WorldWideScience

Sample records for superimposed exponential signals

  1. Analyses and Measures of GPR Signal with Superimposed Noise

    Science.gov (United States)

    Chicarella, Simone; Ferrara, Vincenzo; D'Atanasio, Paolo; Frezza, Fabrizio; Pajewski, Lara; Pavoncello, Settimio; Prontera, Santo; Tedeschi, Nicola; Zambotti, Alessandro

    2014-05-01

    The influence of EM noises and environmental hard conditions on the GPR surveys has been examined analytically [1]. In the case of pulse radar GPR, many unwanted signals as stationary clutter, non-stationary clutter, random noise, and time jitter, influence the measurement signal. When GPR is motionless, stationary clutter is the most dominant signal component due to the reflections of static objects different from the investigated target, and to the direct antenna coupling. Moving objects like e.g. persons and vehicles, and the swaying of tree crown, produce non-stationary clutter. Device internal noise and narrowband jamming are e.g. two potential sources of random noises. Finally, trigger instabilities generate random jitter. In order to estimate the effective influence of these noise signal components, we organized some experimental setup of measurement. At first, we evaluated for the case of a GPR basic detection, simpler image processing of radargram. In the future, we foresee experimental measurements for detection of the Doppler frequency changes induced by movements of targets (like physiological movements of survivors under debris). We obtain image processing of radargram by using of GSSI SIR® 2000 GPR system together with the UWB UHF GPR-antenna (SUB-ECHO HBD 300, a model manufactured by Radarteam company). Our work includes both characterization of GPR signal without (or almost without) a superimposed noise, and the effect of jamming originated from the coexistence of a different radio signal. For characterizing GPR signal, we organized a measurement setup that includes the following instruments: mod. FSP 30 spectrum analyser by Rohde & Schwarz which operates in the frequency range 9 KHz - 30 GHz, mod. Sucoflex 104 cable by Huber Suhner (10 MHz - 18 GHz), and HL050 antenna by Rohde & Schwarz (bandwidth: from 850 MHz to 26.5 GHz). The next analysis of superimposed jamming will examine two different signal sources: by a cellular phone and by a

  2. Superimpose signal processing method for micro-scale thermal imaging of solar salts at high temperature

    Science.gov (United States)

    Morikawa, Junko; Zamengo, Massimiliano; Kato, Yukitaka

    2016-05-01

    The global interest in energy applications activates the advanced study about the molten salts in the usage of fluids in the power cycle, such as for transport and heat storage in solar power facilities. However, the basic properties of molten salts show a general scattering in characterization especially in thermal properties. It is suggested that new studies are required on the measurement of thermal properties of solar salts using recent technologies. In this study, micro-scale heat transfer and phase change in molten salts are presented using our originally developed device: the micro-bolometer Infrared focal plane arrays (IR FPA) measuring system is a portable type instrument, which is re-designed to measure the thermal phenomena in high temperature up to 700 °C or higher. The superimpose system is newly setup adjusted to the signal processing in high temperature to realize the quantitative thermal imaging, simultaneously. The portable type apparatus for a quantitative micro-scale thermography using a micro-bolometer has been proposed based on an achromatic lens design to capture a micro-scale image in the long-wave infrared, a video signal superimposing for the real time emissivity correction, and a pseudo acceleration of a timeframe. Combined with the superimpose technique, the micro-scale thermal imaging in high temperature is achieved and the molten flows of the solar salts, sodium nitrate, and potassium nitrate are successfully observed. The solar salt, the mixture of sodium nitrate and potassium nitrate, shows a different shape of exothermic heat front morphology in the lower phase transition (solidification) temperature than the nitrates on cooling. The proposed measuring technique will be utilized to accelerate the screening step to determine the phase diagram and the eutectics of the multiple mixtures of candidate molten salts, which may be used as heat transport medium from the concentrated solar power to a processing plant for thermal energy

  3. Feasibility study of monitoring of plasma etching chamber conditions using superimposed high-frequency signals on rf power transmission line.

    Science.gov (United States)

    Kasashima, Y; Uesugi, F

    2015-10-01

    An in situ monitoring system that can detect changes in the conditions of a plasma etching chamber has been developed. In the system, low-intensity high-frequency signals are superimposed on the rf power transmission line used for generating plasma. The system measures reflected high-frequency signals and detects the change in their frequency characteristics. The results indicate that the system detects the changes in the conditions in etching chambers caused by the changes in the electrode gap and the inner wall condition and demonstrate the effectiveness of the system. The system can easily be retrofitted to mass-production equipment and it can be used with or without plasma discharge. Therefore, our system is suitable for in situ monitoring of mass-production plasma etching chambers. The system is expected to contribute to development of predictive maintenance, which monitors films deposited on the inner wall of the chamber and prevents equipment faults caused by misalignment of chamber parts in mass-production equipment.

  4. Exponential signaling gain at the receptor level enhances signal-to-noise ratio in bacterial chemotaxis.

    Directory of Open Access Journals (Sweden)

    Silke Neumann

    Full Text Available Cellular signaling systems show astonishing precision in their response to external stimuli despite strong fluctuations in the molecular components that determine pathway activity. To control the effects of noise on signaling most efficiently, living cells employ compensatory mechanisms that reach from simple negative feedback loops to robustly designed signaling architectures. Here, we report on a novel control mechanism that allows living cells to keep precision in their signaling characteristics - stationary pathway output, response amplitude, and relaxation time - in the presence of strong intracellular perturbations. The concept relies on the surprising fact that for systems showing perfect adaptation an exponential signal amplification at the receptor level suffices to eliminate slowly varying multiplicative noise. To show this mechanism at work in living systems, we quantified the response dynamics of the E. coli chemotaxis network after genetically perturbing the information flux between upstream and downstream signaling components. We give strong evidence that this signaling system results in dynamic invariance of the activated response regulator against multiplicative intracellular noise. We further demonstrate that for environmental conditions, for which precision in chemosensing is crucial, the invariant response behavior results in highest chemotactic efficiency. Our results resolve several puzzling features of the chemotaxis pathway that are widely conserved across prokaryotes but so far could not be attributed any functional role.

  5. Multi-exponential inversions of nuclear magnetic resonance relaxation signal

    Institute of Scientific and Technical Information of China (English)

    王为民; 叶朝辉; 李培

    2001-01-01

    Beginning from the first kind of integral equation, two kinds of methods, i. e. Singular Value Decomposition (SVD) and transform that are fit for the inversion calculation of NMR multi-relaxation data from rock, have been derived. The mathematical processing was discussed in detail. The advantage and disadvantage of the two methods have been compared in theory and application. From the view of the degree of freedom of the inversion solution, we discussed the resolution of the solution of NMR relaxation inversion and the selection of optimal inversion modeling. Results showed that SVD method is fit for the inversion of NMR relaxation data with a higher signal to noise ratio and transform inversion method is more flexible and can be used in NMR data with a lower signal to noise ratio. It is advisable that transform inversion method be selected for the multi-relaxation inversion of rock NMR data. SVD method can be used when the signal to noise ratio is better than 80. In order to ensure the accuracy, the number of T2 points should be varied from 30 to 50. The results of the research are useful for NMR core analysis and the interpretation of NMR logging data.

  6. Global exponential stability and dissipativity of generalized neural networks with time-varying delay signals.

    Science.gov (United States)

    Manivannan, R; Samidurai, R; Cao, Jinde; Alsaedi, Ahmed; Alsaadi, Fuad E

    2017-03-01

    This paper investigates the problems of exponential stability and dissipativity of generalized neural networks (GNNs) with time-varying delay signals. By constructing a novel Lyapunov-Krasovskii functionals (LKFs) with triple integral terms that contain more advantages of the state vectors of the neural networks, and the upper bound on the time-varying delay signals are formulated. We employ a new integral inequality technique (IIT), free-matrix-based (FMB) integral inequality approach, and Wirtinger double integral inequality (WDII) technique together with the reciprocally convex combination (RCC) approach to bound the time derivative of the LKFs. An improved exponential stability and strictly (Q,S,R)-γ-dissipative conditions of the addressed systems are represented by the linear matrix inequalities (LMIs). Finally, four interesting numerical examples are developed to verify the usefulness of the proposed method with a practical application to a biological network. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Capacity-Approaching Signal Constellations for the Additive Exponential Noise Channel

    CERN Document Server

    Goff, Stéphane Y Le

    2011-01-01

    We present a new family of signal constellations, called log constellations, that can be used to design near-capacity coded modulation schemes over additive exponential noise (AEN) channels. Log constellations are designed by geometrically approximating the input distribution that maximizes the AEN channel capacity. The mutual information achievable over AEN channels with both coded modulation (CM) and bit-interleaved coded modulation (BICM) approaches is evaluated for various signal sets. In the case of CM, the proposed log constellations outperform, sometimes by over half a decibel, the best existing signal sets available from the literature, and can display error performance within only 0.12 dB of the AEN channel capacity. In the context of BICM, log constellations do not offer significant performance advantages over the best existing constellations. As the potential performance degradation resulting from the use of BICM instead of CM is larger than 1 dB, BICM may however not be a suitable design approach ...

  8. [Superimposed lichen planus pigmentosus].

    Science.gov (United States)

    Monteagudo, Benigno; Suarez-Amor, Óscar; Cabanillas, Miguel; de Las Heras, Cristina; Álvarez, Juan Carlos

    2014-05-16

    Lichen planus pigmentosus is an uncommon variant of lichen planus that is characterized by the insidious onset of dark brown macules in sun-exposed areas and flexural folds. Superimposed linear lichen planus is an exceedingly rare disorder, but it has been found in both lichen planopilaris and lichen planus types. A 39-year-old woman is presented showing a segmental and linear lichen planus associated with non-segmental lesions meeting all criteria for the diagnosis of superimposed linear planus pigmentosus. The segmental lesions were always more pronounced.

  9. Improved exponential convergence result for generalized neural networks including interval time-varying delayed signals.

    Science.gov (United States)

    Rajchakit, G; Saravanakumar, R; Ahn, Choon Ki; Karimi, Hamid Reza

    2017-02-01

    This article examines the exponential stability analysis problem of generalized neural networks (GNNs) including interval time-varying delayed states. A new improved exponential stability criterion is presented by establishing a proper Lyapunov-Krasovskii functional (LKF) and employing new analysis theory. The improved reciprocally convex combination (RCC) and weighted integral inequality (WII) techniques are utilized to obtain new sufficient conditions to ascertain the exponential stability result of such delayed GNNs. The superiority of the obtained results is clearly demonstrated by numerical examples.

  10. Regulation of Indole Signalling during the Transition of E. coli from Exponential to Stationary Phase.

    Science.gov (United States)

    Gaimster, Hannah; Summers, David

    2015-01-01

    During the transition from exponential to stationary phase E. coli produces a substantial quantity of the small, aromatic signalling molecule indole. In LB medium the supernatant indole concentration reaches a maximum of 0.5-1 mM. At this concentration indole has been implicated in many processes inducing acid resistance and the modulation of virulence. It has recently been shown that cell-associated indole transiently reaches a very high concentration (approx. 60 mM) during stationary phase entry, presumably because indole is being produced more rapidly than it can leave the cell. It is proposed that this indole pulse inhibits growth and cell division, causing the culture to enter stationary phase before nutrients are completely exhausted, with benefits for survival in long-term stationary phase. This study asks how E. coli cells rapidly upregulate indole production during stationary phase entry and why the indole pulse has a duration of only 10-15 min. We find that at the start of the pulse tryptophanase synthesis is triggered by glucose depletion and that this is correlates with the up-regulation of indole synthesis. The magnitude and duration of the resulting indole pulse are dependent upon the availability of exogenous tryptophan. Indole production stops when all the available tryptophan is depleted and the cell-associated indole equilibrates with the supernatant.

  11. Research on Superimposed Metallogenic System

    Institute of Scientific and Technical Information of China (English)

    Zhai Yusheng; Wang Jianping; Deng Jun; Peng Runmin

    2004-01-01

    As located in the junction of three tectonic plates (the Eurasian plate, the Indian plate and the west Pacific plate), the China continent shows complex regional metallogenic features due to tectonic evolution of "micro-plates, polycycle tectonic movements". Well developed superimposed metallogenic systems have constituted one of the regional metallogenic features in China. Through the study on superimposed metallogenic system of the middle and lower reaches of the Yangtze River and of the Yuebei basin (northern Guangdong Province), the authors put forward some basic combination pattern of sedimentary-magmatic superimposed metallogenic system and summarize its forming conditions (controlling factors).

  12. Exponential increase of signal crayfish in running waters in Sweden – due to illegal introductions?

    Directory of Open Access Journals (Sweden)

    Bohman P.

    2011-07-01

    Full Text Available Sweden has only one indigenous species of crayfish, the noble crayfish (Astacus astacus, Fabricius. There has been a steady decline of noble crayfish populations in Sweden since 1907, mainly due to the crayfish plague. To substitute the noble crayfish fishery lost, the Swedish government launched a large-scale introduction of the signal crayfish (Pacifastacus leniusculus Dana. Today, the signal crayfish is regarded as a chronic carrier of the crayfish plague, and an expansion of the species may seriously threaten the noble crayfish. This paper examines the decrease of noble crayfish populations, and the concurrent expansion of signal crayfish in running waters. Data from the Swedish Electrofishing RegiSter (SERS was used. We found that in 1980–1984 the noble crayfish occurred in 4.5% of the studied river sections. In 2008–2009 the occurrences had decreased to 1.9%. In contrast, the signal crayfish had increased in occurrence, from 0.2% (1980–1984 to 11.8% in (2008–2009. We studied the number of stocking permits for signal crayfish introductions, and the available signal crayfish population from the open fishery in Lake Vättern, as possible causes of this expansion. A negative correlation between stocking permits and increased occurrence in streams, and a positive correlation between the availability of crayfish in Lake Vättern and the occurrence in streams was found. This suggests that the expansion of signal crayfish may be due to illegal introductions, further endangering the endemic noble crayfish.

  13. POWER ALLOCATION OF DATA DEPENDENT SUPERIMPOSED TRAINING

    Institute of Scientific and Technical Information of China (English)

    Wang Ping; Yuan Weina; Fan Pingzhi

    2008-01-01

    Data Dependent Superimposed Training (DDST) scheme outperforms the traditional superimposed training by fully canceling the effects of unknown data in channel estimator. In DDST,however,the channel estimation accuracy and the data detection or channel equalization performance are affected significantly by the amount of power allocated to data and superimposed training sequence,which is the motivation of this research. In general,for DDST,there is a tradeoff between the channel estimation accuracy and the data detection reliability,i.e.,the more accurate the channel estimation,the more reliable the data detection; on the other hand,the more accurate the channel estimation,the more demanding on the power consumption of training sequence,which in turn leads to the less reliable data detection. In this paper,the relationship between the Signal-to-Noise Ratio (SNR) of the data detector and the training sequence power is analyzed. The optimal power allocation of the training sequence is derived based on the criterion of maximizing SNR of the detector. Analysis and simulation results show that for a fixed transmit power,the SNR and the Symbol Error Rate (SER) of detector vary nonlinearly with the increasing of training sequence power,and there exists an optimal power ratio,which accords with the derived optimal power ratio,among the data and training sequence.

  14. Exponential triples

    CERN Document Server

    Sisto, Alessandro

    2011-01-01

    Using ultrafilter techniques we show that in any partition of $\\mathbb{N}$ into 2 cells there is one cell containing infinitely many exponential triples, i.e. triples of the kind $a,b,a^b$ (with $a,b>1$). Also, we will show that any multiplicative $IP^*$ set is an "exponential $IP$ set", the analogue of an $IP$ set with respect to exponentiation.

  15. Generalization of the normal-exponential model: exploration of a more accurate parametrisation for the signal distribution on Illumina BeadArrays.

    Science.gov (United States)

    Plancade, Sandra; Rozenholc, Yves; Lund, Eiliv

    2012-12-11

    Illumina BeadArray technology includes non specific negative control features that allow a precise estimation of the background noise. As an alternative to the background subtraction proposed in BeadStudio which leads to an important loss of information by generating negative values, a background correction method modeling the observed intensities as the sum of the exponentially distributed signal and normally distributed noise has been developed. Nevertheless, Wang and Ye (2012) display a kernel-based estimator of the signal distribution on Illumina BeadArrays and suggest that a gamma distribution would represent a better modeling of the signal density. Hence, the normal-exponential modeling may not be appropriate for Illumina data and background corrections derived from this model may lead to wrong estimation. We propose a more flexible modeling based on a gamma distributed signal and a normal distributed background noise and develop the associated background correction, implemented in the R-package NormalGamma. Our model proves to be markedly more accurate to model Illumina BeadArrays: on the one hand, it is shown on two types of Illumina BeadChips that this model offers a more correct fit of the observed intensities. On the other hand, the comparison of the operating characteristics of several background correction procedures on spike-in and on normal-gamma simulated data shows high similarities, reinforcing the validation of the normal-gamma modeling. The performance of the background corrections based on the normal-gamma and normal-exponential models are compared on two dilution data sets, through testing procedures which represent various experimental designs. Surprisingly, we observe that the implementation of a more accurate parametrisation in the model-based background correction does not increase the sensitivity. These results may be explained by the operating characteristics of the estimators: the normal-gamma background correction offers an improvement

  16. The exponential rank of nonarchimedean exponential fields

    OpenAIRE

    Kuhlmann, Franz-Viktor; Kuhlmann, Salma

    2000-01-01

    For an exponential on a nonarchimedean ordered field, we introduce the notion of the exponential rank, in analogy to the rank of the field. This gives information about the growth rate of the exponential, and about the convex valuations on the field which are compatible with the exponential. We give several characterizations of these valuations, using maps induced by the exponential on the value group of the natural valuation and on the rank of the field. Finally, we construct exponential fie...

  17. Characterization of gradient echo signal decays in healthy and cancerous prostate at 3T improves with a Gaussian augmentation of the mono-exponential (GAME) model.

    Science.gov (United States)

    Ciris, Pelin Aksit; Balasubramanian, Mukund; Seethamraju, Ravi T; Tokuda, Junichi; Scalera, Jonathan; Penzkofer, Tobias; Fennessy, Fiona M; Tempany-Afdhal, Clare M; Tuncali, Kemal; Mulkern, Robert V

    2016-07-01

    A biomarker of cancer aggressiveness, such as hypoxia, could substantially impact treatment decisions in the prostate, especially radiation therapy, by balancing treatment morbidity (urinary incontinence, erectile dysfunction, etc.) against mortality. R2 (*) mapping with Mono-Exponential (ME) decay modeling has shown potential for identifying areas of prostate cancer hypoxia at 1.5T. However, Gaussian deviations from ME decay have been observed in other tissues at 3T. The purpose of this study is to assess whether gradient-echo signal decays are better characterized by a standard ME decay model, or a Gaussian Augmentation of the Mono-Exponential (GAME) decay model, in the prostate at 3T. Multi-gradient-echo signals were acquired on 20 consecutive patients with a clinical suspicion of prostate cancer undergoing MR-guided prostate biopsies. Data were fitted with both ME and GAME models. The information contents of these models were compared using Akaike's information criterion (second order, AICC ), in skeletal muscle, the prostate central gland (CG), and peripheral zone (PZ) regions of interest (ROIs). The GAME model had higher information content in 30% of the prostate on average (across all patients and ROIs), covering up to 67% of cancerous PZ ROIs, and up to 100% of cancerous CG ROIs (in individual patients). The higher information content of GAME became more prominent in regions that would be assumed hypoxic using ME alone, reaching 50% of the PZ and 70% of the CG as ME R2 (*) approached 40 s(-1) . R2 (*) mapping may have important applications in MRI; however, information lost due to modeling could mask differences in parameters due to underlying tissue anatomy or physiology. The GAME model improves characterization of signal behavior in the prostate at 3T, and may increase the potential for determining correlates of fit parameters with biomarkers, for example of oxygenation status.

  18. Statistical properties of superimposed stationary spike trains.

    Science.gov (United States)

    Deger, Moritz; Helias, Moritz; Boucsein, Clemens; Rotter, Stefan

    2012-06-01

    The Poisson process is an often employed model for the activity of neuronal populations. It is known, though, that superpositions of realistic, non- Poisson spike trains are not in general Poisson processes, not even for large numbers of superimposed processes. Here we construct superimposed spike trains from intracellular in vivo recordings from rat neocortex neurons and compare their statistics to specific point process models. The constructed superimposed spike trains reveal strong deviations from the Poisson model. We find that superpositions of model spike trains that take the effective refractoriness of the neurons into account yield a much better description. A minimal model of this kind is the Poisson process with dead-time (PPD). For this process, and for superpositions thereof, we obtain analytical expressions for some second-order statistical quantities-like the count variability, inter-spike interval (ISI) variability and ISI correlations-and demonstrate the match with the in vivo data. We conclude that effective refractoriness is the key property that shapes the statistical properties of the superposition spike trains. We present new, efficient algorithms to generate superpositions of PPDs and of gamma processes that can be used to provide more realistic background input in simulations of networks of spiking neurons. Using these generators, we show in simulations that neurons which receive superimposed spike trains as input are highly sensitive for the statistical effects induced by neuronal refractoriness.

  19. Paroxysmal Nocturnal Hemoglobinuria Superimposed with Preeclampsia

    Directory of Open Access Journals (Sweden)

    Mann-Ling Chen

    2006-09-01

    Conclusion: The most frequent causes of PNH-related fetomaternal morbidity and mortality are hemolysis and thrombosis. The situation becomes even more complicated when PNH is superimposed with preeclampsia. Appropriate clinical surveillance, awareness of the potential risks of hemolysis and thrombosis, as well as evaluation of fetal wellbeing are essential.

  20. Bent Solenoids with Superimposed Dipole Fields

    Energy Technology Data Exchange (ETDEWEB)

    Meinke, Rainer, B.; Goodzeit, Carl, L.

    2000-03-21

    A conceptual design and manufacturing technique were developed for a superconducting bent solenoid magnet with a superimposed dipole field that would be used as a dispersion device in the cooling channel of a future Muon Collider. The considered bent solenoid is equivalent to a 180° section of a toroid with a major radius of ~610 mm and a coil aperture of ~416 mm. The required field components of this magnet are 4 tesla for the solenoid field and 1 tesla for the superimposed dipole field. A magnet of this size and shape, operating at these field levels, has to sustain large Lorentz forces resulting in a maximum magnetic pressure of about 2,000 psi. A flexible round mini-cable with 37 strands of Cu-NbTi was selected as the superconductor. Detailed magnetic analysis showed that it is possible to obtain the required superimposed dipole field by tilting the winding planes of the solenoid by ~25°. A complete structural analysis of the coil support system and the helium containment vessel under thermal, pressure, and Lorentz force loads was carried out using 3D finite element models of the structures. The main technical issues were studied and solutions were worked out so that a highly reliable magnet of this type can be produced at an affordable cost.

  1. Superimposed MRSA infection of vulvar eczematous dermatitis

    Science.gov (United States)

    Carey, Erin; Zedek, Daniel; Lewis, Jasmine; Zolnoun, Denniz

    2014-01-01

    Background Vulvar eczematous dermatitis predisposes patients to superimposed infections, which may result in late diagnosis and architectural destruction. Methicillin resistant staphylococcus aureus (MRSA) infection is on the rise in genitalia and lower extremities. Case 44 year-old female presented with recurrent vulvar lesions and pain. A diagnosis of methicillin resistant staphylococcus aureus in the setting of eczema was achieved with concomitant use of photography and dermatopathologic review. Antibiotics were tailored to the resistant infection and preventative moisturization therapy was utilized. Conclusion Awareness of dermatologic conditions affecting the vulva is principal in routine gynecologic care. Barrier protection of eczematous vulvar skin may prevent superficial infections. The regular use of photographic documentation and dermatopathology may decrease time to diagnosis with infrequent conditions. PMID:23763013

  2. Extended Poisson Exponential Distribution

    Directory of Open Access Journals (Sweden)

    Anum Fatima

    2015-09-01

    Full Text Available A new mixture of Modified Exponential (ME and Poisson distribution has been introduced in this paper. Taking the Maximum of Modified Exponential random variable when the sample size follows a zero truncated Poisson distribution we have derived the new distribution, named as Extended Poisson Exponential distribution. This distribution possesses increasing and decreasing failure rates. The Poisson-Exponential, Modified Exponential and Exponential distributions are special cases of this distribution. We have also investigated some mathematical properties of the distribution along with Information entropies and Order statistics of the distribution. The estimation of parameters has been obtained using the Maximum Likelihood Estimation procedure. Finally we have illustrated a real data application of our distribution.

  3. Weighted exponential polynomial approximation

    Institute of Scientific and Technical Information of China (English)

    邓冠铁

    2003-01-01

    A necessary and sufficient condition for completeness of systems of exponentials with a weightin Lp is established and a quantitative relation between the weight and the system of exponential in Lp isobtained by using a generalization of Malliavin's uniqueness theorem about Watson's problem.

  4. Exponential Dowling structures

    CERN Document Server

    Ehrenborg, Richard

    2010-01-01

    The notion of exponential Dowling structures is introduced, generalizing Stanley's original theory of exponential structures. Enumerative theory is developed to determine the M\\"obius function of exponential Dowling structures, including a restriction of these structures to elements whose types satisfy a semigroup condition. Stanley's study of permutations associated with exponential structures leads to a similar vein of study for exponential Dowling structures. In particular, for the extended r-divisible partition lattice we show the M\\"obius function is, up to a sign, the number of permutations in the symmetric group on rn+k elements having descent set {r, 2r, ..., nr}. Using Wachs' original EL-labeling of the r-divisible partition lattice, the extended r-divisible partition lattice is shown to be EL-shellable.

  5. Effect of Superimposed Hydrostatic Pressure on Bendability of Sheet Metals

    Science.gov (United States)

    Chen, X. X.; Wu, P. D.; Lloyd, D. J.

    2010-06-01

    The effect of superimposed hydrostatic pressure on fracture under three-point bending is studied numerically using the finite element method based on the Gurson damage model. It is demonstrated that superimposed hydrostatic pressure significantly increases the bendability and bending fracture strain due to the fact that a superimposed pressure delays or completely eliminates the nucleation, growth and coalescence of microvoids or microcracks. Numerical results are found to be in good agreement with experimental observations.

  6. An Unusual Exponential Graph

    Science.gov (United States)

    Syed, M. Qasim; Lovatt, Ian

    2014-01-01

    This paper is an addition to the series of papers on the exponential function begun by Albert Bartlett. In particular, we ask how the graph of the exponential function y = e[superscript -t/t] would appear if y were plotted versus ln t rather than the normal practice of plotting ln y versus t. In answering this question, we find a new way to…

  7. Classification of Complex Reservoirs in Superimposed Basins of Western China

    Institute of Scientific and Technical Information of China (English)

    PANG Xiongqi; ZHOU Xinyuan; LIN Changsong; HUO Zhipeng; LUO Xiaorong; PANG Hong

    2010-01-01

    Many of the sedimentary basins in western China were formed through the superposition and compounding of at least two previously developed sedimentary basins and in general they can be termed as complex superimposed basins.The distinct differences between these basins and monotype basins are their discontinuous stratigraphic sedimentation,stratigraphic structure and stratigraphic stress-strain action over geological history.Based on the correlation of chronological age on structural sections,superimposed basins can be divided into five types in this study:(1)continuous sedimentation type superimposed basins,(2)middle and late stratigraphic superimposed basins,(3)early and late stratigraphic superimposed basins,(4)early and middle stratigraphic superimposed basins,and(5)long-term exposed superimposed basins.Multiple source-reservoir-caprock assemblages have developed in such basins.In addition,multi-stage hydrocarbon generation and expulsion,multiple sources,polycyclic hydrocarbon accumulation and multiple-type hydrocarbon reservoirs adjustment,reformation and destruction have occurred in these basins.The complex reservoirs that have been discovered widely in the superimposed basins to date have remarkably different geologic features from primary reservoirs,and the root causes of this are folding,denudation and the fracture effect caused by multiphase tectonic events in the superimposed basins as well as associated seepage,diffusion,spilling,oxidation,degradation and cracking.Based on their genesis characteristics,complex reservoirs are divided into five categories:(1)primary reservoirs,(2)trap adjustment type reservoirs,(3)component variant reservoirs,(4)phase conversion type reservoirs and(5)scale-reformed reservoirs.

  8. Methods of Fast Exponentiation

    Directory of Open Access Journals (Sweden)

    Mohammed A. Maitah

    2010-01-01

    Full Text Available Problem statement: Modular exponentiation constitutes the basis of many well-known and widely used public key cryptosystems. Approach: A fast portable modular exponentiation algorithm considerably enhanced the speed and applicability of these systems, also an efficient implementation of this algorithm was the key to high performance of such system. Results: In this study, two main approaches for solving this problem were proposed. The proposed approaches involved calculations without usage of extra operational memory for saving constants and calculations with usage of preliminary calculated constants. Conclusion/Recommendations: The estimation of complexity of the speedup and effectiveness of proposed approaches for the data were presented.

  9. Superimposed Pilots Are Superior for Mitigating Pilot Contamination in Massive MIMO

    Science.gov (United States)

    Upadhya, Karthik; Vorobyov, Sergiy A.; Vehkapera, Mikko

    2017-06-01

    In this paper, superimposed pilots are introduced as an alternative to time-multiplexed pilot and data symbols for mitigating pilot contamination in massive multiple-input multiple-output (MIMO) systems. We propose a non-iterative scheme for uplink channel estimation based on superimposed pilots and derive an expression for the uplink signal-to-interference-plus-noise ratio (SINR) at the output of a matched filter employing this channel estimate. Based on this expression, we observe that power control is essential when superimposed pilots are employed. Moreover, the quality of the channel estimate can be improved by reducing the interference that results from transmitting data alongside the pilots, and an intuitive iterative data-aided scheme that reduces this component of interference is also proposed. Approximate expressions for the uplink SINR are provided for the iterative data-aided method as well. In addition, we show that a hybrid system with users utilizing both time-multiplexed and superimposed pilots is superior to an optimally designed system that employs only time-multiplexed pilots, even when the non-iterative channel estimate is used to build the detector and precoder. We also describe a simple approach to implement this hybrid system by minimizing the overall inter and intra-cell interference. Numerical simulations demonstrating the performance of the proposed channel estimation schemes and the superiority of the hybrid system are also provided.

  10. Uniform Exponential Growth in Algebras /

    OpenAIRE

    Briggs, Christopher Alan

    2013-01-01

    We consider uniform exponential growth in algebras. We give conditions for the uniform exponential growth of descending-filtered algebras and prove that an N-graded algebra has uniform exponential growth if it has exponential growth. We use this to prove that Golod- Shafarevich algebras and group algebras of Golod- Shafarevich groups have uniform exponential growth. We prove that the twisted Laurent extension of a free commutative polynomial algebra with respect to an endomorphism with some e...

  11. Estimating exponential scheduling preferences

    DEFF Research Database (Denmark)

    Hjorth, Katrine; Börjesson, Maria; Engelson, Leonid

    time by maximising expected total utility over the day, their departure times are conditional on rates of utility derived at these locations. For forecasting and economic evaluation of planning alternatives, it is desirable to have simple forms of utility rates with few parameters. Several forms...... the travel time is random, Noland and Small (1995) suggested using expected utility theory to derive the reduced form of expected travel time cost that includes the cost of TTV. For the α-β-γ formulation of scheduling preferences and exponential or uniform distribution of travel time, Noland and Small (1995....... The purpose of this paper is to explore how well these scheduling preferences explain behaviour, compared to other possible scheduling models, and whether empirical estimation of the more complex exponential scheduling preferences is feasible. We use data from a stated preference survey conducted among car...

  12. Estimating exponential scheduling preferences

    DEFF Research Database (Denmark)

    Hjorth, Katrine; Börjesson, Maria; Engelson, Leonid

    time by maximising expected total utility over the day, their departure times are conditional on rates of utility derived at these locations. For forecasting and economic evaluation of planning alternatives, it is desirable to have simple forms of utility rates with few parameters. Several forms...... the travel time is random, Noland and Small (1995) suggested using expected utility theory to derive the reduced form of expected travel time cost that includes the cost of TTV. For the α-β-γ formulation of scheduling preferences and exponential or uniform distribution of travel time, Noland and Small (1995....... The purpose of this paper is to explore how well these scheduling preferences explain behaviour, compared to other possible scheduling models, and whether empirical estimation of the more complex exponential scheduling preferences is feasible. We use data from a stated preference survey conducted among car...

  13. Exponential random graph models

    CERN Document Server

    Fronczak, Agata

    2012-01-01

    Nowadays, exponential random graphs (ERGs) are among the most widely-studied network models. Different analytical and numerical techniques for ERG have been developed that resulted in the well-established theory with true predictive power. An excellent basic discussion of exponential random graphs addressed to social science students and researchers is given in [Anderson et al., 1999][Robins et al., 2007]. This essay is intentionally designed to be more theoretical in comparison with the well-known primers just mentioned. Given the interdisciplinary character of the new emerging science of complex networks, the essay aims to give a contribution upon which network scientists and practitioners, who represent different research areas, could build a common area of understanding.

  14. Possibilistic Exponential Fuzzy Clustering

    Institute of Scientific and Technical Information of China (English)

    Kiatichai Treerattanapitak; Chuleerat Jaruskulchai

    2013-01-01

    Generally,abnormal points (noise and outliers) cause cluster analysis to produce low accuracy especially in fuzzy clustering.These data not only stay in clusters but also deviate the centroids from their true positions.Traditional fuzzy clustering like Fuzzy C-Means (FCM) always assigns data to all clusters which is not reasonable in some circumstances.By reformulating objective function in exponential equation,the algorithm aggressively selects data into the clusters.However noisy data and outliers cannot be properly handled by clustering process therefore they are forced to be included in a cluster because of a general probabilistic constraint that the sum of the membership degrees across all clusters is one.In order to improve this weakness,possibilistic approach relaxes this condition to improve membership assignment.Nevertheless,possibilistic clustering algorithms generally suffer from coincident clusters because their membership equations ignore the distance to other clusters.Although there are some possibilistic clustering approaches that do not generate coincident clusters,most of them require the right combination of multiple parameters for the algorithms to work.In this paper,we theoretically study Possibilistic Exponential Fuzzy Clustering (PXFCM) that integrates possibilistic approach with exponential fuzzy clustering.PXFCM has only one parameter and not only partitions the data but also filters noisy data or detects them as outliers.The comprehensive experiments show that PXFCM produces high accuracy in both clustering results and outlier detection without generating coincident problems.

  15. Physiological responses and perceived exertion during cycling with superimposed electromyostimulation.

    Science.gov (United States)

    Wahl, Patrick; Schaerk, Jonas; Achtzehn, Silvia; Kleinöder, Heinz; Bloch, Wilhelm; Mester, Joachim

    2012-09-01

    The goal of the study was to evaluate and to quantify the effects of local electromyostimulation (EMS) during cycling on the cardiorespiratory system, muscle metabolism, and perceived exertion compared with cycling with no EMS. Ten healthy men (age: 24.6 ± 3.2 years, V[Combining Dot Above]O2max: 54.1 ± 6.0 ml·min·kg) performed 3 incremental cycle ergometer step tests, 1 without and 2 with EMS (30 and 85 Hz) until volitional exhaustion. Lactate values and respiratory exchange ratio were significantly higher at intensities ≥75% peak power output (PPO) when EMS was applied. Bicarbonate concentration, base excess (BE), and Pco2 were significantly lower when EMS was applied compared with the control at intensities ≥75% PPO. Saliva cortisol levels increased because of the exercise but were unaffected by EMS. Furthermore, EMS showed greater effects on CK levels 24 hours postexercise than normal cycling did. Rating of perceived exertion was significantly higher at 100% PPO with EMS. No statistical differences were found for heart rate, pH, and Po2 between the tested cycling modes. The main findings of this study are greater metabolic changes (lactate, respiratory exchange ratio, BE, (Equation is included in full-text article.), Pco2) during cycling with EMS compared with normal cycling independent of frequency, mainly visible at higher work rates. Because metabolic alterations are important for the induction of cellular signaling cascades and adaptations, these results lead to the hypothesis that applied EMS stimulations during cycling exercise might be an enhancing stimulus for skeletal muscle metabolism and related adaptations. Thus, superimposed EMS application during cycling could be beneficial to aerobic performance enhancements in athletes and in patients who cannot perform high workloads. However, the higher demand on skeletal muscles involved must be considered.

  16. Detection of correlated fragments in a sequence of images by superimposed Fourier holograms

    Science.gov (United States)

    Pavlov, A. V.

    2016-08-01

    The problem of detecting correlated fragments in a sequence of images recorded by the superimposing holograms within the Fourier holography scheme with angular multiplication of a spatially modulated reference beam is considered. The approach to the solution of this problem is based on the properties of the variance of the image sum. It is shown that this problem can be solved by providing a constant distance between the signal and reference images when recording superimposed holograms and a partial mutual correlatedness of reference images. The detection efficiency is analysed from the point of view of estimated image data capacity, the degree of mutual correlation of reference images, and the hologram recording conditions. The results of a numerical experiment under the most complicated conditions (representation of images by realisations of homogeneous random fields) confirm the theoretical conclusions.

  17. Ordered exponential fields

    CERN Document Server

    Kuhlmann, Salma

    1999-01-01

    Model theoretic algebra has witnessed remarkable progress in the last few years. It has found profound applications in other areas of mathematics, notably in algebraic geometry and in singularity theory. Since Wilkie's results on the o-minimality of the expansion of the reals by the exponential function, and most recently even by all Pfaffian functions, the study of o-minimal expansions of the reals has become a fascinating topic. The quest for analogies between the semi-algebraic case and the o-minimal case has set a direction to this research. Through the Artin-Schreier Theory of real closed

  18. Linearly Time-Varying Channel Estimation and Symbol Detection for OFDMA Uplink Using Superimposed Training

    Directory of Open Access Journals (Sweden)

    Zhang Han

    2009-01-01

    Full Text Available We address the problem of superimposed trainings- (STs- based linearly time-varying (LTV channel estimation and symbol detection for orthogonal frequency-division multiplexing access (OFDMA systems at the uplink receiver. The LTV channel coefficients are modeled by truncated discrete Fourier bases (DFBs. By judiciously designing the superimposed pilot symbols, we estimate the LTV channel transfer functions over the whole frequency band by using a weighted average procedure, thereby providing validity for adaptive resource allocation. We also present a performance analysis of the channel estimation approach to derive a closed-form expression for the channel estimation variances. In addition, an iterative symbol detector is presented to mitigate the superimposed training effects on information sequence recovery. By the iterative mitigation procedure, the demodulator achieves a considerable gain in signal-interference ratio and exhibits a nearly indistinguishable symbol error rate (SER performance from that of frequency-division multiplexed trainings. Compared to existing frequency-division multiplexed training schemes, the proposed algorithm does not entail any additional bandwidth while with the advantage for system adaptive resource allocation.

  19. Angiosarcoma of the Eyelid With Superimposed Enterobacter Infection.

    Science.gov (United States)

    Hamill, Eric B; Agrawal, Megha; Diwan, A Hafeez; Winthrop, Kevin L; Marx, Douglas P

    2016-01-01

    Angiosarcoma is a rare, aggressive, malignant endothelial neoplasm with a variable clinical presentation. The authors describe a case of angiosarcoma involving the eyelid that was complicated by a superimposed Enterobacter infection. Following positive cultures for E. aerogenes and multiple biopsies suspicious but not definitive for angiosarcoma, a final biopsy was consistent with angiosarcoma.

  20. Exponential Cauchy Transforms

    Directory of Open Access Journals (Sweden)

    El-Bachir Yallaoui

    2012-06-01

    Full Text Available In this article, we introduce a new class of analytic functions of the unit disc $mathbf{D}$ namely the Exponential Cauchy Transforms $mathbf{{K}_{e}}$ defined by f(z= {displaystyleint_{mathbf{T}}} expleft[ Kleft( xzight ight] dmu(x where $Kleft( zight =left( 1-zight ^{-1}$ is classical Cauchy kernel and $mu(x$ is a complex Borel measures and $x$ belongs to the unit circle $mathbf{T}$ . We use Laguerre polynomials to explore the coefficients of the Taylor expansions of the kernel and Peron's formula to study the asymptotic behavior of the Taylor coefficients. Finally we investigate relationships between our new class $mathbf{{K}_{e}}$, the classical Cauchy space $mathbf{K}$ and the Hardy spaces $H^{p}$.

  1. Noise in Exponential Growth

    Science.gov (United States)

    Iyer-Biswas, Srividya; Wright, Charles; Henry, Jon; Burov, Stas; Lin, Yihan; Crosson, Sean; Dinner, Aaron; Scherer, Norbert

    2013-03-01

    The interplay between growth and division of cells is has been studied in the context of exponential growth of bacterial cells (in suitable conditions) for decades. However, bulk culture studies obscure phenomena that manifest in single cells over many generations. We introduce a unique technology combining microfluidics, single-cell imaging, and quantitative analysis. This enables us to track the growth of single Caulobacter crescentus stalked cells over hundreds of generations. The statistics that we extract indicate a size thresholding mechanism for cell division and a non-trivial scaling collapse of division time distributions at different temperatures. In this talk I shall discuss these observations and a stochastic model of growth and division that captures all our observations with no free parameters.

  2. Tools to Detect Delirium Superimposed on Dementia: A Systematic Review

    Science.gov (United States)

    Morandi, Alessandro; McCurley, Jessica; Vasilevskis, Eduard E.; Fick, Donna M.; Bellelli, Giuseppe; Lee, Patricia; Jackson, James C.; Shenkin, Susan D.; Trabucchi, Marco; Schnelle, John; Inouye, Sharon K.; Ely, Wesley E.; MacLullich, Alasdair

    2012-01-01

    Background Delirium commonly occurs in patients with dementia. Though several tools for detecting delirium exist, it is unclear which are valid in patients with delirium superimposed on dementia. Objectives Identify valid tools to diagnose delirium superimposed on dementia Design We performed a systematic review of studies of delirium tools, which explicitly included patients with dementia. Setting In-hospital patients Participants Studies were included if delirium assessment tools were validated against standard criteria, and the presence of dementia was assessed according to standard criteria that used validated instruments. Measurements PubMed, Embase, and Web of Science databases were searched for articles in English published between January 1960 and January 2012. Results Nine studies fulfilled the selection criteria. Of the total of 1569 patients, 401 had dementia, and 50 had delirium superimposed on dementia. Six delirium tools were evaluated. One studyusing the Confusion Assessment Method (CAM) with 85% patients with dementia showed a high specificity (96–100%) and moderate sensitivity (77%).Two intensive care unit studies that used the CAM for the Intensive Care Unit (CAM-ICU) ICU reported 100% sensitivity and specificity for delirium among 23 dementia patients. One study using electroencephalography reported a sensitivity of 67% and a specificity of 91% among a population with 100% prevalence of dementia. No studies examined potential effects of dementia severity or subtype upon diagnostic accuracy. Conclusions The evidence base on tools for detection of delirium superimposed on dementia is limited, although some existing tools show promise. Further studies of existing or refined tools with larger samples and more detailed characterization of dementia are now required to address the identification of delirium superimposed on dementia. PMID:23039270

  3. Test Exponential Pile

    Science.gov (United States)

    Fermi, Enrico

    The Patent contains an extremely detailed description of an atomic pile employing natural uranium as fissile material and graphite as moderator. It starts with the discussion of the theory of the intervening phenomena, in particular the evaluation of the reproduction or multiplication factor, K, that is the ratio of the number of fast neutrons produced in one generation by the fissions to the original number of fast neutrons, in a system of infinite size. The possibility of having a self-maintaining chain reaction in a system of finite size depends both on the facts that K is greater than unity and the overall size of the system is sufficiently large to minimize the percentage of neutrons escaping from the system. After the description of a possible realization of such a pile (with many detailed drawings), the various kinds of neutron losses in a pile are depicted. Particularly relevant is the reported "invention" of the exponential experiment: since theoretical calculations can determine whether or not a chain reaction will occur in a give system, but can be invalidated by uncertainties in the parameters of the problem, an experimental test of the pile is proposed, aimed at ascertaining if the pile under construction would be divergent (i.e. with a neutron multiplication factor K greater than 1) by making measurements on a smaller pile. The idea is to measure, by a detector containing an indium foil, the exponential decrease of the neutron density along the length of a column of uranium-graphite lattice, where a neutron source is placed near its base. Such an exponential decrease is greater or less than that expected due to leakage, according to whether the K factor is less or greater than 1, so that this experiment is able to test the criticality of the pile, its accuracy increasing with the size of the column. In order to perform this measure a mathematical description of the effect of neutron production, diffusion, and absorption on the neutron density in the

  4. On exponentiable soft topological spaces

    Directory of Open Access Journals (Sweden)

    Ghasem Mirhosseinkhani

    2016-11-01

    Full Text Available An object $X$ of a category $mathbf{C}$ with finite limits is called exponentiable if the functor $-times X:mathbf{C}rightarrow mathbf{C}$ has a right adjoint. There are many characterizations of the exponentiable  spaces in the category $mathbf{Top}$ of topological spaces. Here, we study the exponentiable objects in the category $mathbf{STop}$ of soft topological spaces which is a generalization of the category  $mathbf{Top}$. We investigate  the exponentiability problem and give a characterization of exponentiable soft spaces. Also wegive the definition of exponential topology on the lattice of soft open sets of a soft space and present some characterizations of it.

  5. Shear flow analyses for polymer melt extruding under superimposed vibration

    Institute of Scientific and Technical Information of China (English)

    LIU Yue-jun; FAN Shu-hong; SHI Pu

    2005-01-01

    The introduction of a vibration force field has a profound influence on the polymer formation process.However, its formation mechanism has not been explored until now. With the application of experimental equipment designed by the authors named "Constant Velocity Type Dynamic Rheometer of Capillary" or (CVDRC),we were able to analyze in detail the whole extrusion process of a polymer melt. We did this after superimposing a sine vibration of small amplitude parallel to the extruding direction of the polymer melt. Then, we created a calculation model to determine the shear stress at the wall of the capillary using a superimposed vibration. We also determined the calculation steps needed to establish the afore-mentioned shear stress. Through measurement and analysis, the instantaneous entry pressure of the capillary, the pressure gradient, and the shear stress of the polymer melt within the capillary under vibration force field can be calculated.

  6. Artistic creation as stimulated by superimposed versus separated visual images.

    Science.gov (United States)

    Sobel, R S; Rothenberg, A

    1980-11-01

    An experiment was performed to examine the role of homospatial thinking in visual art. Each of 43 university-level art students produced three drawing stimulated by pairs of slides. Subjects were randomly assigned to view the pairs either superimposed on one another or separated on the screen. Drawings were independently judged by two internationally noted artists. As predicted, drawings containing an element from each component image intermingled were higher in creative potential when stimulated by the superimposed presentation; however, when sketches from either condition did not clearly contain images from both slides, the separated image presentation yielded the more creative result. Although results favor the hypothesis in part, the overall ambiguity of the data illustrates some of the difficulties in studying creative thought processes under experimental conditions.

  7. One-DOF Superimposed Rigid Origami with Multiple States

    OpenAIRE

    Xiang Liu; Gattas, Joseph M.; Yan Chen

    2016-01-01

    Origami-inspired engineering design is increasingly used in the development of self-folding structures. The majority of existing self-folding structures either use a bespoke crease pattern to form a single structure, or a universal crease pattern capable of forming numerous structures with multiple folding steps. This paper presents a new approach whereby multiple distinct, rigid-foldable crease patterns are superimposed in the same sheet such that kinematic independence and 1-DOF mobility of...

  8. Recrystallization microstructure modelling from superimposed deformed microstructure on microstructure model

    Indian Academy of Sciences (India)

    Prantik Mukhopadhyay

    2009-08-01

    The recovered cold rolled microstructure obtained from orientation image microstructure of Al–4%Mg–0.5%Mn alloy (AA5182 alloy) was superimposed on the grid of cellular automata based microstructure model. The Taylor factors of deformed/cold rolled orientations were considered as the driving force for recrystallization. The local development of recrystallized microstructure and texture were simulated with orientation dependent grain boundary mobility and compared with the experimental results.

  9. Expectation Propagation for Exponential Families

    OpenAIRE

    Seeger, Matthias

    2005-01-01

    This is a tutorial describing the Expectation Propagation (EP) algorithm for a general exponential family. Our focus is on simplicity of exposition. Although the overhead of translating a specific model into its exponential family representation can be considerable, many apparent complications of EP can simply be sidestepped by working in this canonical representation.

  10. Multivariate Matrix-Exponential Distributions

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    2010-01-01

    -exponential distributions. We prove a characterization that states that a distribution is an MVME distribution if and only if all non-negative, non-null linear combinations of the coordinates have a univariate matrix-exponential distribution. This theorem is analog to a well-known characterization theorem...

  11. Multi-exponentially Photoelectric Response of Bacteriorhodopsin

    Institute of Scientific and Technical Information of China (English)

    姚保利; 徐大纶; 侯洵; 胡坤生; 王敖金

    2001-01-01

    A thin oriented bacteriorhodopsin (bR) film is deposited on a stainless steel slide by use of the electrophoretic sedimentation method. A junction is made with electrolyte gels having a counterelectrode to construct a bRbased photoelectric detector. The photoelectric response signal to a 10ns laser pulse is measured. A theory on the photoelectric kinetics of bR is developed based on the concept of the charge displacement current and the bR photocycle rate equations. Comparison between the theoretical and experimental results proves that the bR photoelectric response to a short laser pulse is a multi-exponential process. The decay time constants and amplitudes of each exponential component are obtained by data fitting.

  12. Is Radioactive Decay Really Exponential?

    CERN Document Server

    Aston, Philip J

    2012-01-01

    Radioactive decay of an unstable isotope is widely believed to be exponential. This view is supported by experiments on rapidly decaying isotopes but is more difficult to verify for slowly decaying isotopes. The decay of 14C can be calibrated over a period of 12,550 years by comparing radiocarbon dates with dates obtained from dendrochronology. It is well known that this approach shows that radiocarbon dates of over 3,000 years are in error, which is generally attributed to past variation in atmospheric levels of 14C. We note that predicted atmospheric variation (assuming exponential decay) does not agree with results from modelling, and that theoretical quantum mechanics does not predict exact exponential decay. We give mathematical arguments that non-exponential decay should be expected for slowly decaying isotopes and explore the consequences of non-exponential decay. We propose an experimental test of this prediction of non-exponential decay for 14C. If confirmed, a foundation stone of current dating meth...

  13. Ballistic annihilation with superimposed diffusion in one dimension.

    Science.gov (United States)

    Biswas, Soham; Larralde, Hernán; Leyvraz, Francois

    2016-02-01

    We consider a one-dimensional system with particles having either positive or negative velocity, and these particles annihilate on contact. Diffusion is superimposed on the ballistic motion of the particle. The annihilation may represent a reaction in which the two particles yield an inert species. This model has been the subject of previous work, in which it was shown that the particle concentration decays faster than either the purely ballistic or the purely diffusive case. We report on previously unnoticed behavior for large times when only one of the two species remains, and we also unravel the underlying fractal structure present in the system. We also consider in detail the case in which the initial concentration of right-going particles is 1/2+ɛ, with ɛ≠0. It is shown that remarkably rich behavior arises, in which two crossover times are observed as ɛ→0.

  14. One-DOF Superimposed Rigid Origami with Multiple States

    Science.gov (United States)

    Liu, Xiang; Gattas, Joseph M.; Chen, Yan

    2016-11-01

    Origami-inspired engineering design is increasingly used in the development of self-folding structures. The majority of existing self-folding structures either use a bespoke crease pattern to form a single structure, or a universal crease pattern capable of forming numerous structures with multiple folding steps. This paper presents a new approach whereby multiple distinct, rigid-foldable crease patterns are superimposed in the same sheet such that kinematic independence and 1-DOF mobility of each individual pattern is preserved. This is enabled by the cross-crease vertex, a special configuration consisting of two pairs of collinear crease lines, which is proven here by means of a kinematic analysis to contain two independent 1-DOF rigid-foldable states. This enables many new origami-inspired engineering design possibilities, with two explored in depth: the compact folding of non-flat-foldable structures and sequent folding origami that can transform between multiple states without unfolding.

  15. Universality in stochastic exponential growth.

    Science.gov (United States)

    Iyer-Biswas, Srividya; Crooks, Gavin E; Scherer, Norbert F; Dinner, Aaron R

    2014-07-11

    Recent imaging data for single bacterial cells reveal that their mean sizes grow exponentially in time and that their size distributions collapse to a single curve when rescaled by their means. An analogous result holds for the division-time distributions. A model is needed to delineate the minimal requirements for these scaling behaviors. We formulate a microscopic theory of stochastic exponential growth as a Master Equation that accounts for these observations, in contrast to existing quantitative models of stochastic exponential growth (e.g., the Black-Scholes equation or geometric Brownian motion). Our model, the stochastic Hinshelwood cycle (SHC), is an autocatalytic reaction cycle in which each molecular species catalyzes the production of the next. By finding exact analytical solutions to the SHC and the corresponding first passage time problem, we uncover universal signatures of fluctuations in exponential growth and division. The model makes minimal assumptions, and we describe how more complex reaction networks can reduce to such a cycle. We thus expect similar scalings to be discovered in stochastic processes resulting in exponential growth that appear in diverse contexts such as cosmology, finance, technology, and population growth.

  16. Electronically reconfigurable superimposed waveguide long-period gratings

    Science.gov (United States)

    Kulishov, Mykola; Daxhelet, Xavier; Gaidi, Mounir; Chaker, Mohamed

    2002-08-01

    The perturbation to the refractive index induced by a periodic electric field from two systems of interdigitated electrodes with the electrode-finger period l is analyzed for a waveguide with an electro-optically (EO) active core-cladding. It is shown that the electric field induces two superimposed transmissive refractive-index gratings with different symmetries of their cross-section distributions. One of these gratings has a constant component of an EO-induced refractive index along with its variable component with periodicity l, whereas the second grating possesses only a variable component with periodicity 2l. With the proper waveguide design, the gratings provide interaction between a guided fundamental core mode and two guided cladding modes. Through the externally applied electric potential, these gratings can be independently switched ON and OFF, or they can be activated simultaneously with electronically controlled weighting factors. Coupling coefficients of both gratings are analyzed in terms of their dependence on the electrode duty ratio and dielectric permittivities of the core and cladding. The coupled-wave equations for the superimposed gratings are written and solved. The spectral characteristics are investigated by numerical simulation. It is found that the spectral characteristics are described by a dual-dip transmission spectrum with individual electronic control of the dip depths and positions. Within the concept, a new external potential application scheme is described in which the symmetry of the cross-sectional distribution of the refractive index provides coupling only between the core mode and the cladding modes, preventing interaction of the cladding modes with each another. This simple concept opens opportunities for developing a number of tunable devices for integrated optics by use of the proposed design as a building block.

  17. Exponential Expansion in Evolutionary Economics

    DEFF Research Database (Denmark)

    Frederiksen, Peter; Jagtfelt, Tue

    2013-01-01

    concepts are described in detail. Taken together it provides the rudimentary aspects of an economic system within an analytical perspective. It is argued that the main dynamic processes of the evolutionary perspective can be reduced to these four concepts. The model and concepts are evaluated in the light...... of Thomas Kuhn’s notion of scientific paradigms and criteria for a good theory (1977, 1996). The paper thus aims to augment and assimilate the fragmented and scattered body of concepts presently residing within the field of evolutionary economics, by presenting an intuitive framework, applicable within...... to this problem is proposed in the form of a model of exponential expansion. The model outlines the overall structure and function of the economy as exponential expansion. The pictographic model describes four axiomatic concepts and their exponential nature. The interactive, directional, emerging and expanding...

  18. Phenomenology of stochastic exponential growth

    Science.gov (United States)

    Pirjol, Dan; Jafarpour, Farshid; Iyer-Biswas, Srividya

    2017-06-01

    Stochastic exponential growth is observed in a variety of contexts, including molecular autocatalysis, nuclear fission, population growth, inflation of the universe, viral social media posts, and financial markets. Yet literature on modeling the phenomenology of these stochastic dynamics has predominantly focused on one model, geometric Brownian motion (GBM), which can be described as the solution of a Langevin equation with linear drift and linear multiplicative noise. Using recent experimental results on stochastic exponential growth of individual bacterial cell sizes, we motivate the need for a more general class of phenomenological models of stochastic exponential growth, which are consistent with the observation that the mean-rescaled distributions are approximately stationary at long times. We show that this behavior is not consistent with GBM, instead it is consistent with power-law multiplicative noise with positive fractional powers. Therefore, we consider this general class of phenomenological models for stochastic exponential growth, provide analytical solutions, and identify the important dimensionless combination of model parameters, which determines the shape of the mean-rescaled distribution. We also provide a prescription for robustly inferring model parameters from experimentally observed stochastic growth trajectories.

  19. Bilateral matrix-exponential distributions

    DEFF Research Database (Denmark)

    Bladt, Mogens; Esparza, Luz Judith R; Nielsen, Bo Friis

    2012-01-01

    In this article we define the classes of bilateral and multivariate bilateral matrix-exponential distributions. These distributions have support on the entire real space and have rational moment-generating functions. These distributions extend the class of bilateral phasetype distributions of [1]...

  20. Exponential convergence rate in entropy

    Institute of Scientific and Technical Information of China (English)

    Mu-Fa Chen

    2007-01-01

    The exponential convergence rate in entropy is studied for symmetric forms, with a specia! attention to the Markov chain with a state space having two points only. Some upper and lower bounds of the rate are obtained and five examples with precise or qualitatively exact estimates are presented.

  1. Linear or Exponential Number Lines

    Science.gov (United States)

    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,…

  2. On the role of exponential splines in image interpolation.

    Science.gov (United States)

    Kirshner, Hagai; Porat, Moshe

    2009-10-01

    A Sobolev reproducing-kernel Hilbert space approach to image interpolation is introduced. The underlying kernels are exponential functions and are related to stochastic autoregressive image modeling. The corresponding image interpolants can be implemented effectively using compactly-supported exponential B-splines. A tight l(2) upper-bound on the interpolation error is then derived, suggesting that the proposed exponential functions are optimal in this regard. Experimental results indicate that the proposed interpolation approach with properly-tuned, signal-dependent weights outperforms currently available polynomial B-spline models of comparable order. Furthermore, a unified approach to image interpolation by ideal and nonideal sampling procedures is derived, suggesting that the proposed exponential kernels may have a significant role in image modeling as well. Our conclusion is that the proposed Sobolev-based approach could be instrumental and a preferred alternative in many interpolation tasks.

  3. Nursing care for people with delirium superimposed on dementia.

    Science.gov (United States)

    Pryor, Claire; Clarke, Amanda

    2017-03-31

    Nursing and healthcare is changing in response to an ageing population. There is a renewed need for holistic nursing to provide clinically competent, appropriate and timely care for patients who may present with inextricably linked mental and physical health requirements. This article explores the dichotomy in healthcare provision for 'physical' and 'mental' health, and the unique role nurses have when caring for people with delirium superimposed on dementia (DSD). Delirium is prevalent in older people and recognised as 'acute brain failure'. As an acute change in cognition, it presents a unique challenge when occurring in a person with dementia and poses a significant risk of mortality. In this article, dementia is contrasted with delirium and subtypes of delirium presentation are discussed. Nurses can recognise DSD through history gathering, implementation of appropriate care and effective communication with families and the multidisciplinary team. A simple mnemonic called PINCH ME (Pain, INfection, Constipation, deHydration, Medication, Environment) can help identify potential underlying causes of DSD and considerations for care planning. The mnemonic can easily be adapted to different clinical settings and a fictitious scenario is presented to show its application in practice.

  4. Limit laws for exponential families

    OpenAIRE

    Balkema, August A.; Klüppelberg, Claudia; Resnick, Sidney I.

    1999-01-01

    For a real random variable [math] with distribution function [math] , define ¶ [math] ¶ The distribution [math] generates a natural exponential family of distribution functions [math] , where ¶ [math] ¶ We study the asymptotic behaviour of the distribution functions [math] as [math] increases to [math] . If [math] then [math] pointwise on [math] . It may still be possible to obtain a non-degenerate weak limit law [math] by choosing suitable scaling and centring constants [math] an...

  5. Limit laws for exponential families

    OpenAIRE

    Balkema, August A.; Klüppelberg, Claudia; Resnick, Sidney I.

    1999-01-01

    For a real random variable [math] with distribution function [math] , define ¶ [math] ¶ The distribution [math] generates a natural exponential family of distribution functions [math] , where ¶ [math] ¶ We study the asymptotic behaviour of the distribution functions [math] as [math] increases to [math] . If [math] then [math] pointwise on [math] . It may still be possible to obtain a non-degenerate weak limit law [math] by choosing suitable scaling and centring constants [math] an...

  6. Decomposition of Superimposed Waveforms Using the Cross Time Frequency Transform

    Science.gov (United States)

    2007-11-02

    Decomposition of Myoelectric Signals .” IEEE Engineering in Medicine and Biology. (June): pp 24-28. [5] Choi, H.I., Williams, W.J. Improved time...and De Luca, C. J. (1982). “A Procedure for Decomposing the Myoelectric Signal into its Constituent Action Potentials. Part I. Technique, Theory...throughout a muscle contraction. This paper addresses a specific aspect of the identification process: the decomposition of the compound signal

  7. Risk Factors of Superimposed Preeclampsia in Women with Essential Chronic Hypertension Treated before Pregnancy

    OpenAIRE

    2013-01-01

    OBJECTIVE: To determine risk factors of superimposed preeclampsia in women with essential chronic hypertension receiving antihypertensive therapy prior to conception. METHODS: A retrospective study of 211 patients that analyzed risk factors of superimposed preeclampsia at first prenatal visit. Variables with a p

  8. 16 CFR 300.27 - Wool products containing superimposed or added fibers.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Wool products containing superimposed or added fibers. 300.27 Section 300.27 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF CONGRESS RULES AND REGULATIONS UNDER THE WOOL PRODUCTS LABELING ACT OF 1939 Labeling § 300.27 Wool products containing superimposed...

  9. Angiogenic factors in superimposed preeclampsia: a longitudinal study of women with chronic hypertension during pregnancy.

    Science.gov (United States)

    Perni, Uma; Sison, Cristina; Sharma, Vijay; Helseth, Geri; Hawfield, Amret; Suthanthiran, Manikkam; August, Phyllis

    2012-03-01

    Imbalances in circulating angiogenic factors contribute to the pathogenesis of preeclampsia. To characterize levels of angiogenic factors in pregnant women with chronic hypertension, we prospectively followed 109 women and measured soluble fms-like tyrosine kinase 1 (sFlt1), soluble endoglin, and placental growth factor at 12, 20, 28, and 36 weeks' gestation and postpartum. Superimposed preeclampsia developed in 37 (34%) and was early onset (hypertension. We conclude that alterations in angiogenic factors are detectable before and at the time of clinical diagnosis of early onset superimposed preeclampsia, whereas alterations were observed only at the time of diagnosis in women with late-onset superimposed preeclampsia. Longitudinal measurements of angiogenic factors may help anticipate early onset superimposed preeclampsia and facilitate diagnosis of superimposed preeclampsia in women with chronic hypertension.

  10. Enhancing the performance of exponentially weighted moving average charts: discussion

    NARCIS (Netherlands)

    Abbas, N.; Riaz, M.; Does, R.J.M.M.

    2015-01-01

    Abbas et al. (Abbas N, Riaz M, Does RJMM. Enhancing the performance of EWMA charts. Quality and Reliability Engineering International 2011; 27(6):821-833) proposed the use of signaling schemes with exponentially weighted moving average charts (named as 2/2 and modified − 2/3 schemes) for their impro

  11. Cosmological evolution in exponential gravity

    Energy Technology Data Exchange (ETDEWEB)

    Bamba, Kazuharu; Geng, Chao-Qiang; Lee, Chung-Chi, E-mail: bamba@phys.nthu.edu.tw, E-mail: geng@phys.nthu.edu.tw, E-mail: g9522545@oz.nthu.edu.tw [Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)

    2010-08-01

    We explore the cosmological evolution in the exponential gravity f(R) = R+c{sub 1}(1−e{sup −c{sub 2}R}) (c{sub 1,2} = constant). We summarize various viability conditions and explicitly demonstrate that the late-time cosmic acceleration following the matter-dominated stage can be realized. We also study the equation of state for dark energy and confirm that the crossing of the phantom divide from the phantom phase to the non-phantom (quintessence) one can occur. Furthermore, we illustrate that the cosmological horizon entropy globally increases with time.

  12. Cosmological evolution in exponential gravity

    CERN Document Server

    Bamba, Kazuharu; Lee, Chung-Chi

    2010-01-01

    We explore the cosmological evolution in the exponential gravity $f(R)=R +c_1 \\left(1-e^{- c_2 R} \\right)$ ($c_{1, 2} = \\mathrm{constant}$). We summarize various viability conditions and explicitly demonstrate that the late-time cosmic acceleration following the matter-dominated stage can be realized. We also study the equation of state for dark energy and confirm that the crossing of the phantom divide from the phantom phase to the non-phantom (quintessence) one can occur. Furthermore, we illustrate that the cosmological horizon entropy globally increases with time.

  13. On uniform exponential growth for solvable groups

    OpenAIRE

    Breuillard, Emmanuel

    2006-01-01

    Using a theorem of J. Groves we give a ping-pong proof of Osin's uniform exponential growth for solvable groups. We discuss slow exponential growth and show that this phenomenon disappears as one passes to a finite index subgroup.

  14. Teaching about Exponential Growth in Social Studies.

    Science.gov (United States)

    Allen, Rodney F.; LaHart, David E.

    1984-01-01

    Characteristics of exponential growth which should be taught in social studies classes are listed, and learning activities dealing with exponential growth which can be used in secondary social studies classes are provided. (RM)

  15. Notes on the Stochastic Exponential and Logarithm

    OpenAIRE

    Larsson, Martin; Ruf, Johannes

    2017-01-01

    Stochastic exponentials are defined for semimartingales on stochastic intervals, and stochastic logarithms are defined for nonnegative semimartingales, up to the first time the semimartingale hits zero continuously. In the case of (nonnegative) local supermartingales, these two stochastic transformations are inverse to each other. The reciprocal of a stochastic exponential is again a stochastic exponential on a stochastic interval.

  16. MECO In An Exponential Metric

    CERN Document Server

    Robertson, Stanley L

    2016-01-01

    Magnetic Eternally Collapsing Objects (MECO) have been proposed as the central engines of galactic black hole candidates (GBHC) and supermassive active galactic nuclei (AGN). Previous work has shown that their luminosities and spectral and timing characteristics are in good agreement with observations. These features and the formation of jets are generated primarily by the interactions of accretion disks with an intrinsically magnetic central MECO. The interaction of accretion disks with the anchored magnetic fields of the central objects permits a unified description of properties for GBHC, AGN, neutron stars in low mass x-ray binaries and dwarf novae systems. The previously published MECO models have been based on a quasistatic Schwarzschild metric of General Relativity; however, the only essential feature of this metric is its ability to produce extreme gravitational redshifts. For reasons discussed in this article, an alternative development based on a quasistatic exponential metric is considered here.

  17. Observational Constraints on Exponential Gravity

    CERN Document Server

    Yang, Louis; Luo, Ling-Wei; Geng, Chao-Qiang

    2010-01-01

    We study the observational constraints on the exponential gravity model of f(R)=-beta*Rs(1-e^(-R/Rs)). We use the latest observational data including Supernova Cosmology Project (SCP) Union2 compilation, Two-Degree Field Galaxy Redshift Survey (2dFGRS), Sloan Digital Sky Survey Data Release 7 (SDSS DR7) and Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP7) in our analysis. From these observations, we obtain a lower bound on the model parameter beta at 1.27 (95% CL) but no appreciable upper bound. The constraint on the present matter density parameter is 0.245< Omega_m^0<0.311 (95% CL). We also find out the best-fit value of model parameters on several cases.

  18. UCB Algorithm for Exponential Distributions

    CERN Document Server

    Jouini, Wassim

    2012-01-01

    We introduce in this paper a new algorithm for Multi-Armed Bandit (MAB) problems. A machine learning paradigm popular within Cognitive Network related topics (e.g., Spectrum Sensing and Allocation). We focus on the case where the rewards are exponentially distributed, which is common when dealing with Rayleigh fading channels. This strategy, named Multiplicative Upper Confidence Bound (MUCB), associates a utility index to every available arm, and then selects the arm with the highest index. For every arm, the associated index is equal to the product of a multiplicative factor by the sample mean of the rewards collected by this arm. We show that the MUCB policy has a low complexity and is order optimal.

  19. PARAMETER ESTIMATION OF EXPONENTIAL DISTRIBUTION

    Institute of Scientific and Technical Information of China (English)

    XU Haiyan; FEI Heliang

    2005-01-01

    Because of the importance of grouped data, many scholars have been devoted to the study of this kind of data. But, few documents have been concerned with the threshold parameter. In this paper, we assume that the threshold parameter is smaller than the first observing point. Then, on the basis of the two-parameter exponential distribution, the maximum likelihood estimations of both parameters are given, the sufficient and necessary conditions for their existence and uniqueness are argued, and the asymptotic properties of the estimations are also presented, according to which approximate confidence intervals of the parameters are derived. At the same time, the estimation of the parameters is generalized, and some methods are introduced to get explicit expressions of these generalized estimations. Also, a special case where the first failure time of the units is observed is considered.

  20. Monitoring of vacuum assisted resin transfer moulding (VARTM) process with superimposed Fiber-Bragg-gratings

    Science.gov (United States)

    Triollet, S.; Robert, L.; Marin, E.; Ouerdane, Y.

    2011-05-01

    We report the instrumentation of a manufacturing composite process using an optical fiber sensor based on Bragg gratings. The sensor is made of superimposed Long Period (LPG) and short period (FBG) Bragg gratings written in the same fiber section. The monitoring of the process needs simultaneous measurements of temperature and strain. It has been shown that these two solicitations can be determined and discriminated with a superimposed FBG/LPG sensor [1]. In this paper we present the device based on the dual superimposed gratings. The sensor is embedded in a composite specimen manufactured by Vacuum Assisted Resin Transfer Moulding (VARTM) process for monitoring purpose.

  1. Configurable Transmitter and Systolic Channel Estimator Architectures for Data-Dependent Superimposed Training Communications Systems

    Directory of Open Access Journals (Sweden)

    E. Romero-Aguirre

    2012-01-01

    Full Text Available In this paper, a configurable superimposed training (ST/data-dependent ST (DDST transmitter and architecture based on array processors (APs for DDST channel estimation are presented. Both architectures, designed under full-hardware paradigm, were described using Verilog HDL, targeted in Xilinx Virtex-5 and they were compared with existent approaches. The synthesis results showed a FPGA slice consumption of 1% for the transmitter and 3% for the estimator with 160 and 115 MHz operating frequencies, respectively. The signal-to-quantization-noise ratio (SQNR performance of the transmitter is about 82 dB to support 4/16/64-QAM modulation. A Monte Carlo simulation demonstrates that the mean square error (MSE of the channel estimator implemented in hardware is practically the same as the one obtained with the floating-point golden model. The high performance and reduced hardware of the proposed architectures lead to the conclusion that the DDST concept can be applied in current communications standards.

  2. Research on a Composite Power-Superimposed Ultrasonic Vibrator for Wire Drawing

    Directory of Open Access Journals (Sweden)

    Shen Liu

    2016-01-01

    Full Text Available Vibration power and amplitude are essential factors in ultrasonic drawing processes, especially for difficult-to-draw materials like titanium and its alloys. This paper presents a new composite power-superimposed ultrasonic vibrator for wire drawing which was driven by three separate ultrasonic transducers. The transducers were uniformly distributed around the circular cross section of the vibrator, with their axes along the radial direction and pointing to the center. The vibrator can concentrate the vibrational energy of multiple transducers and transform the radial vibration into a longitudinal vibrator because of the Poisson effect and therefore output larger vibration power and amplitude. In the paper, the four-terminal network method was used to establish the vibration equations of the vibrator. The FE model was established in ANSYS to investigate its characteristics under various excitation conditions. A prototype was manufactured and measurements were performed to verify the validation of FEA results. The results matched well with the theoretical results. It was found that the composite vibrator achieved an amplitude of about 40 μm when driven by square wave signals with 120° in phase difference, which implies a potential way of applying ultrasonic vibration to the processing of difficult-to-draw materials.

  3. Comparative Analysis of Sequence Characteristics among Different Superimposed Stages of the Chelif Basin, Algeria

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yuanfu; JIANG Zaixing; WANG Yue; BAO Dandan

    2009-01-01

    Superimposed basins were investigated with respect to tectonic evolution, sediment deposition and petroleum characteristics within a single superposition stage generally. The comparative study was seldom seen. Sequence characteristics were compared for two different superimposed stages-an expanding rifting stage and a depression-foreland transition stage-in the Chelif Basin during the Miocene in this paper. A model and mechanism for sequence evolution of superimposed basins in different dynamic situations are discussed with respect to sequence similarities and differences. The compared characters include sequence thickness, sequence boundaries and system tracts, as well as sediment deposition within sequences and sequence development patterns. Finally, some typical features of sequence development concomitant with changes of superimposed stages in the Chelif Basin are discussed.

  4. Superimposing of virtual graphics and real image based on 3D CAD information

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Proposes methods of transforming 3D CAD models into 2D graphics and recognizing 3D objects by features and superimposing VE built in computer onto real image taken by a CCD camera, and presents computer simulation results.

  5. Exponential Stabilization of Underactuated Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Pettersen, K.Y.

    1996-12-31

    Underactuated vehicles are vehicles with fewer independent control actuators than degrees of freedom to be controlled. Such vehicles may be used in inspection of sub-sea cables, inspection and maintenance of offshore oil drilling platforms, and similar. This doctoral thesis discusses feedback stabilization of underactuated vehicles. The main objective has been to further develop methods from stabilization of nonholonomic systems to arrive at methods that are applicable to underactuated vehicles. A nonlinear model including both dynamics and kinematics is used to describe the vehicles, which may be surface vessels, spacecraft or autonomous underwater vehicles (AUVs). It is shown that for a certain class of underactuated vehicles the stabilization problem is not solvable by linear control theory. A new stability result for a class of homogeneous time-varying systems is derived and shown to be an important tool for developing continuous periodic time-varying feedback laws that stabilize underactuated vehicles without involving cancellation of dynamics. For position and orientation control of a surface vessel without side thruster a new continuous periodic feedback law is proposed that does not cancel any dynamics, and that exponentially stabilizes the origin of the underactuated surface vessel. A further issue considered is the stabilization of the attitude of an AUV. Finally, the thesis discusses stabilization of both position and attitude of an underactuated AUV. 55 refs., 28 figs.

  6. Theory, computation, and application of exponential splines

    Science.gov (United States)

    Mccartin, B. J.

    1981-01-01

    A generalization of the semiclassical cubic spline known in the literature as the exponential spline is discussed. In actuality, the exponential spline represents a continuum of interpolants ranging from the cubic spline to the linear spline. A particular member of this family is uniquely specified by the choice of certain tension parameters. The theoretical underpinnings of the exponential spline are outlined. This development roughly parallels the existing theory for cubic splines. The primary extension lies in the ability of the exponential spline to preserve convexity and monotonicity present in the data. Next, the numerical computation of the exponential spline is discussed. A variety of numerical devices are employed to produce a stable and robust algorithm. An algorithm for the selection of tension parameters that will produce a shape preserving approximant is developed. A sequence of selected curve-fitting examples are presented which clearly demonstrate the advantages of exponential splines over cubic splines.

  7. Generalised Exponential Families and Associated Entropy Functions

    Directory of Open Access Journals (Sweden)

    Jan Naudts

    2008-07-01

    Full Text Available A generalised notion of exponential families is introduced. It is based on the variational principle, borrowed from statistical physics. It is shown that inequivalent generalised entropy functions lead to distinct generalised exponential families. The well-known result that the inequality of Cram´er and Rao becomes an equality in the case of an exponential family can be generalised. However, this requires the introduction of escort probabilities.

  8. Exponential Observers for Lotka-Volterra Systems

    Directory of Open Access Journals (Sweden)

    Dr. V. Sundarapandian

    2011-03-01

    Full Text Available This paper solves the exponential observer design problem for Lotka-Volterra systems. Explicitly, Sundarapandian’s theorem (2002 for observer design for exponential observer design is used to solve the nonlinear observer design problem for 2-species, 3-species and 4-species Lotka-Volterra systems. Numerical examples are provided to illustrate the effectiveness of the proposed exponential observer design for the Lotka-Volterra systems.

  9. On the exponentials of some structured matrices

    Energy Technology Data Exchange (ETDEWEB)

    Ramakrishna, Viswanath; Costa, F [Department of Mathematical Sciences and Center for Signals, Systems and Communications, University of Texas at Dallas, PO Box 830688, Richardson, TX 75083 (United States)

    2004-12-03

    This paper provides explicit techniques to compute the exponentials of a variety of structured 4 x 4 matrices. The procedures are fully algorithmic and can be used to find the desired exponentials in closed form. With one exception, they require no spectral information about the matrix being exponentiated. They rely on a mixture of Lie theory and one particular Clifford algebra isomorphism. These can be extended, in some cases, to higher dimensions when combined with techniques such as Givens rotations.

  10. The Matrix exponential, Dynamic Systems and Control

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    2004-01-01

    The matrix exponential can be found in various connections in analysis and control of dynamic systems. In this short note we are going to list a few examples. The matrix exponential usably pops up in connection to the sampling process, whatever it is in a deterministic or a stochastic setting...

  11. The Ronkin number of an exponential sum

    CERN Document Server

    Silipo, James

    2011-01-01

    We give an intrinsic estimate of the number of connected components of the complementary set to the amoeba of an exponential sum with real spectrum improving the result of Forsberg, Passare and Tsikh in the polynomial case and that of Ronkin in the exponential one.

  12. The Matrix exponential, Dynamic Systems and Control

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    2004-01-01

    The matrix exponential can be found in various connections in analysis and control of dynamic systems. In this short note we are going to list a few examples. The matrix exponential usably pops up in connection to the sampling process, whatever it is in a deterministic or a stochastic setting...

  13. On level-transitivity and exponential growth

    OpenAIRE

    Klimann, Ines

    2016-01-01

    We prove that if the group generated by a Mealy automaton acts level-transitively on a regular rooted tree, then the semigroup generated by the dual automaton has exponential growth, hence giving a decision procedure of exponential growth for a restricted family of automaton semigroups.

  14. q-exponentials on quantum spaces

    Energy Technology Data Exchange (ETDEWEB)

    Wachter, H. [Ludwig-Maximilians-Universitaet, Sektion Physik, Muenchen (Germany)

    2004-10-01

    We present explicit formulae for q-exponentials on quantum spaces which could be of particular importance in physics, i.e. the q-deformed Minkowski space and the q-deformed Euclidean space with two, three or four dimensions. Furthermore, these formulae can be viewed as 2-, 3- or 4-dimensional analogues of the well-known q-exponential function. (orig.)

  15. Glucose clearance in aged trained skeletal muscle during maximal insulin with superimposed exercise

    DEFF Research Database (Denmark)

    Dela, Flemming; Mikines, K J; Larsen, J J

    1999-01-01

    clamp with a final 30 min of superimposed two-legged exercise at 70% of individual maximal heart rate. With superimposed exercise, leg glucose extraction decreased (P exercise, leg......Insulin and muscle contractions are major stimuli for glucose uptake in skeletal muscle and have in young healthy people been shown to be additive. We studied the effect of superimposed exercise during a maximal insulin stimulus on glucose uptake and clearance in trained (T) (1-legged bicycle...... +/- 8, DM: 70 +/- 10 ml. min(-1). kg leg(-1)) compared with UT (H: 63 +/- 8, DM: 45 +/- 7 ml. min(-1). kg leg(-1)) but not different between groups (P > 0.05). From these results it can be concluded that, in both diabetic and healthy aged muscle, exercise adds to a maximally insulin-stimulated glucose...

  16. Observations of superimposed ice formation at melt-onset on fast ice on Kongsfjorden, Svalbard

    OpenAIRE

    Nicolaus, Marcel; Haas, Christian; Bareiss, Jörg

    2003-01-01

    Measurements of superimposed ice formation and snow properties as a function of the surface energy balance during melt-onset are presented. They were performed on Kongsfjorden, Svalbard, between late May and early June 2002. Rapid snow melt commenced and within 5 days the snow cover initially 0.23 m thick transformed completely into 0.05 m to 0.06 m of superimposed ice. Melt-onset was characterized by rapid changes in the total energy balance, which became positive throughout the whole day af...

  17. Comparing exponential and exponentiated models of drug demand in cocaine users.

    Science.gov (United States)

    Strickland, Justin C; Lile, Joshua A; Rush, Craig R; Stoops, William W

    2016-12-01

    Drug purchase tasks provide rapid and efficient measurement of drug demand. Zero values (i.e., prices with zero consumption) present a quantitative challenge when using exponential demand models that exponentiated models may resolve. We aimed to replicate and advance the utility of using an exponentiated model by demonstrating construct validity (i.e., association with real-world drug use) and generalizability across drug commodities. Participants (N = 40 cocaine-using adults) completed Cocaine, Alcohol, and Cigarette Purchase Tasks evaluating hypothetical consumption across changes in price. Exponentiated and exponential models were fit to these data using different treatments of zero consumption values, including retaining zeros or replacing them with 0.1, 0.01, or 0.001. Excellent model fits were observed with the exponentiated model. Means and precision fluctuated with different replacement values when using the exponential model but were consistent for the exponentiated model. The exponentiated model provided the strongest correlation between derived demand intensity (Q0) and self-reported free consumption in all instances (Cocaine r = .88; Alcohol r = .97; Cigarette r = .91). Cocaine demand elasticity was positively correlated with alcohol and cigarette elasticity. Exponentiated parameters were associated with real-world drug use (e.g., weekly cocaine use) whereas these correlations were less consistent for exponential parameters. Our findings show that selection of zero replacement values affects demand parameters and their association with drug-use outcomes when using the exponential model but not the exponentiated model. This work supports the adoption of the exponentiated demand model by replicating improved fit and consistency and demonstrating construct validity and generalizability. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  18. Exponentials and Laplace transforms on nonuniform time scales

    Science.gov (United States)

    Ortigueira, Manuel D.; Torres, Delfim F. M.; Trujillo, Juan J.

    2016-10-01

    We formulate a coherent approach to signals and systems theory on time scales. The two derivatives from the time-scale calculus are used, i.e., nabla (forward) and delta (backward), and the corresponding eigenfunctions, the so-called nabla and delta exponentials, computed. With these exponentials, two generalised discrete-time Laplace transforms are deduced and their properties studied. These transforms are compatible with the standard Laplace and Z transforms. They are used to study discrete-time linear systems defined by difference equations. These equations mimic the usual continuous-time equations that are uniformly approximated when the sampling interval becomes small. Impulse response and transfer function notions are introduced. This implies a unified mathematical framework that allows us to approximate the classic continuous-time case when the sampling rate is high or to obtain the standard discrete-time case, based on difference equations, when the time grid becomes uniform.

  19. An Exponential Bound for Cox Regression☆

    Science.gov (United States)

    Kosorok, M. R.

    2012-01-01

    We present an asymptotic exponential bound for the deviation of the survival function estimator of the Cox model. We show that the bound holds even when the proportional hazards assumption does not hold. PMID:23565013

  20. An Exponential Bound for Cox Regression.

    Science.gov (United States)

    Goldberg, Y; Kosorok, M R

    2012-07-01

    We present an asymptotic exponential bound for the deviation of the survival function estimator of the Cox model. We show that the bound holds even when the proportional hazards assumption does not hold.

  1. When economic growth is less than exponential

    DEFF Research Database (Denmark)

    Groth, Christian; Koch, Karl-Josef; Steger, Thomas

    2010-01-01

    This paper argues that growth theory needs a more general notion of "regularity" than that of exponential growth. We suggest that paths along which the rate of decline of the growth rate is proportional to the growth rate itself deserve attention. This opens up for considering a richer set of par......) serves as illustration that a continuum of "regular" growth processes fill the whole range between exponential growth and complete stagnation....

  2. When economic growth is less than exponential

    OpenAIRE

    Groth, Christian; Koch, Karl-Josef; Steger, Thomas M.

    2009-01-01

    This paper argues that growth theory needs a more general notion of “regularity” than that of exponential growth. We suggest that paths along which the rate of decline of the growth rate is proportional to the growth rate itself deserve attention. This opens up for considering a richer set of parameter combinations than in standard growth models. And it avoids the usual oversimplistic dichotomy of either exponential growth or stagnation. Allowing zero population growth in three ...

  3. Continued Fraction Algorithm for Matrix Exponentials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A recursive rational algorithm for matrix exponentials was obtained by making use of the generalized inverse of a matrix in this paper. On the basis of the n-th convergence of Thiele-type continued fraction expansion, a new type of the generalized inverse matrix-valued Padé approximant (GMPA) for matrix exponentials was defined and its remainder formula was proved. The results of this paper were illustrated by some examples.

  4. 16 CFR 303.23 - Textile fiber products containing superimposed or added fibers.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Textile fiber products containing... UNDER SPECIFIC ACTS OF CONGRESS RULES AND REGULATIONS UNDER THE TEXTILE FIBER PRODUCTS IDENTIFICATION ACT § 303.23 Textile fiber products containing superimposed or added fibers. Where a textile...

  5. Chronic hypertension superimposed on preeclampsia at 13 gestational weeks: a case report with review

    Institute of Scientific and Technical Information of China (English)

    ZHU Yu-chun; SUN Yu; YANG Hui-xia

    2012-01-01

    Preeclampsia is represented by hypertension and proteinuria in pregnancy.It usually occurs after 20 gestational weeks.There are few reports on preeclampsia before 20 gestational weeks.In this case,we report a patient with chronic hypertension superimposed with preeclampsia at 13 gestational weeks.

  6. A Teething Problem: Artefactual X-Ray Appearances of Odontoid Fracture due to Superimposed Incisor

    Directory of Open Access Journals (Sweden)

    Matthew Crocker

    2012-01-01

    Full Text Available We report a case of artefactual C2 fracture caused by a superimposed incisor tooth in a seven-year-old boy. CT refuted the diagnosis. Trauma clinicians should be aware of this entity to guide correct interpretation of trauma X-rays.

  7. Randomization of Symbol Repetition of Punch Cards with Superimposed Coding in Information-Search Systems.

    Science.gov (United States)

    Pirovich, L. Ya

    The article shows the effect of the irregularity of using separate symbols on search noise on punch cards with superimposed symbol coding in information-search system (IPS). A binomial law of random value distribution of repetition of each symbol is established and analyzed. A method of determining the maximum value of symbol repetition is…

  8. Late-Stage Reservoir Formation Effect and Its Dynamic Mechanisms in Complex Superimposed Basins

    Institute of Scientific and Technical Information of China (English)

    KANG Dejiang; PANG Xiongqi; KUANG Jun; LUO Xiaorong; PANG Hong; LEI Lei

    2010-01-01

    Complex superimposed basins exhibit multi-stage tectonic events and multi-stage reservoir formation; hydrocarbon reservoirs formed in the early stage have generally late-stage genesis characteristics after undergoing adjustment,reconstruction and destruction of later-stage multiple tectonic events.In this paper,this phenomenon is called the late-stage reservoir formation effect.The late-stage reservoir formation effect is a basic feature of oil and gas-forming reservoirs in complex superimposed basins,revealing not only multi-stage character,relevance and complexity of oil and gas-forming reservoirs in superimposed basins but also the importance of late-stage reservoir formation.Late-stage reservoir formation is not a basic feature of off and gas forming reservoir in superimposed basins.Multi-stage reservoir formation only characterizes one aspect of oil and gas-forming reservoir in superimposed basins and does not represent fully the complexity of oil and gas-forming reservoir in superimposed basins.We suggest using"late-stage reservoir formation effect"to replace the"late-stage reservoir formation"concept to guide the exploration of complex reservoirs in superimposed basins.Under current geologic conditions,the late-stage reservoir formation effect is represented mainly by four basic forms:phase transformation,scale reconstruction,component variation and trap adjustment.The late-stage reservoir formation effect is produced by two kinds of geologic processes:first,the off and gas retention function of various geologic thresholds(hydrocarbon expulsion threshold,hydrocarbon migration threshold,and hydrocarbon accumulating threshold)causes the actual time of oil and gas reservoir formation to be later than the time of generation of large amounts of hydrocarbon in a conventional sense,producing the late-stage reservoir formation effect; second,multiple types of tectonic events(continuously strong reconstruction,early-stage strong reconstruction,middle-stage strong

  9. Analysis of global exponential stability for a class of bi—directional associative memory networks

    Institute of Scientific and Technical Information of China (English)

    王宏霞; 何晨

    2003-01-01

    In real-time applications of bi-directional associative memory (BAM) networks.a global exponentially stable equilibrium is highly desired.The existence,uniqueness and global exponential stability for a class of BAM networks are studied in this paper,the signal function of neurons is assumed to be piece-wise linear from the engineering point of view.A very concise condition for the equilbrium of such a network being globally exponentially stable is derived.which makes the pactical design of this kind of networks an easy job.

  10. Analysis of global exponential stability for a class of bi-directional associative memory networks

    Institute of Scientific and Technical Information of China (English)

    王宏霞; 何晨

    2003-01-01

    In real-time applications of bi-directional associative memory (BAM) networks, a global exponentially stable equilibrium is highly desired. The existence, uniqueness and global exponential stability for a class of BAM networks are studied in this paper, the signal function of neurons is assumed to be piece-wise linear from the engineering point of view. A very concise condition for the equilibrium of such a network being globally exponentially stable is derived,which makes the practical design of this kind of networks an easy job.

  11. Local Exponential Methods: a domain decomposition approach to exponential time integration of PDEs

    CERN Document Server

    Bonaventura, Luca

    2015-01-01

    A local approach to the time integration of PDEs by exponential methods is proposed, motivated by theoretical estimates by A.Iserles on the decay of off-diagonal terms in the exponentials of sparse matrices. An overlapping domain decomposition technique is outlined, that allows to replace the computation of a global exponential matrix by a number of independent and easily parallelizable local problems. Advantages and potential problems of the proposed technique are discussed. Numerical experiments on simple, yet relevant model problems show that the resulting method allows to increase computational efficiency with respect to standard implementations of exponential methods.

  12. Multi-exponential inversions of nuclear magnetic resonance relaxation signal

    Institute of Scientific and Technical Information of China (English)

    WANG; Weimin(

    2001-01-01

    [1]Kenyon, W. E. , Petrophysical principles of applications of NMR logging, The Log Analyst, 1997, March-April: 21-43.[2]Timur, A., Producible porosity and permeability of sandstone investigated through nuclear magnetic resonance principles,Journal of Petroleum Technology, 1969, 21: 775-786.[3]Chakrabarty, T. , Longo, J. , A new method for mineral quantification to aid in hydrocarbon exploration and exploitation,Journal of Canadian Petroleum Technology, 1997, 36(11 ): 15-21.[4]Kleinberg, R. L. , Vinegar, H. J. , NMR properties of reservoir fluids, The Log Analyst, 1996, November-December: 20-32.[5]Wahba, G. , Practical approximate solutions to linear operator equations when the data are noisy, SIAM. J. Numer. Anal. ,1977, 14(4): 651-667.[6]Butler, J. P. , Reeds, J. A. , Dawson, S. V. , Estimating solutions of first kind integral equations with nonnegative constraints and optimal smoothing, SIAM J. Numer. Anal. , 1981, 18(3): 381-397.[7]Munn, K. , Smith, D. M., A NMR technique for the analysis of pore structure: Numerical inversion of relaxation measurements, Journal of Colloid and Interface Science, 1987,19(1): 117-126.[8]Provencher, S. W., A constrained regularization method for inverting data represented by linear algebraic or integral equations, Computer Physics Communications, 1982, 27: 213-227.[9]Bergman, D. J., Dunn, K. J., Magnetic susceptibility contrasted fixed field gradient effects on the spin-echo amplitude in a periodic porous media with diffusion, Phys. Soc., 1995, 40: 695-702.[10]Wang Weimin, The basic experiment studies of NMR logging, Well Logging Technology, 1997, 21 (6): 385-392.

  13. A kernel representation for exponential splines with global tension

    Science.gov (United States)

    Barendt, Sven; Fischer, Bernd; Modersitzki, Jan

    2009-02-01

    Interpolation is a key ingredient in many imaging routines. In this note, we present a thorough evaluation of an interpolation method based on exponential splines in tension. They are based on so-called tension parameters, which allow for a tuning of their properties. As it turns out, these interpolants have very many nice features, which are, however, not born out in the literature. We intend to close this gap. We present for the first time an analytic representation of their kernel which enables one to come up with a space and frequency domain analysis. It is shown that the exponential splines in tension, as a function of the tension parameter, bridging the gap between linear and cubic B-Spline interpolation. For example, with a certain tension parameter, one is able to suppress ringing artefacts in the interpolant. On the other hand, the analysis in the frequency domain shows that one derives a superior signal reconstruction quality as known from the cubic B-Spline interpolation, which, however, suffers from ringing artifacts. With the ability to offer a trade-off between opposing features of interpolation methods we advocate the use of the exponential spline in tension from a practical point of view and use the new kernel representation to qualify the trade-off.

  14. Exponential quadruplex priming amplification for DNA-based isothermal diagnostics.

    Science.gov (United States)

    Partskhaladze, Tamar; Taylor, Adam; Lomidze, Levan; Gvarjaladze, David; Kankia, Besik

    2015-02-01

    Polymerase chain reaction (PCR) is a method of choice for molecular diagnostics. However, PCR relies on thermal cycling, which is not compatible with the goals of point-of-care diagnostics. A simple strategy to turn PCR into an isothermal method would be to use specific primers, which upon polymerase elongation can self-dissociate from the primer-binding sites. We recently demonstrated that a monomolecular DNA quadruplex, GGGTGGGTGGGTGGG, meets these requirements, which led to the development of the linear versions of quadruplex priming amplification (QPA). Here we demonstrate exponential version of isothermal QPA, which allows an unprecedented 10(10)-fold amplification of DNA signal in less than 40 min.

  15. Demonstrating Chirality: Using a Mirror with Physical Models To Show Non-superimposability of Chiral Molecules with Their Mirror Images.

    Science.gov (United States)

    Collins, Michael J.

    2001-01-01

    Presents a remarkable demonstration on chiralty in molecules and the existence of enantiomers, also known as non-superimposable mirror images. Uses a mirror, a physical model of a molecule, and a bit of trickery involving the non-superimposable mirror image. (Author/NB)

  16. A 10-days heatwave around flowering superimposed on climate change conditions significantly affects production of 22 barley accessions

    DEFF Research Database (Denmark)

    Ingvordsen, Cathrine Heinz; Lyngkjær, Michael F.; Peltonen-Sainio, Pirjo;

    2015-01-01

    representing a worst case scenario (~RCP8.5, IPCC) at the end of the 21st century. A 10 day-heatwave of 33/22°C (day/night) was superimposed around the time of flowering on the basic climate treatments. The superimposed heatwave decreased overall grain yield in all combinations, however, vast variation...

  17. ESTIMATION ACCURACY OF EXPONENTIAL DISTRIBUTION PARAMETERS

    Directory of Open Access Journals (Sweden)

    muhammad zahid rashid

    2011-04-01

    Full Text Available The exponential distribution is commonly used to model the behavior of units that have a constant failure rate. The two-parameter exponential distribution provides a simple but nevertheless useful model for the analysis of lifetimes, especially when investigating reliability of technical equipment.This paper is concerned with estimation of parameters of the two parameter (location and scale exponential distribution. We used the least squares method (LSM, relative least squares method (RELS, ridge regression method (RR,  moment estimators (ME, modified moment estimators (MME, maximum likelihood estimators (MLE and modified maximum likelihood estimators (MMLE. We used the mean square error MSE, and total deviation TD, as measurement for the comparison between these methods. We determined the best method for estimation using different values for the parameters and different sample sizes

  18. Modeling aftershocks as a stretched exponential relaxation

    Science.gov (United States)

    Mignan, A.

    2015-11-01

    The decay rate of aftershocks has been modeled as a power law since the pioneering work of Omori in the late nineteenth century. Although other expressions have been proposed in recent decades to describe the temporal behavior of aftershocks, the number of model comparisons remains limited. After reviewing the aftershock models published from the late nineteenth century until today, I solely compare the power law, pure exponential and stretched exponential expressions defined in their simplest forms. By applying statistical methods recommended recently in applied mathematics, I show that all aftershock sequences tested in three regional earthquake catalogs (Southern and Northern California, Taiwan) and with three declustering techniques (nearest-neighbor, second-order moment, window methods) follow a stretched exponential instead of a power law. These results infer that aftershocks are due to a simple relaxation process, in accordance with most other relaxation processes observed in Nature.

  19. Unification modulo a partial theory of exponentiation

    CERN Document Server

    Kapur, Deepak; Narendran, Paliath; 10.4204/EPTCS.42.2

    2010-01-01

    Modular exponentiation is a common mathematical operation in modern cryptography. This, along with modular multiplication at the base and exponent levels (to different moduli) plays an important role in a large number of key agreement protocols. In our earlier work, we gave many decidability as well as undecidability results for multiple equational theories, involving various properties of modular exponentiation. Here, we consider a partial subtheory focussing only on exponentiation and multiplication operators. Two main results are proved. The first result is positive, namely, that the unification problem for the above theory (in which no additional property is assumed of the multiplication operators) is decidable. The second result is negative: if we assume that the two multiplication operators belong to two different abelian groups, then the unification problem becomes undecidable.

  20. ESTIMATION ACCURACY OF EXPONENTIAL DISTRIBUTION PARAMETERS

    Directory of Open Access Journals (Sweden)

    muhammad zahid rashid

    2011-04-01

    Full Text Available The exponential distribution is commonly used to model the behavior of units that have a constant failure rate. The two-parameter exponential distribution provides a simple but nevertheless useful model for the analysis of lifetimes, especially when investigating reliability of technical equipment.This paper is concerned with estimation of parameters of the two parameter (location and scale exponential distribution. We used the least squares method (LSM, relative least squares method (RELS, ridge regression method (RR,  moment estimators (ME, modified moment estimators (MME, maximum likelihood estimators (MLE and modified maximum likelihood estimators (MMLE. We used the mean square error MSE, and total deviation TD, as measurement for the comparison between these methods. We determined the best method for estimation using different values for the parameters and different sample sizes

  1. When Economic Growth is Less than Exponential

    DEFF Research Database (Denmark)

    Groth, Christian; Koch, Karl-Josef; Steger, Thomas M.

    This paper argues that growth theory needs a more general notion of "regularity" than that of exponential growth. We suggest that paths along which the rate of decline of the growth rate is proportional to the growth rate itself deserve attention. This opens up for considering a richer set...... of parameter combinations than in standard growth models. And it avoids the usual oversimplistic dichotomy of either exponential growth or stagnation. Allowing zero population growth in three different growth models (the Jones R&D-based model, a learning-by-doing model, and an embodied technical change model......) serve as illustrations that a continuum of "regular" growth processes fill the whole range between exponential growth and complete stagnation....

  2. The technological singularity and exponential medicine

    Directory of Open Access Journals (Sweden)

    Iraj Nabipour

    2016-01-01

    Full Text Available The "technological singularity" is forecasted to occur in 2045. It is a point when non-biological intelligence becomes more intelligent than humans and each generation of intelligent machines re-designs itself smarter. Beyond this point, there is a symbiosis between machines and humans. This co-existence will produce incredible impacts on medicine that its sparkles could be seen in healthcare industry and the future medicine since 2025. Ray Kurzweil, the great futurist, suggested that three revolutions in science and technology consisting genetic and molecular science, nanotechnology, and robotic (artificial intelligence provided an exponential growth rate for medicine. The "exponential medicine" is going to create more disruptive technologies in healthcare industry. The exponential medicine shifts the paradigm of medical philosophy and produces significant impacts on the healthcare system and patient-physician relationship.   

  3. Exponential Polynomial Approximation with Unrestricted Upper Density

    Institute of Scientific and Technical Information of China (English)

    Xiang Dong YANG

    2011-01-01

    We take a new approach to obtaining necessary and sufficient conditions for the incompleteness of exponential polynomials in Lp/α, where Lp/α is the weighted Banach space of complex continuous functions f defined on the real axis (R)satisfying (∫+∞/-∞|f(t)|pe-α(t)dt)1/p, 1 < p < ∞, and α(t) is a nonnegative continuous function defined on the real axis (R). In this paper, the upper density of the sequence which forms the exponential polynomials is not required to be finite. In the study of weighted polynomial approximation, consideration of the case is new.

  4. Metastability of exponentially perturbed Markov chains

    Institute of Scientific and Technical Information of China (English)

    陈大岳; 冯建峰; 钱敏平

    1996-01-01

    A family of irreducible Markov chains on a finite state space is considered as an exponential perturbation of a reducible Markov chain. This is a generalization of the Freidlin-Wentzell theory, motivated by studies of stochastic Ising models, neural network and simulated annealing. It is shown that the metastability is a universal feature for this wide class of Markov chains. The metastable states are simply those recurrent states of the reducible Markov chain. Higher level attractors, related attractive basins and their pyramidal structure are analysed. The logarithmic asymptotics of the hitting time of various sets are estimated. The hitting time over its mean converges in law to the unit exponential distribution.

  5. Exponential Operators, Dobinski Relations and Summability

    CERN Document Server

    Blasiak, P; Horzela, A; Penson, K A; Solomon, A I

    2005-01-01

    We investigate properties of exponential operators preserving the particle number using combinatorial methods developed in order to solve the boson normal ordering problem. In particular, we apply generalized Dobinski relations and methods of multivariate Bell polynomials which enable us to understand the meaning of perturbation-like expansions of exponential operators. Such expansions, obtained as formal power series, are everywhere divergent but the Pade summation method is shown to give results which very well agree with exact solutions got for simplified quantum models of the one mode bosonic systems.

  6. Exponential Data Fitting and its Applications

    CERN Document Server

    Pereyra, Victor

    2010-01-01

    Real and complex exponential data fitting is an important activity in many different areas of science and engineering, ranging from Nuclear Magnetic Resonance Spectroscopy and Lattice Quantum Chromodynamics to Electrical and Chemical Engineering, Vision and Robotics. The most commonly used norm in the approximation by linear combinations of exponentials is the l2 norm (sum of squares of residuals), in which case one obtains a nonlinear separable least squares problem. A number of different methods have been proposed through the years to solve these types of problems and new applications appear

  7. Nonuniform exponential dichotomies and Lyapunov functions

    Science.gov (United States)

    Barreira, Luis; Dragičević, Davor; Valls, Claudia

    2017-05-01

    For the nonautonomous dynamics defined by a sequence of bounded linear operators acting on an arbitrary Hilbert space, we obtain a characterization of the notion of a nonuniform exponential dichotomy in terms of quadratic Lyapunov sequences. We emphasize that, in sharp contrast with previous results, we consider the general case of possibly noninvertible linear operators, thus requiring only the invertibility along the unstable direction. As an application, we give a simple proof of the robustness of a nonuniform exponential dichotomy under sufficiently small linear perturbations.

  8. Arc Tan- Exponential Type Distribution Induced By Stereographic Projection / Bilinear Transformation On Modified Wrapped Exponential Distribution

    Directory of Open Access Journals (Sweden)

    Phani Y.

    2013-05-01

    Full Text Available In this paper we make an attempt to construct a new three parameter linear model, we call this new model as Arc Tan-Exponential Type distribution, by applying Stereographic Projection or equivalently Bilinear transformation on Wrapped Exponential distribution, Probability density and cumulative distribution functions of this new model are presented and their graphs are plotted for various values of parameters.

  9. An Exponential Growth Learning Trajectory: Students' Emerging Understanding of Exponential Growth through Covariation

    Science.gov (United States)

    Ellis, Amy B.; Ozgur, Zekiye; Kulow, Torrey; Dogan, Muhammed F.; Amidon, Joel

    2016-01-01

    This article presents an Exponential Growth Learning Trajectory (EGLT), a trajectory identifying and characterizing middle grade students' initial and developing understanding of exponential growth as a result of an instructional emphasis on covariation. The EGLT explicates students' thinking and learning over time in relation to a set of tasks…

  10. Artistic creation as stimulated by superimposed versus combined-composite visual images.

    Science.gov (United States)

    Rothenberg, A

    1986-02-01

    The creative role of homospatial thinking in visual art was assessed in an experiment with 39 highly talented young artists. In order to compare the creative effects of visual elements occupying the same space with identical elements arrayed in a combined foreground and background organization, superimposed slide images were presented to a randomly selected portion of the subject group, and the other portion of the subject group viewed the same slide images constructed into a figure-ground composite. Both groups produced three drawings stimulated by the slide stimuli, and these drawings were independently judged by three art experts. Results were that drawings produced by the group exposed to the superimposed images were rated higher in creative potential than those stimulated by the figure-ground controls. These results extend previous experimental findings of a tendency toward homospatial thinking in creative individuals in literature and visual art.

  11. Multiple-Element Matching Reservoir Formation and Quantitative Prediction of Favorable Areas in Superimposed Basins

    Institute of Scientific and Technical Information of China (English)

    WANG Huaijie; PANG Xiongqi; WANG Zhaoming; YU Qiuhua; HUO Zhipeng; MENG Qingyang

    2010-01-01

    Superimposed basins in West China have experienced multi-stage tectonic events and multicycle hydrocarbon reservoir formation,and complex hydrocarbon reservoirs have been discovered widely in basins of this kind.Most of the complex hydrocarbon reservoirs are characterized by relocation,scale re-construction,component variation and phase state transformation,and their distributions are very difficult to predict.Research shows that regional caprock(C),high-quality sedimentary facies(Deposits,D),paleohighs(Mountain,M)and source rock(S)are four geologic elements contributing to complex hydrocarbon reservoir formation and distribution of western superimposed basins.Longitudinal sequential combinations of the four elements control the strata of hydrocarbon reservoir formation,and planar superimpositions and combinations control the range of hydrocarbon reservoir and their simultaneous joint effects in geohistory determine the time of hydrocarbon reservoir formation.Multiple-element matching reservoir formation presents a basic mode of reservoir formation in superimposed basins,and we recommend it is expressed as T-CDMS.Based on the multiple-element matching reservoir formation mode,a comprehensive reservoir formation index(Tcdms)is developed in this paper to characterize reservoir formation conditions,and a method is presented to predict reservoir formation range and probability of occurrence in superimposed basins.Through application of new theory,methods and technology,the favorable reservoir formation range and probability of occurrence in the Ordovician target zone in Tarim Basin in four different reservoir formation periods are predicted.Results show that central Tarim,Yinmaili and Lunnan are the three most favorable regions where Ordovician oil and gas fields may have formed.The coincidence of prediction results with currently discovered hydrocarbon reservoirs reaches 97%.This reflects the effectiveness and reliability of the new theory,methods and technology.

  12. Plasma cortisol levels in malnourished children with and without superimposed acute stress

    Science.gov (United States)

    Paisey, R. B.; Angers, Marielena; Frenk, S.

    1973-01-01

    Plasma cortisol levels were measured in 13 children with marasmus, in 7 with kwashiorkor, and in 24 normal children. Cortisol levels in the malnourished children did not differ from those of the normal group, either before or after 15 or 30 days of treatment, unless there was superimposed acute stress. Stress caused by complications such as hypoglycaemia, infection, hypothermia, or acidosis led to raised plasma cortisol levels. PMID:4733640

  13. Superimposed electrical stimulation comfortably improves the endurance of maximal voluntary contractions.

    OpenAIRE

    Boisgontier, Matthieu; Moineau, Bastien; Nougier, Vincent

    2012-01-01

    International audience; AIM: Electrical stimulation has shown to improve muscle endurance in sub-maximal contractions but sessions were painful due to the electric stimuli parameters. Therefore, the present study tested the effects of the superimposed electrical stimulation technique using comfortable current on endurance in repetitions of maximal voluntary contraction. METHODS: Seventeen young healthy subjects performed fifty maximal voluntary contractions of the triceps brachii in two condi...

  14. Acute effects of superimposed electromyostimulation during cycling on myokines and markers of muscle damage

    Science.gov (United States)

    Wahl, P.; Hein, M.; Achtzehn, S.; Bloch, W.; Mester, J.

    2015-01-01

    Objectives: The purpose of the present study was to evaluate the effects of superimposed electromyostimulation (E) during cycling on myokines and markers of muscle damage, as E might be a useful tool to induce a high local stimulus to skeletal muscle during endurance training without performing high external workloads. Methods: 13 subjects participated in three experimental trials each lasting 60 min in a randomized order. 1) Cycling (C), 2) Cycling with superimposed E (C+E) and 3) E. Interleukin-6 (IL-6), brain-derived neurotrophic factor (BDNF), creatine kinase (CK) and myoglobin were determined before (pre) and 0’, 30’, 60’, 240’ and 24h after each intervention. Results: Only C+E caused significant increases in levels of CK and myoglobin. BDNF and IL-6 significantly increased after C and C+E, however increases for IL-6 were significantly higher after C+E compared to C. Conclusion: The present study showed that superimposed E during cycling might be a useful tool to induce a high local stimulus to skeletal muscle even when performing low to moderate external workloads. This effect might be due the activation of additional muscle fibers and mild eccentric work due to the concomitant activation of agonist and antagonist. However the higher load to skeletal muscle has to be taken into account. PMID:25730652

  15. On exponential growth [of gas breakdown

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1991-01-01

    The agreement obtained between measured breakdown voltages and predicted breakdown values is frequently used as a means of assessing the validity of the theory/model in question. However, owing to the mathematical nature of exponential growth, it is easy to formulate a criterion that provides...

  16. Intersection of the Exponential and Logarithmic Curves

    Science.gov (United States)

    Boukas, Andreas; Valahas, Theodoros

    2009-01-01

    The study of the number of intersection points of y = a[superscript x] and y = log[subscript a]x can be an interesting topic to present in a single-variable calculus class. In this article, the authors present a classroom presentation outline involving the basic algebra and the elementary calculus of the exponential and logarithmic functions. The…

  17. When Economic Growth is Less than Exponential

    DEFF Research Database (Denmark)

    Groth, Christian; Koch, Karl-Josef; Steger, Thomas M.

    This paper argues that growth theory needs a more general notion of "regularity" than that of exponential growth. We suggest that paths along which the rate of decline of the growth rate is proportional to the growth rate itself deserve attention. This opens up for considering a richer set...

  18. Exponential lifetime improvement in topological quantum memories

    Science.gov (United States)

    Bardyn, Charles-Edouard; Karzig, Torsten

    2016-09-01

    We propose a simple yet efficient mechanism for passive error correction in topological quantum memories. Our scheme relies on driven-dissipative ancilla systems which couple to local excitations (anyons) and make them "sink" in energy, with no required interaction among ancillae or anyons. Through this process, anyons created by some thermal environment end up trapped in potential "trenches" that they themselves generate, which can be interpreted as a "memory foam" for anyons. This self-trapping mechanism provides an energy barrier for anyon propagation and removes entropy from the memory by favoring anyon recombination over anyon separation (responsible for memory errors). We demonstrate that our scheme leads to an exponential increase of the memory-coherence time with system size L , up to an upper bound Lmax, which can increase exponentially with Δ /T , where T is the temperature and Δ is some energy scale defined by potential trenches. This results in a double exponential increase of the memory time with Δ /T , which greatly improves over the Arrhenius (single-exponential) scaling found in typical quantum memories.

  19. Couplings and Asymptotic Exponentiality of Exit Times

    Science.gov (United States)

    Brassesco, S.; Olivieri, E.; Vares, M. E.

    1998-10-01

    The goal of this note is simply to call attention to the resulting simplification in the proof of asymptotic exponentiality of exit times in the Freidlin-Wentzell regime (as proved by F. Martinelli et al.) by using the coupling proposed by T. Lindvall and C. Rogers.

  20. A Simple Mechanical Experiment on Exponential Growth

    Science.gov (United States)

    McGrew, Ralph

    2015-01-01

    With a rod, cord, pulleys, and slotted masses, students can observe and graph exponential growth in the cord tension over a factor of increase as large as several hundred. This experiment is adaptable for use either in algebra-based or calculus-based physics courses, fitting naturally with the study of sliding friction. Significant parts of the…

  1. Exponentially tapered Josephson flux-flow oscillator

    DEFF Research Database (Denmark)

    Benabdallah, A.; Caputo, J. G.; Scott, Alwyn C.

    1996-01-01

    We introduce an exponentially tapered Josephson flux-flow oscillator that is tuned by applying a bias current to the larger end of the junction. Numerical and analytical studies show that above a threshold level of bias current the static solution becomes unstable and gives rise to a train of flu......, and (iv) better impedance matching to a load....

  2. Functional Regression for General Exponential Families

    CERN Document Server

    Dou, Wei; Zhou, Harrison H

    2010-01-01

    The paper derives a minimax lower bound for rates of convergence for an infinite-dimensional parameter in an exponential family model. An estimator that achieves the optimal rate is constructed by maximum likelihood on finite-dimensional approximations with parameter dimension that grows with sample size.

  3. Generalized approach to non-exponential relaxation

    Indian Academy of Sciences (India)

    R M Pickup; R Cywinski; C Pappas; P Fouquet; B Farago; P Falus

    2008-11-01

    Non-exponential relaxation is a universal feature of systems as diverse as glasses, spin glasses, earthquakes, financial markets and the universe. Complex relaxation results from hierarchically constrained dynamics with the strength of the constraints being directly related to the form of the relaxation, which changes from a simple exponential to a stretched exponential and a power law by increasing the constraints in the system. A global and unified approach to non-exponentiality was first achieved by Weron and was further generalized by Brouers and Sotolongo-Costa, who applied the concept of non-extensive entropy introduced by Tsallis to the relaxation of disordered systems. These concepts are now confronted with experimental results on the classical metallic spin glasses CuMn, AuFe and the insulating system EuSrS. The revisited data have also be complemented by new results on several compositions of the classical CuMn spin glass and on systems, like CoGa and CuCo, the magnetic behaviour of which is believed to arise from magnetic clusters and should be characteristic for superparamagnetism.

  4. Application of Multi-Exponential Inversion Method to NMR Measurements

    Institute of Scientific and Technical Information of China (English)

    XiaoLizhi; WangZhongdong; LiuTangyan

    2004-01-01

    A new multi-exponential inversion method for NMR relaxation signals is presented and tested, which is based on a solid iteration rebuild technique (SIRT). The T2 spectra inversed by the new method are compared with MAP-Ⅱ results. The T1 and T2 inversion results with different pre-assigned relaxation times and different SNR show that 16 to 64 logarithm equal spaced time constants is better obviously than MAP-Ⅱ. And in particular, it can ensure the relaxation time distribution when the SNR of the measured signal is very low. The new algorithm has been applied in rock core NMR analysis and NMR logging data process and interpretation.

  5. Matrix-exponential distributions in applied probability

    CERN Document Server

    Bladt, Mogens

    2017-01-01

    This book contains an in-depth treatment of matrix-exponential (ME) distributions and their sub-class of phase-type (PH) distributions. Loosely speaking, an ME distribution is obtained through replacing the intensity parameter in an exponential distribution by a matrix. The ME distributions can also be identified as the class of non-negative distributions with rational Laplace transforms. If the matrix has the structure of a sub-intensity matrix for a Markov jump process we obtain a PH distribution which allows for nice probabilistic interpretations facilitating the derivation of exact solutions and closed form formulas. The full potential of ME and PH unfolds in their use in stochastic modelling. Several chapters on generic applications, like renewal theory, random walks and regenerative processes, are included together with some specific examples from queueing theory and insurance risk. We emphasize our intention towards applications by including an extensive treatment on statistical methods for PH distribu...

  6. Statistical estimation for truncated exponential families

    CERN Document Server

    Akahira, Masafumi

    2017-01-01

    This book presents new findings on nonregular statistical estimation. Unlike other books on this topic, its major emphasis is on helping readers understand the meaning and implications of both regularity and irregularity through a certain family of distributions. In particular, it focuses on a truncated exponential family of distributions with a natural parameter and truncation parameter as a typical nonregular family. This focus includes the (truncated) Pareto distribution, which is widely used in various fields such as finance, physics, hydrology, geology, astronomy, and other disciplines. The family is essential in that it links both regular and nonregular distributions, as it becomes a regular exponential family if the truncation parameter is known. The emphasis is on presenting new results on the maximum likelihood estimation of a natural parameter or truncation parameter if one of them is a nuisance parameter. In order to obtain more information on the truncation, the Bayesian approach is also considere...

  7. Harmonic analysis on exponential solvable Lie groups

    CERN Document Server

    Fujiwara, Hidenori

    2015-01-01

    This book is the first one that brings together recent results on the harmonic analysis of exponential solvable Lie groups. There still are many interesting open problems, and the book contributes to the future progress of this research field. As well, various related topics are presented to motivate young researchers. The orbit method invented by Kirillov is applied to study basic problems in the analysis on exponential solvable Lie groups. This method tells us that the unitary dual of these groups is realized as the space of their coadjoint orbits. This fact is established using the Mackey theory for induced representations, and that mechanism is explained first. One of the fundamental problems in the representation theory is the irreducible decomposition of induced or restricted representations. Therefore, these decompositions are studied in detail before proceeding to various related problems: the multiplicity formula, Plancherel formulas, intertwining operators, Frobenius reciprocity, and associated alge...

  8. Perturbing Misiurewicz Parameters in the Exponential Family

    Science.gov (United States)

    Dobbs, Neil

    2015-04-01

    In one-dimensional real and complex dynamics, a map whose post-singular (or post-critical) set is bounded and uniformly repelling is often called a Misiurewicz map. In results hitherto, perturbing a Misiurewicz map is likely to give a non-hyperbolic map, as per Jakobson's Theorem for unimodal interval maps. This is despite genericity of hyperbolic parameters (at least in the interval setting). We show the contrary holds in the complex exponential family Misiurewicz maps are Lebesgue density points for hyperbolic parameters. As a by-product, we also show that Lyapunov exponents almost never exist for exponential Misiurewicz maps. The lower Lyapunov exponent is -∞ almost everywhere. The upper Lyapunov exponent is non-negative and depends on the choice of metric.

  9. Six-Parameter Exponential-Type Potential and the Identity for the Exponential-Type Potentials

    Institute of Scientific and Technical Information of China (English)

    JIA Chun-Sheng; ZENG Xiang-Lin; LI Shu-Chuan; SUN Liang-Tian; YANG Qiu-Bo

    2002-01-01

    We propose a six-parameter exponential-type potential (SPEP), which has been shown to be a shape-invariant potential with a translation of parameters. For this reducible potential, the exact energy levels are obtained byusing the supersymmetric shape invariance technique. Choosing appropriate parameters, four classes of exponential-typepotentials and their exact energy spectra are reduced from the SPEP and a general energy level formula, respectively.Each class shows the identity except for the different definitions of parameters.

  10. Financing exponential growth at H3

    OpenAIRE

    2012-01-01

    H3 is a fast-food chain that introduced the concept of gourmet hamburgers in the Portuguese market. This case-study illustrates its financing strategy that supported an exponential growth represented by opening 33 restaurants within approximately 3 years of its inception. H3 is now faced with the challenge of structuring its foreign ventures and change its financial approach. The main covered topics are the options an entrepreneur has for financing a new venture and how it evolves along th...

  11. An exponential correction to Starobinsky's inflationary model

    CERN Document Server

    Fabris, Júlio C; Piattella, Oliver F

    2016-01-01

    We analyse $f(R)$ theories of gravity from a dynamical system perspective, showing how the $R^2$ correction in Starobinsky's model plays a crucial role from the viewpoint of the inflationary paradigm. Then, we propose a modification of Starobinsky's model by adding an exponential term in the $f(R)$ Lagrangian. We show how this modification could allow to test the robustness of the model by means of the predictions on the scalar spectral index $n_s$.

  12. Exponential Stabilization of an Underactuated Surface Vessel

    Directory of Open Access Journals (Sweden)

    Kristin Y. Pettersen

    1997-07-01

    Full Text Available The paper shows that a large class of underactuated vehicles cannot be asymptotically stabilized by either continuous or discontinuous state feedback. Furthermore, stabilization of an underactuated surface vessel is considered. Controllability properties of the surface vessels is presented, and a continuous periodic time-varying feedback law is proposed. It is shown that this feedback law exponentially stabilizes the surface vessel to the origin, and this is illustrated by simulations.

  13. Scalar field collapse with an exponential potential

    Science.gov (United States)

    Chakrabarti, Soumya

    2017-02-01

    An analogue of the Oppenheimer-Synder collapsing model is treated analytically, where the matter source is a scalar field with an exponential potential. An exact solution is derived followed by matching to a suitable exterior geometry, and an analysis of the visibility of the singularity. In some situations, the collapse indeed leads to a finite time curvature singularity, which is always hidden from the exterior by an apparent horizon.

  14. Exponential Attractor for a Nonlinear Boussinesq Equation

    Institute of Scientific and Technical Information of China (English)

    Ahmed Y. Abdallah

    2006-01-01

    This paper is devoted to prove the existence of an exponential attractor for the semiflow generated by a nonlinear Boussinesq equation. We formulate the Boussinesq equation as an abstract equation in the Hilbert space H20(0, 1) × L2(0, 1). The main step in this research is to show that there exists an absorbing set for the solution semiflow in the Hilbert space H03(0, 1) × H10(0, 1).

  15. On the ranges of discrete exponentials

    Directory of Open Access Journals (Sweden)

    Florin Caragiu

    2004-01-01

    Full Text Available Let a>1 be a fixed integer. We prove that there is no first-order formula ϕ(X in one free variable X, written in the language of rings, such that for any prime p with gcd(a,p=1 the set of all elements in the finite prime field Fp satisfying ϕ coincides with the range of the discrete exponential function t↦at(modp.

  16. Asynchronous exponential growth of a bacterial population

    Directory of Open Access Journals (Sweden)

    Mohamed Boulanouar

    2014-01-01

    Full Text Available In this work, we complete a study started earlier in [1,2] wherein a model of growing bacterial population has been the matter of a mathematical analysis. We show that the full model is governed by a strongly continuous semigroup. Beside the positivity and the irreducibility of the generated semigroup, we describe its asymptotic behavior in the uniform topology which leads to the asynchronous exponential growth of the bacterial population.

  17. Estimation and variable selection with exponential weights

    OpenAIRE

    Arias-Castro, Ery; Lounici, Karim

    2014-01-01

    In the context of a linear model with a sparse coefficient vector, exponential weights methods have been shown to be achieve oracle inequalities for denoising/prediction. We show that such methods also succeed at variable selection and estimation under the near minimum condition on the design matrix, instead of much stronger assumptions required by other methods such as the Lasso or the Dantzig Selector. The same analysis yields consistency results for Bayesian methods and BIC-type variable s...

  18. Unwrapped phase inversion with an exponential damping

    KAUST Repository

    Choi, Yun Seok

    2015-07-28

    Full-waveform inversion (FWI) suffers from the phase wrapping (cycle skipping) problem when the frequency of data is not low enough. Unless we obtain a good initial velocity model, the phase wrapping problem in FWI causes a result corresponding to a local minimum, usually far away from the true solution, especially at depth. Thus, we have developed an inversion algorithm based on a space-domain unwrapped phase, and we also used exponential damping to mitigate the nonlinearity associated with the reflections. We construct the 2D phase residual map, which usually contains the wrapping discontinuities, especially if the model is complex and the frequency is high. We then unwrap the phase map and remove these cycle-based jumps. However, if the phase map has several residues, the unwrapping process becomes very complicated. We apply a strong exponential damping to the wavefield to eliminate much of the residues in the phase map, thus making the unwrapping process simple. We finally invert the unwrapped phases using the back-propagation algorithm to calculate the gradient. We progressively reduce the damping factor to obtain a high-resolution image. Numerical examples determined that the unwrapped phase inversion with a strong exponential damping generated convergent long-wavelength updates without low-frequency information. This model can be used as a good starting model for a subsequent inversion with a reduced damping, eventually leading to conventional waveform inversion.

  19. Non-exponential decay of atomic systems

    CERN Document Server

    Ishkhanyan, A M

    2014-01-01

    We discuss the possibility of non-exponential decay of various quantum quasi-stationary systems. This effect can occur at the times which are greater than the lifetime of a considered system. The mechanism for non-exponential depletion of an initial quasi-stationary state is the cutting of the energy spectrum of final continuous states at long times. We first consider the known examples of cold emission of electrons from metal, tunneling alpha-decay of atomic nuclei, and spontaneous decay in two-level systems. The new physical situations discussed are the single-photon atomic ionization by a weak electromagnetic field and tunneling ionization of atoms by a strong low-frequency electromagnetic field. In both cases the decay obeys a power-law dependence on the (long) interaction time. We find that the most promising possibility for observing non-exponential decay at long times is the single-photon ionization of negative atomic ions near the threshold.

  20. Nitrogen washout during tidal breathing with superimposed high-frequency chest wall oscillation.

    Science.gov (United States)

    Harf, A; Zidulka, A; Chang, H K

    1985-08-01

    In order to assess the efficacy of high-frequency chest wall oscillation (HFCWO) superimposed on tidal ventilation, multiple-breath nitrogen washout curves were obtained in 7 normal seated subjects. To maintain a regular breathing pattern throughout the study, the subjects breathed synchronously with a Harvard ventilator set at a constant tidal volume and frequency for each subject during a trial period. Washout curves were obtained during 3 different maneuvers performed in random order. Series A was the control condition with no superimposed HFCWO. In Series B and C, HFCWO at 5 Hz was superimposed on the regulated tidal breathing; the magnitude of the oscillatory tidal volume measured at the airway opening was 20 ml for Series B and 40 ml for Series C. The nitrogen washout was clearly faster in Series C than in Series A for each subject. In Series B, there was an interindividual variability, with a washout rate either equal to that in Maneuver A or in Maneuver C, or intermediate between the two. When these washout curves were analyzed in terms of a simple monocompartment model, the time constant of the washout was found to decrease by 16 +/- 11% in Series B, and 25 +/- 7% in Series C compared with that in Series A. In this group of normal subjects, the correction of any inhomogeneity in the distribution of the ventilation is unlikely to explain these results because of the close fit of all washout curves to a monoexponential model. It is postulated that during inspiration HFCWO enhances gas mixing in the lung periphery and that during expiration it improves gas mixing in the airways.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Aspirin plus calcium supplementation to prevent superimposed preeclampsia: a randomized trial

    Directory of Open Access Journals (Sweden)

    E.V. Souza

    2014-05-01

    Full Text Available Preeclampsia is an important cause of maternal and perinatal morbidity and mortality. Previous studies have tested calcium supplementation and aspirin separately to reduce the incidence of preeclampsia but not the effects of combined supplementation. The objective of this study was to investigate the effectiveness of aspirin combined with calcium supplementation to prevent preeclampsia in women with chronic hypertension. A double-blind, placebo-controlled randomized clinical trial was carried out at the antenatal clinic of a large university hospital in São Paulo, SP, Brazil. A total of 49 women with chronic hypertension and abnormal uterine artery Doppler at 20-27 weeks gestation were randomly assigned to receive placebo (N = 26 or 100 mg aspirin plus 2 g calcium (N = 23 daily until delivery. The main outcome of this pilot study was development of superimposed preeclampsia. Secondary outcomes were fetal growth restriction and preterm birth. The rate of superimposed preeclampsia was 28.6% lower among women receiving aspirin plus calcium than in the placebo group (52.2 vs 73.1%, respectively, P=0.112. The rate of fetal growth restriction was reduced by 80.8% in the supplemented group (25 vs 4.8% in the placebo vs supplemented groups, respectively; P=0.073. The rate of preterm birth was 33.3% in both groups. The combined supplementation of aspirin and calcium starting at 20-27 weeks of gestation produced a nonsignificant decrease in the incidence of superimposed preeclampsia and fetal growth restriction in hypertensive women with abnormal uterine artery Doppler.

  2. Aspirin plus calcium supplementation to prevent superimposed preeclampsia: a randomized trial.

    Science.gov (United States)

    Souza, E V; Torloni, M R; Atallah, A N; Santos, G M S dos; Kulay, L; Sass, N

    2014-05-01

    Preeclampsia is an important cause of maternal and perinatal morbidity and mortality. Previous studies have tested calcium supplementation and aspirin separately to reduce the incidence of preeclampsia but not the effects of combined supplementation. The objective of this study was to investigate the effectiveness of aspirin combined with calcium supplementation to prevent preeclampsia in women with chronic hypertension. A double-blind, placebo-controlled randomized clinical trial was carried out at the antenatal clinic of a large university hospital in São Paulo, SP, Brazil. A total of 49 women with chronic hypertension and abnormal uterine artery Doppler at 20-27 weeks gestation were randomly assigned to receive placebo (N = 26) or 100 mg aspirin plus 2 g calcium (N = 23) daily until delivery. The main outcome of this pilot study was development of superimposed preeclampsia. Secondary outcomes were fetal growth restriction and preterm birth. The rate of superimposed preeclampsia was 28.6% lower among women receiving aspirin plus calcium than in the placebo group (52.2 vs 73.1%, respectively, P=0.112). The rate of fetal growth restriction was reduced by 80.8% in the supplemented group (25 vs 4.8% in the placebo vs supplemented groups, respectively; P=0.073). The rate of preterm birth was 33.3% in both groups. The combined supplementation of aspirin and calcium starting at 20-27 weeks of gestation produced a nonsignificant decrease in the incidence of superimposed preeclampsia and fetal growth restriction in hypertensive women with abnormal uterine artery Doppler.

  3. The Dahl salt-sensitive rat is a spontaneous model of superimposed preeclampsia.

    Science.gov (United States)

    Gillis, Ellen E; Williams, Jan M; Garrett, Michael R; Mooney, Jennifer N; Sasser, Jennifer M

    2015-07-01

    The mechanisms of the pathogenesis of preeclampsia, a leading cause of maternal morbidity and death worldwide, are poorly understood in part due to a lack of spontaneous animal models of the disease. We hypothesized that the Dahl salt-sensitive (S) rat, a genetic model of hypertension and kidney disease, is a spontaneous model of superimposed preeclampsia. The Dahl S was compared with the Sprague-Dawley (SD) rat, a strain with a well-characterized normal pregnancy, and the spontaneously hypertensive rat (SHR), a genetic model of hypertension that does not experience a preeclamptic phenotype despite preexisting hypertension. Mean arterial pressure (MAP, measured via telemetry) was elevated in the Dahl S and SHR before pregnancy, but hypertension was exacerbated during pregnancy only in Dahl S. In contrast, SD and SHR exhibited significant reductions in MAP consistent with normal pregnancy. Dahl S rats exhibited a severe increase in urinary protein excretion, glomerulomegaly, increased placental hypoxia, increased plasma soluble fms-like tyrosine kinase-1 (sFlt-1), and increased placental production of tumor necrosis factor-α (TNF-α). The Dahl S did not exhibit the expected decrease in uterine artery resistance during late pregnancy in contrast to the SD and SHR. Dahl S pups and litter sizes were smaller than in the SD. The Dahl S phenotype is consistent with many of the characteristics observed in human superimposed preeclampsia, and we propose that the Dahl S should be considered further as a spontaneous model to improve our understanding of the pathogenesis of superimposed preeclampsia and to identify and test new therapeutic targets for its treatment.

  4. Pixelated speckle image holography carrier fringes for efficient superimposed light harvesting in organic solar cells

    Science.gov (United States)

    Zhou, Lei; Li, Yan-Qing; Chen, Jing-De; Ou, Qing-Dong; Tang, Jian-Xin; Zhou, Yun; Lin, Yi; Wei, Huai-Xin

    2017-06-01

    An inverted organic solar cell (OSC) device structure by incorporating pixelated speckle image holography carrier fringes (SIHFs) for efficient superimposed light harvesting is demonstrated. The proposed SIHF based OSCs yield an 18.2% increase in power conversion efficiency (PCE) compared to that of the flat control devices. Moreover, compared to the common two-dimensional (2D) periodic grating patterned OSCs, SIHF based devices achieve 7.8% higher short-circuit current (JSC) and 10.0% higher PCE. This observable improvement in PCE of SIHF based OSCs is mainly ascribed to the geometric effect due to the unique chaotic carrier fringes of SIHFs.

  5. Freezing, accelerating and slowing directed currents in real time with superimposed driven lattices

    CERN Document Server

    Mukhopadhyay, Aritra K; Wulf, Thomas; Schmelcher, Peter

    2016-01-01

    We provide a generic scheme offering real time control of directed particle transport in superimposed driven lattices. This scheme allows to accelerate, slow and freeze the transport on demand, by switching one of the lattices subsequently on and off. The underlying physical mechanism hinges on a systematic opening and closing of channels between transporting and non-transporting phase space structures upon switching, and exploits cantori structures which generate memory effects in the population of these structures. Our results should allow for real time control of cold thermal atomic ensembles in optical lattices, but might also be useful as a design principle for targeted delivery of molecules or colloids in optical devices.

  6. Buckling patterns of gold thin films on silicon substrates: Formation of superimposed blisters

    Science.gov (United States)

    Colin, J.; Coupeau, C.; Durinck, J.; Grilhé, J.

    2009-06-01

    Buckling phenomena leading to the formation of superimposed blisters have been experimentally observed with the help of a confocal interferometric microscope onto the surface of gold thin films deposited on silicon substrates. Assuming that residual folding effects resulting from plastic deformation mechanisms take place in the film during its morphological evolution, different probable scenarios for the formation of the observed buckling patterns are elaborated in the framework of the Föppl-von Karman's theory of thin plates. Multi-step buckling with growing interface delamination is considered for the first scenario while a single or multi-step buckling at a given delamination width is assumed for the other ones.

  7. [Relationship between jaws and the masseter muscle by superimposing MR images on the cephalogram].

    Science.gov (United States)

    Higashino, Ryoji

    2006-03-01

    The purpose of this study was to observe the morphological relationship between maxillofacial skeleton and masseter by superimposing the masseter image constructed by MR image scanning on the cephalogram. Sixteen subjects with different mandibular plane angle were examined in this study. Cephalogram and MR images of each subject were taken, and the images were input to a computer by using a digitizer. The areas of masseter were selected in each MR scan image which were projected to the mid-sagittal layer of the MR scan images. The synthesized image of cephalogram and masseter was obtained by completely superimposing sagittal images of the masseter with the mid-sagittal-plane MR image on the cephalogram. The inclination of masseter was determined by the center of gravity on the cross-section of masseter. These synthesized images of cephalogram and masseter showed various shapes of masseter according to different mandibular plane angle. The inclination of masseter had a close correlation with some skeletal parameters (mandibular plane angle, ANB, Y-axis, facial angle, saddle angle) of cephalometric analysis. The volume of the masseter also had a close correlation with skeletal parameters (mandibular plane angle, gonial angle, Y-axis). These results revealed that morphometric analysis using synthesized images of cephalogram and masseter is useful, and that the inclination and the volume of masseter may have an influence on the shape of the mandibular bone and its vertical and anteroposterior development.

  8. A System on a Programmable Chip Architecture for Data-Dependent Superimposed Training Channel Estimation

    Directory of Open Access Journals (Sweden)

    Fernando Martín del Campo

    2009-01-01

    with the information, a series of known symbols, whose analysis is used to define the parameters of the filters that remove the distortion of the data. Nevertheless, a part of the available bandwidth has to be destined to these symbols. Until now, no alternative solution has demonstrated to be fully satisfying for commercial use, but one technique that looks promising is superimposed training (ST. This work describes a hybrid software-hardware FPGA implementation of a recent algorithm that belongs to the ST family, known as Data-dependent Superimposed Training (DDST, which does not need extra bandwidth for its training sequences (TS as it adds them arithmetically to the data. DDST also adds a third sequence known as data-dependent sequence, that destroys the interference caused by the data over the TS. As DDST's computational burden is too high for the commercial processors used in mobile systems, a System on a Programmable Chip (SOPC approach is used in order to solve the problem.

  9. Simultaneously mapping and superimposing landmark configurations with parsimony as optimality criterion.

    Science.gov (United States)

    Catalano, S A; Goloboff, P A

    2012-05-01

    All methods proposed to date for mapping landmark configurations on a phylogenetic tree start from an alignment generated by methods that make no use of phylogenetic information, usually by superimposing all configurations against a consensus configuration. In order to properly interpret differences between landmark configurations along the tree as changes in shape, the metric chosen to define the ancestral assignments should also form the basis to superimpose the configurations. Thus, we present here a method that merges both steps, map and align, into a single procedure that (for the given tree) produces a multiple alignment and ancestral assignments such that the sum of the Euclidean distances between the corresponding landmarks along tree nodes is minimized. This approach is an extension of the method proposed by Catalano et al. (2010. Phylogenetic morphometrics (I): the use of landmark data in a phylogenetic framework. Cladistics. 26:539-549) for mapping landmark data with parsimony as optimality criterion. In the context of phylogenetics, this method allows maximizing the degree to which similarity in landmark positions can be accounted for by common ancestry. In the context of morphometrics, this approach guarantees (heuristics aside) that all the transformations inferred on the tree represent changes in shape. The performance of the method was evaluated on different data sets, indicating that the method produces marked improvements in tree score (up to 5% compared with generalized superimpositions, up to 11% compared with ordinary superimpositions). These empirical results stress the importance of incorporating the phylogenetic information into the alignment step.

  10. Bilateral rapidly destructive arthrosis of the hip joint resulting from subchondral fracture with superimposed secondary osteonecrosis

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Takuaki; Iwamoto, Yukihide [Kyushu University, Department of Orthopaedic Surgery, Fukuoka (Japan); Schneider, Robert [Hospital for Special Surgery, Department of Radiology, New York (United States); Bullough, Peter G. [Hospital for Special Surgery, Department of Laboratory Medicine, New York, NY (United States)

    2010-02-15

    A 57-year-old woman suffered rapid destruction of both hip joints over a 10 months period. At the first visit, her radiographs demonstrated slight joint space narrowing and acetabular cyst formation in both hips. Five months later, joint space narrowing had further progressed, and intra-articular injection of steroid was given in both hips. However, the hip pain gradually became worse. Five months later, both joint spaces had totally disappeared and both femoral heads had undergone massive collapse. At gross examination, both resected femoral heads showed extensive opaque yellow areas consistent with osteonecrosis. Microscopic examination of these areas revealed evidence of both extensive fracture and callus formation, as well as necrosis throughout, indicating that the osteonecrosis observed in this case was a secondary phenomenon superimposed on pre-existing osteoarthritis and subchondral fracture. There were many pseudogranulomatous lesions in the marrow space and necrotic area, where tiny fragments of bone and articular cartilage, surrounded by histiocytes and giant cells, were embedded, such as are typically seen in rapidly destructive arthrosis. No radiologic or morphologic evidence of primary osteonecrosis was noted. This case indicates that at least some cases of rapidly destructive arthritis are the result of subchondral fracture with superimposed secondary osteonecrosis. (orig.)

  11. Superimposed XOR: Approaching Capacity Bounds of the Two-Way Relay Channels

    CERN Document Server

    Liu, Jianquan; Xu, Youyun; Wang, Xiaodong

    2010-01-01

    In two-way relay channels, bitwise XOR and symbol-level superposition coding are two popular network-coding based relaying schemes. However, neither of them can approach the capacity bound when the channels in the broadcast phase are asymmetric. In this paper, we present a new physical layer network coding (PLNC) scheme, called \\emph{superimposed XOR}. The new scheme advances the existing schemes by specifically taking into account the channel asymmetry as well as information asymmetry in the broadcast phase. We obtain its achievable rate regions over Gaussian channels when integrated with two known time control protocols in two-way relaying. We also demonstrate their average maximum sum-rates and service delay performances over fading channels. Numerical results show that the proposed superimposed XOR achieves a larger rate region than both XOR and superposition and performs much better over fading channels. We further deduce the boundary of its achievable rate region of the broadcast phase in an explicit an...

  12. Exponential smoothing for financial time series data forecasting

    Directory of Open Access Journals (Sweden)

    Kuzhda, Tetyana Ivanivna

    2014-05-01

    Full Text Available The article begins with the formulation for predictive learning called exponential smoothing forecasting. The exponential smoothing is commonly applied to financial markets such as stock or bond, foreign exchange, insurance, credit, primary and secondary markets. The exponential smoothing models are useful in providing the valuable decision information for investors. Simple and double exponential smoothing models are two basic types of exponential smoothing method. The simple exponential smoothing method is suitable for financial time series forecasting for the specified time period. The simple exponential smoothing weights past observations with exponentially decreasing weights to forecast future values. The double exponential smoothing is a refinement of the simple exponential smoothing model but adds another component which takes into account any trend in the data. The double exponential smoothing is designed to address this type of data series by taking into account any trend in the data. Measurement of the forecast accuracy is described in this article. Finally, the quantitative value of the price per common share forecast using simple exponential smoothing is calculated. The applied recommendations concerning determination of the price per common share forecast using double exponential smoothing are shown in the article.

  13. Exponential Stability Criteria for Nonautonomous Difference Systems

    Directory of Open Access Journals (Sweden)

    Rigoberto Medina

    2014-01-01

    Full Text Available The aim of this paper is to characterize the exponential stability of linear systems of difference equations with slowly varying coefficients. Our approach is based on the generalization of the freezing method for difference equations combined with new estimates for the norm of bounded linear operators. The main novelty of this work is that we use estimates for the absolute values of entries of a matrix-valued function, instead of bounds on its eigenvalues. By this method, new explicit stability criteria for linear nonautonomous systems are derived.

  14. Exponential sums over primes in short intervals

    Institute of Scientific and Technical Information of China (English)

    LIU Jianya; L(U) Guangshi; ZHAN Tao

    2006-01-01

    In this paper we establish one new estimate on exponential sums over primes in short intervals. As an application of this result, we sharpen Hua's result by proving that each sufficiently large integer N congruent to 5 modulo 24 can be written as N = p21 +p22 +p23 +p24 +p25, with |pj - √N/5| ≤ U = N1/2-1/20+ε,where pj are primes. This result is as good as what one can obtain from the generalized Riemann hypothesis.

  15. Finite difference computing with exponential decay models

    CERN Document Server

    Langtangen, Hans Petter

    2016-01-01

    This text provides a very simple, initial introduction to the complete scientific computing pipeline: models, discretization, algorithms, programming, verification, and visualization. The pedagogical strategy is to use one case study – an ordinary differential equation describing exponential decay processes – to illustrate fundamental concepts in mathematics and computer science. The book is easy to read and only requires a command of one-variable calculus and some very basic knowledge about computer programming. Contrary to similar texts on numerical methods and programming, this text has a much stronger focus on implementation and teaches testing and software engineering in particular. .

  16. Two Interesting Properties of the Exponential Distribution

    OpenAIRE

    Chen, Robert W.

    2015-01-01

    Let $X_1, X_2,\\ldots, X_n$ be $n$ independent and identically distributed random variables, here $n \\geq 2.$ Let $X_{(1)}, X_{(2)}, \\ldots, X_{(n)}$ be the order statistics of $X_1, X_2,..., X_n.$ In this note we proved that: (I) If $X_1, X_2,..., X_n$ are exponential random variables with parameter $c > 0,$ then the "correlation coefficient" between $X_{(k)}$ and $X_{(k+t)}$ is strictly increasing in $k$ from $1$ to $m,$ and then is strictly decreasing in $k$ from $m$ to $n - t,$ here $t$ is...

  17. Progressive Exponential Clustering-Based Steganography

    Directory of Open Access Journals (Sweden)

    Li Yue

    2010-01-01

    Full Text Available Cluster indexing-based steganography is an important branch of data-hiding techniques. Such schemes normally achieve good balance between high embedding capacity and low embedding distortion. However, most cluster indexing-based steganographic schemes utilise less efficient clustering algorithms for embedding data, which causes redundancy and leaves room for increasing the embedding capacity further. In this paper, a new clustering algorithm, called progressive exponential clustering (PEC, is applied to increase the embedding capacity by avoiding redundancy. Meanwhile, a cluster expansion algorithm is also developed in order to further increase the capacity without sacrificing imperceptibility.

  18. Exponentially Convergent Algorithms for Abstract Differential Equations

    CERN Document Server

    Gavrilyuk, Ivan; Vasylyk, Vitalii

    2011-01-01

    This book presents new accurate and efficient exponentially convergent methods for abstract differential equations with unbounded operator coefficients in Banach space. These methods are highly relevant for the practical scientific computing since the equations under consideration can be seen as the meta-models of systems of ordinary differential equations (ODE) as well as the partial differential equations (PDEs) describing various applied problems. The framework of functional analysis allows one to obtain very general but at the same time transparent algorithms and mathematical results which

  19. Information and exponential families in statistical theory

    CERN Document Server

    Barndorff-Nielsen, O

    2014-01-01

    First published by Wiley in 1978, this book is being re-issued with a new Preface by the author. The roots of the book lie in the writings of RA Fisher both as concerns results and the general stance to statistical science, and this stance was the determining factor in the author's selection of topics. His treatise brings together results on aspects of statistical information, notably concerning likelihood functions, plausibility functions, ancillarity, and sufficiency, and on exponential families of probability distributions. 

  20. Compact vs. Exponential-Size LP Relaxations

    Energy Technology Data Exchange (ETDEWEB)

    Carr, R.D.; Lancia, G.

    2000-09-01

    In this paper we introduce by means of examples a new technique for formulating compact (i.e. polynomial-size) LP relaxations in place of exponential-size models requiring separation algorithms. In the same vein as a celebrated theorem by Groetschel, Lovasz and Schrijver, we state the equivalence of compact separation and compact optimization. Among the examples used to illustrate our technique, we introduce a new formulation for the Traveling Salesman Problem, whose relaxation we show equivalent to the subtour elimination relaxation.

  1. Exponential algorithmic speedup by quantum walk

    CERN Document Server

    Childs, A M; Deotto, E; Farhi, E; Gutmann, S; Spielman, D A; Childs, Andrew M.; Cleve, Richard; Deotto, Enrico; Farhi, Edward; Gutmann, Sam; Spielman, Daniel A.

    2002-01-01

    We construct an oracular problem that can be solved exponentially faster on a quantum computer than on a classical computer. The quantum algorithm is based on a continuous time quantum walk, and thus employs a different technique from previous quantum algorithms based on quantum Fourier transforms. We show how to implement the quantum walk efficiently in our oracular setting. We then show how this quantum walk can be used to solve our problem by rapidly traversing a graph. Finally, we prove that no classical algorithm can solve this problem with high probability in subexponential time.

  2. AN EME BLIND SOURCE SEPARATION ALGORITHM BASED ON GENERALIZED EXPONENTIAL FUNCTION

    Institute of Scientific and Technical Information of China (English)

    Miao Hao; Li Xiaodong; Tian Jing

    2008-01-01

    This letter investigates an improved blind source separation algorithm based on Maximum Entropy (ME) criteria. The original ME algorithm chooses the fixed exponential or sigmoid function as the nonlinear mapping function which can not match the original signal very well. A parameter estimation method is employed in this letter to approach the probability of density function of any signal with parameter-steered generalized exponential function. An improved learning rule and a natural gradient update formula of unmixing matrix are also presented. The algorithm of this letter can separate the mixture of super-Gaussian signals and also the mixture of sub-Gaussian signals. The simulation experiment demonstrates the efficiency of the algorithm.

  3. Hyponormal quantization of planar domains exponential transform in dimension two

    CERN Document Server

    Gustafsson, Björn

    2017-01-01

    This book exploits the classification of a class of linear bounded operators with rank-one self-commutators in terms of their spectral parameter, known as the principal function. The resulting dictionary between two dimensional planar shapes with a degree of shade and Hilbert space operators turns out to be illuminating and beneficial for both sides. An exponential transform, essentially a Riesz potential at critical exponent, is at the heart of this novel framework; its best rational approximants unveil a new class of complex orthogonal polynomials whose asymptotic distribution of zeros is thoroughly studied in the text. Connections with areas of potential theory, approximation theory in the complex domain and fluid mechanics are established. The text is addressed, with specific aims, at experts and beginners in a wide range of areas of current interest: potential theory, numerical linear algebra, operator theory, inverse problems, image and signal processing, approximation theory, mathematical physics.

  4. Rounded stretched exponential for time relaxation functions.

    Science.gov (United States)

    Powles, J G; Heyes, D M; Rickayzen, G; Evans, W A B

    2009-12-01

    A rounded stretched exponential function is introduced, C(t)=exp{(tau(0)/tau(E))(beta)[1-(1+(t/tau(0))(2))(beta/2)]}, where t is time, and tau(0) and tau(E) are two relaxation times. This expression can be used to represent the relaxation function of many real dynamical processes, as at long times, t>tau(0), the function converges to a stretched exponential with normalizing relaxation time, tau(E), yet its expansion is even or symmetric in time, which is a statistical mechanical requirement. This expression fits well the shear stress relaxation function for model soft soft-sphere fluids near coexistence, with tau(E)Cole-Cole plots for dielectric and shear stress relaxation (both the modulus and viscosity forms). It is shown that both the dielectric spectra and dynamic shear modulus imaginary parts approach the real axis with a slope equal to 0 at high frequency, whereas the dynamic viscosity has an infinite slope in the same limit. This indicates that inertial effects at high frequency are best discerned in the modulus rather than the viscosity Cole-Cole plot. As a consequence of the even expansion in time of the shear stress relaxation function, the value of the storage modulus derived from it at very high frequency exceeds that in the infinite frequency limit (i.e., G(infinity)).

  5. Reviving Quintessence with an Exponential Potential

    CERN Document Server

    Chang, Hui-Yiing

    2016-01-01

    We examine a quintessence model with a modified exponential potential given by $V(\\phi) = V_0(1+e^{-\\lambda \\phi})$. Unlike quintessence with a standard exponential potential, our model can yield an acceptable accelerated expansion at late times, while producing a distinct "early dark energy" signature at high redshift. We determine the evolution of the equation of state parameter, $w_\\phi$, and the density parameter, $\\Omega_\\phi$, as a function of the scale factor. The strongest constraints on the model come from cosmic microwave background observations rather than supernova data. The former give the limit $\\lambda > 13$. This model predicts a value of the effective neutrino number during Big Bang nucleosynthesis larger than the standard model value. It also provides a partial solution to the coincidence problem, in that the ratio of the quintessence energy density is always within a few orders of magnitude of the background radiation or matter density from the early universe up to the present, but it does ...

  6. On the single-exponential closed form of the product of two exponential operators

    Energy Technology Data Exchange (ETDEWEB)

    Tudor, Tiberiu [Faculty of Physics, University of Bucharest, PO Box MG-11, 0771253 Bucharest-Magurele (Romania)

    2007-12-07

    In the frame of a vectorial Pauli algebraic approach it is shown that the product of two exponentials of any two-by-two linear operators can be put in a single-exponential closed form. As a first application, a compact vectorial expression for the characteristics (angle and axis) of the product of two R{sup 3} rotations is established. The same mathematics can be used in a large diversity of problems of the whole class of two-states physical systems. An exemplification in the field of polarization optics is given.

  7. Exponential and double exponential tails for maximum of two-dimensional discrete Gaussian free field

    CERN Document Server

    Ding, Jian

    2011-01-01

    We study the tail behavior for the maximum of discrete Gaussian free field on a 2D box with Dirichlet boundary condition after centering by its expectation. We show that it exhibits an exponential decay for the right tail and a double exponential decay for the left tail. In particular, our result implies that the variance of the maximum is of order 1, improving an $o(\\log n)$ bound by Chatterjee (2008) and confirming a folklore conjecture. An important ingredient for our proof is a result of Bramson and Zeitouni (2010), who proved the tightness of the centered maximum together with an evaluation of the expectation up to an additive constant.

  8. Global exponential stability for switched memristive neural networks with time-varying delays.

    Science.gov (United States)

    Xin, Youming; Li, Yuxia; Cheng, Zunshui; Huang, Xia

    2016-08-01

    This paper considers the problem of exponential stability for switched memristive neural networks (MNNs) with time-varying delays. Different from most of the existing papers, we model a memristor as a continuous system, and view switched MNNs as switched neural networks with uncertain time-varying parameters. Based on average dwell time technique, mode-dependent average dwell time technique and multiple Lyapunov-Krasovskii functional approach, two conditions are derived to design the switching signal and guarantee the exponential stability of the considered neural networks, which are delay-dependent and formulated by linear matrix inequalities (LMIs). Finally, the effectiveness of the theoretical results is demonstrated by two numerical examples.

  9. Design of air-gapped magnetic-core inductors for superimposed direct and alternating currents

    Science.gov (United States)

    Ohri, A. K.; Wilson, T. G.; Owen, H. A., Jr.

    1976-01-01

    Using data on standard magnetic-material properties and standard core sizes for air-gap-type cores, an algorithm designed for a computer solution is developed which optimally determines the air-gap length and locates the quiescent point on the normal magnetization curve so as to yield an inductor design with the minimum number of turns for a given ac voltage and frequency and with a given dc bias current superimposed in the same winding. Magnetic-material data used in the design are the normal magnetization curve and a family of incremental permeability curves. A second procedure, which requires a simpler set of calculations, starts from an assigned quiescent point on the normal magnetization curve and first screens candidate core sizes for suitability, then determines the required turns and air-gap length.

  10. Superimposed folding and thrusting by two phases of mutually orthogonal or oblique shortening in analogue models

    Science.gov (United States)

    Deng, Hongling; Koyi, Hemin A.; Nilfouroushan, Faramarz

    2016-02-01

    Orogens may suffer more than one phase shortening resulting in superposition of structures of different generations. Superimposition of orthogonal or oblique shortening is studied using sandbox and centrifuge modelling. Results of sand models show that in orthogonal superimposition, the two resulting structural trends are approximately orthogonal to each other. In oblique superimposition, structures trend obliquely to each other in the relatively thin areas of the model (foreland), and mutually orthogonal in areas where the model is thickened during the first phase of shortening (i.e. the hinterland). Thrusts formed during the first shortening phase may be reactivated during the later shortening phase. Spacing of the later phase structures is not as wide as expected, considering they across the pre-existing thickened wedge. Superposition of structures results in formation of type 1 fold interference pattern. Bedding is curved outwards both in the dome and basin structures. Folded layers are dipping and plunging outwards in a dome, while they are dipping and plunging inwards in a basin. In the areas between two adjacent domes or basins (i.e. where an anticline is superimposed by a syncline or a syncline is superimposed by an anticline), bedding is curved inwards, and the anticlines plunge inwards and the synclines outwards. The latter feature could be helpful to determine the age relationship for type 2 fold interference pattern. In tectonic regions where multiple phases of shortening have occurred, the orogenic-scale dome-and-basin and arrowhead-shaped interference patterns are commonly formed, as in the models. However, in some areas, the fold interference pattern might be modified by a later phase of thrusting. Similar to models results, superimposition of two and/or even more deformation phases may not be recorded by structures all over the tectonic area.

  11. Synergistic and Superimposed Effect of Bone Marrow-Derived Mesenchymal Stem Cells Combined with Fasudil in Experimental Autoimmune Encephalomyelitis.

    Science.gov (United States)

    Yu, Jing-Wen; Li, Yan-Hua; Song, Guo-Bin; Yu, Jie-Zhong; Liu, Chun-Yun; Liu, Jian-Chun; Zhang, Hai-Fei; Yang, Wan-Fang; Wang, Qing; Yan, Ya-Ping; Xiao, Bao-Guo; Ma, Cun-Gen

    2016-12-01

    Bone marrow-derived mesenchymal stem cells (MSCs) are the ideal transplanted cells of cellular therapy for promoting neuroprotection and neurorestoration. However, the optimization of transplanted cells and the improvement of microenvironment around implanted cells are still two critical challenges for enhancing therapeutic effect. In the current study, we observed the therapeutic potential of MSCs combined with Fasudil in mouse model of experimental autoimmune encephalomyelitis (EAE) and explored possible mechanisms of action. The results clearly show that combined intervention of MSCs and Fasudil further reduced the severity of EAE compared with MSCs or Fasudil alone, indicating a synergistic and superimposed effect in treating EAE. The addition of Fasudil inhibited MSC-induced inflammatory signaling TLR-4/MyD88 and inflammatory molecule IFN-γ, IL-1β, and TNF-α but did not convert M1 microglia to M2 phenotype. The delivery of MSCs enhanced the expression of glial cell-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) compared with that of Fasudil. Importantly, combined intervention of MSCs and Fasudil further increased the expression of BDNF and GDNF compared with the delivery of MSCs alone, indicating that combined intervention of MSCs and Fasudil synergistically contributes to the expression of neurotrophic factors which should be related to the expression of increased galactocerebroside (GalC) compared with mice treated with Fasudil and MSCs alone. However, a lot of investigation is warranted to further elucidate the cross talk of MSCs and Fasudil in the therapeutic potential of EAE/multiple sclerosis.

  12. Exponential Disks from Stellar Scattering: III. Stochastic Models

    CERN Document Server

    Elmegreen, Bruce G

    2016-01-01

    Stellar scattering off irregularities in a galaxy disk has been shown to make an exponential radial profile, but no fundamental reason for this has been suggested. Here we show that exponentials are mathematically expected from random scattering in a disk when there is a slight inward bias in the scattering probability. Such a bias was present in our previous scattering experiments that formed exponential profiles. Double exponentials can arise when the bias varies with radius. This is a fundamental property of scattering and may explain why piece-wise exponential profiles are ubiquitous in galaxies, even after minor mergers and other disruptive events.

  13. Vortex structures in exponentially shaped Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu. M.; Semerdjieva, E. G.; Boyadjiev, T. L.

    2005-04-01

    We report the numerical calculations of the static vortex structure and critical curves in exponentially shaped long Josephson junctions for in-line and overlap geometries. Stability of the static solutions is investigated by checking the sign of the smallest eigenvalue of the associated Sturm-Liouville problem. The change in the junction width leads to the renormalization of the magnetic flux in comparison with the case of a linear one-dimensional model. We study the influence of the model's parameters, and particularly, the shape parameter on the stability of the states of the magnetic flux. We compare the vortex structure and critical curves for the in-line and overlap geometries. Our numerically constructed critical curve of the Josephson junction matches well with the experimental one.

  14. An exponentiation method for XML element retrieval.

    Science.gov (United States)

    Wichaiwong, Tanakorn

    2014-01-01

    XML document is now widely used for modelling and storing structured documents. The structure is very rich and carries important information about contents and their relationships, for example, e-Commerce. XML data-centric collections require query terms allowing users to specify constraints on the document structure; mapping structure queries and assigning the weight are significant for the set of possibly relevant documents with respect to structural conditions. In this paper, we present an extension to the MEXIR search system that supports the combination of structural and content queries in the form of content-and-structure queries, which we call the Exponentiation function. It has been shown the structural information improve the effectiveness of the search system up to 52.60% over the baseline BM25 at MAP.

  15. On exponential stabilizability of linear neutral systems

    Directory of Open Access Journals (Sweden)

    Dusser Xavier

    2001-01-01

    Full Text Available In this paper, we deal with linear neutral functional differential systems. Using an extended state space and an extended control operator, we transform the initial neutral system in an infinite dimensional linear system. We give a sufficient condition for admissibility of the control operator B , conditions under which operator B can be acceptable in order to work with controllability and stabilizability. Necessary and sufficient conditions for exact controllability are provided; in terms of a gramian of controllability N ( μ . Assuming admissibility and exact controllability, a feedback control law is defined from the inverse of the operator N ( μ in order to stabilize exponentially the closed loop system. In this case, the semigroup generated by the closed loop system has an arbitrary decay rate.

  16. Controlling chaos using an exponential control

    CERN Document Server

    Gadre, S D; Gadre, Sangeeta D; Varma, V S

    1995-01-01

    We demonstrate that chaos can be controlled using a multiplicative exponential feedback control. All three types of unstable orbits - unstable fixed points, limit cycles and chaotic trajectories can be stabilized using this control. The control is effective both for maps and flows. The control is significant, particularly for systems with several degrees of freedom, as knowledge of only one variable on the desired unstable orbit is sufficient to settle the system on to that orbit. We find, that in all the cases studied, the transient time is a decreasing function of the stiffness of control. But increasing the stiffness beyond an optimum value can increase the transient time. The control can also be used to create suitable new stable attractors in a map, which did not exist in the original system.

  17. Poissonian renormalizations, exponentials, and power laws

    Science.gov (United States)

    Eliazar, Iddo

    2013-05-01

    This paper presents a comprehensive “renormalization study” of Poisson processes governed by exponential and power-law intensities. These Poisson processes are of fundamental importance, as they constitute the very bedrock of the universal extreme-value laws of Gumbel, Fréchet, and Weibull. Applying the method of Poissonian renormalization we analyze the emergence of these Poisson processes, unveil their intrinsic dynamical structures, determine their domains of attraction, and characterize their structural phase transitions. These structural phase transitions are shown to be governed by uniform and harmonic intensities, to have universal domains of attraction, to uniquely display intrinsic invariance, and to be intimately connected to “white noise” and to “1/f noise.” Thus, we establish a Poissonian explanation to the omnipresence of white and 1/f noises.

  18. Generalized exponential function and discrete growth models

    Science.gov (United States)

    Souto Martinez, Alexandre; Silva González, Rodrigo; Lauri Espíndola, Aquino

    2009-07-01

    Here we show that a particular one-parameter generalization of the exponential function is suitable to unify most of the popular one-species discrete population dynamic models into a simple formula. A physical interpretation is given to this new introduced parameter in the context of the continuous Richards model, which remains valid for the discrete case. From the discretization of the continuous Richards’ model (generalization of the Gompertz and Verhulst models), one obtains a generalized logistic map and we briefly study its properties. Notice, however that the physical interpretation for the introduced parameter persists valid for the discrete case. Next, we generalize the (scramble competition) θ-Ricker discrete model and analytically calculate the fixed points as well as their stabilities. In contrast to previous generalizations, from the generalized θ-Ricker model one is able to retrieve either scramble or contest models.

  19. Nonlinear elliptic systems with exponential nonlinearities

    Directory of Open Access Journals (Sweden)

    Said El Manouni

    2002-12-01

    Full Text Available In this paper we investigate the existence of solutions for {gather*} -mathop{m div}( a(| abla u | ^N| abla u |^{N-2}u = f(x,u,v quad mbox{in } Omega -mathop{m div}(a(| abla v| ^N| abla v |^{N-2}v = g(x,u,v quad mbox{in } Omega u(x = v(x = 0 quad mbox{on }partial Omega. end{gather*} Where $Omega$ is a bounded domain in ${mathbb{R}}^N$, $Ngeq 2$, $f$ and $g$ are nonlinearities having an exponential growth on $Omega$ and $a$ is a continuous function satisfying some conditions which ensure the existence of solutions.

  20. Exponential Networks and Representations of Quivers

    CERN Document Server

    Eager, Richard; Walcher, Johannes

    2016-01-01

    We study the geometric description of BPS states in supersymmetric theories with eight supercharges in terms of geodesic networks on suitable spectral curves. We lift and extend several constructions of Gaiotto-Moore-Neitzke from gauge theory to local Calabi-Yau threefolds and related models. The differential is multi-valued on the covering curve and features a new type of logarithmic singularity in order to account for D0-branes and non-compact D4-branes, respectively. We describe local rules for the three-way junctions of BPS trajectories relative to a particular framing of the curve. We reproduce BPS quivers of local geometries and illustrate the wall-crossing of finite-mass bound states in several new examples. We describe first steps toward understanding the spectrum of framed BPS states in terms of such "exponential networks."

  1. Transient accelerating scalar models with exponential potentials

    Institute of Scientific and Technical Information of China (English)

    Wen-Ping Cui; Yang Zhang; Zheng-Wen Fu

    2013-01-01

    We study a known class of scalar dark energy models in which the potential has an exponential term and the current accelerating era is transient.We find that,although a decelerating era will return in the future,when extrapolating the model back to earlier stages (z(≥) 4),scalar dark energy becomes dominant over matter.So these models do not have the desired tracking behavior,and the predicted transient period of acceleration cannot be adopted into the standard scenario of the Big Bang cosmology.When couplings between the scalar field and matter are introduced,the models still have the same problem; only the time when deceleration returns will be varied.To achieve re-deceleration,one has to turn to alternative models that are consistent with the standard Big Bang scenario.

  2. An Economic Model of Coupled Exponential Maps

    CERN Document Server

    López-Ruiz, R; Cosenza, M G; Sánchez, J R

    2007-01-01

    In this work, an ensemble of economic interacting agents is considered. The agents are arranged in a linear array where only local couplings are allowed. The deterministic dynamics of each agent is given by a map. This map is expressed by two factors. The first one is a linear term that models the expansion of the agent's economy and that is controlled by the {\\it growth capacity parameter}. The second one is an inhibition exponential term that is regulated by the {\\it local environmental pressure}. Depending on the parameter setting, the system can display Pareto or Boltzmann-Gibbs behavior in the asymptotic dynamical regime. The regions of parameter space where the system exhibits one of these two statistical behaviors are delimited. Other properties of the system, such as the mean wealth, the standard deviation and the Gini coefficient, are also calculated.

  3. Modeling Aftershocks as a Stretched Exponential Relaxation

    CERN Document Server

    Mignan, Arnaud

    2015-01-01

    The decay rate of aftershocks has been modeled as a power law since the pioneering work of Omori in the late nineteenth century. Considered the second most fundamental empirical law after the Gutenberg-Richter relationship, the power law paradigm has rarely been challenged by the seismological community. By taking a view of aftershock research not biased by prior conceptions of Omori power law decay and by applying statistical methods recommended in applied mathematics, I show that all aftershock sequences tested in three regional earthquake catalogs (Southern and Northern California, Taiwan) and with three declustering techniques (nearest-neighbor, second-order moment, window methods) follow a stretched exponential instead of a power law. These results infer that aftershocks are due to a simpler relaxation process than originally thought, in accordance with most other relaxation processes observed in Nature.

  4. Poissonian renormalizations, exponentials, and power laws.

    Science.gov (United States)

    Eliazar, Iddo

    2013-05-01

    This paper presents a comprehensive "renormalization study" of Poisson processes governed by exponential and power-law intensities. These Poisson processes are of fundamental importance, as they constitute the very bedrock of the universal extreme-value laws of Gumbel, Fréchet, and Weibull. Applying the method of Poissonian renormalization we analyze the emergence of these Poisson processes, unveil their intrinsic dynamical structures, determine their domains of attraction, and characterize their structural phase transitions. These structural phase transitions are shown to be governed by uniform and harmonic intensities, to have universal domains of attraction, to uniquely display intrinsic invariance, and to be intimately connected to "white noise" and to "1/f noise." Thus, we establish a Poissonian explanation to the omnipresence of white and 1/f noises.

  5. Exponential Approximations Using Fourier Series Partial Sums

    Science.gov (United States)

    Banerjee, Nana S.; Geer, James F.

    1997-01-01

    The problem of accurately reconstructing a piece-wise smooth, 2(pi)-periodic function f and its first few derivatives, given only a truncated Fourier series representation of f, is studied and solved. The reconstruction process is divided into two steps. In the first step, the first 2N + 1 Fourier coefficients of f are used to approximate the locations and magnitudes of the discontinuities in f and its first M derivatives. This is accomplished by first finding initial estimates of these quantities based on certain properties of Gibbs phenomenon, and then refining these estimates by fitting the asymptotic form of the Fourier coefficients to the given coefficients using a least-squares approach. It is conjectured that the locations of the singularities are approximated to within O(N(sup -M-2), and the associated jump of the k(sup th) derivative of f is approximated to within O(N(sup -M-l+k), as N approaches infinity, and the method is robust. These estimates are then used with a class of singular basis functions, which have certain 'built-in' singularities, to construct a new sequence of approximations to f. Each of these new approximations is the sum of a piecewise smooth function and a new Fourier series partial sum. When N is proportional to M, it is shown that these new approximations, and their derivatives, converge exponentially in the maximum norm to f, and its corresponding derivatives, except in the union of a finite number of small open intervals containing the points of singularity of f. The total measure of these intervals decreases exponentially to zero as M approaches infinity. The technique is illustrated with several examples.

  6. Simultaneous Gaussian and exponential inversion for improved analysis of shales by NMR relaxometry

    Science.gov (United States)

    Washburn, Kathryn E.; Anderssen, Endre; Vogt, Sarah J.; Seymour, Joseph D.; Birdwell, Justin E.; Kirkland, Catherine M.; Codd, Sarah L.

    2014-01-01

    Nuclear magnetic resonance (NMR) relaxometry is commonly used to provide lithology-independent porosity and pore-size estimates for petroleum resource evaluation based on fluid-phase signals. However in shales, substantial hydrogen content is associated with solid and fluid signals and both may be detected. Depending on the motional regime, the signal from the solids may be best described using either exponential or Gaussian decay functions. When the inverse Laplace transform, the standard method for analysis of NMR relaxometry results, is applied to data containing Gaussian decays, this can lead to physically unrealistic responses such as signal or porosity overcall and relaxation times that are too short to be determined using the applied instrument settings. We apply a new simultaneous Gaussian-Exponential (SGE) inversion method to simulated data and measured results obtained on a variety of oil shale samples. The SGE inversion produces more physically realistic results than the inverse Laplace transform and displays more consistent relaxation behavior at high magnetic field strengths. Residuals for the SGE inversion are consistently lower than for the inverse Laplace method and signal overcall at short T2 times is mitigated. Beyond geological samples, the method can also be applied in other fields where the sample relaxation consists of both Gaussian and exponential decays, for example in material, medical and food sciences.

  7. Deformed Algebras and Generalizations of Independence on Deformed Exponential Families

    Directory of Open Access Journals (Sweden)

    Hiroshi Matsuzoe

    2015-08-01

    Full Text Available A deformed exponential family is a generalization of exponential families. Since the useful classes of power law tailed distributions are described by the deformed exponential families, they are important objects in the theory of complex systems. Though the deformed exponential families are defined by deformed exponential functions, these functions do not satisfy the law of exponents in general. The deformed algebras have been introduced based on the deformed exponential functions. In this paper, after summarizing such deformed algebraic structures, it is clarified how deformed algebras work on deformed exponential families. In fact, deformed algebras cause generalization of expectations. The three kinds of expectations for random variables are introduced in this paper, and it is discussed why these generalized expectations are natural from the viewpoint of information geometry. In addition, deformed algebras cause generalization of independences. Whereas it is difficult to check the well-definedness of deformed independence in general, the κ-independence is always well-defined on κ-exponential families. This is one of advantages of κ-exponential families in complex systems. Consequently, we can well generalize the maximum likelihood method for the κ-exponential family from the viewpoint of information geometry.

  8. An exponential decay model for mediation.

    Science.gov (United States)

    Fritz, Matthew S

    2014-10-01

    Mediation analysis is often used to investigate mechanisms of change in prevention research. Results finding mediation are strengthened when longitudinal data are used because of the need for temporal precedence. Current longitudinal mediation models have focused mainly on linear change, but many variables in prevention change nonlinearly across time. The most common solution to nonlinearity is to add a quadratic term to the linear model, but this can lead to the use of the quadratic function to explain all nonlinearity, regardless of theory and the characteristics of the variables in the model. The current study describes the problems that arise when quadratic functions are used to describe all nonlinearity and how the use of nonlinear functions, such as exponential decay, address many of these problems. In addition, nonlinear models provide several advantages over polynomial models including usefulness of parameters, parsimony, and generalizability. The effects of using nonlinear functions for mediation analysis are then discussed and a nonlinear growth curve model for mediation is presented. An empirical example using data from a randomized intervention study is then provided to illustrate the estimation and interpretation of the model. Implications, limitations, and future directions are also discussed.

  9. Black Hole Instabilities and Exponential Growth

    CERN Document Server

    Prabhu, Kartik

    2015-01-01

    Recently, a general analysis has been given of the stability with respect to axisymmetric perturbations of stationary-axisymmetric black holes and black branes in vacuum general relativity in arbitrary dimensions. It was shown that positivity of canonical energy on an appropriate space of perturbations is necessary and sufficient for stability. However, the notions of both "stability" and "instability" in this result are significantly weaker than one would like to obtain. In this paper, we prove that if a perturbation of the form $\\pounds_t \\delta g$---with $\\delta g$ a solution to the linearized Einstein equation---has negative canonical energy, then that perturbation must, in fact, grow exponentially in time. The key idea is to make use of the $t$- or ($t$-$\\phi$)-reflection isometry, $i$, of the background spacetime and decompose the initial data for perturbations into their odd and even parts under $i$. We then write the canonical energy as $\\mathscr E\\ = \\mathscr K + \\mathscr U$, where $\\mathscr K$ and $...

  10. On Simple Graphs Arising from Exponential Congruences

    Directory of Open Access Journals (Sweden)

    M. Aslam Malik

    2012-01-01

    Full Text Available We introduce and investigate a new class of graphs arrived from exponential congruences. For each pair of positive integers a and b, let G(n denote the graph for which V={0,1,…,n−1} is the set of vertices and there is an edge between a and b if the congruence ax≡b (mod n is solvable. Let n=p1k1p2k2⋯prkr be the prime power factorization of an integer n, where p1

  11. Evidence for super-exponentially accelerating atmospheric carbon dioxide growth

    CERN Document Server

    Hüsler, Andreas D

    2011-01-01

    We analyze the growth rates of atmospheric carbon dioxide and human population, by comparing the relative merits of two benchmark models, the exponential law and the finite-time-singular (FTS) power law. The later results from positive feedbacks, either direct or mediated by other dynamical variables, as shown in our presentation of a simple endogenous macroeconomic dynamical growth model. Our empirical calibrations confirm that human population has decelerated from its previous super-exponential growth until 1960 to ``just' an exponential growth, but with no sign of more deceleration. As for atmospheric CO2 content, we find that it is at least exponentially increasing and most likely characterized by an accelerating growth rate as off 2009, consistent with an unsustainable FTS power law regime announcing a drastic change of regime. The coexistence of a quasi-exponential growth of human population with a super-exponential growth of carbon dioxide content in the atmosphere is a diagnostic of insignificant impr...

  12. Knee joint neuromuscular activation performance during muscle damage and superimposed fatigue.

    Science.gov (United States)

    Minshull, Claire; Eston, Roger; Rees, David; Gleeson, Nigel

    2012-01-01

    This study examined the concurrent effects of exercise-induced muscle damage and superimposed acute fatigue on the neuromuscular activation performance of the knee flexors of nine males (age: 26.7 ± 6.1 years; height 1.81 ± 0.05 m; body mass 81.2 ± 11.7 kg [mean±s]). Measures were obtained during three experimental conditions: (i) 'fatigue-muscle damage', involving acute fatiguing exercise performed on each assessment occasion plus a single episode of eccentric exercise performed on the first occasion and after the fatigue trial; (ii) 'fatigue', involving the fatiguing exercise only; and (iii) 'control' consisting of no exercise. Assessments were performed prior to (pre) and at 1 h, 24 h, 48 h, 72 h, and 168 h relative to the muscle damaging eccentric exercise. Repeated-measures analyses of variance (ANOVAs) showed that muscle damage elicited reductions of up to 38%, 24% and 65% in volitional peak force, electromechanical delay and rate of force development compared to baseline and controls, respectively (F ([10, 80]) = 2.3 to 4.6; P exercise.

  13. A case of extra hepatic portal vein obstruction in pregnancy with superimposed pre-eclampsia

    Directory of Open Access Journals (Sweden)

    Bindu Nambisan

    2016-09-01

    Full Text Available Extra hepatic portal vein obstruction in pregnancy poses a clinical challenge by itself. We present here a case of a 19 year old primigravida with EHPVO who developed superimposed preeclampsia. She had a successful maternal and fetal outcome in a tertiary care centre owing to the team effort involving specialists from medical gastroenterology, nephrology, anesthesiology, and neonatology apart from senior obstetrician. EHPVO is an important cause of non-cirrhotic portal hypertension in third world countries. In pregnancy, the increased blood volume and cardiac output and mesenteric vasodilatation will increase portal flow and aggravate portal hypertension in these patients. The resultant hematemesis in such patients, can compromise the perinatal outcome. Endoscopic variceal ligation (EVL reduces the risk of variceal bleeding, and can improve the pregnancy outcome in these women. Thrombocytopenia due to splenomegaly is one of the major complications in these patients and has to be corrected before pregnancy. Platelet transfusion is required intrapartum if the count is less than 50,000/mm3 caesarean delivery is reserved only for obstetric indications. [Int J Reprod Contracept Obstet Gynecol 2016; 5(9.000: 3213-3215

  14. Superimposed Pristine Limestone Aquifers with Marked Hydrochemical Differences Exhibit Distinct Fungal Communities

    Science.gov (United States)

    Nawaz, Ali; Purahong, Witoon; Lehmann, Robert; Herrmann, Martina; Küsel, Kirsten; Totsche, Kai U.; Buscot, François; Wubet, Tesfaye

    2016-01-01

    Fungi are one important group of eukaryotic microorganisms in a diverse range of ecosystems, but their diversity in groundwater ecosystems is largely unknown. We used DNA-based pyro-tag sequencing of the fungal internal transcribed spacer (ITS) rDNA gene to investigate the presence and community structure of fungi at different sampling sites of two superimposed limestone aquifers ranging from 8.5 to 84 m depth in the newly established Hainich Critical Zone Exploratory (Hainich CZE). We detected a diversity of fungal OTUs in groundwater samples of all sampling sites. The relative percentage abundance of Basidiomycota was higher in the upper aquifer assemblage, whilst Ascomycota dominated the lower one. In parallel to differences in the hydrochemistry we found distinct fungal communities at all sampling sites. Classification into functional groups revealed an overwhelming majority of saprotrophs. Finding taxa common to all analyzed groundwater sites, point to a groundwater specific fungal microbiome. The presence of different functional groups and, in particular plant and cattle pathogens that are not typical of subsurface habitats, suggests links between the surface and subsurface biogeosphere due to rapid transportation across the fracture networks typical of karstic regions during recharge episodes. However, further studies including sampling series extended in both time and space are necessary to confirm this hypothesis. PMID:27242696

  15. Dunes morphologies and superimposed bedforms in a cellular automaton dune model

    Science.gov (United States)

    Zhang, D.; Narteau, C.; Rozier, O.; Claudin, P.

    2009-04-01

    We use a new 3D cellular automaton model for bedform dynamics in which individual physical processes such as erosion, deposition and transport are implemented by nearest neighbor interactions and a time-dependent stochastic process. Simultaneously, a lattice gas cellular automaton model is used to compute the flow and quantify the bed shear stress on the topography. Local erosion rates are taken proportional to the shear stress in such a way that there is a complete feedback mechanism between flow and bedform dynamics. In the numerical simulations of dune fields, we observe the formation and the evolution of barchan, transverse, longitudinal and star dunes. For all these types of dunes, we observe the emergence of superimposed bedforms when dunes are large enough. Then, we use the same model under different initial conditions, and we perform the linear stability analysis of a flat sand bed disturbed by a small sinusoidal perturbation. Comparing the most unstable wavelength in the model with the characteristic size of secondary bedforms in nature, we determine the length and time scales of our cellular automaton model. Thus, we establish a link between discrete and continuous approaches and open new perspectives for modeling and quantification of complex patterns in dune fields.

  16. Optimal Superimposed Training Sequences for Channel Estimation in MIMO-OFDM Systems

    Directory of Open Access Journals (Sweden)

    Ratnam V. Raja Kumar

    2010-01-01

    Full Text Available In this work an iterative time domain Least Squares (LS based channel estimation method using superimposed training (ST for a Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM system over time varying frequency selective fading channels is proposed. The performance of the channel estimator is analyzed in terms of the Mean Square Estimation Error (MSEE and its impact on the uncoded Bit Error Rate (BER of the MIMO-OFDM system is studied. A new selection criterion for the training sequences that jointly optimizes the MSEE and the BER of the OFDM system is proposed. Chirp based sequences are proposed and shown to satisfy the same. These are compared with the other sequences proposed in the literature and are found to yield a superior performance. The sequences, one for each transmitting antenna, offers fairness through providing equal interference in all the data carriers unlike earlier proposals. The effectiveness of the mathematical analysis presented is demonstrated through a comparison with the simulation studies. Experimental studies are carried out to study and validate the improved performance of the proposed scheme. The scheme is applied to the IEEE 802.16e OFDM standard and a case is made with the required design of the sequence.

  17. Twisted exponential sums of polynomials in one variable

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The twisted T-adic exponential sums associated to a polynomial in one variable are studied.An explicit arithmetic polygon in terms of the highest two exponents of the polynomial is proved to be a lower bound of the Newton polygon of the C-function of the twisted T-adic exponential sums.This bound gives lower bounds for the Newton polygon of the L-function of twisted p-power order exponential sums.

  18. An Exponential Lower Bound on OBDD Refutations for Pigeonhole Formulas

    CERN Document Server

    Tveretina, Olga; Zantema, Hans

    2009-01-01

    Haken proved that every resolution refutation of the pigeonhole formula has at least exponential size. Groote and Zantema proved that a particular OBDD computation of the pigeonhole formula has an exponential size. Here we show that any arbitrary OBDD refutation of the pigeonhole formula has an exponential size, too: we prove that the size of one of the intermediate OBDDs is at least $\\Omega(1.025^n)$.

  19. Exponential convergence rates for weighted sums in noncommutative probability space

    Science.gov (United States)

    Choi, Byoung Jin; Ji, Un Cig

    2016-11-01

    We study exponential convergence rates for weighted sums of successive independent random variables in a noncommutative probability space of which the weights are in a von Neumann algebra. Then we prove a noncommutative extension of the result for the exponential convergence rate by Baum, Katz and Read. As applications, we first study a large deviation type inequality for weighted sums in a noncommutative probability space, and secondly we study exponential convergence rates for weighted free additive convolution sums of probability measures.

  20. Comparison of different undulator schemes with superimposed alternating gradients for the VUV-FEL at the TESLA Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Pflueger, J.; Nikitina, Y.M. [DESY/HASYLAB, Hamburg (Germany)

    1995-12-31

    For the VUV-FEL at the TESLA Test Facility an undulator with a total length of 30 m is needed. In this study three different approaches to realize an undulator with a sinusoidal plus a superimposed quadrupolar field were studied with the 3D code MAFIA.

  1. The exponential-logarithmic equivalence classes of surreal numbers

    CERN Document Server

    Kuhlmann, Salma

    2012-01-01

    In his monograph, H. Gonshor showed that Conway's real closed field of surreal numbers carries an exponential and logarithmic map. Subsequently, L. van den Dries and P. Ehrlich showed that it is a model of the elementary theory of the field of real numbers with the exponential function. In this paper, we give a complete description of the exponential equivalence classes in the spirit of the classical Archimedean and multiplicative equivalence classes. This description is made in terms of a recursive formula as well as a sign sequence formula for the family of representatives of minimal length of these exponential classes.

  2. Using Differentials to Differentiate Trigonometric and Exponential Functions

    Science.gov (United States)

    Dray, Tevian

    2013-01-01

    Starting from geometric definitions, we show how differentials can be used to differentiate trigonometric and exponential functions without limits, numerical estimates, solutions of differential equations, or integration.

  3. Using Differentials to Differentiate Trigonometric and Exponential Functions

    Science.gov (United States)

    Dray, Tevian

    2013-01-01

    Starting from geometric definitions, we show how differentials can be used to differentiate trigonometric and exponential functions without limits, numerical estimates, solutions of differential equations, or integration.

  4. Exponential sums over primes in short intervals

    Institute of Scientific and Technical Information of China (English)

    LIU; Jianya

    2006-01-01

    [1]Vinogradov,I.M.,Estimation of certain trigonometric sums with prime variables,Izv.Acad.Nauk.SSSR,1939,3:371-398.[2]Zhan,T.,On the representation of large odd integer as a sum of three almost equal primes,Acta Math.Sin.,1991,7:259-272.[3]Ren,X.M.,On exponential sums over primes and application in the Waring-Goldbach problem,Sci.China,Ser.A-Math.,2005,48(6):785-797.[4]Liu,J.Y.,Wooley,T.D.,Yu,G.,The quadratic Waring-Goldbach problem,J.Number Theory,2004,107:298-321.[5]Hua,L.K.,Some results in the additive prime number theory,Quart.J.Math.(Oxford),1938,9:68-80.[6]Liu,J.Y.,Zhan,T.,On sums of five almost equal prime squares,Acta Arith.,1996,77:369-383.[7]Bauer,C.,A note on sums of five almost equal prime squares,Arch.Math,1997,69:20-30.[8]Liu,J.Y.,Zhan,T.,Sums of five almost equal prime squares,Science in China,Ser.A,1998,41:710-722.[9]Liu,J.Y.,Zhan,T.,Hua's theorem on prime squares in short intervals,Acta Math.Sin.,2000,16:1-22.[10]Bauer,C.,Sums of five almost equal prime squares,Acta Math.Sin.,2005,21(4):833-840.[11]Lü,G.S.,Hua's Theorem with five almost equal prime variables,Chin.Ann.Math.,Ser.B,2005,26(2):291-304.[12]Vinogradov,I.M.,Elements of Number Theory,Dover Publications,1954.[13]Titchmarsh,E.C.,The Theory of the Riemann Zeta-function,2nd ed.,Oxford:Oxford University Press,1986.

  5. Insufficiencies of the Single Exponential Model and Efficiency of the Double Exponential Model in the Optimization of Solar Cells Efficiency

    OpenAIRE

    A. Zerga; B. Benyoucef; J.-P. Charles

    1998-01-01

    Single and double exponential models are confronted to determine the most adapted model for optimization of solar cells efficiency. It is shown that the single exponential model (SEM) presents some insufficiencies for efficiency optimization. The interest of the double exponential model to optimize the efficiency and to achieve an adequate simulation of the operation of solar cells is demonstrated by means of I-V characteristics plotting.

  6. Poly-phase salt tectonics and hydrocarbon accumulation in Tarim superimposed basin, northwest China

    Institute of Scientific and Technical Information of China (English)

    TANG Liangjie; JIN Zhijun; JlA Chengzao; PI Xuejun; CHEN Suping

    2004-01-01

    The purpose of this paper is to discuss the poly-phase salt tectonics and its relation to the hydrocarbon accumulation of the Tarim superimposed basin. Several salt sequences are developed in the Tarim basin, they are: (1) the Mid-Early Cambrian salt sequence, mainly distributed in the west part of the north Tarim uplift and Keping uplift; (2) the Early Carboniferous salt sequence, mainly distributed in the south slope of the north Tarim uplift; (3) the Paleogene salt sequence, mainly distributed in the mid-west part of the Kuqa foreland fold belt and north Tarim uplift; and (4) the Miocene salt sequence, mainly distributed in the east part of the Kuqa foreland fold belt. The salt sequences deposited in the tectonically calm scenario, while the salt layers deformed during the period of intense tectonism. Although the salt sequences are characteristic of plastic flow, the differences of salt deformation styles exist in the different salt sequences because of the different deformation mechanism. It is attractive that the distribution of the large oil-gas fields or pools has a bearing upon the salt sequences and salt structures, such as the Tahe oilfield related to the Lower Carboniferous salt sequence and laterally facies changed mudstone, the Kela No.2 gas field to the Paleogene salt structures, and the Dina gas field to the Miocene salt structures. It is indicated that the large-scale hydrocarbon accumulation is controlled by the poly-phase salt sequences and structures. The deep analysis of the poly-phase salt tectonics is helpful to understanding the characteristics of the structural deformation and oil-gas accumulation of the Tarim basin.

  7. [Tubeless superimposed high frequency jet ventilation in high grade laryngeal stenoses].

    Science.gov (United States)

    Aloy, A; Kimla, T; Schragl, E; Donner, A; Grasl, M

    1994-08-01

    Massive stenosis of the larynx may present a potentially life-threatening situation for the patient, requiring immediate measures to ensure a patient's airway. The aim of this prospective study was to evaluate potential benefits of Superimposed High Frequency Jet Ventilation (SHFJV) in patients requiring microlaryngeal surgery due to massive stenosis of the larynx. 23 patients (age range 1.5 to 90 years) with laryngeal stenosis grade 2 and 3 according to the Cotton scale were ventilated using SHFJV. The duration of the SHFJV was 12 to 116 minutes. SHFJV was performed using a Bronchotron Respirator via a jet-laryngoscope. Arterial blood gases demonstrated paO2 between 71 and 295 mmHg and paCO2 of 28 to 81 mmHg. The mean FiO2 applied was 61.75 +/- 19.26. The airway pressure was measured at the tip of the jet-laryngoscope and was between 6 and 15 mmHg, and PEEP was 1 to 5 mmHg. In 13 patients a CO2 laser was utilised during surgery. In all patients SHFJV was performed without problems. Since the ventilation is delivered above any possible stenosis the danger of barotrauma is minimised. The surgeon obtains optimal visibility of the larynx and is not obstructed in the surgical procedure. SHFJV enables both the surgeon and the anesthetist to perform their respective duties and therefore increases the safety of the patient in the management of such a difficult problem as massive stenosis of the larynx.

  8. Incidence and pregnancy outcomes of superimposed preeclampsia with or without proteinuria among women with chronic hypertension.

    Science.gov (United States)

    Nakanishi, Sayuri; Aoki, Shigeru; Nagashima, Ami; Seki, Kazuo

    2017-01-01

    To investigate the incidence and pregnancy outcomes of superimposed preeclampsia (PE) with or without proteinuria among women with chronic hypertension. This retrospective study included 142 women with essential hypertension diagnosed at ⩽20weeks of gestation, managed at a tertiary center. They were divided into three groups (non-PE, PE with proteinuria, and PE without proteinuria) to compare pregnancy outcomes. The non-PE group was further divided into two subgroups (controlled and uncontrolled hypertension). There were 87 women in the non-PE group, 47 in the PE with proteinuria group, and 8 in the PE without proteinuria group. Median gestational age at delivery was 38.7weeks in the non-PE group, 30.4 in the PE with proteinuria group, and 28.4 in the PE without proteinuria group. In three of the women in the PE without proteinuria group, the diagnostic criteria were fulfilled by liver involvement (complicated by thrombocytopenia in one woman). The remaining five women had uteroplacental dysfunction. The 87 women in the non-PE group were divided into a controlled hypertension subgroup of 75 women and uncontrolled hypertension subgroup of 12. The median gestational age at delivery was 39.1weeks in the controlled HT subgroup and 34.1weeks in the uncontrolled hypertension subgroup. The pregnancy outcomes were significantly poorer in the latter group. Pregnancy outcomes were unfavorable in both the PE without proteinuria and PE with proteinuria groups. Women with non-PE uncontrolled hypertension also had poor pregnancy outcomes, although their outcomes were better than those of women with PE. Copyright © 2017 International Society for the Study of Hypertension in Pregnancy. Published by Elsevier B.V. All rights reserved.

  9. Alteration and Reformation of Hydrocarbon Reservoirs and Prediction of Remaining Potential Resources in Superimposed Basins

    Institute of Scientific and Technical Information of China (English)

    PANG Hong; PANG Xiongqi; YANG Haijun; LIN Changsong; MENG Qingyang; WANG Huaijie

    2010-01-01

    Complex hydrocarbon reservoirs developed widely in the superimposed basins of China formed from multiple structural alterations,reformation and destruction of hydrocarbon reservoirs formed at early stages.They are characterized currently by trap adjustment,component variation,phase conversion,and scale reformation.This is significant for guiding current hydrocarbon exploration by revealing evolution mechanisms after hydrocarbon reservoir formation and for predicting remaining potential resources.Based on the analysis of a number of complex hydrocarbon reservoirs,there are four geologic features controlling the degree of destruction of hydrocarbon reservoirs formed at early stages:tectonic event intensity,frequency,time and caprock sealing for oil and gas during tectonic evolution.Research shows that the larger the tectonic event intensity,the more frequent the tectonic event,the later the last tectonic event,the weaker the caprock sealing for oil and gas,and the greater the volume of destroyed hydrocarbons in the early stages.Based on research on the main controlling factors of hydrocarbon reservoir destruction mechanisms,a geological model of tectonic superimposition and a mathematical model evaluating potential remaining complex hydrocarbon reservoirs have been established.The predication method and technical procedures were applied in the Tazhong area of Tarim Basin,where four stages of hydrocarbon accumulation and three stages of hydrocarbon alteration occurred.Geohistorical hydrocarbon accumulation reached 3.184billion tons,of which 1.271 billion tons were destroyed.The total volume of remaining resources available for exploration is~1.9 billion tons.

  10. A New Catalogue of Fine Structures Superimposed on Solar Microwave Bursts

    Institute of Scientific and Technical Information of China (English)

    Qi-Jun Fu; Yi-Hua Yan; Yu-Ying Liu; Min Wang; Shu-Juan Wang

    2004-01-01

    The 2.6-3.8 GHz, 4.5-7.5 GHz, 5.2-7.6 GHz and 0.7-1.5 GHz component spectrometers of Solar Broadband Radio Spectrometer (SBRS) started routine observations, respectively, in late August 1996, August 1999, August 1999, and June 2000. They just managed to catch the coming 23rd solar active maximum. Consequently, a large amount of microwave burst data with high temporal and high spectral resolution and high sensitivity were obtained. A variety of fine structures (FS)superimposed on microwave bursts have been found. Some of them are known, such as microwave type Ⅲ bursts, microwave spike emission, but these were observed with more detail; some are new. Reported for the first time here are microwave type U bursts with similar spectral morphology to those in decimetric and metric wavelengths, and with outstanding characteristics such as very short durations(tens to hundreds ms), narrow bandwidths, higher frequency drift rates and higher degrees of polarization. Type N and type M bursts were also observed. Detailed zebra pattern and fiber bursts at the high frequency were found. Drifting pulsation structure (DPS) phenomena closely associated with CME are considered to manifest the initial phase of the CME, and quasi-periodic pulsation with periods of tens ms have been recorded. Microwave "patches", unlike those reported previously, were observed with very short durations (about 300 ms), very high flux densities (up to 1000 sfu), very high polarization (about 100% RCP), extremely narrow bandwidths(about 5%), and very high spectral indexes. These cannot be interpreted with the gyrosynchrotron process. A superfine structure in the form of microwave FS (ZPS,type U), consisting of microwave millisecond spike emission (MMS), was also found.

  11. Augmented vascular smooth muscle cell stiffness and adhesion when hypertension is superimposed on aging.

    Science.gov (United States)

    Sehgel, Nancy L; Sun, Zhe; Hong, Zhongkui; Hunter, William C; Hill, Michael A; Vatner, Dorothy E; Vatner, Stephen F; Meininger, Gerald A

    2015-02-01

    Hypertension and aging are both recognized to increase aortic stiffness, but their interactions are not completely understood. Most previous studies have attributed increased aortic stiffness to changes in extracellular matrix proteins that alter the mechanical properties of the vascular wall. Alternatively, we hypothesized that a significant component of increased vascular stiffness in hypertension is due to changes in the mechanical and adhesive properties of vascular smooth muscle cells, and that aging would augment the contribution from vascular smooth muscle cells when compared with the extracellular matrix. Accordingly, we studied aortic stiffness in young (16-week-old) and old (64-week-old) spontaneously hypertensive rats and Wistar-Kyoto wild-type controls. Systolic and pulse pressures were significantly increased in young spontaneously hypertensive rats when compared with young Wistar-Kyoto rats, and these continued to rise in old spontaneously hypertensive rats when compared with age-matched controls. Excised aortic ring segments exhibited significantly greater elastic moduli in both young and old spontaneously hypertensive rats versus Wistar-Kyoto rats. were isolated from the thoracic aorta, and stiffness and adhesion to fibronectin were measured by atomic force microscopy. Hypertension increased both vascular smooth muscle cell stiffness and vascular smooth muscle cell adhesion, and these increases were both augmented with aging. By contrast, hypertension did not affect histological measures of aortic collagen and elastin, which were predominantly changed by aging. These findings support the concept that stiffness and adhesive properties of vascular smooth muscle cells are novel mechanisms contributing to the increased aortic stiffness occurring with hypertension superimposed on aging.

  12. Stretched exponential relaxation of piezovoltages in wet bovine bone.

    Science.gov (United States)

    Xu, Lianyun; Hou, Zhende; Fu, Donghui; Qin, Qing-Hua; Wang, Yihan

    2015-01-01

    It is important to determine the amplitude and variation characteristics of piezovoltage in wet bone, which can, in turn, be taken as a basis for studying whether electrical signals induced by external forces can affect the growth of bone cells. This work measured the characteristics of piezoelectric effects under dynamic and static loading. The results show that the variations of piezovoltage in wet bone in both loading and load holding periods follow a stretched exponential relaxation law, and the relaxation time constants of the piezovoltages are much larger than those of dry bone. This finding means that the active time of piezovoltage in wet bone is much longer than that of dry bone. Regardless of the loading and load holding processes, continuously increasing deformation in wet bone caused piezoelectric charges to be continuously induced and increased the dielectric constant of wet bone along with the deformation process. In general, compared with piezovoltage in dry bone, that in wet bone had lower amplitude and could exist for a longer duration. It can be inferred, therefore, that piezoelectricity might create coupling with the streaming potential in bone by changing the thickness of the double electrode layer. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Exponential Correlation of IQ and the Wealth of Nations

    Science.gov (United States)

    Dickerson, Richard E.

    2006-01-01

    Plots of mean IQ and per capita real Gross Domestic Product for groups of 81 and 185 nations, as collected by Lynn and Vanhanen, are best fitted by an exponential function of the form: GDP = "a" * 10["b"*(IQ)], where "a" and "b" are empirical constants. Exponential fitting yields markedly higher correlation coefficients than either linear or…

  14. A Learning Cycle on Exponential Growth and the Energy Crises.

    Science.gov (United States)

    Dykstra, D. I., Jr.

    1982-01-01

    Describes nature and logistics of a learning cycle approach to teaching exponential growth and the energy crisis. Used with both science and nonscience majors, the cycle uses no algebra, never mentions the terms exponential or logarithmic, and requires a calculator. Instructions for obtaining student and instructor materials are provided.…

  15. Exponential Shear Flow of Linear, Entangled Polymeric Liquids

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Park, Kyungho; Venerus, David C.

    2000-01-01

    A previously proposed reptation model is used to interpret exponential shear flow data taken on an entangled polystyrenesolution. Both shear and normal stress measurements are made during exponential shear using mechanical means. The model iscapable of explaining all trends seen in the data, and ...

  16. Molecular integrals for exponential-type orbitals using hyperspherical harmonics

    DEFF Research Database (Denmark)

    Avery, James Emil; Avery, John Scales

    2015-01-01

    Exponential-type orbitals are better suited to calculations of molecular electronic structure than are Gaussians, since ETO's can accurately represent the behavior of molecular orbitals near to atomic nuclei, as well as their long-distance exponential decay. Orbitals based on Gaussians fail in bo...

  17. A nomogram for deconvolution of single exponential fluorescence decays.

    OpenAIRE

    Rockley, M.G.

    1980-01-01

    An extremely rapid technique for deconvolving single exponential luminescence decay data is described that involves essentially no mathematical manipulation of the experimental data. The method permits "real time" measurement of deconvolved luminescence lifetimes with conventional pulsed, lifetime-fluorometers and phosphorimeters. The method assumes that the true luminescence decay of the chromophore is accurately represented by a single exponential decay function.

  18. Residual, restarting and Richardson iteration for the matrix exponential

    NARCIS (Netherlands)

    Botchev, M.A.

    2010-01-01

    A well-known problem in computing some matrix functions iteratively is a lack of a clear, commonly accepted residual notion. An important matrix function for which this is the case is the matrix exponential. Assume, the matrix exponential of a given matrix times a given vector has to be computed.

  19. Residual, restarting and Richardson iteration for the matrix exponential

    NARCIS (Netherlands)

    Botchev, Mike A.; Grimm, Volker; Hochbruck, Marlis

    2013-01-01

    A well-known problem in computing some matrix functions iteratively is the lack of a clear, commonly accepted residual notion. An important matrix function for which this is the case is the matrix exponential. Suppose the matrix exponential of a given matrix times a given vector has to be computed.

  20. Exponential Decay of Correlations for the Strongly Coupled Toom Model

    CERN Document Server

    de Maere, Augustin

    2011-01-01

    We prove that, for the two-dimensional probabilistic cellular automaton of Toom in the low-noise regime, there are two classes of initial measures, each of which converges exponentially fast toward one of the two natural invariant measures. We also show that these two invariant measures have exponential decay of correlations in space and in time and are strongly mixing.

  1. Exponential B-splines and the partition of unity property

    DEFF Research Database (Denmark)

    Christensen, Ole; Massopust, Peter

    2012-01-01

    We provide an explicit formula for a large class of exponential B-splines. Also, we characterize the cases where the integer-translates of an exponential B-spline form a partition of unity up to a multiplicative constant. As an application of this result we construct explicitly given pairs of dual...

  2. Review of "Going Exponential: Growing the Charter School Sector's Best"

    Science.gov (United States)

    Garcia, David

    2011-01-01

    This Progressive Policy Institute report argues that charter schools should be expanded rapidly and exponentially. Citing exponential growth organizations, such as Starbucks and Apple, as well as the rapid growth of molds, viruses and cancers, the report advocates for similar growth models for charter schools. However, there is no explanation of…

  3. Delirium Superimposed on Dementia Strongly Predicts Worse Outcomes in Older Rehabilitation Inpatients

    Science.gov (United States)

    Morandi, Alessandro; Davis, Daniel; Fick, Donna M.; Turco, Renato; Boustani, Malaz; Lucchi, Elena; Guerini, Fabio; Morghen, Sara; Torpilliesi, Tiziana; Gentile, Simona; MacLullich, Alasdair M.; Trabucchi, Marco; Bellelli, Giuseppe

    2014-01-01

    Objective Delirium superimposed on dementia (DSD) is common in many settings. Nonetheless, little is known about the association between DSD and clinical outcomes. The study aim was to evaluate the association between DSD and related adverse outcomes at discharge from rehabilitation and at 1-year follow-up in older inpatients undergoing rehabilitation. Design Prospective cohort study. Setting Hospital rehabilitation unit. Participants A total of 2642 patients aged 65 years or older admitted between January 2002 and December 2006. Measurements Dementia predating rehabilitation admission was detected by DSM-III-R criteria. Delirium was diagnosed with the DSM-IV-TR. The primary outcome was that of walking dependence (Barthel Index mobility subitem score of <15) captured as a trajectory from discharge to 1-year follow-up. A mixed-effects multivariate logistic regression model was used to analyze the association between DSD and outcome, after adjusting for relevant covariates. Secondary outcomes were institutionalization and mortality at 1-year follow-up, and logistic regression models were used to analyze these associations. Results The median age was 77 years (interquartile range: 71–83). The prevalence of DSD was 8%, and the prevalence of delirium and dementia alone were 4% and 22%, respectively. DSD at admission was found to be significantly associated with almost a 15-fold increase in the odds of walking dependence (odds ratio [OR] 15.5; 95% Confidence Interval [CI] 5.6–42.7; P < .01). DSD was also significantly associated with a fivefold increase in the risk of institutionalization (OR 5.0; 95% CI 2.8–8.9; P < .01) and an almost twofold increase in the risk of mortality (OR 1.8; 95% CI 1.1–2.8; P = .01). Conclusions DSD is a strong predictor of functional dependence, institutionalization, and mortality in older patients admitted to a rehabilitation setting, suggesting that strategies to detect DSD routinely in practice should be developed and DSD should

  4. Superimposed epitopes restricted by the same HLA molecule drive distinct HIV-specific CD8+ T cell repertoires.

    Science.gov (United States)

    Sun, Xiaoming; Fujiwara, Mamoru; Shi, Yi; Kuse, Nozomi; Gatanaga, Hiroyuki; Appay, Victor; Gao, George F; Oka, Shinichi; Takiguchi, Masafumi

    2014-07-01

    Superimposed epitopes, in which a shorter epitope is embedded within a longer one, can be presented by the same HLA class I molecule. CD8(+) CTL responses against such epitopes and the contribution of this phenomenon to immune control are poorly characterized. In this study, we examined HLA-A*24:02-restricted CTLs specific for the superimposed HIV Nef epitopes RYPLTFGWCF (RF10) and RYPLTFGW (RW8). Unexpectedly, RF10-specific and RW8-specific CTLs from HIV-1-infected HLA-A*24:02+ individuals had no overlapping Ag reactivity or clonotypic compositions. Single-cell TCR sequence analyses demonstrated that RF10-specific T cells had a more diverse TCR repertoire than did RW8-specific T cells. Furthermore, RF10-specific CTLs presented a higher Ag sensitivity and HIV suppressive capacity compared with RW8-specific CTLs. Crystallographic analyses revealed important structural differences between RF10- and RW8-HLA-A*24:02 complexes as well, with featured and featureless conformations, respectively, providing an explanation for the induction of distinct T cell responses against these epitopes. The present study shows that a single viral sequence containing superimposed epitopes restricted by the same HLA molecule could elicit distinct CD8+ T cell responses, therefore enhancing the control of HIV replication. This study also showed that a featured epitope (e.g., RF10) could drive the induction of T cells with high TCR diversity and affinity. Copyright © 2014 by The American Association of Immunologists, Inc.

  5. Performance Comparison between Nonidentical Segmented Exponential Concave and Nonidentical Segmented Exponential Convex Serrated CATRs

    Directory of Open Access Journals (Sweden)

    T. Venkata Rama Krishna

    2008-01-01

    Full Text Available This paper presented a theoretical and numerical assessment for nonidentical segmented exponential- (NISE- convex and NISE-concave serrated plane CATRs by changing number of serrations. The investigation was based on diffraction theory and, more specifically, on the diffraction formulation of Fresnel. The compact antenna test range (CATR provides uniform illumination within the Fresnel region to the test antenna. Application of serrated edges has been shown to be a good method to control diffraction at the edges of the reflectors. In this paper, the Fresnel fields of NISE-convex and NISE-concave serrated CATRs are analyzed using physical optics (PO technique. The PO analysis is applied in this paper for plane reflector serrated CATR only. The same analysis is applied to any type of reflector. In this paper, lens-based reflector is not considered. It is observed that NISE-concave serrated CATR gives less ripple and enhanced quiet zone width than NISE-convex.

  6. Laminar phase flow for an exponentially tapered Josephson oscillator

    DEFF Research Database (Denmark)

    Benabdallah, A.; Caputo, J. G.; Scott, Alwyn C.

    2000-01-01

    Exponential tapering and inhomogeneous current feed were recently proposed as means to improve the performance of a Josephson flux flow oscillator. Extensive numerical results backed up by analysis are presented here that support this claim and demonstrate that exponential tapering reduces...... the small current instability region and leads to a laminar flow regime where the voltage wave form is periodic giving the oscillator minimal spectral width. Tapering also leads to an increased output power. Since exponential tapering is not expected to increase the difficulty of fabricating a flux flow...

  7. A modified exponential model for reported death toll during earthquakes

    Institute of Scientific and Technical Information of China (English)

    Xinyan Wu; Jianhua Gu

    2009-01-01

    Reliable earthquake death toll estimate can provide valuable references for disaster relief headquarters and civil administration departments to make arrangement and deployment plan during post-earthquake relief work, thus increasing the efficiency of the relief work to a certain extent. In this study, we acquired the death toll data of Wenchuan earthquake, fitted the data using modified exponential curve and compared the result with that of the exponential function. Experimental verification with Chi-Chi earthquake and Kobe earthquake data shows that the fitted result by modified exponential curve is more satisfactory. The final death toll resulting from future destructive earthquakes can be estimated by the acquired fitting function.

  8. Processing Music Signals Using Audio Decomposition Techniques

    OpenAIRE

    Driedger, Jonathan

    2016-01-01

    Music signals are complex. When musicians play together, their instruments' sounds superimpose and form a single complex sound mixture. Furthermore, even the sound of a single instrument may already comprise sound components of harmonic, percussive, noise-like, and transient nature, among others. The complexity of music signal processing tasks such as time-scale modifcation - the task of stretching or compressing the duration of a music signal - or music source separation - the...

  9. Domain decomposition, multi-level integration and exponential noise reduction in lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Ce, Marco [Scuola Normale Superiore, Pisa (Italy); INFN, Sezione di Pisa (Italy); Giusti, Leonardo [Univ. di Milano-Bicocca (Italy). Dipt. di Fisica; INFN, Sezione di Milano-Bicocca (Italy); Schaefer, Stefan [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2016-01-15

    We explore the possibility of computing fermionic correlators on the lattice by combining a domain decomposition with a multi-level integration scheme. The quark propagator is expanded in series of terms with a well defined hierarchical structure. The higher the order of a term, the (exponentially) smaller its magnitude, the less local is its dependence on the gauge field. Once inserted in a Wick contraction, the gauge-field dependence of the terms in the resulting series can be factorized so that it is suitable for multi-level Monte Carlo integration. We test the strategy in quenched QCD by computing the disconnected correlator of two flavor-diagonal pseudoscalar densities, and a nucleon two-point function. In either cases we observe a significant exponential increase of the signal-to-noise ratio.

  10. Effects of Exponential Trends on Correlations of Stock Markets

    Directory of Open Access Journals (Sweden)

    Ai-Jing Lin

    2014-01-01

    Full Text Available Detrended fluctuation analysis (DFA is a scaling analysis method used to estimate long-range power-law correlation exponents in time series. In this paper, DFA is employed to discuss the long-range correlations of stock market. The effects of exponential trends on correlations of Hang Seng Index (HSI are investigated with emphasis. We find that the long-range correlations and the positions of the crossovers of lower order DFA appear to have no immunity to the additive exponential trends. Further, our analysis suggests that an increase in the DFA order increases the efficiency of eliminating on exponential trends. In addition, the empirical study shows that the correlations and crossovers are associated with DFA order and magnitude of exponential trends.

  11. Asymptotic expansions of Feynman integrals of exponentials with polynomial exponent

    Science.gov (United States)

    Kravtseva, A. K.; Smolyanov, O. G.; Shavgulidze, E. T.

    2016-10-01

    In the paper, an asymptotic expansion of path integrals of functionals having exponential form with polynomials in the exponent is constructed. The definition of the path integral in the sense of analytic continuation is considered.

  12. Exponential Stability of Stochastic Nonlinear Dynamical Price System with Delay

    Directory of Open Access Journals (Sweden)

    Wenli Zhu

    2013-01-01

    Full Text Available Based on Lyapunov stability theory, Itô formula, stochastic analysis, and matrix theory, we study the exponential stability of the stochastic nonlinear dynamical price system. Using Taylor's theorem, the stochastic nonlinear system with delay is reduced to an n-dimensional semilinear stochastic differential equation with delay. Some sufficient conditions of exponential stability and corollaries for such price system are established by virtue of Lyapunov function. The time delay upper limit is solved by using our theoretical results when the system is exponentially stable. Our theoretical results show that if the classical price Rayleigh equation is exponentially stable, so is its perturbed system with delay provided that both the time delay and the intensity of perturbations are small enough. Two examples are presented to illustrate our results.

  13. Super-Exponential Solution for a Retrial Supermarket Model

    CERN Document Server

    Li, Quan-Lin; Wang, Yang

    2011-01-01

    In this paper, we provide a new and effective approach for studying super-exponential solution of a retrial supermarket model with Poisson arrivals, exponential service times and exponential retrial times and with two different probing-server numbers. We describe the retrial supermarket model as a system of differential equations by means of density-dependent jump Markov processes, and obtain an iterative algorithm for computing the fixed point of the system of differential equations. Based on the fixed point, we analyze the expected sojourn time that a tagged arriving customer spends in this system, and use numerical examples to indicate different influence of the two probing-server numbers on system performance including the fixed point and the expected sojourn time. Furthermore, we analyze exponential convergence of the current location of the retrial supermarket model to the fixed point, and apply the Kurtz Theorem to study density-dependent jump Markov process given in the retrial supermarket model, whic...

  14. Construction of extended exponential general linear methods 524 ...

    African Journals Online (AJOL)

    Construction of extended exponential general linear methods 524 for solving semi-linear problems. ... Journal Home > Vol 13, No 2 (2014) > ... This paper introduces a new approach for constructing higher order of EEGLM which have become ...

  15. Combinatorial polynomials as moments, Hankel transforms and exponential Riordan arrays

    CERN Document Server

    Barry, Paul

    2011-01-01

    In the case of two combinatorial polynomials, we show that they can exhibited as moments of paramaterized families of orthogonal polynomials, and hence derive their Hankel transforms. Exponential Riordan arrays are the main vehicles used for this.

  16. The true quantum face of the "exponential" decay law

    CERN Document Server

    Urbanowski, K

    2016-01-01

    Results of theoretical studies of the quantum unstable systems caused that there are rather widespread belief that a universal feature od the quantum decay process is the presence of three time regimes of the decay process: the early time (initial) leading to the Quantum Zeno (or Anti Zeno) Effects, "exponential" (or "canonical") described by the decay law of the exponential form, and late time characterized by the decay law having inverse--power law form. Based on the fundamental principles of the quantum theory we give the proof that there is no time interval in which the survival probability (decay law) could be a decreasing function of time of the purely exponential form but even at the "exponential" regime the decay curve is oscillatory modulated with a smaller or a large amplitude of oscillations depending on parameters of the model considered.

  17. True quantum face of the "exponential" decay law

    Science.gov (United States)

    Urbanowski, Krzysztof

    2017-05-01

    Results of theoretical studies of the quantum unstable systems caused that there are rather widespread belief that a universal feature of the quantum decay process is the presence of three time regimes of the decay process: the early time (initial) leading to the Quantum Zeno (or Anti Zeno) Effects, "exponential" (or "canonical") described by the decay law of the exponential form, and late time characterized by the decay law having inverse-power law form. Based on the fundamental principles of the quantum theory we give the proof that there is no time interval in which the survival probability (decay law) could be a decreasing function of time of the purely exponential form but even at the "exponential" regime the decay curve is oscillatory modulated with a smaller or a large amplitude of oscillations depending on parameters of the model considered.

  18. Uniformly Exponential Growth and Mapping Class Groups of Surfaces

    OpenAIRE

    Anderson, J. W.; Aramayona, J.; Shackleton, K.J.

    2005-01-01

    We show that the mapping class group (as well as closely related groups) of an orientable surface with finitely generated fundamental group has uniformly exponential growth. We further demonstrate the uniformly non-amenability of many of these groups.

  19. Boundary value problems for partial differential equations with exponential dichotomies

    Science.gov (United States)

    Laederich, Stephane

    We are extending the notion of exponential dichotomies to partial differential evolution equations on the n-torus. This allows us to give some simple geometric criteria for the existence of solutions to certain nonlinear Dirichlet boundary value problems.

  20. Heterogeneous Highly Parallel Implementation of Matrix Exponentiation Using GPU

    CERN Document Server

    Raja, Chittampally Vasanth; Raghavendra, Prakash S; 10.5121/ijdps.2012.3209

    2012-01-01

    The vision of super computer at every desk can be realized by powerful and highly parallel CPUs or GPUs or APUs. Graphics processors once specialized for the graphics applications only, are now used for the highly computational intensive general purpose applications. Very expensive GFLOPs and TFLOP performance has become very cheap with the GPGPUs. Current work focuses mainly on the highly parallel implementation of Matrix Exponentiation. Matrix Exponentiation is widely used in many areas of scientific community ranging from highly critical flight, CAD simulations to financial, statistical applications. Proposed solution for Matrix Exponentiation uses OpenCL for exploiting the hyper parallelism offered by the many core GPGPUs. It employs many general GPU optimizations and architectural specific optimizations. This experimentation covers the optimizations targeted specific to the Scientific Graphics cards (Tesla-C2050). Heterogeneous Highly Parallel Matrix Exponentiation method has been tested for matrices of ...

  1. Association between delirium superimposed on dementia and mortality in hospitalized older adults: A prospective cohort study

    Science.gov (United States)

    Curiati, Jose A. E.; Jacob-Filho, Wilson

    2017-01-01

    Background Hospitalized older adults with preexisting dementia have increased risk of having delirium, but little is known regarding the effect of delirium superimposed on dementia (DSD) on the outcomes of these patients. Our aim was to investigate the association between DSD and hospital mortality and 12-mo mortality in hospitalized older adults. Methods and findings This was a prospective cohort study completed in the geriatric ward of a university hospital in São Paulo, Brazil. We included 1,409 hospitalizations of acutely ill patients aged 60 y and over from January 2009 to June 2015. Main variables and measures included dementia and dementia severity (Informant Questionnaire on Cognitive Decline in the Elderly, Clinical Dementia Rating) and delirium (Confusion Assessment Method). Primary outcomes were time to death in the hospital and time to death in 12 mo (for the discharged sample). Comprehensive geriatric assessment was performed at admission, and additional clinical data were documented upon death or discharge. Cases were categorized into four groups (no delirium or dementia, dementia alone, delirium alone, and DSD). The no delirium/dementia group was defined as the referent category for comparisons, and multivariate analyses were performed using Cox proportional hazards models adjusted for possible confounders (sociodemographic information, medical history and physical examination data, functional and nutritional status, polypharmacy, and laboratory covariates). Overall, 61% were women and 39% had dementia, with a mean age of 80 y. Dementia alone was observed in 13% of the cases, with delirium alone in 21% and DSD in 26% of the cases. In-hospital mortality was 8% for patients without delirium or dementia, 12% for patients with dementia alone, 29% for patients with delirium alone, and 32% for DSD patients (Pearson Chi-square = 112, p < 0.001). DSD and delirium alone were independently associated with in-hospital mortality, with respective hazard ratios

  2. Bivariate copulas on the exponentially weighted moving average control chart

    Directory of Open Access Journals (Sweden)

    Sasigarn Kuvattana

    2016-10-01

    Full Text Available This paper proposes four types of copulas on the Exponentially Weighted Moving Average (EWMA control chart when observations are from an exponential distribution using a Monte Carlo simulation approach. The performance of the control chart is based on the Average Run Length (ARL which is compared for each copula. Copula functions for specifying dependence between random variables are used and measured by Kendall’s tau. The results show that the Normal copula can be used for almost all shifts.

  3. Algebraic and transcendental solutions of some exponential equations

    CERN Document Server

    Sondow, Jonathan

    2011-01-01

    We study algebraic and transcendental powers of positive real numbers, including solutions of each of the equations $x^x=y$, $x^y=y^x$, $x^x=y^y$, $x^y=y$, and $x^{x^y}=y$. Applications to values of the iterated exponential functions are given. The main tools used are classical theorems of Hermite-Lindemann and Gelfond-Schneider, together with solutions of exponential Diophantine equations.

  4. EXPODE -- Advanced Exponential Time Integration Toolbox for MATLAB

    OpenAIRE

    2014-01-01

    We present a MATLAB toolbox for five different classes of exponential integrators for solving (mildly) stiff ordinary differential equations or time-dependent partial differential equations. For the efficiency of such exponential integrators it is essential to approximate the products of the matrix functions arising in these integrators with vectors in a stable, reliable and efficient way. The toolbox contains options for computing the matrix functions directly by diagonalization or by Pade a...

  5. AN ANALYTICAL SOLUTION FOR AN EXPONENTIAL TYPE DISPERSION PROCESS

    Institute of Scientific and Technical Information of China (English)

    王子亭

    2001-01-01

    The dispersion process in heterogeneous porous media is distance-dependent,which results from multi-scaling property of heterogeneous structure. An analytical model describing the dispersion with an exponential dispersion function is built, which is transformed into ODE problem with variable coefficients, and obtained analytical solution for two type boundary conditions using hypergeometric function and inversion technique.According to the analytical solution and computing results the difference between the exponential dispersion and constant dispersion process is analyzed.

  6. Confronting quasi-exponential inflation with WMAP seven

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Barun Kumar; Pal, Supratik; Basu, B., E-mail: barunp1985@rediffmail.com, E-mail: pal@th.physik.uni-bonn.de, E-mail: banasri@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 B.T. Road, Kolkata 700 108 (India)

    2012-04-01

    We confront quasi-exponential models of inflation with WMAP seven years dataset using Hamilton Jacobi formalism. With a phenomenological Hubble parameter, representing quasi exponential inflation, we develop the formalism and subject the analysis to confrontation with WMAP seven using the publicly available code CAMB. The observable parameters are found to fair extremely well with WMAP seven. We also obtain a ratio of tensor to scalar amplitudes which may be detectable in PLANCK.

  7. Exponential order statistic models of software reliability growth

    Science.gov (United States)

    Miller, D. R.

    1986-01-01

    Failure times of a software reliability growth process are modeled as order statistics of independent, nonidentically distributed exponential random variables. The Jelinsky-Moranda, Goel-Okumoto, Littlewood, Musa-Okumoto Logarithmic, and Power Law models are all special cases of Exponential Order Statistic Models, but there are many additional examples also. Various characterizations, properties and examples of this class of models are developed and presented.

  8. FTEC: a coalescent simulator for modeling faster than exponential growth

    OpenAIRE

    Reppell, Mark; Boehnke, Michael; Zöllner, Sebastian

    2012-01-01

    Summary: Recent genetic studies as well as recorded history point to massive growth in human population sizes during the recent past. To model and understand this growth accurately we introduce FTEC, an easy-to-use coalescent simulation program capable of simulating haplotype samples drawn from a population that has undergone faster than exponential growth. Samples drawn from a population that has undergone faster than exponential growth show an excess of very rare variation and more rapid LD...

  9. Demonstration of the exponential decay law using beer froth

    Energy Technology Data Exchange (ETDEWEB)

    Leike, A. [Ludwig-Maximilians-Universitaet, Sektion Physik, Munich (Germany)]. E-mail: leike@theorie.physik.uni-muenchen.de

    2002-01-01

    The volume of beer froth decays exponentially with time. This property is used to demonstrate the exponential decay law in the classroom. The decay constant depends on the type of beer and can be used to differentiate between different beers. The analysis shows in a transparent way the techniques of data analysis commonly used in science - consistency checks of theoretical models with the data, parameter estimation and determination of confidence intervals. (author)

  10. The extracellular proteome of Rhizobium etli CE3 in exponential and stationary growth phase

    Directory of Open Access Journals (Sweden)

    Mendoza-Hernández Guillermo

    2010-10-01

    Full Text Available Abstract Background The extracellular proteome or secretome of symbiotic bacteria like Rhizobium etli is presumed to be a key element of their infection strategy and survival. Rhizobia infect the roots of leguminous plants and establish a mutually beneficial symbiosis. To find out the possible role of secreted proteins we analyzed the extracellular proteome of R. etli CE3 in the exponential and stationary growth phases in minimal medium, supplemented with succinate-ammonium. Results The extracellular proteins were obtained by phenol extraction and identified by LC-ESI MS/MS. We identified 192 and 191 proteins for the exponential and stationary phases respectively. Using the software Signal P, we predicted signal peptides for 12.95% and 35.60% of the proteins identified in the exponential and stationary phases, respectively, which could therefore be secreted by the Sec pathway. For the exponential growth phase, we found in abundance proteins like the ribosomal proteins, toxins and proteins belonging to the group "defence mechanisms". For the stationary growth phase, we found that the most abundant proteins were those with unknown function, and in many of these we identified characteristic domains of proteases and peptidases. Conclusions Our study provided the first dataset of the secretome of R. etli and its modifications, which may lead to novel insights into the adaptive response of different stages of growth. In addition, we found a high number of proteins with unknown function; these proteins could be analyzed in future research to elucidate their role in the extracellular proteome of R. etli.

  11. Upper bounds on a two-term exponential sum

    Institute of Scientific and Technical Information of China (English)

    Todd; Cochrane

    2001-01-01

    [1]Davenport, H. , Heibronn, H., On an exponential sum, Proc. Lond. Math. Soc., 1936, 41(2): 449-453.[2]Hua, L. K., On exponential sums, Sci. Record (Peking) (N.S.), 1957, 1: 1-4.[3]Vaughan, R. C. , The Hardy-Littlewood Method, 2nd ed. , Cambridge Tracts in Math. , Cambridge: Cambridge Univ. Press, 1997, 125.[4]Weil, A., On some exponential sums, Proc. Nat. Acad. Sci. USA, 1948, 34: 204-207.[5]Cochrane, T., Zheng, Z., Pure and mixed exponential sums, Acta Arith. , 1999, 91(3): 249-278.[6]Chalk, J. H. H., On Hua's estimate for exponential sums, Mathematika, 1987, 34: 115-123.[7]Loh, W. K. A. , Hua's Lemma, Bull. Australian Math. Soc., 1994, 50(3): 451-458.[8]Ding, P., An improvement to Chalk's estimation of exponential sums, Acta Arith. , 1991, 59(2): 149-155.

  12. The Secular Evolution Of Disc Galaxies And The Origin Of Exponential And Double Exponential Surface Density Profiles

    Science.gov (United States)

    Elmegreen, Bruce G.

    2016-10-01

    Exponential radial profiles are ubiquitous in spiral and dwarf Irregular galaxies, but the origin of this structural form is not understood. This talk will review the observations of exponential and double exponential disks, considering both the light and the mass profiles, and the contributions from stars and gas. Several theories for this structure will also be reviewed, including primordial collapse, bar and spiral torques, clump torques, galaxy interactions, disk viscosity and other internal processes of angular momentum exchange, and stellar scattering off of clumpy structure. The only process currently known that can account for this structure in the most theoretically difficult case is stellar scattering off disks clumps. Stellar orbit models suggest that such scattering can produce exponentials even in isolated dwarf irregulars that have no bars or spirals, little shear or viscosity, and profiles that go out too far for the classical Mestel case of primordial collapse with specific angular momentum conservation.

  13. Neuro-fuzzy computing for vibration-based damage localization and severity estimation in an experimental wind turbine blade with superimposed operational effects

    Science.gov (United States)

    Hoell, Simon; Omenzetter, Piotr

    2016-04-01

    Fueled by increasing demand for carbon neutral energy, erections of ever larger wind turbines (WTs), with WT blades (WTBs) with higher flexibilities and lower buckling capacities lead to increasing operation and maintenance costs. This can be counteracted with efficient structural health monitoring (SHM), which allows scheduling maintenance actions according to the structural state and preventing dramatic failures. The present study proposes a novel multi-step approach for vibration-based structural damage localization and severity estimation for application in operating WTs. First, partial autocorrelation coefficients (PACCs) are estimated from vibrational responses. Second, principal component analysis is applied to PACCs from the healthy structure in order to calculate scores. Then, the scores are ranked with respect to their ability to differentiate different damage scenarios. This ranking information is used for constructing hierarchical adaptive neuro-fuzzy inference systems (HANFISs), where cross-validation is used to identify optimal numbers of hierarchy levels. Different HANFISs are created for the purposes of structural damage localization and severity estimation. For demonstrating the applicability of the approach, experimental data are superimposed with signals from numerical simulations to account for characteristics of operational noise. For the physical experiments, a small scale WTB is excited with a domestic fan and damage scenarios are introduced non-destructively by attaching small masses. Numerical simulations are also performed for a representative fully functional small WT operating in turbulent wind. The obtained results are promising for future applications of vibration-based SHM to facilitate improved safety and reliability of WTs at lower costs.

  14. Exponential growth combined with exponential decline explains lifetime performance evolution in individual and human species.

    Science.gov (United States)

    Berthelot, Geoffroy; Len, Stéphane; Hellard, Philippe; Tafflet, Muriel; Guillaume, Marion; Vollmer, Jean-Claude; Gager, Bruno; Quinquis, Laurent; Marc, Andy; Toussaint, Jean-François

    2012-08-01

    The physiological parameters characterizing human capacities (the ability to move, reproduce or perform tasks) evolve with ageing: performance is limited at birth, increases to a maximum and then decreases back to zero at the day of death. Physical and intellectual skills follow such a pattern. Here, we investigate the development of sport and chess performances during the lifetime at two different scales: the individual athletes' careers and the world record by age class in 25 Olympic sports events and in grandmaster chess players. For all data sets, a biphasic development of growth and decline is described by a simple model that accounts for 91.7% of the variance at the individual level and 98.5% of the variance at the species one. The age of performance peak is computed at 26.1 years old for the events studied (26.0 years old for track and field, 21.0 years old for swimming and 31.4 years old for chess). The two processes (growth and decline) are exponential and start at age zero. Both were previously demonstrated to happen in other human and non-human biological functions that evolve with age. They occur at the individual and species levels with a similar pattern, suggesting a scale invariance property.

  15. Simultaneous ultrafast optical pulse train bursts generation and shaping based on Fourier series developments using superimposed fiber Bragg gratings.

    Science.gov (United States)

    García-Muñoz, Víctor; Preciado, Miguel A; Muriel, Miguel A

    2007-08-20

    We propose an all-fiber method for the generation of ultrafast shaped pulse train bursts from a single pulse based on Fourier Series Developments (FDSs). The implementation of the FSD based filter only requires the use of a very simple non apodized Superimposed Fiber Bragg Grating (S-FBG) for the generation of the Shaped Output Pulse Train Burst (SOPTB). In this approach, the shape, the period and the temporal length of the generated SOPTB have no dependency on the input pulse rate.

  16. Recent developments in study of the typical superimposed basins and petroleum accumulation in China:Exemplified by the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    JIN Zhijun; WANG Qingchen

    2004-01-01

    Most of petroliferous sedimentary basins in China have experienced multiple phases of tectonic evolution and deposition, and are characterized by tectonic and depositional superimposition. The term "superimposed basin" is suggested to describe those basins which consist of two or more simple prototype basins superimposing vertically and/or coalescing laterally. The characteristics of petroliferous superimposed basins are "multiple stages of basin forming and reworking, multiple layers of source rocks, multiple periods of hydrocarbon generation and expulsion, multiple periods of petroleum migration-accumulation-escape". Therefore,applying the wave process analysis method to studying the process of basin formation, hydrocarbon generation, and reservoir formation, and then establishing theory of "petroleum accumulation system" is helpful to enhancing petroleum exploration efficiency in superimposed basins.This paper will, based on case study in the Tarim basin, report the major developments in studying basin formation, hydrocarbon generation and petroleum accumulation. In study of basin formation, (1) geophysical comprehensive profiles reveal that the Tarim plate has been subducted beneath the Tianshan orogenic belt with an interfinger structure and that the deep structure in the eastern section of the Tianshan orogenic belt is different from that in the western section. (2) The vertical variation in debris and geochemical composition reveals the nature and Mesozoic-Cenozoic evolution history of the Kuqa Depression. (3) Field investigation and paleostress reconstruction show that the Kuqa Depression has undergone gravity-driven extension in sedimentary cover when the Tianshan uplifted vertically. In hydrocarbon generation study, new developments include (1) setting environmental index to judge high grade source rocks in marine carbonates, and (2) establishing the lower limit of the organic carbon content for effective carbonate source rocks. In petroleum accumulation

  17. Recent developments in study of the typical superimposed basins and petroleum accumulation in China: Exemplified by the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    JIN; Zhijun; WANG; Qingchen

    2004-01-01

    Most of petroliferous sedimentary basins in China have experienced multiple phases of tectonic evolution and deposition, and are characterized by tectonic and depositional superimposition. The term "superimposed basin" is suggested to describe those basins which consist of two or more simple prototype basins superimposing vertically and/or coalescing laterally. The characteristics of petroliferous superimposed basins are "multiple stages of basin forming and reworking, multiple layers of source rocks, multiple periods of hydrocarbon generation and expulsion, multiple periods of petroleum migration-accumulation-escape". Therefore,applying the wave process analysis method to studying the process of basin formation, hydrocarbon generation, and reservoir formation, and then establishing theory of "petroleum accumulation system" is helpful to enhancing petroleum exploration efficiency in superimposed basins.This paper will, based on case study in the Tarim basin, report the major developments in studying basin formation, hydrocarbon generation and petroleum accumulation. In study of basin formation, (1) geophysical comprehensive profiles reveal that the Tarim plate has been subducted beneath the Tianshan orogenic belt with an interfinger structure and that the deep structure in the eastern section of the Tianshan orogenic belt is different from that in the western section. (2) The vertical variation in debris and geochemical composition reveals the nature and Mesozoic-Cenozoic evolution history of the Kuqa Depression. (3) Field investigation and paleostress reconstruction show that the Kuqa Depression has undergone gravity-driven extension in sedimentary cover when the Tianshan uplifted vertically. In hydrocarbon generation study, new developments include (1) setting environmental index to judge high grade source rocks in marine carbonates, and (2) establishing the lower limit of the organic carbon content for effective carbonate source rocks. In petroleum accumulation

  18. Vulvar and Perianal Condyloma Superimposed Inflammatory Linear Verrucous Epidermal Nevus: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Sümeyra Nergız Avcioğlu

    2013-01-01

    Full Text Available Inflammatory linear verrucous epidermal nevus (ILVEN is a benign cutaneous hamartoma characterized by intensely erythematous, pruritic, and inflammatory papules that occur as linear bands along the lines of Blaschko. There is a considerable clinical and histological resemblance between ILVEN and linear psoriasis, lichen striatus, linear lichen planus, and invasion of epidermal nevus by psoriasis. The pathogenesis of ILVEN is unknown. It is regarded as a genetic dyskeratotic disease reflecting genetic mosaicism. Here, a case of vulvar and perianal condyloma superimposed ILVEN is presented.

  19. Using Standardized Case Vignettes to Evaluate Nursing Home Staff Recognition of Delirium and Delirium Superimposed on Dementia

    Science.gov (United States)

    Fick, Donna M.; Kolanowski, Ann M.; Hill, Nikki L.; Yevchak, Andrea; DiMeglio, Brittney; Mulhall, Paula M.

    2014-01-01

    The purpose of this study is to describe nursing home staff knowledge regarding delirium detection and the most common causes of delirium. Specific aims that guided this study include identifying the rate of nurse recognition of delirium and delirium superimposed on dementia (DSD), including different motoric subtypes of delirium, using standardized case vignettes, and exploring what nursing home staff describe as the potential causes of delirium. The study showed overall poor recognition of delirium and DSD, which did not improve over time. Interventions have the potential to increase the early detection of delirium and DSD by the staff and warrant development. PMID:25400513

  20. Bayesian estimation of generalized exponential distribution under noninformative priors

    Science.gov (United States)

    Moala, Fernando Antonio; Achcar, Jorge Alberto; Tomazella, Vera Lúcia Damasceno

    2012-10-01

    The generalized exponential distribution, proposed by Gupta and Kundu (1999), is a good alternative to standard lifetime distributions as exponential, Weibull or gamma. Several authors have considered the problem of Bayesian estimation of the parameters of generalized exponential distribution, assuming independent gamma priors and other informative priors. In this paper, we consider a Bayesian analysis of the generalized exponential distribution by assuming the conventional noninformative prior distributions, as Jeffreys and reference prior, to estimate the parameters. These priors are compared with independent gamma priors for both parameters. The comparison is carried out by examining the frequentist coverage probabilities of Bayesian credible intervals. We shown that maximal data information prior implies in an improper posterior distribution for the parameters of a generalized exponential distribution. It is also shown that the choice of a parameter of interest is very important for the reference prior. The different choices lead to different reference priors in this case. Numerical inference is illustrated for the parameters by considering data set of different sizes and using MCMC (Markov Chain Monte Carlo) methods.

  1. Non-exponential and oscillatory decays in quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Peshkin, Murray [Argonne National Lab. (ANL), Argonne, IL (United States); Volya, Alexander [Florida State Univ., Tallahassee, FL (United States); Zelevinsky, Vladimir [Michigan State Univ., East Lansing, MI (United States)

    2014-08-07

    The quantum-mechanical theory of the decay of unstable states is revisited. We show that the decay is non-exponential both in the short-time and long-time limits using a more physical definition of the decay rate than the one usually used. We report results of numerical studies based on Winter's model that may elucidate qualitative features of exponential and non-exponential decay more generally. The main exponential stage is related to the formation of a radiating state that maintains the shape of its wave function with exponentially diminishing normalization. We discuss situations where the radioactive decay displays several exponents. The transient stages between different regimes are typically accompanied by interference of various contributions and resulting oscillations in the decay curve. The decay curve can be fully oscillatory in a two-flavor generalization of Winter's model with some values of the parameters. We consider the implications of that result for models of the oscillations reported by GSI.

  2. Extended q-Gaussian and q-exponential distributions from gamma random variables.

    Science.gov (United States)

    Budini, Adrián A

    2015-05-01

    The family of q-Gaussian and q-exponential probability densities fit the statistical behavior of diverse complex self-similar nonequilibrium systems. These distributions, independently of the underlying dynamics, can rigorously be obtained by maximizing Tsallis "nonextensive" entropy under appropriate constraints, as well as from superstatistical models. In this paper we provide an alternative and complementary scheme for deriving these objects. We show that q-Gaussian and q-exponential random variables can always be expressed as a function of two statistically independent gamma random variables with the same scale parameter. Their shape index determines the complexity q parameter. This result also allows us to define an extended family of asymmetric q-Gaussian and modified q-exponential densities, which reduce to the standard ones when the shape parameters are the same. Furthermore, we demonstrate that a simple change of variables always allows relating any of these distributions with a beta stochastic variable. The extended distributions are applied in the statistical description of different complex dynamics such as log-return signals in financial markets and motion of point defects in a fluid flow.

  3. Resolution of Nested Neuronal Representations Can Be Exponential in the Number of Neurons

    Science.gov (United States)

    Mathis, Alexander; Herz, Andreas V. M.; Stemmler, Martin B.

    2012-07-01

    Collective computation is typically polynomial in the number of computational elements, such as transistors or neurons, whether one considers the storage capacity of a memory device or the number of floating-point operations per second of a CPU. However, we show here that the capacity of a computational network to resolve real-valued signals of arbitrary dimensions can be exponential in N, even if the individual elements are noisy and unreliable. Nested, modular codes that achieve such high resolutions mirror the properties of grid cells in vertebrates, which underlie spatial navigation.

  4. Flipped-Exponential Nyquist Pulse Technique to Optimize PAPR in Optical Direct-Detection OFDM Systems

    Institute of Scientific and Technical Information of China (English)

    Jiangnan Xiao; Zizheng Cao; Fan Li; Jin Tang; Lin Chen

    2012-01-01

    In this paper, we describe a novel technique based on the flipped-exponential (FE) Nyquist pulse method for reducing peak-to-average power ratio (PAPR) in an optical direct-detection orthogonal frequency-division multiplexing (DD-QFDM) system, The technique involves proper selection of the FE Nyquist pulses for shaping the different subcarriers of the OFDM. We apply this technique to a DD-OFDM transmission system to significantly reduce PAPR. We also investigate the sensitivity of a received OFDM signal with strong nonlinearity in a standard single-mode fiber (SMF).

  5. Exponential Sensitivity and its Cost in Quantum Physics.

    Science.gov (United States)

    Gilyén, András; Kiss, Tamás; Jex, Igor

    2016-02-10

    State selective protocols, like entanglement purification, lead to an essentially non-linear quantum evolution, unusual in naturally occurring quantum processes. Sensitivity to initial states in quantum systems, stemming from such non-linear dynamics, is a promising perspective for applications. Here we demonstrate that chaotic behaviour is a rather generic feature in state selective protocols: exponential sensitivity can exist for all initial states in an experimentally realisable optical scheme. Moreover, any complex rational polynomial map, including the example of the Mandelbrot set, can be directly realised. In state selective protocols, one needs an ensemble of initial states, the size of which decreases with each iteration. We prove that exponential sensitivity to initial states in any quantum system has to be related to downsizing the initial ensemble also exponentially. Our results show that magnifying initial differences of quantum states (a Schrödinger microscope) is possible; however, there is a strict bound on the number of copies needed.

  6. On the Exponential Probability Bounds for the Bernoulli Random Variables

    CERN Document Server

    Nikulin, Vladimir

    2010-01-01

    We consider upper exponential bounds for the probability of the event that an absolute deviation of sample mean from mathematical expectation p is bigger comparing with some ordered level epsilon. These bounds include 2 coefficients {alpha, beta}. In order to optimize the bound we are interested to minimize linear coefficient alpha and to maximize exponential coefficient beta. Generally, the value of linear coefficient alpha may not be smaller than one. The following 2 settings were proved: 1) {1, 2} in the case of classical discreet problem as it was formulated by Bernoulli in the 17th century, and 2) {1, 2/(1+epsilon^2)} in the general discreet case with arbitrary rational p and epsilon. The second setting represents a new structure of the exponential bound which may be extended to continuous case.

  7. Exponential rise of dynamical complexity in quantum computing through projections.

    Science.gov (United States)

    Burgarth, Daniel Klaus; Facchi, Paolo; Giovannetti, Vittorio; Nakazato, Hiromichi; Pascazio, Saverio; Yuasa, Kazuya

    2014-10-10

    The ability of quantum systems to host exponentially complex dynamics has the potential to revolutionize science and technology. Therefore, much effort has been devoted to developing of protocols for computation, communication and metrology, which exploit this scaling, despite formidable technical difficulties. Here we show that the mere frequent observation of a small part of a quantum system can turn its dynamics from a very simple one into an exponentially complex one, capable of universal quantum computation. After discussing examples, we go on to show that this effect is generally to be expected: almost any quantum dynamics becomes universal once 'observed' as outlined above. Conversely, we show that any complex quantum dynamics can be 'purified' into a simpler one in larger dimensions. We conclude by demonstrating that even local noise can lead to an exponentially complex dynamics.

  8. Kullback-Leibler divergence and the Pareto-Exponential approximation.

    Science.gov (United States)

    Weinberg, G V

    2016-01-01

    Recent radar research interests in the Pareto distribution as a model for X-band maritime surveillance radar clutter returns have resulted in analysis of the asymptotic behaviour of this clutter model. In particular, it is of interest to understand when the Pareto distribution is well approximated by an Exponential distribution. The justification for this is that under the latter clutter model assumption, simpler radar detection schemes can be applied. An information theory approach is introduced to investigate the Pareto-Exponential approximation. By analysing the Kullback-Leibler divergence between the two distributions it is possible to not only assess when the approximation is valid, but to determine, for a given Pareto model, the optimal Exponential approximation.

  9. On the performance of exponential integrators for problems in magnetohydrodynamics

    CERN Document Server

    Einkemmer, Lukas; Loffeld, John

    2016-01-01

    Exponential integrators have been introduced as an efficient alternative to explicit and implicit methods for integrating large stiff systems of differential equations. Over the past decades these methods have been studied theoretically and their performance was evaluated using a range of test problems. While the results of these investigations showed that exponential integrators can provide significant computational savings, the research on validating this hypothesis for large scale systems and understanding what classes of problems can particularly benefit from the use of the new techniques is in its initial stages. Resistive magnetohydrodynamic (MHD) modeling is widely used in studying large scale behavior of laboratory and astrophysical plasmas. In many problems numerical solution of MHD equations is a challenging task due to the temporal stiffness of this system in the parameter regimes of interest. In this paper we evaluate the performance of exponential integrators on large MHD problems and compare the...

  10. Exponential stretch-rotation (ESR) formulation of general relativity

    CERN Document Server

    Khokhlov, A M

    2003-01-01

    We study a tensorial exponential transformation of a three-dimensional metric of space-like hypersurfaces embedded in a four-dimensional space-time, $\\gamma_{ij} = e^{\\epsilon_{ikm}\\theta_m} e^{\\phi_k} e^{-\\epsilon_{jkn}\\theta_n}$, where $\\phi_k$ are logarithms of the eigenvalues of $\\gamma_{ij}$, $\\theta_k$ are rotation angles, and $\\epsilon_{ijk}$ is a fully anti-symmetric symbol. Evolution part of Einstein's equations, formulated in terms of $\\phi_k$ and $\\theta_k$, describes time evolution of the metric at every point of a hyper-surface as a continuous stretch and rotation of a local coordinate system in a tangential space. The exponential stretch-rotation (ESR) transformation generalizes particular exponential transformations used previously in cases of spatial symmetry. The ESR 3+1 formulation of Einstein's equations may have certain advantages for long-term stable integration of these equations.

  11. Design of a 9-loop quasi-exponential waveform generator.

    Science.gov (United States)

    Banerjee, Partha; Shukla, Rohit; Shyam, Anurag

    2015-12-01

    We know in an under-damped L-C-R series circuit, current follows a damped sinusoidal waveform. But if a number of sinusoidal waveforms of decreasing time period, generated in an L-C-R circuit, be combined in first quarter cycle of time period, then a quasi-exponential nature of output current waveform can be achieved. In an L-C-R series circuit, quasi-exponential current waveform shows a rising current derivative and thereby finds many applications in pulsed power. Here, we have described design and experiment details of a 9-loop quasi-exponential waveform generator. In that, design details of magnetic switches have also been described. In the experiment, output current of 26 kA has been achieved. It has been shown that how well the experimentally obtained output current profile matches with the numerically computed output.

  12. Experimental investigation of SDBD plasma actuator driven by AC high voltage with a superimposed positive pulse bias voltage

    Science.gov (United States)

    Qi, Xiao-Hua; Yan, Hui-Jie; Yang, Liang; Hua, Yue; Ren, Chun-Sheng

    2017-08-01

    In this work, a driven voltage consisting of AC high voltage with a superimposed positive pulse bias voltage ("AC+ Positive pulse bias" voltage) is adopted to study the performance of a surface dielectric barrier discharge plasma actuator under atmospheric conditions. To compare the performance of the actuator driven by single-AC voltage and "AC+ Positive pulse bias" voltage, the actuator-induced thrust force and power consumption are measured as a function of the applied AC voltage, and the measured results indicate that the thrust force can be promoted significantly after superimposing the positive pulse bias voltage. The physical mechanism behind the thrust force changes is analyzed by measuring the optical properties, electrical characteristics, and surface potential distribution. Experimental results indicate that the glow-like discharge in the AC voltage half-cycle, next to the cycle where a bias voltage pulse has been applied, is enhanced after applying the positive pulse bias voltage, and this perhaps is the main reason for the thrust force increase. Moreover, surface potential measurement results reveal that the spatial electric field formed by the surface charge accumulation after positive pulse discharge can significantly affect the applied external electric field, and this perhaps can be responsible for the experimental phenomenon that the decrease of thrust force is delayed by pulse bias voltage action after the filament discharge occurs in the glow-like discharge region. The schlieren images further verify that the actuator-induced airflow velocity increases with the positive pulse voltage.

  13. Combined multi-nozzle deposition and freeze casting process to superimpose two porous networks for hierarchical three-dimensional microenvironment.

    Science.gov (United States)

    Snyder, Jessica E; Hunger, Philipp M; Wang, Chengyang; Hamid, Qudus; Wegst, Ulrike G K; Sun, Wei

    2014-03-01

    An engineered three-dimensional scaffold with hierarchical porosity and multiple niche microenvironments is produced using a combined multi-nozzle deposition-freeze casting technique. In this paper we present a process to fabricate a scaffold with improved interconnectivity and hierarchical porosity. The scaffold is produced using a two-stage manufacturing process which superimposes a printed porous alginate (Alg) network and a directionally frozen ceramic-polymer matrix. The combination of two processes, multi-nozzle deposition and freeze casting, provides engineering control of the microenvironment of the scaffolds over several length scales; including the addition of lateral porosity and the ratio of polymer to ceramic microstructures. The printed polymer scaffold is submerged in a ceramic-polymer slurry and subsequently, both structures are directionally frozen (freeze cast), superimposing and patterning both microenvironments into a single hierarchical architecture. An optional additional sintering step removes the organic material and densifies the ceramic phase to produce a well-defined network of open pores and a homogenous cell wall material composition. The techniques presented in this contribution address processing challenges, such as structure definition, reproducibility and fine adjustments of unique length scales, which one typically encounters when fabricating topological channels between longitudinal and transverse porous networks.

  14. On the performance of exponential integrators for problems in magnetohydrodynamics

    Science.gov (United States)

    Einkemmer, Lukas; Tokman, Mayya; Loffeld, John

    2017-02-01

    Exponential integrators have been introduced as an efficient alternative to explicit and implicit methods for integrating large stiff systems of differential equations. Over the past decades these methods have been studied theoretically and their performance was evaluated using a range of test problems. While the results of these investigations showed that exponential integrators can provide significant computational savings, the research on validating this hypothesis for large scale systems and understanding what classes of problems can particularly benefit from the use of the new techniques is in its initial stages. Resistive magnetohydrodynamic (MHD) modeling is widely used in studying large scale behavior of laboratory and astrophysical plasmas. In many problems numerical solution of MHD equations is a challenging task due to the temporal stiffness of this system in the parameter regimes of interest. In this paper we evaluate the performance of exponential integrators on large MHD problems and compare them to a state-of-the-art implicit time integrator. Both the variable and constant time step exponential methods of EPIRK-type are used to simulate magnetic reconnection and the Kevin-Helmholtz instability in plasma. Performance of these methods, which are part of the EPIC software package, is compared to the variable time step variable order BDF scheme included in the CVODE (part of SUNDIALS) library. We study performance of the methods on parallel architectures and with respect to magnitudes of important parameters such as Reynolds, Lundquist, and Prandtl numbers. We find that the exponential integrators provide superior or equal performance in most circumstances and conclude that further development of exponential methods for MHD problems is warranted and can lead to significant computational advantages for large scale stiff systems of differential equations such as MHD.

  15. Is it growing exponentially fast? -- Impact of assuming exponential growth for characterizing and forecasting epidemics with initial near-exponential growth dynamics.

    Science.gov (United States)

    Chowell, Gerardo; Viboud, Cécile

    2016-10-01

    The increasing use of mathematical models for epidemic forecasting has highlighted the importance of designing models that capture the baseline transmission characteristics in order to generate reliable epidemic forecasts. Improved models for epidemic forecasting could be achieved by identifying signature features of epidemic growth, which could inform the design of models of disease spread and reveal important characteristics of the transmission process. In particular, it is often taken for granted that the early growth phase of different growth processes in nature follow early exponential growth dynamics. In the context of infectious disease spread, this assumption is often convenient to describe a transmission process with mass action kinetics using differential equations and generate analytic expressions and estimates of the reproduction number. In this article, we carry out a simulation study to illustrate the impact of incorrectly assuming an exponential-growth model to characterize the early phase (e.g., 3-5 disease generation intervals) of an infectious disease outbreak that follows near-exponential growth dynamics. Specifically, we assess the impact on: 1) goodness of fit, 2) bias on the growth parameter, and 3) the impact on short-term epidemic forecasts. Designing transmission models and statistical approaches that more flexibly capture the profile of epidemic growth could lead to enhanced model fit, improved estimates of key transmission parameters, and more realistic epidemic forecasts.

  16. Contribution of mono-exponential, bi-exponential and stretched exponential model-based diffusion-weighted MR imaging in the diagnosis and differentiation of uterine cervical carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Meng; Yu, Xiaoduo; Chen, Yan; Ouyang, Han; Zhou, Chunwu [Chinese Academy of Medical Sciences, Department of Diagnostic Radiology, Cancer Institute and Hospital, Peking Union Medical College, Beijing (China); Wu, Bing; Zheng, Dandan [GE MR Research China, Beijing (China)

    2017-06-15

    To investigate the potential of various metrics derived from mono-exponential model (MEM), bi-exponential model (BEM) and stretched exponential model (SEM)-based diffusion-weighted imaging (DWI) in diagnosing and differentiating the pathological subtypes and grades of uterine cervical carcinoma. 71 newly diagnosed patients with cervical carcinoma (50 cases of squamous cell carcinoma [SCC] and 21 cases of adenocarcinoma [AC]) and 32 healthy volunteers received DWI with multiple b values. The apparent diffusion coefficient (ADC), pure molecular diffusion (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), water molecular diffusion heterogeneity index (alpha), and distributed diffusion coefficient (DDC) were calculated and compared between tumour and normal cervix, among different pathological subtypes and grades. All of the parameters were significantly lower in cervical carcinoma than normal cervical stroma except alpha. SCC showed lower ADC, D, f and DDC values and higher D* value than AC; D and DDC values of SCC and ADC and D values of AC were lower in the poorly differentiated group than those in the well-moderately differentiated group. Compared with MEM, diffusion parameters from BEM and SEM may offer additional information in cervical carcinoma diagnosis, predicting pathological tumour subtypes and grades, while f and D showed promising significance. (orig.)

  17. New results on robust exponential stability of integral delay systems

    Science.gov (United States)

    Melchor-Aguilar, Daniel

    2016-06-01

    The robust exponential stability of integral delay systems with exponential kernels is investigated. Sufficient delay-dependent robust conditions expressed in terms of linear matrix inequalities and matrix norms are derived by using the Lyapunov-Krasovskii functional approach. The results are combined with a new result on quadratic stabilisability of the state-feedback synthesis problem in order to derive a new linear matrix inequality methodology of designing a robust non-fragile controller for the finite spectrum assignment of input delay systems that guarantees simultaneously a numerically safe implementation and also the robustness to uncertainty in the system matrices and to perturbation in the feedback gain.

  18. Exponential sensitivity of noise-driven switching in genetic networks

    Science.gov (United States)

    Mehta, Pankaj; Mukhopadhyay, Ranjan; Wingreen, Ned S.

    2008-06-01

    There is increasing experimental evidence that cells can utilize biochemical noise to switch probabilistically between distinct gene-expression states. In this paper, we demonstrate that such noise-driven switching is dominated by tails of probability distributions and is therefore exponentially sensitive to changes in physiological parameters such as transcription and translation rates. Exponential sensitivity limits the robustness of noise-driven switching, suggesting cells may use other mechanisms in order to switch reliably. We discuss our results in the context of competence in the bacterium Bacillus subtilis.

  19. Exponential Lower Bounds and Separation for Query Rewriting

    CERN Document Server

    Kikot, Stanislav; Podolskii, Vladimir; Zakharyaschev, Michael

    2012-01-01

    We establish connections between the size of circuits and formulas computing monotone Boolean functions and the size of first-order and nonrecursive Datalog rewritings for conjunctive queries over OWL 2 QL ontologies. We use known lower bounds and separation results from circuit complexity to prove similar results for the size of rewritings that do not use non-signature constants. For example, we show that, in the worst case, positive existential and nonrecursive Datalog rewritings are exponentially longer than the original queries; nonrecursive Datalog rewritings are in general exponentially more succinct than positive existential rewritings; while first-order rewritings can be superpolynomially more succinct than positive existential rewritings.

  20. Real-Time Exponential Curve Fits Using Discrete Calculus

    Science.gov (United States)

    Rowe, Geoffrey

    2010-01-01

    An improved solution for curve fitting data to an exponential equation (y = Ae(exp Bt) + C) has been developed. This improvement is in four areas -- speed, stability, determinant processing time, and the removal of limits. The solution presented avoids iterative techniques and their stability errors by using three mathematical ideas: discrete calculus, a special relationship (be tween exponential curves and the Mean Value Theorem for Derivatives), and a simple linear curve fit algorithm. This method can also be applied to fitting data to the general power law equation y = Ax(exp B) + C and the general geometric growth equation y = Ak(exp Bt) + C.

  1. AN EXPONENTIAL INEQUALITY FOR AUTOREGRESSIVE PROCESSES IN ADAPTIVE TRACKING

    Institute of Scientific and Technical Information of China (English)

    Bernard BERCU

    2007-01-01

    A wide range of literature concerning classical asymptotic properties for linear models with adaptive control is available, such as strong laws of large numbers or central limit theorems.Unfortunately, in contrast with the situation without control, it appears to be impossible to find sharp asymptotic or nonasymptotic properties such as large deviation principles or exponential inequalities.Our purpose is to provide a first step towards that direction by proving a very simple exponential inequality for the standard least squares estimator of the unknown parameter of Gaussian autoregressive process in adaptive tracking.

  2. Exponential stability for uncertain neutral systems with Markov jumps

    Institute of Scientific and Technical Information of China (English)

    Shuping HE; Fei LIU

    2009-01-01

    This paper deals with the global exponential stability problems for stochastic neutral Markov jump sys-tems(MJSs) with uncertain parameters and multiple time-delays,The delays are respectively considered as constant and time varying cases,and the uncertainties are assumed to be norm bounded.By selecting appropriate Lyapunov-Krasovskii functions,it gives the sufficient condition such that the uncertain neutral MJSs are globally exponentially stochastically stable for all admissible uncertainties.The stability criteria are formulated in the form of linear matrix inequalities(LMIs),which can be easily checked in practice.Finally,two numerical examples are exploited to illustrate the effectiveness of the developed techniques.

  3. THE ROC CURVE MODEL FROM GENERALIZED-EXPONENTIAL DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    Ehtesham Hussain

    2011-04-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 In biomedical studies often yield continuously positively skewed (non- normal distributed data. In this regard Generalized-Exponential Distribution is suggested for analyzing such data. In this paper the parametric equation of  the Receiving Operating Characteristic (ROC curve model is established under the assumptions of bi-distributional population based on pair of Generalized-Exponential Distributions. Also its maximum likelihood estimator MLE, sampling distribution , equivalence test statistic and exact confidence interval are derived.  

  4. On an Asymptotic Behavior of Exponential Functional Equation

    Institute of Scientific and Technical Information of China (English)

    Soon Mo JUNG

    2006-01-01

    The stability problems of the exponential (functional) equation on a restricted domain will be investigated, and the results will be applied to the study of an asymptotic property of that equation. More precisely, the following asymptotic property is proved: Let X be a real (or complex)normed space. A mapping f : X → C is exponential if and only if f(x + y) - f(x)f(y) → 0 as ‖x‖ + ‖y‖→∞ under some suitable conditions.

  5. Stability of the Exponential Functional Equation in Riesz Algebras

    Directory of Open Access Journals (Sweden)

    Bogdan Batko

    2014-01-01

    Full Text Available We deal with the stability of the exponential Cauchy functional equation F(x+y=F(xF(y in the class of functions F:G→L mapping a group (G, + into a Riesz algebra L. The main aim of this paper is to prove that the exponential Cauchy functional equation is stable in the sense of Hyers-Ulam and is not superstable in the sense of Baker. To prove the stability we use the Yosida Spectral Representation Theorem.

  6. On unit root formulas for toric exponential sums

    CERN Document Server

    Adolphson, Alan

    2010-01-01

    Starting from a classical generating series for Bessel functions due to Schlomilch, we use Dwork's relative dual theory to broadly generalize unit-root results of Dwork on Kloosterman sums and Sperber on hyperkloosterman sums. In particular, we express the (unique) p-adic unit root of an arbitrary exponential sum on the torus in terms of special values of the p-adic analytic continuation of a ratio of A-hypergeometric functions. In contrast with the earlier works, we use noncohomological methods and obtain results that are valid for arbitrary exponential sums without any hypothesis of nondegeneracy.

  7. TESTING FOR VARYING DISPERSION IN DISCRETE EXPONENTIAL FAMILY NONLINEAR MODELS

    Institute of Scientific and Technical Information of China (English)

    LinJinguan; WeiBocheng; ZhangNansong

    2003-01-01

    It is necessary to test for varying dispersion in generalized nonlinear models. Wei ,et al(1998) developed a likelihood ratio test,a score test and their adjustments to test for varying dispersion in continuous exponential family nonlinear models. This type of problem in the framework of general discrete exponential family nonlinear models is discussed. Two types of varying dispersion, which are random coefficients model and random effects model, are proposed,and corresponding score test statistics are constructed and expressed in simple ,easy to use ,matrix formulas.

  8. Circuit design and exponential stabilization of memristive neural networks.

    Science.gov (United States)

    Wen, Shiping; Huang, Tingwen; Zeng, Zhigang; Chen, Yiran; Li, Peng

    2015-03-01

    This paper addresses the problem of circuit design and global exponential stabilization of memristive neural networks with time-varying delays and general activation functions. Based on the Lyapunov-Krasovskii functional method and free weighting matrix technique, a delay-dependent criteria for the global exponential stability and stabilization of memristive neural networks are derived in form of linear matrix inequalities (LMIs). Two numerical examples are elaborated to illustrate the characteristics of the results. It is noteworthy that the traditional assumptions on the boundness of the derivative of the time-varying delays are removed.

  9. Exponential model for option prices: Application to the Brazilian market

    Science.gov (United States)

    Ramos, Antônio M. T.; Carvalho, J. A.; Vasconcelos, G. L.

    2016-03-01

    In this paper we report an empirical analysis of the Ibovespa index of the São Paulo Stock Exchange and its respective option contracts. We compare the empirical data on the Ibovespa options with two option pricing models, namely the standard Black-Scholes model and an empirical model that assumes that the returns are exponentially distributed. It is found that at times near the option expiration date the exponential model performs better than the Black-Scholes model, in the sense that it fits the empirical data better than does the latter model.

  10. Fourier Transform of the Stretched Exponential Function: Analytic Error Estimates, Double Exponential Transform, and Open-Source Implementation libkww

    CERN Document Server

    Wuttke, Joachim

    2009-01-01

    An algorithm is described for computing the Laplace transform (one-sided Fourier sine and cosine transform) of the stretched (or compressed) exponential function exp(-t^beta) (also known as Kohlrausch-Williams-Watts function, as characteristic function of a Levy stable distribution, or as complementary cumulative Weibull distribution) for exponents beta between 0.1 and 2. For low and high frequencies, the well-known series expansions are used; for intermediate frequencies, the explicit integration is strongly accelerated by the Ooura-Mori double exponential transformation. The algorithm is implemented in C as library libkww. The source code is available at http://www.messen-und-deuten.de/kww

  11. Towards multi-exponential analysis in optically stimulated luminescence

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank; Hansen, Per Christian

    2010-01-01

    Optically stimulated luminescence (OSL) data from quartz can follow different mathematical forms depending on the stimulation mode. These data can be described in terms of different multi-exponential models and can be numerically fitted using several well-known methods. Here we make a comparative...

  12. Geometry of exponential family nonlinear models and some asymptotic inference

    Institute of Scientific and Technical Information of China (English)

    韦博成

    1995-01-01

    A differential geometric framework in Euclidean space for exponential family nonlinear models is presented. Based on this framework, some asymptotic inference related to statistical curvatures and Fisher information are studied. This geometric framework can also be extended to more genera) dass of models and used to study some other problems.

  13. Exponentially Localized Wannier Functions in Periodic Zero Flux Magnetic Fields

    CERN Document Server

    De Nittis, Giuseppe

    2011-01-01

    n this work, we investigate conditions which ensure the existence of an exponentially localized Wannier basis for a given periodic hamiltonian. We extend previous results [Pan07, Kuc09] to include periodic zero flux magnetic fields. The new notion of magnetic symmetry plays a crucial r\\^ole; to a large class of symmetries for a non-magnetic system, one can associate "magnetic" symmetries of the related magnetic system. Observing that the existence of an exponentially localized Wannier basis is equivalent to the triviality of the so-called Bloch bundle, a rank m hermitian vector bundle over the Brillouin zone, we prove that magnetic time-reversal symmetry is sufficient to ensure the triviality of the Bloch bundle in spatial dimension d = 1, 2, 3. For d = 4, an exponentially localized Wannier basis exists provided that the trace per unit volume of a suitable function of the Fermi projection vanishes. For d > 4 and d \\leq 2m (stable rank regime) only the exponential localization of a subset of Wannier functions ...

  14. Fine Tuning in Quintessence Models with Exponential Potentials

    CERN Document Server

    Rosenfeld, R; Jr., Urbano Lopes Franca; Rosenfeld, Rogerio

    2002-01-01

    We show that there still are reasonable regions of the parameter space of the simple exponential potential model for quintessence that are allowed by observational constraints. We find that the level of fine tuning that is required in this model is not too stringent.

  15. Exponentially Fitted Variants of Euler's Method for ODEs

    Science.gov (United States)

    Kanwar, V.; Tomar, S. K.

    2008-01-01

    A new class of Euler's method for the numerical solution of ordinary differential equations is presented in this article. The methods are iterative in nature and admit their geometric derivation from an exponentially fitted osculating straight line. They are single-step methods and do not require evaluation of any derivatives. The accuracy and…

  16. Meet and Join Matrices in the Poset of Exponential Divisors

    Indian Academy of Sciences (India)

    Ismo Korkee; Pentti Haukkanen

    2009-06-01

    It is well-known that $(\\mathbb{Z}_+,|)=(\\mathbb{Z}_+,GCD,LCM)$ is a lattice, where $|$ is the usual divisibility relation and $GCD$ and $LCM$ stand for the greatest common divisor and the least common multiple of positive integers. The number $d=\\prod^r_{k=1}p^{d^{(k)}}_k$ is said to be an exponential divisor or an -divisor of $n=\\prod^r_{k=1}p^{n^{(k)}}_k(n >1)$, written as $d|_e n$, if $d^{(k)}|n^{(k)}$ for all prime divisors $p_k$ of . It is easy to see that $(\\mathbb{Z}_+\\backslash\\{1\\},|_e)$ is a poset under the exponential divisibility relation but not a lattice, since the greatest common exponential divisor $(GCED)$ and the least common exponential multiple $(LCEM)$ do not always exist. In this paper we embed this poset in a lattice. As an application we study the $GCED$ and $LCEM$ matrices, analogues of $GCD$ and $LCM$ matrices, which are both special cases of meet and join matrices on lattices.

  17. Approximating Exponential and Logarithmic Functions Using Polynomial Interpolation

    Science.gov (United States)

    Gordon, Sheldon P.; Yang, Yajun

    2017-01-01

    This article takes a closer look at the problem of approximating the exponential and logarithmic functions using polynomials. Either as an alternative to or a precursor to Taylor polynomial approximations at the precalculus level, interpolating polynomials are considered. A measure of error is given and the behaviour of the error function is…

  18. Einstein Static Universe in Exponential $f(T)$ Gravity

    CERN Document Server

    Li, Jung-Tsung; Geng, Chao-Qiang

    2013-01-01

    We analyze the stability of the Einstein static closed and open universe in two types of exponential $f(T)$ gravity theories. We show that the stable solutions exist in these two models. In particular, we find that large regions of parameter space in equation of state $w=p/\\rho$ for the stable universe are allowed in the $f(T)$ theories.

  19. Einstein static universe in exponential f(T) gravity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jung-Tsung; Lee, Chung-Chi; Geng, Chao-Qiang [National Tsing Hua University, Department of Physics, Hsinchu (China); National Center for Theoretical Sciences, Physics Division, Hsinchu (China)

    2013-02-15

    We analyze the stability of the Einstein static closed and open universe in two types of exponential f(T) gravity theory. We show that stable solutions exist in these two models. In particular, we find that large regions of parameter space in equation of state w=p/{rho} for the stable universe are allowed in the f(T) theories. (orig.)

  20. The universe evolution in exponential $F(R)$-gravity

    CERN Document Server

    Bamba, K; Myrzakulov, R; Odintsov, S D; Sebastiani, L

    2013-01-01

    A generic feature of viable exponential $F(R)$-gravity is investigated. An additional modification to stabilize the effective dark energy oscillations during matter era is proposed and applied to two viable models. An analysis on the future evolution of the universe is performed. Furthermore, a unified model for early and late-time acceleration is proposed and studied.

  1. Exact Exponential-Time Algorithms for Domination Problems in Graphs

    NARCIS (Netherlands)

    van Rooij, J.M.M.

    2011-01-01

    This PhD thesis studies exact exponential-time algorithms for domination problems in graphs. Domination problems in graphs are a special kind of subset problems in graphs. A subset problem in a graph is a problem where one is given a graph G=(V,E), and one is asked whether there exist some subset S

  2. Electron traps in semiconducting polymers: exponential versus Gaussian trap distribution

    NARCIS (Netherlands)

    Nicolai, H.T.; Mandoc, M.M.; Blom, P.W.M.

    2011-01-01

    The low electron currents in poly(dialkoxy-p-phenylene vinylene) (PPV) derivatives and their steep voltage dependence are generally explained by trap-limited conduction in the presence of an exponential trap distribution. Here we demonstrate that the electron transport of several PPV derivatives can

  3. Electron traps in semiconducting polymers : Exponential versus Gaussian trap distribution

    NARCIS (Netherlands)

    Nicolai, H. T.; Mandoc, M. M.; Blom, P. W. M.

    2011-01-01

    The low electron currents in poly(dialkoxy-p-phenylene vinylene) (PPV) derivatives and their steep voltage dependence are generally explained by trap-limited conduction in the presence of an exponential trap distribution. Here we demonstrate that the electron transport of several PPV derivatives can

  4. Using Logarithms to Explore Power and Exponential Functions.

    Science.gov (United States)

    Rahn, James R.; Berndes, Barry A.

    1994-01-01

    Discusses activities to help students make visual generalizations about power and exponential functions, methods to determine an approximate function represented by data using logarithms, hands-on activities, and student activity sheets. Includes a Pascal Turbo computer program which generates random numbers. (MKR)

  5. Long-lasting Exponential Spreading in Periodically Driven Quantum Systems

    CERN Document Server

    Wang, Jiao; Casati, Giulio; Gong, Jiangbin; 10.1103/PhysRevLett.107.234104

    2012-01-01

    Using a dynamical model relevant to cold-atom experiments, we show that long-lasting exponential spreading of wave packets in momentum space is possible. Numerical results are explained via a pseudo-classical map, both qualitatively and quantitatively. Possible applications of our findings are also briefly discussed.

  6. An Exponentially Weighted Moving Average Control Chart for Bernoulli Data

    DEFF Research Database (Denmark)

    Spliid, Henrik

    2010-01-01

    We consider a production process in which units are produced in a sequential manner. The units can, for example, be manufactured items or services, provided to clients. Each unit produced can be a failure with probability p or a success (non-failure) with probability (1-p). A novel exponentially...

  7. Cycles in Repeated Exponentiation Modulo $p^n$

    CERN Document Server

    Glebsky, Lev

    2010-01-01

    Given a number $r$, we consider the dynamical system generated by repeated exponentiations modulo $r$, that is, by the map $u \\mapsto f_g(u)$, where $f_g(u) \\equiv g^u \\pmod r$ and $0 \\le f_g(u) \\le r-1$. The number of cycles of the defined above dynamical system is considered for $r=p^n$.

  8. Loss of exponential stability for a thermoelastic system with memory

    Directory of Open Access Journals (Sweden)

    Bruno Ferreira Alves

    2010-09-01

    Full Text Available In this article we study a thermoelastic system considering the linearized model proposed by Gurtin and Pipkin [8] instead of the Fourier's law for the heat flux. We use theory of semigroups [9, 11] combining Pruss' Theorem [10] and the idea developed in [5] to show that the system is not exponentially stable.

  9. A simple proof of Renner's exponential de Finetti theorem

    OpenAIRE

    Vidick, Thomas; Yuen, Henry

    2016-01-01

    We give a simple proof of the exponential de Finetti theorem due to Renner. Like Renner's proof, ours combines the post-selection de Finetti theorem, the Gentle Measurement lemma, and the Chernoff bound, but avoids virtually all calculations, including any use of the theory of types.

  10. Quadratic Lyapunov Function and Exponential Dichotomy on Time Scales

    Institute of Scientific and Technical Information of China (English)

    ZHANG JI; LIU ZHEN-XIN

    2011-01-01

    In this paper, we study the relationship between exponential dichotomy and quadratic Lyapunov function for the linear equation x△ = A(t)x on time scales.Moreover, for the nonlinear perturbed equation x△ = A(t)x + f(t,x) we give the instability of the zero solution when f is sufficiently small.

  11. An Exponentially Small $\\mu$--term in String Theory

    CERN Document Server

    Halyo, Edi

    2009-01-01

    We describe a mechanism that produces an exponentially small $\\mu$--term on the world--volumes of D5 branes wrapping a deformed and fibered $A_3$ singularity. The small $\\mu$ arises due to brane instanton effects which can be calculated after a geometric transition at one of the nodes of the singularity.

  12. EXPONENTIAL STABILITY OF INTERVAL DYNAMICAL SYSTEM WITH MULTIDELAY

    Institute of Scientific and Technical Information of China (English)

    孙继涛; 张银萍; 刘永清; 邓飞其

    2002-01-01

    Using the matrix measure and delay differential inequality, the sufficient conditions were obtained for exponential stability of interval dynamical system with multidelay. These conditions are an improvement and extension of the results achieved in earlier papers presented by LIAO, LIU, ZHANG, SUN, et al.

  13. The Harmonic Decomposition Reconstruction for the Exponential Radon Transform

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The exponential Radon transform, a generalization of the Radon transform, is defined andstudied as a mapping of function spaces. It is represented in terms of Fourier transform of its domain andrange, and this leads to the harmonic decomposition reconstruction. The results are similar results of Tre-tiak and Metz.

  14. Exponential Stabilization for C0 -Semigroups Under Compact Perturbation

    Institute of Scientific and Technical Information of China (English)

    LILT Li-xin

    2008-01-01

    It is proved that a system under compact perturbation cannot be uniformly exponentially stable for an isometric C0-semigroup or a C0-group with polynomial growth for negative time in a Banach space. The results extend and improve the corresponding results of previous literature.

  15. Minimal requirements for exponential growth of Lactococcus lactis

    DEFF Research Database (Denmark)

    Jensen, Peter Ruhdal; Hammer, Karin

    1993-01-01

    A minimal growth medium containing glucose, acetate, vitamins, and eight amino acids allowed for growth of Lactococcus lactis subsp. lactis, with a specific growth rate in batch culture of mu = 0.3 h-1. With 19 amino acids added, the growth rate increased to mu = 0.7 h-1 and the exponential growth...

  16. Weinstein-Sobolev Spaces of Exponential Type and Applications

    Institute of Scientific and Technical Information of China (English)

    Hassen BEN MOHAMED; Belgacem GHRIBI

    2013-01-01

    In this paper,we introduce and study the Sobolev spaces of exponential type associated with the Weinstein operator,via some elements of harmonic analysis related to this operator.In particular,some properties,including completeness and imbedding theorem,are proved.Finally,using the theory of reproducing kernels,some applications are given for these spaces.

  17. Approximating Exponential and Logarithmic Functions Using Polynomial Interpolation

    Science.gov (United States)

    Gordon, Sheldon P.; Yang, Yajun

    2017-01-01

    This article takes a closer look at the problem of approximating the exponential and logarithmic functions using polynomials. Either as an alternative to or a precursor to Taylor polynomial approximations at the precalculus level, interpolating polynomials are considered. A measure of error is given and the behaviour of the error function is…

  18. On some Vongruence with Application to Exponential Sums

    Indian Academy of Sciences (India)

    Soon-Mo Jung

    2004-02-01

    We will study the solution of a congruence, $x≡ g^{(1/2)_g(2^n)}\\mathrm{mod} 2^n$, depending on the integers and , where $_g(2^n)$ denotes the order of modulo $2^n$. Moreover, we introduce an application of the above result to the study of an estimation of exponential sums.

  19. Exponential stability of dynamic equations on time scales

    Directory of Open Access Journals (Sweden)

    Raffoul Youssef N

    2005-01-01

    Full Text Available We investigate the exponential stability of the zero solution to a system of dynamic equations on time scales. We do this by defining appropriate Lyapunov-type functions and then formulate certain inequalities on these functions. Several examples are given.

  20. Exponential decay for solutions to semilinear damped wave equation

    KAUST Repository

    Gerbi, Stéphane

    2011-10-01

    This paper is concerned with decay estimate of solutions to the semilinear wave equation with strong damping in a bounded domain. Intro- ducing an appropriate Lyapunov function, we prove that when the damping is linear, we can find initial data, for which the solution decays exponentially. This result improves an early one in [4].

  1. The generalized exponential function and fractional trigonometric identities

    KAUST Repository

    Radwan, Ahmed G.

    2011-08-01

    In this work, we recall the generalized exponential function in the fractional-order domain which enables defining generalized cosine and sine functions. We then re-visit some important trigonometric identities and generalize them from the narrow integer-order subset to the more general fractional-order domain. Generalized hyperbolic function relations are also given. © 2011 IEEE.

  2. The exponential age distribution and the Pareto firm size distribution

    OpenAIRE

    Coad, Alex

    2008-01-01

    Recent work drawing on data for large and small firms has shown a Pareto distribution of firm size. We mix a Gibrat-type growth process among incumbents with an exponential distribution of firm’s age, to obtain the empirical Pareto distribution.

  3. Modelling income data using two extensions of the exponential distribution

    Science.gov (United States)

    Calderín-Ojeda, Enrique; Azpitarte, Francisco; Gómez-Déniz, Emilio

    2016-11-01

    In this paper we propose two extensions of the Exponential model to describe income distributions. The Exponential ArcTan (EAT) and the composite EAT-Lognormal models discussed in this paper preserve key properties of the Exponential model including its capacity to model distributions with zero incomes. This is an important feature as the presence of zeros conditions the modelling of income distributions as it rules out the possibility of using many parametric models commonly used in the literature. Many researchers opt for excluding the zeros from the analysis, however, this may not be a sensible approach especially when the number of zeros is large or if one is interested in accurately describing the lower part of the distribution. We apply the EAT and the EAT-Lognormal models to study the distribution of incomes in Australia for the period 2001-2012. We find that these models in general outperform the Gamma and Exponential models while preserving the capacity of the latter to model zeros.

  4. RMS slope of exponentially correlated surface roughness for radar applications

    DEFF Research Database (Denmark)

    Dierking, Wolfgang

    2000-01-01

    In radar signature analysis, the root mean square (RMS) surface slope is utilized to assess the relative contribution of multiple scattering effects. For an exponentially correlated surface, an effective RMS slope can be determined by truncating the high frequency tail of the roughness spectrum...

  5. The algorithm of decomposing superimposed 2-D Poisson processes and its application to the extracting earthquake clustering pattern

    Institute of Scientific and Technical Information of China (English)

    裴韬; 周成虎; 杨明; 骆剑承; 李全林

    2004-01-01

    Aiming at the complexity of seismic gestation mechanism and spatial distribution, we hypothesize that the seismic data are composed of background earthquakes and anomaly earthquakes in a certain temporal-spatial scope. Also the background earthquakes and anomaly earthquakes both satisfy the 2-D Poisson process of different parameters respectively. In the paper, the concept of N-th order distance is introduced in order to transform 2-D superimposed Poisson process into 1-D mixture density function. On the basis of choosing the distance, mixture density function is decomposed to recognize the anomaly earthquakes through genetic algorithm. Combined with the temporal scanning of C value, the algorithm is applied to the recognition on spatial pattern of foreshock anomalies by examples of Songpan and Longling sequences in the southwest of China.

  6. Black-spot poison ivy dermatitis. An acute irritant contact dermatitis superimposed upon an allergic contact dermatitis.

    Science.gov (United States)

    Hurwitz, R M; Rivera, H P; Guin, J D

    1984-08-01

    A black spot in the epidermis over a blister of poison ivy dermatitis is an uncommon finding. Four patients with the phenomenon are described. Histologic and histochemical studies were made on biopsy material and the blackish deposit on the skin surface was compared with black deposits in and on leaves of the species of poison ivy. This examination revealed a yellow, amorphous substance on the stratum corneum of the lesions and a similar substance in and on leaves of the poison ivy plant, Toxicodendron radicans ssp. negundo. Associated with the pigmentary deposits there were distinct changes of acute irritant contact dermatitis superimposed upon allergic contact dermatitis. Our findings support the view that the black material is the oleoresin of the plant, and that this substance behaves both as an irritant and an allergen.

  7. Nuclear counting filter based on a centered Skellam test and a double exponential smoothing

    Energy Technology Data Exchange (ETDEWEB)

    Coulon, Romain; Kondrasovs, Vladimir; Dumazert, Jonathan; Rohee, Emmanuel; Normand Stephane [CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, F-91191 Gif-sur-Yvette, (France)

    2015-07-01

    Online nuclear counting represents a challenge due to the stochastic nature of radioactivity. The count data have to be filtered in order to provide a precise and accurate estimation of the count rate, this with a response time compatible with the application in view. An innovative filter is presented in this paper addressing this issue. It is a nonlinear filter based on a Centered Skellam Test (CST) giving a local maximum likelihood estimation of the signal based on a Poisson distribution assumption. This nonlinear approach allows to smooth the counting signal while maintaining a fast response when brutal change activity occur. The filter has been improved by the implementation of a Brown's double Exponential Smoothing (BES). The filter has been validated and compared to other state of the art smoothing filters. The CST-BES filter shows a significant improvement compared to all tested smoothing filters. (authors)

  8. Metallogenetic Mechanism and Timing of Late Superimposing Fluid Mineralization in the Dongguashan Diplogenetic Stratified Copper Deposit, Anhui Province

    Institute of Scientific and Technical Information of China (English)

    XU Zhaowen; LU Xiancai; LING Hongfei; LU Jianjun; JIANG Shoyong; NIE Guiping; HUANG Shunsheng; HUA Ming

    2005-01-01

    An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of the Yangtze Block during 140-135 Ma under extensional tectonic circumstances following the collision between the North China and Yangtze blocks. The main orebodies of the Dongguashan copper deposit, a typical diplogenetic stratified deposit among many polymetallic ore deposits in China, are hosted by strata between Upper Devonian sandstone and Carboniferous limestone, and its mineralization was genetically related to the Qingshanjiao intrusive. The Rb-Sr isotopic isochron of the Qingshanjiao intrusive yields an age of about 136.5±1.4 Ma. The ore-forming fluid reflected by the inclusion fluid in quartz veins is characterized by high temperature and high salinity, and its age was also determined by Rb-Sr isotope dating as 134±11 Ma. Oxygen and hydrogen isotope composition data suggest that the ore-forming fluid was derived mainly from magmatism. By integrating these isotopic dating data, characteristics of fluid inclusions and the geology of the deposit, the mineralization of the Dongguashan copper deposit is divided into two stages. First, a stratiform sedimentary deposit or protore layer formed in the Late Devonian to the Early Carboniferous, while in the second stage the pre-existing protore was superimposed by hydrothermal fluid that was derived from the Yanshanian magmatic activities occurring around 135 Ma ago. This two-stage mineralization formed the Dongguashan statiform copper deposit.Associated "porphyry" mineralization found in the bottom of and in surrounding intrusive rocks of the orebodies might have occurred in the same period as a second-stage mineralization of this deposit.

  9. Numerical Investigations on the Influence of Superimposed Double-Sided Pressure on the Formability of Biaxially Stretched AA6111-T4 Sheet Metal

    Science.gov (United States)

    Liu, Jianguang; Wang, Zhongjin; Meng, Qingyuan

    2012-04-01

    Lightweight materials have been widely used in aerospace, automobile industries to meet the requirement of structural weight reduction. Due to their limited plasticity at room temperature, however, lightweight materials always exhibit distinctly poor forming capability in comparison with conventional deep drawing steels. Based on the phenomenon that the superimposed hydrostatic pressure can improve the plasticity of metal, many kinds of double-sided pressure forming processes have been proposed. In the present study, the Gurson-Tvergaard-Needleman (GTN) damage model combined with finite element method is used to investigate the influence of double-sided pressure on the deformation behavior of biaxially stretched AA6111-T4 sheet metal, including nucleation and growth of microvoids, evaluation of stress triaxiality, and so forth. The Marciniak-Kuczynski (M-K) localized necking model is used to predict the right-hand side of the forming limit diagram (FLD) of sheet metal under superimposed double-sided pressure. It is found that the superimposed double-sided pressure has no obvious effect on the nucleation of microvoids. However, the superimposed double-sided pressure can suppress the growth and coalescence of microvoids. The forming limit curve (FLC) of the biaxially stretched AA6111-T4 sheet metal under the superimposed double-sided pressure is improved and the fracture locus shifts to the left. Furthermore, the formability increase value is sensitive to the strain path.

  10. Resolution of superimposed pre-eclampsia, and improvement in umbilical artery flow in a surviving twin after intrauterine demise of its co-twin.

    Science.gov (United States)

    Narasimhulu, Deepa M; Karakash, Scarlett; Rankin, Linda; Minkoff, Howard

    2015-09-01

    Pre-eclampsia has a progressive clinical course, and is only cured by delivery of the placenta. We report a 30-year-old G1P0 with dichorionic twins, discordant growth and chronic hypertension who developed superimposed pre-eclampsia in her 21st week of gestation. After intrauterine demise of the severely growth-restricted twin, the superimposed pre-eclampsia resolved. The surviving twin initially had absent end diastolic flow, which resolved after the demise. A healthy 1935-g neonate with Apgar 9/9 was delivered at 34 weeks. Antenatal resolution of pre-eclampsia is extremely rare and resolution of superimposed pre-eclampsia has not, to our knowledge, been reported.

  11. The scaling of human mobility by taxis is exponential

    CERN Document Server

    Liang, Xiao; Lv, Weifeng; Zhu, Tongyu; Xu, Ke

    2011-01-01

    As a significant factor in urban planning, traffic forecasting and prediction of epidemics, modeling patterns of human mobility draws intensive attention from researchers for decades. Power-law distribution and its variations are observed from quite a few real-world human mobility datasets such as the movements of banking notes, trackings of cell phone users' locations and trajectories of vehicles. In this paper, we build models for 20 million trajectories with fine granularity collected from more than 10 thousand taxis in Beijing. In contrast to most models observed in human mobility data, the taxis' traveling displacements in urban areas tend to follow an exponential distribution instead of a power-law. Similarly, the elapsed time can also be well approximated by an exponential distribution. Worth mentioning, analysis of the interevent time indicates the bursty nature of human mobility, similar to many other human activities.

  12. A stochastic evolutionary model generating a mixture of exponential distributions

    CERN Document Server

    Fenner, Trevor; Loizou, George

    2015-01-01

    Recent interest in human dynamics has stimulated the investigation of the stochastic processes that explain human behaviour in various contexts, such as mobile phone networks and social media. In this paper, we extend the stochastic urn-based model proposed in \\cite{FENN15} so that it can generate mixture models,in particular, a mixture of exponential distributions. The model is designed to capture the dynamics of survival analysis, traditionally employed in clinical trials, reliability analysis in engineering, and more recently in the analysis of large data sets recording human dynamics. The mixture modelling approach, which is relatively simple and well understood, is very effective in capturing heterogeneity in data. We provide empirical evidence for the validity of the model, using a data set of popular search engine queries collected over a period of 114 months. We show that the survival function of these queries is closely matched by the exponential mixture solution for our model.

  13. THE JOINT DISTRIBUTION OF BIVARIATE EXPONENTIAL UNDER LINEARLY RELATED MODEL

    Directory of Open Access Journals (Sweden)

    Norou Diawara

    2010-09-01

    Full Text Available In this paper, fundamental results of the joint distribution of the bivariate exponential distributions are established.  The positive support multivariate distribution theory is important in reliability and survival analysis, and we applied it to the case where more than one failure or survival is observed in a given study. Usually, the multivariate distribution is restricted to those with marginal distributions of a specified and familiar lifetime family. The family of exponential distribution contains the absolutely continuous and discrete case models with a nonzero probability on a set of measure zero. Examples are given, and estimators are developed and applied to simulated data. Our findings generalize substantially known results in the literature, provide flexible and novel approach for modeling related events that can occur simultaneously from one based event.

  14. Handbook of exponential and related distributions for engineers and scientists

    CERN Document Server

    Pal, Nabendu; Lim, Wooi K

    2005-01-01

    The normal distribution is widely known and used by scientists and engineers. However, there are many cases when the normal distribution is not appropriate, due to the data being skewed. Rather than leaving you to search through journal articles, advanced theoretical monographs, or introductory texts for alternative distributions, the Handbook of Exponential and Related Distributions for Engineers and Scientists provides a concise, carefully selected presentation of the properties and principles of selected distributions that are most useful for application in the sciences and engineering.The book begins with all the basic mathematical and statistical background necessary to select the correct distribution to model real-world data sets. This includes inference, decision theory, and computational aspects including the popular Bootstrap method. The authors then examine four skewed distributions in detail: exponential, gamma, Weibull, and extreme value. For each one, they discuss general properties and applicabi...

  15. Exponentially fitted explicit Runge-Kutta-Nystrom methods

    Science.gov (United States)

    Franco, J. M.

    2004-05-01

    Exponentially fitted Runge-Kutta-Nystrom (EFRKN) methods for the numerical integration of second-order IVPs with oscillatory solutions are derived. These methods integrate exactly differential systems whose solutions can be expressed as linear combinations of the set of functions {exp(λt),exp(-λt)}, , or equivalently {sin(ωt),cos(ωt)} when λ=iω, . Explicit EFRKN methods with two and three stages and algebraic orders 3 and 4 are constructed. In addition, a 4(3) embedded pair of explicit EFRKN methods based on the FSAL technique is obtained, which permits to introduce an error and step length control with a small cost added. Some numerical experiments show the efficiency of our explicit EFRKN methods when they are compared with other exponential fitting type codes proposed in the scientific literature.

  16. Statistical region-based active contours with exponential family observations

    CERN Document Server

    Lecellier, François; Fadili, Jalal; Aubert, Gilles; Revenu, Marinette

    2008-01-01

    In this paper, we focus on statistical region-based active contour models where image features (e.g. intensity) are random variables whose distribution belongs to some parametric family (e.g. exponential) rather than confining ourselves to the special Gaussian case. Using shape derivation tools, our effort focuses on constructing a general expression for the derivative of the energy (with respect to a domain) and derive the corresponding evolution speed. A general result is stated within the framework of multi-parameter exponential family. More particularly, when using Maximum Likelihood estimators, the evolution speed has a closed-form expression that depends simply on the probability density function, while complicating additive terms appear when using other estimators, e.g. moments method. Experimental results on both synthesized and real images demonstrate the applicability of our approach.

  17. A recursion identity for formal iterated logarithms and iterated exponentials

    CERN Document Server

    Robinson, Thomas J

    2010-01-01

    We prove a recursive identity involving formal iterated logarithms and formal iterated exponentials. These iterated logarithms and exponentials appear in a natural extension of the logarithmic formal calculus used in the study of logarithmic intertwining operators and logarithmic tensor category theory for modules for a vertex operator algebra. This extension has a variety of interesting arithmetic properties. We develop one such result here, the aforementioned recursive identity. We have applied this identity elsewhere to certain formal series expansions related to a general formal Taylor theorem and these series expansions in turn yield a sequence of combinatorial identities which have as special cases certain classical combinatorial identities involving (separately) the Stirling numbers of the first and second kinds.

  18. THE SENSITIVITY OF THE EXPONENTIAL OF AN ESSENTIALLY NONNEGATIVE MATRIX

    Institute of Scientific and Technical Information of China (English)

    Weifang Zhu; Jungong Xue; Weiguo Gao

    2008-01-01

    This paper performs perturbation analysis for the exponential of an essentially nonnegative matrix which is perturbed in the way that each entry has a small relative perturbation.For a general essentially nonnegative matrix,we obtain an upper bound for the relative error in 2-norm,which is sharper than the existing perturbation results.For a triangular essentially nonnegative matrix,we obtain an upper bound for the relative error in entrywise sense.This bound indicates that,if the spectral radius of an essentially nonnegative matrix is not large,then small entrywise relative perturbations cause small relative error in each entry of its exponential.Finally,we apply our perturbation results to the sensitivity analysis of RC networks and complementary distribution functions of phase-type distributions.

  19. Interval Estimations of the Two-Parameter Exponential Distribution

    Directory of Open Access Journals (Sweden)

    Lai Jiang

    2012-01-01

    Full Text Available In applied work, the two-parameter exponential distribution gives useful representations of many physical situations. Confidence interval for the scale parameter and predictive interval for a future independent observation have been studied by many, including Petropoulos (2011 and Lawless (1977, respectively. However, interval estimates for the threshold parameter have not been widely examined in statistical literature. The aim of this paper is to, first, obtain the exact significance function of the scale parameter by renormalizing the p∗-formula. Then the approximate Studentization method is applied to obtain the significance function of the threshold parameter. Finally, a predictive density function of the two-parameter exponential distribution is derived. A real-life data set is used to show the implementation of the method. Simulation studies are then carried out to illustrate the accuracy of the proposed methods.

  20. Historical remarks on exponential product and quantum analysis

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Masuo [Computational Astrophysics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2015-03-10

    The exponential product formula [1, 2] was substantially introduced in physics by the present author [2]. Its systematic applications to quantum Monte Carlo Methods [3] were preformed [4, 5] first in 1977. Many interesting applications [6] of the quantum-classical correspondence (namely S-T transformation) have been reported. Systematic higher-order decomposition formulae were also discovered by the present author [7-11], using the recursion scheme [7, 9]. Physically speaking, these exponential product formulae play a conceptual role of separation of procedures [3,14]. Mathematical aspects of these formulae have been integrated in quantum analysis [15], in which non-commutative differential calculus is formulated and a general quantum Taylor expansion formula is given. This yields many useful operator expansion formulae such as the Feynman expansion formula and the resolvent expansion. Irreversibility and entropy production are also studied using quantum analysis [15].

  1. Exponential time-dependent perturbation theory in rotationally inelastic scattering

    Science.gov (United States)

    Cross, R. J.

    1983-08-01

    An exponential form of time-dependent perturbation theory (the Magnus approximation) is developed for rotationally inelastic scattering. A phase-shift matrix is calculated as an integral in time over the anisotropic part of the potential. The trajectory used for this integral is specified by the diagonal part of the potential matrix and the arithmetic average of the initial and final velocities and the average orbital angular momentum. The exponential of the phase-shift matrix gives the scattering matrix and the various cross sections. A special representation is used where the orbital angular momentum is either treated classically or may be frozen out to yield the orbital sudden approximation. Calculations on Ar+N2 and Ar+TIF show that the theory generally gives very good agreement with accurate calculations, even where the orbital sudden approximation (coupled-states) results are seriously in error.

  2. Truncated $\\gamma$-exponential models for tidal stellar systems

    CERN Document Server

    Gomez-Leyton, Y J

    2016-01-01

    We introduce a parametric family of models to characterize the properties of astrophysical systems in a quasi-stationary evolution under the incidence evaporation. We start from an one-particle distribution $f_{\\gamma}\\left(\\mathbf{q},\\mathbf{p}|\\beta,\\varepsilon_{s}\\right)$ that considers an appropriate deformation of Maxwell-Boltzmann form with inverse temperature $\\beta$, in particular, a power-law truncation at the scape energy $\\varepsilon_{s}$ with exponent $\\gamma>0$. This deformation is implemented using a generalized $\\gamma$-exponential function obtained from the \\emph{fractional integration} of ordinary exponential. As shown in this work, this proposal generalizes models of tidal stellar systems that predict particles distributions with \\emph{isothermal cores and polytropic haloes}, e.g.: Michie-King models. We perform the analysis of thermodynamic features of these models and their associated distribution profiles. A nontrivial consequence of this study is that profiles with isothermal cores and p...

  3. The scaling of human mobility by taxis is exponential

    Science.gov (United States)

    Liang, Xiao; Zheng, Xudong; Lv, Weifeng; Zhu, Tongyu; Xu, Ke

    2012-03-01

    As a significant factor in urban planning, traffic forecasting and prediction of epidemics, modeling patterns of human mobility draws intensive attention from researchers for decades. Power-law distribution and its variations are observed from quite a few real-world human mobility datasets such as the movements of banking notes, trackings of cell phone users' locations and trajectories of vehicles. In this paper, we build models for 20 million trajectories with fine granularity collected from more than 10 thousand taxis in Beijing. In contrast to most models observed in human mobility data, the taxis' traveling displacements in urban areas tend to follow an exponential distribution instead of a power-law. Similarly, the elapsed time can also be well approximated by an exponential distribution. Worth mentioning, analysis of the interevent time indicates the bursty nature of human mobility, similar to many other human activities.

  4. Excitation of a single atom with exponentially rising light pulses

    CERN Document Server

    Aljunid, Syed Abdullah

    2013-01-01

    We investigate the interaction between a single atom and optical pulses in a coherent state with a controlled temporal envelope. In a comparison between a rising exponential and a square envelope, we show that the rising exponential envelope leads to a higher excitation probability for fixed low average photon numbers, in accordance to a time-reversed Weisskopf-Wigner model. We characterize the atomic transition dynamics for a wide range of the average photon numbers, and are able to saturate the optical transition of a single atom with ~50 photons in a pulse by a strong focusing technique. For photon numbers of ~1000 in a 15ns long pulse, we clearly observe Rabi oscillations.

  5. On the exponential of matrices in su(4)

    Energy Technology Data Exchange (ETDEWEB)

    Ramakrishna, Viswanath; Zhou, Hong [Department of Mathematical Sciences and Center for Signals, Systems and Communications, University of Texas at Dallas, PO Box 830688, Richardson, TX 75083 (United States)

    2006-03-24

    This paper provides explicit techniques to compute the exponentials of a variety of anti-Hermitian matrices in dimension 4. Many of these formulae can be written down directly from the entries of the matrix. Whenever any spectral calculations are required, these can be done in closed form. In many instances only 2 x 2 spectral calculations are required. These formulae cover a wide variety of applications. Conditions on the matrix which render it to admit one of three minimal polynomials are also given. Matrices with these minimal polynomials admit simple and tractable representations for their exponentials. One of these is the Euler-Rodrigues formula. The key technique is the relation between real 4 x 4 matrices and the quaternions.

  6. Robust exponential control of a class of systems with uncertainties

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The robust exponential stabilization problem for uncertain systems is studied. Based on the solution for a nominal linear quadratic regulator problem with a prescribed degree of stability, the methods of constructing state feedback controllers are developed to ensure the robust stability of the closed loop system under the conditions weaker than the matching condition. Also, the cases where the matching condition is satisfied are considered in detail. Some examples are included to show the solution methods.

  7. Exponential Stability of Complex-Valued Memristive Recurrent Neural Networks.

    Science.gov (United States)

    Wang, Huamin; Duan, Shukai; Huang, Tingwen; Wang, Lidan; Li, Chuandong

    2017-03-01

    In this brief, we establish a novel complex-valued memristive recurrent neural network (CVMRNN) to study its stability. As a generalization of real-valued memristive neural networks, CVMRNN can be separated into real and imaginary parts. By means of M -matrix and Lyapunov function, the existence, uniqueness, and exponential stability of the equilibrium point for CVMRNNs are investigated, and sufficient conditions are presented. Finally, the effectiveness of obtained results is illustrated by two numerical examples.

  8. Modified Binary Exponential Backoff Algorithm to Minimize Mobiles Communication Time

    OpenAIRE

    Ibrahim Sayed Ahmad; Ali Kalakech; Seifedine Kadry

    2014-01-01

    the field of Wireless Local Area Networks (LANs) is expanding rapidly as a result of advances in digital communications, portable computers, and semiconductor technology. The early adopters of this technology have primarily been vertical application that places a premium on the mobility offered by such systems. Binary Exponential Backoff (BEB) refers to a collision resolution mechanism used in random access MAC protocols. This algorithm is used in Ethernet (IEEE 802.3) wired LANs. In Ethe...

  9. Fractal structures in a generalized square map with exponential terms

    Institute of Scientific and Technical Information of China (English)

    Li Xian-Feng; Chu Yan-Dong; Zhang Hui

    2012-01-01

    Fractal structures in a generalized squared map with exponential terms are expanded in this paper.We describe how complex behaviors can arise as the parameters change.The appearances of different kinds of fractal structures,in both the attractive and the divergent regions,and most interestingly,on small regular islands embedded in the chaotic region,are manifested to have a variety of extraordinary geometries in the parameter plane.

  10. Inverse Problems for Matrix Exponential in System Identification: System Aliasing

    OpenAIRE

    Yue, Zuogong; Thunberg, Johan; Goncalves, Jorge

    2016-01-01

    This note addresses identification of the $A$-matrix in continuous time linear dynamical systems on state-space form. If this matrix is partially known or known to have a sparse structure, such knowledge can be used to simplify the identification. We begin by introducing some general conditions for solvability of the inverse problems for matrix exponential. Next, we introduce "system aliasing" as an issue in the identification of slow sampled systems. Such aliasing give rise to non-unique mat...

  11. Exponential Inequalities for Positively Associated Random Variables and Applications

    Directory of Open Access Journals (Sweden)

    Yang Shanchao

    2008-01-01

    Full Text Available Abstract We establish some exponential inequalities for positively associated random variables without the boundedness assumption. These inequalities improve the corresponding results obtained by Oliveira (2005. By one of the inequalities, we obtain the convergence rate for the case of geometrically decreasing covariances, which closes to the optimal achievable convergence rate for independent random variables under the Hartman-Wintner law of the iterated logarithm and improves the convergence rate derived by Oliveira (2005 for the above case.

  12. Short Cycles in Repeated Exponentiation Modulo a Prime

    CERN Document Server

    Glebsky, Lev

    2009-01-01

    Given a prime $p$, we consider the dynamical system generated by repeated exponentiations modulo $p$, that is, by the map $u \\mapsto f_g(u)$, where $f_g(u) \\equiv g^u \\pmod p$ and $0 \\le f_g(u) \\le p-1$. This map is in particular used in a number of constructions of cryptographically secure pseudorandom generators. We obtain nontrivial upper bounds on the number of fixed points and short cycles in the above dynamical system.

  13. EXPONENTIAL ESTIMATES FOR STOCHASTIC DELAY HYBRID SYSTEMS WITH MARKOVIAN SWITCHING

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper deals with the problem of norm bounds for the solutions of stochastic hybrid systems with Markovian switching and time delay. Based on Lyapunov-Krasovskii theory for functional differential equations and the linear matrix inequality (LMI) approach, mean square exponential estimates for the solutions of this class of linear stochastic hybrid systems are derived. Finally, An example is illustrated to show the applicability and effectiveness of our method.

  14. Tachyonic matter cosmology with exponential and hyperbolic potentials

    Science.gov (United States)

    Pourhassan, B.; Naji, J.

    In this paper, we consider tachyonic matter in spatially flat Friedmann-Robertson-Walker (FRW) universe, and obtain behavior of some important cosmological parameters for two special cases of potentials. First, we assume the exponential potential and then consider hyperbolic cosine type potential. In both cases, we obtain behavior of the Hubble, deceleration and EoS parameters. Comparison with observational data suggest the model with hyperbolic cosine type scalar field potentials has good model to describe universe.

  15. An exponential polynomial observer for synchronization of chaotic systems

    Science.gov (United States)

    Mata-Machuca, J. L.; Martínez-Guerra, R.; Aguilar-López, R.

    2010-12-01

    In this paper, we consider the synchronization problem via nonlinear observer design. A new exponential polynomial observer for a class of nonlinear oscillators is proposed, which is robust against output noises. A sufficient condition for synchronization is derived analytically with the help of Lyapunov stability theory. The proposed technique has been applied to synchronize chaotic systems (Rikitake and Rössler systems) by means of numerical simulation.

  16. INFLUENCE ANALYSIS ON EXPONENTIAL NONLINEAR MODELS WITH RANDOM EFFECTS

    Institute of Scientific and Technical Information of China (English)

    宗序平; 赵俊; 王海斌; 韦博成

    2003-01-01

    This paper presents a unified diagnostic method for exponential nonlinear models with random effects based upon the joint likelihood given by Robinson in 1991.The authors show that the case deletion model is equivalent to mean shift outlier model.From this point of view,several diagnostic measures,such as Cook distance,score statistics are derived.The local influence measure of Cook is also presented.Numerical example illustrates that our method is available.

  17. Chaos and Exponentially Localized Eigenstates in Smooth Hamiltonian Systems

    CERN Document Server

    Santhanam, M S; Lakshminarayan, A

    1998-01-01

    We present numerical evidence to show that the wavefunctions of smooth classically chaotic Hamiltonian systems scarred by certain simple periodic orbits are exponentially localized in the space of unperturbed basis states. The degree of localization, as measured by the information entropy, is shown to be correlated with the local phase space structure around the scarring orbit; indicating sharp localization when the orbit undergoes a pitchfork bifurcation and loses stability.

  18. Discrete power law with exponential cutoff and Lotka's Law

    CERN Document Server

    Smolinsky, Lawrence

    2015-01-01

    The first bibliometric law appeared in Alfred J. Lotka's 1926 examination of author productivity in chemistry and physics. The result is that the productivity distribution is thought to be described by a power law. In this paper, Lotka's original data on author productivity in chemistry is reconsidered by comparing the fit of the data to both a discrete power law and a discrete power law with exponential cutoff.

  19. Variable Selection with Exponential Weights and $l_0$-Penalization

    OpenAIRE

    Arias-Castro, Ery; Lounici, Karim

    2012-01-01

    In the context of a linear model with a sparse coefficient vector, exponential weights methods have been shown to be achieve oracle inequalities for prediction. We show that such methods also succeed at variable selection and estimation under the necessary identifiability condition on the design matrix, instead of much stronger assumptions required by other methods such as the Lasso or the Dantzig Selector. The same analysis yields consistency results for Bayesian methods and BIC-type variabl...

  20. A Spectral Lyapunov Function for Exponentially Stable LTV Systems

    Science.gov (United States)

    Zhu, J. Jim; Liu, Yong; Hang, Rui

    2010-01-01

    This paper presents the formulation of a Lyapunov function for an exponentially stable linear timevarying (LTV) system using a well-defined PD-spectrum and the associated PD-eigenvectors. It provides a bridge between the first and second methods of Lyapunov for stability assessment, and will find significant applications in the analysis and control law design for LTV systems and linearizable nonlinear time-varying systems.

  1. Epidemic Dynamics with Feedback Mechanism in Exponential Networks

    Institute of Scientific and Technical Information of China (English)

    LIU Zi-Ran; YAN Jia-Ren; ZHANG Jian-Guo; WANG Li

    2006-01-01

    @@ We introduce a feedback mechanism to study the spreading of an epidemic by analytical methods and large scale simulations in exponential networks. It is found that introducing the feedback mechanism can reduce the density of infected individuals. Furthermore, it does not change the epidemic threshold (critical point) λc. These results can help us to understand epidemic spreading phenomena on social networks more practically and design appropriate strategies to control social infections.

  2. Exponential wealth distribution : a new approach from functional iteration theory*

    Directory of Open Access Journals (Sweden)

    López José-Luis

    2012-08-01

    Full Text Available Different approaches are possible in order to derive the exponential regime in statistical systems. Here, a new functional equation is proposed in an economic context to explain the wealth exponential distribution. Concretely, the new iteration [1] given by egin{equation} f_{n+1}(x = int!!int_{u+v>x},{f_n(uf_n(vover u+v} ; {mathrm d}u{mathrm d}v ,. onumber label{syst1} end{equation} f n + 1 ( x = ∫ ∫ u + v > x   f n ( u f n ( v u + v d u d v   . It is found that the exponential distribution is a stable fixed point of this functional iteration equation. From this point of view, it is easily understood why the exponential wealth distribution (or by extension, other kind of distributions is asymptotically obtained in different multi-agent economic models. Différentes approches pour dériver le régime asymptotique exponentiel dans les systèmes statistiques sont possibles. Ici une nouvelle équation fonctionnelle est proposée, dans le cadre des systèmes économiques, pour expliquer la distribution exponentielle. Nous montrons que cette distribution est le seul point fixe vers lequel la dynamique de cette équation fonctionnelle évolue quand l’itération va vers l’infini. De ce point de vue, il est facile de comprendre l’ubiquité de cette distribution (ou d’autres en différents problèmes statistiques réels.

  3. Extracting the exponential behaviors in the market data

    CERN Document Server

    Watanabe, K; Takayasu, M; Watanabe, Kota; Takayasu, Hideki; Takayasu, Misako

    2006-01-01

    We introduce a mathematical criterion defining the bubbles or the crashes in financial market price fluctuations by considering exponential fitting of the given data. By applying this criterion we can automatically extract the periods in which bubbles and crashes are identified. From stock market data of so-called the Internet bubbles it is found that the characteristic length of bubble period is about 100 days.

  4. Evidence for Truncated Exponential Probability Distribution of Earthquake Slip

    KAUST Repository

    Thingbaijam, Kiran K. S.

    2016-07-13

    Earthquake ruptures comprise spatially varying slip on the fault surface, where slip represents the displacement discontinuity between the two sides of the rupture plane. In this study, we analyze the probability distribution of coseismic slip, which provides important information to better understand earthquake source physics. Although the probability distribution of slip is crucial for generating realistic rupture scenarios for simulation-based seismic and tsunami-hazard analysis, the statistical properties of earthquake slip have received limited attention so far. Here, we use the online database of earthquake source models (SRCMOD) to show that the probability distribution of slip follows the truncated exponential law. This law agrees with rupture-specific physical constraints limiting the maximum possible slip on the fault, similar to physical constraints on maximum earthquake magnitudes.We show the parameters of the best-fitting truncated exponential distribution scale with average coseismic slip. This scaling property reflects the control of the underlying stress distribution and fault strength on the rupture dimensions, which determines the average slip. Thus, the scale-dependent behavior of slip heterogeneity is captured by the probability distribution of slip. We conclude that the truncated exponential law accurately quantifies coseismic slip distribution and therefore allows for more realistic modeling of rupture scenarios. © 2016, Seismological Society of America. All rights reserverd.

  5. Exponential processes in human auditory excitation and adaptation.

    Science.gov (United States)

    Formby, C; Rutledge, J C; Sherlock, L P

    2002-02-01

    Peripheral auditory adaptation has been studied extensively in animal models, and multiple exponential components have been identified. This study explores the feasibility of estimating these component processes for human listeners with a peripheral model of adaptation. The processes were estimated from off-frequency masked detection data that probed temporal masking responses to a gated narrowband masker. The resulting response patterns reflected step-like onset and offset features with characteristically little evidence of confounding backward and forward masking. The model was implemented with linear combinations of exponential functions to represent the unadapted excitation response to gating the masker on and then off and the opposing effects of adaptation in each instance. The onset and offset of the temporal masking response were assumed to be approximately inverse operations and were modeled independently in this scheme. The unadapted excitation response at masker onset and the reversed excitation response at masker offset were each represented in the model by a single exponential function. The adaptation processes were modeled by three independent exponential functions, which were reversed at masker offset. Each adaptation component was subtractive and partially negated the unadapted excitation response to the dynamic masker. This scheme allowed for quantification of the response amplitude, action latency, and time constant for the unadapted excitation component and for each adaptation component. The results reveal that (1) the amplitudes of the unadapted excitation and reversed excitation components grow nonlinearly with masker level and mirror the 'compressive' input-output velocity response of the basilar membrane; (2) the time constants for the unadapted excitation and reversed excitation components are related inversely to masker intensity, which is compatible with neural synchrony increasing at masker onset (or offset) with increasing masker strength

  6. Cleaved DNAzyme substrate induced enzymatic cascade for the exponential amplified analysis of L-histidine.

    Science.gov (United States)

    He, Jing-Lin; Wu, Ping; Zhu, Shuang-Li; Li, Ting; Li, Pan-Pan; Xiang, Jian-Nan; Cao, Zhong

    2015-01-01

    A novel strategy of cleaved DNAzyme substrate induced enzymatic cascade has been devised for the exponential amplified detection of L-histidine. The enzyme strand carries out hydrolytic cleavage of the substrate strand in the presence of L-histidine. The cleaved DNAzyme substrates introduce the polymerase/endonuclease reaction cycles as primers. The L-histidine acts as the activator for enzymatic cascade amplification generating a distinguishable fluorescence enhancement. A good nonlinear correlation (R=0.9994) between fluorescence intensity and the logarithm of the L-histidine concentration is obtained over the range from 50 nM to 1.0 mM. The detection limit was estimated as 30 nM. This efficient amplification of the fluorescence signal is attributed to the L-histidine induced cooperation of Klenow Fragment polymerase (exo(-)) and Nb.BbvCI endonuclease reaction. The activation of such enzymatic cascades through analyte-DNAzyme interactions has a substantial impact on the development of exponential amplified DNAzyme sensors.

  7. Chemiluminescence imaging for microRNA detection based on cascade exponential isothermal amplification machinery.

    Science.gov (United States)

    Xu, Yongjie; Li, Dandan; Cheng, Wei; Hu, Rong; Sang, Ye; Yin, Yibing; Ding, Shijia; Ju, Huangxian

    2016-09-14

    A novel G-quadruplex DNAzyme-driven chemiluminescence (CL) imaging method was developed for ultrasensitive and specific detection of miRNA based on the cascade exponential isothermal amplification reaction (EXPAR) machinery. A structurally tailored hairpin probe switch was designed to selectively recognise miRNA and form hybridisation products to trigger polymerase and nicking enzyme machinery, resulting in the generation of product I, which was complementary to a region of the functional linear template. Then, the response of the functional linear template to the generated product I further activated the exponential isothermal amplification machinery, leading to synthesis of numerous horseradish peroxidase mimicking DNAzyme units for CL signal transduction. The amplification paradigm generated a linear response from 10 fM to 100 pM, with a low detection limit of 2.91 fM, and enabled discrimination of target miRNA from a single-base mismatched target. The developed biosensing platform demonstrated the advantages of isothermal, homogeneous, visual detection for miRNA assays, offering a promising tool for clinical diagnosis.

  8. Development of a prototype apparatus visualizing on a screen the gamma sources superimposed on the image of the vision field

    Energy Technology Data Exchange (ETDEWEB)

    Imbard, G.; Lemaire, J.E. [CEA Centre d`Etudes de la Vallee du Rhone, 30 - Marcoule (France). Dept. d`Exploitation du Retraitement et de Demantelement; Carcreff, H.; Marchand, L.; Thellier, G. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Reacteurs Experimentaux

    1994-12-31

    Mapping the gamma activity of irradiating zones is often an important prerequisite in dismantling nuclear facilities. The operation is necessary to define a suitable decommissioning strategy before any work begins; it is also required during the procedure to measure the residual activity wherever dose rates are too high to allow human intervention. This report summarizes the work carried out under CEC contract FIED-0055, covering a prototype imaging system designed to display radioactive sources superimposed in real time over a visible light image on a video monitor. This project was developed from an earlier off-line system. The gamma photons are collimated by a double cone system. The imaging system comprises a transparent scintillator bonded to the fiber-optic window of an ultrasensitive camera. The camera was miniaturized to meet specification requirements: with its radiological shielding, the gamma camera weighs 40 kg and is 120 mm in diameter. The processing system is compatible with a realtime camera, and small enough for use at any nuclear. The point-source angular resolution is 1.4 deg. for {sup 60} Co and 0.8 deg. for {sup 137} Cs. The dose rate sensitivity limit is approximately 0.01 mGy.h{sup -1}. Process reliability was confirmed by tests in a high-level radio-metallurgy cell at actual decommissioning site. (authors). 7 figs.

  9. Experimental results of superimposing 9.9 GHz extraordinary mode microwaves on 2.45 GHz ECRIS plasma

    Energy Technology Data Exchange (ETDEWEB)

    Nishiokada, Takuya, E-mail: nishiokada@nf.eie.eng.osaka-u.ac.jp; Nagaya, Tomoki; Hagino, Shogo; Otsuka, Takuro; Sato, Fuminobu; Kato, Yushi [Division of Electrical, Electronic, and Information Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871 (Japan); Muramatsu, Masayuki; Kitagawa, Atsushi [National Institute of Radiological Sciences (NIRS), 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-855 (Japan)

    2016-02-15

    Efficient production of multicharged ions has been investigated on the tandem-type ECRIS in Osaka University. According to the consideration of the accessibility conditions of microwaves to resonance and cutoff regions, it was suggested that the upper hybrid resonance (UHR) heating contributed to enhancement of ion beam intensity. In order to enhance multicharged ion beams efficiently, injecting higher frequency microwave with extraordinary (X-mode) toward UHR region has been tried. In this study, 2.45 GHz frequency microwaves are used for conventional ECR discharge, and 9.9 GHz frequency microwaves with X-mode are superimposed for UHR heating. The effects of additive microwave injection are investigated experimentally in terms of plasma parameters and electron energy distribution function (EEDF) measured by Langmuir probe and ion beam current. As the results show, it is confirmed that the electrons in the high energy region are affected by 9.9 GHz X-mode microwave injection from the detailed analysis of EEDF.

  10. Delirium superimposed on dementia: a survey of delirium specialists shows a lack of consensus in clinical practice and research studies.

    Science.gov (United States)

    Richardson, Sarah; Teodorczuk, Andrew; Bellelli, Giuseppe; Davis, Daniel H J; Neufeld, Karin J; Kamholz, Barbara A; Trabucchi, Marco; MacLullich, Alasdair M J; Morandi, Alessandro

    2016-05-01

    Despite advances in delirium knowledge and the publication of best practice guidelines, uncertainties exist regarding assessment of Delirium Superimposed on Dementia (DSD). An international survey of delirium specialists was undertaken to evaluate current practice. Invitations to participate in an online survey were distributed by email among members of four international delirium associations with additional publication on their websites. The survey covered the assessment and diagnosis of DSD in clinical practice and research studies. Questions were structured around current practice and attitudes. The 205 responders were mostly confident that they could detect DSD with 60% rating their confidence at 7 or above on a likert scale of 0 (none) to 10 (excellent). Seventy-six percent felt that Dementia with Lewy Bodies (DLB) was the most challenging dementia subtype in which to diagnose DSD. Several scales were used to assess for the presence of DSD including the Confusion Assessment Method (CAM) (54%), DSM-5 criteria (25%) and CAM-ICU (15%). Responders stated that attention (71%), fluctuation in cognitive status (65%), and arousability (41%) were the most clinically useful features to assess when diagnosing DSD. Motor fluctuations were also deemed important but 61% had no specific test to monitor these. The largest survey of DSD practice to date demonstrates that despite good levels of confidence in recognizing DSD, there exists a lack of consensus concerning assessment and diagnosis globally. These findings suggest the need for the development of more research leading to precise diagnostic criteria and comprehensive guidelines regarding the assessment and diagnosis of DSD.

  11. Novel Au/La-SrTiO3 microspheres: superimposed effect of gold nanoparticles and lanthanum doping in photocatalysis.

    Science.gov (United States)

    Wang, Guannan; Wang, Pei; Luo, He-Kuan; Hor, T S Andy

    2014-07-01

    Novel multielement Au/La-SrTiO(3) microspheres were synthesized by a solvothermal method using monodisperse gold and La-SrTiO(3) nanocrystals as building blocks. The porous Au/La-SrTiO(3) microspheres had a large surface area of 94.6 m(2)  g(-1). The stable confined Au nanoparticles demonstrated strong surface plasmon resonance effect, leading to enhanced absorption in a broad UV/Vis/NIR range. Doping of rare-earth metal La also broadened the absorption band to the visible region. Both the conduction and valence bands of Au/La-SrTiO(3) microspheres thus show favorable potential for proton reduction under visible light. The superimposed effect of Au nanoparticles and La doping in Au/La-SrTiO(3) microspheres led to high photocurrent density in photoelectrochemical water splitting and good photocatalytic activity in photodegradation of rhodamine B. The photocatalytic activities are in the order of the following: Au/La-SrTiO(3) microspheres>Au/SrTiO(3) microspheres>La-SrTiO(3) microspheres>SrTiO(3) microspheres.

  12. High-speed observation of bubble cloud generation near a rigid wall by second-harmonic superimposed ultrasound.

    Science.gov (United States)

    Yoshizawa, Shin; Yasuda, Jun; Umemura, Shin-ichiro

    2013-08-01

    Cavitation bubbles are known to accelerate therapeutic effects of ultrasound. Although negative acoustic pressure is the principle factor of cavitation, positive acoustic pressure has a role for bubble cloud formation at a high intensity of focused ultrasound when cavitation bubbles provide pressure release surfaces converting the pressure from highly positive to negative. In this study, the second-harmonic was superimposed onto the fundamental acoustic pressure to emphasize either peak positive or negative pressure. The peak negative and positive pressure emphasized waves were focused on a surface of an aluminum block. Cavitation bubbles induced near the block were observed with a high-speed camera by backlight and the size of the cavitation generation region was measured from the high-speed images. The negative pressure emphasized waves showed an advantage in cavitation inception over the positive pressure emphasized waves. In the sequence of the negative pressure emphasized waves immediately followed by the positive pressure emphasized waves, cavitation bubbles were generated on the block by the former waves and the cavitation region were expanded toward the transducer in the latter waves with high reproducibility. The sequence demonstrated its potential usefulness in enhancing the effects of therapeutic ultrasound at a high acoustic intensity.

  13. Normal Spectral Emissivity Measurement of Molten Cu-Co Alloy Using an Electromagnetic Levitator Superimposed with a Static Magnetic Field

    Science.gov (United States)

    Ueno, Shoya; Nakamura, Yuki; Sugioka, Ken-Ichi; Kubo, Masaki; Tsukada, Takao; Uchikoshi, Masahito; Fukuyama, Hiroyuki

    2017-02-01

    The normal spectral emissivity of molten Cu-Co alloy with different compositions was measured in the wavelength range of 780 nm to 920 nm and in the temperature range of 1430 K to 1770 K including the undercooled condition by an electromagnetic levitator superimposed with a static magnetic field. The emissivity was determined as the ratio of the radiance from a levitated molten Cu-Co droplet measured by a spectrometer to the radiance from a blackbody calculated by Planck's law at a given temperature, where a static magnetic field of 2.5 T to 4.5 T was applied to the levitated droplet to suppress the surface oscillation and translational motion of the sample. We found little temperature dependence of the normal spectral emissivity of molten Cu-Co alloy. Concerning the composition dependence, the emissivity decreased markedly above 80 at%Cu and reached that of pure Cu, although its dependence was low between 20 at%Cu and 80 at%Cu. In addition, this composition dependence of the emissivity of molten Cu-Co alloy can be explained well by the Drude free-electron model.

  14. On exponential stability for systems with state delays

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper considers the issue of delay-dependent exponential stability for time-delay systems. Both nominal and uncertain systems are investigated. New sufficient conditions in terms of linear matrix inequalities (LMIs) are obtained. These criteria are simple owing to the use of an integral inequality. The model transformation approaches, bounding techniques for cross terms and slack matrices are all avoided in the derivation. Rigorous proof and numerical examples showed that the proposed criteria and those based on introducing slack matrices are equivalent.

  15. Exponential integrators for the incompressible Navier-Stokes equations.

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Christopher K.

    2004-07-01

    We provide an algorithm and analysis of a high order projection scheme for time integration of the incompressible Navier-Stokes equations (NSE). The method is based on a projection onto the subspace of divergence-free (incompressible) functions interleaved with a Krylov-based exponential time integration (KBEI). These time integration methods provide a high order accurate, stable approach with many of the advantages of explicit methods, and can reduce the computational resources over conventional methods. The method is scalable in the sense that the computational costs grow linearly with problem size. Exponential integrators, used typically to solve systems of ODEs, utilize matrix vector products of the exponential of the Jacobian on a vector. For large systems, this product can be approximated efficiently by Krylov subspace methods. However, in contrast to explicit methods, KBEIs are not restricted by the time step. While implicit methods require a solution of a linear system with the Jacobian, KBEIs only require matrix vector products of the Jacobian. Furthermore, these methods are based on linearization, so there is no non-linear system solve at each time step. Differential-algebraic equations (DAEs) are ordinary differential equations (ODEs) subject to algebraic constraints. The discretized NSE constitute a system of DAEs, where the incompressibility condition is the algebraic constraint. Exponential integrators can be extended to DAEs with linear constraints imposed via a projection onto the constraint manifold. This results in a projected ODE that is integrated by a KBEI. In this approach, the Krylov subspace satisfies the constraint, hence the solution at the advanced time step automatically satisfies the constraint as well. For the NSE, the projection onto the constraint is typically achieved by a projection induced by the L{sup 2} inner product. We examine this L{sup 2} projection and an H{sup 1} projection induced by the H{sup 1} semi-inner product. The H

  16. DISRUPTION MANAGEMENT FOR SUPPLY CHAIN COORDINATION WITH EXPONENTIAL DEMAND FUNCTION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The coordination problem of a supply chain comprising one supplier and one retailer under market demand disruption is studied in this article. A novel exponential demand function is adopted, and the penalty cost is introduced explicitly to capture the deviation production cost caused by the market demand disruption. The optimal strategies are obtained for different disruption scale under the centralized mode. For the decentralized mode, it is proved that the supply chain can be fully coordinated by adjusting the price discount policy appropriately when disruption occurs. Furthermore, the authors point out that similar results can be established for more general demand functions that represent different market circumstances if certain assumptions are satisfied.

  17. New robust chaotic system with exponential quadratic term

    Institute of Scientific and Technical Information of China (English)

    Bao Bo-Cheng; Li Chun-Biao; Xu Jian-Peing; Liu Zhong

    2008-01-01

    This paper proposes a new robust chaotic system of three-dimensional quadratic autonomous ordinary differential equations by introducing an exponential quadratic term.This system can display a double-scroll chaotic attractor with only two equilibria,and can be found to be robust chaotic in a very wide parameter domain with positive maximum Lyapunov exponent.Some basic dynamical properties and chaotic behaviour of novel attractor are studied.By numerical simulation,this paper verifies that the three-dimensional system can also evolve into periodic and chaotic behaviottrs by a constant controller.

  18. Problems on Finite Automata and the Exponential Time Hypothesis

    Directory of Open Access Journals (Sweden)

    Henning Fernau

    2017-02-01

    Full Text Available We study several classical decision problems on finite automata under the (Strong Exponential Time Hypothesis. We focus on three types of problems: universality, equivalence, and emptiness of intersection. All these problems are known to be CoNP-hard for nondeterministic finite automata, even when restricted to unary input alphabets. A different type of problems on finite automata relates to aperiodicity and to synchronizing words. We also consider finite automata that work on commutative alphabets and those working on two-dimensional words.

  19. Power exponential velocity distributions in disordered porous media

    CERN Document Server

    Matyka, Maciej; Koza, Zbigniew

    2016-01-01

    Velocity distribution functions link the micro- and macro-level theories of fluid flow through porous media. Here we study them for the fluid absolute velocity and its longitudinal and lateral components relative to the macroscopic flow direction in a model of a random porous medium. We claim that all distributions follow the power exponential law controlled by an exponent $\\gamma$ and a shift parameter $u_0$ and examine how these parameters depend on the porosity. We find that $\\gamma$ has a universal value $1/2$ at the percolation threshold and grows with the porosity, but never exceeds 2.

  20. Exponential speed of mixing for skew-products with singularities

    CERN Document Server

    Markarian, R; Vieitez, J

    2012-01-01

    Let $f: [0,1]\\times [0,1] \\setminus {1/2} \\to [0,1]\\times [0,1]$ be the $C^\\infty$ endomorphism given by $$f(x,y)=(2x- [2x], y+ c/|x-1/2|- [y+ c/|x-1/2|]),$$ where $c$ is a positive real number. We prove that $f$ is topologically mixing and if $c>1/4$ then $f$ is mixing with respect to Lebesgue measure. Furthermore we prove that the speed of mixing is exponential.

  1. Exponential Family Techniques for the Lognormal Left Tail

    DEFF Research Database (Denmark)

    Asmussen, Søren; Jensen, Jens Ledet; Rojas-Nandayapa, Leonardo

    [Xe−θX]/L(θ)=x. The asymptotic formulas involve the Lambert W function. The established relations are used to provide two different numerical methods for evaluating the left tail probability of lognormal sum Sn=X1+⋯+Xn: a saddlepoint approximation and an exponential twisting importance sampling estimator. For the latter we...... demonstrate logarithmic efficiency. Numerical examples for the cdf Fn(x) and the pdf fn(x) of Sn are given in a range of values of σ2,n,x motivated from portfolio Value-at-Risk calculations....

  2. Exponential reduction of finite volume effects with twisted boundary conditions

    CERN Document Server

    Cherman, Aleksey; Wagman, Michael L; Yaffe, Laurence G

    2016-01-01

    Flavor-twisted boundary conditions can be used for exponential reduction of finite volume artifacts in flavor-averaged observables in lattice QCD calculations with $SU(N_f)$ light quark flavor symmetry. Finite volume artifact reduction arises from destructive interference effects in a manner closely related to the phase averaging which leads to large $N_c$ volume independence. With a particular choice of flavor-twisted boundary conditions, finite volume artifacts for flavor-singlet observables in a hypercubic spacetime volume are reduced to the size of finite volume artifacts in a spacetime volume with periodic boundary conditions that is four times larger.

  3. Exponential Martingales and Changes of Measure for Counting Processes

    DEFF Research Database (Denmark)

    Sokol, Alexander; Hansen, Niels Richard

    2015-01-01

    We give sufficient criteria for the Doléans-Dade exponential of a stochastic integral with respect to a counting process local martingale to be a true martingale. The criteria are adapted particularly to the case of counting processes and are sufficiently weak to be useful and verifiable, as we i...... illustrate by several examples. In particular, the criteria allow for the construction of for example nonexplosive Hawkes processes, counting processes with stochastic intensities depending on diffusion processes as well as inhomogeneous finite-state Markov processes....

  4. Evolution of Weighted Networks with Exponential Aging of Sites

    Institute of Scientific and Technical Information of China (English)

    XU Xin-Jian; WU Zhi-Xi; WANG Ying-Hai

    2005-01-01

    @@ We study the growth of weighted networks with exponential aging of sites. Each new vertex of the network is connected to some old vertices with proportional (i) to the strength of the old vertex and (ii) to e-ατ, where τ is the age of the old vertex and α is a positive constant. As soon as the preferential attachment is moditied by such factors, the interesting quantities of the produced network (the vertex degree, vertex strength, clustering coefficient and average path length) will be significantly transformed.

  5. On the Linear Combination of Exponential and Gamma Random Variables

    Directory of Open Access Journals (Sweden)

    Samuel Kotz

    2005-06-01

    Full Text Available Abstract: The exact distribution of the linear combination α X + β Y is derived when X and Y are exponential and gamma random variables distributed independently of each other. A measure of entropy of the linear combination is investigated. We also provide computer programs for generating tabulations of the percentage points associated with the linear combination. The work is motivated by examples in automation, control, fuzzy sets, neurocomputing and other areas of computer science.

  6. The decision-making properties of discrete multiple exponential bidirectional associative memories.

    Science.gov (United States)

    Wang, C C; Lee, J P

    1995-01-01

    A method for modeling the learning of belief combination in evidential reasoning using a neural network is presented. A centralized network composed of multiple exponential bidirectional associative memories (eBAM's) sharing a single output array of neurons is proposed to process the uncertainty management of many pieces of evidence simultaneously. The stability of the proposed multiple eBAM network is proved. The sufficient condition to recall a stored pattern pair is discussed. Most important of all, a majority rule of decision making in presentation of multiple evidence is also found by the study of signal-noise-ratio of multiple eBAM network. A guaranteed stable state condition, i.e., the condition for the fastest recall of a pattern pair, is also studied. The result is coherent with the intuition of reasoning.

  7. On the effects of nonlinearities in room impulse response measurements with exponential sweeps

    DEFF Research Database (Denmark)

    Ciric, Dejan; Markovic, Milos; Mijic, Miomir

    2013-01-01

    In room impulse response measurements, there are some common disturbances that affect the measured results. These disturbances include nonlinearity, noise and time variance. In this paper, the effects of nonlinearities in the measurements with exponential sweep-sine signals are analyzed from...... different perspectives. The analysis combines theoretical approach, simulations and measurements. The focus is on distortion artifacts in the causal part of the impulse response and their effects on room acoustical parameters. The results show that the sweep-sine method is vulnerable to a certain extent...... to nonlinearities from a theoretical standpoint, but the consequences of this vulnerability are reduced in the responses measured in practice. However, due to irretrievable contamination of the impulse responses, the nonlinearities (especially strong ones) should be avoided....

  8. A dynamic CMOS multiplier for analog VLSI based on exponential pulse-decay modulation

    Science.gov (United States)

    Massengill, Lloyd W.

    1991-03-01

    A clocked, charge-based, CMOS modulator circuit is presented. The circuit, which performs a semilinear multiplication function, has applications in arrayed analog VLSI architectures such as parallel filters and neural network systems. The design presented is simple in structure, uses no operational amplifiers for the actual multiplication function, and uses no power in the static mode. Two-quadrant weighting of an input signal is accomplished by control of the magnitude and decay time of an exponential current pulse, resulting in the delivery of charge packets to a shared capacitive summing bus. The cell is modular in structure and can be fabricated in a standard CMOS process. An analytical derivation of the operation of the circuit, SPICE simulations, and MOSIS fabrication results are presented. The simulation studies indicate that the circuit is inherently tolerant to temperature effects, absolute device sizing errors, and clock-feedthrough transients.

  9. Detecting the start of an influenza outbreak using exponentially weighted moving average charts

    Directory of Open Access Journals (Sweden)

    Coory Michael

    2010-06-01

    Full Text Available Abstract Background Influenza viruses cause seasonal outbreaks in temperate climates, usually during winter and early spring, and are endemic in tropical climates. The severity and length of influenza outbreaks vary from year to year. Quick and reliable detection of the start of an outbreak is needed to promote public health measures. Methods We propose the use of an exponentially weighted moving average (EWMA control chart of laboratory confirmed influenza counts to detect the start and end of influenza outbreaks. Results The chart is shown to provide timely signals in an example application with seven years of data from Victoria, Australia. Conclusions The EWMA control chart could be applied in other applications to quickly detect influenza outbreaks.

  10. A stochastic evolutionary model generating a mixture of exponential distributions

    Science.gov (United States)

    Fenner, Trevor; Levene, Mark; Loizou, George

    2016-02-01

    Recent interest in human dynamics has stimulated the investigation of the stochastic processes that explain human behaviour in various contexts, such as mobile phone networks and social media. In this paper, we extend the stochastic urn-based model proposed in [T. Fenner, M. Levene, G. Loizou, J. Stat. Mech. 2015, P08015 (2015)] so that it can generate mixture models, in particular, a mixture of exponential distributions. The model is designed to capture the dynamics of survival analysis, traditionally employed in clinical trials, reliability analysis in engineering, and more recently in the analysis of large data sets recording human dynamics. The mixture modelling approach, which is relatively simple and well understood, is very effective in capturing heterogeneity in data. We provide empirical evidence for the validity of the model, using a data set of popular search engine queries collected over a period of 114 months. We show that the survival function of these queries is closely matched by the exponential mixture solution for our model.

  11. Exponential Fuzzy C-Means for Collaborative Filtering

    Institute of Scientific and Technical Information of China (English)

    Kiatichai Treerattanapitak; Chuleerat Jaruskulchai

    2012-01-01

    Collaborative filtering (CF) is one of the most popular techniques behind the success of recommendation system. It predicts the interest of users by collecting information from past users who have the same opinions. The most popular approaches used in CF research area are Matrix factorization methods such as SVD.However,many wellknown recommendation systems do not use this method but still stick with Neighborhood models because of simplicity and explainability.There are some concerns that limit neighborhood models to achieve higher prediction accuracy.To address these concerns,we propose a new exponential fuzzy clustering (XFCM) algorithm by reformulating the clustering's objective function with an exponential equation in order to improve the method for membership assignment.The proposed method assigns data to the clusters by aggressively excluding irrelevant data,which is better than other fuzzy C-means (FCM) variants.The experiments show that XFCM-based CF improved 6.9% over item-based method and 3.0% over SVD in terms of mean absolute error for 100 K and 1 M MovieLens dataset.

  12. Online System Identification Method Using Modified Regularized Exponential Forgetting

    Directory of Open Access Journals (Sweden)

    Ján VACHÁLEK

    2013-12-01

    Full Text Available The paper deals with the use of regularized exponential forgetting (REF in the process of online system identification. The deployment of this type of forgetting strategy is advantageous for very long runs with small changes in the identified input parameters (in the range of 100 000 steps. In these cases, the classical methods of forgetting, such as an exponential (EF or directional forgetting (DF lack the required quality and reach the limit of numerical stability of the calculations of system parameters, which may lead to the early termination of system identification procedure. To avoid this undesirable effect and maintain sufficient primary information about the identified system, a modified REF method is used that employs alternative covariance matrix (ACM formulation to store the primary information of the identified system (REFACM and prevents the numerical destabilization of the identification process. The quality of the modified REFACM forgetting method —along with its validation and comparison with REZ to verify its properties—is performed using standard tests.

  13. Stretched exponential relaxation and ac universality in disordered dielectrics

    DEFF Research Database (Denmark)

    Milovanov, Alexander V.; Rypdal, Kristoffer; Juul Rasmussen, Jens

    2007-01-01

    This paper is concerned with the connection between the properties of dielectric relaxation and alternating-current (ac) conduction in disordered dielectrics. The discussion is divided between the classical linear-response theory and a self-consistent dynamical modeling. The key issues are stretc......This paper is concerned with the connection between the properties of dielectric relaxation and alternating-current (ac) conduction in disordered dielectrics. The discussion is divided between the classical linear-response theory and a self-consistent dynamical modeling. The key issues...... are stretched exponential character of dielectric relaxation, power-law power spectral density, and anomalous dependence of ac conduction coefficient on frequency. We propose a self-consistent model of dielectric relaxation in which the relaxations are described by a stretched exponential decay function....... Mathematically, our study refers to the expanding area of fractional calculus and we propose a systematic derivation of the fractional relaxation and fractional diffusion equations from the property of ac universality....

  14. The Non-Abelian Exponentiation theorem for multiple Wilson lines

    CERN Document Server

    Gardi, Einan; White, Chris D

    2013-01-01

    We study the structure of soft gluon corrections to multi-leg scattering amplitudes in a non-Abelian gauge theory by analysing the corresponding product of semi-infinite Wilson lines. We prove that diagrams exponentiate such that the colour factors in the exponent are fully connected. This completes the generalisation of the non-Abelian exponentiation theorem, previously proven in the case of a Wilson loop, to the case of multiple Wilson lines in arbitrary representations of the colour group. Our proof is based on the replica trick in conjunction with a new formalism where multiple emissions from a Wilson line are described by effective vertices, each having a connected colour factor. The exponent consists of connected graphs made out of these vertices. We show that this readily provides a general colour basis for webs. We further discuss the kinematic combinations that accompany each connected colour factor, and explicitly catalogue all three-loop examples, as necessary for a direct computation of the soft a...

  15. The non-Abelian exponentiation theorem for multiple Wilson lines

    Science.gov (United States)

    Gardi, Einan; Smillie, Jennifer M.; White, Chris D.

    2013-06-01

    We study the structure of soft gluon corrections to multi-leg scattering amplitudes in a non-Abelian gauge theory by analysing the corresponding product of semi-infinite Wilson lines. We prove that diagrams exponentiate such that the colour factors in the exponent are fully connected. This completes the generalisation of the non-Abelian exponentiation theorem, previously proven in the case of a Wilson loop, to the case of multiple Wilson lines in arbitrary representations of the colour group. Our proof is based on the replica trick in conjunction with a new formalism where multiple emissions from a Wilson line are described by effective vertices, each having a connected colour factor. The exponent consists of connected graphs made out of these vertices. We show that this readily provides a general colour basis for webs. We further discuss the kinematic combinations that accompany each connected colour factor, and explicitly catalogue all three-loop examples, as necessary for a direct computation of the soft anomalous dimension at this order.

  16. Bayesian inference and life testing plans for generalized exponential distribution

    Institute of Scientific and Technical Information of China (English)

    KUNDU; Debasis; PRADHAN; Biswabrata

    2009-01-01

    Recently generalized exponential distribution has received considerable attentions.In this paper,we deal with the Bayesian inference of the unknown parameters of the progressively censored generalized exponential distribution.It is assumed that the scale and the shape parameters have independent gamma priors.The Bayes estimates of the unknown parameters cannot be obtained in the closed form.Lindley’s approximation and importance sampling technique have been suggested to compute the approximate Bayes estimates.Markov Chain Monte Carlo method has been used to compute the approximate Bayes estimates and also to construct the highest posterior density credible intervals.We also provide different criteria to compare two different sampling schemes and hence to ?nd the optimal sampling schemes.It is observed that ?nding the optimum censoring procedure is a computationally expensive process.And we have recommended to use the sub-optimal censoring procedure,which can be obtained very easily.Monte Carlo simulations are performed to compare the performances of the different methods and one data analysis has been performed for illustrative purposes.

  17. Hyperbolic neighborhoods as organizers of finite-time exponential stretching

    Science.gov (United States)

    Balasuriya, Sanjeeva; Ouellette, Nicholas

    2016-11-01

    Hyperbolic points and their unsteady generalization, hyperbolic trajectories, drive the exponential stretching that is the hallmark of nonlinear and chaotic flow. Typical experimental and observational velocity data is unsteady and available only over a finite time interval, and in such situations hyperbolic trajectories will move around in the flow, and may lose their hyperbolicity at times. Here we introduce a way to determine their region of influence, which we term a hyperbolic neighborhood, which marks fluid elements whose dynamics are instantaneously dominated by the hyperbolic trajectory. We establish, using both theoretical arguments and numerical verification from model and experimental data, that the hyperbolic neighborhoods profoundly impact Lagrangian stretching experienced by fluid elements. In particular, we show that fluid elements traversing a flow experience exponential boosts in stretching while within these time-varying regions, that greater residence time within hyperbolic neighborhoods is directly correlated to larger Finite-Time Lyapunov Exponent (FTLE) values, and that FTLE diagnostics are reliable only when the hyperbolic neighborhoods have a geometrical structure which is regular in a specific sense. Future Fellowship Grant FT130100484 from the Australian Research Council (SB), and a Terman Faculty Fellowship from Stanford University (NO).

  18. Arima model and exponential smoothing method: A comparison

    Science.gov (United States)

    Wan Ahmad, Wan Kamarul Ariffin; Ahmad, Sabri

    2013-04-01

    This study shows the comparison between Autoregressive Moving Average (ARIMA) model and Exponential Smoothing Method in making a prediction. The comparison is focused on the ability of both methods in making the forecasts with the different number of data sources and the different length of forecasting period. For this purpose, the data from The Price of Crude Palm Oil (RM/tonne), Exchange Rates of Ringgit Malaysia (RM) in comparison to Great Britain Pound (GBP) and also The Price of SMR 20 Rubber Type (cents/kg) with three different time series are used in the comparison process. Then, forecasting accuracy of each model is measured by examinethe prediction error that producedby using Mean Squared Error (MSE), Mean Absolute Percentage Error (MAPE), and Mean Absolute deviation (MAD). The study shows that the ARIMA model can produce a better prediction for the long-term forecasting with limited data sources, butcannot produce a better prediction for time series with a narrow range of one point to another as in the time series for Exchange Rates. On the contrary, Exponential Smoothing Method can produce a better forecasting for Exchange Rates that has a narrow range of one point to another for its time series, while itcannot produce a better prediction for a longer forecasting period.

  19. Exponential decay and scaling laws in noisy chaotic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Seoane, Jesus M. [Nonlinear Dynamics and Chaos Group, Departamento de Fisica, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain)], E-mail: jesus.seoane@urjc.es; Sanjuan, Miguel A.F. [Nonlinear Dynamics and Chaos Group, Departamento de Fisica, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain)], E-mail: miguel.sanjuan@urjc.es

    2008-01-07

    In this Letter we present a numerical study of the effect of noise on a chaotic scattering problem in open Hamiltonian systems. We use the second order Heun method for stochastic differential equations in order to integrate the equations of motion of a two-dimensional flow with additive white Gaussian noise. We use as a prototype model the paradigmatic Henon-Heiles Hamiltonian with weak dissipation which is a well-known example of a system with escapes. We study the behavior of the scattering particles in the scattering region, finding an abrupt change of the decay law from algebraic to exponential due to the effects of noise. Moreover, we find a linear scaling law between the coefficient of the exponential law and the intensity of noise. These results are of a general nature in the sense that the same behavior appears when we choose as a model a two-dimensional discrete map with uniform noise (bounded in a particular interval and zero otherwise), showing the validity of the algorithm used. We believe the results of this work be useful for a better understanding of chaotic scattering in more realistic situations, where noise is presented.

  20. Data assimilation on the exponentially accurate slow manifold.

    Science.gov (United States)

    Cotter, Colin

    2013-05-28

    I describe an approach to data assimilation making use of an explicit map that defines a coordinate system on the slow manifold in the semi-geostrophic scaling in Lagrangian coordinates, and apply the approach to a simple toy system that has previously been proposed as a low-dimensional model for the semi-geostrophic scaling. The method can be extended to Lagrangian particle methods such as Hamiltonian particle-mesh and smooth-particle hydrodynamics applied to the rotating shallow-water equations, and many of the properties will remain for more general Eulerian methods. Making use of Hamiltonian normal-form theory, it has previously been shown that, if initial conditions for the system are chosen as image points of the map, then the fast components of the system have exponentially small magnitude for exponentially long times as ε→0, and this property is preserved if one uses a symplectic integrator for the numerical time stepping. The map may then be used to parametrize initial conditions near the slow manifold, allowing data assimilation to be performed without introducing any fast degrees of motion (more generally, the precise amount of fast motion can be selected).

  1. Five Exponential Diophantine Equations and Mayhem Problem M429

    CERN Document Server

    Zelator, Konstantine

    2011-01-01

    Crux Mathematicorum with Mathematical Mayhem, is a problem solving journal published by the Canadian Mathematical Society. In the March 2010 issue(see reference[1]) ,the following problem was proposed:Determine all positive integers a,b, and c such that a^(b^c)=(a^b)^c; or equivalently, a^(b^c)=a^(b^c). A solution by this author was published in the December2010 issue of Crux(see reference[2]). Accordingly, all such positive integer triples are the following:The triples of the form (1,b,c); with b, c any positive integers; the triples (a,b,1); a, b positive integers, with a being at least 2; and the triples of the form (a,2,2); a being a positive integer not equal to 1.These are then the positive integer solutions to the 3-variable exponential diophantine equation, x^(y^z)=x^(yz) (1) Motivated by mayhem problem M429, in this work we investigate for more 3-variable exponential diophantine equations: x^(y^z)=x^(z^y) (2), x^(y^z)=y^(xz) (3) x^(yz)=y^(xz) (4), x^(y^z)=z^(xy) (5) We completely determine the positi...

  2. On the construction of bivariate exponential distributions with an arbitrary correlation coefficient

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    In this paper we use a concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... the exponential random vectors....

  3. On the Construction of Bivariate Exponential Distributions with an Arbitrary Correlation Coefficient

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    2010-01-01

    In this article we use the concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... the exponential random vectors....

  4. Global Exponential Stability Analysis of a Class of Dynamical Neural Networks

    Institute of Scientific and Technical Information of China (English)

    Jin-Liang Shao; Ting-Zhu Huang

    2009-01-01

    The problem of the global exponential stability of a class of Hopfield neural networks is considered. Based on nonnegative matrix theory, a sufficient condition for the existence, uniqueness and global exponential stability of the equilibrium point is presented. And the upper bound for the degree of exponential stability is given. Moreover, a simulation is given to show the effectiveness of the result.

  5. Exponential Decay of Reconstruction Error from Binary Measurements of Sparse Signals

    Science.gov (United States)

    2014-08-01

    Mary Woottersm∗† rDepartment of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005 USA. Email: richb@rice.edu...Church Street, Ann Arbor, MI 48109, USA. Email: wootters@umich.edu August 1, 2014 Abstract Binary measurements arise naturally in a variety of

  6. Protective and super-imposing effects of Estradiol , Breviscapini, Lumbrokinase In focal cerebral ischemic-reperfusion injury on rats

    Institute of Scientific and Technical Information of China (English)

    Shang huiFang; Luo ZuMing

    2000-01-01

    Baekgrouad: Postmenopausal estrogen replacement therapy is always associated with a decrease in risk of stroke incidence and mortality. The breviscapini and lumbrokinase can protect brain from ischemic injury..Experiments in animal models suggest estradiol can protect brain from ischemic injury. But we know little about the mechanism of brain protection role of estradiol. Espectically we don't know if estrodiol plus other brain protective drugs such as breviscapini and lumbrokinase have superimposing protection. Objective: To study protective function and its mechanism of estradio breviscapini and lumbrokinase after cerebral ischemic reperfusion tn overiectimiaed rat. Methods: We made the local ischemic repenfusion model with thread emgolism of right middle cerebral artery (MCA) of young female SD rars which werc bilaterally ovariectomized two weeks ago were used. These rats were randomized into sham-operated group, control group, estrodiol group, brevisacapini group, 10 SD rats each group. We admistrated each group with reseponsed treatment when rats were subjected to half an hour of MCAO. MCA were oecluded 2 hours and followed by 70 hours of reperfusion. Sham-poerated group were exposed cervical common artery and weren't occluded MCA. The rats were killed at 72 hours. The observed patameters each group listed: 1) The neurological deficit scores were made after MCAO 2 hours and bcforc killed. 2) Each group excluded sham operaated group were caculaled cerebral infarct volume ratio and edema volume with stereological microscoppe. 3) The level of Nitrc oxide (NO) in serum were determined with nitrate redutase method. 4) The level of Interlukin-I (IL-1) and tumor necrosis factot (TNF) were determined by biological activity method. 5) Ultrastructure of neuron were observed with electron microscope. All the rcsults from different groups were compared with each other. The drugs identified effictive in formcr study plus estradiot wcre admistratcd to rats to obscrvcd

  7. Protective and super-imposing effects of Estradiol , Breviscapini, Lumbrokinase In focal cerebral ischemic-reperfusion injury on rats

    Institute of Scientific and Technical Information of China (English)

    Shang huiFang; Luo ZuMing

    2000-01-01

    Baekgrouad: Postmenopausal estrogen replacement therapy is always associated with a decrease in risk of stroke incidence and mortality. The breviscapini and lumbrokinase can protect brain from ischemic injury..Experiments in animal models suggest estradiol can protect brain from ischemic injury. But we know little about the mechanism of brain protection role of estradiol. Espectically we don't know if estrodiol plus other brain protective drugs such as breviscapini and lumbrokinase have superimposing protection. Objective: To study protective function and its mechanism of estradio breviscapini and lumbrokinase after cerebral ischemic reperfusion tn overiectimiaed rat. Methods: We made the local ischemic repenfusion model with thread emgolism of right middle cerebral artery (MCA) of young female SD rars which werc bilaterally ovariectomized two weeks ago were used. These rats were randomized into sham-operated group, control group, estrodiol group, brevisacapini group, 10 SD rats each group. We admistrated each group with reseponsed treatment when rats were subjected to half an hour of MCAO. MCA were oecluded 2 hours and followed by 70 hours of reperfusion. Sham-poerated group were exposed cervical common artery and weren't occluded MCA. The rats were killed at 72 hours. The observed patameters each group listed: 1) The neurological deficit scores were made after MCAO 2 hours and bcforc killed. 2) Each group excluded sham operaated group were caculaled cerebral infarct volume ratio and edema volume with stereological microscoppe. 3) The level of Nitrc oxide (NO) in serum were determined with nitrate redutase method. 4) The level of Interlukin-I (IL-1) and tumor necrosis factot (TNF) were determined by biological activity method. 5) Ultrastructure of neuron were observed with electron microscope. All the rcsults from different groups were compared with each other. The drugs identified effictive in formcr study plus estradiot wcre admistratcd to rats to obscrvcd

  8. Frequency dependence of lung volume changes during superimposed high-frequency jet ventilation and high-frequency jet ventilation.

    Science.gov (United States)

    Sütterlin, R; Priori, R; Larsson, A; LoMauro, A; Frykholm, P; Aliverti, A

    2014-01-01

    Superimposed high-frequency jet ventilation (SHFJV) has proved to be safe and effective in clinical practice. However, it is unclear which frequency range optimizes ventilation and gas exchange. The aim of this study was to systematically compare high-frequency jet ventilation (HFJV) with HFJV by assessing chest wall volume variations (ΔEEV(CW)) and gas exchange in relation to variable high frequency. SHFJV or HFJV were used alternatively to ventilate the lungs of 10 anaesthetized pigs (21-25 kg). The low-frequency component was kept at 16 min(-1) in SHFJV. In both modes, high frequencies ranging from 100 to 1000 min(-1) were applied in random order and ventilation was maintained for 5 min in all modalities. Chest wall volume variations were obtained using opto-electronic plethysmography. Airway pressures and arterial blood gases were measured repeatedly. SHFJV increased ΔEEV(CW) compared with HFJV; the difference ranged from 43 to 68 ml. Tidal volume (V(T)) was always >240 ml during SHFJV whereas during HFJV ranged from 92 ml at the ventilation frequency of 100 min(-1) to negligible values at frequencies >300 min(-1). We observed similar patterns for Pa(O₂) and Pa(CO₂). SHFJV provided generally higher, frequency-independent oxygenation (Pa(O₂) at least 32.0 kPa) and CO₂ removal (Pa(CO₂) ∼5.5 kPa), whereas HFJV led to hypoxia and hypercarbia at higher rates (Pa(O₂) 10 kPa at f(HF)>300 min(-1)). In a porcine model, SHFJV was more effective in increasing end-expiratory volume than single-frequency HFJV, but both modes may provide adequate ventilation in the absence of airway obstruction and respiratory disease, except for HFJV at frequencies ≥300 min(-1).

  9. Hybrid Adaptive Filter development for the minimisation of transient fluctuations superimposed on electrotelluric field recordings mainly by magnetic storms

    Directory of Open Access Journals (Sweden)

    A. Konstantaras

    2006-01-01

    Full Text Available The method of Hybrid Adaptive Filtering (HAF aims to recover the recorded electric field signals from anomalies of magnetotelluric origin induced mainly by magnetic storms. An adaptive filter incorporating neuro-fuzzy technology has been developed to remove any significant distortions from the equivalent magnetic field signal, as retrieved from the original electric field signal by reversing the magnetotelluric method. Testing with further unseen data verifies the reliability of the model and demonstrates the effectiveness of the HAF method.

  10. Thermal dynamics on the lattice with exponentially improved accuracy

    CERN Document Server

    Pawlowski, Jan

    2016-01-01

    We present a novel simulation prescription for thermal quantum fields on a lattice that operates directly in imaginary frequency space. By distinguishing initial conditions from quantum dynamics it provides access to correlation functions also outside of the conventional Matsubara frequencies $\\omega_n=2\\pi n T$. In particular it resolves their frequency dependence between $\\omega=0$ and $\\omega_1=2\\pi T$, where the thermal physics $\\omega\\sim T$ of e.g.~transport phenomena is dominantly encoded. Real-time spectral functions are related to these correlators via an integral transform with rational kernel, so their unfolding is exponentially improved compared to Euclidean simulations. We demonstrate this improvement within a $0+1$-dimensional scalar field theory and show that spectral features inaccessible in standard Euclidean simulations are quantitatively captured.

  11. Noise facilitation in associative memories of exponential capacity.

    Science.gov (United States)

    Karbasi, Amin; Salavati, Amir Hesam; Shokrollahi, Amin; Varshney, Lav R

    2014-11-01

    Recent advances in associative memory design through structured pattern sets and graph-based inference algorithms have allowed reliable learning and recall of an exponential number of patterns that satisfy certain subspace constraints. Although these designs correct external errors in recall, they assume neurons that compute noiselessly, in contrast to the highly variable neurons in brain regions thought to operate associatively, such as hippocampus and olfactory cortex. Here we consider associative memories with boundedly noisy internal computations and analytically characterize performance. As long as the internal noise level is below a specified threshold, the error probability in the recall phase can be made exceedingly small. More surprising, we show that internal noise improves the performance of the recall phase while the pattern retrieval capacity remains intact: the number of stored patterns does not reduce with noise (up to a threshold). Computational experiments lend additional support to our theoretical analysis. This work suggests a functional benefit to noisy neurons in biological neuronal networks.

  12. Static vortices in long Josephson junctions of exponentially varying width

    Science.gov (United States)

    Semerdjieva, E. G.; Boyadjiev, T. L.; Shukrinov, Yu. M.

    2004-06-01

    A numerical simulation is carried out for static vortices in a long Josephson junction with an exponentially varying width. At specified values of the parameters the corresponding boundary-value problem admits more than one solution. Each solution (distribution of the magnetic flux in the junction) is associated to a Sturm-Liouville problem, the smallest eigenvalue of which can be used, in a first approximation, to assess the stability of the vortex against relatively small spatiotemporal perturbations. The change in width of the junction leads to a renormalization of the magnetic flux in comparison with the case of a linear one-dimensional model. The influence of the model parameters on the stability of the states of the magnetic flux is investigated in detail, particularly that of the shape parameter. The critical curve of the junction is constructed from pieces of the critical curves for the different magnetic flux distributions having the highest critical currents for the given magnetic field.

  13. Income inequality in Romania: The exponential-Pareto distribution

    Science.gov (United States)

    Oancea, Bogdan; Andrei, Tudorel; Pirjol, Dan

    2017-03-01

    We present a study of the distribution of the gross personal income and income inequality in Romania, using individual tax income data, and both non-parametric and parametric methods. Comparing with official results based on household budget surveys (the Family Budgets Survey and the EU-SILC data), we find that the latter underestimate the income share of the high income region, and the overall income inequality. A parametric study shows that the income distribution is well described by an exponential distribution in the low and middle incomes region, and by a Pareto distribution in the high income region with Pareto coefficient α = 2.53. We note an anomaly in the distribution in the low incomes region (∼9,250 RON), and present a model which explains it in terms of partial income reporting.

  14. Auxiliary Parameter MCMC for Exponential Random Graph Models

    Science.gov (United States)

    Byshkin, Maksym; Stivala, Alex; Mira, Antonietta; Krause, Rolf; Robins, Garry; Lomi, Alessandro

    2016-11-01

    Exponential random graph models (ERGMs) are a well-established family of statistical models for analyzing social networks. Computational complexity has so far limited the appeal of ERGMs for the analysis of large social networks. Efficient computational methods are highly desirable in order to extend the empirical scope of ERGMs. In this paper we report results of a research project on the development of snowball sampling methods for ERGMs. We propose an auxiliary parameter Markov chain Monte Carlo (MCMC) algorithm for sampling from the relevant probability distributions. The method is designed to decrease the number of allowed network states without worsening the mixing of the Markov chains, and suggests a new approach for the developments of MCMC samplers for ERGMs. We demonstrate the method on both simulated and actual (empirical) network data and show that it reduces CPU time for parameter estimation by an order of magnitude compared to current MCMC methods.

  15. Fitting and Analyzing Randomly Censored Geometric Extreme Exponential Distribution

    Directory of Open Access Journals (Sweden)

    Muhammad Yameen Danish

    2016-06-01

    Full Text Available The paper presents the Bayesian analysis of two-parameter geometric extreme exponential distribution with randomly censored data. The continuous conjugate prior of the scale and shape parameters of the model does not exist while computing the Bayes estimates, it is assumed that the scale and shape parameters have independent gamma priors. It is seen that the closed-form expressions for the Bayes estimators are not possible; we suggest the Lindley’s approximation to obtain the Bayes estimates. However, the Bayesian credible intervals cannot be constructed while using this method, we propose Gibbs sampling to obtain the Bayes estimates and also to construct the Bayesian credible intervals. Monte Carlo simulation study is carried out to observe the behavior of the Bayes estimators and also to compare with the maximum likelihood estimators. One real data analysis is performed for illustration.

  16. Coexistence of exponentially many chaotic spin-glass attractors.

    Science.gov (United States)

    Peleg, Y; Zigzag, M; Kinzel, W; Kanter, I

    2011-12-01

    A chaotic network of size N with delayed interactions which resembles a pseudoinverse associative memory neural network is investigated. For a load α = P/N chaotic network functions as an associative memory of 2P attractors with macroscopic basin of attractions which decrease with α. At finite α, a chaotic spin-glass phase exists, where the number of distinct chaotic attractors scales exponentially with N. Each attractor is characterized by a coexistence of chaotic behavior and freezing of each one of the N chaotic units or freezing with respect to the P patterns. Results are supported by large scale simulations of networks composed of Bernoulli map units and Mackey-Glass time delay differential equations.

  17. A Generalization of Exponential Class and Its Applications

    Directory of Open Access Journals (Sweden)

    Hongya Gao

    2013-01-01

    Full Text Available A function space, Lθ,∞(Ω, 0≤θ<∞, is defined. It is proved that Lθ,∞(Ω is a Banach space which is a generalization of exponential class. An alternative definition of Lθ,∞(Ω space is given. As an application, we obtain weak monotonicity property for very weak solutions of -harmonic equation with variable coefficients under some suitable conditions related to Lθ,∞(Ω, which provides a generalization of a known result due to Moscariello. A weighted space Lwθ,∞(Ω is also defined, and the boundedness for the Hardy-Littlewood maximal operator Mw and a Calderón-Zygmund operator T with respect to Lwθ,∞(Ω is obtained.

  18. Predicting jet radius in electrospinning by superpositioning exponential functions

    Science.gov (United States)

    Widartiningsih, P. M.; Iskandar, F.; Munir, M. M.; Viridi, S.

    2016-08-01

    This paper presents an analytical study of the correlation between viscosity and fiber diameter in electrospinning. Control over fiber diameter in electrospinning process was important since it will determine the performance of resulting nanofiber. Theoretically, fiber diameter was determined by surface tension, solution concentration, flow rate, and electric current. But experimentally it had been proven that significantly viscosity had an influence to fiber diameter. Jet radius equation in electrospinning process was divided into three areas: near the nozzle, far from the nozzle, and at jet terminal. There was no correlation between these equations. Superposition of exponential series model provides the equations combined into one, thus the entire of working parameters on electrospinning take a contribution to fiber diameter. This method yields the value of solution viscosity has a linear relation to jet radius. However, this method works only for low viscosity.

  19. Increasing hazard rate of mixtures for natural exponential families

    CERN Document Server

    Bar-Lev, Shaul K

    2010-01-01

    Hazard rates play an important role in various areas, e.g., reliability theory, survival analysis, biostatistics, queueing theory and actuarial studies. Mixtures of distributions are also of a great preeminence in such areas as most populations of components are indeed heterogeneous. In this study we present a sufficient condition for mixtures of two elements\\ of the same natural exponential family (NEF) to have an increasing hazard rate. We then apply this condition to some classical NEF's having either quadratic, or cubic variance functions (VF) and others as well. A particular attention is devoted to the hyperbolic cosine NEF having a quadratic VF, the Ressel NEF having a cubic VF and to the Kummer distributions of type 2 NEF. The application of such a sufficient condition is quite intricate and cumbersome, in particular when applied to the latter three NEF's. Various lemmas and propositions are needed then to verify this condition for these NEF's.

  20. Exact inference for two exponential populations with competing risks data

    Institute of Scientific and Technical Information of China (English)

    Song Mao; Yimin Shi; Liang Wang

    2014-01-01

    In a reliability comparative test, the joint censoring model is usual y adopted to evaluate the performances of units with the same facility. However, most researchers ignore the pos-sibility that there is more than one factor for the failure when a test unit fails. To solve this problem, we consider a joint Type-II hybrid censoring model for the analysis of exponential competing failure data. Based on the maximum likelihood theory, we compute the maximum likelihood estimators (MLEs) of parameters and then obtain the condition ensuring MLEs existence for every unknown parameter. Then we derive the conditional exact distributions and corresponding moment properties for parameters by the moment generating function (MGF). A Monte-Carlo simulation is conducted to compare the performances of different ways. And final y, we conduct a numerical example to il ustrate the proposed method.

  1. Control of Spacecraft Formation with Disturbance Rejection and Exponential Gains

    Directory of Open Access Journals (Sweden)

    R. Schlanbusch

    2013-01-01

    Full Text Available We address the problem of state feedback translational motion control of a spacecraft formation through a modified sliding surface controller using variable gains and I^2 action for disturbance rejection. The exponential varying gains ensure faster convergence of the state trajectories during attitude maneuver while keeping the gains small (and the system less stiff for station keeping. Integral action is introduced for rejection of disturbances with a constant nonzero mean such as aerodynamic drag. A direct consequence is a drop in energy consumption when affected by sensor noise and a decrease in size of the error states residual when operating close to the equilibrium point. A large number of simulation results are presented to show the control performance.

  2. A generalized exponential time series regression model for electricity prices

    DEFF Research Database (Denmark)

    Haldrup, Niels; Knapik, Oskar; Proietti, Tomasso

    We consider the issue of modeling and forecasting daily electricity spot prices on the Nord Pool Elspot power market. We propose a method that can handle seasonal and non-seasonal persistence by modelling the price series as a generalized exponential process. As the presence of spikes can distort...... the estimation of the dynamic structure of the series we consider an iterative estimation strategy which, conditional on a set of parameter estimates, clears the spikes using a data cleaning algorithm, and reestimates the parameters using the cleaned data so as to robustify the estimates. Conditional...... on the estimated model, the best linear predictor is constructed. Our modeling approach provides good fit within sample and outperforms competing benchmark predictors in terms of forecasting accuracy. We also find that building separate models for each hour of the day and averaging the forecasts is a better...

  3. Collective Prediction of Individual Mobility Traces with Exponential Weights

    CERN Document Server

    Hawelka, Bartosz; Kazakopoulos, Pavlos; Beinat, Euro

    2015-01-01

    We present and test a sequential learning algorithm for the short-term prediction of human mobility. This novel approach pairs the Exponential Weights forecaster with a very large ensemble of experts. The experts are individual sequence prediction algorithms constructed from the mobility traces of 10 million roaming mobile phone users in a European country. Average prediction accuracy is significantly higher than that of individual sequence prediction algorithms, namely constant order Markov models derived from the user's own data, that have been shown to achieve high accuracy in previous studies of human mobility prediction. The algorithm uses only time stamped location data, and accuracy depends on the completeness of the expert ensemble, which should contain redundant records of typical mobility patterns. The proposed algorithm is applicable to the prediction of any sufficiently large dataset of sequences.

  4. Exponential fading to white of black holes in quantum gravity

    CERN Document Server

    Barceló, Carlos; Garay, Luis J

    2016-01-01

    Quantization of the gravitational field could allow the existence of a hypothetical decay channel of black holes into white holes with an explicit time-reversal symmetry. The definition of a meaningful decay probability for this channel is studied in spherically symmetric situations. As a first nontrivial calculation, we present the functional integration over a set of geometries using a single-variable function to interpolate between black-hole and white-hole geometries in a bounded region of spacetime. This computation gives a finite result which depends only on the Schwarzschild mass and a parameter measuring the width of the interpolating region. The associated probability distribution displays an exponential decay law on the latter parameter, with the Planck time as its mean lifetime (up to subdominant terms). In physical terms this would imply that matter collapsing to a black hole from a finite radius bounces back elastically and instantaneously, with negligible time delay as measured by external obser...

  5. Exponential Family Techniques for the Lognormal Left Tail

    DEFF Research Database (Denmark)

    Asmussen, Søren; Jensen, Jens Ledet; Rojas-Nandayapa, Leonardo

    Let X be lognormal(μ,σ2) with density f(x), let θ>0 and define L(θ)=Ee−θX. We study properties of the exponentially tilted density (Esscher transform) fθ(x)=e−θxf(x)/L(θ), in particular its moments, its asymptotic form as θ→∞ and asymptotics for the saddlepoint θ(x) determined by E[Xe−θX]/L(θ)=x....... demonstrate logarithmic efficiency. Numerical examples for the cdf Fn(x) and the pdf fn(x) of Sn are given in a range of values of σ2,n,x motivated from portfolio Value-at-Risk calculations....

  6. Iterative exponential growth of stereo- and sequence-controlled polymers.

    Science.gov (United States)

    Barnes, Jonathan C; Ehrlich, Deborah J C; Gao, Angela X; Leibfarth, Frank A; Jiang, Yivan; Zhou, Erica; Jamison, Timothy F; Johnson, Jeremiah A

    2015-10-01

    Chemists have long sought sequence-controlled synthetic polymers that mimic nature's biopolymers, but a practical synthetic route that enables absolute control over polymer sequence and structure remains a key challenge. Here, we report an iterative exponential growth plus side-chain functionalization (IEG+) strategy that begins with enantiopure epoxides and facilitates the efficient synthesis of a family of uniform >3 kDa macromolecules of varying sequence and stereoconfiguration that are coupled to produce unimolecular polymers (>6 kDa) with sequences and structures that cannot be obtained using traditional polymerization techniques. Selective side-chain deprotection of three hexadecamers is also demonstrated, which imbues each compound with the ability to dissolve in water. We anticipate that these new macromolecules and the general IEG+ strategy will find broad application as a versatile platform for the scalable synthesis of sequence-controlled polymers.

  7. Statistical modelling of agrometeorological time series by exponential smoothing

    Science.gov (United States)

    Murat, Małgorzata; Malinowska, Iwona; Hoffmann, Holger; Baranowski, Piotr

    2016-01-01

    Meteorological time series are used in modelling agrophysical processes of the soil-plant-atmosphere system which determine plant growth and yield. Additionally, long-term meteorological series are used in climate change scenarios. Such studies often require forecasting or projection of meteorological variables, eg the projection of occurrence of the extreme events. The aim of the article was to determine the most suitable exponential smoothing models to generate forecast using data on air temperature, wind speed, and precipitation time series in Jokioinen (Finland), Dikopshof (Germany), Lleida (Spain), and Lublin (Poland). These series exhibit regular additive seasonality or non-seasonality without any trend, which is confirmed by their autocorrelation functions and partial autocorrelation functions. The most suitable models were indicated by the smallest mean absolute error and the smallest root mean squared error.

  8. Iterative Exponential Growth Synthesis and Assembly of Uniform Diblock Copolymers.

    Science.gov (United States)

    Jiang, Yivan; Golder, Matthew R; Nguyen, Hung V-T; Wang, Yufeng; Zhong, Mingjiang; Barnes, Jonathan C; Ehrlich, Deborah J C; Johnson, Jeremiah A

    2016-08-03

    Studies on the phase segregation of unimolecular block copolymers (BCPs) are limited by a lack of reliable, versatile methods for the synthesis of such polymers on the preparative scale. Herein, we describe an advancement of Iterative Exponential Growth (IEG) wherein chiral allyl-based IEG oligomers are subjected to thiol-ene reactions and converted into unimolecular BCPs. With this strategy we have synthesized uniform BCPs with molar masses up to 12.1 kDa on ∼1 g scale. BCPs composed of decane-based side chains and either triethyleneglycol- or thioglycerol-based side chains phase-segregate into hexagonal cylinder morphologies. The assembly is not driven by side-chain crystallization, but is instead the result of amorphous BCP assembly.

  9. Academia-industry collaboration feeds exponential growth curve

    CERN Document Server

    Jones Bey Hassaun, A

    2004-01-01

    The use of silicon strip detectors in high-energy particle tracking is discussed. The functional strength of silicon for high-energy particle physics as well as astrophysics lies in the ability to detect passage of charged particles with micron-scale spatial resolution. In addition to vertex detection, silicon strip detectors also provide full tracking detection to include momentum determination of particles in the magnetic field. Even if silicon detectors for basic science applications do not continue to grow larger, exponential growth of the technology for terrestrial commercial applications is likely to follow a healthy growth curve, as researchers continue to adapt silicon detector technology for low- dose medical x-ray imaging. (Edited abstract)

  10. Holographic Lifshitz fermions and exponentially suppressed spectral weight

    CERN Document Server

    Kim, Youngshin

    2016-01-01

    One of the unusual features of Lifshitz holography is the presence of a tunneling barrier that arises from the bulk geometry for probes carrying large transverse momentum. This leads to a decoupling of the horizon from the boundary, and in particular gives rise to an exponential suppression of spectral weight in the large transverse momentum limit. We compute the spin-1/2 holographic Green's function and show that this suppression has the same origin as in the scalar case. We furthermore demonstrate that the suppression factor is universal in the $\\hat\\omega\\to0$ limit where $\\hat\\omega=\\omega/|\\vec k|^z$. In particular, it depends only on $\\hat\\omega$ and the critical exponent $z$, and is independent of scaling dimension and spin.

  11. Rotating Dilaton Black Strings Coupled to Exponential Nonlinear Electrodynamics

    Directory of Open Access Journals (Sweden)

    Ahmad Sheykhi

    2014-01-01

    Full Text Available We construct a new class of charged rotating black string solutions coupled to dilaton and exponential nonlinear electrodynamic fields with cylindrical or toroidal horizons in the presence of a Liouville-type potential for the dilaton field. Due to the presence of the dilaton field, the asymptotic behaviors of these solutions are neither flat nor (AdS. We analyze the physical properties of the solutions in detail. We compute the conserved and thermodynamic quantities of the solutions and verify the first law of thermodynamics on the black string horizon. When the nonlinear parameter β2 goes to infinity, our results reduce to those of black string solutions in Einstein-Maxwell-dilaton gravity.

  12. Control of a heterogeneous two-server exponential queueing system

    Science.gov (United States)

    Larsen, R. L.; Agrawala, A. K.

    1983-01-01

    A dynamic control policy known as 'threshold queueing' is defined for scheduling customers from a Poisson source on a set of two exponential servers with dissimilar service rates. The slower server is invoked in response to instantaneous system loading as measured by the length of the queue of waiting customers. In a threshold queueing policy, a specific queue length is identified as a 'threshold,' beyond which the slower server is invoked. The slower server remains busy until it completes service on a customer and the queue length is less than its invocation threshold. Markov chain analysis is employed to analyze the performance of the threshold queueing policy and to develop optimality criteria. It is shown that probabilistic control is suboptimal to minimize the mean number of customers in the system. An approximation to the optimum policy is analyzed which is computationally simple and suffices for most operational applications.

  13. Galilean invariance in the exponential model of atomic collisions

    Energy Technology Data Exchange (ETDEWEB)

    del Pozo, A.; Riera, A.; Yaez, M.

    1986-11-01

    Using the X/sup n//sup +/(1s/sup 2/)+He/sup 2+/ colliding systems as specific examples, we study the origin dependence of results in the application of the two-state exponential model, and we show the relevance of polarization effects in that study. Our analysis shows that polarization effects of the He/sup +/(1s) orbital due to interaction with X/sup (//sup n//sup +1)+/ ion in the exit channel yield a very small contribution to the energy difference and render the dynamical coupling so strongly origin dependent that it invalidates the basic premises of the model. Further study, incorporating translation factors in the formalism, is needed.

  14. The group exponential lasso for bi-level variable selection.

    Science.gov (United States)

    Breheny, Patrick

    2015-09-01

    In many applications, covariates possess a grouping structure that can be incorporated into the analysis to select important groups as well as important members of those groups. One important example arises in genetic association studies, where genes may have several variants capable of contributing to disease. An ideal penalized regression approach would select variables by balancing both the direct evidence of a feature's importance as well as the indirect evidence offered by the grouping structure. This work proposes a new approach we call the group exponential lasso (GEL) which features a decay parameter controlling the degree to which feature selection is coupled together within groups. We demonstrate that the GEL has a number of statistical and computational advantages over previously proposed group penalties such as the group lasso, group bridge, and composite MCP. Finally, we apply these methods to the problem of detecting rare variants in a genetic association study.

  15. On Quantified Propositional Logics and the Exponential Time Hierarchy

    Directory of Open Access Journals (Sweden)

    Miika Hannula

    2016-09-01

    Full Text Available We study quantified propositional logics from the complexity theoretic point of view. First we introduce alternating dependency quantified boolean formulae (ADQBF which generalize both quantified and dependency quantified boolean formulae. We show that the truth evaluation for ADQBF is AEXPTIME(poly-complete. We also identify fragments for which the problem is complete for the levels of the exponential hierarchy. Second we study propositional team-based logics. We show that DQBF formulae correspond naturally to quantified propositional dependence logic and present a general NEXPTIME upper bound for quantified propositional logic with a large class of generalized dependence atoms. Moreover we show AEXPTIME(poly-completeness for extensions of propositional team logic with generalized dependence atoms.

  16. Exponential protection of zero modes in Majorana islands.

    Science.gov (United States)

    Albrecht, S M; Higginbotham, A P; Madsen, M; Kuemmeth, F; Jespersen, T S; Nygård, J; Krogstrup, P; Marcus, C M

    2016-03-10

    Majorana zero modes are quasiparticle excitations in condensed matter systems that have been proposed as building blocks of fault-tolerant quantum computers. They are expected to exhibit non-Abelian particle statistics, in contrast to the usual statistics of fermions and bosons, enabling quantum operations to be performed by braiding isolated modes around one another. Quantum braiding operations are topologically protected insofar as these modes are pinned near zero energy, with the departure from zero expected to be exponentially small as the modes become spatially separated. Following theoretical proposals, several experiments have identified signatures of Majorana modes in nanowires with proximity-induced superconductivity and atomic chains, with small amounts of mode splitting potentially explained by hybridization of Majorana modes. Here, we use Coulomb-blockade spectroscopy in an InAs nanowire segment with epitaxial aluminium, which forms a proximity-induced superconducting Coulomb island (a 'Majorana island') that is isolated from normal-metal leads by tunnel barriers, to measure the splitting of near-zero-energy Majorana modes. We observe exponential suppression of energy splitting with increasing wire length. For short devices of a few hundred nanometres, sub-gap state energies oscillate as the magnetic field is varied, as is expected for hybridized Majorana modes. Splitting decreases by a factor of about ten for each half a micrometre of increased wire length. For devices longer than about one micrometre, transport in strong magnetic fields occurs through a zero-energy state that is energetically isolated from a continuum, yielding uniformly spaced Coulomb-blockade conductance peaks, consistent with teleportation via Majorana modes. Our results help to explain the trivial-to-topological transition in finite systems and to quantify the scaling of topological protection with end-mode separation.

  17. Exponentiation for products of Wilson lines within the generating function approach

    CERN Document Server

    Vladimirov, Alexey A

    2015-01-01

    We present the generating function approach to the perturbative exponentiation of correlators of a product of Wilson lines and loops. The exponentiated expression is presented in the closed form as an algebraic function of correlators of known operators, which can be seen as a generating function for web diagrams. The expression is naturally split onto two parts: the exponentiation kernel, which accumulates all non-trivial information about web diagrams, and the defect of exponentiation, which reconstructs the matrix exponent and is a function of the exponentiation kernel. The detailed comparison of the presented approach with existing approaches to exponentiation is presented as well. We also give examples of calculations within the generating function exponentiation, namely, we consider different configurations of light-like Wilson lines in the multi-gluon-exchange-webs (MGEW) approximation. Within this approximation the corresponding correlators can be calculated exactly at any order of perturbative expans...

  18. Intravoxel incoherent motion diffusion-weighted imaging in the liver: comparison of mono-, bi- and tri-exponential modelling at 3.0-T

    Energy Technology Data Exchange (ETDEWEB)

    Cercueil, Jean-Pierre [University of Burgundy, INSERM U866, BP 87900, Dijon (France); CHU (University Hospital), Department of Radiology, BP 77908, Dijon (France); Petit, Jean-Michel [University of Burgundy, INSERM U866, BP 87900, Dijon (France); CHU (University Hospital), Department of Endocrinology, Diabetology, and Metabolic Diseases, BP 77908, Dijon (France); Nougaret, Stephanie; Pierredon-Foulongne, Marie-Ange; Schembri, Valentina; Delhom, Elisabeth; Guiu, Boris [St-Eloi University Hospital, Department of Radiology, Montpellier (France); Soyer, Philippe [Hopital 1 Lariboisiere, Assistance Publique Hopitaux de Paris, Department of Body and Interventional Imaging, Paris Cedex 10 (France); Fohlen, Audrey [University Hospital, Department of Radiology, Caen (France); Schmidt, Sabine; Denys, Alban [Centre Hospitalier Universitaire Vaudois, Department of Radiology, Lausanne (Switzerland); Aho, Serge [CHU (University Hospital), Department of Biostatistics, BP 77908, Dijon (France)

    2015-06-01

    To determine whether a mono-, bi- or tri-exponential model best fits the intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) signal of normal livers. The pilot and validation studies were conducted in 38 and 36 patients with normal livers, respectively. The DWI sequence was performed using single-shot echoplanar imaging with 11 (pilot study) and 16 (validation study) b values. In each study, data from all patients were used to model the IVIM signal of normal liver. Diffusion coefficients (D{sub i} ± standard deviations) and their fractions (f{sub i} ± standard deviations) were determined from each model. The models were compared using the extra sum-of-squares test and information criteria. The tri-exponential model provided a better fit than both the bi- and mono-exponential models. The tri-exponential IVIM model determined three diffusion compartments: a slow (D{sub 1} = 1.35 ± 0.03 x 10{sup -3} mm{sup 2}/s; f{sub 1} = 72.7 ± 0.9 %), a fast (D{sub 2} = 26.50 ± 2.49 x 10{sup -3} mm{sup 2}/s; f{sub 2} = 13.7 ± 0.6 %) and a very fast (D{sub 3} = 404.00 ± 43.7 x 10{sup -3} mm{sup 2}/s; f{sub 3} = 13.5 ± 0.8 %) diffusion compartment [results from the validation study]. The very fast compartment contributed to the IVIM signal only for b values ≤15 s/mm{sup 2} The tri-exponential model provided the best fit for IVIM signal decay in the liver over the 0-800 s/mm{sup 2} range. In IVIM analysis of normal liver, a third very fast (pseudo)diffusion component might be relevant. (orig.)

  19. Dependence of the frequency spectrum of small amplitude vibrations superimposed on finite deformations of a nonlinear, cylindrical elastic body on residual stress

    KAUST Repository

    Gorb, Yuliya

    2010-11-01

    We model and analyze the response of nonlinear, residually stressed elastic bodies subjected to small amplitude vibrations superimposed upon large deformations. The problem derives from modeling the use of intravascular ultrasound (IVUS) imaging to interrogate atherosclerotic plaques in vivo in large arteries. The goal of this investigation is twofold: (i) introduce a modeling framework for residual stress that unlike traditional Fung type classical opening angle models may be used for a diseased artery, and (ii) investigate the sensitivity of the spectra of small amplitude high frequency time harmonic vibrations superimposed on a large deformation to the details of the residual stress stored in arteries through a numerical simulation using physiologic parameter values under both low and high blood pressure loadings. The modeling framework also points the way towards an inverse problem using IVUS techniques to estimate residual stress in healthy and diseased arteries. © 2010 Elsevier Ltd. All rights reserved.

  20. Accelerating Oil and Gas Exploration in Western China by Studies of Formations of Hydrocarbon Accumulations in Superimposed Basins——A Preface

    Institute of Scientific and Technical Information of China (English)

    PANG Xiongqi

    2010-01-01

    @@ The superimposed basins in the western region of China are a hot research topic for earth scientists home and abroad for their vast area and rich oil and gas resources.Their complex geological conditions and resultant great exploration difficulties have received much attention of the scientists.This issue presents the advances of several scholars in their long-term research on the mechanisms of oil and gas accumulation and the patterns of oil and gas distribution.These studies are part of the National 973Project entitled"Mechanism of Oil and Gas Accumulation and Patterns of Oil and Gas Distribution in Typical Superimposed Basins in the Western Region of China(no.2006CB202300)",which is funded by the Chinese Ministry of Science and Technology.

  1. Investigation of the Impact of a Heinrich-Event-like Abrupt Event Superimposed Onto the RCP 8.5 Scenario

    Science.gov (United States)

    Defrance, D.; Ramstein, G.; Dumas, C.; Charbit, S.

    2014-12-01

    The CMIP5/IPCC (AR5) projections of climate change showed the temperatures should increase by between 1.3 °C and 4.4 °C by 2100 and the sea level rise between 26 cm and 82 cm on average. Superimposed on these climatic and hydrologic trends associated with the RCP 8.5 most pessimistic scenario, it is important to investigate the possible effect of an abrupt event like an ice-sheet surge. This is first justified by the recent collapse of the Larsen B ice shelf which illustrates that a non-linear response of the cryosphere may occur in a warming world. Furthermore, in glacial periods, ice-sheets have been unstable and huge surges of icebergs did occur and deeply modified the climate. The aim of this presentation is to show the hypothetical climatic consequences of such a Heinrich-type event on future climate change. To achieve this goal, 3 scenarios of rapid ice-sheet deglaciation have been designed, corresponding to an additional sea level rise of around 3 m : - S1 corresponds to a contribution from Greenland only; - S2 from West-Antarctica only; - S3 from both ice-sheets. We use the global atmosphere-ocean general circulation model (OAGCM) IPSL-CM5A-LR. The freshwater perturbation is applied near the ice-sheet(s) during 20 years from 2050 to 2070 during an RCP8.5 perturbation. The RCP8.5 scenario is then continued until 2100 (without freshwater). For these types of scenarios, previous experiments for paleoclimatic cases help us diagnose the most vulnerable areas. The North Atlantic and the collapse of thermohaline circulation is one key issue, but far field teleconnections with the Asian monsoon will also be explored. We will investigate the timing and amplitude of the climate impacts due to the perturbations, which may be quite different in our 3 scenarios. These abrupt events consequences can be important for the populations and the consideration of rapid changes should improve the reliability of IPCC predictions.

  2. The γ parameter of the stretched-exponential model is influenced by internal gradients: Validation in phantoms

    Science.gov (United States)

    Palombo, Marco; Gabrielli, Andrea; De Santis, Silvia; Capuani, Silvia

    2012-03-01

    In this paper, we investigate the image contrast that characterizes anomalous and non-Gaussian diffusion images obtained using the stretched exponential model. This model is based on the introduction of the γ stretched parameter, which quantifies deviation from the mono-exponential decay of diffusion signal as a function of the b-value. To date, the biophysical substrate underpinning the contrast observed in γ maps, in other words, the biophysical interpretation of the γ parameter (or the fractional order derivative in space, β parameter) is still not fully understood, although it has already been applied to investigate both animal models and human brain. Due to the ability of γ maps to reflect additional microstructural information which cannot be obtained using diffusion procedures based on Gaussian diffusion, some authors propose this parameter as a measure of diffusion heterogeneity or water compartmentalization in biological tissues. Based on our recent work we suggest here that the coupling between internal and diffusion gradients provide pseudo-superdiffusion effects which are quantified by the stretching exponential parameter γ. This means that the image contrast of Mγ maps reflects local magnetic susceptibility differences (Δχm), thus highlighting better than T2∗ contrast the interface between compartments characterized by Δχm. Thanks to this characteristic, Mγ imaging may represent an interesting tool to develop contrast-enhanced MRI for molecular imaging. The spectroscopic and imaging experiments (performed in controlled micro-beads dispersion) that are reported here, strongly suggest internal gradients, and as a consequence Δχm, to be an important factor in fully understanding the source of contrast in anomalous diffusion methods that are based on a stretched exponential model analysis of diffusion data obtained at varying gradient strengths g.

  3. Modified Binary Exponential Backoff Algorithm to Minimize Mobiles Communication Time

    Directory of Open Access Journals (Sweden)

    Ibrahim Sayed Ahmad

    2014-02-01

    Full Text Available the field of Wireless Local Area Networks (LANs is expanding rapidly as a result of advances in digital communications, portable computers, and semiconductor technology. The early adopters of this technology have primarily been vertical application that places a premium on the mobility offered by such systems. Binary Exponential Backoff (BEB refers to a collision resolution mechanism used in random access MAC protocols. This algorithm is used in Ethernet (IEEE 802.3 wired LANs. In Ethernet networks, this algorithm is commonly used to schedule retransmissions after collisions. The paper’s goal is to minimize the time transmission cycle of the information between mobiles moving in a Wi-Fi by changing the BEB algorithm. The Protocol CSMA / CA manage access to the radio channel by performing an arbitration based on time. This causes many problems in relation to time transmission between mobiles moving in a cell 802.11. what we have done show that the protocol using CSMA / CA access time believed rapidly when the number of stations and / or the network load increases or other circumstances affects the network.

  4. Predictors of the peak width for networks with exponential links

    Science.gov (United States)

    Troutman, B.M.; Karlinger, M.R.

    1989-01-01

    We investigate optimal predictors of the peak (S) and distance to peak (T) of the width function of drainage networks under the assumption that the networks are topologically random with independent and exponentially distributed link lengths. Analytical results are derived using the fact that, under these assumptions, the width function is a homogeneous Markov birth-death process. In particular, exact expressions are derived for the asymptotic conditional expectations of S and T given network magnitude N and given mainstream length H. In addition, a simulation study is performed to examine various predictors of S and T, including N, H, and basin morphometric properties; non-asymptotic conditional expectations and variances are estimated. The best single predictor of S is N, of T is H, and of the scaled peak (S divided by the area under the width function) is H. Finally, expressions tested on a set of drainage basins from the state of Wyoming perform reasonably well in predicting S and T despite probable violations of the original assumptions. ?? 1989 Springer-Verlag.

  5. Exponential 6 parameterization for the JCZ3-EOS

    Energy Technology Data Exchange (ETDEWEB)

    McGee, B.C.; Hobbs, M.L.; Baer, M.R.

    1998-07-01

    A database has been created for use with the Jacobs-Cowperthwaite-Zwisler-3 equation-of-state (JCZ3-EOS) to determine thermochemical equilibrium for detonation and expansion states of energetic materials. The JCZ3-EOS uses the exponential 6 intermolecular potential function to describe interactions between molecules. All product species are characterized by r*, the radius of the minimum pair potential energy, and {var_epsilon}/k, the well depth energy normalized by Boltzmann`s constant. These parameters constitute the JCZS (S for Sandia) EOS database describing 750 gases (including all the gases in the JANNAF tables), and have been obtained by using Lennard-Jones potential parameters, a corresponding states theory, pure liquid shock Hugoniot data, and fit values using an empirical EOS. This database can be used with the CHEETAH 1.40 or CHEETAH 2.0 interface to the TIGER computer program that predicts the equilibrium state of gas- and condensed-phase product species. The large JCZS-EOS database permits intermolecular potential based equilibrium calculations of energetic materials with complex elemental composition.

  6. Characterizing quantum correlations. Entanglement, uncertainty relations and exponential families

    Energy Technology Data Exchange (ETDEWEB)

    Niekamp, Soenke

    2012-04-20

    This thesis is concerned with different characterizations of multi-particle quantum correlations and with entropic uncertainty relations. The effect of statistical errors on the detection of entanglement is investigated. First, general results on the statistical significance of entanglement witnesses are obtained. Then, using an error model for experiments with polarization-entangled photons, it is demonstrated that Bell inequalities with lower violation can have higher significance. The question for the best observables to discriminate between a state and the equivalence class of another state is addressed. Two measures for the discrimination strength of an observable are defined, and optimal families of observables are constructed for several examples. A property of stabilizer bases is shown which is a natural generalization of mutual unbiasedness. For sets of several dichotomic, pairwise anticommuting observables, uncertainty relations using different entropies are constructed in a systematic way. Exponential families provide a classification of states according to their correlations. In this classification scheme, a state is considered as k-correlated if it can be written as thermal state of a k-body Hamiltonian. Witness operators for the detection of higher-order interactions are constructed, and an algorithm for the computation of the nearest k-correlated state is developed.

  7. Kinetically Modified Non-Minimal Inflation With Exponential Frame Function

    CERN Document Server

    Pallis, C

    2016-01-01

    We consider Supersymmetric (SUSY) and non-SUSY models of chaotic inflation based on the phi^n potential with n=2 or 4. We show that the coexistence of an exponential nonminimal coupling to gravity, fR=Exp(cR phi^p), with a kinetic mixing of the form fK=cK fR^m can accommodate inflationary observables favored by the Planck and Bicep2/Keck Array results for p=1 and 2, 1<=m<=15 and 2.6x10^(-3)<=rRK=cR/cK^(p/2)<=1, where the upper limit is not imposed for p=1. Inflation is of hilltop type and it can be attained for subplanckian inflaton values with the corresponding effective theories retaining the perturbative unitarity up to the Planck scale. The supergravity embedding of these models is achieved employing two chiral gauge singlet supefields, a monomial superpotential and several (semi)logarithmic or semipolynomial Kaehler potentials.

  8. Absence of exponential clustering in quantum Coulomb fluids

    Science.gov (United States)

    Alastuey, A.; Martin, Ph. A.

    1989-12-01

    We show that the quantum corrections to the classical correlations of a Coulomb fluid do not decay exponentially fast for all values of the thermodynamical parameters. Specifically, the ħ4 term in the Wigner-Kirkwood expansion of the equilibrium charge-charge correlations of the quantum one-component plasma is found to decay like ||r||-10. More generally, using functional integration, we present a diagrammatic representation of the ħ expansion of the correlations in a multicomponent fluid with a locally regularized Coulomb potential and Maxwell-Boltzmann statistics. The ħ2n terms are found to decay algebraically for all n>=2. Furthermore, an analysis of the hierarchy equations for the correlations provides upper bounds that are compatible with the findings of the perturbative expansion. Except for the monopole, all higher-order multipole sum rules do not hold, in general, in the quantum system. This violation of the multipole sum rules as well as the related algebraic tails are due to the intrinsic quantum fluctuations that prevent a perfect organization of the screening clouds. This phenomenon is illustrated in a simpler model where the large-distance correlations between two quantum particles embedded in a classical plasma can be exactly computed.

  9. A Study on The Mixture of Exponentiated-Weibull Distribution

    Directory of Open Access Journals (Sweden)

    Adel Tawfik Elshahat

    2016-12-01

    Full Text Available Mixtures of measures or distributions occur frequently in the theory and applications of probability and statistics. In the simplest case it may, for example, be reasonable to assume that one is dealing with the mixture in given proportions of a finite number of normal populations with different means or variances. The mixture parameter may also be denumerable infinite, as in the theory of sums of a random number of random variables, or continuous, as in the compound Poisson distribution. The use of finite mixture distributions, to control for unobserved heterogeneity, has become increasingly popular among those estimating dynamic discrete choice models. One of the barriers to using mixture models is that parameters that could previously be estimated in stages must now be estimated jointly: using mixture distributions destroys any additive reparability of the log likelihood function. In this thesis, the maximum likelihood estimators have been obtained for the parameters of the mixture of exponentiated Weibull distribution when sample is available from censoring scheme. The maximum likelihood estimators of the parameters and the asymptotic variance covariance matrix have been also obtained. A numerical illustration for these new results is given.

  10. Optimal ambiguity functions and Weil's exponential sum bound

    CERN Document Server

    Benedetto, John J; Woodworth, Joseph T

    2011-01-01

    Complex-valued periodic sequences, u, constructed by Goran Bjorck, are analyzed with regard to the behavior of their discrete periodic narrow-band ambiguity functions A_p(u). The Bjorck sequences, which are defined on Z/pZ for p>2 prime, are unimodular and have zero autocorrelation on (Z/pZ)\\{0}. These two properties give rise to the acronym, CAZAC, to refer to constant amplitude zero autocorrelation sequences. The bound proven is |A_p(u)| \\leq 2/\\sqrt{p} + 4/p outside of (0,0), and this is of optimal magnitude given the constraint that u is a CAZAC sequence. The proof requires the full power of Weil's exponential sum bound, which, in turn, is a consequence of his proof of the Riemann hypothesis for finite fields. Such bounds are not only of mathematical interest, but they have direct applications as sequences in communications and radar, as well as when the sequences are used as coefficients of phase-coded waveforms.

  11. Mutant number distribution in an exponentially growing population

    Science.gov (United States)

    Keller, Peter; Antal, Tibor

    2015-01-01

    We present an explicit solution to a classic model of cell-population growth introduced by Luria and Delbrück (1943 Genetics 28 491-511) 70 years ago to study the emergence of mutations in bacterial populations. In this model a wild-type population is assumed to grow exponentially in a deterministic fashion. Proportional to the wild-type population size, mutants arrive randomly and initiate new sub-populations of mutants that grow stochastically according to a supercritical birth and death process. We give an exact expression for the generating function of the total number of mutants at a given wild-type population size. We present a simple expression for the probability of finding no mutants, and a recursion formula for the probability of finding a given number of mutants. In the ‘large population-small mutation’ limit we recover recent results of Kessler and Levine (2014 J. Stat. Phys. doi:10.1007/s10955-014-1143-3) for a fully stochastic version of the process.

  12. Exponential flux-controlled memristor model and its floating emulator

    Science.gov (United States)

    Liu, Wei; Wang, Fa-Qiang; Ma, Xi-Kui

    2015-11-01

    As commercial memristors are still unavailable in the market, mathematic models and emulators which can imitate the features of the memristor are meaningful for further research. In this paper, based on the analyses of characteristics of the q-φ curve, an exponential flux-controlled model, which has the quality that its memductance (memristance) will keep monotonically increasing or decreasing unless the voltage’s polarity reverses (if not approach the boundaries), is constructed. A new approach to designing the floating emulator of the memristor is also proposed. This floating structure can flexibly meet various demands for the current through the memristor (especially the demand for a larger current). The simulations and experiments are presented to confirm the effectiveness of this model and its floating emulator. Project supported by the National Natural Science Foundation of China (Grant Nos. 51377124 and 51221005), the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 201337), the Program for New Century Excellent Talents in University of China (Grant No. NCET-13-0457), and the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2012JQ7026).

  13. Fermat quotients: Exponential sums, value set and primitive roots

    CERN Document Server

    Shparlinski, Igor E

    2011-01-01

    For a prime $p$ and an integer $u$ with $\\gcd(u,p)=1$, we define Fermat quotients by the conditions $$ q_p(u) \\equiv \\frac{u^{p-1} -1}{p} \\pmod p, \\qquad 0 \\le q_p(u) \\le p-1. $$ D. R. Heath-Brown has given a bound of exponential sums with $N$ consecutive Fermat quotients that is nontrivial for $N\\ge p^{1/2+\\epsilon}$ for any fixed $\\epsilon>0$. We use a recent idea of M. Z. Garaev together with a form of the large sieve inequality due to S. Baier and L. Zhao, to show that on average over $p$ one can obtain a nontrivial estimate for much shorter sums starting with $N\\ge p^{\\epsilon}$. We also obtain lower bounds on the image size of the first $N$ consecutive Fermat quotients and use it to prove that there is a positive integer $n\\le p^{3/4 + o(1)}$ such that $q_p(n)$ is a primitive root modulo $p$.

  14. Exponential Polynomials as Solutions of Certain Nonlinear Difference Equations

    Institute of Scientific and Technical Information of China (English)

    Zhi Tao WEN; Janne HEITTOKANGAS; Ilpo LAINE

    2012-01-01

    Recently,C.-C.Yang and I.Laine have investigated finite order entire solutions f of nonlinear differential-difference equations of the form fn+L(z,f)=h,where n ≥ 2 is an integer.In particular,it is known that the equation f(z)2+q(z)f(z+1) =p(z),where p(z),q(z) are polynomials,has no transcendental entire solutions of finite order.Assuming that Q(z) is also a polynomial and c ∈ C,equations of the form f(z)n + q(z)eQ(z)f(z + c) =p(z) do posses finite order entire solutions.A classification of these solutions in terms of growth and zero distribution will be given.In particular,it is shown that any exponential polynomial solution must reduce to a rather specific form.This reasoning relies on an earlier paper due to N.Steinmetz.

  15. Synchronization and Exponential Estimates of Complex Networks with Mixed Time-varying Coupling Delays

    Institute of Scientific and Technical Information of China (English)

    Yang Dai; YunZe Cai; Xiao-Ming Xu

    2009-01-01

    Exponential estimates and sufficient conditions for the exponential synchronization of complex dynamical networks with bounded time-varying delays are given in terms of linear matrix inequalities (LMIs). A generalized complex networks model involving both neutral delays and retarded ones is presented. The exponential synchronization problem of the complex networks is converted equivalently into the exponential stability problem of a group of uncorrelated delay functional differential equations with mixed time-varying delays. By utilizing the free weighting matrix technique, a less conservative delay-dependent synchronization criterion is derived. An illustrative example is provided to demonstrate the effectiveness of the proposed method.

  16. New Nonequilibrium-to-Equilibrium Dynamical Scaling and Stretched-Exponential Critical Relaxation in Cluster Algorithms

    Science.gov (United States)

    Nonomura, Yoshihiko

    2014-11-01

    Nonequilibrium relaxation behaviors in the Ising model on a square lattice based on the Wolff algorithm are totally different from those based on local-update algorithms. In particular, the critical relaxation is described by the stretched-exponential decay. We propose a novel scaling procedure to connect nonequilibrium and equilibrium behaviors continuously, and find that the stretched-exponential scaling region in the Wolff algorithm is as wide as the power-law scaling region in local-update algorithms. We also find that relaxation to the spontaneous magnetization in the ordered phase is characterized by the exponential decay, not the stretched-exponential decay based on local-update algorithms.

  17. Recursive Least Squares Estimator with Multiple Exponential Windows in Vector Autoregression

    Institute of Scientific and Technical Information of China (English)

    Hong-zhi An; Zhi-guo Li

    2002-01-01

    In the parameter tracking of time-varying systems, the ordinary method is weighted least squares with the rectangular window or the exponential window. In this paper we propose a new kind of sliding window called the multiple exponential window, and then use it to fit time-varying Gaussian vector autoregressive models. The asymptotic bias and covariance of the estimator of the parameter for time-invariant models are also derived. Simulation results show that the multiple exponential windows have better parameter tracking effect than rectangular windows and exponential ones.

  18. Generalized Exponential Distribution in Flood Frequency Analysis for Polish Rivers

    Science.gov (United States)

    Markiewicz, Iwona; Strupczewski, Witold G.; Bogdanowicz, Ewa; Kochanek, Krzysztof

    2015-01-01

    Many distributions have been used in flood frequency analysis (FFA) for fitting the flood extremes data. However, as shown in the paper, the scatter of Polish data plotted on the moment ratio diagram shows that there is still room for a new model. In the paper, we study the usefulness of the generalized exponential (GE) distribution in flood frequency analysis for Polish Rivers. We investigate the fit of GE distribution to the Polish data of the maximum flows in comparison with the inverse Gaussian (IG) distribution, which in our previous studies showed the best fitting among several models commonly used in FFA. Since the use of a discrimination procedure without the knowledge of its performance for the considered probability density functions may lead to erroneous conclusions, we compare the probability of correct selection for the GE and IG distributions along with the analysis of the asymptotic model error in respect to the upper quantile values. As an application, both GE and IG distributions are alternatively assumed for describing the annual peak flows for several gauging stations of Polish Rivers. To find the best fitting model, four discrimination procedures are used. In turn, they are based on the maximized logarithm of the likelihood function (K procedure), on the density function of the scale transformation maximal invariant (QK procedure), on the Kolmogorov-Smirnov statistics (KS procedure) and the fourth procedure based on the differences between the ML estimate of 1% quantile and its value assessed by the method of moments and linear moments, in sequence (R procedure). Due to the uncertainty of choosing the best model, the method of aggregation is applied to estimate of the maximum flow quantiles. PMID:26657239

  19. Minimizing Mobiles Communication Time Using Modified Binary Exponential Backoff Algorithm

    Directory of Open Access Journals (Sweden)

    Ibrahim Sayed Ahmad

    2013-11-01

    Full Text Available The domain of wireless Local Area Networks (WLANsis growing speedily as a consequence ofdevelopments in digital communications technology.The early adopters of this technology have mainlybeen vertical applicationthat places a premium on the mobility offered by such systems. Examples of thesetypes of applications consist of stocking control in depot environments,point of sale terminals, and rentalcar check-in. Furthermore to the mobility thatbecomes possible with wireless LANs; these systemshavealso been used in environments where cable installation is expensive or impractical. Such environmentsincludemanufacturingfloors, tradingfloors on stock exchanges, conventions and trade shows,and historicbuildings. With the increasing propagation of wireless LANs comes theneed for standardization so as toallow interoperability for an increasingly mobileworkforce. Despite all the advantages and facilities thatWi-FI offers, there is still the delay problem thatis due to many reasons that are introduced in details inour case study which also presents the solutions and simulation that can reduce this delay for betterperformance of the wireless networks.Binary Exponential Backoff (BEB refers to a collision resolution mechanism used in random access MACprotocols. This algorithm is used in Ethernet (IEEE802.3 wired LANs. In Ethernet networks, thisalgorithm is commonly used to schedule retransmissions after collisions.The paper’s goal is to minimize the time transmission cycle of the information between mobiles movingin aWi-Fi by changing the BEB algorithm. The Protocol CSMA / CA manage access to the radio channel byperforming an arbitration based on time. This causes many problems in relation to time transmissionbetween mobiles moving in a cell 802.11. what we have done show that the protocol using CSMA / CAaccess time believed rapidly when the number of stations and / or the network load increases or othercircumstances affects the network.

  20. Generalized Exponential Distribution in Flood Frequency Analysis for Polish Rivers.

    Science.gov (United States)

    Markiewicz, Iwona; Strupczewski, Witold G; Bogdanowicz, Ewa; Kochanek, Krzysztof

    2015-01-01

    Many distributions have been used in flood frequency analysis (FFA) for fitting the flood extremes data. However, as shown in the paper, the scatter of Polish data plotted on the moment ratio diagram shows that there is still room for a new model. In the paper, we study the usefulness of the generalized exponential (GE) distribution in flood frequency analysis for Polish Rivers. We investigate the fit of GE distribution to the Polish data of the maximum flows in comparison with the inverse Gaussian (IG) distribution, which in our previous studies showed the best fitting among several models commonly used in FFA. Since the use of a discrimination procedure without the knowledge of its performance for the considered probability density functions may lead to erroneous conclusions, we compare the probability of correct selection for the GE and IG distributions along with the analysis of the asymptotic model error in respect to the upper quantile values. As an application, both GE and IG distributions are alternatively assumed for describing the annual peak flows for several gauging stations of Polish Rivers. To find the best fitting model, four discrimination procedures are used. In turn, they are based on the maximized logarithm of the likelihood function (K procedure), on the density function of the scale transformation maximal invariant (QK procedure), on the Kolmogorov-Smirnov statistics (KS procedure) and the fourth procedure based on the differences between the ML estimate of 1% quantile and its value assessed by the method of moments and linear moments, in sequence (R procedure). Due to the uncertainty of choosing the best model, the method of aggregation is applied to estimate of the maximum flow quantiles.

  1. EXPONENTIAL TIME DIFFERENCING FOR HODGKIN-HUXLEY-LIKE ODES.

    Science.gov (United States)

    Börgers, Christoph; Nectow, Alexander R

    2013-01-01

    Several authors have proposed the use of exponential time differencing (ETD) for Hodgkin-Huxley-like partial and ordinary differential equations (PDEs and ODEs). For Hodgkin-Huxley-like PDEs, ETD is attractive because it can deal effectively with the stiffness issues that diffusion gives rise to. However, large neuronal networks are often simulated assuming "space-clamped" neurons, i.e., using the Hodgkin-Huxley ODEs, in which there are no diffusion terms. Our goal is to clarify whether ETD is a good idea even in that case. We present a numerical comparison of first- and second-order ETD with standard explicit time-stepping schemes (Euler's method, the midpoint method, and the classical fourth-order Runge-Kutta method). We find that in the standard schemes, the stable computation of the very rapid rising phase of the action potential often forces time steps of a small fraction of a millisecond. This can result in an expensive calculation yielding greater overall accuracy than needed. Although it is tempting at first to try to address this issue with adaptive or fully implicit time-stepping, we argue that neither is effective here. The main advantage of ETD for Hodgkin-Huxley-like systems of ODEs is that it allows underresolution of the rising phase of the action potential without causing instability, using time steps on the order of one millisecond. When high quantitative accuracy is not necessary and perhaps, because of modeling inaccuracies, not even useful, ETD allows much faster simulations than standard explicit time-stepping schemes. The second-order ETD scheme is found to be substantially more accurate than the first-order one even for large values of Δt.

  2. Surface properties and exponential stress relaxations of mammalian meibum films.

    Science.gov (United States)

    Eftimov, Petar; Yokoi, Norihiko; Tonchev, Vesselin; Nencheva, Yana; Georgiev, Georgi As

    2017-03-01

    The surface properties of meibomian secretion (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The interfacial properties of canine, cMGS, and feline, fMGS, meibum films were studied using a Langmuir surface balance. These species were selected because they have blinking frequency and TF stability similar to those of humans. The sample's performance during dynamic area changes was evaluated by surface pressure (π)-area (A) isocycles and the layer structure was monitored with Brewster angle microscopy. The films' dilatational rheology was probed via the stress-relaxation technique. The animal MGS showed similar behavior both between each other and with human MGS (studied previously). They form reversible, non-collapsible, multilayer thick films. The relaxations of canine, feline, and human MGS films were well described by double exponential decay reflecting the presence of two processes: (1) fast elastic process, with characteristic time τ  100 s-emphasizing the meibum layers viscoelasticity. The temperature decrease from 35 to 25 °C resulted in decreased thickness and lateral expansion of all MGS layers accompanied with increase of the π/A hysteresis and of the elastic process contribution to π relaxation transients. Thus, MGS films of mammals with similar blinking frequency and TF stability have similar surface properties and stress relaxations unaltered by the interspecies MGS compositional variations. Such knowledge may impact the selection of animal mimics of human MGS and on a better understanding of lipid classes' impact on meibum functionality.

  3. Rapid and ultrasensitive detection of microRNA by target-assisted isothermal exponential amplification coupled with poly (thymine)-templated fluorescent copper nanoparticles

    Science.gov (United States)

    Park, Kwan Woo; Batule, Bhagwan S.; Kang, Kyoung Suk; Park, Ki Soo; Park, Hyun Gyu

    2016-10-01

    We devised a novel method for rapid and ultrasensitive detection of target microRNA (miRNA) by employing target-assisted isothermal exponential amplification (TAIEA) combined with poly (thymine)-templated fluorescent copper nanoparticles (CuNPs) as signaling probes. The target miRNA hybridizes to the unimolecular template DNA and works as a primer for the extension reaction to form double-stranded product, which consequently generates two nicking endonuclease recognition sites. By simultaneous nicking and displacement reactions, exponential amplification generates many poly (thymine) strands as final products, which are employed for the synthesis of fluorescent CuNPs. Based on the fluorescent signal from CuNPs, target miRNA is detected as low as 0.27 fM around 1 h of total analysis time. The diagnostic capability of this system has been successfully demonstrated by reliably detecting target miRNA from different cell lysates, showing its great potential towards real clinical applications.

  4. Recognition of the reference signals at interference generation and loss at random times

    Directory of Open Access Journals (Sweden)

    Виктор Васильевич Авраменко

    2016-03-01

    Full Text Available This article describes the reference of the signal recognition method, which is superimposed on the random additive interference. References, in turn, can be various types of pulses, which makes impossible the calculation of their derivatives in some times. Also, reference includes in the analyzed signal with a certain advance unknown scale factor. The proposed method allows determining a fragment of the references included in the analyzed signal at random time

  5. Model Order Selection for Short Data: An Exponential Fitting Test (EFT

    Directory of Open Access Journals (Sweden)

    Martin Haardt

    2007-01-01

    Full Text Available High-resolution methods for estimating signal processing parameters such as bearing angles in array processing or frequencies in spectral analysis may be hampered by the model order if poorly selected. As classical model order selection methods fail when the number of snapshots available is small, this paper proposes a method for noncoherent sources, which continues to work under such conditions, while maintaining low computational complexity. For white Gaussian noise and short data we show that the profile of the ordered noise eigenvalues is seen to approximately fit an exponential law. This fact is used to provide a recursive algorithm which detects a mismatch between the observed eigenvalue profile and the theoretical noise-only eigenvalue profile, as such a mismatch indicates the presence of a source. Moreover this proposed method allows the probability of false alarm to be controlled and predefined, which is a crucial point for systems such as RADARs. Results of simulations are provided in order to show the capabilities of the algorithm.

  6. Modeling shock waves using exponential interpolation functions with the Least-Squares Finite Element method

    Science.gov (United States)

    Smith, Bradford Scott, Jr.

    The hypothesis of this research is that exponential interpolation functions will approximate fluid properties at shock waves with less error than polynomial interpolation functions. Exponential interpolation functions are derived for the purpose of modeling sharp gradients. General equations for conservation of mass, momentum, and energy for an inviscid flow of a perfect gas are converted to finite element equations using the least-squares method. Boundary conditions and a mesh adaptation scheme are also presented. An oblique shock reflection problem is used as a benchmark to determine whether or not exponential interpolation provides any advantages over Lagrange polynomial interpolation. Using exponential interpolation in elements downstream of a shock and having edges coincident with the shock showed a slight reduction in the solution error. However there was very little qualitative difference between solutions using polynomial and exponential interpolation. Regardless of the type of interpolation used, the shocks were smeared and oscillations were present both upstream and downstream of the shock waves. When a mesh adaptation scheme was implemented, exponential elements adjacent to the shock waves became much smaller and the numerical solution diverged. Changing the exponential elements to polynomial elements yielded a convergent solution. There appears to be no significant advantage to using exponential interpolation in comparison to Lagrange polynomial interpolation.

  7. Feller property and exponential ergodicity of diffusion processes with state-dependent switching

    Institute of Scientific and Technical Information of China (English)

    XI FuBao

    2008-01-01

    In this paper we consider the Feller property and the exponential ergodicity for general diffusion processes with State-dependent switching. We prove their Feller continuity by means of intro-ducing some auxiliary processes and by making use of the Radon-Nikodym derivatives. Furthermore, we also prove their strong Feller continuity and their exponential ergodicity under some reasonable conditions.

  8. Gradient flow of the stochastic relaxation on a generic exponential family

    Energy Technology Data Exchange (ETDEWEB)

    Malagò, Luigi, E-mail: malago@shinshu-u.ac.jp [Collegio Carlo Alberto, Via Real Collegio 30, 10024 Moncalieri, Italy and Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Pistone, Giovanni, E-mail: giovanni.pistone@carloalberto.org [Collegio Carlo Alberto, Via Real Collegio 30, 10024 Moncalieri (Italy)

    2015-01-13

    We study the natural gradient flow of the expected value E{sub p} [f] of an objective function f for p in an exponential family. We parameterize the exponential family with the expectation parameters and we show that the dynamical system associated to the natural gradient flow can be extended outside the marginal polytope.

  9. Exponential stability of Takagi-Sugeno fuzzy systems with impulsive effects and small delays

    Institute of Scientific and Technical Information of China (English)

    Yu Yong-Bin; Zhong Qi-Shui; Liao Xiao-Feng; Yu Jue-Bang

    2008-01-01

    This paper deals with the exponential stability of impulsive Takagi-Sugeno fuzzy systems with delay. Impulsive control and delayed fuzzy control are applied to the system, and the criterion on exponential stability expressed in terms of linear matrix inequalities (LMIs) is presented.

  10. Existence and exponential stability for impulsive stochastic partial functional differential equations

    Science.gov (United States)

    Xiao, Shuiming; Chen, Huabin

    2017-03-01

    In this paper, the existence and uniqueness, the exponential stability, and the almost sure exponential stability of mild solution for impulsive stochastic partial functional differential equations with finite delay are considered. Some sufficient conditions are established for our concerned problems, and some existing results are generalized and improved. Finally, an illustrative example is provided to show the feasibility and effectiveness of the obtained results.

  11. Improved delay-dependent exponential stability for uncertain stochastic neural networks with time-varying delays

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, O.M., E-mail: madwind@chungbuk.ac.k [School of Electrical Engineering, Chungbuk National University, Cheongju (Korea, Republic of); Lee, S.M., E-mail: moony@daegu.ac.k [School of Electronics Engineering, Daegu University, Kyongsan (Korea, Republic of); Park, Ju H., E-mail: jessie@ynu.ac.k [Department of Electrical Engineering, Yeungnam University, Kyongsan (Korea, Republic of)

    2010-02-22

    This Letter investigates the problem of delay-dependent exponential stability analysis for uncertain stochastic neural networks with time-varying delay. Based on the Lyapunov stability theory, improved delay-dependent exponential stability criteria for the networks are established in terms of linear matrix inequalities (LMIs).

  12. Exponential estimation of generalized state-space time-delay systems

    Energy Technology Data Exchange (ETDEWEB)

    Lien, C-H; Yu, K-W [Department of Marine Engineering, National Kaohsiung Marine University, Taiwan 811 (China); Lin, J-S; Hung, M-L [Department of Electrical Engineering, Far East University, Tainan, Taiwan 744 (China)], E-mail: chlien@mail.nkmu.edu.tw

    2008-02-15

    In this paper, global exponential stability for a class of generalized state-space time-delay systems is considered. Delay-dependent criteria are proposed to guarantee the exponential stability and estimate the convergence rate for the generalized state-space systems with two cases of uncertainties. Finally, some numerical examples are illustrated to show the usefulness of the theory.

  13. Global stabilizer of a general class of feedback nonlinear systems and its exponential convergence

    Institute of Scientific and Technical Information of China (English)

    Runing MA; Jundi DIAN

    2005-01-01

    We discuss the global stabilization procedure which renders a general class of feedback nonlinear systems exponential convergent. Our stabilizer consists of a nested saturation function, which is a nonlinear combination of satrration functions. Here we prove the exponential convergence of the stabilizer for the first time and give numerical examples to illustrate the efficiency of the result given above.

  14. GLOBAL ATTRACTIVITY AND GLOBAL EXPONENTIAL STABILITY FOR DELAYED HOPFIELD NEURAL NETWORK MODELS

    Institute of Scientific and Technical Information of China (English)

    蒲志林; 徐道义

    2001-01-01

    Some global properties such as global attractivity and global exponential stability for delayed Hopfield neural networks model, under the weaker assumptions on nonlinear activation functions, are concerned. By constructing suitable Liapunov function, some simpler criteria for global attractivity and global exponential stability for Hopfield continuous neural networks with time delays are presented.

  15. Feller property and exponential ergodicity of diffusion processes with state-dependent switching

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper we consider the Feller property and the exponential ergodicity for general diffusion processes with state-dependent switching. We prove their Feller continuity by means of intro- ducing some auxiliary processes and by making use of the Radon-Nikodym derivatives. Furthermore, we also prove their strong Feller continuity and their exponential ergodicity under some reasonable conditions.

  16. Exponential martingale for compound Poisson process with latent variable and its applications

    Institute of Scientific and Technical Information of China (English)

    YAN Jun

    2015-01-01

    In this article, we construct an exponential martingale for the compound Poisson process with latent variable. With the help of this exponential martingale, we provide an asymptotic behavior of the coherent entropic risk measure for the compound Poisson process and a deviation inequality for the ruin probability of the partly shifted risk process.

  17. Recent developments in exponential random graph (p*) models for social networks

    NARCIS (Netherlands)

    Robins, Garry; Snijders, Tom; Wang, Peng; Handcock, Mark; Pattison, Philippa

    2007-01-01

    This article reviews new specifications for exponential random graph models proposed by Snijders et al. [Snijders, T.A.B., Pattison, P., Robins, G.L., Handcock, M., 2006. New specifications for exponential random graph models. Sociological Methodology] and demonstrates their improvement over homogen

  18. A short guide to exponential Krylov subspace time integration for Maxwell's equations

    NARCIS (Netherlands)

    Botchev, Mike A.

    2012-01-01

    The exponential time integration, i.e., time integration which involves the matrix exponential, is an attractive tool for solving Maxwell's equations in time. However, its application in practice often requires a substantial knowledge of numerical linear algebra algorithms, in particular, of the Kry

  19. Exponential self-replication enabled through a fibre elongation/breakage mechanism

    NARCIS (Netherlands)

    Colomb-Delsuc, Mathieu; Mattia, Elio; Sadownik, Jan W; Otto, Sijbren

    2015-01-01

    Self-replicating molecules are likely to have played a central role in the origin of life. Most scenarios of Darwinian evolution at the molecular level require self-replicators capable of exponential growth, yet only very few exponential replicators have been reported to date and general design crit

  20. Teaching the Verhulst Model: A Teaching Experiment in Covariational Reasoning and Exponential Growth

    Science.gov (United States)

    Castillo-Garsow, Carlos

    2010-01-01

    Both Thompson and the duo of Confrey and Smith describe how students might be taught to build "ways of thinking" about exponential behavior by coordinating the covariation of two changing quantities, however, these authors build exponential behavior from different meanings of covariation. Confrey and Smith advocate beginning with discrete additive…