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The North Atlantic Oscillation (NAO) is a large-scale climatic pattern that strongly influences the atmospheric circulation in the northern Hemisphere and by consequence the long-term variability of marine and terrestrial ecosystem over great part of northern Europe and western Mediterranean. In the Mediterranean, the effects of the NAO on vertebrates has been studied mainly on bird populations but was rarely analysed in ectothermic animals, and in particular in amphibians. In this study, we investigated the relationships between winter, spring and summer NAO indexes and the long-term population dynamics of the plethodontid salamander Speleomantes strinatii. This terrestrial salamander was monitored inside an artificial cave in NW Italy for 24 consecutive years. The relationships between seasonal NAO indexes and the salamander dynamics were assessed by cross-correlation function (CCF) analysis, after prewhitening the time series by autoregressive moving average statistical modelling. Results of CCF analyses indicated that the salamander abundance varied in relation to the one-year ahead winter NAO (P = 0.018), while no relationships were found with spring and summer indexes. These results strengthen some previous findings that suggested a high sensitivity of temperate terrestrial amphibians to wintertime climatic conditions.

Рассмотрена возможность использования нестационарного стохастического процесса как математической модели посуточного потребления электрической энергии, а также сделан прогноз потребления электроэнергии отдельным регионом на протяжении одного месяца. С помощью регрессионного анализа определены доверительные интервалы для индивидуальных средних значений этого потребления. Полученные экспериментально значения подтверждают эффективность построенной математической модели. Possibility of the use of stochastic process in the capacity of mathematical model of 24-hour consumption of electric energyis examined, and the prognosis of consumption of electric power by separate region during one month is done. By a regressive analysis, confidence intervals were estimated for the individual mean values of this consumption. Obtained experimentally values confirm efficiency of the built mathematical model.

One of the most difficult issues of farm management is giving the answer to the question what to produce, i.e. making a decision about the sowing structure. Economic factors and principles play an important role in farmers' decisions about what to grow and on which areas. The purchase price of each crop, including soybeans, is an important but not the only factor of competitiveness. The authors of this paper started from the assumption that the level and trend of soybean purchase prices, among others, affect producers' decision on the growing area for this crop. Therefore, in order to scientifically confirm the initial assumption, an attempt has been made to examine (using appropriate statistical methods) the effect of average soybean purchase prices on the spread of this crop in Serbia.

Показана эффективность применения метода кросс-корреляционного качественного анализа для автоматического определения наличия элементов в пробе по её атомно-эмиссионному спектру. Метод основан на вычислении для каждого элемента Периодической таблицы функции кросс-корреляции зарегистрированного спектра и набора спектральных линий элемента из базы данных программы «Атом», предварительно преобразованных к специальному виду. Наличие элемента в пробе определяется по соотношению амплитуды корреляционного пика к шуму. Метод реализован в программе «Атом» и позволяет менее чем за секунду определить перечень элементов, присутствующих в пробе. This paper reports on the effectiveness of a method of qualitative cross-correlation analysis for the automatic determination of the presence of elements in a sample using its atomic emission spectrum. The method is based on the calculation of the cross-correlation function of the recorded spectrum and the set of specially transformed element spectral lines from the Atom database for each element of Mendeleev’s periodic table. The presence of an element in the sample is determined from the correlation peak-to-noise ratio. The method is implemented in the Atom software and allows the determination of the elements present in a sample in less than a second.

The Vajont Valley is mainly known for the catastrophic event of 9 October 1963, when a vast landslide occurred on the southern slope of the Vajont dam reservoir, causing a giant wave of water that flooded the Piave Valley below. Since then, many studies of the geological and geomechanical aspect of the landslide have been carried out, while very few studies have focused on the hydrogeological characteristics of this area. This paper proposes a hydrogeological conceptual model for the carbonate aquifers of the Vajont area, based on the continuous monitoring of two springs and environmental isotope investigations. Cross-correlation functions between time series and the VESPA index were used to delineate groundwater flow systems and the degree of karstification. This model has been confirmed by analyses of the amounts of stable isotopes, such as 18O and 3H, in precipitation and groundwater.

We present the measurement of the projected and redshift space 2-point correlation function (2pcf) of the new catalog of Chandra COSMOS-Legacy AGN at 2.9$\leq$z$\leq$5.5 ($\langle L_{bol} \rangle \sim$10$^{46}$ erg/s) using the generalized clustering estimator based on phot-z probability distribution functions (Pdfs) in addition to any available spec-z. We model the projected 2pcf estimated using $\pi_{max}$ = 200 h$^{-1}$ Mpc with the 2-halo term and we derive a bias at z$\sim$3.4 equal to b = 6.6$^{+0.60}_{-0.55}$, which corresponds to a typical mass of the hosting halos of log M$_h$ = 12.83$^{+0.12}_{-0.11}$ h$^{-1}$ M$_{\odot}$. A similar bias is derived using the redshift-space 2pcf, modelled including the typical phot-z error $\sigma_z$ = 0.052 of our sample at z$\geq$2.9. Once we integrate the projected 2pcf up to $\pi_{max}$ = 200 h$^{-1}$ Mpc, the bias of XMM and \textit{Chandra} COSMOS at z=2.8 used in Allevato et al. (2014) is consistent with our results at higher redshift. The results suggest only a slight increase of the bias factor of COSMOS AGN at z$\gtrsim$3 with the typical hosting halo mass of moderate luminosity AGN almost constant with redshift and equal to logM$_h$ = 12.92$^{+0.13}_{-0.18}$ at z=2.8 and log M$_h$ = 12.83$^{+0.12}_{-0.11}$ at z$\sim$3.4, respectively. The observed redshift evolution of the bias of COSMOS AGN implies that moderate luminosity AGN still inhabit group-sized halos at z$\gtrsim$3, but slightly less massive than observed in different independent studies using X-ray AGN at z$\leq2$., Comment: Accepted for publication in The Astrophysical Journal

Hypocretin/orexin signalling varies among sleep-wake behaviours, impacts upon cardiovascular autonomic control and is impaired in patients with narcolepsy with cataplexy (NC). However, evidence concerning disturbed cardiovascular autonomic control in NC patients is contrasting, and limited mainly to waking behaviour. We thus investigated whether control of cardiovascular variability is altered in NC patients during wakefulness preceding sleep, light (1-2) and deep (3-4) stages of non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Polysomnographic recordings and finger blood pressure measurements were performed on nine drug-free male NC patients and nine matched healthy control subjects during spontaneous sleep-wake behaviour in a standardized laboratory environment. Indices of autonomic function were computed based on spontaneous fluctuations of systolic blood pressure (SBP) and heart period (HP). During wakefulness before sleep, NC patients showed significant decreases in indices of vagal HP modulation, cardiac baroreflex sensitivity and amplitude of central autonomic (feed-forward) cardiac control compared with control subjects. During NREM sleep, the negative correlation between HP and subsequent SBP values was greater in NC patients than in control subjects, suggesting a greater contribution of central autonomic commands to cardiac control. Collectively, these results provide preliminary evidence that autonomic control of cardiac variability by baroreflex and central autonomic (feed-forward) mechanisms is altered in NC patients during spontaneous sleep-wake behaviour, and particularly during wakefulness before sleep.

The performance, efficiency and lifetime of modern combustion engines significantly depend on the quality of the engine lubricants. However, contaminants, such as gasoline, moisture, coolant and wear particles, reduce the life of engine mechanical components and lubricant quality. Therefore, direct and indirect measurements of engine lubricant properties, such as physical-mechanical, electro-magnetic, chemical and optical properties, are intensively utilized in engine condition monitoring systems and sensors developed within the last decade. Such sensors for the measurement of engine lubricant properties can be used to detect a functional limit of the in-use lubricant, increase drain interval and reduce the environmental impact. This paper proposes two new methodologies for the quantitative and qualitative analysis of the presence of contaminants in the engine lubricants. The methodologies are based on optical analysis of the distortion effect when an object image is obtained through a thin random optical medium (e.g. engine lubricant). The novelty of the proposed methodologies is in the introduction of an object with a known periodic shape behind a thin film of the contaminated lubricant. In this case, an acquired image represents a combined lubricant-object optical appearance, where an a priori known periodic structure of the object is distorted by a contaminated lubricant. In the object shape-based optical analysis, several parameters of an acquired optical image, such as the gray scale intensity of lubricant and object, shape width at object and lubricant levels, object relative intensity and width non-uniformity coefficient are newly proposed. Variations in the contaminant concentration and use of different contaminants lead to the changes of these parameters measured on-line. In the statistical optical analysis methodology, statistical auto- and cross-characteristics (e.g. auto- and cross-correlation functions, auto- and cross-spectrums, transfer function, coherence function, etc) are used for the analysis of combined object-lubricant images. Both proposed methodologies utilize the comparison of measured parameters and calculated object shape-based and statistical characteristics for fresh and contaminated lubricants. Developed methodologies are verified experimentally showing an ability to distinguish lubricant with 0%, 3%, 7% and 10% water and coolant contamination. This proves the potential applicability of the developed methodologies for on-line measurement, monitoring and control of the engine lubricant condition. © 2012 IOP Publishing Ltd.

На основі теорії збурення матриць отримано критерій вибору об’єму експериментальних досліджень. Для реалізації такого вибору необхідно знати кореляційні функції параметрів, що характеризують технічний стан промислових об’єктів. Наведено методику отримання таких кореляційних функцій, і на конкретному прикладі показано, яким чином визначається необхідний об’єм інформації для розв’язання задач контролю технічного стану газоперекачувальних агрегатів., На основании теории возмущения матриц получен критерий выбора объема экспериментальных исследований. Для реализации такого выбора необходимо знать корреляционные функции параметров, характеризующие техническое состояние промышленных объектов. Приведена методика получения таких корреляционных функций, и на конкретном примере показано, каким образом определяется необходимый объем информации для решения задач контроля технического состояния газоперекачивающих агрегатов., In the article according to the basis of theory matrices investigation the criterion of volume choice of experimental researches has been gained. For realization of such choice it is necessary to know the crosscorrelation functions of parameters which characterize the technical state of industrial objects. In the article the cross-correlation functions methods are discussed, and practically shown the way of setting necessary informationvolume for tasks management connected with gas disposal machines technical control.

This thesis aims at investigating experimentally, analytically and numerically, the consequences of hydrodynamic variations and oscillations with high temporal variability in partially saturated porous media. The problems investigated in this work involve “free surfaces” both outside and inside the porous media, the free surface being defined as the “atmospheric” water pressure isosurface (Pwater = Patm). The laboratory experiments studied in this work are, respectively: Lateral imbibition in a dry sand box with significant capillary effects; Transmission of oscillations of the free surface through a vertical sand box placed in a small wave canal (IMFT, Toulouse); Dynamics of free surface oscillations and wave propagation in a large wave canal (HYDRALAB, Barcelona), partially covered with sand, with measurements of both open water and groundwater levels, and of sand topography (erosion / deposition). For theoretical studies, we have developed linearized analytical solutions. Here is a sample problem that was treated analytically in this work: The linearized equation of Dupuit-Boussinesq (DB) for transient free surface flow, assuming horizontal flow and instantaneous wetting/drainage of the unsaturated zone: forced oscillations, wave transmission and dissipation through a rectangular sandbox. We also developed a weakly nonlinear solution of the Dupuit-Boussinesq equation to study the sudden imbibition (temporal monitoring of the wetting front). We have studied the different types of transient flow problems related to the experiments cited above by numerical simulation. In particular, we have simulated unsaturated or partially saturated transient flows in vertical cross-section, using a computer code (BIGFLOW 3D) which solves a generalized version of Richards’ equation. Thus, using the Richards / BIGFLOW 3D model, we have studied numerically the experiment of unsaturated imbibition in a dry sand (IMFT sandbox), and then, with the same model, we have also studied the partially saturated wave propagation experiment in the large Barcelona wave canal (HYDRALAB laboratory), focusing on the sloping sandy beach, with coupling between the micro-porous zone (sand) and the “macro-porous” zone (open water). To interpret the results of the latter experiment and compare them to simulations, we use several methods of signal analyzis and signal processing, such as: Fourier analysis, discrete multi-resolution wavelets (Daubechies), auto and cross-correlation functions. These methods are combined with pre-filtering methods to estimate trends and residuals (moving averages; discrete wavelet analyses). This signal analyzis has allowed us to interpret and quantify water propagation phenomena through a sandy beach. To sum up, different modeling approaches, combined with model calibration procedures, were applied to transient nonlinear coupled flow problems. These approaches have allowed us to reproduce globally the water content distributions and water level propagation in the different configurations studied in this work.

Date of Conference: 9-11 April 2009 Conference Name: IEEE 17th Signal Processing and Communications Applications Conference, SIU 2009 In this study, the relation between Total Electron Content (TEC) estimates obtained from GPS and the earthquakes is examined. Five earthquakes between 2003-2008 occured in Japan with different properties and China earthquake in May 2008 are chosen for the purpose. The 15-days period before and after the registered earthquakes are considered for the basis of this investigation. Also the TEC in computed for each GPS station for the time periods including Ionosphere quiet and disturbed days not without any serious earthquake in the region. For the statistical analysis, the cross correlation function (CC) which is used in the literature before, and the Kullback-Leibler Divergence (KLD) with L2-Norm (L2N) methods which are used for the first time in this context, are applied to the data sets. The computed values for CC, KLD and L2N are compared for both between different GPS stations where available and between consecutive days for the time periods in the data set. With CC analysis, the anomalies existed in the earthquake time intervals are also observed for the quiet days data set. For the earthquakes with scale larger than 6, the possibilities of generating an alarm signal is more likely with a future detailed comperative study of the estimated TEC nearby GPS station estimates in space and time.

La función de correlación cruzada muestral (FCCM) ha sido empleada para estudiar la fortaleza y la dirección de la relación lineal entre dos procesos estocásticos conjuntamente estacionarios. Rosales (2004) y Castaño (2005) muestran que dicha función, calculada entre el proceso estacionario y los residuales de un modelo preliminar estimado, puede ser empleada como un diagnóstico adicional en la identificación de un modelo apropiado ARMA(p,q) para este proceso. El propósito de este trabajo es mostrar que la FCCM entre los residuales de un modelo preliminar, aunque no sea correcto, y la serie de tiempo estacionaria, contiene información relevante del modelo adecuado y, por tanto, puede ser usado como un diagnóstico adicional en la formulación y construcción de modelos ARMA (Autoregressive-Moving Average). El procedimiento propuesto se ilustra con series reales y simuladas. The sample cross-correlation function (SCCF) has been used to study the strength and direction of the linear relation between two jointly stationary stochastic processes. Rosales (2004) and Castaño (2005) show that the cross-correlation function between a stationary process and the residuals of an estimated preliminary model can be used as an additional diagnostic tool, for the identification of an appropriate ARMA(p,q) model, for the generating process of the series. The purpose of this article is to show that the FCCM between a series and the residual of a preliminary model to describe it, not necessarily correct, contains relevant information of the correct model and for this reason it can be used as a diagnostic tool for the construction of ARMA models. The procedure is ilustrated with real and simulated series.

RESUMEN: La función de correlación cruzada muestral (FCCM) ha sido empleada para estudiar la fortaleza y la dirección de la relación lineal entre dos procesos estocásticos conjuntamente estacionarios. Rosales (2004) y Castaño (2005) muestran que dicha función, calculada entre el proceso estacionario y los residuales de un modelo preliminar estimado, puede ser empleada como un diagnóstico adicional en la identificación de un modelo apropiado ARMA(p, q) para este proceso. El propósito de este trabajo es mostrar que la FCCM entre los residuales de un modelo preliminar, aunque no sea correcto, y la serie de tiempo estacionaria, contiene información relevante del modelo adecuado y, por tanto, puede ser usado como un diagnóstico adicional en la formulación y construcción de modelos ARMA (Autoregressive-Moving Average). El procedimiento propuesto se ilustra con series reales y simuladas. ABSTRACT: The sample cross-correlation function (SCCF) has been used to study the strength and direction of the linear relation between two jointly stationary stochastic processes. Rosales (2004) and Castaño (2005) show that the cross-correlation function between a stationary process and the residuals of an estimated preliminary model can be used as an additional diagnostic tool, for the identification of an appropriate ARMA(p, q) model, for the generating process of the series. The purpose of this article is to show that the FCCM between a series and the residual of a preliminary model to describe it, not necessarily correct, contains relevant information of the correct model and for this reason it can be used as a diagnostic tool for the construction of ARMA models. The procedure is ilustrated with real and simulated series.

We propose a new method for estimating common factors of multiple time series. One distinctive feature of the new approach is that it is applicable to some nonstationary time series. The unobservable, nonstationary factors are identified by expanding the white noise space step by step, thereby solving a high-dimensional optimization problem by several low-dimensional sub-problems. Asymptotic properties of the estimation are investigated. The proposed methodology is illustrated with both simulated and real datasets. Copyright 2008, Oxford University Press.

Doutoramento em Matemática Aplicada à Economia e Gestão Tradicionalmente, a identificação de um modelo de função transferência bivariado é realizada através da função de correlação cruzada amostral entre as séries temporais input e output. No entanto, a prática tem mostrado que aquela função, como instrumento de identificação, apresenta um apreciável grau de subjectividade na especificação das ordens r e s, associadas aos polinómios output e input, respectivamente. Com base no estabelecimento de estimadores dos mínimos quadrados iterados consistentes, é introduzida uma generalização do conceito de função de autocorrelação estendida amostral e é proposta uma metodologia de identificação dos modelos de função transferência bivariados. Um exemplo prático e um estudo de simulação são apresentados, ilustrando as potencialidades do procedimento proposto.

The large field of view required in Earth observation interferometric radiometers does not enable the use of a variable delay to compensate for different transit times, as in radioastronomy. A technique is presented to characterise the influence of a channels frequency response automatically in the shape of the cross-correlation function.