Search

Aiming at the problems of poor detection effect, high rate of missed detection and high rate of false detection in traditional methods, an anomaly detection method for wireless sensor networks based on improved GM model is proposed. The multilateral measurement method is used to locate the nodes in the wireless sensor network, and the state tracking of the running track of the located nodes is carried out. According to the tracking results, the self similarity between nodes is measured by Hurst index. Based on the measurement results, the improved GM model is used to predict the abnormal nodes. The abnormal values of the wireless sensor network are calculated by the distance between adjacent points, and the state of the current node is judged, this completes the anomaly detection of wireless sensor networks. The experimental results show that the proposed method is effective in anomaly detection of wireless sensor networks, and the rate of missed detection and false detection is low.

Due to their practicality and convenient parametrization, fractals derived from iterated function systems (IFSs) constitute powerful tools widely used to model natural and synthetic shapes. An IFS can generate sets other than fractals, extending its application field. Some of such sets arise from IFS fractals by adding minimal modifications to their defining rule. In this work, we propose two modifications to a fractal recently introduced by the authors: the so-called 2 -ball fractal dust, which consists of a set of balls diminishing in size along an iterative process and delimited by an enclosing square. The proposed modifications are (a) adding a resizer parameter to introduce an interaction between the generator and generated ball elements and (b) a new fractal embedded into the 2 -ball fractal dust, having the characteristic of filling zones not covered by the previous one. We study some numerical properties of both modified resulting sets to gain insights into their general properties. The resulting sets are geometrical forms with potential applications. Notably, the first modification generates an algorithm capable of producing geometric structures similar to those in mandalas and succulent plants; the second modification produces shapes similar to those found in nature, such as bubbles, sponges, and soil. Then, although a direct application of our findings is beyond the scope of this research, we discuss some clues of possible uses and extensions among which we can remark two connections: the first one between the parametrization we propose and the mandala patterns, and the second one between the embedded fractal and the grain size distribution of rocks, which is useful in percolation modeling. [ABSTRACT FROM AUTHOR]

An Active Queue Management (AQM) mechanism, recommended by the Internet Engineering Task Force (IETF), increases the efficiency of network transmission. An example of this type of algorithm can be the Random Early Detection (RED) algorithm. The behavior of the RED algorithm strictly depends on the correct selection of its parameters. This selection may be performed automatically depending on the network conditions. The mechanisms that adjust their parameters to the network conditions are called the adaptive ones. The example can be the Adaptive RED (ARED) mechanism, which adjusts its parameters taking into consideration the traffic intensity. In our paper, we propose to use an additional traffic parameter to adjust the AQM parameters—degree of self-similarity—expressed using the Hurst parameter. In our study, we propose the modifications of the well-known AQM algorithms: ARED and fractional order P I α D β and the algorithms based on neural networks that are used to automatically adjust the AQM parameters using the traffic intensity and its degree of self-similarity. We use the Fluid Flow approximation and the discrete event simulation to evaluate the behavior of queues controlled by the proposed adaptive AQM mechanisms and compare the results with those obtained with their basic counterparts. In our experiments, we analyzed the average queue occupancies and packet delays in the communication node. The obtained results show that considering the degree of self-similarity of network traffic in the process of AQM parameters determination enabled us to decrease the average queue occupancy and the number of rejected packets, as well as to reduce the transmission latency. [ABSTRACT FROM AUTHOR]

Fractals in higher dimensional dynamical systems have significant roles in physics and other applied sciences. In this paper, one of the key property of fractals, called self similarity in product systems, is studied using the concept of similarity boundary. The relationship between similarity boundary of an attractor in a product space to one of its projection spaces is discussed. The impact of inverse invariance of similarity boundary on its coordinate iterated function system is analyzed. Fractals satisfying the strong open set condition , restricted to attractors in product spaces, are characterized. The relationship between similarity boundary of attractors in product spaces and their overlapping sets is also obtained. The equivalency of the restricted open set condition (ROSC) and the strong open set condition in product spaces, is proved. Self similarity of an attractor in a product system is characterized using the Hausdorff measure of its similarity boundary. Also, the Hausdorff dimensions of the overlapping set and similarity boundary of attractors for different types of iterated function systems are obtained. [ABSTRACT FROM AUTHOR]

We present an approach for generic object detection using single query image for finding and locating visually similar objects from target images. The key challenge here is describing an object class using only one query without any training. Our approach is based on computation of Local Self-Similarity descriptors which captures local internal geometric layout within an image and is good representative of object class. We propose to use only predefined landmark points from query image which significantly improves performance of detection. We also present few novel ideas for selection of informative descriptors from the set of all descriptors of the test image to reduce computational expense in feature matching. The algorithm yields Hough-style similarity surface indicating likelihood of presence of the query object at every location. Presence and location of objects are finalized by employing two significance tests followed by non-maxima suppression. We evaluate results of the proposed approach on UIUC car dataset and achieve higher accuracy in comparison with earlier training-free approaches. Results are also analysed on ETHZ shape classes dataset which accounts for large intra-class variations, scale variations, and clutter. Performance of detection on this challenging dataset having diverse contexts demonstrates robustness and efficacy of the algorithm. [ABSTRACT FROM AUTHOR]

We prove finite time blowup of the Burgers--Hilbert equation. We construct smooth initial data with finite H5-norm such that the L∞-norm of the spatial derivative of the solution blows up in finite time. The blowup is an asymptotic self-similar shock at one single point with an explicitly computable blowup profile. The blowup profile is a cusp with Hölder 1/3 continuity. The blowup time and location are described in terms of explicit ODEs. Our proof uses a transformation to modulated self-similar variables which is compatible with the Hilbert transform, the quantitative properties of the stable self-similar solution to the inviscid Burgers equation, an L²-estimate in self-similar variables, and pointwise estimates for the Hilbert transform and for transport equations. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of a weak-jet on the development of a turbulent axisymmetric strong jet. A parametric study is carried out to evaluate simultaneously the effect to the jets-spacing (S/D=3 and S/D=7.5) and their velocity ratios in range 0≤λ≤1. The mixing phenomenon is studied numerically by the finite volume method using the 3D-RANS second-order model, which gives a good agreement with the available data. Three distinct regions of this type of jets interaction are evidenced. This study confirms that the jets spacing affects strongly the converging region and has a minor effect on the combining region. It is found that the weak jet attracts the strong jet and the combining region extends from 30D to 40D where the self-similarity of a single jet is obtained. The jet width decreases when velocity ratio and jets spacing augment. In the combining region, in comparison with the free jet, it is found that the addition of a weak-jet increases the decay rate of the centerline velocity. [ABSTRACT FROM AUTHOR]

In this paper, using the technique of measure of weak noncompactness and by removing the convexity hypothesis, we prove some fixed set results for the sum and the product of three multivalued mappings AB + C, acting on Banach algebras satisfying a certain sequential condition in the weak topology setting. In addition, by using a new definition of the multivalued mapping , we get new fixed set theorems for the mappings of the form under some suitable conditions on the operators A, B, and C in Banach algebras. These hybrid theorems improve some recently obtained results by Ben Amar et al. We also apply these results to the theory of self-similarity. [ABSTRACT FROM AUTHOR]

SAR (species area relationship) is a classic ecological theory that has been extensively investigated and applied in the studies of global biogeography and biodiversity conservation in macro-ecology. It has also found important applications in microbial ecology in recent years thanks to the breakthroughs in metagenomic sequencing technology. Nevertheless, SAR has a serious limitation for practical applications—ignoring the species abundance and treating all species as equally abundant. This study aims to explore the biogeography discoveries of human microbiome over 18 sites of 5 major microbiome habitats, establish the baseline DAR (diversity-area scaling relationship) parameters, and perform comparisons with the classic SAR. The extension from SAR to DAR by adopting the Hill numbers as diversity measures not only overcomes the previously mentioned flaw of SAR but also allows for obtaining a series of important findings on the human microbiome biodiversity and biogeography. Specifically, two types of DAR models were built, the traditional power law (PL) and power law with exponential cutoff (PLEC), using comprehensive datasets from the HMP (human microbiome project). Furthermore, the biogeography "maps" for 18 human microbiome sites using their DAR profiles for assessing and predicting the diversity scaling across individuals, PDO profiles (pair-wise diversity overlap) for measuring diversity overlap (similarity), and MAD profile (for predicting the maximal accrual diversity in a population) were sketched out. The baseline biogeography maps for the healthy human microbiome diversity can offer guidelines for conserving human microbiome diversity and investigating the health implications of the human microbiome diversity and heterogeneity. [ABSTRACT FROM AUTHOR]

Abstract Two and three dimensional large eddy simulations of a spatially developing supersonic mixing layer are performed using an in-house hybrid finite volume code that combines a fourth order non-dissipative MacCormack scheme for capturing turbulence and a second order SLAU2 upwind scheme for capturing shocks and other discontinuities in the flow. Three-dimensional predictions of growth rate and statistical moments in the self similar regime are consistent with past experimental and direct numerical simulation studies. The peak values of the transverse turbulence stresses are over predicted in two dimensional simulations. This may be attributed to the lack of vortex stretching and the lack of significant energy transfer to the smaller scales. This also leads to sustenance, pairing and overall growth of large coherent structures that result in an over-prediction of growth rate by about 20%. [ABSTRACT FROM AUTHOR]

Let a data set Δ = { ( t i , y i ) ∈ R × Y : i = 0 , 1 , ⋯ , N } be given, where t 0 < t 1 < t 2 < ⋯ < t N and Y is a complete metric space. In this article, fractal interpolation functions (FIFs) on I = [ t 0 , t N ] corresponding to the set Δ are constructed by mappings W 1 , ⋯ , W N . Each W k is of the form W k = ( L k , M k ) , where L k : J k → I k is a homeomorphism and M k : J k × Y → Y is continuous. Here I k = [ t k − 1 , t k ] and J k = [ t j ( k ) , t l ( k ) ] , j ( k ) , l ( k ) ∈ { 0 , 1 , ⋯ , N } , are subintervals of I which depend on k . In this construction, the length of J k is not assumed to be larger than the length of I k , and each L k is not supposed to be a contraction. A FIF established by this method has a property of self similarity between its graph on J k and on I k . In this paper we give a construction of FIFs with locally self similar graphs. The stability and sensitivity of FIFs established in this way are also discussed. [ABSTRACT FROM AUTHOR]

The complete cartwheel tiling is a well known Penrose tiling without exact pentagonal symmetry, but with an approximate decagonal symmetry far away from the center. We show in this paper that this tiling is not obtained by the 'cut and project' method of de Bruijn (Indag Math 43:39-66, 1981) though it is a limit of such projections. [ABSTRACT FROM AUTHOR]

Double roll crushers (DRC) have the highest throughputs among primary crushers. In the oil sands, the hourly capacity may exceed 14,000 t/h. They are preferably used to comminute medium-hard rock or sticky materials. An unusual tough particle or unbreakable object may effect substantial dynamic forces in a DRC. Considering the large amount of energy stored in the flywheels and the fact that the mass of the floating rolls of the largest machines exceeds 60 t, any unexpected dynamic behavior can be an issue for a safe and reliable operation. Research is conducted on a small industrial scale smooth DRC at the Institute of Mineral Processing Machines. Results of the crushing force dynamics under extreme conditions, as well as the related product particle size distribution and the influence of the mineral structure of a variety of rocks on the nipping behavior are presented. [ABSTRACT FROM AUTHOR]

The 'driving force' per unit area on the boundary of a spherical self-similarly expanding Eshelby inclusion with general eigenstrain $$\epsilon ^*_{ij}$$ is obtained. It is independent of r and t, and depends only on the wave speeds a and b, and the expansion velocity $$\upsilon $$ . It is, thus, the same at the initial time $$t =0$$ when the expansion starts from the zero dimension. [ABSTRACT FROM AUTHOR]

Option overlays on a rebalanced portfolio are designed. Inputs to the design problem are the physical and risk neutral probabilities at the option maturity. They are estimated from time series and option data, respectively. The objective for the design is the bid price of a two price economy modelled as a distorted expectation. The design is monotone increasing in the underlier with a delta constraint. The option positioning is implemented on the S&P 500 index, supposedly rebalanced every 21 days with option positions taken 10 days prior to a rebalance date with a maturity near two months. Option overlays are seen to raise performance measures and reduce drawdowns. [ABSTRACT FROM AUTHOR]

Animal movement is often modelled on an individual level using simulated random walks. In such applications it is preferable that the properties of these random walks remain consistent when the choice of time is changed (time scale invariance). While this property is well understood in unbounded space, it has not been studied in detail for random walks in a confined domain. In this work we undertake an investigation of time scale invariance of the drift and diffusion rates of Brownian random walks subject to one of four simple boundary conditions. We find that time scale invariance is lost when the boundary condition is non-conservative, that is when movement (or individuals) is discarded due to boundary encounters. Where possible analytical results are used to describe the limits of the time scaling process, numerical results are then used to characterise the intermediate behaviour. [ABSTRACT FROM AUTHOR]

Fractals are defined as geometric shapes that exhibit symmetry of scale. This simply implies that fractal is a shape that it would still look the same even if somebody could zoom in on one of its parts an infinite number of times. This property is also called self-similarity with several applications including nano-pharmacology and drug nanocarriers. We are interested in the study of the properties of fractal aggregates in a microgravity environment above an orbiting spacecraft. To model the effect we use a complete expression for the gravitational acceleration. In particular on the surface of the Earth the acceleration is corrected for the effect of oblateness and rotation. In the gravitational acceleration the effect of oblateness can be modeled with the inclusion of a term that contains the J harmonic coefficient, as well as a term that depends on the square of angular velocity of the Earth. In orbit the acceleration of gravity at the point of the spacecraft is a function of the orbital elements and includes only in our case the J harmonic since no Coriolis force is felt by the spacecraft. Using the fitting parameter d = 3.0 we have found that the aggregate monomer number N is not significantly affected and exhibits a minute 0.0001 % difference between the geocentric and areocentric latitudes of 90° and 0°. Finally for circular and elliptical orbits around Earth and Mars of various inclinations and eccentricities the aggregate monomer number it's not affected at all at the orbital altitude of 300 km. [ABSTRACT FROM AUTHOR]

Highlights: [•] Many physiological systems can be modeled as fractal processes. [•] We investigated various approaches for estimation of spectral behavior. [•] The averaged wavelet coefficient method yielded the most accurate results. [ABSTRACT FROM AUTHOR]

We construct a process with inverse gamma increments and an asymptotically self-similar limit. This construction supports the use of long-range-dependent t subordinator models for actual financial data as advocated in Heyde and Leonenko (2005), in that it allows for noninteger-valued model parameters, as is found empirically in model estimation from data. [ABSTRACT FROM AUTHOR]

A study was conducted at Msekera Regional Agricultural Research Station in eastern Zambia to (1) describe canopy branching properties of Acacia angustissima, Gliricidia sepium and Leucaena collinsii in short rotation forests, (2) test the existence of self similarity from repeated iteration of a structural unit in tree canopies, (3) examined intra-specific relationships between functional branching characteristics, and (4) determine whether allometric equations for relating aboveground tree biomass to fractal properties could accurately predict aboveground biomass. Measurements of basal diameter (D) at 10cm aboveground and total height (H), and aboveground biomass of 27 trees were taken, but only nine trees representative of variability of the stand and the three species were processed for functional branching analyses (FBA) of the shoot systems. For each species, fractal properties of three trees, including fractal dimension (D), bifurcation ratios ( p) and proportionality ratios ( q) of branching points were assessed. The slope of the linear regression of p on proximal diameter was not significantly different (P < 0.01) from zero and hence the assumption that p is independent of scale, a pre-requisite for use of fractal branching rules to describe a fractal tree canopy, was fulfilled at branching orders with link diameters >1.5 cm. The proportionality ration q for branching patterns of all tree species was constant at all scales. The proportion of q values >0.9 (f) was 0.8 for all species. Mean fractal dimension (D) values (1.5-1.7) for all species showed that branching patterns had an increasing magnitude of intricacy. Since D values were ≥1.5, branching patterns within species were self similar. Basal diameter (D), proximal diameter and D described most of variations in aboveground biomass, suggesting that allometric equations for relating aboveground tree biomass to fractal properties could accurately predict aboveground biomass. Thus, assessed Acacia, Gliricidia and Leucaena trees were fractals and their branching properties could be used to describe variability in size and aboveground biomass. [ABSTRACT FROM AUTHOR]

In this article, we will give a method of reconstruction of a random walk in the ring of p-adic integers. Paying attention to a structural importance in the self similarity, we will perform the construction by means of modified method for constructing canonical stochastic processes on fractals in the Euclidean space. As a result, we will obtain an important subfamily of Albeverio and Karwowski's stochastic processes with a self-similar randomness. [ABSTRACT FROM AUTHOR]

Abstract: Applying a limiter function with respect to the ratio of the volumes of colliding particles to the coagulation kernel a new family of kernels arises. The behavior of the solutions of the coagulation equation for the simplest member of this family (the so-called Π-kernel), is examined in the present work using several mathematical tools. It is shown that even this kernel exhibits zero order homogeneity, self-similar solutions of the coagulation equation do not exist. Surprisingly enough, even a slight change to the constant coagulation kernel induces a fundamental change to the nature of the coagulation equation solution. [ABSTRACT FROM AUTHOR]

A recently developed remote-sensing instrument acquires high-quality digital photographs in shallow-marine settings within water depths of 15 m. The technology, known as the Along-Track Reef-Imaging System, provides remarkably clear, georeferenced imagery that allows visual interpretation of benthic class (substrates, organisms) for mapping coral reef habitats, as intended. Unforeseen, however, are functions new to the initial technologic purpose: interpretable evidence for real-time biogeologic processes and for perception of scaled-up skeletal self-similarity of scleractinian microstructure. Florida reef sea trials lacked the grid structure required to map contiguous habitat and submarine topography. Thus, only general observations could be made relative to times and sites of imagery. Degradation of corals was nearly universal; absence of reef fish was profound. However, ∼1% of more than 23,600 sea-trial images examined provided visual evidence for local environs and processes. Clarity in many images was so exceptional that small tracks left by organisms traversing fine-grained carbonate sand were visible. Other images revealed a compelling sense, not yet fully understood, of the microscopic wall structure characteristic of scleractinian corals. Conclusions drawn from classifiable images are that demersal marine animals, where imaged, are oblivious to the equipment and that the technology has strong capabilities beyond mapping habitat. Imagery acquired along predetermined transects that cross a variety of geomorphic features within depth limits will (1) facilitate construction of accurate contour maps of habitat and bathymetry without need for ground-truthing, (2) contain a strong geologic component of interpreted real-time processes as they relate to imaged topography and regional geomorphology, and (3) allow cost-effective monitoring of regional- and local-scale changes in an ecosystem by use of existing-image global-positioning system coordinates to re-image areas. Details revealed in the modern setting have taphonomic implications for what is often found in the geologic record. [ABSTRACT FROM AUTHOR]

Copyright of Ciencia, Docencia y Technologia is the property of Universidad Nacional de Entre Rios and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: A number of interesting and potentially useful regularities have been observed in high pressure batch filtration of fine and colloidal suspensions carried out to equilibrium under a wide variety of physical and chemical process conditions. Two such regularities are described here. The first regular behavior, demonstrated by a large number of colloidal suspensions, can be represented by the Pareto profile, which relates filtration rate with solid content of filter cake at equilibrium. The profile is found to be a strong function of material fineness but is seemingly independent of physical and chemical process conditions. Since it can be treated as a constrained performance benchmark for the filtration of a suspension, it is germane for evaluating the filtration process in terms of two of its more important process measures, namely, kinetics and maximum extent of dewatering that is achievable. The Pareto regularity reflects the fact that in general it is not feasible to improve both measures simultaneously in a batch filtration which is driven to equilibrium, and any process modification may improve one measure but invariably at the expense of the other. The second regular behavior, namely, self-similarity in pressure filtration is demonstrated for filtration of wide variety of varying materials and process conditions. Simple transformation and scaling of slurry filtration data with critical solid volume fraction and critical time at the transition from cake formation stage to cake consolidation stage translate the filtration curves into a form which are remarkably self-similar. This self-preserving behavior is demonstrated for a wide variety of experimental data under varying physical and chemical process conditions for different colloidal systems. Some implications of the regularities are discussed. [Copyright &y& Elsevier]

The proportionality factor (p) is a parameter used for fractal root system modelling. It describes tapering along root axes and is calculated by the ratio of total cross sectional area (CSA) before and after branching. The exact point where the area of the parent branch is measured is often not defined. By measurement of the CSA adjacent to a branching point tapering without branching is not included in factor p. In this study p was measured on six tropical tree species (Clethra revoluta, Graffenrieda emarginata, Vismia tomentosa, Weinmannia loxensis, Clusia sp. and Styrax foveolaria). The measurement was conducted in three different ways, quantifying (i) tapering of roots by branching (p branch), (ii) tapering without branching (p within), and (iii) total root tapering (p total). For five species p total was significantly higher than p branch (p <0.05). For three species p within contributed significantly more to p total than p branch. There was only a weak correlation between p and root segment diameter. The slope of the regression line was often higher for p within than for p branch. The results suggest that the exclusive use of p branch in fractal branching models leads to an underestimation of total root system tapering and to an overestimation of total root system biomass and root length in fractal branching models. Furthermore in some species self-similarity decreases when tapering without branching is included in the proportionality factor p. This may imply that models should allow p to change with increasing diameter. [Copyright &y& Elsevier]