scholarly journals Rotational analysis of ChaCha permutation

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Stefano Barbero ◽  
Emanuele Bellini ◽  
Rusydi H. Makarim
Keyword(s):  
Theoretical Analysis ◽  
Upper Bound ◽  
Stream Cipher ◽  
Random Permutation ◽  
Point Of View ◽  
Rotational Analysis ◽  
Input Size

<p style='text-indent:20px;'>We show that the underlying permutation of ChaCha20 stream cipher does not behave as a random permutation for up to 17 rounds with respect to rotational cryptanalysis. In particular, we derive a lower and an upper bound for the rotational probability through ChaCha quarter round, we show how to extend the bound to a full round and then to the full permutation. The obtained bounds show that the probability to find what we call a parallel rotational collision is, for example, less than <inline-formula><tex-math id="M1">\begin{document}$ 2^{-505} $\end{document}</tex-math></inline-formula> for 17 rounds of ChaCha permutation, while for a random permutation of the same input size, this probability is <inline-formula><tex-math id="M2">\begin{document}$ 2^{-511} $\end{document}</tex-math></inline-formula>. We remark that our distinguisher is not an attack against the ChaCha20 stream cipher, but rather a theoretical analysis of its internal permutation from the point of view of rotational cryptanalysis. Whenever possible, our claims are supported by experiments.</p>

Timber Auctions in the Context of the Modern Auction Theory

2007 ◽  
pp. 86-94
Author(s):  
A. Manakov
Keyword(s):  
Theoretical Analysis ◽  
Auction Theory ◽  
Point Of View ◽  
Theoretical Point ◽  
English Auction ◽  
Analysis And Evaluation

The article provides theoretical analysis and evaluation of the timber auctions reforms in Russia. The author shows that the mechanism of the "combined auctions", which functioned until recently, is more appropriate from the theoretical point of view (and from the point of view of the Russian practice) as compared to the officially approved format of the English auction.

An Alternative Carcass Design to Prevent Flow-Induced Pulsations in Flexibles

2021 ◽  
Author(s):  
N. González Díez ◽  
S. P. C. Belfroid ◽  
T. Iversen Solfeldt ◽  
C. Kristiansen
Keyword(s):  
Pressure Drop ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Steel Strip ◽  
Point Of View ◽  
Theoretical Point ◽  
Adjacent Structures ◽  
Operational Constraints ◽  
Short Time ◽  
Fatigue Failures

Abstract Flow-induced pulsations (FLIP) are pressure oscillations generated inside of flexibles used in dry gas applications that can cause unacceptable vibration levels and eventually failure of equipment. Because of the design of inner layer of the flexibles, the carcass, the frequency of the pulsations is high, potentially leading to fatigue failures of adjacent structures in a relatively short time. The traditional carcass is made of a steel strip formed into an interlocked s-shape in a series of preforming and winding steps. To enable bending of the pipe, gaps are present between each winding with a shape that can cause FLIP. The gaps can be reduced, and the profiles optimized, but they will always be able to generate FLIP at a certain gas velocity. To remove the risk of FLIP in dry gas projects and ensure that operator does not get operational constraints, an alternative carcass design has been developed. This is essentially a conventional agraff carcass but with an additional cover strip to close the gap, making the resulting carcass nearly smooth bore in nature. With a smooth bore this carcass can be used for flexibles which have a risk of FLIP or to produce pipes with a lower internal roughness. This alternative design can be manufactured and can therefore build on the large manufacturing and design experience of the traditional strip carcass. This alternative carcass technology is to undergo a full qualification process, in which the risk of flow induced pulsations is an essential component. With the investigated alternative carcass design, the cavities present in the traditional agraff designs are covered. It is expected that the risk due to the appearance of FLIP is therefore eliminated. Theoretical analysis, numerical simulations and scaled experiments are used to explore the risk for the alternative technology to create FLIP. The theoretical analysis is based on existing knowledge and literature. The numerical simulations and scaled tests are done to generate direct evidence for the end statements resulting from the qualification process. Numerical simulations follow the power balance method presented by the same authors in earlier papers. The same applies to the techniques used for the scaled tests. The main outcome of the qualification presented here are the pressure drop performance and the anti-FLIP capabilities of the design. The new design performs significantly better than the nominal design carcass for the same purpose. The pressure drop coefficients found are close to those expected for a normal, non-corrugated pipe, and thus the recommendation given by the API 17J standard does not apply to this design. The pressure drop coefficient is dependent on the installation direction of the flexible with respect to the flow. No signs of FLIP are found for the nominal design of the investigated carcass technology. This is the case for either installation direction. This is explained from a theoretical point of view, but also numerical and experimental evidence are provided.

scholarly journals State of the art of social representations theory in Asia: An empirical meta-theoretical analysis

2019 ◽  
Vol 13 ◽  
Author(s):  
Annamaria Silvana de Rosa ◽  
Mihaela-Alexandra Gherman
Keyword(s):  
Theoretical Analysis ◽  
State Of The Art ◽  
Multiple Correspondence Analysis ◽  
Social Representations ◽  
Point Of View ◽  
Descriptive Statistics ◽  
Research Trend ◽  
Cultural Backgrounds ◽  
Social Phenomena ◽  
Social Representations Theory

AbstractPart of a larger research project aimed at performing the meta-theoretical analysis of the worldwide literature published on social representations theory (SRT), this article explores the state of art of the theory in the geocultural context of Asia, spatially and temporally, as well as from a conceptual, disciplinary, theoretical, empirical and thematic point of view. The Grid for MetaTheoretical Analysis was used on 194 sources, extracted from the So.Re.Com “A.S. de Rosa”@-library. Multi-step strategies of data analyses offer a diversified picture of findings: (a) descriptive statistics and geomapping with Tableau Desktop the bibliometric impact country by country; (b) structural multidimensional view of significant intersections between “meta-data” performing hierarchical clustering on the top of the multiple correspondence analysis. The three clusters detected reveal a shift from a more generic and applied tradition of research on SRT in 2002–2011 to a more theoretically oriented empirical research trend starting from 2011, identifying the scientific production anchored into different Asian regions (Indonesia, China and Israel) and mainly differentiated by the methodology employed. Results revealed that SRT was adopted due to its epistemological and empirical compatibilities with the purpose of creating an original Asian social psychology, interested in indigenous social phenomena specific to cultural backgrounds.

scholarly journals Visiting Power Laws in Cyber-Physical Networking Systems

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Ming Li ◽  
Wei Zhao
Keyword(s):  
Differential Equations ◽  
Power Law ◽  
Upper Bound ◽  
Large Time ◽  
Power Laws ◽  
Point Of View ◽  
Fundamental Theory ◽  
Physical Systems ◽  
Time Scaling ◽  
Type Data

Cyber-physical networking systems (CPNSs) are made up of various physical systems that are heterogeneous in nature. Therefore, exploring universalities in CPNSs for either data or systems is desired in its fundamental theory. This paper is in the aspect of data, aiming at addressing that power laws may yet be a universality of data in CPNSs. The contributions of this paper are in triple folds. First, we provide a short tutorial about power laws. Then, we address the power laws related to some physical systems. Finally, we discuss that power-law-type data may be governed by stochastically differential equations of fractional order. As a side product, we present the point of view that the upper bound of data flow at large-time scaling and the small one also follows power laws.

Quantum-Behaved Particle Swarm Optimization: Analysis of Individual Particle Behavior and Parameter Selection

2012 ◽  
Vol 20 (3) ◽  
pp. 349-393 ◽  
Author(s):  
Jun Sun ◽  
Wei Fang ◽  
Xiaojun Wu ◽  
Vasile Palade ◽  
Wenbo Xu
Keyword(s):  
Particle Swarm Optimization ◽  
Theoretical Analysis ◽  
Upper Bound ◽  
Optimization Problems ◽  
Empirical Studies ◽  
Particle Swarm ◽  
Performance Comparison ◽  
Stochastic Simulations ◽  
Swarm Optimization ◽  
Bare Bones

Quantum-behaved particle swarm optimization (QPSO), motivated by concepts from quantum mechanics and particle swarm optimization (PSO), is a probabilistic optimization algorithm belonging to the bare-bones PSO family. Although it has been shown to perform well in finding the optimal solutions for many optimization problems, there has so far been little analysis on how it works in detail. This paper presents a comprehensive analysis of the QPSO algorithm. In the theoretical analysis, we analyze the behavior of a single particle in QPSO in terms of probability measure. Since the particle's behavior is influenced by the contraction-expansion (CE) coefficient, which is the most important parameter of the algorithm, the goal of the theoretical analysis is to find out the upper bound of the CE coefficient, within which the value of the CE coefficient selected can guarantee the convergence or boundedness of the particle's position. In the experimental analysis, the theoretical results are first validated by stochastic simulations for the particle's behavior. Then, based on the derived upper bound of the CE coefficient, we perform empirical studies on a suite of well-known benchmark functions to show how to control and select the value of the CE coefficient, in order to obtain generally good algorithmic performance in real world applications. Finally, a further performance comparison between QPSO and other variants of PSO on the benchmarks is made to show the efficiency of the QPSO algorithm with the proposed parameter control and selection methods.

scholarly journals Shifting the Frontiers of Analog and Mixed-Signal Electronics

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Arthur H. M. van Roermund
Keyword(s):  
Channel Capacity ◽  
Upper Bound ◽  
Power Dissipation ◽  
Point Of View ◽  
Mixed Signal ◽  
Analog Signals ◽  
Four Levels ◽  
On Chip ◽  
High Level ◽  
Chip Signal

Nowadays, analog and mixed-signal (AMS) IC designs, mainly found in the frontends of large ICs, are highly dedicated, complex, and costly. They form a bottleneck in the communication with the outside world, determine an upper bound in quality, yield, and flexibility for the IC, and require a significant part of the power dissipation. Operating very close to physical limits, serious boundaries are faced. This paper relates, from a high-level point of view, these boundaries to the Shannon channel capacity and shows how the AMS circuitry forms a matching link in transforming the external analog signals, optimized for the communication medium, to the optimal on-chip signal representation, the digital one, for the IC medium. The signals in the AMS part itself are consequently not optimally matched to the IC medium. To further shift the frontiers of AMS design, a matching-driven design approach is crucial for AMS. Four levels will be addressed: technology-driven, states-driven, redundancy-driven, and nature-driven design. This is done based on an analysis of the various classes of AMS signals and their specific properties, seen from the angle of redundancy. This generic, but abstract way of looking at the design process will be substantiated with many specific examples.

A Theoretical Analysis of Timber Drying in Oscillating Climates

Holzforschung ◽  
2003 ◽  
Vol 57 (4) ◽  
pp. 427-432 ◽  
Author(s):  
J.-G. Salin
Keyword(s):  
Surface Layer ◽  
Theoretical Analysis ◽  
Simulation Model ◽  
Driving Forces ◽  
Point Of View ◽  
Drying Rate ◽  
Drying Time ◽  
Practical Point ◽  
Board Surface ◽  
External Driving

Summary In this study the influence of oscillating climates on the drying of timber is investigated theoretically. First, the effect of oscillations superimposed on an ordinary drying schedule is examined by solving the corresponding partial differential equations. It is shown that the average drying rate is not affected by the oscillations. Second, properly selected oscillation amplitudes and frequencies can result in enhanced mechano-sorptive creep in the board surface layer, which enables increased external driving forces with an unchanged risk of checking. This method is analysed by using a drying simulation model. It is shown that substantial reductions in the drying time can be obtained in theory. From a practical point of view the benefit is probably rather marginal.

scholarly journals BÜCHI COMPLEMENTATION MADE TIGHTER

2006 ◽  
Vol 17 (04) ◽  
pp. 851-867 ◽  
Author(s):  
EHUD FRIEDGUT ◽  
ORNA KUPFERMAN ◽  
MOSHE Y. VARDI
Keyword(s):  
Lower Bound ◽  
Upper Bound ◽  
Blow Up ◽  
Careful Analysis ◽  
Point Of View ◽  
Upper And Lower Bounds ◽  
Theoretical Point ◽  
Infinite Words ◽  
Büchi Automata ◽  
Buchi Automata

The complementation problem for nondeterministic word automata has numerous applications in formal verification. In particular, the language-containment problem, to which many verification problems is reduced, involves complementation. For automata on finite words, which correspond to safety properties, complementation involves determinization. The 2n blow-up that is caused by the subset construction is justified by a tight lower bound. For Büchi automata on infinite words, which are required for the modeling of liveness properties, optimal complementation constructions are quite complicated, as the subset construction is not sufficient. From a theoretical point of view, the problem is considered solved since 1988, when Safra came up with a determinization construction for Büchi automata, leading to a 2O(n log n) complementation construction, and Michel came up with a matching lower bound. A careful analysis, however, of the exact blow-up in Safra's and Michel's bounds reveals an exponential gap in the constants hiding in the O( ) notations: while the upper bound on the number of states in Safra's complementary automaton is n2n, Michel's lower bound involves only an n! blow up, which is roughly (n/e)n. The exponential gap exists also in more recent complementation constructions. In particular, the upper bound on the number of states in the complementation construction of Kupferman and Vardi, which avoids determinization, is (6n)n. This is in contrast with the case of automata on finite words, where the upper and lower bounds coincides. In this work we describe an improved complementation construction for nondeterministic Büchi automata and analyze its complexity. We show that the new construction results in an automaton with at most (0.96n)n states. While this leaves the problem about the exact blow up open, the gap is now exponentially smaller. From a practical point of view, our solution enjoys the simplicity of the construction of Kupferman and Vardi, and results in much smaller automata.

Buried Concentration Profiles for Optical Waveguides by One-Step Electro-Diffusion Process: Theoretical Analysis

1991 ◽  
Vol 228 ◽  
Author(s):  
Xiaoming Li ◽  
Paul F. Johnson
Keyword(s):  
Theoretical Analysis ◽  
Electric Field ◽  
Optical Waveguides ◽  
Diffusion Processes ◽  
Silver Ions ◽  
Point Of View ◽  
Concentration Profiles ◽  
Step Process ◽  
Practical Operation ◽  
One Step

IntroductionIn recent years, a two-step electric field assisted diffusion or ion-exchange technique has been extensively studied for producing buried concentration profiles in glass [1,2,3], polymer [4,5], electrooptic and semiconducting [6,7] substrate materials to fabricate buried optical waveguide devices. The technique contains two separate diffusion processes and is quite complicated, cost and time consuming. In addition, theoretical analysis of the technique is too complicated to be used for calculating and tailoring concentration profiles. Many efforts have been made to pursue a one-step process for producing buried profiles. Very recently, a novel one-step technique [8] involving electric field assisted diffusion of silver ions into glass from molten AgNO3 bath with decaying silver concentration has been developed to produce buried Ag+ concentration profiles in glass substrate. The new technique is, from the practical operation point of view, relatively simple and is a significant improvement over the conventional two-step process.

scholarly journals ASANA IN YOGA – A SPECIFIC FORM OF MOVEMENT TOWARDS AUTONOMY OF HUMAN WILL

2021 ◽  
pp. 196-212
Author(s):  
A. Dobreva
Keyword(s):  
Physical Education ◽  
Theoretical Analysis ◽  
Research Methods ◽  
Scientific Knowledge ◽  
Specific Form ◽  
Point Of View ◽  
Physical Culture ◽  
Theoretical Substantiation ◽  
Independent Element ◽  
Analysis And Synthesis

The aim of the research is to theoretically clarify some of the issues related to the place of Asana in the system of yoga and physical culture in the modern historical stage of formalization of knowledge. This was preceded by research and analysis of ancient resources in yoga, which describes the phenomenon of "Asana"; establishing the place and significance of the Asana in the studied ancient sources; upgrading the term Asana and its explanation from a modern point of view of the achieved degree of formalization of scientific knowledge; theoretical substantiation of the characteristics of Asana as a mandatory component of Yoga by studying its systemic place in the studied sources; pointing out and identifying the general and especially specific characteristics of Asana as a component of yoga, distinguishing it from other means of physical culture, physical education, training and therapy. Research methods include theoretical analysis and synthesis - distinguishing one of the components of yoga, namely: Asana and its study as an independent element and as part of the whole.

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