Search results for "Statistical"

Palvelunestohyökkäysten havainnointi ja torjuminen tilastollisilla menetelmillä

2015

Palvelunestohyökkäykset ovat ajankohtaisena ongelmana tärkeä tutkimuksen kohde. Palvelunestohyökkäysten torjumiseen tarvitaan menetelmiä, joilla palvelua kuormittava hyökkäysliikenne voidaan erottaa tavallisesta verkkoliikenteestä. Tämän tutkimuksen tavoitteena on perehtyä palvelunestohyökkäysten toimintaan ja selvittää, mitä tilastollisia torjumismenetelmiä hyökkäysten torjumiseen käytetään. Tutkimuksessa selvitettiin palvelunestohyökkäysten yleiset pääpiirteet ja luokiteltiin hyökkäykset kahteen pääluokkaan. Lisäksi tutkimuksessa tunnistettiin neljä eri tilastollista torjumismenetelmää. Palvelunestohyökkäysten torjuminen on haasteellista, eikä yleiskäyttöistä torjumismenetelmää ole kehite…

Female reproductive factors are associated with objectively measured physical activity in middle-aged women

2017

Physical activity improves health and may delay the onset of several chronic diseases. For women in particular, the rate of these diseases accelerates at middle age; therefore it is important to identify the determinants of health-enhancing physical activity during midlife in this population. In this study, we focused on determinants that are unique to the female sex, such as childbearing and menopause. The main objective was to characterize the level of physical activity and differences between active and inactive middle-aged Finnish women. In addition, we examined the association of physical activity with female reproductive factors at midlife. The study population consisted of 647 women …

Assessing Statistical Anxiety Among Online and Traditional Students

2019

The purpose of this study was to determine whether scores on the Statistical Anxiety Scale (SAS) manifest in the same way for students in online and traditional statistics courses. Tests of measurement invariance indicated that invariance of the two-factor model of the SAS held at every level. Therefore, we compared the statistical anxiety of online and traditional students. Results indicated that online and traditional statistics students reported comparable levels of anxiety with slightly less anxiety in terms of seeking help for traditional students. We concluded that online instruction is a viable form of statistics education at least for undergraduate students enrolled in the social sc…

The ALICE experiment at the CERN LHC

2008

Journal of Instrumentation 3(08), S08002 (2008). doi:10.1088/1748-0221/3/08/S08002

Statistical sampling of water uses for leakage assessment via water budget

2012

Kinetics of phase separation in thin films: Lattice versus continuum models for solid binary mixtures

2008

A description of phase separation kinetics for solid binary (A,B) mixtures in thin film geometry based on the Kawasaki spin-exchange kinetic Ising model is presented in a discrete lattice molecular field formulation. It is shown that the model describes the interplay of wetting layer formation and lateral phase separation, which leads to a characteristic domain size $\ell(t)$ in the directions parallel to the confining walls that grows according to the Lifshitz-Slyozov $t^{1/3}$ law with time $t$ after the quench. Near the critical point of the model, the description is shown to be equivalent to the standard treatments based on Ginzburg-Landau models. Unlike the latter, the present treatmen…

Study of quantitative and qualitative variations in essential oils of Sicilian oregano biotypes

2015

Essential oil (EO) was extracted using hydrodistillation from samples of Origanum vulgare subspecies hirtum (Link) Ietswaart, gathered from the wild in various parts of Sicily, Italy; GC-FID and GC-MS analyses were subsequently performed. The aim of the study was to analyze the relationship between essential oil yields and the geographical distribution of oregano wild populations based on variations in environmental factors as collection sites. Moreover, the purpose was to group Origanum vulgare subspecies hirtum biotypes according to the chemical composition of the EO. The seven principal components in the EO was thymol (24.0–54.4%), γ-terpinene (9.8–30.5%), ρ-cymene (5.2–18.7%), α-terpine…

Univariate and multivariate properties of wind velocity time series

2009

We analyze the time series of hourly average wind speeds measured at 29 different stations located in Sicily, a region with a complex morphology. The investigation, performed from the univariate as well as the multivariate point of view, evidences that the statistical properties of wind at the single sites have features that are not reproduced by standard models and, thus, require specific modeling. Moreover, the synchronous evolution of wind velocity presents a cluster structure, obtained with different algorithms, that persists in the standard deviation too.

Statistical Approximation of Fourier Transform-IR Spectroscopy Data for Zinc White Pigment from Twentieth-Century Russian Paintings

2017

We present a statistical model for approximation of experimental Fourier transform-IR spectroscopy (FTIR) data for paint samples from paintings of different ages. The model utilizes random variations in some parameters (initial ageing rate, degree of change in ageing rate and time at which the change occurs). We determine the parameters characterizing variation in the paint composition and the storage conditions for the paintings. The numerical calculation is qualitatively consistent with the experimental data. In the proposed model, changes in the initial composition of the paint and the storage conditions make about the same contribution to the experimentally observed scatter in the data …

Dynamics of a harmonic oscillator coupled with a Glauber amplifier

2020

A system of a quantum harmonic oscillator bi-linearly coupled with a Glauber amplifier is analysed considering a time-dependent Hamiltonian model. The Hilbert space of this system may be exactly subdivided into invariant finite dimensional subspaces. Resorting to the Jordan-Schwinger map, the dynamical problem within each invariant subspace may be traced back to an effective SU(2) Hamiltonian model expressed in terms of spin variables only. This circumstance allows to analytically solve the dynamical problem and thus to study the exact dynamics of the oscillator-amplifier system under specific time-dependent scenarios. Peculiar physical effects are brought to light by comparing the dynamics…