Cycle Lengths and Correlation Properties of Finite Precision Chaotic Maps

2014 ◽  
Vol 24 (09) ◽  
pp. 1450107 ◽  
Author(s):  
İsmail Öztürk ◽  
Recai Kiliç
Keyword(s):  
Chaotic Maps ◽  
Initial Conditions ◽  
Statistical Tests ◽  
Initial Condition ◽  
Security Vulnerabilities ◽  
Finite Precision ◽  
Cycle Lengths ◽  
Highly Correlated ◽  
Number Of Cycles ◽  
Correlation Properties

This paper investigates cycle and transient lengths of spatially discretized chaotic maps with respect to different initial condition values. By investigating cycle lengths and their correlation properties using fixed point arithmetic, it is observed that for different initial condition values only a limited number of cycles occur for each resolution and rounding type. Additionally, it is seen that cycles with the same length are actually identical due to intersections between pseudo trajectories. The drawbacks of this situation are demonstrated for chaos based cryptosystems that use initial conditions as key. It is shown that highly correlated outputs for different initial conditions cause serious security vulnerabilities, although the statistical tests indicate otherwise. Finally, correlations in the perturbed systems are discussed.

Is it a Right Assumption That B and Ge are Distributed Randomly After Growing a Strained HBT-Structure?

2002 ◽  
Vol 716 ◽  
Author(s):  
Victor I. Kol'dyaev
Keyword(s):  
Surface Segregation ◽  
Initial Conditions ◽  
Initial Condition ◽  
Basic Assumptions ◽  
Transient Diffusion ◽  
Segregation Process ◽  
Main Observation

AbstractIt is accepted that surface Ge atoms are considered to be responsible for the surface B segregation process. A set of original experiments is carried out. A main observation from the B and Ge profiles grown at different conditions shows that at certain conditions B is taking initiative and determine the Ge surface segregation process. basic assumptions are suggested to self-consistently explain these original experimental features and what is observed in the literature. These results have a strong implication for modeling the B diffusion in Si1-xGex where the initial conditions should be formulated accounting for the correlation in B and Ge distribution. A new assumption for the initial condition to be “all B atoms are captured by Ge” is regarded as a right one implicating that there is no any transient diffusion representing the B capturing kinetics.

scholarly journals Application of Adjoint-Derived Forecast Sensitivities to the 24–25 January 2000 U.S. East Coast Snowstorm

2005 ◽  
Vol 133 (11) ◽  
pp. 3148-3175 ◽  
Author(s):  
Daryl T. Kleist ◽  
Michael C. Morgan
Keyword(s):  
Response Function ◽  
Initial Conditions ◽  
Forecast Error ◽  
Weather Prediction ◽  
Lower Troposphere ◽  
Vertical Motion ◽  
Initial Condition ◽  
Response Functions ◽  
Eastern United States ◽  
Surface Cyclone

Abstract The 24–25 January 2000 eastern United States snowstorm was noteworthy as operational numerical weather prediction (NWP) guidance was poor for lead times as short as 36 h. Despite improvements in the forecast of the surface cyclone position and intensity at 1200 UTC 25 January 2000 with decreasing lead time, NWP guidance placed the westward extent of the midtropospheric, frontogenetically forced precipitation shield too far to the east. To assess the influence of initial condition uncertainties on the forecast of this event, an adjoint model is used to evaluate forecast sensitivities for 36- and 48-h forecasts valid at 1200 UTC 25 January 2000 using as response functions the energy-weighted forecast error, lower-tropospheric circulation about a box surrounding the surface cyclone, 750-hPa frontogenesis, and vertical motion. The sensitivities with respect to the initial conditions for these response functions are in general very similar: geographically isolated, maximized in the middle and lower troposphere, and possessing an upshear vertical tilt. The sensitivities are maximized in a region of enhanced low-level baroclinicity in the vicinity of the surface cyclone’s precursor upper trough. However, differences in the phase and structure of the gradients for the four response functions are evident, which suggests that perturbations could be constructed to alter one response function but not necessarily the others. Gradients of the forecast error response function with respect to the initial conditions are used in an iterative procedure to construct initial condition perturbations that reduce the forecast error. These initial condition perturbations were small in terms of both spatial scale and magnitude. Those initial condition perturbations that were confined primarily to the midtroposphere grew rapidly into much larger amplitude upper-and-lower tropospheric perturbations. The perturbed forecasts were not only characterized by reduced final time forecast error, but also had a synoptic evolution that more closely followed analyses and observations.

Transient elastodynamic analysis with a combination of convolution quadrature method and pseudo-initial condition method

2018 ◽  
Vol 36 (1) ◽  
pp. 334-355
Author(s):  
Yuan Li ◽  
J. Zhang ◽  
Yudong Zhong ◽  
Xiaomin Shu ◽  
Yunqiao Dong
Keyword(s):  
Initial Conditions ◽  
Initial Condition ◽  
Quadrature Method ◽  
Memory Requirement ◽  
Content Type ◽  
Convolution Quadrature ◽  
Force Method ◽  
Cpu Time ◽  
Condition Method ◽  
Convolution Quadrature Method

Purpose The Convolution Quadrature Method (CQM) has been widely applied to solve transient elastodynamic problems because of its stability and generality. However, the CQM suffers from the problems of huge memory requirement in case of direct implementation in time domain or CPU time in case of its reformulation in Laplace domain. The purpose of this paper is to combine the CQM with the pseudo-initial condition method (PICM) to achieve a good balance between memory requirement and CPU time. Design/methodology/approach The combined methods first subdivide the whole analysis into a few sub-analyses, which is dealt with the PICM, namely, the results obtained by previous sub-analysis are used as the initial conditions for the next sub-analysis. In each sub-analysis, the time interval is further discretized into a number of sub-steps and dealt with the CQM. For non-zero initial conditions, the pseudo-force method is used to transform them into equivalent body forces. The boundary face method is employed in the numerical implementation. Three examples are analyzed. Results are compared with analytical solutions or FEM results and the results of reformulated CQM. Findings Results demonstrate that the computation time and the storage requirement can be reduced significantly as compared to the CQM, by using the combined approach. Originality/value The combined methods can be successfully applied to the problems of long-time dynamic response, which requires a large amount of computer memory when CQM is applied, while preserving the CQM stability. If the number of time steps is high, then the accuracy of the proposed approach can be deteriorated because of the pseudo-force method.

scholarly journals Using G-Suite Docs to Improve Students’ Writing Ability at SMA Negeri 1 Batuan, Sumenep

2021 ◽  
Vol 3 (2) ◽  
pp. 1-15
Author(s):  
Norani Yanuar Subandi ◽  
Hablil Warid ◽  
Sulistyaningsih
Keyword(s):  
Action Research ◽  
Data Collection ◽  
Group Work ◽  
Initial Conditions ◽  
Research Data ◽  
Initial Condition ◽  
Writing Ability ◽  
Student Activity ◽  
School Year ◽  
Learning Management

The aim of this research were to describe the implementation of Using G - Suite Docs to Improve Students’ Writing Ability at SMA Negeri 1 Batuan, Sumenep and to find out  the achievement of student’s writing ability in Using G - Suite at SMA Negeri 1 Batuan, Sumenep. The approach used in this research was classroom action research. Data collection tools in this study were observation sheets of learning management through G-Suite Docs media, student activity observation sheets and tests. The objects of this study were 25 students of class XII IPA 1 SMA Negeri 1 Batuan even semester of the 2020/2021 school year. The research showed that the result of implementing of using G-Suite Docs showed that the students were more enthusiastic in writing discussion text and all students could respond to their group work by commenting on the process in writing. Moreover, the students achievement from the initial conditions up to second cycle. The average of initial condition was 66.6 changed to be 79.64 or increased 80% with the result of completeness reaching 92%.   Keywords: G - Suite Docs, Writing ability, Discussion Text

scholarly journals VoIP Speech Encryption System Using Stream Cipher with Chaotic Key Generator

2021 ◽  
pp. 240-248
Author(s):  
Mahmood Khalel Ibrahem ◽  
Hussein Ali Kassim
Keyword(s):  
Stream Cipher ◽  
Chaotic Maps ◽  
Initial Conditions ◽  
Local Network ◽  
Average Delay ◽  
Performance Quality ◽  
Chaotic Cryptography ◽  
Wireless Telecommunication ◽  
Encryption Decryption ◽  
Voice Data

Recently, with the development multimedia technologies and wireless telecommunication, Voice over Internet Protocol, becomes widely used in communication between connecting people, VoIP allows people that are connected to the local network or the Internet to make voice calls using digital connection instead of based on the analog traditional telephone network. The technologies of Internet doesn’t give any security mechanism and there is no way to guarntee that the voice streams will be transmitted over Internet or network have not been intercepted in between. In this paper, VoIP is developed using stream cipher algorithm and the chaotic cryptography for key generator. It is based on the chaotic maps for generating a one-time random key used to encrypt each voice data in the RTP packet. Chaotic maps have been used successfully for encryption bulky data such as voice, image, and video, chaotic cryptography has good properties such as long periodicity, pseudo-randomness, and sensitivity to initial conditions and change in system parameters. A VoIP system was successfully implemented based on the on ITU-T G.729 for voice codec, as a multimedia encoding of Real-time Transport Protocol payload data, then, apply a proposed method to generate three-mixed logistic chaotic maps [1] and then analysis the encryption/ decryption quality measures for speech signal based this method. The experimental work demonstrates that the proposed scheme can provide confidentiality to voice data with voice over IP performance quality, minimum lost in transmitted packet, minimum average delay, and minimum jitter.

Role of initial condition and parametric uncertainty in a severe hailstorm forecast

2021 ◽  
Author(s):  
Patrick Kuntze ◽  
Annette Miltenberger ◽  
Corinna Hoose ◽  
Michael Kunz
Keyword(s):  
Initial Conditions ◽  
Weather Prediction ◽  
Parametric Uncertainty ◽  
Radar Data ◽  
Cloud Microphysics ◽  
Initial Condition ◽  
Relative Contribution ◽  
Cloud Properties ◽  
Set Up ◽  
The Impact

<p>Forecasting high impact weather events is a major challenge for numerical weather prediction. Initial condition uncertainty plays a major role but so potentially do uncertainties arising from the representation of physical processes, e.g. cloud microphysics. In this project, we investigate the impact of these uncertainties for the forecast of cloud properties, precipitation and hail of a selected severe convective storm over South-Eastern Germany.<br>To investigate the joint impact of initial condition and parametric uncertainty a large ensemble including perturbed initial conditions and systematic variations in several cloud microphysical parameters is conducted with the ICON model (at 1 km grid-spacing). The comparison of the baseline, unperturbed simulation to satellite, radiosonde, and radar data shows that the model reproduces the key features of the storm and its evolution. In particular also substantial hail precipitation at the surface is predicted. Here, we will present first results including the simulation set-up, the evaluation of the baseline simulation, and the variability of hail forecasts from the ensemble simulation.<br>In a later stage of the project we aim to assess the relative contribution of the introduced model variations to changes in the microphysical evolution of the storm and to the fore- cast uncertainty in larger-scale meteorological conditions.</p>

Dependence of global monsoon response to volcanic eruptions on the background oceanic states

2021 ◽  
Author(s):  
Meng Zuo ◽  
Tianjun Zhou ◽  
Wenmin Man
Keyword(s):  
Radiative Forcing ◽  
Initial Conditions ◽  
Southern Oscillation ◽  
Volcanic Eruptions ◽  
Initial Condition ◽  
Monsoon Precipitation ◽  
Surface Cooling ◽  
Global Monsoon ◽  
Precipitation Changes ◽  
Sst Anomalies

<p>Both proxy data and climate modeling show divergent responses of global monsoon precipitation to volcanic eruptions. The reason is however unknown. Here, based on analysis of the CESM Last Millennium Ensemble simulation, we show evidences that the divergent responses are dominated by the pre-eruption background oceanic states. We found that under El Niño-Southern Oscillation (ENSO) neutral and warm phases initial conditions, the Pacific favors an El Niño-like anomaly after volcanic eruptions, while La Niña-like SST anomalies tend to occur following eruptions under ENSO cold phase initial condition, especially after southern eruptions. The cold initial condition is associated with stronger upper ocean temperature stratification and shallower thermocline over the eastern Pacific than normal. The easterly anomalies triggered by surface cooling over the tropical South America continent can generate changes in SST through anomalous advection and the ocean subsurface upwelling more efficiently, causing La Niña-like SST anomalies. Whereas under warm initial condition, the easterly anomalies fail to develop and the westerly anomalies still play a dominant role, thus forms an El Niño-like SST anomaly. Such SST response further regulates the monsoon precipitation changes through atmospheric teleconnection. The contribution of direct radiative forcing and indirect SST response to precipitation changes show regional differences, which will further affect the intensity and sign of precipitation response in submonsoon regions. Our results imply that attention should be paid to the background oceanic state when predicting the global monsoon precipitation responses to volcanic eruptions.</p>

FAILURE OF A MEAN-FIELD APPROACH FOR THE MILLER–HUSE PHASE TRANSITION

2000 ◽  
Vol 10 (01) ◽  
pp. 251-256 ◽  
Author(s):  
FRANCISCO SASTRE ◽  
GABRIEL PÉREZ
Keyword(s):  
Phase Transition ◽  
Ising Model ◽  
Chaotic Maps ◽  
Initial Conditions ◽  
Mean Field ◽  
Region Of Interest ◽  
Universality Class ◽  
Two Dimensional ◽  
Field Approach

The diffusively coupled lattice of odd-symmetric chaotic maps introduced by Miller and Huse undergoes a continuous ordering phase transition, belonging to a universality class close but not identical to that of the two-dimensional Ising model. Here we consider a natural mean-field approach for this model, and find that it does not have a well-defined phase transition. We show how this is due to the coexistence of two attractors in its mean-field description, for the region of interest in the coupling. The behavior of the model in this limit then becomes dependent on initial conditions, as can be seen in direct simulations.

scholarly journals Finding symmetries by incorporating initial conditions as side conditions

2008 ◽  
Vol 19 (6) ◽  
pp. 701-715 ◽  
Author(s):  
JOANNA GOARD
Keyword(s):  
Initial Value Problems ◽  
Initial Conditions ◽  
Invariant Solution ◽  
Lie Symmetry ◽  
Initial Condition ◽  
Initial Value ◽  
Side Condition ◽  
Symmetry Generator ◽  
Infinitesimal Symmetry

It is generally believed that in order to solve initial value problems using Lie symmetry methods, the initial condition needs to be left invariant by the infinitesimal symmetry generator that admits the invariant solution. This is not so. In this paper we incorporate the imposed initial value as a side condition to find ‘infinitesimals’ from which solutions satisfying the initial value can be recovered, along with the corresponding symmetry generator.

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