturn's Rings
NASA Astrophysics Data System (ADS)
Esposito, L. W.
2015-10-01
Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible. Results of driven N-body systems by Stuart Robbins: Even unforced rings show large variations; Forcing triggers aggregation; Some limit cycles and phase lags seen, but not always as predicted by predator-prey model. Summary of Halo Results: A predatorprey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw'. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon
Simple Cassegrain scanning system for infrared astronomy
NASA Technical Reports Server (NTRS)
Apt, J.; Goody, R.; Mertz, L.
1980-01-01
To meet the need for a reliable, fast imaging system capable of being taken rapidly on and off the telescope, a simple, inexpensive, and compact Cassegrain reimaging system for scanning IR images was constructed. Using commercially available components without requiring close mechanical tolerances, the design solves the problem of beam stability pointed out by Koornneef and van Overbeeke (1976). For the moving-iron galvanometer scanner, it is noted that at the imaging frequency of 0.5 Hz, hysteresis in image plane motion was found to be less than 0.2 arc sec for a 64-arc sec scan, and the deviation from linearity with a triangular wave input was found to be less than 0.3 arc sec. This system and a scanning secondary were used to image Venus at 11.5 microns, and compared with the scanning secondary, the reimaging system did not appear to contribute any additional noise, considerably improved mechanical reliability, and eliminated cross-scan motion
Linear Algebraic Method for Non-Linear Map Analysis
Yu,L.; Nash, B.
2009-05-04
We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a matrix analysis method from linear algebra. Choosing the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of Jordan decomposition which is widely used in conventional linear algebra.
Capture zones for simple aquifers
McElwee, Carl D.
1991-01-01
Capture zones showing the area influenced by a well within a certain time are useful for both aquifer protection and cleanup. If hydrodynamic dispersion is neglected, a deterministic curve defines the capture zone. Analytical expressions for the capture zones can be derived for simple aquifers. However, the capture zone equations are transcendental and cannot be explicitly solved for the coordinates of the capture zone boundary. Fortunately, an iterative scheme allows the solution to proceed quickly and efficiently even on a modest personal computer. Three forms of the analytical solution must be used in an iterative scheme to cover the entire region of interest, after the extreme values of the x coordinate are determined by an iterative solution. The resulting solution is a discrete one, and usually 100-1000 intervals along the x-axis are necessary for a smooth definition of the capture zone. The presented program is written in FORTRAN and has been used in a variety of computing environments. No graphics capability is included with the program; it is assumed the user has access to a commercial package. The superposition of capture zones for multiple wells is expected to be satisfactory if the spacing is not too close. Because this program deals with simple aquifers, the results rarely will be the final word in a real application.
User's manual for interfacing a leading edge, vortex rollup program with two linear panel methods
NASA Technical Reports Server (NTRS)
Desilva, B. M. E.; Medan, R. T.
1979-01-01
Sufficient instructions are provided for interfacing the Mangler-Smith, leading edge vortex rollup program with a vortex lattice (POTFAN) method and an advanced higher order, singularity linear analysis for computing the vortex effects for simple canard wing combinations.
NASA Technical Reports Server (NTRS)
Holloway, Sidney E., III; Crossley, Edward A.; Miller, James B.; Jones, Irby W.; Davis, C. Calvin; Behun, Vaughn D.; Goodrich, Lewis R., Sr.
1995-01-01
Linear proof-mass actuator (LPMA) is friction-driven linear mass actuator capable of applying controlled force to structure in outer space to damp out oscillations. Capable of high accelerations and provides smooth, bidirectional travel of mass. Design eliminates gears and belts. LPMA strong enough to be used terrestrially where linear actuators needed to excite or damp out oscillations. High flexibility designed into LPMA by varying size of motors, mass, and length of stroke, and by modifying control software.
A simple ice nucleation spectrometer.
Wharton, David A; Mutch, Jodi S; Wilson, Peter W; Marshall, Craig J; Lim, Miang
2004-01-01
The construction of a simple ice nucleation spectrometer is described. It uses 10 microliter droplets loaded into glass capillary tubes which are then inserted into an aluminium holder. Each holder takes six capillary tubes surrounding a central thermocouple. Four holders are placed into a cooling block, cooled by fluid from a programmable refrigerated circulator, and the thermocouples interfaced to a computer to record temperatures. Freezing of each sample is detected by an exotherm on the temperature recording, with 24 samples recorded per run. The spectrometer was tested using deionized water, an extract from a New Zealand alpine cockroach and an extract of lawn grass. The cockroach extract is estimated to contain about 10(3) more nucleators, active at -5 degrees C, than the grass extract. PMID:15618985
Simple photoreceptors in Limulus polyphemus.
Millecchia, R; Bradbury, J; Mauro, A
1966-12-01
The "olfactory nerve," the endoparietal eye, and the rudimentary lateral eyes of Limulus (polyphemus) contain simple photoreceptor cells that duplicate many of the electrical responses of the retinular cells of the lateral eye; the responses are a receptor potential consisting of aninitial transient phase and a subsequent steady phase,low-amplitude fluctuations, and a small locally regenerative response to pulses of both light and current. Photic stimulation does not induce conducted action potentials, but does increase the membrane conductance. The receptor potentialrequires the presence of sodium ions in the external medium. Measurements of action and absorption spectra indicate a photopigment whose maximum absorption is of light with wavelength of 535 nanometers. The functional significance of these cells has not been ascertained. PMID:5921383
Simple lattice model of macroevolution
NASA Astrophysics Data System (ADS)
Borkowski, Wojciech
2009-04-01
In future astrobiology, like in modern astrophysics, the numerical simulations can be a very important tool for proving theories. In this paper, I propose a simple lattice model of a multi-species ecosystem suitable for the study of emergent properties of macroevolution. Unlike the majority of ecological models, the number of species is not fixed - they emerge by "mutation" of existing species, then survive or go extinct depending on the balance between local ecological interactions. The Monte-Carlo numerical simulations show that this model is able to qualitatively reproduce phenomena that have been empirically observed, like the dependence between size of the isolated area and the number of species inhabiting there, primary production and species-diversity. The model allows also studying the causes of mass extinctions and more generally, repeatability, and the role of pure chance in macroevolution.
Simple cyst of urinary bladder.
Bo, Yang
2014-07-01
Simple cysts are rare in the urinary bladder and can pose a diagnostic dilemma to both the urologist and the histopathologist. No case study was found in the database of Elsevier Science Direct, Spring-Link, or PubMed. We present two cases of subserous cyst in the bladder and discuss the diagnosis and treatment of the condition. The cystic lesion at bladder dome was detected by radiologic examination and confirmed by cystoscopy. In case 1, transurethral resection was first performed which was followed by partial cystectomy; In case 2, the cyst was removed with the urachus using laparoscopic surgery. The patients recovered uneventfully and the histopathology showed cysts in subserous layer of urinary bladder. The bladder cyst should be distinguished from urachal tumor, and laparoscopic partial cystectomy is the preferred operative procedure.
Linear collider development at SLAC
Irwin, J.
1993-08-01
Linear collider R&D at SLAC comprises work on the present Stanford Linear Collider (SLC) and work toward the next linear collider (NLC). Recent SLC developments are summarized. NLC studies are divided into hardware-based and theoretical. We report on the status of the NLC Test Accelerator (NLCTA) and the final focus test beam (FFTB), describe plans for ASSET, an installation to measure accelerator structure wakefields, and mention IR design developments. Finally we review recent NLC theoretical studies, ending with the author`s view of next linear collider parameter sets.
Quantization of general linear electrodynamics
Rivera, Sergio; Schuller, Frederic P.
2011-03-15
General linear electrodynamics allow for an arbitrary linear constitutive relation between the field strength 2-form and induction 2-form density if crucial hyperbolicity and energy conditions are satisfied, which render the theory predictive and physically interpretable. Taking into account the higher-order polynomial dispersion relation and associated causal structure of general linear electrodynamics, we carefully develop its Hamiltonian formulation from first principles. Canonical quantization of the resulting constrained system then results in a quantum vacuum which is sensitive to the constitutive tensor of the classical theory. As an application we calculate the Casimir effect in a birefringent linear optical medium.
Linear equality constraints in the general linear mixed model.
Edwards, L J; Stewart, P W; Muller, K E; Helms, R W
2001-12-01
Scientists may wish to analyze correlated outcome data with constraints among the responses. For example, piecewise linear regression in a longitudinal data analysis can require use of a general linear mixed model combined with linear parameter constraints. Although well developed for standard univariate models, there are no general results that allow a data analyst to specify a mixed model equation in conjunction with a set of constraints on the parameters. We resolve the difficulty by precisely describing conditions that allow specifying linear parameter constraints that insure the validity of estimates and tests in a general linear mixed model. The recommended approach requires only straightforward and noniterative calculations to implement. We illustrate the convenience and advantages of the methods with a comparison of cognitive developmental patterns in a study of individuals from infancy to early adulthood for children from low-income families.
Mass transfer coefficients determination from linear gradient elution experiments.
Pfister, David; Morbidelli, Massimo
2015-01-01
A procedure to estimate mass transfer coefficients in linear gradient elution chromatography is presented and validated by comparison with experimental data. Mass transfer coefficients are traditionally estimated experimentally through the van Deemter plot, which represents the HETP as a function of the fluid velocity. Up to now, the HETP was obtained under isocratic elution conditions. Unfortunately, isocratic elution experiments are often not suitable for large biomolecules which suffer from severe mass transfer hindrances. Yamamoto et al. were the first to propose a semi-empirical equation to relate HETPs measured from linear gradient elution experiments to those obtained under isocratic conditions [7]. Based on his pioneering work, the approach presented in this work aims at providing an experimental procedure supported by simple equations to estimate reliable mass transfer parameters from linear gradient elution chromatographic experiments. From the resolution of the transport model, we derived a rigorous analytical expression for the HETP in linear gradient elution chromatography.
Linear Algebra and Image Processing
ERIC Educational Resources Information Center
Allali, Mohamed
2010-01-01
We use the computing technology digital image processing (DIP) to enhance the teaching of linear algebra so as to make the course more visual and interesting. Certainly, this visual approach by using technology to link linear algebra to DIP is interesting and unexpected to both students as well as many faculty. (Contains 2 tables and 11 figures.)
Linear algebra and image processing
NASA Astrophysics Data System (ADS)
Allali, Mohamed
2010-09-01
We use the computing technology digital image processing (DIP) to enhance the teaching of linear algebra so as to make the course more visual and interesting. Certainly, this visual approach by using technology to link linear algebra to DIP is interesting and unexpected to both students as well as many faculty.
Linear Programming across the Curriculum
ERIC Educational Resources Information Center
Yoder, S. Elizabeth; Kurz, M. Elizabeth
2015-01-01
Linear programming (LP) is taught in different departments across college campuses with engineering and management curricula. Modeling an LP problem is taught in every linear programming class. As faculty teaching in Engineering and Management departments, the depth to which teachers should expect students to master this particular type of…
Passive linearization of nonlinear resonances
NASA Astrophysics Data System (ADS)
Habib, G.; Grappasonni, C.; Kerschen, G.
2016-07-01
The objective of this paper is to demonstrate that the addition of properly tuned nonlinearities to a nonlinear system can increase the range over which a specific resonance responds linearly. Specifically, we seek to enforce two important properties of linear systems, namely, the force-displacement proportionality and the invariance of resonance frequencies. Numerical simulations and experiments are used to validate the theoretical findings.
Spatial Processes in Linear Ordering
ERIC Educational Resources Information Center
von Hecker, Ulrich; Klauer, Karl Christoph; Wolf, Lukas; Fazilat-Pour, Masoud
2016-01-01
Memory performance in linear order reasoning tasks (A > B, B > C, C > D, etc.) shows quicker, and more accurate responses to queries on wider (AD) than narrower (AB) pairs on a hypothetical linear mental model (A -- B -- C -- D). While indicative of an analogue representation, research so far did not provide positive evidence for spatial…
Efficient multiscale simulation of simple metallic systems
NASA Astrophysics Data System (ADS)
Choly, Nicholas Isaac
2004-12-01
scales quasi-linearly (O(N log N)) with the system size. We develop and examine a multiscale method for the simulation of simple metallic systems. Part of the system is treated quantum-mechanically, and part classically, with consideration made to the coupling of the two. We apply this method to several physical systems.
Analysis of linear trade models and relation to scale economies
Gomory, Ralph E.; Baumol, William J.
1997-01-01
We discuss linear Ricardo models with a range of parameters. We show that the exact boundary of the region of equilibria of these models is obtained by solving a simple integer programming problem. We show that there is also an exact correspondence between many of the equilibria resulting from families of linear models and the multiple equilibria of economies of scale models. PMID:11038573
Ogawa, Takahiro; Usuki, Naoya; Nakazono, Kazuko; Koyama, Yasuhito; Takata, Toshikazu
2015-04-01
Linear-cyclic polymer structural transformation and its reversibility are demonstrated by a simple but rational strategy using the structural characteristics of crown ether-based rotaxanes. The structure of a polymer containing a [1]rotaxane unit at one end was controlled by conventional protection-deprotection reactions, giving rise to a reversible linear-cyclic polymer structural transformation. PMID:25531061
Ogawa, Takahiro; Usuki, Naoya; Nakazono, Kazuko; Koyama, Yasuhito; Takata, Toshikazu
2015-04-01
Linear-cyclic polymer structural transformation and its reversibility are demonstrated by a simple but rational strategy using the structural characteristics of crown ether-based rotaxanes. The structure of a polymer containing a [1]rotaxane unit at one end was controlled by conventional protection-deprotection reactions, giving rise to a reversible linear-cyclic polymer structural transformation.
A Simple Demonstration Model of Osmosis
NASA Astrophysics Data System (ADS)
Morse, Joseph G.
1999-01-01
A simple device constructed from a wire screen, a large beaker, beans, and oats is described. It provides a simple and effective visual model of the phenomenon of osmosis and, by extension, the origin of other colligative properties of solutions.
Simple Solutions for Treating Dry Mouth
Patient Education Sheet Simple Solutions for Treating Dry Mouth Clinicians: Please make as many copies of this ... Philadelphia, for authoring “Simple Solutions for Treating Dry Mouth.” Ask your family doctor to discontinue or provide ...
Simple method for model reference adaptive control
NASA Technical Reports Server (NTRS)
Seraji, H.
1989-01-01
A simple method is presented for combined signal synthesis and parameter adaptation within the framework of model reference adaptive control theory. The results are obtained using a simple derivation based on an improved Liapunov function.
Simple molecules as complex systems.
Furtenbacher, Tibor; Arendás, Péter; Mellau, Georg; Császár, Attila G
2014-01-01
For individual molecules quantum mechanics (QM) offers a simple, natural and elegant way to build large-scale complex networks: quantized energy levels are the nodes, allowed transitions among the levels are the links, and transition intensities supply the weights. QM networks are intrinsic properties of molecules and they are characterized experimentally via spectroscopy; thus, realizations of QM networks are called spectroscopic networks (SN). As demonstrated for the rovibrational states of H2(16)O, the molecule governing the greenhouse effect on earth through hundreds of millions of its spectroscopic transitions (links), both the measured and first-principles computed one-photon absorption SNs containing experimentally accessible transitions appear to have heavy-tailed degree distributions. The proposed novel view of high-resolution spectroscopy and the observed degree distributions have important implications: appearance of a core of highly interconnected hubs among the nodes, a generally disassortative connection preference, considerable robustness and error tolerance, and an "ultra-small-world" property. The network-theoretical view of spectroscopy offers a data reduction facility via a minimum-weight spanning tree approach, which can assist high-resolution spectroscopists to improve the efficiency of the assignment of their measured spectra.
Asymptotic safety: A simple example
NASA Astrophysics Data System (ADS)
Braun, Jens; Gies, Holger; Scherer, Daniel D.
2011-04-01
We use the Gross-Neveu model in 2
Simple molecules as complex systems
Furtenbacher, Tibor; Árendás, Péter; Mellau, Georg; Császár, Attila G.
2014-01-01
For individual molecules quantum mechanics (QM) offers a simple, natural and elegant way to build large-scale complex networks: quantized energy levels are the nodes, allowed transitions among the levels are the links, and transition intensities supply the weights. QM networks are intrinsic properties of molecules and they are characterized experimentally via spectroscopy; thus, realizations of QM networks are called spectroscopic networks (SN). As demonstrated for the rovibrational states of H216O, the molecule governing the greenhouse effect on earth through hundreds of millions of its spectroscopic transitions (links), both the measured and first-principles computed one-photon absorption SNs containing experimentally accessible transitions appear to have heavy-tailed degree distributions. The proposed novel view of high-resolution spectroscopy and the observed degree distributions have important implications: appearance of a core of highly interconnected hubs among the nodes, a generally disassortative connection preference, considerable robustness and error tolerance, and an “ultra-small-world” property. The network-theoretical view of spectroscopy offers a data reduction facility via a minimum-weight spanning tree approach, which can assist high-resolution spectroscopists to improve the efficiency of the assignment of their measured spectra. PMID:24722221
Asymptotic safety: A simple example
Braun, Jens; Gies, Holger; Scherer, Daniel D.
2011-04-15
We use the Gross-Neveu model in 2
Some results concerning linear iterative (systolic) arrays
Ibarra, O.H.; Palis, M.A.; Kim, S.M.
1985-05-01
The authors have shown some new interesting results concerning the properties, power, and limitations of various types of linear iterative (systolic) arrays. The method they employed consisted of finding sequential machine characterizations of these array models, and then using the characterizations to prove the results. Because of the absence of any concurrency and synchronization problems, the authors obtained simple proofs to results which when proved directly on the arrays would seem very difficult. The characterizations, therefore, provide a novel and promising method which can be used to analyze other systolic systems. In the future they hope to extend this methodology to the study of two-dimensional and multidimensional systolic arrays, and other systolic systems with different interconnection networks.
Stochastic robustness of linear control systems
NASA Technical Reports Server (NTRS)
Stengel, Robert F.; Ryan, Laura E.
1990-01-01
A simple numerical procedure for estimating the stochastic robustness of a linear, time-invariant system is described. Monte Carlo evaluation of the system's eigenvalues allows the probability of instability and the related stochastic root locus to be estimated. This definition of robustness is an alternative to existing deterministic definitions that address both structured and unstructured parameter variations directly. This analysis approach treats not only Gaussian parameter uncertainties but non-Gaussian cases, including uncertain-but-bounded variations. Trivial extensions of the procedure admit alternate discriminants to be considered. Thus, the probabilities that stipulated degrees of instability will be exceeded or that closed-loop roots will leave desirable regions also can be estimated. Results are particularly amenable to graphical presentation.
Robust Control Design via Linear Programming
NASA Technical Reports Server (NTRS)
Keel, L. H.; Bhattacharyya, S. P.
1998-01-01
This paper deals with the problem of synthesizing or designing a feedback controller of fixed dynamic order. The closed loop specifications considered here are given in terms of a target performance vector representing a desired set of closed loop transfer functions connecting various signals. In general these point targets are unattainable with a fixed order controller. By enlarging the target from a fixed point set to an interval set the solvability conditions with a fixed order controller are relaxed and a solution is more easily enabled. Results from the parametric robust control literature can be used to design the interval target family so that the performance deterioration is acceptable, even when plant uncertainty is present. It is shown that it is possible to devise a computationally simple linear programming approach that attempts to meet the desired closed loop specifications.
Micro digital sun sensor with linear detector.
Fan, Qiao-Yun; Peng, Jia-Wen; Gao, Xin-Yang
2016-07-01
In this paper, the design of a novel micro digital sun sensor is described. It relies on V-shaped slit and linear array CCD to measure sun-ray angle against two axes. A highly integrated microprogram control unit) is used to make a very simple and compact system. V-shaped slit can simplify algorithm and achieve a wider field of view. Error compensation and accurate calibration are employed to improve accuracy. Adaptive threshold and adjustable expose time further improve reliability. Experiments and flight validation show that the FOV (Field of View) of the sun sensor is ±65° × ± 65° and the accuracy is 0.1° in the whole FOV. It can work reliably at an update rate of 25 Hz, while the consumption is only 200 mW. This sun sensor is proved to have a good prospect in micro/nanosatellites.
A magnetically suspended linearly driven cryogenic refrigerator
NASA Technical Reports Server (NTRS)
Stolfi, F.; Goldowsky, M.; Ricciardelli, J.; Shapiro, P.
1983-01-01
This paper described a novel Stirling cycle cryogenic refrigerator which was designed, fabricated and successfully tested at Philips Laboratories. The prominent features of the machine are an electro-magnetic bearing system, a pair of moving magnet linear motors, and clearance seals with a 25 mu m radial gap. The all-metal and ceramic construction eliminates long-term organic contamination of the helium working fluid. The axial positions of the piston and displacer are electronically controlled, permitting independent adjustment of the amplitude of each and their relative phase relationship during operation. A simple passive counterbalance reduces axial vibrations. The design of the refrigerator system components is discussed and a comparison is made between performance estimates and measured results.
Micro digital sun sensor with linear detector
NASA Astrophysics Data System (ADS)
Fan, Qiao-yun; Peng, Jia-wen; Gao, Xin-yang
2016-07-01
In this paper, the design of a novel micro digital sun sensor is described. It relies on V-shaped slit and linear array CCD to measure sun-ray angle against two axes. A highly integrated microprogram control unit) is used to make a very simple and compact system. V-shaped slit can simplify algorithm and achieve a wider field of view. Error compensation and accurate calibration are employed to improve accuracy. Adaptive threshold and adjustable expose time further improve reliability. Experiments and flight validation show that the FOV (Field of View) of the sun sensor is ±65° × ± 65° and the accuracy is 0.1° in the whole FOV. It can work reliably at an update rate of 25 Hz, while the consumption is only 200 mW. This sun sensor is proved to have a good prospect in micro/nanosatellites.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts tomore » adiabaticity for specific and very short driving times.« less
Numerical linearized MHD model of flapping oscillations
NASA Astrophysics Data System (ADS)
Korovinskiy, D. B.; Ivanov, I. B.; Semenov, V. S.; Erkaev, N. V.; Kiehas, S. A.
2016-06-01
Kink-like magnetotail flapping oscillations in a Harris-like current sheet with earthward growing normal magnetic field component Bz are studied by means of time-dependent 2D linearized MHD numerical simulations. The dispersion relation and two-dimensional eigenfunctions are obtained. The results are compared with analytical estimates of the double-gradient model, which are found to be reliable for configurations with small Bz up to values ˜ 0.05 of the lobe magnetic field. Coupled with previous results, present simulations confirm that the earthward/tailward growth direction of the Bz component acts as a switch between stable/unstable regimes of the flapping mode, while the mode dispersion curve is the same in both cases. It is confirmed that flapping oscillations may be triggered by a simple Gaussian initial perturbation of the Vz velocity.
Micro digital sun sensor with linear detector.
Fan, Qiao-Yun; Peng, Jia-Wen; Gao, Xin-Yang
2016-07-01
In this paper, the design of a novel micro digital sun sensor is described. It relies on V-shaped slit and linear array CCD to measure sun-ray angle against two axes. A highly integrated microprogram control unit) is used to make a very simple and compact system. V-shaped slit can simplify algorithm and achieve a wider field of view. Error compensation and accurate calibration are employed to improve accuracy. Adaptive threshold and adjustable expose time further improve reliability. Experiments and flight validation show that the FOV (Field of View) of the sun sensor is ±65° × ± 65° and the accuracy is 0.1° in the whole FOV. It can work reliably at an update rate of 25 Hz, while the consumption is only 200 mW. This sun sensor is proved to have a good prospect in micro/nanosatellites. PMID:27475588
Pyroelectric linear array sensor for object recognition
NASA Astrophysics Data System (ADS)
Chari, Srikant; Jacobs, Eddie L.; Choudhary, Divya
2014-02-01
This paper presents a proof of concept sensor system based on a linear array of pyroelectric detectors for recognition of moving objects. The utility of this prototype sensor is demonstrated by its use in trail monitoring and perimeter protection applications for classifying humans against animals with object motion transverse to the field of view of the sensor array. Data acquisition using the system was performed under varied terrains and using a wide variety of animals and humans. With the objective of eventually porting the algorithms onto a low resource computational platform, simple signal processing, feature extraction, and classification techniques are used. The object recognition algorithm uses a combination of geometrical and texture features to provide limited insensitivity to range and speed. Analysis of system performance shows its effectiveness in discriminating humans and animals with high classification accuracy.
A New Simple Chaotic Circuit Based on Memristor
NASA Astrophysics Data System (ADS)
Wu, Renping; Wang, Chunhua
In this paper, a new memristor is proposed, and then an emulator built from off-the-shelf solid state components imitating the behavior of the proposed memristor is presented. Multisim simulation and breadboard experiment are done on the emulator, exhibiting a pinched hysteresis loop in the voltage-current plane when the emulator is driven by a periodic excitation voltage. In addition, a new simple chaotic circuit is designed by using the proposed memristor and other circuit elements. It is exciting that this circuit with only a linear negative resistor, a capacitor, an inductor and a memristor can generate a chaotic attractor. The dynamical behaviors of the proposed chaotic system are analyzed by Lyapunov exponents, phase portraits and bifurcation diagrams. Finally, an electronic circuit is designed to implement the chaotic system. For the sake of simple circuit topology, the proposed chaotic circuit can be easily manufactured at low cost.
Simple cost model for EV traction motors
Cuenca, R.M.
1995-02-01
A simple cost model has been developed that allows the calculation of the OEM cost of electric traction motors of three different types, normalized as a function of power in order to accommodate different power and size. The model includes enough information on the various elements integrated in the motors to allow analysis of individual components and to factor-in the effects of changes in commodities prices. A scalable cost model for each of the main components of an electric vehicle (EV) is a useful tool that can have direct application in computer simulation or in parametric studies. For the cost model to have wide usefulness, it needs to be valid for a range of values of some parameter that determines the magnitude or size of the component. For instance, in the case of batteries, size may be determined by energy capacity, usually expressed in kilowatt-hours (kWh), while in the case of traction motors, size is better determined by rated power, usually expressed in kilowatts (kW). The simplest case is when the cost of the component in question is a direct function of its size; then cost is simply the product of its specific cost ($/unit size) and the number of units (size) in the vehicle in question. Batteries usually fall in this category (cost = energy capacity x $/kWh). But cost is not always linear with size or magnitude; motors (and controllers), for instance, become relatively less expensive as power rating increases. Traction motors, one of the main components for EV powertrains are examined in this paper, and a simplified cost model is developed for the three most popular design variations.
Novel linear piezoelectric motor for precision position stage
NASA Astrophysics Data System (ADS)
Chen, Chao; Shi, Yunlai; Zhang, Jun; Wang, Junshan
2016-03-01
Conventional servomotor and stepping motor face challenges in nanometer positioning stages due to the complex structure, motion transformation mechanism, and slow dynamic response, especially directly driven by linear motor. A new butterfly-shaped linear piezoelectric motor for linear motion is presented. A two-degree precision position stage driven by the proposed linear ultrasonic motor possesses a simple and compact configuration, which makes the system obtain shorter driving chain. Firstly, the working principle of the linear ultrasonic motor is analyzed. The oscillation orbits of two driving feet on the stator are produced successively by using the anti-symmetric and symmetric vibration modes of the piezoelectric composite structure, and the slider pressed on the driving feet can be propelled twice in only one vibration cycle. Then with the derivation of the dynamic equation of the piezoelectric actuator and transient response model, start-upstart-up and settling state characteristics of the proposed linear actuator is investigated theoretically and experimentally, and is applicable to evaluate step resolution of the precision platform driven by the actuator. Moreover the structure of the two-degree position stage system is described and a special precision displacement measurement system is built. Finally, the characteristics of the two-degree position stage are studied. In the closed-loop condition the positioning accuracy of plus or minus <0.5 μm is experimentally obtained for the stage propelled by the piezoelectric motor. A precision position stage based the proposed butterfly-shaped linear piezoelectric is theoretically and experimentally investigated.
A Simple Model of Global Aerosol Indirect Effects
NASA Technical Reports Server (NTRS)
Ghan, Steven J.; Smith, Steven J.; Wang, Minghuai; Zhang, Kai; Pringle, Kirsty; Carslaw, Kenneth; Pierce, Jeffrey; Bauer, Susanne; Adams, Peter
2013-01-01
Most estimates of the global mean indirect effect of anthropogenic aerosol on the Earth's energy balance are from simulations by global models of the aerosol lifecycle coupled with global models of clouds and the hydrologic cycle. Extremely simple models have been developed for integrated assessment models, but lack the flexibility to distinguish between primary and secondary sources of aerosol. Here a simple but more physically based model expresses the aerosol indirect effect (AIE) using analytic representations of cloud and aerosol distributions and processes. Although the simple model is able to produce estimates of AIEs that are comparable to those from some global aerosol models using the same global mean aerosol properties, the estimates by the simple model are sensitive to preindustrial cloud condensation nuclei concentration, preindustrial accumulation mode radius, width of the accumulation mode, size of primary particles, cloud thickness, primary and secondary anthropogenic emissions, the fraction of the secondary anthropogenic emissions that accumulates on the coarse mode, the fraction of the secondary mass that forms new particles, and the sensitivity of liquid water path to droplet number concentration. Estimates of present-day AIEs as low as 5 W/sq m and as high as 0.3 W/sq m are obtained for plausible sets of parameter values. Estimates are surprisingly linear in emissions. The estimates depend on parameter values in ways that are consistent with results from detailed global aerosol-climate simulation models, which adds to understanding of the dependence on AIE uncertainty on uncertainty in parameter values.
A simple white noise analysis of neuronal light responses.
Chichilnisky, E J
2001-05-01
A white noise technique is presented for estimating the response properties of spiking visual system neurons. The technique is simple, robust, efficient and well suited to simultaneous recordings from multiple neurons. It provides a complete and easily interpretable model of light responses even for neurons that display a common form of response nonlinearity that precludes classical linear systems analysis. A theoretical justification of the technique is presented that relies only on elementary linear algebra and statistics. Implementation is described with examples. The technique and the underlying model of neural responses are validated using recordings from retinal ganglion cells, and in principle are applicable to other neurons. Advantages and disadvantages of the technique relative to classical approaches are discussed. PMID:11405422
Non-linearity in Bayesian 1-D magnetotelluric inversion
NASA Astrophysics Data System (ADS)
Guo, Rongwen; Dosso, Stan E.; Liu, Jianxin; Dettmer, Jan; Tong, Xiaozhong
2011-05-01
This paper applies a Bayesian approach to examine non-linearity for the 1-D magnetotelluric (MT) inverse problem. In a Bayesian formulation the posterior probability density (PPD), which combines data and prior information, is interpreted in terms of parameter estimates and uncertainties, which requires optimizing and integrating the PPD. Much work on 1-D MT inversion has been based on (approximate) linearized solutions, but more recently fully non-linear (numerical) approaches have been applied. This paper directly compares results of linearized and non-linear uncertainty estimation for 1-D MT inversion; to do so, advanced methods for both approaches are applied. In the non-linear formulation used here, numerical optimization is carried out using an adaptive-hybrid algorithm. Numerical integration applies Metropolis-Hastings sampling, rotated to a principal-component parameter space for efficient sampling of correlated parameters, and employing non-unity sampling temperatures to ensure global sampling. Since appropriate model parametrizations are generally not known a priori, both under- and overparametrized approaches are considered. For underparametrization, the Bayesian information criterion is applied to determine the number of layers consistent with the resolving power of the data. For overparametrization, prior information is included which favours simple structure in a manner similar to regularized inversion. The data variance and/or trade-off parameter regulating data and prior information are treated in several ways, including applying fixed optimal estimates (an empirical Bayesian approach) or including them as hyperparameters in the sampling (hierarchical Bayesian). The latter approach has the benefit of accounting for the uncertainty in the hyperparameters in estimating model parameter uncertainties. Non-linear and linearized inversion results are compared for synthetic test cases and for the measured COPROD1 MT data by considering marginal probability
"You Can't Always Get What You Want" - Linearity as the Golden Ratio of Toxicology.
Bast, Aalt; Hanekamp, Jaap C
2014-12-01
Referring to the Golden Ratio (i.e. expressed in the Fibonacci sequence) in nature and art, we conclude that toxicology knows its own Golden Ration, namely linearity. The latter seems imposed on pharmaco-toxicological processes that in fact show far more complexity than simple linearity could hope to elucidate. Understanding physiological and pharmaco-toxicological processes as primarily linear is challenged in this contribution based on very straightforward principles and examples. PMID:25552963
A self-saturating mechanical oscillator with linear feedback
NASA Astrophysics Data System (ADS)
Chen, Changyao; Zanette, Damian; Czaplewski, David; Guest, Jeffrey; Lopez, Daniel
Oscillators, opposed to resonators, produce a prescribed periodic signal without any external frequency reference. In order to maintain stable oscillations, there needs to be an amplitude limiting mechanism, which is usually realized by saturating at least one of the sustaining amplifiers. Here we demonstrate a simple oscillator structure that solely relies on the nonlinearity inherent to the constituent mechanical resonator to limit the oscillating amplitude, while the performance of the feedback loop remains in the linear regime. To validate the model, we experimentally demonstrate the principle using a non-linear silicon microelectromechanical (MEMS) resonator, and perform comprehensive characterizations that agree well with the theoretical predictions.
INTEGRATING A LINEAR INTERPOLATION FUNCTION ACROSS TRIANGULAR CELL BOUNDARIES
J. R. WISEMAN; J. S. BROCK
2000-04-01
Computational models of particle dynamics often exchange solution data with discretized continuum-fields using interpolation functions. These particle methods require a series expansion of the interpolation function for two purposes: numerical analysis used to establish the model's consistency and accuracy, and logical-coordinate evaluation used to locate particles within a grid. This report presents discrete-expansions for a linear interpolation function commonly used within triangular cell geometries. Discrete-expansions, unlike a Taylor's series, account for interpolation discontinuities across cell boundaries and, therefore, are valid throughout a discretized domain. Verification of linear discrete-expansions is demonstrated on a simple test problem.
NASA Technical Reports Server (NTRS)
Ferencz, Donald C.; Viterna, Larry A.
1991-01-01
ALPS is a computer program which can be used to solve general linear program (optimization) problems. ALPS was designed for those who have minimal linear programming (LP) knowledge and features a menu-driven scheme to guide the user through the process of creating and solving LP formulations. Once created, the problems can be edited and stored in standard DOS ASCII files to provide portability to various word processors or even other linear programming packages. Unlike many math-oriented LP solvers, ALPS contains an LP parser that reads through the LP formulation and reports several types of errors to the user. ALPS provides a large amount of solution data which is often useful in problem solving. In addition to pure linear programs, ALPS can solve for integer, mixed integer, and binary type problems. Pure linear programs are solved with the revised simplex method. Integer or mixed integer programs are solved initially with the revised simplex, and the completed using the branch-and-bound technique. Binary programs are solved with the method of implicit enumeration. This manual describes how to use ALPS to create, edit, and solve linear programming problems. Instructions for installing ALPS on a PC compatible computer are included in the appendices along with a general introduction to linear programming. A programmers guide is also included for assistance in modifying and maintaining the program.
SSL - THE SIMPLE SOCKETS LIBRARY
NASA Technical Reports Server (NTRS)
Campbell, C. E.
1994-01-01
The Simple Sockets Library (SSL) allows C programmers to develop systems of cooperating programs using Berkeley streaming Sockets running under the TCP/IP protocol over Ethernet. The SSL provides a simple way to move information between programs running on the same or different machines and does so with little overhead. The SSL can create three types of Sockets: namely a server, a client, and an accept Socket. The SSL's Sockets are designed to be used in a fashion reminiscent of the use of FILE pointers so that a C programmer who is familiar with reading and writing files will immediately feel comfortable with reading and writing with Sockets. The SSL consists of three parts: the library, PortMaster, and utilities. The user of the SSL accesses it by linking programs to the SSL library. The PortMaster initializes connections between clients and servers. The PortMaster also supports a "firewall" facility to keep out socket requests from unapproved machines. The "firewall" is a file which contains Internet addresses for all approved machines. There are three utilities provided with the SSL. SKTDBG can be used to debug programs that make use of the SSL. SPMTABLE lists the servers and port numbers on requested machine(s). SRMSRVR tells the PortMaster to forcibly remove a server name from its list. The package also includes two example programs: multiskt.c, which makes multiple accepts on one server, and sktpoll.c, which repeatedly attempts to connect a client to some server at one second intervals. SSL is a machine independent library written in the C-language for computers connected via Ethernet using the TCP/IP protocol. It has been successfully compiled and implemented on a variety of platforms, including Sun series computers running SunOS, DEC VAX series computers running VMS, SGI computers running IRIX, DECstations running ULTRIX, DEC alpha AXPs running OSF/1, IBM RS/6000 computers running AIX, IBM PC and compatibles running BSD/386 UNIX and HP Apollo 3000
Colligative properties of simple solutions.
Andrews, F C
1976-11-01
Vapor pressure lowering, osmotic pressure, boiling point elevation, and freezing point depression are all related quantitatively to the decrease in micro(1)(soln) upon the addition of solute in forming a solution. In any equilibrium system, regardless of whether it is in a gravitational field or whether it contains walls, semipermeable membranes, phase transitions, or solutes, all equilibria are maintained locally, in the small region of the equilibrium, by the equality of micro(1)(soln). If there are several subsystems in a gravitational field, at any fixed height, microi will have the same value in each subsystem into which substance i can get, and microi + M(i)gh is constant throughout the entire system. In a solution, there is no mechanism by which solvent and solute molecules could sustain different pressures. Both the solvent and solute are always under identical pressures in a region of solution, namely, the pressure of the solution in that region. Since nature does not know which component we call the solvent and which the solute, equations should be symmetric in the two (acknowledging that the nonvolatile component, if any, is commonly chosen to be solute). Simple molecular pictures illustrate what is happening to cause pressure (positive or negative) in liquids, vapor pressure of liquids, and the various colligative properties of solutions. The only effect of solute involved in these properties is that it dilutes the solvent, with the resulting increase in S and decrease in micro(1)(soln). Water can be driven passively up a tree to enormous heights by the difference between its chemical potential in the roots and the ambient air. There is nothing mysterious about the molecular bases for any of these phenomena. Biologists can use the well-understood pictures of these phenomena with confidence to study what is happening in the complicated living systems they consider.
Colligative properties of simple solutions.
Andrews, F C
1976-11-01
Vapor pressure lowering, osmotic pressure, boiling point elevation, and freezing point depression are all related quantitatively to the decrease in micro(1)(soln) upon the addition of solute in forming a solution. In any equilibrium system, regardless of whether it is in a gravitational field or whether it contains walls, semipermeable membranes, phase transitions, or solutes, all equilibria are maintained locally, in the small region of the equilibrium, by the equality of micro(1)(soln). If there are several subsystems in a gravitational field, at any fixed height, microi will have the same value in each subsystem into which substance i can get, and microi + M(i)gh is constant throughout the entire system. In a solution, there is no mechanism by which solvent and solute molecules could sustain different pressures. Both the solvent and solute are always under identical pressures in a region of solution, namely, the pressure of the solution in that region. Since nature does not know which component we call the solvent and which the solute, equations should be symmetric in the two (acknowledging that the nonvolatile component, if any, is commonly chosen to be solute). Simple molecular pictures illustrate what is happening to cause pressure (positive or negative) in liquids, vapor pressure of liquids, and the various colligative properties of solutions. The only effect of solute involved in these properties is that it dilutes the solvent, with the resulting increase in S and decrease in micro(1)(soln). Water can be driven passively up a tree to enormous heights by the difference between its chemical potential in the roots and the ambient air. There is nothing mysterious about the molecular bases for any of these phenomena. Biologists can use the well-understood pictures of these phenomena with confidence to study what is happening in the complicated living systems they consider. PMID:17818408
Linearization algorithms for line transfer
Scott, H.A.
1990-11-06
Complete linearization is a very powerful technique for solving multi-line transfer problems that can be used efficiently with a variety of transfer formalisms. The linearization algorithm we describe is computationally very similar to ETLA, but allows an effective treatment of strongly-interacting lines. This algorithm has been implemented (in several codes) with two different transfer formalisms in all three one-dimensional geometries. We also describe a variation of the algorithm that handles saturable laser transport. Finally, we present a combination of linearization with a local approximate operator formalism, which has been implemented in two dimensions and is being developed in three dimensions. 11 refs.
Precision magnetic suspension linear bearing
NASA Technical Reports Server (NTRS)
Trumper, David L.; Queen, Michael A.
1992-01-01
We have shown the design and analyzed the electromechanics of a linear motor suitable for independently controlling two suspension degrees of freedom. This motor, at least on paper, meets the requirements for driving an X-Y stage of 10 Kg mass with about 4 m/sq sec acceleration, with travel of several hundred millimeters in X and Y, and with reasonable power dissipation. A conceptual design for such a stage is presented. The theoretical feasibility of linear and planar bearings using single or multiple magnetic suspension linear motors is demonstrated.
On Sub-linear Convergence for Linearly Degenerate Waves in Capturing Schemes
Banks, J W; Aslam, T; Rider, W J
2008-03-17
A common attribute of capturing schemes used to find approximate solutions to the Euler equations is a sub-linear rate of convergence with respect to mesh resolution. Purely nonlinear jumps, such as shock waves produce a first-order convergence rate, but linearly degenerate discontinuous waves, where present, produce sub-linear convergence rates which eventually dominate the global rate of convergence. The classical explanation for this phenomenon investigates the behavior of the exact solution to the numerical method in combination with the finite error terms, often referred to as the modified equation. For a first-order method, the modified equation produces the hyperbolic evolution equation with second-order diffusive terms. In the frame of reference of the traveling wave, the solution of a discontinuous wave consists of a diffusive layer that grows with a rate of t{sup 1/2}, yielding a convergence rate of 1/2. Self-similar heuristics for higher order discretizations produce a growth rate for the layer thickness of {Delta}t{sup 1/(p+1)} which yields an estimate for the convergence rate as p/(p+1) where p is the order of the discretization. In this paper we show that this estimated convergence rate can be derived with greater rigor for both dissipative and dispersive forms of the discrete error. In particular, the form of the analytical solution for linear modified equations can be solved exactly. These estimates and forms for the error are confirmed in a variety of demonstrations ranging from simple linear waves to multidimensional solutions of the Euler equations.
A free lunch in linearized experimental design?
NASA Astrophysics Data System (ADS)
Coles, Darrell; Curtis, Andrew
2011-08-01
The No Free Lunch (NFL) theorems state that no single optimization algorithm is ideally suited for all objective functions and, conversely, that no single objective function is ideally suited for all optimization algorithms. This paper examines the influence of the NFL theorems on linearized statistical experimental design (SED). We consider four design algorithms with three different design objective functions to examine their interdependency. As a foundation for the study, we consider experimental designs for fitting ellipses to data, a problem pertinent to the study of transverse isotropy in many disciplines. Surprisingly, we find that the quality of optimized experiments, and the computational efficiency of their optimization, is generally independent of the criterion-algorithm pairing. We discuss differences in the performance of each design algorithm, providing a guideline for selecting design algorithms for other problems. As a by-product we demonstrate and discuss the principle of diminishing returns in SED, namely, that the value of experimental design decreases with experiment size. Another outcome of this study is a simple rule-of-thumb for prescribing optimal experiments for ellipse fitting, which bypasses the computational expense of SED. This is used to define a template for optimizing survey designs, under simple assumptions, for Amplitude Variations with Azimuth and Offset (AVAZ) seismics in the specialized problem of fracture characterization, such as is of interest in the petroleum industry. Finally, we discuss the scope of our conclusions for the NFL theorems as they apply to nonlinear and Bayesian SED.
Terahertz-driven linear electron acceleration
Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.
2015-10-06
The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeVm^{-1 }gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. As a result, these ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.
Local linear viscoelasticity of confined fluids
NASA Astrophysics Data System (ADS)
Hansen, J. S.; Daivis, P. J.; Todd, B. D.
2007-04-01
In this paper the authors propose a novel method to study the local linear viscoelasticity of fluids confined between two walls. The method is based on the linear constitutive equation and provides details about the real and imaginary parts of the local complex viscosity. They apply the method to a simple atomic fluid undergoing zero mean oscillatory flow using nonequilibrium molecular dynamics simulations. The method shows that the viscoelastic properties of the fluid exhibit dramatic spatial changes near the wall-fluid boundary due to the high density in this region. It is also shown that the real part of the viscosity converges to the frequency dependent local shear viscosity sufficiently far away from the wall. This also provides valuable information about the transport properties in the fluid, in general. The viscosity is compared with predictions from the local average density model. The two methods disagree in that the local average density model predicts larger viscosity variations near the wall-fluid boundary than what is observed through the method presented here.
Reverberation mapping by regularized linear inversion
NASA Technical Reports Server (NTRS)
Krolik, Julian H.; Done, Christine
1995-01-01
Reverberation mapping of active galactic nucleus (AGN) emission-line regions requires the numerical deconvolution of two time series. We suggest the application of a new method, regularized linear inversion, to the solution of this problem. This method possesses many good features; it imposes no restrictions on the sign of the response function; it can provide clearly defined uncertainty estimates; it involves no guesswork about unmeasured data; it can give a clear indication of when the underlying convolution model is inadequate; and it is computationally very efficient. Using simulated data, we find the minimum S/N and length of the time series in order for this method to work satisfactorily. We also define guidelines for choosing the principal tunable parameter of the method and for interpreting the results. Finally, we reanalyze published data from the 1989 NGC 5548 campaign using this new method and compare the results to those previously obtained by maximum entropy analysis. For some lines we find good agreement, but for others, especially C III lambda(1909) and Si IV lambda(1400), we find significant differences. These can be attributed to the inability of the maximum entropy method to find negative values of the response function, but also illustrate the nonuniqueness of any deconvolution technique. We also find evidence that certain line light curves (e.g., C IV lambda(1549)) cannot be fully described by the simple linear convolution model.
Terahertz-driven linear electron acceleration
Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.
2015-01-01
The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeV m−1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. These ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams. PMID:26439410
Terahertz-driven linear electron acceleration
Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.
2015-10-06
The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeVm-1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton acceleratorsmore » with simple accelerating structures, high repetition rates and significant charge per bunch. As a result, these ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.« less
Estimating population trends with a linear model
Bart, J.; Collins, B.; Morrison, R.I.G.
2003-01-01
We describe a simple and robust method for estimating trends in population size. The method may be used with Breeding Bird Survey data, aerial surveys, point counts, or any other program of repeated surveys at permanent locations. Surveys need not be made at each location during each survey period. The method differs from most existing methods in being design based, rather than model based. The only assumptions are that the nominal sampling plan is followed and that sample size is large enough for use of the t-distribution. Simulations based on two bird data sets from natural populations showed that the point estimate produced by the linear model was essentially unbiased even when counts varied substantially and 25% of the complete data set was missing. The estimating-equation approach, often used to analyze Breeding Bird Survey data, performed similarly on one data set but had substantial bias on the second data set, in which counts were highly variable. The advantages of the linear model are its simplicity, flexibility, and that it is self-weighting. A user-friendly computer program to carry out the calculations is available from the senior author.
Linear summation of cat motor cortex outputs.
Ethier, Christian; Brizzi, Laurent; Darling, Warren G; Capaday, Charles
2006-05-17
Recruitment of movement-related muscle synergies involves the functional linking of motor cortical points. We asked how the outputs of two simultaneously stimulated motor cortical points would interact. To this end, experiments were done in ketamine-anesthetized cats. When prolonged (e.g., 500 ms) trains of intracortical microstimulation were applied in the primary motor cortex, stimulus currents as low as 10-20 microA evoked coordinated movements of the contralateral forelimb. Paw kinematics in three dimensions and the electromyographic (EMG) activity of eight muscles were simultaneously recorded. We show that the EMG outputs of two cortical points simultaneously stimulated are additive. The movements were represented as displacement vectors pointing from initial to final paw position. The displacement vectors resulting from simultaneous stimulation of two cortical points pointed in nearly the same direction as the algebraic resultant vector. Linear summation of outputs was also found when inhibition at one of the cortical points was reduced by GABAA receptor antagonists. A simple principle emerges from these results. Notwithstanding the underlying complex neuronal circuitry, motor cortex outputs combine nearly linearly in terms of movement direction and muscle activation patterns. Importantly, simultaneous activation does not change the nature of the output at each point. An additional implication is that not all possible movements need be explicitly represented in the motor cortex; a large number of different movements may be synthesized from a smaller repertoire.
Reduced Order ODE Model for Linear Contrails
NASA Astrophysics Data System (ADS)
Inamdar, A. R.; Lele, S. K.; Jacobson, M. Z.
2015-12-01
It is widely acknowledged that the large uncertainties in predictions of climate impact of linear contrails stem from inadequate parametrization of contrails in GCMs. But, the parameter space on which contrail dynamics and optical properties depend is very large and spanning it using high fidelity LES is prohibitively expensive. This study leverages the large dataset of LES done so far to understand the most important physical process that governs the evolution of contrails in different stages of its life and proposes a simple, low-cost and robust ODE model to capture the evolution of quantities of interest such as ice mass, vortex downwash and contrail cross-sectional dimensions. A direct consequence of modeling the contrail using parameters impacting the most important physical process is the reduction of the original parameter space to only those groupings of parameters that impact linear contrails independently. We are able to capture the most prominent features of the contrail at every stage of the life of the contrail - the induction of the jet exhaust by the trailing vortex pair, the vortex downwash and eventual destruction and the subsequent spreading of the contrail by ambient turbulence. A simplified version of GATOR-GCMOM - a GCM - is initialized using inputs from the new ODE model to test if the inclusion of the impact of the aforementioned parameter groups has significant persistent effects. Results from the GATOR-GCMOM box model calculations show which parameter groupings show persistent effects.
Overdetermined Systems of Linear Equations.
ERIC Educational Resources Information Center
Williams, Gareth
1990-01-01
Explored is an overdetermined system of linear equations to find an appropriate least squares solution. A geometrical interpretation of this solution is given. Included is a least squares point discussion. (KR)
Acoustic emission linear pulse holography
Collins, H.D.; Busse, L.J.; Lemon, D.K.
1983-10-25
This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.
NASA Technical Reports Server (NTRS)
Klumpp, A. R.; Lawson, C. L.
1988-01-01
Routines provided for common scalar, vector, matrix, and quaternion operations. Computer program extends Ada programming language to include linear-algebra capabilities similar to HAS/S programming language. Designed for such avionics applications as software for Space Station.
Optimal piecewise locally linear modeling
NASA Astrophysics Data System (ADS)
Harris, Chris J.; Hong, Xia; Feng, M.
1999-03-01
Associative memory networks such as Radial Basis Functions, Neurofuzzy and Fuzzy Logic used for modelling nonlinear processes suffer from the curse of dimensionality (COD), in that as the input dimension increases the parameterization, computation cost, training data requirements, etc. increase exponentially. Here a new algorithm is introduced for the construction of a Delaunay input space partitioned optimal piecewise locally linear models to overcome the COD as well as generate locally linear models directly amenable to linear control and estimation algorithms. The training of the model is configured as a new mixture of experts network with a new fast decision rule derived using convex set theory. A very fast simulated reannealing (VFSR) algorithm is utilized to search a global optimal solution of the Delaunay input space partition. A benchmark non-linear time series is used to demonstrate the new approach.
SLC: The first linear collider
NASA Astrophysics Data System (ADS)
Phinney, Nan
The Stanford Linear Collider (SLC) was built in the 1980s at the Stanford Linear Accelerator Center (SLAC) in California. Like LEP, it was designed to study the properties of the Z boson at a center-of-mass energy of about 91 GeV. The SLC was also a prototype for an entirely new approach to electron-positron colliders. The development of a new technology was motivated by the fact that in an electron storage ring, the electrons radiate synchrotron radiation as they are bent around the ring. To avoid excessive energy loss from this radiation, the circumference of the ring has to increase as the square of the desired energy, making very high energy rings prohibitively large and expensive. With a linear accelerator, the electrons do not need to bend and the tunnel length only grows linearly with energy...
Spacetime metric from linear electrodynamics
NASA Astrophysics Data System (ADS)
Obukhov, Yuri N.; Hehl, Friedrich W.
1999-07-01
The Maxwell equations are formulated on an arbitrary (1+3)-dimensional manifold. Then, imposing a (constrained) linear constitutive relation between electromagnetic field (E,B) and excitation (D,ℌ), we derive the metric of spacetime therefrom.
Linear Back-Drive Differentials
NASA Technical Reports Server (NTRS)
Waydo, Peter
2003-01-01
Linear back-drive differentials have been proposed as alternatives to conventional gear differentials for applications in which there is only limited rotational motion (e.g., oscillation). The finite nature of the rotation makes it possible to optimize a linear back-drive differential in ways that would not be possible for gear differentials or other differentials that are required to be capable of unlimited rotation. As a result, relative to gear differentials, linear back-drive differentials could be more compact and less massive, could contain fewer complex parts, and could be less sensitive to variations in the viscosities of lubricants. Linear back-drive differentials would operate according to established principles of power ball screws and linear-motion drives, but would utilize these principles in an innovative way. One major characteristic of such mechanisms that would be exploited in linear back-drive differentials is the possibility of designing them to drive or back-drive with similar efficiency and energy input: in other words, such a mechanism can be designed so that a rotating screw can drive a nut linearly or the linear motion of the nut can cause the screw to rotate. A linear back-drive differential (see figure) would include two collinear shafts connected to two parts that are intended to engage in limited opposing rotations. The linear back-drive differential would also include a nut that would be free to translate along its axis but not to rotate. The inner surface of the nut would be right-hand threaded at one end and left-hand threaded at the opposite end to engage corresponding right- and left-handed threads on the shafts. A rotation and torque introduced into the system via one shaft would drive the nut in linear motion. The nut, in turn, would back-drive the other shaft, creating a reaction torque. Balls would reduce friction, making it possible for the shaft/nut coupling on each side to operate with 90 percent efficiency.
Polarized Electrons for Linear Colliders
NASA Astrophysics Data System (ADS)
Clendenin, J. E.; Brachmann, A.; Garwin, E. L.; Kirby, R. E.; Luh, D.-A.; Maruyama, T.; Prescott, C. Y.; Sheppard, J. C.; Turner, J.; Prepost, R.
2005-08-01
Future electron-positron linear colliders require a highly polarized electron beam with a pulse structure that depends primarily on whether the acceleration utilizes warm or superconducting RF structures. The International Linear Collider (ILC) will use cold structures for the main linac. It is shown that a DC-biased polarized photoelectron source such as successfully used for the SLC can meet the charge requirements for the ILC micropulse with a polarization approaching 90%.
Polarized Electrons for Linear Colliders
Clendenin, J.
2004-11-19
Future electron-positron linear colliders require a highly polarized electron beam with a pulse structure that depends primarily on whether the acceleration utilizes warm or superconducting rf structures. The International Linear Collider (ILC) will use cold structures for the main linac. It is shown that a dc-biased polarized photoelectron source such as successfully used for the SLC can meet the charge requirements for the ILC micropulse with a polarization approaching 90%.
Linear superposition in nonlinear equations.
Khare, Avinash; Sukhatme, Uday
2002-06-17
Several nonlinear systems such as the Korteweg-de Vries (KdV) and modified KdV equations and lambda phi(4) theory possess periodic traveling wave solutions involving Jacobi elliptic functions. We show that suitable linear combinations of these known periodic solutions yield many additional solutions with different periods and velocities. This linear superposition procedure works by virtue of some remarkable new identities involving elliptic functions. PMID:12059300
Inverse modelling problems in linear algebra undergraduate courses
NASA Astrophysics Data System (ADS)
Martinez-Luaces, Victor E.
2013-10-01
This paper will offer an analysis from a theoretical point of view of mathematical modelling, applications and inverse problems of both causation and specification types. Inverse modelling problems give the opportunity to establish connections between theory and practice and to show this fact, a simple linear algebra example in two different presentations will be discussed. Finally, several results will be presented and some conclusions proposed.
Low-frequency turbulence in a linear magnetized plasma.
Rogers, B N; Ricci, Paolo
2010-06-01
Plasma turbulence in a linear device is explored for the first time with three-dimensional global two-fluid simulations, focusing on the plasma parameters of the Large Plasma Device. Three instabilities are present in the simulations: the Kelvin-Helmholtz instability, a sheath-driven instability, and a resistive drift wave instability. The Kelvin-Helmholtz mode is shown to dominate the transport of plasma across the magnetic field. Simple scaling laws are obtained for the plasma profiles. PMID:20867177
LINEAR SCANNING METHOD BASED ON THE SAFT COARRAY
Martin, C. J.; Martinez-Graullera, O.; Romero, D.; Ullate, L. G.; Higuti, R. T.
2010-02-22
This work presents a method to obtain B-scan images based on linear array scanning and 2R-SAFT. Using this technique some advantages are obtained: the ultrasonic system is very simple; it avoids the grating lobes formation, characteristic in conventional SAFT; and subaperture size and focussing lens (to compensate emission-reception) can be adapted dynamically to every image point. The proposed method has been experimentally tested in the inspection of CFRP samples.
Linear force-free fields in the lower corona
NASA Technical Reports Server (NTRS)
Barbosa, D. D.
1978-01-01
Boundary conditions are imposed on the normal component of B on two parallel planes which delineate the force-free volume of linear magnetic fields in low coronal levels of the solar atmosphere. Green's function is employed to ensure that equations for the magnetic field energy remain bounded and smooth. Field line tracings of a simple bipolar source distribution are developed and compared with empirical data obtained from visual observations in H(alpha), EUV, and X-rays.
Optimization of quasiperiodic structures in a linear resonance ion accelerator
NASA Astrophysics Data System (ADS)
Garashchenko, F. G.; Sokolov, L. S.; Tsulaya, A. V.
1980-06-01
A method is proposed for optimizing the parameters of a linear ion accelerator with rectangular or trapezoidal shape of the accelerating voltage between the tubes, systematic allowance being made for the quasiperiodicity of their arrangement. Numerical calculations have demonstrated the effectiveness of the method and also the fairly simple structure of its realization. A detailed algorithm is given. An estimate is made of the interval of entrance phases, the maximal value of which exceeds by several percent the limits previously predicted.
Comparison of Linear and Non-Linear Regression Models to Estimate Leaf Area Index of Dryland Shrubs.
NASA Astrophysics Data System (ADS)
Dashti, H.; Glenn, N. F.; Ilangakoon, N. T.; Mitchell, J.; Dhakal, S.; Spaete, L.
2015-12-01
Leaf area index (LAI) is a key parameter in global ecosystem studies. LAI is considered a forcing variable in land surface processing models since ecosystem dynamics are highly correlated to LAI. In response to environmental limitations, plants in semiarid ecosystems have smaller leaf area, making accurate estimation of LAI by remote sensing a challenging issue. Optical remote sensing (400-2500 nm) techniques to estimate LAI are based either on radiative transfer models (RTMs) or statistical approaches. Considering the complex radiation field of dry ecosystems, simple 1-D RTMs lead to poor results, and on the other hand, inversion of more complex 3-D RTMs is a demanding task which requires the specification of many variables. A good alternative to physical approaches is using methods based on statistics. Similar to many natural phenomena, there is a non-linear relationship between LAI and top of canopy electromagnetic waves reflected to optical sensors. Non-linear regression models can better capture this relationship. However, considering the problem of a few numbers of observations in comparison to the feature space (n
simple linear models. In this study linear versus non-linear regression techniques were investigated to estimate LAI. Our study area is located in southwestern Idaho, Great Basin. Sagebrush (Artemisia tridentata spp) serves a critical role in maintaining the structure of this ecosystem. Using a leaf area meter (Accupar LP-80), LAI values were measured in the field. Linear Partial Least Square regression and non-linear, tree based Random Forest regression have been implemented to estimate the LAI of sagebrush from hyperspectral data (AVIRIS-ng) collected in late summer 2014. Cross validation of results indicate that PLS can provide comparable results to Random Forest.
Non-linear stochastic growth rates and redshift space distortions
Jennings, Elise; Jennings, David
2015-04-09
The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ = ∇ ∙ v(x,t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean <θ|δ>, together with the fluctuations of θ around this mean. We also measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10 per cent at k < 0.2 h Mpc^{-1} to 25 per cent at k ~ 0.45 h Mpc^{-1} at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 10^{12} M_{⊙} h^{-1}, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean <θ|δ> away from the linear theory prediction -f_{LT}δ, where f_{LT }is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) fork < 0.1 h Mpc^{-1}. Furthermore, the stochasticity in the θ – δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of f_{LT} from two-point statistics in redshift space. Furthermore, given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of f_{LT} extracted using models which assume a linear, deterministic expression.
Non-linear stochastic growth rates and redshift space distortions
Jennings, Elise; Jennings, David
2015-04-09
The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ = ∇ ∙ v(x,t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean <θ|δ>, together with the fluctuations of θ around this mean. We also measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10 per cent at k < 0.2 h Mpc-1 to 25 per cent at kmore » ~ 0.45 h Mpc-1 at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 1012 M⊙ h-1, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean <θ|δ> away from the linear theory prediction -fLTδ, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) fork < 0.1 h Mpc-1. Furthermore, the stochasticity in the θ – δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of fLT from two-point statistics in redshift space. Furthermore, given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.« less
Transformation matrices between non-linear and linear differential equations
NASA Technical Reports Server (NTRS)
Sartain, R. L.
1983-01-01
In the linearization of systems of non-linear differential equations, those systems which can be exactly transformed into the second order linear differential equation Y"-AY'-BY=0 where Y, Y', and Y" are n x 1 vectors and A and B are constant n x n matrices of real numbers were considered. The 2n x 2n matrix was used to transform the above matrix equation into the first order matrix equation X' = MX. Specially the matrix M and the conditions which will diagonalize or triangularize M were studied. Transformation matrices P and P sub -1 were used to accomplish this diagonalization or triangularization to return to the solution of the second order matrix differential equation system from the first order system.
Suspension culture titration: A simple method for measuring baculovirus titers.
Matindoost, Leila; Chan, Leslie C L; Qi, Ying Mei; Nielsen, Lars K; Reid, Steven
2012-08-01
The baculovirus-insect cell expression system is an important technology for the production of recombinant proteins and baculovirus-based biopesticides. Budded virus titration is critical when scaling up baculovirus production processes in suspension cultures, to ensure reproducible infections, especially when a low multiplicity of infection (MOI) is applied. In this study, a simple suspension culture titration (SCT) assay was developed that involves accurate measurements of the initial cell densities (ICDs) and peak cell densities (PCDs) of an infected culture, from which the MOI and hence the virus inoculum infectious titer can be estimated, using the established Power-Nielsen baculovirus infection model. The SCT assay was assessed in parallel with two adherent culture-based assays (MTT and AlamarBlue) for the Heliothine baculovirus HaSNPV, and was shown to be more objective, time-efficient and reproducible. The model predicted a linear correlation between log(PCD/ICD) and log(MOI), hence an alternative model-independent SCT assay was also developed, which relies on a well-replicated standard curve relating suspension culture-derived PCD/ICD ratios with plaque or endpoint assay-derived MOIs. Standard curves with excellent linearity were generated for HaSNPV and the industrially significant rAcMNPV, demonstrating the feasibility of this simple titration approach, especially in terms of its applicability to a wide range of virus infection kinetics.
A simple formula for predicting claw volume of cattle.
Scott, T D; Naylor, J M; Greenough, P R
1999-11-01
The object of this study was to develop a simple method for accurately calculating the volume of bovine claws under field conditions. The digits of 30 slaughterhouse beef cattle were examined and the following four linear measurements taken from each pair of claws: (1) the length of the dorsal surface of the claw (Toe); (2) the length of the coronary band (CorBand); (3) the length of the bearing surface (Base); and (4) the height of the claw at the abaxial groove (AbaxGr). Measurements of claw volume using a simple hydrometer were highly repeatable (r(2)= 0.999) and could be calculated from linear measurements using the formula:Claw Volume (cm(3)) = (17.192 x Base) + (7.467 x AbaxGr) + 45.270 x (CorBand) - 798.5This formula was found to be accurate (r(2)= 0.88) when compared to volume data derived from a hydrometer displacement procedure. The front claws occupied 54% of the total volume compared to 46% for the hind claws.
A simple formula for predicting claw volume of cattle.
Scott, T D; Naylor, J M; Greenough, P R
1999-11-01
The object of this study was to develop a simple method for accurately calculating the volume of bovine claws under field conditions. The digits of 30 slaughterhouse beef cattle were examined and the following four linear measurements taken from each pair of claws: (1) the length of the dorsal surface of the claw (Toe); (2) the length of the coronary band (CorBand); (3) the length of the bearing surface (Base); and (4) the height of the claw at the abaxial groove (AbaxGr). Measurements of claw volume using a simple hydrometer were highly repeatable (r(2)= 0.999) and could be calculated from linear measurements using the formula:Claw Volume (cm(3)) = (17.192 x Base) + (7.467 x AbaxGr) + 45.270 x (CorBand) - 798.5This formula was found to be accurate (r(2)= 0.88) when compared to volume data derived from a hydrometer displacement procedure. The front claws occupied 54% of the total volume compared to 46% for the hind claws. PMID:10558838
Characterising dynamic non-linearity in floating wind turbines
NASA Astrophysics Data System (ADS)
Lupton, R. C.
2014-12-01
Fully coupled aero-hydro-control-elastic codes are being developed to cope with the new modelling challenges presented by floating wind turbines, but there is also a place for more efficient methods of analysis. One option is linearisation and analysis in the frequency domain. For this to be an effective method, the non-linearities in the system must be well understood. The present study focusses on understanding the dynamic response of the rotor to the overall platform motion, as would arise from wave loading, by using a simple model of a floating wind turbine with a rigid tower and flexible rotor (represented by hinged rigid blades). First, an equation of motion of the blade is derived and an approximate solution for the blade response is found using the perturbation method. Secondly, the full non-linear solution is found by time- domain simulation. The response is found to be linear at lower platform pitching frequencies, becoming non-linear at higher frequencies, with the approximate solution giving good results for weakly non-linear behaviour. Higher rotor speeds have a stabilising effect on the response. In the context of typical floating turbine parameters, it is concluded that the blade flapwise response is likely to be linear.
A nanoscale linear-to-linear motion converter of graphene.
Dai, Chunchun; Guo, Zhengrong; Zhang, Hongwei; Chang, Tienchong
2016-08-14
Motion conversion plays an irreplaceable role in a variety of machinery. Although many macroscopic motion converters have been widely used, it remains a challenge to convert motion at the nanoscale. Here we propose a nanoscale linear-to-linear motion converter, made of a flake-substrate system of graphene, which can convert the out-of-plane motion of the substrate into the in-plane motion of the flake. The curvature gradient induced van der Waals potential gradient between the flake and the substrate provides the driving force to achieve motion conversion. The proposed motion converter may have general implications for the design of nanomachinery and nanosensors.
Inhomogeneous electric field effects in a linear RF quadruple trap
NASA Technical Reports Server (NTRS)
Melborne, R. K.
1990-01-01
The exact potential corresponding to confining fields inside a linear rf quadrupole particle trap of finite length is presented. The analytic expressions for the trapping potential is derived by introducing a linear trap employing a relatively simple cylindrical geometry and solving Laplace's equation for the trap electrodes. The finite length of linear traps results in field distortion near the trap ends. An exact analytic determination of the fields is useful because the profile of the trapped ion cloud is highly dependent on the fields confining it. It is shown that near the ends of the trap, the effective potential arising from the rf fields acts to propel particles out of the trap, and further, that the addition of a dc bias generates an inhomogeneous in the trap that influences the particles both perpendicularly to and along the trap's long axis.
Linear minimum variance filters applied to carrier tracking
NASA Technical Reports Server (NTRS)
Gustafson, D. E.; Speyer, J. L.
1976-01-01
A new approach is taken to the problem of tracking a fixed amplitude signal with a Brownian-motion phase process. Classically, a first-order phase-lock loop (PLL) is used; here, the problem is treated via estimation of the quadrature signal components. In this space, the state dynamics are linear with white multiplicative noise. Therefore, linear minimum-variance filters, which have a particularly simple mechanization, are suggested. The resulting error dynamics are linear at any signal/noise ratio, unlike the classical PLL. During synchronization, and above threshold, this filter with constant gains degrades by 3 per cent in output rms phase error with respect to the classical loop. However, up to 80 per cent of the maximum possible noise improvement is obtained below threshold, where the classical loop is nonoptimum, as demonstrated by a Monte Carlo analysis. Filter mechanizations are presented for both carrier and baseband operation.
Non-linear Young's double-slit experiment.
San Roman, Julio; Ruiz, Camilo; Perez, Jose Antonio; Delgado, Diego; Mendez, Cruz; Plaja, Luis; Roso, Luis
2006-04-01
The Young's double slit experiment is recreated using intense and short laser pulses. Our experiment evidences the role of the non-linear Kerr effect in the formation of interference patterns. In particular, our results evidence a mixed mechanism in which the zeroth diffraction order of each slit are mainly affected by self-focusing and self-phase modulation, while the higher orders propagate linearly. Despite of the complexity of the general problem of non-linear propagation, we demonstrate that this experiment retains its simplicity and allows for a geometrical interpretation in terms of simple optical paths. In consequence, our results may provide key ideas on experiments on the formation of interference patterns with intense laser fields in Kerr media.
Simple scale interpolator facilitates reading of graphs
NASA Technical Reports Server (NTRS)
Fetterman, D. E., Jr.
1965-01-01
Simple transparent overlay with interpolation scale facilitates accurate, rapid reading of graph coordinate points. This device can be used for enlarging drawings and locating points on perspective drawings.
ERIC Educational Resources Information Center
Schwarz, Cindy
1995-01-01
Describes learnings originating from a simple pendulum simulation using "interactive physics" simulations. Discusses tension in the rope, acceleration of the pendulum bob, and initial displacements. (JRH)
Henry, J.J.
1961-09-01
A linear count-rate meter is designed to provide a highly linear output while receiving counting rates from one cycle per second to 100,000 cycles per second. Input pulses enter a linear discriminator and then are fed to a trigger circuit which produces positive pulses of uniform width and amplitude. The trigger circuit is connected to a one-shot multivibrator. The multivibrator output pulses have a selected width. Feedback means are provided for preventing transistor saturation in the multivibrator which improves the rise and decay times of the output pulses. The multivibrator is connected to a diode-switched, constant current metering circuit. A selected constant current is switched to an averaging circuit for each pulse received, and for a time determined by the received pulse width. The average output meter current is proportional to the product of the counting rate, the constant current, and the multivibrator output pulse width.
Belos Block Linear Solvers Package
2004-03-01
Belos is an extensible and interoperable framework for large-scale, iterative methods for solving systems of linear equations with multiple right-hand sides. The motivation for this framework is to provide a generic interface to a collection of algorithms for solving large-scale linear systems. Belos is interoperable because both the matrix and vectors are considered to be opaque objects--only knowledge of the matrix and vectors via elementary operations is necessary. An implementation of Balos is accomplished viamore » the use of interfaces. One of the goals of Belos is to allow the user flexibility in specifying the data representation for the matrix and vectors and so leverage any existing software investment. The algorithms that will be included in package are Krylov-based linear solvers, like Block GMRES (Generalized Minimal RESidual) and Block CG (Conjugate-Gradient).« less
QUANTUM OPTICS. Universal linear optics.
Carolan, Jacques; Harrold, Christopher; Sparrow, Chris; Martín-López, Enrique; Russell, Nicholas J; Silverstone, Joshua W; Shadbolt, Peter J; Matsuda, Nobuyuki; Oguma, Manabu; Itoh, Mikitaka; Marshall, Graham D; Thompson, Mark G; Matthews, Jonathan C F; Hashimoto, Toshikazu; O'Brien, Jeremy L; Laing, Anthony
2015-08-14
Linear optics underpins fundamental tests of quantum mechanics and quantum technologies. We demonstrate a single reprogrammable optical circuit that is sufficient to implement all possible linear optical protocols up to the size of that circuit. Our six-mode universal system consists of a cascade of 15 Mach-Zehnder interferometers with 30 thermo-optic phase shifters integrated into a single photonic chip that is electrically and optically interfaced for arbitrary setting of all phase shifters, input of up to six photons, and their measurement with a 12-single-photon detector system. We programmed this system to implement heralded quantum logic and entangling gates, boson sampling with verification tests, and six-dimensional complex Hadamards. We implemented 100 Haar random unitaries with an average fidelity of 0.999 ± 0.001. Our system can be rapidly reprogrammed to implement these and any other linear optical protocol, pointing the way to applications across fundamental science and quantum technologies. PMID:26160375
Interpretation of simulated global warming using a simple model
Watterson, I.G.
2000-01-01
A simple energy balance model with two parameters, an effective heat capacity and an effective climate sensitivity, is used to interpret six GCM simulations of greenhouse gas-induced global warming. By allowing the parameters to vary in time, the model can be accurately calibrated for each run. It is found that the sensitivity can be approximated as a constant in each case. However, the effective heat capacity clearly varies, and it is important that the energy equation is formulated appropriately, and thus unlike many such models. For simulations with linear forcing and from a cold start, the capacity is in each case close to that of a homogeneous ocean with depth initially 200 m, but increasing some 4.3 m each year, irrespective of the sensitivity and forcing growth rate. Analytic solutions for t his linear capacity function are derived, and these reproduce the GCM runs well, even for cases where the forcing is stabilized after a century or so. The formation of a subsurface maximum in the mean ocean temperature anomaly is a significant feature of such cases. A simple model for a GCM run with a realistic forcing scenario starting from 1,880 is constructed using component results for forcing segments. Given this, an estimate of the cold start error of a simulation of the warming due to forcing after the present would be given by the negative of the temperature drift of the anomaly due to the past forcing. The simple model can evidently be used to give an indication of likely warming curves, at lest for this range of scenarios and GCM sensitivities.
Permafrost Hazards and Linear Infrastructure
NASA Astrophysics Data System (ADS)
Stanilovskaya, Julia; Sergeev, Dmitry
2014-05-01
The international experience of linear infrastructure planning, construction and exploitation in permafrost zone is being directly tied to the permafrost hazard assessment. That procedure should also consider the factors of climate impact and infrastructure protection. The current global climate change hotspots are currently polar and mountain areas. Temperature rise, precipitation and land ice conditions change, early springs occur more often. The big linear infrastructure objects cross the territories with different permafrost conditions which are sensitive to the changes in air temperature, hydrology, and snow accumulation which are connected to climatic dynamics. One of the most extensive linear structures built on permafrost worldwide are Trans Alaskan Pipeline (USA), Alaska Highway (Canada), Qinghai-Xizang Railway (China) and Eastern Siberia - Pacific Ocean Oil Pipeline (Russia). Those are currently being influenced by the regional climate change and permafrost impact which may act differently from place to place. Thermokarst is deemed to be the most dangerous process for linear engineering structures. Its formation and development depend on the linear structure type: road or pipeline, elevated or buried one. Zonal climate and geocryological conditions are also of the determining importance here. All the projects are of the different age and some of them were implemented under different climatic conditions. The effects of permafrost thawing have been recorded every year since then. The exploration and transportation companies from different countries maintain the linear infrastructure from permafrost degradation in different ways. The highways in Alaska are in a good condition due to governmental expenses on annual reconstructions. The Chara-China Railroad in Russia is under non-standard condition due to intensive permafrost response. Standards for engineering and construction should be reviewed and updated to account for permafrost hazards caused by the
Simple Coupling of Reactor Physics Effects and Uncertain Nuances
2012-08-27
The "Simple Coupling of Reactor Physics Effects and Uncertain Nuances" (SCORPEUN) code is a simple r-z 1-group neutron diffusion code where each r-mesh is coupled to a single-flow-channel model that represents all flow-channels in that r-mesh. This 1-D model assesses q=m*Cp*deletaT for each z-mesh in that channel. This flow channel model is then coupled to a simple 1-D heat conduction model for ascertaining the peak center-line fuel temperature in a hypothetical pin assigned to thatmore » flow channel. The code has property lookup capability for water, Na, Zirc, HT9, metalic fuel, oxide fuel, etc. It has linear interpolation features for micro-scopic cross-sections with respect to coolant density and fuel temperature. ***This last feature has not been fully tested and may need development***. The interpolated microscopic cross-sections are then combined (using the water density from the T/H calculation) to generate macroscopic diffusion coefficient, removal cross-section and nu-sigmaF for each r-z mesh of the neutron diffusion code.« less
Vanilla technicolor at linear colliders
NASA Astrophysics Data System (ADS)
Frandsen, Mads T.; Järvinen, Matti; Sannino, Francesco
2011-08-01
We analyze the reach of linear colliders for models of dynamical electroweak symmetry breaking. We show that linear colliders can efficiently test the compositeness scale, identified with the mass of the new spin-one resonances, until the maximum energy in the center of mass of the colliding leptons. In particular we analyze the Drell-Yan processes involving spin-one intermediate heavy bosons decaying either leptonically or into two standard model gauge bosons. We also analyze the light Higgs production in association with a standard model gauge boson stemming also from an intermediate spin-one heavy vector.
Characterizations of linear sufficient statistics
NASA Technical Reports Server (NTRS)
Peters, B. C., Jr.; Reoner, R.; Decell, H. P., Jr.
1977-01-01
A surjective bounded linear operator T from a Banach space X to a Banach space Y must be a sufficient statistic for a dominated family of probability measures defined on the Borel sets of X. These results were applied, so that they characterize linear sufficient statistics for families of the exponential type, including as special cases the Wishart and multivariate normal distributions. The latter result was used to establish precisely which procedures for sampling from a normal population had the property that the sample mean was a sufficient statistic.
Linear Corrugating - Final Technical Report
Lloyd Chapman
2000-05-23
Linear Corrugating is a process for the manufacture of corrugated containers in which the flutes of the corrugated medium are oriented in the Machine Direction (MD) of the several layers of paper used. Conversely, in the conventional corrugating process the flutes are oriented at right angles to the MD in the Cross Machine Direction (CD). Paper is stronger in MD than in CD. Therefore, boxes made using the Linear Corrugating process are significantly stronger-in the prime strength criteria, Box Compression Test (BCT) than boxes made conventionally. This means that using Linear Corrugating boxes can be manufactured to BCT equaling conventional boxes but containing 30% less fiber. The corrugated container industry is a large part of the U.S. economy, producing over 40 million tons annually. For such a large industry, the potential savings of Linear Corrugating are enormous. The grant for this project covered three phases in the development of the Linear Corrugating process: (1) Production and evaluation of corrugated boxes on commercial equipment to verify that boxes so manufactured would have enhanced BCT as proposed in the application; (2) Production and evaluation of corrugated boxes made on laboratory equipment using combined board from (1) above but having dual manufactures joints (glue joints). This box manufacturing method (Dual Joint) is proposed to overcome box perimeter limitations of the Linear Corrugating process; (3) Design, Construction, Operation and Evaluation of an engineering prototype machine to form flutes in corrugating medium in the MD of the paper. This operation is the central requirement of the Linear Corrugating process. Items I and II were successfully completed, showing predicted BCT increases from the Linear Corrugated boxes and significant strength improvement in the Dual Joint boxes. The Former was constructed and operated successfully using kraft linerboard as the forming medium. It was found that tensile strength and stretch
A Simple Equation to Predict a Subscore's Value
ERIC Educational Resources Information Center
Feinberg, Richard A.; Wainer, Howard
2014-01-01
Subscores are often used to indicate test-takers' relative strengths and weaknesses and so help focus remediation. But a subscore is not worth reporting if it is too unreliable to believe or if it contains no information that is not already contained in the total score. It is possible, through the use of a simple linear equation provided in…
An Anharmonic Solution to the Equation of Motion for the Simple Pendulum
ERIC Educational Resources Information Center
Johannessen, Kim
2011-01-01
An anharmonic solution to the differential equation describing the oscillations of a simple pendulum at large angles is discussed. The solution is expressed in terms of functions not involving the Jacobi elliptic functions. In the derivation, a sinusoidal expression, including a linear and a Fourier sine series in the argument, has been applied.…
The Double-Well Potential in Quantum Mechanics: A Simple, Numerically Exact Formulation
ERIC Educational Resources Information Center
Jelic, V.; Marsiglio, F.
2012-01-01
The double-well potential is arguably one of the most important potentials in quantum mechanics, because the solution contains the notion of a state as a linear superposition of "classical" states, a concept which has become very important in quantum information theory. It is therefore desirable to have solutions to simple double-well potentials…
A Simple and Effective Protein Folding Activity Suitable for Large Lectures
ERIC Educational Resources Information Center
White, Brian
2006-01-01
This article describes a simple and inexpensive hands-on simulation of protein folding suitable for use in large lecture classes. This activity uses a minimum of parts, tools, and skill to simulate some of the fundamental principles of protein folding. The major concepts targeted are that proteins begin as linear polypeptides and fold to…
Fujibuchi, Toshioh; Yonai, Shunsuke; Yoshida, Masahiro; Sakae, Takeji; Watanabe, Hiroshi; Abe, Yoshihisa; Itami, Jun
2014-08-01
Photonuclear reactions generate neutrons in the head of the linear accelerator. Therefore, some parts of the linear accelerator can become activated. Such activated materials must be handled as radioactive waste. The authors attempted to investigate the distribution of induced radioactivity using photostimulable phosphor imaging plates. Autoradiographs were produced from some parts of the linear accelerator (the target, upper jaw, multileaf collimator and shielding). The levels of induced radioactivity were confirmed to be non-uniform within each part from the autoradiographs. The method was a simple and highly sensitive approach to evaluating the relative degree of activation of the linear accelerators, so that appropriate materials management procedures can be carried out.
Free unitary groups are (almost) simple
Chirvasitu, Alexandru
2012-12-15
We show that the quotients of Wang and Van Daele's universal quantum groups by their centers are simple in the sense that they have no normal quantum subgroups, thus providing the first examples of simple compact quantum groups with non-commutative fusion rings.
Sunspots and Their Simple Harmonic Motion
ERIC Educational Resources Information Center
Ribeiro, C. I.
2013-01-01
In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.
A simple approach to nonlinear oscillators
NASA Astrophysics Data System (ADS)
Ren, Zhong-Fu; He, Ji-Huan
2009-10-01
A very simple and effective approach to nonlinear oscillators is suggested. Anyone with basic knowledge of advanced calculus can apply the method to finding approximately the amplitude-frequency relationship of a nonlinear oscillator. Some examples are given to illustrate its extremely simple solution procedure and an acceptable accuracy of the obtained solutions.
Restoration Monitoring - A Simple Photo Monitoring Method
Nelson, J.K.
2000-02-14
Through the use of a simple photo monitoring design, it is possible to visually document, with both landscape and ground views, the progression of a restoration/revegetation project in a repeatable, cost-effective manner. The use of web browser technology can display the results in a simple, informative, professional manner, suitable for presentations and displays.
Simple Numerical Analysis of Longboard Speedometer Data
ERIC Educational Resources Information Center
Hare, Jonathan
2013-01-01
Simple numerical data analysis is described, using a standard spreadsheet program, to determine distance, velocity (speed) and acceleration from voltage data generated by a skateboard/longboard speedometer (Hare 2012 "Phys. Educ." 47 409-17). This simple analysis is an introduction to data processing including scaling data as well as…
The Fluid Foil: The Seventh Simple Machine
ERIC Educational Resources Information Center
Mitts, Charles R.
2012-01-01
A simple machine does one of two things: create a mechanical advantage (lever) or change the direction of an applied force (pulley). Fluid foils are unique among simple machines because they not only change the direction of an applied force (wheel and axle); they convert fluid energy into mechanical energy (wind and Kaplan turbines) or vice versa,…
Simple Experiments for Teaching Air Pressure
ERIC Educational Resources Information Center
Shamsipour, Gholamreza
2006-01-01
Everyone who teaches physics knows very well that sometimes a simple device or experiment can help to make a concept clear. In this paper, inspired by "The Jumping Pencil" by Martin Gardner, I will discuss a simple demonstration device that can be used to start the study of air pressure.
MHD simple waves and the divergence wave
Webb, G. M.; Pogorelov, N. V.; Zank, G. P.
2010-03-25
In this paper we investigate magnetohydrodynamic (MHD) simple divergence waves in MHD, for models in which nablacentre dotBnot =0. These models are related to the eight wave Riemann solvers in numerical MHD, in which the eighth wave is the divergence wave associated with nablacentre dotBnot =0. For simple wave solutions, all physical variables (the gas density, pressure, fluid velocity, entropy, and magnetic field induction in the MHD case) depend on a single phase function phi. We consider the form of the MHD equations used by both Powell et al. and Janhunen. It is shown that the Janhunen version of the equations possesses fully nonlinear, exact simple wave solutions for the divergence wave, but no physically meaningful simple divergence wave solution exists for the Powell et al. system. We suggest that the 1D simple, divergence wave solution for the Janhunen system, may be useful for the testing and validation of numerical MHD codes.
New directions in linear accelerators
Jameson, R.A.
1984-01-01
Current work on linear particle accelerators is placed in historical and physics contexts, and applications driving the state of the art are discussed. Future needs and the ways they may force development are outlined in terms of exciting R and D challenges presented to today's accelerator designers. 23 references, 7 figures.
Linear electric field mass spectrometry
McComas, D.J.; Nordholt, J.E.
1991-03-29
A mass spectrometer is described having a low weight and low power requirement, for use in space. It can be used to analyze the ionized particles in the region of the spacecraft on which it is mounted. High mass resolution measurements are made by timing ions moving through a gridless cylindrically sysmetric linear electric field.
Linear electric field mass spectrometry
McComas, D.J.; Nordholt, J.E.
1992-12-01
A mass spectrometer and methods for mass spectrometry are described. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field. 8 figs.
Linear electric field mass spectrometry
McComas, David J.; Nordholt, Jane E.
1992-01-01
A mass spectrometer and methods for mass spectrometry. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field.
Linearization of Conservative Nonlinear Oscillators
ERIC Educational Resources Information Center
Belendez, A.; Alvarez, M. L.; Fernandez, E.; Pascual, I.
2009-01-01
A linearization method of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force which allows us to obtain a frequency-amplitude relation which is valid not only for small but also for large amplitudes and, sometimes, for…
Feedback Systems for Linear Colliders
1999-04-12
Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an integral part of the design. Feedback requirements for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at high bandwidth and fast response. To correct for the motion of individual bunches within a train, both feedforward and feedback systems are planned. SLC experience has shown that feedback systems are an invaluable operational tool for decoupling systems, allowing precision tuning, and providing pulse-to-pulse diagnostics. Feedback systems for the NLC will incorporate the key SLC features and the benefits of advancing technologies.
Parameterized Linear Longitudinal Airship Model
NASA Technical Reports Server (NTRS)
Kulczycki, Eric; Elfes, Alberto; Bayard, David; Quadrelli, Marco; Johnson, Joseph
2010-01-01
A parameterized linear mathematical model of the longitudinal dynamics of an airship is undergoing development. This model is intended to be used in designing control systems for future airships that would operate in the atmospheres of Earth and remote planets. Heretofore, the development of linearized models of the longitudinal dynamics of airships has been costly in that it has been necessary to perform extensive flight testing and to use system-identification techniques to construct models that fit the flight-test data. The present model is a generic one that can be relatively easily specialized to approximate the dynamics of specific airships at specific operating points, without need for further system identification, and with significantly less flight testing. The approach taken in the present development is to merge the linearized dynamical equations of an airship with techniques for estimation of aircraft stability derivatives, and to thereby make it possible to construct a linearized dynamical model of the longitudinal dynamics of a specific airship from geometric and aerodynamic data pertaining to that airship. (It is also planned to develop a model of the lateral dynamics by use of the same methods.) All of the aerodynamic data needed to construct the model of a specific airship can be obtained from wind-tunnel testing and computational fluid dynamics
Linear or Exponential Number Lines
ERIC Educational Resources Information Center
Stafford, Pat
2011-01-01
Having decided to spend some time looking at one's understanding of numbers, the author was inspired by "Alex's Adventures in Numberland," by Alex Bellos to look at one's innate appreciation of number. Bellos quotes research studies suggesting that an individual's natural appreciation of numbers is more likely to be exponential rather than linear,…
NASA Astrophysics Data System (ADS)
Rincon, F.; Schekochihin, A. A.; Cowley, S. C.
2015-02-01
Slow dynamical changes in magnetic-field strength and invariance of the particles' magnetic moments generate ubiquitous pressure anisotropies in weakly collisional, magnetized astrophysical plasmas. This renders them unstable to fast, small-scale mirror and firehose instabilities, which are capable of exerting feedback on the macroscale dynamics of the system. By way of a new asymptotic theory of the early non-linear evolution of the mirror instability in a plasma subject to slow shearing or compression, we show that the instability does not saturate quasi-linearly at a steady, low-amplitude level. Instead, the trapping of particles in small-scale mirrors leads to non-linear secular growth of magnetic perturbations, δB/B ∝ t2/3. Our theory explains recent collisionless simulation results, provides a prediction of the mirror evolution in weakly collisional plasmas and establishes a foundation for a theory of non-linear mirror dynamics with trapping, valid up to δB/B = O(1).
Phycotoxicity of linear alkylbenzene sulfonate
Chawla, G.; Viswanathan, P.N.; Devi, S.
1988-04-01
Dose- and time-dependent effects of linear alkylbenzene sulfonate, a major component of synthetic detergent, to the blue-green alga Nostoc muscorum, were studied under laboratory conditions. Toxicity was evident, at doses above 0.001%, from the decrease in biomass, heterocyst number, and protein content and pathomorphological alterations.
A simple and direct method for generating travelling wave solutions for nonlinear equations
Bazeia, D. Das, Ashok; Silva, A.
2008-05-15
We propose a simple and direct method for generating travelling wave solutions for nonlinear integrable equations. We illustrate how nontrivial solutions for the KdV, the mKdV and the Boussinesq equations can be obtained from simple solutions of linear equations. We describe how using this method, a soliton solution of the KdV equation can yield soliton solutions for the mKdV as well as the Boussinesq equations. Similarly, starting with cnoidal solutions of the KdV equation, we can obtain the corresponding solutions for the mKdV as well as the Boussinesq equations. Simple solutions of linear equations can also lead to cnoidal solutions of nonlinear systems. Finally, we propose and solve some new families of KdV equations and show how soliton solutions are also obtained for the higher order equations of the KdV hierarchy using this method.
Simple scale interpolator facilitates reading of graphs
NASA Technical Reports Server (NTRS)
Fazio, A.; Henry, B.; Hood, D.
1966-01-01
Set of cards with scale divisions and a scale finder permits accurate reading of the coordinates of points on linear or logarithmic graphs plotted on rectangular grids. The set contains 34 different scales for linear plotting and 28 single cycle scales for log plots.
A tutorial on Bayesian Normal linear regression
NASA Astrophysics Data System (ADS)
Klauenberg, Katy; Wübbeler, Gerd; Mickan, Bodo; Harris, Peter; Elster, Clemens
2015-12-01
Regression is a common task in metrology and often applied to calibrate instruments, evaluate inter-laboratory comparisons or determine fundamental constants, for example. Yet, a regression model cannot be uniquely formulated as a measurement function, and consequently the Guide to the Expression of Uncertainty in Measurement (GUM) and its supplements are not applicable directly. Bayesian inference, however, is well suited to regression tasks, and has the advantage of accounting for additional a priori information, which typically robustifies analyses. Furthermore, it is anticipated that future revisions of the GUM shall also embrace the Bayesian view. Guidance on Bayesian inference for regression tasks is largely lacking in metrology. For linear regression models with Gaussian measurement errors this tutorial gives explicit guidance. Divided into three steps, the tutorial first illustrates how a priori knowledge, which is available from previous experiments, can be translated into prior distributions from a specific class. These prior distributions have the advantage of yielding analytical, closed form results, thus avoiding the need to apply numerical methods such as Markov Chain Monte Carlo. Secondly, formulas for the posterior results are given, explained and illustrated, and software implementations are provided. In the third step, Bayesian tools are used to assess the assumptions behind the suggested approach. These three steps (prior elicitation, posterior calculation, and robustness to prior uncertainty and model adequacy) are critical to Bayesian inference. The general guidance given here for Normal linear regression tasks is accompanied by a simple, but real-world, metrological example. The calibration of a flow device serves as a running example and illustrates the three steps. It is shown that prior knowledge from previous calibrations of the same sonic nozzle enables robust predictions even for extrapolations.
PCANet: A Simple Deep Learning Baseline for Image Classification?
Chan, Tsung-Han; Jia, Kui; Gao, Shenghua; Lu, Jiwen; Zeng, Zinan; Ma, Yi
2015-12-01
In this paper, we propose a very simple deep learning network for image classification that is based on very basic data processing components: 1) cascaded principal component analysis (PCA); 2) binary hashing; and 3) blockwise histograms. In the proposed architecture, the PCA is employed to learn multistage filter banks. This is followed by simple binary hashing and block histograms for indexing and pooling. This architecture is thus called the PCA network (PCANet) and can be extremely easily and efficiently designed and learned. For comparison and to provide a better understanding, we also introduce and study two simple variations of PCANet: 1) RandNet and 2) LDANet. They share the same topology as PCANet, but their cascaded filters are either randomly selected or learned from linear discriminant analysis. We have extensively tested these basic networks on many benchmark visual data sets for different tasks, including Labeled Faces in the Wild (LFW) for face verification; the MultiPIE, Extended Yale B, AR, Facial Recognition Technology (FERET) data sets for face recognition; and MNIST for hand-written digit recognition. Surprisingly, for all tasks, such a seemingly naive PCANet model is on par with the state-of-the-art features either prefixed, highly hand-crafted, or carefully learned [by deep neural networks (DNNs)]. Even more surprisingly, the model sets new records for many classification tasks on the Extended Yale B, AR, and FERET data sets and on MNIST variations. Additional experiments on other public data sets also demonstrate the potential of PCANet to serve as a simple but highly competitive baseline for texture classification and object recognition.
Kinetics of DSB rejoining and formation of simple chromosome exchange aberrations
NASA Technical Reports Server (NTRS)
Cucinotta, F. A.; Nikjoo, H.; O'Neill, P.; Goodhead, D. T.
2000-01-01
PURPOSE: To investigate the role of kinetics in the processing of DNA double strand breaks (DSB), and the formation of simple chromosome exchange aberrations following X-ray exposures to mammalian cells based on an enzymatic approach. METHODS: Using computer simulations based on a biochemical approach, rate-equations that describe the processing of DSB through the formation of a DNA-enzyme complex were formulated. A second model that allows for competition between two processing pathways was also formulated. The formation of simple exchange aberrations was modelled as misrepair during the recombination of single DSB with undamaged DNA. Non-linear coupled differential equations corresponding to biochemical pathways were solved numerically by fitting to experimental data. RESULTS: When mediated by a DSB repair enzyme complex, the processing of single DSB showed a complex behaviour that gives the appearance of fast and slow components of rejoining. This is due to the time-delay caused by the action time of enzymes in biomolecular reactions. It is shown that the kinetic- and dose-responses of simple chromosome exchange aberrations are well described by a recombination model of DSB interacting with undamaged DNA when aberration formation increases with linear dose-dependence. Competition between two or more recombination processes is shown to lead to the formation of simple exchange aberrations with a dose-dependence similar to that of a linear quadratic model. CONCLUSIONS: Using a minimal number of assumptions, the kinetics and dose response observed experimentally for DSB rejoining and the formation of simple chromosome exchange aberrations are shown to be consistent with kinetic models based on enzymatic reaction approaches. A non-linear dose response for simple exchange aberrations is possible in a model of recombination of DNA containing a DSB with undamaged DNA when two or more pathways compete for DSB repair.
Locally linear regression for pose-invariant face recognition.
Chai, Xiujuan; Shan, Shiguang; Chen, Xilin; Gao, Wen
2007-07-01
The variation of facial appearance due to the viewpoint (/pose) degrades face recognition systems considerably, which is one of the bottlenecks in face recognition. One of the possible solutions is generating virtual frontal view from any given nonfrontal view to obtain a virtual gallery/probe face. Following this idea, this paper proposes a simple, but efficient, novel locally linear regression (LLR) method, which generates the virtual frontal view from a given nonfrontal face image. We first justify the basic assumption of the paper that there exists an approximate linear mapping between a nonfrontal face image and its frontal counterpart. Then, by formulating the estimation of the linear mapping as a prediction problem, we present the regression-based solution, i.e., globally linear regression. To improve the prediction accuracy in the case of coarse alignment, LLR is further proposed. In LLR, we first perform dense sampling in the nonfrontal face image to obtain many overlapped local patches. Then, the linear regression technique is applied to each small patch for the prediction of its virtual frontal patch. Through the combination of all these patches, the virtual frontal view is generated. The experimental results on the CMU PIE database show distinct advantage of the proposed method over Eigen light-field method.
From Parity and Payoff Games to Linear Programming
NASA Astrophysics Data System (ADS)
Schewe, Sven
This paper establishes a surprising reduction from parity and mean payoff games to linear programming problems. While such a connection is trivial for solitary games, it is surprising for two player games, because the players have opposing objectives, whose natural translations into an optimisation problem are minimisation and maximisation, respectively. Our reduction to linear programming circumvents the need for concurrent minimisation and maximisation by replacing one of them, the maximisation, by approximation. The resulting optimisation problem can be translated to a linear programme by a simple space transformation, which is inexpensive in the unit cost model, but results in an exponential growth of the coefficients. The discovered connection opens up unexpected applications - like μ-calculus model checking - of linear programming in the unit cost model, and thus turns the intriguing academic problem of finding a polynomial time algorithm for linear programming in this model of computation (and subsequently a strongly polynomial algorithm) into a problem of paramount practical importance: All advancements in this area can immediately be applied to accelerate solving parity and payoff games, or to improve their complexity analysis.
NASA Technical Reports Server (NTRS)
Vranish, John
2009-01-01
T-slide linear actuators use gear bearing differential epicyclical transmissions (GBDETs) to directly drive a linear rack, which, in turn, performs the actuation. Conventional systems use a rotary power source in conjunction with a nut and screw to provide linear motion. Non-back-drive properties of GBDETs make the new actuator more direct and simpler. Versions of this approach will serve as a long-stroke, ultra-precision, position actuator for NASA science instruments, and as a rugged, linear actuator for NASA deployment duties. The T slide can operate effectively in the presence of side forces and torques. Versions of the actuator can perform ultra-precision positioning. A basic T-slide actuator is a long-stroke, rack-and-pinion linear actuator that, typically, consists of a T-slide, several idlers, a transmission to drive the slide (powered by an electric motor) and a housing that holds the entire assembly. The actuator is driven by gear action on its top surface, and is guided and constrained by gear-bearing idlers on its other two parallel surfaces. The geometry, implemented with gear-bearing technology, is particularly effective. An electronic motor operating through a GBDET can directly drive the T slide against large loads, as a rack and pinion linear actuator, with no break and no danger of back driving. The actuator drives the slide into position and stops. The slide holes position with power off and no brake, regardless of load. With the T slide configuration, this GBDET has an entire T-gear surface on which to operate. The GB idlers coupling the other two T slide parallel surfaces to their housing counterpart surfaces provide constraints in five degrees-of-freedom and rolling friction in the direction of actuation. Multiple GB idlers provide roller bearing strength sufficient to support efficient, rolling friction movement, even in the presence of large, resisting forces. T-slide actuators can be controlled using the combination of an off
Non-Linear Dynamics of Saturn's Rings
NASA Astrophysics Data System (ADS)
Esposito, L. W.
2015-12-01
Non-linear processes can explain why Saturn's rings are so active and dynamic. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw', as observed ny Cassini cameras. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn's rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. This confirms the triple architecture of ring particles: a broad size distribution of particles; these aggregate into temporary rubble piles; coated by a regolith of dust. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from
Topics in linear optical quantum computation
NASA Astrophysics Data System (ADS)
Glancy, Scott Charles
This thesis covers several topics in optical quantum computation. A quantum computer is a computational device which is able to manipulate information by performing unitary operations on some physical system whose state can be described as a vector (or mixture of vectors) in a Hilbert space. The basic unit of information, called the qubit, is considered to be a system with two orthogonal states, which are assigned logical values of 0 and 1. Photons make excellent candidates to serve as qubits. They have little interactions with the environment. Many operations can be performed using very simple linear optical devices such as beam splitters and phase shifters. Photons can easily be processed through circuit-like networks. Operations can be performed in very short times. Photons are ideally suited for the long-distance communication of quantum information. The great difficulty in constructing an optical quantum computer is that photons naturally interact weakly with one another. This thesis first gives a brief review of two early approaches to optical quantum computation. It will describe how any discrete unitary operation can be performed using a single photon and a network of beam splitters, and how the Kerr effect can be used to construct a two photon logic gate. Second, this work provides a thorough introduction to the linear optical quantum computer developed by Knill, Laflamme, and Milburn. It then presents this author's results on the reliability of this scheme when implemented using imperfect photon detectors. This author finds that quantum computers of this sort cannot be built using current technology. Third, this dissertation describes a method for constructing a linear optical quantum computer using nearly orthogonal coherent states of light as the qubits. It shows how a universal set of logic operations can be performed, including calculations of the fidelity with which these operations may be accomplished. It discusses methods for reducing and
Linear response and periodic points
NASA Astrophysics Data System (ADS)
Pollicott, M.; Vytnova, P.
2016-10-01
Given an expanding map of the interval we can associate an absolutely continuous measure. Given an Anosov transformation on a two torus we can associate a Sinai-Ruelle-Bowen measure. In this note we consider first and second derivatives of the change in the average of a reference function. We present an explicit convergent series for these derivatives. In particular, this gives a relatively simple method of computation.
Response properties of pigeon otolith afferents to linear acceleration
NASA Technical Reports Server (NTRS)
Si, X.; Angelaki, D. E.; Dickman, J. D.
1997-01-01
In the present study, the sensitivity to sinusoidal linear accelerations in the plane of the utricular macula was tested in afferents. The head orientation relative to the translation axis was varied in order to determine the head position that elicited the maximal and minimal responses for each afferent. The response gain and phase values obtained to 0.5-Hz and 2-Hz linear acceleration stimuli were then plotted as a function of head orientation and a modified cosine function was fit to the data. From the best-fit cosine function, the predicted head orientations that would produce the maximal and minimal response gains were estimated. The estimated maximum response gains to linear acceleration in the utricular plane for the afferents varied between 75 and 1420 spikes s-1 g-1. The mean maximal gains for all afferents to 0.5-Hz and 2-Hz sinusoidal linear acceleration stimuli were 282 and 367 spikes s-1 g-1, respectively. The minimal response gains were essentially zero for most units. The response phases always led linear acceleration and remained constant for each afferent, regardless of head orientation. These response characteristics indicate that otolith afferents are cosine tuned and behave as one-dimensional linear accelerometers. The directions of maximal sensitivity to linear acceleration for the afferents varied throughout the plane of the utricle; however, most vectors were directed out of the opposite ear near the interaural axis. The response dynamics of the afferents were tested using stimulus frequencies ranging between 0.25 Hz and 10 Hz (0.1 g peak acceleration). Across stimulus frequencies, most afferents had increasing gains and constant phase values. These dynamic properties for individual afferents were fit with a simple transfer function that included three parameters: a mechanical time constant, a gain constant, and a fractional order distributed adaptation operator.
Superstructure of linear duplex DNA.
Vollenweider, H J; Koller, T; Parello, J; Sogo, J M
1976-01-01
The superstructure of a covalently closed circular DNA (of bacteriophage PM 2) was compared by electron microscopy with that of a linear duplex DNA (of bacteriophage T7) when ionic strength and benzyldimethylalkylammonium chloride concentration were varied. In parallel studies the sedimentation behavior of these DNAs was studied by analytical ultracentrifugation, but for technical reasons these had to be without benzyldimethylalkylammonium chloride. By combining the information from the two methods one has to conclude that with increasing ionic strength the linear duplex T7 DNA spontaneously forms a structure similar to that of the superhelical structure of closed circular PM 2 DNA. The superstructure is destroyed under premelting conditions and in the presence of an excess of ethidium bromide. Images PMID:1069302
Linear regression in astronomy. II
NASA Technical Reports Server (NTRS)
Feigelson, Eric D.; Babu, Gutti J.
1992-01-01
A wide variety of least-squares linear regression procedures used in observational astronomy, particularly investigations of the cosmic distance scale, are presented and discussed. The classes of linear models considered are (1) unweighted regression lines, with bootstrap and jackknife resampling; (2) regression solutions when measurement error, in one or both variables, dominates the scatter; (3) methods to apply a calibration line to new data; (4) truncated regression models, which apply to flux-limited data sets; and (5) censored regression models, which apply when nondetections are present. For the calibration problem we develop two new procedures: a formula for the intercept offset between two parallel data sets, which propagates slope errors from one regression to the other; and a generalization of the Working-Hotelling confidence bands to nonstandard least-squares lines. They can provide improved error analysis for Faber-Jackson, Tully-Fisher, and similar cosmic distance scale relations.
Spatial processes in linear ordering.
von Hecker, Ulrich; Klauer, Karl Christoph; Wolf, Lukas; Fazilat-Pour, Masoud
2016-07-01
Memory performance in linear order reasoning tasks (A > B, B > C, C > D, etc.) shows quicker, and more accurate responses to queries on wider (AD) than narrower (AB) pairs on a hypothetical linear mental model (A - B - C - D). While indicative of an analogue representation, research so far did not provide positive evidence for spatial processes in the construction of such models. In a series of 7 experiments we report such evidence. Participants respond quicker when the dominant element in a pair is presented on the left (or top) rather than on the right (or bottom). The left-anchoring tendency reverses in a sample with Farsi background (reading/writing from right to left). Alternative explanations and confounds are tested. A theoretical model is proposed that integrates basic assumptions about acquired reading/writing habits as a scaffold for spatial simulation, and primacy/dominance representation within such spatial simulations. (PsycINFO Database Record PMID:26641448
Linear inflation from quartic potential
NASA Astrophysics Data System (ADS)
Kannike, Kristjan; Racioppi, Antonio; Raidal, Martti
2016-01-01
We show that if the inflaton has a non-minimal coupling to gravity and the Planck scale is dynamically generated, the results of Coleman-Weinberg inflation are confined in between two attractor solutions: quadratic inflation, which is ruled out by the recent measurements, and linear inflation which, instead, is in the experimental allowed region. The minimal scenario has only one free parameter — the inflaton's non-minimal coupling to gravity — that determines all physical parameters such as the tensor-to-scalar ratio and the reheating temperature of the Universe. Should the more precise future measurements of inflationary parameters point towards linear inflation, further interest in scale-invariant scenarios would be motivated.
Positive fractional linear electrical circuits
NASA Astrophysics Data System (ADS)
Kaczorek, Tadeusz
2013-10-01
The positive fractional linear systems and electrical circuits are addressed. New classes of fractional asymptotically stable and unstable electrical circuits are introduced. The Caputo and Riemann-Liouville definitions of fractional derivatives are used to analysis of the positive electrical circuits composed of resistors, capacitors, coils and voltage (current) sources. The positive fractional electrical and specially unstable different types electrical circuits are analyzed. Some open problems are formulated.
Segmented rail linear induction motor
Cowan, Jr., Maynard; Marder, Barry M.
1996-01-01
A segmented rail linear induction motor has a segmented rail consisting of a plurality of nonferrous electrically conductive segments aligned along a guideway. The motor further includes a carriage including at least one pair of opposed coils fastened to the carriage for moving the carriage. A power source applies an electric current to the coils to induce currents in the conductive surfaces to repel the coils from adjacent edges of the conductive surfaces.
Segmented rail linear induction motor
Cowan, M. Jr.; Marder, B.M.
1996-09-03
A segmented rail linear induction motor has a segmented rail consisting of a plurality of nonferrous electrically conductive segments aligned along a guideway. The motor further includes a carriage including at least one pair of opposed coils fastened to the carriage for moving the carriage. A power source applies an electric current to the coils to induce currents in the conductive surfaces to repel the coils from adjacent edges of the conductive surfaces. 6 figs.
Logistic systems with linear feedback
NASA Astrophysics Data System (ADS)
Son, Leonid; Shulgin, Dmitry; Ogluzdina, Olga
2016-08-01
A wide variety of systems may be described by specific dependence, which is known as logistic curve, or S-curve, between the internal characteristic and the external parameter. Linear feedback between these two values may be suggested for a wide set of systems also. In present paper, we suggest a bifurcation behavior for systems with both features, and discuss it for two cases, which are the Ising magnet in external field, and the development of manufacturing enterprise.
Precision linear ramp function generator
Jatko, W. Bruce; McNeilly, David R.; Thacker, Louis H.
1986-01-01
A ramp function generator is provided which produces a precise linear ramp unction which is repeatable and highly stable. A derivative feedback loop is used to stabilize the output of an integrator in the forward loop and control the ramp rate. The ramp may be started from a selected baseline voltage level and the desired ramp rate is selected by applying an appropriate constant voltage to the input of the integrator.
Precision linear ramp function generator
Jatko, W.B.; McNeilly, D.R.; Thacker, L.H.
1984-08-01
A ramp function generator is provided which produces a precise linear ramp function which is repeatable and highly stable. A derivative feedback loop is used to stabilize the output of an integrator in the forward loop and control the ramp rate. The ramp may be started from a selected baseline voltage level and the desired ramp rate is selected by applying an appropriate constant voltage to the input of the integrator.
Cast dielectric composite linear accelerator
Sanders, David M.; Sampayan, Stephen; Slenes, Kirk; Stoller, H. M.
2009-11-10
A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.
Wilson, P.B.
1987-05-01
The next generation of linear collider after the SLC (Stanford Linear Collider) will probably have an energy in the range 300 GeV-1 TeV per linac. A number of exotic accelerating schemes, such as laser and plasma acceleration, have been proposed for linear colliders of the far future. However, the technology which is most mature and which could lead to a collider in the above energy range in the relatively near future is the rf-driven linac, in which externally produced rf is fed into a more or less conventional metallic accelerating structure. Two basic technologies have been proposed for producing the required high peak rf power: discrete microwave power sources, and various two-beam acceleration schemes in which the rf is produced by a high current driving beam running parallel to the main accelerator. The current status of experimental and analytic work on both the discrete source and the two-beam methods for producing rf is discussed. The implications of beam-beam related effects (luminosity, disruption and beamstrahlung) for the design of rf-driven colliders are also considered.
BLAS- BASIC LINEAR ALGEBRA SUBPROGRAMS
NASA Technical Reports Server (NTRS)
Krogh, F. T.
1994-01-01
The Basic Linear Algebra Subprogram (BLAS) library is a collection of FORTRAN callable routines for employing standard techniques in performing the basic operations of numerical linear algebra. The BLAS library was developed to provide a portable and efficient source of basic operations for designers of programs involving linear algebraic computations. The subprograms available in the library cover the operations of dot product, multiplication of a scalar and a vector, vector plus a scalar times a vector, Givens transformation, modified Givens transformation, copy, swap, Euclidean norm, sum of magnitudes, and location of the largest magnitude element. Since these subprograms are to be used in an ANSI FORTRAN context, the cases of single precision, double precision, and complex data are provided for. All of the subprograms have been thoroughly tested and produce consistent results even when transported from machine to machine. BLAS contains Assembler versions and FORTRAN test code for any of the following compilers: Lahey F77L, Microsoft FORTRAN, or IBM Professional FORTRAN. It requires the Microsoft Macro Assembler and a math co-processor. The PC implementation allows individual arrays of over 64K. The BLAS library was developed in 1979. The PC version was made available in 1986 and updated in 1988.
Mass Distributions of Linear Chain Polymers.
Hubler, Shane L; Craciun, Gheorghe
2012-06-01
Biochemistry has many examples of linear chain polymers, i.e., molecules formed from a sequence of units from a finite set of possibilities; examples include proteins, RNA, single-stranded DNA, and paired DNA. In the field of mass spectrometry, it is useful to consider the idea of weighted alphabets, with a word inheriting weight from its letters. We describe the distribution of the mass of these words in terms of a simple recurrence relation, the general solution to that relation, and a canonical form that explicitly describes both the exponential form of this distribution and its periodic features, thus explaining a wave pattern that has been observed in protein mass databases. Further, we show that a pure exponential term dominates the distribution and that there is exactly one such purely exponential term. Finally, we illustrate the use of this theorem by describing a formula for the integer mass distribution of peptides and we compare our theoretical results with mass distributions of human and yeast peptides.
Mass Distributions of Linear Chain Polymers
Hubler, Shane L.; Craciun, Gheorghe
2012-01-01
Biochemistry has many examples of linear chain polymers, i.e., molecules formed from a sequence of units from a finite set of possibilities; examples include proteins, RNA, single-stranded DNA, and paired DNA. In the field of mass spectrometry, it is useful to consider the idea of weighted alphabets, with a word inheriting weight from its letters. We describe the distribution of the mass of these words in terms of a simple recurrence relation, the general solution to that relation, and a canonical form that explicitly describes both the exponential form of this distribution and its periodic features, thus explaining a wave pattern that has been observed in protein mass databases. Further, we show that a pure exponential term dominates the distribution and that there is exactly one such purely exponential term. Finally, we illustrate the use of this theorem by describing a formula for the integer mass distribution of peptides and we compare our theoretical results with mass distributions of human and yeast peptides. PMID:23024448
Linear diffusion into a Faraday cage.
Warne, Larry Kevin; Lin, Yau Tang; Merewether, Kimball O.; Chen, Kenneth C.
2011-11-01
Linear lightning diffusion into a Faraday cage is studied. An early-time integral valid for large ratios of enclosure size to enclosure thickness and small relative permeability ({mu}/{mu}{sub 0} {le} 10) is used for this study. Existing solutions for nearby lightning impulse responses of electrically thick-wall enclosures are refined and extended to calculate the nearby lightning magnetic field (H) and time-derivative magnetic field (HDOT) inside enclosures of varying thickness caused by a decaying exponential excitation. For a direct strike scenario, the early-time integral for a worst-case line source outside the enclosure caused by an impulse is simplified and numerically integrated to give the interior H and HDOT at the location closest to the source as well as a function of distance from the source. H and HDOT enclosure response functions for decaying exponentials are considered for an enclosure wall of any thickness. Simple formulas are derived to provide a description of enclosure interior H and HDOT as well. Direct strike voltage and current bounds for a single-turn optimally-coupled loop for all three waveforms are also given.
Thirty Simple Ideas for Interactive Whiteboards
ERIC Educational Resources Information Center
Adams, Caralee
2011-01-01
This article presents thirty simple ideas for interactive whiteboards and how IWB can make one's teaching life easier. These teaching ideas for the interactive whiteboard can be used by teachers every day. Tips for classroom management are also presented.
Simple shear of deformable square objects
NASA Astrophysics Data System (ADS)
Treagus, Susan H.; Lan, Labao
2003-12-01
Finite element models of square objects in a contrasting matrix in simple shear show that the objects deform to a variety of shapes. For a range of viscosity contrasts, we catalogue the changing shapes and orientations of objects in progressive simple shear. At moderate simple shear ( γ=1.5), the shapes are virtually indistinguishable from those in equivalent pure shear models with the same bulk strain ( RS=4), examined in a previous study. In theory, differences would be expected, especially for very stiff objects or at very large strain. In all our simple shear models, relatively competent square objects become asymmetric barrel shapes with concave shortened edges, similar to some types of boudin. Incompetent objects develop shapes surprisingly similar to mica fish described in mylonites.
Simple and Clear Proofs of Stirling's Formula
ERIC Educational Resources Information Center
Niizeki, Shozo; Araki, Makoto
2010-01-01
The purpose of our article is to show two simpler and clearer methods of proving Stirling's formula than the traditional and conventional ones. The distinction of our method is to use the simple trapezoidal formula.
The Invention Convention: Mind Meets Simple Machines.
ERIC Educational Resources Information Center
Hadi-Tabassum, Samina
1997-01-01
Describes an Earth Day celebration where students had to design an invention made of simple machines that could crush an empty aluminum can through 10 rapid mechanical movements using materials foraged from the students' homes. (JRH)
Thinking in Two Dimensions: Simple Multiplicative Relations
ERIC Educational Resources Information Center
Hutson, Barbara A.; Clark, Richard M.
1976-01-01
In order to study developmental and task-related factors in ability to coordinate two dimensions, a simple multiplicative relations matrix task was presented to 51 children in kindergarten and grades 1 and 2. (MS)
Pendulum: Rich physics from a simple system
Nelson, R.A.; Olsson, M.G.
1986-02-01
We provide a comprehensive discussion of the corrections needed to accurately measure the acceleration of gravity using a plane pendulum. A simple laboratory experiment is described in which g was determined to four significant figures of accuracy.
A simple device for embalming cadavers.
Janakiram, S; Balasubramanyam, V; Thomas, I M
1998-01-01
A simple design of a mobile embalming unit is presented that offers better quality embalming and is fairly economical. The technique is faster and consistently more reliable than the conventional gravity aided embalming.
Interstitialcy theory of simple condensed matter
NASA Astrophysics Data System (ADS)
Granato, Andrew V.
2014-01-01
A simple, more physical and compelling version of the Interstitialcy Theory of Simple Condensed Matter than that given previously is provided here. Also, computer simulation and direct and indirect experimental evidence is updated and reviewed. The theory is based on the properties of an interstitial in the interstitialcy, sometimes known as the dumbbell configuration. A free energy is derived, taking account of the unusually large shear susceptibility and vibrational entropy of the dumbbell to find the thermodynamic and kinetic properties of simple liquids and glasses. The connection between theory and experiment for some of the more notable properties of simple condensed matter found later is also discussed. The direct visual observation of interstitial diffusion to the surface in platinum near 20 K in irradiated thin films by Morgenstern et al. [M. Morgenstern, T. Michely, G. Comsa, Phys. Rev. Lett. 79, 1305 (1997)] is found to be sufficient compelling evidence for the interstitialcy theory.
Some Points about the Present Simple.
ERIC Educational Resources Information Center
Kaluza, Henryk
1981-01-01
Describes uses of English present simple tense as a definite, one point tense which can be expanded by context into segments of definite or indefinite present time, as well as into future and past references. (Author/BK)
Robotic-Assisted Simple Prostatectomy: An Overview.
Holden, Marc; Parsons, J Kellogg
2016-08-01
Despite widespread use of medical therapy for benign prostatic hyperplasia, a need remains for robust surgical therapy in select patients. Robotic-assisted simple prostatectomy (RASP) is an efficacious and safe therapy for patients with bladder outlet obstruction owing to large volume prostates. Data from 13 published cohorts suggest functional outcomes equivalent to open simple prostatectomy with substantially decreased length of hospital stay and risk of transfusion. However, there are few longer term data. PMID:27476131
Robotic-Assisted Simple Prostatectomy: An Overview.
Holden, Marc; Parsons, J Kellogg
2016-08-01
Despite widespread use of medical therapy for benign prostatic hyperplasia, a need remains for robust surgical therapy in select patients. Robotic-assisted simple prostatectomy (RASP) is an efficacious and safe therapy for patients with bladder outlet obstruction owing to large volume prostates. Data from 13 published cohorts suggest functional outcomes equivalent to open simple prostatectomy with substantially decreased length of hospital stay and risk of transfusion. However, there are few longer term data.
NASA Astrophysics Data System (ADS)
Santos, I. F.; Saracho, C. M.; Smith, J. T.; Eiland, J.
2004-04-01
This work makes a theoretical and experimental contribution to the problem of rotor-blades dynamic interaction. A validation procedure of mathematical models is carried out with the help of a simple test rig, built by a mass-spring system attached to four flexible rotating blades. With this test rig, it is possible to highlight some dynamic effects and experimentally simulate the structural behaviour of a windmill in two dimensions (2-D model). Only lateral displacement of the rotor in the horizontal direction is taken into account. Gyroscopic effect due to angular vibrations of the rotor is eliminated in the test rig by attaching the rigid rotor to a flexible foundation. The blades are modelled as Euler-Bernoulli beams. Using three different approaches to describe the beam deformation one achieves: (a) a linear model; (b) a linear beam model with second order terms; (c) a fully non-linear model. Tip masses at the end of the blades emphasize the coupling between the dynamic and elastic terms. The shape functions are chosen in order to reduce the mathematical model, so that only the first bending mode of the beam is taken into account. The resulting equations of motion have five degrees of freedom and illustrate linear, non-linear and time-dependent terms in a very transparent way. Although neither gyroscopic effect due to rotor angular vibrations nor higher blade mode shapes are considered in the analysis, the equations of motion of the rotor-blades system are still general enough for the purpose of the work: validation of different linear and non-linear models with time dependent (periodic) coefficients. Experiments are carried out in the time and frequency domains while the rotor operates with different constant angular velocities.
Transient shear banding in a simple yield stress fluid.
Divoux, Thibaut; Tamarii, David; Barentin, Catherine; Manneville, Sébastien
2010-05-21
We report a large set of experimental data which demonstrates that a simple yield stress fluid, i.e., which does not present aging or thixotropy, exhibits transient shear banding before reaching a steady state characterized by a homogeneous, linear velocity profile. The duration of the transient regime decreases as a power law with the applied shear rate γ. This power-law behavior, observed here in carbopol dispersions, does not depend on the gap width and on the boundary conditions for a given sample preparation. For γ≲0.1 s(-1), heterogeneous flows could be observed for as long as 10(5) s. These local dynamics account for the ultraslow stress relaxation observed at low shear rates. PMID:20867072
A simple perturbative tool to calculate plasmonic photonic bandstructures
NASA Astrophysics Data System (ADS)
Mohammed, Faris; Quandt, Alexander
2016-06-01
We use first order perturbation theory to study the effect of surface plasmon polaritons on the photonic band structure of plasmonic photonic crystals. Our results are based on a simple numerical tool that we have developed to extend the standard frequency domain methods to compute the photonic band structure of plasmonic photonic crystals. For a two-dimensional honeycomb photonic crystal with a lattice constant of 500 nm placed on an aluminium substrate, we show that the band gap for TM modes is enhanced by 13%. Thus a slight variation in the effective dielectric function results in a plasmonic band structure that is not scale-invariant, which is reminiscent of the inherent non-linear properties of the effective dielectric constant.
Simple implementation of a quantum search with trapped ions
NASA Astrophysics Data System (ADS)
Ivanov, Svetoslav S.; Ivanov, Peter A.; Vitanov, Nikolay V.
2008-09-01
We propose an ion-trap implementation of Grover’s quantum search algorithm for an unstructured database of arbitrary length N . The experimental implementation is appealingly simple because the linear ion trap allows for a straightforward construction, in a single interaction step and without a multitude of Hadamard transforms, of the reflection operator, which is the engine of the Grover algorithm. Consequently, a dramatic reduction in the number of the required physical steps takes place, to just O(N) , the same as the number of mathematical steps. The proposed setup allows for demonstration of both the original (probabilistic) Grover search and its deterministic variation, and is remarkably robust to imperfections in the register initialization.
Fractional non-linear modelling of ultracapacitors
NASA Astrophysics Data System (ADS)
Bertrand, Nicolas; Sabatier, Jocelyn; Briat, Olivier; Vinassa, Jean-Michel
2010-05-01
In this paper, it is demonstrated that an ultracapacitor exhibits a non-linear behaviour in relation to the operating voltage. A set of fractional order linear systems resulting from a frequency analysis of the ultracapacitor at various operating points is first obtained. Then, a non-linear model is deduced from the linear systems set, so that its Taylor linearization around the considered operating points (for the frequency analysis), produces the linear system set. The resulting non-linear model is validated on a Hybrid Electric Vehicle (HEV) application.
A simple FEM-DEM technique for fracture prediction in materials and structures
NASA Astrophysics Data System (ADS)
Zárate, Francisco; Oñate, Eugenio
2015-09-01
This paper presents a new computational technique for predicting the onset and evolution of fracture in a continuum in a simple manner combining the finite element method (FEM) and the discrete element method (DEM). Onset of cracking at a point is governed by a simple damage model. Once a crack is detected at an element side in the FE mesh, discrete elements are generated at the nodes sharing the side and a simple DEM mechanism is considered to follow the evolution of the crack. The combination of the DEM with simple 3-noded linear triangular elements correctly captures the onset of fracture and its evolution, as shown in several examples of application in two and three dimensions.
Development of a rapid, simple assay of plasma total carotenoids
2012-01-01
Background Plasma total carotenoids can be used as an indicator of risk of chronic disease. Laboratory analysis of individual carotenoids by high performance liquid chromatography (HPLC) is time consuming, expensive, and not amenable to use beyond a research laboratory. The aim of this research is to establish a rapid, simple, and inexpensive spectrophotometric assay of plasma total carotenoids that has a very strong correlation with HPLC carotenoid profile analysis. Results Plasma total carotenoids from 29 volunteers ranged in concentration from 1.2 to 7.4 μM, as analyzed by HPLC. A linear correlation was found between the absorbance at 448 nm of an alcohol / heptane extract of the plasma and plasma total carotenoids analyzed by HPLC, with a Pearson correlation coefficient of 0.989. The average coefficient of variation for the spectrophotometric assay was 6.5% for the plasma samples. The limit of detection was about 0.3 μM and was linear up to about 34 μM without dilution. Correlations between the integrals of the absorption spectra in the range of carotenoid absorption and total plasma carotenoid concentration gave similar results to the absorbance correlation. Spectrophotometric assay results also agreed with the calculated expected absorbance based on published extinction coefficients for the individual carotenoids, with a Pearson correlation coefficient of 0.988. Conclusion The spectrophotometric assay of total carotenoids strongly correlated with HPLC analysis of carotenoids of the same plasma samples and expected absorbance values based on extinction coefficients. This rapid, simple, inexpensive assay, when coupled with the carotenoid health index, may be useful for nutrition intervention studies, population cohort studies, and public health interventions. PMID:23006902
Effect of geometric parameters on deformation behavior of simple shear extrusion
NASA Astrophysics Data System (ADS)
Bagherpour, E.; Qods, F.; Ebrahimi, R.
2014-08-01
In the present study, the effect of geometric parameters on the simple shear extrusion (SSE) process as one of the most recent severe plastic deformation methods is investigated. Three deferent curvatures for deformation channel based on linear, quadratic and sine equations are introduced. Simulation of the process is carried out by means of the commercial finite element code ABAQUS/Explicit. Effect of die profile as well as backpressure on the strain, strain rate and load of deformation is studied. Results show that the shape of die profile does not have any significant effect on the required backpressure and the load of the process. The most homogeneous distribution of strain is obtained by linear die profile. Among all die profiles, only the linear profile can provide a constant strain rate. It is shown that linear profile is also the best candidate for deformation channel in SSE process due to its feasibility and homogeneity in the distribution of stain and constant strain rate.
Localization of the SFT inspired nonlocal linear models and exact solutions
NASA Astrophysics Data System (ADS)
Vernov, S. Yu.
2011-05-01
A general class of gravitational models driven by a nonlocal scalar field with a linear or quadratic potential is considered. We study the action with an arbitrary analytic function ℱ(□ g ), which has both simple and double roots. The way of localization of nonlocal Einstein equations is generalized on models with linear potentials. Exact solutions in the Friedmann-Robertson-Walker and Bianchi I metrics are presented.
Design of reduced-order state estimators for linear time-varying multivariable systems
NASA Technical Reports Server (NTRS)
Nguyen, Charles C.
1987-01-01
The design of reduced-order state estimators for linear time-varying multivariable systems is considered. Employing the concepts of matrix operators and the method of canonical transformations, this paper shows that there exists a reduced-order state estimator for linear time-varying systems that are 'lexicography-fixedly observable'. In addition, the eigenvalues of the estimator can be arbitrarily assigned. A simple algorithm is proposed for the design of the state estimator.
Are V1 Simple Cells Optimized for Visual Occlusions? A Comparative Study
Bornschein, Jörg; Henniges, Marc; Lücke, Jörg
2013-01-01
Simple cells in primary visual cortex were famously found to respond to low-level image components such as edges. Sparse coding and independent component analysis (ICA) emerged as the standard computational models for simple cell coding because they linked their receptive fields to the statistics of visual stimuli. However, a salient feature of image statistics, occlusions of image components, is not considered by these models. Here we ask if occlusions have an effect on the predicted shapes of simple cell receptive fields. We use a comparative approach to answer this question and investigate two models for simple cells: a standard linear model and an occlusive model. For both models we simultaneously estimate optimal receptive fields, sparsity and stimulus noise. The two models are identical except for their component superposition assumption. We find the image encoding and receptive fields predicted by the models to differ significantly. While both models predict many Gabor-like fields, the occlusive model predicts a much sparser encoding and high percentages of ‘globular’ receptive fields. This relatively new center-surround type of simple cell response is observed since reverse correlation is used in experimental studies. While high percentages of ‘globular’ fields can be obtained using specific choices of sparsity and overcompleteness in linear sparse coding, no or only low proportions are reported in the vast majority of studies on linear models (including all ICA models). Likewise, for the here investigated linear model and optimal sparsity, only low proportions of ‘globular’ fields are observed. In comparison, the occlusive model robustly infers high proportions and can match the experimentally observed high proportions of ‘globular’ fields well. Our computational study, therefore, suggests that ‘globular’ fields may be evidence for an optimal encoding of visual occlusions in primary visual cortex. PMID:23754938
Nonferromagnetic linear variable differential transformer
Ellis, James F.; Walstrom, Peter L.
1977-06-14
A nonferromagnetic linear variable differential transformer for accurately measuring mechanical displacements in the presence of high magnetic fields is provided. The device utilizes a movable primary coil inside a fixed secondary coil that consists of two series-opposed windings. Operation is such that the secondary output voltage is maintained in phase (depending on polarity) with the primary voltage. The transducer is well-suited to long cable runs and is useful for measuring small displacements in the presence of high or alternating magnetic fields.
Linear readout of object manifolds
NASA Astrophysics Data System (ADS)
Chung, SueYeon; Lee, Daniel D.; Sompolinsky, Haim
2016-06-01
Objects are represented in sensory systems by continuous manifolds due to sensitivity of neuronal responses to changes in physical features such as location, orientation, and intensity. What makes certain sensory representations better suited for invariant decoding of objects by downstream networks? We present a theory that characterizes the ability of a linear readout network, the perceptron, to classify objects from variable neural responses. We show how the readout perceptron capacity depends on the dimensionality, size, and shape of the object manifolds in its input neural representation.
A linear Fick's law calorimeter
NASA Astrophysics Data System (ADS)
Alpert, Seymour S.; Bryant, Pat D.; Woodside, William F.
1982-10-01
A small animal calorimeter is described that is based on the direct application of Fick's law. Heat flow is channeled through a circular disk of magnesium and the temperature difference between the inside and outside surface of the disk is detected by means of solid-state temperature transducers. The device is calibrated using a light-weight electrical resistive source and is shown to be linear in its response and to have an e-folding time of 4.8 min. A rat was introduced into the calorimeter and its heat energy expenditure rate was observed in both the sedated and unsedated states.
A terabyte linear tape recorder
NASA Technical Reports Server (NTRS)
Webber, John C.
1994-01-01
A plan has been formulated and selected for a NASA Phase 2 SBIR award for using the VLBA tape recorder for recording general data. The VLBA tape recorder is a high-speed, high-density linear tape recorder developed for Very Long Baseline Interferometry (VLBI) which is presently capable of recording at rates up to 2 Gbit/sec and holding up to 1 Terabyte of data on one tape, using a special interface and not employing error correction. A general-purpose interface and error correction will be added so that the recorder can be used in other high-speed, high-capacity applications.
ALPS - A LINEAR PROGRAM SOLVER
NASA Technical Reports Server (NTRS)
Viterna, L. A.
1994-01-01
Linear programming is a widely-used engineering and management tool. Scheduling, resource allocation, and production planning are all well-known applications of linear programs (LP's). Most LP's are too large to be solved by hand, so over the decades many computer codes for solving LP's have been developed. ALPS, A Linear Program Solver, is a full-featured LP analysis program. ALPS can solve plain linear programs as well as more complicated mixed integer and pure integer programs. ALPS also contains an efficient solution technique for pure binary (0-1 integer) programs. One of the many weaknesses of LP solvers is the lack of interaction with the user. ALPS is a menu-driven program with no special commands or keywords to learn. In addition, ALPS contains a full-screen editor to enter and maintain the LP formulation. These formulations can be written to and read from plain ASCII files for portability. For those less experienced in LP formulation, ALPS contains a problem "parser" which checks the formulation for errors. ALPS creates fully formatted, readable reports that can be sent to a printer or output file. ALPS is written entirely in IBM's APL2/PC product, Version 1.01. The APL2 workspace containing all the ALPS code can be run on any APL2/PC system (AT or 386). On a 32-bit system, this configuration can take advantage of all extended memory. The user can also examine and modify the ALPS code. The APL2 workspace has also been "packed" to be run on any DOS system (without APL2) as a stand-alone "EXE" file, but has limited memory capacity on a 640K system. A numeric coprocessor (80X87) is optional but recommended. The standard distribution medium for ALPS is a 5.25 inch 360K MS-DOS format diskette. IBM, IBM PC and IBM APL2 are registered trademarks of International Business Machines Corporation. MS-DOS is a registered trademark of Microsoft Corporation.
Fast feedback for linear colliders
Hendrickson, L.; Adolphsen, C.; Allison, S.; Gromme, T.; Grossberg, P.; Himel, T.; Krauter, K.; MacKenzie, R.; Minty, M.; Sass, R.
1995-05-01
A fast feedback system provides beam stabilization for the SLC. As the SLC is in some sense a prototype for future linear colliders, this system may be a prototype for future feedbacks. The SLC provides a good base of experience for feedback requirements and capabilities as well as a testing ground for performance characteristics. The feedback system controls a wide variety of machine parameters throughout the SLC and associated experiments, including regulation of beam position, angle, energy, intensity and timing parameters. The design and applications of the system are described, in addition to results of recent performance studies.
Acoustic emission linear pulse holography
Collins, H. D.; Busse, L. J.; Lemon, D. K.
1985-07-30
Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.
Acoustic emission linear pulse holography
Collins, H. Dale; Busse, Lawrence J.; Lemon, Douglas K.
1985-01-01
Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.
Linearized Bekenstein varying α models
NASA Astrophysics Data System (ADS)
Avelino, P. P.; Martins, C. J.; Oliveira, J. C.
2004-10-01
We study the simplest class of Bekenstein-type, varying α models, in which the two available free functions (potential and gauge kinetic function) are Taylor-expanded up to linear order. Any realistic model of this type reduces to a model in this class for a certain time interval around the present day. Nevertheless, we show that no such model is consistent with all existing observational results. We discuss possible implications of these findings, and, in particular, clarify the ambiguous statement (often found in the literature) that “the Webb results are inconsistent with Oklo.”
Elementary principles of linear accelerators
NASA Astrophysics Data System (ADS)
Loew, G. A.; Talman, R.
1983-09-01
A short chronology of important milestones in the field of linear accelerators is presented. Proton linacs are first discussed and elementary concepts such as transit time, shunt impedance, and Q are introduced. Critical issues such as phase stability and transverse forces are addressed. An elementary discussion of waveguide acclerating structures is also provided. Finally, electron accelerators addressed. Taking SLAC as an exmple, various topics are discussed such as structure design, choice of parameters, frequency optmization, beam current, emittance, bunch length and beam loading. Recent developments and future challenges are mentioned briefly.
Simple space-time symmetries: Generalizing conformal field theory
Mack, Gerhard; Riese, Mathias de
2007-05-15
We study simple space-time symmetry groups G which act on a space-time manifold M=G/H which admits a G-invariant global causal structure. We classify pairs (G,M) which share the following additional properties of conformal field theory. (1) The stability subgroup H of o set-membership sign M is the identity component of a parabolic subgroup of G, implying factorization H=MAN{sup -}, where M generalizes Lorentz transformations, A dilatations, and N{sup -} special conformal transformations. (2) Special conformal transformations {xi} set-membership sign N{sup -} act trivially on tangent vectors v set-membership sign T{sub o}M. The allowed simple Lie groups G are the universal coverings of SU(m,m),SO(2,D),Sp(l,R),SO*(4n), and E{sub 7(-25)} and H are particular maximal parabolic subgroups. They coincide with the groups of fractional linear transformations of Euclidean Jordan algebras whose use as generalizations of Minkowski space-time was advocated by Guenaydin [Mod. Phys. Lett. A 8, 1407 (1993)]. All these groups G admit positive energy representations. It will also be shown that the classical conformal groups SO(2,D) are the only allowed groups which possess an automorphism with properties appropriate for a time reflection.
Introducing CFD in the optical simulation of linear Fresnel collectors
NASA Astrophysics Data System (ADS)
Moghimi, M. A.; Rungasamy, A.; Craig, K. J.; Meyer, J. P.
2016-05-01
This paper seeks to determine whether the Finite Volume method within a commercially available Computational Fluid Dynamics (CFD) solver (ANSYS Fluent) can model radiation with comparable accuracy to a Monte Carlo ray-tracing software package (SolTrace). A detailed investigation was performed into modeling techniques that can be used to significantly reduce the optical errors traditionally associated with CFD modeling of radiation false scattering and ray effect using a simple optical test case. The strategies formulated in the first part of this paper were used to model a variety of Linear Fresnel Collector Concentrating Solar Power Plants. This paper shows that commercial CFD packages yield accurate results for line focusing concentrating solar applications and simple geometries, validating its use in an integrated environment where both optical and thermal performance of these plants can be simulated and optimized.
Linear optical coherence tomography system with extended measurement range.
Koch, Peter; Hellemanns, Volker; Hüttmann, Gereon
2006-10-01
Optical coherence tomography (OCT) sensors traditionally use scanning optical delay lines with moving parts and a single detector. OCT systems with a linear detector array (linear OCT or L-OCT) are simple and robust, but a detector with approximately 10,000 pixels is needed for an imaging depth of 2mm, which is necessary for most biomedical applications. We present a new optical setup for L-OCT with an increased measurement range. An additional grating performs a reduction of the spatial frequencies of the fringe pattern on the detector without loss in the signal-to-noise ratio, so the signal can be sampled with a minimal number of pixels. The theory for this approach is addressed and the first measurements are presented. PMID:16969410
Attitude control with realization of linear error dynamics
NASA Technical Reports Server (NTRS)
Paielli, Russell A.; Bach, Ralph E.
1993-01-01
An attitude control law is derived to realize linear unforced error dynamics with the attitude error defined in terms of rotation group algebra (rather than vector algebra). Euler parameters are used in the rotational dynamics model because they are globally nonsingular, but only the minimal three Euler parameters are used in the error dynamics model because they have no nonlinear mathematical constraints to prevent the realization of linear error dynamics. The control law is singular only when the attitude error angle is exactly pi rad about any eigenaxis, and a simple intuitive modification at the singularity allows the control law to be used globally. The forced error dynamics are nonlinear but stable. Numerical simulation tests show that the control law performs robustly for both initial attitude acquisition and attitude control.
Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA).
Leick, Michael T.; Moses, Ronald W.
2015-03-01
This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to charge the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.
A higher order panel method for linearized supersonic flow
NASA Technical Reports Server (NTRS)
Ehlers, F. E.; Epton, M. A.; Johnson, F. T.; Magnus, A. E.; Rubbert, P. E.
1979-01-01
The basic integral equations of linearized supersonic theory for an advanced supersonic panel method are derived. Methods using only linear varying source strength over each panel or only quadratic doublet strength over each panel gave good agreement with analytic solutions over cones and zero thickness cambered wings. For three dimensional bodies and wings of general shape, combined source and doublet panels with interior boundary conditions to eliminate the internal perturbations lead to a stable method providing good agreement experiment. A panel system with all edges contiguous resulted from dividing the basic four point non-planar panel into eight triangular subpanels, and the doublet strength was made continuous at all edges by a quadratic distribution over each subpanel. Superinclined panels were developed and tested on s simple nacelle and on an airplane model having engine inlets, with excellent results.
Linear and circular digital spectral analysis of serial data
NASA Technical Reports Server (NTRS)
Stothers, Richard B.
1991-01-01
Two methods of digital spectral analysis of unevenly sampled data are developed and illustrated here. One method uses a linear function of time (or space), the other uses circular functions. The circular method turns out to be essentially equivalent to a least-squares sine-wave analysis. The linear, anharmonic method uses only the field of real numbers and elementary algebraic operations, and hence it can be made computationally very fast and accurate. Both methods are very general, properly handling all kinds of time series ranging from simple series consisting only of the times of events to complicated series consisting of pulses with long duty cycles. The two methods are here applied to the analysis of annual mean relative sunspot numbers.
Lowekamp, Bradley C.; Chen, David T.; Ibáñez, Luis; Blezek, Daniel
2013-01-01
SimpleITK is a new interface to the Insight Segmentation and Registration Toolkit (ITK) designed to facilitate rapid prototyping, education and scientific activities via high level programming languages. ITK is a templated C++ library of image processing algorithms and frameworks for biomedical and other applications, and it was designed to be generic, flexible and extensible. Initially, ITK provided a direct wrapping interface to languages such as Python and Tcl through the WrapITK system. Unlike WrapITK, which exposed ITK's complex templated interface, SimpleITK was designed to provide an easy to use and simplified interface to ITK's algorithms. It includes procedural methods, hides ITK's demand driven pipeline, and provides a template-less layer. Also SimpleITK provides practical conveniences such as binary distribution packages and overloaded operators. Our user-friendly design goals dictated a departure from the direct interface wrapping approach of WrapITK, toward a new facade class structure that only exposes the required functionality, hiding ITK's extensive template use. Internally SimpleITK utilizes a manual description of each filter with code-generation and advanced C++ meta-programming to provide the higher-level interface, bringing the capabilities of ITK to a wider audience. SimpleITK is licensed as open source software library under the Apache License Version 2.0 and more information about downloading it can be found at http://www.simpleitk.org. PMID:24416015
Lowekamp, Bradley C; Chen, David T; Ibáñez, Luis; Blezek, Daniel
2013-01-01
SimpleITK is a new interface to the Insight Segmentation and Registration Toolkit (ITK) designed to facilitate rapid prototyping, education and scientific activities via high level programming languages. ITK is a templated C++ library of image processing algorithms and frameworks for biomedical and other applications, and it was designed to be generic, flexible and extensible. Initially, ITK provided a direct wrapping interface to languages such as Python and Tcl through the WrapITK system. Unlike WrapITK, which exposed ITK's complex templated interface, SimpleITK was designed to provide an easy to use and simplified interface to ITK's algorithms. It includes procedural methods, hides ITK's demand driven pipeline, and provides a template-less layer. Also SimpleITK provides practical conveniences such as binary distribution packages and overloaded operators. Our user-friendly design goals dictated a departure from the direct interface wrapping approach of WrapITK, toward a new facade class structure that only exposes the required functionality, hiding ITK's extensive template use. Internally SimpleITK utilizes a manual description of each filter with code-generation and advanced C++ meta-programming to provide the higher-level interface, bringing the capabilities of ITK to a wider audience. SimpleITK is licensed as open source software library under the Apache License Version 2.0 and more information about downloading it can be found at http://www.simpleitk.org. PMID:24416015
Lowekamp, Bradley C; Chen, David T; Ibáñez, Luis; Blezek, Daniel
2013-01-01
SimpleITK is a new interface to the Insight Segmentation and Registration Toolkit (ITK) designed to facilitate rapid prototyping, education and scientific activities via high level programming languages. ITK is a templated C++ library of image processing algorithms and frameworks for biomedical and other applications, and it was designed to be generic, flexible and extensible. Initially, ITK provided a direct wrapping interface to languages such as Python and Tcl through the WrapITK system. Unlike WrapITK, which exposed ITK's complex templated interface, SimpleITK was designed to provide an easy to use and simplified interface to ITK's algorithms. It includes procedural methods, hides ITK's demand driven pipeline, and provides a template-less layer. Also SimpleITK provides practical conveniences such as binary distribution packages and overloaded operators. Our user-friendly design goals dictated a departure from the direct interface wrapping approach of WrapITK, toward a new facade class structure that only exposes the required functionality, hiding ITK's extensive template use. Internally SimpleITK utilizes a manual description of each filter with code-generation and advanced C++ meta-programming to provide the higher-level interface, bringing the capabilities of ITK to a wider audience. SimpleITK is licensed as open source software library under the Apache License Version 2.0 and more information about downloading it can be found at http://www.simpleitk.org.
Are running speeds maximized with simple-spring stance mechanics?
Clark, Kenneth P; Weyand, Peter G
2014-09-15
Are the fastest running speeds achieved using the simple-spring stance mechanics predicted by the classic spring-mass model? We hypothesized that a passive, linear-spring model would not account for the running mechanics that maximize ground force application and speed. We tested this hypothesis by comparing patterns of ground force application across athletic specialization (competitive sprinters vs. athlete nonsprinters, n = 7 each) and running speed (top speeds vs. slower ones). Vertical ground reaction forces at 5.0 and 7.0 m/s, and individual top speeds (n = 797 total footfalls) were acquired while subjects ran on a custom, high-speed force treadmill. The goodness of fit between measured vertical force vs. time waveform patterns and the patterns predicted by the spring-mass model were assessed using the R(2) statistic (where an R(2) of 1.00 = perfect fit). As hypothesized, the force application patterns of the competitive sprinters deviated significantly more from the simple-spring pattern than those of the athlete, nonsprinters across the three test speeds (R(2) <0.85 vs. R(2) ≥ 0.91, respectively), and deviated most at top speed (R(2) = 0.78 ± 0.02). Sprinters attained faster top speeds than nonsprinters (10.4 ± 0.3 vs. 8.7 ± 0.3 m/s) by applying greater vertical forces during the first half (2.65 ± 0.05 vs. 2.21 ± 0.05 body wt), but not the second half (1.71 ± 0.04 vs. 1.73 ± 0.04 body wt) of the stance phase. We conclude that a passive, simple-spring model has limited application to sprint running performance because the swiftest runners use an asymmetrical pattern of force application to maximize ground reaction forces and attain faster speeds.
A Thermodynamic Theory Of Solid Viscoelasticity. Part 1: Linear Viscoelasticity.
NASA Technical Reports Server (NTRS)
Freed, Alan D.; Leonov, Arkady I.
2002-01-01
The present series of three consecutive papers develops a general theory for linear and finite solid viscoelasticity. Because the most important object for nonlinear studies are rubber-like materials, the general approach is specified in a form convenient for solving problems important for many industries that involve rubber-like materials. General linear and nonlinear theories for non-isothermal deformations of viscoelastic solids are developed based on the quasi-linear approach of non-equilibrium thermodynamics. In this, the first paper of the series, we analyze non-isothermal linear viscoelasticity, which is applicable in a range of small strains not only to all synthetic polymers and bio-polymers but also to some non-polymeric materials. Although the linear case seems to be well developed, there still are some reasons to implement a thermodynamic derivation of constitutive equations for solid-like, non-isothermal, linear viscoelasticity. The most important is the thermodynamic modeling of thermo-rheological complexity , i.e. different temperature dependences of relaxation parameters in various parts of relaxation spectrum. A special structure of interaction matrices is established for different physical mechanisms contributed to the normal relaxation modes. This structure seems to be in accord with observations, and creates a simple mathematical framework for both continuum and molecular theories of the thermo-rheological complex relaxation phenomena. Finally, a unified approach is briefly discussed that, in principle, allows combining both the long time (discrete) and short time (continuous) descriptions of relaxation behaviors for polymers in the rubbery and glassy regions.
Neighboring extremal guidance for systems with a piecewise linear control
NASA Technical Reports Server (NTRS)
Hull, David G.; Helfrich, Clifford E.
1991-01-01
The neighboring extremal feedback control law is developed for systems with a piecewise linear control for the case where the optimal control is obtained by nonlinear programming techniques. To develop the control perturbation for a given deviation from the nominal path, the second variation is minimized subject to the constraint that the final conditions be satisfied. This process leads to a feedback relationship between the control perturbation and the measured deviation from the nominal state. A simple example, the lunar launch problem, is used to demonstrate the validity of the guidance law. For model errors on the order of 5 percent, the results indicate that 5 percent errors occur in the final conditions.
Recognizing Human Activities Using Non-linear SVM Decision Tree
NASA Astrophysics Data System (ADS)
Zhao, Haiyong; Liu, Zhijing; Zhang, Hao
This paper presents a new method of human activity recognition, which is based on R transform and non-linear SVM Decision Tree (NSVMDT). For a key binary human silhouette, R transform is employed to represent low-level features. The advantage of the R transform lies in its low computational complexity and geometric invariance. We utilize NSVMDT to train and classify video sequences, and demonstrate the usability with many sequences. Compared with other methods, ours is superior because the descriptor is robust to frame loss in superior because the descriptor is robust to frame loss in activities recognition, simple representation, computational complexity and template generalization. Sufficient experiments have proved the efficiency.
Matrix preconditioning: a robust operation for optical linear algebra processors.
Ghosh, A; Paparao, P
1987-07-15
Analog electrooptical processors are best suited for applications demanding high computational throughput with tolerance for inaccuracies. Matrix preconditioning is one such application. Matrix preconditioning is a preprocessing step for reducing the condition number of a matrix and is used extensively with gradient algorithms for increasing the rate of convergence and improving the accuracy of the solution. In this paper, we describe a simple parallel algorithm for matrix preconditioning, which can be implemented efficiently on a pipelined optical linear algebra processor. From the results of our numerical experiments we show that the efficacy of the preconditioning algorithm is affected very little by the errors of the optical system.
Thermodynamic formalism and linear response theory for nonequilibrium steady states.
Speck, Thomas
2016-08-01
We study the linear response in systems driven away from thermal equilibrium into a nonequilibrium steady state with nonvanishing entropy production rate. A simple derivation of a general response formula is presented under the condition that the generating function describes a transformation that (to lowest order) preserves normalization and thus describes a physical stochastic process. For Markov processes we explicitly construct the conjugate quantities and discuss their relation with known response formulas. Emphasis is put on the formal analogy with thermodynamic potentials and some consequences are discussed. PMID:27627270
A RECIPE FOR LINEAR COLLIDER FINAL FOCUS SYSTEM DESIGN
Seryi, Andrei
2003-05-27
The design of Final Focus systems for linear colliders is challenging because of the large demagnifications needed to produce nanometer-sized beams at the interaction point. Simple first- and second-order matrix matching have proven insufficient for this task, and minimization of third- and higher-order aberrations is essential. An appropriate strategy is required for the latter to be successful. A recipe for Final Focus design, and a set of computational tools used to implement this approach, are described herein. An example of the use of this procedure is given.
Digitally gain controlled linear high voltage amplifier for laboratory applications.
Koçum, C
2011-08-01
The design of a digitally gain controlled high-voltage non-inverting bipolar linear amplifier is presented. This cost efficient and relatively simple circuit has stable operation range from dc to 90 kHz under the load of 10 kΩ and 39 pF. The amplifier can swing up to 360 V(pp) under these conditions and it has 2.5 μs rise time. The gain can be changed by the aid of JFETs. The amplifiers have been realized using a combination of operational amplifiers and high-voltage discrete bipolar junction transistors. The circuit details and performance characteristics are discussed.
A recurrent neural network for solving bilevel linear programming problem.
He, Xing; Li, Chuandong; Huang, Tingwen; Li, Chaojie; Huang, Junjian
2014-04-01
In this brief, based on the method of penalty functions, a recurrent neural network (NN) modeled by means of a differential inclusion is proposed for solving the bilevel linear programming problem (BLPP). Compared with the existing NNs for BLPP, the model has the least number of state variables and simple structure. Using nonsmooth analysis, the theory of differential inclusions, and Lyapunov-like method, the equilibrium point sequence of the proposed NNs can approximately converge to an optimal solution of BLPP under certain conditions. Finally, the numerical simulations of a supply chain distribution model have shown excellent performance of the proposed recurrent NNs.
A Solution to the Fundamental Linear Fractional Order Differential Equation
NASA Technical Reports Server (NTRS)
Hartley, Tom T.; Lorenzo, Carl F.
1998-01-01
This paper provides a solution to the fundamental linear fractional order differential equation, namely, (sub c)d(sup q, sub t) + ax(t) = bu(t). The impulse response solution is shown to be a series, named the F-function, which generalizes the normal exponential function. The F-function provides the basis for a qth order "fractional pole". Complex plane behavior is elucidated and a simple example, the inductor terminated semi- infinite lossy line, is used to demonstrate the theory.
Comparison of Tracking Codes for the International Linear Collider
Latina, A.; Schulte, D.; Smith, J.C.; Poirier, F.; Walker, N.J.; Lebrun, P.; Ranjan, K.; Kubo, K.; Tenenbaum, Peter Gregory; Eliasson, P.; /Uppsala U.
2008-01-23
In an effort to compare beam dynamics and create a ''benchmark'' for Dispersion Free Steering (DFS) a comparison was made between different International Linear Collider (ILC) simulation programs while performing DFS. This study consisted of three parts. Firstly, a simple betatron oscillation was tracked through each code. Secondly, a set of component misalignments and corrector settings generated from one program was read into the others to confirm similar emittance dilution. Thirdly, given the same set of component misalignments, DFS was performed independently in each program and the resulting emittance dilution was compared. Performance was found to agree exceptionally well in all three studies.
From hyperbolic regularization to exact hydrodynamics for linearized Grad's equations.
Colangeli, Matteo; Karlin, Iliya V; Kröger, Martin
2007-05-01
Inspired by a recent hyperbolic regularization of Burnett's hydrodynamic equations [A. Bobylev, J. Stat. Phys. 124, 371 (2006)], we introduce a method to derive hyperbolic equations of linear hydrodynamics to any desired accuracy in Knudsen number. The approach is based on a dynamic invariance principle which derives exact constitutive relations for the stress tensor and heat flux, and a transformation which renders the exact equations of hydrodynamics hyperbolic and stable. The method is described in detail for a simple kinetic model -- a 13 moment Grad system.
High-Resolution Rotary-To-Linear Motion Converter
NASA Technical Reports Server (NTRS)
Millam, M. Bruce; Studer, Philip
1992-01-01
Compact rotary-to-linear motion converter combines high load-carrying ability with finely resolvable movement. Simple and inexpensive to manufacture. Helical coil of metal ribbon wrapped around spool. Bearing supports spool on fixed base. Restraining bar prevents collar from rotating, but allows it to rise and fall. 1,000-turn coil of ribbon 0.010 in. thick provides for translation of collar over distance of 10 inches. Coil made from flattened roll-formed wire. Material inexpensive, strong, and resistant to fatigue.
Thermodynamic formalism and linear response theory for nonequilibrium steady states
NASA Astrophysics Data System (ADS)
Speck, Thomas
2016-08-01
We study the linear response in systems driven away from thermal equilibrium into a nonequilibrium steady state with nonvanishing entropy production rate. A simple derivation of a general response formula is presented under the condition that the generating function describes a transformation that (to lowest order) preserves normalization and thus describes a physical stochastic process. For Markov processes we explicitly construct the conjugate quantities and discuss their relation with known response formulas. Emphasis is put on the formal analogy with thermodynamic potentials and some consequences are discussed.
Steady-state decoupling and design of linear multivariable systems
NASA Technical Reports Server (NTRS)
Thaler, G. J.
1974-01-01
A constructive criterion for decoupling the steady states of a linear time-invariant multivariable system is presented. This criterion consists of a set of inequalities which, when satisfied, will cause the steady states of a system to be decoupled. Stability analysis and a new design technique for such systems are given. A new and simple connection between single-loop and multivariable cases is found. These results are then applied to the compensation design for NASA STOL C-8A aircraft. Both steady-state decoupling and stability are justified through computer simulations.
Challenges in future linear colliders
Swapan Chattopadhyay; Kaoru Yokoya
2002-09-02
For decades, electron-positron colliders have been complementing proton-proton colliders. But the circular LEP, the largest e-e+ collider, represented an energy limit beyond which energy losses to synchrotron radiation necessitate moving to e-e+ linear colliders (LCs), thereby raising new challenges for accelerator builders. Japanese-American, German, and European collaborations have presented options for the Future Linear Collider (FLC). Key accelerator issues for any FLC option are the achievement of high enough energy and luminosity. Damping rings, taking advantage of the phenomenon of synchrotron radiation, have been developed as the means for decreasing beam size, which is crucial for ensuring a sufficiently high rate of particle-particle collisions. Related challenges are alignment and stability in an environment where even minute ground motion can disrupt performance, and the ability to monitor beam size. The technical challenges exist within a wider context of socioeconomic and political challenges, likely necessitating continued development of international collaboration among parties involved in accelerator-based physics.
Linear Response for Intermittent Maps
NASA Astrophysics Data System (ADS)
Baladi, Viviane; Todd, Mike
2016-11-01
We consider the one parameter family {α mapsto T_{α}} ({α in [0,1)}) of Pomeau-Manneville type interval maps {T_{α}(x) = x(1+2^{α} x^{α})} for {x in [0,1/2)} and {T_{α}(x)=2x-1} for {x in [1/2, 1]}, with the associated absolutely continuous invariant probability measure {μ_{α}}. For {α in (0,1)}, Sarig and Gouëzel proved that the system mixes only polynomially with rate {n^{1-1/{α}}} (in particular, there is no spectral gap). We show that for any {ψ in Lq}, the map {α to int_01 ψ d μ_{α}} is differentiable on {[0,1-1/q)}, and we give a (linear response) formula for the value of the derivative. This is the first time that a linear response formula for the SRB measure is obtained in the setting of slowly mixing dynamics. Our argument shows how cone techniques can be used in this context. For {α ≥ 1/2} we need the {n^{-1/{α}}} decorrelation obtained by Gouëzel under additional conditions.
Repair of overheating linear accelerator
Barkley, Walter; Baldwin, William; Bennett, Gloria; Bitteker, Leo; Borden, Michael; Casados, Jeff; Fitzgerald, Daniel; Gorman, Fred; Johnson, Kenneth; Kurennoy, Sergey; Martinez, Alberto; O’Hara, James; Perez, Edward; Roller, Brandon; Rybarcyk, Lawrence; Stark, Peter; Stockton, Jerry
2004-01-01
Los Alamos Neutron Science Center (LANSCE) is a proton accelerator that produces high energy particle beams for experiments. These beams include neutrons and protons for diverse uses including radiography, isotope production, small feature study, lattice vibrations and material science. The Drift Tube Linear Accelerator (DTL) is the first portion of a half mile long linear section of accelerator that raises the beam energy from 750 keV to 100 MeV. In its 31st year of operation (2003), the DTL experienced serious issues. The first problem was the inability to maintain resonant frequency at full power. The second problem was increased occurrences of over-temperature failure of cooling hoses. These shortcomings led to an investigation during the 2003 yearly preventative maintenance shutdown that showed evidence of excessive heating: discolored interior tank walls and coper oxide deposition in the cooling circuits. Since overheating was suspected to be caused by compromised heat transfer, improving that was the focus of the repair effort. Investigations revealed copper oxide flow inhibition and iron oxide scale build up. Acid cleaning was implemented with careful attention to protection of the base metal, selection of components to clean and minimization of exposure times. The effort has been very successful in bringing the accelerator through a complete eight month run cycle allowing an incredible array of scientific experiments to be completed this year (2003-2004). This paper will describe the systems, investigation analysis, repair, return to production and conclusion.
Evolution equation for non-linear cosmological perturbations
Brustein, Ram; Riotto, Antonio E-mail: Antonio.Riotto@cern.ch
2011-11-01
We present a novel approach, based entirely on the gravitational potential, for studying the evolution of non-linear cosmological matter perturbations. Starting from the perturbed Einstein equations, we integrate out the non-relativistic degrees of freedom of the cosmic fluid and obtain a single closed equation for the gravitational potential. We then verify the validity of the new equation by comparing its approximate solutions to known results in the theory of non-linear cosmological perturbations. First, we show explicitly that the perturbative solution of our equation matches the standard perturbative solutions. Next, using the mean field approximation to the equation, we show that its solution reproduces in a simple way the exponential suppression of the non-linear propagator on small scales due to the velocity dispersion. Our approach can therefore reproduce the main features of the renormalized perturbation theory and (time)-renormalization group approaches to the study of non-linear cosmological perturbations, with some possibly important differences. We conclude by a preliminary discussion of the nature of the full solutions of the equation and their significance.
Completely monolithic linearly polarized high-power fiber laser oscillator
NASA Astrophysics Data System (ADS)
Belke, Steffen; Becker, Frank; Neumann, Benjamin; Ruppik, Stefan; Hefter, Ulrich
2014-03-01
We have demonstrated a linearly polarized cw all-in-fiber oscillator providing 1 kW of output power and a polarization extinction ratio (PER) of up to 21.7 dB. The design of the laser oscillator is simple and consists of an Ytterbium-doped polarization maintaining large mode area (PLMA) fiber and suitable fiber Bragg gratings (FBG) in matching PLMA fibers. The oscillator has nearly diffraction-limited beam quality (M² < 1.2). Pump power is delivered via a high power 6+1:1 pump coupler. The slope efficiency of the laser is 75 %. The electro/optical efficiency of the complete laser system is ~30 % and hence in the range of Rofin's cw non-polarized fiber lasers. Choosing an adequate bending diameter for the Yb-doped PLMA fiber, one polarization mode as well as higher order modes are sufficiently supressed1. Resulting in a compact and robust linearly polarized high power single mode laser without external polarizing components. Linearly polarized lasers are well established for one dimensional cutting or welding applications. Using beam shaping optics radially polarized laser light can be generated to be independent from the angle of incident to the processing surface. Furthermore, high power linearly polarized laser light is fundamental for nonlinear frequency conversion of nonlinear materials.
Linear and nonlinear effects in detonation wave structure formation
NASA Astrophysics Data System (ADS)
Borisov, S. P.; Kudryavtsev, A. N.
2016-06-01
The role of linear and nonlinear effects in the process of formation of detonation wave structure is investigated using linear stability analysis and direct numerical simulation. A simple model with a one-step irreversible chemical reaction is considered. For linear stability computations, both the local iterative shooting procedure and the global Chebyshev pseudospectral method are employed. Numerical simulations of 1D pulsating instability are performed using a shock fitting approach based on a 5th order upwind-biased compact-difference discretization and a shock acceleration equation deduced from the Rankine-Hugoniot conditions. A shock capturing WENO scheme of the 5th order is used to simulate propagation of detonation wave in a plane channel. It is shown that the linear analysis predicts correctly the mode dominating on early stages of flow evolution and the size of detonation cells which emerge during these stages. Later, however, when a developed self-reproducing cellular structure forms, the cell size is approximately doubled due to nonlinear effects.
The generalized sidelobe canceller based on quaternion widely linear processing.
Tao, Jian-wu; Chang, Wen-xiu
2014-01-01
We investigate the problem of quaternion beamforming based on widely linear processing. First, a quaternion model of linear symmetric array with two-component electromagnetic (EM) vector sensors is presented. Based on array's quaternion model, we propose the general expression of a quaternion semiwidely linear (QSWL) beamformer. Unlike the complex widely linear beamformer, the QSWL beamformer is based on the simultaneous operation on the quaternion vector, which is composed of two jointly proper complex vectors, and its involution counterpart. Second, we propose a useful implementation of QSWL beamformer, that is, QSWL generalized sidelobe canceller (GSC), and derive the simple expressions of the weight vectors. The QSWL GSC consists of two-stage beamformers. By designing the weight vectors of two-stage beamformers, the interference is completely canceled in the output of QSWL GSC and the desired signal is not distorted. We derive the array's gain expression and analyze the performance of the QSWL GSC in the presence of one type of interference. The advantage of QSWL GSC is that the main beam can always point to the desired signal's direction and the robustness to DOA mismatch is improved. Finally, simulations are used to verify the performance of the proposed QSWL GSC. PMID:24955425
The Generalized Sidelobe Canceller Based on Quaternion Widely Linear Processing
Tao, Jian-wu; Chang, Wen-xiu
2014-01-01
We investigate the problem of quaternion beamforming based on widely linear processing. First, a quaternion model of linear symmetric array with two-component electromagnetic (EM) vector sensors is presented. Based on array's quaternion model, we propose the general expression of a quaternion semiwidely linear (QSWL) beamformer. Unlike the complex widely linear beamformer, the QSWL beamformer is based on the simultaneous operation on the quaternion vector, which is composed of two jointly proper complex vectors, and its involution counterpart. Second, we propose a useful implementation of QSWL beamformer, that is, QSWL generalized sidelobe canceller (GSC), and derive the simple expressions of the weight vectors. The QSWL GSC consists of two-stage beamformers. By designing the weight vectors of two-stage beamformers, the interference is completely canceled in the output of QSWL GSC and the desired signal is not distorted. We derive the array's gain expression and analyze the performance of the QSWL GSC in the presence of one type of interference. The advantage of QSWL GSC is that the main beam can always point to the desired signal's direction and the robustness to DOA mismatch is improved. Finally, simulations are used to verify the performance of the proposed QSWL GSC. PMID:24955425
Gaussian fluctuations and linear response in an electron transfer protein
Simonson, Thomas
2002-01-01
In response to charge separation or transfer, polar liquids respond in a simple linear fashion. A similar linear response for proteins might be expected from the central limit theorem and is postulated in widely used theories of protein electrostatics, including the Marcus electron transfer theory and dielectric continuum theories. Although these theories are supported by a variety of experimental data, the exact validity of a linear protein dielectric response has been difficult to determine. Molecular dynamics simulations are presented that establish a linear dielectric response of both protein and surrounding solvent over the course of a biologically relevant electron transfer reaction: oxido-reduction of yeast cytochrome c in solution. Using an umbrella-sampling free energy approach with long simulations, an accurate treatment of long-range electrostatics and both classical and quantum models of the heme, good agreement is obtained with experiment for the redox potential relative to a heme–octapeptide complex. We obtain a reorganization free energy that is only half that for heme–octapeptide and is reproduced with a dielectric continuum model where the heme vicinity has a dielectric constant of only 1.1. This value implies that the contribution of protein reorganization to the electron transfer free energy barrier is reduced almost to the theoretical limit (a dielectric of one), and that the fluctuations of the electrostatic potential on the heme have a simple harmonic form, in accord with Marcus theory, even though the fluctuations of many individual protein groups (especially at the protein surface) are anharmonic. PMID:12011418
Simple microfluidic stagnation point flow geometries.
Dockx, Greet; Verwijlen, Tom; Sempels, Wouter; Nagel, Mathias; Moldenaers, Paula; Hofkens, Johan; Vermant, Jan
2016-07-01
A geometrically simple flow cell is proposed to generate different types of stagnation flows, using a separation flow and small variations of the geometric parameters. Flows with high local deformation rates can be changed from purely rotational, over simple shear flow, to extensional flow in a region surrounding a stagnation point. Computational fluid dynamic calculations are used to analyse how variations of the geometrical parameters affect the flow field. These numerical calculations are compared to the experimentally obtained streamlines of different designs, which have been determined by high speed confocal microscopy. As the flow type is dictated predominantly by the geometrical parameters, such simple separating flow devices may alleviate the requirements for flow control, while offering good stability for a wide variety of flow types. PMID:27462382
Maximal temperature in a simple thermodynamical system
NASA Astrophysics Data System (ADS)
Dai, De-Chang; Stojkovic, Dejan
2016-06-01
Temperature in a simple thermodynamical system is not limited from above. It is also widely believed that it does not make sense talking about temperatures higher than the Planck temperature in the absence of the full theory of quantum gravity. Here, we demonstrate that there exist a maximal achievable temperature in a system where particles obey the laws of quantum mechanics and classical gravity before we reach the realm of quantum gravity. Namely, if two particles with a given center of mass energy come at the distance shorter than the Schwarzschild diameter apart, according to classical gravity they will form a black hole. It is possible to calculate that a simple thermodynamical system will be dominated by black holes at a critical temperature which is about three times lower than the Planck temperature. That represents the maximal achievable temperature in a simple thermodynamical system.
Converting simple vegetation surveys in functional dynamics
NASA Astrophysics Data System (ADS)
Fernandes, Claúdia; Cabral, João Alexandre; Crespí, António Luís; Hughes, Samantha Jane; Santos, Mário
2013-04-01
This study assessed an integrated method for estimating the structural and functional trends of Mediterranean vegetation based on simple field characterizations. Despite considerable effort made by scientists to estimate vegetation dynamics, most methods are too complex to be applied and quantification achieved by non-specialists. We propose an alternative approach that converts simple measures such as generic vegetation cover into life forms or life traits. We used the Stochastic Dynamic Methodology, a dynamic approach based on a sequential process, to calculate the functional response to succession and anthropogenic disturbances using Raunkiaer's life form spectra. Using derived scenarios, the model was able to successfully translate functional and structural trends from simple field descriptions. The simulations demonstrate that this methodology can be used in environmental studies, particularly when specialised field botanists are not available.
Computing Linear Mathematical Models Of Aircraft
NASA Technical Reports Server (NTRS)
Duke, Eugene L.; Antoniewicz, Robert F.; Krambeer, Keith D.
1991-01-01
Derivation and Definition of Linear Aircraft Model (LINEAR) computer program provides user with powerful, and flexible, standard, documented, and verified software tool for linearization of mathematical models of aerodynamics of aircraft. Intended for use in software tool to drive linear analysis of stability and design of control laws for aircraft. Capable of both extracting such linearized engine effects as net thrust, torque, and gyroscopic effects, and including these effects in linear model of system. Designed to provide easy selection of state, control, and observation variables used in particular model. Also provides flexibility of allowing alternate formulations of both state and observation equations. Written in FORTRAN.
A free lunch in linearized experimental design?
NASA Astrophysics Data System (ADS)
Coles, D.; Curtis, A.
2009-12-01
The No Free Lunch (NFL) theorems state that no single optimization algorithm is ideally suited for all objective functions and, conversely, that no single objective function is ideally suited for all optimization algorithms (Wolpert and Macready, 1997). It is therefore of limited use to report the performance of a particular algorithm with respect to a particular objective function because the results cannot be safely extrapolated to other algorithms or objective functions. We examine the influence of the NFL theorems on linearized statistical experimental design (SED). We are aware of no publication that compares multiple design criteria in combination with multiple design algorithms. We examine four design algorithms in concert with three design objective functions to assess their interdependency. As a foundation for the study, we consider experimental designs for fitting ellipses to data, a problem pertinent, for example, to the study of transverse isotropy in a variety of disciplines. Surprisingly, we find that the quality of optimized experiments, and the computational efficiency of their optimization, is generally independent of the criterion-algorithm pairing. This is promising for linearized SED. While the NFL theorems must generally be true, the criterion-algorithm pairings we investigated are fairly robust to the theorems, indicating that we need not account for independency when choosing design algorithms and criteria from the set examined here. However, particular design algorithms do show patterns of performance, irrespective of the design criterion, and from this we establish a rough guideline for choosing from the examined algorithms for other design problems. As a by-product of our study we demonstrate that SED is subject to the principle of diminishing returns. That is, we see that the value of experimental design decreases with survey size, a fact that must be considered when deciding whether or not to design an experiment at all. Another outcome
Portmanteau Constructions, Phrase Structure, and Linearization
Chan, Brian Hok-Shing
2015-01-01
In bilingual code-switching which involves language-pairs with contrasting head-complement orders (i.e., head-initial vs. head-final), a head may be lexicalized from both languages with its complement sandwiched in the middle. These so-called “portmanteau” sentences (Nishimura, 1985, 1986; Sankoff et al., 1990, etc.) have been attested for decades, but they had never received a systematic, formal analysis in terms of current syntactic theory before a few recent attempts (Hicks, 2010, 2012). Notwithstanding this lack of attention, these structures are in fact highly relevant to theories of linearization and phrase structure. More specifically, they challenge binary-branching (Kayne, 1994, 2004, 2005) as well as the Antisymmetry hypothesis (ibid.). Not explained by current grammatical models of code-switching, including the Equivalence Constraint (Poplack, 1980), the Matrix Language Frame Model (Myers-Scotton, 1993, 2002, etc.), and the Bilingual Speech Model (Muysken, 2000, 2013), the portmanteau construction indeed looks uncommon or abnormal, defying any systematic account. However, the recurrence of these structures in various datasets and constraints on them do call for an explanation. This paper suggests an account which lies with syntax and also with the psycholinguistics of bilingualism. Assuming that linearization is a process at the Sensori-Motor (SM) interface (Chomsky, 2005, 2013), this paper sees that word order is not fixed in a syntactic tree but it is set in the production process, and much information of word order rests in the processor, for instance, outputting a head before its complement (i.e., head-initial word order) or the reverse (i.e., head-final word order). As for the portmanteau construction, it is the output of bilingual speakers co-activating two sets of head-complement orders which summon the phonetic forms of the same word in both languages. Under this proposal, the underlying structure of a portmanteau construction is as simple as