Real Distributions Research Articles

Tail Parameters of Stable Distributions Using One Million Observations of Real Estate Returns from Five Continents

This study focuses on global real estate return distributions. For our analysis, we employ the class of stable distributions that has become prominent in the real estate literature. We add to the literature by undertaking a global-scale analysis for the first time. By using data since the early 1990s, we show that there is considerable variation in the tail weights of return distributions, both between countries as well as among sectors within the countries. It is important to note that the tail parameters vary over time as well. Our results strengthen the recently discovered notion about non-constant tail parameters in stable distributions, which contradicts earlier findings about constant tail parameters. Additionally, we argue that merely changes over time were to be discovered, rather than pure methodological facts driving the variation, which is in contrast to the initial assumption associated with constant tail parameters. Our results provide an extensive overview of the tailedness of global real estate markets and offer a comprehensive insight into differing market distributions.

Mathematical modeling of the heating of a fast ignition target by an ion beam

We develop a BIN computer code for simulating the interaction of a monochromatic ion beam with a plasma, which takes into account changes in the spatial distribution of the heated-plasma temperature. This enables us to calculate the heating of both homogeneous and inhomogeneous plasmas with parameters corresponding to their real spatial distributions at the time of maximum compression of the inertial confinement fusion (ICF) target. We present the results of a numerical simulation using the BIN code for the heating of a homogeneous deuterium–tritium plasma by a short pulse of monochromatic ions at various ion velocity and plasma–electron thermal velocity ratios. We also present the results of calculations for the heating of an inhomogeneous plasma of a non-cryogenic target formed as a beryllium deuteride–tritide shell by beams of light, medium, and heavy ions. As the initial distributions, we use the results of numerical simulations for such a target, precompressed by a laser pulse (carried out at the M. V. Keldysh Institute of Applied Mathematics using the DIANA code). We demonstrate the possibility of forming the central ignitor with the parameters sufficient for igniting the targets by beams of ions with energies E ~ 100 − 400 MeV/u and specific energy densities of the beam Q ∼ 5−20 GJ/cm2. The required specific energy density drops with increase in the ion energy; however, due to the increased path length, larger-charge ions have to be used.

Reflectionless acoustic gravity waves in the Earth’s atmosphere

The vertical wave propagation in an inhomogeneous compressible atmosphere is studied in the framework of a linear theory. Under specific conditions imposed on atmospheric parameters, solutions can be found in the form of travelling waves with variable amplitudes and wave numbers that do not reflect in the atmosphere in spite of its strong inhomogeneity. Model representations for the sound speed have been found, for which waves can propagate in the atmosphere without reflection. A wave energy flux retains these reflectionless profiles, which confirms that energy can be transferred to high altitudes. The number of these model representations is fairly large, which makes it possible to approximate real vertical distributions of the sound speed in the Earth’s atmosphere using piecewise reflectionless profiles. The Earth’s standard atmosphere is shown to be well approximated by four reflectionless profiles with weak jumps in the sound speed gradient. It has been established that the Earth’s standard atmosphere is almost completely transparent for the considered vertical acoustic waves in a wide range of frequencies, which is confirmed by observational data and conclusions derived using numerical solutions of original equations.

Analysis and synthesis of point distributions based on pair correlation

Analyzing and synthesizing point distributions are of central importance for a wide range of problems in computer graphics. Existing synthesis algorithms can only generate white or blue-noise distributions with characteristics dictated by the underlying processes used, and analysis tools have not been focused on exploring relations among distributions. We propose a unified analysis and general synthesis algorithms for point distributions. We employ the pair correlation function as the basis of our methods and design synthesis algorithms that can generate distributions with given target characteristics, possibly extracted from an example point set, and introduce a unified characterization of distributions by mapping them to a space implied by pair correlations. The algorithms accept example and output point sets of different sizes and dimensions, are applicable to multi-class distributions and non-Euclidean domains, simple to implement and run in O ( n ) time. We illustrate applications of our method to real world distributions.

The Study of Infrared Heating on PET Bottles by Experiment and Adaptive Finite Volume Method

Stretch-Blow moulding (SBM) fabricate process is a well known method to produce PET bottles. During the construction procedure, PET surface temperature distribution controlled by infrared heating is the key factor about manufacture technique for the better quality of PET. This paper focuses on how to measure and estimate temperature distribution on the surface of semi-transparent polymers so that we can make sure the proper position and intensity of the infrared lamb. We use infrared camera to detect the real temperature distributions and C++ object-oriented programming to estimate the infrared radiation (IR) results by adaptive finite volume method (Adaptive FVM). The numerical results have been compared with experimental results and the consequence is satisfied. Multiple lambs’ cases and the interior temperature distribution in PET will be discussed in future.

An experimentally validated finite element method for augmented vertebral bodies

BackgroundFinite element models of augmented vertebral bodies require a realistic modelling of the cement infiltrated region. Most methods published so far used idealized cement shapes or oversimplified material models for the augmented region. In this study, an improved, anatomy-specific, homogenized finite element method was developed and validated to predict the apparent as well as the local mechanical behavior of augmented vertebral bodies. MethodsForty-nine human vertebral body sections were prepared by removing the cortical endplates and scanned with high-resolution peripheral quantitative CT before and after injection of a standard and a low-modulus bone cement. Forty-one specimens were tested in compression to measure stiffness, strength and contact pressure distributions between specimens and loading-plates. From the remaining eight, fourteen cylindrical specimens were extracted from the augmented region and tested in compression to obtain material properties. Anatomy-specific finite element models were generated from the CT data. The models featured element-specific, density-fabric-based material properties, damage accumulation, real cement distributions and experimentally determined material properties for the augmented region. Apparent stiffness and strength as well as contact pressure distributions at the loading plates were compared between simulations and experiments. FindingsThe finite element models were able to predict apparent stiffness (R2>0.86) and apparent strength (R2>0.92) very well. Also, the numerically obtained pressure distributions were in reasonable quantitative (R2>0.48) and qualitative agreement with the experiments. InterpretationThe proposed finite element models have proven to be an accurate tool for studying the apparent as well as the local mechanical behavior of augmented vertebral bodies.

Multidimensional welfare distributions: empirical application to household panel data from Vietnam

This article explores the empirical application of theoretical multidimensional welfare distribution analysis techniques to real household welfare distributions. The article operationalizes recent conceptual developments in multidimensional distribution theory and assesses their usefulness for the measurement of multidimensional household inequality. The results strongly highlight the importance of bringing nonmonetary aspects of household welfare into the forefront of inequality analysis. Agreement over the various approaches to the measurement of multidimensional inequality entails, however, nontrivial decisions that may limit the practical usefulness of these measures. We suggest that the use of multidimensional inequality ranges and the application of restrictive dominance criteria to multidimensional welfare distributions may open significant scope for further developments in the empirical analysis of multidimensional inequality.

Inference of Genome Duplications from Age Distributions Revisited

Whole-genome duplications (WGDs), thought to facilitate evolutionary innovations and adaptations, have been uncovered in many phylogenetic lineages. WGDs are frequently inferred from duplicate age distributions, where they manifest themselves as peaks against a small-scale duplication background. However, the interpretation of duplicate age distributions is complicated by the use of K(S), the number of synonymous substitutions per synonymous site, as a proxy for the age of paralogs. Two particular concerns are the stochastic nature of synonymous substitutions leading to increasing uncertainty in K(S) with increasing age since duplication and K(S) saturation caused by the inability of evolutionary models to fully correct for the occurrence of multiple substitutions at the same site. K(S) stochasticity is expected to erode the signal of older WGDs, whereas K(S) saturation may lead to artificial peaks in the distribution. Here, we investigate the consequences of these effects on K(S)-based age distributions and WGD inference by simulating the evolution of duplicated sequences according to predefined real age distributions and re-estimating the corresponding K(S) distributions. We show that, although K(S) estimates can be used for WGD inference far beyond the commonly accepted K(S) threshold of 1, K(S) saturation effects can cause artificial peaks at higher ages. Moreover, K(S) stochasticity and saturation may lead to confounded peaks encompassing multiple WGD events and/or saturation artifacts. We argue that K(S) effects need to be properly accounted for when inferring WGDs from age distributions and that the failure to do so could lead to false inferences.

The Proposed OECD Treatment of Real Estate Investment Trust Distributions: Is the OECD Approach being Implemented in Tax Treaties?

The author, in this article, considers the proposed OECD tax treatment of distributions from real estate investment trusts and the extent to which the OECD proposal is being implemented by countries in their tax treaties.

Realistic Modeling of Resources for a Large-Scale Computational Grid System

To build a large-scale computational grid resource model with realistic characteristics, this paper proposes a statistical remedy to approximate the distributions of computational and communicational abilities of resources. After fetching the source data of resources including computing devices and networks from the real world, the gamma and normal distributions are employed to approximate probabilities for the ability distribution of grid resources. With this method, researchers can supply the computational grid simulators with required parameters relating to computational and communicational abilities. The experiment result shows that proposed methodology can lead to a better precision according to the error measurement of the simulated data and its source. The proposed method can support existing modern grid simulators with a high-precision resource model which can consider the characteristics of distribution for its computational and communicational abilities in the grid computing environment.

PIRS: Profile-based Illumina pair-end reads simulator

The next-generation high-throughput sequencing technologies, especially from Illumina, have been widely used in re-sequencing and de novo assembly studies. However, there is no existing software that can simulate Illumina reads with real error and quality distributions and coverage bias yet, which is very useful in relevant software development and study designing of sequencing projects. We provide a software package, pIRS (profile-based Illumina pair-end reads simulator), which simulates Illumina reads with empirical Base-Calling and GC%-depth profiles trained from real re-sequencing data. The error and quality distributions as well as coverage bias patterns of simulated reads using pIRS fit the properties of real sequencing data better than existing simulators. In addition, pIRS also comes with a tool to simulate the heterozygous diploid genomes. pIRS is written in C++ and Perl, and is freely available at ftp://ftp.genomics.org.cn/pub/pIRS/.

Diffraction residual stress analysis in technical components — Status and prospects

Over the years residual stress analysis using diffraction techniques developed to an important approach to solve basic scientific as well as application oriented problems in materials science and technology. In particular it became an indispensable tool for the dimensioning of highly loaded components as well as for the assessment of the quality of industrial production processes. Both laboratory X-ray sources as well as synchrotron radiation are used. For homogeneous residual stress states, process descriptions exist ensuring reliable and correct measurements not only under laboratory conditions but also in industrial environments.After a short survey about the physical background of the method, characteristic examples showing the basic principles and usefulness of residual stress analyses in technical components are given. In many cases, residual stress analyses are substantially complemented by additional information provided by the diffraction peaks, e.g. intensity or peak width. In case of residual stress depth gradients, which are very common in practice, the penetration depth of the X-rays used is of fundamental importance. On the one hand, integral values instead of depth resolved values result for very steep gradients. On the other hand, the maximum information depth for non-destructive analyses is limited. Different methods exist to achieve depth resolved residual stress analyses. The penetration depth of the X-rays can be adjusted using appropriate beam paths in the near surface volumes of the components under investigation. Here, if necessary, real space stress distributions have to be calculated from the measured data. On the other hand, special slit systems, integrated in the beam path as well as fixed to the component under investigation are applied to restrict the geometry of the material volume of interest. Angle resolved techniques are most common, but energy resolved analyses have specific advantages and are increasingly used.

STABILITAS STATIS DAN DINAMIS KAPAL PURSE SEINE DI PELABUHAN PERIKANAN PANTAI LAMPULO KOTA BANDA ACEH NANGGROE ACEH DARUSSALAM

Study on stability of a purseiner, which is based in Lampulo, has never been carried out till now. The objective of the research is to analized quality of stability of a purseiner which is based in Lampulo Fishing Port based on its real load distributions. Stability analysis was carried out on some load distributions variations, such as: 1) Condition 1; departure (100% fuel-0% load) ; 2) Con-dition 2, 3 and 4; arrival from fishing ground (fuel remain 20%, 25%, 20% and load of fish 100%, 70%, 50% ) and 3) Condition 5; arrival from fishing ground (55% fuel-100% load). Krylov method combines with trapezoidal approximation was used for analyzing. The results show that in all load conditions, this purseseiner show a good stability with the highest GZ maximum value in condition 4 (GZ max 0.63 m) and the lowest is in conditon 5 (GZ mas 0.52). Comparing to the IMO reco-mendation on stability, all load variations above are comply with the recomendations.

Real Estate Return Distributions Using Maximum Likelihood Estimation: New Technology, New Results

The estimation of parameters of real estate return distributions is affected by the tools used to do the work. Consistent with previous studies, investment risk models with infinite variance describe distributions of individual property returns in the National Council of Real Estate Investment Fiduciaries (NCREIF) database over the period 1980 to 2010. Applying Maximum Likelihood Estimation (MLE) to the historic data shows real estate investment risk to be heteroscedastic, but the characteristic exponent of the investment risk function varies more among property types than previously reported. Apartment properties introduced in this study evidence the same basic performance characteristics as office, retail, and industrial properties.

Topic‐sensitive search engine evaluation

PurposeThis work aims to investigate the sensitivity of ranking performance with respect to the topic distribution of queries selected for ranking evaluation.Design/methodology/approachThe authors reweight queries used in two TREC tasks to make them match three real background topic distributions, and show that the performance rankings of retrieval systems are quite different.FindingsIt is found that search engines tend to perform similarly on queries about the same topic; and search engine performance is sensitive to the topic distribution of queries used in evaluation.Originality/valueUsing experiments with multiple real‐world query logs, the paper demonstrates weaknesses in the current evaluation model of retrieval systems.

Scaling down distribution maps from atlas data: a test of different approaches with virtual species

AbstractAim Conservation managers are increasingly looking for modelled projections of species distributions to inform management strategies; however, the coarse resolution of available data usually compromises their helpfulness. The aim of this paper is to delineate and test different approaches for converting coarse‐grain occurrence data into high‐resolution predictions, and to clarify the conceptual circumstances affecting the accuracy of downscaled models.Location We used environmental data from a real landscape, southern Africa, and simulated species distributions within this landscape.Methods We built 10 virtual species at a resolution of 5 arcmin, and for each species we simulated atlas range maps at four decreasing resolutions (15, 30, 60, 120 arcmin). We tested the ability of three downscaling strategies to produce high‐resolution predictions using two modelling techniques: generalized linear models and generalized boosted models. We calibrated reference models with high‐resolution data and we compared the relative reduction of predictive performance in the downscaled models by using a null model approach. We also estimated the applicability of downscaling procedures to different situations by using distribution data for Mediterranean reptiles.Results All reference models achieved high performance measures. For all strategies, we observed a reduction of predictive performance proportional to the degree of downscaling. The differences in evaluation indices between reference models and downscaled projections obtained from atlases at 15 and 30 arcmin were never statistically significant. The accuracy of projections scaled down from 60 arcmin largely depended on the combination of approach and algorithm adopted. Projections scaled down from 120 arcmin gave misleading results in all cases.Main conclusions Moderate levels of downscaling allow for reasonably accurate results, regardless of the technique used. The most general effect of scaling down coarse‐grain data is the reduction of model specificity. The models can successfully delineate a species’ environmental association up until a 12‐fold downscaling, although with an increasing approximation that causes the overestimation of true distributions. We suggest appropriate procedures to mitigate the commission error introduced by downscaling at intermediate levels (approximately 12‐fold). Reductions of grain size > 12‐fold are discouraged.

Evaluation of procedural changes for minimizing noise impact near military airfields

Over time, communities surrounding military airfields tend to grow, while the noise generated by subsequent generations of military aircraft tends to increase. This creates an accelerating problem of human exposure to noise. One technique to alleviate this disparity is to modify attributes of flight trajectories in a way that reduces the sound exposure of the population. This involves the changing of flight ground tracks, profiles, and power settings within linear and non-linear boundaries which can include exceptions (such as no-fly-zones.) To demonstrate the effectiveness of these changes, DNL levels are calculated for real world population distributions and existing Navy departure procedures. These values are generated computationally using the widely accepted NoiseMap model. It is shown that significant reductions of exposure averaged over the population can be achieved in this way. Possible methods for automating this procedure are discussed. Properties of the objective function spaces are explored (e.g., convexity) and the appropriateness of different optimization methods is discussed. [Work supported by Naval Air Warfare Center.]

New methods in potential theory

A theory of equigravitating bodies by which external force fields of volumetric axially symmetric figures can be represented by unitary integrals is developed. This theory is being developed in three directions. The first is connected with the proof of the existence of equigravitating line segments. Such line segments can have both real and imaginary distributions of density; however, the mass and external potential remain real values. The ends of line segments coincide with special points (these are cusp points on the surfaces or special points of the analytical continuation of the external potential inside the body). At two special points, the body has only one line equigravitating segment, otherwise the line segments are compound or form equigravitating “skeletons.” At the isolated special points, external gravitational fields can be presented by a set of line segments and mass points. The second direction is based on a representation of the external gravitational field of volumetric axially symmetric figures with an equator plane by means of potentials of flat round disks. Such disks are obtained on the line segments with symmetric density distributions. The return is always true: for homogeneous or any nonuniform round disk, it is possible to find an equigravitating line segment. It manages to construct chains of “spheroid-disk-line segment” equigravitating bodies. The third direction of this theory is connected with the development and expansion on the scope of the method of confocal transformations. This method is modified and applied not only to continuous homogeneous ellipsoids, but also to non-uniform stratified ellipsoids with a stratification of the general type, as well as to homogeneous and nonuniform shells. Any elementary or thick ellipsoidal shells (and continuous nonuniform stratified ellipsoids) connected by special confocal transformations equigravitate each other.

Aircraft emissions and local air quality impacts from takeoff activities at a large International Airport

Real time number concentrations and size distributions of ultrafine particles (UFPs, diameter <100 nm) and time integrated black carbon, PM2.5 mass, and chemical species were studied at the Los Angeles International Airport (LAX) and a background reference site. At LAX, data were collected at the blast fence (∼140 m from the takeoff position) and five downwind sites up to 600 m from the takeoff runway and upwind of the 405 freeway. Size distributions of UFPs collected at the blast fence site showed very high number concentrations, with the highest numbers found at a particle size of approximately 14 nm. The highest spikes in the time series profile of UFP number concentrations were correlated with individual aircraft takeoff. Measurements indicate a more than 100-fold difference in particle number concentrations between the highest spikes during takeoffs and the lowest concentrations when no takeoff is occurring. Total UFP counts exceeded 107 particles cm−3 during some monitored takeoffs. Time averaged concentrations of PM2.5 mass and two carbonyl compounds, formaldehyde and acrolein, were statistically elevated at the airport site relative to a background reference site. Peaks of 15 nm particles, associated with aircraft takeoffs, that occurred at the blast fence were matched with peaks observed 600 m downwind, with time lags of less than 1 min. The results of this study demonstrate that commercial aircraft at LAX emit large quantities of UFP at the lower end of currently measurable particle size ranges. The observed highly elevated UFP concentrations downwind of LAX associated with aircraft takeoff activities have significant exposure and possible health implications.

Two real parton contributions to non-singlet kernels for exclusive QCD DGLAP evolution

Results for the two real parton differential distributions needed for implementing a next-to-leading order (NLO) parton shower Monte Carlo are presented. They are also integrated over the phase space in order to provide solid numerical control of the MC codes and for the discussion of the differences between the standard $\bar{MS}$ factorization and Monte Carlo implementation at the level of inclusive NLO evolution kernels. Presented results cover the class of non-singlet diagrams entering into NLO kernels. The classic work of Curci-Furmanski-Pertonzio was used as a guide in the calculations.