Record Values Research Articles

Dramatically Improved Thermoelectric Properties by Defect Engineering in Cement-Based Composites.

In recent years, the problem of overheating in summer has been of great concern. Pavements are continuously exposed to solar radiation, and because of high temperatures, pavement temperatures reach 60 to 70 °C. This potential low-grade heat has been unused. Cement-based composites with thermoelectric properties can convert this low-grade heat to useful electrical energy. The importance of this green technology for generating renewable energy and sustainable development has been widely accepted and noticed. However, the power factor of current cement-based composites is too low, and harvesting low-grade heat on a large scale and at low cost requires improving the thermoelectric properties of cement-based composites. In this paper, we present a method to increase the electrical conductivity of ZnO and thus improve the thermoelectric properties of cement-based composites by defect engineering, obtaining a high power factor of 224 μWm-1 K-2 at 70 °C, a record value recently reported for thermoelectric cement-based composites. Zinc oxide powder was treated with a reducing atmosphere to increase the content of oxygen defects and thus improve the electrical conductivity. Pretreated ZnO powder of 5.0 and 10.0 wt % expanded graphite were added to the cement matrix. The ZnO/expanded graphite cement-based composites were made and tested for their thermoelectric properties using a dry pressing process, which exhibited excellent thermoelectric properties. The result showed high conductivity (12.78 S·cm-1), a high Seebeck coefficient (-419 μV/°C), a high power factor (224 μWm-1 K-2), and a high figure of merit value (8.7 × 10-3), which facilitate future large-scale applications. Using the cement-based composites to lay a road of 1 km in length and 10 m in width, 35.2 kW·h of electricity can be collected in 8 h. This study will inspire how to improve thermoelectric performance of cement-based composites.

Moments of order statistics and k-record values arising from the complementary beta distribution with application

The order statistics (OSs) arise in both practical and theoretical aspects including goodness-of-fit tests, characterizations of probability distributions and some estimation approaches such as the L-moments method. Most of these instances are connected with moments of OSs. The records and k-record statistics, also called kth record values in the literature, are other important topics related to the OSs. This kind of data appears in some practical circumstances, e.g. shock models, industrial stress testing and meteorological data analysis. This paper deals with deriving recurrence relations for the single and the product moments of OSs as well as k-record values from the complementary beta (CB) distribution defined by Jones (2002). The CB model, as a distribution on the unit interval, is more flexible than the well-known beta distribution in problems involving moments of OSs. This fact suggests that the former distribution can be employed rather than the latter when OSs are of the main interest. The results obtained are applied on four real data sets for the issues of parameter estimation as well as providing a visual inspection for goodness-of-fit of the CB model.

Record Energetics for an Inertial Fusion Implosion at NIF.

Inertial confinement fusion seeks to create burning plasma conditions in a spherical capsule implosion, which requires efficiently absorbing the driver energy in the capsule, transferring that energy into kinetic energy of the imploding DT fuel and then into internal energy of the fuel at stagnation. We report new implosions conducted on the National Ignition Facility (NIF) with several improvements on recent work [Phys. Rev. Lett. 120, 245003 (2018)PRLTAO0031-900710.1103/PhysRevLett.120.245003; Phys. Rev. E 102, 023210 (2020)PRESCM2470-004510.1103/PhysRevE.102.023210]: larger capsules, thicker fuel layers to mitigate fuel-ablator mix, and new symmetry control via cross-beam energy transfer; at modest velocities, these experiments achieve record values for the implosion energetics figures of merit as well as fusion yield for a NIF experiment.

On a weighted exponential distribution with a logarithmic weight: theory and applications

A new weighted exponential distribution is proposed with the feature to use a logarithmic weight function. Among the merits, this distribution shows a remarkable flexibility with respect to the probability density and hazard functions shapes. Mathematical properties are studied, including moments, residual life function, order statistics and record values. A parametric estimation is performed using the maximum likelihood method. Applications are provided using four practical data sets. It is shown that the new distribution works better than a number of classical and recent distributions.

Testing symmetry based on the extropy of record values

In this paper, we first present the symmetric property of the extropy of record values and some characterisations of exponential distributions. Then a new test for symmetry of the continuous distribution is proposed based on a characterisation result. Our proposed test has an advantage that we do not need to estimate the centre of symmetry. Moreover, for a wide variety of alternative asymmetric distributions, Monte Carlo simulation shows that our test performs better than the competitor tests. Finally, two real data sets are used to illustrate the applicability of the proposed test by monitoring p-values of our test and its competitors.

Classical and Bayesian Inference of GPW Distribution Based on Record Values: Estimation and Prediction

In this paper, the classical and Bayesian estimation of the parameters of generalized power Weibull distribution based on record values are discussed. Lindley approximation is used to obtain explicit forms of Bayes estimators. Also, the classical and Bayesian predictions of the future record values from generalized power Weibull distribution are discussed. A real dataset and the simulation study are presented for illustration purposes.

On Generalizations of the Optimal Choice Problem

In this paper, we consider generalizations of the optimal choice problem. There is a sequence of n identically distributed random variables on the interval [0, 1]. Sequentially obtaining the observed values of these quantities, it is necessary at some point to stop at one of them, taking it as the starting point for counting the upper or lower record values. In the optimal choice problem and its generalizations, it is required to make the correct choice of the starting point of the records in order to maximize the mathematical expectation of the sum of values or the number of upper, lower, or both record values obtained as a result of such a procedure. A review of the results on the uniform distribution of random variables and new results on the exponential distribution of random variables are presented.

On relations for moments of the normal $k$th record values and a characterization

В статье приводятся явные выражения для моментов $k$-х рекордных величин нормального распределения, а также соотношения между $r$-м моментом, $(r-2)$-м моментом и моментом произведения. Эти соотношения позволяют вычислить коэффициенты асимметрии и эксцесса рекордных величин и дать новую характеризацию нормального распределения.

ESTABLISHING SOLAR ACTIVITY TREND FOR SOLAR CYCLES 21 – 24

Solar-terrestrial environment is manifested primarily by the physical conditions of solar interior, solar atmosphere and eruptive solar plasma. Each parameter gives unique information about the Sun and its activity according to its defined characteristics. Hence the variability of solar parameters is of interest from the point of view of plasma dynamics on the Sun and in the interplanetary space as well as for the solar-terrestrial physics. In this study, we have analysed various solar transients and parameters to establish the recent trends of solar activity during solar cycles 21, 22, 23 and 24. The correlation coefficients of linear regression of F10.7 cm index, Lyman alpha index, Mg II index, cosmic ray intensity, number of M & X class flares and coronal mass ejections (CMEs) occurrence rate versus sunspot number was examined for last four solar cycles. A running cross-correlation method has been used to study the momentary relationship among the above mentioned solar activity parameters. Solar cycle 21 witnessed the highest value of correlation for F10.7 cm index, Lyman alpha index and number of M-class and X-class flares versus sunspot number among all the considered solar cycles which were 0.979, 0.935 and 0.964 respectively. Solar cycle 22 recorded the highest correlation in case of Mg II index, Ap index and CMEs occurrence rate versus sunspot number among all the considered solar cycles (0.964, 0.384 and 0.972 respectively). Solar cycle 23 and 24 did not witness any highest correlation compared to solar cycle 21 and 22. Further the record values (highest value compared to other solar three cycles) of each solar activity parameters for each of the four solar cycles have been studied. Here solar cycle 24 has no record text at all, this simply indicating that this cycle was a weakest cycle compared to the three previous ones. We have concluded that in every domain solar 24 was weaker to its three predecessors.

On Relations for Moments of the Normal ${k}$th Record Values and a Characterization

Article DataHistorySubmitted: 22 January 2020Published online: 02 November 2021Keywords$k$th upper record values, complete sequence of functions, characterization of probability distributionsPublication DataISSN (print): 0040-585XISSN (online): 1095-7219Publisher: Society for Industrial and Applied MathematicsCODEN: tprbau

РИНОК МІЖНАРОДНИХ ІНВЕСТИЦІЙНИХ РЕСУРСІВ: СТРУКТУРА ТА СУЧАСНІ ТЕНДЕНЦІЇ РОЗВИТКУ

The article is devoted to the study of the dynamics of the market of international investment resources. A comprehensive analysis of current trends in the market of international investment resources in terms of its structural division into the market of foreign direct investment, the market of basic investment instruments - stocks and bonds, and the market of financial derivatives. Based on the analyzed statistical information, the authors draw conclusions about current trends in the international market of investment resources. The analysis of the foreign direct investment market revealed a tendency to decrease the volume of direct investment capital in all regions of the world. It is shown that foreign direct investment market is suffering severely from the crisis caused by the COVID-19 pandemic, as well as from the impact of other factors such as the new industrial revolution, the transition of many world policies to greater economic nationalism, and the trend of sustainable development. In particular, countries with transition economies, developed and developing countries are suffered from decline of about 40% of foreign direct investments most of all. The market of basic investment instruments demonstrates a tendency to recover: the global stock market and the bond market also suffered significantly at the beginning of the pandemic in March 2020, but by the end of 2020 these markets had almost fully recovered and the bond market in general began to show record volumes and values. The derivatives and hybrid financial instruments market is showing a steady positive upward trend in 2020: trading in instruments such as currency futures, stock market futures, ETF options, etc. is showing significant growth. Such trends indicate that investors have become more active in portfolio investment strategies.

Axiograph and the Panoramic Radiographic Imaging Technique, an Alternative to Conventional Technique to Record Condylar Guidance

Introduction: The documentation of the maxillomandibular relationship and the recording values of condylar guidance is the most critical, yet essential step in fabrication of complete denture prosthesis and it also helps in diagnosing, treatment planning, and fabrication of the balanced complete denture prosthesis that aids in enhancing the aesthetics, and maintenance of the stomatognathic system. Various techniques are available to record the condylar guidance; One of them being axiographic technique and panoramic radiograph followed by programming the semi adjustable articulators. Aim: The aim of the present study was to evaluate and compare the condylar guidance using the conventional technique the gothic arch tracing with that of axiographic technique and the panoramic radiographs. Materials and Methods: The observational study with the clinical set up was carried out over a period between October 2018- March 2019. Twenty completely edentulous patients were selected for the study. The comparative evaluation of axiographic tracing technique, panoramic radiographic technique and the extraoral gothic arch tracing technique was conducted. The horizontal condylar guidance values obtained with these techniques were assessed. The data obtained was statistically analysed using Karl Pearson correlation test to determine the correlation between the values obtained from all the three techniques on the right side and the left side of the subjects. Paired t-test and Bonferroni Post-Hoc test were used to compare the extraoral gothic arch tracing values and Orthopantomogram values and axiographic tracing values on right side and left side of the subjects. Results: A statistically significant correlation was observed between the extraoral Gothic arch tracing technique and the panoramic radiographic technique on right (r=0.047, p-value 0.04) and left sides (r=0.55, p-value 0.01) of the subjects. The axiographic tracing showed lower values when compared with gothic arch tracing technique and the panoramic radiographic technique. (95%CI of difference was -0.49 lower). Significant differences were obtained on comparison between all three techniques on right (p-value<0.001) and left sides.(p-value 0.008). On pairwise comparison of right sides between Extraoral gothic arch Tracing and Axiographic tracing (p-value<0.001) and between axiographic tracing and Orthopantomographic tracing (p-value<0.001), were significant, while pairwise comparison on left side between Orthopantomogram and Axiographic tracings (p-value 0.01) was significant. Conclusion: The panoramic radiographic images can be used as an alternative method to that of conventional gothic arch tracing technique to obtain the condylar guidance values. The values obtained using axiographic tracings method was comparatively lower. Thus, the values obtained from axiographic technique should be used with caution or the values needs to be compared to gold standard techniques to further analyse the accuracy of the values that can be used as a valuable aid in setting the condylar guidance in semi-adjustable articulators.

On Some Relations Linking Exponential and Geometrical Record Random Variables

Various record achievements are recorded in a number of areas of human activity. In this case, some discretization of the obtained observation results repeatedly occurs with varying accuracy (up to a second, up to a meter, and up to a thousand individuals). Using exponential and geometric distributions as an example, we show how such a transition from continuous to discrete probability distributions changes the number of record values in the corresponding sequences of random variables.

Разработка системы низкопрофильного дефлектометра комбинированных систем сканирующей зондовой и оптической микроскопии

A system of a low-profile SPM-deflectometer (SPM - scanning probe microscopy) which makes it possible to increase the aperture of the supplied objectives to the currently record value NA = 0.75 has been developed, manufactured and tested. The introduction of such a system will significantly improve the performance of optical techniques for combined SPM / optical microspectroscopy systems.

On estimation of stress-strength reliability using lower record values from odd generalized exponential: Exponential distribution

This research paper aims to find the estimated values closest to the true values of the reliability function under lower record values, and to know how to obtain these estimated values using point estimation methods or interval estimation methods. This helps researchers later in obtaining values of the reliability function in theory and then applying them to reality which makes it easier for the researcher to access the missing data for long periods such as weather. We evaluated the stress-strength model of reliability based on point and interval estimation for reliability under lower records by using Odd Generalize Exponential-Exponential distribution (OGEE) which has an important role in the lifetime of data. After that, we compared the estimated values of reliability with the real values of it. We analyzed the data obtained by the simulation method and the real data in order to reach certain results. The Numerical results for estimated values of reliability supported with graphical illustrations. The results of both simulated data and real data gave us the same coverage.

Childlessness among women of reproductive age in Serbia from a demographic perspective

The social, economic, and cultural changes that have taken place in Europe in the past few decades in the field of fertility have been accompanied by an increase in permanent childlessness. The childlessness level among women born in 1968 is 12% in Serbia, slightly below the European average (14%). The aim of this paper is to explore in more detail the level of childlessness in Serbia and the characteristics of women aged 15-49 without live births. Changes in childlessness over a 60-year period (1961-2020) by five-year age groups were analysed. The basic characteristics of childless women of reproductive age by education, marital status, and age were observed from 1991 to 2011. The paper is based on census and vital statistics data. The authors introduce two new indicators of childlessness: the general childlessness rate (GChR) as the share of women without live births in the total female population aged 15-49, and the age-specific childlessness rate (ASChR) as the percentage of childless women by age. Changes in cumulative fertility rates by age were less influenced by the reproductive behaviour of mothers and much more by an increase in the proportion of childless women. The general childlessness rate until 1991 was relatively stable in Serbia. Since then, it has increased intensely (from 30.1% in 1991 to 41.6% in 2011, and 43.4% in 2020). The increase in childlessness is largely a consequence of the postponement of first births, but also of the increase in permanent childlessness among women aged 45-49. The postponement of first births has occured in all age groups and the ASChR has increased across the board. In Serbia, in 2020, the ASChR reached record values for all five-year age groups (36.5% for women aged 30-34, 21.4% for ages 35-39), as did the level of permanent childlessness (13.8% for ages 45-49). The paper also analyses childlessness by education and marital status. According to census data (1991, 2002, and 2011), the general childlessness rate is lowest among women without any formal education and those who haven?t completed primary school, and highest among women with a primary education. Childlessness rates are particularly high among women in their thirties and forties. The influence of marital status on the level of childlessness was also confirmed. The GChR of single women was at least 10 times higher than the value for ever married women. The GChR ranged from 96% to 89% for single women and invariably slightly above 8% for ever married women. The results of direct standardization showed the greater importance of the changes that occurred between 1991 and 2011 by education and marital status of women aged 15-49 on the childlessness level, as well as their completely opposite effects compared to those caused by the change in the age structure. The large impact of changes in marital structure also indicates the possibility of a certain influence on reducing childlessness in Serbia. As the decreasein marriage is not accompanied by a higherprevalence of stable extramarital unions, it?s possible that the creation of more favourable circumstances for an independent life for young people and for forming a union could contribute to reducing the postponement of childbearing, and thus reducing childlessness during and at the end of the reproductive age. This is especially important considering that family and children are highly valued in Serbia. It should be noted that the high and growing shares of women without children in the 30-34 and 35-39 age groups limit the possibilities of reducing permanent childlessness, particularly in the near future.

On generalizations of the optimal choice problem

The article is dedicated to some generalizations of the classical optimal choice problem (the fastidious bride problem, the secretary problem). Let there be a sequence of n identically distributed random variables on the interval [0, 1]. Getting consistently observed values of these variables, we should stop at some moment on one of them, accepting it as the initial point for counting upper or lower record values. In the optimal choice problem and its generalizations, it is needed to make the correct choice of the initial point of counting records, in order to guess the place of the last record (the classical optimal choice problem) or to maximize the expected sum of upper and/or lower record values or the expected total number of upper and/or lower records, obtained by this procedure. A review of results on the uniform distribution of the random variables and some new results concerning the exponential distribution are presented.

On some relations which tie exponential and geometrical record random variables

Different record achievements are fixed in many domains of the human activities. Very often this process happens with some rate of discretization (up to seconds, up to meters or up to thousands of individuals) of the observed results. On the examples of exponential and geometrical distributions it is shown how such type of the transition from continuous to discrete distributions can vary the numbers of the record values in the corresponding sequences of the random variables.

A Log-Dagum Weibull Distribution: Properties and Characterization

This article proposes a new family of continuous distributions generated from a log dagum random variable (named Log-Dagum Weibull Distribution) on the basis of T-X family technique. mathematical and statistical properties including survival function, hazard and reverse hazard function, Rth moments, L-moments, incomplete rth moments, quantile points, Order Statistics, Bonferroni and Lorenz curves as well as entropy measures for this class of distributions are presented also LDW distribution characterized by truncated moments order statistics and upper record values. Simulation study of the proposed family of distribution has been derived. The model parameters are obtained by the method of maximum likelihood estimation. We illustrate the performance of the proposed new family of distributions by means of four real data sets and the data sets show the new family of distributions is more appropriate as compared to Exponentiated exponential distribution (EED), Weibull distribution (WD), Gamma distribution (GD), NEED Nadarajah Exponentiated exponential distribution and Lomax distribution (LD). Moreover, perfection of competing models is also tested via the Kolmogrov-Simnorov (K S), the Anderson Darling (A*) and the Cramer-von Misses (W*). The measures of goodness of fit including the Akaike information criterion (AIC), consistent Akaike information criterion (CAIC), Bayesian information criterion (BIC), Hannan-Quinn information criterion (HQIC) are computed to compare the fitted models.

Estimation of R for geometric distribution under lower record values

In this paper, the estimation of the stress-strength model R=P(Y<X), based on lower record values is derived when both X and Y are independent and identical random variables with geometric distribution. Estimating R with maximum likelihood estimator and Bayes estimator with non-informative prior information based on mean square errors and LINIX loss functions for geometric distribution are obtained. The confidence intervals of R are constructed by using exact, bootstrap and Bayesian methods. Finally, different methods have been used for illustrative purpose by using simulation. The main results are obtained and introduced through a set of tables and figures with discussions.