Distance Ranking Research Articles

Adaptive Indexed Divisible Load Theory for Wireless Sensor Network Workload Allocation

Energy depletion in wireless sensors is a major obstacle for a wireless sensor network (WSN) to operate over an extended period of time. This problem can be extenuated by minimizing the need for high-power transmission from sensors to the master processor. Sensors could be arranged in clusters, and their sensing workloads are properly determined for minimal energy consumption during the sensing and result reporting stages. The divisible load theory (DLT) is applied here to obtain optimal allocation of sensor workloads taking into account the balance of energy used such that the failure of the first sensor can be delayed. Since standard DLT assumes an ordered indexing of the sensors, its direct application in WSNs may result in unbalanced energy usage. Adaptive indexing schemes with the application of DLT, adaptive indexed divisible load theory (AIDLT), are thus proposed to redefine the indices of sensors in each sensing round while calculating the assigned workload portions. Furthermore, adaptations based on transmission distances, sensor residual energies, double ranking of distances with residual energies, and randomized sensor identifications are formulated and evaluated. Simulation results on a cluster of sensors have shown that adaptation based on residual energies outperforms the other indexing schemes while the randomization scheme is the simplest.

A Novel Lightness Localization Algorithm Based on Anchor Nodes Equilateral Triangle Layout in WSNs

Localization, which determines the geographical locations of sensors, is a crucial issue in wireless sensor networks. In this paper, we propose a novel lightweight equilateral triangle localization algorithm (LETLA) that accurately localizes sensors and minimizes the power consumption. In the LETLA, the approximate coordinates substituted for the real coordinates of the unknown node, and the corresponding optimization problem is formulated to minimize the estimation error. With the sequences that represent the ranking of distances from the anchors to the unknown node, a simple and robust technique is developed to quickly and efficiently estimate a region containing the approximate coordinates, and a condition under which the approximate error can be minimized is given. This condition employs a new geometric construct of anchor layout called equilateral triangle diagrams. Extensive simulations show that the LETLA performs better than other state-of-the-art approaches in terms of energy consumption with the same localization precision.

Optimal rank-based tests for block exogeneity in vector autoregressions

The aim of this paper is to construct a class of locally asymptotically most stringent (in the Le Cam sense) tests for independence between two sets of variables in the V AR models. These tests are based on multivariate ranks of distances and multivariate signs of the observations and are shown to be asymptotically distribution-free under very mild assumptions on the noise, which is obtained by applying a linear transformation to marginally spherical innovations. The class of tests derived is invariant with respect to the group of block affine transformations and asymptotically invariant with respect to the group of continuous monotone marginal radial transformations.

A consistent multivariate test of association based on ranks of distances

We are concerned with the detection of associations between random vectors of any dimension. Few tests of independence exist that are consistent against all dependent alternatives. We propose a powerful test that is applicable in all dimensions and is consistent against all alternatives. The test has a simple form and is easy to implement. We demonstrate its good power properties in simulations and on examples.

Role of Ranking Algorithms for Information Retrieval

As the use of web is increasing more day by day, the web users get easily lost in the web's rich hyper structure. The main aim of the owner of the website is to give the relevant information according their needs to the users. We explained the Web mining is used to categorize users and pages by analyzing user's behavior, the content of pages and then describe Web Structure mining. This paper includes different Page Ranking algorithms and compares those algorithms used for Information Retrieval. Different Page Rank based algorithms like Page Rank (PR), WPR (Weighted Page Rank), HITS (Hyperlink Induced Topic Selection), Distance Rank and EigenRumor algorithms are discussed and compared. Simulation Interface has been designed for PageRank algorithm and Weighted PageRank algorithm but PageRank is the only ranking algorithm on which Google search engine works.

A multi-objective particle swarm optimizer with distance ranking and its applications to air compressor design optimization

Multi-objective particle swarm optimization (MOPSO) has been steadily gaining attention from the research community because of its high convergence speed. On the other hand, in the face of increasing complexity and dimensionality of today’s application coupled with its tendency towards premature convergence related to the high convergence speeds, it is necessary to improve the global convergence and uniform distribution of MOPSO. A novel crowding distance ranking-based particle swarm optimizer is proposed (DMOPSO). With the elitism strategy, the evolution of the external swarm is achieved based on particles’ crowding distance ranking by descending order, to delete the repetitive ones in the crowded area. The update of the global optimum is performed by selecting a particle with relatively bigger crowding distance, to lead the swarm evolving to the disperse region. A small ratio mutation is also introduced to the inner swarm to enhance the global searching capacity of the algorithm. So the number of Pareto optimal solutions can be controlled, and the convergence and diversity of Pareto optimal set can also be guaranteed. The experiment on the optimization of single-stage air compressor showed that DMOPSO handled problems with two and three objectives efficiently, and outperformed the comparison algorithms in terms of the convergence and diversity of the Pareto front. The robustness was illustrated through sensitivity analysis for key parameters.

La dispersión geográfica de las redes personales: cálculo y significado

This article compares three indices that represent the geographical dispersion of personal networks. The first index is built on the computation of distances for each Ego with their Alters and among each one them. After calculating the total distance, it is obtained the average for each Ego. The absolute value of the logarithm of this average is the proposed measure. The second index is constructed taking into account only the relations Ego-Alter of the above formula and the third, common in such studies, shows the distribution of active contacts in a ranking of distances (same neighbourhood, same city, Catalonia, rest of Spain, other countries). The comparison is made exploring the effect of the three indexes on the exchanged social support of people living in Catalonia. The data are taken from the survey of

Soil properties prediction of western Mediterranean islands with similar climatic environments by means of mid‐infrared diffuse reflectance spectroscopy

This study investigated the suitability of mid‐infrared diffuse reflectance Fourier transform (MIR‐DRIFT) spectroscopy, with partial least squares (PLS) regression, for the determination of variations in soil properties typical of Italian Mediterranean off‐shore environments. Pianosa, Elba and Sardinia are typical of islands from this environment, but developed on different geological substrates. Principal components analysis (PCA) showed that spectra could be grouped according to the soil composition of the islands. PLS full cross‐validation of soil property predictions was assessed by the coefficient of determination (R2), the root mean square error of cross‐validation and prediction (RMSECV and RMSEP), the standard error (SECV for cross‐validation and SEP for prediction), and the residual predictive deviation (RPD). Although full cross‐validation appeared to be the most accurate (R2 = 0.95 for organic carbon (OC), 0.96 for inorganic carbon (IC), 0.87 for CEC, 0.72 for pH and 0.74 for clay; RPD = 4.4, 6.0, 2.7, 1.9 and 2.0, respectively), the prediction errors were considered to be optimistic and so alternative calibrations considered to be more similar to ‘true’ predictions were tested. Predictions using individual calibrations from each island were the least efficient, while predictions using calibration selection based on a Euclidian distance ranking method, using as few as 10 samples selected from each island, were almost as accurate as full cross‐validation for OC and IC (R2 = 0.93 for OC and 0.96 for IC; RPD = 3.9 and 4.7, respectively). Prediction accuracy for CEC, pH and clay was less accurate than expected, especially for clay (R2 = 0.73 for CEC, 0.50 for pH and 0.41 for clay; RPD = 1.8, 1.5 and 1.4, respectively). This study confirmed that the DRIFT PLS method was suitable for characterizing important properties for soils typical of islands in a Mediterranean environment and capable of discriminating between the variations in soil properties from different parent materials.

Reliable detection of directional couplings using rank statistics

To detect directional couplings from time series various measures based on distances in reconstructed state spaces were introduced. These measures can, however, be biased by asymmetries in the dynamics' structure, noise color, or noise level, which are ubiquitous in experimental signals. Using theoretical reasoning and results from model systems we identify the various sources of bias and show that most of them can be eliminated by an appropriate normalization. We furthermore diminish the remaining biases by introducing a measure based on ranks of distances. This rank-based measure outperforms existing distance-based measures concerning both sensitivity and specificity for directional couplings. Therefore, our findings are relevant for a reliable detection of directional couplings from experimental signals.

The isolation game: A game of distances

We introduce a new multi-player geometric game, which we will refer to as the isolation game, and study its Nash equilibria and best or better response dynamics. The isolation game is inspired by the Voronoi game, competitive facility location, and geometric sampling. In the Voronoi game studied by Dürr and Thang, each player’s objective is to maximize the area of her Voronoi region. In contrast, in the isolation game, each player’s objective is to position herself as far away from other players as possible in a bounded space. Even though this game has a simple definition, we show that its game-theoretic behaviors are quite rich and complex. We consider various measures of farness from one player to a group of players and analyze their impacts to the existence of Nash equilibria and to the convergence of the best or better response dynamics: We prove that it is NP-hard to decide whether a Nash equilibrium exists, using either a very simple farness measure in an asymmetric space or a slightly more sophisticated farness measure in a symmetric space. Complementing these hardness results, we establish existence theorems for several special families of farness measures in symmetric spaces: We prove that, for isolation games where each player wants to maximize her distance to her m th nearest neighbor, for any m , equilibria always exist. Moreover, there is always a better response sequence starting from any configuration that leads to a Nash equilibrium. We show that when m = 1 the game is a potential game, no better response sequence has a cycle, but when m > 1 the games are not potential. More generally, we study farness functions that give different weights to a player’s distances to others based on the distance rankings, and obtain both existence and hardness results when the weights are monotonically increasing or decreasing. Finally, we present results on the hardness of computing best responses when the space has a compact representation as a hypercube.

Quality assessment of dimensionality reduction: Rank-based criteria

Dimensionality reduction aims at providing low-dimensional representations of high-dimensional data sets. Many new nonlinear methods have been proposed for the last years, yet the question of their assessment and comparison remains open. This paper first reviews some of the existing quality measures that are based on distance ranking and K -ary neighborhoods. Next, the definition of the co-ranking matrix provides a tool for comparing the ranks in the initial data set and some low-dimensional embedding. Rank errors and concepts such as neighborhood intrusions and extrusions can then be associated with different blocks of the co-ranking matrix. Several quality criteria can be cast within this unifying framework; they are shown to involve one or several of these characteristic blocks. Following this line, simple criteria are proposed, which quantify two aspects of the embedding quality, namely its overall quality and its tendency to favor intrusions or extrusions. They are applied to several recent dimensionality reduction methods in two experiments, with both artificial and real data.

Automatic calibration of a rainfall–runoff model using a fast and elitist multi-objective particle swarm algorithm

In order to successfully calibrate a numerical model, multiple criteria should be considered. Multi-objective genetic algorithms (MOGAs) have proved effective in numerous such applications, where most of the techniques relying on the condition of Pareto efficiency to compare different solutions. In this paper, a new non-dominated sorting particle swarm optimisation (NSPSO), is proposed, that combines the operations (fast ranking of non-dominated solutions, crowding distance ranking and elitist strategy of combining parent population and offspring population together) of a known MOGA NSGA-II and the other advanced operations (selection and mutation operations) with a single particle swarm optimisation (PSO). The efficacy of this algorithm is demonstrated on the calibration of a rainfall–runoff model, and the comparison is made with the NSGA-II. The simulation results suggest that the proposed optimisation framework is able to achieve good solutions as well diversity compared to the NSGA-II optimisation framework.

Some problems and solutions in density estimation from bearing tree data: a review and synthesis

AbstractAim I detail several problems and solutions related to estimating pre‐settlement forest density from land surveyors’ bearing tree data. The data have a high value, so clarification of existing problems is needed in the development of a better theoretical framework in which to treat them. I focus on absolute density because it is the foundation for several other variables, e.g. basal area, timber volume and carbon content.Location The issues raised are relevant to the vast area encompassed by rectangular land surveys, including the General Land Office survey area of the United States (roughly, Ohio and Florida to the Pacific coast and Alaska), as well as significant areas in the eastern United States, and possibly elsewhere.Methods A literature review details the history and nature of density estimation from bearing tree data, and spatial simulations quantify the effects of certain identified problems on density estimates. The review focuses on methodological issues appearing in the ecological and biometrical literature.Results Problems encountered in the literature and addressed here include: (1) aggregated tree spatial patterns and their effect on density using traditional estimators; (2) the mis‐designation of bearing tree labels in relation to definitions given in the estimators; (3) biases due to small sample size; and (4) surveyor‐induced biases. Simulations of aggregated tree populations having a 44‐fold density variation show that estimates ranging from 5 to 127 per cent of actual can result, depending on the estimator used, the scale at which it is calculated, and the error in tree distance rank assignments. The traditionally used estimator is accurate only when trees are spatially random throughout, and sample size is not small. More robust estimators exist that can accommodate a wider range of variation in spatial pattern, sampling design and sample size. One of these is discussed in detail.Main conclusions Data users should pay much closer attention to critical aspects of bearing tree data and analytical methods, provide basic but necessary descriptive data, and more accurately represent the inherent range of possible errors of estimate. They can narrow this range of uncertainty by using the methods and considerations discussed here and in other recent work.

Cardiac activity in dairy goats whilst feeding side-by-side at two different distances and during social separation

When loose-housed dairy goats feed in close proximity to each other, frequent social conflicts are often reported. The aim of this study was to investigate whether the cardiac activity of dairy goats is affected when they are obliged to feed side-by-side in close proximity. In five dyads of goats each stemming from eight groups (8 × 5 dyads) differing in terms of grouping age and presence of horns, heart rate (HR) and root mean square of successive beat-to-beat differences (RMSSD) as a parameter of heart-rate variability were measured in two experimental situations differing in distance during feeding. Dyads were allowed to feed for 5 min at two hayracks set-up side-by-side at a “far” or a “near” distance. Before goats were exposed to these test situations, baseline values of cardiac activity were measured. The differences of the baseline and test values (Δ) for HR and RMSSD were used for statistical analysis with linear mixed-effects models with crossed random effects. They were tested for dependence on feeding distance, rank within the group, dyadic rank relationship, grouping age, and presence of horns. In addition, cardiac activity was measured in a social-separation experiment conducted with the same goats. Baseline cardiac activity depended on the goat's rank within the group, with higher/lower levels of RMSSD/HR found in high-ranking than in low-ranking goats. In the feeding experiment, a significant interaction (feeding distance⁎rank within group, p = 0.01) was found for Δ RMSSD: Low-ranking goats had lower Δ values at the far than at the near feeding distance. By contrast, high-ranking goats had lower Δ values at the near than at the far distance. In the separation experiment, Δ HR increased significantly compared to the feeding experiment ( p < 0.05), whereas Δ RMSSD did not differ significantly. Our results show that cardiac response is context-specific in dairy goats (feeding vs. separation), and that the individual's rank within the group must be taken into account in any future studies of their cardiac activity.

Tests of Bivariate Exchangeability

Summary We discuss the hypothesis of bivariate exchangeability and show that testing bivariate exchangeability is related to the two‐sample testing of equality of distribution functions. We consider three test statistics based on the ordering of the Euclidean interpoint distances. The runs test of exchangeability counts the runs among the observations and their mirror images on the minimal spanning tree. The nearest neighbour test of exchangeability is based on the number of nearest neighbour type coincidences among the observations and their folded images on the plane. The rank test of exchangeability compares the within and between ranks of the interpoint distances. We also consider the sign test of exchangeability, which uses the signs of the observations in specific regions, and a bootstrap test of exchangeability based on the maximum distance between the mirror images. We compare the power of these methods in a Monte Carlo study which shows different power orderings of the methods, depending on the alternative hypothesis.

Multi-objective optimisation of batch separation processes

This paper considers for the first time the simultaneous multi-objective optimisation of design and operation of batch distillation as well as of batch hybrid distillation/pervaporation processes. The overall problem is formulated as a multi-objective mixed integer dynamic optimisation (MO-MIDO) problem. The optimisation strategy comprises of different ranking procedures that allow the determination of the Pareto optimal set. A case study for the separation of a homogeneous tangent-pinch (acetone–water) mixture is presented for a dual-criteria optimisation case of minimising capital investment while at the same time minimising the energy consumption rate during the batch. It is found that the proposed distance ranking procedure yields the best Pareto optimal set when compared to other non-dominated sorting procedures. Furthermore, the distance ranking procedure was found to be further improved when used with an elitism operator.

Sequence-Based Localization in Wireless Sensor Networks

We introduce a novel sequence-based localization technique for wireless sensor networks. We show that the localization space can be divided into distinct regions that can each be uniquely identified by sequences that represent the ranking of distances from the reference nodes to that region. For <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> reference nodes in the localization space, combinatorially, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</i> ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> ") sequences are possible, but we show that, due to geometric constraints, the actual number of feasible location sequences is much lower: only <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</i> ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> ). Using these location sequences, we develop a localization technique that is robust to random errors due to the multipath and shadowing effects of wireless channels. Through extensive systematic simulations and a representative set of real mote experiments, we show that our lightweight localization technique provides comparable or better accuracy than other state-of-the-art radio signal strength-based localization techniques over a range of wireless channel and node deployment conditions.

Distance‐Ranked Connectivity Compression of Triangle Meshes

Abstract We present a new, single‐rate method for compressing the connectivity information of a connected 2‐manifold triangle mesh with or without boundary. Traditional compression schemes interleave geometry and connectivity coding, and are thus typically unable to utilize information from vertices (mesh regions) they have not yet processed. With the advent of competitive point cloud compression schemes, it has become feasible to develop separate connectivity encoding schemes that can exploit complete, global vertex position information to improve performance. Our scheme demonstrates the utility of this separation of vertex and connectivity coding. By traversing the mesh edges in a consistent fashion, and using global vertex information, we can predict the position of the vertex that completes the unprocessed triangle attached to a given edge. We then rank the vertices in the neighborhood of this predicted position by their Euclidean distance. The distance rank of the correct closing vertex is stored. Typically, these rank values are small, and the set of rank values thus possesses low entropy and compresses very well. The sequence of rank values is all that is required to represent the mesh connectivity—no special split or merge codes are necessary. Results indicate improvements over traditional valence‐based schemes for more regular triangulations. Highly irregular triangulations or those containing a large number of slivers are not well modelled by our current set of predictors and may yield poorer connectivity compression rates than those provided by the best valence‐based schemes.

Codes over Galois rings with respect to the Rosenbloom–Tsfasman metric

We investigate the structure of codes over Galois rings with respect to the Rosenbloom–Tsfasman (shortly RT) metric. We define a standard form generator matrix and show how we can determine the minimum distance of a code by taking advantage of its standard form. We compute the RT-weights of a linear code given with a generator matrix in standard form. We define maximum distance rank (shortly MDR) codes with respect to this metric and give the weights of the codewords of an MDR code. Finally, we give a decoding technique for codes over Galois rings with respect to the RT metric.

Linear Codes over $\mathbb{F}_{q}[u]/(u^s)$ with Respect to the Rosenbloom–Tsfasman Metric

We investigate the structure of codes over $\mathbb{F}_q[u]/(u^s)$ rings with respect to the Rosenbloom-Tsfasman (RT) metric. We define a standard form generator matrix and show how we can determine the minimum distance of a code by taking advantage of its standard form. We define MDR (maximum distance rank) codes with respect to this metric and give the weights of the codewords of an MDR code. We explore the structure of cyclic codes over $\mathbb{F}_q[u]/(u^s)$ and show that all cyclic codes over $\mathbb{F}_q[u]/(u^s)$ rings are MDR. We propose a decoding algorithm for linear codes over these rings with respect to the RT metric.