Investigation on the Effect of Probability Distribution on the Dynamic Response of Liquefiable Soils

This study investigated the effect of different probabilistic distributions (Lognormal, Gamma, and Beta) to characterize the spatial variability of shear modulus on the soil liquefiable response. The parameter sensitivity analysis included the coefficient of variation and scale of fluctuation of soil shear modulus. The results revealed that the distribution type had no significant influence on the liquefication zone. In particular, the estimation with Beta distribution is the worst scenario. It illuminated that the estimation with Beta distribution can provide a conservative design if site investigation is absent.

CALCULATION OF CLIMATE LOADS DESIGN VALUES ACCORDING TO THE PROBABILITY MODEL OF ANNUAL MAXIMUM SERIES

The aim of this work is to improve a method for determining the characteristic values of climatic loads according to a probabilistic model of the annual maxima sequence, by choosing a rational type of generalized extreme value distribution law. An analysis is provided regarding the suitability of using four types of distributions for describing a data collection of maximum values of climatic loads. Using example data from the meteorological stations of Ukraine, it is found that for coefficients of variation smaller than 0.85–1.0, it is advisable to use the double exponential Gumbel distribution (generalized extreme value distribution type-I), and at higher values of the coefficient of variation, it is advisable to use the Weibull distribution (generalized extreme value distribution type-III). Recommendations are provided for considering the accuracy in the estimations of the characteristic values of loads according to the probabilistic model for the annual maximum value series.

Surfing on the world stage: a narrative review of acute and overuse injuries and preventative measures for the competitive and recreational surfer

Surfing has rapidly grown in popularity as the sport made its debut at the Tokyo 2020 Olympic Games. Surfing injuries are becoming more relevant with the globalisation and increasing risks of the sport, but despite this, little is known about surfing injuries or prevention strategies in either the competitive or recreational surfer. Prior research demonstrates that surfers are injured at a frequency of 0.74–1.79 injuries per 1000 hours of surfing. We reviewed the literature for the incidence, anatomical distribution, type and underlying mechanism of acute and overuse injuries, and discuss current preventative measures. This review finds that skin injuries represent the highest proportion of total injuries. Acute injuries most frequently affect the head, neck and face, followed by the lower limbs. Being struck by one’s own board is the most common mechanism of injury. Non-contact acute ligament injuries have increased as surfing manoeuvres have become more acrobatic and overuse musculoskeletal injuries are highly correlated with paddling. However, there is a paucity of research for surfing injuries, and studies on overuse musculoskeletal injuries and prevention are disproportionally under-represented. Most of the prior studies are limited by small sample sizes, poor data collection methodology and geographical constraints. Further research is needed to establish preventative measures for both acute and overuse surfing injuries and to ensure the increasing popularity of surfing is met with an improved understanding of sport risks and safety. Specifically, we recommend research be prioritised regarding the efficacy of training programmes to prevent surfing-related overuse musculoskeletal injuries.

Probabilistic approach in solving an optimization problem with application to in physical and technical systems

The article considers some optimization models with a nonlinear objective function and constraints in the form of equalities and inequalities. The model is considered in two forms – deterministic and stochastic, which allows it to be used to solve various optimization problems in physical and technical systems. The presented stochastic model is based on the inclusion of stochastic parameters into the well-known Cobb-Douglas function. The influence of stochastic variables on the optimal value of the objective function, depending on their distribution type, is analyzed.

Spatial distribution evolution and accessibility of A-level scenic spots in Guangdong Province from the perspective of quantitative geography

As a typical representative of tourism resources, the spatial distribution of A-level scenic spots has a profound impact on the layout of tourism industry. Scenic spot accessibility is also important for the development of tourism. However, the relationship of regional accessibility and spatial distribution of A-level scenic spots are understudied. The study used quantitative geography and geographic information system spatial analysis methods and analyzed the evolution of spatial distribution and regional accessibility of A-level scenic spots in Guangdong Province from 2001 to 2020. The results present the following: 1. Agglomeration distribution is the main distribution type of A-level scenic spots in Guangdong Province, and the spatial distribution is unbalanced. 2. From 2001 to 2020, the spatial distribution of A-level scenic spots in 21 prefecture-level cities of Guangdong Province has gradually developed from "wide gap" to "relatively reasonable." 3. Distribution density of A-level scenic spots in Guangdong Province has evolved into the main core area of high density. 4. Center of the gravity of A-level scenic spots in Guangdong Province developed from east to west during 2002–2007 and moved to the east after 2007. 5. Accessibility between A-level scenic spots and tourist source areas in Guangdong Province is good, with an evident aggregation phenomenon. This study reveals the spatial distribution evolution law and regional accessibility of A-level scenic spots, which is conducive to healthy, sustainable, and stable development of tourism in Guangdong Province.

Analysis of the error distribution density convergence with its orthogonal decomposition in navigation measurements

Modern trends towards the expansion of online services lead to the need to determine the location of customers, who may also be on a moving object (vessel or aircraft, others vehicle – hereinafter the “Vehicle”). This task is of particular relevance in the fields of medicine – when organizing video conferencing for diagnosis and/or remote rehabilitation, e.g., for post-infarction and post-stroke patients using wireless devices, in education – when organizing distance learning and when taking exams online, etc. For the analysis of statistical materials of the accuracy of determining the location of a moving object, the Gaussian normal distribution is usually used. However, if the histogram of the sample has “heavier tails”, the determination of latitude and longitude’s error according to Gaussian function is not correct and requires an alternative approach. To describe the random errors of navigation measurements, mixed laws of a probability distribution of two types can be used: the first type is the generalized Cauchy distribution, the second type is the Pearson distribution, type VII. This paper has shown that it’s possible obtaining the decomposition of the error distribution density using orthogonal Hermite polynomials, without having its analytical expression. Our numerical results show that the approximation of the distribution function using the Gram-Charlier series of type A makes it possible to apply the orthogonal decomposition to describe the density of errors in navigation measurements. To compare the curves of density and its orthogonal decomposition, the density values were calculated. The research results showed that the normalized density and its orthogonal decomposition practically coincide.

Finite Element Model for Free Vibration Analyses of FG-CNT Reinforced Composite Beams using Refined Shear Deformation Theories

The present article deals with the free vibration of functionally graded carbon nanotube reinforced composite (FG-CNTRC) beams employing various refined deformation theories and validates the accuracy and feasibility of these proposed theories. The theories involved are the first order shear deformation theory (FSDT) and other refined theories involving additional higher order terms. Carbon nanotubes (CNTs) are assumed to be oriented along the axis of the beam. Uniform and three types of different functionally graded (FG) distributions of CNTs through the thickness of the beam are considered. The rule of mixture is used to describe the effective material properties of the beams. The governing equations are derived using Hamilton’s principle and solved using the finite element method (FEM). A FEM code is compiled in MATLAB considering a C 0 finite element. The influences of different key parameters such as CNT volume fraction, distribution type of CNTs, boundary conditions and slenderness ratio on the natural frequencies of FG-CNTRC beams are investigated. It can be concluded that the above-mentioned parameters have significant influence on the free vibration of the beam and the accuracy of the proposed refined theories is good.

Nonparametric extrapolation of extreme quantiles: a comparison study

The extrapolation of quantiles beyond or below the largest or smallest observation plays an important role in hydrological practice, design of hydraulic structures, water resources management, or risk assessment. Traditionally, extreme quantiles are obtained using parametric methods that require to make an a priori assumption about the distribution that generated the data. This approach has several limitations mainly when applied to the tails of the distribution. Semiparametric or nonparametric methods, on the other hand, allow more flexibility and they may overcome the problems of the parametric approach. Therefore, we present here a comparison between three selected semi/nonparametric methods, namely the methods of Hutson (Stat and Comput, 12(4):331–338, 2002) and Scholz (Nonparametric tail extrapolation. Tech. Rep. ISSTECH-95-014, Boeing Information and Support Services, Seattle, WA, United States of America, 1995) and kernel density estimation. While the first and third methods have already applications in hydrology, Scholz (Nonparametric tail extrapolation. Tech. Rep. ISSTECH-95-014, Boeing Information and Support Services, Seattle, WA, United States of America, 1995) is proposed in this context for the first time. After describing the methods and their applications in hydrology, we compare their performance for different sample lengths and return periods. We use synthetic samples extracted from four distributions whose maxima belong to the Gumbel, Weibull, and Fréchet domain of attraction. Then, the same methods are applied to a real precipitation dataset and compared with a parametric approach. Eventually, a detailed discussion of the results is presented to guide researchers in the choice of the most suitable method. None of the three methods, in fact, outperforms the others; performances, instead, vary greatly with distribution type, return period, and sample size.

Quantitative Distribution of English and Indonesian Motion Verbs and Its Typological Implications: A case study with the English and Indonesian versions of the Twilight novel

This paper investigates the quantitative distribution (type and token frequencies, and type-per-token ratio [TTR]) of motion verbs found in English and Indonesian versions of the novel Twilight (Meyer, 2005; Sari, 2008). The study is contextualized within two divergent views on the typological characteristics of Indonesian lexicalization patterns of motion events. One study (Son, 2009) suggests that Indonesian behaves like English, representing a satellite-framed pattern (i.e., lexicalizing Manner of motion in the main verb) while another study (Wienold, 1995) argues for the verb-framed nature of Indonesian (i.e., lexicalizing Path of motion in the main verb). We seek to offer a quantitative perspective to these two proposals. Our study shows that, compared to English, Indonesian has significantly higher number (i.e., types) and occurrences (i.e., tokens) of Path verbs (reflecting the verb-framed pattern). Moreover, the higher TTR value of Path verbs for Indonesian shows a greater lexical diversity in the inventory of Indonesian Path verbs compared to English. In contrast, the English Manner verbs are significantly higher in number and in token frequency than Indonesian (suggesting the satellite-framed pattern), and show greater lexical diversity given the higher TTR value. While these findings lean toward supporting the verb-framed pattern of Indonesian (Wienold, 1995), we caution with the limitation of our conclusion and offer suggestions for future study.