Parameters Of Distribution Function Research Articles

NEW DIRECTIONS IN PREDICTING AND MODELING TRUCK LOAD POPULATIONS INCLUDING OVERLOADS

Overload trucks often appear as a sizeable portion of truck populations on highways. Within most transportation jurisdictions in the United States, overloads refer to truck weights in excess of 356 kN (80 kips). The load populations exhibit an inconsistent pattern-often with two or more distinct peaks. This paper represents new directions in modeling truck load patterns with capabilities to offer the continuity as well as the bimodal feature of the load data. The method presented is data-driven and uses a bimodal distribution function. The extension of the model to predict the truck load population when data are incomplete or not available is also presented. The parameters required in the model are estimated via the fuzzy regression analysis in the proposed method. The fuzzy regression analysis allows the utilization of subjective and limited information. The Weigh-in-Motion (WIM) data obtained from several stations were used to quantify the parameters of this bimodal distribution function by employing the fuzzy regression analysis. The procedure on obtaining an appropriate distribution function for truck load population is explained along with illustrative examples.

Aleurite particle concentration profiles in the surface layer of the atmosphere on desertificated areas

The large particle mass flux profile measurement at heights from 0.125 to 16 m and parameters of the size distribution function received by O.E. Semenov on the desertificated areas in the Aral region were analyzed. The technique has been worked out for the large particle height profile characteristic retrieving. The aleurite particle number concentration profiles with sizes less than 50, 73 and 100 μm and sand particle concentration have been retrieved. Power-law approximations of the vertical aleurite and sand particles concentrations profiles are proposed.

Large-scale parameter modelling for millimeter-wave multiple-input multiple-output channel in 5G ultra-dense network

<span>Network densification (ND) in 5G has been suggested as a solution to improve network capacity. ND has small cell backhaul as its bottleneck in the ensuing ultra-dense network (UDN). Due to the new deployment scenarios of small cells, it becomes necessary to thoroughly investigate the radio-propagation characteristics of the new transmission path between the base station and the small cells. The problem of the impact of small cell height on the backhaul large-scale parameters under typical outdoor-to-indoor (high-rise) and outdoor-to-outdoor (street canyon) scenarios was first investigated. Next, the probability distribution functions of the various parameters were investigated and modeled. Novel use of 5G NR air interface using a deterministic ray-tracing engine to characterize the backhaul at <br /> 28 GHz center frequency and 100 MHz bandwidth using 4x4 cross-polarized uniform planar array (UPA) at the base station and 2x2 multiple input, multiple output (MIMO) antennas at the small cells was proposed. New sets of models for root mean square (RMS) delay spread and RMS angular spread suitable for predicting network deployment in the two scenarios and similar environments were presented.</span>

A novel route to improve the fatigue properties of aviation M50 steel via tailoring the bainite content and cold deformation

The microstructure, mechanical and fatigue properties of M50 steel by combining austempering processing with cold deformation have been investigated. The results show that the introduction of bainite can effectively refine the multiphase microstructure. When the bainite content is 10.5%, the finest microstructure and the best combination between strength and toughness can be obtained. It is also found that 20% cold deformation leads to a slight improvement of tensile strength and impact toughness, while the mechanical properties deteriorates significantly under larger cold deformation. It is concluded that the mechanical properties can be improved by tailoring the bainite content at about 10% and cold deformation degree at 20%. For the tailored specimen, the specific life of rolling contact fatigue is 114.1% longer than that of traditional martensitic quenched specimen. The slope parameter of Weibull distribution function also shows an increase from 1.8267 to 2.2992, reflecting the more stable of RCF life. There are fewer microcracks in the subsurface of peeling pits, which should be attributed to the higher toughness and finer carbides. Additionally, owing to the higher density of grain/phase boundaries, the tailored specimen with a lower hardness shows better resistance to plastic deformation under the wear trace. This finding provides a novel route to improve the RCF properties of M50 steel via strictly tailoring the bainite content and cold deformation degree.

Bayesian inference of finite-nuclei observables based on the KIDS model

Bayesian analyses on both isoscalar and isovector nuclear interaction parameters are carried out based on the Korea-IBS-Daegu-SKKU (KIDS) model under the constraints of nuclear structure data of $^{208}$Pb and $^{120}$Sn. Under the constraint of the neutron-skin thickness, it is found that incorporating the curvature parameter $K_{sym}$ of nuclear symmetry energy as an independent variable significantly broadens the posterior probability distribution function (PDF) of the slope parameter $L$, and affects the related correlations. Typically, the anticorrelation between $L$ and the symmetry energy at saturation density disappears, while a positive correlation between $L$ and $K_{sym}$ is observed. Under the constraint of the isoscalar giant monopole resonance (ISGMR), incorporating the skewness parameter as an independent variable also significantly broadens the posterior PDF of the nuclear matter incompressibility $K_0$. Even with the broad uncertainties of higher-order parameters of the equation of state (EOS), robust constraints of $L<90$ MeV and $K_0<270$ MeV are obtained. Our study quantifies the consistency between the constraints on $L$ from the neutron-skin data of PREXII and isovector giant dipole resonance (IVGDR) data, and the constraints on $K_0$ from the data of ISGMR in $^{208}$Pb and $^{120}$Sn.

Molecular hydrogen sorption capacity of P216-schwarzite: PM6-D3, MP2 and QTAIM approaches

Schwarzites, due to their high porosity, are among prospective materials for the sorption of different gases, including hydrogen. Their surface possesses negative Gaussian curvature that intimately determines how many carbon atoms each hydrogen molecule will interact with, which, in turn, defines the fraction of hydrogen that would be sorbed in the schwarzite. The critical question about contributions to the sorption of the surface topology and electronic effects is solved here. Within the framework of the QTAIM theory, the topological parameters of the electron density distribution function at the bond critical points characterizing the dispersion interaction of the H2 molecule with the carbon surface are estimated. On the example of molecules [6]circulene and [7]circulene, it was shown that, despite the electronic effects arising from the bending of this surface, on average, the energy of physical sorption of hydrogen obtained using MP2 calculations changes insignificantly – by about 0.1 kJ/mol in the case of, for example, vertical orientation of the molecule. By calculating the thermochemical properties by the PM6-D3 method, the dependence of the weight fraction of hydrogen sorbed in P216-schwarzite on the external gas pressure and the temperature has been established. In particular, it was shown that at 300 K and 10 MPa, this value is 4.6%, slightly higher than other carbon nanostructures with similar density, porosity, and accessible surface area values.

Limits on non-canonical heating and turbulence in the intergalactic medium from the low redshift Lyman α forest

ABSTRACT We examine the column density distribution function (CDDF) and Doppler parameter distribution from hydrodynamical simulations and Cosmic Origins Spectrograph (COS) observations of the Ly α forest at redshift 0 ≤ z ≤ 0.2. Allowing for a factor of two uncertainty in the metagalactic H $\, \rm \scriptstyle I \, $ photoionization rate, our hydrodynamical simulations are in good agreement (1–1.5σ) with the shape and amplitude of the observed CDDF at H $\, \rm \scriptstyle I \, $ column densities $10^{13.3}\rm \, cm^{-2}\le N_{\rm H\,{\small I}}\le 10^{14.5}\rm \, cm^{-2}$. However, the Doppler widths of the simulated lines remain too narrow with respect to the COS data. We argue that invoking AGN feedback does not resolve this discrepancy. We also disfavour enhanced photoheating rates as a potential solution, as this requires an unphysically hard UV background spectrum. If instead appealing to a non-canonical source of heating, an additional specific heat injection of $u \lesssim 6.9\rm \, eV\, m_{\rm p}^{-1}$ is required at z ≲ 2.5 for gas that has $N_{\rm H\,{\small I}}\simeq 10^{13.5}\rm \, cm^{-2}$ by z = 0.1. Alternatively, there may be an unresolved line of sight turbulent velocity component of $v_{\rm turb}\lesssim 8.5\rm \, km\, s^{-1}(N_{\rm H\,{\small I}}/10^{13.5}\rm \, cm^{-2})^{0.21}$ for the coldest gas in the diffuse IGM.

Dynamical Anomaly of Aqueous Amphiphilic Solutions: Connection to Solution H-Bond Fluctuation Dynamics?

We have investigated the possible connection between “dynamical anomaly” observed in time-resolved fluorescence measurements of reactive and nonreactive solute-centered relaxation dynamics in aqueous binary mixtures of different amphiphiles and the solution intra- and interspecies H-bond fluctuation dynamics. Earlier studies have connected the anomalous thermodynamic properties of binary mixtures at very low amphiphile concentrations to the structural distortion of water. This is termed as “structural anomaly.” Interestingly, the abrupt changes in the composition-dependent average rates of solute relaxation dynamics occur at amphiphile mole fractions approximately twice as large as those where structural anomalies appear. We have investigated this anomalous solution dynamical aspect by considering (water + tertiary butanol) as a model system and performed molecular dynamics simulations at several tertiary butanol (TBA) concentrations covering the extremely dilute to the moderately concentrated regimes. The “dynamical anomaly” has been followed via monitoring the composition dependence of the intra- and interspecies H-bond fluctuations and reorientational relaxations of TBA and water molecules. Solution structural aspects have been followed via examining the tetrahedral order parameter, radial and spatial distribution functions, numbers of H bonds per water and TBA molecules, and the respective populations participating in H-bond formation. Our simulations reveal abrupt changes in the H-bond fluctuations and reorientational dynamics and tetrahedral order parameter at amphiphile concentrations differing approximately by a factor of 2 and corroborates well with the steady-state and the time-resolved spectroscopic measurements. This work therefore explains, following a uniform and cogent manner, both the experimentally observed structural and dynamical anomalies in microscopic terms.

Accurate small major hysteresis loops calculation by the Preisach model with improved parametric distribution function

The inversed Preisach hysteresis model is widely used to realize the rapid coupling of hysteresis characteristics of core materials in finite element analysis. However, the small major hysteresis loop is difficult to be accurately simulated. In this paper, an improved inversed Preisach model based on an improved parametric distribution function is proposed. By analyzing the magnetic remanence, the waveform factor is coupled with the parametric distribution function, and the identification of the small major hysteresis loop is strengthened. The distribution function parameters can be found from the limit hysteresis loop through the optimization algorithm. In the numerical calculation process of the model, the amplitude correction coefficient in the discrete formula is extracted by the basic magnetization curve. Compared with the previous method, this method simulates the limit hysteresis loop well and has higher simulation accuracy for the small major hysteresis loops.

A Novel Atmospheric Correction Algorithm to Exploit the Diurnal Variability in Hypertemporal Geostationary Observations

This study developed a new atmospheric correction algorithm, GeoNEX-AC, that is independent from the traditional use of spectral band ratios but dedicated to exploiting information from the diurnal variability in the hypertemporal geostationary observations. The algorithm starts by evaluating smooth segments of the diurnal time series of the top-of-atmosphere (TOA) reflectance to identify clear-sky and snow-free observations. It then attempts to retrieve the Ross-Thick–Li-Sparse (RTLS) surface bi-directional reflectance distribution function (BRDF) parameters and the daily mean atmospheric optical depth (AOD) with an atmospheric radiative transfer model (RTM) to optimally simulate the observed diurnal variability in the clear-sky TOA reflectance. Once the initial RTLS parameters are retrieved after the algorithm’s burn-in period, they serve as the prior information to estimate the AOD levels for the following days and update the surface BRDF information with the new clear-sky observations. This process is iterated through the full time span of the observations, skipping only totally cloudy days or when surface snow is detected. We tested the algorithm over various Aerosol Robotic Network (AERONET) sites and the retrieved results well agree with the ground-based measurements. This study demonstrates that the high-frequency diurnal geostationary observations contain unique information that can help to address the atmospheric correction problem from new directions.

Estimation of Distribution Function Parameters for Cases of Risk of Mortality Rate due to Malnutrition and Unhealthy Sanitation in Indonesia

Child undernutrition is a significant problem in Indonesia; persistently high rates of stunting, underweight and wasting. Data about malnutrition and sanitation that taken for this research is data of age-standardized death rate, measured per 100,000 individuals from unsafe sanitation and malnutrition in Indonesia. The purpose of this research is to determine the distribution function and estimate the parameter distribution, so the values can provide identification of risk events. The method used for this research is Maximum Likelihood Estimation (MLE) and Newton Raphson iterations. The distribution function formed is gamma and Generalized Pareto Distribution (GPD), respectively for sanitation and malnutrition problems in Indonesia. The projected probability of occurrence of the risk of death due to malnutrition tends to be low in the future. So that the risk classification of the mortality rate due to malnutrition is considered low based on the results of the probability distribution approach on the GPD function. While, the projected probability of occurrence of the risk of death due to sanitation tends to decrease in the future. Based on the graph, the risk value with a high probability is around 20. So, the risk classification of the mortality rate due to malnutrition is considered moderate based on the results of the probability distribution approach on this gamma function.

The Influence of Humidity on Electron Transport Parameters and Insulation Performance of Air

The environmental conditions affect the external insulation performance of power equipment. In order to study the physical characteristics of air discharge, the microscopic process of electron–molecule collision in the air based on the Boltzmann equation has been studied in this paper. The influence of humidity on the air gap insulation performance was also analyzed. The calculation results show that with the temperature 300 K and the pressure 1.0 atm, the electron energy distribution function and electron transport parameters varied with the air relative humidity. As the air relative humidity is increased by each 30%, the average electron energy decreases by about 0.2 eV, the reduced electron mobility decreases by about 0.25 × 1023 [1/(V·m·s)], the reduced electron diffusion coefficient decreases by about 0.2 × 1024 [1/(m s)], and the effective ionization coefficient decreases by about 4 × 10−24 m2. As the air relative humidity increases from 0% to 60%, the critical breakdown electric field increases by 1.22 kV/cm.

Визначення параметричного простору показників для оцінювання доступності інфокомунікаційного процесу в бездротовому централізованому мережевому кластері

The article analytically defines the model of parametric space of indicators for assessing the availability of infocommunication process in a wireless centralized network cluster. The researched process is described as a Markov queuing system, the controlled parameter of which is the total amount of occupied system resources for all active sessions of info-communication interaction. The defined space of qualitative stochastic characteristics included: the average amount of occupied system resources and the average number of active sessions of infocommunication interaction in the information environment of the base station; the probability of losing the incoming request due to insufficient free system resources or lack of free communication channels on the base station side. Also, the functional dependences of the values of the listed qualitative characteristics on the type and parameters of the volume distribution function of the released system resources of the base station are analytically determined. As additional controlled parameters in the created model such characteristics as the level of loading of the front-end interface of the base station and the desired amount of system resources specified in the input request are taken into account. From the results of empirical research of the created mathematical apparatus it was found that with increasing load on the front-end interface of the studied system, the values of all characteristic parameters of the metric of qualitative indicators increase. Note that the simultaneous increase in the values of the average volume of occupied system resources and the average number of active sessions of infocommunication interaction occurs almost linearly, in contrast to the behavior of the value of the probability of loss of incoming request, which increases exponentially. The obvious reason for the increase in the probability of losing an incoming request is the increase in the variance of the value of such a characteristic parameter as the desired amount of system resources in incoming requests. It was also found that the geometric distribution-based scheme for managing the allocation of system resources shows a tendency to satisfy incoming requests with less value of the desired amount of system resources and is generally focused on supporting already active sessions of infocommunication interaction.

Numerical approaches and analysis of optical measurements of laser radar cross-sections affected by aero-optical transmission

One of the concerns in the process of measuring laser radar cross-section (LRCS) using optical measurement methods is the aero-optical effect around a high-speed flow field. In this paper, a computational model for LRCS considering supersonic flow in a non-homogeneous medium is presented. First, by taking a typical 15° half-cone blunt cone as the research object, based on CFD calculation, the flow field distribution of the non-uniform medium around the high-speed vehicle is obtained. The ray-tracing method is used to calculate the light transmission in an aero-optical environment. An LRCS approach for arbitrarily complex targets in the aero-optical environment is then proposed, and the method is verified by analytical and numerical methods. Finally, the effects of incoming density, incoming Mach number, and material bidirectional reflectance distribution function (BRDF) parameters on LRCS measurements are investigated, and the errors caused by the steady aero-optical environment are analyzed. The results show that the maximum relative error of the measurement caused by the aero-optical environment in the direction of the shock-wave layer observation is significant when the Fresnel function approximation exponential function parameter is too large or when the root mean square (RMS) of the surface slope is too small in the BRDF parameters of the material. The influence of the aero-optical environmental flow field on the LRCS is characterized by a directional and regional distribution, determined by the incoming Mach number and shock-wave angle, with the influence of the incident flow density on the regional distribution being weakly correlated. The proposed method and calculation results are useful for the simulation, analysis, and calibration of LRCS measurements in complex aero-optical environments.

Using molecular dynamics and experiments to investigate the morphology and micro-structure of SBS modified asphalt binder

The study aimed at investigating the compatibility between styrene-butadiene-styrene (SBS) and asphalt, and the influence of SBS on morphology and micro-structure of asphalt through molecular dynamics (MD) and experiments method. In this work, the solubility parameter and molecular structure parameters of SBS modified asphalt were calculated by Materials Studio software, and its morphology of were investigated by microscope techniques. The results showed that solubility parameter of SBS and asphalt fluctuated along with simulation temperature, and the difference between SBS and asphalt is around 10.5 (J/cm3)0.5, which means these two materials cannot reach a total miscible state, and the scanning electron microscope (SEM) and fluorescence microscope (FM) results on the compatibility between asphalt and SBS corresponding with the simulation results. The interaction simulation on SBS and asphalt indicated that van der Waals interaction makes a significant contribution to non-bond interaction and plays a dominate role in the miscibility between asphalt and SBS. The structure parameters of radial distribution function (RDF) and radius of gyration showed that SBS had an a evident influence on the structure of asphalt molecule, for it increased the tightness of the asphalt and reinforced the ractility of branched-chain of asphalt components. Through AFM test results, we also found that SBS increased the bee-like phase of asphalt, and bring asphalt a better physical properties.

StringSpinner - adding spin to the PYTHIA string fragmentation

StringSpinner is a plugin allowing for the introduction of spin effects in the hadronization part of the PYTHIA 8 event generator. In this first version the implementation is limited to handling pesudoscalar mesons in events without parton showers. The spin effects are generated by propagating the quark polarization along the fragmentation chain according to the rules of the quantum mechanical string+P03 model. By using parametrizations for the transversity parton distribution functions, StringSpinner allows to simulate the polarized semi inclusive deep inelastic scattering process on protons and neutrons. The instructions to use StringSpinner and to modify the parametrizations of the transversity distribution functions are presented, as well as an example of the calculation of the Collins asymmetries as obtained from simulations of the transversely polarized semi inclusive deep inelastic scattering process. Program summaryProgram Title: StringSpinnerCPC Library link to program files:https://doi.org/10.17632/37jrpmyz3t.1Developer's repository link:https://gitlab.com/albikerbizi/stringspinner.gitLicensing provisions: GNU GPL v2 or laterProgramming language: C++, FortranNature of problem: To analyse and interpret the experimental data on the study of the nucleon spin structure, as well as to make predictions for future experiments simulations are needed.Solution method: Introduce spin effects in the hadronization part of a complete Monte Carlo event generator, largely used in the community of high energy particle physicists.

A non-Darcy gas flow model for coalbed methane in mine gobs

The expected extraction efficiency of coalbed methane (CBM) depends significantly on the laws considered to govern its gas flow. This study applies a non-Darcy gas flow model to describe the CBM migration in mine gobs; by mine gob, we mean that it is a fractured zone along with massive cracks and the primary place where gas flows after mining activities. A permeation experiment involving crushed sandstone is first conducted to prove the CBM undergoes Forchheimer-type non-Darcy flow. Subsequently, the three-dimensional continuous distribution functions of the permeability parameters are determined. The non-Darcy flow model includes the influence of inertial force on the gas flow, which is neglected in the Darcy model. A coupling model is established based on the experimental results and the gas flow characteristics in different regions. Thereafter, the model and distribution functions are applied to a series of numerical simulations of CBM extraction at the Sihe coal mine in China, to ascertain the most appropriate location for a ground borehole. These simulations involve boreholes placed in three different zones: the natural accumulation zone (NAZ), the load affected zone (LAZ), and the compaction stable zone (CSZ). The simulation results show that the total extraction quantity expected from the borehole in the NAZ is 2.4 and 13.5 times that from the boreholes in the LAZ and CSZ, respectively. This confirms that the NAZ is the most suitable zone for a borehole. This research ultimately provides a realistic gas flow model for CBM extraction from mine gobs.

Performance Comparison of New Generation Parameter Estimation Methods for Weibull Distribution to Compute Wind Energy Density

To install a wind energy conversion system to a region, the wind speed characteristics of that region must be identified. The two-parameter Weibull distribution is highly efficient in modeling wind speed characteristics. In this study, the wind speed data of 32 cities in three different regions of Turkey have been comparatively analysed to estimate Weibull distribution function parameters by the use of three well-known methods (Graphical Method (GM), Maximum Likelihood Method (MLM), Justus Moment Method (JMM)) and three new parameter estimation methods (Energy Pattern Factor Method (EPFM), Wind Energy Intensification Method (WEIM), Power Density Method (PD)) which have been proposed in recent years. Three years of hourly wind speed data of the specified regions have been used. The performance metrics of these analyses have been compared using Wind Energy Error (WEE), Root Mean Square Error (RMSE), and Coefficient of Determination (R2). The results have shown that while the PD method has high model performance, the JMM is closely competitive with the MLM. Besides, the wind energy densities that were estimated by using actual data have been compared with the resulting Weibull distribution. It has been clear that the method that has the closest estimation to the actual values is the PD method.

Probabilistic analysis of soil-water characteristic curve based on machine learning algorithms

The soil-water characteristic curve (SWCC) is the constitutive relationship curve of soil suction and water content, which has important engineering significance for studying the soil strength, permeability coefficient and volume change of unsaturated soils. Considering the experimental measurement of the SWCC is time-consuming, many empirical methods have been suggested to estimate the SWCC. This paper proposed a machine learning algorithm to predict SWCC from limited sets of soil properties. By predicting the parameters of the Fredlund and Xing model (which is called FX model), the most probable SWCC can be obtained. Since SWCC can’t be accurately determined, the residual probability distribution functions of parameters of FX model are also derived in this paper. Finally, this paper predicted the 90% confidence interval of the SWCC. The result shows that the machine learning algorithm has high accuracy and generalization ability. The suggested method provides a practical means to estimate the SWCC and the variability of it, so that the error associated with the prediction model can be explicitly considered.

Fatigue life of preloaded injection bolts in a bridge strengthening scenario – sensitivity analysis of fatigue life estimators

AbstractOld metallic bridges are prone to high levels of structural degradation due to their long service life, therefore, it is essential to study strengthening techniques. Implementation of injection bolts to replace riveted joints exposed to fatigue damages has been studied. The mechanical performance of injection bolts has been studied mainly based on quasi‐static or creep tests. The objective of this paper is comparison of fatigue resistance between bolted joints with preloaded injection bolts opposing bolted joints with preloaded high strength bolts. Specimens were defined aiming to reproduce as close as possible a strengthening scenario. Single and double lap joints were tested. The fatigue phenomenon has a stochastic nature and therefore robust models are necessary to estimate parameters of distribution functions. Therefore, different estimation methodologies were implemented to determine the parameters of Weibull distribution. The main goal was to define reliable S‐N design curves. Results showed that the use of preloaded injection bolts contribute to increase the fatigue life and to reduce the scatter, mainly for double lap joints. It is shown that S‐N curves of EN1993‐1‐9 do not represent the fatigue strength of structural details with old metallic materials.